Small-horsepower hcvt active speed reduction and pre-charge oil coordinated commutation method and system

Abstract

The present application relates to the field of agricultural machinery transmission technology, and discloses a small-horsepower HCVT active speed reduction and pre-oil-filling coordinated reversing method and system. The method collects the traveling speed, the output shaft speed, the hydraulic oil temperature, the oil pressure and the proportional valve feedback current in real time. When the reversing command reaches the preset time window and the speed and the oil temperature meet the conditions, the vehicle speed is actively reduced by adjusting the swash plate inclination angle through the variable pump, and the forward gear clutch pressure is kept at the half-linkage pressure threshold value. Then, the forward gear clutch is simultaneously depressurized, and the pre-oil-filling high-pressure pulse is input to the reverse gear clutch. The pre-oil-filling pulse width is determined based on the oil temperature, the flow rate, the leakage amount and the wear state. The pressure outer ring and the current inner ring are used to close loop and keep the reverse gear clutch pressure at the engagement critical threshold value. When the output shaft speed approaches zero, the system working pressure is raised to complete the reversing. The present application effectively reduces the reversing impact and the friction plate sliding wear, and is suitable for the low-speed high-frequency reversing working condition of small-horsepower tracked tractors.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery transmission technology, and in particular to a method and system for coordinated reversing of low-horsepower HCVT active speed reduction and pre-filled oil. Background Technology

[0002] With the increasing precision of modern agriculture, small tracked tractors are widely used in loading and yard management. In these scenarios, tractors often need to frequently switch between forward and reverse, such as using the front loader to shovel soil or turning around in narrow plots. In these operations, the tractor's normal operating speed is typically no higher than […]. However, the reversing frequency is extremely high. This low-speed, high-frequency operating condition causes the transmission system to frequently switch between forward and reverse directions; at the same time, the rated flow rate of the main oil circuit in the hydraulic system of small-horsepower engines is usually no higher than... Electro-hydraulic reversing technology, which cannot directly handle high-flow rates, is not feasible. Existing tractor transmission systems mostly employ purely mechanical shifting or simple hydrostatic drives. Traditional mechanical reversing requires depressing the main clutch to cut off power before forcibly engaging reverse gear, a cumbersome process that generates significant mechanical shock, leading to gear grinding and severe wear on the clutch friction plates. Traditional dual-clutch reversing systems, relying solely on simple solenoid valves for on / off control, are prone to gearbox stalling or severe jerking during sudden reversing at high speeds due to excessive speed differences, resulting in a poor driver experience and difficulty in ensuring the lifespan of core transmission components.

[0003] Therefore, it is necessary to provide a new method and system for active speed reduction and pre-charged oil coordinated commutation of low-horsepower HCVT to solve the above-mentioned technical problems. Summary of the Invention

[0004] The main objective of this invention is to provide a method and system for coordinated reversing of low-horsepower HCVT with active deceleration and pre-filling oil, aiming to solve the problem that existing vehicle reversing methods cannot guarantee smoothness, operational stability, and component life during frequent reversing.

[0005] To achieve the above objectives, this invention proposes a method for coordinated reversing of a low-horsepower HCVT active deceleration and pre-charge oil, used to control the reversing of a low-horsepower tracked tractor. The method includes the following steps: Real-time acquisition of vehicle status parameters of low-horsepower tracked tractors, including: vehicle status parameters include the travel speed signal of the low-horsepower tracked tractor, the speed signal of the output shaft in the transmission system, and the signal of the hydraulic actuator module. The signal of the hydraulic actuator module includes the main oil circuit pressure signal, hydraulic oil temperature, and proportional valve current. When the duration of the commutation command received by the main controller reaches the preset time window threshold and both the travel speed and oil temperature are lower than the corresponding speed threshold and oil temperature threshold, the commutation control mechanism is triggered. The commutation control mechanism includes: S1: Dynamic flexible unloading, specifically: The main controller controls the variable pump of the forward gear clutch to adjust the swashplate tilt angle to change the gear ratio so that the vehicle speed decreases linearly with the set deceleration slope; at the same time, it controls the forward gear clutch to reduce the oil pressure and maintain it at the semi-engaged pressure threshold to flexibly release the torque stress of the transmission system; until the real-time collected vehicle speed decreases to the safety threshold and enters S2. S2: Cross-shifting and pre-charge oil, specifically: S2.1 The main controller outputs a PWM signal with the first duty cycle to control the forward gear clutch to start linearly depressurizing at the set depressurization slope until the forward gear oil pressure is 0; at the same time, a pre-charged high-pressure pulse is sent to the reverse gear clutch to eliminate the mechanical clearance of the friction plates. S2.2 After the pre-charge high-voltage pulse is applied, the main controller controls the proportional pressure reducing valve of the reverse clutch to reduce the oil pressure to the engagement critical threshold, and maintains the oil pressure at the engagement critical threshold until the real-time collected output shaft speed drops to the speed threshold and enters S3; S3: Smooth combination of power output, specifically: The main controller controls the proportional valve of the reverse gear clutch to fully open until the reverse gear oil pressure stabilizes at the system working pressure, thus completing the smooth reverse power output.

[0006] Optionally, in step S1, the main controller adjusts the swashplate tilt angle based on the electro-hydraulic closed-loop drive equation, as shown in the following formula: ; in: The control time from the moment of commutation triggering The corresponding swashplate tilt angle; The initial tilt angle of the swashplate when the reversal is triggered; This represents the maximum tilt angle of the variable pump. This represents the maximum displacement of the variable pump. This refers to the displacement of a fixed-displacement motor. The total volumetric efficiency of the system; For mechanical bus and rear axle combined transmission ratio; The diameter of the drive wheel; The input shaft speed of the variable pump; To set the deceleration slope, , The travel speed when the direction change is triggered. For commutation safety threshold, The time required to slow down to the target.

[0007] Optionally, in S2.1, the specific formula for the amount of oil introduced by the pre-charged high-pressure pulse is as follows: ; in: This refers to the total amount of oil required for pre-filling. This is the effective pressure area of ​​the reverse gear clutch piston. The piston stroke required to eliminate the axial clearance of the friction plate assembly and bring the friction plates to their initial contact state; This refers to the volume of the residual cavity in the pipeline between the proportional valve outlet and the clutch cylinder. The base pulse width of the pre-charged high-pressure pulse Determine by the following formula: ; in: Basic pulse width; Hydraulic oil temperature Oil inlet flow rate when the lower proportional pressure reducing valve is fully open; oil temperature The equivalent leakage flow rate is as follows; Hydraulic oil temperature; Pre-charge high-pressure pulse time Determine by the following formula: ; in: This is the oil temperature correction factor. This is the clutch wear compensation coefficient.

