Wheeled vehicle hydraulic driving system parameter matching method

Abstract

The invention discloses a wheeled vehicle hydraulic driving system parameter matching method. The method comprises the steps that vehicle basic parameters are obtained; according to the vehicle basic parameters, matching calculation is conducted on a vehicle straight driving system and a vehicle steering system, and straight driving pump motor data and steering pump motor data are obtained; and based on the straight driving pump motor data and the steering pump motor data, the optimal matching parameters of the vehicle hydraulic driving system are obtained. According to the method, the parameter design requirements of the straight driving and steering system of the pure hydraulic driving wheeled vehicle can be met, the performance indexes of the pure hydraulic driving wheeled vehicle are guaranteed, and the performance of the pure hydraulic driving wheeled vehicle is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle drive systems, and particularly relates to a method for parameter matching of a hydraulic drive system for wheeled vehicles. Background Art

[0002] Vehicle hydraulic drive technology uses components such as hydraulic pumps and hydraulic motors to construct a drive system, achieving stepless speed change, making the performance matching between the engine and the load better, and effectively improving the comprehensive energy utilization efficiency. It has broad application prospects in the field of off-road vehicles.

[0003] The hydraulic drive system for wheeled vehicles uses components such as hydraulic pumps and hydraulic motors to construct a vehicle drive system to achieve straight driving and steering. The change in the drive mode will affect the parameter design requirements of the vehicle's straight driving and steering systems, and the non-linear characteristics of the hydraulic drive system lead to multi-objective coupling problems in its parameter matching process. First, the displacement selection of the hydraulic motor needs to simultaneously meet dynamic performance indicators such as maximum traction force and maximum vehicle speed; second, the hydraulic pump needs to simultaneously meet the requirements of the engine's maximum power and the maximum flow demand of the hydraulic motor; in addition, the steering hydraulic pump motor needs to simultaneously meet the differential requirements of the inner and outer wheels and the steering load under steering conditions. Therefore, a method for parameter matching of a hydraulic drive system for wheeled vehicles needs to be proposed to achieve the performance indicators of a pure hydraulic drive wheeled vehicle. Summary of the Invention

[0004] To solve the above technical problems, the present invention proposes a method for parameter matching of a hydraulic drive system for wheeled vehicles, which can meet the parameter design requirements of the straight driving and steering systems of a pure hydraulic drive wheeled vehicle, ensure the realization of the performance indicators of a pure hydraulic drive wheeled vehicle, and further improve the performance of a pure hydraulic drive vehicle.

[0005] The present invention provides a method for parameter matching of a hydraulic drive system for wheeled vehicles, including:

[0006] Obtain the basic parameters of the vehicle;

[0007] According to the basic parameters of the vehicle, perform matching calculations on the vehicle's straight driving system and the vehicle's steering system respectively to obtain the data of the straight driving pump motor and the data of the steering pump motor;

[0008] Based on the data of the straight driving pump motor and the data of the steering pump motor, obtain the optimal matching parameters of the vehicle's hydraulic drive system.

[0009] Optionally, the basic parameters of the vehicle include: engine power, engine torque, vehicle mass, vehicle driving resistance, and vehicle wheel parameters.

[0010] Optionally, according to the basic parameters of the vehicle, performing matching calculations on the vehicle's straight driving system and the vehicle's steering system respectively to obtain the data of the straight driving pump motor and the data of the steering pump motor includes:

[0011] According to the vehicle basic parameters, perform matching calculations on the vehicle straight - driving system and the vehicle steering system respectively to obtain the rated pressure and displacement of the straight - driving pump motor, and the rated pressure and displacement of the steering pump motor.

[0012] Optionally, according to the vehicle basic parameters, perform a matching calculation on the vehicle straight - driving system to obtain the rated pressure and displacement of the straight - driving pump motor and the maximum speed of the straight - driving pump motor, including:

[0013] Based on the vehicle basic parameters, calculate the torque requirement of the straight - driving motor and the speed requirement of the straight - driving motor;

[0014] Based on the torque requirement of the straight - driving motor and the speed requirement of the straight - driving motor, calculate the matching parameters of the straight - driving motor;

[0015] Based on the vehicle basic parameters, calculate the speed requirement of the straight - driving pump and the torque requirement of the straight - driving pump;

[0016] Based on the speed requirement of the straight - driving pump and the torque requirement of the straight - driving pump, match the flow rate of the straight - driving pump motor to obtain the matching parameters of the straight - driving pump;

[0017] Based on the matching parameters of the straight - driving motor and the matching parameters of the straight - driving pump, obtain the rated pressure and displacement of the straight - driving pump motor and the maximum speed of the straight - driving pump motor.

