WO2003014599A1

WO2003014599A1 - Hydraulic control systems

Info

Publication number: WO2003014599A1
Application number: PCT/DE2002/002747
Authority: WO
Inventors: Charles John Jones; Eugene M. O'sullivan
Original assignee: Luk Lamellen Und Kupplungsbau Beteiligungs Kg
Priority date: 2001-07-31
Filing date: 2002-07-26
Publication date: 2003-02-20
Also published as: GB2378489A; ITMI20021702A1; DE10234070A1; GB0118600D0; JP2004537022A; DE10293562D2; FR2828662A1

Abstract

A method for operating a hydraulic control system for the speed selection mechanism on a motor vehicle with first and second double-acting hydraulic actuators (114,115) and a main control valve (150), which is suitable for the selected connection of one side of the hydraulic actuator to a supply source (275) with pressurised hydraulic fluid, or to a volume equalisation vessel (278).

Description

HYDRAULIC CONTROL SYSTEMS

The present invention relates to hydraulic control systems and, more particularly, to a hydraulic control system for operating a gear shift mechanism of an automatic transmission system of a motor vehicle.

In hydraulic control systems for operating gear shift mechanisms of automatic transmission systems, such as those disclosed in GB2308413 and GB2339249, the disclosure of which is incorporated by reference and the content of which is expressly cited in the disclosure of the present application, a master control solenoid valve controls the connection of the gear actuators and secondary solenoid valves with the supply source of pressurized hydraulic fluid or with a volume compensation vessel, wherein the secondary valves selectively connect one side of the actuator to the main control valve or to the volume expansion vessel. In such systems, the main control valve normally connects the actuator and secondary valves to the volume expansion tank when it is not energized. The secondary valves normally connect one side of the actuators to the surge tank when they are not energized and are movable to a zero position between the non-energized position and a fully energized position where the secondary valves close one side of the actuators.

In such systems, if they do not change gear, the main control solenoid valve and the secondary valves are not energized. When the gear change is in progress, the main control valve is either fully energized or is current controlled using a feedback control system that depends on the fluid pressure in the hydraulic control system. The secondary valves are flow controlled using a feedback control system that depends on the actuator position.

The speed and repeatability of the main control valve and secondary valves are critical, especially in a loaded gear change, which is typically a gear change in the acceleration phase of the vehicle. However, valves of the type used for the main control valve and the secondary valves of such systems can show slow or inconsistent responsiveness when feedback controlled due to:

Stiction of the valves after they have been in a fixed (unexcited) position for a period of time;

Response of the electromagnets for retraction; and

Response of the valves when moving from the rest position of the valve to its control position.

In these systems, a dedicated clutch control solenoid valve is provided to control clutch engagement and disengagement during a gear change. Upon initiation of a gear shift, the clutch control solenoid is first energized to disengage the clutch, with the main control valve and secondary valves of the gear engagement mechanism not energized to effect the gear shift until the clutch is disengaged at least to the pressure point at which it stops transmitting torque.

The present invention provides a modification to the mode of operation of a hydraulic control system in which the responsiveness and the durability of the gear change process can be improved.

In accordance with one aspect of the present invention for an operating method of a hydraulic control system for the gear shift mechanism of a motor vehicle, the control system includes first and second double-acting hydraulic actuators, a main control valve, for selectively connecting one side of the hydraulic actuators to a supply source of pressurized hydraulic fluid or to a volume compensation vessel is suitable first and second secondary valves, each being adapted to connect to the other side of the first and second actuators, respectively, with the main control valve or the volume compensation vessel, a clutch control solenoid valve for controlling the engagement and disengagement of a vehicle clutch, and an electronic control unit for selectively energizing the clutch control valve, the main control valve and / or the secondary valves to disengage the clutch, disengage one gear and engage another gear and re-energize the clutch, wherein when the main control valve is de-energized, the actuators and secondary control valves are connected to the volume compensation vessel and when the main control valve is energized is, the actuators and secondary control valves are connected to the supply source of the pressurized hydraulic fluid, the secondary valves, when de-energized, connect the other side of the actuators to the volume compensation vessel and, we When fully excited, connect the other side of the actuator to the main control valve, the secondary valves having a partially excited zero position in which they block the other side of the actuator from both the main control valve and the volume compensation vessel, the operating method comprising that upon initiation of a gear shift, the control unit energizes the clutch control valve to disengage the clutch, the control unit reducing the clutch torque to zero.