[0008] Optionally, the process by which the main controller maintains the oil pressure at the semi-clutch pressure threshold or the engagement critical threshold is as follows: ① Timing-down duty cycle: Specifically, at the instant the pre-charge high-pressure pulse time ends, the main controller adjusts the PWM signal duty cycle from the first duty cycle to the second duty cycle and transmits it to the proportional pressure reducing valve of the forward or reverse clutch; wherein, the second duty cycle is determined based on the half-clutch pressure threshold or engagement critical threshold, hydraulic oil temperature, and the current-pressure calibration relationship of the proportional pressure reducing valve, specifically: According to target pressure and hydraulic oil temperature By querying the current-pressure calibration relationship of the proportional pressure reducing valve, the target control current can be obtained. ; The outer pressure loop determines the target control current based on the current pressure error according to the following formula; ; in: The target pressure is the semi-linkage pressure threshold or the engagement critical threshold. Control the current to the target; The reference current given for the current-pressure calibration relationship; This is the pressure outer ring proportional coefficient; This represents the current pressure error. ; To control the actual pressure; The second duty cycle is calculated based on the conversion relationship between current-PWM correction and duty cycle, according to the target control current. ② The current and hydraulic negative feedback closed loop is as follows: The target control current corresponding to the semi-linkage pressure threshold or engagement critical threshold is determined based on the current-pressure calibration relationship of the proportional pressure reducing valve. The proportional pressure reducing valve of the forward or reverse gear clutch linearly converts the PWM signal into the axial electromagnetic thrust of the valve core. The main controller collects the feedback current of the proportional valve in real time and executes closed-loop PID regulation. Specifically, it calculates the PWM correction amount based on the conversion relationship between current, PWM correction amount and duty cycle, determines the PWM duty cycle after output correction based on the PWM correction amount, and sets the output limit and integral anti-saturation. ③ Pressure sensor fine-tuning: Specifically: The system uses pressure sensors located in the main oil circuit and clutch control end to send the real-time collected actual control pressure of the hydraulic actuator module back to the main controller; The main controller dynamically compares the deviation between the actual control pressure and the semi-linkage pressure threshold or engagement critical threshold, and corrects the target control current based on the conversion relationship between current-PWM correction amount-duty cycle. Then, the PWM duty cycle is corrected by the current inner loop PID, and the valve port flow, leakage or pressure control parameters are corrected according to the hydraulic oil temperature.

[0009] Optionally, the conversion relationship between current and PWM correction is as follows: ; in: This is the PWM correction amount. For current error, , For the first The target current for each sampling period For feedback current; The sampling period; , and These are the proportional, integral, and differential coefficients, respectively. This is the current sampling sequence number; For summation index; The conversion relationship between PWM correction and duty cycle is as follows: ; in: Based on duty cycle, This is the corrected duty cycle. This is the amplitude limiting function.

[0010] Optionally, the specific formula for the critical threshold is as follows: ; in: This is the critical threshold for bonding; The equivalent resultant force of the initial preload of the W-shaped return spring inside the reverse clutch and the sealing friction resistance; This is the stiffness coefficient of the W-type return spring.

[0011] Optionally, the depressurization rate of the forward gear clutch and the pre-charge rate of the reverse gear clutch are cross-controlled in opposite directions and coordinated according to a preset cross-control constant. Specifically, the main controller performs linear depressurization with a set depressurization slope, while simultaneously introducing a pre-charge high-pressure pulse with a set pre-charge slope; wherein, The pressure relief slope of the forward gear clutch band is shown. , The pre-charge slope of the reverse clutch with the symbol is the pre-charge oil slope. When using inverse proportional coordination, the following conditions are met. , These are the cross-control constants obtained through bench calibration; Set the pressure relief slope The specific formula is as follows: ; in, This represents the pressure change of the forward gear clutch during the control period. This refers to the pressure relief control period; the pressure relief phase. ; Set the pre-fill slope The specific formula is as follows: ; in, This represents the pressure change of the reverse clutch during the control period. This refers to the pre-filling oil control period; the pre-filling oil stage. .

[0012] Optionally, if the duration of the reversing command does not reach the preset time window threshold, a first alarm signal is triggered, which is determined to be a false trigger or signal jitter, and the reversing command is ignored or anti-jitter processing is performed. If the travel speed is higher than the corresponding speed threshold after the reversing command duration reaches the preset time window threshold, the second alarm signal is triggered, which prohibits reversing, maintains the current gear, and outputs a high-speed reversing lock-up alarm; if the hydraulic oil temperature is higher than or equal to the corresponding oil temperature threshold, the third alarm signal is triggered, which limits the reversing frequency or enters the hydraulic system thermal protection mode.

[0013] In addition, this invention also provides a low-horsepower HCVT active deceleration and pre-charge oil-coordinated reversing system. This system includes a transmission system, a signal acquisition module, a hydraulic execution module, and a main controller. The signal acquisition module is used to acquire vehicle status and operation intention signals in real time. The transmission system includes an output shaft, a forward gear clutch, and a reverse gear clutch. The hydraulic execution module includes a hydraulic continuously variable speed control device, a forward gear proportional pressure reducing valve, and a reverse gear proportional pressure reducing valve. The hydraulic continuously variable speed control device is used to adjust the swashplate angle of the variable pump. The forward gear proportional pressure reducing valve is used to adjust the oil pressure in the forward gear clutch, and the reverse gear proportional pressure reducing valve is used to adjust the oil pressure in the reverse gear clutch. The signal acquisition module, forward gear clutch, reverse gear clutch, hydraulic continuously variable speed control device, forward gear proportional pressure reducing valve, and reverse gear proportional pressure reducing valve are all electrically connected to the main controller. The main controller is used to execute the aforementioned low-horsepower HCVT active deceleration and pre-charge oil-coordinated reversing method.

[0014] Optionally, the low-horsepower HCVT active deceleration and pre-charge oil coordinated commutation system further includes a multi-channel safety interception and dynamic protection module. The multi-channel safety interception and dynamic protection module is electrically connected to the signal acquisition module and the main controller, respectively. The multi-channel safety interception and dynamic protection module can trigger different alarm signals based on the data acquired by the signal acquisition module and feed them back to the main controller.

[0015] The technical solution of the present invention has the following beneficial effects: The fundamental difference between this invention and existing tractor reversing technology lies in the deep integration of hardware execution and software control timing. Existing structures often rely on purely mechanical operation to cut off power and then hard-engage gears, or traditional dual-clutch systems rely solely on simple on / off solenoid valves for switching control. This invention eliminates the need for on / off valves, instead introducing a high-frequency proportional pressure reducing valve assembly (response time ≤30ms) and a hydraulic continuously variable transmission module working in tandem. It does not rely solely on a clutch, but utilizes the active displacement adjustment characteristics of a variable pump to participate in power control.

