DE102017102583A1 - Method for determining an actuator travel of a hydraulic clutch actuator - Google Patents

Abstract

The invention relates to a method for determining an actuator travel of a hydraulic clutch actuator, wherein the Aktorweg is changed in response to a temperature of the clutch actuator (4) via a compensation value and a calculation of the compensation value via a determination of a temperature of the actuator actuated hydraulic fluid (8). In a method in which a particularly favorable initialization value of the temperature of the hydraulic fluid is determined, an initial value of the temperature of the hydraulic fluid (8) is calculated as a function of the plausibilized temperature of the clutch actuator (4) and a clutch temperature determined by a clutch temperature model.

Description

The invention relates to a method for determining an actuator travel of a hydraulic clutch actuator, wherein the Aktorweg is changed in response to a temperature of the clutch actuator via a compensation value and a calculation of the compensation value via a determination of a temperature of an actuated by the actuator hydraulic fluid.

In modern motor vehicles, especially passenger cars, increasingly automated clutches are used which use a hydrostatic clutch actuator. Such a hydrostatic clutch actuator has a master cylinder, in which a master piston is mounted axially movable. The master cylinder of the master cylinder, which is driven by an electric motor, pressurizes a hydraulic fluid, which is arranged in a hydrostatic transmission path, whereby a slave piston of the slave cylinder is moved, whose movement is transmitted to the clutch, whereby it is opened.

From the DE 10 2014 219 029 A1 are known a method and a device for controlling a clutch actuator for actuating a clutch, preferably a non-actuated closed clutch, for a motor vehicle. The clutch actuator can travel a maximum distance to actuate the master cylinder to move over the hydrostatic transmission links the slave cylinder and fully open the clutch. The release travel of the slave piston on the slave cylinder is also limited. It is known that the maximum distance of the clutch actuator is reduced in order not to move the slave cylinder at a temperature increase further than allowed. As a result, the slave cylinder is protected from destruction. It is therefore to be assumed that, in the case of a temperature increase at which the hydraulic fluid expands, the actuator travel is compensated so that the expansion is counteracted. It is analogous to a contraction of the liquid during a cooling process.

In the older, not previously published, own German patent application with the official file number DE 10 2015 213 297.8 is shown as the reduction of Aktorweges from the DE 10 2014 219 029 A1 and known compensations can be conveniently combined with each other via linear combinations.

In the older, not previously published own German patent application with the official file number DE 10 2016 215 590.3 It is proposed to send available temperature signals of the hydrostatic actuator in the form of board temperature, pressure sensor temperature and angle sensor temperature to a transmission control unit, there to carry out a plausibility check at the start of the control unit together with the available there engine shutdown time. The temperature of the hydraulic fluid is estimated and calculated on the basis of the compensation value. If the liquid heats up, it expands, which is why compensation reduces the actuator travel.

It is known to initialize the temperature of the hydraulic fluid with the temperature of the actuator. This can cause a significant change in the temperature of the hydraulic fluid, especially at low ambient temperatures and high clutch temperature. However, since this strong change does not exist in reality and is caused only by the initialization, sniffing operations are unnecessarily early and frequently requested. In addition, a compensation value is calculated based on the temperature difference of the hydraulic fluid since the last snooping operation, which does not exist in reality.

The invention has for its object to provide a method for determining a Aktorweges a hydraulic clutch actuator, in which an initialization of the temperature of the hydraulic fluid is made, in which the disadvantages described are suppressed.

According to the invention, the object is achieved by calculating an initial value of the temperature of the hydraulic fluid as a function of the plausibilized temperature of the clutch actuator and a clutch temperature determined by a clutch temperature model. This has the advantage that with a simple calculation waiving a dynamic model, the initialization of the temperature of the hydraulic fluid can be made.

