WO2008060603A2

WO2008060603A2 - Electrohydraulic clutch for motorcycle

Info

Publication number: WO2008060603A2
Application number: PCT/US2007/024018
Authority: WO
Inventors: Michael Czysz
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-11-15
Filing date: 2007-11-15
Publication date: 2008-05-22
Anticipated expiration: 2009-05-15
Also published as: WO2008060603A3

Abstract

A motorcycle clutch actuator including a hydraulic cylinder and piston combination that mechanically operates a clutch disengagement mechanism, and for which an electrically controlled hydraulic fluid outlet valve is operated by an electronic control unit to prevent or allow the clutch to be engaged, in response to signals provided to the electronic control unit by sensors indicative of various parameters such as engine speed, transmission gear selection, and ground wheel speed.

Description

ELECTROHYDRAULIC CLUTCH FOR MOTORCYCLE

TECHNICAL FIELD

[0001] The present invention relates to motorcycle clutch control, particularly in high- performance motorcycles.

BACKGROUND ART

[0002] In situations where a motorcycle needs fine control, it can require a great amount of coordination and finesse from the rider. Some instances are more challenging than others. For example, in motorcycle racing, the motorcycle may need to negotiate turns as quickly as possible. The rider would be required to steer, brake, shift gears, and modulate the clutch and throttle to match the engine speed with the road speed. When these actions are not performed optimally under certain road conditions, there may be chassis instability or rear wheel lock-up.

[0003] One type of device that helps reduce wheel chatter and prevent the rear wheel from locking up is a slipper clutch. When engaging the clutch at mismatched engine and rear wheel speeds would otherwise lead to an undesirable response from the motorcycle, a typical slipper clutch automatically disengages the clutch enough to allow slippage and prevent the rear wheel from over-revving the engine.

[0004] As a mechanical solution, slipper clutches do not offer much flexibility in fine- tuning. It is desirable to have a system that permits at least a degree of real- time feedback to aid in engagement of the clutch.

DISCLOSURE OF INVENTION

[0005] A clutch actuator as disclosed herein and as defined by the claims appended hereto includes a hydraulic cylinder and a piston disposed movably therein and arranged to operate a clutch mechanism, and an electrically controlled valve arranged to control release of hydraulic fluid from the hydraulic cylinder in response to a control signal provided by an electronic control unit programmed to respond to signals representative of various parameters that may include engine speed, selected transmission gear ratio, road wheel speeds, brake states, and engine throttle position.

[0006] The foregoing and other features and advantages of the disclosed apparatus will be more readily understood upon consideration of the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a side elevational view of a motorcycle including a clutch such as the one disclosed herein. [0008] FIG. 2 is a front elevational view of a portion of the motorcycle shown in FIG. 1 , including a view of the clutch mechanism.

[0009] FIG. 3 is a sectional view taken along line 3-3 of FIG. 2, showing the clutch mechanism disclosed herein.

[0010] FIG. 4 is a sectional view similar to a portion of FIG. 3, at an enlarged scale, and showing the clutch actuation mechanism together with portions of an electronic control system.

[0011] FIG. 5A is an isometric view from the upper rear of the clutch actuator housing shown in FIGS. 2, 3, and 4.

[0012] FIG. 5B is an isometric view from the upper front of the clutch actuator housing.

[0013] FIG. 5C is a rear elevational view of the clutch actuator housing.

[0014] FIG. 5D is a sectional view taken on line 5D-5D in FIG. 5C.

[0015] FIG. 5E is a bottom plan view of the clutch actuator housing.

[0016] FIG. 5F is a sectional view taken on line 5F-5F in FIG. 5E.

[0017] FIG. 6 is a front elevational view of a clutch actuator housing that is an alternative embodiment.

[0018] FIG. 7 is a sectional view of the clutch actuator housing shown in FIG. 6, taken along line 7-7 of FIG. 6.

[0019] FIG. 8 is bottom plan view of the clutch actuator housing shown in FIGS. 6 and 7.

[0020] FIG. 9 is a sectional view of the clutch actuator housing shown in FIGS. 6-8, taken along line 9-9 of FIG. 8.

[0021] FIG. 10 is an isometric view from the upper rear of the clutch actuator housing shown in FIGS. 6-9.

[0022] FIG. 11 is an isometric view taken from the upper front of the clutch actuator housing shown in FIGS. 6-10.

[0023] FIG. 12 is a sectional view of the clutch actuator housing shown in FIGS. 6-1 1, taken on line 12-12 of FIG. 6.