[0016] Existing methods directly cut off the forward gear hydraulic pressure and then fill the reverse gear cylinder with oil when changing direction at high speed or under load. Due to the large speed difference and mechanical dead zone, this easily causes the transmission to stall, experience severe jerking, or grind. This invention employs a four-step flexible transition method in its control logic: ① Do not directly cut off power: After receiving the command, the forward gear does not directly release pressure to zero, but instead drops to "semi-clutch pressure holding", allowing a small amount of slippage to release the torque stress inside the system.

[0017] ② Active speed reduction replaces passive slippage: The low-horsepower HCVT variable pump actively reduces the displacement and absorbs kinetic energy to achieve "linear speed reduction", instead of relying on burning the clutch friction plate to reduce the speed.

[0018] ③ Inverse proportional cross control and pre-charge pulse: When the speed drops to the safe threshold ( At speeds of km / h, while linearly depressurizing in forward gear, a very short high-pressure oil pulse is applied to reverse gear. This pulse precisely overcomes the return spring force and eliminates friction plate clearance (eliminating dead zones), then maintains low pressure, which is distinctly different from the linear, slow oil filling technology of existing technologies. ④ Precise zero-speed matching: It is necessary to wait until the system detects that the output shaft speed is close to standstill ( Only when the reverse gear oil pressure is increased to the working pressure at rpm can it be fully engaged and achieve smooth reverse gear operation.

[0019] This invention acquires real-time signals of travel speed and output shaft rotation speed, actively adjusts the hydraulic continuously variable transmission module and the forward gear clutch oil pressure to flexibly unload power, and differentially controls the forward gear depressurization and reverse gear pre-filling when the speed drops to a safe threshold. Finally, when the output shaft speed matches, the reverse gear clutch fully engages to output power in the opposite direction. This invention solves the problems of large mechanical impact, significant power interruption, and easy burn-out of friction plates in existing low-horsepower tracked tractors during frequent reversing operations. It achieves seamless power connection and precise speed matching, fundamentally eliminating the jerking sensation and gear grinding phenomenon during reversing in traditional tractors; it avoids forced slippage of the clutch under large speed differences, significantly reduces the wear and heat generation of multi-plate wet clutches and reversing idler wheels, and extends the overall service life of the transmission; it sets a safety threshold judgment based on speed and rotation speed to prevent the risk of transmission system lock-up or vehicle loss of control caused by the driver accidentally engaging reverse gear at high speed. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the architecture of the small-horsepower HCVT active deceleration and pre-charge oil coordinated commutation system in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the change curves of commutation timing and oil pressure in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the architecture of the small-horsepower HCVT active deceleration and pre-charge oil coordinated commutation system in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the tractor transmission system in Embodiment 2 of the present invention.

[0022] Explanation of icon numbers: 1. Variable pump, 2. Fixed displacement motor, 3. Output shaft.

[0023] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0026] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0029] This invention proposes a method and system for coordinated reversing of low-horsepower HCVT with active speed reduction and pre-filling oil, aiming to solve the problem that existing vehicle reversing methods cannot guarantee smoothness, operational stability and component life during frequent reversing.

[0030] Example 1: This embodiment introduces precise timing control and cross-shift control methods, see [link to documentation]. Figure 4 The variable displacement pump's regulating valve or servo mechanism changes the angle of the swashplate relative to the pump shaft reference plane. The method in this embodiment changes the displacement and transmission ratio of the variable pump. Upon receiving a reversing command, it does not directly cut off power. Instead, it utilizes a hydrostatic system continuously variable transmission module composed of a variable pump 1 and a fixed displacement motor 2. The main controller adjusts the swashplate angle of the variable pump 1 to achieve continuous stepless change in the transmission ratio, thereby actively and smoothly reducing the speed and torque of the output shaft 3, completing a flexible unloading of power and avoiding the impact of directly disengaging the clutch. Then, a high-frequency proportional pressure reducing valve group receives a high-frequency pulse width modulation (PWM) signal to precisely adjust the oil pressure of the forward and reverse clutches at the millisecond level. At critical reversing points, utilizing its rapid response characteristics, it performs linear pressure relief for the forward gear and applies a 'pre-charge pulse' of specific frequency and intensity to the reverse gear to precisely overcome the friction plate return spring force and eliminate mechanical backlash, achieving seamless power switching. The reverse clutch is only fully engaged when the output shaft 3 speed approaches zero.

[0031] See Figure 1 and Figure 2 This embodiment provides a method for coordinated reversing of active deceleration and pre-charge oil in a low-horsepower HCVT, used to control the reversing of the transmission system of a low-horsepower tracked tractor. The method for coordinated reversing of active deceleration and pre-charge oil in a low-horsepower HCVT includes the following steps: I. Identification and Input Acquisition: Real-time acquisition of vehicle status parameters of the tractor transmission system; including: vehicle status parameters such as travel speed v, transmission system output shaft speed signal n, hydraulic system main oil circuit pressure signal P, hydraulic oil temperature T, and proportional valve current I; 2. The commutation control mechanism is triggered when the duration of the commutation command received by the main controller reaches a preset time window threshold and both the travel speed and oil temperature are lower than the corresponding speed and oil temperature thresholds; in this embodiment, the preset time window threshold is... The speed threshold is The oil temperature threshold is 95℃.

[0032] In this embodiment, the main controller performs safety judgments according to mutually exclusive priorities: if the duration of the reversing command does not reach the preset time window threshold, a first alarm signal is triggered and the reversing command is ignored, i.e., the operation terminal noise filtering mode; only when the duration of the reversing command reaches the time window threshold, if the traveling speed is higher than the speed threshold, a second alarm signal is triggered and reversing is prohibited, i.e., high-speed lock-up protection; if the hydraulic oil temperature is higher than or equal to the oil temperature threshold, a third alarm signal is triggered and the reversing frequency is limited or the hydraulic system thermal protection mode is entered to achieve high-speed lock-up protection.

[0033] The commutation control mechanism includes: S1: Dynamic flexible unloading (i.e.) Figure 2 The time period from T0 to T1 is as follows: The main controller controls the variable pump 1 of the forward gear clutch to adjust the swashplate tilt angle to change the transmission ratio so that the vehicle speed decreases linearly with the set deceleration slope; at the same time, it controls the forward gear clutch to reduce the oil pressure and maintain it at the semi-engaged pressure threshold to flexibly release the torque stress of the transmission system; until the real-time collected vehicle speed decreases to the safety threshold and enters S2. This embodiment utilizes the hydraulic damping characteristics of the hydraulic-mechanical continuously variable transmission module to absorb the kinetic energy of the transmission system, replacing the friction plate slippage reduction, thereby achieving flexible unloading of power. In this embodiment, the safety threshold is... .