[0018] Optionally, obtaining the displacement of the straight - driving pump motor includes:

[0019] Based on the matching parameters of the straight - driving motor and the matching parameters of the straight - driving pump, determine the torque data at the maximum vehicle speed and the torque data when the vehicle is climbing the maximum slope;

[0020] Based on the torque data when the vehicle is climbing the maximum slope, determine the first displacement data of the straight - driving pump motor:

[0021] Based on the torque data at the maximum vehicle speed, determine the second displacement data of the straight - driving pump motor;

[0022] According to the first displacement data of the straight - driving pump motor and the second displacement data of the straight - driving pump motor, obtain the displacement data of the straight - driving pump motor.

[0023] Optionally, the method for obtaining the rated pressure and displacement of the straight - driving pump motor and the maximum speed of the straight - driving pump motor is:

[0024] Based on the vehicle basic parameters, calculate the torque requirement of the straight - driving motor:

[0025]

[0026] Based on the vehicle basic parameters, calculate the speed requirement of the straight - driving motor:

[0027]

[0028] Calculate the straight-ahead motor matching parameters based on the straight-ahead motor torque requirement and the straight-ahead motor speed requirement:

[0029] V m,max = max(V m,max1 , V m,max2 )

[0030] Calculate the straight-ahead pump speed requirement based on the vehicle basic parameters:

[0031]

[0032] Calculate the straight-ahead pump torque requirement based on the vehicle basic parameters:

[0033]

[0034] Match the straight-ahead pump motor flow based on the straight-ahead pump speed requirement and the straight-ahead pump torque requirement, and obtain the straight-ahead pump matching parameters:

[0035]

[0036] where, T m,vmax is the maximum output torque of the hydraulic motor at the maximum vehicle speed, v max is the maximum vehicle speed required by the index, i m , i0 are the output reduction ratio of the hydraulic motor and the main reduction ratio respectively, η m , η0 are the corresponding transmission efficiencies, r w is the wheel radius, f r is the ground deformation resistance coefficient, C d is the air resistance coefficient, A is the vehicle frontal area, T mmax is the maximum output torque of the hydraulic motor, θ is the slope angle, n m max is the maximum speed of the hydraulic motor, V m，max is the maximum value of the motor displacement, V m，max1 is the first calculated value of the maximum displacement of the straight-ahead motor, V m，max2 is the second calculated value of the maximum displacement of the straight-ahead motor, n p max is the maximum speed of the hydraulic pump, n e max is the maximum speed of the engine, i e is the engine output reduction ratio, T p max is the maximum input torque of the hydraulic pump, V p max is the maximum displacement of the hydraulic pump, Δp is the system pressure difference, T emax is the maximum output torque of the engine, η pm is the mechanical efficiency of the straight-ahead hydraulic pump, η eis the mechanical efficiency of the engine, T emax is the maximum torque of the engine, V p，max1 is the first calculated value of the maximum displacement of the straight-ahead pump, V p，max2 is the second calculated value of the maximum displacement of the straight-ahead pump, V p，max is the final calculated value of the maximum displacement of the straight-ahead pump, n e Rated is the rated speed of the engine, η mv is the volumetric efficiency of the straight-ahead hydraulic motor, η pv is the volumetric efficiency of the straight-ahead hydraulic pump, n e max is the maximum speed of the engine, V m max is the final calculated value of the maximum displacement of the motor.

[0037] Optionally, according to the basic vehicle parameters, perform a matching calculation on the vehicle steering system to obtain the rated pressure and displacement of the steering pump motor, including:

[0038] Based on the basic vehicle parameters, combine the longitudinal force model and the lateral force model of the tire to construct a two-degree-of-freedom model;

[0039] According to the two-degree-of-freedom model, obtain the maximum torque and maximum speed of the steering hydraulic motor;

[0040] According to the maximum torque and maximum speed of the steering hydraulic motor, obtain the power data of the steering hydraulic motor;

[0041] Based on the power data of the steering hydraulic motor, combine the characteristics of the conventional pressure level and the fixed-displacement motor to obtain the rated pressure and displacement of the steering pump motor.

[0042] Optionally, the method for constructing the two-degree-of-freedom model is:

[0043]

[0044] Among them, is the lateral speed at the vehicle center of mass; v x is the longitudinal speed at the vehicle center of mass; ω z is the yaw angular velocity about the Z axis at the vehicle center of mass, is the yaw angular acceleration about the Z axis at the vehicle center of mass; F xij and F yij are respectively the longitudinal force and the lateral force of the wheel in the tire coordinate system. i represents the axle number where the wheel is located, j represents the left / right wheel, j = f represents the left wheel, j = r represents the right wheel, I z is the moment of inertia about the Z axis at the vehicle center of mass; L i (i = 1, 2, 3) is the longitudinal distance from each axle to the center of mass, and B is the vehicle width.

