Method for controlling the selection of a gear in an automatic mechanical transmission

Abstract

The application discloses an automatic mechanical gearbox selection and gear shifting failure control method, which realizes the selection and gear shifting function in a fault state by combining the actual driving condition and the fuzzy control mechanism, thereby protecting the gearbox gear and driving safety, and providing more driving options for the state when the fault occurs. Specifically, the selection and gear shifting mechanism is monitored to determine whether it is an electrical failure or a mechanical failure. When it is determined to be an electrical failure, based on the selection failure and / or gear shifting failure state, the corresponding preset strategy is executed in combination with the driving intention to retain the driving function. When it is determined to be a mechanical failure, based on the selection failure or gear shifting failure state, the gear is kept or the electric cylinder is controlled to restore limited selection and gear shifting function. The application has been verified and statistically shown that in the case of selection and gear shifting failure, the basic driving function can be ensured as much as possible when the fault state occurs, the fault home function is realized, and the driving risk in the case of selection and gear shifting failure is greatly reduced, and the vehicle reliability and safety are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic transmissions, and in particular to a method for controlling gear selection and shift failure of an automatic mechanical transmission. Background Art

[0002] A typical AMT (automatic mechanical transmission) is based on the basic structure of a manual transmission (MT), with the addition of an automatic control mechanism of an electronic unit. It replaces the operations originally performed manually by the driver, such as clutch separation and engagement, shifting and engaging gears, and adjusting the engine speed and torque, thereby automating the gear shifting process.

[0003] The shift selection mechanism is the shift control core of the AMT. Its main function is to execute different gears and different fork engagements based on the current TCU's gear decision. If the shift selection actuator fails during the shift control process, the vehicle will not be able to drive in the gear. At this time, power is lost and the vehicle cannot be driven.

[0004] In addition, if the shift actuator does not fail, but the sensor that monitors the shift position fails, the shift control based on position information will also be greatly affected. Without position information, the wrong gear will be frequently shifted, such as low gear shifting to high gear, high gear shifting to low gear, forward gear shifting to reverse gear, etc., which will seriously affect the safety of the gearbox and even directly threaten the driver's driving safety.

[0005] If the actuator or position sensor fails, the driver will be "forced" to stop the vehicle immediately, which often affects the driving experience. Current protection technologies all directly protect and interrupt power output after a fault occurs, which has many disadvantages:

[0006] First, the current vehicle speed and driving conditions are ignored and the output is interrupted; second, after the output is interrupted, there are almost no effective measures to drive the vehicle to a maintenance station, service station, etc., that is, the fault "go home" function has limited effect; third, a failure in one place may lead to the loss of all core functions of the vehicle, which is a simple over-protection. Summary of the Invention

[0007] In view of the above, the present invention aims to provide a method for controlling failure of automatic mechanical transmission gear selection and shifting, so as to solve the problem of power interruption and loss of driving function of the whole vehicle after failure.

[0008] The technical solution adopted in the present invention is as follows:

[0009] The present invention provides a method for controlling failure of automatic mechanical transmission gear selection and shifting, which includes:

[0010] Monitoring whether the gear selection and shift mechanism has a fault, including determining whether an electrical gear selection and shift failure has occurred by identifying a preset flag, or determining whether a mechanical gear selection and shift failure has occurred based on the gear selection and shift execution process;

[0011] When a gear selection and shift electrical failure is determined to have occurred, a corresponding preset strategy is executed based on the state of the gear selection failure and / or the gear shift failure in combination with the driving intention to maintain driving function, the preset strategy including at least one of the following: maintaining the gear, coasting in neutral, coaxial gear pushing, or clutch opening and closing control;

[0012] When it is determined that a gear selection and shifting mechanical failure has occurred, the gear is maintained or the electric cylinder is controlled to restore a limited gear selection and shifting function based on the state of the gear selection failure or the gear engagement failure.

[0013] In at least one possible implementation, the control strategy for electrical failure of gear selection and shifting includes:

[0014] When it is determined that the gear selection is invalid and the gear shift is not invalid, if the in-gear state is satisfied, it is determined whether a gear change request is detected. If not, the current gear is maintained.

[0015] In at least one possible implementation, if it is detected that the gear change request is an upshift request, the current gear is forcibly maintained; if it is detected that the gear change request is a downshift request, the transmission is controlled to coast in neutral, and once the driving intention is detected again, only the starting gear or reverse gear is allowed to be shifted from neutral.

[0016] In at least one possible implementation, if the gear change request is detected, the coaxial gear push operation is driven by the shift electric cylinder to meet the driving intention corresponding to the gear change request.

