A shift method based on a double clutch automobile gearbox

Abstract

The application discloses a gear shifting method based on a double-clutch automobile gearbox, which is used for reducing the automobile gearbox from a three-gear working condition mode to a two-gear working condition mode, and comprises the following steps: after the automobile meets the gear shifting condition of reducing from the three-gear to the two-gear, a first input signal of an accelerator and a brake signal are acquired; when there is no first input signal and brake signal, two clutches are controlled to be switched to a half-joining state; when the two clutches are switched to the half-joining state, a second input signal of the accelerator is acquired again; a gear reduction strategy is determined according to the second input signal; and the two clutches are controlled to switch the working state according to the gear reduction strategy, so as to reduce the automobile gearbox from the three-gear working condition mode to the two-gear working condition mode. The application aims to provide better vehicle power stability and driving comfort, realize smooth gear shifting, reduce fuel consumption and improve vehicle performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gearbox, in particular to the technical field of gear shifting, and specifically to a gear shifting method based on a double clutch automobile gearbox. BACKGROUND

[0002] On an automobile, a clutch is a component directly connected with an engine in an automobile transmission system, which can ensure smooth starting of the automobile and smooth operation of the transmission system during gear shifting. The subjective feeling brought by different gear shifting strategies will be quite different during frequent gear shifting of the gearbox in daily use. The three-to-two gear shifting condition occurs very frequently in the use scene of the vehicle, such as deceleration at a red light, speed limit change on an urban road, driving off a viaduct, and driving off an expressway. Generally, the engine speed is increased to coordinate the disengagement and engagement of the clutch during the gear down operation of the double clutch transmission. At this time, the driver may be confused by the increase of the engine speed, and the engine speed is increased while the vehicle is decelerating, which also leads to the increase of fuel consumption and affects the comfort of the vehicle. SUMMARY

[0003] The main purpose of the present application is to provide a gear shifting method based on a double clutch automobile gearbox, which aims to provide better vehicle power stability and driving comfort, realize smooth gear shifting, reduce fuel consumption, and improve vehicle performance.

[0004] To achieve the above purpose, the present application provides a gear shifting method based on a double clutch automobile gearbox, which is used to reduce the automobile gearbox from a three-gear condition mode to a two-gear condition mode. The double clutch automobile gearbox includes two clutches, each of which includes multiple working states, and the multiple working states include a disengagement state, a half-engagement state, and an engagement state. The gear shifting method includes the following steps:

[0005] After the automobile meets the gear shifting condition of three-to-two, a first input signal of the accelerator and a brake signal are obtained;

[0006] When there is no first input signal and brake signal, the two clutches are controlled to switch to the half-engagement state;

[0007] When the two clutches are switched to the half-engagement state, a second input signal of the accelerator is obtained again;

[0008] According to the second input signal, a gear down strategy is determined;

[0009] According to the gear down strategy, the working states of the two clutches are controlled to switch to reduce the automobile gearbox from a three-gear condition mode to a two-gear condition mode.

[0010] Optionally, the double clutch gearbox comprises an input inner shaft and an input outer shaft, the input inner shaft is sleeved in the input outer shaft, the input inner shaft is drivingly connected to the three-gear working condition gear, and the input outer shaft is drivingly connected to the two-gear working condition gear.

[0011] The two clutches comprise a first clutch and a second clutch, the first clutch is connected with a first hydraulic pipe, the second clutch is connected with a second hydraulic pipe, the first clutch is drivingly connected to the input inner shaft, and the second clutch is drivingly connected to the input outer shaft.

[0012] Optionally, the step of controlling the two clutches to switch to the half-connection state when there is no first input signal and brake signal comprises:

[0013] controlling the oil amount of the hydraulic oil in the second hydraulic pipe to increase, so as to drive the second clutch to switch from the separated state to the half-connection state;

[0014] controlling the oil amount of the hydraulic oil in the first hydraulic pipe to decrease, so as to drive the first clutch to switch from the connection state to the half-connection state.

[0015] Optionally, after the step of controlling the two clutches to switch to the half-connection state when there is no first input signal and brake signal, the method further comprises:

[0016] controlling the engine speed not to increase.

[0017] Optionally, the step of determining the downshift strategy according to the second input signal comprises:

[0018] if there is no second input signal, controlling the automobile gearbox to directly enter the two-gear working condition mode;

[0019] if there is the second input signal, controlling the two clutches to switch the working state, so as to reduce the automobile gearbox from the three-gear working condition mode to the two-gear working condition mode.

