KR102532020B1 - Protection method for hydrostatic clutch actuators, especially for vehicles - Google Patents

Abstract

The present invention relates to a method for protecting a hydrostatic clutch actuator comprising a hydrostatic pressure transmission section having a master cylinder (17), wherein the hydraulic fluid (18) is displaced for operation of the clutch (4) in the master cylinder (17). The pressure (p) of the hydraulic fluid (18) is determined and compared with the overpressure threshold (p _s ). In this method in which overpressure is prevented within the hydrostatic clutch actuator, the motion information of the clutch actuator 12 is analyzed when the overpressure threshold p _s is reached and, according to the motion information of the clutch actuator 12, the clutch actuator 12 ) causes the opening or closing of

Description

Protection method for hydrostatic clutch actuators, especially for vehicles

The present invention relates to a method for protecting a hydrostatic clutch actuator including a hydrostatic pressure transmission section having a master cylinder, in which hydraulic fluid is displaced for operation of a clutch in the master cylinder and the pressure of the hydraulic fluid is determined to determine an overpressure threshold and are compared

From DE 10 2011 085 127 A1 a method for controlling a dual clutch actuated by means of a hydrostatic clutch actuator is known. The hydrostatic clutch actuator includes a master cylinder, a slave cylinder, and a hydrostatic section between the master cylinder and the slave cylinder. It may be important to have a pressure limiting valve on each hydrostatic clutch actuator to limit it to a pre-provided maximum pressure value. However, these valves are usually omitted for reasons of cost and strategic reasons, since the pressure-limiting valve must be absolutely closed under normal circumstances and after an error situation, and in an error situation there is a gap between the pressure of the clutch actuator and the path. This is because unspecified displacement may occur in In the case of this device for operating the dual clutch, the hydrostatic clutch actuator further includes a pressure sensor for detecting a pressure value in the static hydraulic pressure section, wherein the control device stores and analyzes the pressure value detected by the pressure sensor Thus, it can be protected against overpressure.

A hydrostatic clutch actuator should be understood as an actuator having a static hydraulic pressure transmission section, such as a pressure line with hydraulic fluid, and the pressure of the hydraulic fluid is measured by a pressure sensor. The clutch is operated through the displacement of hydraulic fluid within the static hydraulic pressure transmission section. To operate the clutch, a piston within the master cylinder of the clutch actuator is controlled by an electric motor. In this way, the piston in the slave cylinder is actuated by the hydraulic fluid in the system. In this case, the piston of the slave cylinder acts on the lever spring peak of the disc spring, which then, when actuated, disengages the clutch plate from the clutch disc, thereby blocking transmission of the clutch torque to the clutch. A preloaded lever spring deactivates the clutch.

In the case of a clutch deactivated by a lever spring, the pressure rises to the maximum pressure value during the opening of the clutch and then drops again slightly.

In dual-clutch transmissions, the overpressure protection from the hydrostatic clutch actuator is such that the hydrostatic clutch actuator opens immediately when a pre-specified, very high pressure level is reached, until the pressure drops back below the pre-specified low pressure. It is done. This action is performed by the hydrostatic clutch actuator itself.

When a non-actuated closed clutch is combined with a hydrostatic clutch actuator, the clutch actuator can be moved to a high position by opening the clutch. In this case, the pressure maximum must necessarily be suppressed. In this open clutch position the clutch actuator can now be held longer. The pressure maximum can then rise due to rotational speed effects, wear on the friction partners of the clutch, and/or expansion of the hydraulic fluid. In case of temperature expansion, the clutch opens even fully through this effect, as a result of which the pressure rises strongly at the end of the pressure characteristic curve when the mechanical limit is reached. If the clutch is closed and the pressure minimum is higher than the permitted pressure threshold, the hydrostatic clutch actuator will in this case open the clutch actuator as quickly as possible. As a result, the pressure still rises further up to the pressure maximum, whereby the clutch actuator may be damaged.

An object of the present invention is to provide a method for protecting a hydrostatic clutch actuator, which can be used in a clutch having a lever spring (disc spring) actuated by the hydrostatic clutch actuator.

