Vehicle with a transmission and method for operating such a transmission

Abstract

Vehicle with a transmission with an electronic control unit (31) for engaging and disengaging gears (G1 to G6) of the transmission, wherein a target gear (R) can be engaged or preselected by means of the control unit (31) when the vehicle is stationary, and wherein the control unit (31) starts a shift routine upon detection of a tooth-on-tooth position of the target gear shift partners (24, 29), in which the control unit (31) - interrupts the engagement of the target gear (R), - engages an intermediate gear (G5) different from the target gear (R) in order to effect a compensating rotational movement (D) in the transmission by engaging the intermediate gear (G5), by means of which the tooth-on-tooth position can be resolved, and then - the target gear (R) is now re-engaged without any interference contours and the intermediate gear (G5) is disengaged, whereby a test device (30) is assigned to the control unit (31) which carries out an intermediate gear test in which it is checked in advance which of the gears (G1 to G6) is suitable as an intermediate gear in order to generate the compensating rotational movement (D) in the transmission when it is engaged, and wherein the control unit (31) engages the intermediate gear (G5) classified as suitable by the test device (30), wherein the test device (30) detects all gears (G1 to G6) that have been engaged during the vehicle standstill up to the time of the test during the intermediate gear test, characterized in that the testing device (30) classifies a gear (G1) already engaged while the vehicle is stationary as an unsuitable intermediate gear, and that the testing device (30) classifies a gear (G3, G5) not yet engaged while the vehicle is stationary as a suitable intermediate gear.

Description

[0001] The invention relates to a vehicle with a transmission according to the preamble of claim 1 and a method for operating such a transmission according to claim 8.

[0002] A vehicle has a transmission, in particular a dual-clutch transmission, with an electronic control unit for engaging and disengaging gears. With the help of the control unit, a target gear can be engaged or preselected when the vehicle is stationary. The target gear can, for example, be a starting gear with which the vehicle is moved off once the vehicle has come to a standstill. Alternatively, the target gear can be part of a parking lock function. To activate such a parking lock function, the two separating clutches of the dual-clutch transmission are first released. Then a preselected gear is engaged. As soon as the control unit detects that the vehicle is stationary, a locking gear is also engaged to lock the transmission.

[0003] If the control unit detects a tooth-on-tooth position of the target gear shift partners, it starts the following shift routine: First, engagement of the target gear is interrupted. The control unit also engages an intermediate gear different from the target gear in order to generate a compensating rotational movement in the transmission when the intermediate gear is engaged. The compensating rotational movement is intended to resolve the tooth-on-tooth position. The control unit then engages the target gear without any interference contours, while the intermediate gear is disengaged again.

[0004] To generate a compensating rotational movement, the shifting partners of the intermediate gear must be at least slightly offset from one another. In contrast, if the shifting partners are perfectly aligned in axial alignment, no compensating rotational movement is generated. Therefore, if the control unit selects an intermediate gear whose shifting partners are perfectly aligned with one another, no compensating rotational movement is generated. In this case, the tooth-to-tooth position of the shifting partners of the target gear cannot be resolved.

[0005] DE 10 2014 225 453 A1 discloses a generic non-positive gear shift strategy in a transmission in which a tooth-on-tooth position of a participating positive-locking claw clutch is released. DE 10 2015 213 683 A1 discloses a shift strategy in which a tooth-on-tooth position is released by shaft rotation via clutch drag torque.

[0006] The object of the invention is to provide a vehicle with a transmission and a method for operating such a transmission, with which standstill shifts can be carried out in a simple and reliable manner compared to the prior art.

[0007] The object is achieved by the features of claim 1 or 8. Preferred developments of the invention are disclosed in the subclaims.

[0008] The invention relates to a vehicle with a transmission having an electronic control unit with which transmission gears can be engaged and disengaged. With the help of the electronic control unit, a target gear can be engaged when the vehicle is stationary. For example, the target gear can be a starting gear with which the vehicle is moved off once the vehicle has come to a standstill. Alternatively, the target gear can be part of a parking lock function. To activate such a parking lock function, the two separating clutches of the dual-clutch transmission are first released. Then a preselect gear is engaged. As soon as the control unit detects that the vehicle is stationary, an additional locking gear is engaged to lock the transmission.

