Method for determining the synchronization point of a coupling process of a dog clutch

Abstract

The invention relates to a method for determining the synchronization point P_Sact during a coupling process of a dog clutch (1). An electric machine (2) can be drivingly connected to a component to be driven via the dog clutch (1), and the dog clutch (1) has at least one first clutch element (1a) and an axially movable second clutch element (1b). The rotational speed of the electric machine (2) is controlled and thus a specified differential rotational speed is set between the two clutch elements (1a), (1b). The axial movement of the second clutch element (1b) of the dog clutch (1) is divided into at least two movement phases V1, V2, namely a first movement phase V1 and a second movement phase V2, wherein a first criterion is generated by determining the average torque M1_av and a maximum torque M1_max of the electric machine (2) during the first movement phase V1 and by comparing the torque values M1_av, M1_max determined during the first movement phase V1 with a torque M2 determined in the second movement phase V2 in order to detect a previous synchronization point P_Spre, and a second criterion is generated in order to set the previous synchronization point P_Spre as the actual synchronization point P_Sact.

Description

[0001] Method for determining a synchronization point of a coupling process of a claw clutch

[0002] Field of the invention

[0003] The present invention relates to a method for determining a synchronization point during a coupling process of a claw clutch, wherein an electric machine can be drive-effectively connected to a component to be driven via the claw clutch, wherein the claw clutch has at least a first clutch element and an axially movable second clutch element and wherein the electric machine is speed-controlled and thus a predetermined differential speed is set between the two clutch elements.

[0004] Furthermore, the present invention relates to the use of a method according to the invention in an electric or hybrid motor vehicle.

[0005] State of the art

[0006] In electric and hybrid vehicles, so-called claw clutches are often used to transmit rotary motion or torque from an electric motor via a transmission to a driven vehicle axle. The claw clutch has two clutch elements, with a first clutch element being connected, for example, to the electric motor and the second clutch element being connected to the driven axle of the vehicle. In order to close the claw clutch with low wear and noise when the vehicle is in motion, the speed of the two claw elements must be synchronized. In electric and hybrid vehicles, this is usually done actively via the electric motor by setting a defined speed difference between the clutch elements of the claw clutch.In order to engage the claw clutch, the electric machine is controlled by a control unit in such a way that a nearly constant differential speed band results between the electric machine and the axle of the motor vehicle to be driven.

[0007] A "synchronization point" of a dog clutch is the point in time during a coupling or closing process at which initial contact occurs in the form of a frictional or positive engagement between the two coupling elements of the dog clutch. In relation to the above-described application of the dog clutch in an electric or hybrid vehicle, the synchronization point thus represents the point in time at which the driving electric motor and the driven axle of the vehicle are effectively connected.

[0008] Precise knowledge of the synchronization point of the clutch elements of the dog clutch results in several advantages that have a positive effect on shifting comfort, shifting time and NVH (Noise Vibration Harshness) behavior during the shifting process of the dog clutch.

[0009] Summary of the invention

[0010] It is an object of the invention to provide a method for the simple and precise determination of a synchronization point during a coupling process of a claw clutch, via which a drive-effective connection can be established between an electrical machine and a driven component. Furthermore, it is an object of the present invention to provide an advantageous use of the method according to the invention.

[0011] This need can be met by the subject matter of the present invention according to independent claims 1 and 3. Advantageous embodiments of the present invention are described in the dependent claims.

[0012] The method according to the invention serves to determine a synchronization point during a coupling process of a claw clutch, wherein an electric machine can be connected in a drive-effective manner to a component to be driven via the claw clutch.

[0013] According to the invention, the claw clutch has at least a first clutch element and an axially movable second clutch element.

[0014] According to the present invention, the electric machine is speed-controlled - in this way, a predetermined differential speed is set between the two clutch elements.

[0015] According to the invention, the axial movement of the second coupling element of the claw coupling is divided into at least two adjustment phases, namely a first adjustment phase and a second adjustment phase.

[0016] According to the present invention, a first criterion is generated to determine a provisional synchronization point and a second criterion is generated to define the provisional synchronization point as the actual synchronization point by determining an average and maximum torque of the electric machine during the first adjustment phase and by comparing the torque values ​​determined in the first adjustment phase with a torque detected in the second adjustment phase.