[0034] In step S1, the main controller adjusts the swashplate tilt angle based on the electro-hydraulic closed-loop drive equation, as shown in the following formula: ; in, The control time from the moment of commutation triggering The corresponding swashplate angle, The initial tilt angle of the swashplate when the reversing is triggered. This represents the maximum tilt angle of variable pump 1. This is the maximum displacement of variable pump 1. It is a fixed displacement motor with a displacement of 2. The total volumetric efficiency of the system. For mechanical bus and rear axle combined transmission ratio, The diameter of the drive wheel, The input shaft speed of variable pump 1 To set the deceleration slope, The travel speed when the direction change is triggered. For commutation safety threshold, The time required to slow down to the target.

[0035] While the main controller sends decreasing PWM duty cycle control commands to change the transmission ratio and make the vehicle speed decrease linearly according to the set deceleration slope, it simultaneously collects the actual swashplate tilt angle feedback signal of the variable pump 1 in real time through external sensors. It also utilizes a built-in closed-loop PID control algorithm to frequently correct the control current of the proportional displacement regulating valve, overcoming the pressure / flow volume fluctuations in the main oil circuit caused by temperature rise in low-horsepower engines. Figure 2 velocity curve in the middle (solid line) The mutations were completely eliminated, and a smooth linear decreasing trend with extremely high fitting was observed.

[0036] At the same time, such as Figure 2 As shown, the forward gear oil pressure drops instantly from the highest working pressure and remains at the "semi-clutch pressure". This allows the forward gear friction plate to produce a small amount of slippage, thereby flexibly releasing the torque stress in the transmission system and avoiding the mechanical shock caused by the traditional hard disengagement.

[0037] S2: Cross-shifting and pre-filling (i.e., Figure 4 The time period from T1 to T2 is as follows: S2.1 The main controller outputs a PWM signal with the first duty cycle to control the forward gear clutch to start linearly depressurizing at the set depressurization slope until the forward gear oil pressure is 0; at the same time, a pre-charged high-pressure pulse is sent to the reverse gear clutch to eliminate the mechanical clearance of the friction plates. In this embodiment, when the travel speed When the speed reaches km / h, step S2.1 is triggered. For example... Figure 4 At time T1, as shown, both linear depressurization and pre-charge pulses are performed simultaneously, as detailed below: 1) Linear pressure relief: After the forward gear oil pressure ends and the semi-clutch is held, the pressure is continuously and linearly relieved to zero along the set slope, smoothly cutting off the forward power.

[0038] Furthermore, the forward clutch depressurization rate and the reverse clutch pre-charge rate are cross-controlled in opposite directions and coordinated according to a preset cross-control constant. At time T1, the forward gear oil pressure decreases along the slope, while the reverse gear oil pressure rapidly increases along the slope. The transient intersection point of their pressures is controlled at... Between. The pressure at this intersection point is slightly higher than the engagement threshold of the reverse clutch, ensuring that both friction plates are in a state of fretting load during the instant of reversal, thereby avoiding a dead zone of power interruption. Among them, , When using inverse proportional coordination, the following conditions are met. , The cross-control constants are obtained through bench calibration.

[0039] Set the pressure relief slope The specific formula is as follows: ; in, This represents the pressure change of the forward gear clutch during the control period. This refers to the pressure relief control period; the pressure relief phase. ,therefore .

[0040] Set the pre-fill slope The specific formula is as follows: ; in, This represents the pressure change of the reverse clutch during the control period. This refers to the pre-filling oil control period; the pre-filling oil stage. ,therefore .

[0041] 2) Pre-charge pulse: Simultaneously, the reverse clutch begins to execute the adaptive pre-charge control logic. Specifically, at time T1, the main controller instructs the reverse proportional pressure reducing valve to fully open, controlling its output pressure to instantly jump to the rated working pressure of the main hydraulic circuit within a hardware response time of ≤30ms.

[0042] In S2.1, the specific formula for the amount of oil introduced by the pre-charged high-pressure pulse is as follows: ; in, This is the total amount of oil required for pre-filling. This is the effective pressure area of ​​the reverse gear clutch piston. The piston stroke required to eliminate the axial clearance of the friction plate assembly and bring the friction plates to their initial contact state. This refers to the residual cavity volume in the pipeline between the proportional valve outlet and the clutch cylinder. All the above parameters are determined based on the actual clutch structure.

[0043] In this embodiment, the pre-charge pulse width is first calculated based on the required volume of the clutch oil chamber, the inlet flow rate, and the leakage compensation amount to obtain the basic pulse width. Then, the basic pulse width is calibrated and corrected based on the hydraulic oil temperature, system pressure, valve orifice flow characteristics, and clutch wear condition to obtain the final control pulse width. The calibration curve is used to correct the calculation results, not to replace the basic calculation; the actual control program uses a combination of the above basic calculation and calibration correction. The final control pulse width is obtained from the basic pulse width after oil temperature correction and wear compensation, as shown in the following formula. The specific calibration curve and correction coefficients are obtained through vehicle bench calibration tests and are fixed in the calibration parameter table of the main controller.

[0044] Based on the continuity relationship of hydraulic fluid, the basic pulse width of the pre-charged high-pressure pulse Determine by the following formula: ; in, Based on the pulse width, oil temperature The oil inlet flow rate when the lower proportional pressure reducing valve is fully open. oil temperature The equivalent leakage flow rate is as follows. This refers to the hydraulic oil temperature.

[0045] Pre-charge high-pressure pulse time Determine by the following formula: ;

[0046] In the formula, For the final pre-charge oil high-pressure pulse time, This is the oil temperature correction factor. This is the clutch wear compensation coefficient.

[0047] In this embodiment, the hydraulic oil temperature is collected in real time during actual vehicle operation. Three different pulse width calibration scenario control chains were divided and executed: (a) Low temperature chiller scenario ( Due to the high viscosity of the oil and the large resistance at the valve orifice and in the flow channel, the injection flow rate is... Significant attenuation; to ensure sufficient oil supply and completely eliminate gaps, the TCU adaptively and dynamically extends the high-pressure oil inlet time, with the control pulse width calibrated to... (b) Normal temperature and normal environment ( The hydraulic oil flowability and system internal leakage reach the design balance point; the high-pressure oil injection time maintains the baseline calibration value; and the pulse width is precisely locked at... (c) Extreme high temperature scenario Equivalent leakage flow rate within the system An abnormal surge in pulse output, with millisecond-level oil filling timing being highly susceptible to loss of control and increased risk of thermal damage from sliding friction, prompts the TCU to directly and forcibly terminate pulse output, limit commutation frequency, and report a hardware alarm for extreme temperature rise.

