CN210687088U

CN210687088U - Clutch valve and clutch system

Info

Publication number: CN210687088U
Application number: CN201920579703.2U
Authority: CN
Inventors: B·E·J·M·蕾纳尔特斯
Original assignee: Punch Powertrain NV
Current assignee: Nanjing Bangqi Automatic Transmission Co ltd
Priority date: 2018-04-25
Filing date: 2019-04-25
Publication date: 2020-06-05
Anticipated expiration: 2029-04-25
Also published as: BE1026265A1; BE1026265B1

Abstract

The utility model relates to a clutch valve and clutch system, this clutch valve are used for automatically operation friction clutch system. The valve has a first end in fluid communication with the pilot pressure port and a recess section in fluid communication with the sump port and the clutch pressure port if the valve body is in the clutch disengaged position and in fluid communication with the clutch pressure port and the supply pressure port if the valve body is in the clutch engaged position. The valve body has a first section on an axial side of the recess section where the pilot pressure port is located, and a second section on an opposite axial side of the recess section. The first section fits in the valve chamber with a first clearance and the second section fits in the valve chamber with a second clearance that is greater than the first clearance.

Description

Clutch valve and clutch system

Technical Field

The present invention relates to a clutch valve for an automatically operating friction clutch system and a friction clutch system comprising such a valve.

Background

Automatically actuated friction clutches are widely used in the powertrains of passenger and light commercial vehicles, for example as clutches in line with continuously variable transmissions or in line with automatic transmissions (with one or two clutches). The automatically operated friction clutch is also used to automatically couple and decouple front wheel drive or rear wheel drive of a four wheel drive transmission in response to wheel rotation, and an automatic self-braking differential for transmitting torque to the wheel with the greatest grip.

In such clutches, frictional engagement of the driving and driven clutch components is typically controlled by gradually increasing the pilot pressure supplied to the clutch-operating valve. In response to an increase in the pilot pressure, the clutch-operating valve allows more of the operating pressure generated by the pressure source to be transferred to the clutch, which in turn causes the clutch members to engage with a normal force sufficient to transfer a torque greater than the maximum torque that the vehicle engine can generate without being greater than a safety margin. When the clutch is engaged, starting from a stationary state or after shifting gears, torque is transferred from a minimum transfer torque and moves to a fully transferred engine torque when the clutch is actuated by the clutch valve to fully engaged.

A problem with such clutches is that in some cases the increase in transmitted torque from the engine then levels off briefly, after which a sudden brief increase in transmitted torque results in a brief sudden acceleration (commonly referred to as a "tip-in shock") occurring during clutch engagement, which is intended to be gradual, for example for smooth driving from a stationary condition or for smooth establishment of torque transmission after a gear shift or in response to wheel rotation of other driven wheels. This causes discomfort to the passengers and, in severe cases (especially for torque-distributing clutches), wheel rotation, loss of cornering stability, increased transmission wear of the transmission and even damage.

Known solutions that attempt to mask this problem result in clutch components engaging more slowly and providing resiliency and damping in the driveline. However, a slower increase in clutch engagement leads to more slipping of the clutch and thus to more wear, power loss and increased energy consumption, and an increase in elasticity and damping in the driveline tends to lead to undesirable dynamic behavior of the driveline, such as indirect response and surge during vibration at high loads or high speeds.

SUMMERY OF THE UTILITY MODEL

The object of the invention is to at least reduce acceleration shocks during clutch engagement, in particular when accelerating from a standstill, and during clutch engagement while driving.

