Automatic following and steering control hydraulic system for a ladle car

Abstract

The application discloses a kind of ladle transport car automatic following steering control hydraulic systems, install on ladle transport car, including variable plunger pump, front steering control system, front steering execution element, front steering following system, rear steering control system, rear steering execution element, rear steering following system, front wheel position feedback device, rear wheel position feedback device, PLC controller and remote controller;When driver rotates steering wheel in front cab and carries out front wheel steering, PLC controller controls rear steering following system according to the front wheel steering angle that front wheel position feedback device feedbacks, makes rear steering cylinder and front steering cylinder synchronization, realizes rear wheel automatic synchronous following front wheel steering function.The present application is accurate in return middle position, and front and rear oil cylinder synchronization error is small, repeatability is good, and no need to supplement oil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic control, in particular to an automatic following steering control hydraulic system for a ladle transport vehicle. BACKGROUND

[0002] The steering system of the traditional ladle transport vehicle breaks the mechanical connection of the front and rear steering cylinders at the load bearing position of the middle ladle, and the front and rear steering of the driver's cab is controlled by the front and rear steering gears to drive the front and rear hydraulic cylinders to realize hydraulic steering. However, due to the difference in the position of the near and far ends of the hydraulic cylinder, the hydraulic oil flow is not evenly distributed, resulting in different actions of the front and rear hydraulic cylinders during steering, uneven steering, and pressure build-up in the steering cylinder on one side at the limit position. In addition, the deviation of the center position is large, and manual oil supplementing is required to adjust the center position, which is inconvenient for the user and difficult to operate.

[0003] The control system for steering of a heavy flatbed transport vehicle controlled by multiple servo valves disclosed in publication No. CN 107856735 A controls each wheel group of the heavy flatbed transport vehicle through multiple servo valves, and adjusts the steering process of the wheel group according to the real-time angle state of the wheel group through closed-loop angle coordination control, thereby completing the coordinated steering of multiple wheel groups of the heavy flatbed transport vehicle. The flatbed vehicle requires independent rotation of each wheel group, so the control cannot guarantee the following property of the front and rear wheels and the Akerman steering condition of each wheel group, and each wheel group is driven independently, which requires a complex control program. Therefore, the control system cannot meet the steering requirements of the ladle transport vehicle.

[0004] Therefore, how to provide an automatic following steering control hydraulic system for a ladle transport vehicle, which adopts an angle closed-loop control principle to enable the front steering wheel to actively control the rotation of the front wheels and the rear wheels to automatically follow, the rear steering wheel to actively control the rotation of the rear wheels and the front wheels to automatically follow, and the front wheels to proportionally control the steering when the vehicle is controlled by remote control and the rear wheels to automatically follow, and to have the characteristics of easy operation, no need for oil supplementing, accurate center return, small error, and good repeatability, is still a difficult problem to be solved by those skilled in the art. SUMMARY

[0005] The present application relates to the technical field of hydraulic control, in particular to an automatic following steering control hydraulic system for a ladle transport vehicle.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The application discloses an automatic following and steering control hydraulic system of a ladle transporting vehicle, which is installed on the ladle transporting vehicle and comprises a variable plunger pump, a front steering control system, a front steering execution element, a front steering following system, a rear steering control system, a rear steering execution element, a rear steering following system, a front wheel position feedback device, a rear wheel position feedback device, a PLC controller and a remote controller.

[0008] The front steering control system is in fluid connection with the variable plunger pump and the front steering execution element and is used for actively controlling the front wheel steering.

[0009] The front steering execution element comprises a front right oil cylinder and a front left oil cylinder and is used for driving the front wheel steering.

[0010] The rear steering control system is in fluid connection with the variable plunger pump and the rear steering execution element and is used for actively controlling the rear wheel steering.

[0011] The rear steering execution element comprises a rear left oil cylinder and a rear right oil cylinder and is used for driving the rear wheel steering.

[0012] The front steering following system is in fluid connection with the variable plunger pump and the front steering control system and is electrically connected with the PLC controller and is used for actively controlling the front wheel automatic following of the rear wheel steering when the rear wheel steering is actively controlled.

[0013] The rear steering following system is in fluid connection with the variable plunger pump and the rear steering control system and is electrically connected with the PLC controller and is used for actively controlling the rear wheel automatic following of the front wheel steering when the front wheel steering is actively controlled.

[0014] The front wheel position feedback device is arranged on a front wheel axle and is electrically connected with the PLC controller and is used for measuring the front wheel position information and transmitting the measurement value to the PLC controller.

