Method for managing a gear change in a gearbox
The control method optimizes engine torque management in manually controlled gearboxes by adjusting torque reduction and restoration based on real-time sensor feedback, addressing inefficiencies and emissions in gear shifts.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- VITESCO TECHNOLOGIES GMBH
- Filing Date
- 2024-07-23
- Publication Date
- 2026-06-12
AI Technical Summary
Existing gear change methods in manually controlled gearboxes of motorized mobile machines do not adequately account for variations due to component aging or user differences, leading to inefficient and prolonged engine torque reduction during gear shifts, affecting responsiveness and pollutant emissions.
A control method that iteratively acquires the angular position of the selector shaft, reducing engine torque when a predetermined threshold is exceeded and restoring it when approaching the next gear position, with thresholds adjusted to minimize torque reduction duration.
This method enhances driving responsiveness and reduces pollutant emissions by optimizing engine torque management during gear shifts, ensuring timely torque restoration based on real-time sensor feedback.
Smart Images
Figure 00000012_0000 
Figure 00000012_0001 
Figure 00000013_0000
Abstract
Description
Title of the invention: Method for managing a gear change in a gearbox
[0001] The present invention relates to a control method for managing a gear change in a gearbox of a motorized mobile machine.
[0002] The present invention finds particular application in mobile devices of the motor cycle type, such as motorcycles or off-road motorcycles. The mobile devices in question may have two wheels, three wheels, or even four wheels ('quad').
[0003] The mobile machine to which the present invention is applied includes a manually controlled gear-shifting gearbox, i.e., the gear shifting is not automatic.
[0004] The gearbox is a gearbox with discrete ratios, each having a predetermined reduction ratio, that is to say it is not a continuously variable reduction transmission ('variator').
[0005] The mobile device to which the present invention is applied comprises a ratio selection shaft and an angular position sensor delivering a voltage value corresponding to a current angular position of the selection shaft.
[0006] As regards the engine, here an internal combustion engine, it can be a 4-stroke engine or a 2-stroke engine, moreover the engine can be a single cylinder, a twin cylinder, without excluding other configurations.
[0007] According to a very common configuration, the gear change control is carried out with a foot of the driver, in this case the left foot, by actuating a gear change control lever.
[0008] We are interested here in a so-called rapid gear change, in particular a gear change without using the clutch. In practice, the driver operates the gear shift lever with their foot without using the clutch control with their hand.
[0009] The advantage of making a quick gear change is mainly for upshifts, when the machine is at increasing speed.
[0010] It is known to detect, by means of the aforementioned sensor, the start of the gear change sequence, and to reduce or eliminate engine torque for a predefined time period, in particular to allow the engine speed to fall, so that the engagement of the next higher adjacent gear is easy and quick.
[0011] Even if the aforementioned predefined timing can be derived from a calibration table, it does not take into account certain variations, such as the aging of components, differences in operation between several users of the device, the presence of certain games which are different from one device to another although theoretically identical.
[0012] The inventors sought to improve the situation, in particular to refine the duration of reduction or suppression of engine torque to just what is necessary during the upshift sequence.
[0013] To this end, a control method is proposed for managing an upshift in a gearbox of a mobile machine having an engine, the shift being intended to change from a starting gear to an ending gear, in which the gearbox includes a selector shaft movable between a first stable position corresponding to the starting gear and a second stable position corresponding to the ending gear, in which the gearbox includes an angular position sensor of the selector shaft delivering a voltage value corresponding to a current angular position of the selector shaft, the method comprising: - an acquisition step in which the voltage value corresponding to the angular position of the selection shaft is iteratively acquired, - a motor torque reduction step, whereby, starting from a first reference value corresponding to the first stable position of the selector shaft, the current voltage value increases and becomes greater than a first predetermined threshold, then a motor torque reduction is triggered, the first predetermined threshold exceeding the first reference value by a first deviation; - a motor torque restoration step, whereby, when the current voltage value increases and becomes greater than a second predetermined threshold, then the motor torque reduction is removed, and the required motor torque is applied. the second predetermined threshold being separated by a second gap, and below, a second reference value corresponding to the second stable position of the selection tree.
[0014] Thanks to these provisions, particularly the engine torque restoration step, it is possible to shorten the duration of engine torque reduction or suppression. This is beneficial for the driving experience of the machine and increases the perceived responsiveness from the driver's point of view.
