Method for automatically warming up a clutch actuator

Abstract

A method for automatically warming up a clutch actuator for a clutch of a transmission in a vehicle, wherein the clutch actuator is operable by use of pressurized fluid and configured to actuate the clutch from an engaged to a disengaged state, and/or vice versa, the method including: identifying if a temperature is below a predetermined temperature value and if the clutch actuator is leaking, and if it is identified that the temperature is below the predetermined temperature value and that the clutch actuator is leaking; then repeatedly pressurizing the clutch actuator by use of the pressurized fluid until a state is reached indicative of the clutch actuator being functional, or until a maximum run out state is reached indicative of a faulty clutch actuator.

Claims

1. A method for automatically warming up a clutch actuator for a clutch of a transmission in a vehicle, wherein the clutch actuator is operable by use of pressurized fluid and configured to actuate the clutch between an engaged and a disengaged state, the method comprising: identifying if a temperature is below a predetermined temperature value and if the clutch actuator is leaking; and in response to identifying that the temperature is below the predetermined temperature value and that the clutch actuator is leaking, repeatedly pressurizing the clutch actuator by use of the pressurized fluid until the first of: a state is reached indicative of the clutch actuator being functional; and a maximum run out state is reached indicative of a faulty clutch actuator.

2. The method according to claim 1, wherein identifying if the clutch actuator is leaking comprises: identifying if a leaking condition is fulfilled which is indicative of an unallowable positional change and/or an unallowable pressure drop over time of the clutch actuator when the clutch actuator is pressurized by the pressurized fluid.

3. The method according to claim 1, wherein the state indicative of the clutch actuator being functional is determined by identifying if a functional condition is fulfilled which is indicative of at least one of an allowable positional change and an allowable pressure drop over time of the clutch actuator when the clutch actuator is pressurized.

4. The method according to claim 1, wherein the maximum run out state is determined by identifying that the clutch actuator does not reach the disengaged or engaged state after at least one of a predetermined number of pressurizing repetitions have been performed and a predetermined run out time has been reached.

5. The method according to claim 4, wherein the at least one of the predetermined number of pressurizing repetitions and the predetermined run out time is adjustable with respect to the temperature.

6. The method according to claim 1, wherein the temperature is at least one of a clutch actuator temperature, a transmission oil temperature and an ambient temperature with respect to the vehicle.

7. The method according to claim 1, wherein the predetermined temperature value corresponds to a glass transition temperature of a seal for sealing a fluid chamber of the clutch actuator.

8. A transmission control unit for a clutch actuator for a clutch of a transmission, the transmission control unit being configured to perform the method according to claim 1.

9. A transmission for a vehicle comprising a clutch and a clutch actuator for actuating the clutch between an engaged and a disengaged state, wherein the transmission further comprises the transmission control unit according to claim 8.

10. A vehicle comprising the transmission according to claim 9.

11. The method according to claim 1, wherein identifying if the clutch actuator is leaking comprises: identifying if the clutch actuator does not reach the disengaged or engaged state when the clutch actuator is pressurized by the pressurized fluid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With reference to the appended drawings, below follows a more detailed description of embodiments of the disclosure cited as examples.

(2) In the drawings:

(3) FIG. 1 is a side view vehicle according to an example embodiment of the present disclosure;

(4) FIG. 2 is a schematic cross-sectional view of a clutch actuator according to an example embodiment of the present disclosure;

(5) FIG. 3 is a cross-sectional view of a transmission according to an example embodiment of the present disclosure; and

(6) FIG. 4 is a flowchart of a method according to an example embodiment of the present disclosure.

(7) The drawings show diagrammatic exemplifying embodiments of the present disclosure and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the disclosure is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the disclosure. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

DETAILED DESCRIPTION

(8) FIG. 1 shows a side view of a vehicle 100 according to an example embodiment of the present disclosure. The vehicle 100 is here a heavy-duty truck, adapted to tow one or more trailers (not shown). It shall however be understood that the disclosure is not limited to only this type of vehicle, but may also be used for other types of vehicles as e.g. mentioned herein. The vehicle 100 comprises an internal combustion engine, ICE, which is drivingly connected to a transmission 10 according to an example embodiment of the disclosure. The transmission 10 drivingly connects the ICE to a propulsion shaft 50, which in turn is drivingly connected to drive wheels 40.

(9) FIG. 2 shows a cross-sectional and simplified view of a clutch actuator 1 for actuating a clutch 2 as e.g. shown in FIG. 3. Accordingly, FIG. 3 shows a cross-sectional view of a transmission 10 according to an example embodiment.

