Shift device for a motor vehicle transmission and method for operating such a shift device

Abstract

The invention relates to a shift device (10) for a motor vehicle transmission, having unsynchronized shift dogs (14) which have two shift parts which are rotatable relative to one another about a rotational axis (22), which have corresponding shift toothing and can be moved relative to one another along the rotational axis (22) between at least one engagement position and at least one disengagement position, wherein in the engagement position the shift toothing is in engagement with one another such that the shift parts are connected to one another in a rotationally fixed manner, and in the disengagement position the shift toothing is disengaged from one another such that the shift parts are rotatable relative to one another about the rotational axis (22). Detection means (36) are provided by means of which a rotational position in which at least one of the shift parts can be rotated relative to the other shift part about the rotational axis (22) can be measured. Electronic computing means (38) are provided which are designed to move the shift parts from the disengagement position to the engagement position in dependence on the measured rotational position. The invention also relates to a method for operating such a shift device.

Description

TECHNICAL FIELD

[0001] The invention relates to a shift device for a transmission of a motor vehicle, in particular a passenger car. The invention also relates to a method for operating such a shift device. BACKGROUND

[0002] Such a shift device for a transmission of a motor vehicle has been disclosed, for example, by DE 10 2010 043 592 A1. The shift device has at least one unsynchronized shift dog, i.e. an unsynchronized positive shift element, which comprises two shift parts which can be rotated relative to each other about a rotational axis. The shift parts each have a shift toothing. These shift toothings are, for example, directed towards each other along the rotational axis. The shift parts can be moved relative to each other along the rotational axis between at least one engagement position and at least one disengagement position. In the engagement position, the shift toothings engage into each other, so that in the engagement position the shift toothings positively cooperate. As a result, the shift parts are connected to each other in a rotationally fixed manner. In the disengagement position, the shift toothings are disengaged from each other. This means that the shift toothings are not engaged and thus not cooperating in the disengagement position, so that in the disengagement position the shift parts can be rotated relative to each other about the rotational axis. SUMMARY

[0003] It is an object of the invention to improve a shift device of the type mentioned at the outset and to provide a method for operating a shift device, so that a very advantageous shifting can be achieved.

[0004] This object is achieved by a shift device having the features described below and by a method having the features described below.

[0005] In order to improve a shift device of the type described in the background section in such a way that a particularly advantageous switching of the shift dog, also referred to as shift element, from the disengaged position to the engaged position can be achieved, the application provides a detection device, in particular of an electrical or electronic type, by means of which the rotational position can be detected, at least one shift part being rotatable about a rotational axis relative to the other shift part, in particular in the disengaged position, into the rotational position. In other words, in the disengaged position, one shift part can be rotated about the rotational axis relative to the other shift part and thereby moved into the rotational position, so that it is in the rotational position relative to the other shift part. It is conceivable here that the other shift part is fixed against rotation on the transmission housing, in particular permanently, both in the disengaged position and in the engaged position, so that the other shift part cannot be rotated about the rotational axis relative to the housing. This means, in particular, that in the engaged position, one shift part is fixed against rotation on the housing by means of the other shift part. In the disengaged position, one shift part can be rotated about the rotational axis relative to the other shift part and relative to the housing. In the disengaged position, this one shift part can thus be rotated about the rotational axis relative to the housing and relative to the other shift part and thereby moved into the rotational position. In particular by detecting the rotational position, the rotational position of one shift part can be determined or associated with the other shift part and / or the housing, so that depending on the respective detected rotational position, the respective, also referred to as relative, position or orientation of one shift part relative to the other shift part can be determined or detected. In particular, the respective rotational position can also be determined or detected as the respective position of one shift part relative to the other shift part, so that for example by detecting the respective rotational position, the respective position or orientation of one shift part relative to the other shift part is known. In particular, the detection device is designed to measure the rotational speed with which this one shift part is rotated about the rotational axis relative to the other shift part, in particular in the disengaged position. It is thus conceivable that the detection device is a rotational speed detection system, by means of which the rotational speed and thus the rotational position of one shift part can be captured, i.e. measured.