[0045] Optionally, obtaining the maximum torque and maximum speed of the steering hydraulic motor according to the two-degree-of-freedom model includes:

[0046] Calculating according to the two-degree-of-freedom model to obtain the steering motor load;

[0047] Based on the steering motor load, obtaining the maximum torque of the steering hydraulic motor through the maximum steering load during neutral steering:

[0048]

[0049] Based on the steering motor load, obtaining the maximum speed of the steering hydraulic motor through the maximum steering angular velocity during neutral steering:

[0050]

[0051] Among them, T Msmax is the maximum output torque of the steering motor, i zM and i zd are the transmission ratios from the steering motor to the sun gear, η izM and η izd are the corresponding transmission efficiencies, k is the planetary row characteristic parameter, η h is the transmission efficiency of the confluence planetary row, i c is the side transmission ratio, η c is the side transmission efficiency, η xd is the transmission efficiency of the crawler running system, r is the wheel radius, Δv max is the maximum value of the speed difference between the two side wheels, T sl空档 is the neutral steering load.

[0052] Compared with the prior art, the present invention has the following advantages and technical effects: The present invention provides a parameter matching method for a hydraulic drive system of a wheeled vehicle, realizing the functional matching between the straight-ahead hydraulic pump and the engine, the straight-ahead hydraulic pump and the straight-ahead hydraulic motor, the straight-ahead hydraulic motor and the straight-ahead vehicle index, and the steering hydraulic motor and the steering load. The present invention comprehensively considers the torque and speed requirements of the straight-ahead hydraulic motor for the maximum vehicle speed and maximum climbing gradient, reasonably selects the rated pressure and displacement parameters of the straight-ahead hydraulic motor, and combines the rotational speed limit of the mechanical connection between the hydraulic pump and the engine to give full play to the engine power on the premise of meeting the maximum flow rate of the straight-ahead hydraulic motor; for the vehicle steering condition, the present invention establishes a two-degree-of-freedom model of the vehicle's lateral movement and yaw movement, obtains the calculation expression of the steering load, and further designs and matches a steering hydraulic pump-motor circuit with sufficient power. The present invention improves the performance of a pure hydraulic drive wheeled vehicle, is an important guarantee for ensuring the realization of the performance indicators of a pure hydraulic drive wheeled vehicle, and is also the basis for realizing the forward design of the vehicle drive system. Description of the Drawings

[0053] The accompanying drawings, which form a part of this application, are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the accompanying drawings:

[0054] Figure 1 is the schematic diagram of the system structure of the embodiment of the present invention;

[0055] Figure 2 is the schematic diagram of the two-degree-of-freedom model of the skid-steering wheeled vehicle of the embodiment of the present invention;

[0056] Figure 3 is the flowchart of the parameter matching method for the hydraulic drive system of a wheeled vehicle of the embodiment of the present invention. Detailed implementation manners

[0057] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the accompanying drawings and combine the embodiments to detail this application.

[0058] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0059] The present invention proposes a parameter matching method for the hydraulic drive system of a wheeled vehicle, as Figure 3 shown, which specifically includes the following steps:

[0060] Obtain the basic parameters of the vehicle;

[0061] According to the basic parameters of the vehicle, perform matching calculations on the vehicle straight-driving system and the vehicle steering system respectively to obtain the straight-driving pump motor data and the steering pump motor data;

[0062] Based on the straight-driving pump motor data and the steering pump motor data, obtain the optimal matching parameters of the vehicle hydraulic drive system.

[0063] Furthermore, the basic parameters of the vehicle include: engine power, engine torque, vehicle mass, vehicle driving resistance, vehicle wheel parameters, maximum vehicle driving speed, motor output reduction ratio of the vehicle transmission system, main reduction ratio, engine output reduction ratio and their corresponding transmission efficiencies, engine rated speed and maximum speed, minimum vehicle turning time and maximum angular velocity.

[0064] Furthermore, according to the basic parameters of the vehicle, performing matching calculations on the vehicle straight-driving system and the vehicle steering system respectively to obtain the straight-driving pump motor data and the steering pump motor data includes:

[0065] According to the basic vehicle parameters, the straight - driving system and the vehicle steering system of the vehicle are respectively matched and calculated to obtain the rated pressure and displacement of the straight - driving pump motor, the maximum speed of the straight - driving pump motor, the rated pressure and displacement of the steering pump motor, and the maximum speed of the steering pump motor.

