Method for identifying an operating state of a clutch and clutch

Abstract

The invention relates to a method for identifying an operating state of a clutch (12), which can be operated via an operating device (52) by an operating pressure (p) for switching the operating state, which, upon pressure transmission, is subjected to a pressure deviation (pa) as a difference between the clutch operating pressure (p) and the operating pressure (pm) measured at a first measuring location (56) along a transmission path (39), and at least one first pressure state (B1) of the clutch (12) is identified 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 pressure value (p1) preset, and the first operating state (B1) is identified as present as long as the measured operating pressure (pm, pm1) lies within the first pressure range (P1), wherein during the operation of the clutch (12), the pressure deviation (pa) is determined from a pressure-influencing variable (E), and the first pressure value (p1) is set in dependence on the pressure-influencing variable (E). Furthermore, the invention relates to such a clutch (12).

Description

TECHNICAL FIELD

[0001] The invention relates to a method for identifying an operating state of a clutch. Furthermore, the invention relates to such a clutch. BACKGROUND

[0002] In DE 10 2018 128 96 a clutch for transmitting torque between a clutch input and a clutch output which can be releasably connected to it frictionally depending on an operating state in a powertrain of a vehicle is described. In the powertrain a first electric motor is engaged on the clutch output side and an internal combustion engine and a 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 output a drive torque to a driven device via the clutch, respectively. In the open clutch the second electric motor can cause a drive torque at the driven device and the first electric motor is driven by the internal combustion engine in a generator operation.

[0003] If the switching of the operating state of the clutch is caused via an operating device by an operating pressure provided by a pressure device, via the knowledge of the clutch operating pressure as the operating pressure at the operating device, the operating state of the clutch can be inferred. If the clutch operating pressure at the operating device cannot be detected directly due to a construction space, a pressure measurement can be carried out at a first measuring position between the pressure device providing the operating pressure and the operating device along a transmission path for transmitting the operating pressure connected to the operating device.

[0004] In the pressure transmission via the transmission path, however, a pressure deviation between the clutch operating pressure and the operating pressure measured at the first measuring position exists. The pressure deviation can be produced, for example, by a line pressure drop in the transmission path and causes an inaccurate identification of the operating state of the clutch from the clutch operating pressure. SUMMARY

[0005] It is an object of the invention to identify the operating state of the clutch more accurately. The clutch should be more cost-advantageously embodied and more reliably operated.

[0006] At least one of the objects is achieved by a method having the features described below. 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-advantageously embodied and more simply constructed.

[0007] The clutch can be arranged in a powertrain. The powertrain can be arranged in a vehicle, in particular in a motor vehicle. The powertrain can be a hybrid powertrain.

[0008] The clutch input can be connectable with a first drive element. The first drive element can provide a first drive torque. The first drive element can be an internal combustion engine.

[0009] The clutch output can be connectable with a driven device. The first drive torque can be transmitted via the closed clutch to the driven device.

[0010] The driven device can be a transmission. The driven device can be formed by at least one wheel.

[0011] The powertrain 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.

[0012] 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 serve 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 arranged in series.

[0013] 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, in particular, the first and / or second drive element.

[0014] The clutch can be a K0 clutch. The clutch can be arranged operatively between the first and second drive elements. The first drive element can be connected via the clutch with the second drive element. In a fully open clutch, the transmission of the first drive torque via the clutch can be interrupted.

[0015] The clutch can be closed (normally closed) or open (normally open) in the unoperated state, i.e. in the absence of an operating pressure. In connection therewith, the clutch is closed or open when operated by an operating pressure. In a closed clutch, torque transmission can take place. In an open clutch, torque transmission can be interrupted.

[0016] 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 which is in a determined torque range as clutch torque which is transmittable via the clutch.

[0017] The measured operating pressure can be measured by means of a pressure sensor associated with the transmission path.

[0018] The switching of the operating state can be a switching between the first operating state and the second operating state. The pressure deviation can be generated by a drop in the line pressure in the transmission path. The sign of the pressure deviation can be related to the operating direction of the switching of the operating state, i.e. to whether a switching from the first operating state to the second operating state or vice versa takes place.

