Brake control method for forward moving type forklift truck with offset driving wheels

Abstract

The invention discloses a braking control method for a forward forklift with biased driving wheels, which comprises the following steps of: detecting a voltage signal of a forklift braking switch, judging whether a driver has a braking intention or not according to the voltage signal, and if so, monitoring a forward switch and a backward switch of the forklift; according to the collected forward switching value signal and the collected backward switching value signal, it is judged that the forklift travels along the driving wheel side or the bearing wheel side; the rotating speed of a forklift traction motor is obtained in real time, and the left offset torque M of the inertia force and the driving wheel friction force on the left bearing wheel in the forklift braking state is obtained through calculation; according to the left offset torque M and the driving state, whether the driving wheel is in a sideslip state or not is judged, and if yes, the braking torque of a traction motor is reduced so that the driving wheel can not slip. According to the invention, the braking accuracy and convenience of the forklift can be improved, and the operation safety of the forklift is improved.

Description

Technical Field

[0001] This invention relates to the technical field of forklift braking control, and more specifically, to a braking control method for a drive wheel biased reach truck. Background Technology

[0002] Reach trucks, with their masts that can move forward and backward along the inner guide rails of the outriggers, facilitate loading and unloading and are suitable for operation in narrow aisles and confined spaces. However, existing reach trucks have offset drive wheels, and the braking torque of the traction motor is transmitted to the drive wheels via a gearbox. When braking, due to the small diameter of the load-bearing wheels and the absence of brakes, the following problems often arise: on slippery surfaces, braking while the load-bearing wheels are in the direction of travel may cause the drive wheels to sideslip, affecting braking safety; on normal surfaces, when the forks are moved forward to the load-bearing wheel end and braking while the load-bearing wheels are in the direction of travel, the drive wheels may also sideslip, affecting braking safety. Therefore, how to safely and conveniently control the braking of forklifts is of great significance. Summary of the Invention

[0003] This invention provides a braking control method for a reach truck with offset drive wheels, solving the safety problem of drive wheel slippage and deviation during braking in existing reach trucks. It improves the accuracy and convenience of forklift braking, increasing the safety of forklift operation.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A braking control method for a drive wheel biased reach truck includes:

[0006] The voltage signal of the forklift brake switch is detected, and the driver's intention to brake is determined based on the voltage signal. If so, the forward and reverse switches of the forklift are monitored.

[0007] Based on the collected forward and reverse switch signals, it can be determined whether the forklift is traveling along the drive wheel side or the load-bearing wheel side.

[0008] The rotational speed of the forklift traction motor is acquired in real time, and the left offset torque M of the inertial force and the frictional force of the drive wheel on the left bearing wheel under the braking state of the forklift is calculated.

[0009] Based on the left offset torque M and the driving state, determine whether the drive wheel is in a sideslip state. If so, reduce the torque of the traction motor to prevent the drive wheel from slipping.

[0010] Preferably, determining whether the drive wheel is in a sideslip state based on the left offset torque M and the driving state includes:

[0011] When the forklift is traveling along the side of the load-bearing wheel, if the left offset torque M > 0, it is determined that the drive wheel is in a sideslip state.

[0012] Preferred options also include:

[0013] When the forklift is traveling along the side of the load-bearing wheel, if the left offset torque M ≤ 0, the traction motor is controlled to brake at the maximum braking torque of the traction motor at the specified speed.

[0014] Preferred options also include:

[0015] When the forklift is traveling along the drive wheel side, the traction motor is controlled to brake at the maximum braking torque of the traction motor at the said speed.

[0016] Preferably, the calculation of the left offset torque M on the left load-bearing wheel under forklift braking conditions includes:

[0017] According to the formula: M=(G1+G2)*a*W 重心 -F 驱动 *W 驱动轮 *Φ-F 驱动 *L*Φ is used to calculate the left offset torque M, where G1 is the forklift load mass, G2 is the forklift mass, a is the forklift braking deceleration, and W... 重心 W is the distance from the vehicle's center of gravity to the center plane of the left load-bearing wheel. 驱动轮 Φ is the distance from the center plane of the drive wheel to the center plane of the left bearing wheel, Φ is the adhesion coefficient of the drive wheel, and F is the distance from the center plane of the drive wheel to the center plane of the left bearing wheel. 驱动 The load is the drive wheel load, and L is the forklift wheelbase.