According to the present invention, this problem is solved by the fact that when an overpressure threshold is reached, the motion information of the clutch actuator is analyzed and an opening or closing of the clutch actuator is caused according to the motion information of the clutch actuator. Through simultaneous analysis of pressure and motion information, an overpressure situation can be reliably detected regardless of which direction the clutch actuator moves in the pressure characteristic curve, from which measures can be introduced to reduce the pressure occurring within the static hydraulic pressure section. . This method is not only effective for clutches with lever springs (disc springs), but can also be used for normally non-actuated open clutches and non-actuated closed clutches. In this case, the fluctuations on the pressure characteristic curve due to motion are much larger than other effects and the clutch actuator is held only in the fully closed position and fully open position.

Preferably, when the pressure is above the overpressure threshold and the clutch actuator is held in its position, the clutch actuator will move in the direction of the clutch being opened. Since this leads to the mechanical limit of the clutch actuator, it is important that the opening of the clutch actuator advantageously be set by the pressure maximum before reaching the overpressure threshold.

In one embodiment, if the clutch actuator's motion information indicates that the clutch actuator is opening the clutch, at which time the pressure is above the overpressure threshold, the clutch actuator will move in the direction of the clutch being closed.

In one alternative, if the clutch actuator's motion information indicates that the clutch actuator is closing the clutch starting from the open state, at which time the pressure is above the overpressure threshold, the clutch actuator will move in the direction of the clutch being opened. Thus, in this state, the clutch actuator is reliably protected against overpressure.

In one variant, the clutch actuator opens and closes based on reaching the overpressure threshold until a release pressure threshold less than the overpressure threshold is reached. This release pressure threshold, established through the continuously alternating opening and closing of the clutch actuator, allows the clutch actuator to operate in a pressure range that avoids overloading the system.

In one refinement, the position of the clutch actuator upon reaching the overpressure threshold is stored as a limit value, with the limit value being maintained upon opening and closing of the clutch actuator based on reaching the overpressure threshold value. This ensures that damage or destruction of the hydrostatic clutch actuator is prevented since the maximum pressure value based on the pre-provided position of the clutch actuator is not exceeded.

In one embodiment, after reaching the release pressure threshold, movement of the clutch actuator in the direction of the clutch that opens is permitted from the limit, or movement of the actuator in the direction of the clutch that closes is allowed up to the limit. Thereby, the hydrostatic clutch actuator operates in a pressure range that allows reliable and trouble-free operation of the clutch.

In one embodiment, the threshold of a clutch that is open increases over time, while the threshold of a clutch that is closed decreases over time. Since the range of motion of the clutch actuator is limited by the limit value, this range of motion changes over time, so that the clutch actuator does not reach the overpressure threshold.

The present invention allows multiple embodiments. One of these is explained in more detail by means of an embodiment shown in the drawings.

1 is a basic principle diagram of a hybrid driving unit.
2 is a basic principle diagram of a hydrostatic clutch operating system having a hydrostatic transmission section.
3 is a pressure-path characteristic curve of a hydrostatic clutch actuator.

1 shows a basic principle diagram of a drive train 1 of a hybrid vehicle. This drive train 1 comprises a combustion engine 2 and an electric motor 3 . Between the combustion engine 2 and the electric motor 3 a hybrid decoupling clutch 4 is arranged immediately after the combustion engine 2 . The combustion engine 2 and the hybrid decoupling clutch 4 are connected to each other via a crankshaft 5 . The electric motor 3 has a rotatable rotor 6 and a fixed stator 7 . The output shaft 8 of the hybrid split clutch is connected to a transmission 9, which is connected to a coupling element not shown in detail, for example a second clutch or rotational torque disposed between the electric motor 3 and the transmission 9. Includes converter. Transmission 9 transmits the torque generated by combustion engine 2 and/or electric motor 3 to drive wheels 10 of the hybrid vehicle. In this case, the electric motor 3 and transmission 9 form a transmission system 11 driven by a hydrostatic clutch actuator 12 . A hybrid decoupling clutch 4 disposed between the combustion engine 2 and the electric motor 3 is configured to start the combustion engine 2 using torque generated by the electric motor 3 while the hybrid vehicle is running. or closed for travel by the combustion engine 2 and the electric motor 3 driven during the boost operating mode. In this case, the hybrid decoupling clutch 4 actuated by a disc spring is actuated by a hydrostatic clutch actuator 12 . An electric motor (3) which, when starting the combustion engine (2) again by means of the electric motor (3), moves the hybrid vehicle by means of the drive wheel (10) without loss of comfort and at the same time also actually starts the combustion engine (2). Accurate knowledge of the clutch characteristic curve of the hybrid decoupling clutch 4, in which the clutch torque is plotted against the path of the hydrostatic clutch actuator 12, is necessary to ensure that sufficient torque is provided by .