Advantageously, the calculation of the initial value according to $$T_{HydraulikflüssiGkeit}=\frac{C_1*T_{KupplunGstemperatur\text{mod}ell}}{C_1+{\text{<figure-callout id="2" label="C" filenames="DE102017102583A1\_0008.png" state="{{state}}">C</figure-callout>}}_2}+\frac{{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DE102017102583A1\_0008.png"\; state="\{\{state\}\}">C</figure-callout>}}_2*T_{HydrOstatiscHerAktOr}}{C_1+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DE102017102583A1\_0008.png"\; state="\{\{state\}\}">C</figure-callout>}}_2}$$

By means of this equation, the clutch temperature calculated by the clutch temperature model and the actuator temperature selected by the hydrostatic actuator are weighted, resulting in an initial value of the temperature of the hydraulic fluid, which can be used reliably under a variety of external temperature and clutch temperature conditions.

dar, welches der Initialisierung zugrunde gelegt wird. Liegt ein solches dynamisches Modell der Initialisierung zugrunde, werden durch die Verwendung des stationären Endwertes die in der Realität nicht vorhergesehenen Schwankungen herausgenommen, was die Genauigkeit des Rechenergebnisses verbessert.In one embodiment, the calculated initial value of the temperature of the hydraulic fluid according to a stationary end value of a dynamic model $${\dot{T}}_{HydraulikflüssiGkeit}=C_1\left(T_{KupplunGstemperatur\text{mod}ell}-T_{HydraulikflüssiGkeit}\right)+C_2\left(T_{HydrOstatiscHerAktOr}-T_{HydraulikflüssiGkeit}\right)\text{,}$$

which is the basis of the initialization. If such a dynamic model is based on the initialization, the use of the steady-state final value removes the fluctuations that were not foreseen in reality, which improves the accuracy of the calculation result.

In a further development, the dynamic temperature model of the hydraulic fluid depends on the plausibilized temperature of the clutch actuator and a clutch temperature determined by the clutch temperature model. As a result, fluctuations in the determination of the temperature of the hydraulic fluid are further reduced.

In one variant, the plausibilized temperature of the clutch actuator is determined by comparing the temperatures of the clutch actuator measured by different temperature sensors, wherein one of the measured temperatures is selected as a plausibilized temperature of the clutch actuator with a predetermined correlation of the detected temperatures. Since this occurs during a period in which the controller is not active, i. the engine is stationary, the temperature sensors are in a steady state, so that they have a predetermined temperature correlation among themselves due to their positioning in the hydrostatic clutch actuator, which ensures that the temperatures thus determined can also be used.

In one embodiment, the temperature sensors measure a board temperature, an angle sensor temperature, and a pressure sensor temperature in the clutch actuator. These temperature sensors are installed at very different positions in the clutch actuator and only give off comparable signals when the vehicle and thus the clutch actuator have cooled down accordingly.

In one embodiment, the board temperature is used as the temperature of the clutch actuator for determining the compensation value of the Aktorweges after successful plausibility against the angle sensor temperature and the pressure sensor temperature. As a result of the plausibility only a temperature signal is necessary, by means of which a temperature of the hydraulic fluid and depending on the compensation path of the clutch actuator is determined by a temperature model.

In an alternative, the angle sensor temperature is used after successful plausibility against the pressure sensor temperature as the temperature of the clutch actuator for determining the compensation value of Aktorweges in the absence of plausibility of the board temperature. Thus, sufficient redundant signals are present, by means of which, in case of failure of a temperature signal, the temperature of the clutch actuator can still be reliably determined.

Advantageously, the calculation of the dynamic temperature model of the hydraulic fluid takes place in an actuator control device. Since the board temperature, angle sensor temperature and pressure sensor temperature are measured in the actuator itself, the further processing of the signals for the determination of the temperature of the hydraulic fluid can be performed reliably in the actuator control unit.

In one embodiment, the method of temperature compensation is performed on a non-actuated closed clutch with a hydrostatically actuated clutch actuator and a hydraulic path when the clutch is in an open position.

The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures shown in the drawing.

• 1 eine Prinzipdarstellung eines Kupplungsbetätigungssystems in einem Fahrzeug,
• 2 eine Prinzipdarstellung des erfindungsgemäßen Verfahrens.

Show it:

• 1 a schematic diagram of a clutch actuation system in a vehicle,
• 2 a schematic diagram of the method according to the invention.

