DE102017215877A1 - Variable valve lift device - Google Patents

Abstract

A variable valve lift device includes a cam that rotates in unison with a camshaft, a lever body that is in rolling contact with an end portion of the cam and performs a lever movement by receiving torque of the cam, two valves that operate in response to a lever movement of the lever body, a valve gap control means disposed at the other end portion of the lever body to simultaneously push the two valves through a main stroke and to control a gap of the valve, and an operating portion which is operated to a variable valve to selectively push one of which is located under the two valves to a sub-stroke, and at the other end portion of the lever body.

Description

Cross-reference (e) to related applications

The present application claims the priority of Korean Patent Application No. 10-2016-0167758 , filed on Dec. 9, 2016, the entire contents of which are incorporated herein by reference for all purposes.

Background of the invention

Field of the invention

The present invention relates to a variable valve lift device. More specifically, the present invention relates to a variable valve lift device capable of varying the profile of a valve to improve an efficiency of an engine.

Description of related art

Generally, an internal combustion engine receives fuel and air in a combustion chamber and generates power by burning the fuel and the air. Herein, an intake valve is operated by driving a camshaft, and air flows into the combustion chamber while the intake valve is opened. In addition, an exhaust valve is actuated by driving a camshaft, and air is discharged from the combustion chamber while the exhaust valve is opened.

Meanwhile, optimum operations of the intake valve or the exhaust valve become dependent on the rotational speed of the engine, that is, stroke and opening and closing timings of the valves are properly controlled depending on the rotational speed of the engine. A variable valve lift (VHL) device has been developed in which the valves are actuated for different strokes in response to a rotational speed of the engine to achieve optimum valve actuation. For example, there is a variable valve lift apparatus in which a plurality of cams for operating the valves are provided at a different stroke at the camshaft, respectively, and the cam actuating the valves is selected depending on a condition.

However, when the plurality of cams are provided to the camshaft, the structure for selecting a change of the cam to operate the intake valve or the exhaust valve may become complex, and interference between the elements of the structure may occur. However, in the case where the plurality of cams are respectively and independently operated to prevent the interference between the elements of the structure, an additional constituent member is required in each cam for actuating the cam, which may be increased in cost.

The information disclosed in this Background section is merely for enhancement of understanding of the general background of the invention and should not be construed as any form of concession or suggestion that this information constitutes prior art that is already known to one skilled in the art.

Short Summary

Various aspects of the present invention are directed to providing a variable valve lift (VHL) device having the advantages that the profile of a valve can be varied in response to the rotation of a cam using a simple construction.

The variable valve lift apparatus according to an exemplary embodiment of the present invention may include a cam that rotates in unison with a camshaft, a lever body that is in rolling contact with an end portion of the cam, and performs lever movement by receiving torque of the cam, two valves which are adapted to be actuated in response to a lever movement of the lever body, a valve gap control means which is formed at the other end portion of the lever body and is adapted to press the two valves simultaneously by means of a main lift and a gap of the valve and an operation portion adapted to selectively push a variable valve which is one of the two valves by means of a sub lift and which is located at the other end portion of the lever body.

A roller may be disposed at a portion where the lever body is in contact with the cam.

The actuating portion may include an actuator actuated by hydraulic pressure, a chamber that is a volume that selectively forms a high pressure in response to actuation of the actuator, a plunger that performs a rectilinear reciprocal motion which linearly reciprocates in response to the pressure change of an interior of the chamber, and a solenoid valve which is operated to selectively supply hydraulic pressure to the actuator.

The piston can selectively push the variable valve by means of the sub-stroke and a resilient one Section may be arranged at a lower end portion which presses the variable valve.

The sub-stroke of the variable valve may be a stroke that is smaller than the main stroke.

An elastic portion may be disposed at a lower end portion of the valve gap control means which simultaneously presses the two valves.

The variable valve lift device may further include a valve bridge connecting the two valves.

The lower end portion of the valve gap controller may push the valve bridge.

The variable valve may be arranged to be vertically movable on the valve bridge.

The variable valve lift device may further include a tappet disposed at an upper end portion of the variable valve on the valve bridge to realize an up and down movement of the variable valve.

The cam may have a base formed in an arcuate shape with a uniform radius and a circle center, the center of rotation of which forms the cam, a sub-lobe that engages the lever body from the time to wherein the opening of the variable valve is started until the closing of the variable valve is completed, press while the variable valve is operated by the sub-stroke, and a main tab which presses the lever body from the time when the opening of the second valve is started is completed by the main lift until the closing of the second valve is completed.