[0066] Further, according to the basic vehicle parameters, the straight - driving system of the vehicle is matched and calculated to obtain the rated pressure and displacement of the straight - driving pump motor and the maximum speed of the straight - driving pump motor, including:

[0067] Based on the basic vehicle parameters, calculate the torque requirement of the straight - driving motor and the speed requirement of the straight - driving motor;

[0068] Based on the torque requirement of the straight - driving motor and the speed requirement of the straight - driving motor, calculate the matching parameters of the straight - driving motor;

[0069] Based on the basic vehicle parameters, calculate the speed requirement of the straight - driving pump and the torque requirement of the straight - driving pump;

[0070] Based on the speed requirement of the straight - driving pump and the torque requirement of the straight - driving pump, match the flow rate of the straight - driving pump motor to obtain the matching parameters of the straight - driving pump;

[0071] Based on the matching parameters of the straight - driving motor and the matching parameters of the straight - driving pump, obtain the rated pressure and displacement of the straight - driving pump motor and the maximum speed of the straight - driving pump motor.

[0072] Further, obtaining the displacement of the straight - driving pump motor includes:

[0073] Based on the matching parameters of the straight - driving motor and the matching parameters of the straight - driving pump, determine the torque data at the maximum vehicle speed and the torque data when the vehicle is climbing the maximum slope;

[0074] Based on the torque data when the vehicle is climbing the maximum slope, determine the first displacement data of the straight - driving pump motor:

[0075] Based on the torque data at the maximum vehicle speed, determine the second displacement data of the straight - driving pump motor;

[0076] According to the first displacement data of the straight - driving pump motor and the second displacement data of the straight - driving pump motor, obtain the displacement data of the straight - driving pump motor.

[0077] Further, according to the basic vehicle parameters, the vehicle steering system is matched and calculated to obtain the rated pressure and displacement of the steering pump motor, including:

[0078] Based on the basic vehicle parameters, combine the longitudinal force model and the lateral force model of the tire to construct a two - degree - of - freedom model;

[0079] According to the two - degree - of - freedom model, obtain the maximum torque and maximum speed of the steering hydraulic motor;

[0080] According to the maximum torque and maximum speed of the steering hydraulic motor, obtain the power data of the steering hydraulic motor;

[0081] Based on the power data of the steering hydraulic motor, combined with the characteristics of the conventional pressure level and the fixed displacement motor, the rated pressure and displacement of the steering pump motor are obtained.

[0082] The following elaborates on this embodiment in detail with reference to the accompanying drawings:

[0083] The research object of this embodiment is a pure hydraulic drive wheeled vehicle, and the basic principles of the pure hydraulic drive and steering system of the vehicle are as Figure 1 shown.

[0084] The vehicle is a pure hydraulic drive wheeled vehicle, and its power transmission system mainly consists of an engine, a front transmission, a straight drive hydrostatic continuously variable transmission system, a steering drive hydrostatic continuously variable transmission system, a manifold, and other reduction mechanisms. The power output by the engine is respectively output to the ring gear and the sun gear of the manifold through the straight drive hydraulic circuit and the steering hydraulic circuit. When going straight, the engine power passes through the straight drive hydraulic pump, the hydraulic pump converts mechanical energy into hydraulic energy, and then through the hydraulic motor into mechanical energy. The power output by the motor passes through the mechanical reduction mechanism and is input to the ring gear of the planetary gear set of the manifold. When steering, the engine output power also passes through the reduction mechanism and is input to the steering hydrostatic continuously variable transmission circuit, and the power output by the steering hydraulic motor is sent to the sun gear of the manifold. The rotational speeds of the sun gears on both sides of the manifold planetary gear set are equal in magnitude and opposite in direction, and the planet carrier serves as the final drive output. When the displacement of the steering pump is 0, the output rotational speed of the steering hydraulic motor is 0, and the output rotational speeds of the two planet carriers in the manifold are equal, and the vehicle goes straight; when the displacement of the steering hydraulic pump is not 0, the rotational speeds of the two sun gears are equal in magnitude and opposite in direction, and a speed difference is formed between the rotational speeds of the two wheels, and the vehicle steers. In addition, when the displacement of the straight drive hydraulic pump is 0, the vehicle can achieve a 360° in-situ turn.

[0085] 1 Vehicle straight drive system matching calculation:

[0086] The straight drive system matching calculation includes the matching of the straight drive motor, the straight drive pump, and the engine.