[0009] If the control unit detects a tooth-on-tooth position of the target gear shift partners when engaging the target gear, it starts the following shift routine: First, engagement of the target gear is interrupted. The control unit also engages an intermediate gear that is different from the target gear. Engaging the intermediate gear is intended to generate a compensating rotational movement in the transmission, by means of which the tooth-on-tooth position is resolved. The control unit can then engage the target gear without any interference contours and, in particular, also disengage the intermediate gear. According to the invention, a test device that performs an intermediate gear test is assigned to the control unit. During the intermediate gear test, a check is carried out in advance to determine which gear is suitable as an intermediate gear to generate the compensating rotational movement in the transmission when engaged. The intermediate gear classified as suitable by the test device is then engaged by the transmission control unit.

[0010] According to the invention, during the intermediate gear test, the test device records all gears that have been engaged while the vehicle was stationary up to the time of the test. The test device classifies a gear that has already been engaged while the vehicle was stationary as an unsuitable intermediate gear. Conversely, the test device classifies a gear that has not yet been engaged while the vehicle was stationary as a suitable intermediate gear.

[0011] The intermediate gear test described above is based on the fact that a gear engaged while the vehicle is stationary can no longer function successfully as an intermediate gear. In this case, the gear shift partners of this gear are aligned tooth-to-tooth (due to the previous engagement). Therefore, re-engaging this gear (as an intermediate gear) cannot lead to the desired compensating rotational movement in the transmission.

[0012] It is preferred if the test device can perform the intermediate gear test using sensors already installed in the transmission. Position or travel sensors that detect the position or travel of gearshift elements while the vehicle is stationary are suitable for this purpose. If a change in the position or travel of a gearshift element is detected, the test device can classify the associated engaged gear as an unsuitable intermediate gear.

[0013] The transmission, in particular a sub-transmission of a dual-clutch transmission, has in one technical implementation a number of gear levels, each forming gears. Each gear level has a shift gear loosely mounted on a transmission shaft and a fixed gear meshing therewith, arranged on another transmission shaft. The shift gear can be coupled to the associated transmission shaft by means of a gearshift element. The gearshift element can be a sliding sleeve, the internal toothing of which sits on a corresponding external toothing of a sliding sleeve carrier arranged in a rotationally fixed manner on the transmission shaft. To engage a gear, the sliding sleeve is axially adjustable from a neutral position into a shift position.In the shift position, the sliding sleeve's internal teeth can mesh with the sliding sleeve carrier on the one hand and with the external teeth of a clutch body of the shift gear to be engaged on the other. In the tooth-to-tooth position, the teeth of the sliding sleeve's internal teeth strike the teeth of the external teeth of the clutch body of the shift gear to be engaged. In contrast, in the tooth-to-gap position, the sliding sleeve's internal teeth engage tightly against the teeth of the external teeth of the clutch body of the shift gear to be engaged. In contrast, in the tooth-to-gap position, the sliding sleeve can shift smoothly through to its shift position.

[0014] In a dual-clutch transmission, a first drive shaft and a second drive shaft can be connected to a drive unit, such as an internal combustion engine, via clutches of a dual clutch. A first sub-transmission can be activated via the first drive shaft, while a second sub-transmission can be activated via the drive shaft. In such a dual-clutch transmission, the test device must select a suitable intermediate gear that is located together with the target gear in the same sub-transmission. This creates a rotary connection from the intermediate gear to the target gear, via which the compensating rotary movement can be transmitted from the intermediate gear to the target gear.

[0015] An embodiment of the invention is described below with reference to the attached figures.

[0016] They show: Fig. 1 to 5 different representations of a dual clutch transmission.

[0017] In the Fig. 1 shows a transmission structure of a drive train of a motor vehicle, which essentially consists of an internal combustion engine 1 and a dual-clutch transmission. The dual-clutch transmission has a first drive shaft 7 and a second drive shaft 9. These are arranged coaxially and can be connected in an alternating manner to a power output shaft 10 of the internal combustion engine 1 via two, for example, hydraulically actuated powershift clutches K1, K2, in a torque-transmitting manner. The first drive shaft 7 is in the Fig. 1 is realized as a solid shaft, which is guided coaxially within the second drive shaft 9, which is realized as a hollow shaft. An output shaft 13 is provided axially parallel to the two drive shafts 7, 9. This output shaft drives via a gear stage 15 with spur gears to an input shaft 19 of an axle differential 21. Flange shafts 23 lead from the axle differential 21 on both sides to vehicle wheels (not shown).