[0017] In at least one possible implementation, the failure control method further includes:

[0018] After the push operation is triggered, the actual speed ratio between the output shaft and the intermediate shaft is calculated and compared with the preset speed ratio of the requested gear;

[0019] Determine whether the coaxial push gear position is successful based on the comparison result;

[0020] If unsuccessful, shift to neutral or disengage the clutch synchronously.

[0021] In at least one possible implementation, the control strategy for electrical failure of gear selection and shifting further includes:

[0022] When it is determined that the gear shift fails, the gear selection does not fail, or both the gear shift and the gear selection fail, if the in-gear state is satisfied and no downshift request is detected, the current gear is maintained.

[0023] In at least one possible implementation manner, if the downshift request is detected to be from a preset high gear to a preset low gear, the clutch is triggered to be opened.

[0024] In at least one possible implementation, if the in-gear state is a preset low gear and a downshift request is detected, requesting a gear other than neutral is prohibited;

[0025] When a request for neutral is detected, the clutch is triggered to open while maintaining the current gear state until the driving intention is detected again, at which time the clutch is controlled to engage.

[0026] In at least one possible implementation, the control strategy for the failure of the gear selection mechanism includes:

[0027] The shift selector block is pushed by the electric cylinder, and the valid shift range is determined after the shift selector block falls back, and the shift action is only allowed to be performed for the gears within the valid shift range.

[0028] In at least one possible implementation, the control strategy for shift mechanism failure includes:

[0029] If it is determined that the gear engagement fails, the vehicle shifts from the current gear to neutral until the speed reaches the speed range of the adjacent lower gear of the current gear, and maintains driving in the adjacent lower gear and the following gears;

[0030] If it is determined that the gear shifting is invalid, then based on the current vehicle speed change, determine whether the requested gear is a coaxial gear:

[0031] If so, the coaxial opposite gear push operation is directly performed through the electric cylinder;

[0032] If not, the current gear is maintained, and when the vehicle speed is not within the speed range of the current gear, the clutch is triggered to open.

[0033] Compared with the prior art, the main design concept of the application is that, by combining the actual driving condition and the fuzzy control mechanism, the gear selection and shifting function in the fault state is realized to protect the gearbox gear and the driving safety of the driver, and more driving options are provided for the state when the fault occurs. Specifically, the gear selection and shifting mechanism is monitored for electrical failure or mechanical failure, when it is determined to be electrical failure, based on the state of gear selection failure and / or gear shifting failure, the corresponding preset strategy is executed in combination with the driving intention to retain the driving function; when it is determined to be mechanical failure, based on the state of gear selection failure or gear shifting failure, it is kept in gear or the electric cylinder is controlled to restore limited gear selection and shifting function. The application is actually verified and counted, in the case of gear selection and shifting failure, the basic driving function can be ensured as much as possible when the fault state occurs, the "fault home" function is ensured in more than 90% of the failure cases, thereby greatly reducing the driving risk in the case of gear selection and shifting failure, and improving the reliability and safety of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0034] To make the objectives, technical solutions and advantages of the present application clearer, the following will further describe the present application with reference to the accompanying drawings, in which:

[0035] Figure 1 The flowchart of the automatic mechanical gearbox gear selection and shifting failure control method provided by the embodiment of the present application is shown. DETAILED DESCRIPTION

[0036] The embodiments of the present application will be described in detail below, and the examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as a limitation on the present application.

[0037] The present application proposes an embodiment of an automatic mechanical gearbox gear selection and shifting failure control method, specifically as shown in Figure 1 , which includes:

[0038] Step S1, monitoring whether the gear selection and shifting mechanism fails, including determining whether the gear selection and shifting electrical failure occurs by identifying the preset flag bit, or determining whether the gear selection and shifting mechanical failure occurs according to the gear selection and shifting execution process;

[0039] Step S2, when it is determined that the gear selection and shifting electrical failure occurs, based on the state of gear selection failure and / or gear shifting failure, the corresponding preset strategy is executed in combination with the driving intention to retain the limited driving function, the preset strategy at least includes one of the following: keeping in gear, coasting with empty gear, coaxial gear position pushing or clutch opening and closing control;

[0040] Step S3: When it is determined that a gear selection and shifting mechanical failure has occurred, based on the state of gear selection failure or gear engagement failure, the gear is maintained or the electric cylinder is controlled to restore a limited gear selection and shifting function.

