Control method, device and vehicle for a mechanical hydraulic continuously variable transmission

Abstract

The application provides a control method and device of a mechanical hydraulic stepless gearbox and a vehicle. The control method comprises the following steps: receiving a working condition signal of the vehicle; judging a load working condition based on the working condition signal when the working condition signal meets a power downshift condition; controlling the gearbox to downshift according to a preset downshift mode when the load working condition meets a first preset load condition; and in the preset downshift mode, the gearbox is controlled to synchronously perform torque exchange of a clutch and transmission ratio adjustment of a hydraulic system. The control method can monitor and identify the load working condition in real time when the gearbox downshifts, and can adaptively select different downshift modes according to different external loads. When the gearbox downshifts under a large load, the fast downshift mode of adjusting the hydraulic transmission ratio and simultaneously performing the torque exchange of the clutch is adopted, so that the friction work of the clutch is effectively reduced, the downshift time is shortened, the excessive wear of the clutch is effectively prevented, and the service life of the clutch is prolonged.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to a control method for a mechanical-hydraulic continuously variable transmission (CVT), a control device for a mechanical-hydraulic CVT, and a vehicle. Background Technology

[0002] The existing powered downshift control method involves first controlling the speed phase (matching the clutch speeds) when the transmission is detected to be powered downshifting. This means first using engine speed to adjust the clutch speed difference of the target gear to a positive value to achieve positive power transmission, followed by clutch torque exchange. During this downshifting process, if there are large changes in external load during speed phase control, it can cause the disengaged clutch to slip, thus accelerating clutch wear. Summary of the Invention

[0003] The objective of this invention is to at least solve the problem of the short lifespan of existing transmissions. This objective is achieved through the following technical solution:

[0004] The first aspect of this invention provides a control method for a mechanical-hydraulic continuously variable transmission, comprising the following steps:

[0005] Receive the vehicle's first operating condition signal;

[0006] Based on the operating condition signal, the load condition is determined according to the first operating condition signal, which satisfies the power downshift condition.

[0007] If the load condition meets the first preset load condition, control the transmission to downshift according to the preset downshift mode;

[0008] In the preset downshift mode, the transmission is controlled to simultaneously perform torque exchange of the clutch system and transmission ratio adjustment of the hydraulic system.

[0009] The control method of the mechanical hydraulic continuously variable transmission proposed in this invention monitors and intelligently identifies the load condition in real time when there is power downshifting, and adaptively selects different power downshifting control methods according to different external loads. When actively downshifting under heavy load, a rapid downshifting method is adopted to adjust the hydraulic transmission ratio and exchange clutch torque at the same time, which can effectively reduce clutch friction work, shorten downshifting time, effectively prevent excessive clutch wear, and improve clutch service life.

[0010] In addition, the control method for the mechanical-hydraulic continuously variable transmission according to the present invention may also have the following additional technical features:

[0011] In some embodiments of the present invention, the first operating condition signal includes:

[0012] The required speed, actual speed, accelerator pedal change rate, load torque, and engine load rate of the vehicle.

[0013] In some embodiments of the present invention, satisfying the first preset load condition according to the load condition includes:

[0014] The actual vehicle speed is less than the sum of the required vehicle speed and the preset vehicle speed threshold, the accelerator pedal change rate is less than the preset change rate, the load torque is higher than the preset load torque, and the engine load rate is higher than the preset load rate.

[0015] In some embodiments of the present invention, the clutch system includes a plurality of clutches corresponding one-to-one with the gear positions of the transmission, and the step of controlling the transmission to downshift according to a preset downshift mode based on the load condition satisfying the first preset load condition further includes the following step:

[0016] Control the transmission to reduce the torque capacity of the clutch corresponding to the current gear to the current actual transmitted torque.

[0017] In some embodiments of the present invention, the control method further includes the step of:

[0018] If the load condition meets the second preset load condition, the transmission is controlled to downshift in a normal mode.

[0019] In the conventional mode, the transmission is controlled to first adjust the transmission ratio of the hydraulic system, and then to exchange torque in the clutch system.

