DE102022200520A1 - parking lock device - Google Patents

Abstract

Described is a parking lock device (100; 101; 102) with a hydraulically or pneumatically controllable actuator (10) which has two pistons (11, 12) arranged axially displaceably on the same longitudinal axis (13) in a housing (16) of the actuator (10). The first piston (11) can be fixed mechanically at least in the first piston position by means of a locking device (14). An axial distance between the end faces (11a, 12b) of the pistons (11, 12) when both pistons (11, 12) are in the first piston positions is smaller than an axial distance between the end faces (11a, 12b) of the pistons ( 11, 12) when the first piston (11) is arranged in the first piston position and the second piston (12) in the second piston position. The second piston (12) is connected or operatively connected to a blocking element (6). An emergency actuating device (19) is provided, by means of which the second piston (12) can be displaced axially relative to the first piston (11) from the first piston position into the second piston position against the spring force of the spring (9). In addition, a stop device (20a; 20b; 20c; 20d) is provided, which holds the second piston (12) against the spring force of the spring (9) in its first piston position.

Description

The present invention relates to a parking lock device, in particular a parking lock device of an automatic transmission of a motor vehicle, with a hydraulically or pneumatically controllable actuator of the type defined in more detail in the preamble of patent claim 1.

Parking lock devices or parking locks are known from practice, by means of which motor vehicles are secured against rolling away. Such parking locks are provided, for example, in motor vehicles that have automatic or automated transmissions and each act mechanically on the output shafts of the transmission. Furthermore, drive axles of motor vehicles driven by electric motors are also assigned parking locks, which act mechanically on the two output-side half-shafts of such drive axles. Such parking locks usually each comprise at least one pawl pivotably mounted on a ratchet bolt, which positively engages and non-rotatably holds a parking lock wheel connected to the output of the transmission or the drive axle or disengages and releases from the parking lock wheel.

A parking lock is usually engaged mechanically by the spring force of an engagement spring. To disengage the parking lock, a hydraulic actuator is often provided, in which an end of a connecting rod that faces away from a locking element is articulated on a dial. The dial is operatively connected to a piston rod of a hydraulically actuable hydraulic piston disposed in a bore of the actuator housing. The parking lock is engaged by the preloaded engagement spring and transferred to the disengaged state when the hydraulic piston is axially displaced against the force of an engagement spring.

To actuate such a parking lock hydraulically, pressure is applied to the pressure chamber of the actuator formed by the lateral surface of the housing bore together with the hydraulic piston. The hydraulic piston is thereby axially displaced against the spring force of the insert spring into its piston position, which is assigned to the disengaged state of the parking lock (P_off). The compressive force of the hydraulic piston moves the blocking element out of its blocking position or out of engagement with the parking lock wheel.

In order to additionally lock the hydraulic piston of the actuator in the disengaged state of the parking lock, an electromagnet is usually provided, which is electrically energized in the disengaged operating state of the parking lock. A locking mechanism acting on the hydraulic piston is then actuated by the electromagnet. The latching mechanism is provided in order to prevent the parking lock from being engaged undesirably in the event of a pressure drop in the pressure chamber. Such a pressure drop can occur, for example, when a vehicle is out of service for a long time. Then the oil volume that is initially present in the pressure chamber can flow out of the pressure chamber while the vehicle is stationary due to gravity and due to existing leaks in the oil-carrying area of the parking lock and the pressure chamber can run empty.

To engage the parking lock, a solenoid valve is switched off again, which results in a so-called venting of the pressure chamber of the actuator. In addition, the mechanical locking of the hydraulic piston of the actuator is released. The hydraulic piston is then transferred into its switch position P_on (parking lock engaged) by the prestressed engagement spring. Here, the locking element is moved under the pawl. The blocking element then acts on the pawl in such a way that a tooth of this pawl engages in a corresponding tooth gap of a ratchet toothing of the parking lock wheel. The detent mechanism already provided for mechanically locking the actuator piston in the switch position P_off can be modified or adapted in such a way that the actuator piston can also be mechanically locked with it in the switch position P_on. In this case, one electromagnet is sufficient to lock the actuator piston either in the switch position P_off or in the switch position P_on. Those skilled in the art refer to such a parking lock actuation system as a hydraulically actuatable parking lock actuator with a bistable piston lock.

A device for actuating a parking lock of a transmission is, for example, from DE 10 2017 218 748 A1 famous. An insertion spring is provided for engaging the parking lock, the spring force of which acts on a shift lever in the direction in which the parking lock is engaged. The shift lever acts on a locking element of the parking lock via a connecting rod and the locking element acts on the pawl of the parking lock. To disengage the parking lock, a hydraulically controllable actuator is provided, the compressive force of which acts on the shift lever in the disengagement direction of the parking lock. In order to be able to disengage the parking lock manually if necessary, the parking lock also includes an emergency release device that can be brought into an operative connection with the shift lever.

In addition, the actuator of DE 10 2017 218 748 A1 two on the same longitudinal axis axially displaceable in an actuator housing arranged piston and arranged in the actuator housing electromagnetically actuated locking device. The first piston can be hydraulically pressurized to disengage the parking lock and, when pressurized, displaces the second piston in the axial direction against the spring force of the insert spring. The second piston is mechanically connected to the shift lever in such a way that an axial movement of the second piston causes the shift lever to pivot and pivoting of the shift lever results in an axial movement of the second piston.

The locking device can be actuated by an electromagnet. It mechanically locks the first piston either in a piston position associated with the engaged state of the parking lock or in a piston position associated with the disengaged state of the parking lock when the electromagnet is de-energized. The electromagnet must be energized to release the detent in the respective piston position. This structural design makes it possible for the second piston to be displaced axially by the shift lever when the emergency release device is actuated, without the first piston leaving its latched piston position, which is associated with the engaged state of the parking lock.