[0015] Shortening the shutdown time is favorable for reducing pollutant emissions.
[0016] Thanks to the method proposed here, the duration of the torque cut-off is adjusted to just what is necessary.
[0017] In practice, as soon as the selection shaft leaves the stable position corresponding to the starting ratio, the engine torque is reduced or eliminated, and conversely, as soon as the shaft As the selection approaches the stable position corresponding to the arrival ratio, the couple is restored.
[0018] Advantageously, we do not wait for a predefined time to elapse before restoring the required torque; we restore it as soon as the arrival ratio is at least partially engaged.
[0019] It should be noted that the terms 'first' and 'second' above cover not only the case of shifting from the first to the second gear ratio but also all cases of higher gear ratios. It is therefore understood that the final gear ratio is directly above the initial gear ratio, for example, a final gear ratio of R4 with an initial gear ratio of R3, or, in another example, a final gear ratio of R3 with an initial gear ratio of R2.
[0020] It should be noted that the concept of "torque reduction" encompasses a substantial reduction of torque or a total elimination of torque.
[0021] The phrase "the second predetermined threshold being separated by a second gap, and below, from a second reference value" should be understood as the second predetermined threshold is below the second reference value, and the second threshold is separated from the second reference value by the second gap.
[0022] According to one embodiment, when, after an execution of the motor torque reduction step, the current voltage value does not reach the second predetermined threshold and returns to the first predetermined threshold, then the motor torque reduction is removed, and the required motor torque is applied.
[0023] Wherefore, if an incomplete maneuver is undertaken by the driver and this triggers a torque cut-off, the torque is restored after the initially programmed time has elapsed.
[0024] Similarly, if an object strikes the operating lever and causes a small displacement of the latter which engenders the cut-off of torque normally provided for a gear change, the normal situation is restored after the initially programmed time has elapsed.
[0025] It is also noted that if the proposed strategy of shortening the torque cut-off time does not work, for any reason, then the predefined time delay will still lead to the restoration of the motor torque when it has elapsed.
[0026] According to one embodiment, the first deviation is between 5% and 15% of the difference between the second reference value and the first reference value.
[0027] As soon as the selector shaft leaves the first stable position, this is interpreted as the beginning of a gear shift sequence. The initial deviation is small enough for early detection. The anticipated torque cut-off also helps facilitate disengagement from the starting gear.
[0028] According to one embodiment, the second deviation is between 5% and 15% of the difference between the second reference value and the first reference value.
[0029] As soon as the second reference value is approached, the torque requested by the driver is restored. This means that, in practice, as soon as the final gear is at least partially engaged, the torque is restored in order to minimize the time during which the torque has been reduced or eliminated. This increases the responsiveness of the system.
[0030] According to one option, the acquisition step includes an acquisition frequency of at least 100 Hz, or even 1 kHz.
[0031] As a result, the value is sampled at least every 1 ms. This allows us to react advantageously in real time to transition sequences that can typically last a few tens of milliseconds.
[0032] According to one embodiment, the first stable position of the selection shaft corresponds either to the second gear ratio, or to the third gear ratio, or to the fourth gear ratio, and the first reference value corresponds respectively to the second, third and fourth gear ratio tensions.
[0033] The proposed method can thus be applied to all rising passages from the first ratio up to the highest ratio.
[0034] According to one embodiment, at least the second, third and fourth ratio voltages are derived from a calibration table and are adjusted by learning.
[0035] Thanks to the mechanical indexing of each gear position, the control unit under load can be programmed to consider a stable voltage value as corresponding to the voltage of the engaged gear. Based on this, the control unit can adjust the value initially present in the calibration table.
[0036] This allows us to take into account certain drifts in mechanical components or play that develop with aging. We can also provide for initial learning and supplementary learning adjustments from time to time.
[0037] The present invention also relates to a computer configured to implement the process as defined above.
[0038] The present invention also relates to a computer program product, preferably stored on a non-transient memory medium, comprising instructions which, when executed by at least one processor of the computer, performs the process as defined above.
[0039] The present invention also relates to a control system for managing an upshift in a gearbox of a mobile machine having an engine, the gearbox comprising a selector shaft, an angular position sensor of the selector shaft delivering a voltage value corresponding to a current angular position of the selector shaft, and a shift control lever gearbox ratio, the control system including a computer configured to implement the process as described above.