1 shows a structure of a hydrostatic clutch actuation system 1 for use in a vehicle. The hydrostatic clutch actuation system 1 includes on the donor side 2 an actuator control unit 3 , which is a hydrostatic clutch actuator 4 controls. The clutch actuator 4 is about a gearbox 5 with a piston 6 of a master cylinder 7 kinematically connected. When the position of the clutch actuator changes 4 and at the same time the piston 6 in the master cylinder 7 along the Aktorweges to the right is a volume of the master cylinder 7 changed, creating a pressure p in the master cylinder 7 is built, which has a hydraulic fluid 8th via a hydraulic line 9 to the slave side of the hydrostatic clutch actuation system 1 is transmitted. On the taker side 10 causes the pressure p of the hydraulic fluid 8th in a slave cylinder 11 a path change that is transmitted to a clutch 12 to actuate it. At the clutch 12 it is a clutch that is open in the unactuated state, as used, for example, as a hybrid disconnect clutch in hybrid vehicles.

The of the piston 6 of the master cylinder 7 traveled distance along the Aktorweges is by means of a displacement sensor 13 determined. The master cylinder 7 is with a surge tank 14 connected, wherein a connection opening 15 of the master cylinder 7 through the piston 6 of the master cylinder 7 is released when the piston 6 is in a predetermined position, whereby a volume compensation and thus a cooling of the hydraulic fluid in the hydrostatic route is made possible.

To a destruction of the clutch actuation system 1 To prevent, depending on an actuator temperature, the temperature of the hydraulic fluid 8th determines what happens with the aid of a temperature model. Using the temperature of the hydraulic fluid 8th becomes a compensation value of the disengagement travel of the clutch actuator 4 certainly.

2 shows a schematic diagram of the method according to the invention. Input signals of the temperature model of the hydraulic fluid 8th _Form once a first temperature T _coupling temperature model and a second temperature T _{hyrostaticAktor} . The temperature model supplies as output a temperature T _{hydraulic fluid} . However, this temperature T _{hydraulic fluid} must be initialized at the beginning of the calculation. The temperature model for the hydraulic fluid 8th is a dynamic model that represents a differential equation in the form: $${\dot{T}}_{HydraulikflüssiGkeit}=C_1\left(T_{KupplunGstemperatur\text{mod}ell}-T_{HydraulikflüssiGkeit}\right)+C_2\left(T_{HydrOstatiscHerAktOr}-T_{HydraulikflüssiGkeit}\right)\text{,}$$

A favorable initial value for the temperature of the hydraulic fluid 8th can be specified with a steady-state final value of the dynamic equation (1). To do this, the differential system is set to zero and the time to infinity is considered. This results in the final value $$T_{HydraulikflüssiGkeit}=\frac{C_1*T_{KupplunGstemperatur\text{mod}ell}}{C_1+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DE102017102583A1\_0008.png"\; state="\{\{state\}\}">C</figure-callout>}}_2}+\frac{{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DE102017102583A1\_0008.png"\; state="\{\{state\}\}">C</figure-callout>}}_2*T_{HydrOstatiscHerAktOr}}{C_1+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DE102017102583A1\_0008.png"\; state="\{\{state\}\}">C</figure-callout>}}_2}$$

Alternatively, it is also possible, instead of using the dynamic temperature model, the temperature T _{hydraulic fluid of} the hydraulic fluid 8th to initialize only with the steady state value. A general calculation of the temperature of the hydraulic fluid takes place with the expression $$T_{HydraulikflüssiGkeit}=\frac{C_1*T_{KupplunGstemperatur\text{mod}ell}}{C_1+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DE102017102583A1\_0008.png"\; state="\{\{state\}\}">C</figure-callout>}}_2}+\frac{{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DE102017102583A1\_0008.png"\; state="\{\{state\}\}">C</figure-callout>}}_2*T_{HydrOstatiscHerAktOr}}{C_1+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DE102017102583A1\_0008.png"\; state="\{\{state\}\}">C</figure-callout>}}_2}$$

As a result, it is possible to completely dispense with dynamic models in that only one stationary value is used as the initial value for the hydraulic fluid temperature model 8th is used.

Instead of the temperature T _{hydraulic fluid of} the hydraulic fluid 8th As described, it is also conceivable to intentionally lower the status of the hydraulic fluid temperature signal with rapid changes in the temperature signal in order to reduce confidence in the temperature signal of subsequent strategies. Such subsequent strategies are, for example, the snoop request or the compensation of the actuator path. If the status signal is lowered, it will not be taken into account in further calculations, but only when the status signal has been raised again. It is assumed that when the status is raised, the temperature signal has settled and can therefore be used.