[0048] Cross-control refers to the local overlap and intersecting intervals in the time domain between the pressure build-up curve of the forward clutch and the pre-charge pressure build-up curve of the reverse clutch. Hydraulic pressure overlap characteristics: such as... Figure 2 As shown, in After cross-shifting is initiated, the forward gear clutch oil pressure decreases linearly along the slope from the semi-engaged pressure threshold, while the reverse gear clutch oil pressure rapidly increases along the slope due to the application of a pre-charged high-pressure pulse. Transient intersection control: During the dynamic process of the two curves overlapping, the falling edge of the forward gear clutch oil pressure and the rising edge of the reverse gear clutch oil pressure intersect in the time domain. The transient intersection point of their pressures is controlled at... Between. The pressure at this intersection point, calibrated on a bench, is slightly higher than the critical engagement threshold pressure of the reverse clutch.

[0049] S2.2 After the pre-charge high-voltage pulse is applied, the main controller controls the proportional pressure reducing valve of the reverse clutch to reduce the oil pressure to the engagement critical threshold, and maintains the oil pressure at the engagement critical threshold until the real-time collected output shaft 3 speed drops to the speed threshold, entering S3; in this embodiment, the speed threshold is During the determined pre-charge high-pressure pulse time After completion, in order to prevent the reverse gear clutch piston from resetting and degenerating under the axial force of the internal W-shaped return spring, the main controller instructs the reverse gear proportional pressure reducing valve to quickly reduce the control oil pressure and maintain it at a low pressure holding state at the engagement critical point (Kiss Point).

[0050] In this embodiment, to precisely maintain the pressure at the aforementioned semi-clutch or critical pressure threshold under harsh operating conditions such as low rated flow rate in the main oil circuit of a low-horsepower engine (≤40L / min) and high-frequency, drastic fluctuations in oil temperature, the main controller employs a proportional closed-loop control strategy based on the 'voltage-current-pressure' (VIP) mapping relationship. Furthermore, the pressure holding control mechanism at the critical threshold is completely consistent with the semi-clutch pressure threshold holding control mechanism in stage S1 within the same "control closed-loop framework," both relying on three layers of closed-loop control strategies executed by the main controller: time-degraded PWM duty cycle control, current and hydraulic negative feedback closed loop, and pressure sensor fine-tuning. Specifically, the process by which the main controller maintains the oil pressure at the semi-clutch pressure threshold or the critical threshold is as follows: ① Timing-based duty cycle reduction: Specifically, at the instant the pre-charge high-pressure pulse time ends, the main controller adjusts the PWM signal duty cycle from the first duty cycle to the second duty cycle and transmits it to the proportional pressure reducing valve of the forward or reverse clutch; wherein, the second duty cycle is determined based on the half-clutch pressure threshold or engagement critical threshold, hydraulic oil temperature, and the current-pressure calibration relationship of the proportional pressure reducing valve; specifically: According to target pressure and hydraulic oil temperature By querying the current-pressure calibration relationship of the proportional pressure reducing valve, the target control current can be obtained. ; The outer pressure loop determines the target control current based on the current pressure error according to the following formula; ; in, The target pressure is the semi-linkage pressure threshold or the engagement critical threshold. To control the target current, To effectively control pressure, The reference current given for the current-pressure calibration relationship. This is the pressure outer ring proportional coefficient; This represents the current pressure error. ; The second duty cycle is calculated based on the conversion relationship between current-PWM correction and duty cycle, according to the target control current. In this embodiment, the range of the first duty cycle corresponding to the pre-filling stage is: Preferred The second duty cycle range corresponding to the pressure holding phase is: Preferred The permissible deviation for each duty cycle is... The actual values ​​were determined by bench calibration based on the current-pressure characteristic curve of the proportional pressure reducing valve and the system operating pressure.

[0051] ② The current and hydraulic negative feedback closed loop is as follows: The target control current corresponding to the semi-linkage pressure threshold or engagement critical threshold is determined based on the current-pressure calibration relationship of the proportional pressure reducing valve. The proportional pressure reducing valve of the forward or reverse gear clutch linearly converts the PWM signal into the axial electromagnetic thrust of the valve core. To overcome the drift of the drive current caused by the change in resistance due to the temperature rise of the electromagnetic coil, the main controller collects the feedback current of the proportional valve in real time and executes closed-loop PID regulation. Specifically, the PWM correction amount is calculated based on the conversion relationship between current, PWM correction amount and duty cycle, and the output PWM duty cycle after correction is determined based on the PWM correction amount. At the same time, the output limit and integral anti-saturation are set to realize closed-loop PID regulation. ③ Pressure sensor fine-tuning: Specifically: The system uses pressure sensors located in the main oil circuit and clutch control end to send the real-time collected actual control pressure of the hydraulic actuator module back to the main controller; The main controller dynamically compares the deviation between the actual control pressure and the semi-clutch pressure threshold or engagement critical threshold, and corrects the target control current based on the conversion relationship between current-PWM correction amount-duty cycle. Then, the PWM duty cycle is corrected by the current inner loop PID, and the valve port flow, leakage or pressure control parameters are corrected according to the hydraulic oil temperature, so that the cylinder pressure is stabilized within the allowable deviation range near the pre-calibrated semi-clutch pressure threshold or engagement critical threshold.

[0052] In this embodiment, the conversion relationship between current and PWM correction is as follows: ; in: This is the PWM correction amount. For current error, , For the first The target current for each sampling period For feedback current; The sampling period; , and These are the proportional, integral, and differential coefficients, respectively. This is the current sampling sequence number; For summation index; The conversion relationship between PWM correction and duty cycle is as follows: ; in: Based on duty cycle, This is the corrected duty cycle. This is the amplitude limiting function.

[0053] The PID coefficients in this embodiment were tuned through bench step response tests: a target current step was applied under different oil temperatures, system operating pressures, and load conditions, and the coefficients were adjusted based on the pressure response time, steady-state error, and overshoot. , and The tuning results are then written into the main controller calibration parameter table. In this embodiment, the scaling factor The range of values ​​is Integral coefficient The range of values ​​is Differential coefficients The range of values ​​is Sampling period for Preferred Output limiting is the PWM duty cycle. The integral anti-saturation limit is The specific values ​​were determined after tuning the clutch pressure response characteristics through bench testing.

[0054] In this embodiment, the critical threshold is used. The specific formula is as follows: ; in, To meet the critical threshold for bonding, The equivalent resultant force of the initial preload of the W-shaped return spring inside the reverse clutch and the sealing friction resistance is... This is the stiffness coefficient of the W-type return spring.

