A transmission shift control method, control system and shift system

Abstract

This invention discloses a transmission shift control method, control system, and shift system. The control method includes the following steps: S1, acquiring vehicle speed S0, vehicle longitudinal acceleration, and throttle opening; S2, determining whether the vehicle needs to shift gears; if so, proceeding to step S3; otherwise, maintaining the current gear; S3, acquiring the current gear ratio ξ1 and the target gear ratio ζ2, and comparing ξ1 and ζ2; if the difference between ξ1 and ξ2 is greater than a preset value P, proceeding to step S4; otherwise, proceeding to step S5; S4, acquiring the engine speed difference EVS and torque difference EVT between the current gear and the target gear, and directly controlling the engine to eliminate the engine speed difference EVS and torque difference EVT; S5, performing a gear shift operation on the transmission. This invention can solve the problem of shift shock, providing good smoothness, and can also reduce clutch wear to extend clutch life.

Description

Technical Field

[0001] This invention relates to the field of transmission technology, specifically to a transmission shift control method, control system, and shift system. Background Technology

[0002] To handle complex loads, construction machinery typically employs high starting torque, necessitating a transmission system with a large gear ratio. Frequent changes in operating conditions also require multiple gear ratios to adapt to different conditions, and rapid gear shifting is essential for improving operational efficiency. Currently, hydraulic mechanical transmissions are commonly used in the power transmission systems of construction machinery. Gear shifting in hydraulic mechanical transmissions is achieved by controlling the oil pressure in the clutch drums of each gear to engage and disengage the gears. The timing and duration of oil filling and emptying, as well as the control of oil pressure, are all managed by the Electronic Control Unit (ECU).

[0003] Smooth shifting and minimizing power interruption during shifts are crucial indicators for evaluating the shifting quality of hydraulic mechanical transmissions. Construction machinery power transmission systems employ multiple gear ratios to meet the power transmission needs of various operating conditions, and the large difference in gear ratios between adjacent gears leads to shift shock. When the difference in gear ratios reaches a certain value, the engine speed should be reduced before shifting from a higher gear ratio to a lower gear ratio. However, drivers often maintain full throttle to ensure continuous power output, causing the engine speed to rise sharply. This results in a mismatch between vehicle speed and engine output speed, as well as the required traction and engine torque output, exacerbating torque surges. Even when controlling the clutch engagement pressure to mitigate the shock during shifting, this method cannot completely absorb the energy of sudden torque changes, resulting in noticeable shift shock.

[0004] Specifically, the transmission currently has the following problems:

[0005] 1. Long shifting time will cause clutch slippage, resulting in wear problems with the gear clutch.

[0006] 2. When shifting from a high gear ratio to a low gear ratio, especially when the difference between the two gear ratios is significant (e.g., from first to second gear), the engine speed should decrease before shifting from first to second. However, in automatic transmission mode, the driver is unaware of the shift point, causing the throttle to remain at high output, resulting in a sharp increase in engine speed. This creates a mismatch between vehicle speed, engine output speed, traction demand, and engine torque output, exacerbating the torque surge. Even if the clutch engagement pressure is controlled to mitigate the impact, this method cannot completely absorb the energy of the torque surge, resulting in a noticeable shock when shifting from first to second gear. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a transmission shift control method, control system and shift system with good gear shifting smoothness in response to the technical problems existing in the prior art.

[0008] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0009] A transmission shift control method includes the following steps:

[0010] S1. Obtain vehicle status information, including vehicle speed S0, vehicle longitudinal acceleration, and throttle opening.

[0011] S2. Determine whether the vehicle needs to shift gears based on the vehicle status information; if so, proceed to step S3; otherwise, maintain the current gear.

[0012] S3. Obtain the current gear ratio ξ1 and the target gear ratio ζ2, and compare the current gear ratio ξ1 with the target gear ratio ζ2; if ξ1-ξ2 is greater than the preset value P, proceed to step S4; otherwise, proceed to step S5.

[0013] S4. Obtain the engine speed difference EVS and torque difference EVT between the current gear and the target gear, and directly control the engine to eliminate the engine speed difference EVS and torque difference EVT.

[0014] S5. Perform a gear shift operation on the transmission.

[0015] Preferably, in step S1, the throttle opening is calculated by reading the engine's throttle parameters.