A first aspect of the present invention relates to a clutch valve for an automatically operated friction clutch system for a drive train of a motor vehicle, the clutch valve comprising: a valve housing with, in axial sequence, a pilot pressure port for fluid communication with a pilot pressure controller, a sump port for fluid communication with a sump, a clutch pressure port for fluid communication with a clutch, and a supply pressure port for fluid communication with a supply pressure source, the pilot pressure port, the sump port, the clutch pressure port, and the supply pressure port being in fluid communication with a valve cavity in the valve housing, and a valve body axially movable in the valve cavity; wherein the valve body has a first end in fluid communication with the pilot pressure port and a recessed section in fluid communication with the sump port and the clutch pressure port if the valve body is in the clutch disengaged position and in fluid communication with the clutch pressure port and the supply pressure port if the valve body is in the clutch engaged position; wherein the valve cavity and the valve body are arranged such that the valve body separates the pilot pressure port from the sump port, the clutch pressure port, the supply pressure port, the valve body in the clutch disengaged position closes the supply pressure port from the clutch pressure port, and the valve body in the clutch engaged position closes the clutch pressure port from the sump port; and the valve body has a first sealing section on the axial side of the recess section where the pilot pressure port is located, which first sealing section is fitted with a first clearance in the valve chamber, and a second sealing section on the opposite axial side of the recess section, which second sealing section is fitted with a second clearance in the valve chamber, which second clearance is larger than the first clearance.

A second aspect of the present invention relates to a clutch system for a drive train of a motor vehicle, the clutch system comprising: a clutch having a driven clutch member, a driving clutch member, and a hydraulically operated chamber, a first one of the clutch members being operable between an engaged condition in which the first member is pressed in frictional contact against a second one of the clutch members for common rotation with the second member, and a disengaged condition in which each of the clutch members is permitted to rotate relative to the other of the clutch members, the hydraulically operated chamber being for applying hydraulic pressure that presses the first one of the clutch members into the engaged condition, the improvement comprising: the clutch valve according to the first aspect; a pressure source in fluid communication with the supply pressure port; a pilot pressure controller in fluid communication with the pressure source and the pilot pressure port; and a sump in fluid communication with the sump port and the pressure source.

Because the second clearance is larger than the first clearance, the tendency of the valve member to exhibit stick-slip behavior is at least substantially reduced, and the pressure supplied to the clutch follows a gradual increase in the pilot pressure substantially more smoothly than in a clutch system with a clutch valve having substantially the same clearance over all bearing and sealing surfaces.

Further features, effects and details of the invention can be seen from the detailed description and the drawings.

Drawings

Fig. 1 is a schematic diagram of a clutch system according to the present invention; and is

Fig. 2 is a schematic cross-sectional view of a clutch valve of a clutch system according to the present invention.

Detailed Description

The invention is first described in more detail with reference to the example shown in fig. 1 and 2. The clutch system is used in the drive train of a motor vehicle. The clutch system may be a master clutch system for allowing acceleration from rest, driven by an electric motor such as an internal combustion engine that is unable to generate drive torque from rest, but may also be a clutch for coupling or decoupling a driven axle or wheel from a power source. The clutch system has a clutch 1, the clutch 1 having a driven clutch part 2 and a drive clutch part 3. The driven clutch member 2 is intended to be coupled to an electric motor driven thereby, and the drive clutch member 3 is intended to be coupled to a transmission or drive shaft via which one or more wheels of the vehicle are driven. In this example, the driven clutch member 2 is operable between an engaged condition in which the driven clutch member 2 is pressed in frictional contact against the other of the clutch members 3, i.e. the drive clutch member, for co-rotation with the drive clutch member 3, and a disengaged condition in which each of the clutch members 2, 3 is permitted to rotate relative to the other of the clutch members 2, 3. Between the engaged state and the disengaged state is an operating range of the slipping state in which the driving clutch member rotates at a different rotational speed than the driven clutch member. Because the clutch is actuated to change its operating state from the disengaged state to the engaged state and its operation involves passing through the slipping state, the difference in rotational speed is reduced and the transmitted torque is increased. In particular, in order to smoothly deviate from a standstill, the difference in the rotational speed should be gradually reduced (so that the vehicle speed smoothly increases), and the transmitted torque should also be gradually increased (so that the vehicle acceleration experienced by the passenger smoothly increases as an acceleration force). Furthermore, a hydraulic chamber 4 is provided for applying hydraulic pressure to press the driven clutch member into engagement. Alternatively or additionally to the driven clutch member, the drive clutch member is operable for engaging and disengaging another clutch member.

