GB2231633A

GB2231633A - Power operated clutch and gear-changing device

Info

Publication number: GB2231633A
Application number: GB9011219A
Authority: GB
Inventors: Franz Boss; Andreas Graf
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1989-05-20
Filing date: 1990-05-18
Publication date: 1990-11-21
Anticipated expiration: 2010-05-18
Also published as: SE9001808L; GB9011219D0; SE468979B; SE9001808D0; GB2231633B; DE4015287A1; DE4015287C2

Abstract

A power operated clutch and gear-changing device for a motor vehicle with a gearbox (5) controlled by the driver via the clutch control on the clutch pedal (2), and having a tactile response signal provided by a signal transmitter unit (8) for the driver at the pedal (2) when the gear is engaged in the gearbox (5) comprises a valve (1) mounted in a pressure line (9) between a transmitter piston (21) mechanically connected to the pedal (2) and a receiver piston (31) for actuating the clutch (3). The valve (1) provides a flow path via the pressure line (9) from the piston (21) to the piston (31) when a gear is not engaged. and blocks flow in the opposite direction. The valve (1) is operated via a switch (23), electronic control device (7), magnetic valve (62), and the compressed air which is necessary to move the gear changing cylinders. <IMAGE>

Description

AUXILIARY POWER OPERATED CLUTCH AND GEAR-CHANGING SAFETY DEVICE THEREFOR DESCRIPTION This invention relates to an auxiliary power operated clutch and gear-changing device for a motor vehicle with a gear change controlled by the driver via the clutch control at the clutch pedal and with a response signal for the driver when, after the change, the gear is engaged, wherein a safety device is mounted in the pressure line between the transmitter cylinder mechanically connected to the clutch pedal and the receiver cylinder for actuating the clutch via which safety device, the pressure line having a flow path from the transmitter cylinder to the receiver cylinder when a gear is not engaged but being locked in the opposite direction from the receiver cylinder to the transmitter cylinder. The invention also relates to the safety device per se.

A safety device of this type is known and has proved to be advantageous because the clutch cannot be engaged even when the clutch pedal is retracted unless a gear is first engaged, and the drive line is then also engaged on the engagement of the clutch.

The cost of such a device is very high because, in addition to the gear change sensors or switches for changing over, an expensive magnetic valve is needed solely for the saftey device.

It is an object of the invention therefore to simplify an auxiliary power operated clutch and gear-changing device of the type described without impairing the function of the safety device.

According to one aspect of the invention, there is provided a safety device in an auxiliary power operated clutch and gear-changing device for a motor vehicle in which a gear change in the gearbox is controlled by the driver by means of the operation of a clutch pedal and a response signal is transmitted to the driver when the gear is engaged in the gearbox after the change, a safety device being mounted in a pressure line connecting a transmitter cylinder mechanically linked to the clutch pedal and a receiver cylinder for actuating the clutch, the safety device providing a flow path from the transmitter cylinder to the receiver cylinder when the gear is not engaged, but being locked in the opposite direction from the receiver cylinder to the transmitter cylinder, the safety device comprising a locking valve for the clutch actuated by compressed air, and the locking valve also being changed via control devices and the compressed air used to actuate a gear changing cylinder.

The invention further provides an auxiliary power operated clutch and gear-changing device for a motor vehicle in which a gear change in the gearbox is controlled by the driver by means of the operation of a clutch pedal and a response signal is transmitted to the driver when the gear is engaged in the gearbox after the change, wherein in the pressure line between the transmitter piston mechanically connected to the clutch pedal and a receiver cylinder for actuating the clutch, a safety device is additionally mounted, via which the pressure line has a flow from the transmitter cylinder to the receiver cylinder when the gear is not engaged, and is locked in the opposite direction from the receiver cylinder to the transmitter cylinder, characterised in that the safety device is a locking valve for the clutch actuated by compressed air, and the locking valve is also changed via the control devices and the compressed air used for moving a gear changing cylinder.

If the safety device is formed as a simple locking valve and is operated not electrically but with compressed air, a substantially more advantageous solution is achieved, because the magnetic valve provided to supply air to the adjusting cylinders which effect the gear change are also used to operate the locking valve at the same time. The electric switch for operating the compressed air for the gear change and mounted on the clutch pedal is therefore also used for actuating the safety device due to the coupling of the magnetic valve of the gear changing device to the locking valve. Due to the compressed air operation of the locking valve, this can be substantially simplified.

