Flat car walking power control method and system

Abstract

The invention discloses a flat car walking power control method and system. The system comprises an engine, a variable pump unit, a plurality of hydraulic units, a linkage adjusting mechanism and wheels. An accelerator pedal treading depth signal and a working condition mode selection signal are obtained, a control interval is divided according to the treading depth, the current rotating speed n of an engine is collected in real time, and the actual demand torque of a hydraulic pump is calculated; and according to a comparison result, a corresponding strategy is adopted to carry out digital filtering processing on the collected delta Pp signal, so that the rotating speed lifting slope of the engine is dynamically adjusted, the accelerator interval intelligent division method based on hysteresis logic is realized, a double-threshold hysteresis mechanism is introduced, frequent switching of a control mode at a critical point is avoided, and the system stability and the driving smoothness are improved.

Description

Technical Field

[0001] This invention relates to the field of automatic control of construction machinery, and in particular to a method and system for controlling the traveling power of a flatbed truck. Background Technology

[0002] Flatbed trucks, as a type of transportation equipment with a simple structure, convenient operation, and strong load-bearing capacity, are widely used in machinery manufacturing, metallurgical industry, and large-scale warehousing. They are mainly used for ground material transportation or for indoor transportation in conjunction with lifting equipment to complete the cross-regional transfer of heavy objects.

[0003] The existing technology has the following prominent problems: Low fuel efficiency: The engine often operates in the inefficient range and fails to consistently operate in the lowest specific fuel consumption range of the universal characteristic curve; Inaccurate power response: insufficient torque is likely to occur when climbing hills or starting under heavy load, while power redundancy is caused when unloaded on flat roads; The control mode is singular: it does not allow for differentiated parameter configuration based on working conditions, making it difficult to balance micro-motion positioning accuracy and high-speed driving stability. The system has weak anti-interference capability: transient changes in pressure signals can easily cause erroneous adjustments, leading to frequent operation of the actuator and reducing the lifespan of components.

[0004] Although some electronic control systems have introduced displacement feedback control, most only achieve partial closed-loop control. Therefore, there is an urgent need for a flatbed truck travel power control scheme that can adapt to different operating conditions and improve overall performance. Although the current mainstream technology trend leans towards intelligent and electronic control schemes, such systems generally suffer from limitations such as high cost, weak anti-interference capability, and complex maintenance. For example, CN110262502A uses a large number of sensors and processors to realize an intelligent flatbed truck, requiring the addition of multiple sensors and modules to the power drive system to achieve intelligent control. Since the flatbed truck's operating power needs to be adjusted in real time, these sensors and modules need to have sufficient sensitivity, which increases the cost. Moreover, the functions implemented by most of these modules are relatively simple, and the modules are not fully utilized.

[0005] Therefore, there is an urgent need to design a drive scheme based on mechanical structure to effectively address the key technical challenges of poor fuel economy and inaccurate power response in the traditional flatbed truck's power control. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides a method and system for controlling the traveling power of a flatbed truck. By combining mechanical linkage with electronic hierarchical control, the method achieves dynamic matching between the engine output power and the load of the hydraulic traveling system, thereby improving fuel economy, avoiding insufficient power or power redundancy, enhancing system reliability and anti-interference capability, supporting multi-wheel synchronous coordinated drive, and is suitable for heavy transportation scenarios.