[0040] According to one embodiment, the gearbox gear shift control lever is connected to the selector shaft by a linkage mechanism. The gear shift control lever is external, i.e., accessible by foot, and is of the impulse type; the linkage mechanism transforms an impulse movement into a rotation of the selector shaft from a stable starting position to a stable ending position, which corresponds to a gear change.
[0041] According to one embodiment, the angular position sensor is a potentiometric type sensor. This is a simple and robust solution, easy to implement from an electronic point of view.
[0042] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which [Fig.l] schematically illustrates an area of the gear shift lever on a motorcycle; [Fig.2] schematically illustrates an example of a rotation control mechanism for a selector shaft in a motorcycle gearbox; [Fig.3] illustrates a chronogram of the transmission of reports; [Fig.4] shows a functional diagram of the control system involved in the present invention; [Fig.5] illustrates an example of a chronogram of the transition from one ratio to another, in this case between the 2nd ratio and the 3rd ratio; [Fig.6] illustrates another example of a chronogram.
[0043] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.
[0044] The present invention finds particular application in mobile vehicles of the motor cycle type, such as motorcycles or off-road motorcycles. The mobile vehicles in question may have two wheels, three wheels, or even four wheels ('quad').
[0045] The application has been illustrated on a motorcycle, with a manually controlled gear-shifting gearbox.
[0046] In the illustrated example, there are five gears in the gearbox, respectively labeled RI, R2, R3, R4 and R5. Of course, the invention is also applicable to configurations with fewer than five gears or more than five gears.
[0047] As known per se, the gearbox includes forks that move sliding gear selectors. The position of the forks is controlled by a gear selector shaft, designated 1.
[0048] According to one embodiment, an angular position sensor 2 is provided, with the rotating part connected in rotation to the ratio selection shaft 1, and the body of the sensor being stationary.
[0049] The angular position sensor 2 delivers a voltage value corresponding to the current angular position of the selection shaft.
[0050] With reference to [Fig.2], the angular position sensor 2 is arranged at the end of the selection shaft.
[0051] The angular position sensor 2 is electrically connected to a control unit, also called a computer, discussed later, by electrical conductors 20.
[0052] The angular position sensor 2 is an analog sensor. In the illustrated example, the angular position sensor 2 is a potentiometric type sensor. It covers an angular range close to 360°. It could cover a smaller range.
[0053] Other types of sensor can also be used, provided that their output resembles an analog value which takes several distinct values depending on the respective ratio engaged.
[0054] The angular position sensor can be installed on an auxiliary wheel engaged with the selector shaft. Regardless of the sensor technology or the sensor installation configuration, the angular position sensor provides, directly or indirectly, an image of the angular position of the selector shaft.
[0055] The motorcycle is equipped with a gearbox gear shift control lever 3.
[0056] The control lever 3 is connected to the gear selection shaft 1 via a linkage mechanism noted 4.
[0057] As is well known, and visible in [Fig.1], the control lever 3 is moved by the driver's foot F, either upwards (G-up) or downwards (G-Dn) depending on whether the driver wants to shift to a higher or lower gear.
[0058] The control lever 3 is mounted to rotate around the axis X0.
[0059] The control lever 3 is of the impulse type, that is to say that the lever of the control returns to a rest position when no action is taken from the driver's foot.
[0060] The control lever 3 cooperates with the selection shaft by means of the linkage mechanism noted 4, a simplified version of which is illustrated in [Fig.2].
[0061] A first connecting rod 41 is rotationally linked with the control lever 3, with rotation about the axis X0. A second connecting rod 42 is connected to the first connecting rod 41 by a pivot joint with axis XL. The second connecting rod 42 includes teeth 13 configured to hook the pins 11.
[0062] The gear selection shaft 1 is mounted for rotation on the gearbox housing relative to the axis X2.
[0063] The ratio selection tree 1 includes pins 11 actuated by the second connecting rod 42 and indexing grooves 12.
[0064] A third connecting rod 43 with a roller 44 indexes the particular positions of the ratios of the ratio selection shaft 1, the roller 44 fitting into the index hollows 12.
[0065] To complete the understanding about the ratio selection tree 1 and the linkage mechanism 4, the reader may refer to documents US3421384 and US4491031.
[0066] The gear selector shaft is sometimes called a 'selector drum' or 'selector barrel'. The gear selector shaft 1 includes grooves, generally annular, which allow the movement of the forks to be driven axially, i.e. along the axis X2, by cam action.