In contrast to the type of actuation described above, actuation systems that work inversely, in which the parking lock is engaged hydraulically and disengaged mechanically by spring force, are also known.

Usually, the pressure medium is supplied to the pressure chamber of a parking lock actuator and this pressure chamber is vented via a control valve or several hydraulically interacting control valves of an electrohydraulic control unit of a transmission or an electric motor-driven drive axle mentioned at the outset. Such an electrohydraulic control device is supplied with hydraulic fluid by an oil pump. The oil pump can be driven by a motor that is provided to drive the transmission, or by an electric machine that is provided to drive the drive axle, or by a separate electric motor.

However, there is a problem if the second piston is transferred from its second piston position to its first piston position by the spring without braking and then hits the first piston with a large impulse, which is dependent, among other things, on the spring rate of the spring, and is braked by it. In this way, the service life of the parking lock device can be adversely affected.

Unbraked spring-side displacement of the second piston from its second piston position in the direction of its first piston position can occur, for example, after an emergency actuation of the parking lock by the emergency release device. During such an emergency operation, the second piston is moved away from its first piston position by the first piston against the spring force of the spring, which acts on the second piston in the direction of the first piston, in order to engage or disengage the parking lock, depending on the design of the parking lock device. The first piston is held in its first piston position by the locking device.

If the emergency release device is deactivated, the second piston is spontaneously pushed in the direction of the first piston by the acting spring and then hits the first piston unbraked.

A high impulse is also introduced into the first piston when the first piston is released by the locking device in its second piston position and at the same time the pressure chamber is essentially vented. This is the case because the spring then moves both pistons together axially in the direction of their first piston positions without a significant force being applied to the pistons, which acts on the piston in the opposite direction to the spring force of the spring. If, on the other hand, the pressure chamber is filled with pressure medium, the pressure medium is pushed out of the pressure chamber when the pistons are adjusted in the direction of the first piston positions, as a result of which the resetting of the pistons is damped.

However, permanent filling of the pressure chamber with pressure medium can only be guaranteed with a great deal of design effort, which increases production costs. In order to be able to permanently ensure that the pressure chamber is filled with pressure medium without complex sealing measures, the pressure chamber could be connected to a pressure medium reservoir and arranged below a filling level of the pressure medium reservoir when the pressure chamber is pressurized hydraulically. However, such an arrangement of the parking lock is not always possible due to the limited space available in a vehicle.

Proceeding from this, the invention is based on the object of providing a structurally simple and cost-effective parking lock device which is characterized by a long service life.

This problem is solved by a parking lock device with the features of patent claim 1 . Other inventive outputs Designs and advantages emerge from the dependent claims.

The invention is based on a parking lock device, in particular a parking lock device of an automatic transmission of a vehicle, with a hydraulically or pneumatically controllable actuator. The actuator comprises two pistons arranged to be axially displaceable on the same longitudinal axis in a housing of the actuator. The first piston can be acted upon by pressure medium in order to actuate the parking lock. When pressure is applied to the first piston, it displaces the second piston axially against the spring force of a spring from a first piston position, in which the parking lock occupies a first switching position, into a second piston position, in which the parking lock occupies a second switching position. The first piston is also transferred from a first piston position to a second piston position. At least during the displacement of the second piston by the first piston, the two pistons bear against one another in the region of axial end faces facing one another. The first piston can be fixed mechanically at least in the first piston position by means of a locking device.

If the first switching position of the parking lock defines the disengaged state of the parking lock, the second switching position of the parking lock defines the engaged state of the parking lock. On the other hand, if the first switching position of the parking lock defines the engaged state of the parking lock, the second switching position of the parking lock defines the disengaged state of the parking lock.

An axial distance between the faces of the pistons when both pistons are in the first piston positions is smaller than an axial distance between the faces of the pistons when the first piston is in the first piston position and the second piston is in the second piston position. In addition, the second piston is connected or operatively connected to a blocking element.

In addition, an emergency release device is provided, by means of which the second piston can be adjusted axially relative to the first piston from the first piston position into the second piston position against the spring force of the spring.

The parking lock device can be designed such that it can be actuated manually via the emergency release device, for example, without the first piston of the actuator leaving its mechanically fixed piston position when the parking lock is actuated manually.

According to the invention, a stop device is provided which holds the second piston in its first piston position against the spring force of the spring.

This ensures that the second piston is moved by the spring into its first piston position, for example after manual actuation via the emergency actuation device, and is braked by the stop device and held in the first piston position. This is a simple way to prevent the second piston from hitting the end face of the first piston with its end face and introducing an undesirably high impulse into the first piston, which impairs the function of the parking lock device and thus also the service life of the parking lock device.

Such an emergency actuation device is usually designed as an emergency release device in order to be able to move the motor vehicle, which has previously been fixed by means of the parking lock device, if necessary in the event of a defect in the actuator control. In the case of such an emergency release device, the parking lock is in the disengaged state in its first switching position, but in the engaged state in its second switching position.

Alternatively, the emergency actuation device can be embodied as an emergency locking device in order to be able to fix the motor vehicle by means of the parking lock device if necessary in the event of a defect in the actuator control. In the case of such an emergency locking device, the parking lock is in the engaged state in its first switching position, but in the disengaged state in its second switching position.

The anchorage device is structurally simple to implement since, depending on the design of the anchorage device, only tolerance chains with a small number of individual tolerances need to be taken into account. This significantly simplifies a manufacturing process, with the result that the parking lock device according to the invention can also be produced inexpensively.

The second piston can have a piston rod and a shoulder of the stop device can be firmly connected to the piston rod. In the first piston position of the second piston, the shoulder can then bear against a housing-side stop surface of the stop device and can support the second piston in a structurally simple manner against the spring force of the spring in the first piston position of the second piston on the stop surface.

