Vehicle brake control method and device

Abstract

The application provides a vehicle brake control method and device, and belongs to the technical field of driving brake, wherein the method comprises the following steps: collecting the traction motor speed and the lifting cylinder bottom pressure; calculating the vehicle load according to the lifting cylinder bottom pressure; calculating the vehicle rear axle load according to the vehicle load; calculating the maximum torque of the traction motor according to the traction motor speed; calculating the maximum adhesion torque of the driving wheel according to the vehicle load and the vehicle rear axle load; comparing the numerical values of the maximum torque of the traction motor and the maximum adhesion torque of the driving wheel, and taking the smaller one as the maximum given torque; calculating the traction motor regenerative braking torque according to the maximum given torque; and braking the vehicle through the traction motor regenerative braking torque. The application solves the problems that the current brake does not consider the influence of the driving wheel load, leading to brake deviation, and the vehicle state cannot be identified during the braking process, the brake impact is large in the no-load state, and the braking distance is long at high speed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of driving brake control, and particularly relates to a vehicle brake control method and device. BACKGROUND

[0002] The existing station driver type forklift driving brake has the following problems: mechanical brake is adopted, the brake torque is a constant value, and the brake impact is large; or AC motor regenerative brake is adopted, the brake torque is variable, but the brake torque is small at high speed of the vehicle, and the brake distance is long due to the influence of the motor characteristics; the influence of brake on the load of the driving wheel is not considered, the brake force applied to the driving wheel is greater than the adhesion of the driving wheel, and the brake deviation is caused; the vehicle state (whether there is load) cannot be identified, the brake torque is the same under different states of the vehicle, and the brake torque is large under the no-load state, and the brake impact is large. SUMMARY

[0003] To solve the problems in the prior art, the application provides a vehicle brake control method and device.

[0004] In a first aspect, the application provides a vehicle brake control method, comprising:

[0005] Collecting the speed of a traction motor and the bottom pressure of a lifting cylinder;

[0006] Calculating the vehicle load according to the bottom pressure of the lifting cylinder;

[0007] Calculating the load of the rear axle of the vehicle according to the vehicle load;

[0008] Calculating the maximum torque of the traction motor according to the speed of the traction motor;

[0009] Calculating the maximum adhesion torque of the driving wheel according to the vehicle load and the load of the rear axle of the vehicle;

[0010] Comparing the numerical values of the maximum torque of the traction motor and the maximum adhesion torque of the driving wheel, and taking the smaller one as the maximum given torque;

[0011] Calculating the regenerative brake torque of the traction motor according to the maximum given torque;

[0012] Controlling the brake of the vehicle through the regenerative brake torque of the traction motor.

[0013] In a preferred embodiment of the application, the calculation formula of the vehicle load according to the bottom pressure of the lifting cylinder is as follows:

[0014] G 负载 =(C 起升油缸缸底压力 / C)*G 额定负载

[0015] Wherein, C 起升油缸缸底压力F is the cylinder bottom pressure value of the lifting cylinder, C is the cylinder bottom pressure value of the lifting cylinder corresponding to the rated load of the vehicle, G 额定负载 is the rated load of the vehicle.

[0016] In the preferred embodiment of the present application, the vehicle rear axle load is calculated according to the vehicle load, and the specific calculation formula is as follows:

[0017] F 后桥 = F 后桥空载 + G 负载 *g*(L1 / L)

[0018] Wherein, F 后桥空载 is the vehicle rear axle load, g is the acceleration of gravity, L1 is the horizontal distance from the gravity center of the vehicle load to the bearing wheel, L is the wheelbase of the vehicle, and G 负载 is the vehicle load.

[0019] In the preferred embodiment of the present application, the maximum torque of the driving wheel adhesion force is calculated according to the vehicle load and the vehicle rear axle load, and the specific calculation formula is as follows: 附着力 is the maximum torque of the driving wheel adhesion force when the driving wheel load is increased by braking,

[0020] is the maximum torque of the driving wheel adhesion force when the driving wheel load is increased by braking deceleration, 附着力 ,

[0021] T 附着力 = (F 后桥 +(G 负载 + G 空载 )*a*H / L)*K*u*R

[0022] Wherein, F 后桥 is the vehicle rear axle load, G 负载 is the vehicle load, G 空载 is the empty weight of the vehicle, H is the height of the gravity center of the full load of the vehicle, L is the wheelbase of the vehicle, a is the maximum braking acceleration of the vehicle, K is the driving wheel load coefficient, u is the adhesion coefficient of the driving wheel, and R is the radius of the driving wheel.

[0023] In the preferred embodiment of the present application, the maximum torque of the driving wheel adhesion force is calculated according to the vehicle load and the vehicle rear axle load, and the specific calculation formula is as follows: 附着力 is the maximum torque of the driving wheel adhesion force when the driving wheel load is reduced by braking,

[0024] is the maximum torque of the driving wheel adhesion force when the driving wheel load is reduced by braking deceleration, 附着力 ,

[0025] T 附着力 = (F 后桥 -(G 负载 + G空载 )*a*H / L)*K*u*R

[0026] wherein F 后桥 is the rear axle load of the vehicle, G 负载 is the load of the vehicle, G 空载 is the empty mass of the vehicle, H is the height of the center of gravity of the full load of the vehicle, L is the wheelbase of the vehicle, a is the maximum braking acceleration of the vehicle, K is the load coefficient of the driving wheel, u is the adhesion coefficient of the driving wheel, and R is the radius of the driving wheel.