[0041] Regarding the specific situation of electrical failure of gear selection and shifting, the strategy details can be formulated according to the following specific situations:

[0042] (1) Gear selection fails but gear shifting does not fail (which specific failure can be determined by the sensor voltage, such as the voltage is less than 200mV or greater than 4800mV, or by the underlying fault code of the electric cylinder). According to the general gear layout, the transmission cannot determine the lateral gear selection position (longitudinal control is normal). If the gear is in gear when the fault occurs, that is, it is in D gear or R gear, and is driving normally without a request to change the gear (the driver can determine the intention by operating the pedals, baffles, etc.), then the current gear will be maintained.

[0043] On this basis, here are two approaches to handling different gear shift intentions:

[0044] The first is that when the driver demands a faster speed by stepping on the accelerator pedal (upshift control under normal circumstances), since the gear selection function is invalid, in principle, the gear change (upshift) is not allowed, and the current gear remains; when the driver thinks the current speed is too fast, he slows down by releasing the accelerator, stepping on the brake, etc. (downshift control under normal circumstances), since the gear shift function is normal in this case, that is, the longitudinal control in the gear layout is normal, the gear shift actuator can be controlled to make the gearbox gear in the N gear position. At this time, the gearbox input shaft is no longer engaged with the output shaft, the engine power no longer transmits power, and the vehicle is in a neutral coasting state, and then deceleration can be achieved by coasting resistance and normal braking. The advantage of the method of having the gearbox shift out of N gear here is that when the vehicle speed drops to a preset low speed, such as 5km / h, the mechanical action of the transverse gear selection spring can make the shift block in the neutral position inevitably reach the No. 1 shift fork (Fork1, corresponding to 1st gear / R gear in the general AMT gear layout, and the gear selection control is replaced by the elastic force of the mechanical component) position. In this way, once the driving intention is detected again, the shift actuator is allowed to shift longitudinally into 1st gear or R gear.

[0045] The second method provides an advanced method for situations where gear selection fails but shifting is enabled, expanding the permissible speed range by pushing the gears in opposite directions. In practice, this involves using the maximum thrust output by the shift cylinder to push the shifter directly into the coaxial opposite gear. This allows the vehicle speed range to be appropriately expanded to meet the driver's intent in this fault condition.

[0046] For example, in the aforementioned transmission gear layout example, gears 2 and 3 of the transmission are on the same shaft, and gears 4 and 5 are also on the same shaft. For these four coaxial gears, 100% duty cycle is allowed at this time, that is, the maximum electric cylinder force is directly pushed to the opposite gear. This can ensure that when the gear selection fails in gear 2 or 3, the vehicle speed can be kept normally within the speed range of gears 2 to 3 (in some designs, the gear 2 speed range also includes the gear 1 speed range. Therefore, if the current gear is gear 2 or 3 when this fault occurs, the actual speed of the vehicle can be expanded within the speed range of gears 1 to 3). If the gear selection fails in gear 4 or 5, the vehicle can be kept normally within the speed range of gears 4 to 5. Of course, it is understandable that the limitations of this preferred method come from the coaxial gear itself, that is, if the gear in question is 3rd gear, once there is a request to shift up after a fault occurs, the highest speed can only be within the maximum design limit of 3rd gear. If the gear in question is 2nd gear, once there is a request to shift up after a fault occurs, this advanced method can be used to push the shift block longitudinally from 2nd gear to 3rd gear with maximum thrust; correspondingly, if the gear in question is 5th gear, once there is a request to shift down after a fault occurs, this advanced method can be used to push the shift block longitudinally from 5th gear to 4th gear with maximum thrust. If the gear in question is 4th gear when the fault occurs, the first control method of disengaging the neutral gear can be used after a downshift request is detected.

[0047] It should be noted that for the aforementioned advanced measure of providing 100% duty cycle gear shifting, full gear shifting monitoring can also be performed during this process. Specifically, after the shifting operation, the speed ratio of the output shaft and the intermediate shaft is compared with the preset speed ratio of the requested gear to determine whether the coaxial shifting gear was successful. If the collected speed ratio does not match the speed ratio of the requested gear, the shift is determined to have failed and the gear shift is immediately disengaged. Alternatively, the clutch can be disengaged and a corresponding fault signal can be output synchronously. It should be noted that after actual vehicle verification of the aforementioned embodiment, after 200 coaxial shifting operations, the preferred strategy had a 100% success rate.

[0048] (2) Shifting fails, gear selection does not fail, or both shifting and gear selection fail. In this case, the longitudinal position of the gear layout cannot be determined, that is, the longitudinal control ability of the gear shift is lost. If the gear is in the gear position when the fault occurs, the vehicle will still maintain the current gear during normal driving or when there is a request to shift up. The maximum speed that the vehicle can reach is the speed output by the gear at the maximum engine speed.