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows in diagrammatic form part of an auxiliary power operated clutch and gear-changing device; Figure 2 is a cross section through one form of safety device incorporating a locking valve, and, Figure 3 shows a cross section through part of an alternative safety device incorporating a locking valve.

A gear-changing and starting clutch 3 is mounted between a drive motor 4 and a gearbox 5. This starting clutch 3 is operated by a receiver piston 31, which is mounted in a receiver piston unit 32. A clutch pedal 2 is mechanically connected to a transmitter piston 21, which is mounted in a transmitter piston unit 22. The transmission of the mechanical clutch operation is effected from the transmitter piston 21 to the receiver piston 31 via a pressure medium, e.g. brake fluid and via pressure medium circuit 9, which is supplied from a pressure medium source 91. A signal transmitter unit 8 having a pressure piston or signal transmitter 82 is connected to this pressure medium circuit, the signal transmitter in this example being connected to a magnetic valve 81 and acted upon thereby.

When the magnetic valve 81 is opened, the air pressure pushes against the pressure piston 82 and hence against the presure medium in the pressure medium circuit 9.

This impact may be damped via pressure spirng 83, this damping being regulated by means of an adjusting device 84 by changing the pre-stressing of the pressure spring 83. The haptic signal acting on the clutch pedal 2 can therefore be regulated according to the driver's requirement.

A central valve block 6 is mounted on the gearbox 5 with magnetic valve 62 and controls both the pressure medium from the pressure medium source 64 for the locking valve 1 via the pressure line 61 and the gear changing cylinders via the line 63. Alternatively, however, the pressure line 61 can also be connected directly to the pressure medium source 64, in which case a separate pre-control valve is necessary, which, controlled by a control device 7, controls the pressure actuation of the locking valve 10. The electronic control device 7 is intended for the whole auxiliary power operated clutch and gear-changing device, although in this example, only the electric leads necessary for actuating the magnetic valve 62, and hence the locking valve 1, are shown.

The device according to Figure 1 operates as follows: In preparation for a gear change, the clutch pedal 2 is pressed right down by the driver, so that an electrical signal is transmitted from the switch 23 direct to the magnetic valve 62 or first of all via the electronic control device 7. The compressed air line 63 for supplying the gear changing cylinder and the compressed air line 61 which leads to the locking valve 1, are filled with compressed air from the compressed air source 64 due to the change-over of the magnetic valve 62. When the clutch pedal 2 is non-operative, the switch 23 is open so the locking valve 1 is switched in the indicated position to flow. When the clutch pedal 2 is actuated, the transmitter piston 21 opens or disengages the clutch 3 via the receiver piston 31 so the compressed air effects the change-over of the locking valve in the line 61.Futhermore, in this position, a passage is created from the transmitter piston 21 to the receiver piston 31, whereas it is locked in the opposite direction from the clutch 3, i.e. from the receiver piston 31 in the direction of the transmitter piston 21.

Even if the clutch pedal 2 is released by the driver, the clutch 3 remains open due to the locking effect of the locking valve 1 for as long as pressure is being applied in the compressed air line 61. During the normal course of a gear change, the driver receives a detectable signal at the clutch pedal after the engagement of a gear in the gearbox. To this end, after the engagement of a gear, the magnetic valve 81 is changed over via line 71 by the electronic control device 7 so that a pressure impact is transmitted into the pressure medium line 9 via the piston 82 and is transmitted via the transmitter piston 21 to the clutch pedal 2.

In parallel, the magnetic valve 62 also receives the same signal from the electronic control device 7 that a gear is engaged, and vents the pressure lines 61 and 63. Thus the locking valve 1 is again changed back into the position shown in Figure 1, and the driver can close or engage the clutch 3 in a known manner via the clutch pedal 2. The signal transmitter, namely switch 23 and magnetic valve 62 which is necessary for changing gear and the compressed air in the pressure line 63 necessary for the change, are also used for the locking valve via the compressed air line 61.

Figure 2 shows a preferred construction 10 for the locking valve 1 of Figure 1. In a housing 100, an appropriately shaped bore 101, 102 is provided for receiving a stepped pressure piston 120/150, the end face of the larger bore 102 being covered by a plate 103, which has a compressed air connection 104, e.g.

in the centre, to which the compressed air line 61 of Figure 1 is connected. The smaller diameter bore 101 receives, in addition to pressure piston 120, a further sealing piston 130 in an axial extension thereof, which sealing piston cooperates with a sealing face 105 of the housing 100 via a conical surface 131.