[0006] Furthermore, the application provides that the shift device has an electronic computing device, also referred to as electronic control device, which is designed to move the shift part from the disengaged position into the engaged position depending on the detected rotational position. By means of this, the shift dog, also referred to as form-fit shift element, can be switched without a so-called tooth tip tooth position occurring. In other words, the shift part can be moved from the disengaged position into the engaged position without a so-called tooth tip tooth position occurring. The application is based here, in particular, on the recognition that generally, the shift dog is synchronized by means of a pre-synchronization mechanism, in particular designed as a frictional synchronization mechanism, in order to reduce or eliminate the rotational speed difference between the shift parts of the shift dog, after which the shift toothings can be brought into engagement. Here, in particular due to the tooth tip tooth position, more severe wear and perhaps also rattling, i.e. undesirable noise, and thus a reduction in comfort can occur.

[0007] The application now allows, in one aspect, the use of a non-synchronized shift dog, i.e. at least the abandonment of the frictional engagement synchronization of the shift dog. In another aspect, the application allows the avoidance of the tooth-on-tooth position, in particular when the shift portion is moved from the disengaged position to the engaged position, by detecting the rotational position, also referred to as rotational angle position, and moving the shift portion from the disengaged position to the engaged position depending on the detected rotational angle position. Due to the consideration of the rotational position, the electronic computing device can move the shift portion, or move it from the disengaged position to the engaged position, in such a way that the tooth-on-tooth position, and thus more severe wear and undesired noise, does not occur. The movement of the shift portion from the disengaged position to the engaged position is also referred to as engagement of the shift portion, which is also referred to simply as dog or shift dog. It is possible, in particular, to purposefully adjust the engagement of the dog depending on the detected rotational position (rotational angle position). In particular in combination with a sufficiently accurate torque sensor or rotational speed sensor for detecting the rotational position, such as an electric motor, and a suitable dog shape, for example like a hook tooth and a ratchet tooth design, it is possible to purposefully control the ratchet tooth or the first shift portion and / or the second shift portion therein, in order to avoid the tooth-on-tooth position and the resulting undesired phenomena such as rattling, reduced comfort or undesired noise when the dog is engaged.

[0008] The non-synchronized shift dog is cost- and installation space-advantageous and technically simple, since in particular a frictional pre-synchronization mechanism can be dispensed with. In particular in a transmission for an electrically powered drive device with an electric machine as a drive machine, wherein for example the first shift portion or the second shift portion, in particular one shift portion, is connected in particular rotationally fixedly to the electric machine, in particular to the electric machine rotor, the dog engagement, also referred to as engagement process, can be adjusted by means of the electric machine. In comparison to an internal combustion engine, the electric machine can be adjusted quickly and well and also adjusted to zero rotational speed quickly and well, so that a synchronization of the dog can be dispensed with. As a result, the engagement can be carried out with high shift comfort.

[0009] The motor vehicle can be purely electrically driven, in particular, so that the transmission is preferably a transmission of an electrically driven vehicle, in particular a purely electrically driven vehicle. The shift portions are also referred to as shift element halves, for example. The respective shift tooth row has a plurality of teeth, also referred to as dog teeth. It is conceivable here that the respective tooth end of the dog teeth of the respective shift portion points in the axial direction, i.e. along the rotational axis, to the respective other, opposite shift portion, so that the shift portions are preferably arranged next to each other or one after the other in the axial direction, i.e. along the rotational axis. Thus, the shift tooth row of one shift portion preferably faces the other shift portion, and the shift tooth row of the other shift portion faces the one shift portion in the axial direction, in particular in such a way that the shift tooth row of one shift portion faces the shift tooth row of the other shift portion in the axial direction, and the shift tooth row of the other shift portion faces the shift tooth row of one shift portion in the axial direction. The respective length of the respective dog teeth of the respective shift tooth row extends in the axial direction, for example for each shift portion, from a defined axial reference plane up to the respective tooth end, at which the respective teeth of the respective shift tooth row end.

