GB2033986A

GB2033986A - Dual Clutch Control Device for a Variable Ratio Gear

Info

Publication number: GB2033986A
Application number: GB7937210A
Authority: GB
Original assignee: Kloeckner Humboldt Deutz AG
Current assignee: Kloeckner Humboldt Deutz AG
Priority date: 1978-10-30
Filing date: 1979-10-26
Publication date: 1980-05-29
Also published as: DE2847123C2; FR2440497A1; GB2033986B; FR2440497B1; DE2847123A1

Abstract

A control device for effecting the transfer of drive progressively between a first clutch (46) biased towards a disengaged condition and a second clutch (47) biased towards an engaged condition includes a first valve (18) having a first valve member (23) movable to vary the supply of pressurized fluid from the first valve (18) to a second valve via a second valve supply line (33) and the second valve having a second valve member (32) which is selectively movable between first and second positions to effect drive transfer between the clutches, the second valve member (32) when its first position placing clutch supply lines (44, 45) in communication with the supply in (33) of the second valve to pressurize both clutches, thus engaging the first clutch (46), and when in its second position connecting the clutch supply lines (44, 45) to a fluid return line (48) to depressurize the clutches, thus engaging the second clutch (47), the first valve (18) being self-regulating accordance with the pressure in the clutch supply lines (44, 45) so that as pressure builds up in said clutch supply lines due to movement of the second valve member (32) to its first position the first valve member (23) is progressively moved to reduce the supply of fluid to the second valve. <IMAGE>

Description

SPECIFICATION Dual Clutch Control Device This invention relates to a control device for effecting the transfer of drive progressively from a first clutch to a second clutch and vice versa, the first clutch being biased towards a disengaged condition but being arranged to be engaged by the supply to it of pressurized fluid, and the second of the clutches being biased towards an engaged condition but being arranged to be disengaged by the supply to it of pressurized fluid.

Such control devices are used in hot shift dual clutch gear transmissions of vehicles.

An aim of the invention is to provide a simple, effective, and reliable control device for the purpose specified in the opening paragraph, and with this aim in view the invention is directed to a control device including two valves, the first valve having a first valve member movable to vary the supply of pressurized fluid from the first valve to the second valve via a second valve supply line and the second valve having a second valve member which is selectively movable between first and second positions to effect drive transfer between the clutches, the second valve member when in its first position placing clutch supply lines in communication with the supply line of the second valve to pressurize both clutches, and when in its second position connecting the clutch supply lines to a fluid return line to depressurize the clutches, the first valve being self-regulating in accordance with the pressure in the clutch supply lines so that as pressure builds up in said clutch supply lines due to movement of the second valve member to its first position the first valve member is progressively moved to reduce the supply of fluid to the second valve.

A control device according to the invention is effective to transfer drive from one clutch to the other completely and rapidly.

The second valve member which effects the transfer of drive can be a simple sliding member of the hydraulic two-position type. Such a sliding member can be produced at reasonable cost and, in addition, it has a relatively small flow resistance combined with a short gear-change movement.

In order to avoid shock during the operation of the operation of the clutches, it is appropriate to incorporate a restriction in the flow return line.

A preferred embodiment of a control device according to the invention and arranged to control a hot shift dual clutch gear box will now be described with reference to the accompanying drawing.

The illustrated control device comprises a block 1 connected to a fluid pressure medium pump 3 by a line 2. The intake side of pump 3 is connected to a fluid reservoir 4. In the block 1 line 2 leads to the annular grooves 6 and 7 of a pressure maintenance valve 5. Groove 6 is formed in a sliding valve member 8, and groove 7 is formed in a bore in which the valve member 8 slides. Inside the sliding valve member 8 these grooves 6 and 7 communicate with a cylindrical space 9 defined between a bore in member 8 and one end of a small piston 10. The other end of piston 10 is supported on the block 1. The sliding valve member 8 is biased on the side remote from the piston 10 by a control spring 11.An annular groove 12 which comes into communication with the annular groove 7 when the valve sliding member 8 is displaced upwardly against the force of the control spring 11 is connected to a line 14 leading away from the block 1. A line 1 5 branching off from line 2 leads to an annular groove 1 6 of a first valve 18.

One working space 19 of the valve 18 contains an axially-displaceable control piston 20 which, on its side facing away from the working space 19, is supported against a controlling sliding valve member 23 by a control spring 21. The valve member 23 has a central annular groove 24 and is seated in a guide bore 25 in which it can move axially. This guide bore contains three adjacent annular grooves 16, 26 and 27, of which the last communicates directly with the reservoir 4. A line 30 incorporating a restriction 31 connects a space 29 located on the left-hand end-face of the valve member 23 to a line 33 leading from the annular groove 26 to a second valve having a gear-changing sliding valve member 32 movable and will to effect drive transfer between clutches 46 and 47.