[0027] In the preferred embodiment of the present application, the maximum given torque is the smaller one of the maximum torque of the traction motor and the maximum torque of the adhesion of the driving wheel, and the specific calculation formula is as follows:

[0028] When the braking deceleration increases the load of the driving wheel, the maximum given torque is obtained by comparing the maximum torque of the traction motor and the maximum torque of the adhesion of the driving wheel, and T1

[0029] T1 = min(T 附着力 , T 电机 )

[0030] T 电机 is the maximum torque of the traction motor calculated according to the collected speed of the traction motor.

[0031] In the preferred embodiment of the present application, the maximum given torque is the smaller one of the maximum torque of the traction motor and the maximum torque of the adhesion of the driving wheel, and the specific calculation formula can also be:

[0032] When the braking deceleration decreases the load of the driving wheel, the maximum given torque is obtained by comparing the maximum torque of the traction motor and the maximum torque of the adhesion of the driving wheel, and T2

[0033] T2 = min(T 附着力 , T 电机 )

[0034] T 制动 is the maximum torque of the traction motor calculated according to the collected speed of the traction motor.

[0035] In the preferred embodiment of the present application, the calculation of the regenerative braking torque of the traction motor according to the maximum given torque comprises:

[0036] When the braking deceleration increases the load of the driving wheel, the regenerative braking torque of the traction motor is T1 制动 ,

[0037] T1 负载 = K1 * T1 * K 负载

[0038] wherein K 负载 is a load influence coefficient, and K1 is a braking intensity coefficient.

[0039] In the preferred embodiment of the present application, the traction motor regenerative braking torque is calculated according to the maximum given torque, comprising:

[0040] When the braking deceleration causes the driving wheel load to decrease, the traction motor regenerative braking torque is T2 制动 ,

[0041] T2 制动 = K1*T2*K 负载

[0042] wherein K 负载 is a load influence coefficient, and K1 is a braking intensity coefficient.

[0043] In the preferred embodiment of the present application, the K 负载 is specifically calculated as follows:

[0044] K 负载 = (G 负载 + G 空载 ) / M

[0045] wherein M is the full load mass of the vehicle, G 空载 is the empty load mass of the vehicle, and G 负载 is the load of the vehicle.

[0046] In a second aspect, the present application provides a vehicle braking control device, comprising:

[0047] a rotation speed and pressure signal acquisition module, configured to acquire the rotation speed of the traction motor and the bottom pressure of the lifting oil cylinder;

[0048] a vehicle load calculation module, configured to calculate the load of the vehicle according to the bottom pressure of the lifting oil cylinder;

[0049] a vehicle rear axle load calculation module, configured to calculate the load of the vehicle rear axle according to the load of the vehicle;

[0050] a traction motor maximum torque calculation module, configured to calculate the maximum torque of the traction motor according to the rotation speed of the traction motor;

[0051] a driving wheel adhesion maximum torque calculation module, configured to calculate the maximum torque of the driving wheel adhesion according to the load of the vehicle and the load of the vehicle rear axle;

[0052] a maximum given torque calculation module, configured to compare the numerical values of the maximum torque of the traction motor and the maximum torque of the driving wheel adhesion, and take the smaller one as the maximum given torque;

[0053] a braking torque calculation module configured to calculate a traction motor regenerative braking torque according to the maximum given torque;

[0054] a braking control module configured to brake control the vehicle by the traction motor regenerative braking torque.

[0055] The technical scheme provided by some embodiments of the present application has at least the following beneficial effects:

[0056] The present application provides a vehicle braking control method and device, which collects the traction motor speed and the lifting cylinder bottom pressure; calculates the vehicle load according to the lifting cylinder bottom pressure; calculates the vehicle rear axle load according to the vehicle load; calculates the maximum torque of the traction motor according to the traction motor speed; calculates the maximum torque of the driving wheel adhesion according to the vehicle load and the vehicle rear axle load; compares the numerical values of the maximum torque of the traction motor and the maximum torque of the driving wheel adhesion, and takes the smaller one as the maximum given torque; calculates the traction motor regenerative braking torque according to the maximum given torque; and brakes the vehicle by the traction motor regenerative braking torque. The present application solves the problem that the current braking does not consider the influence of the driving wheel load, resulting in braking deviation, and the vehicle state cannot be identified during the braking process, the braking impact is large in the empty load state, and the braking distance is long at high speed.

[0057] Other features and advantages of the present application will be set forth in the descriptions below, and in part will become apparent to those skilled in the art from the descriptions, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and achieved by the structure particularly pointed out in the specification, claims and drawings.

[0058] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are described in detail as follows.

[0059] The advantages of the additional aspects of the present application will be partially given in the following description, partially will become apparent from the following description, or will be understood by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to make the technical scheme of the embodiments of the present application more clear, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application or the prior art. Obviously, the following described drawings are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without paying creative labor on the basis of these drawings.