[0018] By means of the first and second input shafts 7, 9, a first partial transmission I and a second partial transmission II of the dual-clutch transmission can be activated. In the figure, the first partial transmission I is axially spaced from the dual clutch K1, K2 with the second partial transmission II interposed. Fixed and loose gears are arranged in gear planes on the two input shafts 7, 9 and on the output shaft 13. These are combined into gear sets to form six forward gear stages G1 to G6 and one reverse gear stage R. Fig. 1, the idler gears of all gear stages are positioned on the output side of the output shaft 13. The idler gears can be shifted using gear shift elements S1 to S4, which are also positioned on the output shaft 13.

[0019] Each of the gear shift elements S1 to S4 is implemented as a synchronous clutch with a sliding sleeve 24, which is axially adjustable on one or both sides by means of an indicated shift fork 25 over an adjustment path Δs. The sliding sleeve 24 sits with its internal toothing (not shown) on a corresponding external toothing of a sliding sleeve carrier 27 arranged in a rotationally fixed manner on the output shaft 13. Each of the sliding sleeves 24 is in the Fig. 1 is positioned in a neutral position. Starting from the neutral position, the sliding sleeves 24 can be moved into a shift position in order to shift a gear. In the shift position, the sliding sleeve internal teeth mesh with the sliding sleeve carrier 27 on the one hand and with the external teeth of a clutch body 29 of a shift gear on the other hand. For example, in the Fig. 2 the sliding sleeve 24 of the gearshift element S4 in its left switching position, in which the first gear G1 is engaged.

[0020] Each of the shift forks 25 is in the Fig. 1 in operative connection with, for example, a hydraulically operating actuator 26, which can be controlled by a shift control unit 31. When actuated accordingly, the shift fork 25 is axially adjusted over a travel Δs in order to bring the associated sliding sleeve 24 into or out of clutch engagement with a shift gear.

[0021] The travels Δs of the shift forks 25 are detected by travel sensors 37, which, among other things, are in signal communication with a test device 30 associated with an electronic transmission control unit 31. The electronic transmission control unit 31 can be used to control the actuators 26 and a clutch control unit 35 of the dual clutch K1, K2.

[0022] When the vehicle is stationary, the internal combustion engine 1 is switched off, while the separating clutches K1, K2 are released. Accordingly, the input shafts 7, 9 and the output shaft 13 are also stationary. In this case, the transmission control unit 31 can preselect first gear G1 as the starting gear in preparation for the next driving operation, as described in the Fig. 2. Accordingly, when the first gear G1 is engaged, the sliding sleeve 24 of the gearshift element S4 is shifted into its left switching position.

[0023] The core of the invention relates to a gear change during vehicle standstill, for example from the already preselected first gear G1 to the reverse gear R (as the new target gear). Such a gear change can occur, for example, due to a changed gear selection by the user during vehicle standstill. However, the gear change from the first gear G1 to the reverse gear R (ie target gear) can be blocked due to a tooth-on-tooth position, as described in the Fig. 3. Accordingly, the teeth 22 of the internal toothing of the sliding sleeve 24 strike against the teeth 28 of the external toothing of the clutch body 29 of the shift gear of the reverse gear R.

[0024] As soon as the tooth-to-tooth position of the reverse gear shift partners (i.e. sliding sleeve 24 and clutch body 29) is detected, the transmission control unit 31 starts the following routine: First, the engagement of the reverse gear R is interrupted. In addition, the test device 30 carries out an intermediate gear test in which a suitable intermediate gear is selected, upon engagement of which a compensating rotational movement D ( Fig. 4) is generated in the gearbox, by means of which the tooth-on-tooth position of the reverse gear shift partners 24, 29 can be resolved.

[0025] The intermediate gear classified as suitable by the test device 30 is engaged by the transmission control unit 31. In the present exemplary embodiment, the transmission control unit 31 selects the fifth gear G5 as the suitable intermediate gear. After briefly engaging and disengaging the fifth gear G5, which forms the intermediate gear, the transmission control unit 31 controls the shift fork 25 of the gearshift element S4 in order to engage the reverse gear R (as the target gear) without any interference contours.