[0024] FIG. 13 is a sectional view similar to FIG. 7, showing a clutch actuator housing that is another alternative embodiment.

[0025] FIG. 14 is a sectional view taken on line 14-14 of FIG. 13.

DETAILED DESCRIPTION OF MODES FOR CARRYING OUT THE INVENTION

[0026] FIG. 1 shows a motorcycle 20 which uses a clutch for engaging and disengaging engine power to and from the transmission. The clutch includes a clutch lever 22 coupled with a master cylinder 23 mounted on a handlebar 24 of the motorcycle for a rider to actuate the clutch 26. The clutch lever is connected to a master cylinder, a component on the handlebar that is capable of sending hydraulic fluid downward to command a slave unit, as further discussed below. When the clutch lever 22 is pulled in, the clutch disengages and power is not transmitted from the engine 28 to the transmission 30. When the clutch lever is released, the clutch 26 engages due to preload. In theory, for smooth downshifting, engagement of the clutch should take place when the engine speed and the road speed are matched up.

[0027] FIG. 2 shows the front of the clutch 26 and a clutch actuator assembly 32 for use with the clutch 26 according to one embodiment. The clutch actuator assembly 32 is coupled to the crankcase of the engine 28, aligned with the clutch 26. The clutch actuator assembly 32 may be made to be compatible with conventional clutches and components, and can be added on to a typical clutch. In addition, the use of wet (in oil bath) or dry (sealed) clutch plates is compatible with the actuator assembly 32 disclosed herein.

[0028] As shown in FIG. 3, the clutch 26 includes a clutch basket 34 which is to be coupled to a crankshaft or other output shaft 36 from the engine (not shown). Adjacently disposed within the clutch basket 34 is a clutch hub 38 coupled to a transmission power input shaft 40 (not shown). Driven clutch plates 42 are coupled to the clutch hub 38 and are rotatably disposed within the clutch basket 34. The clutch 26 also includes driving plates 44 that are carried in and configured to rotate with the clutch basket 34 and are interleaved between the driven plates 42 that are configured to rotate with the clutch hub 38.

[0029] A clutch actuator pull rod 46 is inserted through a bearing 48 attached to the pressure plate 50 and can move the pressure plate 48 away from the clutch plates 42, 44 for clutch disengagement, or can allow the pressure plate 50 to move towards the clutch plates 42, 44 for engaging the clutch 26. The clutch actuator pull rod 46 extends into a clutch actuator housing 52 disposed adjacent to the pressure plate 50.

[0030] In general, the clutch 26 is predisposed to being engaged, as are most clutches. Helical coil springs 54 are housed in spring cups 56 defined in the pressure plate 58. The springs 54 are compressed between the cups 56 and flanges 60 of mandrels 62, mounted in and extending from the hub 38, and around which the springs 54 are disposed. The springs 54 thus cause the pressure plate 50 to apply pressure to urge the driven clutch plates 42 and driving clutch plates 44 together, into frictional contact with one another. The applied pressure and resulting friction enable the clutch basket 34 and the hub 38 and components within related to the pressure plate 50 to rotate together as one unit and transfer power from the engine 28 to the transmission 30.

[0031] When the clutch lever 22 is pulled to disengage the clutch 26, the springs 54 are compressed by the pull rod 46, acting on the pressure plate 50 through the bearing 48, so that the pressure plate moves away from the clutch plates 42, 44, the clutch basket 34, and the clutch hub 38. This relief of pressure frees the driving plates 44 to rotate at engine speed and the driven plates 42 to rotate with the clutch hub 38, typically at a speed determined by the selected transmission gear ratio and road speed, and thus usually a speed different from the engine speed. Since the driving plates 44 and driven plates 42 are free to separate from each other, the plates slip and allow the clutch basket 34 and hub 38 to rotate independently of each other. Thus engine power from the clutch basket 34 is decoupled from the clutch hub 38. [0032] Referring now to FIG. 4, the clutch actuator housing 52 and other actuator components which together comprise the clutch actuator assembly 32 are shown in more detail. As a subassembly of the clutch 26, the clutch actuator assembly 32 effects the engagement and disengagement of the clutch 26 using an electronically controlled hydraulic system. The clutch actuator housing 52 includes a front cover 64 that conceals a hydraulic cylinder 66 in which a clutch actuator piston 68 is movably disposed. The front cover 64 may also prevent debris from entering the clutch actuator mechanism 32. The clutch actuator pull rod 46 passes through a bore 69 in the base of the hydraulic cylinder 66, and a seal is mounted in the rod to retain fluid in the hydraulic cylinder 66.