[0061] Figure 1 The vehicle braking control method flow chart shown in the embodiments of the present application;

[0062] Figure 2A schematic block diagram of a vehicle brake control device according to an embodiment of the present application. DETAILED DESCRIPTION

[0063] In order to make the objects, technical solutions and advantages of the present application clearer, the following will further describe the present application in detail with reference to the accompanying drawings and embodiments.

[0064] The following description refers to the accompanying drawings. In the following description, same numbers in different drawings represent same or similar elements unless otherwise represented. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of methods and apparatuses consistent with some aspects of the present application as detailed in the appended claims.

[0065] In the description of the present application, it should be understood that the terms "first", "second" and the like are used for descriptive purposes only and cannot be construed as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances. In addition, in the description of the present application, "a plurality of" means two or more, unless otherwise specified. "And / or", which describes the association between the associated objects, means that there can be three relationships, for example, A and / or B can mean that there are three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0066] Embodiment One:

[0067] The following will describe in detail a vehicle brake control method provided by an embodiment of the present application with reference to the accompanying drawings.

[0068] Please refer to Figure 1 A flowchart of a vehicle brake control method provided by an embodiment of the present application. As Figure 1 shown, the method of the present embodiment can include the following steps:

[0069] Step S1: Collecting the traction motor speed and the hoist cylinder bottom pressure;

[0070] The hoist cylinder bottom pressure signal collected in the present embodiment is represented by C 起升油缸缸底压力 .

[0071] Step S2: Calculating the vehicle load according to the hoist cylinder bottom pressure;

[0072] In one possible implementation, the calculation formula for calculating the vehicle load according to the hoist cylinder bottom pressure is as follows:

[0073] G 负载 = (C 起升油缸缸底压力 / C)*G 额定负载

[0074] wherein C 起升油缸缸底压力 is the cylinder bottom pressure value of the lifting cylinder, C is the cylinder bottom pressure value corresponding to the rated load of the vehicle, G 额定负载 is the rated load of the vehicle.

[0075] Step S3: calculating the rear axle load of the vehicle according to the vehicle load;

[0076] In a possible implementation, the rear axle load of the vehicle is calculated according to the vehicle load, and the specific calculation formula is as follows:

[0077] F 后桥 = F 后桥空载 + G 负载 *g*(L1 / L)

[0078] wherein F 后桥 is the rear axle load of the vehicle, F 后桥空载 is the rear axle load of the vehicle under no load; g is the acceleration of gravity; L1 is the horizontal distance between the gravity center of the vehicle load and the bearing wheel; L is the wheelbase of the vehicle; and G 负载 is the vehicle load.

[0079] Step S4: calculating the maximum torque of the traction motor according to the rotational speed of the traction motor;

[0080] In this embodiment, T 电机 is taken as the maximum torque of the traction motor, and it can be understood that when the rotational speed n 牵引 ≤ n 拐 , the traction motor works in a constant torque region, and T 电机 = 9550*P / n 拐 .

[0081] When the rotational speed n 牵引 > n 拐 , the traction motor works in a constant power region,

[0082] T 电机 = 9550*P / n 牵引

[0083] wherein P is the rated power of the traction motor, in kW; and n 拐 is the inflection point speed of the motor, in rpm (revolutions per minute).

[0084] Step S5: calculating the maximum torque of the driving wheel adhesion force according to the vehicle load and the rear axle load of the vehicle;

[0085] In a possible implementation, the maximum torque of the driving wheel adhesion force is calculated according to the vehicle load and the rear axle load of the vehicle, including: T 附着力The maximum torque of the driving wheel adhesion is generated when the load on the driving wheels increases due to braking.

[0086] When braking and deceleration increase the load on the drive wheels, the maximum torque of the drive wheel's adhesion is T. 附着力 ,

[0087] T 附着力 =(F 后桥 +(G 负载 +G 空载 )*a*H / L)*K*u*R

[0088] Among them, F 后桥 For the load on the rear axle of the vehicle, G 负载 For vehicle load, G 空载 Where is the vehicle's unloaded mass, H is the vehicle's center of gravity height when fully loaded, L is the vehicle's wheelbase, a is the vehicle's maximum braking acceleration, K is the drive wheel load coefficient, u is the drive wheel adhesion coefficient, and R is the drive wheel radius.

[0089] In another possible implementation, the calculation of the maximum torque for drive wheel adhesion based on vehicle load and rear axle load further includes: T' 附着力 The maximum torque that the driving wheel adhesion force can provide when braking reduces the load on the driving wheels.

[0090] When braking and deceleration reduce the load on the drive wheels, the maximum torque of the drive wheel's adhesion is T'. 附着力 ,

[0091] T' 附着力 =(F 后桥 -(G 负载 +G 空载 )*a*H / L)*K*u*R

[0092] Among them, F 后桥 For the load on the rear axle of the vehicle, G 负载 For vehicle load, G 空载 Where is the vehicle's unloaded mass, H is the vehicle's center of gravity height when fully loaded, L is the vehicle's wheelbase, a is the vehicle's maximum braking acceleration, K is the drive wheel load coefficient, u is the drive wheel adhesion coefficient, and R is the drive wheel radius.

