Control method for an unsynchronised variable-speed gearbox, control device and motor vehicle

Abstract

The invention relates to a control method for an unsynchronised variable-speed gearbox (3) of a motor vehicle (1), wherein - a shifting process is started in response to a shifting command in order to engage a target gear in the shifting process by mechanically connecting a first shifting element (15.1) to a second shifting element (15.2), wherein - it is checked whether a shifting error is present, wherein - if a shifting error is present, at least one parameter is adapted, wherein - the shifting process is concluded by engaging the target gear. The invention also relates to a control device (5) for carrying out such a method and to a motor vehicle (1) having such a control device (5).

Description

[0001] Control method for an unsynchronized gear-shifting transmission, control device and motor vehicle

[0002] The invention relates to a control method for an unsynchronized gear transmission of a motor vehicle, a control device for carrying out such a method and a motor vehicle with such a control device.

[0003] In such a control system, a switching operation is initiated upon a switching command. This operation involves mechanically connecting a first switching element, such as a gear, to a second switching element, such as a switching coupling element designed as a shift sleeve, thereby engaging a target gear. This is typically achieved by moving a switching actuator from an idle position to a switching position. During the actuator's movement, the system checks for switching errors, particularly a shift jam. If an error occurs, the switching operation is aborted, and the switching actuator returns to its idle position. The switching operation is then restarted once or several times, which can result in a comparatively long interruption of the powertrain.If the shifting error is due to a speed difference between the first rotational speed of the first shift element and the second rotational speed of the second shift element, which exceeds a certain engagement threshold – the maximum differential speed up to which engagement is possible – it is possible that the next shifting process will also be aborted due to the same error. Such a procedure is inefficient and can result in a gear change to the desired gear not being completed, forcing the selection of a different gear.

[0004] The invention is therefore based on the objective of providing a control method for an unsynchronized gear transmission of a motor vehicle, a control device for carrying out such a method, and a motor vehicle with such a control device, wherein the aforementioned disadvantages are reduced or preferably do not occur. This objective is achieved by providing the present technical teaching, in particular the teaching of the independent claims and the preferred embodiments disclosed in the dependent claims and the description.

[0005] The problem is solved, in particular, by creating a control method for an unsynchronized gear transmission of a motor vehicle, especially a commercial vehicle, particularly a truck. In the method, a shifting operation is initiated upon a shifting command in order to engage a target gear by mechanically connecting a first shifting element to a second shifting element. The system checks, particularly after the start of the shifting operation, whether a shifting error has occurred. If a shifting error has occurred, at least one parameter is adjusted, and the shifting operation is completed by engaging the target gear. Specifically, the target gear is engaged by means of a shifting actuator.

[0006] Advantageously, a shifting process no longer needs to be aborted due to a shifting error. Instead, the target gear can be engaged during the ongoing shift by adjusting parameters that correct, and in particular overcome, the shifting error. This eliminates the need for a subsequent shifting process. It also ensures that the gear change to the target gear can be completed. This can advantageously result in a comparatively shorter powertrain interruption.

[0007] In particular, a switching element, selected from the first switching element and the second switching element, is configured as a gear of the gear transmission, wherein another switching element, selected from the second switching element and the first switching element, is configured as a switching coupling element, in particular a shift sleeve, of the gear transmission. The switching coupling element is, in particular, arranged on a transmission shaft and is rotationally fixed relative to the transmission shaft along a circumferential direction. In particular, the switching coupling element is arranged to be displaceable on the transmission shaft along an insertion displacement direction that is oriented concentrically to a central axis of the transmission shaft.

[0008] The switching coupling element is displaced, in particular by means of the switching actuator, along the insertion displacement direction. According to a further development of the invention, it is provided that it is checked whether a switching malfunction exists between the first switching element and the second switching element.