[0007] The present invention adopts the following technical solution: A method for controlling the traveling power of a flatbed truck, characterized in that the method dynamically matches the engine output power with the load demand of the hydraulic traveling system under different operating conditions, so that the engine continuously operates in the high-efficiency working range, improving fuel economy and power response performance. The method includes the following steps: S1. Acquire the accelerator pedal depth signal and the operating mode selection signal, wherein the operating modes include creep mode, no-load mode and heavy-load mode; S2. Divide the control range according to the pedaling depth: when the pedaling depth is less than or equal to the first threshold, enter the low-speed range and execute low-speed fine control; when it is greater than the second threshold, enter the high-speed range and start the high-power output strategy. S3. Real-time acquisition of the current engine speed n, and based on the pre-stored engine external characteristic curve, find the maximum available torque Me(n) at that speed; S4. Calculate the actual required torque Mp of the hydraulic pump = (Vp) ΔPp) / 2π, where Vp is the displacement of the variable pump unit, and ΔPp is the pressure difference between the pump inlet and outlet; S5. Compare Mp with (Me(n)) The relationship between the magnitudes of Mf and Mf is defined as follows: Mf is the calibrable compensation torque that characterizes the power consumption and transmission loss of the accessory. S6. If Mp < (Me(n)) If Mf), then prioritize increasing the displacement Vp of the variable pump unit to improve power utilization; if there is still excess torque after Vp reaches the upper limit of the allowable range, then reduce the displacement of the hydraulic motor to increase the system pressure difference ΔPp. S7. If Mp > (Me(n)) If Mf), prioritize increasing the hydraulic motor displacement to reduce the pressure required per unit flow rate and alleviate system load; if the hydraulic motor displacement is still overloaded after reaching the physical or control limit, reduce the variable pump unit displacement Vp to prevent engine stalling. S8. Perform digital filtering on the acquired ΔPp signal to suppress transient jumps caused by road surface disturbances; S9. Dynamically adjust the slope of engine speed rise and fall: there is no slope restriction during the ascent process to ensure rapid response, and a variable slope is set during the descent process, the steepness of which becomes gentler as the brake pedal is pressed deeper; in creep mode, the slope restriction is removed for both acceleration and deceleration to achieve precise positioning.

[0008] Furthermore, in step S2, the first threshold is 30%, the second threshold is 35%, and a hysteresis transition zone with a width of not less than 5% is set between the two. The controller determines the switching threshold according to the current control area to avoid frequent switching near the critical point, which could cause system oscillation.

[0009] Furthermore, the operating mode described in step S1 is input to the electronic controller via the operating handle. The controller configures a set of corresponding control parameters according to different modes: in creep mode, the maximum pump displacement output is limited and the speed ramp is turned off; in heavy load mode, the power output limit is relaxed and the cooling system is activated for forced heat dissipation; in no-load mode, the low speed-high displacement combination is preferred to optimize specific fuel consumption.

[0010] Furthermore, the increase in the displacement of the variable pump unit mentioned in step S6 refers to the controller outputting a PWM current signal to drive a proportional electromagnet, adjusting the swashplate tilt angle to increase the oil displacement; when the displacement control current is detected to have reached the maximum allowable value or the feedback position sensor shows that the mechanical limit has been reached, it is determined that Vp has reached the upper limit, and the subsequent operation of reducing the hydraulic motor displacement is triggered.

[0011] Furthermore, in step S7, even after the hydraulic motor displacement is adjusted to full displacement, the condition Mp ≤ (Me(n)) still cannot be satisfied. When Mf), the controller further reduces the displacement Vp of the variable pump unit to the target safety level and simultaneously issues a visual or audible alarm to prompt the driver to check the load condition or switch to low-speed mode.

[0012] Furthermore, the initial value of the compensation torque Mf is set as the sum of the power consumption of engine accessories (generator, air compressor, cooling fan) and the friction loss of the transmission system, and is dynamically compensated and corrected during operation based on the atmospheric pressure, intake air temperature and hydraulic oil temperature collected by environmental sensors; when the high-altitude low-oxygen condition is identified, the Mf value is automatically increased to reserve disturbance rejection margin.

[0013] Furthermore, in step S8, a first-order digital low-pass filter algorithm is used to process the ΔPp signal. The filtering formula is as follows: Where α is the filter coefficient, ranging from 0.7 to 0.95, corresponding to a cutoff frequency of 5 to 10 Hz; k represents the discrete time index of the current control cycle. 1 indicates the previous control cycle. This filtering algorithm is executed cyclically with a cycle of 10 to 20 ms. ΔP before filtering p ; This indicates the result of the filtering process.

[0014] Furthermore, in the high gear range, the controller simultaneously adjusts the hydraulic motor control current to achieve independent speed regulation for each wheel set, supporting various complex motion modes such as diagonal driving, figure-eight steering, and stationary turning; in the low gear range, the hydraulic motor displacement is locked at a slightly higher level, and smooth start and low-speed cruising are achieved only through variable pump adjustment.

[0015] Furthermore, both the variable pump unit and the hydraulic motor are electro-hydraulic proportional control type axial piston elements, and their displacement is achieved by driving a proportional electromagnet with a 0-2A continuously adjustable current signal output by the controller. The system is equipped with a current feedback verification module to monitor the deviation between the command current and the actual current in real time. If the deviation exceeds ±5% for a continuous period, fault-tolerant control is activated and a fault code is recorded.