[0015] The rear wheel position feedback device is arranged on a rear wheel axle and is electrically connected with the PLC controller and is used for measuring the rear wheel position information and transmitting the measurement value to the PLC controller.

[0016] The remote controller is in wireless communication connection with the PLC controller.

[0017] Further, the front turning control system comprises a front flow amplification valve, a front steering gear, a front left limit electromagnetic valve and a front right limit electromagnetic valve, an HP port of the front flow amplification valve is fluidly connected with an oil outlet of the variable piston pump, a P port of the front flow amplification valve is fluidly connected with a P port of the front steering gear, an L port of the front steering gear is fluidly connected with a P port of the front left electromagnetic limit valve through a first shuttle valve, an A port of the front left electromagnetic limit valve is fluidly connected with an L port of the front flow amplification valve, an R port of the front steering gear is fluidly connected with a P port of the front right electromagnetic limit valve through a second shuttle valve, an A port of the front right electromagnetic limit valve is fluidly connected with an R port of the front flow amplification valve, a CL port of the front flow amplification valve is fluidly connected with a front right cylinder large cavity and a front left cylinder small cavity, and a CR port of the front flow amplification valve is fluidly connected with a front right cylinder small cavity and a front left cylinder large cavity.

[0018] Further, the rear turning control system comprises a rear flow amplification valve, a rear steering gear, a rear left limit electromagnetic valve and a rear right limit electromagnetic valve, an HP port of the rear flow amplification valve is fluidly connected with an oil outlet of the variable piston pump, a P port of the rear flow amplification valve is fluidly connected with a P port of the rear steering gear, an L port of the rear steering gear is fluidly connected with a P port of the rear left electromagnetic limit valve through a third shuttle valve, an A port of the rear left electromagnetic limit valve is fluidly connected with an L port of the rear flow amplification valve, an R port of the rear steering gear is fluidly connected with a P port of the rear right limit electromagnetic valve through a fourth shuttle valve, an A port of the rear right limit electromagnetic valve is fluidly connected with an R port of the rear flow amplification valve, a CL port of the rear flow amplification valve is fluidly connected with a rear right cylinder large cavity and a rear left cylinder small cavity, and a CR port of the rear flow amplification valve is fluidly connected with a rear right cylinder small cavity and a rear left cylinder large cavity.

[0019] Further, the front turning following system comprises a front proportional directional valve, a P port of the front proportional directional valve is fluidly connected with an oil outlet of the variable piston pump, and A and B ports of the front proportional directional valve are respectively fluidly connected with the second shuttle valve and the first shuttle valve.

[0020] Further, the front proportional directional valve is fluidly connected with a fifth shuttle valve, two oil inlet ports of the fifth shuttle valve are respectively communicated with A and B ports of the front proportional directional valve, the fifth shuttle valve is fluidly connected with a sixth shuttle valve, one oil inlet port of the sixth shuttle valve is communicated with an oil outlet port of the fifth shuttle valve, another oil inlet port of the sixth shuttle valve is communicated with an Ls port of the front steering gear, an oil outlet port of the sixth shuttle valve is communicated with an Ls port of the front flow amplification valve and fluidly connected with a seventh shuttle valve, and an oil outlet port of the seventh shuttle valve is fluidly connected with an X port of the variable piston pump.

[0021] Further, the rear turning following system comprises a rear proportional directional valve, a P port of the rear proportional directional valve is fluidly connected with an oil outlet of the variable piston pump, and A and B ports of the rear proportional directional valve are respectively fluidly connected with the third shuttle valve and the fourth shuttle valve.

[0022] Further, the rear proportional directional valve is fluidly connected with an eighth shuttle valve, two oil inlets of the eighth shuttle valve are in communication with A and B ports of the rear proportional directional valve respectively, the eighth shuttle valve is fluidly connected with a ninth shuttle valve, one oil inlet of the ninth shuttle valve is in communication with an oil outlet of the eighth shuttle valve, another oil inlet of the ninth shuttle valve is in communication with an Ls port of the rear steering gear, and the oil outlet of the ninth shuttle valve is in communication with an Ls port of the rear flow amplification valve and is fluidly connected with the seventh shuttle valve.

[0023] Further, the front wheel position feedback device comprises a first angle encoder, the first angle encoder is installed on a front wheel axle, the first angle encoder is electrically connected with the PLC controller, and the first angle encoder is used for measuring and transmitting a front wheel steering angle.