The clutch system also has a clutch valve 5, the clutch valve 5 having a valve housing 6 (see fig. 2) and an elongated valve body 7, the valve body 7 being movable in the valve housing 6 in the axial direction (double arrow 8).

In the valve housing 6, a pilot pressure port 9, a sump port 10, a clutch pressure port 11, and a supply pressure port 12 are provided in the axial order. The pilot pressure port 9, the sump port 10, the clutch pressure port 11 and the supply pressure port 12 are in fluid communication with a valve chamber 13 in the valve housing 6, the valve body 7 being fitted in a sliding fit in the valve chamber 13. The closest fit between the valve body 7 and the valve chamber 13 in a direction perpendicular to the axial direction 8 is preferably a sliding fit that is as small as possible based on effectively sustainable manufacturing tolerances and ensures essentially no forceful free sliding movement while minimizing leakage between the ports. A vent or second sump port 31 is provided to allow air and/or oil to flow in and out as the valve body 7 moves back and forth in the valve cavity 13. In this example, the valve chamber 13 is a bore having a large diameter section and a small diameter section. The transition from the large diameter section to the small diameter section is at the location where the clutch pressure port 11 intersects the valve chamber 13.

The valve chamber 13 is axially bounded on opposite ends of the valve chamber 13 by

end plugs

14, 15. One of the plugs 14 leaves an annular space between the plug 14 and a peripheral wall portion of the valve chamber 13, accommodating an outer end portion of the helical spring 25. A coil spring 25 is arranged for urging the valve body towards the cam member 16.

The pressure source 17 of the clutch system is in fluid communication with the supply pressure port 12 via a pressure line 20. The pilot pressure controller 18 of the clutch system is in fluid communication with the pressure source 17 via a pressure line 21 through a pressure relief system (not shown) and with the pilot pressure port 9 via a pressure line 22 for transferring a controlled amount of control pressure from the reduced pressure from the pressure source 17 to the pilot pressure port 9. Such pilot pressure controllers are known and may be controlled, for example, based on user input received from a throttle pedal and optionally from an acceleration sensor. The pilot pressure controller may for example be arranged to control the pilot pressure in dependence on a control signal received from a vehicle control unit, the control signal being indicative of a currently required amount of acceleration and a current rotational speed of the driven coupling part 2 and the driving coupling part 3. The sump 19 is in fluid communication with the first sump port 10 via a return line 23 and may be in communication with the second sump port 31. Further, the sump 19 is in fluid communication with the pressure source 17 via a suction line 24.

The valve body 7 has a first end 26 and a recess section 27, the first end 26 being in fluid communication with the pilot pressure port 9, the recess section 27 being in fluid communication with the sump port 10 and with the clutch pressure port 11 if the valve body 7 is in the clutch disengaged position (as shown in fig. 2), the recess section 27 being in fluid communication with the clutch pressure port 11 and with the supply pressure port 12 if the valve body 7 is in the clutch engaged position, wherein the valve body is moved a certain distance from the tab member 16 towards the coil spring 25 so that the recess section 27 reaches the supply pressure port 12 and the recess section 27 is still in open communication with the sump port. As the valve body 7 is moved further, the size of the opening communicating with the supply pressure port 12 increases, and the size of the opening communicating with the sump port 10 decreases until the opening to the sump port 10 is closed.

Furthermore, the valve chamber 13 and the valve body 7 are arranged such that the valve body 7 separates the pilot pressure port 9 from the sump port 10, the clutch pressure port 11 and the supply pressure port 12 in any operating position of the valve body 7. As shown in this example, this may be accomplished, for example, by providing the following: the valve body 7 is provided with a first sealing section 28 which fits tightly in a corresponding first sealing section 29 of the valve chamber 13. The cooperation between the first sealing section 28 of the valve body 7 and the first sealing section 29 of the valve chamber 13 provides a seal that keeps the pilot pressure port 9 substantially separated from the sump port 10.