[0055] In this embodiment, the system operating pressure is Preferred The semi-linkage pressure threshold is the system operating pressure. ,Right now Preferred The critical threshold for connection is the system operating pressure. ,Right now Preferred .

[0056] S3: Smooth transition and power output (i.e.) Figure 2 After time T2, specifically: The main controller controls the proportional valve of the reverse gear clutch to fully open until the reverse gear oil pressure stabilizes at the system working pressure, thus completing the smooth reverse power output.

[0057] In this embodiment, when the absolute value of the output shaft 3 rotation speed... When the rpm is almost stationary, step S3 is triggered. At this time, the corresponding... Figure 2 At time T2, the speed curve is about to cross zero. The main controller instructs the reverse gear proportional valve to fully open. Figure 2 The reverse gear hydraulic pressure (PR) rapidly rises and stabilizes at the system operating pressure, fully pressing the reverse gear friction plates together. Power is then smoothly output in the reverse direction. Figure 2The medium-speed curve enters the reverse linear acceleration phase. The entire reversal process is underway. The entire process is completed automatically within seconds, without the driver needing to operate the clutch pedal. This engagement strategy, based on precise matching at near-zero speeds to fully engage the clutch, completely avoids the forced slippage of the clutch under huge speed differences in traditional reversing. It fundamentally eliminates the power jerk and gear impact sensation at the moment of reversing, achieving a seamless and smooth connection of reverse power output; at the same time, it eliminates the cumbersome clutch pedal operation, thus achieving smooth reversing.

[0058] The active deceleration and pre-charge oil-coordinated commutation method for low-horsepower HCVT in this embodiment has the following beneficial effects: 1. Eliminate mechanical shock: It achieves seamless power connection and precise speed matching, fundamentally eliminating the jerking sensation and gear grinding phenomenon when reversing traditional tractors.

[0059] 2. Extend component life: It avoids forced slippage of the clutch under huge speed differences, significantly reduces the wear and heat generation of multi-plate wet clutches and reversing idlers, and extends the overall service life of the gearbox.

[0060] 3. Improve operational safety: Safety threshold judgment based on speed and rotation speed is set to prevent the risk of transmission system lock-up or vehicle loss of control caused by the driver accidentally engaging reverse gear while driving at high speed.

[0061] Furthermore, the core differences between 50 horsepower and below tracked tractors and high-horsepower tractors determine the irreplaceability of this solution: a. Hydraulic system constraints: The engine power of low-horsepower models is limited, and the rated flow rate of the main oil circuit of the hydraulic system is ≤40L / min, and the rated pressure is ≤20MPa. The pressure / flow redundancy is much lower than that of high-horsepower models, which cannot support high flow and high response hydraulic control. This solution adopts a high-frequency proportional pressure reducing valve with a response of ≤30ms, combined with single-pulse pre-charge logic, to achieve gap elimination with a very small flow rate, which is perfectly adapted to low-flow hydraulic systems.

[0062] b. Differences in operating conditions: Low-horsepower models are mainly used for narrow plots of land, yard management, and front-end loading operations, with a reversing frequency of up to [missing information]. This speed per minute is significantly higher than that of high-horsepower machines operating in the field; this solution The fully automatic reversing logic requires no operation of the clutch pedal and is suitable for high-frequency reversing needs.

[0063] c. Transmission system constraints: The small size of the gearbox in low-horsepower models and the low heat capacity of the clutch friction plates make it unable to withstand slippage under large speed differences; this solution uses a low-horsepower HCVT active speed reduction to replace friction plate slippage, fundamentally reducing the heat generation of the friction plates, avoiding burnout, and adapting to the hardware constraints of small-capacity clutches.

[0064] Example 2: See Figure 3 and Figure 4 This embodiment provides a low-horsepower HCVT active deceleration and pre-charge oil-coordinated reversing system. The system includes a transmission system, a signal acquisition module, a hydraulic execution module, and a main controller. The signal acquisition module is used to acquire vehicle status and operation intention signals in real time. The transmission system includes an output shaft 3, a forward gear clutch, and a reverse gear clutch. The hydraulic execution module includes a hydraulic continuously variable speed control device, a forward gear proportional pressure reducing valve, and a reverse gear proportional pressure reducing valve. The hydraulic continuously variable speed control device is used to adjust the swashplate angle of the variable pump 1. The forward gear proportional pressure reducing valve is used to adjust the oil pressure in the forward gear clutch, and the reverse gear proportional pressure reducing valve is used to adjust the oil pressure in the reverse gear clutch. The signal acquisition module, forward gear clutch, reverse gear clutch, hydraulic continuously variable speed control device, forward gear proportional pressure reducing valve, and reverse gear proportional pressure reducing valve are all electrically connected to the main controller. The main controller is used to execute the above-described low-horsepower HCVT active deceleration and pre-charge oil-coordinated reversing method. In this embodiment, both the forward gear clutch and the reverse gear clutch are wet clutches, and the response time of the proportional pressure reducing valve is less than or equal to... It is used to precisely adjust the pressure curve of the clutch cylinder.

[0065] In this embodiment, the signal acquisition module includes a reversing lever / operating terminal, a speed sensor, and an output shaft speed sensor. Physically, the reversing lever or operating terminal is typically mounted on the side of the steering column or the right-side multi-function control armrest in the tractor cab for easy driver operation and real-time acquisition of reversing intentions. The speed sensor is generally located in the rear axle housing or final drive of the tractor chassis, or a radar sensor can be mounted on the bottom of the frame to accurately acquire the actual travel speed signal. The output shaft 3 speed sensor is located at the power output end of the hydraulic mechanical continuously variable transmission, such as near the output shaft 3 bearing cover or the output gear, to directly and accurately monitor the real-time power output and output shaft 3 speed signal after the clutch is engaged. When the operator moves the reversing lever, the input terminal is responsible for transmitting the reversing command and the real-time tractor travel speed signal. and the speed signal of the output shaft 3 of the transmission system Send to the control center.

[0066] In this embodiment, the main controller internally records the steps of a smooth reversing control method. This method first acquires the reversing command and collects speed and rotational speed in real time. After confirming that the current speed is not in a high-speed state, it adjusts the unloading power through variable pump 1 and reduces the forward gear clutch oil pressure to a semi-engaged state. As the speed decreases, when the system detects that the speed is not higher than... At this time, the forward gear clutch is fully depressurized, while the reverse gear clutch begins to pre-charge with oil; then the speed is continuously monitored until the absolute value of the output shaft speed drops to a certain level. At this time, the reverse gear clutch pressure is increased to the system working pressure to fully engage, completing a smooth reversal. The main controller is responsible for performing high-frequency calculations and safety judgments on the input signals and outputting corresponding electronic control commands; the speed threshold is the cross-shift trigger threshold, and only after the reversal command has passed the time window, speed, and oil temperature safety judgments will it enter S2.1.