[0087] (1) Matching of the straight drive motor:

[0088] The maximum vehicle speed refers to the highest speed that the vehicle can reach on a good straight road surface. Ignoring the acceleration resistance and the climbing resistance, the vehicle is mainly subject to the rolling resistance and the air resistance. The torque requirement of the hydraulic motor is:

[0089]

[0090] In the formula, T m,vmax is the maximum output torque of the hydraulic motor at the maximum vehicle speed, v max is the maximum vehicle speed required by the index, i m, \(i_0\) are the output reduction ratio of the hydraulic motor and the main reduction ratio respectively, and \(\eta\) m , \(\eta_0\) are the corresponding transmission efficiencies.

[0091] When the vehicle is climbing the maximum slope, the vehicle speed is generally slow, and the air resistance can be ignored. The vehicle is mainly subject to rolling resistance and gradient resistance. The torque requirement of the hydraulic motor when the vehicle is climbing is as follows:

[0092]

[0093] In the formula, \(T\) mmax is the maximum output torque of the hydraulic motor.

[0094] At the same time, the hydraulic motor needs to meet the speed requirement, that is, the following relationship exists between the motor speed and the vehicle speed:

[0095]

[0096] In the formula, \(n\) mmax is the maximum speed of the hydraulic motor.

[0097] The torque of the hydraulic motor is proportional to the displacement and pressure of the hydraulic motor. Assuming that the pressure of the hydraulic system is constant, the hydraulic motor obtains the maximum driving torque at the maximum displacement, and the maximum speed of the hydraulic motor is generally obtained at the minimum working displacement. To prevent the efficiency from being too low when the displacement ratio of the motor is too small, the minimum displacement ratio is set to \(\varepsilon_{min}\).

[0098] The maximum torque of the hydraulic motor is:

[0099]

[0100] The torque output by the hydraulic motor at the maximum vehicle speed is:

[0101]

[0102] It can be seen that for a certain maximum torque requirement, the higher the system pressure, the smaller the required hydraulic motor displacement. However, the higher the pressure, the stricter the sealing of the hydraulic system. Therefore, the maximum displacement of the motor is taken as the maximum value in formula (4) and formula (5):

[0103] \(V\) m,max = max(\(V\) m,max1 , \(V\) m,max2 )(6)

[0104] From formula (1) - formula (6), the following constraint conditions can be obtained:

[0105]

[0106] (2) Matching calculation of the straight - driving hydraulic pump and the engine:

[0107] For the selection of a hydraulic pump, the power requirement must be met first. To fully utilize the power of the engine, the power P of the hydraulic pump pmax must be greater than the maximum power P of the engine emax , that is

[0108] P pmax ≥P emax (8)

[0109] Since there is a mechanical connection between the hydraulic pump and the engine, the rotational speed requirement must be met, that is, the maximum rotational speed n of the hydraulic pump pmax needs to meet the following conditions:

[0110]

[0111] where n emax is the maximum rotational speed of the engine, and i e is the engine output reduction ratio.

[0112] To meet the power requirement, the relationship between the maximum torque of the hydraulic pump and the maximum torque of the engine needs to meet the following conditions:

[0113]

[0114] where T pmax is the maximum input torque of the hydraulic pump, V pmax is the maximum displacement of the hydraulic pump, Δp is the system pressure difference, and T emax is the maximum output torque of the engine.

[0115] The maximum output flow of the hydraulic pump is taken at its rated rotational speed and maximum displacement. The rated rotational speed of the hydraulic pump is determined by the rated rotational speed of the engine, that is, the maximum flow of the hydraulic pump is:

[0116]

[0117] where q p , V p are the pump output flow and displacement respectively, n e is the engine rotational speed, and η pv is the volumetric efficiency of the hydraulic pump.

[0118] For a hydraulic motor, the engine and the hydraulic pump can be regarded as a whole. The maximum output flow of the hydraulic pump needs to meet the maximum flow demand of the hydraulic motor. Generally, the flow demand of the hydraulic motor is the largest at the highest vehicle speed, that is, the maximum output flow of the hydraulic pump should meet:

[0119]

[0120] From equations (8) - (12), the following constraint conditions can be obtained:

[0121]

[0122] (3) Matching calculation of the straight - driving hydraulic pump and motor:

[0123] The conventional pressure ratings of the pump - motor can be selected as 40 Mpa and 30 Mpa, that is, the rated pressure ratings of the pump and motor can be selected as 40 Mpa and 30 Mpa.

[0124] Determine the displacement and maximum speed data of the straight - driving hydraulic pump and the straight - driving hydraulic motor from Equation (7) and Equation (13).