[0010] If the shift portion is in the engaged position, the shift dog is in the closed state. It is preferably provided in the closed state of the shift dog that the teeth of the respective shift toothed row engage in the dog gap, also referred to as the gap or the tooth gap, of the respective other shift toothed row, wherein the respective dog gap of the respective shift toothed row is arranged between the teeth of the respective shift toothed row, in particular in the circumferential direction of the shift portion extending about the rotational axis.

[0011] It is furthermore preferably provided that at least one of the dog teeth of the respective shift toothed row is designed as a catch tooth / hook tooth, the length of which extending in the axial direction and thus along the rotational axis is greater than the length of the other dog teeth of the respective shift toothed row designed as locking teeth / ratchet teeth.

[0012] It has also been shown to be particularly advantageous if the detection device comprises at least one sensor means and at least one encoder means rotationally fixed to one shift portion. Preferably, the encoder means is a wheel encoder. The sensor means is also referred to as a sensor, for example. The sensor means is rotationally fixed to the housing and / or to another shift portion, for example. Since the encoder means is rotationally fixed to one shift portion, the encoder means can rotate with one shift portion about the rotational axis relative to the sensor means and in particular relative to another shift portion or the housing. The encoder means has a plurality of encoder segments. These encoder segments are arranged one after the other and in particular spaced apart from one another, for example in the circumferential direction of the encoder means extending about the rotational axis, so that between each two adjacent encoder segments an encoder gap, also referred to simply as a gap, is arranged. The encoder segments are measurable by means of the sensor means (sensor), so that from the measurement of the encoder segments the rotational position of one shift portion can be detected. In other words, for example, each rotational position is characterized by at least one of the encoder segments, so that by measuring this encoder segment the rotational position can be detected, in particular as in a crankshaft sensor. The sensor means is designed to provide an electrical signal, for example, which characterizes the encoder segment and thus the rotational position detected. For example, each encoder segment generates a respective signal pulse or sensor pulse, so that the signal has one pulse for each encoder segment, for example. From the signal pulse, the encoder segment and thus the rotational position can be measured or determined. The encoder segments are therefore also referred to as pulse-emitting segments or pulse-emitting encoder segments of the encoder means, in particular of the wheel encoder.

[0013] It is preferably provided here that the number of pulse-emitting segments of the encoder means corresponds at least to the sum of the number of teeth of the shift toothed row of one shift portion and the number of tooth gaps of the shift toothed row of this one shift portion.

[0014] The feature "the electronic computing device is designed to move the shift element from the disengaged position to the engaged position in dependence on the detected rotational position" means, in particular, that the electronic computing device is designed to cause the shift element to move from the disengaged position to the engaged position. To this end, at least one of the shift elements or actuators is controlled by means of the electronic computing device. It is also preferred that the electronic computing device is designed to move the shift element from the engaged position to the disengaged position and thus to cause the shift element to move from the engaged position to the disengaged position. The movement of the shift element from the disengaged position to the engaged position is also referred to as the shift dog biting in. The movement of the shift element from the engaged position to the disengaged position is also referred to as the shift dog pulling out. The shift dog can thus be caused to bite in and pull out by means of the electronic control device.

[0015] As already indicated, it is preferred that the first shift element and / or the second shift element, in particular only one of the shift elements with respect to a plurality of shift elements, is connected to the electric machine or to the output device of the electric machine, as the case can be, depending on the drive. This can mean, in particular, that the first and / or the second shift element, in particular one of the shift elements, is connected to the output device, in particular the shaft, of the electric machine in a rotationally fixed manner.

[0016] When the number of pulses, i.e. the number of encoder segments, is at least the same as the sum of the number of teeth and the number of tooth gaps of the shift toothing of one shift element, the shift dog can then be engaged with high shift comfort, in particular. That is, there is then a so-called absolute resolution, so that the rotational position of one shift element can be detected very precisely. If, for example, the shift toothing has 60 teeth and thus 60 tooth gaps, the number of encoder segments is preferably 120, so that the number of pulses is 120.