applies a current pulse to the secondary solenoid valves while the main control valve remains de-energized;

applies a current to the secondary solenoid valves to keep them in their zero positions;

applies a current pulse to the main control valve while the secondary valves are in their zero positions;

applies a current pulse to the main control valve by a predetermined one

Provide pressure in the hydraulic control system; the secondary control valves are energized as necessary to disengage one gear and engage another gear when the clutch torque reaches zero; and

the clutch control valve is de-energized to engage the clutch again when the other gear is engaged.

Timing the secondary valves and the main control valve, as described above, frees the valves to the extent that they respond quickly and consistently to control signals from the control unit. While the main control valve is de-energized and connects the secondary valves to the surge tank when the current pulse is applied to the secondary valves, the movement of the secondary valves has no effect on the pressure applied across the actuators, so there is no movement arises. Furthermore, when the secondary valves are in the zero position, they hydraulically lock the actuators so that the pulsing of the main control valve and pressurization of the hydraulic control system will not move the actuators until the secondary valves are on one side or move the other side of the zero position.

According to a preferred embodiment of the present invention, the time taken to reduce the clutch torque to zero from the initiation of the gear change is typically on the order of 250 ms. The pulse that is applied to the secondary valves is preferably at the level of the maximum electromagnetic excitation current for a duration of the order of 100 ms and the pulse that acts on the main control valve is the maximum electromagnetic excitation current for a duration that is sufficient to increase pressure in the hydraulic control circuit, which is typically on the order of 50 ms.

The invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 shows a semi-automatic transmission system using a hydraulic circuit according to the present invention;

FIG. 2 shows a gear shift control link and the associated shift guides as used in the transmission system shown in FIG. 1;

Figure 3 shows a hydraulic control circuit for the gear engagement mechanism of the transmission system shown in Figure 1 in the form of a circuit diagram;

Figure 4 shows a schematic partial sectional view of the clutch control valves used in the hydraulic actuation system shown in Figure 3 in a second position;

Figure 5 shows a view similar to that of the clutch control valve of Figure 4 in a third position; and

FIG. 6 shows representations of the energized state of the solenoid valves, the clutch position and the gear engagement state for the hydraulic control system shown in FIG. 3.

Fig. 1 of the accompanying drawings shows a motor 10 with a starter and attached starter circuit 10a, which is coupled by the main drive friction clutch 14 to a multi-stage, synchronized engaging transmission of the type with countershaft 12 via a transmission drive shaft 15. Fuel is supplied to the engine via a throttle 16, which includes a throttle valve 18 which is actuated by an accelerator pedal 19. The invention is equally applicable to electronic or mechanical gasoline or diesel injection engines.

The clutch 14 is engaged / disengaged by a release fork 20 which is actuated by a hydraulic follower cylinder 22 under the control of a clutch actuator control means 38. A gearshift lever 24 actuates a control link 50 which has two extensions 51 and 52 which are connected by a transverse guide 53 which extends between the end of extension 52 and the middle between the two ends of the extension 51. The control link 50 defines five positions; "R" at the end of the extension 52; "N" between the ends of the transverse guide 53; "S" at the interface of extension 51 with transverse guide 53; and "+" and "-" at the outer ends of extension 51. In extension 51, the lever is biased to the middle position "S". The "N" position of the shift lever 24 corresponds to idling; "R" corresponds to the selection of the reverse gear; "S" corresponds to the selection of a forward drive mode; the brief movement of the lever to the "+" position provides a command to shift the transmission into the next higher gear; and momentarily moving the lever to the "-" position provides a command to shift the transmission to the next lower gear.

The positions of the lever 24 are detected by a series of sensors, for example miniature switches or optical sensors, which are arranged around the control link 50. The signals from the sensors are fed to an electronic control unit 36. As described in more detail below, the signals from the control unit 36 control a transmission engagement mechanism 25 which engages the gear stages of the transmission 12 according to the movement of the shift lever 24 by the driver.