Furthermore, the valve body 7 in the clutch disengaged position shown separates the supply pressure port 12 from the valve chamber 13. As shown in this example, this may be accomplished, for example, by providing the following: the valve body 7 is provided with a second sealing section 32, the second sealing section 32 being located axially on the opposite side of the recess section 27 from the first sealing section 28 of the valve body 7 and fitting tightly in a corresponding third sealing section 33 of the valve chamber 13. The second sealing section 32 seals the supply pressure port 12 from the axially adjacent clutch pressure port 11 when the valve body 7 is in the clutch disengaged position shown. Such sealing may allow for a small leakage below the maximum oil consumption of the clutch 1 on the downstream side of the port 11, which is below a threshold flow rate at which the clutch 1 will be pulled out of the disengaged state. Thus, any leakage will not bring the clutch 1 out of its disengaged state.

Furthermore, the valve body 7 has a third sealing section 40 which seals against the fourth sealing section 38 of the valve chamber 13. This seal separates the supply pressure port 12 from the second sump port 31. Such a seal may allow for slight leakage and is preferably arranged to minimize leakage while ensuring a snug fit with effectively sustainable manufacturing tolerances.

Furthermore, the valve chamber 13 and the valve body 7 are arranged such that if the valve body 7 is in the clutch engaged position, it closes the sump port 10 and thus prevents a substantial flow from the clutch 1 via the clutch pressure port 11 towards the sump 19. As shown in this example, this may be achieved, for example, by providing the following: the first sealing section 28 of the valve body is tightly fitted in a corresponding second sealing section 37 of the valve chamber 13 between the sump port 10 and the clutch pressure port 11. This first sealing section 28 of the valve body 7 substantially seals the clutch pressure port 11 from the axially adjacent sump port 10 against the inner surface of the second sealing section 37 of the valve chamber 13 between the pressure port 11 and the sump port 10 when the valve body 7 is in the clutch engaged position.

In operation, the pilot pressure controller 18 gradually increases the pilot pressure when clutch engagement is desired. This causes the valve body 7 to move gradually away from the boss member 16. When the second sealing section 32 of the valve body 7 between the supply pressure port 12 and the clutch pressure port 11 disengages the third sealing section 33 of the valve chamber 13 between the supply pressure port 12 and the clutch pressure port 11, oil is allowed to pass from the supply pressure passage 20 to the hydraulic chamber 4 of the clutch 1 via the supply pressure port 12, the valve chamber 13, the clutch pressure port 11, and the clutch passage 39. At the same time, the first sealing section of the valve body 7 moves towards the second sealing section 37 of the valve chamber 13 between the clutch pressure port 11 and the sump port 10, thereby restricting and substantially preventing oil from flowing to the sump 19 after sealing contact with the second sealing section 37 of the valve chamber 13. When flow to the sump 19 is substantially stopped, clutch pressure builds from the supply passage 20.

The clutch pressure will act axially at the transition of the recess section 27 to the first sealing section 28 of the valve body and the recess section 27 to the second sealing section 32 of the valve body. Since the first sealing section 28 has a larger diameter than the second sealing section 32, this results in a net feedback force acting on the valve body 7 against the axial force exerted on the end 26 of the valve body 7 by the pilot pressure. The net feedback force and the axial force exerted by the coil spring 25 force the valve body 7 back towards the clutch disengaged position so that each pilot pressure reaches an equilibrium position in which the axial forces acting on the valve member 7 cancel each other resulting in a constant controlled clutch pressure on the line which is independent of the flow from the supply pressure port 12 to the clutch pressure port 11 and is only slightly affected by the supply pressure at the supply pressure port 12. As the pilot pressure increases, the equilibrium position of the valve body 7 moves towards the clutch engagement position until the pilot pressure is sufficient to substantially prevent backflow to the sump 19 and to allow maximum transfer of the supply pressure to the clutch 1. This preferably achieves a maximum clutch pressure that ensures that the clutch members 2 and 3 are in non-slipping frictional engagement with one another. The clutch pressure is preferably not higher than the supply pressure. The seal between the first sealing section 28 of the valve body 7 and the second sealing section 37 of the valve chamber 13 is preferably sized to minimize leakage while ensuring that the valve body 7 slides freely under effectively sustainable manufacturing tolerances.