[0049] If the driver intends to slow down (for example, when a downshift request is received), the fault can be handled in the following two situations:

[0050] The first kind, i.e. the station in the gearbox angle, the demand is from the preset high speed gear (can be set to 3 gears and above) to the preset low speed gear (such as 1 gear, 2 gears), the clutch is triggered to disengage, i.e. the power output of the engine end and the gearbox input end is disconnected, the engine is no longer combined with the gearbox, at this time the vehicle is in the open clutch coasting state (different from the mechanical mechanism of executing to N gear, but also plays a role in coasting), to ensure that the current gear will not be dragged by the engine to the minimum engine speed due to too low speed, causing the engine to stall.

[0051] The second kind, if the current gear is a preset low gear, such as 1 gear, 2 gears or R gear, the fault occurs and the speed is reduced, the current gear is maintained and the gearbox is prohibited from requesting other gears except N gear (neutral gear), if it is detected that the neutral gear is requested (such as the driver switches the gear knob from D gear to N gear), the current gear state is still maintained in the gearbox, but the clutch is disengaged to disconnect the power output (equivalent to meeting the driver's intention to remove the neutral gear), and if it is detected that the driver engages D gear or R gear, the clutch can be recombined to normally drive the vehicle (because the gearbox still maintains the gear state when the fault occurs).

[0052] Regarding the specific situation of the selection and gear shifting mechanical failure, i.e. the failure in the selection and gear shifting control process, the following processing form can be referred to:

[0053] (1) Regarding the selection failure

[0054] The selection does not reach the corresponding request gear position under the normal control strategy of the TCU, at this time the cylinder force can be withdrawn first, for example, 0 current is given to the cylinder, the gear block returns to the initial Fork1 position under the action of the spring, and then the cylinder current is given again to select the gear again. At this time, affected by the performance of the cylinder, in order to protect the cylinder from ablation, the time and number of times of using the cylinder for selection are judged, and if the expected position is still not selected after continuous current is given to the cylinder for more than a certain time (such as 2 seconds) or the number of times of selection exceeds a certain number (such as 5 times), the selection control fault is triggered, i.e. it can be represented that there may be deformation in the selection actuator, at this time the maximum duty cycle is given to the selection cylinder to push the maximum force, and after the selection lever falls back, the effective selection area is determined by the limit of the maximum force push, and the gear positions in the effective selection area are allowed to perform subsequent gear shifting. For example, after the selection failure is determined by the number of retries, the maximum force is given to the Fork4 area for a short time, and if the lever falls to the Fork2 area and does not fall into the Fork1 area, it is determined that gears 2, 3, 4, 5 and 6 are allowed to be selected and engaged.

[0055] (2) Regarding the gear shifting failure

[0056] Specifically, it can be divided into gear engagement failure and gear disengagement failure. Gear engagement is the process of pushing the gear from the N gear position to the in-gear position. Similarly, if the in-gear position is not reached under the first gear engagement control, the gear engagement control is re-executed. After several cycles (such as 5 times) and still the target in-gear position is not engaged, the gear is disengaged to N gear. At this time, the power is interrupted and the vehicle speed drops until it reaches the gear before the current gear and maintains driving below the current gear; if the gear disengagement fails, that is, it is impossible to shift to the N gear position in the gear state and still cannot disengage N after trying more than a predetermined number of times, then based on the current vehicle speed change requirements, determine whether the requested gear is a coaxial gear. If so, the advanced method mentioned above is adopted to skip the N gear disengagement process and directly push it to the coaxial opposite gear with all strength. If not, that is, the current requested gear is not a coaxial opposite gear, the clutch is triggered to disengage and the power output is interrupted.

[0057] In summary, the main design concept of the present invention is to achieve a gear selection and shifting function in a fault state by combining actual driving conditions with a fuzzy control mechanism, thereby protecting the transmission gears and the driver's driving safety, and providing more driving options for responding to fault conditions. Specifically, the gear selection and shifting mechanism is monitored to determine whether it has an electrical failure or a mechanical failure. When an electrical failure is determined, based on the status of the gear selection failure and / or the gear shift failure, a corresponding preset strategy is executed in combination with the driving intention to maintain driving function; when a mechanical failure is determined, based on the status of the gear selection failure or the gear engagement failure, the gear is maintained or the electric cylinder is controlled to restore limited gear selection and shifting functions. According to actual verification and statistics, the present invention can maintain basic driving functions as much as possible in the event of a gear selection and shift failure, ensuring a "failure return home" function in more than 90% of failure cases, thereby greatly reducing the driving risk in the event of a gear selection and shift failure and improving the reliability and safety of the entire vehicle.