[0020] In some embodiments of the present invention, the step of controlling the gearbox to first adjust the transmission ratio of the hydraulic system is further included before the following step:

[0021] Control the transmission to reduce the torque capacity of the clutch corresponding to the current gear to the current actual transmitted torque.

[0022] In some embodiments of the present invention, the control method further includes the step of:

[0023] Receive the vehicle's second operating condition signal;

[0024] In the preset downshift mode, the friction work and cumulative friction work of the clutch system are calculated in real time based on the second operating condition signal;

[0025] Based on the friction work being greater than a preset safety threshold and / or the cumulative friction work being greater than a preset cumulative safety threshold, the transmission is controlled to disengage all clutches in the clutch system.

[0026] In some embodiments of the present invention, the second operating condition signal includes real-time gear pressure, the speed difference between the driving and driven ends of the clutch corresponding to the current gear, and the speed difference between the driving and driven ends of the clutch corresponding to the target gear.

[0027] A second aspect of the present invention provides a control device for a mechanical-hydraulic continuously variable transmission (CVT), used to implement the control method for the mechanical-hydraulic CVT proposed in the first aspect of the present invention, the control device comprising:

[0028] Acquisition unit, used to acquire vehicle operating condition signals;

[0029] The judgment unit is used to judge the load condition based on the operating condition signal, and to judge whether the first preset load condition is met based on the load condition.

[0030] The control unit is used to control the transmission to downshift according to a preset downshifting mode based on the judgment result of the judgment unit.

[0031] In the preset downshift mode, the transmission is controlled to simultaneously perform torque exchange in the clutch system and adjust the transmission ratio in the hydraulic system.

[0032] The control device for the mechanical-hydraulic continuously variable transmission (CVT) proposed in the second aspect of the present invention has the same beneficial effects as the control method for the mechanical-hydraulic CVT proposed in the first aspect of the present invention, and will not be described again here.

[0033] A third aspect of the invention provides a vehicle including a control device for a mechanical-hydraulic continuously variable transmission as described in the second aspect of the invention. Attached Figure Description

[0034] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0035] In the attached diagram:

[0036] Figure 1 A schematic flowchart of a control method for a mechanical-hydraulic continuously variable transmission according to an embodiment of the present invention is shown.

[0037] Figure 2 A schematic diagram illustrating the specific flow of the control method for a mechanical-hydraulic continuously variable transmission according to an embodiment of the present invention is shown.

[0038] Figure 3 A schematic diagram of the control device for a mechanical-hydraulic continuously variable transmission according to an embodiment of the present invention is shown.

[0039] Figure label:

[0040] 10: Control device; 11: Acquisition unit; 12: Judgment unit; 13: Control unit. Detailed Implementation

[0041] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0042] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0043] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0044] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0045] like Figure 1 As shown, the first aspect of the present invention proposes a control method for a mechanical-hydraulic continuously variable transmission, comprising the following steps:

[0046] S001: Receive vehicle operating condition signals;

[0047] S002: Based on the working condition signal, determine the load condition according to the working condition signal that meets the conditions for power downshifting;

[0048] S003: Based on the load conditions meeting the first preset load condition, control the transmission to downshift according to the preset downshift mode;

[0049] In the preset downshift mode, the transmission is controlled to simultaneously perform torque exchange of the clutch system and transmission ratio adjustment of the hydraulic system.

[0050] Understandably, vehicle operating condition signals are collected by onboard sensors, including vehicle speed, load, load ratio, and accelerator pedal change rate. Powered downshifting refers to downshifting while the vehicle is in motion and has power. The vehicle's control system, upon receiving these signals from the onboard sensors, can determine whether a powered downshift is in progress based on vehicle speed and transmission gear. If so, it further assesses the vehicle's load. For example, large speed fluctuations and high engine load indicate a heavy load. To prevent excessive wear on the transmission's clutch system during downshifting due to heavy load, the transmission is pre-controlled to operate in a preset downshift mode. This involves simultaneously adjusting the torque exchange of the clutch system and the transmission ratio of the hydraulic system. This prevents clutch slippage caused by increased load during high-load powered downshifting, thus reducing clutch friction and effectively shortening downshift time.