Instead of the conical face 131, a spherical face may cooperate with a sealing face of the housing. A pressure spring 140 is mounted between a collar 132 and the radially outward-projecting sealing face 105, so that the sealing piston 130 is pressed in the axial direction against the pressure piston 120. In the illustrated example a transmission body, such as a ball 110, is mounted in appropriate recesses 121, 133 between the sealing piston 130 and the pressure piston 120. This ball 110 is intended to compensate for tolerance discrepancies between the bores 101 and 102.

In the axial extension to the bore 101, a further stepped bore 106 with a threaded connection 107 is provided in the housing, the pressure medium line 9 coming from the transmission piston unit 22 being connected to the threaded connection 107 via the connection 92. Transverse to the bore 101 in the region of the sealing piston 130 and the pressure spring 140, a second pressure medium connection 108 is provided, which permits connection to the receiver piston unit 32 via the pressure medium line 9. In the same region, a further connection 109 is provided transverse to the bore 101 for a ventilator 160, such as is known from brake medium circuits. The piston chamber 151 of the larger piston 150 of the bore 102 is also vented via a ventilator 170.The compressed air circuit supplied via the compressed air connection 104 to the locking valve 10, is sealed by seals 122 and 152 relative to the pressure medium circuit which is supplied via the connections 107, 108.

The locking valve operates as followss- In the indicated postion, in which no air pressure is applied to the compressed air connection 104, the sealing piston 130 is held by the spring 140 in the position shown. Thus a free passage is created between the connection 92 and the pressure medium connection 108, as is shown in Figure 1. Each actuation of the clutch pedal 2 in Figure 1 is transmitted in this position via the transmitter piston 21 and the receiver piston 31 to the clutch 3. If in connection with the actuation of the clutch pedal 2, the switch 23 is closed, as has already been described with reference to Figure 1, the locking valve 1, 10 is actuated with compressed air via the connection 104.The double piston 120/150 is thereby moved to the left, and the free passage from connection 92 to the pressure medium connection 108 is interrupted via the sealing piston 130 and the sealing face 105. The transmission from the double piston 120/150 to the sealing piston 130 is effected in this case via the ball 110. While the pasage from connection 108 to connection 92 is locked, the pressure of the sealing piston 130 can be superpressured with the clutch pedal 2 and the transmitter piston 21, so that in emergencies it is always possible to open or disengage the clutch 3.

Figure 3 shows a section through an alternative form of locking valve 10 in the region of its connection 92 to the pressure medium line 9, which substantially corresponds to the locking valve shown in Figure 2. A sealing piston 180 of this locking valve 10 is formed as a hollow piston and receives in its interior an axially displaceable valve ball 181, which is pressed via a spring 182 against a valve seat 183 provided in the sealing piston 180. From the stepped bore 106, which is connected to the transmitter piston unit 22 via the pressure medium line 9, a pressure acts on the valve ball 181 via a bore 184 provided on the end face of the sealing piston 180. Furthermore, the sealing piston 180 has radial bores 185 which communicate with the pressure medium connection 108. The structural elements 181 to 185 act as a non-return valve, which permits the clutch 3 to be disengaged by the locking valve 10 with slight actuating force on the clutch pedal 2 even when the pressure medium line 9 is locked.

This is a safety function whereby it should always be possible to open the clutch 3 in emgergencies.

Claims

CLAINS

1. In an auxiliary power operated clutch and gear-changing device for a motor vehicle in which a gear change in the gearbox is controlled by the driver by means of the operation of a clutch pedal and a response signal is transmitted to the driver when the gear is engaged in the gearbox after the change, a safety device being mounted in a pressure line connecting a transmitter cylinder mechanically linked to the clutch pedal and a receiver cylinder for actuating the clutch, the safety device providing a flow path from the transmitter cylinder to the receiver cylinder when the gear is not engaged, but being locked in the opposite direction from the receiver cylinder to the transmitter cylinder, the safety device comprising a locking valve for the clutch actuated by compressed air, and the locking valve also being changed via control devices and the compressed air used to actuate a gear changing cylinder.

2. A safety device as claimed in claim 1 wherein the locking valve is changed from its flow position into its locked position direct via a switch mounted on the clutch pedal and a magnetic valve actuated thereby, or via an electronic control device.

3. A safety device as claimed in claim 2 wherein the locking valve comprises a stepped pressure piston which is mounted in a correspondingly stepped bore in a housing the end face of the larger borer being covered by a plate which has a compressed air connection thereto, a sealing piston being mounted in an axial extension of the bore of smaller diameter, the sealing piston having a spherical/conical face which cooperates with a sealing face on the housing, a further stepped bore in an axial extension of said bore of smaller diameter, said further bore having a threaded connection to which a pressure line leading to the transmitter piston unit is connectable, and a second pressure medium connection mounted transverse to the further bore in the region of the sealing piston connectable to the receiver piston unit.

