CN110226052B

CN110226052B - Method for determining the temperature of a hydraulic fluid in a hydraulic clutch actuation system

Info

Publication number: CN110226052B
Application number: CN201880008247.4A
Authority: CN
Inventors: 克里斯蒂安·弗尔布雷希特
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2017-02-24
Filing date: 2018-01-18
Publication date: 2021-07-02
Anticipated expiration: 2038-01-18
Also published as: DE102017103815A1; DE112018001003B4; DE112018001003A5; WO2018153397A1; CN110226052A

Abstract

The invention relates to a method for determining the temperature of hydraulic fluid in a hydraulic clutch actuation system, wherein a compensation value for an actuator path of a clutch actuator (4) in the clutch actuation system (1) is determined by means of the temperature (T _ C) of the hydraulic fluid, wherein the temperature (T _ C) of the hydraulic fluid (8) is calculated by means of a fluid temperature model (16), and two different temperatures (T _ A, T _ B) are supplied as input signals to the fluid temperature model. In the method, in which the correct temperature of the hydraulic fluid is determined even in the case of an insufficient quality of the temperature signal, a validity information is assigned to each temperature (T _ A, T _ B), wherein, in the presence of at least one invalid delivered temperature (T _ A, T _ B), the fluid temperature model (16) calculates the temperature (T _ C) of the hydraulic fluid (8) from the previous valid delivered temperature (T _ A, T _ B).

Description

Method for determining the temperature of a hydraulic fluid in a hydraulic clutch actuation system

Technical Field

The invention relates to a method for determining the temperature of a hydraulic fluid in a hydraulic clutch actuation system, wherein a compensation value for an actuator stroke of a clutch actuator in the clutch actuation system is determined using the temperature of the hydraulic fluid, wherein the temperature of the hydraulic fluid is calculated by means of a fluid temperature model, and two different temperatures are supplied as input signals to the fluid temperature model.

Background

The hydraulic fluid in a hydraulic clutch actuation system used in vehicles is subject to volume changes due to external influences, in particular mainly due to changes in the temperature of the fluid. This volume change results in a different displacement of the slave cylinder in the same master cylinder position. In order to transmit the required clutch torque, the position of the slave cylinder must be determined with sufficient accuracy. In order to compensate for the volume changes occurring in the hydrostatic connecting line, the master cylinder is moved in such a way that the connecting line is connected to the unpressurized compensating tank via an opening present in the master cylinder. Thereby a volume compensation is performed between the compensation vessel and the connecting line. A known relationship is then established between the position of the master cylinder and the position of the slave cylinder. The opening of the connection between the compensation vessel and the connecting line and the maintenance in this position up to the volume compensation is referred to as suction (Schn ü ffeln). However, such an air induction process has a non-negligible effect on the driving behavior of the vehicle. On the other hand, the frequent air suction process greatly reduces the driving comfort. The required switching process may be delayed due to the inspiration process.

DE 102014219029 a1 discloses a method and a device for controlling a clutch actuator for actuating a clutch, preferably a clutch which is closed when not actuated, of a vehicle. The clutch actuator is operable through a maximum stroke for operating the master cylinder to move the slave cylinder through a hydrostatic transmission path including hydraulic fluid and to fully open the clutch. The separation stroke of the slave piston on the slave cylinder is limited. It is known to reduce the maximum travel of the clutch actuator to disable the slave cylinder from continuing to move as the temperature increases. Thereby protecting the slave cylinder from damage. As the temperature of the hydraulic fluid in the transmission path of the hydrostatic system increases (at which temperature the hydraulic fluid expands), the actuator stroke is displaced by compensation in such a way that this expansion is counteracted. The same is true when the liquid contracts during cooling.

In the past, unpublished german patent application No. DE 102017102583.9, a fluid temperature model is proposed, by means of which the temperature of the hydraulic fluid is calculated in order to determine a compensation value for the actuator travel of the clutch actuator. This liquid temperature model has two different temperature input signals. It may happen that the quality of the temperature input signal of the liquid temperature model is insufficient for calculating the temperature of the hydraulic liquid, which results in erroneous actuator stroke compensation values.

Disclosure of Invention

The object of the present invention is to provide a method for determining the temperature of a hydraulic fluid in a hydraulic clutch actuation system, which method functions even if the temperature input signal of the fluid temperature model is not of sufficient quality.

According to the invention, this object is achieved in that validity information is associated with each delivered temperature, wherein the fluid temperature model calculates the temperature of the hydraulic fluid from the previous valid delivered temperature in the presence of at least one invalid delivered temperature. This has the advantage that the temperature of the hydraulic fluid can also be calculated with the aid of the temperatures which were once supplied to the fluid temperature model and which are regarded as of sufficient quality. Thus, an erroneous determination of the compensation value for the actuator stroke on the basis of an erroneously determined hydraulic fluid temperature is prohibited.