A clutch actuation system 13 with a hydrostatic clutch actuator 12 is shown in FIG. 2 . The clutch actuation system 13 includes a control device 15 on the master side 14 , which drives the hydrostatic clutch actuator 12 . When the state of the hydrostatic clutch actuator 12 changes, the piston 16 is displaced to the right along the clutch actuator path in the master cylinder 17 to compress the hydraulic fluid 18 in the master cylinder 17, thereby A pressure p is formed in the master cylinder 17 and is transmitted to the slave cylinder 20 via the hydraulic fluid 18 via the hydraulic line 19 . The pressure p of the hydraulic fluid 18 in the slave cylinder 20 causes the sleeve piston 21 to change its path, which is transmitted to the hybrid separation clutch 4 to operate it. The pressure p in the master cylinder 17 is detected by the pressure sensor 22, while the path section s traveled by the hydrostatic clutch actuator 12 along the actuator path is determined by the path sensor 23. It is measured.

FIG. 3 shows the pressure p along the path s of the hydrostatic clutch actuator 12 , as detected by the pressure sensor 22 and path sensor 23 . As can be seen, in the non-actuated closed hybrid split clutch 4 actuated by the lever spring (disc spring), the pressure p does not behave linearly, because the pressure of the hybrid split clutch 4 This is because the pressure rises to the maximum value during opening and then decreases slightly again. In the upper segment of the hysteresis curve of the pressure characteristic curve proceeds from left to right during the opening of the inoperatively closed hybrid decoupling clutch 4 . The lower segment of the hysteresis curve of the pressure characteristic curve proceeds from right to left during the closing of the non-actuated closed hybrid decoupling clutch 4 . In clutches with few friction points, the hysteresis curve can run much narrower than shown in FIG. 3 .

In order to protect the hydrostatic clutch actuator 12 associated with a non-actuated closed clutch from overpressure, the pressure output via the pressure sensor 22 is compared by the control device 15 with an overpressure threshold p _s , as well as At the same time, if the overpressure threshold p _s is exceeded, the direction of movement of the clutch actuator 12 is analyzed. An intended opening or closing of the clutch actuator 12 results from this analysis.

If the clutch actuator 12 does not move from its final position after the closing movement and the pressure p measured by the pressure sensor 22 reaches the overpressure threshold p _s , then at the clutch-open end of the pressure characteristic curve It is assumed that a mechanical limit has been reached. The clutch actuator 12 is then opened, which means that the clutch actuator moves in the closing direction of the hybrid separation clutch 4 . When the clutch actuator 12 moves towards a higher position s in the pressure characteristic curve, this means that the hybrid decoupling clutch 4 opens and the clutch actuator 12 releases a pressure above the overpressure threshold p _s during this movement ( p), then the clutch actuator 12 is open, i.e. the hybrid decoupling clutch 4 is closed by the movement of the clutch actuator 12.

If the clutch actuator 12 moves towards the smaller position s, this corresponds to the closing of the hybrid decoupling clutch 4 starting from the open state, which in this case means reaching the overpressure threshold p _s , then In order to prevent a further rise in pressure p, the clutch actuator 12 is closed, i.e. the hybrid disengagement clutch 4 is opened.

When the clutch actuator opens, the opening and closing of the clutch actuator 12 based on reaching the overpressure threshold p _s , when the release pressure threshold p _F is reached or when the clutch actuator 12 closes It runs until the maximum value for this position is reached. In some cases, a minimum value of the release pressure threshold may be separately defined for the latter case. This release pressure threshold p _F is a pressure threshold starting from which the clutch actuator 12 is operated in a pressure range that is smaller than the overpressure threshold p _s and in which damage to the clutch actuator 12 is reliably prevented. indicates

When the overpressure threshold p _s is reached, the position of the clutch actuator 12 , which is stored as the limit value s _B in the control device 15 , is detected by the path sensor 23 . Upon further opening/closing of the clutch actuator 12 based on reaching the overpressure threshold p _s , the limit value s _B remains constant. This can reach the maximum at the position of the current limit value s _B(open) upon opening of the clutch actuator 12 after reaching the release pressure threshold p _F , whereas At the time of closing, the limit value s _B(closed) represents the minimum position of the clutch actuator 12 . In order to allow the clutch actuator 12 to operate normally again after setting the release pressure threshold value p _F , the limit value s _{B (open)} gradually rises over time, while the limit value s _{B (closed )} ) gradually lowers over time upon closing of the clutch actuator, whereby the clutch actuator 12 again obtains a greater range of motion.