[0020] Optionally, the two clutches comprise a first clutch and a second clutch.

[0021] if there is the second input signal, controlling the two clutches to switch the working state, so as to reduce the automobile gearbox from the three-gear working condition mode to the two-gear working condition mode, comprises:

[0022] obtaining a first actual engine speed;

[0023] determining a preset connection strategy of the first clutch and the second clutch according to the first actual engine speed;

[0024] controlling the first clutch and the second clutch to switch the connection state according to the preset connection strategy.

[0025] Optionally, the step of controlling the coupling states of the first clutch and the second clutch according to the preset coupling strategy comprises:

[0026] controlling the first clutch to switch from the half-coupling state to the coupling state so that the first clutch rotates synchronously with the engine;

[0027] reacquiring the second actual rotating speed of the engine;

[0028] controlling the first clutch and the second clutch to switch the coupling states according to the second actual rotating speed.

[0029] Optionally, the step of controlling the first clutch and the second clutch to switch the coupling states according to the second actual rotating speed comprises:

[0030] if the second actual rotating speed is greater than the second clutch rotating speed, the first clutch continues to rotate synchronously with the engine until the rotating speed of the engine is not greater than the second clutch rotating speed;

[0031] if the second actual rotating speed is not greater than the second clutch rotating speed, the second clutch switches from the half-coupling state to the coupling state, the engine rotates synchronously with the second clutch, and the first clutch switches from the coupling state to the half-coupling state.

[0032] Optionally, the step of determining the gear shifting condition of the automobile after the automobile meets the gear shifting condition of three-gear descending two ends comprises:

[0033] acquiring the actual driving speed of the automobile;

[0034] determining the gear shifting strategy of the transmission of the automobile according to the actual driving speed.

[0035] Optionally, the step of determining the gear shifting strategy of the transmission of the automobile according to the actual driving speed comprises:

[0036] if the actual driving speed is greater than a preset speed, the transmission of the automobile keeps the three-gear working condition mode;

[0037] if the actual driving speed is less than or equal to the preset speed, the transmission of the automobile is prepared to switch from the three-gear working condition mode to the two-gear working condition mode.

[0038] In the technical scheme of the present application, the engine speed is no longer requested to be raised during the shifting process, thereby reducing fuel consumption, making the automobile have more stable power, improving the driving comfort and the riding comfort, optimizing the clutch shifting strategy of the automobile gearbox, achieving smooth shifting, reducing fuel consumption, and improving the performance of the automobile. Specifically, the TCU first acquires the first input signal and the brake signal of the automobile, adjusts the two clutches to the half-joined state in advance when there is no first input signal and brake signal, and then acquires the second input signal and the brake signal. When there is no second input signal, the automobile directly enters the two-gear working mode. In this way, the automobile gearbox is reduced from the three-gear working mode to the two-gear working mode without raising the engine speed of the automobile, thereby reducing the fuel consumption of the automobile. When there is a second input signal, the two clutches are switched to the corresponding working state, the engine speed is inhibited from being raised, and the engine speed is prevented from being raised. In this way, the engine speed of the automobile is not raised when the automobile gearbox is reduced from the three-gear working mode to the two-gear working mode, thereby reducing the fuel consumption, making the automobile have more stable power, improving the driving comfort and the riding comfort. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical schemes in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on the drawings shown.

[0040] Figure 1 A flowchart of an embodiment of a shifting method of a double-clutch automobile gearbox provided by the present application is shown.

[0041] Figure 2 A structural diagram of an embodiment of an automobile gearbox provided by the present application is shown.

[0042] Figure 3 A real vehicle data graph when there is a second input signal in step S50 of the present application is shown.

[0043] Explanation of reference numerals:

[0044] Reference Name Reference Name 100 Automotive gearbox 3 Three forward gears 10 First clutch 4 Four forward gears 20 Second clutch 5 Five forward gears 30 Input inner shaft 6 Six forward gears 40 Input outer shaft 7 Seven forward gears 1 One forward gear R Reverse gear 2 Two forward gears

[0045] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort fall within the protection scope of the present application.

