CN115335611A

CN115335611A - Method for detecting an operating state of a clutch and clutch

Info

Publication number: CN115335611A
Application number: CN202180023741.XA
Authority: CN
Inventors: 迪特马尔·赫克
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2020-04-08
Filing date: 2021-03-09
Publication date: 2022-11-11
Also published as: WO2021204322A1; DE102021106660A1

Abstract

The invention relates to a method for detecting an operating state of a clutch (12), which can be operated by an operating pressure (p) via an operating device (52) for switching the operating state, said operating pressure being subjected to a pressure deviation (pa) during pressure transmission as a difference between the clutch operating pressure (p) and an operating pressure (pm) measured at a first measuring point (56) along a transmission path (39), and at least one first pressure state (B1) of the clutch (12) being detected from the measured operating pressure (pm) in such a way that: a first pressure range (P1) of the measured operating pressure (pm) is determined, which is bounded by at least one first preset pressure value (P1), and the first operating state (B1) is detected as being present as long as the measured operating pressure (pm, pm 1) lies within the first pressure range (P1), wherein during operation of the clutch (12) a pressure deviation (pa) is determined as a function of the pressure-influencing variable (E) and the first pressure value (P1) is set as a function of the pressure-influencing variable (E). The invention further relates to such a clutch (12).

Description

Method for detecting an operating state of a clutch and clutch

Technical Field

The invention relates to a method for identifying an operating state of a clutch according to the preamble of claim 1. The invention further relates to such a clutch.

Background

DE 10 2018 128 describes a clutch in a drive train of a vehicle for transmitting torque between a clutch input and a clutch output which can be releasably connected thereto in a friction-fit manner depending on the operating state. In the powertrain, the first electric motor is engaged on the clutch output side and the internal combustion engine and the second electric motor are engaged on the clutch output side. In the closed clutch, the first electric motor, the second electric motor and/or the internal combustion engine can each output a drive torque to the driven device via the clutch. In the disengaged clutch, the second electric motor can generate a drive torque at the output and the first electric motor is driven by the internal combustion engine in generator mode.

If the switching of the operating state of the clutch is caused by the operating pressure provided by the pressure device via the operating device, the operating state of the clutch can be inferred via knowledge of the clutch operating pressure as the operating pressure at the operating device. If the clutch actuating pressure at the actuating device cannot be detected directly on account of the installation space, a pressure measurement can be carried out at a first measurement location which is located along a transmission path connected to the actuating device for transmitting the actuating pressure between the pressure device which supplies the actuating pressure and the actuating device.

In the pressure transmission via the transmission path, however, a pressure deviation exists between the clutch actuating pressure and the actuating pressure measured at the first measuring point. The pressure deviations can be generated, for example, by a line pressure drop in the transmission path and lead to an inaccurate detection of the clutch actuating pressure and thus the operating state of the clutch.

Disclosure of Invention

The aim of the invention is to identify the operating state of a clutch more accurately. The clutch should be more cost-effective to construct and operate more reliably.

At least one of the objects is achieved by a method having the features according to claim 1. Thereby, the operating state can be identified more accurately. The clutch can be operated more reliably and more safely. The clutch can be more cost-effectively designed and can be constructed more simply.

The clutch can be disposed in the powertrain. The drive train can be arranged in a vehicle, in particular in a motor vehicle. The powertrain can be a hybrid powertrain.

The clutch input can be connected to the first drive element. The first drive element is capable of providing a first drive torque. The first drive element can be an internal combustion engine.

The clutch output can be connected to a driven device. The first drive torque can be transmitted to the output via the closed clutch.

The driven device can be a transmission. The driven device can be formed by at least one wheel.

The drive train can have a second drive element for providing a second drive torque. The second drive element can be engaged on the clutch input side or on the clutch output side. The second drive torque can be applied on the clutch input side or on the clutch output side. The second drive element can be an electric motor.

The third drive element can be engaged on the clutch input side or on the clutch output side. The third drive element can be an electric motor. The third drive element can provide a third drive torque and/or act as a generator. The third drive torque can be applied on the clutch input side or on the clutch output side. The first, second and third drive torques can be operatively arranged in series.

The pressure device can have a fluid pressure pump. The operating pressure can be a fluid pressure. The fluid can be liquid and/or gaseous. The operating pressure can be provided hydraulically or pneumatically. The pressure device can also provide a supply fluid flow for lubricating and/or cooling the first and/or second drive element, in particular.