[0125] 2 Vehicle steering system matching calculation:

[0126] The steering system matching calculation includes the matching of the rated pressure ratings, displacements, and maximum speeds of the steering motor and the steering pump:

[0127] (1) Vehicle steering dynamics model:

[0128] In this vehicle's hydraulic drive scheme, driving and steering are achieved through the wheel speed difference output by the transmission system. Therefore, in this embodiment, a vehicle steering dynamics model with rotational speed as the input is established. As follows Figure 2 As shown, the two - degree - of - freedom model of the vehicle's lateral motion and yaw motion during steering is:

[0129]

[0130] In the formula: v y is the lateral speed at the vehicle's center of mass; v x is the longitudinal speed at the vehicle's center of mass; ω z is the yaw angular velocity about the Z - axis at the vehicle's center of mass; F xij and F yij are the longitudinal force and lateral force of the wheel in the tire coordinate system respectively (for the sake of convenience in representation, in this embodiment, in the subscript ij, i represents the axle number where the wheel is located, j represents the left / right wheel, j = f represents the left wheel, j = r represents the right wheel); I z is the moment of inertia about the Z - axis at the vehicle's center of mass; Li (i = 1, 2, 3) is the longitudinal distance from each axle to the center of mass, with the axle in front of the center of mass being positive and behind the center of mass being negative; B is the vehicle width. XOY is the vehicle body coordinate system as Figure 2 shown.

[0131] The longitudinal force model of the tire is:

[0132]

[0133] In the formula: K xil and K xir are the longitudinal stiffnesses of the left and right wheels of the i - th axle respectively; sil and s ir are the longitudinal slip ratios of the left and right wheels of the i-th axle respectively.

[0134] The lateral force model of the tire is:

[0135]

[0136] In the formula, K yil and K yir are the lateral stiffnesses of the left and right wheels of the i-th axle respectively; α il and α ir are the sideslip angles of the left and right wheels of the i-th axle respectively.

[0137] Assume that the longitudinal stiffness and lateral stiffness of the left and right wheels of each axle of the vehicle are equal, that is:

[0138] K xil = K xir = K xi

[0139] K yil = K yir = K yi (17)

[0140] Substitute equations (16), (17), and (18) into equation (15), and we can get

[0141]

[0142] In the formula: K yi and K xi are the lateral and longitudinal stiffnesses of the wheels of the i-th axle respectively; β is the sideslip angle of the vehicle's center of mass in motion, β = v y / v x .

[0143] At this time, the load of the steering motor is:

[0144]

[0145] (2) Matching calculation of steering system parameters:

[0146] 1) Matching of steering motor torque:

[0147] The maximum torque of the steering hydraulic motor should be greater than the maximum load of vehicle steering, that is:

[0148] T Msmax i zM i zd (1 + k)i c η izM η izd η h η c η xd≥T slmax (20)

[0149] Wherein, T Msmax is the maximum output torque of the steering motor, with the unit of N·m, i zM and i zd are the transmission ratios from the steering motor to the sun gear, η izM and η izd are the corresponding transmission efficiencies, k is the characteristic parameter of the planetary gear set, η h is the transmission efficiency of the confluence planetary gear set, i c is the side transmission ratio, η c is the side transmission efficiency, η xd is the transmission efficiency of the crawler running system.

[0150] During neutral steering, all the power of the vehicle is transmitted only through the steering. When performing neutral steering on the most difficult road surface, the steering load T sl is the largest. At this time, the driving forces of the inner and outer tracks are both output as traction forces for power. Therefore, the maximum output torque T Msmax of the hydraulic steering motor should be determined according to this working condition, and a safety factor δ (δ > 1) is given as follows:

[0151]

[0152] The maximum output torque of the hydraulic steering motor can be determined according to the above formulas (20) and (22).

[0153] 2) Matching of the steering motor speed:

[0154] This solution belongs to a differential two-flow steering mechanism, and the speed change is stepless. Therefore, the highest vehicle speed corresponding to a certain transmission ratio and the maximum specified steering radius of this transmission ratio satisfy:

[0155]

[0156] The above formula shows that the ratio of υ imax and R ig is the maximum angular velocity ω imax of the vehicle. Assuming that the volumetric efficiency of the hydraulic system is a constant value during the steering process, the maximum angular velocity of the vehicle is a constant value, which has nothing to do with the straight-ahead transmission ratio:

[0157]

[0158] Wherein, t min is the minimum turnover time.

[0159] Δυ max = 3.6Bω imax (24)

[0160] Wherein, △υmax is the maximum value of the speed difference between the two side wheels.