[0067] In this embodiment, the hydraulic actuator module includes a hydraulic continuously variable transmission (CVT) module, a forward gear proportional pressure reducing valve, and a reverse gear proportional pressure reducing valve. Both the forward and reverse gear proportional pressure reducing valves in this embodiment are high-frequency proportional valves. These high-frequency proportional valves receive pulse width modulation (PWM) signals from the TCU to precisely control the displacement of the hydraulic CVT module, as well as the pressure build-up and pressure relief curves within the forward / reverse wet clutch cylinders.

[0068] The hydraulic continuously variable transmission (CVT) module is the key hardware for achieving "linear speed reduction" during reversing. It employs a closed-loop circuit consisting of a variable displacement pump 1 and a fixed displacement motor 2. The main controller precisely controls the direction and magnitude of the flow output of variable displacement pump 1 by driving the displacement regulating valve of variable displacement pump 1. In the initial stage of reversing (at time T0), the system does not rely on clutch slippage for deceleration, but rather reduces the pump's displacement, utilizing the damping characteristics of the hydraulic system to absorb kinetic energy, allowing the speed to steadily decrease to a safe threshold along a preset slope.

[0069] The high-frequency proportional pressure reducing valve selected in this embodiment has an extremely high dynamic response frequency and a response time that is typically... The function of the valve is to linearly convert the current signal output by the TCU into a pressure signal for the clutch piston. Pre-filling logic: At time T1, the valve receives a high duty cycle pulse command, causing the oil pressure to jump instantaneously. This "pulse" rapidly fills the oil chamber and pushes the piston to the critical position where the friction plates are about to contact, after which the pressure immediately drops to a low-pressure holding state. This precise pressure control completely eliminates the "power interruption dead zone" caused by waiting for oil filling in traditional reversing.

[0070] In this embodiment, the low-horsepower HCVT active deceleration and pre-charge oil coordinated commutation system also includes a multi-channel safety interception and dynamic protection module. The multi-channel safety interception and dynamic protection module is electrically connected to the signal acquisition module and the main controller, respectively. The multi-channel safety interception and dynamic protection module can trigger different alarm signals based on the data collected by the information acquisition module and feed them back to the main controller.

[0071] Since the low-horsepower HCVT active deceleration and pre-charge oil coordinated commutation system includes the low-horsepower HCVT active deceleration and pre-charge oil coordinated commutation method described above, the system possesses all the beneficial effects of the above method, which will not be elaborated here.

[0072] The above description is only a preferred embodiment of the present invention and does not limit the scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. A method for coordinated reversing of low-horsepower HCVT active deceleration and pre-charge oil, used to control the reversing of a low-horsepower tracked tractor, characterized in that, The active deceleration and pre-charge oil-coordinated commutation method for low-horsepower HCVT includes the following steps: Real-time acquisition of vehicle status parameters of low-horsepower tracked tractors, including: vehicle status parameters include the travel speed signal of the low-horsepower tracked tractor, the speed signal of the output shaft in the transmission system, and the signal of the hydraulic actuator module. The signal of the hydraulic actuator module includes the main oil circuit pressure signal, hydraulic oil temperature, and proportional valve current. When the duration of the commutation command received by the main controller reaches the preset time window threshold and both the travel speed and oil temperature are lower than the corresponding speed threshold and oil temperature threshold, the commutation control mechanism is triggered. The commutation control mechanism includes: S1: Dynamic flexible unloading, specifically: The main controller controls the variable pump of the forward gear clutch to adjust the swashplate tilt angle to change the gear ratio so that the vehicle speed decreases linearly with the set deceleration slope; at the same time, it controls the forward gear clutch to reduce the oil pressure and maintain it at the semi-engaged pressure threshold to flexibly release the torque stress of the transmission system; until the real-time collected vehicle speed decreases to the safety threshold and enters S2. S2: Cross-shifting and pre-charge oil, specifically: S2.1 The main controller outputs a PWM signal with the first duty cycle to control the forward gear clutch to start linearly depressurizing at the set depressurization slope until the forward gear oil pressure is 0; at the same time, a pre-charged high-pressure pulse is sent to the reverse gear clutch to eliminate the mechanical clearance of the friction plates. S2.2 After the pre-charge high-voltage pulse is applied, the main controller controls the proportional pressure reducing valve of the reverse clutch to reduce the oil pressure to the engagement critical threshold, and maintains the oil pressure at the engagement critical threshold until the real-time collected output shaft speed drops to the speed threshold and enters S3; S3: Smooth combination of power output, specifically: The main controller controls the proportional valve of the reverse gear clutch to fully open until the reverse gear oil pressure stabilizes at the system working pressure, thus completing the smooth reverse power output.

2. The method for coordinated commutation of low-horsepower HCVT active deceleration and pre-charge oil as described in claim 1, characterized in that, In step S1, the main controller adjusts the swashplate tilt angle based on the electro-hydraulic closed-loop drive equation, as shown in the following formula: ； in: The control time from the moment of commutation triggering The corresponding swashplate tilt angle; The initial tilt angle of the swashplate when the reversal is triggered; This represents the maximum tilt angle of the variable pump. This represents the maximum displacement of the variable pump. This refers to the displacement of a fixed-displacement motor. The total volumetric efficiency of the system; For mechanical bus and rear axle combined transmission ratio; The diameter of the drive wheel; The input shaft speed of the variable pump; To set the deceleration slope, , The travel speed when the direction change is triggered. For commutation safety threshold, The time required to slow down to the target.

3. The method for coordinated commutation of low-horsepower HCVT active deceleration and pre-charge oil as described in claim 1, characterized in that, In S2.1, the specific formula for the amount of oil introduced by the pre-charged high-pressure pulse is as follows: ； in: This refers to the total amount of oil required for pre-filling. This is the effective pressure area of ​​the reverse gear clutch piston. The piston stroke required to eliminate the axial clearance of the friction plate assembly and bring the friction plates to their initial contact state; This refers to the volume of the residual cavity in the pipeline between the proportional valve outlet and the clutch cylinder. The base pulse width of the pre-charged high-pressure pulse Determine by the following formula: ； in: Basic pulse width; oil temperature Oil inlet flow rate when the lower proportional pressure reducing valve is fully open; oil temperature The equivalent leakage flow rate is as follows; Hydraulic oil temperature; Pre-charge high-pressure pulse time Determine by the following formula: ； in: This is the oil temperature correction factor; This is the clutch wear compensation coefficient.