[0019] The pressure deviation can be determined as a function of the temperature. The first pressure value can be set as a function of the temperature. A correlation between the pressure deviation and / or the first pressure value and the temperature can be detected beforehand.

[0020] In a preferred embodiment of the application, the pressure-influencing variable can be measured at the second measuring point. The pressure-influencing variable can thereby be detected precisely and quickly.

[0021] In a specific embodiment of the application, the second measuring point is associated with the pressure device or the transmission path. The second measuring point can be associated with the fluid pressure pump.

[0022] In a preferred embodiment of the application, the first measuring point is arranged offset or congruently to the second measuring point. The installation space can thereby be used optimally.

[0023] In a specific embodiment of the application, the pressure-influencing variable is a volume flow and / or a pressure gradient which exists upon a change in the operating pressure. The pressure gradient can be measured by a pressure sensor which also detects the measured operating pressure.

[0024] In a preferred embodiment of the application, a correlation between the first pressure value and the pressure-influencing variable is detected beforehand. The correlation between the pressure deviation and / or the first pressure value and the pressure-influencing variable can be detected before the clutch is put into operation, preferably for the first time. The correlation can be calculated and / or measured. The correlation can be saved in an associated table (look-up table) which can be called up during operation of the clutch.

[0025] In a specific embodiment of the application, the second operating state of the clutch is identified as a function of the measured operating pressure in such a way that a second pressure range of the measured operating pressure which is limited by at least one preset second pressure value is determined, and the second operating state is identified as existing as long as the measured operating pressure is within the second pressure range. The second operating state can correspond to a closed or open clutch.

[0026] In a further specific embodiment of the application, the second pressure value is set as a function of the pressure-influencing variable. The pressure deviation in setting the second pressure value can be different from the pressure deviation in setting the first pressure value.

[0027] In a preferred embodiment of the application, the second pressure value is smaller than the first pressure value and the first pressure range has no overlap with the second pressure range. The pressure range can be spread between the first and the second pressure value. If the measured operating pressure is in the pressure range, the operating state cannot be associated one-to-one with the first or the second operating state.

[0028] Further, in order to achieve at least one of the above-mentioned tasks, a clutch for transmitting torque between a drive element and a driven device is proposed, having a clutch input rotatable about an axis of rotation and a clutch output releasably connectable frictionally to the clutch input for transmitting torque depending on an operating pressure provided via an operating device, wherein an operating state of the clutch is identifiable by a method having at least one of the features described above.

[0029] Further advantages and advantageous design of the application result from the description and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] The application is described in detail below with reference to the drawings. Shown in detail are:

[0031] Figure 1 A hybrid powertrain with a clutch having a particular embodiment of the application is shown.

[0032] Figure 2 A hydraulic device for a clutch of a particular embodiment of the application is shown.

[0033] Figure 3 A graph of an operating pressure when using a method of a particular embodiment of the application is shown. DETAILED DESCRIPTION

[0034] Figure 1 A hybrid powertrain 10 with a clutch 12 having a particular embodiment of the application is shown. The hybrid powertrain 10 is arranged in a vehicle and comprises an internal combustion engine 14 as a first drive element which can provide a first drive torque, a first electric motor 16 as a second drive element which can provide a second drive torque, and a second electric motor 18 as a third drive element.

[0035] The internal combustion engine 14, the first electric motor 16 and the second electric motor 18 are effectively connected in series. The first electric motor 16 is directly connected with a driven device 20 which is formed by a transmission 22. The driven device 20 is connected with wheels 24 for a forward movement of the vehicle. The internal combustion engine 14 is directly connected with the second electric motor 18.

[0036] A clutch 12 is arranged operatively between the 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 is releasably connectable in frictional engagement therewith. The clutch input 26 and the clutch output 28 are rotatable about a common axis of rotation. The second electric motor 18 and the combustion engine 14 are engaged on the clutch input side and the first electric motor 16 is engaged on the clutch output side.