[0017] In other designs of the application, it is provided that the number of encoder segments is at least twice the aforementioned sum. It is thus preferred that the number of encoder segments is at least four times the number of teeth of the shift toothing of one shift element.

[0018] In other designs of the application, it is provided that the encoder means has a gap, also referred to as a blank, where a first width of a first gap between two adjacent encoder segments of the encoder means, which extends in the circumferential direction of the encoder means about the rotational axis, is greater than a second width of a second gap or another gap between adjacent encoder segments of the encoder means, which extends in the circumferential direction of the encoder means. Depending on the gap, one of the rotational positions can be detected as a reference pose or reference position, from which further rotational positions can advantageously be detected or determined, in particular, i.e. the shift dog is engaged, for example, only at rotational positions at which a tooth tip tooth position does not occur.

[0019] It is also preferred that one ratchet tooth is provided between the two hooks, respectively.

[0020] It is also preferable to provide that the shift dog is designed as a dog clutch, wherein the sensor is connected to a further shift part which is fixedly connected to the transmission housing, and the encoder device is fixedly connected to a movable shift part. This is advantageous in terms of being able to precisely adjust the engagement process in the case of a shift part which is fixed to the housing, since the sensor then has zero rotational speed and thus cannot rotate relative to the housing about the rotational axis.

[0021] It is conceivable in other designs of the application that the shift dog is designed as a dog clutch, wherein, for example, the further shift part is connected to at least one or exactly one wheel of the motor vehicle, either as a driven or as a counter-rotating wheel. The rotational speed of the further shift part can thus be determined and thus known, wherein the rotational speed of the further shift part can be determined from the motor vehicle speed, for example along the ground.

[0022] It is conceivable in other designs that the electronic computing device has or executes a routine for pulse distribution in the event of a shift dog disengagement after starting the motor vehicle, in order to correspondingly assign the angular or rotational position to the pulses.

[0023] It is conceivable in other designs of the application that the control device has a teaching routine / learning program, in particular for execution in an end-of-line test (EOL test: end-of-line test) after and / or during production of the vehicle or after a transmission change in the use of the motor vehicle, which determines for each pulse whether engagement is possible in the event of a shift dog (shift element) engagement.

[0024] It is provided in other designs, in particular as an alternative to the teaching routine, that the wheel encoder has a marking, notch, etc., so that the angular position of the missing pulse of the wheel encoder has the same fixed setting relative to the sensor in all series-produced transmissions. The teaching routine can be dispensed with when the wheel encoder has, for example, a marking and there is a set condition that the wheel encoder is always installed at the same angular position. It is conceivable in particular that a routine for pulse distribution is executed before the teaching routine in each newly installed transmission, which is also referred to as learning or teaching.

[0025] The gap is also referred to as a gap pulse, wherein it is conceivable to provide exactly one or more gaps or gap pulses. The larger or wider encoder gap at the gap in relation to the other encoder gaps leads to a mutual distance of two adjacent signal pulses which is larger than the mutual distance of the remaining adjacent pulses, so that the encoder gap or gap pulse can be identified. All pulses following the gap pulse can be indexed, so that, for example, the respective angular position or the respective rotational position of a shift portion which is, for example, rotationally fixed to a shaft can be determined. The number of pulses generated, for example, by a magnetized pole wheel or tooth, is preferably significantly larger than the number of toothing, at least four times larger. By means of a targeted installation and / or teaching routine, it is determined for the pulse index or the index of the region between two pulses whether it corresponds to a gap or a tip tooth position. By means of this information and by means of a rotational speed sensor which is as precise as possible, the pawl can be held at the gap position for the engagement or meshing of the pawl, so that the tip tooth position is avoided.

[0026] The application also comprises a method for operating the shift device according to the application. The advantages and advantageous designs of the shift device according to the application are to be regarded as advantages and advantageous designs of the method according to the application and vice versa.