[0016] Preferably, in step S2, the vehicle needs to shift gears by consulting a preset shift parameter table based on the vehicle speed S0, the vehicle longitudinal acceleration, and the throttle opening.

[0017] Preferably, in step S4, the specific process of obtaining the engine speed difference EVS and torque difference EVT is as follows:

[0018] Obtain the current engine output speed ES0 and torque T0, and obtain the theoretical output torque T1 of the transmission output shaft based on the torque T0 and the current gear ratio ξ1;

[0019] The target output torque T2 is obtained based on the theoretical output torque T1 of the transmission output shaft and the target gear ratio ξ2.

[0020] The target engine speed ES1 is calculated based on the current vehicle speed S0 and the target gear ratio ζ2.

[0021] The engine speed difference EVS = ES1 - ES0 is obtained from the engine target speed ES1 and the current engine output speed ES0; the torque difference EVT = T2 - T1 is obtained from the target output torque T2 and the theoretical output torque T1.

[0022] Preferably, in step S5, the specific process of the gear shifting operation is as follows:

[0023] S51. Obtain the boost curve for each gear and the oil filling and draining overlap time;

[0024] S52. Determine whether to upshift based on the boost curve of each gear and the oil filling and draining overlap time; if upshifting is required, perform the upshift operation; if downshifting is required, perform the downshift operation.

[0025] Preferably, when upshifting, the upshifting logic is invoked, the oil release and filling overlap time of upshifting is controlled, the oil filling and pressure increase of the target gear clutch is controlled, and PWM output is generated; when downshifting, the downshifting logic is invoked, the oil release and filling overlap time of downshifting is controlled, the oil filling and pressure increase of the target gear clutch is controlled, and PWM output is generated.

[0026] The present invention also discloses a transmission shift control system for executing the transmission shift control method described above, comprising:

[0027] The first module is used to acquire vehicle status information, which includes vehicle speed S0, vehicle longitudinal acceleration, and throttle opening.

[0028] The second module is used to determine whether the vehicle needs to shift gears based on the vehicle status information; if so, proceed to step S3; otherwise, maintain the current gear.

[0029] The third module is used to obtain the current gear ratio ξ1 and the target gear ratio ζ2, and compare the current gear ratio ξ1 with the target gear ratio ζ2; if ξ1-ξ2 is greater than the preset value P, then proceed to step S4; otherwise, proceed to step S5.

[0030] The fourth module is used to obtain the engine speed difference EVS and torque difference EVT between the current gear and the target gear, and directly control the engine to eliminate the engine speed difference EVS and torque difference EVT.

[0031] The fifth module is used for shifting gears in the transmission.

[0032] The present invention further discloses a transmission shifting system, including a vehicle speed signal acquisition unit, a shift controller, a hydraulic circuit, and a switching unit located in the hydraulic circuit;

[0033] The vehicle speed signal acquisition unit is connected to the gear shift controller and is used to acquire the vehicle speed and send it to the gear shift controller;

[0034] The shift controller is connected to the engine controller and is used to acquire engine status parameters;

[0035] The shift controller is connected to each switching unit and is used to control the on / off state of the switching units according to vehicle speed and engine status parameters to achieve shifting.

[0036] Preferably, the vehicle speed signal acquisition unit is a vehicle speed sensor, which is installed on the output shaft of the transmission.

[0037] Preferably, the shift controller is connected to the engine controller via a CAN bus.

[0038] Compared with the prior art, the advantages of the present invention are as follows:

[0039] The transmission shift control method of this invention determines the target gear based on the shift pattern, and then selects a specific control method to resolve shift shock based on whether the transmission ratio between the current gear and the target gear is greater than a preset value. If the speed ratio between the current gear and the target gear differs greatly, pressure control is performed based on turbine speed, vehicle speed, and gear clutch, and simultaneously combined with a hybrid engine torque-speed matching method. The engine speed torque is matched by vehicle speed and transmission ratio to achieve shifting. If the transmission ratio between the current gear and the target gear is not significantly different, single gear engagement timing and boost control are selected to reduce engine torque-speed matching time. Torque fluctuations are absorbed by moderate clutch slippage, thereby reducing shifting time. This also reduces power interruption and gear clutch friction time, thereby reducing clutch wear and extending clutch life. Attached Figure Description

[0040] Figure 1 This is a structural diagram of the shifting system of the present invention in an embodiment.