An outer diameter of the minor lobe may be larger than an outer diameter of the base, and an outer diameter of the main lobe may be larger than an outer diameter of the minor lobe.

The base and the main lobes may be formed at opposite sides to each other with respect to a rotation center of the cam, and the sidelobe is formed between the base and the main lobe.

The sidelobes may be formed on both sides with respect to a rotation center of the cam.

When the operating portion is not operated, the variable valve may not be pushed by the operating portion even if the slave lobe of the cam is in contact with the lever body.

When the solenoid valve is to be ON, with hydraulic pressure supplied to the chamber by operation of the actuator while the slave lobes of the cam are in contact with the lever body, the piston can be moved down and push the variable valve.

When the main lobe of the cam is in contact with the lever body, the piston may return to an original position thereof when the solenoid valve is OFF, and hydraulic pressure is released from the chamber by stopping the operation of the actuator.

The variable valve can be actuated by the sub-stroke during a suction stroke of an engine, which realizes an internal exhaust gas recirculation or recirculation.

The variable valve can be operated by the sub-stroke during a compression stroke of an engine, so that an engine brake is realized.

The timing of opening an exhaust port by the variable valve may be a center of top dead center.

The methods and apparatus of the present invention have other features and advantages that will be apparent or further explained in the accompanying figures provided herein and the following detailed description, which together serve to explain certain principles of the present invention ,

list of figures

• 1 FIG. 10 is a schematic diagram of a variable valve lift device according to an exemplary embodiment of the present invention. FIG.
• 2 FIG. 12 is a figure showing a shape of a cam according to an exemplary embodiment of the present invention. FIG.
• 3 . 4 and 5 FIG. 10 are operational diagrams of a variable valve lift apparatus according to an exemplary embodiment of the present invention. FIG.
• 6 and 7 FIG. 11 is graphs illustrating a valve profile in response to a variable valve lift device according to an exemplary embodiment of the present invention. FIG.

It should be understood that the accompanying drawings are not necessarily to scale and are a somewhat simplified representation of various features which illustrate the basic principles of the invention. The specific design features of the present invention, as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the specific intended application and use environment.

Reference numerals in the figures refer to the same or corresponding parts of the present invention through the various figures of the drawing.

Detailed description

Reference will now be made in detail to various embodiments of the present invention, examples which are shown in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments, it is to be understood that the present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments which may fall within the spirit and scope of the invention as defined by the accompanying claims.

1 FIG. 10 is a schematic diagram of a variable valve lift device according to an exemplary embodiment of the present invention. FIG.

As in 1 1, a variable valve lift device according to an exemplary embodiment of the present invention includes a lever body 10 , a lever rotation shaft 15 , a cam contact section 20 , a cam 25 , an operating section 30 , a solenoid valve 40 , a valve gap control device 50 , a valve 60 , a valve bridge 70 and a valve lifter 80 on.

The lever body 10 Performs a lever movement by receiving torque of a camshaft to the valve 60 to press. In addition, the cam 25 formed at the camshaft or arranged to a rotational movement of the camshaft in a lever movement of the lever body 10 transferred to. Herein can the valve 60 an intake valve or an exhaust valve of an engine. According to an exemplary embodiment of the present invention, the valve 60 is used as an exhaust valve, but is not limited thereto.

The lever rotation shaft 15 is a shaft having a cylindrical shape as a rotation center of a lever movement of the lever body 10 and is rotatably connected to the lever body 10 , In addition, the lever rotation shaft 15 arranged parallel to the camshaft to the lever body 10 to penetrate. Herein, an arrangement or provision of the camshaft is known to a person skilled in the art, so descriptions thereof are omitted.

The cam contact section 20 is at an end portion of the lever body 10 trained or arranged. In addition, the cam contact section is 20 with the cam 25 in rolling contact, to a rotational movement of the camshaft in a lever movement of the lever body 10 transferred to. Furthermore, the cam contact portion 20 be a roller with the lever body 10 is connected to rotate about a rotary shaft, which is parallel to the camshaft, and the lever body 10 arranged or formed.

The operating section 30 is at the other end portion of the lever body 10 arranged. In addition, the operating section 30 an actuator 32 , a chamber 34 , a piston 36 and a piston-elastic section 38 on.

