阅读说明：本技术 用于操作混合动力车辆的混合动力分离离合器的方法 (Method for operating a hybrid disconnect clutch of a hybrid vehicle ) 是由 斯特芬·克莱尔 于 2018-06-06 设计创作，主要内容包括：本发明涉及用于操作混合动力车辆的混合动力分离离合器的方法,在该方法中,通过静液压式离合器致动器(12)使混合动力分离离合器(4)运动,其实现方式是：可轴向运动地支承在静液压式致动器(12)的主动缸(17)中的活塞(16)通过含有液压液体的静液压行程操作操纵混合动力分离离合器(4)的从动缸(21),其中,主动缸(17)的活塞(16)在未被操作的状态下将主动缸(17)相对无压力的补偿容器(24)的连接口(25)打开,以进行液压液体(18)的体积补偿。在即使在混合动力车辆中也可优化通气过程的方法中,在混合动力车辆的纯电动行驶期间,根据混合动力驱动系(1)的系统参数增加液压液体(18)的冷却时间,以推迟体积补偿。(The invention relates to a method for operating a hybrid disconnect clutch of a hybrid vehicle, in which method the hybrid disconnect clutch (4) is moved by a hydrostatic clutch actuator (12), which is implemented in that: a piston (16) mounted axially movably in a master cylinder (17) of a hydrostatic actuator (12) actuates a slave cylinder (21) of the hybrid separating clutch (4) by means of a hydrostatic stroke operation which contains hydraulic fluid, wherein the piston (16) of the master cylinder (17) in the non-actuated state opens a connection opening (25) of the master cylinder (17) to a pressure-free compensating reservoir (24) for volume compensation of the hydraulic fluid (18). In a method for optimizing the ventilation process even in a hybrid vehicle, the cooling time of the hydraulic fluid (18) is increased during electric-only driving of the hybrid vehicle as a function of system parameters of the hybrid drive train (1) in order to delay the volume compensation.)

1. Method for operating a hybrid disconnect clutch of a hybrid vehicle, in which method the hybrid disconnect clutch (4) is moved by a hydrostatic clutch actuator (12), by: a piston (16) mounted axially movably in a master cylinder (17) of the hydrostatic actuator (12) actuates a slave cylinder (21) of the hybrid disconnect clutch (4) by means of a hydrostatic stroke operation which contains hydraulic fluid (18), wherein the piston (16) of the master cylinder (17) in the inoperative state opens a connection opening (25) of the master cylinder (17) to a pressure-free compensating reservoir (24) for volume compensation of the hydraulic fluid (18), characterized in that, during purely electric driving of the hybrid vehicle, the cooling time of the hydraulic fluid (18) is increased as a function of system parameters of the hybrid drive train (1) in order to delay the volume compensation.

2. Method according to claim 1, characterized in that component tolerances and/or temperature dependencies and/or internal combustion engine parameters and/or centrifugal force influences are taken into account as system parameters.

3. Method according to claim 1 or 2, characterized in that the system parameters are evaluated separately from one another and the influence of each system parameter on the characteristic curve shift of the hybrid disconnect clutch (4) is evaluated, and then a measure for delaying the occurrence of the drag torque of the internal combustion engine (2) is selected from the overall result of the respective considerations, whereby the temperature difference of the hydraulic fluid (18) is increased.

4. A method according to claim 1, 2 or 3, characterized by using the rotational speed of the combustion engine (2) during the final volume compensation as a system parameter.

5. Method according to at least one of the preceding claims, characterized in that the current rotational speed of the combustion engine (2) is used as a system parameter.

6. Method according to at least one of the preceding claims, characterized in that fluid temperature variations are used as system parameters.

7. Method according to at least one of the preceding claims, characterized in that the position which the clutch actuator (12) occupies when driving past the connecting opening relative to the compensating reservoir (24) when the pressure rises in the hydrostatic stroke of the clutch actuator (12) is used as a system parameter.

8. Method according to at least one of the preceding claims, characterized in that the priority requirement for volume compensation of the hydraulic liquid (18) is derived from an overall evaluation of system parameters of the hybrid drive train (1).

9. Method according to claim 8, characterized in that the overall assessment and the priority requirement for volume compensation of the hydraulic liquid (18) are output to a superior vehicle strategy unit.

10. Method according to claim 8 or 9, characterized in that said priority requirements are divided into different levels of urgency.