Based on the proposed solution, the hydrostatic clutch actuator 12 is reliably protected against overpressure in combination with a non-actuated closed hybrid decoupling clutch 4 . This is especially important in the case of clutch systems designed with limit values. Through analysis of the pressure information and motion information of the hydrostatic clutch actuator 12 when the pressure limit value is reached, an intended opening or closing of the clutch actuator 12 to prevent overpressure damage is caused.

1 drivetrain
2 combustion engine
3 electric motor
4 hybrid split clutch
5 crankshaft
6 rotors
7 stator
8 output shaft
9 gearbox
10 driving wheel
11 transmission system
12 Hydrostatic Clutch Actuator
13 clutch actuation system
14 master side
15 control unit
16 piston
17 master cylinder
18 hydraulic fluid
19 hydraulic lines
20 slave cylinder
21 slave piston
22 pressure sensor
23 path sensor
p pressure
p _s overpressure threshold
p _F release pressure threshold
s _B limit value

Claims (8)

delete delete As a method of protecting a hydrostatic clutch actuator comprising a hydrostatic pressure transmission section with a master cylinder (17), the hydraulic fluid (18) is displaced for the operation of the clutch (4) in the master cylinder (17) and the hydraulic fluid (18 In the method in which the pressure (p) of ) is determined and compared with the overpressure threshold value ( _ps ), when the overpressure threshold value ( _ps ) is reached, the motion information of the clutch actuator 12 is analyzed and the clutch actuator 12 The opening or closing of the clutch actuator 12 is caused according to the motion information of
If the motion information of the clutch actuator 12 indicates that the clutch actuator 12 opens the clutch 4 at which time the pressure p exceeds the overpressure threshold p _s , the clutch actuator 12 is closed. A method for protecting a hydrostatic clutch actuator, characterized in that it moves in the direction of the clutch (4). As a method of protecting a hydrostatic clutch actuator comprising a hydrostatic pressure transmission section with a master cylinder (17), the hydraulic fluid (18) is displaced for the operation of the clutch (4) in the master cylinder (17) and the hydraulic fluid (18 In the method in which the pressure (p) of ) is determined and compared with the overpressure threshold value ( _ps ), when the overpressure threshold value ( _ps ) is reached, the motion information of the clutch actuator 12 is analyzed and the clutch actuator 12 The opening or closing of the clutch actuator 12 is caused according to the motion information of
If the motion information of the clutch actuator 12 indicates that the clutch actuator 12 closes the clutch 4 starting from the open state, at which time the pressure p exceeds the overpressure threshold p _s , the clutch actuator 12 (12) A method for protecting a hydrostatic clutch actuator, characterized in that it moves in the direction of the clutch (4) being opened. 5. The clutch actuator (12) according to claim 3 or 4, based on reaching the overpressure threshold ( _ps ), will reach a release pressure threshold (p _F ) smaller than the overpressure threshold ( _ps ). A method for protecting a hydrostatic clutch actuator, characterized in that it is opened and closed until 5. The clutch actuator (12) according to claim 3 or 4, wherein the position of the clutch actuator (12) is stored as a limit value when the overpressure threshold ( _ps ) is reached, wherein the clutch actuator (12) is based on the overpressure threshold ( _ps ) reached. A method for protecting a hydrostatic clutch actuator, characterized in that the limit value is kept constant during the opening and closing of (12). 6. The method according to claim 5, wherein the position of the clutch actuator (12) upon reaching the overpressure threshold ( _ps ) is stored as a limit value, wherein the position of the clutch actuator ( ₁₂ ) based on the overpressure threshold (ps) reached During opening and closing, the limit value remains constant, and the movement of the clutch actuator 12 in the direction of the clutch 4, which opens after reaching the release pressure threshold p _F , is allowed from the limit value or the clutch closed (4) A method for protecting a hydrostatic clutch actuator, characterized in that movement of the clutch actuator (12) in the direction is allowed up to a limit value. 7. Method according to claim 6, characterized in that the limit value of the clutch being opened increases over time, while the limit value of the clutch being closed decreases over time.

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