[0027] Further advantages, features and details of the application result from the following description of preferred embodiments and in conjunction with the drawings. The features mentioned in the description and the features combinations mentioned in the description above and the features and feature combinations mentioned in the following description of the drawings and / or shown alone in the only drawing can be adopted in other combinations or alone, without departing from the scope of the application. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A schematic view of a shift device for a motor vehicle transmission according to the application is shown. DETAILED DESCRIPTION

[0029] Figure 1 A partial view of a shift device 10 for a transmission of a motor vehicle, in particular a car, is shown. The transmission has a housing 12 which is shown schematically in particular in Figure 1 The shift device 10 comprises at least one unsynchronized shift pawl 14, which is also referred to simply as shift element or pawl. The motor vehicle comprises, for example, an electric machine, by means of which the motor vehicle can be driven in particular purely electrically, in particular in such a way that at least or exactly two wheels of the motor vehicle can be driven by means of the electric machine. The electric machine has a stator and a rotor which can be rotated relative to the stator and by means of which the motor vehicle can be driven. The shift pawl 14 has a first shift portion 16 and a second shift portion 18. As in Figure 1As indicated by the dashed arrow 20, the shift portion 18 can be rotated relative to the shift portion 16 and relative to the housing 12 about the axis of rotation 22. It is conceivable here, in particular, that the shift portion 16 is fixed against rotation on the housing 12 and thus cannot be rotated relative to the housing 12 about the axis of rotation 22. It is conceivable, in particular, that the shift portion 18 is connected to the motor rotor against rotation.

[0030] The shift portion 16 has a first shift toothing 24 with first teeth 26 and first tooth gaps 28 arranged between the teeth 26. The shift portion 18 has a second shift toothing 30 with second teeth 32 and second tooth gaps 34 arranged between the teeth 32. It is conceivable that the respective teeth 26, 32 have a respective length parallel to the axis of rotation 22. Here, the length of the teeth is indicated by Z1 in Figure 1 The length of the teeth is indicated by Z2 in Figure 1 The respective teeth Z1 are also referred to as hook teeth and the respective teeth Z2 are also referred to as ratchet teeth. The shift dog 14 and the shift toothings 24, 30 are designed, for example, as described in DE 10 2012 043 592 A1.

[0031] It can be seen from Figure 1 that the shift toothing 24 is axially, i.e. along the axis of rotation 22, opposite the shift toothing 30 and the shift toothing 30 is axially opposite the shift toothing 24. The shift portions 16, 18 can be moved opposite one another along the axis of rotation 22 between at least one engagement position and at least one disengagement position as indicated in Figure 1 In the engagement position, the shift toothings 24, 30 are in mesh with one another, whereby the shift portions 16, 18 are connected to one another against rotation in a form-fit manner. In the disengagement position, the shift toothings 24, 30 are disengaged from one another. This means that the shift toothings 24, 30 are not in mesh with one another in the disengagement position and thus the shift portions 16, 18 can be rotated opposite one another about the axis of rotation 22 in the disengagement position. The movement of the shift portions 16, 18 from the disengagement position to the engagement position is also referred to as engagement or engagement process or biting in of the shift dog 14.

[0032] In order for the shift dog 14 to be able to engage particularly advantageously, the shift device 10 comprises a detection device 36 with which a rotational position to which the shift portion 18 can be rotated relative to the shift portion 16 and relative to the housing 12 about the axis of rotation 22 is measured or can be measured. Furthermore, an electronic computing device 38 is provided, which is indicated particularly schematically in Figure 1 with which the shift portions 16, 18 can be moved from the disengagement position to the engagement position depending on the measured rotational position.