The clutch may be a K0 clutch. A clutch is operatively disposed between the first and second drive elements. The first drive element can be connected to the second drive element via a clutch. In a completely disengaged clutch, the transmission of the first drive torque via the clutch can be interrupted.

The clutch can be closed (normally closed) or opened (normally open) when not operated, i.e. when there is no operating pressure. In this connection, the clutch is closed or opened when operated by the operating pressure. Torque transmission can take place in the closed clutch. In the disengaged clutch, the torque transmission can be interrupted.

The first operating state can correspond to a closed or open clutch. The first operating state can exist when the clutch operating pressure is in a pressure range that is in a determined torque range of the clutch torque as the torque transmittable via the clutch.

The measured operating pressure can be measured by means of a pressure sensor associated with the transmission section.

The switching of the operating state can be a switching between a first operating state and a second operating state. The pressure deviation can be generated by a line pressure drop in the transfer path. The sign of the pressure deviation can be correlated with the operating direction of the switching of the operating state, i.e. with: whether to switch from the first operating state to the second operating state or vice versa.

The pressure deviation can be determined from the temperature. The first pressure value can be set according to the temperature. The correlation between the pressure deviation and/or the first pressure value and the temperature can be detected in advance.

In a preferred embodiment of the invention, the pressure-influencing variable can be measured at the second measuring location. Thereby, the pressure-influencing variable can be detected accurately and quickly.

In a particular embodiment of the invention, the second measurement position is associated with a pressure device or a transmission path section. The second measurement location can be associated with a fluid pressure pump.

In a preferred embodiment of the invention, the first measuring position is arranged offset from or coincident with the second measuring position. This makes optimal use of the installation space possible.

In a particular embodiment of the invention, the pressure-influencing variable is the volume flow and/or the pressure gradient which is present when the operating pressure is changed. The pressure gradient can be measured by a pressure sensor, which also detects the measured operating pressure.

In a preferred embodiment of the invention, the correlation between the first pressure value and the pressure-influencing variable is detected beforehand. The pressure deviation and/or the correlation between the first pressure value and the pressure-influencing variable can be detected before the clutch is put into operation, preferably before the first time it is put into operation. The correlation can be calculated and/or measured. The correlation can be maintained in an association table (look-up table) that can be invoked during operation of the clutch.

In a particular embodiment of the invention, the second operating state of the clutch is identified on the basis of the measured operating pressure in such a way that: a second pressure range of the measured operating pressure, which is bounded by at least one preset second pressure value, is determined, and the second operating state is recognized as present as long as the measured operating pressure lies within the second pressure range. The second operating state can correspond to a closed or open clutch.

In another particular embodiment of the invention, the second pressure value is set in dependence on a pressure influencing variable. The pressure deviation at the time of setting the second pressure value can be different from the pressure deviation at the time of setting the first pressure value.

In a preferred embodiment of the invention, the second pressure value is less than the first pressure value, and the first pressure range is non-overlapping with the second pressure range. A pressure range may be expanded between the first and second pressure values. If the measured operating pressure is in the pressure range, the operating state cannot be associated one-to-one with the first or second operating state.

In order to achieve at least one of the above-mentioned objects, a clutch for transmitting torque between a drive element and a driven device is furthermore proposed, having a clutch input rotatable about a rotational axis and a clutch output releasably connectable thereto in a friction-fit manner for transmitting torque as a function of an operating pressure provided via an operating device, wherein an operating state of the clutch can be identified by a method having at least one of the features described above.

Further advantages and advantageous embodiments of the invention result from the description of the figures and the drawings.

Drawings

The invention is described in detail below with reference to the drawings. Showing in detail:

fig. 1 shows a hybrid powertrain with a clutch according to a particular embodiment of the invention.

Fig. 2 shows a hydraulic device for a clutch according to a particular embodiment of the invention.

FIG. 3 shows a graph of operating pressure when using the method of one particular embodiment of the invention.

Detailed Description

Fig. 1 illustrates a hybrid powertrain 10 having a clutch 12 in accordance with a particular embodiment of the present invention. The hybrid powertrain 10 is provided in a vehicle and includes: the internal combustion engine 14 as a first drive element, which can provide a first drive torque; the first electric motor 16 as a second drive element, which can provide a second drive torque; and a second motor 18 as a third drive element.

The internal combustion engine 14, the first electric motor 16, and the second electric motor 18 are operatively connected in series. The first electric motor 16 is directly connected to a driven device 20, which is formed by a transmission 22. The driven device 20 is connected with wheels 24 for forward movement of the vehicle. The internal combustion engine 14 is directly connected to the second electric motor 18.