[0017] The method according to the invention preferably comprises at least the following steps when a coupling request is made for the claw clutch:

[0018] Setting the predetermined differential speed between the two coupling elements of the claw clutch via the electric machine,

[0019] Calculation of the average torque of the electric machine in the first adjustment phase of the second clutch element of the claw clutch,

[0020] Determination of the maximum torque of the electric machine in the first adjustment phase of the claw clutch, intermediate storage of the calculated average torque and the determined maximum torque of the electric machine in the first adjustment phase of the claw clutch, recording the torque of the electric machine during the second adjustment phase of the claw clutch and simultaneous comparison of the recorded torque with the maximum torque determined in the first adjustment phase,

[0021] Intermediate storage of the time and position of the second clutch element when the maximum torque determined in the first adjustment phase is exceeded for the first time in the second adjustment phase as a preliminary synchronization point,

[0022] Calculating the average torque in the second adjustment phase from the recorded preliminary synchronization point, comparing the average torque calculated in the second adjustment phase, from the recorded preliminary synchronization point, with the average torque calculated and temporarily stored in the first adjustment phase, storing the preliminary synchronization point as the actual synchronization point if the average torque calculated in the second adjustment phase, from the recorded preliminary synchronization point, is higher by a defined amount than the average torque calculated in the first adjustment phase.

[0023] According to the present invention, the method according to the invention is used in an electric or hybrid motor vehicle.

[0024] By means of the method according to the invention for determining a synchronization point during a coupling process of a dog clutch that is drivingly connected to an electric machine, not only can the switching time of the dog clutch be reduced, but also improved NHV and vibration behavior can be achieved. Furthermore, precise knowledge of the dog clutch's synchronization point can reduce wear on the clutch elements.

[0025] By applying the method according to the invention in an electric or hybrid motor vehicle, in particular in the area of ​​an electric axle arrangement, driver safety can also be increased.

[0026] Brief description of the drawings

[0027] The invention is described below by way of example with reference to the drawings. Figure 1 shows a schematic detailed illustration of a motor vehicle drive with an electric motor and a transmission with a decoupled claw clutch.

[0028] Fig. 2 shows diagrams of parameters for determining the synchronization point of a dog clutch in a structure according to Fig. 1.

[0029] Detailed description of the invention

[0030] Fig. 1 schematically illustrates a detail of a motor vehicle drive, namely a gear transmission 3 and an electric motor 2, by way of example. The method according to the invention is described using the topology shown in Fig. 1, but can also be used with other transmission topologies, such as a planetary transmission.

[0031] The electric machine 2 is drive-connected to an input shaft 4 of the gear transmission 3. Furthermore, the electric machine 2 is connected to an inverter 9 for powering the electric machine 2. The inverter 9 has a control unit 10. The control unit 10 is responsible for sending a target speed value to the inverter 9. The inverter 9 then automatically regulates the electric machine 2 to the required speed.

[0032] The gear transmission 3 can have several gear stages, of which only one gear stage 5, which has a fixed gear 5a and an idler gear 5b, is shown in Fig. 1. Both the fixed gear 5a and the idler gear 5b are designed as spur gears. The fixed gear 5a is arranged on the input shaft 4 of the gear transmission 3. The idler gear 5b is arranged on an output shaft 6 of the gear transmission 3. Furthermore, an output gear 7 is arranged on the output shaft 6 of the gear transmission, which is drivingly connected to an axle of the motor vehicle (not shown), more precisely to a differential gear (not shown) arranged on the axle.

[0033] The idler gear 5b can be coupled in a rotationally fixed manner to the output shaft 6 of the gear transmission 3 by means of a claw coupling 1.

[0034] The claw clutch 1 comprises a first clutch element 1a, namely a claw element, and an axially movable second clutch element 1b, namely a sliding sleeve. The claw element, as the first clutch element 1a, is also designated by the reference symbol "1a." The sliding sleeve, as the second clutch element 1b, is also designated by the reference symbol "1b."

[0035] The claw element 1a is connected to the idler gear 5b in a rotationally fixed and axially fixed manner. The sliding sleeve 1b is translationally displaceable in the direction of the claw element 1a and is connected to the output shaft 6 of the gear transmission 3 in a rotationally fixed manner.

[0036] By engaging the sliding sleeve 1b in the claw element 1a, the idler gear 5b can therefore be connected in a rotationally fixed manner to the output shaft 6 of the gear transmission 3 in order to enable power transmission from the electric machine 2 via the gear stage 5 to the output shaft 6 of the gear transmission 3, wherein the fixed gear 5a is held in a rotationally fixed manner on the input shaft 4 of the gear transmission 3.

[0037] In order to transfer the sliding sleeve 1b from the uncoupled position shown in Fig. 1 into a coupled position, i.e., to perform a coupling process, the sliding sleeve 1b is drive-connected to an actuator unit 8. The actuator unit 8 comprises a shift drum (not shown in detail).