Advantageously, the respective last active delivery temperature of the respective two delivery temperatures is used as the previous active delivery temperature. By using the respective last effective delivered temperature, the hydraulic fluid temperature is calculated such that in the steady state of the fluid temperature model the temperature of the hydraulic fluid and the actuator position compensation value associated therewith can be kept in the previously calculated range.

In one embodiment, in the case of the unsteady state of the fluid temperature model, the temperature oscillations of the hydraulic fluid are set into a state which is correlated with the two last effective delivery temperatures. This also makes it possible to reliably determine the temperature of the hydraulic fluid and thus the compensation value for the actuator stroke.

The invention relates to a method for determining the temperature of a hydraulic fluid in a hydraulic clutch actuation system, wherein a compensation value for an actuator travel of a clutch actuator in the clutch actuation system is determined using the temperature of the hydraulic fluid, wherein the temperature of the hydraulic fluid is calculated by means of a fluid temperature model, and two different temperatures are supplied as input signals to the fluid temperature model. In order to be able to determine a reliable temperature of the hydraulic fluid even if the quality of the delivered temperatures is insufficient, validity information is provided for each delivered temperature, and in the absence of a valid delivered temperature, the calculation of the temperature of the hydraulic fluid by means of the fluid temperature model is interrupted until a first valid temperature of one of the two delivered temperatures occurs, which is used instead of the calculated temperature of the hydraulic fluid. This has the advantage that, when a first effective temperature of one of the two delivered temperatures occurs, this temperature is used as the temperature of the hydraulic fluid in order to determine the compensation value for the actuator travel accordingly.

In one variant, after the first effective delivery temperature of the other of the two delivery temperatures has occurred, the fluid temperature model calculates the temperature of the hydraulic fluid from the two first effective delivery temperatures of the two delivery temperatures. The temperature of the hydraulic fluid can thus be determined again using normal calculations by means of a fluid temperature model after a transition period in which the temperature of the hydraulic fluid is replaced by the first effective temperature of one of the two delivered temperatures.

In one embodiment, the fluid temperature model is initialized before the temperature of the hydraulic fluid is calculated. By initialization it is ensured that the starting point for all subsequent calculations of the temperature of the hydraulic liquid in the liquid temperature model is fixed.

Advantageously, a temperature jump, which occurs when the first effective temperature of the two delivered temperatures is used initially, is concealed when calculating the temperature of the hydraulic fluid. This ensures that no discontinuities occur in the calculation of the hydraulic fluid temperature as a result of the switching, and therefore the compensation value for the actuator travel is determined directly as a function of the temperature change of the hydraulic fluid.

In one embodiment, the temperature of the hydraulic fluid is calculated between two successive intake processes of the clutch actuator by means of a fluid temperature model. This is particularly always advantageous if there is a relatively long time period between successive suction processes. The described method can reliably react to changes in the temperature of the hydraulic fluid and to changes in the volume of the hydraulic fluid.

In one embodiment, the time period between two successive inspiration processes is a maximum of several hours. By interrupting the air suction process for such a long time, the driving comfort is improved due to the stop of the air suction process and the influence of the air suction process on the driving performance is prevented.

In one variant, in the case of a clutch which is closed when not operated, the method is carried out with the aid of a hydrostatically operated clutch actuator having a hydraulic stroke when compensating the actuator stroke.

Drawings

There are various embodiments of the present invention. Two of which are illustrated in detail in the drawings attached hereto.

In which is shown:

figure 1 shows a schematic diagram of a clutch operating system in a vehicle,

figure 2 illustrates one embodiment of a fluid temperature model,

figure 3 shows a first embodiment of the method according to the invention,

fig. 4 shows a second embodiment of the method according to the invention.

Detailed Description

Fig. 1 shows a configuration of a hydrostatic clutch actuation system 1 for use in a vehicle. The hydrostatic clutch actuation system 1 comprises an actuator control 3 on the drive side 2, which actuates a hydrostatic clutch actuator 4. The clutch actuator 4 is connected kinematically via a gear 5 to a piston 6 of a master cylinder 7. When the clutch actuator 4 and in this case the piston 6 in the master cylinder 7 change position to the right along the actuator stroke, the volume of the master cylinder 7 changes, as a result of which a pressure p builds up in the master cylinder 7, which is transmitted via the hydraulic fluid 8 via the hydraulic line 9 to the output side of the hydrostatic clutch actuation system 1. On the output side 10, the pressure p of the hydraulic fluid 8 causes a stroke change in the slave cylinder 11, which is transmitted to the clutch 12 for actuating the clutch. The clutch 12 is a clutch that is closed in an unoperated state, as is used, for example, as a hybrid disconnect clutch in a hybrid vehicle.