[0026] The intermediate gear test according to the invention performed by the test device 30 is described below. Accordingly, in the intermediate gear test, all gears G1 to G6 that have already been engaged while the vehicle was stationary up to the intermediate gear test are detected by the test device 30. The test device 30 performs the following categorization: A gear that has already been engaged while the vehicle was stationary is classified as an unsuitable intermediate gear. Conversely, a gear that has not yet been engaged while the vehicle was stationary is classified as a suitable intermediate gear. In the present exemplary embodiment, the first gear G1 has already been engaged as a preselected gear while the vehicle was stationary. This was followed by a gear change to reverse gear R (as the target gear).The test device 30 therefore classifies the first gear G1 as an unsuitable intermediate gear, while the gear G5 (or alternatively the gear G3) is classified as a suitable intermediate gear.

[0027] This intermediate gear test performed by test device 30 is based on the fact that a gear already engaged while the vehicle is stationary (in this case, first gear G1) no longer successfully causes a compensating rotational movement D as an intermediate gear. The shift partners (sliding sleeve 24 and shift gear coupling body 29) of this gear G1, which was already engaged while the vehicle was stationary, are already aligned tooth-to-gap due to the previous engagement. Re-engaging this gear G1 would therefore not result in a compensating rotational movement D in the transmission.

[0028] In contrast, there is a high probability that in the fifth gear G5, which is classified as suitable, the shift partners 24, 29 are slightly offset by a rotational offset v ( Fig. 5) are twisted. When engaging the fifth gear G5, a Fig. 5, by means of which the tooth-on-tooth position of the shift partners 24, 29 of the reverse gear R can be resolved.

[0029] It is relevant that the intermediate gear G5, which was classified as suitable by the test device 30, and the reverse gear R are located in the same sub-transmission I. This means that a (in the Fig. 5 indicated by arrows) rotary connection from the intermediate gear G5 via the drive shaft 7 to the target gear (i.e. reverse gear R) is ensured, so that the compensating rotary movement D ( Fig. 5) is transmitted from the intermediate gear G5 in a movement path to the target gear (i.e. reverse gear R). LIST OF REFERENCE SYMBOLS: 1 internal combustion engine 7 first drive shaft 9 second drive shaft 10 Power output shaft 13 Output shaft 15 spur gear stage 19 Input shaft 21 axle differential 22 teeth of the internal toothing of the sliding sleeve 24 23 flange shafts 24 sliding sleeve 25 shift fork 26 Actuator 27 sliding sleeve carrier 28 teeth of the external toothing of the clutch body 29 of the shift gear of the reverse gear R 29 Shift gear clutch body 30 Test facility 31 Switching control unit 35 Clutch control unit 37 sensors K1, K2 separating couplings S1 to S4 gearshift elements Δs travel D Compensating rotational movement v Rotational offset