[0018] Preferred options also include:

[0019] A pressure sensor is set up to detect the bottom pressure P of the lifting cylinder, and the forklift load mass G1 is calculated according to the formula: G1=K1*P*A*K2 / g, where K1 is the load weight coefficient, A is the effective working area of ​​the lifting cylinder, K2 is the unit conversion coefficient, and g is the acceleration due to gravity.

[0020] Preferred options also include:

[0021] A position sensor is set up to detect the forward and backward movement distance of the forks. The distance L1 from the front end of the fork to the drive wheel axis when the fork is in the forward position is calculated according to the formula: L1=L2+L3*(C2 / 5). Where L2 is the distance from the front end of the fork to the drive wheel axis when the fork is in the backward position, L3 is the forward movement distance of the fork, and C2 is the voltage signal of the position sensor.

[0022] Preferred options also include:

[0023] According to the formula: F 驱动 =(L 重心*(G1+G2)*gH 重心 The load F on the drive wheel is calculated using *(G1+G2)*a)*K3 / L. 驱动 , where L 重心 H is the distance from the vehicle's center of gravity to the drive axle axis. 重心 This is the distance from the vehicle's center of gravity to the ground.

[0024] Preferred options also include:

[0025] According to the formula: L 重心 =(L4*G2+(L1+L5)*G1) / (G1+G2), calculate the distance L from the vehicle's center of gravity to the drive axle axis. 重心 ;

[0026] According to the formula: H 重心 =(H1*G2+(H3+L5)*G1) / (G1+G2), calculate the distance H from the vehicle's center of gravity to the ground. 重心 ;

[0027] Where L4 is the distance from the vehicle's center of gravity without load to the drive axle axis, L5 is the vehicle's load center distance, H1 is the distance from the vehicle's center of gravity without load to the ground, and H3 is the fork lifting height when the forklift is in motion.

[0028] Preferably, reducing the driving torque of the traction electric motor to prevent the drive wheels from slipping includes:

[0029] According to the formula: T 制动调整 =( L 重心 *g*(K3 / L)*Φ*(W 驱动轮 +L) / ((W 重心 + H 重心 *(K3 / L)*Φ*(W 驱动轮 +L))-g*u)*R*(G1+G2)*K4 / i, adjust the driving torque of the traction electric motor, where T 制动调整 R is the braking adjustment torque, K3 is the driving wheel rolling radius, K4 is the driving wheel load distribution coefficient, u is the wheel rolling resistance coefficient, K4 is the braking torque adjustment coefficient, and i is the gearbox speed ratio.

[0030] This invention provides a braking control method for a reach truck with offset drive wheels. By calculating the left offset torque M on the left load-bearing wheel due to the inertial force and friction of the drive wheels during braking, the method determines whether the drive wheel is in a sideslip state based on the left offset torque M. If slippage occurs, the method reduces the torque of the traction motor, thus solving the safety problem of drive wheel sideslip and deviation during braking in existing reach trucks. This method improves the accuracy and convenience of forklift braking and increases the safety of forklift operation. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below.

[0032] Figure 1 This is a schematic diagram of a braking control method for a drive wheel biased reach truck provided by the present invention. Detailed Implementation

[0033] To enable those skilled in the art to better understand the embodiments of the present invention, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and implementation methods.

[0034] The present invention addresses the safety issue of drive wheel slippage during braking in current reach trucks, which poses a safety hazard. It provides a braking control method for a reach truck with offset drive wheels, resolving this problem and improving the accuracy and convenience of forklift braking, thus enhancing operational safety.

[0035] like Figure 1 As shown, a braking control method for a drive wheel biased reach truck includes:

[0036] 101: By detecting the voltage signal of the forklift brake switch, and judging whether the driver intends to brake based on the voltage signal, if so, monitor the forklift's forward and reverse switches.

[0037] 102: Based on the collected forward and reverse switch signals, determine whether the forklift is traveling along the drive wheel side or the load-bearing wheel side;

[0038] 103: Real-time acquisition of the rotational speed of the forklift traction motor, and calculation of the left offset torque M of the inertial force and the frictional force of the drive wheel on the left bearing wheel under the braking state of the forklift;

[0039] 104: Based on the left offset torque M and the driving state, determine whether the drive wheel is in a sideslip state. If so, reduce the torque of the traction motor to prevent the drive wheel from slipping.