The actuator 32 is actuated by hydraulic pressure. In addition, the actuator 32 mounted so that it is in the other end portion of the lever body 10 is introduced.

The chamber 34 is a volume in which high pressure is selectively formed depending on the operation of the actuator 32 ,

The piston 36 performs a straightforward reciprocation in response to the change in pressure in the chamber 34 , In addition, the piston 36 be arranged so that it is in the other end portion of the lever body 10 is introduced. Furthermore, the chamber 34 between the actuator 32 and the piston 36 be arranged.

The elastic piston section 38 is provided at the piston 36. In addition, the elastic piston section 38 at an opposite side of the chamber 34 in relation to the piston 36 arranged. In this regard, the opposite side is a lower end portion of the chamber 34 that's the valve 60 is facing. Meanwhile, the elastic piston portion 38 have a plastic or rubber material.

The solenoid valve is actuated to the actuator 32 to selectively supply hydraulic pressure. In addition, the solenoid valve 40 operated by a solenoid or solenoid which is electrically turned on or off. The magnet and the control thereof are known to a person skilled in the art, detailed descriptions thereof are thus omitted.

The valve gap controller 50 is for controlling a gap of the valve 60 set up. In addition, the valve gap control device 50 at another end portion of the lever body 10 arranged to move further from the lever rotation shaft 15 to be spaced in comparison with the operating section 30 , Furthermore, an elastic gap section or gap-elastic section 58 at a lower end portion of the valve gap control device 50 arranged and is the valve 60 facing. Meanwhile, the elastic gap portion 58 have a plastic or rubber material. Herein, the basic structure and function of the valve gap control means (lash adjuster) are known to those skilled in the art, and descriptions thereof are thus omitted.

The valve 60 has a variable valve 61 and a fastened valve 62 on, and the valve bridge 70 connects an upper end portion of the variable valve 61 with an upper end portion of the fixed valve 62 , That is, an engine employing the variable valve apparatus according to an exemplary embodiment of the present invention may be an engine having two exhaust valves arranged such that two exhaust valves execute the exhaust in one cylinder.

The variable valve 61 is arranged so that it is on the valve bridge 70 is movable up and down to be selectively operable by means of a sub-stroke in response to the operation of the operating portion 30 , Herein, the sub-stroke may be a low lift, in which the variable valve 61 is actuated to be independent with an actuation of the fixed valve 62 ,

The fixed valve 62 is at the valve bridge 70 attached to always be actuated by means of a main lift. Herein, the main stroke may be a normal stroke where the variable valve 61 together with the attached valve 62 is actuated by an identical stroke, while the attached valve 62 is pressed.

However, the normal stroke and the lower or low stroke are strokes of the valve 60 , which are predetermined depending on a design of a person skilled in the art, and a stroke duration of the opening of the valve 60 and a stroke width of the valve 60 due to the low lift are shorter than those of the normal hub. A stroke for actuating the variable valve 61 to be independent of the operation of the attached valve 62 however, are not limited to the lower and lower strokes, respectively, and may be changed depending on a design of a person skilled in the art.

The pestle 80 is at the upper end portion of the variable valve 61 arranged and is adapted to an upward and downward movement of the variable valve 61 at the valve bridge 70 to realize. In addition, the plunger 80 arranged so that he is in a pusher hole 75 is introduced, that at the valve bridge 70 is formed to penetrate the valve bridge 70. Herein, the basic structure and function of the plunger as a valve device having a cylindrical shape are known to those skilled in the art, detailed descriptions thereof are thus omitted.

2 FIG. 12 is a figure showing a shape of a cam according to an exemplary embodiment of the present invention. FIG.

As in 2 shown, the cam points 25 According to an exemplary embodiment of the present invention, a base 27 , a sidelobel 28 and a main lobe 29 on.

The base 27 is a base circle of an outer circumference of the cam 25 and is formed in an arc shape having a uniform radius and a circle center C representing the center of rotation (C).