[0037] The clutch 12 is operable by an operating pressure which is provided by a pressure device. By operating the clutch 12, the clutch is switchable between a first operating state in which, for example, a torque transmission via the clutch 12 takes place, and a second operating state in which, for example, a torque transmission via the clutch 12 is interrupted. In the first operating state, the clutch input 26 is connected in frictional engagement with the clutch output 28 and a torque transmission via the clutch is established. In the second operating state, the clutch 12 is open and a torque transmission via the clutch 12 is interrupted.

[0038] In the second operating state of the clutch 12, the vehicle is driven exclusively by a second drive torque which is provided by the first electric motor 16. Here, the combustion engine 14 can be in operation or switched off. If the 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 provides it to the electrical energy store and / or the first electric motor 16.

[0039] In addition or alternatively to the second drive torque of the first electric motor 16, a first drive torque is provided at the driven device 20 when the combustion engine 14 is in operation and in the first operating state of the clutch 12.

[0040] In Figure 2 A hydraulic device 30 for a clutch 12 of one specific embodiment of the application is shown in Fig. 1. The hydraulic device 30 is arranged in the vehicle and causes 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 configured as a gear pump and is operable by an electronic pump actuator 34, which has an electric motor 36. The electric motor 36 is controlled by a control unit 38.

[0041] The fluid pressure pump 33 causes an operating pressure in the hydraulic device 30 in such a way that the fluid pressure pump is operated at a pump rotational speed. Here, the fluid pressure pump 33 provides an operating pressure in a first fluid branch 40 of a transmission path 39 formed between the pressure device 32 and the clutch 12 in one rotational direction and a fluid pressure in a second fluid branch 42 in the opposite rotational direction. The second fluid branch 42 is here provided 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.

[0042] The first fluid branch 40 hydraulically connects the fluid pressure pump 33 via a valve 46 with a park lock 48 and an operating device 52 of the clutch 12, the park lock having a travel sensor 50 for identifying a park lock position. Depending on the valve position of the valve 46, the park lock 48 and / or the clutch 12 can be hydraulically operated by the operating pressure. The operating device 52 can be a CSC operating mechanism having an output cylinder 54 arranged concentrically to the rotational axis of the clutch 12, which transforms the operating pressure into an operating force acting on a friction area 55 of the clutch 12.

[0043] The fluid pressure pump 33 can be switched between a first operating mode and a second operating mode. In the first operating mode, the fluid pressure pump 33 can cause a supply fluid flow in the second fluid branch 42, and in the second operating mode, an operating pressure is provided in the first fluid branch 40 for operating the clutch 12 and / or for operating the park lock 48.

[0044] The clutch 12 can be designed as a disengaged (normally open) clutch in the unoperated state. Upon operating the clutch 12, a torque transmission can exist between a clutch input and a clutch output of the clutch 12. In the unoperated state of the clutch 12, corresponding to the disengaged clutch 12, the torque transmission via the clutch 12 is interrupted.

[0045] Along the transmission path, a pressure sensor 58 for detecting the operating pressure as a measured operating pressure is provided at a first measuring position 56. The switching of the operating state of the clutch 12 via the operating device 52 is caused by a change in 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 applied on the operating device 52 as a clutch operating pressure and the operating pressure measured at the first measuring position 56 by the transmission path 39.

[0046] Upon knowledge of the clutch operating pressure as the operating pressure at the operating device 52, the operating state of the clutch 12 can be inferred. Since the first measuring location 56 is not directly applied at the operating device 52 due to construction space, upon pressure transmission via the transmission path 39, the measured operating pressure can differ from the clutch operating pressure according to a pressure deviation. The pressure deviation can be caused, for example, by a line pressure drop in the transmission path 39.

[0047] The travel sensor 50 and the pressure sensor 58 are electrically connected with the control unit 38. The control unit 38 is connected, for example, via a CAN data line 60 with a power control unit 62, which controls, for example, at least one electric motor that provides a drive torque for driving the vehicle.

[0048] Figure 3 A diagram of the operating pressure is shown when applying the method of one specific embodiment of the application. In Figure 3 In a), the operating pressure p is plotted in relation to the torque that can be transmitted via the clutch as clutch torque M. Here, the clutch operating pressure pk is shown as the operating pressure at the clutch operating device in comparison to the measured operating pressure pm, which is shifted by a pressure deviation pa.