The clutch 12 is operatively disposed between the internal combustion engine 14 and the driven device 20 and operatively between the first electric motor 16 and the second electric motor 18. The clutch 12 has a clutch input 26 and a clutch output 28 which can be releasably connected in a friction-fitting manner thereto. The clutch input 26 and the clutch output 28 are rotatable about a common axis of rotation. The second electric motor 18 and the internal combustion engine 14 are engaged on the clutch input side and the first electric motor 16 is engaged on the clutch output side.

The clutch 12 is operable by an operating pressure, which is provided by a pressure device. By operating the clutch 12, the clutch can be switched between a first operating state in which, for example, torque transmission via the clutch 12 is performed, and a second operating state in which, for example, torque transmission via the clutch 12 is interrupted. In a first operating state, the clutch input 26 is connected in a friction-fit manner with the clutch output 28 and a torque transmission via the clutch is established. In the second operating state, the clutch 12 is disengaged and torque transmission via the clutch 12 is interrupted.

In the second operating state of the clutch 12, the vehicle is driven exclusively by means of the second drive torque, which is provided by means of the first electric motor 16. The internal combustion engine 14 can be in operation or switched off. If the internal combustion engine 14 is in operation, the first drive torque can operate the second electric motor 18, which converts the first drive torque into electrical energy as a generator and supplies it to the electrical energy store and/or the first electric motor 16.

In addition or alternatively to the second drive torque of the first electric motor 16, a first drive torque is provided at the output 20 when the internal combustion engine 14 is running and in the first operating state of the clutch 12.

In fig. 2, a hydraulic device 30 for the clutch 12 of a particular embodiment of the present invention is shown. A hydraulic device 30 is provided in the vehicle and induces an operating pressure for operating the clutch 12 via a pressure device 32, which has a fluid pressure pump 33. The fluid pressure pump 33 is designed as a gear pump and is operable by an electronic pump actuator 34, which has an electric motor 36. The motor 36 is controlled by a control unit 38.

The fluid pressure pump 33 causes an operating pressure in the hydraulic device 30 in the manner: the fluid pressure pump operates at a pump rotational speed. The fluid pressure pump 33 in this case supplies the operating pressure in a first fluid branch 40, which forms the transfer path 39 between the pressure device 32 and the clutch 12, in one rotational direction and the fluid pressure in a second fluid branch 42 in the opposite rotational direction. The second fluid branch 42 is provided here for a supply fluid flow which is conducted via a heat exchanger 44, for example to cool and/or lubricate the electric motor and/or at least one bearing.

The first fluid branch 40 hydraulically connects the fluid pressure pump 33 via the valve 46 to a parking lock 48 with a travel sensor 50 for detecting a parking lock position and to an operating device 52 of the clutch 12. Depending on the valve position of the valve 46, the parking lock 48 and/or the clutch 12 can be hydraulically actuated by means of an actuating pressure. The actuating device 52 can be a CSC actuating mechanism having an output cylinder 54 arranged concentrically to the rotational axis of the clutch 12, which converts an actuating pressure into an actuating force acting on a friction region 55 of the clutch 12.

The fluid pressure pump 33 is switchable between a first operation mode and a second operation mode. In the first operating mode, the fluid pressure pump 33 can generate a supply fluid flow in the second fluid branch 42, and in the second operating mode, the operating pressure in the first fluid branch 40 is provided for operating the clutch 12 and/or for operating the parking brake 48.

The clutch 12 can be configured as a (normally open) clutch that is disengaged when not operated. When the clutch 12 is actuated, a torque transmission can occur between the clutch input and the clutch output of the clutch 12. When the clutch 12 is not operated, the torque transmission via the clutch 12 is interrupted corresponding to the clutch 12 being disconnected.

Along the transfer section, a pressure sensor 58 for detecting the operating pressure as a measured operating pressure is provided at the first measurement location 56. The switching of the operating state of the clutch 12 via the operating device 52 is brought about by changing the operating pressure. Since the operating pressure is transmitted between the pressure device 32 and the operating device 52, a pressure deviation exists between the operating pressure acting on the operating device 52 as clutch operating pressure and the operating pressure measured at the first measuring point 56 via the transmission path 39.