In a further development of the parking lock device according to the invention, the active compound comprises a shift lever between the second piston and the locking element of the parking lock. The shift lever is in operative connection with the second piston and the locking element and is pivoted by the second piston during an axial displacement of the second piston, as a result of which the locking element is actuated to the desired extent.

In one embodiment of the parking lock device according to the invention, which is compact in terms of installation space and can be integrated into existing parking lock systems with little effort, the shift lever rests in the first piston position of the second piston on a stop surface of the stop device fixed to the housing and holds the second piston in its first position against the spring force of the spring piston position.

The emergency actuation device can have a preferably manually actuated actuating lever, by means of which the shift lever can be moved in a structurally simple manner against the spring force of the spring, which acts on the second piston, from a first pivoting position, which is assigned to the first piston position of the second piston, into a second Pan position can be transferred. The second pivoting position of the shift lever is assigned to the second piston position of the second piston. In the first pivoting position, the adjusting lever can bear against a stop surface of the stop device on the housing side and can hold the second piston in the first piston position via the switching lever against the spring force of the spring.

Such an embodiment of the parking lock device according to the invention requires little additional installation space compared to known parking locks and can be integrated into existing parking lock systems with little structural effort.

The housing-side stop surface of the stop device can be provided with little effort in the area of the housing of the actuator.

For example, if the housing of the actuator is made of plastic, it is possible to produce the stop surface by overmolding an additional area on the housing of the actuator. The additional area of the housing can be designed to withstand the load by means of a so-called injected metal insert.

Furthermore, the stop surface of the stop device can also be provided in the area of the metallic housing of known parking lock systems by means of a suitable casting process with little effort.

An axial end of the first piston, which faces away from the second piston, is spaced in the axial direction from the housing of the actuator in a development of the parking lock device according to the invention when the first piston is in the first piston position. This ensures in a simple manner that no undesirably large impulse is introduced from the second piston into the housing of the actuator via the first piston.

In a further embodiment of the parking lock device according to the invention, an end position damping unit is provided between the pistons. By means of the end position damping unit, an actuating speed of the second piston can be reduced before the second piston reaches the first piston position, and a load on the actuator can thus be limited.

In a structurally simple manner, the end position damping unit can use a fluid to damp the adjustment movement of the second piston in the direction of the stop device and also of the first piston. Provision can be made for the second piston to push out a fluid from a storage space during its axial movement in the direction of its first piston position, thereby slowing down its actuating speed. As an alternative to this or in combination with this, the actuating movement of the second piston in the direction of its first piston position can also suck a fluid from a fluid reservoir, preferably via an orifice, with the suction of the fluid creating a negative pressure, which causes the actuating movement of the second piston in the direction dampens the first piston position of the second piston or counteracts the spring force of the spring.

In an embodiment of the parking lock device that is favorable in terms of installation space, the locking device can comprise an electromagnet and locking elements that can be actuated by its armature rod.

If the first piston, which can be acted upon by pressure medium, is mechanically fixed by means of the locking device, provision can be made for the locking elements to be supported axially directly on a support surface of the first piston against the spring force of the spring.

Furthermore, it can also be provided that the locking elements are supported on a support surface of a sleeve, which in turn is mounted on the first piston in an axially displaceable manner and then, when the first piston is mechanically fixed by means of the locking device, on a contact shoulder of the first piston axially against the spring force of the spring.

Preferably, the locking device mechanically fixes the first piston of the actuator, which can be pressurized, in the respective existing piston position when the electromagnet of the locking device is not electrically energized. In this case, the electromagnet must be electrically energized to release the piston fixation in the respective piston position, so that the first piston of the actuator can only change its piston position when the electromagnet is electrically energized.

As an alternative to this, however, it can also be provided that the locking device then mechanically fixes the first piston of the actuator in the respective existing piston position when the electromagnet of the locking device is electrically energized. The electromagnet must be switched off electrically in order to release the piston fixation in the respective piston position, so that the first piston of the actuator can only change its piston position when the electromagnet is not electrically energized.

When locking or axially fixing the first piston of the actuator, the locking device preferably acts directly on this first piston. Alternatively, however, it can also be provided that the locking device acts indirectly or indirectly on this first piston when locking the first piston of the actuator, for example via a piston rod connected to this first piston.

As already indicated, the actuator is suitable as an actuating element for parking lock devices of the most varied—in principle any—construction. For example, it can be provided that the compressive force of the actuator acts in the disengagement direction of the parking lock, whereas the spring force of the spring acts in the engagement direction of the parking lock. As an alternative to this, it can be provided, for example, that the compressive force of the actuator acts in the engagement direction of the parking lock device, whereas the spring force of the spring acts in the disengagement direction of the parking lock device.

The use of the parking lock device according to the invention is also not limited to a specific application. For example, the parking lock device according to the invention can be assigned both to a transmission of a motor vehicle and to a drive axle of a motor vehicle driven by an electric motor.

• 1 eine vereinfachte schematische Schnittdarstellung einer Parksperrenvorrichtung mit einem Aktuator in ausgelegtem Betriebszustand;
• 2 die Parksperrenvorrichtung gemäß 1 in eingelegtem Betriebszustand in einer 1 entsprechenden Darstellung;
• 3 eine schematisierte Teillängsschnittansicht einer Weiterbildung der Parksperrenvorrichtung gemäß 1 mit einer Endlagendämpfungseinheit;
• 4a eine vergrößerte Ansicht eines in 3 näher gekennzeichneten Bereiches IV der Parksperrenvorrichtung gemäß 3, der die Endlagendämpfungseinheit umfasst, wobei die Endlagendämpfungseinheit in einem nicht aktiven Betriebszustand dargestellt ist;
• 4b eine 4a entsprechende Darstellung des Bereiches IV und die Endlagendämpfungseinheit in aktivem Betriebszustand, in dem sie eine Stellbewegung eines zweiten Kolbens des Aktuators in Richtung eines ersten Kolbens des Aktuators verzögert;
• 5 eine dreidimensionale Teilunteransicht eines Getriebes und eines weiteren Ausführungsbeispiels der erfindungsgemäßen Parksperrenvorrichtung; und
• 6 eine Längsschnittansicht des Aktuators der Parksperrenvorrichtung gemäß 5.