[0049] The measured operating pressure pm is divided into a first measured operating pressure pm1 and a second measured operating pressure pm2, which are related to the operating direction of the clutch. For example, the second measured operating pressure pm2 is present when switching from a first operating state Bl to a second operating state B2. In the first operating state Bl, the clutch can be closed, and in the second operating state B2, the clutch can be open.

[0050] The switching from the second operating state B2 to the first operating state Bl takes place by increasing the operating pressure p and corresponds to a change curve of the first measured operating pressure pm1. The switching from the first operating state Bl to the second operating state B2 takes place by a decrease of the operating pressure p and corresponds to a change curve of the second measured operating pressure pm2.

[0051] The pressure deviation pa is related to a plurality of influences and can cause a large deviation between the clutch operating pressure pk and the corresponding measured operating pressure pm. For example, the first operating state Bl of the clutch is identified in relation to the first measured operating pressure pm1 in such a way that a first pressure range Pl of the measured operating pressure pm is determined, which is limited by at least one preset first pressure value pf1, and the first operating state Bl is identified as present as long as the first measured operating pressure pm1 is within the first pressure range Pl.

[0052] Furthermore, the second operating state B2 of the clutch is identified in correlation with the second measured operating pressure pm2 in that a second pressure range P2 of the measured operating pressure pm is determined which is limited by at least one preset second pressure value pf2 and the second operating state B2 is identified as present as soon as the second measured operating pressure pm2 is in the second pressure range P2.

[0053] The determination of the first pressure value pf1 and the second pressure value pf2 can be carried out during the operation of the clutch without a precise knowledge of the pressure deviation pa in that a respective maximum in-operation-expected pressure deviation pa is assumed and associated with the measured operating pressure pm as a safety range, by means of which the operating state of the clutch is reliably identified via the first and second measured operating pressure pm1, pm2.

[0054] The pressure range U between the first and second pressure values pf1, pf2 is thereby greater than the actual pressure range M of the clutch operating pressure pk which delimits the first operating state B1 from the second operating state B2 as an unreliable range which does not unambiguously explain the operating state of the clutch. In order to reduce the pressure range U which develops between the first and second pressure values pf1, pf2 and thereby improve the accuracy of the identification of the operating state, the pressure deviation pa is set in dependence on the pressure influencing variable during the operation of the clutch and the first pressure value pf1 and the second pressure value pf2 are each set in dependence on the pressure influencing variable.

[0055] In Figure 3 The correlation between the operating pressure p and the pressure influencing variable E is depicted in b). The pressure influencing variable E can be a volume flow in l / min, for example, at the time of switching the operating state of the clutch. The volume flow can be measured at the pressure device or at a second measuring location which is between the pressure device and the operating device along the transmission path. If the measurement of the volume flow is not possible, the pressure influencing variable can also be a time pressure gradient of the operating pressure p, which can be measured, for example, via a pressure sensor at the first measuring location.

[0056] The first pressure value p1 is variable here and is set in correlation with the pressure influencing variable E. Likewise, the second pressure value p2 is variable and is set in correlation with the pressure influencing variable E. In the static case, i.e. when the pressure influencing variable E is equal to zero, 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.

[0057] The correlation of the first and second pressure values p1, p2 with the pressure influencing variable can be detected in advance, for example before the clutch is put into operation, in particular for the first time. For example, the correlation can be saved in an assignable correlation table (look-up table). Via the pressure influencing variable E measured when switching the operating state 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 each set in correlation with the pressure deviation pa. Thereby, the operating state of the clutch can be detected more accurately and the pressure range U is adapted to the pressure range M.