[0024] Further, the rear wheel position feedback device comprises a second angle encoder, the second angle encoder is installed on a rear wheel axle, the second angle encoder is electrically connected with the PLC controller, and the second angle encoder is used for measuring and transmitting a rear wheel steering angle.

[0025] Further, the front proportional directional valve and the rear proportional directional valve are three-position four-way servo proportional directional valves.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] 1. The present application is provided with a front steering following system, a rear steering following system, a front wheel position feedback device and a rear wheel position feedback device, when the driver turns the steering wheel in the front cab to steer the front wheels, the PLC controller controls the rear steering following system according to the front wheel angle and the rear wheel angle fed back by the front wheel position feedback device and the rear wheel position feedback device after analysis and comparison, so that the rear steering cylinder is synchronized with the front steering cylinder, realizing the function of automatic synchronous following of the rear wheels steering the front wheels. When the driver turns the steering wheel in the rear cab to steer the rear wheels, the PLC controller controls the front steering following system according to the front wheel angle and the rear wheel angle fed back by the front wheel position feedback device and the rear wheel position feedback device after analysis and comparison, so that the front steering cylinder is synchronized with the rear steering cylinder, realizing the function of automatic synchronous following of the front wheels steering the rear wheels. The present application is accurate in the middle position, has small synchronization error of the front and rear cylinders, good repeatability, and does not need oil supplement.

[0028] 2. The present application is provided with a remote controller, which is wirelessly connected with the PLC controller, and can realize the functions of remote control of the front wheel steering, synchronous following of the rear wheels / remote control of the rear wheel steering, synchronous following of the front wheels. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The hydraulic principle diagram of the present application;

[0030] Figure 2The front wheel is driven steering, and the rear wheel is automatically followed steering control principle diagram;

[0031] Figure 3 The rear wheel is driven steering, and the front wheel is automatically followed steering control principle diagram;

[0032] Figure 4 The prior art hydraulic principle diagram;

[0033] In the figure: 1 - oil filter, 2 - variable plunger pump, 3 - check valve, 4 - high pressure filter, 5 - front flow amplification valve, 6 - front steering gear, 7 - first shuttle valve, 8 - second shuttle valve, 9 - front left limit solenoid valve, 10 - front right limit solenoid valve, 11 - front right oil cylinder, 12 - front left oil cylinder, 13 - front proportional directional valve, 14 - fifth shuttle valve, 15 - sixth shuttle valve, 16 - seventh shuttle valve, 17 - rear flow amplification valve, 18 - rear steering gear, 19 - third shuttle valve, 20 - fourth shuttle valve, 21 - rear left limit solenoid valve, 22 - rear right limit solenoid valve, 23 - rear left oil cylinder, 24 - rear right oil cylinder, 25 - rear proportional directional valve, 26 - eighth shuttle valve, 27 - ninth shuttle valve, 28 - first angle encoder, 29 - second angle encoder, 30 - PLC controller, 31 - remote controller, 32 - front steering column, 33 - rear steering column, 34 - oil return filter, 35 - oil supplement pump, 36 - oil supplement pump overflow valve, 37 - oil supplement switch valve, 38 - oil supplement overflow valve, 39 - oil supplement ball valve, 40 - limit solenoid valve, 41 - flow amplification valve. DETAILED DESCRIPTION

[0034] The application will be described in detail below with reference to the drawings and specific examples. EXAMPLE

[0035] Please refer to Figures 1-2The application discloses an automatic following and steering control hydraulic system of a ladle transporting vehicle, which is installed on the ladle transporting vehicle and comprises a variable plunger pump 2, a front steering control system, a front steering execution element, a front steering following system, a rear steering control system, a rear steering execution element, a rear steering following system, a front wheel position feedback device, a rear wheel position feedback device, a PLC controller 30 and a remote controller 31; the front steering control system is in fluid connection with the variable plunger pump 2 and the front steering execution element and is used for actively controlling the front wheel steering; the front steering execution element comprises a front right oil cylinder 11 and a front left oil cylinder 12 and is used for driving the front wheel steering; the rear steering control system is in fluid connection with the variable plunger pump 2 and the rear steering execution element and is used for actively controlling the rear wheel steering; the rear steering execution element comprises a rear left oil cylinder 23 and a rear right oil cylinder 24 and is used for driving the rear wheel steering; the front steering following system is in fluid connection with the variable plunger pump 2 and the front steering control system and is electrically connected with the PLC controller 30 and is used for actively controlling the front wheel automatic following of the rear wheel steering; the rear steering following system is in fluid connection with the variable plunger pump 2 and the rear steering control system and is electrically connected with the PLC controller 30 and is used for actively controlling the rear wheel automatic following of the front wheel steering; the front wheel position feedback device is arranged on a front wheel axle and is electrically connected with the PLC controller 30 and is used for measuring the front wheel position information and transmitting the measurement value to the PLC controller 30; the rear wheel position feedback device is arranged on a rear wheel axle and is electrically connected with the PLC controller 30 and is used for measuring the rear wheel position information and transmitting the measurement value to the PLC controller 30; the remote controller 31 is in wireless communication connection with the PLC controller 30 and can control the PLC controller 30 to achieve the purpose of steering the vehicle outside the vehicle.