The invention is explained in more detail below with reference to the attached figures. Show in it:

• 1 a simplified schematic sectional view of a parking lock device with an actuator in the designed operating state;
• 2 the parking lock device according to 1 in inserted operating condition in a 1 corresponding representation;
• 3 a schematic partial longitudinal sectional view of a further development of the parking lock device 1 with a cushioning unit;
• 4a an enlarged view of an in 3 More specifically marked area IV of the parking lock device according to 3 , which comprises the end position damping unit, wherein the end position damping unit is shown in a non-active operating state;
• 4b one 4a Corresponding representation of area IV and the end position damping unit in the active operating state in which it delays an adjustment movement of a second piston of the actuator in the direction of a first piston of the actuator;
• 5 a three-dimensional partial bottom view of a transmission and another embodiment of the parking lock device according to the invention; and
• 6 a longitudinal sectional view of the actuator of the parking lock device according to FIG 5 .

1 and 2 each show a simplified schematic sectional view of a parking lock device 100 with a hydraulically actuable actuator 10 for actuating the parking lock device 100. The parking lock device 100 in 1 shown in the disengaged operating state or in the “parking lock disengaged” switching position, which is identified by the reference symbol P_aus. In contrast, shows 2 the parking lock device 100 in 1 shown in the engaged operating state or in the switching position "parking lock engaged", which is identified by the reference symbol P_ein.

The parking lock device 100 includes a pawl 2 pivotably mounted on a pawl bolt 3. A ratchet tooth 2a of the pawl 2 engages in or out of a tooth gap 1a of a locking toothing of a parking lock wheel 1, depending on the switching position of the parking lock device 100. The parking lock wheel 1 is non-rotatably connected to a transmission shaft of a motor vehicle transmission, not shown here. In addition, the parking lock device 100 includes a locking element 6 which is arranged on a connecting rod 5 . The connecting rod 5 is connected to a shift lever 4 . The lock Element 6 is spring-loaded via a spring element 7 and is clamped between the pawl 2 and a guide plate 8 fixed to the transmission housing in the locked state, ie in the engaged switching state of the parking lock device 100 . This prevents the ratchet tooth 2a from being pushed out of the corresponding tooth gap 1a of the parking lock wheel 1 . The blocking element 6 is designed here, for example, as a blocking cone.

The shift lever 4 is also rotatably mounted on the latch bolt 3, so that the latch bolt longitudinal axis 3a, the pawl pivot axis and the shift lever axis of rotation are identical. The end of the connecting rod 5 facing away from the blocking element 6 is connected in an articulated manner to the shift lever 4 . In order to be able to engage and disengage parking lock device 100, shift lever 4 has a driver 4a, which is connected to actuator 10 that can be actuated hydraulically or pneumatically. The switching position of the parking lock device 100 can be predetermined by means of the actuator 10 . In the present exemplary embodiment, parking lock device 100 is disengaged by means of a compressive force of actuator 10 and engaged by means of a spring force of a spring 9 . The spring 9 can therefore also be referred to as an “insert spring” here. When the parking lock device 100 is disengaged, the compressive force of the actuator 10 therefore works here against the spring force of the spring 9.

Actuator 10 has two separate pistons 11 and 12 that are axially displaceable on the same longitudinal axis 13 in a housing 16 of actuator 10 , of which only first piston 11 can be hydraulically pressurized to disengage parking lock device 100 . When pressure is applied, the first piston 11 moves the second piston 12 in the axial direction against the spring force of the spring 9. In the present case, the housing 16 of the actuator 10 has two housing parts 161 and 162 which are firmly connected to one another. The parking lock device 100 can thus be installed with little effort.

The spring 9 is designed as a compression spring which is clamped axially between the second piston 12 and the first housing part 161 of the actuator housing 16 and thereby concentrically encloses a piston rod 12a of the second piston 12 . The piston rod 12a of the second piston 12 is guided in a longitudinally displaceable manner in the region of a bore 161a in the first housing part 161 and is also partially arranged outside of the housing 16 . The second piston 12 is mechanically connected to the shift lever 4 via a pin 12c. The pin 12c is inserted into the piston rod 12a outside of the first housing part 161 and engages in the driver 4a of the shift lever 4 . An axial movement of the second piston 12 thus causes the shift lever 4 to rotate about the shift lever axis of rotation 3a. Conversely, twisting the shift lever 4 about its axis of rotation 3a causes an axial movement of the second piston 12.

In addition, the actuator 10 has a so-called bistable locking device 14 for its first piston 11 , which is arranged, for example, inside the first housing part 161 of the actuator housing 16 - in this case, for example, centrally inside the first piston 11 . The locking device 14 can be actuated electromagnetically by an electromagnet 14a, which is arranged in the second housing part 162 of the actuator housing 16 . The locking device 14 fixes the first piston 11 mechanically in the axial direction either in a first piston position, which is assigned to the engaged state P_in of the parking lock device 100, or in a second piston position, which is assigned to the disengaged state P_off of the parking lock device 100 when the electromagnet 14a is not energized. In order to be able to adjust the first piston 11 axially in each case, the electromagnet 14a must therefore be energized in order to cancel the blocking effect of the locking device 14 .

An armature rod 14b of the electromagnet 14a acts on locking elements 14c, which are embodied here as balls, for example. In the locked state of the first piston 11, these locking elements 14c are supported in the 1 and 2 manner shown axially and radially on a support surface 11c of the first piston 11 from.