[0041] Figure 2 This is a flowchart of an embodiment of the shift control method of the present invention. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0043] like Figure 2 As shown, the transmission shift control method of this invention includes the following steps:

[0044] S1. Obtain vehicle status information, including vehicle speed S0, vehicle longitudinal acceleration, and throttle opening.

[0045] S2. Determine whether the vehicle needs to shift gears based on the vehicle status information; if so, proceed to step S3; otherwise, maintain the current gear.

[0046] S3. Obtain the current gear ratio ξ1 and the target gear ratio ζ2, and compare the current gear ratio ξ1 with the target gear ratio ζ2; if ξ1-ξ2 is greater than the preset value P, proceed to step S4; otherwise, proceed to step S5.

[0047] S4. Obtain the engine speed difference EVS and torque difference EVT between the current gear and the target gear, and directly control the engine to eliminate the engine speed difference EVS and torque difference EVT.

[0048] S5. Performs corresponding hydraulic circuit control for gear shifting operations of the transmission.

[0049] In one specific embodiment, the process of obtaining the engine speed difference EVS and torque difference EVT in step S4 is as follows:

[0050] Obtain the current engine output speed ES0 and torque T0, and obtain the theoretical output torque T1 of the transmission output shaft based on the torque T0 and the current gear ratio ξ1;

[0051] The target output torque T2 is obtained based on the theoretical output torque T1 of the transmission output shaft and the target gear ratio ξ2.

[0052] The target engine speed ES1 is calculated based on the current vehicle speed S0 and the target gear ratio ζ2.

[0053] The engine speed difference EVS = ES1 - ES0 is obtained from the engine target speed ES1 and the current engine output speed ES0; the torque difference EVT = T2 - T1 is obtained from the target output torque T2 and the theoretical output torque T1.

[0054] The present invention also discloses a transmission shift control system for executing the transmission shift control method described above, comprising:

[0055] The first module is used to acquire vehicle status information, which includes vehicle speed S0, vehicle longitudinal acceleration, and throttle opening.

[0056] The second module is used to determine whether the vehicle needs to shift gears based on the vehicle status information; if so, proceed to step S3; otherwise, maintain the current gear.

[0057] The third module is used to obtain the current gear ratio ξ1 and the target gear ratio ζ2, and compare the current gear ratio ξ1 with the target gear ratio ζ2; if ξ1-ξ2 is greater than the preset value P, then proceed to step S4; otherwise, proceed to step S5.

[0058] The fourth module is used to obtain the engine speed difference EVS and torque difference EVT between the current gear and the target gear, and directly control the engine to eliminate the engine speed difference EVS and torque difference EVT.

[0059] The fifth module is used to perform gear shifting operations on the transmission and execute corresponding hydraulic circuit controls.

[0060] The transmission shift control system of the present invention, corresponding to the shift control method described above, also has the advantages described above.

[0061] like Figure 1 As shown, this embodiment of the invention provides a transmission shifting system, including a vehicle speed signal acquisition unit (such as a vehicle speed sensor), a shift controller, a hydraulic circuit, and a switching unit (gear logic control solenoid valve) located in the hydraulic circuit. The vehicle speed sensor is installed on the transmission output shaft. The shift controller calculates the vehicle speed and acceleration values ​​based on the vehicle speed value and the rate of change of the accelerator pedal value, and then determines the transmission ratio between the current gear and the target gear. The shift controller is also connected to the engine controller via a CAN bus. This communication route enables the reading of the engine's current gear requirement speed and torque parameters. The shift controller issues the target gear speed requirement and torque limit requirement at the shift point. The engagement and disengagement of the shift clutch are achieved through the opening and closing of the hydraulic circuit and pressure. The two-position four-way solenoid valves 3#-4# implement the forward and reverse gear logic. When solenoid valve #3 is energized and solenoid valve #4 is de-energized, the gear is in forward gear; when solenoid valve #3 is de-energized and solenoid valve #4 is energized, the gear is in reverse gear. Two-position four-way solenoid valves #1 and #2 achieve different gear numbers through energization / de-energization logic combinations. Controlling the energization and de-energization of the solenoid valves at different times enables the oil charging / draining connection during gear shifting; proportional valves #5- #7 control the oil charging and draining pressure of each clutch drum. The transmission shifting system of this invention executes the shifting control method described above and also possesses the advantages described above.