The stroke of the piston 6 of the master cylinder 7, which has to be covered along the actuator stroke, is determined by means of the displacement sensor 13. The master cylinder 7 is connected to a compensating reservoir 14, wherein, when the piston 6 is in a predetermined position, a connecting opening 15 of the master cylinder 7 is released by the piston 6 of the master cylinder 7, thereby enabling a volume compensation of the hydraulic fluid and a cooling of the hydraulic fluid during the hydrostatic stroke. This volume compensation is called the inspiration process.

In order to prevent interference with the clutch actuation system 1 between two suction processes, the temperature of the hydraulic fluid 8 is determined, which is carried out by means of the fluid temperature model 16. The compensation value for the disengagement path of the clutch actuator 4 is determined by means of the temperature of the hydraulic liquid 8.

Fig. 2 shows a schematic illustration of the liquid temperature model 16, to which the first temperature T _ a and the second temperature T _ B are supplied. The temperatures T _ a and T _ B are two temperatures measured in the vicinity of the clutch operating system 1 or in the clutch operating system 1, for example a measured ambient temperature and a measured actuator temperature. In the fluid temperature model 16, the temperature T _ C of the hydraulic fluid 8 is determined from the two delivered measured temperatures T _ a and T _ B according to a predefined algorithm.

In case one or both of the temperatures T _ a and T _ B delivered to the liquid temperature model are not of sufficiently high quality, the temperature T _ C of the hydraulic liquid 8 has to be determined via an alternative strategy. For this purpose, each of the delivered temperatures T _ a and T _ B is provided with status information which transmits the validity of the respective temperature T _ a and T _ B to the fluid temperature model 16.

Further distinguishing between cases, i.e. cases: before the ineffective delivery temperatures T _ a and T _ B are applied, the effective temperatures T _ a and T _ B are already present at the fluid temperature model 16, from which the temperature T _ C of the hydraulic fluid 8 can already be calculated, and the situation: the effective temperatures T _ a and T _ B that have not yet been delivered at the fluid temperature model 16.

In the case that the temperature T _ C of the hydraulic fluid 8 can be calculated on the basis of the already existing effective temperatures T _ a and T _ B, the temperature T _ C of the hydraulic fluid 8 is determined in accordance with the exemplary embodiment of the method according to the invention shown in fig. 3 when temperatures T _ a and T _ B of insufficient quality occur. The temperature T at the time T is shown in fig. 3, wherein the temperatures T _ a and T _ B supplied to the liquid temperature model 16 and the temperature T _ C of the hydraulic liquid 16 calculated from the temperatures T _ a and T _ B by the liquid temperature model 16 are shown at the same time. In the first time period Δ T1, it is assumed that the delivered temperature T _ a and the delivered temperature T _ B are valid and therefore of sufficient quality. The first temperature T _ a delivered in the time period Δ T2 immediately following the time period Δ T1 provides an invalid signal. This invalid signal is not available for calculating the temperature T _ C of the hydraulic fluid 8. For this purpose, in addition to the effective temperature T _ B additionally supplied, the last or last effective temperature T _ a supplied is used to calculate the temperature T _ C of the hydraulic fluid 8. If after the time period Δ T2 has elapsed and at the beginning of the time period Δ T3 the effective temperature T _ a is again present at the fluid temperature model 16, the temperature T _ C of the hydraulic fluid 8 is calculated with the current delivered temperature T _ a and the current delivered temperature T _ B.

In fig. 4, a situation in which no effective temperatures T _ a and T _ B are supplied to the fluid temperature model 16 at all is discussed, fig. 4 showing a second embodiment of the method according to the invention. In this example, the temperature T is shown over time T. The effective temperatures T _ a and T _ B are shown in the diagram 4 a. It can be seen here that the temperatures T _ a and T _ B delivered first in the time period Δ T4 are not effective. The effective temperature T _ a is initially supplied to the liquid temperature model 16 after a time period Δ T4. The delivered temperature T _ B is also ineffective. In this case, the effective temperature T _ a is used for the first time as the temperature T _ C of the hydraulic fluid 8 in the time period Δ T5 (fig. 4 b). The second temperature T _ B is first effective at the beginning of the time period at 6. As soon as the two delivered temperatures T _ a and T _ B are present at the fluid temperature model 16 with sufficient quality, the fluid temperature model 16 is initialized as a function of these first temperatures T _ a and T _ B and the temperature T _ C of the hydraulic fluid 8 is calculated as a function of the fluid temperature model 16 in a time period Δ T6.