[0033] The clutch actuator housing 52, as may also be seen with reference to FIGS. 5 A, 5B, 5C, 5D, 5E, and 5F, is configured with hydraulic fluid passages in communication with the hydraulic cylinder 66, forming a closed circuit hydraulic system. In an inlet receptacle 70 of the clutch actuator housing, a check valve 72 is positioned downstream of a hydraulic hose connector socket 73 to permit forward, or inward, flow of hydraulic fluid into the hydraulic cylinder 66 initiated, e.g., from a master cylinder 23, typically located at the handlebars and responding to the clutch lever 22. One such check valve found to be satisfactory is a poppet style forward flow check valve available from the Lee Company of Westbrook, CT, as its part No. CKFAl 876201 A.

[0034] When the check valve 72 is opened, the fluid enters the hydraulic cylinder 66, via a fluid inlet port 74, but the check valve 72 is unidirectional and does not permit the fluid to return upstream from the hydraulic cylinder 66 into the inlet receptacle 70.

[0035] The clutch actuator housing 52 includes a fluid outlet port 76 in hydraulic communication with the hydraulic cylinder 66. The fluid outlet port 76 is in communication with a valve housing 78 configured to retain a solenoid valve 80 or other electrically operated or controlled valve which may be selectively opened and closed to control the ability of hydraulic fluid to exit the hydraulic cylinder 66 via the outlet port 76. One solenoid valve that operates with a satisfactorily short response time in an embodiment of the actuator mechanism is a high pressure single coil piloting solenoid valve available from The Lee Company, of Westbrook CT, as its part number SDBB21310*2A. The valve housing 78 is in fluid communication with an annular cavity 82, defined in the housing and closed by a rear cover 84, via a second fluid line, such as a tubular bore 86 defined in the housing.

[0036] The clutch actuator rear cover 84, as may be seen in FIGS. 4, 5 A, and 5D, is configured to be mated with the actuator housing 52 to close the annular cavity 82. The rear cover 84 defines a through-hole 88 for the pull rod 46. The actuator housing 52 defines a pair of concentric grooves 90 facing toward the rear cover 84. Hydraulic fluid flowing from the outlet port 76 and through the solenoid valve 80 may be contained in the annular cavity 82, between two concentric O-ring seals placed in the grooves 90, the rear cover 84, and the clutch actuator housing 52. This containing area will be referred to herein as a return pool. Alternatively, the hydraulic fluid may be contained using other means.

[0037] When the solenoid valve 80 is open, hydraulic fluid flows from the hydraulic cylinder 66 and travels through the second fluid line 86 and into the return pool via a return pool inlet port 92, as a result of the pull rod 46 pulling the piston 68 into the left, or bottom end of the hydraulic cylinder 66 when the springs 54 move the pressure plate 50 toward the hub 38. At some distance from the return pool inlet port 92 is a pool outlet port 94, where the fluid may exit the return pool and flow into a third, or return flow, fluid line 96 leading to the inlet receptacle 70 from the clutch master cylinder, if pressure from the master cylinder 23 has been reduced by release of the clutch lever 22.

[0038] The return flow fluid line 96 may be in fluid communication with a bleed hole 98 and an appropriate bleeder fitting where pressure may be released and air bubbles trapped in the fluid may escape. There may be bleed holes built into the other fluid lines and locations in the hydraulic fluid circuit. Alternatively, no bleed holes may be necessary, as sufficient bleeding may be possible at the master cylinder.

[0039] When the clutch lever 22 is pulled to cause clutch disengagement, the master cylinder 23 sends fluid down to the check valve 72. The hydraulic cylinder 66 fills with fluid let in by the check valve 72, and the pressure builds up and acts on the clutch actuator piston 68. As fluid pressure increases due to forward flow from the check valve 72 and the hydraulic cylinder 66 fills with fluid, the hydraulic fluid pushes the clutch actuator piston 68 outward toward the front cover 64, i.e., toward the position shown in FIG. 3.

[0040] As briefly mentioned above, the clutch actuator pull rod 46 is coupled to the clutch actuator piston 68. The clutch actuator pull rod 46 may include a threaded end that secures to the clutch actuator piston by a nut. Alternatively, any other means of securing the clutch actuator pull rod to the clutch actuator piston, such as a circular spring clip 99, may be used. The clutch actuator pull rod 46 may also include grooves suitable for retaining O-ring seals in appropriate locations to seal the hydraulic cylinder 66 tightly while allowing the piston 68 and pull rod 46 to move.