To determine the temperature T _{hydrostatic clutch actuator of} the hydrostatic clutch actuator, a board temperature is used as the temperature of the clutch actuator, which is plausibilized using an angular sensor temperature and pressure sensor temperature, all three of which are measured in the hydrostatic clutch actuator. The plausibility check is carried out after a predetermined service life, which is specified by a timer, it being assumed after expiry of this service life that the temperatures measured by the three temperature sensors are approximately equal. First, the board temperature is plausibilized against the pressure sensor temperature and the angle sensor temperature. If all three temperature sensors indicate the same temperature, it is assumed that the status of the board temperature is in order, which is why the board temperature is the temperature of the clutch actuator 4 the calculation of the temperature T _{hydraulic fluid of} the hydraulic fluid 8th is taken as a basis. If the board temperature deviates too far from the pressure sensor temperature and the angle sensor temperature, their status is reduced so that the board temperature can no longer be used. In this case, the angle sensor temperature is used as the temperature of the clutch actuator 4 after having been made plausible against the pressure sensor temperature.

LIST OF REFERENCE NUMBERS

1

Hydrostatic clutch actuation system

2

donor side

3

actuator control

4

clutch actuator

5

transmission

6

piston

7

Master cylinder

8th

hydraulic fluid

9

hydraulic line

10

recipient side

11

slave cylinder

12

clutch

13

displacement sensor

14

surge tank

15

connecting opening

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014219029 A1 [0003, 0004]
• DE 102015213297 [0004]
• DE 102016215590 [0005]

Claims (10)

Method for determining an actuator travel of a hydraulic clutch actuator, wherein the actuator travel is varied as a function of a temperature of the clutch actuator (4) via a compensation value and a calculation of the compensation value via a determination of a temperature of a hydraulic fluid actuated by the actuator (8), characterized in that an initial value of the temperature of the hydraulic fluid (8) is calculated as a function of the plausibilized temperature of the clutch actuator (4) and a clutch temperature determined by a clutch temperature model. Method according to Claim 1 , characterized in that the calculation of the initial value according to $$T_{HydraulikflüssiGkeit}=\frac{C_1*T_{KupplunGstemperatur\text{mod}ell}}{C_1+C_2}+\frac{C_2*T_{HydrOstatiscHerAktOr}}{C_1+C_2}$$

he follows. Method according to Claim 1 or 2 , characterized in that the calculated initial value of the temperature of the hydraulic fluid according to a stationary end value of a dynamic model $${\dot{T}}_{HydraulikflüssiGkeit}=C_1\left(T_{KupplunGstemperatur\text{mod}ell}-T_{HydraulikflüssiGkeit}\right)+C_2\left(T_{HydrOstatiscHerAktOr}-T_{HydraulikflüssiGkeit}\right)\text{,}$$

represents which of the initialization is based. Method according to Claim 3 , characterized in that the dynamic temperature model of the hydraulic fluid (8) depends on the plausibilized temperature of the clutch actuator (4) and a clutch temperature determined by a clutch temperature model. Method according to at least one of the preceding claims, characterized in that the plausibilized temperature of the clutch actuator (4) is determined by comparing the temperatures measured by different temperature sensors of the clutch actuator, wherein at a predetermined correlation of the detected temperatures to each other one of the measured temperatures as plausibilized temperature of the clutch actuator (4) is selected. Method according to Claim 5 , characterized in that the temperature sensors measure a board temperature, an angle sensor temperature and a pressure sensor temperature in the clutch actuator (4). Method according to Claim 5 or 6 , characterized in that the board temperature is used as the temperature of the clutch actuator (4) for determining the compensation value of Aktorweges after successful plausibility against the angle sensor temperature and the pressure sensor temperature. Method according to Claim 5 or 6 , characterized in that in the absence of plausibility of the board temperature, the angle sensor temperature is used after successful plausibility against the pressure sensor temperature as the temperature of the clutch actuator (4) for determining the compensation value of Aktorweges. Method according to at least one of the preceding claims, characterized in that the calculation of the dynamic temperature model of the hydraulic fluid takes place in an actuator control device (3). Method according to at least one of the preceding claims, characterized in that the method is carried out at a temperature compensation in an unactuated closed clutch (12) with hydrostatically actuated clutch actuator (4) with a hydraulic path when the clutch (12) is in an open position ,

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