The actuator concept with the two pistons 11, 12 enables a manually operable emergency release device 19 despite the presence of a bistable latching of the first piston 11 of the actuator 10, which can be pressurized electrical activation of the actuator 10 can be mechanically transferred from the switch position P_on to the switch position P_off. For this purpose, the emergency release device 19 can be brought into an operative connection mechanically with the shift lever 4 . In the exemplary embodiment of the parking lock device 100 shown here, the emergency release device 19 comprises an outer lever 19a arranged on the outside of the transmission housing of the automatic transmission and an inner lever 19b arranged in the interior of the transmission housing, which is connected non-rotatably to this outer lever 19a via a bolt 19d penetrating the transmission housing. The inner lever 19b has a leg 19c which, in the event of an actuation of the emergency release device 19, acts mechanically directly on a leg 4b of the shift lever 4, causing the shift lever 4 to move about its axis of rotation 3a in order to disengage the parking lock device 100 intended direction of rotation twisted. If the emergency release device 19 is actuated, the second piston 12 of the actuator 10 is axially displaced by the shift lever 4 without the first piston 11 of the actuator 10 leaving its piston position corresponding to the engaged state P_in of the parking lock device 100 .

In order to be able to hydraulically design the parking lock device 100 in normal operation with a secured supply of the actuator 10, the actuator 10 has a pressure chamber 16a, which can be pressurized with pressure medium or hydraulic fluid via a pressure connection, not shown in detail. In the switching position P_on of the parking lock device 100, this pressure chamber 16a is vented and the two pistons 11 and 12 of the actuator 10 are in their first end positions or first axial piston positions, in which the pistons 11 and 12 are adjusted in the direction of the electromagnet 14a. The first piston 11 is mechanically fixed by the locking device 14 against an axial movement - so locked - and the electromagnet 14a is switched off.

In order to be able to disengage parking lock device 100 starting from switching position P_on, electromagnet 14a must first be energized. The blocking effect of the locking device 14 is deactivated by energizing the electromagnet 14a. At about the same time, the previously unpressurized pressure chamber 16a of the actuator 10 is filled with pressure medium. The consequence of this is that the first piston 11 is axially displaced in the direction of the second piston 12 by the compressive force which is then applied to the first piston 11 . The first piston 11 also displaces the second piston 12 in the axial direction against the spring force of the spring 9 out of its first piston position as soon as the first piston 11 rests with an end face 11a on an end face 12b of the second piston 12 . The pistons 11 and 12 are moved until they reach their predefined second end positions or second axial piston positions.

The axial movement of the second piston 12 is converted via the shift lever 4 into a rotary movement of the shift lever 4 about the axis of rotation 3a, which causes the parking lock device 100 to be disengaged. The rotational movement of the shift lever 4 is transmitted to the locking element 6 via the connecting rod 5, as a result of which the locking element 6 is mechanically pulled out of its locking position. This means that the pawl 2 pivots and the ratchet tooth 2a is guided out of engagement with the tooth gap 1a of the ratchet teeth of the parking lock wheel 1 . The parking lock device 100 is now in the switching state P_off.

In the designed operating state P_out of the parking lock device 100, the electromagnet 14a is de-energized. This activates the locking device 14 and mechanically locks the first piston 11 in its second piston position. This mechanical locking of first piston 11 secures parking lock device 100 against unintentional engagement of parking lock device 100 . For example, if the pressure level in the pressure chamber 16a is not sufficient for the situation or if there is a defect in the pressure supply to the pressure chamber 16a of the actuator 10, an undesired engagement of the parking lock device 100 is prevented.

If, starting from the switching state P_off of parking lock device 100, in which parking lock device 100 is designed, parking lock device 100 is to be engaged in normal operation with a secured supply of actuator 10, pressure chamber 16a of actuator 10 must be vented. In addition, the blocking effect of the locking device 14 must be canceled by energizing the electromagnet 14a with electricity so that the locking device 14 releases the first piston 11 .

If pressure medium is pushed out of the pressure chamber 16a and the pressure chamber 16a can be vented and the electromagnet 14a is energized, the first piston 11 and the second piston 12 can be moved axially by the spring 9 in the direction of the electromagnet 14a. Then the pistons 11 and 12 are transferred into their first piston positions and the shift lever 4 is rotated about the axis of rotation 3a in the direction of rotation provided for engaging the parking lock. This rotational movement of the shift lever 4 is transmitted via the connecting rod 5 to the locking element 6 and from the locking element 6 to the pawl 2 .

If the ratchet tooth 2a hits a tooth gap 1a of the ratchet teeth of the parking lock wheel 1 and is not rejected again by the outer diameter of the ratchet teeth because the parking pawl wheel 1 is rotating too fast, the ratchet tooth 2a positively engages in the ratchet teeth in the area of one of the tooth gaps 1a and sets the parking lock wheel 1. The parking lock device 100 is now in the switching state P_on. When the operating state P_in of the parking lock device 100 is engaged, the electromagnet 14a is de-energized again, so that the locking device 14 mechanically locks the first piston 11 in its end position facing the electromagnet 14a or in its first piston position.

A failure of the activation of the actuator 10 in the disengaged state P_out of the parking lock device 100 does not pose a problem since the parking lock is still in its switching position as a result given mechanical locking of the first piston 11 can not change automatically.

If the activation of the actuator 10 fails in the engaged state P_in of the parking lock device 100 and the locking device 14 is still activated, the parking lock device 100 can no longer be configured to the usual extent. The emergency release device 19 is provided for such functional failures, by means of which the parking lock device 100 can also be manually disengaged without the above-described actuation of the actuator 10 .