In use, such clutch systems often produce sudden, brief accelerations when engaged ("acceleration shocks"), similar to the shock felt by the driver when releasing a manually operated clutch pedal too quickly, which is uncomfortable. This acceleration shock can be reduced by modifying the clutch plate engagement points using software modifications so that the torque transmitted between the clutch halves moves the clutch valve body 7, at least initially, further away from its position in relation to the shock-prone operation of the clutch system. This has side effects such as more severe clutch wear and more severe vehicle vibration due to increased slip of the clutch 1.

It has been found that acceleration shock can be reduced or eliminated. For this purpose, the first sealing section 28 of the valve body 7 is fitted with a first clearance in a corresponding first sealing section 29 of the valve chamber 13, and the second sealing section 32 of the valve body 7 is fitted with a second clearance in a corresponding third sealing section 33 of the valve chamber 13, the second clearance being greater than the first clearance. Therefore, the stick-slip behavior of the valve body 7 when moving with an increase in the pilot pressure is reduced or prevented, and the amount of supply pressure applied to the clutch 1 more closely follows the gradual increase in the pilot pressure, rather than temporarily lagging and then abruptly increasing.

The tolerance range of the second gap preferably does not overlap the tolerance range of the first gap, i.e. the minimum allowable gap of the second range is preferably equal to or greater than the maximum allowable tolerance of the first gap range. In a preferred embodiment, the second gap is at least 1.5 times the size of the first gap, or the second gap is at least 0.01mm larger or at least 0.02mm larger than the first gap.

On the one hand, the second gap is preferably dimensioned such that the largest contaminating particles can pass through and do not block between the second sealing surface 32 of the valve body 7 and the third sealing surface 33 of the valve chamber 13, and on the other hand, to avoid leakage, the second gap is preferably dimensioned to be largest such that the leakage flow is below the minimum flow through the port 11 that would cause the actuation clutch 1 to fall out of the disengaged state. For this purpose, the second gap range may, for example, be in the range of 0.04-0.08mm, while the first gap range may, for example, be in the range of 0.01-0.04 mm. Such a range of values for the first clearance and the second clearance may for example apply to valve body diameters of 8-20mm clearance, in particular 10-15mm clearance. In a preferred embodiment, the second gap is at most 0.05mm larger or at most 0.04mm larger than the first gap.

For precise guidance of the valve body 7 in the valve body 13, a third sealing section 40 of the valve body 7 on the axial side of the second sealing section 32 of the valve body 7 remote from the recess section 27 can be fitted in a corresponding fourth sealing section 38 of the valve chamber 13, and the third gap is smaller than the second gap. The third gap is preferably approximately equal to the first gap and is minimized from leakage while allowing for efficient manufacturing.

A second clearance larger than the third clearance can be effectively produced if the diameter of the second sealing section 32 of the valve body 7 is slightly reduced compared to the diameter of the third sealing section 40 of the valve body 7 and/or the diameter of the third sealing section 33 of the valve chamber 13 is slightly enlarged compared to the diameter of the fourth sealing section 38 of the valve chamber 13.

This difference can be achieved, for example, by: starting from the same diameter, the second sealing section 32 of the valve body 7 is finished to a smaller diameter than the diameter of the third sealing section 40 of the valve body 7 and/or starting from the same diameter, the third sealing section 33 of the valve chamber 13 is finished to a larger diameter than the diameter of the fourth sealing section 38 of the valve chamber 13.