[0036] The front steering control system comprises a front flow amplification valve 5, a front steering gear 6, a front left limiting electromagnetic valve 9 and a front right limiting electromagnetic valve 10; the HP port of the front flow amplification valve 5 is in fluid connection with the oil outlet of the variable plunger pump 2; the P port of the front flow amplification valve 5 is in fluid connection with the P port of the front steering gear 6; the L port of the front steering gear 6 is in fluid connection with the P port of the front left limiting electromagnetic valve 9 through the first shuttle valve 7; the A port of the front left limiting electromagnetic valve 9 is in fluid connection with the L port of the front flow amplification valve 5; the R port of the front steering gear 6 is in fluid connection with the P port of the front right limiting electromagnetic valve 10 through the second shuttle valve 8; the A port of the front right limiting electromagnetic valve 10 is in fluid connection with the R port of the front flow amplification valve 5; the CL port of the front flow amplification valve 5 is in fluid connection with the large cavity of the front right oil cylinder 11 and the small cavity of the front left oil cylinder 12; and the CR port of the front flow amplification valve 5 is in fluid connection with the small cavity of the front right oil cylinder 11 and the large cavity of the front left oil cylinder 12.

[0037] Wherein, the rear steering control system comprises a rear flow amplification valve 17, a rear steering gear 18, a rear left limit electromagnetic valve 21, a rear right limit electromagnetic valve 22, the HP port of the rear flow amplification valve 17 is fluidly connected with the oil outlet of the variable piston pump 2, the P port of the rear flow amplification valve 17 is fluidly connected with the P port of the rear steering gear 18, the L port of the rear steering gear 18 is fluidly connected with the P port of the rear left electromagnetic limit valve 21 through the third shuttle valve 19, the A port of the rear left electromagnetic limit valve 21 is fluidly connected with the L port of the rear flow amplification valve 17, the R port of the rear steering gear 18 is fluidly connected with the P port of the rear right limit electromagnetic valve 22 through the fourth shuttle valve 20, the A port of the rear right limit electromagnetic valve 22 is fluidly connected with the R port of the rear flow amplification valve 17, the CL port of the rear flow amplification valve 17 is fluidly connected with the large cavity of the rear right oil cylinder 24 and the small cavity of the rear left oil cylinder 23, and the CR port of the rear flow amplification valve 17 is fluidly connected with the small cavity of the rear right oil cylinder 24 and the large cavity of the rear left oil cylinder 23.

[0038] Wherein, the front steering follow-up system comprises a front proportional directional valve 13, the P port of the front proportional directional valve 13 is fluidly connected with the oil outlet of the variable piston pump 2, and the A port and the B port of the front proportional directional valve 13 are respectively fluidly connected with the second shuttle valve 8 and the first shuttle valve 7.

[0039] Wherein, the front proportional directional valve 13 is fluidly connected with a fifth shuttle valve 14, two oil inlet ports of the fifth shuttle valve 14 are respectively communicated with the A port and the B port of the front proportional directional valve 13, the fifth shuttle valve 14 is fluidly connected with a sixth shuttle valve 15, one oil inlet port of the sixth shuttle valve 15 is communicated with the oil outlet of the fifth shuttle valve 14, the other oil inlet port of the sixth shuttle valve 15 is communicated with the Ls port of the front steering gear 6, the oil outlet of the sixth shuttle valve 15 is communicated with the Ls port of the front flow amplification valve 5 and fluidly connected with a seventh shuttle valve 16, the oil outlet of the seventh shuttle valve 16 is fluidly connected with the X port of the variable piston pump 2, when the front wheel is steering, the front proportional directional valve 13, the front steering gear 6 and the front flow amplification valve 5 transmit the load pressure to the variable piston pump 2, the variable piston pump 2 automatically compensates the pressure difference, so that the pressure before and after the valve is constant, the flow is accurately controlled, the steering load sensitive control is realized, and the power consumption of the hydraulic system is reduced.