When the clutch operating pressure, which is the operating pressure at the operating device 52, is known, the operating state of the clutch 12 can be inferred. Since the first measuring point 56 is not directly applied to the actuating device 52 due to the installation space, the measured actuating pressure can differ from the clutch actuating pressure as a function of the pressure deviation during the pressure transmission via the transmission path 39. The pressure deviation can be caused, for example, by a line pressure drop in the transfer path 39.

The stroke sensor 50 and the pressure sensor 58 are electrically connected to the control unit 38. The control unit 38 is connected, for example, via a CAN data line 60 to a power control unit 62, which, for example, controls at least one electric motor which provides a drive torque for driving the vehicle.

Fig. 3 shows a graph of the operating pressure when applying the method of one particular embodiment of the invention. In fig. 3 a), the operating pressure p is plotted in relation to the torque transmittable via the clutch as the clutch torque M. Here, the clutch actuating pressure pk is shown as an actuating pressure at the clutch actuating device in comparison to the measured actuating pressure pm shifted by the pressure deviation pa.

The measured operating pressure pm is divided into a first measured operating pressure pm1 and a second measured operating pressure pm2, in relation to the operating direction of the clutch. For example, a second measured operating pressure pm2 is present when switching from the first operating state B1 to the second operating state B2. In the first operating state B1, the clutch can be closed, and in the second operating state B2, the clutch can be opened.

The switching from the second operating state B2 to the first operating state B1 takes place by increasing the operating pressure p and corresponds to the profile of the first measured operating pressure pm 1. The switching from the first operating state B1 to the second operating state B2 takes place by a reduction of the operating pressure p and corresponds to the course of the second measured operating pressure pm 2.

The pressure deviation pa is dependent on a plurality of influences and can cause large deviations between the clutch operating pressure pk and the corresponding measured operating pressure pm. For example, the first operating state B1 of the clutch is identified in relation to the first measured operating pressure pm1 by: a first pressure range P1 of the measured operating pressure pm, which is delimited by at least one preset first pressure value pf1, is determined and the first operating state B1 is identified as present as long as the first measured operating pressure pm1 lies within the first pressure range P1.

Furthermore, for example, a second operating state B2 of the clutch is identified in relation to a second measured operating pressure pm2 in that: a second pressure range P2 of the measured operating pressure pm, which is delimited by at least one preset second pressure value pf2, is determined, and a second operating state B2 is identified as present as long as the second measured operating pressure pm2 is in the second pressure range P2.

The first pressure value pf1 and the second pressure value pf2 can be determined during operation of the clutch in the absence of an accurate detection of the pressure deviation pa in that: the respective maximum pressure deviation pa to be expected during operation is assumed and is associated as a safety range with the measured operating pressure pm, whereby the operating state of the clutch is reliably detected via the first and second measured operating pressures pm1, pm 2.

Thus, the pressure range U between the first and second pressure values pf1, pf2 serves as an unreliable range not one-to-one indicative of the clutch operating state, which is greater than the actual pressure range M delimiting the first operating state B1 from the second operating state B2 of the clutch operating pressure pk. In order to reduce the pressure range U that extends between the first and second pressure values pf1, pf2, and thereby improve the accuracy of identifying the operating state, the pressure deviation pa is set according to the pressure-influencing variable, and the first and second pressure values pf1, pf2 are set according to the pressure-influencing variable, respectively, during operation of the clutch.

The correlation between the operating pressure p and the pressure influencing variable E is depicted in fig. 3 b). The pressure-influencing variable E can be a volumetric flow, for example in l/min, when switching the operating state of the clutch. The volume flow can be measured at the pressure device or at a second measurement location, which is located along the transfer path between the pressure device and the operating device. If a measurement of the volume flow is not possible, the pressure-influencing variable can also be a temporal pressure gradient of the operating pressure p, which can be measured, for example, via a pressure sensor at the first measurement location.

The first pressure value p1 is variable and is set in dependence on the pressure-influencing variable E. Likewise, the second pressure value p2 is variable and set in relation to the pressure-influencing variable E. In a static situation, i.e. when the pressure influencing variable E is equal to zero, then the first pressure value p1 corresponds to the associated pressure value of the clutch operating pressure pk and the second pressure value p2 corresponds to the associated pressure value of the clutch operating pressure pk.

The correlation of the first and second pressure values p1, p2 with the pressure-influencing variable can be detected beforehand, for example before the clutch is put into operation, in particular before the clutch is put into operation for the first time. For example, the correlation can be saved in a callable association table (lookup table). Via the pressure-influencing variable E measured when the operating state is switched by changing the operating pressure p, the pressure deviation pa is calculated and the first pressure value p1 and the second pressure value p2 are set in association with the pressure deviation pa, respectively. Thereby, the operating state of the clutch can be detected more accurately and the pressure range U is adapted to the pressure range M.