[0058] In the embodiment of the present invention, "at least one" refers to one or more, and "more" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, a and b, a and c, b and c, or a, b and c, where a, b, c can be single or multiple.

[0059] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings, but the above is only a preferred embodiment of the present invention. It should be noted that the technical features involved in the above embodiments and their preferred modes can be reasonably combined and matched into a variety of equivalent schemes by those skilled in the art without departing from or changing the design ideas and technical effects of the present invention; therefore, the scope of implementation of the present invention is not limited to what is shown in the drawings. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the scope of protection of the present invention.

Claims

1. A method for controlling failure of automatic mechanical transmission gear selection and shifting, characterized in that: include: Monitoring whether the gear selection and shift mechanism has a fault, including determining whether an electrical gear selection and shift failure has occurred by identifying a preset flag, or determining whether a mechanical gear selection and shift failure has occurred based on the gear selection and shift execution process; When a gear selection and shift electrical failure is determined to have occurred, a corresponding preset strategy is executed based on the state of the gear selection failure and / or the gear shift failure in combination with the driving intention to maintain driving function, the preset strategy including at least one of the following: maintaining the gear, coasting in neutral, coaxial gear pushing, or clutch opening and closing control; When it is determined that a gear selection and shifting mechanical failure has occurred, based on the state of gear selection failure or gear engagement failure, the gear is maintained or the electric cylinder is controlled to restore limited gear selection and shifting functions; Among them, the control strategy for electrical failure of gear selection and shifting includes: When it is determined that the gear selection is invalid and the gear shift is not invalid, if the in-gear state is satisfied, it is determined whether a gear change request is detected. If not, the currently in-gear gear is maintained; If it is detected that the gear change request is an upshift request, the current gear is forcibly maintained; if it is detected that the gear change request is a downshift request, the transmission is controlled to coast in neutral, and once the driving intention is detected again, only the starting gear or reverse gear is allowed to be shifted from neutral.

2. The automatic mechanical transmission shift selection failure control method according to claim 1, characterized in that: If the gear change request is detected, the coaxial gear push operation is driven by the shift electric cylinder to meet the driving intention corresponding to the gear change request.

3. The automatic mechanical transmission shift selection failure control method according to claim 2, characterized in that: The failure control method further includes: After the push operation is triggered, the actual speed ratio between the output shaft and the intermediate shaft is calculated and compared with the preset speed ratio of the requested gear; Determine whether the coaxial push gear position is successful based on the comparison result; If unsuccessful, shift to neutral or disengage the clutch synchronously.

4. The automatic mechanical transmission shift selection failure control method according to claim 1, characterized in that: The control strategy for electrical failure of gear selection and shifting also includes: When it is determined that the gear shift fails, the gear selection does not fail, or both the gear shift and the gear selection fail, if the in-gear state is satisfied and no downshift request is detected, the current gear is maintained.

5. The automatic mechanical transmission shift selection failure control method according to claim 4, characterized in that: If the downshift request is detected to be from a preset high gear to a preset low gear, the clutch is triggered to open.

6. The automatic mechanical transmission shift selection failure control method according to claim 4, characterized in that: If the in-gear state is the preset low gear and a downshift request is detected, requesting other gears except neutral is prohibited; When a request for neutral is detected, the clutch is triggered to open while maintaining the current gear state until the driving intention is detected again, at which time the clutch is controlled to engage.

7. The automatic mechanical transmission shift selection failure control method according to claim 1, characterized in that: The control strategies for gear selection mechanical failure include: The shift selector block is pushed by the electric cylinder, and the valid shift range is determined after the shift selector block falls back, and the shift action is only allowed to be performed for the gears within the valid shift range.

8. The automatic mechanical transmission shift selection failure control method according to claim 1, characterized in that: The control strategies for shift mechanism failure include: If it is determined that the gear engagement fails, the vehicle shifts from the current gear to neutral until the vehicle speed reaches the speed range of the adjacent lower gear of the current gear, and maintains driving in the adjacent lower gear and the gear below; If it is determined that the gear shifting is invalid, then based on the current vehicle speed change, determine whether the requested gear is a coaxial gear: If so, the electric cylinder is used to push the gear in the opposite direction. If not, the current gear is maintained, and when the vehicle speed is not within the speed range of the current gear, the clutch is triggered to open.

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