[0093] Step S6: Compare the maximum torque of the traction motor and the maximum torque of the drive wheel adhesion, and take the smaller value as the maximum given torque;

[0094] In one possible implementation, the formula for calculating the maximum given torque is as follows:

[0095] When braking and deceleration increase the load on the drive wheels, the maximum torque of the traction motor and the maximum torque of the drive wheel adhesion are compared to obtain the maximum given torque as T1.

[0096] T1 = min(T 电机 , T 附着力 )

[0097] T 电机 is the maximum traction motor torque calculated according to the collected traction motor speed, and T 附着力 is the maximum driving wheel adhesion torque when the driving wheel load is increased by braking.

[0098] In another possible implementation, the values of the maximum traction motor torque and the maximum driving wheel adhesion torque are compared, and the smaller one is taken as the maximum given torque. The specific calculation formula can also be:

[0099] When the driving wheel load is reduced by braking deceleration, the values of the maximum traction motor torque and the maximum driving wheel adhesion torque are compared, and the maximum given torque is T2,

[0100] T2 = min(T 电机 , T 附着力 )

[0101] T 电机 is the maximum traction motor torque calculated according to the collected traction motor speed, and T 附着力 is the maximum driving wheel adhesion torque when the driving wheel load is reduced by braking deceleration.

[0102] Step S7: calculating the traction motor regenerative braking torque according to the maximum given torque;

[0103] In one possible implementation, the traction motor regenerative braking torque is calculated according to the maximum given torque, including:

[0104] When the driving wheel load is increased by braking deceleration, the traction motor regenerative braking torque is T1 制动 ,

[0105] T1 制动 = K1 * T1 * K 负载

[0106] wherein K 负载 is a load influence coefficient, and K1 is a braking intensity coefficient.

[0107] In one possible implementation, the traction motor regenerative braking torque is calculated according to the maximum given torque, including:

[0108] When the driving wheel load is reduced by braking deceleration, the traction motor regenerative braking torque is T2 制动 ,

[0109] T2 制动 = K1 * T2 * K 负载

[0110] wherein K 负载 is a load influence coefficient, and K1 is a braking intensity coefficient.

[0111] In one possible implementation, K 负载 is calculated as follows:

[0112] K 负载 = (G 负载 + G 空载 ) / M

[0113] wherein M is the full load mass of the vehicle, G 空载 is the empty load mass of the vehicle, and G 负载 is the load of the vehicle.

[0114] It can be understood that,

[0115] M = G 空载 + G 额定负载

[0116] Therefore, K 负载 = (G 负载 + G 空载 ) / M = (G 负载 + G 空载 ) / (G 额定负载 + G 空载 );

[0117] In view of the influence of the load of the vehicle, a load influence coefficient K 负载 is introduced. When the vehicle is empty, K 负载 < 1, and when the vehicle is fully loaded, K 负载 = 1; that is, the braking torque provided is small when the vehicle is empty and large when the vehicle is fully loaded.

[0118] In one possible implementation, the traction motor regenerative braking torque is calculated according to the maximum given torque, and further comprising:

[0119] When the mechanical braking is involved and the braking deceleration causes the load of the driving wheel to increase, the traction motor regenerative braking torque is T1' 制动 ,

[0120] T1' 制动 = K2 * T1 * K 负载 - T 机械

[0121] When the mechanical braking is involved and the braking deceleration causes the load of the driving wheel to decrease, the traction motor regenerative braking torque is T2' 制动 ,

[0122] T2' 制动 = K2 * T2 * K 负载 - T机械

[0123] K2 = K1 + K2, K2 is the regenerative braking strength coefficient when the mechanical brake is working, T 机械 is the mechanical brake braking torque.

[0124] Step S8: Braking control of the vehicle is performed by the regenerative braking torque of the traction motor.

[0125] The following lists an example to explain the specific implementation process of the embodiment in detail.

[0126] The vehicle braking control method relates to a 1.8t rider type forklift, and is implemented through a reverse switch, a forward switch, a potentiometer of a handle accelerator, a brake switch, a traction motor speed sensor and a lifting cylinder bottom pressure sensor. The specific steps are as follows:

[0127] Step S101, monitoring the reverse switch output signal C1, the forward switch output signal C2, the potentiometer output signal C3 of the handle accelerator, the brake switch output signal C4, the traction motor speed signal n 牵引 , and the lifting cylinder bottom pressure signal C5;

[0128] When C1 = 1, C3 changes from large to small and C4 = 1, S102 is executed.

[0129] When C2 = 1, C3 changes from small to large and C4 = 1, S103 is executed.

[0130] When C4 = 0 and C1 = 1, S104 is executed; when C4 = 0 and C2 = 1, S105 is executed.

[0131] C1 is the reverse switch output signal, and when C1 = 1, it indicates that the vehicle is in a reverse state (a forklift reverse direction running state).

[0132] C2 is the forward switch output signal, and when C2 = 1, it indicates that the vehicle is in a forward state (a forklift direction running state).