Claims

[1] Vehicle with a transmission with an electronic control unit (31) for engaging and disengaging gears (G1 to G6) of the transmission, wherein a target gear (R) can be engaged or preselected by means of the control unit (31) when the vehicle is stationary, and wherein the control unit (31) starts a shift routine upon detection of a tooth-on-tooth position of the target gear shift partners (24, 29), in which the control unit (31) - interrupts the engagement of the target gear (R), - engages an intermediate gear (G5) different from the target gear (R) in order to effect a compensating rotational movement (D) in the transmission by engaging the intermediate gear (G5), by means of which the tooth-on-tooth position can be resolved, and then - the target gear (R) is now re-engaged without any interference contours and the intermediate gear (G5) is disengaged, whereby the control unit (31) is assigned a testing device (30) which carries out an intermediate gear test in which it is checked in advance which of the gears (G1 to G6) is suitable as an intermediate gear in order to generate the compensating rotational movement (D) in the transmission when it is engaged, and wherein the control unit (31) engages the intermediate gear (G5) classified as suitable by the testing device (30), wherein the testing device (30) detects all gears (G1 to G6) that have been engaged during the vehicle standstill up to the time of the test during the intermediate gear test, characterized by , that the testing device (30) classifies a gear (G1) already engaged while the vehicle is stationary as an unsuitable intermediate gear, and that the testing device (30) classifies a gear (G3, G5) not yet engaged while the vehicle is stationary as a suitable intermediate gear. [2] Vehicle according to claim 1, characterized bythat the intermediate gear test of the test device (30) is based on the fact that a gear (G1) already engaged while the vehicle is stationary no longer has a promising effect as an intermediate gear with a compensating rotary movement (D), since its shift partners (24, 29) are already aligned tooth-to-gap due to the engagement that has already taken place, so that a renewed engagement of this gear (G1) does not generate a compensating rotary movement (D) in the transmission. [3] Vehicle according to one of the preceding claims, characterized by that the intermediate gear test of the test device (30) is carried out using position or travel sensors (37) which detect a position or travel (Δs) of gearshift elements (S1 to S4) while the vehicle is at a standstill. [4] Vehicle according to claim 3, characterized bythat when a change in position or a travel (Δs) of a gearshift element (S1 to S4) is detected, the associated engaged gear is classified by the testing device (30) as an unsuitable intermediate gear. [5] Vehicle according to one of the preceding claims, characterized bythat the transmission, in particular a partial transmission (I, II) of a dual-clutch transmission, has a number of gear-forming gear planes, each with a shift gear loosely mounted on a transmission shaft (7, 9, 13) and a fixed gear meshing therewith and arranged on another transmission shaft (7, 9, 13), and that the shift gear can be coupled to the associated transmission shaft (7, 9, 13) by means of a gearshift element (S1 to S4), wherein the gearshift element (S1 to S4) has a sliding sleeve (24) which sits with its internal toothing on a corresponding external toothing of a sliding sleeve carrier (27) arranged in a rotationally fixed manner on the transmission shaft (7, 9, 13), and that for engaging a gear, the sliding sleeve (24) can be adjusted from a neutral position into a shift position,in which the sliding sleeve internal toothing meshes on the one hand with the sliding sleeve carrier (27) and on the other hand with the external toothing of a clutch body (29) of the shift gear to be engaged, and in particular in the tooth-on-tooth position, the teeth of the sliding sleeve internal toothing abut against the teeth of the external toothing of the clutch body (29) of the shift gear to be engaged. [6] Vehicle according to claim 5, characterized by that the dual-clutch transmission has a first drive shaft (7) and a second drive shaft (9) which can be connected to a drive unit, in particular an internal combustion engine (1), via clutches (K1, K2) of a dual clutch, and that in particular a first partial transmission (I) and a second partial transmission (II) can be activated by means of the first and second drive shafts (7, 9). [7] Vehicle according to claim 6, characterized bythat the testing device (30) selects a suitable intermediate gear (G3, G5) which is arranged together with the target gear (R) in the same partial transmission (I). [8] Method for operating a vehicle with a transmission having an electronic control unit (31) for engaging and disengaging gears (G1 to G6) of the transmission, wherein a target gear (R) is engaged or preselected by means of the control unit (31) when the vehicle is stationary, and wherein the control unit (31) starts a shift routine upon detection of a tooth-on-tooth position of the target gear shift partners (24, 29), in which the control unit (31) - interrupts the engagement of the target gear (R), - engages an intermediate gear (G5) different from the target gear (R) in order to effect a compensating rotational movement (D) in the transmission by engaging the intermediate gear (G5), by means of which the tooth-on-tooth position can be resolved, and then - the target gear (R) is now re-engaged without interference contours and in particular the intermediate gear (G5) is disengaged, wherein the control unit (31) is assigned a testing device (30) which carries out an intermediate gear test in which it is checked in advance which of the gears (G1 to G6) is suitable as an intermediate gear in order to generate the compensating rotational movement (D) in the transmission when it is engaged, and wherein the control unit (31) engages the intermediate gear (G5) classified as suitable by the testing device (30), wherein the test device (30) detects all gears (G1 to G6) that have been engaged during the intermediate gear test up to the time of the test, characterized by , that the testing device (30) classifies a gear (G1) already engaged while the vehicle is stationary as an unsuitable intermediate gear, and that the testing device (30) classifies a gear (G3, G5) not yet engaged while the vehicle is stationary as a suitable intermediate gear.

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