(10) The transmission 10 as shown is an Automated Manual Transmission, AMT. It comprises a clutch 2 for selectively engaging and disengaging the ICE to an input shaft 3 of the transmission 10. The transmission 10 as shown further comprises an intermediate shaft 6, a number of gear wheels 7, 8, 9, 11 and a range gear 12. The range gear 12 is drivingly connected to an output shaft 13. The output shaft 13 may be drivingly connected to the propeller shaft 50. It shall be understood that the transmission 10 may be any type of transmission known to a skilled person, with e.g. more or fewer gear wheels as shown in FIG. 3, with and without the range gear 12 etc. As such, the transmission 10 as shown in FIG. 3 is only one example embodiment of a transmission according to the present disclosure.

(11) The clutch actuator 1 as shown in FIG. 2 for actuating the clutch 2 comprises a cylinder C and a piston P which is movable back and forth in the direction of the shown arrow. Accordingly, any positional change of the clutch actuator 1 is referring to a positional change of the piston P. The clutch actuator 1 further comprises at least one seal S for sealing a fluid chamber C1 which is defined and delimited by inner walls of the cylinder C. It shall be understood that the clutch actuator 1 as shown is simplified. As such, the clutch actuator 1 may comprise more parts, such one or more valves, more seals etc. The piston P is actuated by pressurizing the inside of the cylinder C by a fluid, such as by pressurized air.

(12) Referring to FIGS. 2-3, and also to FIG. 4 which shows a flowchart, a method according to example embodiments of the disclosure will be described.

(13) Thus, a method for automatically warming up a clutch actuator 1 for a clutch 2 of a transmission 10 in a vehicle 100 is provided, wherein the clutch actuator 1 is operable by use of pressurized fluid and configured to actuate the clutch 2 from an engaged to a disengaged state, and/or vice versa. The method comprises: S1: identifying if a temperature is below a predetermined temperature value and if the clutch actuator 1 is leaking, and if it is identified that the temperature is below the predetermined temperature value and that the clutch actuator 1 is leaking; then S2: repeatedly pressurizing the clutch actuator 1 by use of the pressurized fluid until a state is reached indicative of the clutch actuator 1 being functional or until a maximum run out state is reached indicative of a faulty clutch actuator 1.

(14) The predetermined temperature value may for example be in the range of −5 to −30 degrees Celsius.

(15) Identifying if the clutch actuator 1 is leaking may comprise:

(16) identifying if a leaking condition is fulfilled which is indicative of an unallowable positional change and/or an unallowable pressure drop over time of the clutch actuator 1 when the clutch actuator 1 is pressurized by the pressurized fluid. For example, it may be identified that the clutch actuator 1, i.e. the piston P, is moving at an unallowable speed when the clutch actuator 1 is pressurized, which may be considered as an unallowable positional change over time.

(17) Additionally, or alternatively, identifying if the clutch actuator 1 is leaking may comprise:

(18) identifying if the clutch actuator 1 does not reach the disengaged or engaged state when the clutch actuator 1 is pressurized by the pressurized fluid.

(19) The state indicative of the clutch actuator 1 being functional may be determined by identifying if a functional condition is fulfilled which is indicative of an allowable positional change and/or an allowable pressure drop over time of the clutch actuator 1 when the clutch actuator 1 is pressurized. Accordingly, the clutch actuator may comprise a sensor for measuring and obtaining a value indicative of a position of the piston P, and/or it may comprise a sensor for measuring and obtaining a value indicative of pressure in the fluid chamber C1.

(20) The maximum run out state may be determined by identifying that the clutch actuator 1 does not reach the disengaged or engaged state after a predetermined number of pressurizing repetitions have been performed and/or after a predetermined run out time has been reached.

(21) The predetermined number of pressurizing repetitions and/or the predetermined run out time may be adjustable with respect to the temperature.

(22) The temperature may be at least one of a clutch actuator temperature, a transmission oil temperature and an ambient temperature with respect to the vehicle 100.

(23) The predetermined temperature value may correspond to a glass transition temperature of the seal S for sealing the fluid chamber C1 of the clutch actuator 1.

(24) The method is advantageously implemented in a transmission control unit (not shown), by use of hardware and/or software. For example, the transmission control unit may comprise and/or utilize the above-mentioned computer program and/or computer readable medium. For example, the transmission control unit may obtain measurement values from the above-mentioned sensors, i.e. sensors for measuring temperature, pressure and/or position of the piston P. By use of the measurement values, the transmission control unit may issue a signal for controlling the clutch actuator 1 to be repeatedly pressurized as mentioned in the above. The transmission control unit may then also monitor the clutch actuator 1 in order to identify when the state is reached indicative of the clutch actuator 1 being functional, or until a maximum run out state is reached indicative of a faulty clutch actuator 1. In addition, the transmission control unit may also be configured to automatically control shifting of gears in the transmission 10. As such, a versatile transmission control unit may be realized which is adapted to perform various tasks relating the control of the transmission 10.

(25) It is to be understood that the present disclosure is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.