[0062] The transmission shift control method of the present invention is applicable to the automatic shift control of engineering hydraulic mechanical transmissions. It utilizes an Electronic Control Unit (ECU) to switch to the target gear based on the collected vehicle speed and engine speed; controls the timing of oil filling and releasing of the wet clutch drum and the oil filling pressure according to different transmission ratios; or combines a hybrid control method that matches engine speed and torque to ensure the smoothness of gear shifting between different transmission ratios.

[0063] The present invention will be further described below with reference to a complete specific embodiment, such as... Figure 2 As shown:

[0064] 1) The shift controller continuously detects the shift mode lever signal. When the detected signal logic is forward automatic mode, proceed to step 2).

[0065] 2) The shift controller calculates the current vehicle speed S0 and the vehicle longitudinal acceleration based on the vehicle speed sensor installed on the transmission output shaft. At the same time, the shift controller communicates with the engine to read the throttle parameters and calculate the throttle opening.

[0066] 3) Based on the current vehicle speed S0, vehicle longitudinal acceleration, and throttle opening, query the preset shift parameter table to determine whether the vehicle status requires shifting; if shifting is not required, maintain the current gear and return to shift mode detection; if shifting is required, proceed to step 4); where the current gear status is calculated using vehicle speed, or vehicle speed and throttle opening.

[0067] 4) Read the target gear ratio parameter ζ2, compare the current gear ratio ξ1 with the target gear ratio ζ2; determine whether the gear ratio difference is greater than the preset parameter P, that is, whether the difference between ξ1 and ξ2 is greater than P. If so, proceed to step 5); if the difference between ξ1 and ξ2 is not greater than P, proceed directly to step 8).

[0068] 5) The shift controller communicates with the engine to obtain the current engine output speed ES0 and torque T0; and calculates the theoretical output torque T1 of the transmission output shaft based on the torque T0 and the current transmission ratio ξ1.

[0069] The target required torque T2 is calculated based on the theoretical output torque T1 of the current transmission output shaft and the target gear ratio ξ2. The target engine speed ES1 is calculated based on the current vehicle speed S0 and the target gear ratio ζ2.

[0070] The engine speed difference EVS and torque difference EVT between the current gear and the target gear are calculated, where EVS = ES1 - ES0 and EVT = T2 - T1.

[0071] 6) The shift controller communicates with the engine via the CAN bus. When shifting gears, the ECU obtains engine control, issues a request to take over engine speed and torque control, and issues the target speed or torque demand value. The engine responds to the request, and at this time the engine no longer responds to the accelerator pedal signal; this step eliminates the engine speed difference EVS and torque difference EVT.

[0072] 7) Determine whether the engine speed difference EVS and torque difference EVT have been eliminated; if not, continue to step 1); if the target range has been reached, proceed to step 8.

[0073] 8) Read the pressure rise curve of each gear and the oil filling and draining overlap time of each gear according to the calibrated oil pressure control parameter table;

[0074] 9) Determine whether to upshift based on the boost curve of each gear and the oil filling and releasing overlap time of each gear; if so, implement gear shifting according to the upshifting logic, control the oil filling pressure, control the oil releasing pressure, and control the overlap time of the current gear oil releasing proportional valve closing and the target gear proportional valve oil filling start, and output a PWM signal to the corresponding gear solenoid proportional valve; if downshifting, execute the downshifting logic, control the downshift oil releasing and oil filling overlap time, control the target gear clutch oil filling and boosting, and generate PWM output;

[0075] 10) Is the hydraulic pressure control complete? If not, repeat step 9); if yes, return to step 1.

[0076] The transmission shift control method of this invention determines the target gear based on the shift pattern, and then selects a specific control method to resolve shift shock based on whether the transmission ratio between the current gear and the target gear is greater than a preset value. If the speed ratio between the current gear and the target gear differs significantly, pressure control is performed based on turbine speed, vehicle speed, and gear clutch, while simultaneously combining a hybrid engine torque-speed matching method. The engine speed and torque are matched by vehicle speed and transmission ratio to achieve shifting. If the transmission ratio between the current gear and the target gear is not significantly different, single gear engagement timing and boost control are performed to reduce engine torque-speed matching time. Torque fluctuations are absorbed by moderate clutch slippage, thereby reducing shifting time. This also reduces power interruption and gear clutch friction time, thus reducing clutch wear and extending clutch life.

[0077] As shown in this disclosure and the claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. The terms "connected" or "linked" are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect.