Manual actuation of the emergency release device 19 initiates pivoting of the non-rotatably connected levers 19a and 19b of the emergency release device 19. During this pivoting, the leg 19c of the inner lever 19a presses on the leg 4b of the shift lever. This causes the shift lever 4 to rotate about the axis of rotation 3a in the direction of rotation provided for disengaging the parking lock device 100 . As a result, the blocking element 6 is pulled out of its blocking position via the connecting rod 5, as in normal operation of the parking lock device 100, and the parking lock device 100 is disengaged.

Since the shift lever 4 is also mechanically connected to the piston rod 12a, actuating the emergency release device 19 also causes the second piston 12 to be displaced axially into its second piston position. The first piston 11 of the actuator 10, which is still locked in the axial direction by the activated locking device 14, remains in its first piston position. The parking lock device 100 is now in the so-called emergency unlocked operating state.

If the actuation of the emergency release device 19 ends in the emergency-released operating state of the parking lock device 100, the two levers 19a and 19b of the emergency release device 19, which are connected to one another in a rotationally fixed manner, pivot back into their initial position as a result of the restoring force of a torsion spring 19e provided here as an example. As a result, the second piston 12 is pushed by the spring 9 in the direction of its first piston position and the engagement of the parking lock device 100 is initiated.

A "regular" pivoting of the shift lever 4 in normal operation - i.e. with a fully functional actuator 10 - has no mechanical effect whatsoever on the inner lever 19b and the outer lever 19a of the emergency release device 19.

Taking into account the mode of operation of parking lock device 100 described in more detail above, there is both normal operation, during which actuator 10 can be actuated both hydraulically and electrically with the full range of functions, and when parking lock device 100 exits the emergency-unlocked operating state, in which parking lock device 100 is activated via the Emergency release device 19 is designed manually against the spring force of the spring 9, the possibility that the second piston 12 is transferred from the spring 9 essentially unbraked from its second piston position to its first piston position.

In normal operation of parking lock device 100, this is the case when pressure chamber 16a is not sufficiently filled with pressure medium and the blocking effect of locking device 14 is deactivated in the designed operating state of parking lock device 100 by energizing electromagnet 14a. Then the spring 9 transfers the two pistons 11 and 12 together unbraked from the second piston positions in the direction of the first piston positions.

If the actuation of the emergency release device 19 ends, the spring 9 guides the second piston 12 from its second piston position in the direction of its first position, without any significant force counteracting this actuating movement.

In order to prevent impermissible loads in the region of the actuator 10 as a result of the unbraked return movement of the second piston 12 in a structurally simple manner, the parking lock device 100 is designed with a stop device. In 1 and 2 different versions of the stop device are shown by way of example, which are each provided in different areas of the parking lock device 100 and are also designed differently and are identified in more detail under the reference symbols 20a, 20b, 20c, 20d.

The travel of the second piston 12 in the direction of the electromagnet 14a and the first piston 11 is limited by means of the stop devices 20a, 20b, 20c, 20d in such a way that the setting movement of the second piston 12 is stopped in the region of the stop device 20a, 20b, 20c, 20d and no pulse is introduced into the first piston 11 by the second piston 12 . This is achieved via the stop devices 20a, 20b, 20c, 20d, regardless of whether the second piston 12 in its first piston position rests with its end face 12b on the end face 11a of the first piston 11 or whether the two end faces 12b and 11a are in the first Piston positions of the pistons 11 and 12 are spaced apart from one another in the axial direction.

Depending on the particular application, parking lock device 100 is designed such that, in its first piston position, end face 12b of second piston 12 either rests against end face 11a of the first piston, or the two end faces 12b and 11a are spaced apart from one another in the axial direction. In any case, the design is such that an unbraked return of the second piston 12 from its second piston position to its first piston position does not introduce an impulse into the first piston 11, which is supported by the first piston 11 on the housing side or in the area of the electromagnet 14a got to. This ensures that in particular the functions of the locking device 14 and also of the electromagnet 14a are not impaired.

In addition, the first piston 11 can be positioned in its first piston position in the axial direction and designed with such an axial length that a further end face 11c of the first piston 11 facing the electromagnet 14a is axially separated from an end face 162a of the second housing part 162 of the housing 16, which faces the further end face 11c of the first piston 11, is spaced apart. In the event that the second piston 12 hits the first piston 11 without braking due to manufacturing tolerances, this prevents the impulse then applied to the first piston 11 in the area of the further end face 11c of the first piston 11 from spreading into the second Housing part 162 of the housing 16 is introduced and the operative connection between the two housing parts 161 and 162 is acted upon with it.

The stop device 20a has a shoulder 20a1, which is firmly connected to the piston rod 12a of the second piston 12 and which, in a structurally simple embodiment, is designed as a spring ring that is mounted immovably in the axial direction in a groove of the piston rod 12a of the second piston 12 . In the first piston position of the second piston 12, the step 20a1 rests against a housing-side stop surface 20a2 of the stop device 20a and supports the second piston 12 against the spring force of the spring 9 in the first piston position of the second piston 12 on the stop surface 20a2. The stop face 20a2 is provided in the area of an outside end face 161b of the first housing part 161 of the housing 16 of the actuator 10 .

As an alternative to this, the stop device 20b is provided in the area of the shift lever 4 . When the second piston 12 is in the first piston position, the shift lever 4 rests with a region 20b1 of its driver 4a on a housing-fixed stop surface 20b2 of the stop device 20B and thus holds the second piston 12 against the spring force of the spring 9 in its first piston position. The stop face 20b2 is an end face of a region that preferably extends in a finger-like manner away from the first housing part 161 of the housing 16 of the actuator 10 in the axial direction, which can be provided on housings of known parking lock systems with little structural effort.

A stop surface 20c2 of the stop device 20c is provided in the area of a housing of the transmission, on which the leg 4b of the shift lever 4 in the in 2 manner shown in more detail applied to hold the second piston 12 in its first piston position against the spring force of the spring 9.