[0009] In the context of this technical teaching, a switching jam is understood to mean, in particular, that the first switching element and the second switching element cannot be mechanically connected to each other. This can occur when the differential rotational speed between the first rotational speed of the first switching element and the second rotational speed of the second switching element exceeds a certain insertion threshold differential rotational speed—up to which insertion is possible. In this case, a first switching connection element of the first switching element and a second switching connection element of the second switching element repel each other, thus preventing a mechanical connection between the first and second switching elements. This is colloquially referred to as a "ratchet."Alternatively, this can also occur if a protrusion of the first switching connection element – ​​which would engage in a recess of the second switching connection element during a faultless insertion process – encounters a protrusion of the second switching connection element, particularly due to a faulty mutual alignment in the circumferential direction encompassing the insertion displacement direction. This can occur especially because, at the beginning of the switching process, it is not known how the first and second switching connection elements are aligned relative to each other in the circumferential direction, particularly whether they are rotated.

[0010] When a shift jam occurs during a shifting process, the advantages already mentioned are realized in a special way, since - without overcoming the shift jam - the shifting process cannot be completed and the target gear cannot be engaged.

[0011] According to a further development of the invention, it is provided that the parameter is an adjustment of the rotational speed of a drive of the motor vehicle.

[0012] Advantageously, the differential speed can be reduced until its absolute value is smaller than the insertion limit differential speed. After this reduction, the first switching connection element of the first switching element and the second switching connection element of the second switching element no longer repel each other, thus enabling a mechanical connection between the first and second switching elements.

[0013] In one embodiment, the parameter is an adjustment of the rotational speed, in particular the target rotational speed, of an electric drive of the motor vehicle.

[0014] Preferably, the speed, in particular the target speed, of the electric drive is reduced when a higher gear is engaged - i.e., when the gear ratio of the transmission is reduced - and increased when a lower gear is engaged - i.e., when the gear ratio of the transmission is increased.

[0015] However, it is also possible that the speed, in particular the target speed, of the electric drive is increased when a higher gear is engaged, especially if the speed of the electric drive has dropped so low that the differential speed exceeds the engagement limit differential speed.

[0016] It is also possible that the gear transmission has a clutch device designed to selectively open or close a mechanical connection between the gear transmission and the drive. In such a configuration, it is possible that—as a parameter adjustment—the shaft speed of an intermediate shaft, also known as a countershaft, of the gear transmission is reduced by means of a shaft brake.

[0017] According to a further development of the invention, upon receiving a shift command, a shift actuator of the gear transmission is moved from an idle position to an intermediate position. The system then checks whether a shifting error is present. If an error is present, the shift actuator remains in the intermediate position while at least one parameter is adjusted. After the parameter adjustment, the shift actuator is moved from the intermediate position to a switching position in which the first and second shifting elements are mechanically connected. Advantageously, a shifting process with a shifting error is converted into a shifting process without a shifting error with minimal effort. It is not necessary to move the shift actuator back to the idle position.Rather, the switching actuator can remain in the intermediate position until the parameter adjustment is complete, after which the switching process is completed by engaging the target gear. In the context of this technical teaching, an idle position is understood to be, in particular, a position of the switching actuator in which the first switching element and the second switching element are not connected to each other, in particular not mechanically connected, in particular not drive-related, and in particular not touching each other. The first switching element and the second switching element can rotate independently of each other in the circumferential direction. In the idle position, the gear comprising the first switching element and the second switching element is not engaged.

[0018] In the context of this technical teaching, an intermediate position is understood to be, in particular, a position of the switching actuator that—with respect to the insertion displacement direction—is located between the idle position and the switching position. The switching actuator has been displaced from the idle position but has not yet reached the switching position. In the intermediate position, contact can occur between the first switching element, in particular the first switching connection element, and the second switching element, in particular the second switching connection element, and thus mutual rejection, in particular the ratchet mechanism.

[0019] In the context of this technical teaching, a switching position is understood to be, in particular, a position of the switching actuator in which the first switching element and the second switching element are connected to each other, especially mechanically connected, and especially by means of a drive mechanism. The first switching element and the second switching element are coupled to each other circumferentially and cannot rotate independently of each other. In the switching position, the gear comprising the first switching element and the second switching element is engaged.

[0020] The switching coupling element is moved between the neutral position, the intermediate position, and the switching position, particularly by means of the switching actuator. Specifically, the switching coupling element mechanically connects the gear to the transmission shaft, especially in a rotationally fixed manner in the switching position.

[0021] According to a further development of the invention, the switching error is checked by evaluating a sensor signal from an accelerometer. According to a further development of the invention, the accelerometer used is an accelerometer configured to detect longitudinal acceleration of the motor vehicle.