The valve member 32 is axially slidable in a guide bore 35 of the block 1 and can be retained by a spring-loaded detent 36 in each of two positions to which the valve member is selectively movable. Three annular grooves 37, 38, 39 are arranged side by side in the guide bore 35 and two annular grooves 40 and 41 are arranged in the gear-changing sliding member 32. The annular groove 37 is connected to the supply line 33 of the second valve, while the annular groove 38 is connected both to the working space 1 9 of the pressure control valve 1 8 by a pressure pickoff line 42 incorporating a restriction 43 and also to the clutches 46 and 47 by clutch supply pressure lines 44 and 45. The annular groove 39 is connected to the reservoir 4 by a line 48 incorporating a restriction 49.The first clutch 46 is constructed such that supply of pressure medium causes it to become engaged while spring force causes it to be disengaged while the second clutch 47, conversely, is engaged by spring pressure and is disengaged by pressure medium.

When the pressure medium pump 3 is actuated the pressure medium which it conveys passes through the line 2 to the pressure maintenance valve 5. When pressure in the line 2 reaches a certain valve, the valve member 8 is raised by the pressure in chamber 9 until fluid can bleed away via line 14 and grooves 12, 6 and 7.

Thus, the valve 5 maintains the pressure in line 1 5 at a desired value. Pressure in the line 1 5 is conveyed to the annular space 1 6 of the first valve 18. The valve member 23 permits the flow of pressure medium through the annular grooves 24, 26 to the line 33 and to the annular groove 37 of the second valve. With the gear-changing sliding valve member 32 in its position shown in the drawing, i.e. in its right-hand operational position, pressure medium can pass from the annular groove 37 through the succeeding annular grooves 40 and 38 and through the pressure lines 44 and 45 to the two clutches 46 and 47. The build-up of pressure in the line system and in the clutches 46, 47 caused engagement of the clutch 46 and a simultaneous disengagement of the clutch 47.Simultaneously with the pressure build-up in the clutches 46 and 47, pressure also builds up in the pick-off line 42 to produce a build-up of pressure in the working space 19 of the first valve 1 8. The control piston 20 is thus moved to the left against the action of the control spring 21 in correspondence with the increase in pressure in the working space 1 9. The valve member 23 is also moved to the left via the control spring 21 and, ultimately, when a certain pre-determined pressure is reached at the clutches 46 and 47 and in the working space 19, the connection between the annular grooves 1 6 and 26 is interrupted by the sliding member 23.

This initially stops the supply of pressure media to the clutches 46 and 47. Pressure medium which has passed through the restriction 31 and the line 30 into the space 29 counters the leftward movements of the controlling sliding member 23 and more especially dampens chatter of the valve member 23. It will thus be appreciated that the first valve is self-regulating in accordance with pressure in the pick-off line.

When the gear-changing sliding member 32 is changed over from the operational position shown to the other operational position, line 33 is isolated from lines 42 and 44, 45 and these lines are connected to the reservoir 4 via a flow return line 48 incorporating a restriction 49. The result is that no pressure is applied to the two clutches 46 and 47 and clutch 46 is disengaged while clutch 47 is engaged by spring force. In addition, the pressure in the working space 1 9 of the valve 1 8 falls and, consequently, the controlling piston 20 moves to the right into the starting position under the action of the control spring 21.

The control device in accordance with the invention is marked by a simple method of construction which requires a relatively small constructional space. Timing of the pressure build-up and relief control in the clutches 46 and 47 can be regulated by an appropriate operation of the gear-changing sliding member 32 during gear-changing.

Claims

1. A control device for effecting the transfer of drive progressively from a first clutch to a second clutch and vice versa, the first clutch being biased towards a disengaged condition but being arranged to be engaged by the supply to it of pressurized fluid, and the second of the clutches being biased towards an engaged condition but being arranged to be disengaged by the supply to it of pressurized fluid, the control device including two valves, the first valve having a first valve member movable to vary the supply of pressurized fluid from the first valve to the second valve via a second valve supply line, and the second valve having a second valve member which is selectively movable between first and second positions to effect drive transfer between the clutches, the second valve member when in its first position placing clutch supply lines in communication with the supply line of the second valve to pressurize both clutches, and when in its second position connecting the clutch supply lines to a fluid return line to depressurize the clutches, the first valve being self-regulating in accordance with the pressure in the clutch supply lines so that as pressure builds up in said clutch supply lines due to movement of the second valve member to its first position the first valve member is progressively moved to reduce the supply of fluid to the second valve.

2. A control device according to claim 1, in which the position of the first valve member is controlled in accordance with the pressurize of fluid in a pick-off line, and in which the second valve member when in its first position places the second valve supply line, the clutch supply lines, and the pick-off line in communication with each other, and when in its second position places the clutch supply lines, the pick-off line, and the fluid return line in communication with each other.

3. A control device according to claim 2, in which the pick-off line includes a restriction to reduce the sensitivity of the self regulation of the first valve.

4. A control device in accordance with claim 2 or claim 3, in which the first valve member engages a piston via a compression spring, and in which the piston movable in accordance with the pressure in the pick-off line.

5. A control device according to claim 4, in which the side of the first valve member which is remote from the piston communicates with the second valve supply line via a passage incorporating a restriction.

6. A control device according to any preceding claim, in which the fluid return line incorporates a restriction.

7. A control device according to any preceding claim in which fluid is fed to the first valve at a controlled pressure.

8. A control device substantially as described herein with reference to the accompanying drawings.

9. A variable ratio gear both including a dual clutch drive controlled by a control device according to any preceding claim.