In contrast to this, a stop surface 20d2 of the stop device 20d, which is also designed in the area of the transmission housing, interacts with a region 20d1 of the inner lever 19b of the emergency release device 19 in order to hold the second piston 12 against the spring force of the spring 9 acting on the second piston 12 in the to hold the first piston position. The stop device 20d limits both a pivoting angle of the inner lever 19b and a pivoting angle of the shift lever 4 in the pivoting direction that corresponds to an axial adjustment of the second piston 12 in the direction of the first piston position.

3 shows a greatly simplified representation of another parking lock device 101, which essentially has the same structural design as the parking lock device 100 and in a region IV includes an end position damping unit 30 in addition to one of the stop devices 20a to 20d. The end position damping unit 30 is described below with reference to FIG 4a and 4b described in more detail and is arranged radially inside the second piston 12 and is provided acting in the axial direction between the first piston 11 and the second piston 12 . With regard to the further functioning and the structural design of the parking lock device 101, reference is made to the above description in order to avoid repetition 1 and 2 referred.

The end position damping unit 30 comprises a piston element 30a which is arranged in a cylinder tube 30b so as to be axially longitudinally displaceable. The piston element 30a is in operative connection with the second piston 12 and is displaced by the second piston 12 in the axial direction in the cylinder tube 30b. 4a shows the piston element 30a in a first axial piston position, which the piston element 30a occupies when the second piston 12 is arranged in its second piston position in which the park locking device 101 has its designed operating state P_off.

The cylinder tube 30b, the piston element 30a and a cylinder cover 30c delimit a piston chamber 30d which is connected to the interior of the second piston 12 via a radial bore 30e and is preferably filled with air. The piston element 30a has a stepped design and rests with a diameter area 30a1 on an inner side 30b1 of the cylinder tube 30b. When the second piston 12 is displaced towards its first piston position, the piston element 30a is also displaced in the axial direction, the volume of the piston chamber 30d then being reduced and air being pushed out of the piston chamber 30d via the radial bore 30e.

Shortly before the second piston 12 reaches the first piston position, the piston element 30a with a further diameter area 30a2, the diameter of which is smaller than the diameter of the diameter area 30a1, enters a cylindrical inner area 30c1 of the cylinder cover 30c. The piston chamber 30d is then divided by the piston element 30a and the inner region 30c1 of the cylinder cover 30c into a first piston chamber region 30d1 and a second piston chamber region 30d2.

The first piston chamber area 30d1 is still connected to the environment of the second piston 12 via the radial bore 30e, and air continues to be expelled unhindered from the first piston chamber area 30d1 via the radial bore 30e. From the second piston chamber area 30d2, on the other hand, the air can only be routed in a very restricted manner via the gap between the outside of the diameter area 30a2 of the piston element 30a and the inside of the inner area 30c1 of the cylinder cover 30c into the first piston chamber area 30d1, as a result of which the pressure in the second Piston chamber area 30d2 increases and dampens the positioning speed of the second piston 12 in the direction of its first piston position.

In order not to influence the restoring behavior of the second piston 12 too much, the second piston chamber area 30d2 is also connected to the surroundings of the second piston 12 via a so-called throttle screw 30f, via which air from the second piston chamber area 30d2 can be discharged in a throttled manner. The actuating movement of the second piston 12 can thus be damped before the first piston position is reached, and the impulse that is to be absorbed by the stop device 20A, 20B, 20C or 20D is smaller than in the case of a parking lock device that is designed without the end position damping unit 30.

5 shows another parking lock unit 102, which has the same function as the parking lock device 100 and, in addition to the stop device 20C, is also designed with an end position damping unit 40, which is described in more detail below. The end position damping unit 40 differs structurally from the end position damping unit 30, but like the end position damping unit 30, before the second piston 12 reaches the first piston position, it also applies a damping force to the second piston 12, which counteracts the spring force of the spring 9.

For this purpose, the housing 16 of the actuator 10 has an in 6 shown and the interior of the housing 16 with a fluid reservoir connecting channel 40a is provided. The channel 40a is released when the second piston 12 is displaced in the direction of its first piston position and when the second piston 12 passes a defined axial position in the process. The axial adjustment of the second piston 12 in the housing 16 results in a negative pressure in the first housing part 161 . In order to compensate for this, fluid is sucked in from the fluid reservoir. This causes an actuating force which acts in the opposite direction to the spring force of the spring 9 on the second piston 12 and dampens the actuating movement of the second piston 12 in the direction of the first piston position. In order to be able to set this actuating force to a defined extent and to the respective application in a defined manner, a throttle device can be provided in channel 40a, which controls the suctioned volume flow and thus the actuating force acting against spring 9 .