[0051] The control method for a mechanical-hydraulic continuously variable transmission (CVT) proposed in this invention monitors and intelligently identifies load conditions in real time during powered downshifting. Based on different external loads, it adaptively selects different powered downshifting control methods. During active downshifting under heavy load, a rapid downshifting method is employed that adjusts the hydraulic transmission ratio while simultaneously exchanging clutch torque. This effectively reduces clutch friction work, shortens downshifting time, and effectively prevents excessive clutch wear, thereby extending clutch lifespan. The control method of this invention is applicable to mechanical-hydraulic CVTs.

[0052] In some embodiments of the present invention, the operating condition signal includes:

[0053] The required vehicle speed, actual vehicle speed, accelerator pedal change rate, load torque, and engine load rate.

[0054] Specifically, the required vehicle speed is calculated and determined based on vehicle operating conditions and driver operation; the actual vehicle speed is obtained from the onboard speed sensor; the accelerator pedal change rate is obtained from the accelerator position sensor; the load torque is collected and calculated from the engine integrated sensor; and the engine load rate is calculated based on the real-time engine operating conditions collected by various engine sensors. Operating condition signals may also include other vehicle parameter signals.

[0055] In some embodiments of the present invention, satisfying a first preset load condition based on the load condition includes:

[0056] The actual vehicle speed is less than the sum of the required vehicle speed and the preset vehicle speed threshold; the accelerator pedal change rate is less than the preset change rate; the load torque is higher than the preset load torque; and the engine load rate is higher than the preset load rate.

[0057] During heavy load active downshifting, due to the large external load during downshifting, the actual vehicle speed deviates significantly from the required speed, the load torque exceeds the preset load torque, and the engine load rate is also higher than the preset load rate. Furthermore, the accelerator pedal change rate is relatively small during driver-initiated downshifting. Therefore, a first preset load condition is established. If the load condition meets this condition, the vehicle is determined to be in a heavy load active downshifting condition. At this point, the control device adaptively selects a rapid downshifting control method, adjusting the hydraulic system transmission ratio while simultaneously exchanging clutch torque. This control method prevents clutch slippage during heavy load downshifting if the load increases during the speed phase, thus avoiding high clutch friction work.

[0058] In some embodiments of the present invention, the clutch system includes a plurality of clutches corresponding one-to-one with the gears of the transmission. Before the step of controlling the transmission to downshift according to a preset downshift mode based on a first preset load condition, the system further includes the following step:

[0059] Control the transmission to reduce the torque capacity of the clutch corresponding to the current gear to the actual torque being transmitted.

[0060] When downshifting, the torque capacity of the clutch corresponding to the previous gear, which is the clutch that is about to disengage, is reduced first. This can suppress the excessive increase in engine speed and prevent clutch slippage when the load increases during the clutch speed matching phase, thereby improving clutch life.

[0061] In some embodiments of the present invention, the control method further includes the step of:

[0062] If the second preset load condition is met under load conditions, the transmission is controlled to downshift in the normal mode.

[0063] In the normal mode, the transmission first adjusts the transmission ratio of the hydraulic system, and then the torque exchange of the clutch system is performed.

[0064] The second preset load condition is defined as follows: the current actual vehicle speed can stably follow the required vehicle speed; the load torque is lower than the preset load torque; the engine load rate is lower than the preset load rate; and the accelerator pedal change rate is higher than the preset change rate. This second load condition differs from the first load condition. Under normal vehicle operating conditions, the vehicle speed is stable, the load torque is low, the engine load rate is also low, and a high accelerator pedal change rate indicates the vehicle is in a high-throttle downshifting acceleration state. If the second preset load condition is met, it can be determined that the vehicle is currently in a low-load, high-throttle downshifting acceleration state. The controller adaptively selects a conventional downshifting control method, and the control device controls the transmission to downshift according to the conventional downshifting mode. First, the torque capacity (pressure) of the clutch corresponding to the current gear is reduced to and maintained at the current actual transmitted torque. Then, the hydraulic system is controlled to adjust the transmission ratio until the speed difference between the two ends of the engaged clutch is within an acceptable range before the clutch torque exchange occurs. After the exchange, the clutch corresponding to the target gear is engaged. This control method can maintain a low downshifting impact during low-load downshifting, improving the driving experience.