[0022] Preferably, the acceleration sensor is a different sensor from a driver assistance system sensor used in an electronic driver assistance system of the motor vehicle. In particular, the acceleration sensor used to detect the shifting error is not used for an electronic driver assistance system of the motor vehicle.

[0023] In one embodiment, the gear transmission is arranged in the vehicle such that the transmission shafts, on which the first or second shifting element is displaced along the insertion displacement direction, are oriented in a longitudinal direction of the vehicle. When the first and second shifting elements repel each other, a vibration is generated in the gear transmission, the amplitude of which is oriented in the longitudinal direction of the vehicle. This vibration can be detected by the acceleration sensor, which is preferably configured to detect longitudinal acceleration. Since vehicles typically already have such an acceleration sensor for detecting road inclination, an additional sensor is advantageously unnecessary.

[0024] According to a further development of the invention, it is provided that an acceleration sensor of a control device of the gear-shifting transmission is used as the acceleration sensor.

[0025] In an alternative embodiment, the acceleration sensor is arranged on the gear transmission.

[0026] In one embodiment, where the vehicle has an electric drive, the acceleration sensor is preferably arranged on the gear transmission. In another embodiment, where the vehicle has an internal combustion engine as its drive, the acceleration sensor is preferably arranged on the vehicle's control unit.

[0027] According to a further development of the invention, it is provided that after the parameter adjustment of at least one parameter, a parameter settling time of the parameter adjustment is waited for before the switching process is completed, in particular before the target gear is engaged, in particular before the switching actuator is moved from the intermediate position to the switching position.

[0028] Advantageously, a control delay – in particular a delay in controlling and reporting the rotational speed – of the preferably electric drive is taken into account. This ensures that the differential rotational speed is reduced before the switching process is completed, in particular before the target gear is engaged, and in particular before the switching actuator is moved from the intermediate position to the switching position. The control delay is in particular in the range of 30 ms to 70 ms, in particular from 40 ms to 60 ms, and in particular at 50 ms.

[0029] According to a further development of the invention, the switching error is checked by comparing a first rotational speed of the first switching element and a second rotational speed of the second switching element. The switching error occurs when the difference in rotational speed between the first and second rotational speeds exceeds a predetermined differential speed threshold.

[0030] In particular, the predetermined differential speed threshold is smaller in absolute value than the engagement differential speed limit. This ensures that the shifting process can be completed if the differential speed is smaller in absolute value than the differential speed threshold.

[0031] Alternatively or additionally, switching errors are checked by monitoring the switching path of the switching actuator. A switching error occurs when the switching path deviates from a predetermined switching path characteristic. In particular, the switching path is oriented parallel to the insertion displacement direction.

[0032] In particular, the vibration generated in the gear-shifting transmission – transmitted via the first or second switching element, depending on which element is designed as the switching coupling element – ​​acts on the switching actuator and displaces it periodically along the insertion displacement direction, generating a shift path oscillation. The periodic displacement of the switching actuator and the resulting maxima and minima of the shift path oscillation can be detected. The amplitude and the distances between two adjacent extreme points of the shift path oscillation can be used to determine the switching error. Alternatively or additionally, the switching error is checked by monitoring a predetermined maximum switching time of the switching process. The switching error occurs when the predetermined maximum half-time is exceeded.

[0033] In one embodiment, the first speed can be derived from the drive speed, particularly that of an electric drive, and the second speed can be derived from the output speed, particularly at a transmission output shaft. In another embodiment, the first speed and / or the second speed can also be detected by means of a speed sensor, which is preferably arranged in the gear transmission, particularly directly on the respective transmission shaft. In particular, the first speed can also be derived and the second speed detected, or vice versa.

[0034] The problem is also solved by providing a control device for a gear-shifting transmission, which is configured to carry out a control method according to the invention or a control method according to one or more of the embodiments described above. The advantages of the control device are particularly evident in the advantages already explained in connection with the control method.