[0133] C3 is the potentiometer output signal of the handle accelerator, and its change range is 0-5V. When the handle accelerator is in the middle position, the potentiometer signal C3 = 2.5V. When the handle accelerator is pushed forward (the vehicle is in forward motion), the potentiometer output voltage signal changes in the range of 2.5-0V, at this time, the handle accelerator is released, C3 signal changes from 0V to 2.5V (C3 signal changes from small to large), which indicates that the vehicle is in a forward motion process and requests braking. When the handle accelerator is pulled backward (the vehicle is in reverse motion), the potentiometer output voltage signal changes in the range of 2.5-5V, at this time, the handle accelerator is released, C3 signal changes from 5V to 2.5V (C3 signal changes from large to small), which indicates that the vehicle is in a reverse motion process and requests braking.

[0134] C4 is the brake switch output signal, when C4 = 1, the mechanical brake does not work, and the vehicle can normally travel, when C4 = 0, the mechanical brake works;

[0135] n 牵引 is the traction motor speed signal, n 牵引 is positively correlated with the vehicle travel speed;

[0136] C5 is the lifting cylinder bottom pressure signal, the change range is 0-5V, corresponding to the vehicle load of 0-1800kg, 0V corresponds to the vehicle load of 0kg, and 5V corresponds to 1800kg.

[0137] Step S102, the vehicle is backing up, the traction motor is regenerative braking, at this time, when the driving wheel load increases due to braking deceleration, the braking intensity is relatively weak, considering the driving wheel adhesion, in order to avoid brake deviation, the traction motor generates torque as follows:

[0138] The vehicle is backing up (driving wheel direction travel), the motor is regenerative braking, the braking intensity is relatively weak, which is used for general braking, considering the driving wheel adhesion, to avoid brake deviation: the controller controls the traction motor to provide a regenerative braking torque T 制动 ,

[0139] T 制动 =K1*T1*K 负载

[0140] Wherein: T 制动 is the regenerative braking torque provided by the traction motor controlled by the controller, unit: Nm;

[0141] K1 is the braking intensity coefficient, the value range is 0-1, considering the operation comfort, in this example, K1 = 0.8;

[0142] T1 is the vehicle backing up, considering the influence of braking acceleration on the driving wheel adhesion, the maximum given torque of regenerative braking, unit: Nm;

[0143] T1 = min(T 电机 , T 后退附着 )

[0144] T 电机 is the maximum regenerative braking torque that the motor can provide, unit: Nm;

[0145] When the motor speed n 牵引 ≤n 拐 , T 电机 =9550*P / n 拐 When the motor speed n 牵引 >n 拐 , T 电机 =9550*P / n 牵引

[0146] n 拐 n

[0147] When n 拐 = 1000 rpm.

[0148] At this time,

[0149] T 后退附着 = (F 后桥 + G 负载 + G 空载 )*a*H / L)*K*u*R

[0150] Where F 后桥 is the vehicle rear axle load, unit: N;

[0151] F 后桥 = F 后桥空载 + G 负载 *g*(L1 / L)

[0152] F 后桥空载 is the vehicle empty vehicle rear axle load, unit: N, no need to detect, determined by product design, is a constant value;

[0153] g is the acceleration of gravity, unit: m / s 2 ;

[0154] L1 is the distance from the vehicle load center of gravity to the horizontal direction of the bearing wheel, usually determined by product design, is a constant value, unit: mm; When the vehicle load center of gravity is between the drive wheel and the bearing wheel, take the positive value, otherwise take the negative value;

[0155] L is the vehicle wheelbase, unit: mm;

[0156] G 负载 is the vehicle load, unit: kg;

[0157] In this example, the lifting cylinder bottom pressure signal is C5, the change range is 0-5V, corresponding to the vehicle load 0-1800kg, so G 负载 The calculation expression is:

[0158] G 负载 = (C5 / 5)*G 额定负载 = 360*C5

[0159] G 额定负载 is the rated load of the vehicle, unit: kg; In this example, G 额定负载 = 1800kg;

[0160] G 空载 G is the vehicle empty mass, unit: kg, in this example G 空载 = 3200 kg;

[0161] a is the maximum braking acceleration of the vehicle, unit: m / s 2 ;

[0162] H is the height of the center of gravity of the full load vehicle, unit: mm;

[0163] K is the load coefficient of the driving wheel, K = F 驱动轮 / F 后桥 ;

[0164] F 驱动轮 is the load of the driving wheel, unit: N;

[0165] u is the adhesion coefficient of the driving wheel, in this example, polyurethane tire is used, u is 0.6;

[0166] R is the radius of the driving wheel, unit: m.

[0167] It should be noted that the vehicle provided in this example is a stand-driving forklift, the driving wheel is offset, and the rear axle is composed of the driving wheel and the auxiliary wheel, so the load of the driving wheel is equal to the load of the rear axle of the vehicle * the load coefficient of the driving wheel; and the driving wheel is arranged at the rear of the vehicle body (in the opposite direction of the fork).

[0168] Since the driving wheel is arranged at the rear of the vehicle body, when the vehicle is moving forward (driving in the direction of the fork), braking occurs under the influence of the braking acceleration, and the load of the rear axle of the vehicle will decrease, i.e. the load of the rear axle of the vehicle becomes: F 后桥 -(G 负载 +G 空载 )*a*H / L; when the vehicle is moving backward (driving in the direction of the driving wheel), braking occurs under the influence of the braking acceleration, and the load of the rear axle of the vehicle will increase, i.e. the load of the rear axle of the vehicle becomes: F 后桥 +(G 负载 +G 空载 )*a*H / L.