In addition to the signals from the gear shift lever 24, the control unit 36 receives signals from:

Sensor 19a, which indicates the degree of depression of the accelerator pedal 19;

Sensor 30, which indicates the degree of opening of the throttle control valve 18;

Sensor 26 which designates the engine speed;

Sensor 42, which indicates the speed of the driven clutch disc; Sensor 34, which indicates the position of the clutch follower cylinder; and

Sensor 32, which designates the selected gear.

The control unit 36 uses the signals from these sensors to control the actuation of the clutch 14 during start-up from the rest phase to the gear changes, for example as described in the patent specifications EP0038113, EP0043660, EP0059035, EP0101220 and WO92 / 13208, the content of which is expressly described is incorporated into the disclosure content of the present invention.

In addition to the sensors mentioned above, the control unit 36 also receives signals from a vehicle speed sensor 57, the ignition switch 54 and the brake switch 56 belonging to the main brake system, for example the foot brake 58 of the vehicle.

A buzzer 55 is connected to the control unit 36 in order to warn the driver or to indicate him when certain operating conditions occur. In addition to the buzzer 55 or in its place, a flashing warning light or other indicator can be used. A gear indicator 60 is also provided to indicate the selected gear level.

As shown in FIG. 2, the gear shift mechanism 25 includes three shifting rulers 111, 112, 113 which are attached in parallel to each other for movement in an axial direction. Each shift ruler 111, 112, 113 is attached to two of the shift stages of the transmission 12 via a selection fork and a synchronous engagement unit in a conventional manner, so that movement of the shift rulers 111, 112, 113 in an axial direction engages one of the associated shift stages and axial movement of the switching rulers 111, 112, 113 in the opposite axial direction causes the other of the assigned switching stages to engage.

Typically, the first and second gears are assigned to the shift ruler 111, so that axial movement of the shift ruler 111 in a first direction engages the first gear or axial movement of the shift rulers 111 in a second direction causes the second gear to be engaged; the third and fourth gears are associated with the shift ruler 112 so that axial movement of the shift ruler 112 in the first direction engages the third gear or axial movement of the shift ruler 112 in a second direction causes the fourth gear to engage; and the fifth gear and the reverse gear are assigned to the shift ruler 113, so that axial movement of the shift ruler 113 in the first direction brings about engagement of the fifth gear, while axial movement of the shift ruler 113 in the second direction engages the reverse gear.

A shift finger 110 is mounted for movement in a first direction X transverse to the axes of the shifting rulers 111, 112, 113 and in a second direction Y for movement axially to the shifting rulers 111, 112 and 113. The shift finger 110 can therefore be moved in the direction X along a neutral plane A-B so that it can be indexed and engaged with a selected rail of the shifting rulers 111, 112, 113. The shift finger 110 can then be moved in the Y direction in order to move the occupied rail 111, 112, 113 axially in one of the two directions in order to engage one of the gears assigned to it.

As shown in FIG. 3, a hydraulic control system comprises an accumulator 275 and a volume compensation vessel 278 for a hydraulic fluid. An electrically operated pump 223 is available to charge the pressure accumulator 275 via a check valve 276. A pressure transducer 282 is available to measure the pressure in the pressure accumulator and to send signals to the control unit 36 which correspond to it. A pressure relief valve 280 is provided between the outlet of the pump 223 and a volume expansion tank 278 to ensure that the pressure provided by the pump 223 does not exceed a predetermined maximum pressure. The pump 223 operated with an electric motor is controlled by the control unit 36 on the basis of the signals from the pressure measurement transducer 282 in order to keep the pressure accumulator 275 at a suitable pressure. The clutch follower cylinder 22 is selected connected to the pressure accumulator 275 or the volume compensation vessel 278 by means of a clutch control valve 120 operated via an electromagnet. The clutch control valve 120 includes a housing 122 that defines a valve cylinder 124. A spacer ring 126 is slidably arranged in the valve cylinder 124, the spacer ring 126 having two axially spaced circumferential webs 130, 132 which act in a sealing manner in the valve cylinder 124. An electromagnet 134 acts on one end of the spacer ring 126 so that when the electromagnet 134 is energized, the spacer ring 126 is moved axially in the valve cylinder 124 against a load which is exerted by a compression spring 136 which acts on the opposite end of the spacer ring 126.