[0047] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0048] In addition, if the embodiments of the present application involve descriptions such as “first”, “second”, etc., the descriptions of “first”, “second”, etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first” and “second” can explicitly or implicitly include at least one of the features. In addition, the meaning of “and / or” appearing throughout the text includes three parallel solutions. Taking “A and / or B” as an example, it includes A solution, or B solution, or A and B solutions. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it. When the combination of technical solutions contradicts each other or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the protection scope of the present application.

[0049] On the car, the clutch is a component directly connected with the engine in the automobile transmission system, which can ensure the smooth starting of the automobile and ensure the smooth work of the transmission system during gear shifting. The gear position of the gearbox changes frequently during daily use, and the subjective feeling brought by different shifting strategies will be quite different. During the process of driving on urban roads, the three-to-two gear reduction condition appears very frequently in the vehicle use scene, such as red light deceleration, urban road speed limit change, off-ramp, and driving off the expressway. Generally, when the double clutch transmission performs the downshift operation, the engine speed will be raised to cooperate with the disengagement and engagement of the clutch. At this time, the driver may be confused by the rising engine speed during deceleration and downshift. At the same time, the rising engine speed will also cause the fuel consumption to rise, affecting the comfort of the vehicle.

[0050] In view of this, the present application provides a gear shifting method based on a double clutch automobile gearbox, Figure 1An embodiment of the flowchart of the shift method based on the double clutch automobile gearbox provided by the application can provide better vehicle power stability and driving comfort, realize smooth shift, reduce fuel consumption and improve vehicle performance. The shift method based on the double clutch automobile gearbox will be mainly described below in combination with specific drawings.

[0051] Please refer to Figure 1 The shift method is used to reduce the automobile gearbox 100 from the three-gear working condition mode to the two-gear working condition mode. The double clutch automobile gearbox includes two clutches, each of which includes multiple working states, and the multiple working states include the separation state, the half-connection state and the connection state. The shift method includes the following steps:

[0052] Step S10: After the automobile meets the shift condition of reducing from the three-gear to the two-gear, the first input signal of the accelerator and the brake signal are obtained.

[0053] Step S20: When there is no first input signal and brake signal, the two clutches are controlled to switch to the half-connection state.

[0054] Step S30: When the two clutches are switched to the half-connection state, the second input signal of the accelerator is obtained again.

[0055] Step S40: The shift strategy is determined according to the second input signal.

[0056] Step S50: The two clutches are controlled to switch the working state according to the shift strategy, so as to reduce the automobile gearbox 100 from the three-gear working condition mode to the two-gear working condition mode.

[0057] It should be noted that in the application, the control method is controlled based on the remote information control unit (i.e., TCU).

[0058] In the technical scheme, the engine speed is not requested to be increased during the shifting process, so as to reduce the fuel consumption, make the automobile have more stable power, improve the driving comfort and the riding comfort, optimize the clutch shifting strategy of the automobile gearbox 100, realize smooth shifting, reduce the fuel consumption and improve the performance of the automobile. Specifically, the TCU first acquires the first input signal and the brake signal of the automobile, adjusts the two clutches to the half combination state in advance when there is no first input signal and brake signal, the TCU again acquires the second input signal and the brake signal, and the automobile directly performs the two-gear working mode when there is no second input signal. In this way, the automobile gearbox 100 is completed from the three-gear working mode to the two-gear working mode without increasing the engine speed of the automobile, so as to reduce the fuel consumption of the automobile. When there is the second input signal, the two clutches are switched to the corresponding working state, the increase of the engine speed is inhibited, the increase of the engine speed is avoided, the automobile gearbox 100 is completed from the three-gear working mode to the two-gear working mode without increasing the engine speed of the automobile, so as to reduce the fuel consumption of the automobile. In this way, no matter whether there is the second input signal, when the automobile gearbox 100 is completed from the three-gear working mode to the two-gear working mode, the engine speed of the automobile is not increased, so as to reduce the fuel consumption, make the automobile have more stable power, improve the driving comfort and the riding comfort.

[0059] It should be noted that in the embodiment, the first input signal is the accelerator input, and the no first input signal is the no accelerator input. Similarly, the second input signal is the accelerator input, and the no second input signal is the no accelerator input.

[0060] It should be noted that the clutch has a clutch part and a matching part, and the specific structure of the clutch can be set according to the conventional setting in the field, which will not be described here.