4. A safety device as claimed in claim 3 wherein a pressure spring is mounted in an axial extension between a collar on the sealing piston and the housing.

5. A safety device as claimed in claim 4 wherein a transmission body is mounted between the pressure piston and the sealing piston.

6. A safety device as claimed in claim 5 wherein a ball is mounted in a respective recess in the pressure piston and the sealing piston.

7. A safety device as claimed in claim 4 wherein a non-return valve is mounted inside the sealing piston and operable to open a by-pass to the section of the pressure medium line connected to the receiver piston unit when pressure rises in the section of the pressure medium line connected to the transmitter piston unit.

8. A safety device as claimed in claim 7 wherein the pressure piston is hollow and has a ball valve located therein which is displaceable axially towards the stepped bore via a pressure spring, said ball valve lifting from a valve seat when pressure is applied to the end face of the sealing piston and opening a by-pass between an end-face bore and radial bores.

9. A safety device as claimed in claim 3 wherein an electromagnetic pilot valve controlled by the electronic control device is mounted inside the compressed air channel which is directly connected to a pressure medium source.

10. A safety device for an axially power operated clutch and gear changing device for a motor vehicle substantially as herein described with reference to the accompanying drawings.

11. An auxiliary power operated clutch and gear-changing device for a motor vehicle in which a gear change in the gearbox is controlled by the driver by means of the operation of a clutch pedal and a response signal is transmitted to the driver when the gear is engaged in the gearbox after the change, wherein, in the pressure line between the transmitter piston mechanically connected to the clutch pedal and a receiver cylinder for actuating the clutch, a safety device is additionally mounted via which the pressure line has a flow path from the transmitter cylinder to the receiver cylinder when the gear is not engaged, and is locked in the opposite direction from the receiver cylinder to the transmitter cylinder, characterised in that the safety device is a locking valve for the clutch actuated by compressed air, and the locking valve is also changed via the control devices and the compressed air used for moving a gear changing cylinder.

12. An auxiliary power operated clutch and gear-changing device according to claim 11 wherein the locking valve for the clutch is changed from its flow position into its locked position direct via a switch mounted on the clutch pedal and a magnetic valve actuated thereby, or via an electronic control device

13.An auxiliary power operated clutch and gear-changing device according to claim 12, wherein the clutch locking valve consists of a stepped pressure piston which is mounted in a correspondingly stepped bore in a housing, the end face of the large bore being covered by a plate which has a central compressed air connection which is connected to a compressed air line a a seling piston being mounted in the bore of smaller diameter in a further axial extension thereof, said sealing piston having a spherical/conical face which cooperates with a sealing face on the housing, a further stepped bore being provided in said further axial extension of the bore and having a threaded connection, to which the connection of the pressure line leading to the transmitter piston unit is connected and a second pressure medium connection mounted transverse to the bore in the region of the sealing piston which permits connection to the receiver piston unit.

14. An auxiliary power operated clutch and gear-changing device according to claim 13 wherein a pressure spring is mounted in an axial extension between a collar on the sealing piston and the housing.

15. An auxiliary power operated clutch and gear-changing device according to claim 14 wherein a transmission body is mounted between the pressure piston and the sealing piston.

16. An auxiliary power operated clutch and gear-changing device according to claim 15 wherein a ball is mounted in a respective recess in the pressure piston and the sealing piston.

17. An auxiliary power operated clutch and gear-changing device according to claim 14 wherein a non-return valve is mounted inside the sealing piston, which non-return valve opens a by-pass to the section of the pressure medium line connected to the receiver piston unit when pressure rises in the section of the pressure medium line connected to the transmitter piston unit.

18. An auxiliary power operated clutch and gear-changing device according to claim 17 wherein the pressure piston is formed as a hollow piston and has in its interior a valve ball which is displaceable axially towards the stepped bore via a pressure spring, and which lifts from a valve seat when pressure is applied to the end face of the sealing piston and which opens a by-pass between an end-face bore and radial bores.

19. An auxiliary power operated clutch and gear-changing device according to claim 13 wherein an electromagnetic pilot valve controlled by the electronic control device is mounted inside the compressed air line which is directly connected to a pressure medium source.

20. An auxiliary power operated clutch and gear-changing device substantially as herein described with reference to the accompanying drawings.