An inlet 138 into the valve cylinder 124 of the valve 120 is connected to the pressure accumulator 275. An outlet 140 from the valve cylinder 124 of the clutch control valve 120 is connected to the volume compensation vessel 278. An opening 148 from the valve cylinder 124 is connected to the clutch follower cylinder 22. The clutch follower cylinder 22 comprises a piston 62 which is displaceable in a cylinder 64. An engagement rod 66 extends from one side of the piston 62 and is connected to the fork 20 to disengage the clutch 14 when the engagement rod 66 is extended from the cylinder 64. The opening 148 of the clutch control valve 120 is connected to the cylinder 64 of the follower cylinder 22 on the side of the piston 62, which is remote from the engagement rod 66, through the opening 68.

FIG. 3 shows the clutch control valve 120 in an unexcited position, in which the clutch follower cylinder 22 is connected to the volume compensation vessel 278 via the opening 148 and the outlet 140 of the clutch control valve 120 and the clutch 14 is engaged.

As shown in FIG. 4, the electromagnet 34 can be energized to move the spacer ring 126 to a second or zero position, in which the web 132 closes the opening 148 and the clutch follower cylinder 22 both from the pressure accumulator 275 and from the volume compensation vessel 278 separates. When the excitation current at the electromagnet 134 is increased, the spacer ring 126 moves to a third position. tion, as shown in Fig. 5, in which the follower cylinder 22 is connected to the pressure accumulator 275 via the openings 148 and 138 of the clutch control valve 120.

Movement of the shift finger 110 in a first direction X along the neutral plane AB of the shift control link shown in FIG. 2 for aligning the shift finger 110 with one of the shift rulers 111, 112 or 113 and the resulting selection of the gear pair that is assigned to that shift ruler controlled by a first actuator 114 operated by fluid pressure. The shift finger 110 can then be moved in a Y direction by means of a second actuator 115 operated by fluid pressure to axially move the shifting rulers 111, 112 or 113 in either direction to engage one of the gears associated therewith.

The actuators 114, 115 each comprise a double-acting plunger with an engagement rod 114a, or 115a, which is operatively connected to the shift finger 110. The engaging rod 114a extends from one side of the piston 116 of the actuator 114, so that the working area on the rod side of the piston 116 is smaller than on the opposite head side. The same applies to the actuator 115, wherein an engagement rod 115a extends from one side of the piston 117 of the actuator 114, so that the work-causing area on the rod side of the piston 117 is smaller than on the opposite head side.

The supply of hydraulic fluid to the rod and head sides of the pistons 116 and 117 is controlled by three electromagnetically operated valves 150, 152 and 154, a main control valve 150, a slide valve 152 and a selector valve 154. The valves 150, 152 and 154 are constructed similarly to the clutch control valve 120 and the same reference number is used for the same components. Valves 150, 152 and 154 are between a first rest position, as shown in FIG. 3, a partially excited second or zero position, which corresponds to that shown in FIG. 4, and a fully excited third position, which corresponds to that shown in FIG. 5, switchable. The inlet 138 of the main control valve 150 is with the accumulator 275 and the Outlets 140 of the valves 150, 152 and 154 are connected to the volume expansion tank 278.

The opening 148 of the main control valve 150 is connected to the rod side chambers of the pistons 116 and 117 of the actuators 114, 115 and to the inlets 138 of the slide and select valves 152, 154. The opening 148 of the slide valve 152 is connected to the head side chamber of the piston 117 of the actuator 115 and the opening 148 of the selector valve 154 is connected to the head side chamber of the piston 116 of the actuator 114.

A pressure transducer 170 is provided between the main control valve 150 and the valves 152 and 154 and the rod end chambers of the pistons 116 and 117.

Potentiometers 226 and 227 are connected to engagement rods 114a and 115a, respectively, to provide a signal indicating the position of the associated engagement rod. The signals from potentiometers 226 and 227 are provided to control unit 36 to provide an indication of engagement rods 114a and 115a for each of the gears of the transmission and also to indicate the position of engagement rod 115a when shift finger 110 is off neutral AB Fig. 2 is located. The transmission system can therefore be calibrated so that predetermined position signals from potentiometers 226 and 227 correspond to the engagement of each of the gears of transmission 15.