[0169] Since the driving wheel is offset, when the system braking torque is greater than the torque that can be provided by the adhesion of the driving wheel, the phenomenon of braking deviation will occur; therefore, in order to avoid braking deviation, T1 = min(T 电机 ,T 后退附着 ), T2 = min(T 电机 ,T 前进附着 ).

[0170] Step S103, the vehicle is moving forward (the fork direction is running), the motor regenerative braking, the brake intensity is relatively weak, which is used for general braking, considering the influence of brake acceleration on the driving wheel adhesion, to avoid brake deviation; the controller controls the traction motor to provide regenerative braking torque T 制动 = K1 * T2 * K 负载 .

[0171] Wherein, T2 is the vehicle forward, considering the influence of brake acceleration on the driving wheel adhesion, the maximum given torque of regenerative braking, unit: Nm;

[0172] T2 = min(T 电机 , T 前进附着 )

[0173] T 前进附着 is the maximum torque that the driving wheel adhesion can provide under the vehicle forward working condition, unit: Nm.

[0174] T 前进附着 = (F rear axle - (G load + G 空载 ) * a * H / L) * K * u * R

[0175] Step S104, the vehicle is moving backward (the driving wheel direction is running), the brake mode is motor regenerative braking + mechanical brake braking, which is emergency braking at this time, the brake intensity is strong, the braking distance is short, considering the influence of brake acceleration on the driving wheel adhesion, to avoid brake deviation, the controller controls the traction motor to provide regenerative braking torque T 制动 ,

[0176] T 制动 = K2 * T1 * K 负载 -T 机械

[0177] At the same time, the mechanical brake works, the braking torque is T 机械 , at this time, the braking torque of the braking system T 系统 = K2 * T1 * K 负载 .

[0178] Wherein, K2 is the regenerative braking intensity coefficient when the mechanical brake works, K2 = 0.95 in this example.

[0179] T 机械 is the mechanical brake braking torque, unit: Nm.

[0180] T 系统 is the total braking torque of the braking system, including the mechanical brake braking torque and the motor regenerative braking torque, unit: Nm.

[0181] Step S105, the vehicle advances (fork direction driving), the braking mode is motor regenerative braking + mechanical braking, at this time, emergency braking, strong braking intensity, short braking distance, considering the influence of braking acceleration on the adhesion of the driving wheel, avoiding braking deviation; the controller controls the traction motor to provide regenerative braking torque T 制动 ,

[0182] T 制动 = K2 * T2 * K 负载 -T 机械

[0183] At the same time, the mechanical brake works, the braking torque is T 机械 , at this time, the braking torque of the braking system T 系统 = K2 * T2 * K 负载 .

[0184] The specific implementation of the method of the application is based on a 1.8t forklift truck, and the specific implementation effects are as follows:

[0185] The vehicle's empty running speed is 10.5km / h, and the full load running speed is 10km / h; the vehicle's empty mass is 3200kg, and the full load mass is 5000kg.

[0186] According to the requirements of GB / T 18849-2011 standard, the braking distance S < 0.15V + V / 4.7,

[0187] The empty braking distance Semptyis less than 3.8(m),

[0188] The full load braking distance Sfullis less than 3.6(m),

[0189] According to the requirements of B56.1-2009 standard, the braking distance S < 0.268V,

[0190] The empty braking distance Semptyis less than 2.8(m),

[0191] The full load braking distance Sfullis less than 2.7(m),

[0192] In the above formula, V is the vehicle running speed, km / h; S is the braking distance, m.

[0193] Test results:

[0194] 1. Using mechanical brake alone: the empty (fork direction) braking distance is 2.5m, the empty (fork reverse direction) braking distance is 2.1m; the full load (fork reverse direction) braking distance is 3m, and the full load (fork direction) braking distance is not measured considering safety; it meets the requirements of GB / T 18849-2011, but does not meet the requirements of B56.1-2009. The braking impact is large, and there is a braking deviation phenomenon.

[0195] 2, AC motor regenerative braking alone: empty (fork direction) braking distance is 2.5m, empty (fork reverse direction) braking distance is 2.3m; full load (fork reverse direction) braking distance is 3.3m, full load (fork direction) considering safety, braking distance is not measured; meet the requirements of GB / T 18849-2011, not meet the requirements of B56.1-2009. There is a brake deviation phenomenon.

[0196] 3, the use of composite braking (the vehicle braking control method proposed in the embodiment), empty (fork direction) braking distance is 2.5m, empty (fork reverse direction) braking distance is 2.5m; full load (fork reverse direction) braking distance is 2.6m, full load (fork direction) considering safety, braking distance is not measured; meet the requirements of GB / T 18849-2011, meet the requirements of B56.1-2009. And the brake does not run off.