[0040] Specifically, the drive wheel bias reach truck braking control system includes: a controller, a traction motor speed sensor, a fork forward / backward position sensor, a pressure sensor, a brake switch, a forward switch, and a reverse switch. The traction motor speed sensor detects the traction motor speed using a voltage signal C1, with a range of 0-5V. The fork forward / backward position sensor monitors the fork forward / backward position using a voltage signal C2, also with a range of 0-5V, to detect the distance from the fork tip face to the drive wheel axis. The pressure sensor detects the lifting cylinder bottom pressure using a voltage signal C3, with a range of 0-5V. The brake switch detects the driver's braking intention using a voltage signal C4, which is a switching signal; when C4=1, it indicates that the driver has issued a braking request. The forward switch identifies the vehicle's intention to move towards the load-bearing wheel using a voltage signal C5, which is a switching signal; when C5=1, it indicates that the vehicle is moving towards the load-bearing wheel. The reverse switch identifies the vehicle's intention to move towards the drive wheel using a voltage signal C6, which is a switching signal; when C6=1, it indicates that the vehicle is moving towards the drive wheel. The controller adjusts the traction motor's torque based on the aforementioned signals and calculates the left offset torque M on the left load-bearing wheel caused by the inertial force and the frictional force of the drive wheels under forklift braking conditions. Based on this left offset torque M, the controller determines whether the drive wheel is in a sideslip state. If slippage occurs, the controller reduces the traction motor's torque, thus ensuring braking without sideslip or deviation of the vehicle's drive wheels. This method improves the accuracy and convenience of forklift braking and increases the safety of forklift operation.

[0041] Furthermore, determining whether the drive wheel is in a sideslip state based on the left offset torque M and the driving state includes:

[0042] When the forklift is traveling along the side of the load-bearing wheel, if the left offset torque M > 0, it is determined that the drive wheel is in a sideslip state.

[0043] The method further includes: when the forklift is traveling along the side of the load-bearing wheel, if the left offset torque M ≤ 0, then controlling the traction motor to brake at the maximum braking torque of the traction motor at the specified speed.

[0044] The method further includes: when the forklift is traveling along the drive wheel side, controlling the traction motor to brake at the maximum braking torque of the traction motor at the said rotational speed.

[0045] Furthermore, the calculation of the left offset torque M of the inertial force and drive wheel friction on the left load-bearing wheel under the braking state of the forklift includes:

[0046] According to the formula: M=(G1+G2)*a*W 重心 -F 驱动 *W 驱动轮 *Φ-F 驱动*L*Φ is used to calculate the left offset torque M, where G1 is the forklift load mass, G2 is the forklift mass, a is the forklift braking deceleration, and W... 重心 W is the distance from the vehicle's center of gravity to the center plane of the left load-bearing wheel. 驱动轮 Φ is the distance from the center plane of the drive wheel to the center plane of the left bearing wheel, Φ is the adhesion coefficient of the drive wheel, and F is the distance from the center plane of the drive wheel to the center plane of the left bearing wheel. 驱动 The load is the drive wheel load, and L is the forklift wheelbase.

[0047] The method also includes: setting a pressure sensor to detect the bottom pressure P of the lifting cylinder, and calculating the forklift load mass G1 according to the formula: G1=K1*P*A*K2 / g, where K1 is the load weight coefficient, A is the effective working area of ​​the lifting cylinder, K2 is the unit conversion coefficient, and g is the gravitational acceleration.

[0048] The method further includes: setting a position sensor to detect the forward and backward movement distance of the fork, and calculating the distance L1 from the front end face of the fork to the drive wheel axis when the fork is in the forward position according to the formula: L1=L2+L3*(C2 / 5), where L2 is the distance from the front end face of the fork to the drive wheel axis when the fork is in the backward position, L3 is the forward movement distance of the fork, and C2 is the voltage signal of the position sensor.

[0049] The method also includes: according to the formula: F 驱动 =(L 重心 *(G1+G2)*gH 重心 Calculate the load F directed to the drive wheel using *(G1+G2)*a)*K3 / L. 驱动 , where L 重心 H is the distance from the vehicle's center of gravity to the drive axle axis. 重心 This is the distance from the vehicle's center of gravity to the ground.

[0050] The method also includes:

[0051] According to the formula: L 重心 =(L4*G2+(L1+L5)*G1) / (G1+G2), calculate the distance L from the vehicle's center of gravity to the drive axle axis. 重心 ;

[0052] According to the formula: H 重心 =(H1*G2+(H3+L5)*G1) / (G1+G2), calculate the distance H from the vehicle's center of gravity to the ground. 重心 ;

[0053] Where L4 is the distance from the vehicle's center of gravity without load to the drive axle axis, L5 is the vehicle's load center distance, H1 is the distance from the vehicle's center of gravity without load to the ground, and H3 is the lifting height of the forks when the forklift is in motion, typically H3 = 300mm.