In the diagram of fig. 4b, however, the temperature T _ C of the hydraulic fluid 8 thus determined has temperature jumps Δ T1 and Δ T2, which can lead to errors in the compensation of the maximum actuator position and in the confirmation of the necessity of performing a suction. Thus, when determining the temperature T _ Cdelta of the hydraulic fluid 8, the temperature jumps Δ T1 and Δ T2, i.e. the temperature jumps (Δ T1) that occur when starting to use the effective temperature T _ a as the temperature T _ C of the hydraulic fluid 8 by means of the fluid temperature model 16 according to fig. 4B and the temperature jumps (Δ T2) that occur when starting to calculate the temperature T _ C of the hydraulic fluid 8 from the two effective temperatures T _ a and T _ B, are hidden according to fig. 4C. It is thus ensured that the calculation of the compensation value for the actuator travel and the determination of the necessity of carrying out an intake process are taken into account only by a change in the temperature T _ C of the hydraulic fluid 8 since the last or last intake.

List of reference numerals

1 Clutch actuation System

2 active side

3 actuator control apparatus

4 Clutch actuator

5 Transmission mechanism

6 piston

7 driving cylinder

8 hydraulic fluid

9 Hydraulic line

10 driven side

11 slave cylinder

12 clutch

13 displacement sensor

14 compensating container

15 connecting port

16 liquid temperature model

Temperature of T _ A delivery

Temperature of T _ B delivery

Temperature of hydraulic liquid of T _ C

Claims

1. A method for determining the temperature of hydraulic fluid in a hydraulic clutch actuation system, wherein a compensation value for an actuator stroke of a clutch actuator (4) in the clutch actuation system (1) is determined by means of the temperature (T _ C) of the hydraulic liquid, wherein the temperature (T _ C) of the hydraulic liquid (8) is calculated by means of a liquid temperature model (16), to which two different temperatures (T _ A, T _ B) are supplied as input signals, characterized in that each temperature (T A, T _ B) is provided with validity information, wherein, in the presence of at least one invalid temperature (T A, T _ B) of the transport, the fluid temperature model (16) calculates the temperature (T _ C) of the hydraulic fluid (8) from the previously effective delivered temperature (T _ A, T _ B).

2. Method according to claim 1, characterized in that the respective last effective temperature of the respective two delivered temperatures (T _ A, T _ B) is used as the previously effective delivered temperature (T _ A, T _ B).

3. Method according to claim 2, characterized in that in the case of an unsteady state of the liquid temperature model (16), the temperature (T _ C) of the hydraulic liquid (8) is adjusted in an oscillating manner into a state which is related to the two last effective delivered temperatures (T _ A, T _ B).

4. A method for determining the temperature of hydraulic fluid in a hydraulic clutch actuation system, wherein a compensation value for an actuator travel of a clutch actuator (4) in the clutch actuation system (1) is determined by means of the temperature (T _ C) of the hydraulic fluid (8), wherein the temperature (T _ C) of the hydraulic fluid (8) is calculated by means of a fluid temperature model (16), to which two different temperatures (T _ A, T _ B) are supplied as input signals, characterized in that validity information is provided for each supplied temperature (T _ A, T _ B) and, in the absence of a valid supplied temperature (T _ A, T _ B), the calculation of the temperature (T _ C) of the hydraulic fluid (8) by means of the fluid temperature model (16) is interrupted until the two supplied temperatures (T _ A, B) occur, T _ B), using said first effective delivered temperature instead of the calculated temperature (T _ C) of the hydraulic liquid (8).

5. Method according to claim 4, characterized in that the liquid temperature model (16) calculates the temperature (T _ C) of the hydraulic liquid (8) from the two first effective delivered temperatures (T _ A, T _ B) of the two delivered temperatures (T _ A, T _ B) after the occurrence of the first effective delivered temperature (T _ B) of the other of the two delivered temperatures (T _ A, T _ B).

6. A method according to claim 5, characterized in that the liquid temperature model (16) is initialized before calculating the temperature (T _ C) of the hydraulic liquid (8).

7. Method according to claim 4, characterized in that a temperature jump is concealed when calculating the temperature of the hydraulic liquid, which temperature jump occurs at the beginning of the use of the first effective temperature of the two delivered temperatures.

8. Method according to claim 4, characterized in that the temperature (T _ C) of the hydraulic liquid (8) is calculated between two successive suction processes of the clutch actuator (4) by means of the liquid temperature model (16).

9. Method according to claim 8, characterized in that the time period between the two successive inspiration processes is a maximum of several hours.

10. Method according to one of claims 4 to 9, characterized in that in the clutch (12) which is closed when not operated, the method is carried out with the aid of a hydrostatically operated clutch actuator (4) having a hydraulic stroke when the actuator stroke is compensated.