[0161] Therefore, the maximum rotational speed of the hydraulic steering motor required during steering is:

[0162]

[0163] Furthermore, the maximum power output of the motor required for steering is determined by the following formula:

[0164]

[0165] In the formula, P Mmax is the maximum power output of the motor required for steering, with the unit of kW.

[0166] (3) Matching of the displacement and rated pressure of the steering motor:

[0167] Since the steering hydraulic motor is a fixed-displacement motor, and the torque of the hydraulic motor is proportional to the displacement and pressure of the hydraulic motor, the displacement of the steering hydraulic motor is determined by the following formula:

[0168]

[0169] Conventional pressure grades can be 40 Mpa and 30 Mpa. Generally, the parameters of the steering hydraulic pump and the steering hydraulic motor are the same.

[0170] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A parameter matching method for a wheeled vehicle hydraulic drive system, characterized in that: include: Get basic vehicle parameters; According to the basic parameters of the vehicle, matching calculations are performed on the vehicle direct driving system and the vehicle steering system respectively to obtain direct driving pump motor data and steering pump motor data; Based on the direct driving pump motor data and the steering pump motor data, optimal matching parameters of the vehicle hydraulic drive system are obtained.

2. A parameter matching method for a wheeled vehicle hydraulic drive system according to claim 1, characterized in that: The basic vehicle parameters include: engine power, engine torque, vehicle mass, vehicle driving resistance, vehicle wheel parameters, vehicle maximum driving speed, vehicle transmission system motor output reduction ratio, main reduction ratio, engine output reduction ratio and its corresponding transmission efficiency, engine rated speed and maximum speed, vehicle minimum turnover time and maximum angular velocity.

3. A parameter matching method for a wheeled vehicle hydraulic drive system according to claim 1, characterized in that: According to the basic parameters of the vehicle, matching calculations are performed on the vehicle direct driving system and the vehicle steering system respectively, and the direct driving pump motor data and the steering pump motor data are obtained, including: According to the basic parameters of the vehicle, the vehicle direct driving system and the vehicle steering system are matched and calculated respectively to obtain the rated pressure and displacement of the direct driving pump motor and the maximum speed of the direct driving pump motor, the rated pressure and displacement of the steering pump motor and the maximum speed of the steering pump motor.

4. A parameter matching method for a wheeled vehicle hydraulic drive system according to claim 3, characterized in that: According to the basic parameters of the vehicle, the vehicle direct drive system is matched and calculated to obtain the rated pressure and displacement of the direct drive pump motor and the maximum speed of the direct drive pump motor, including: Based on the basic parameters of the vehicle, calculating the torque requirement of the direct-drive motor and the speed requirement of the direct-drive motor; Calculating a direct-drive motor matching parameter based on the direct-drive motor torque requirement and the direct-drive motor speed requirement; Based on the basic parameters of the vehicle, calculating a direct-drive pump speed requirement and a direct-drive pump torque requirement; Based on the direct-drive pump speed requirement and the direct-drive pump torque requirement, matching the direct-drive pump motor flow rate to obtain direct-drive pump matching parameters; Based on the direct-drive motor matching parameters and the direct-drive pump matching parameters, the rated pressure and displacement of the direct-drive pump motor and the maximum speed of the direct-drive pump motor are obtained.

5. A parameter matching method for a wheeled vehicle hydraulic drive system according to claim 4, characterized in that: Get direct drive pump motor displacement including: Determining torque data at the maximum speed of the vehicle and torque data at the maximum climbing grade of the vehicle based on the direct-drive motor matching parameters and the direct-drive pump matching parameters; Based on the torque data of the vehicle at the maximum climbing grade, the displacement data of the first straight-running pump motor is determined: determining the displacement data of the second direct-drive pump motor based on the torque data at the maximum speed of the vehicle; The direct-drive pump motor displacement data is acquired according to the first direct-drive pump motor displacement data and the second direct-drive pump motor displacement data.