[0054] Furthermore, the reduction of the traction motor's driving torque to prevent the drive wheels from slipping includes:

[0055] According to the formula: T 制动调整 =( L 重心 *g*(K3 / L)*Φ*(W 驱动轮 +L) / ((W 重心 + H 重心 *(K3 / L)*Φ*(W 驱动轮 +L))-g*u)*R*(G1+G2)*K4 / i, adjust the driving torque of the traction electric motor, where T 制动调整 R is the braking adjustment torque, K3 is the driving wheel rolling radius, K4 is the driving wheel load distribution coefficient, u is the wheel rolling resistance coefficient, K4 is the braking torque adjustment coefficient, and i is the gearbox speed ratio.

[0056] In one embodiment, the braking control process includes the following steps:

[0057] S1. Monitor the voltage signal C1 of the traction motor speed. The controller calculates the traction motor speed n = n1 * (C1 / 5) based on C1. Where n is the traction motor speed, n1 is the maximum speed set for the traction motor, and the voltage signal C1 is 0-5V, with 5V corresponding to the maximum speed n1 set for the traction motor.

[0058] S2. Monitor the voltage signal C2 of the fork's forward and backward movement position. The controller calculates the distance L1 = L2 + L3 * (C2 / 5) from the front end face of the fork to the drive wheel axis based on C2.

[0059] S3. Monitor the voltage signal C3 of the lifting cylinder bottom pressure. The controller calculates the load (forks, attachments, and goods) mass G1 = K1 * P * A * K2 / g based on C3. Here, G1 is the load mass, K1 is the load weight coefficient, and since the lifting cylinder lifts the load via a fixed pulley and lifting chain, the load weight is equal to half the force exerted by the lifting cylinder, so K1 = 0.5. The lifting cylinder bottom pressure P = (C3 / 5) * Pmax. The voltage signal C3 for the lifting cylinder bottom pressure is 0-5V, with 5V corresponding to the maximum hydraulic system pressure Pmax. Pmax is the maximum hydraulic system pressure, which can be set according to the maximum pressure of the reach truck's hydraulic system; the unit conversion factor K2 = 100.

[0060] S4. Monitor the brake switch signal, forward switch signal, and reverse switch signal.

[0061] S5. The controller calculates the distance L from the vehicle's center of gravity to the drive axle axis based on the above signals. 重心 The distance H of the vehicle's center of gravity from the ground 重心 Drive wheel load F 驱动 .

[0062] S6. The controller calculates the left offset torque M of the inertial force and driving wheel friction on the left load-bearing wheel (the load-bearing wheel is in the direction of vehicle forward movement, and the driving wheel is offset to the left) under vehicle braking conditions. Where M > 0, it indicates that the driving wheel sideslips; M ≤ 0, it indicates that the driving wheel does not sideslip.

[0063] When C4=1 and C6=1, execute S7.

[0064] When C4=1, C5=1, and M≤0, execute S7.

[0065] When C4=1, C5=1, and M>0, execute S8.

[0066] S7, Controller controls the traction motor's torque T 制动 =T(n), where T(n) is the maximum braking torque of the traction motor at this speed.

[0067] S8, Controller controls the traction motor's torque T 制动调整 K4=0.95.

[0068] Therefore, this invention provides a braking control method for a reach truck with offset drive wheels. By calculating the left offset torque M on the left load-bearing wheel due to the inertial force and friction of the drive wheels during braking, and determining whether the drive wheel is in a sideslip state based on the left offset torque M, the method reduces the traction motor torque when slipping. This solves the safety problem of drive wheel sideslip and deviation during braking in existing reach trucks. It improves the accuracy and convenience of forklift braking and increases the safety of forklift operation.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A braking control method for a reach forklift with offset driving wheels, characterized in that: include: By detecting the voltage signal of the forklift's brake switch, and judging whether the driver has the intention to brake according to the voltage signal, if yes, the forward switch and the reverse switch of the forklift are monitored; According to the collected forward switch signal and backward switch signal, it is determined whether the forklift is traveling along the driving wheel side or the load wheel side; The speed of the forklift traction motor is obtained in real time, and the left offset torque M of the left load-bearing wheel caused by the inertia force and the friction force of the driving wheel under the braking state of the forklift is calculated; According to the left bias torque M and the driving state, it is determined whether the driving wheel is in a side slip state. If so, the traction motor torque is reduced to prevent the driving wheel from slipping.