Technical Field

The invention relates to a method for operating a hybrid clutch of a hybrid vehicle, in which method the hybrid clutch is moved by means of a hydrostatic clutch actuator, which is implemented in that: the piston, which is mounted axially movably in the master cylinder of the hydrostatic clutch actuator, actuates the slave cylinder of the hybrid separating clutch by means of a hydrostatic stroke operation that contains hydraulic fluid, wherein the piston of the master cylinder, in the inoperative state, opens a connection opening of the master cylinder to a relatively pressure-free compensating reservoir for volume compensation of the hydraulic fluid.

Background

Automatic clutches, which use hydrostatic clutch actuators, are increasingly used in modern motor vehicles, in particular passenger cars. The hydrostatic clutch actuator has a master cylinder in which a master piston is mounted so as to be axially movable. The drive piston of the master cylinder, which is driven by the electric motor, puts the hydraulic fluid, which is arranged in the hydrostatic stroke, under pressure, whereby the slave piston of the slave cylinder moves, the movement of the slave piston being transmitted to the clutch, whereby the clutch is disengaged. The hydraulic liquid undergoes a volume change due to external influences. The change in volume caused by a change in the temperature of the hydraulic fluid is mainly observed here. In the same master cylinder position, volume changes caused by temperature changes result in slave cylinder movement. In order to transmit the required clutch torque to the slave cylinder and thus to the clutch, the position of the slave cylinder must be known with sufficient accuracy. In order to compensate for the volume change in the hydrostatic stroke, the master cylinder is moved in such a way that the hydrostatic stroke is connected to a pressure-free supplementary tank via an opening present in the master cylinder. In this way, a volume compensation can be achieved between the replenishment reservoir and the hydrostatic stroke. The known relationship between the positions of the master and slave cylinders is then recreated.

The connection between the refill container and the hydrostatic stroke is opened and waits in this position until the volume compensation is called venting. Each ventilation process has a non-negligible effect on the driving performance of the vehicle. On the one hand, frequent ventilation processes significantly reduce the driving comfort, and on the other hand, the required shifting process is delayed by the ventilation process. In order to at least reduce the influence of the temperature of the hydraulic fluid on the clutch actuated by the hydrostatic actuator in the drive train of the motor vehicle, a temperature-dependent change in the pressure medium volume is determined according to DE 102011103750 a1, and the differential displacement of the slave cylinder piston caused by this change is compensated by the loading of the drive device on the master cylinder piston. This allows a longer ventilation cycle to be carried out without impairing driving comfort.

DE 102015210175 a1 discloses a method for controlling an automatically actuated friction clutch, in which the contact points of a clutch characteristic curve, which change as a function of the ventilation process and as a function of the rotational speed of the friction clutch about the axis of rotation, are continuously corrected by means of a compensation value, wherein the compensation value is determined as a function of the direction of the change in rotational speed of the friction clutch.

In a hybrid vehicle having two drive units in the form of an internal combustion engine and an electric motor, which are separated by a hybrid disconnect clutch, the vehicle availability is determined as a function of the driving mode. In this case, the vehicle can be driven by the internal combustion engine and the electric motor individually or simultaneously by two drive units.

Disclosure of Invention

The object of the present invention is therefore to provide a method for operating a hybrid disconnect clutch of a hybrid vehicle, in which the ventilation process can be optimally adjusted.

According to the invention, this technical problem is solved by: during electric-only driving of the hybrid vehicle, the cooling time of the hydraulic fluid is increased in accordance with the system parameters of the hybrid drive train in order to delay the volume compensation. Since the internal combustion engine is switched off during purely electric driving, and the temperature output by the internal combustion engine is not transmitted to the hydraulic fluid of the hydraulic clutch actuator in this case, the time during which cooling can take place is utilized. Therefore, increasing the cooling time improves the availability of the vehicle in electric driving.

Advantageously, component tolerances and/or temperature dependencies and/or internal combustion engine parameters and/or centrifugal force influences are taken into account as system parameters. This takes into account not only the characteristics of the hydrostatic clutch actuator itself, but also the characteristics of the entire hybrid drive train, in order to improve the driving performance of the vehicle by extending the cooling time.

In one embodiment, the system parameters are evaluated separately from one another and the influence of each system parameter on the characteristic curve shift of the hybrid separating clutch is evaluated, and then a measure for delaying the occurrence of the drag torque of the internal combustion engine is selected from the overall result of the individual considerations, as a result of which the temperature difference of the hydraulic fluid is increased. The temperature difference corresponds to the cooling time, provided that the hydraulic liquid temperature gradient remains constant. Considering the combination of the individual considerations and the fact that the hybrid clutch used is a normally closed clutch (in the case of a normally closed clutch, driving between the internal combustion engine and the electric motor is possible when the hybrid clutch is engaged), it is possible to detect how much actuator displacement remains until the hybrid clutch is fully engaged and thus the drag torque occurs by evaluating the deviation of the individual characteristic curves. If the hybrid disconnect clutch is engaged during purely electric driving, a drag torque occurs, in which case the internal combustion engine of the hybrid drive train is started. The occurrence of the drag torque should be delayed as far as possible by means of established measures.