The sidelobel 28 is a section of an outer circumference of the cam 25 pressing the cam contact section 20 is set, from the time at which the opening of the variable valve 61 occurs, which is selectively actuated by means of a sub-stroke in response to an actuation of the actuating portion 30 when closing the variable valve 61 ends depending on a rotation of the cam 25 ,

The main lobe 29 is a section of an outer circumference of the cam 25 pressing the cam contact section 20 is set up, from the moment when the valve opens 60 is started until when closing the valve 60 ends by means of a main lift in response to a rotation of the cam 25 , That is, an outer diameter of the minor lobe 28 is larger than an outside diameter of the base 27 and an outer diameter of the main lobe is larger than an outer diameter of the sidelobe 28 , In addition, the base 27 and the main tab 29 at opposite sides to each other with respect to a center of rotation (C) of the cam 25 trained, and the sidelobes 28 are relative to both sides a center of rotation (C) of the cam 25 between the base 27 and the main lobe 29 educated.

3 . 4 and 5 FIG. 10 are operational diagrams of a variable valve lift apparatus according to an exemplary embodiment of the present invention. FIG.

3 shows a state of non-operation of the operation portion 30 ,

As in 3 shown, the variable valve 61 when the operation section 30 is not operated, not operated by means of a sub-stroke, even if the sidelobes 28 of the cam 25 with the cam contact section 20 in contact. That is, when the operation section 30 is not actuated, is a state of the elastic piston portion 38 from the pestle 80 separated, and is maintained, even if the sidelobes 28 the cam 25 with the cam contact portion 20 in contact.

4 shows a state of the operation of the operating portion 30 ,

As in 4 shown, the variable valve 61 operated when the operating section 30 operated by a sub-stroke, during the sidelobe 28 of the cam 25 with the cam contact section 20 in contact. That is, when the solenoid valve 40 Is ON, with hydraulic pressure to the chamber 34 is supplied by means of an actuation of the actuator 32 while the sidelobes 28 of the cam 25 with the cam contact section 20 in contact, the piston becomes 36 moved downwards, wherein the elastic piston portion 38 an upper end portion of the plunger 80 suppressed. In 4 is a relative stroke size (a) of the variable valve 61 from the attached valve 62 with a "zero lift" state through arranged lines ("adjoint lines").

5 shows a state of positioning of the operating portion 30 in an original position thereof.

As in 5 shown, the piston returns 36 if the main lobe 29 of the cam 25 with the cam contact portion 20 in contact, in an original position thereof back when the solenoid valve 40 OFF is, taking hydraulic pressure from the chamber 34 by stopping the actuation of the actuator 32 is released. At the present time, the elastic gap section presses 58 the valve gap control device 50 the valve bridge 70 , and the variable valve 61 and the attached valve 62 are operated together by a main lift.

6 and 7 FIG. 11 is graphs showing a valve profile in response to a variable valve lift device according to an exemplary embodiment of the present invention. FIG.

In 6 and 7 For example, a lift profile of an intake valve (IL) is shown as a dot chain line, and a main lift profile (EL) of the valve 60 , which has been described as an exhaust valve according to an exemplary embodiment of the present invention, is shown as a fixed line, and a Nebenhubprofil the variable valve 61 , under the valve 60 , is shown as a dotted line.

As in 6 shown, the variable valve 61 be operated by a sub-stroke during an intake stroke of an engine after the operation of the variable valve 61 and the attached valve 62 by means of a main lift. In the present case, a section S1 is the operation of the variable valve 61 by means of a sub-stroke, a section S1 in which exhaust gas is recirculated to an engine (internal exhaust gas recirculation section S1). That is, if the variable valve 61 an exhaust port opens during an intake stroke, internal EGR is realized, which exhaust gas discharged through the exhaust port flows into a combustion chamber by negative pressure of the combustion chamber.

As in 7 shown, the variable valve 61 operated by a sub-stroke during a compression stroke of an engine, before the main lift operation of the variable valve 61 and the attached valve 62 , In the present case, a sub-stroke operation portion S2 of the variable valve 61 a motor brake section S2. That is, if the variable valve 61 the exhaust opening during an intake stroke during braking opens, the engine brake can be realized by releasing a compression of the combustion chamber. However, the time at which the variable valve 61 the exhaust port during an intake stroke when braked opens a top dead center (TDC) of a piston.

According to an exemplary embodiment of the present invention, efficiency of an engine may be maximized when one of two valves 60 , which are opened together by a main lift, is selectively opened by a secondary lift. In addition, the internal exhaust gas recirculation and the engine brake can be achieved depending on the operation of the valve 61 which is selectively opened by a sub-stroke.

To simplify the description and precise definitions in the accompanying claims are the terms "upper", "lower", "inner", "outer", "upper", "lower", "upward", "downward", "front", "rear", "back", "inner" , "Outward,""inward,""outward,""inner,""outer,""forward," and "reverse" are used to describe characteristics of the exemplary embodiments with reference to the location of such features as in the figures shown.