[0016] A flatbed vehicle travel power control system for implementing the control method as described in any one of claims 1 to 9, characterized in that it comprises: engine; The variable pump unit connected to the engine constitutes a closed hydraulic circuit; Multiple hydraulic drive units are respectively installed at each axle. Each unit includes a hydraulic motor and an integrated wheel-side planetary reducer. The hydraulic motor receives hydraulic energy through a high-pressure oil circuit and drives the wheel to rotate. The accelerator pedal, brake pedal, and operating mode selection lever are used to input the driver's operating intentions; Multiple sensors, including engine speed sensor, hydraulic system pressure sensor, and vehicle speed sensor; An electronic controller, communicatively connected to the aforementioned components, is programmed to execute the steps of the method described in claim 1; The electronic controller achieves dynamic power matching of the engine-hydraulic system by independently adjusting the control current of the variable pump unit and each hydraulic motor, without relying on any mechanical linkage adjustment mechanism.

[0017] Due to the adoption of the above technical solution, the technical progress achieved by this invention includes the following aspects: 1. A throttle interval intelligent division method based on hysteresis logic was implemented, and a dual-threshold hysteresis mechanism was introduced to avoid frequent switching of control modes at critical points, thereby improving system stability and driving smoothness; 2. Adopt a dynamic torque matching control strategy for the engine-hydraulic system and construct Me(n). The comparison closed loop between Mf and Mp adjusts the pump / motor displacement according to priority, achieving efficient power utilization and overload protection. 3. Establish a multi-condition adaptive and collaborative control architecture, integrating condition mode selection, signal filtering, speed ramp management and fault early warning, to form an intelligent control system for all scenarios of heavy flatbed truck applications. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments 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 these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the control method of the present invention; Figure 2 This is the walking power matching process according to an embodiment of the present invention; Figure 3 This is a flowchart illustrating the operation of the control system of the present invention. Figure 4 This is a top view of the hydraulic system according to an embodiment of the present invention; Figure 5 This is a side view of the hydraulic system according to an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, in the following description, specific details such as particular system structures and technologies are set forth for illustrative purposes rather than for limiting purposes, in order to provide a thorough understanding of the embodiments of the present invention. However, those skilled in the art should understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary details.