[0078] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A transmission shift control method, characterized in that, Including the following steps: S1. Obtain vehicle status information, including vehicle speed S0, vehicle longitudinal acceleration, and throttle opening. S2. Determine whether the vehicle needs to shift gears based on the vehicle status information; If necessary, proceed to step S3; otherwise, maintain the current gear. S3. Obtain the current gear ratio ξ1 and the target gear ratio ζ2, and compare the current gear ratio ξ1 with the target gear ratio ζ2; if the difference between ξ1 and ξ2 is greater than the preset value P, proceed to step S4. Otherwise proceed to step S5; S4. Obtain the engine speed difference EVS and torque difference EVT between the current gear and the target gear, and directly control the engine to eliminate the engine speed difference EVS and torque difference EVT. S5. Perform a gear shift operation on the transmission; In step S5, the specific process of shifting gears is as follows: S51. Obtain the boost curve for each gear and the oil filling and draining overlap time; S52. Determine whether to upshift based on the boost curve of each gear and the oil filling and releasing overlap time; if upshifting is required, perform the upshift operation; if downshifting is required, perform the downshift operation. When upshifting, the upshifting logic is invoked, controlling the oil release and filling overlap time during upshifting, and controlling the oil filling and pressure increase of the target gear clutch to generate PWM output; when downshifting, the downshifting logic is invoked, controlling the oil release and filling overlap time during downshifting, and controlling the oil filling and pressure increase of the target gear clutch to generate PWM output.

2. The transmission shift control method according to claim 1, characterized in that, In step S1, the throttle opening is calculated by reading the engine's throttle parameters.

3. The transmission shift control method according to claim 1, characterized in that, In step S2, the vehicle speed S0, longitudinal acceleration, and throttle opening are used to query a preset shift parameter table to determine whether the vehicle needs to shift gears.

4. The transmission shift control method according to claim 1, 2, or 3, characterized in that, In step S4, the specific process of obtaining the engine speed difference EVS and torque difference EVT is as follows: Obtain the current engine output speed ES0 and torque T0, and obtain the theoretical output torque T1 of the transmission output shaft based on the torque T0 and the current gear ratio ξ1; The target output torque T2 is obtained based on the theoretical output torque T1 of the transmission output shaft and the target gear ratio ξ2. The target engine speed ES1 is calculated based on the current vehicle speed S0 and the target gear ratio ζ2. The speed difference EVS = ES1 - ES0 is obtained by comparing the engine target speed ES1 with the current engine output speed ES0. The torque difference EVT = T2 - T1 is obtained from the target output torque T2 and the theoretical output torque T1.

5. A transmission shift control system for executing the transmission shift control method as described in claims 1-4, characterized in that, include: The first module is used to acquire vehicle status information, which includes vehicle speed S0, vehicle longitudinal acceleration, and throttle opening. The second module is used to determine whether the vehicle needs to shift gears based on the vehicle status information. If necessary, proceed to step S3; otherwise, maintain the current gear. The third module is used to obtain the current gear ratio ξ1 and the target gear ratio ζ2, and compare the current gear ratio ξ1 with the target gear ratio ζ2; if ξ1-ξ2 is greater than the preset value P, then proceed to step S4; Otherwise, proceed to step S5; The fourth module is used to obtain the engine speed difference EVS and torque difference EVT between the current gear and the target gear, and directly control the engine to eliminate the engine speed difference EVS and torque difference EVT. The fifth module is used for shifting gears in the transmission.

6. A transmission shifting system for executing the transmission shifting control method as described in claims 1-4, characterized in that, It includes a vehicle speed signal acquisition unit, a shift controller, a hydraulic circuit, and a switching unit located in the hydraulic circuit; The vehicle speed signal acquisition unit is connected to the gear shift controller and is used to acquire the vehicle speed and send it to the gear shift controller; The shift controller is connected to the engine controller and is used to acquire engine status parameters; The shift controller is connected to each switching unit and is used to control the on / off state of the switching units according to vehicle speed and engine status parameters to achieve shifting.

7. The transmission shifting system according to claim 6, characterized in that, The vehicle speed signal acquisition unit is a vehicle speed sensor, which is installed on the output shaft of the transmission.

8. The transmission shifting system according to claim 6 or 7, characterized in that, The shift controller is connected to the engine controller via a CAN bus.

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