4. The method for coordinated commutation of low-horsepower HCVT active deceleration and pre-charge oil as described in claim 3, characterized in that, The main controller maintains the oil pressure as follows: ① Timing-down duty cycle: Specifically, at the instant the pre-charge high-pressure pulse time ends, the main controller adjusts the PWM signal duty cycle from the first duty cycle to the second duty cycle and transmits it to the proportional pressure reducing valve of the forward or reverse clutch; wherein, the second duty cycle is determined based on the half-clutch pressure threshold or engagement critical threshold, hydraulic oil temperature, and the current-pressure calibration relationship of the proportional pressure reducing valve, specifically: According to target pressure and hydraulic oil temperature By querying the current-pressure calibration relationship of the proportional pressure reducing valve, the target control current can be obtained. ; The outer pressure loop determines the target control current based on the current pressure error according to the following formula; ； in: The target pressure is the semi-linkage pressure threshold or the engagement critical threshold. Control the current to the target; The reference current given for the current-pressure calibration relationship; This is the pressure outer ring proportional coefficient; This represents the current pressure error. ; To control the actual pressure; The second duty cycle is calculated based on the conversion relationship between current-PWM correction and duty cycle, according to the target control current. ② The current and hydraulic negative feedback closed loop is as follows: The target control current corresponding to the semi-linkage pressure threshold or engagement critical threshold is determined based on the current-pressure calibration relationship of the proportional pressure reducing valve. The proportional pressure reducing valve of the forward or reverse gear clutch linearly converts the PWM signal into the axial electromagnetic thrust of the valve core. The main controller collects the feedback current of the proportional valve in real time and executes closed-loop PID regulation. Specifically, it calculates the PWM correction amount based on the conversion relationship between current, PWM correction amount and duty cycle, determines the PWM duty cycle after output correction based on the PWM correction amount, and sets the output limit and integral anti-saturation. ③ Pressure sensor fine-tuning: Specifically: The system uses pressure sensors located in the main oil circuit and clutch control end to send the real-time collected actual control pressure of the hydraulic actuator module back to the main controller; The main controller dynamically compares the deviation between the actual control pressure and the semi-linkage pressure threshold or engagement critical threshold, and corrects the target control current based on the conversion relationship between current-PWM correction amount-duty cycle. Then, the PWM duty cycle is corrected by the current inner loop PID, and the valve port flow, leakage or pressure control parameters are corrected according to the hydraulic oil temperature.

5. The method for coordinated commutation of active speed reduction and pre-charge oil in a low-horsepower HCVT according to claim 4, characterized in that, The conversion relationship between current and PWM correction is as follows: ； in: This is the PWM correction amount; For current error, , For the first The target current for each sampling period For feedback current; The sampling period; , and These are the proportional, integral, and differential coefficients, respectively. This is the current sampling sequence number; For summation index; The conversion relationship between PWM correction and duty cycle is as follows: ； in: Based on duty cycle, This is the corrected duty cycle. This is the amplitude limiting function.

6. The method for coordinated commutation of active deceleration and pre-charge oil in a low-horsepower HCVT according to any one of claims 3 to 5, characterized in that, The specific formula for the critical threshold of bonding is as follows: ； in: This is the critical threshold for bonding; The equivalent resultant force of the initial preload of the W-shaped return spring inside the reverse clutch and the sealing friction resistance; This is the stiffness coefficient of the W-type return spring.

7. The method for coordinated commutation of active speed reduction and pre-charge oil in a low-horsepower HCVT according to any one of claims 1 to 5, characterized in that, The decompression rate of the forward gear clutch and the pre-charge rate of the reverse gear clutch are cross-controlled in opposite directions and coordinated according to a preset cross-control constant. Specifically, the main controller performs linear decompression with a set decompression slope, while simultaneously introducing a pre-charge high-pressure pulse with a set pre-charge slope; wherein, The pressure relief slope of the forward gear clutch band is shown. , The pre-charge slope of the reverse clutch with the symbol is the pre-charge oil slope. When using inverse proportional coordination, the following conditions are met. , These are the cross-control constants obtained through bench calibration; Set the pressure relief slope The specific formula is as follows: ； in, This represents the pressure change of the forward gear clutch during the control period. This refers to the pressure relief control period; the pressure relief phase. ; Set the pre-fill slope The specific formula is as follows: ； in, This represents the pressure change of the reverse clutch during the control period. This refers to the pre-filling oil control period; the pre-filling oil stage. .

8. The method for coordinated commutation of low-horsepower HCVT active deceleration and pre-charge oil as described in any one of claims 1 to 5, characterized in that, If the duration of the reversing command does not reach the preset time window threshold, the first alarm signal is triggered, which is determined to be a false trigger or signal jitter, and the reversing command is ignored or anti-jitter processing is performed. If the travel speed is higher than the corresponding speed threshold after the reversing command duration reaches the preset time window threshold, the second alarm signal is triggered, which prohibits reversing, maintains the current gear, and outputs a high-speed reversing lock-up alarm; if the hydraulic oil temperature is higher than or equal to the corresponding oil temperature threshold, the third alarm signal is triggered, which limits the reversing frequency or enters the hydraulic system thermal protection mode.

9. A low-horsepower HCVT active deceleration and pre-charge oil-coordinated commutation system, characterized in that, The low-horsepower HCVT active deceleration and pre-charge oil-coordinated reversing system includes a transmission system, a signal acquisition module, a hydraulic execution module, and a main controller. The signal acquisition module is used to acquire vehicle status and operation intention signals in real time. The transmission system includes an output shaft, a forward gear clutch, and a reverse gear clutch. The hydraulic execution module includes a hydraulic continuously variable speed control device, a forward gear proportional pressure reducing valve, and a reverse gear proportional pressure reducing valve. The hydraulic continuously variable speed control device is used to adjust the swashplate angle of the variable pump. The forward gear proportional pressure reducing valve is used to adjust the oil pressure in the forward gear clutch's oil circuit, and the reverse gear proportional pressure reducing valve is used to adjust the oil pressure in the reverse gear clutch's oil circuit. The signal acquisition module, forward gear clutch, reverse gear clutch, hydraulic continuously variable speed control device, forward gear proportional pressure reducing valve, and reverse gear proportional pressure reducing valve are all electrically connected to the main controller. The main controller is used to execute the low-horsepower HCVT active deceleration and pre-charge oil-coordinated reversing method according to any one of claims 1 to 8.

10. The low-horsepower HCVT active deceleration and pre-charge oil-coordinated commutation system according to claim 9, characterized in that, The low-horsepower HCVT active deceleration and pre-charge oil coordinated commutation system also includes a multi-channel safety interception and dynamic protection module. The multi-channel safety interception and dynamic protection module is electrically connected to the signal acquisition module and the main controller, respectively. The multi-channel safety interception and dynamic protection module can trigger different alarm signals based on the data acquired by the signal acquisition module and feed them back to the main controller.

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