[0197] From the above, the vehicle braking control method disclosed in the embodiment, when the collected speed of the traction motor is less than or equal to the inflection point speed, the maximum regenerative braking torque of the traction motor is calculated according to the relationship between the vehicle rear axle load, the vehicle load and the driving wheel load; the regenerative braking torque of the traction motor is calculated according to the mass ratio corresponding to the vehicle load when the vehicle is fully loaded, the maximum regenerative braking torque and the braking intensity coefficient; the vehicle is controlled by the regenerative braking torque of the traction motor, which solves the problem that the influence of braking on the driving wheel load is not considered at present, resulting in brake deviation, unable to identify the vehicle state, large braking impact in empty state, and long braking distance at high speed.

[0198] Example two:

[0199] The application proposes a vehicle braking control device, as shown in Figure 2 , comprising:

[0200] The speed and pressure signal acquisition module is used to collect the speed of the traction motor and the pressure at the bottom of the lifting cylinder;

[0201] The vehicle load calculation module is used to calculate the vehicle load according to the pressure at the bottom of the lifting cylinder;

[0202] The vehicle rear axle load calculation module is used to calculate the vehicle rear axle load according to the vehicle load;

[0203] The traction motor maximum torque calculation module is used to calculate the maximum torque of the traction motor according to the speed of the traction motor;

[0204] The driving wheel adhesion maximum torque calculation module is used to calculate the maximum torque of the driving wheel adhesion according to the vehicle load and the vehicle rear axle load;

[0205] The maximum given torque calculation module is used to compare the numerical values of the maximum torque of the traction motor and the maximum adhesion torque of the drive wheel, and the smaller one is the maximum given torque;

[0206] The braking torque calculation module is used to calculate the regenerative braking torque of the traction motor according to the maximum given torque.

[0207] The braking control module is used to brake the vehicle by the regenerative braking torque of the traction motor.

[0208] The speed and pressure signal acquisition module, the vehicle load calculation module, the vehicle rear axle load calculation module, the traction motor maximum torque calculation module, the drive wheel adhesion maximum torque calculation module, the maximum given torque calculation module, the braking torque calculation module and the braking control module are sequentially connected.

[0209] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here. Since the vehicle braking control device disclosed in the present application has the same control process as the method embodiments, it also has the same technical effects.

[0210] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some communication interfaces, devices or units, which can be electrical, mechanical or other forms.

[0211] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or they can be distributed on a plurality of network units. According to actual needs, some or all of the units can be selected to achieve the purpose of the embodiment scheme.

[0212] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit.

[0213] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a nonvolatile computer readable storage medium executable by a processor. Based on this understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0214] It should be noted that the flowcharts and block diagrams in the drawings show the possible implementation architecture, function and operation of the systems, methods and computer program products according to the embodiments of the present application. In this regard, each block in the flowchart or block diagram can represent a module, a program segment or a part of code, which includes one or more executable instructions for implementing the specified logic function. It should also be noted that in some alternative implementations, the functions noted in the blocks can occur in different order from that noted in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and sometimes they can be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0215] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present application, which are used to illustrate the technical solutions of the present application, but not to limit them. The protection scope of the present application is not limited thereto, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily think of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed by the present application, or make equivalent replacements to some of the technical features; and these modifications, changes or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered within 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.

[0216] The applicant of the present application makes detailed explanation and description on the implementation examples of the present application in combination with the drawings of the specification, but the skilled in the art should understand that the above implementation examples are only the preferred implementation of the present application, and the detailed explanation is only to help the reader better understand the spirit of the present application, and does not limit the protection scope of the present application. On the contrary, any improvement or modification based on the spirit of the present application should fall within the protection scope of the present application.

Claims

1. A vehicle brake control method characterized by, The method comprises the following steps: collecting the rotating speed of the traction motor and the bottom pressure of the lifting cylinder; calculating the vehicle load according to the bottom pressure of the lifting cylinder; calculating the rear axle load of the vehicle according to the vehicle load; calculating the maximum torque of the traction motor according to the rotating speed of the traction motor; calculating the maximum adhesion torque of the driving wheel according to the vehicle load and the rear axle load of the vehicle; comparing the values of the maximum torque of the traction motor and the maximum adhesion torque of the driving wheel, and taking the smaller one as the maximum given torque; calculating the regenerative braking torque of the traction motor according to the maximum given torque; controlling the braking of the vehicle by the regenerative braking torque of the traction motor.

2. The vehicle brake control method according to claim 1, characterized by, The calculation formula for calculating the vehicle load according to the bottom pressure of the lifting cylinder is as follows: G 负载 = (C 起升油缸缸底压力 / C)*G 额定负载 Wherein, C 起升油缸缸底压力 is the lifting cylinder bottom pressure value, C is the lifting cylinder bottom pressure value corresponding to the rated load of the vehicle, G 额定负载 is the rated load of the vehicle.

3. The vehicle brake control method according to claim 1, characterized by, The calculation formula for calculating the rear axle load of the vehicle according to the vehicle load is as follows: F 后桥 = F 后桥空载 + G 负载 * g * (L1 / L) where F 后桥空载 is the load on the rear axle of the vehicle; g is the acceleration due to gravity; Li is the horizontal distance from the load center of gravity to the load bearing wheels; L is the wheelbase of the vehicle; G 负载 is the load on the vehicle.