[0041] As the clutch actuator piston 68 slides out toward the front cover 64, the clutch actuator piston 68 draws the actuator pull rod 46 with it. Adequate clearance for movement of the clutch actuator piston 68 and/or clutch actuator pull rod 46 is available behind the front cover 64. As the clutch actuator pull rod 46 is drawn, it pulls the pressure plate 50 so that the pressure plate 50 releases the pressure on the driving plates 44 and the driving plates 44 are allowed to slip, with respect to the driven plates 42, thus disengaging the clutch.

[0042] When the solenoid valve 80 is closed when the clutch lever 22 is pulled, the fluid pressure may build up in the hydraulic cylinder 66 and push the clutch actuator piston 68 towards the front cover 64, effectively reducing or removing the pressure plate forces acting on the clutch plates 42 and 46 and disengaging the clutch 26. When the clutch lever 22 is released, if the solenoid valve 80 is still closed, the hydraulic fluid is retained in the hydraulic cylinder 66 and may reach a temporary equilibrium, because of the check valve 72, thus allowing the clutch actuator piston 68 and the clutch actuator pull rod 46 to remain stationary.

[0043] If the solenoid valve 80 is open, when the clutch lever 22 is released the fluid pressure acting on the clutch actuator piston 68 in the hydraulic cylinder 66 decreases as the fluid passes through the cylinder outlet port 76 and the solenoid valve 80 and enters the fluid line 86, to return eventually to the inlet receptacle 70 and the master cylinder 23. This enables the clutch actuator piston 68 and the clutch actuator pull rod 46 to move together in a direction towards the clutch basket 34, and allows the springs 54 to cause the pressure plate 50 to apply pressure to the clutch plates 42 and 44, reengaging the clutch 26.

[0044] The solenoid valve 80 may be controlled by an electronic control unit (ECU) 100. The ECU 100 is configured to receive electrical input signals from sensors measuring various motorcycle systems and subsystems. The ECU input signals may be representative of parameters such as which transmission gear ratio is in use, the gear the rider desires to shift to, the rear wheel speed, the engine speed, the front wheel speed, the status of front and rear brakes, and other parameters. Ranges of critical values for each parameter will differ depending on the motorcycle. The ECU may be programmed to follow an algorithm using certain parameters to determine whether to command the solenoid valve 80 to open or close. As a non-limiting example, the ECU 100 may be preprogrammed to respond to engine speed, the real-time rear wheel speed and selection of a particular transmission gear ratio by causing solenoid valve 80 to stay closed, to limit engagement of the clutch 26 until a target rear wheel speed is reached. Controlling the solenoid valve 80 to open and close for proper engagement of the clutch 26 may assist a rider in control of the motorcycle 20, by preventing engagement of the clutch 26 when input parameter signals indicate that engagement would cause the rear wheel to lose traction.

[0045] As another example, when the motorcycle 20 is entering a turn at high speed, braking heavily with the front wheel, and downshifting, the result of engine braking may cause the rear wheel to repeatedly and briefly slip on the ground, causing the rear suspension to chatter, and so a rider may pull the clutch lever 22 to disengage the clutch 26 temporarily. The ECU can be programmed to allow the clutch 26 to be reengaged at the earliest practical time after release of the clutch lever 22, by opening the solenoid valve 80 in response to signals indicating a preselected combination of selected parameters, to effect engine braking of the rear wheel without thereby skidding the rear wheel or overspeeding the engine.

[0046] The ECU 100 may include a control circuit, power supply circuit, microcomputer, and/or power supply circuit. The ECU may be linked to and/or communicate with a digital CPU, wireless system, or other system, or alternatively, the ECU 100 may function as a standalone device. As mentioned, the ECU 100 may be preprogrammed to respond to input signals from sensors measuring selected parameters. Alternatively, the ECU may accept instructions entered in real-time and alter the desired time of clutch engagement to selected input signals. The ECU may be physically located in proximity to the clutch actuator housing. Alternatively, the ECU 100 may be located at a remote location.

[0047] In an alternate embodiment (not shown), the clutch actuator assembly 32 may include or be connected to a pump for pressurization of hydraulic fluid, and the ECU 100 may also control the pump in regulating the hydraulic actuation of the clutch 26. However, such an arrangement is not necessary for the function of the clutch actuator assembly.

[0048] In an alternative embodiment of the clutch actuator housing 52, as shown in FIGS.