[0021] Example 1 According to the instruction manual Figure 1 It can be seen that this embodiment is a method and system for controlling the traveling power of a flatbed truck, specifically as follows: A method for controlling the traveling power of a flatbed truck, characterized by comprising the following steps: S1. Acquire the accelerator pedal depth signal and the operating mode selection signal. The operating modes include creep mode, no-load mode, and heavy-load mode. The operating mode is input to the electronic controller via the operating lever. The controller configures the corresponding set of control parameters according to different modes: in creep mode, the maximum pump displacement output is limited and the speed ramp is turned off; in heavy-load mode, the power output limit is relaxed and the cooling system is activated for forced heat dissipation; in no-load mode, the low speed-high displacement combination is prioritized to optimize fuel consumption. S2. Divide the control range according to the pedaling depth: When the pedaling depth is less than or equal to the first threshold, enter the low-speed range and execute low-speed fine control; when it is greater than the second threshold, enter the high-speed range and start the high-power output strategy. The first threshold is 30% and the second threshold is 35%. A hysteresis transition zone with a width of not less than 5% is set between the two. The controller determines the switching threshold according to the current control range to avoid frequent switching near the critical point, which would cause system oscillation. S3. Real-time acquisition of the current engine speed n, and based on the pre-stored engine external characteristic curve, find the maximum available torque Me(n) at that speed; S4. Calculate the actual required torque Mp of the hydraulic pump = (Vp) ΔPp) / 2π, where Vp is the displacement of the variable pump unit, and ΔPp is the pressure difference between the pump inlet and outlet; S5. Compare Mp with (Me(n)) The relationship between the magnitudes of Mf and Mf is defined as follows: Mf is the calibrable compensation torque that characterizes the power consumption and transmission loss of the accessory. S6. If Mp < (Me(n)) If the displacement of the variable pump unit (Vp) is increased first to improve power utilization, then if there is still excess torque after Vp reaches the upper limit, the displacement of the hydraulic motor is reduced to increase the system pressure difference ΔPp. Increasing the displacement of the variable pump unit means that the controller outputs a PWM current signal to drive the proportional electromagnet and adjust the swashplate angle to increase the oil discharge. When the displacement control current is detected to have reached the maximum allowable value or the feedback position sensor shows that the mechanical limit has been reached, it is determined that Vp has reached the upper limit and the subsequent operation of reducing the displacement of the hydraulic motor is triggered. S7. If Mp > (Me(n)) If Mf), then the hydraulic motor displacement is increased first to reduce the pressure required per unit flow rate and alleviate the system load; if the hydraulic motor displacement is still overloaded after reaching the physical or control limit, then the variable pump unit displacement Vp is reduced to prevent the engine from stalling; if the hydraulic motor displacement is adjusted to full displacement but still cannot satisfy Mp≤(Me(n)), then... When Mf is detected, the controller further reduces the displacement Vp of the variable pump unit to the target safety level and simultaneously issues a visual or audible alarm to prompt the driver to check the load condition or switch to low-speed mode. The initial value of the compensation torque Mf is set as the sum of the power consumption of engine accessories (generator, air compressor, cooling fan) and the friction loss of the transmission system, and is dynamically compensated and corrected during operation based on atmospheric pressure, intake air temperature, and hydraulic oil temperature collected by environmental sensors. When the high-altitude low-oxygen condition is identified, the Mf value is automatically increased to reserve disturbance rejection margin. S8. The acquired ΔPp signal is digitally filtered to suppress transient jumps caused by road surface disturbances. A first-order digital low-pass filter algorithm is used to process the ΔPp signal. The filtering formula is as follows: Where α is the filter coefficient, ranging from 0.7 to 0.95, corresponding to a cutoff frequency of 5 to 10 Hz; k represents the discrete time index of the current control cycle. 1 indicates the previous control cycle. This filtering algorithm is executed cyclically with a cycle of 10 to 20 ms. ΔP before filtering p ; This indicates the result of the filtering process; S9. Dynamically adjust the slope of engine speed rise and fall: there is no slope restriction during the ascent process to ensure rapid response, and a variable slope is set during the descent process, the steepness of which becomes gentler as the brake pedal is pressed deeper; in creep mode, the slope restriction is removed for both acceleration and deceleration to achieve high-precision positioning.

[0022] In the high-speed range, the controller simultaneously adjusts the hydraulic motor control current to achieve independent speed regulation for each wheel set, supporting various complex motion modes such as diagonal driving, figure-eight steering, and stationary turning. In the low-speed range, the hydraulic motor displacement is locked at a slightly higher level, and smooth start and low-speed cruising are achieved only through the variable pump adjustment. Both the variable pump unit and the hydraulic motor are electro-hydraulic proportional control axial piston elements, and their displacement is achieved by driving a proportional electromagnet with a 0-2A continuously adjustable current signal output by the controller. The system is equipped with a current feedback verification module to monitor the deviation between the command current and the actual current in real time. If the deviation exceeds ±5% for a sustained period, fault-tolerant control is activated and a fault code is recorded.

[0023] A flatbed vehicle travel power control system for implementing the control method as described in any one of claims 1 to 9, characterized in that it comprises: engine; The variable displacement pump unit connected to the engine forms a closed hydraulic circuit; Multiple hydraulic drive units are installed at each axle. Each unit includes a hydraulic motor and an integrated wheel-side planetary reducer. The hydraulic motor receives hydraulic energy through a high-pressure oil circuit and drives the wheels to rotate. The accelerator pedal, brake pedal, and operating mode selection lever are used to input the driver's operating intentions; Multiple sensors, including engine speed sensor, hydraulic system pressure sensor, and vehicle speed sensor; An electronic controller, communicatively connected to the aforementioned components, is programmed to execute the method steps of claim 1; The electronic controller achieves dynamic power matching of the engine-hydraulic system by independently adjusting the control current of the variable pump unit and each hydraulic motor, without relying on any mechanical linkage adjustment mechanism.

[0024] The overall effect achieved by Example 1 is as follows: By integrating system-level functions and innovating structural design, intelligent electro-hydraulic collaborative control replaces traditional mechanical linkage, significantly improving system robustness while ensuring high-precision power coordination.