[0061] Further, refer to Figure 2The double clutch gearbox comprises an input inner shaft 30 and an input outer shaft 40, the input inner shaft 30 is sleeved in the input outer shaft 40, the input inner shaft 30 is drivingly connected to a three-gear working condition gear, and the input outer shaft 40 is drivingly connected to a two-gear working condition gear; two clutches comprise a first clutch 10 and a second clutch 20, the first clutch 10 is connected with a first hydraulic pipe, the second clutch 20 is connected with a second hydraulic pipe, the first clutch 10 is drivingly connected to the input inner shaft 30, and the second clutch 20 is drivingly connected to the input outer shaft 40. In the embodiment, when the second clutch 20 is from the separation state to the combination state, the hydraulic oil in the second hydraulic pipe increases, so as to drive the clutch part and the matching part on the second clutch 20 to be combined, when the second clutch 20 is from the combination state to the separation state, the hydraulic oil in the second hydraulic pipe decreases, and the clutch part and the matching part on the second clutch 20 are separated, wherein the semi-combination state is that the clutch part and the matching part of the second clutch 20 are in a sliding film state; the separation state and the combination state of the first clutch 10 are the same as those of the second clutch 20, and reference can be made to the second clutch 20, which will not be described herein.

[0062] It should be noted that, in the shifting process, when the automobile gearbox 100 is in the three-gear working condition mode, the first clutch 10 is in the combination state, and the second clutch 20 is in the separation state.

[0063] In some embodiments, in step S10, the step after the automobile meets the three-gear-to-two-gear shifting condition further comprises the following steps:

[0064] Step S101, obtaining the actual driving speed of the automobile;

[0065] Step S102, determining the shifting strategy of the automobile gearbox 100 according to the actual driving speed.

[0066] Specifically, in the process of automobile driving, the gearbox needs to be adjusted to the corresponding gear according to the speed of the automobile, therefore, in the shifting process of the automobile gearbox 100, the TCU requests to obtain the actual driving speed of the automobile, judges the size of the actual driving speed and the preset speed (i.e. the shifting speed point of the three-gear working condition mode to the two-gear working condition mode), and determines whether the automobile needs to be decelerated according to the actual driving speed.

[0067] Further, in some embodiments, the step S102 further comprises the following steps:

[0068] Step S1021, if the actual driving speed is greater than the preset speed, the automobile gearbox 100 remains in the three-gear working condition mode;

[0069] Step S1022, if the actual driving speed is less than or equal to the preset vehicle speed, the automobile transmission 100 is ready to switch from the three-gear working condition mode to the two-gear working condition mode.

[0070] In some embodiments, the step S20 further comprises the following steps:

[0071] Step S201, control the oil amount of the hydraulic oil in the second hydraulic pipe to increase, drive the second clutch 20 from the disengaged state to the half-engaged state;

[0072] Step S202, control the oil amount of the hydraulic oil in the first hydraulic pipe to decrease, drive the first clutch 10 from the engaged state to the half-engaged state.

[0073] Specifically, when the step S20 is performed, the TCU sends a signal to control the second hydraulic pipe, so that the oil amount of the hydraulic oil in the second hydraulic pipe increases, and the engaging part and the cooperating part of the second clutch 20 are engaged. In the process of engaging the second clutch 20, the torque of the second clutch 20 rises from the Ramp point to the TP point. When the torque reaches the TP point, the oil amount input into the second hydraulic pipe is stopped. At this time, the second clutch is in the half-engaged state, and the conversion of the second clutch 20 from the disengaged state to the half-engaged state is completed. In this process, the TCU simultaneously sends a signal to control the first hydraulic pipe, so that the oil amount of the hydraulic oil in the first hydraulic pipe decreases, and the engaging part and the cooperating part of the first clutch 10 are disengaged. In the process of disengaging the first clutch 10, the torque of the first clutch 10 begins to decrease. When it decreases to the TP point, the oil amount of the first hydraulic pipe stops decreasing. At this time, the first clutch 10 is in the half-engaged state, and the conversion of the first clutch 10 from the disengaged state to the half-engaged state is completed.

[0074] In some embodiments, after the step S20, before the step S30, the following step is further included:

[0075] Step S210, control the engine speed not to increase.

[0076] Specifically, generally, when the double-clutch transmission performs the downshift operation, in order to disengage and engage the clutches, the TCU requests the engine speed to increase, and accelerates the shifting process. Therefore, in this embodiment, when the automobile transmission is switched from the three-gear working condition mode to the two-gear working condition mode, the TCU needs to request to control the engine speed not to increase, so as to avoid the situation that the fuel consumption increases due to the automatic increase of the engine speed.