[0040] Wherein, the rear steering follow-up system comprises a rear proportional directional valve 25, the P port of the rear proportional directional valve 25 is fluidly connected with the oil outlet of the variable piston pump 2, and the A port and the B port of the rear proportional directional valve 25 are respectively fluidly connected with the third shuttle valve 19 and the fourth shuttle valve 20.

[0041] The rear proportional directional valve 25 is fluidly connected with an eighth shuttle valve 26, two oil inlets of the eighth shuttle valve 26 are respectively communicated with the A port and the B port of the rear proportional directional valve 25, the eighth shuttle valve 26 is fluidly connected with a ninth shuttle valve 27, one oil inlet of the ninth shuttle valve 27 is communicated with the oil outlet of the eighth shuttle valve 26, the other oil inlet of the ninth shuttle valve 27 is communicated with the Ls port of the rear steering gear 18, the oil outlet of the ninth shuttle valve 27 is communicated with the Ls port of the rear flow amplification valve 17 and is fluidly connected with the seventh shuttle valve 16, when the rear wheel is steered, the rear proportional directional valve 25, the rear steering gear 18 and the rear flow amplification valve 17 transmit the load pressure to the variable piston pump 2, the variable piston pump 2 automatically compensates the pressure difference, so that the pressure before and after the valve is constant, the flow is accurately controlled, the steering load sensitive control is realized, and the power consumption of the hydraulic system is reduced.

[0042] The front wheel position feedback device comprises a first angle encoder 28, the first angle encoder 28 is installed on the front wheel axle, the first angle encoder 28 is electrically connected with the PLC controller 30, and the first angle encoder 28 is used for measuring and transmitting the front wheel steering angle.

[0043] The rear wheel position feedback device comprises a second angle encoder 29, the second angle encoder 29 is installed on the rear wheel axle, the second angle encoder 29 is electrically connected with the PLC controller 30, and the second angle encoder 29 is used for measuring and transmitting the rear wheel steering angle.

[0044] The front proportional directional valve 13 and the rear proportional directional valve 25 are three-position four-way servo proportional directional valves.

[0045] When the ladle transport vehicle is running in a straight line, the front steering gear 6, the rear steering gear 18, the front proportional directional valve 13 and the rear proportional directional valve 25 are all in the middle position, and the front right oil cylinder 11, the front left oil cylinder 12, the rear right oil cylinder 24 and the rear left oil cylinder 23 do not act. When the driver starts to turn the steering wheel to the left in the front cab, the front steering column 32 is turned, the P port of the front steering gear 6 is in communication with the L port, and the hydraulic oil from the hydraulic oil tank enters the P port of the front steering gear 6 through the oil suction filter 1, the variable plunger pump 2, the check valve 3, the high-pressure filter 4, the HP port and the P port of the front flow amplification valve 5, and then enters the L port of the front steering gear 6, and then enters the front flow amplification valve 5 through the first shuttle valve 7, the P port and the A port of the front left electromagnetic limiting valve 9 and the L port of the front flow amplification valve 5, and then enters the front right oil cylinder 11 large cavity and the front left oil cylinder 12 small cavity through the CL port of the front flow amplification valve 5 after the flow amplification of the front flow amplification valve 5, and then pushes the front right oil cylinder 11 and the front left oil cylinder 12 to drive the front wheel to turn to the left, so as to realize the function of turning the front wheel to the left. At the same time, the oil in the front right oil cylinder 11 small cavity and the front left oil cylinder 12 large cavity flows back to the oil tank through the CR port and the T port of the front flow amplification valve 5 and the oil return filter 34. At the same time, the first angle encoder 28 and the second angle encoder 29 respectively transmit the angle information of the front wheel and the rear wheel to the PLC controller 30, and the PLC controller 30 analyzes and compares the angle values of the front wheel and the rear wheel, and when the function value is greater than the set coefficient ε, the PLC controller 30 calculates and outputs the PWM proportional signal to the rear proportional directional valve 25 in the proportional-differential (PD) control mode, and when the function value is not greater than the set coefficient ε, the PLC controller 30 calculates and outputs the PWM proportional signal to the rear proportional directional valve 25 in the proportional-integral-differential (PID) control mode. The valve core of the rear proportional directional valve 25 moves to the right and adjusts the opening degree of the valve port in real time according to the proportional signal. The P port of the rear proportional directional valve 25 is connected with the A port, and part of the hydraulic oil from the variable plunger pump 2 enters the rear flow amplification valve 17 through the P port and the A port of the rear proportional directional valve 25, the third shuttle valve 19, the P port and the A port of the rear left electromagnetic limiting valve 21 and the L port of the rear flow amplification valve 17, and then enters the rear flow amplification valve 17 after the flow amplification of the rear flow amplification valve 17, and then enters the rear right oil cylinder 24 large cavity and the rear left oil cylinder 23 small cavity through the CL port of the rear flow amplification valve 17, and then pushes the rear right oil cylinder 24 and the rear left oil cylinder 23 to drive the rear wheel to turn to the left. Since the output hydraulic oil quantity of the rear proportional directional valve 25 is controlled by the PWM proportional signal, the rear right oil cylinder 24 and the rear left oil cylinder 23 act synchronously and at the same speed as the front right oil cylinder 11 and the front left oil cylinder 12 respectively, so as to realize the function of automatically following the front wheel to turn to the left. The oil in the rear right oil cylinder 24 small cavity and the rear left oil cylinder 23 large cavity flows back to the oil tank through the CR port and the T port of the rear flow amplification valve 17 and the oil return filter 34.