2. The braking control method for a reach truck with offset driving wheels according to claim 1, characterized in that: The step of judging whether the driving wheel is in a side slip state according to the left bias moment M and the driving state includes: When the forklift is traveling along the load-bearing wheel side, if the left offset torque M>0, it is determined that the drive wheel is in a side slip state.

3. The braking control method for a reach truck with offset driving wheels according to claim 2, characterized in that: Also includes: When the forklift is traveling along the load-bearing wheel side, if the left offset torque M≤0, the traction motor is controlled to brake at the maximum braking torque of the traction motor at the rotation speed.

4. The braking control method for a reach truck with offset driving wheels according to claim 3, characterized in that: Also includes: When the forklift travels along the driving wheel side, the traction motor is controlled to brake at the maximum braking torque of the traction motor at the rotation speed.

5. The brake control method for a reach truck with offset drive wheels according to claim 4, characterized in that: The calculation to obtain the left offset moment M of the left load-bearing wheel caused by the inertia force and the friction force of the driving wheel under the braking state of the forklift includes: According to the formula: M=(G1+G2)*a*W 重心 -F 驱动 *W 驱动轮 *Φ-F 驱动 *L*Φ, the left offset moment M is calculated, where G1 is the forklift load mass, G2 is the forklift mass, a is the forklift braking deceleration, W 重心 W is the distance from the center of gravity of the vehicle to the center plane of the left load-bearing wheel. 驱动轮 is the distance from the center plane of the driving wheel to the center plane of the left load-bearing wheel, Φ is the driving wheel adhesion coefficient, F 驱动 is the driving wheel load and L is the forklift wheelbase.

6. The brake control method for a reach truck with offset drive wheels according to claim 5, characterized in that: Also includes: A pressure sensor is set up to detect the bottom pressure P of the lifting cylinder, and the forklift load mass G1 is calculated according to the formula: G1=K1*P*A*K2 / g, where K1 is the load weight coefficient, A is the effective working area of ​​the lifting cylinder, K2 is the unit conversion coefficient, and g is the acceleration of gravity.

7. The brake control method for a reach truck with offset drive wheels according to claim 6, characterized in that: Also includes: A position sensor is set to detect the distance the fork moves forward and backward, and according to the formula: L1=L2+L3*(C2 / 5), the distance L1 from the front end of the fork to the axis of the driving wheel when the fork is in place is calculated, where L2 is the distance from the front end of the fork to the axis of the driving wheel when the fork moves backward, L3 is the distance the fork moves forward, and C2 is the voltage signal of the position sensor.

8. The brake control method for a reach truck with offset drive wheels according to claim 6, characterized in that: Also includes: According to the formula: F 驱动 =(L 重心 *(G1+G2)*gH 重心 *(G1+G2)*a)*K3 / L, calculate the drive wheel load F 驱动 , where L 重心 H is the distance between the vehicle's center of gravity and the drive axle axis. 重心 is the distance between the vehicle's center of gravity and the ground.

9. The brake control method for a reach truck with offset drive wheels according to claim 8, characterized in that: Also includes: According to the formula: L 重心 =(L4*G2+(L1+L5)*G1) / (G1+G2), calculate the distance L between the center of gravity of the vehicle and the axis of the drive axle 重心 ; According to the formula: H 重心 =(H1*G2+(H3+L5)*G1) / (G1+G2), calculate the distance H between the center of gravity of the vehicle and the ground 重心 ; Among them, L4 is the distance from the center of gravity of the unloaded vehicle to the axis of the drive axle, L5 is the vehicle load center distance, H1 is the distance from the center of gravity of the unloaded vehicle to the ground, and H3 is the lifting height of the forklift when driving.

10. The brake control method for a reach truck with offset drive wheels according to claim 9, characterized in that: The step of reducing the traction motor torque so that the driving wheels do not slip comprises: According to the formula: T 制动调整 =( L 重心 *g*(K3 / L)*Φ*(W 驱动轮 +L) / ((W 重心 + H 重心 *(K3 / L)*Φ*(W 驱动轮 +L))-g*u)*R*(G1+G2)*K4 / i, adjust the traction motor torque, where T 制动调整 is the braking adjustment torque, R is the rolling radius of the driving wheel, K3 is the driving wheel load distribution coefficient, u is the wheel rolling resistance coefficient, K4 is the braking torque adjustment coefficient, and i is the gearbox speed ratio.

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