[0065] In some embodiments of the present invention, the step of controlling the gearbox to first adjust the transmission ratio of the hydraulic system is further included:

[0066] Control the transmission to reduce the torque capacity of the clutch corresponding to the current gear to the actual torque being transmitted.

[0067] When downshifting to accelerate under light load and heavy throttle, reducing the torque capacity of the clutch corresponding to the current gear can suppress excessive increase in engine speed, prevent clutch slippage when the load increases during the speed phase, and thus improve clutch life.

[0068] In some embodiments of the present invention, the control method further includes the step of:

[0069] During downshifting, the frictional work and cumulative frictional work of the clutch system are calculated in real time based on the operating condition signals;

[0070] Based on the friction work exceeding a preset safety threshold and / or the cumulative friction work exceeding a preset cumulative safety threshold, control the disengagement of all clutches in the gearbox clutch system.

[0071] Understandably, the current clutch-transmitted torque can be calculated based on the actual pressure detected by the pressure sensor at the clutch, and the friction work can be calculated using the torque and the speed difference between the clutch and the clutch. During downshifting, the actual gear pressure and the speed difference between the driving and driven ends of the disengaging and engaging clutches are monitored in real time, and the friction work of the clutch during downshifting is calculated in real time and integrated to obtain the cumulative friction work. If the friction work is detected to exceed the safety threshold, all gear clutches are quickly disengaged to protect the clutches.

[0072] In some embodiments of the present invention, the operating condition signals include real-time gear pressure, the speed difference between the driving and driven ends of the clutch corresponding to the current gear, and the speed difference between the driving and driven ends of the clutch corresponding to the target gear. The real-time gear pressure is obtained from a pressure sensor at the clutch, and the speed difference is obtained from a speed sensor.

[0073] like Figure 3 As shown, a second aspect of the present invention provides a control device for a mechanical-hydraulic continuously variable transmission (CVT) for implementing the control method for the mechanical-hydraulic CVT proposed in the first aspect of the present invention. The control device 10 includes:

[0074] Acquisition unit 11 is used to acquire the vehicle's operating condition signals;

[0075] The judgment unit 12 is used to judge the load condition based on the working condition signal, and to judge whether the first preset load condition is met based on the load condition.

[0076] The control unit 13 is used to control the transmission to downshift according to the preset downshift mode based on the judgment result of the judgment unit 12.

[0077] In the preset downshift mode, the transmission is controlled to simultaneously perform torque exchange in the clutch system and adjust the transmission ratio in the hydraulic system.

[0078] The control device 10 for the mechanical-hydraulic continuously variable transmission (CVT) proposed in the second aspect of the present invention has the same beneficial effects as the control method for the mechanical-hydraulic CVT proposed in the first aspect of the present invention. It can monitor and intelligently identify the load condition in real time when there is power downshifting, and adaptively select different power downshifting control methods according to different external loads. The specific control flow is as follows:

[0079] like Figure 2As shown, the system first monitors key parameters such as required vehicle speed, actual vehicle speed, accelerator pedal change rate, load torque, and engine load rate in real time to intelligently detect the load conditions during downshifting. If the conditions for power downshifting are met, the system intelligently identifies the load conditions during downshifting and adaptively selects either a conventional downshifting mode or a preset downshifting mode based on the load conditions. If a low-load, high-throttle downshifting acceleration condition is detected, the conventional downshifting method is used. First, the torque capacity (pressure) of the clutch corresponding to the current gear is reduced to and maintained at the current actual transmitted torque. Then, the hydraulic system transmission ratio is adjusted until the speed difference between the two ends of the clutch corresponding to the target gear is within an acceptable range. After the exchange, the clutch torque is exchanged, and then the clutch is engaged. This reduces downshift shock and improves the driving experience. If a high-load active downshifting condition is detected, a preset downshifting mode is used. First, the torque capacity of the clutch corresponding to the current gear is reduced to the current actual transmitted torque. Then, while adjusting the hydraulic system transmission ratio, the clutch torque is exchanged to reduce downshifting time and clutch friction work.