For efficient manufacturing, the second and

third sealing sections

32, 40 of the valve body 7 or the third and

fourth sealing sections

33, 38 of the valve chamber 13 may be manufactured to the same diameter (i.e. to the same tolerance range).

Claims

1. A clutch valve for an automatically operating friction clutch system for a drive train of a motor vehicle, the clutch valve (5) comprising:

-a valve housing (6) carrying, in axial sequence, a pilot pressure port (9), a sump port (10), a clutch pressure port (11) and a supply pressure port (12), the pilot pressure port (9) being for fluid communication with a pilot pressure controller, the sump port (10) being for fluid communication with a sump, the clutch pressure port (11) being for fluid communication with a clutch, the supply pressure port (12) being for fluid communication with a supply pressure source, the pilot pressure port (9), the sump port (10), the clutch pressure port (11) and the supply pressure port (12) being in fluid communication with a valve cavity (13) in the valve housing (6), and

-a valve body (7), the valve body (7) being axially movable in the valve chamber (13);

wherein the valve body (7) has a first end (26) and a recess section (27), the first end (26) being in fluid communication with the pilot pressure port (9), the recess section (27) being in fluid communication with the sump port (10) and the clutch pressure port (11) if the valve body (7) is in a clutch disengaged position, the recess section (27) being in fluid communication with the clutch pressure port (11) and the supply pressure port (12) if the valve body (7) is in a clutch engaged position;

wherein the valve chamber (13) and the valve body (7) are arranged such that the valve body (7) separates the pilot pressure port (9) from the sump port (10), the clutch pressure port (11), the supply pressure port (12), the valve body (7) in the clutch disengaged position closes the supply pressure port (12) from the clutch pressure port (11), and the valve body (7) in the clutch engaged position closes the clutch pressure port (11) from the sump port (10); and is

Characterized in that the valve body (7) has a first sealing section (28) on the axial side of the recess section (27) in which the pilot pressure port (9) is located, the first sealing section (28) fitting with a first clearance in the valve chamber (13), and the valve body (7) has a second sealing section (32) on the opposite axial side of the recess section (27), the second sealing section fitting with a second clearance in the valve chamber (13), the second clearance being larger than the first clearance.

2. The clutch valve as recited in claim 1, wherein the second clearance is 0.04-0.08 mm.

3. A clutch valve according to claim 1 or 2, characterized in that the second clearance is at most 0.05mm larger than the first clearance.

4. A clutch valve according to claim 1 or 2, characterized in that the second gap is at most 0.01mm larger than the first gap.

5. A clutch valve according to claim 1 or 2, characterized in that the second gap is at least 1.5 times as large as the first gap.

6. Clutch valve according to claim 1, the valve body (7) having a third sealing section (40) on the axial side of the second sealing section (32) remote from the recess section (27), the third sealing section (40) fitting in the valve chamber (13) with a third clearance which is smaller than the second clearance.

7. The clutch valve as recited in claim 6, wherein the third clearance is equal to the first clearance.

8. A clutch system for a driveline of a motor vehicle, the clutch system comprising:

a clutch (1) having a driven clutch member (2), a driving clutch member (3) and a hydraulically operated chamber (4), a first one of the clutch members (2, 3) being operable between an engaged condition in which it is pressed in frictional contact against a second one of the clutch members (2, 3) for co-rotation therewith and a disengaged condition in which each of the clutch members is allowed to rotate relative to the other one of the clutch members, the hydraulically operated chamber (4) being for applying a hydraulic pressure which presses the first one of the clutch members (2, 3) into the engaged condition, characterised by further comprising:

a clutch valve (5) according to any of the preceding claims;

a pressure source (17), the pressure source (17) being in fluid communication with the supply pressure port (12);

a pilot pressure controller (18), the pilot pressure controller (18) being in fluid communication with the pressure source (17) and the pilot pressure port (9); and

a sump (19), the sump (19) in fluid communication with the sump port (10) and the pressure source (17).