[0038] By rotating the shift drum of the actuator unit 8, the sliding sleeve 1b can be displaced toward the claw element 1a to couple the sliding sleeve 1b to the claw element 1a (coupling process). Likewise, the sliding sleeve 1b can be decoupled from the claw element 1a by rotating the shift drum of the actuator unit 8 (decoupling process).

[0039] For this purpose, the sliding sleeve 1b has a guide element which is guided in a shift gate of the shift drum in order to convert a rotation of the shift drum into a translational displacement of the guide element together with the sliding sleeve 1b (not shown).

[0040] The method according to the invention for determining a synchronization point P_Sact of the dog clutch 1 is described below with reference to Fig. 2.

[0041] Diagram I of Fig. 2 shows the position P of the shift drum of the actuator unit 8 in degrees [°], related to a rotation of the shift drum about its own axis, plotted against time t in seconds [s].

[0042] Diagram II in Fig. 2 shows the torque curve M of the electric machine 2 during speed control of the electric machine 2 in Newton meters [Nm] plotted against time t in seconds [s].

[0043] The coupling process between the sliding sleeve 1b of the claw clutch 1 and the claw element 1a of the claw clutch 1 begins at a starting time t_0 and is completed at the end time t_end. The diagrams according to Fig. 2 therefore describe the manner in which the sliding sleeve 1b is moved, starting from a starting position P_0 at time t_0, i.e., a decoupled state of the claw clutch 1, until it reaches an end position P_end at time t_end, i.e., the coupled state of the claw clutch 1.

[0044] A first adjustment phase V1 begins at time t_1 and ends at time t_2.

[0045] During the first adjustment phase V1 of the sliding sleeve 1b, no contact between the sliding sleeve 1b and the claw element 1a is to be expected. The first adjustment phase V1 can also be referred to as the "implausible synchronization range" of the sliding sleeve 1b.

[0046] During the first adjustment phase V1, a speed difference is specified between the idler gear 5b and the output shaft 6 to be synchronized, on which the idler gear 5b is arranged, wherein the idler gear 5b is coupled to the electric motor 2 via the fixed gear 5a arranged on the input shaft 4 in order to set a speed of the idler gear 5b. Specifying the speed difference between the idler gear 5b and the output shaft 6 to be synchronized equally means specifying a speed difference between the sliding sleeve 1b of the claw clutch 1, which is rotationally fixedly coupled to the output shaft 6, and the claw element 1a, which is rotationally fixedly held on the idler gear 5b.

[0047] During the first adjustment phase V1, the sliding sleeve 1b is moved from the starting position P_0 to a first position P_1. The first position P_1 is a defined intermediate position of the sliding sleeve 1b before contact with the claw element 1a of the idler gear 5a.

[0048] The displacement of the sliding sleeve 1b of the claw clutch 1 in the direction of the claw element 1a of the idler gear 5b from the starting position P_0 to the first position P_1 is effected by means of the controlled shift drum of the actuation unit 8.

[0049] During the first adjustment phase V1, the torque is recorded during the first adjustment phase M1. Furthermore, during the first adjustment phase V1, an average torque M1_av is calculated and the maximum torque M1_max is determined during the first adjustment phase V1. If the first adjustment phase V1 is successfully completed without a termination criterion, such as if the desired differential speed between the sliding sleeve 1b and the claw element 1a is not set, the calculated values ​​for the average torque M1_av and the determined value for the maximum torque M1_max during the first adjustment phase V1 are temporarily stored in the memory unit of the control unit 10.

[0050] The first adjustment phase V1 is followed by a second adjustment phase V2. The second adjustment phase V2 begins at time t_2 and ends at time t_3.

[0051] During the second adjustment phase V2, contact between the sliding sleeve 1b and the claw element 1a is to be expected. The second adjustment phase V2 can also be referred to as the "plausible synchronization range" of the sliding sleeve 1b.

[0052] During the second adjustment phase V2, the sliding sleeve is moved from the first position P_1 to a second position P_2. The second position P_2 is a further intermediate position of the sliding sleeve 1b after the sliding sleeve 1b has been coupled into the claw element 1a of the idler gear 5b.

[0053] The sliding sleeve 1b of the claw clutch 1 is moved in the direction of the claw element 1a of the idler gear 5b from the first position P1 to the second position P2 by means of the controlled shift drum of the actuation unit 8.

[0054] During the second adjustment phase V2, the torque is recorded during the second adjustment phase M2 and at the same time the recorded torque M2 is compared with the maximum torque M1_max recorded in the first adjustment phase V1.