Measurements from potentiometers 226 and 227 can then be used by a closed loop system to control valves 150, 152 and 154 to move engagement rods 114a and 115a to the predetermined positions to engage the desired gear.

As shown in FIG. 6, when a gear change is initiated from the assumed 2nd gear to the 3rd gear, for example at time t _0, the clutch control valve 120 is energized to move it from the first position, shown in FIG. 3, to the third position 5, so that the follower cylinder 22 is connected to the pressure accumulator 275. is bound and the pressurized hydraulic fluid enters the follower cylinder 22 to disengage the clutch 14. Initially, clutch 14 is rapidly disengaged until the torque transmitted through clutch 14 drops to engine torque, and clutch 14 release rate is then controlled by switching valve 120 between the first and third positions to reduce the Follow engine torque, which is regulated by the engine operating system of the vehicle, thereby avoiding engine roar when clutch 14 is released.

At the same time t ₀ , a current pulse is applied to the switching and selection valves 152 and 154 to move the valves 152 and 154 from their first position, as shown in FIG. 3, to their third position, as shown in FIG. 5 move. During this pulse, which typically has a duration of 100 ms, during which the valves 152 and 154 connect the top sides of the pistons 116 and 117 to the main control valve 150, the main control valve remains de-energized, so that the opening 148 thereof via the outlet 140 to the volume compensation vessel 278 is connected. As a result, there is no pressure difference between pistons 116 and 117 to move actuators 114, 115. At the end of the bar at time t | an excitation current is applied to the solenoids 138 of valves 152 and 154 so that they are held in their second "zero position" as shown in Fig. 4. In this position, the tops of pistons 116 and 117 are closed, providing a hydraulic Provide a lock that prevents movement of the actuators 114, 115. At time ti, a current pulse is applied to the electromagnet 138 of the main control valve 150 so that the outlet 148 of the valve 150 is connected to the pressure accumulator 275. The pulse is applied to the Main control valve 150 is applied until the pressure on the piston rod sides of pistons 116 and 117 and inlets 138 of switch and select valves 152 and 154 begins to increase, as indicated by transducer 170, this process typically being on the order of 50 ms. The main control valve 150 is then energized at time t ₂ to control the valve 150 to a predetermined pressure k to the piston rod sides of the pistons 116 and 117 and the inlets 138 of the switching and selection valves 152 and 154. Although during the co-pulse assignment of the main control valve 150 and subsequently pressure is applied to the piston rod sides of the pistons 116 and 117, there is no movement of the actuators 114 and 115, since these are hydraulically locked by the valves 152 and 154. The specific predetermined pressure can be built up and maintained by switching the main control valve 150 between its first, second and third positions, as shown in FIGS. 3, 4 and 5, respectively.

At time t ₃ , after clutch 14 is disengaged to its pressure point (tp) at which it no longer transmits torque, shift control valve 152 is controlled to move the top of piston 117 with the volume expansion tank as in FIG. 3 shown, or to be connected to the pressure accumulator 275 via the main control valve 150, as shown in FIG. 5. The connection of the head side of the piston 117 to the volume compensation vessel 278 creates a pressure difference in the piston 117, which moves the piston 117 upward, as shown in FIG. 3, the liquid flowing out of the head side of the piston 117 into the volume expansion vessel 278 , The actuator piston rod 115a is thereby retracted, whereby the shift finger 110 is moved in a Y direction. The connection of the head side of the piston 117 to the pressure accumulator 275 via the main control valve 150 supplies both sides of the piston 117 with hydraulic fluid under pressure. While the pressure on both sides of piston 117 is equal, the difference in area of piston 117 causes piston 117 to move downward, as shown in Fig. 3, which causes actuator piston rod 115a to extend, with shift finger 110 moving in the opposite direction Moved towards Y. The shift control valve 152 is operated to shift the shift finger 110 in the Y direction and the shift ruler 111, 112, 113 thereby engaged from the position corresponding to the currently engaged gear to a position corresponding to the neutral plane AB corresponds to move. The shift control valve 152 is then moved to its zero position to lock the actuator 115 in a position at time t ₄ that corresponds to the neutral plane AB.