Description of the reference numerals

10. Hybrid power assembly

12. Clutch device

14. Internal combustion engine

16. A first motor

18. Second motor

20. Driven device

22. Speed variator

24. Wheel of vehicle

26. Clutch input

28. Clutch output

30. Hydraulic device

32. Pressure equipment

33. Fluid pressure pump

34. Electronic pump actuator

36. Electric motor

38. Control unit

39. Transfer section

40. First fluid branch

42. Second fluid branch

44. Heat exchanger

46. Valve with a valve body

48. Parking lock

50. Stroke sensor

52. Operating device

54. Output cylinder

55. Friction area

56. First measuring position

58. Pressure sensor

60 CAN data line

62. Power control unit

B1 A first operating state

B2 A second operating state

E pressure influencing variable

Moment of clutch M

p operating pressure

p1 first pressure value

p2 second pressure value

pa pressure deviation

pf1 first pressure value

pf2 second pressure value

pk Clutch operating pressure

pm measured operating pressure

P1 first pressure range

P2 second pressure range

Range of M pressure

U pressure range.

Claims

1. A method for detecting an operating state of a clutch (12) having a clutch input (26) which is rotatable about an axis of rotation and a clutch output (28) which can be connected releasably to the clutch input in a friction-fit manner for torque transmission, and

the clutch can be operated via an operating device (52) by an operating pressure (p) provided by a pressure device (32) for switching an operating state, the operating pressure being applied at the operating device (52) as a clutch operating pressure (pk) and being transferable via a transfer section (39) present between the pressure device (32) and the operating device (52), and the operating pressure being subjected to a pressure deviation (pa) at the time of pressure transfer as a difference between the clutch operating pressure (p) and an operating pressure (pm) measured at a first measuring location (56) along the transfer section (39), and

identifying at least one first operating state (B1) of the clutch (12) in relation to the measured operating pressure (pm),

the method comprises the following steps: determining a first pressure range (P1) of the measured operating pressure (pm) which is bounded by at least one preset first pressure value (pf 1, P1), and recognizing the first operating state (B1) as present as long as the measured operating pressure (pm, pm 1) lies within the first pressure range (P1),

it is characterized in that the preparation method is characterized in that,

during operation of the clutch (12), the pressure deviation (pa) is determined as a function of a pressure-influencing variable (E), and

the first pressure value (p 1) is set in dependence on the pressure influencing variable (E).

2. The method as set forth in claim 1, wherein,

it is characterized in that the preparation method is characterized in that,

the pressure-influencing variable (E) is measured at a second measurement location.

3. The method as set forth in claim 2, wherein,

it is characterized in that the preparation method is characterized in that,

the second measurement position is associated with the pressure device (32) or the transfer section (39).

4. The method according to claim 2 or 3,

it is characterized in that the preparation method is characterized in that,

the first measurement position (56) is arranged offset or coincident with the second measurement position.

5. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the pressure-influencing variable (E) is the volume flow and/or the pressure gradient which prevails when the operating pressure (p) is changed.

6. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

-detecting in advance a correlation between said first pressure value (p 1) and said pressure influencing variable (E).

7. The method according to any one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

a second operating state (B2) of the clutch (12) is identified on the basis of the measured operating pressure (pm) by: a second pressure range (P2) of the measured operating pressure (pm) is determined, which is delimited by at least one preset second pressure value (P2), and the second operating state (B2) is detected as present as long as the measured operating pressure (pm, pm 2) lies within the second pressure range (P2).

8. The method of claim 7, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the second pressure value (p 2) is set in accordance with the pressure-influencing variable (E).

9. The method according to claim 7 or 8,

it is characterized in that the preparation method is characterized in that,

the second pressure value (P2) is smaller than the first pressure value (P1) and the first pressure range (P1) is non-overlapping with the second pressure range (P2).

10. A clutch (12) for transmitting torque between a drive element (14) and a driven device (20), having a clutch input (26) which is rotatable about an axis of rotation and a clutch output (28) which can be releasably connected in a friction-fitting manner to the clutch input for transmitting torque in relation to an operating pressure (p) which is provided via an operating device (52), wherein an operating state of the clutch (12) is identifiable by a method according to one of the preceding claims.