[0033] The detection device 36 has a sensor 40, which is indicated particularly schematically in Figure 1The encoder means 40, which is shown here by way of example and is designed as a sensor wheel / wheel encoder, has at least one pole pair 42, for example and in particular one for each tooth 32 and each tooth gap 34. The encoder means 40 and thus also the pole pairs 42 are connected in a rotationally fixed manner to the shift portion 18. The detection device 36 also comprises sensor means 44, also referred to simply as sensors, which are connected in a rotationally fixed manner to the housing 12 and / or the shift portion 16. The pole pairs 42 are encoder sections of the encoder means 40 and can be measured by means of the sensor means 44. The sensor means 44 provide a signal 46, for example an electrical signal, which is designed as a raw signal, which has, for example and in particular, exactly one pulse P for each pole pair 42 measured. Here, the encoder means 40 have a gap F, also referred to as an empty space, at which a first width of the encoder means 40 extending in the circumferential direction thereof around the rotation axis 22 of a first gap between two adjacent pole pairs 42 is greater than a second width extending in the circumferential direction of the encoder means of a second gap between two adjacent pole pairs 42. The gap F is thus represented in the signal 46 in that a first distance between two adjacent pulses P of the signal 46 is greater than a second distance between other pulses P of the signal 46. The gap F thus represents one of the rotational positions mentioned, so that this one rotational position can be used as a reference position or reference attitude. The reference attitude is thus, for example, known and is thus a known attitude of the shift portion 18 relative to the shift portion 16. From the reference attitude, the rotational position can be ascertained or identified in which, upon engagement of the dog, a tooth tip tooth position does not occur. The shift dog 14 can thus be engaged very advantageously.

[0034] List of reference signs

[0035] 10 shift device

[0036] 12 housing

[0037] 14 shift dog

[0038] 16 shift portion

[0039] 18 shift portion

[0040] 20 arrow

[0041] 22 rotation axis

[0042] 24 shift tooth row

[0043] 26 tooth

[0044] 28 tooth gap

[0045] 30 shift tooth row

[0046] 32 tooth

[0047] 34 tooth gap

[0048] 36 detection device

[0049] 38 electronic computing device

[0050] 40 encoding means

[0051] 42 pole pair

[0052] 44 sensing means

[0053] 46 signal

[0054] F void

[0055] P pulse

[0056] Z1 tooth

[0057] Z2 tooth

Claims

1. A shift device (10) for a motor vehicle transmission, having at least one unsynchronized shift dog (14) which comprises two shift parts which are rotatable relative to one another about an axis of rotation (22) and each have a shift toothing and are movable relative to one another along the axis of rotation (22) between at least one engagement position and at least one disengagement position, wherein In the engaged position, the shift toothed rows engage one another such that the shift parts are connected to one another against rotation; and in the disengaged position, the shift toothed rows are separated from one another such that the shift parts can be rotated relative to one another about the rotational axis (22), wherein - a detection device (36) is provided, by means of which a rotational position to which at least one of the shift parts can be rotated relative to the other shift part about the rotational axis (22) can be measured, - an electronic computing device (38) is provided, which is designed to move the shift parts (16, 18) from the disengaged position to the engaged position depending on the measured rotational position, - the detection device (36) comprises at least one sensor means (44) and at least one encoder means (40) which is connected to the one shift part against rotation and can thus be rotated with the one shift part relative to the sensor means (44) about the rotational axis (22), the encoder means having a plurality of encoder sections (42) which can be measured by means of the sensor means (44) such that the rotational position of the one shift part can be measured depending on the measurement of the encoder sections (42), and - the number of the encoder sections (42) corresponds at least to the sum of the number of the teeth (32) of the shift toothed row of the one shift part and the number of the tooth gaps (34) of the shift toothed row of the one shift part, - wherein the encoder means (40) has at least one encoder section (42) for each tooth (32) and for each tooth gap (34).

2. The shift device (10) according to claim 1, characterized in that The number of the encoder sections (42) is at least twice the sum.

3. The shift device (10) according to claim 1 or 2, characterized in that The encoder means (40) has a gap (F) at which a first width of a first gap between two adjacent encoder sections (42) of the encoder means (40) extending in a circumferential direction of the encoder means (40) about the rotational axis (22) is greater than a second width of a second gap between adjacent encoder sections (42) of the encoder means (40) extending in the circumferential direction of the encoder means (40).

4. A method for operating a shift device (10) according to any one of claims 1 to 3.

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