[0077] In some embodiments, in step S30, the reason for obtaining the second input signal again is that during the driving of the vehicle, the throttle input and brake input are not only controlled by the TCU, but also affected by the driver, so even if the TCU requests that the engine speed is not to be increased, when the driver steps on the throttle during driving, the engine speed will be increased, so in this embodiment, the state of the first clutch 10 and the second clutch 20 is controlled according to whether there is a throttle signal, so as to complete the shift of the vehicle transmission 100 from the three-gear working condition mode to the two-gear working condition mode without increasing the engine speed.

[0078] In some embodiments, the step S40 further comprises the following steps:

[0079] Step S401, if there is no second input signal, control the vehicle transmission 100 to directly enter the two-gear working condition mode;

[0080] Step S402, if there is the second input signal, control the two clutches to switch the working state to shift the vehicle transmission 100 from the three-gear working condition mode to the two-gear working condition mode.

[0081] Specifically, during driving, when the driver does not step on the throttle of the vehicle for acceleration during downshift, the first clutch 10 and the second clutch 20 remain in the half-coupling state, and the vehicle transmission 100 directly enters the two-gear Creep working condition and travels at a constant speed according to the two-gear speed; during driving, when the driver steps on the throttle of the vehicle for acceleration during downshift, the first clutch 10 and the second clutch 20 cooperate to suppress the increase of the engine speed, so that the vehicle is shifted from the three-gear working condition mode to the two-gear working condition mode without increasing the engine speed.

[0082] Specifically, the step S402 further comprises the following steps:

[0083] Step S420, obtaining the first actual engine speed;

[0084] Step S421, determining the preset coupling strategy of the first clutch 10 and the second clutch 20 according to the first actual engine speed;

[0085] Step S422, controlling the first clutch 10 and the second clutch 20 to switch the coupling state according to the preset coupling strategy.

[0086] Specifically, in the actual control process, the TCU first obtains the actual speed of the engine. When the driver steps on the accelerator, the speed of the engine will increase. Therefore, when the first actual speed is greater than the preset speed (the speed of the engine when the shifting speed point of the three-gear working condition mode to the two-gear working condition mode of the automobile is reached), it is determined that the automobile transmission 100 is controlled according to step S402.

[0087] Further, please refer to Figure 3 In some embodiments, the step S422 further comprises the following steps:

[0088] Step S4221, controlling the first clutch 10 to switch from the half-engaged state to the engaged state, so that the first clutch 10 rotates synchronously with the engine;

[0089] Step S4222, obtaining the second actual speed of the engine again;

[0090] Step S4223, controlling the first clutch 10 and the second clutch 20 to switch the engaged state according to the second actual speed.

[0091] Further, the step S4223 further comprises the following steps:

[0092] Step S42231, if the second actual speed is greater than the speed of the second clutch 20, the first clutch 10 continues to rotate synchronously with the engine until the speed of the engine is not greater than the speed of the second clutch 20;

[0093] Step S42232, if the second actual speed is not greater than the speed of the second clutch 20, the second clutch 20 switches from the half-engaged state to the engaged state, the engine rotates synchronously with the second clutch 20, and the first clutch 10 switches from the engaged state to the half-engaged state.

[0094] Specifically, in the actual driving process, when the engine speed increases, the hydraulic oil in the first hydraulic pipe increases, driving the clutch part and the matching part of the first clutch 10 to combine, that is, the first clutch 10 is converted from the semi-coupling state to the coupling state, at this time the torque of the first clutch 10 increases, the first clutch 10 rotates synchronously with the engine, thereby inhibiting the increase of the engine speed, the TCU sends a signal to obtain the second actual speed of the engine, when the second actual speed is still greater than the speed of the first clutch 10, the first clutch 10 continues to rotate synchronously with the engine, reducing the speed of the engine until the speed of the engine is the same as the speed of the first clutch 10; when the second actual speed is the same as the speed of the first clutch 10, the TCU sends a signal to control the hydraulic oil in the first hydraulic pipe to decrease, so that the first clutch 10 is converted from the coupling state to the semi-coupling state, at the same time, the TCU sends a signal to control the hydraulic oil in the second hydraulic pipe to increase, so that the second clutch 20 is converted from the semi-coupling state to the coupling state, so that the second clutch 20 rotates synchronously with the engine, completing the conversion of the automobile gearbox 100 from the three-gear working condition mode to the two-gear working condition mode, in this way, even if the driver steps on the accelerator during the shifting process, the engine of the automobile will not speed up, thereby realizing the reduction of fuel consumption, making the automobile have more stable power, improving the driving comfort and the riding comfort.