[0058] Reference Signs List

[0059] [1] 10 hybrid assembly

[0060] [2] 12 clutch

[0061] [3] 14 internal combustion engine

[0062] [4] 16 first electric motor

[0063] [5] 18 second electric motor

[0064] [6] 20 driven device

[0065] [7] 22 transmission

[0066] [8] 24 wheel

[0067] [9] 26 clutch input

[0068]

[10] 28 clutch output

[0069]

[11] 30 hydraulic device

[0070]

[12] 32 pressure device

[0071]

[13] 33 fluid pressure pump

[0072]

[14] 34 electronic pump actuator

[0073]

[15] 36 electric motor

[0074]

[16] 38 control unit

[0075]

[17] 39 transmission path

[0076]

[18] 40 first fluid branch

[0077]

[19] 42 second fluid branch

[0078]

[20] 44 heat exchanger

[0079]

[21] 46 valve

[0080]

[22] 48 parking lock

[0081]

[23] 50 travel sensor

[0082]

[24] 52 operating device

[0083]

[25] 54 output cylinder

[0084]

[26] 55 friction region

[0085]

[27] 56 first measurement position

[0086]

[28] 58 pressure sensor

[0087]

[29] 60 CAN data line

[0088]

[30] 62 power control unit

[0089]

[31] B1 first operating state

[0090]

[32] B2 second operating state

[0091]

[33] E pressure influencing variable

[0092]

[34] M clutch torque

[0093]

[35] p operating pressure

[0094]

[36] pi first pressure value

[0095]

[37] p2 second pressure value

[0096]

[38] pa pressure deviation

[0097]

[39] pf1 first pressure value

[0098]

[40] pf2 second pressure value

[0099]

[41] pk clutch operating pressure

[0100]

[42] pm measured operating pressure

[0101]

[43] P1 first pressure range

[0102]

[44] P2 second pressure range

[0103]

[45] M pressure range

[0104] U pressure range.

Claims

1. A method for identifying the operating state of a clutch (12), the clutch having a clutch input end (26) rotatable about a rotation axis and a clutch output end (28) releasable to be frictionally engaged with the clutch input end for transmitting torque, and The clutch can be operated via an operating device (52) by an operating pressure provided by a pressure device (32) to switch operating states. This operating pressure is applied at the operating device (52) as a clutch operating pressure and can be transmitted via a transmission path (39) between the pressure device (32) and the operating device (52). During pressure transmission, the operating pressure undergoes a pressure deviation as the difference between the clutch operating pressure and the operating pressure measured along the transmission path (39) at a first measuring position (56). At least one first operating state (B1) of the clutch (12) is identified in relation to the measured operating pressure. The method is as follows: a first pressure range is determined by the measured operating pressure, which is limited by at least one preset first pressure value; and the first operating state (B1) is identified as existing as long as the measured operating pressure is within the first pressure range. Its features are, During the operation of the clutch (12), the pressure deviation is determined based on the pressure influence variable (E), and The first pressure value is set according to the pressure influence variable (E), which is the volumetric flow and / or pressure gradient present when the operating pressure changes.

2. The method according to claim 1, Its features are, The pressure influence variable (E) is measured at the second measurement location.

3. The method according to claim 2, Its features are, The second measurement location is associated with the pressure device (32) or the transmission route (39).

4. The method according to claim 2, Its features are, The first measurement position (56) is set either offset from or consistent with the second measurement position.

5. The method according to claim 1 above, Its features are, The correlation between the first pressure value and the pressure-affecting variable (E) is detected in advance.

6. The method according to any one of claims 1 to 5, Its features are, The second operating state (B2) of the clutch (12) is identified based on the measured operating pressure by determining a second pressure range of the measured operating pressure that is limited by at least one preset second pressure value, and identifying the second operating state (B2) as existing as long as the measured operating pressure is within the second pressure range.

7. The method according to claim 6, Its features are, The second pressure value is set according to the pressure influence variable (E).

8. The method according to claim 6, Its features are, The second pressure value is less than the first pressure value, and the first pressure range does not overlap with the second pressure range.

9. A clutch (12) for transmitting torque between a drive element (14) and a driven device (20), having a clutch input end (26) rotatable about a rotation axis and a clutch output end (28) releasably connected to the clutch input end in a frictional engagement with an operating pressure provided via an operating device (52) for transmitting torque, wherein the operating state of the clutch (12) is identifiable by a method according to any one of the preceding claims.

Images