[0055] As soon as the detected torque exceeds the maximum torque M1_max from the first adjustment phase V1 once during the second adjustment phase V2, the position P_s of the sliding sleeve 1b at this time t_s is used as the provisional synchronization point P_s pretemporarily stored. The average torque M2_av is then calculated from time t_s until the end of the second adjustment phase V2, i.e., until time t_3. If the calculated average torque M2_av in the period from time t_s to time t_3 is higher by a certain amount than the average torque M1_av calculated in the first adjustment range V1, the previously stored position P_s at time t_s is stored as the actual synchronization point P_Sact.

[0056] Following the second adjustment phase V2, the sliding sleeve 1 b fully engages the claw element 1a in the period t_3 to t_end.

[0057] List of reference symbols

[0058] 1 claw coupling

[0059] 1a First coupling element (claw element)

[0060] 1 b Second coupling element (sliding sleeve)

[0061] 2 Electric machine

[0062] 3 gear transmissions

[0063] 4 Input shaft

[0064] 5 gear stage

[0065] 5a Fixed gear

[0066] 5b idler gear

[0067] 6 Input shaft

[0068] 7 Output gear

[0069] 8 Actuation unit

[0070] 9 inverters

[0071] 10 Control unit

[0072] V1 First adjustment phase

[0073] V2 Second adjustment phase

[0074] M1_av Average torque during the first adjustment phase

[0075] M2_av Average torque during the second adjustment phase

[0076] M1_max Maximum torque during the first adjustment phase

[0077] M1 Torque during the first adjustment phase

[0078] M2 Torque during the second adjustment phase

[0079] P_s pre Preliminary synchronization point

[0080] P_Sact Actual synchronization point t Time t_s Time of the synchronization point t_0 Start time t_end End time t_1 , t_2, t_3 (Intermediate) times

[0081] P Position (of the sliding sleeve)

[0082] P_s Position of the synchronization point

[0083] P_0 starting position

[0084] P_end End position

[0085] P_1 First Position

[0086] P_2 Second Position

Claims

Patent claims 1 . Method for determining a synchronization point P_s act during a coupling process of a claw clutch 1, wherein an electric machine 2 as a driving component can be drive-effectively connected to a component to be driven via the claw clutch 1, wherein the claw clutch 1 has at least a first clutch element 1a and an axially movable second clutch element 1b, wherein the electric machine 2 is speed-controlled and thus a predetermined differential speed between the two clutch elements 1a, 1b is set and wherein the axial movement of the second clutch element 1b of the claw clutch 1 is divided into at least two adjustment phases V1, V2, namely a first adjustment phase V1 and a second adjustment phase V2, wherein by determining an average torque M1_av and a maximum torque M1_max of the electric machine 2 during the first adjustment phase V1 and by comparing the torque values ​​M1_av determined in the first adjustment phase V1,M1_max with a torque M2 determined in the second adjustment phase V2, a first criterion is generated to determine a preliminary synchronization point P_s, P re and a second criterion is generated to determine the preliminary synchronization point P_s pre to set the actual synchronization point P_Sact. Method according to claim 1, characterized in that the method comprises at least the following steps when a coupling request is made to the claw clutch 1: Setting the predetermined differential speed between the two clutch elements 1a, 1b of the claw clutch 1 via the electric machine 2, Calculating the average torque M1_av of the electric machine 2 in the first adjustment phase V1 of the second clutch element 1b of the claw clutch 1, determining the maximum torque M1_max of the electric machine 2 in the first adjustment phase V1 of the second clutch element 1b of the claw clutch 1, temporarily storing the calculated average torque M1_av and the determined maximum torque M1_max of the electric machine 2 in the first adjustment phase V1 of the second claw element 1b of the claw clutch 1, detecting the torque M2 of the electric machine 2 during the second adjustment phase V2 of the second clutch element 1b of the claw clutch 1 and simultaneously comparing the detected torque with the maximum torque M1_max determined in the first adjustment phase V1, Intermediate storage of the time t_s and the position P_s of the second clutch element 1 b when the maximum torque M1_max determined in the first adjustment phase V1 is exceeded for the first time in the second adjustment phase V2 as a preliminary synchronization point P_Spre, calculation of the average torque M2_av in the second adjustment phase V2 from the recorded preliminary synchronization ization point P_s pr e, Comparison of the second adjustment phase V2, from the recorded preliminary synchronization point P_s pre , calculated average torque M2_av with the average torque M1_av calculated and temporarily stored in the first adjustment phase V1, Storing the preliminary synchronization point P_s pre as the actual synchronization point P_s ac t, if the value recorded in the second adjustment phase V2, from the preliminary synchronization point P_s Pre, calculated average torque M2_av is higher than the average torque M1 av calculated in the first adjustment phase V1.

3. Use of a method according to claim 1 or 2 in an electric or hybrid motor vehicle.

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