4. The vehicle brake control method according to claim 1, characterized by The drive wheel adhesion maximum torque is calculated based on the vehicle load and the vehicle rear axle load, including: T 附着力 The drive wheel adhesion maximum torque is calculated based on the vehicle load and the vehicle rear axle load, including: T 附着力 The drive wheel adhesion maximum torque is calculated based on the vehicle load and the vehicle rear axle load, including: T 附着力 The drive wheel adhesion maximum torque is calculated based on the vehicle load and the vehicle rear axle load, including: T 附着力 The drive When the brake deceleration increases the load of the drive wheels, the maximum torque of the drive wheels is T 附着力 , T 附着力 = (F 后桥 + (G 负载 + G 空载 )*a*H / L)*K*u*R where F 后桥 is the vehicle rear axle load, G 负载 is the vehicle load, G 空载 is the vehicle unloaded mass, H is the vehicle loaded center of gravity height, L is the vehicle wheel base, a is the vehicle maximum braking acceleration, K is the drive wheel load coefficient, u is the drive wheel adhesion coefficient, and R is the drive wheel radius.

5. The vehicle brake control method according to claim 1, characterized by The vehicle load and the vehicle rear axle load calculate the maximum torque of the driving wheel adhesion force, also includes: T' 附着力 The maximum torque of the driving wheel adhesion force can be provided when the driving wheel load is reduced for braking. The maximum torque of the driving wheel T' is the maximum torque of the driving wheel when the load of the driving wheel is reduced by the braking deceleration 附着力 , T' 附着力 = (F 后桥 - (G 负载 + G 空载 )*a*H / L)*K*u*R where F 后桥 is the vehicle rear axle load, G 负载 is the vehicle load, G 空载 is the vehicle unloaded mass, H is the vehicle loaded center of gravity height, L is the vehicle wheel base, a is the vehicle maximum braking acceleration, K is the drive wheel load coefficient, u is the drive wheel adhesion coefficient, and R is the drive wheel radius.

6. The vehicle brake control method according to claim 4, characterized by The calculation formula for comparing the values of the maximum torque of the traction motor and the maximum adhesion torque of the driving wheel, and taking the smaller one as the maximum given torque, is as follows: When the braking deceleration increases the load of the driving wheel, the maximum given torque is T1, which is obtained by comparing the values of the maximum torque of the traction motor and the maximum adhesion torque of the driving wheel. T1 = min(T 电机 , T 附着力 ) T 电机 is the maximum torque of the traction motor calculated from the traction motor speed acquired.

7. The vehicle brake control method according to claim 5, characterized by The calculation formula for comparing the values of the maximum torque of the traction motor and the maximum adhesion torque of the driving wheel, and taking the smaller one as the maximum given torque, can also be as follows: When the braking deceleration reduces the load of the driving wheel, the maximum given torque is T2, which is obtained by comparing the values of the maximum torque of the traction motor and the maximum adhesion torque of the driving wheel. T2 = min(T 电机 , T' 附着力 ) T 电机 The maximum torque of the traction motor is calculated from the acquired traction motor rotational speed.

8. The vehicle brake control method according to claim 6, characterized by, The calculation of the regenerative braking torque of the traction motor according to the maximum given torque comprises the following steps: When the brake deceleration increases the load of the driving wheel, the regenerative braking torque of the traction motor is T1 制动 , T1 制动 = K1 * T1 * K 负载 wherein K 负载 is a load influence coefficient, and K1 is a braking intensity coefficient.

9. The vehicle brake control method according to claim 7, characterized by The calculation of the regenerative braking torque of the traction motor according to the maximum given torque comprises the following steps: When braking deceleration reduces the load on the drive wheels, the regenerative braking torque of the traction motor is T2. 制动 , T2 制动 = K1 * T2 * K 负载 wherein K 负载 is a load influence coefficient, and K1 is a braking intensity coefficient.

10. The vehicle brake control method according to claim 8 or 9, characterized by, The K 负载 The specific calculation is as follows: K 负载 = (G 负载 + G 空载 ) / M where M is the vehicle laden mass, G 空载 is the vehicle unladen mass, G 负载 is the vehicle load.

11. A vehicle brake control device characterized by comprising: The method comprises the following steps: The rotating speed of the traction motor and the bottom pressure of the lifting cylinder are collected by a rotating speed and pressure signal collection module. The vehicle load is calculated according to the bottom pressure of the lifting cylinder by a vehicle load calculation module. The rear axle load of the vehicle is calculated according to the vehicle load by a vehicle rear axle load calculation module. The maximum torque of the traction motor is calculated according to the rotating speed of the traction motor by a traction motor maximum torque calculation module. The maximum adhesion torque of the driving wheel is calculated according to the vehicle load and the rear axle load of the vehicle by a driving wheel adhesion maximum torque calculation module. The maximum given torque is calculated by comparing the values of the maximum torque of the traction motor and the maximum adhesion torque of the driving wheel, and taking the smaller one as the maximum given torque by a maximum given torque calculation module. The regenerative braking torque of the traction motor is calculated according to the maximum given torque by a braking torque calculation module. The braking of the vehicle is controlled by the regenerative braking torque of the traction motor by a braking control module.

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