Reference List

1

parking lock wheel

1a

Tooth gap of the locking teeth of the parking lock wheel

2

pawl

2a

ratchet tooth of the pawl

3

latch bolt

3a

latch bolt longitudinal axis; pawl pivot axis; Shift Lever Pivot

4

shifter

4a

Driver of the shift lever

4b

Leg of the shift lever

5

connecting rod

6

blocking element; locking cone

7

spring element of the locking element

8th

guide plate

9

Feather; insert spring

10

actuator

11

first piston of the actuator

11 a

face of the first piston

11b

further face of the first piston

11c

Support surface on the first piston for the locking elements

12

second piston of the actuator

12a

Piston rod of the second piston

12b

face of the second piston

12c

Pen

13

Longitudinal axis of the piston

14

Actuator locking device

14a

Electromagnet of the latching device

14b

Electromagnet armature rod

14c

locking element; Bullet

16

actuator housing

16a

pressure chamber of the actuator

161

first housing part of the housing of the actuator

161a

Bore of the first housing part 161

161b

outside face of the first housing part 161

162

second housing part of the housing of the actuator

162a

Face of the second housing part 162

19

emergency actuation device; emergency release device

19a

outside lever

19b

inside lever

19c

inner lever leg

19d

bolt

19e

Leg spring

20a

anchor device

20a1

Paragraph of the anchor device 20a

20a2

Stop surface of the stop device 20a

20b

anchor device

20b1

area of the driver

20b2

Stop surface of the stop device 20b

20c

anchor device

20c2

Stop surface of the stop device 20c

20d

anchor device

20d1

Inner Lever Area 19b

20d2

Stop surface of the stop device 20d

30

cushioning unit

30a

piston element

30a1, 30a2

Diameter range of the piston element

30b

cylinder barrel

30b1

inside of the cylinder tube

30c

cylinder cover

30c1

Interior of the cylinder cover

30d

piston space

30d1, 30d2

piston chamber area

30e

radial bore

30f

throttle screw

40

cushioning unit

40a

channel

100, 101, 102

parking lock device

P_off

designed state of the parking lock

p_a

engaged state of the parking lock

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017218748 A1 [0007, 0008]

Claims (13)

Parking lock device (100; 101; 102), in particular a parking lock device of an automatic transmission, with a hydraulically or pneumatically controllable actuator (10) which has two pistons (11 , 12), of which the first piston (11) can be pressurized to actuate the parking lock device and when pressure is applied, the second piston (12) moves axially against the spring force of a spring (9) from a first piston position, in which the parking lock device is in a first switching position is moved to a second piston position, in which the parking lock device is in a second switching position, with the first piston (11) also being transferred from a first piston position to a second piston position and the two pistons (11, 12) at least during the displacement of the second piston (12) by the first piston (11) in the range of mutually facing axial end faces (11a, 12B) abut one another, the first piston (11) being mechanically fixable at least in the first piston position by means of a locking device (14), an axial distance between the end faces (11a, 12b) of the pistons (11 , 12), when both pistons (11, 12) are in the first piston positions, is smaller than an axial distance between the end faces (11a, 12b) of the pistons (11, 12) when the first piston (11) is in the first piston position and the second piston (12) is arranged in the second piston position, the second piston (12) being connected or operatively connected to a blocking element (6), and an emergency actuating device (19) being provided, by means of which the second piston (12 ) against the spring force of the spring (9) can be adjusted axially with respect to the first piston (11) from the first piston position into the second piston position, characterized in that a stop device (20a; 20b; 20c; 20d) is provided, which holds the second piston (12) against the spring force of the spring (9) in its first piston position. Parking lock device after claim 1 , characterized in that the second piston (12) has a piston rod (12a) and a shoulder (20a1) of the stop device (20a) is firmly connected to the piston rod (12a), which in the first piston position of the second piston (12). a housing-side stop surface (20a2) of the stop device (20a) and supports the second piston (12) against the spring force of the spring (9) in the first piston position of the second piston (12) on the stop surface (20a2). Parking lock device after claim 1 or 2 , characterized in that the operative connection between the second piston (12) and the locking element (6) of the parking lock comprises a switching lever (4) which is in operative connection with the second piston (12) and the locking element (6) and which during a axial adjustment of the second piston (12) is pivoted by the second piston (12). Parking lock device after claim 3 , characterized in that the switching lever (4) in the first piston position of the second piston (12) bears against a stop surface (20c2) of the stop device (20c) fixed to the housing and the second piston (12) against the spring force of the spring (9) in its holds the first piston position. Parking lock device according to one of the preceding claims, characterized in that the emergency actuating device (19) has an actuating lever (19a, 19b) by means of which the shift lever (4) can be moved against the spring force of the spring (9) acting on the second piston (12) from a first pivoting position, which is assigned to the first piston position of the second piston (12), into a second pivoting position, which is assigned to the second piston position of the second piston (12), the adjusting lever (19a, 19b) being in the first pivoting position at one housing-side stop surface (20d2) of the stop device (20d) and holds the second piston (12) via the shift lever (4) against the spring force of the spring (9) in the first piston position. Parking lock device according to one of the preceding claims, characterized in that the housing-side stop surface (20a2) of the stop device (20a) is provided in the region of the housing (16) of the actuator (10). Parking lock device according to one of the preceding claims, characterized in that an axial end (11b) of the first piston (11), which faces away from the second piston (12), in the first piston position of the first piston (11) in the axial direction of the housing ( 16, 162a) of the actuator (10). Parking lock device according to one of the preceding claims, characterized in that an end position damping unit (30) is provided between the pistons (11, 12), by means of which an actuating speed of the second piston (12) can be reduced before the second piston (12) reaches the first piston position . Parking lock device according to one of the preceding claims, characterized in that the locking device (14) has an electromag net (14a) and by means of an armature rod (14b) of this electromagnet (14a) actuatable locking elements (14c). Parking lock device according to one of the preceding claims, characterized in that the locking device (14) mechanically fixes the first piston (11) in the respective piston position when the electromagnet (14a) of the locking device (14) is not electrically energized, so that the first Piston (11) can only change its piston position when the electromagnet (14a) is electrically energized. Parking lock device according to one of the preceding claims, characterized in that the locking device (14) mechanically fixes the first piston (11) in the respective existing piston position when the electromagnet (14a) of the locking device (14) is electrically energized, so that the first piston (10) can only change its piston position when the electromagnet (14a) is not electrically energized. Parking lock device according to one of Claims 1 until 11 , characterized in that the compressive force of the actuator (10) acts in the disengagement direction of the parking lock, whereas the spring force of the spring (9) acts in the engagement direction of the parking lock. Parking lock device according to one of Claims 1 until 11 , characterized in that the compressive force of the actuator (10) acts in the direction of engagement of the parking lock, whereas the spring force of the spring (9) acts in the direction of disengagement of the parking lock.

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