[0025] Example 2 According to the instruction manual Figure 2 and attached Figure 3 It can be seen that this embodiment is a method and system for controlling the traveling power of a flatbed truck, specifically as follows: S11. Obtain the accelerator pedal depth and divide the gear range into low gear range or high gear range accordingly; S12. In the low gear range, only the engine speed and the variable pump unit control current are adjusted; in the high gear range, the engine speed, the variable pump unit control current and the hydraulic motor control current are adjusted simultaneously. S13. Obtain the engine speed n in real time and look up the engine external characteristic curve to get the current maximum output torque M. e (n); S14. Calculate the current output torque M of the hydraulic pump. p = (V p ·ΔP p ) / 2π, where V p For the displacement of the variable pump unit, ΔP p This refers to the pump pressure differential; S15. Compare M p With (M) e (n) The relationship between the magnitudes of M_f and M_f, where M_f is the calibrable auxiliary torque; S16. If M p <(M e (n) If M_f), then first increase the displacement V of the variable pump unit. p V p After reaching the upper limit, reduce the hydraulic motor displacement to increase ΔP. p ; S17. If M p >(M e (n) If M_f), then first increase the displacement of the hydraulic motor to reduce ΔP. p After the hydraulic motor displacement reaches its upper limit, the displacement V of the variable pump unit is reduced. p ; S18. For ΔP pThe signal is filtered to suppress numerical jumps during the adjustment process; S19. Simultaneously execute engine speed control strategies under different conditions: there is no ramp when the engine speed rises, and a ramp is set when it falls. The steepness of the ramp decreases as the brake pedal is pressed deeper. There is no ramp during acceleration and deceleration under creep conditions.

[0026] The flatbed truck's travel control system is controlled by the accelerator pedal. The operating mode of the flatbed truck is adjusted according to the pedal's depressor depth. In low gear, it controls the engine speed and hydraulic pump current. In high gear, in addition to controlling the engine speed and hydraulic pump current, it also controls the hydraulic motor current. By adjusting the motor current, the speed of the reducer is controlled, thus regulating the vehicle's speed. When the vehicle needs to decelerate, releasing the accelerator pedal causes it to decelerate automatically. For a quick stop, pressing the brake pedal brings the vehicle to a rapid halt.

[0027] The accelerator and brake pedals control the engine speed, and the brake pedal also controls the air brake. The small lever controls the forward / reverse direction and the creep, heavy load, and no load gears. The displacement of the hydraulic pump and hydraulic motor is matched and given by the controller according to the road conditions and engine speed. The driver adjusts the working state of the above structures according to actual needs, and the flatbed truck matches the corresponding walking power according to different working states.

[0028] The power matching process is as follows: S21. By referring to the engine's external characteristic curve, we can find that the engine torque at speed n is... ; S22. Hydraulic pump torque , Pump displacement, mL / r; Pump pressure differential, MPa; S23. Engine speed is lower than pump starting speed. The hydraulic pump and motor are not outputting power; the engine speed is greater than or equal to the pump starting speed. The hydraulic pump and motor are calculated and matched according to power output. S24. When satisfied When the engine is at its optimal operating temperature, fuel economy is at its best and energy output is at its maximum. Auxiliary torque, Nm; S25. First, increase the pump displacement. ; After reaching maximum displacement, reduce the motor displacement to make Increase the speed until the motor displacement is at its minimum or the vehicle speed reaches the required level. S26. At this time, first increase the motor displacement, so that Reduce; decrease pump displacement after the motor displacement has reached its maximum. Until the pump displacement is at its minimum; S27. Auxiliary Torque Pump starting speed Light and heavy load vehicle speed All can be calibrated; S28. To prevent numerical jumps, the pump pressure differential... Perform filtering; In addition to the hydraulic system and motor displacement, the traveling power of the flatbed truck is also affected by the engine speed. The engine speed control process is as follows: S31. Engine speed changes proportionally to the accelerator pedal position; S32. Engine speed increase without ramp, set to minimum 1, and increase in real time; S33. The engine speed decreases with a slope, mainly for two reasons: First, to simulate the feeling of driving, the vehicle speed gradually decreases when the accelerator is released, rather than braking suddenly; Second, to ensure that the engine speed is maintained within the range of 1500-1900 r / min during normal driving, at which time the engine power output and torque are more stable, and fuel consumption is lower. The initial slope value can be calibrated, and the slope decreases as the brake pedal is pressed. The greater the angle of the brake pedal, the faster it decreases, until it reaches a minimum of 1. S34. Pneumatic brake when engine speed drops to rated speed The following will be added gradually, at the rated speed. Can be calibrated; S35. The creeping situation is special, requiring slow speed, precise positioning, and no ramps for acceleration and deceleration.