[0095] The above description is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, any equivalent structural transformation made under the concept of the present application, using the content of the present application specification and drawings, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A shifting method based on a dual-clutch automotive transmission, used to downshift the automotive transmission from a third-gear operating mode to a second-gear operating mode, wherein the dual-clutch automotive transmission includes two clutches, each clutch having multiple operating states, including a disengaged state, a partially engaged state, and an engaged state, characterized in that... The gear shifting method includes the following steps: After the car meets the shift conditions of downshifting from third gear to second gear, the first input signal of the accelerator and the brake signal are obtained; When there is no first input signal and brake signal, control both clutches to switch to a semi-engaged state; When both clutches are switched to a semi-engaged state, the second input signal of the throttle is acquired again. The downshift strategy is determined based on the second input signal; The downshifting strategy controls the switching of the two clutches to reduce the vehicle's transmission from third gear mode to second gear mode. The step of determining the downshift strategy based on the second input signal includes: If there is no second input signal, the vehicle's transmission will directly enter the second gear mode. If the second input signal is received, control the two clutches to switch their working states so as to downgrade the vehicle transmission from the third gear mode to the second gear mode. The two clutches include a first clutch and a second clutch; If the second input signal is received, controlling the two clutches to switch their operating states to downshift the vehicle transmission from third gear mode to second gear mode includes: Obtain the engine's first actual speed; Based on the first actual engine speed, a preset engagement strategy for the first clutch and the second clutch is determined; According to the preset engagement strategy, the first clutch and the second clutch are controlled to switch engagement states. The step of controlling the engagement state of the first clutch and the second clutch according to the preset engagement strategy includes: Control the first clutch to switch from the semi-engaged state to the engaged state so that the first clutch rotates synchronously with the engine; The second actual speed of the engine is obtained again; The engagement state of the first clutch and the second clutch is switched according to the second actual speed. The step of controlling the switching engagement state of the first clutch and the second clutch according to the second actual speed includes: If the second actual speed is greater than the second clutch speed, the first clutch continues to rotate synchronously with the engine until the engine speed is not greater than the second clutch speed. If the second actual speed is not greater than the second clutch speed, the second clutch switches from the semi-engaged state to the engaged state, the engine rotates synchronously with the second clutch, and the first clutch switches from the engaged state to the semi-engaged state.

2. The gear shifting method as described in claim 1, characterized in that, The dual-clutch transmission includes an inner input shaft and an outer input shaft. The inner input shaft is sleeved inside the outer input shaft. The inner input shaft is driven to a third-speed gear, and the outer input shaft is driven to a second-speed gear. The two clutches include a first clutch and a second clutch. The first clutch is connected to a first hydraulic pipe, and the second clutch is connected to a second hydraulic pipe. The first clutch is driven to the inner input shaft, and the second clutch is driven to the outer input shaft.

3. The shifting method as described in claim 2, characterized in that, When there is no first input signal and no brake signal, controlling both clutches to switch to a semi-engaged state includes: The hydraulic oil in the second hydraulic pipe is increased to drive the second clutch from the disengaged state to the semi-engaged state; The amount of hydraulic oil in the first hydraulic pipe is reduced, driving the first clutch from the engaged state to the semi-engaged state.

4. The gear shifting method as described in claim 1, characterized in that, After the step of controlling both clutches to switch to a semi-engaged state when there is no first input signal and brake signal, the method further includes: Control the engine speed to prevent it from increasing.

5. The gear shifting method as described in claim 1, characterized in that, The steps after the car meets the shifting condition of downshifting from third to second gear include: To obtain the actual speed of the car; The vehicle's transmission shifting strategy is determined based on the actual driving speed.

6. The gear shifting method as described in claim 5, characterized in that, Determining the transmission shift strategy based on the actual driving speed includes: If the actual driving speed is greater than the preset vehicle speed, the vehicle transmission will maintain the three-speed operating mode. If the actual driving speed is less than or equal to the preset speed, the vehicle transmission prepares to switch from the third gear mode to the second gear mode.

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