The selector control valve 154 is then operated in the manner described above to control the actuator 114 to move the shift finger 110 in the X direction to engage the shift ruler 111, 112, 113 associated with the intended gear. is not. The selector control valve 154 is then moved to its zero position at time t ₅ and the shift control valve 152 is controlled to move the shift finger 110 from the neutral plane AB to the position corresponding to the intended gear engagement. The shift control valve 152 is again moved to its zero position at time t ₆ when the intended gear has been engaged.

The clutch control valve 120 is then controlled to connect the slave cylinder 22 to the surge tank so that the clutch 14 can re-engage, the re-engagement being controlled in the known manner to provide smooth power consumption by the clutch control valve 120 is switched between the volume compensation vessel 278 and the pressure accumulator 275.

As soon as the clutch has been engaged at time t ₇ , the solenoid valves 120, 150, 152 and 154 are de-energized in order to be ready for the next gear change.

The timing of the main control valve 150 and the shift and select valves 152, 154 in the manner disclosed above overcomes any static friction in the valves so that they respond quickly and consistently to effect gear changes. The patent claims submitted with the application are proposals for formulation without prejudice for the achievement of further patent protection. The applicant reserves the right to claim further combinations of features previously only disclosed in the description and / or drawings.

Back-references used in subclaims indicate the further development of the subject matter of the main claim by the features of the respective subclaim; they are not to be understood as a waiver of the achievement of independent, objective protection for the combinations of features of the related subclaims.

Since the subjects of the subclaims can form independent inventions with regard to the state of the art on the priority date, the rin themselves to make them the subject of independent claims or declarations of division. They can furthermore also contain independent inventions which have a design which is independent of the objects of the preceding subclaims.

The exemplary embodiments are not to be understood as a restriction of the invention. Rather, numerous changes and modifications are possible within the scope of the present disclosure, in particular those variants, elements and combinations and / or materials which, for example, by combining or modifying individual ones in conjunction with those described in the general description and embodiments and the claims and features or elements or procedural steps contained in the drawings can be taken by the person skilled in the art with regard to the solution of the task and, through combinable features, lead to a new object or to new procedural steps or procedural step sequences, also insofar as they involve manufacturing, testing and working methods affect.

Claims

claims

1. A method of operating a hydraulic control system for the gear selection mechanism of a motor vehicle, the control system comprising first and second double-acting hydraulic actuators, a main control valve used to selectively connect one side of the hydraulic actuators to a supply source of pressurized hydraulic fluid or to a volume expansion tank is suitable, first and second secondary valves, each suitable for connecting to the other side of the first and second actuators with the main control valve or the volume expansion tank, a clutch control solenoid valve to control the engagement and disengagement of a vehicle clutch, and an electronic control unit for selected energizing the clutch control valve, the main control valve, and / or the secondary valves to disengage the clutch, disengage one gear and engage another gear, and re-engage the clutch rain, whereby when the main control valve is de-energized, the actuators and secondary control valves are connected to the volume compensation vessel and, when the main control valve is energized, the actuators and secondary control valves are connected to the supply source of the pressurized hydraulic fluid, the secondary valves, when de-energized, connect the other side of the actuators to the surge tank and, when fully excited, connect the other side of the actuator to the main control valve, the secondary valves having a partially excited zero position in which they both the other side of the actuator lock from the main control valve as well as from the volume compensation vessel, the operating method comprising, when a gear change is initiated, the control unit excites the clutch control valve to disengage the clutch, the control unit while the clutch torque is reduced to zero; applies a current pulse to the secondary solenoid valves while the main control valve remains de-energized;

applies a current pulse to the main control valve by a predetermined one

Provide pressure in the hydraulic control system;

the secondary control valves are energized as necessary to disengage one gear and engage another gear when the clutch torque reaches zero; and

2. The method of claim 1, wherein the secondary valves are pulsed for a period on the order of 100 ms.

3. The method of claim 1 or 2, wherein the main control valve is pulsed until the pressure in the hydraulic control circuit begins to rise.

4. The method of claim 3, in which the main control valve is pulsed for a period on the order of 50 ms.

5. The method according to any one of the preceding claims, in which a pulse of the maximum excitation current is applied to the main control valve and / or the secondary control valves. A method of operating a hydraulic control system for the gear selection mechanism of a motor vehicle, substantially as described herein and illustrated in, with reference to Figures 1 to 6 of the accompanying drawings.