[0067] The timing diagram in [Fig.3] illustrates a complete driving phase from zero speed with the gearbox in neutral N, up to 5th gear and back to second gear.
[0068] More precisely, from the beginning until time t1, the gearbox is in neutral (N). Then, from time t1 to time t2, first gear RI is engaged. From time t2 to time t3, second gear R2 is engaged. From time t3 to time t4, third gear R3 is engaged. From time t4 to time t5, fourth gear R4 is engaged. Finally, at time t5, fifth gear R5 is engaged. Times t6, t7, and t8 correspond to downshifts (R5 to R2).
[0069] It is noted that the voltage delivered by the sensor evolves in steps, each step (VR0, VR1, VR2, VR3, VR4, VR5) corresponds to a particular angular position of the selection shaft (0N, 0R1, 0R2, 0R3, 0R4, 0R5, cf. [Fig.4]).
[0070] Furthermore, each gear corresponds to a specific ratio of the gearbox. It is therefore possible to display the engaged gear on the instrument cluster at any time.
[0071] In the illustrated example, the value delivered by the angular position sensor 2 when the gearbox is in neutral ratio N is approximately 1.1 volts. When the gearbox is in ratio RI, the voltage value VR1 is approximately 0.6 V. When the gearbox is in ratio R2, the voltage value VR2 is approximately 1.7 V. When the gearbox is in ratio R3, the voltage value VR3 is approximately 2.4 V. When the gearbox is in ratio R4, the voltage value VR4 is approximately 3.3 V. When the gearbox is in ratio R5, the voltage value VR5 is approximately 4.3 V. These reference voltages are also referred to as 'ratio voltages' in this document.
[0072] As apparent in [Fig.4], the control system involved here comprises a control unit 5 which includes at least a first functional block 51 (acronym 'Shift CTrl') in charge of changing the gearbox ratio and a second functional block 52 (acronym 'Trq CTrl') in charge of calculating and applying torque through the engine (internal combustion engine here).
[0073] The control unit 5 ('computer') continuously acquires the voltage delivered by the angular position sensor 2.
[0074] The acquisition step is carried out at an acquisition frequency of at least 100 Hz. This sampling gives at least one value every 10 milliseconds for the voltage delivered by the sensor.
[0075] An upshift without using the clutch typically lasts in practice a few tens of milliseconds.
[0076] Turning now to [Fig. 5], we observe in detail a transition from a starting ratio to an ending ratio; here, in the illustrated example, it is a transition from the 2nd ratio to the 3rd ratio. Of course, what is presented applies, mutatis mutandis, to the transitions R3 -> R4, R4 -> R5, R5 -> R6, as appropriate.
[0077] We start, at time ta, from a first reference value V1 corresponding to the first stable position 01 of the selection tree, and we obtain at the end of the passing sequence a second reference value V2 corresponding to the second stable position 02 of the selection tree (arrival position).
[0078] If the starting ratio is the 2nd ratio then VI = VR2 and 01 = 0R2, and also V2 = VR3 and 02 = 0R3. If the starting ratio is the 3rd ratio then VI = VR3, 01 = 0R3, V2 = VR4 and 02 = 0R4.
[0079] The proposed method provides for a motor torque reduction step, according to which when the current voltage value 61 increases and becomes greater than a first predetermined threshold VS1, then a motor torque reduction is triggered (transition 62 at time tb, OFF to ON).
[0080] For reasons of conciseness of the exposition, the boolean output of torque reduction, i.e. ON or OFF, is represented at mid-height and in the middle of the chronogram.
[0081] The first predetermined threshold VS1 exceeds the first reference value VI by a first deviation EL. For example, it can be chosen that the first deviation El is between 5% and 15% of the difference between the second reference value V2 and the first reference value VL. For example, El can be on the order of 20 mV to 60 mV.
[0082] For example, in the illustrated example, the first predetermined threshold VS1 is set at 1.7 volts. El can be chosen between 5% of (V2-V1) and 15% of (V2-V1), for example 10% of (V2-V1).
[0083] At time td, the selection tree 1 is indexed on the position of the arrival ratio, here the 3rd ratio.
[0084] Advantageously, the proposed process provides for a motor torque recovery step, according to which when the current voltage value 61 increases further and becomes greater than a second predetermined threshold VS2, then the motor torque reduction is removed, and the required motor torque is applied (transition 66 at time te).