[0035] The problem is also solved by creating a motor vehicle, in particular a commercial vehicle, especially a truck, with a gear transmission, a preferably electric drive, and a control device according to the invention or a control device according to one or more of the embodiments described above. The preferably electric drive is configured to propel the motor vehicle, in particular to move it. The drive is operatively connected to a transmission input shaft of the gear transmission. The control device is operatively connected to the gear transmission and is configured to mechanically connect, preferably by means of a switching actuator, a first switching element and a second switching element of the gear transmission. In connection with the motor vehicle, the advantages that have already been explained in connection with the control method and the control device arise in particular.

[0036] According to a further development of the invention, the control device is additionally configured to request an adjustment of the rotational speed, in particular the target rotational speed, of the preferably electric drive at the drive control device. The invention is explained in more detail below with reference to the drawing. The drawing shows:

[0037] Fig. 1 shows a schematic representation of an embodiment of a motor vehicle with a gear-shifting transmission and a control device, and

[0038] Fig. 2 shows a process flow diagram of a control method for operating a gear-changing transmission according to Fig. 1.

[0039] Figure 1 shows a schematic representation of an embodiment of a motor vehicle 1 with a gear transmission 3 and a control device 5.

[0040] The motor vehicle 1 further comprises a preferably electric drive 7, an acceleration sensor 8, and a drive control device 9. The preferably electric drive 7 is configured to propel the motor vehicle 1, in particular to move it. The drive 7 is operatively connected to a transmission input shaft 11.1 of the gear transmission 3. The control device 5 is operatively connected to the gear transmission 3 and is configured to mechanically connect a first switching element 15.1, here a gear, and a second switching element 15.2, here a switching coupling element, of the gear transmission 3 by means of a switching actuator 13, and to request an adjustment of a speed, in particular a target speed, of the preferably electric drive 7 from the drive control device 9. The second switching element 15.2 can be displaced by means of the switching actuator 13 along an insertion displacement direction 6, indicated by an arrow.In a switching position, the second switching element 15.2 mechanically connects the first switching element 15.1, in particular in a rotationally fixed manner, to a transmission output shaft 11.2.

[0041] The control device 5 is further configured to carry out a procedure described in more detail in Figure 2.

[0042] Figure 2 shows a process flow diagram of a method for operating a gear-changing transmission 3 according to Fig. 1.

[0043] Identical and functionally equivalent elements in all figures are designated with the same reference numerals, so that reference is made to the preceding description in each case. In a first step S1 of the method, a switching operation is initiated upon a switching command in order to engage a target gear by mechanically connecting the first switching element 15.1 with the second switching element 15.2. Upon the switching command, the switching actuator 13 of the gear-shifting transmission 3 is moved from an idle position to an intermediate position.

[0044] In a second step S2, particularly after the start of the switching process, it is checked whether a switching error exists, whereby in this embodiment it is checked whether the switching error is a switching jam between the first switching element 15.1 and the second switching element 15.2.

[0045] The switching error is checked by evaluating a sensor signal from the acceleration sensor 8. The acceleration sensor 8 is configured to detect longitudinal acceleration of the vehicle 1. The acceleration sensor 8 is located on the gear transmission 3.

[0046] In an embodiment not shown, the acceleration sensor 8 is an acceleration sensor 8 of the control device 5 of the gear-shifting transmission 3.

[0047] In an embodiment not shown, the switching error is checked by comparing a first rotational speed of the first switching element 15.1 and a second rotational speed of the second switching element 15.2. The switching error occurs if the difference in rotational speed between the first and second speeds exceeds a predetermined differential speed threshold. In this case, the first and second rotational speeds can be detected by means of speed sensors 10, specifically a first speed sensor 10.1 for detecting the first speed and a second speed sensor 10.2 for detecting the second speed. These sensors are preferably arranged in the gear transmission 3, particularly directly on the respective transmission shaft, selected from the transmission input shaft 11.1, the transmission output shaft 11.2, and an intermediate transmission shaft 11.3.

[0048] If a switching error occurs, the switching actuator 13 remains in the intermediate position, and in a third step S3 at least one parameter is adjusted. Preferably, the parameter is the rotational speed of the drive 7 of the motor vehicle 1. Alternatively or additionally—particularly if the gear transmission 3 has a clutch device not shown here—the parameter adjustment is the reduction of the shaft speed of the intermediate transmission shaft 11.3, preferably by means of a shaft brake not shown here.