6. A parameter matching method for a wheeled vehicle hydraulic drive system according to claim 4, characterized in that: The method for obtaining the rated pressure and displacement of the direct-drive pump motor and the maximum speed of the direct-drive pump motor is: Based on the basic vehicle parameters, the direct drive motor torque requirement is calculated: Based on the basic parameters of the vehicle, the speed requirement of the direct driving motor is calculated: Based on the direct-drive motor torque requirement and the direct-drive motor speed requirement, the direct-drive motor matching parameters are calculated: V m,max =max(V m,max1 ,V m,max2 ) Based on the basic vehicle parameters, calculate the direct drive pump speed requirement: Based on the basic vehicle parameters, the direct drive pump torque requirement is calculated: Based on the direct-drive pump speed requirement and the direct-drive pump torque requirement, the direct-drive pump motor flow is matched to obtain the direct-drive pump matching parameters: Among them, T m,vmax is the maximum output torque of the hydraulic motor at the highest vehicle speed, v max is the maximum vehicle speed required by the indicator, i m and i0 are the hydraulic motor output reduction ratio and the main reduction ratio respectively, η m , η0 are the corresponding transmission efficiencies, r w is the wheel radius, f r is the ground deformation resistance coefficient, C d is the air resistance coefficient, A is the frontal area of ​​the vehicle, T mmax is the maximum output torque of the hydraulic motor, θ is the slope angle, n mmax is the maximum speed of the hydraulic motor, V m，max is the maximum displacement of the motor, V m，max1 is the first calculated value of the maximum displacement of the direct-drive motor, V m，max2 is the second calculated value of the maximum displacement of the direct-drive motor, n pmax is the maximum speed of the hydraulic pump, n emax is the maximum engine speed, i e is the engine output reduction ratio, T pmax is the maximum input torque of the hydraulic pump, V pmax is the maximum displacement of the hydraulic pump, Δp is the system pressure difference, T emax is the maximum output torque of the engine, η pm is the mechanical efficiency of the direct-drive hydraulic pump, η e is the engine mechanical efficiency, T emax is the maximum torque of the engine, V p，max1 is the first calculated value of the maximum displacement of the direct-drive pump, V p，max2 is the second calculated value of the maximum displacement of the direct-drive pump, V p，max is the final calculated value of the maximum displacement of the direct-drive pump, n eRaied is the rated speed of the engine, η mv is the volumetric efficiency of the direct-drive hydraulic motor, η pv is the volumetric efficiency of the direct-drive hydraulic pump, n emax is the maximum engine speed, V mmax This is the final calculated value of the motor's maximum displacement.

7. A parameter matching method for a wheeled vehicle hydraulic drive system according to claim 3, characterized in that: According to the basic parameters of the vehicle, the vehicle steering system is matched and calculated to obtain the rated pressure and displacement of the steering pump motor, including: Based on the basic vehicle parameters, a two-degree-of-freedom model is constructed in combination with a tire longitudinal force model and a lateral force model; According to the two-degree-of-freedom model, obtaining the maximum torque and maximum speed of the steering hydraulic motor; Acquiring power data of the steering hydraulic motor according to the maximum torque and maximum speed of the steering hydraulic motor; Based on the steering hydraulic motor power data and in combination with the characteristics of conventional pressure levels and fixed displacement motors, the rated pressure and displacement of the steering pump motor are obtained.

8. A parameter matching method for a wheeled vehicle hydraulic drive system according to claim 7, characterized in that: The method to construct a two-degree-of-freedom model is: in, is the lateral velocity at the center of mass of the vehicle; v x is the longitudinal velocity at the center of mass of the vehicle; ω z is the yaw angular velocity around the Z axis at the center of mass of the vehicle, is the yaw angular acceleration around the Z axis at the center of mass of the vehicle; F xij and F yij are the longitudinal force and lateral force of the wheel in the tire coordinate system, i represents the axle number of the wheel, j represents the left / right wheel, j=f represents the left wheel, j=r represents the right wheel, I z is the moment of inertia of the vehicle's center of mass around the Z axis; L i (i=1,2,3) is the longitudinal distance from each axle to the center of mass, and B is the vehicle width.

9. A parameter matching method for a wheeled vehicle hydraulic drive system according to claim 7, characterized in that: According to the two-degree-of-freedom model, obtaining the maximum torque and maximum speed of the steering hydraulic motor includes: Calculate according to the two-degree-of-freedom model to obtain the steering motor load; Based on the steering motor load, the maximum torque of the steering hydraulic motor is obtained through the maximum steering load during neutral steering: Based on the steering motor load, the maximum speed of the steering hydraulic motor is obtained through the maximum steering angular velocity during neutral steering: Among them, T Msmax is the maximum output torque of the steering motor, i zM and i zd is the transmission ratio from the steering motor to the sun gear, η izM and η izd is the corresponding transmission efficiency, k is the characteristic parameter of the planetary gear, η h is the transmission efficiency of the planetary gear, i c is the side transmission ratio, η c is the side transmission efficiency, η xd is the transmission efficiency of the track motion system, r is the wheel radius, Δv max is the maximum speed difference of the wheels on both sides, T sl空挡 Steering load for neutral gear.

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