6-12, the passages through which hydraulic fluid may flow are arranged slightly differently, but operation is as described above with respect to the actuator assembly 32 shown in FIGS. 3-5F.

[0049] Referring to FIGS. 13 and 14, in another alternative embodiment of the clutch actuator mechanism 32, an actuator housing 152 includes a single inlet/outlet port 176 in fluid communication with the interior of the hydraulic cylinder 66, and a bleed port 198 in a location similar to that of the inlet port 74 in the previously described embodiments of the actuator housing 52.

[0050] As shown in FIG. 14, the hydraulic fluid inlet/outlet port 176 is in fluid communication with a hydraulic hose connector receptacle 170 extending to one side of and located adjacent to the solenoid valve housing 178. A hydraulic fluid inlet conduit 174 houses a check valve 72 arranged to permit flow from the receptacle 170 into the inlet/outlet port 176. [0051] The solenoid valve 80, when open, permits flow of hydraulic fluid from the hydraulic cylinder 66 through the inlet/outlet port 176 and through the valve body of the solenoid valve 80 into a return line 196 in fluid communication with the receptacle 170, so that hydraulic fluid can return from the hydraulic cylinder 66 to the master cylinder 23, depending upon the position of the clutch lever 22.

[0052] This arrangement of the fluid inlet connector receptacle 170 adjacent to the solenoid valve housing 178 obviates the annular cavity 82, the rear cover 84, the grooves 90, the O-rings, and the communicating ports 86 and 96 used for return flow of hydraulic fluid in the previously described embodiments of the clutch actuator 52.

[0053] It is to be noted that the solenoid valve 80 may be is any suitable mechanism that can release or relieve the fluid pressure from the hydraulic cylinder 66 and that responds to an electronic control means. This invention is not limited to the particular shape of the clutch actuator housing, and may include other shapes or geometries suitable for implementation of the electronic and/or hydraulic systems as described above. This invention may further include systems where the clutch 26 is engaged when the lever 22 is pulled in. There may be additional components in the clutch that may assist in the functionality of the clutch mechanisms, such as shock absorbers, bearings, spacers, shims, seals, etc., and their inclusion would be considered within the scope of this invention.

[0054] The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

Claims

CLAIM(S)

What is claimed is: 1. An actuator for a clutch, comprising: (a) an actuator housing adapted for attachment to a clutch housing; (b) a hydraulic cylinder defined in the housing;

(C) an actuator piston fitted in the hydraulic cylinder and movable therein in response to hydraulic fluid pressure;

(d) an actuator rod interconnected with the actuator piston so as to be moved by the actuator piston;

(e) a fluid inlet port communicating with the hydraulic cylinder; (0 a check valve arranged to admit fluid into the hydraulic cylinder through the inlet port and prevent the fluid from leaving the cylinder through the inlet port;

(g) an outlet port communicating with the hydraulic cylinder; (h) an electrically controlled valve located so as to control fluid flow in the outlet port and arranged to open and close in response to an electrical control signal;

(i) a sensor arranged to measure a selected parameter and provide a corresponding input signal; and

O) an ECU arrange to receive an input signal from the sensor and programmed to operate the electrically controlled valve in response to determining that the input signal is indicative of a predetermined value of the selected parameter.

2. The actuator of claim 1 wherein the ECU is responsive to each of a plurality of input signals representative of a plurality of parameters.

3. The actuator of claim 1 wherein said selected parameter is engine speed.

4. The actuator of claim 1 wherein said selected parameter is rear wheel speed.

5. The actuator of claim 1 wherein said selected parameter is a selected transmission gear ratio.

6. The actuator of claim 1 wherein said selected parameter is front wheel speed.

7. The actuator of claim 1 wherein said selected parameter is brake status.

8. A method of controlling a clutch arranged to deliver engine power to a power transmission gearbox in a motorcycle, comprising:

(a) decreasing clutch engagement by selectively providing a first quantity of hydraulic fluid under pressure to a hydraulically operated clutch actuator; and

(b) releasing a second quantity of the hydraulic fluid from the actuator by using an ECU to control an electrically operated outlet valve in response to a predetermined input signal indicative of a selected operational parameter.

9. The method of claim 8 wherein said step of decreasing clutch engagement includes manually disengaging the clutch completely, while said ECU keeps the electrically operated outlet valve closed.

10. The method of claim 8 including the step of operating the ECU to open the electrically operated outlet valve in response to a combination of input signals indicative of sensing a plurality of operational parameters within a predetermined set of values.