[0049] In a fourth step S4, the switching process is completed by engaging the target gear using the switching actuator 13. Preferably, after parameter adjustment, the switching actuator 13 is moved from the intermediate position to a switching position in which the first switching element 15.1 and the second switching element 15.2 are mechanically connected.

[0050] Preferably, after the parameter adjustment of at least one parameter, a parameter settling time of the parameter adjustment is waited for before the switching process is completed, in particular before the target gear is engaged, in particular before the switching actuator 13 is moved from the intermediate position to the switching position.

[0051] Reference symbol list

[0052] I. Motor vehicle. Gearbox. Control device. Insertion displacement direction.

[0053] 7. Drive

[0054] 8. Accelerometer

[0055] 9. Drive control device

[0056] 10. Speed ​​sensor

[0057] 10.2 First speed sensor

[0058] 10.2 Second speed sensor

[0059] I I.1 Gearbox input shaft

[0060] 11.2 Transmission output shaft

[0061] 11.3 Intermediate shaft

[0062] 13. Switching actuator

[0063] 15.1 first switching element

[0064] 15.2 second switching element

Claims

Patent claims 1. Control method for an unsynchronized gear transmission (3) of a motor vehicle (1), wherein - a switching operation is started in response to a switching command in order to engage a target gear in the switching operation by mechanically connecting a first switching element (15.1) with a second switching element (15.2), wherein - it is checked whether a switching error is present, whereby - if a switching error occurs, at least one parameter is adjusted, whereby - the shifting process is completed by engaging the target gear.

2. Control method according to claim 1, wherein - it is checked whether the switching fault is a switching interference between the first switching element (15.1) and the second switching element (15.2).

3. Control method according to one of the preceding claims, wherein - when the parameter is adjusted to a rotational speed of a drive (7) of the motor vehicle (1).

4. Control method according to one of the preceding claims, wherein - upon receiving the switching command, a switching actuator (13) of the gear-changing transmission (3) is moved from an idle position to an intermediate position, whereby - then it is checked whether the switching error is present, whereby - if the switching fault occurs, the switching actuator (13) remains in the intermediate position while at least one parameter is adjusted, whereby - after parameter adjustment, the switching actuator (13) is moved from the intermediate position to a switching position in which the first switching element (15.1) and the second switching element (15.2) are mechanically connected.

5. Control method according to one of the preceding claims, wherein - is checked for switching errors by evaluating a sensor signal from an acceleration sensor (8).

6. Control method according to claim 5, wherein - when the acceleration sensor (8) is used, an acceleration sensor (8) is configured to detect longitudinal acceleration of the motor vehicle (1).

7. Control method according to claim 5 or 6, wherein - when the acceleration sensor (8) is used as an acceleration sensor (8) of a control device (5) of the gear shifting transmission (3).

8. Control method according to one of the preceding claims, wherein - after the parameter adjustment of at least one parameter, a parameter settling time of the parameter adjustment is waited for before the switching process is completed.

9. Control method according to one of the preceding claims, wherein the switching error is checked. - by comparing a first rotational speed of the first switching element (15.1) and a second rotational speed of the second switching element (15.2), wherein the switching error occurs when a differential rotational speed between the first rotational speed and the second rotational speed exceeds a predetermined differential rotational speed threshold, and / or - by monitoring a switching path of the switching actuator (13), wherein the switching error occurs when the switching path deviates from a predetermined switching path characteristic, and / or - by monitoring a predetermined maximum switching time of the switching process, whereby the switching error occurs when the predetermined maximum switching time is exceeded.

10. Control device (5) for a gear-changing transmission (3), wherein the control device (5) is set up to carry out a control procedure according to one of the preceding claims.

11. Motor vehicle (1), comprising: - a gear-changing transmission (3); - a drive (7) which is configured to drive the motor vehicle (1), wherein the drive (7) is drivenly connected to a transmission input shaft (11.1) of the gear transmission (3), and - a control device (5) according to claim 10, wherein - the control device (5) is operatively connected to the gear transmission (3) and is configured to mechanically connect a first switching element (15.1) and a second switching element (15.1) of the gear transmission (3).

12. Motor vehicle (1) according to claim 11 , wherein - the control device (5) is additionally equipped to request an adjustment of the speed of the drive (7) at the drive control device (9).

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