[0029] The overall effect of Embodiment 2 is that controlling the engine's driving power through the accelerator pedal can effectively reduce engine energy loss and fuel consumption, while effectively avoiding the problems of insufficient vehicle power and energy waste.

[0030] Example 3 According to the instruction manual Figure 4 and attached Figure 5 It can be seen that this embodiment is a practical application embodiment of a flatbed truck travel power control method and system, specifically as follows: The flatbed truck adopts a high-strength welded longitudinal and transverse beam frame structure. The longitudinal beams are I-beam profiles with a height of 750mm, arranged on both sides along the length of the vehicle body, and are the main load-bearing components. The transverse beams are evenly distributed between each set of suspensions, forming a stable "well" frame with excellent torsional stiffness, which can effectively protect the central traveling mechanism and hydraulic pipeline system.

[0031] Each axle is mounted under the frame via a balance arm suspension structure, allowing the tires to swing laterally by ±15° around the axle journal to accommodate uneven factory floors or impacts from track joints. Each axle is equipped with two tubeless pneumatic tires, with both inner and outer tires secured to the hub bolts, providing high load-bearing capacity and shock absorption performance.

[0032] This structural feature dictates that the vehicle requires extremely high stability in power output when moving at low speeds and with slight movements. If the control mode is switched frequently, it can easily cause the vehicle body to sway back and forth, affecting the safety of hoisting operations.

[0033] Control-structure coordination mechanism: When the system is in a low-gear range, the controller only adjusts the engine speed and the current of the variable pump unit to keep the hydraulic motor displacement stable at around 60%, avoiding instantaneous acceleration and deceleration of the wheels due to fluctuations in motor response. This strategy is particularly suitable for scenarios where the vehicle is stationary during lifting or slowly moving for docking. Combined with four-point hydraulic support legs to lock the vehicle's posture, it prevents frame twisting or center of gravity shift due to sudden changes in local driving force.

[0034] When the driver presses the accelerator pedal deeply into the high gear range, the system determines that it has entered the high-speed transport mode and then activates the independent current control of each hydraulic motor. Because the vehicle is equipped with 8 independent drive wheel sets, and each wheel-side reducer is directly integrated into the motor output, precise differential adjustment can be achieved in complex movements such as diagonal driving and figure-eight steering.

[0035] By introducing a hysteresis judgment mechanism during the transition from low to high gears, the control mode can be effectively prevented from repeatedly switching due to throttle signal jitter caused by slight road bumps. Actual measurements show that when passing over trench covers or track joints, traditional single-threshold control experiences an average of 4.2 false switches, while the proposed solution reduces this to 0.3, significantly improving the operational stability of the mechanical system and the lifespan of components.

[0036] The overall effect achieved in Example 3 is as follows: By introducing a dual-threshold hysteresis judgment mechanism, the frequent switching of control modes caused by throttle signal fluctuations due to slight driver tremors or road vibrations is effectively avoided, making it suitable for various working conditions requiring high stability.

[0037] Example 4 This embodiment is a practical application of a flatbed truck travel power control method and system. Specifically, the flatbed truck adopts a multi-point support load-bearing method, with the load distributed at two points of contact in the middle or eccentric position of the vehicle body. The frame is connected to each suspension frame through multiple sets of integrated slewing bearing steering mechanisms. Each suspension set can be independently controlled by an electronically controlled proportional valve to adjust the steering angle, supporting various modes such as turning on the spot and diagonal travel.

[0038] The power transmission path is as follows: Engine → Variable displacement pump unit → Hydraulic motors → Planetary gear reducer → Rim → Tire; Due to variations in hydraulic line length, cornering resistance, and the changing ground reaction force of each wheel, the actual required driving torque for each wheel exhibits dynamic deviations. Without adjustment, this can lead to slippage or overloading of some wheelsets, exacerbating tire wear and even causing stress concentration in the frame.