[0080] A third aspect of the invention provides a vehicle including a control device for a mechanical-hydraulic continuously variable transmission as described in the second aspect of the invention.

[0081] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A control method for a mechanical-hydraulic continuously variable transmission, characterized in that, Includes the following steps: Receive the vehicle's first operating condition signal; Based on the operating condition signal, the load condition is determined according to the first operating condition signal, which satisfies the power downshift condition. Based on the load condition meeting the first preset load condition, it is determined that the vehicle is in a high-load active downshifting condition, and the transmission is controlled to downshift according to the preset downshifting mode. In the preset downshift mode, the transmission is controlled to simultaneously perform torque exchange of the clutch system and transmission ratio adjustment of the hydraulic system. The first operating condition signal includes: The required speed, actual speed, accelerator pedal change rate, load torque, and engine load rate of the vehicle; The condition of satisfying the first preset load condition according to the load condition includes: The actual vehicle speed is less than the sum of the required vehicle speed and the preset vehicle speed threshold, the accelerator pedal change rate is less than the preset change rate, the load torque is higher than the preset load torque, and the engine load rate is higher than the preset load rate; The control method further includes the following steps: Based on the load condition meeting the second preset load condition, it is determined that the vehicle is in a low-load, high-throttle downshifting acceleration condition, and the transmission is controlled to downshift in a normal mode. In the conventional mode, the transmission is controlled to first adjust the transmission ratio of the hydraulic system, and then the torque exchange of the clutch system is performed. The second preset load condition is that the actual vehicle speed stably follows the required vehicle speed, the load torque is lower than the preset load torque, the engine load rate is lower than the preset load rate, and the accelerator pedal change rate is higher than the preset change rate.

2. The control method for a mechanical-hydraulic continuously variable transmission according to claim 1, characterized in that, The clutch system includes multiple clutches that correspond one-to-one with the gears of the transmission. Before the step of controlling the transmission to downshift according to a preset downshift mode based on the first preset load condition, the system further includes the following step: Control the transmission to reduce the torque capacity of the clutch corresponding to the current gear to the current actual transmitted torque.

3. The control method for a mechanical-hydraulic continuously variable transmission according to claim 1, characterized in that, Before the step of controlling the gearbox to adjust the transmission ratio of the hydraulic system, the following step is included: Control the transmission to reduce the torque capacity of the clutch corresponding to the current gear to the current actual transmitted torque.

4. The control method for a mechanical-hydraulic continuously variable transmission according to claim 1, characterized in that, The control method further includes the following steps: Receive the vehicle's second operating condition signal; In the preset downshift mode, the friction work and cumulative friction work of the clutch system are calculated in real time based on the second operating condition signal; Based on the friction work being greater than a preset safety threshold and / or the cumulative friction work being greater than a preset cumulative safety threshold, the transmission is controlled to disengage all clutches in the clutch system.

5. The control method for a mechanical-hydraulic continuously variable transmission according to claim 4, characterized in that, The second operating condition signal includes real-time gear pressure, the speed difference between the driving and driven ends of the clutch corresponding to the current gear, and the speed difference between the driving and driven ends of the clutch corresponding to the target gear.

6. A control device for a gearbox, characterized in that, A control device for implementing the mechanical-hydraulic continuously variable transmission according to any one of claims 1 to 5, the control device comprising: Acquisition unit, used to acquire vehicle operating condition signals; The judgment unit is used to judge the load condition based on the operating condition signal, and to judge whether the load condition meets the first preset load condition. The control unit is used to control the transmission to downshift according to a preset downshifting mode based on the judgment result of the judgment unit. In the preset downshift mode, the transmission is controlled to simultaneously perform torque exchange in the clutch system and adjust the transmission ratio in the hydraulic system.

7. A vehicle, characterized in that, Includes the control device for the mechanical-hydraulic continuously variable transmission as described in claim 6.

Images