In one variant, the rotational speed of the internal combustion engine during the final volume compensation is used as a system parameter. In this case, the respective rotational speed has a particularly great influence on the centrifugal force acting on the hybrid clutch via the internal combustion engine. The large centrifugal force has disadvantages in that: the slave piston changes its position in such a way that the volume of hydraulic fluid contained in the hydrostatic stroke is smaller after the venting than before the venting.

In one embodiment, the current rotational speed of the internal combustion engine is used as a system parameter. At this rotational speed, the centrifugal force influences also have a large influence on the offset of the clutch characteristic curve.

In another embodiment, the temperature change of the hydraulic liquid is used as a system parameter. Since the change in volume of the hydraulic fluid occurs as a result of a change in temperature, the characteristic curve of the clutch is also shifted in this case.

In one embodiment, the position which the actuator occupies during the pressure increase during the hydraulic stroke of the clutch actuator when driving through the connecting opening of the opposite compensating reservoir is used as a system parameter. This pressure rise shifts the start of the slave piston movement. The starting point of the slave piston movement determines the allowable cooling of the hydrostatic stroke.

Advantageously, the priority requirement for volume compensation of the hydraulic fluid is derived from an overall evaluation of the system parameters of the hybrid drive train. The priority requirement may be that the volume compensation is required immediately, or that the volume compensation is delayed and other measures are first implemented in the hybrid drive train.

In one refinement, the overall evaluation and the priority requirement for volume compensation of the hydraulic fluid are output to a higher-level vehicle strategy unit. Because the availability of the vehicle in pure electric running is improved, the upper vehicle strategy unit does not need to replace the strategy.

In one embodiment, the priority requirements are divided into different levels of urgency. Thus not only are there two levels, but the priority requirement forms a scale. Depending on the determined level, the ventilation process is executed immediately if all other processes, for example a gear shift process, are postponed at a higher priority or after other processes at a lower priority.

Drawings

The invention has a variety of embodiments. Two of which are explained in detail on the basis of the illustrations shown in the figures.

Wherein:

figure 1 shows a schematic diagram of a drive train of a hybrid vehicle,

fig. 2 shows a schematic structure of the hydrostatic clutch operating system.

Detailed Description

Fig. 1 shows a schematic diagram of a drive train 1 of a hybrid vehicle. The drive train 1 comprises an internal combustion engine 2 and an electric motor 3. A hybrid disconnect clutch 4 is arranged between the internal combustion engine 2 and the electric motor 3, immediately after the internal combustion engine 2. The internal combustion engine 2 and the hybrid clutch 4 are connected to each other via a crankshaft 5. The electric motor 3 has a rotatable rotor 6 and a stationary stator 7. The output shaft 8 of the hybrid disconnect clutch 4 is connected to a transmission 9, which contains a coupling element, not shown in detail, such as a second clutch or a torque converter, which is arranged between the electric motor 3 and the transmission 9. The transmission 9 transmits torque generated by the internal combustion engine 2 and/or the electric motor 3 to drive wheels 10 of the hybrid vehicle. The hybrid separating clutch 4 and the transmission 9 thus form a transmission system 11, which is actuated by a hydrostatic clutch actuator 12. A hybrid disconnect clutch 4 disposed between the internal combustion engine 2 and the electric motor 3 is engaged to start the internal combustion engine 2 with torque generated by the electric motor 3 during hybrid vehicle travel or to travel with the internal combustion engine 2 and the electric motor 3 driven during power-assisted propulsion travel.