[0085] The second predetermined threshold VS2 is below V2. A second gap E2 separates the second reference value V2 from the second predetermined threshold VS2.
[0086] The second deviation E2 is between 5% and 15% of the difference between the second reference value V2 and the first reference value VL. E2 can be chosen between 5% of (V2-V1) and 15% of (V2-V1), for example 10% of (V2-V1).
[0087] The deviations El and E2 can have identical or different values. The deviations El and E2 can be managed in a calibration table.
[0088] Fig. 6 illustrates a scenario where the passage is not carried out but an incomplete action is still performed on the selection tree which is moved from its rest position but does not go to the arrival position and returns to the starting position.
[0089] The instant tg corresponds to the maximum voltage value delivered by the sensor during this aborted gear change sequence. After rotating, the selector shaft moves back to the starting position.
[0090] At time th, the value delivered by the sensor falls below the first predetermined threshold VS 1. At this moment the reduction of the motor torque is removed, and the requested motor torque is applied (transition 66 at time th).
[0091] It should be noted that in another alternative implementation, it is at the instant tf when the voltage value crosses back over the reference value V1 that the torque is restored (dotted line).
[0092] It should be noted that the first, second, third, fourth and fifth ratio voltages (VR1, VR2, VR3, VR4, VR5) are derived from a calibration table. They can be adjusted by learning, in relation to the indexing of the ratio positions as explained above.
[0093] The momentary cut-off of engine torque can be achieved, for a certain number of engine cycles, by inhibiting the ignition control and canceling the fuel injection control.
Claims
Demands
1. A control method for managing an upshift in a gearbox of a mobile machine having an engine, the shift being intended to change from a starting gear to a finishing gear, wherein the gearbox includes a selector shaft (1) movable between a first stable position (01) corresponding to the starting gear and a second stable position (02) corresponding to the finishing gear, wherein the gearbox includes an angular position sensor (2) of the selector shaft delivering a voltage value (61) corresponding to a current angular position of the selector shaft, the method comprising: - an acquisition step in which the voltage value corresponding to the angular position of the selector shaft is iteratively acquired, - an engine torque reduction step in which, when,Starting from a first reference value (VI) corresponding to the first stable position (01) of the selector shaft, the current voltage value increases and becomes greater than a first predetermined threshold (VS1), at which point a reduction in motor torque is triggered, the first predetermined threshold (VS1) exceeding the first reference value (VI) by a first gap (E1), - a motor torque recovery step, according to which when the current voltage value increases and becomes greater than a second predetermined threshold (VS2), then the motor torque reduction is removed, and the required motor torque is applied, the second predetermined threshold (VS2) being separated by a second gap (E2), and below, a second reference value (V2) corresponding to the second stable position (02) of the selector shaft.
2. The method according to claim 1, characterized in that when, after the motor torque reduction step has been performed, the current voltage value does not reach the second predetermined threshold (VS2) and returns to the first predetermined threshold (VS1), then removes the engine torque reduction, and the required engine torque is applied.
3. A method according to any one of claims 1 to 2, characterized in that the first deviation (El) is between 5% and 15% of the difference between the second reference value (V2) and the first reference value (VI).
4. A method according to any one of claims 1 to 3, characterized in that the second deviation (E2) is between 5% and 15% of the difference between the second reference value (V2) and the first reference value (VI).
5. A method according to any one of claims 1 to 4, characterized in that the acquisition step comprises an acquisition frequency of at least 100 Hz.
6. A method according to any one of claims 1 to 5, characterized in that the first stable position (01) of the selector shaft corresponds either to the second gear ratio, or to the third gear ratio, or to the fourth gear ratio, and the first reference value (VI) corresponds respectively to second, third and fourth gear ratio tensions (VR2,VR3,VR4).
7. A method according to claim 6, wherein at least the second, third and fourth ratio voltages are taken from a calibration table and are adjusted by learning.
8. Calculator configured to implement the method according to any one of claims 1 to 7.
9. Product computer program, preferably stored on a non-transient memory medium, comprising instructions which, when executed by at least one processor of the computer, carry out the method according to any one of claims 1 to 7
10. Control system for managing an upshift in a gearbox of a mobile machine having an engine, the gearbox comprising a selector shaft (1), an angular position sensor (2) of the selector shaft delivering a voltage value corresponding to a current angular position of the selector shaft and a gearbox gear shift control lever (3), the control system comprising a computer (5) configured to implement the method according to any one of claims 1 to 7.