The foregoing description of specific exemplary embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the specific forms disclosed, and it is evident that various modifications and variations are possible in light of the above teachings. The exemplary embodiments have been chosen and described to explain certain principles of the invention and their practical application to enable one skilled in the art to model and use various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the claims attached hereto and by the equivalents.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• KR 1020160167758 [0001]

Claims (19)

Variable valve lift device, with: a cam adapted to rotate together with a camshaft; a lever body, which is in rolling contact with a first end portion of the cam and performs a lever movement by receiving torque of the cam; two valves, which are operated in response to the lever movement of the lever body; a valve gap control means disposed at a second end portion of the lever body for simultaneously urging the two valves around a main stroke and controlling a gap of the valves; and an operating portion operable to selectively push a variable valve, which is one of the two valves, by means of a sub-stroke, and disposed at the second end portion of the lever body. Variable valve lift device after Claim 1 in which a roller is disposed at a portion such that the lever body is in contact with the cam. Variable valve lift device after Claim 1 or 2 wherein the operating portion comprises: an actuator operable by hydraulic pressure; a chamber that is a volume that selectively generates a high pressure in response to actuation of the actuator; a piston performing a rectilinear reciprocation in response to a pressure change in an interior of the chamber; and a solenoid valve operable to selectively supply the hydraulic pressure to the actuator. Variable valve lift device after Claim 3 wherein the piston selectively presses the variable valve by a sub-stroke, and an elastic piston portion is disposed at a lower end portion of the piston. A variable valve lift device according to any one of the preceding claims, wherein the sub-stroke of the variable valve is a stroke lower than the main stroke. A variable valve lift device according to any one of the preceding claims, wherein an elastic gap portion is disposed at a lower end portion of the valve gap control means which presses the two valves simultaneously. Variable valve lift device after Claim 6 further comprising: a valve bridge connecting the two valves, the lower end portion of the valve gap control means being adapted to press the valve bridge. Variable valve lift device after Claim 7 in which the variable valve is arranged to be movable up and down the valve bridge. Variable valve lift device after Claim 8 further comprising a plunger disposed at an upper end portion of the variable valve on the valve bridge to realize a relative upward and downward movement of the variable valve. Variable valve lift device after Claim 3 wherein the cam comprises: a base formed in an arc shape having a uniform radius and a circular center which is a rotation center of the cam; a sidelobe configured to press the lever body from when opening of the variable valve is started until closing of the variable valve is completed while the variable valve is operated by the sub-stroke; and a main tab configured to press the lever body from when opening of the second valve is started until closing of the second valve is completed by the main stroke. Variable valve lift device after Claim 10 wherein an outer diameter of the minor lobe is larger than an outer diameter of the base and an outer diameter of the main lobe is larger than an outer diameter of the minor lobe. Variable valve lift device after Claim 10 or 11 in that the base and the main lobes are formed at opposite sides to each other with respect to a rotation center of the cam and the sidelobe is formed between the base and the main lobe. Variable valve lift device after Claim 12 in which the sidelobes are formed at a first side and a second side with respect to a rotation center of the cam. Variable valve lift device according to one of the Claims 10 to 13 in that, when the operating portion is not operated, the variable valve is not pushed by the operating portion even if the slave lobe of the cam is in contact with the lever body. Variable valve lift device according to one of the Claims 10 to 14 wherein, when the solenoid valve is ON, a hydraulic pressure is supplied to the chamber by an operation of the actuator while the slave cam of the cam is in contact with the lever body, the piston is adapted to be moved down, and the variable valve presses , Variable valve lift device according to one of the Claims 10 to 15 wherein, when the main lobe of the cam is in contact with the lever body, the piston returns to an original position thereof when the solenoid valve is OFF, hydraulic pressure being released from the chamber by stopping actuation of the actuator. A variable valve lift device according to any one of the preceding claims, wherein the variable valve is adapted to be actuated by the sub-stroke during an intake stroke of an engine realizing an internal exhaust gas recirculation. A variable valve lift apparatus according to any one of the preceding claims, wherein the variable valve is adapted to be operated by the sub-stroke during a compression stroke of an engine, whereby engine braking is realized. Variable valve lift device after Claim 18 in which a timing of opening of an exhaust port by the variable valve is a center of top dead center.

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