The structure of an automatic clutch operating system is schematically shown in fig. 2, in an example in which a hydrostatic clutch actuator 12 is schematically shown, applied in a vehicle. The hydraulic clutch actuation system comprises on the drive side a controller 13 which actuates an electric motor 14 which in turn drives a transmission 15 in order to convert a rotary motion of the electric motor 14 into a translatory motion of a drive piston 16 which is mounted in an axially movable manner in a drive cylinder 17. If the rotational movement of the electric motor 14 causes a change in the position of the master piston 16 in the master cylinder 17 to the right along the actuator displacement, the volume of the master cylinder 17 changes, as a result of which a pressure p builds up in the master cylinder 17, which is transmitted via the hydraulic fluid 18 via the hydraulic line 19 to the output side 20 of the hydraulic clutch actuation system. On the output side 20, the pressure p of the hydraulic fluid 18 in the slave cylinder 21 causes a change in the displacement of the slave piston of the slave cylinder 21, which is transmitted to the hybrid disconnect clutch 4 in order to operate it. The pressure p in the master cylinder 17 on the master side of the hydraulic clutch actuation system can be determined by means of a sensor 22. The sensor 22 is a pressure sensor. The distance covered by the clutch actuator 12 is determined by means of a second sensor 23, which is embodied as a displacement sensor. In this case, the two sensors 22 and 23 are connected to the controller 13. The actuator cylinder 17 is connected to a compensation reservoir 24 via an opening 25. The opening 25 is opened by the active piston 16 for volume compensation of the hydraulic liquid 18.

In order to delay the volume compensation between the compensation reservoir 24 and the hydrostatic stroke as long as possible, the electric drive of the hybrid vehicle is set as long as possible. In this case, electric driving is set for as long as possible by taking into account the change in the clutch characteristic curve (which changes when the variable clutch torque changes between the initial position and the final position of the clutch actuator 12) without the occurrence of a drag torque at the hybrid disconnect clutch 4 that starts the internal combustion engine 2 that is not operated. For this purpose, system parameters of drive train 1 are evaluated in the software of controller 13 and thus allow a stronger cooling as a function of the tolerance combination, which cooling is achieved when internal combustion engine 2 is switched off. The parameters to be taken into account in the setting of the cooling time include the rotational speed of the internal combustion engine 2 during the final volume compensation, the current engine rotational speed, the temperature change of the hydraulic fluid 18 and the pressure rise position during the volume compensation during the passage through the opening. In this case, in particular, the closing point is considered, from which the hydraulic separating clutch 4 is actuated.

Since the conventional hybrid disconnect clutch 4 is a normally closed clutch, the hybrid disconnect clutch 4 must be opened to enable electric driving of the vehicle. The cooling of the hydraulic fluid 18 is achieved by the electric-only drive, which is caused on the one hand by the driving wind and on the other hand also by the switched-off internal combustion engine 2. In order to vent in this state, the actuator must operate pressureless. The engagement of the hybrid disconnect clutch 4 is delayed on the basis of a characteristic curve deviation due to the cooling of the hydraulic fluid 8, since the clutch actuator has not yet reached the final position.

In a further exemplary embodiment, the rotational speed of the internal combustion engine 2 is used for the final volume compensation. If the rotational speed is found to be very low, for example below 2000U/s, it is assumed that no characteristic curve shift has taken place and therefore no ventilation process is required. At a rotational speed of 4000U/s, the actuator displacement and thus the clutch characteristic curve achieve a shift of, for example, 0.6 mm. On the basis of this, the characteristic curve shifts and the actuator displacement increases as the rotational speed increases and is therefore always closer to the final position. But since the actuator displacement is limited to 13mm, for example, it can be determined by observing the respective characteristic curve shifts: how many millimeters the clutch actuator 12 is from the final position. In this way, provision is made at the hybrid drive train 1 for the distance of the actuator position up to its final position to be sufficiently large to enable further cooling of the hydraulic fluid 8. That is, the current actuator position, which is adjusted by the characteristic curve offset, is also sufficiently spaced from the final position of the clutch actuator 12. Thereby avoiding adjustment of the drag torque. Meanwhile, the pure electric running time of the vehicle is prolonged.

The determination of the influence of the system parameters on the cooling performance of the hydraulic liquid can be combined with the ventilation requirement, which is implemented with different priorities. The priority forms a scale that divides "immediate ventilation" or "postpones the ventilation process". There are further levels between them, which further levels comprise corresponding provisions for the ventilation process. In this implementation, the ventilation priority requirement is determined based on the effect of the entire hybrid drive train.

List of reference numerals

1 drive train

2 internal combustion engine

3 electric motor

4 hybrid disconnect clutch

5 crankshaft

6 rotor

7 stator

8 driven shaft

9 speed variator

10 driving wheel

11 transmission system

12 Clutch actuator

13 controller

14 motor

15 driving device

16 active piston

17 master cylinder

18 hydraulic fluid

19 hydraulic line

20 driven side

21 slave cylinder

22 pressure sensor

23 displacement sensor

24 compensating container

25 opening