[0039] Torque matching and mechanical protection mechanisms: The control system calculates the total torque demand of the main circuit Mp=(Vp) in real time. ΔPp) / 2π, and compared with the engine's available torque Me(n), dynamically adjust the energy distribution priority: When Mp<(Me(n) Mf) indicates that the engine still has spare power. At this time, the displacement of the variable pump is increased first to improve the flow output; when the pump has reached the upper limit of the electronic control, the system begins to gradually reduce the displacement of the hydraulic motor, so that each motor works in a small displacement, high pressure state, thereby increasing the overall system pressure difference ΔPp and making full use of the remaining torque.

[0040] This process is particularly suitable for starting uphill under full load. For example, when transporting a large transformer up an 8% slope, the initial pump displacement is already close to its maximum, but about 12% of the engine's potential remains untapped. At this point, the controller automatically reduces the displacement of all hydraulic motors to 75%, raising the system pressure from 28MPa to 31.5MPa, increasing traction by about 9% without increasing the engine load.

[0041] When Mp>(Me(n) If Mf), first increase the hydraulic motor displacement to the fully open state to reduce the pressure required per unit flow and reduce the pump load; if this still cannot be met, actively reduce the variable pump displacement to prevent the engine from stalling.

[0042] This mechanism is particularly important during downhill regenerative braking or emergency stops. When a vehicle is fully loaded and the accelerator is released while descending a slope, the hydraulic motor operates as a pump, which may cause a reverse impact on the system. At this time, the controller quickly switches the motor to a high-displacement mode to reduce peak pressure, which, in conjunction with the brake cylinder action, effectively mitigates the impact on the drivetrain and protects the wheel-side reducer gears and connecting flanges.

[0043] In addition, the Mf compensation item is dynamically corrected according to the hydraulic oil temperature: when the oil temperature exceeds 75°C, Mf is automatically increased by 10% to reserve more safety margin and prevent power mismatch caused by the decrease in volumetric efficiency due to high temperature.

[0044] The overall effect achieved in Example 4 is as follows: By comparing Me(n) in real time Mf and Mp prioritize utilizing the pressure difference of the excess torque regulation system, which can release an additional 10% of potential traction during the hill start phase, avoiding the energy waste problem in traditional control and improving overall fuel efficiency.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for controlling the traveling power of a flatbed truck, characterized in that, The method includes the following steps: S1. Acquire the accelerator pedal depth signal and the operating mode selection signal, wherein the operating modes include creep mode, no-load mode, and heavy-load mode; S2. Divide the control range according to the pedal depth: when the pedal depth is less than or equal to a first threshold, enter the low-gear range and execute low-speed fine control; when it is greater than a second threshold, enter the high-gear range and activate the high-power output strategy; S3. Real-time acquisition of the current engine speed n, and based on the pre-stored engine external characteristic curve, find the maximum available torque Me(n) at that speed; S4. Calculate the actual required torque Mp of the hydraulic pump = (Vp ΔPp) / 2π, where Vp is the displacement of the variable pump unit, and ΔPp is the pressure difference between the pump inlet and outlet; S5. Compare Mp with (Me(n)) / 2π. The relationship between the magnitudes of Mf and Mp, where Mf is the calibrable compensable torque characterizing the power consumption and transmission loss of the accessory; S6. If Mp < (Me(n) If Mf), then prioritize increasing the displacement Vp of the variable pump unit to improve power utilization; if there is still excess torque after Vp reaches the allowable upper limit, then reduce the displacement of the hydraulic motor to increase the system pressure difference ΔPp; S7. If Mp>(Me(n)) If Mf), prioritize increasing the hydraulic motor displacement to reduce the pressure required per unit flow rate and alleviate system load; if the hydraulic motor displacement is still overloaded after reaching the physical or control limit, reduce the variable pump unit displacement Vp to prevent engine stall; S8. Perform digital filtering on the collected ΔPp signal to suppress transient jumps caused by road disturbances; S9. Dynamically adjust the engine speed rise and fall slope: there is no slope restriction during the ascent process to ensure rapid response, and a variable slope is set during the descent process, the steepness of which becomes gentler as the brake pedal is pressed deeper; in creep mode, the slope restriction is removed for both acceleration and deceleration to achieve precise positioning.

2. The method for controlling the traveling power of a flatbed truck as described in claim 1, characterized in that, In step S2, the first threshold is 30%, the second threshold is 35%, and a hysteresis transition zone with a width of not less than 5% is set between the two. The controller determines the switching threshold according to the current control area to avoid frequent switching near the critical point, which could cause system oscillation.

3. The method for controlling the traveling power of a flatbed truck as described in claim 1, characterized in that, The operating mode described in step S1 is input to the electronic controller via the operating handle. The controller configures a set of control parameters according to different modes: in creep mode, the maximum pump displacement output is limited and the speed ramp is turned off; in heavy load mode, the power output limit is relaxed and the cooling system is activated for forced heat dissipation; in no-load mode, the low speed-high displacement combination is preferred to optimize specific fuel consumption.

4. The method for controlling the traveling power of a flatbed truck as described in claim 1, characterized in that, In step S6, increasing the displacement of the variable pump unit refers to the controller outputting a PWM current signal to drive a proportional electromagnet, adjusting the swashplate angle to increase the oil displacement. When the displacement control current is detected to have reached the maximum allowable value or the feedback position sensor shows that the mechanical limit has been reached, it is determined that Vp has reached the upper limit, and the subsequent operation of reducing the hydraulic motor displacement is triggered.

5. The method for controlling the traveling power of a flatbed truck as described in claim 1, characterized in that, In step S7, even after the hydraulic motor displacement is adjusted to full displacement, the condition Mp ≤ (Me(n)) still cannot be satisfied. When Mf), the controller further reduces the displacement Vp of the variable pump unit to the target safety level and simultaneously issues a visual or audible alarm to prompt the driver to check the load condition or switch to low-speed mode.

6. The method for controlling the traveling power of a flatbed truck as described in claim 5, characterized in that, The initial value of the compensation torque Mf is set as the sum of the power consumption of engine accessories (generator, air compressor, cooling fan) and the friction loss of the transmission system. During operation, it is dynamically compensated and corrected based on the atmospheric pressure, intake air temperature and hydraulic oil temperature collected by environmental sensors. When the high-altitude low-oxygen condition is identified, the Mf value is automatically increased to reserve disturbance rejection margin.

7. The method for controlling the traveling power of a flatbed truck as described in claim 1, characterized in that, In step S8, a first-order digital low-pass filter algorithm is used to process the ΔPp signal. The filter formula is as follows: Where α is the filter coefficient, ranging from 0.7 to 0.95, corresponding to a cutoff frequency of 5 to 10 Hz; k represents the discrete time index of the current control cycle. 1 indicates the previous control cycle. This filtering algorithm is executed cyclically with a cycle of 10 to 20 ms. ΔP before filtering p ; This indicates the result of the filtering process.

8. The method for controlling the traveling power of a flatbed truck as described in claim 1, characterized in that, In the high gear range, the controller simultaneously adjusts the hydraulic motor control current to achieve independent speed regulation for each wheel set, supporting various complex motion modes such as diagonal driving, figure-eight steering, and stationary turning; in the low gear range, the hydraulic motor displacement is locked at a slightly higher level, and smooth start and low-speed cruising are achieved only through variable pump adjustment.

9. The method for controlling the traveling power of a flatbed truck as described in claim 1, characterized in that, Both the variable pump unit and the hydraulic motor are electro-hydraulic proportional control type axial piston elements. Their displacement is achieved by driving a proportional electromagnet with a 0-2A continuously adjustable current signal output by the controller. The system is equipped with a current feedback verification module to monitor the deviation between the command current and the actual current in real time. If the deviation exceeds ±5% for a continuous period, fault-tolerant control is activated and a fault code is recorded.

10. A flatbed truck travel power control system for implementing the control method as described in any one of claims 1 to 9, characterized in that, include: engine; The variable pump unit connected to the engine constitutes a closed hydraulic circuit; Multiple hydraulic drive units are respectively installed at each axle. Each unit includes a hydraulic motor and an integrated wheel-side planetary reducer. The hydraulic motor receives hydraulic energy through a high-pressure oil circuit and drives the wheel to rotate. The accelerator pedal, brake pedal, and operating mode selection lever are used to input the driver's operating intentions; Multiple sensors, including engine speed sensor, hydraulic system pressure sensor, and vehicle speed sensor; An electronic controller, communicatively connected to the aforementioned components, is programmed to execute the steps of the method described in claim 1; The electronic controller achieves dynamic power matching of the engine-hydraulic system by independently adjusting the control current of the variable pump unit and each hydraulic motor, without relying on any mechanical linkage adjustment mechanism.

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