[0046] When the current wheel left turns to the limit position, the front left electromagnetic limit valve 9 is actuated, the valve core moves down, the P port of the front left electromagnetic limit valve 9 is communicated with the B port, the oil path to the L port of the front flow amplification valve 5 is disconnected, the front right oil cylinder 11 and the front left oil cylinder 12 are no longer driven to act, and the oil cylinder impact is prevented. When the rear wheel follows the front wheel left turning to the limit position, the rear left electromagnetic limit valve 21 is actuated, the valve core moves down, the P port of the rear left electromagnetic limit valve 21 is communicated with the B port, the oil path to the L port of the rear flow amplification valve 17 is disconnected, the rear right oil cylinder 24 and the rear left oil cylinder 23 are no longer driven to act, and the oil cylinder impact is prevented.

[0047] Similarly, when the driver starts the front wheel right turning by turning the steering wheel right in the front cab, the front steering column 32 is turned, the P port of the front steering gear 6 is communicated with the R port inside, the hydraulic oil enters the P port of the front steering gear 6 from the hydraulic oil tank through the oil suction filter 1, the variable plunger pump 2, the check valve 3, the high-pressure filter 4, the HP port and the P port of the front flow amplification valve 5, enters the front flow amplification valve 5 from the R port of the front steering gear 6 through the second shuttle valve 8, the P port and the A port of the front right limit electromagnetic valve 10, and the R port of the front flow amplification valve 5, enters the front right oil cylinder 11 small cavity and the front left oil cylinder 12 large cavity from the CR port of the front flow amplification valve 5 after the flow amplification of the front flow amplification valve 5, drives the front right oil cylinder 11 and the front left oil cylinder 12 to turn the front wheel right, realizes the front wheel right turning function, and the oil in the front right oil cylinder 11 large cavity and the front left oil cylinder 12 small cavity flows back to the oil tank through the CL port, the T port of the front flow amplification valve 5 and the oil return filter 34. At the same time, the first angle encoder 28 and the second angle encoder 29 respectively transmit the angle information of the front wheel and the rear wheel to the PLC controller 30, the PLC controller 30 performs function analysis and comparison on the angle values of the rear wheel and the front wheel, and outputs the PWM proportional signal to the rear proportional directional valve 25 according to the comparison value. The valve core of the rear proportional directional valve 25 moves left and adjusts the valve port opening degree in real time according to the proportional signal. The P port of the rear proportional directional valve 25 is communicated with the B port, part of the hydraulic oil from the variable plunger pump 2 enters the rear flow amplification valve 17 through the P port, the B port of the rear proportional directional valve 25, the fourth shuttle valve 20, the P port and the A port of the rear right limit electromagnetic valve 22, and the R port of the rear flow amplification valve 17, is amplified by the rear flow amplification valve 17, enters the rear right oil cylinder 24 small cavity and the rear left oil cylinder 23 large cavity from the CR port of the rear flow amplification valve 17, drives the rear right oil cylinder 24 and the rear left oil cylinder 23 to turn the rear wheel right. Since the output hydraulic oil quantity of the rear proportional directional valve 25 is controlled by the PWM proportional signal, the rear right oil cylinder 24 and the rear left oil cylinder 23 respectively act synchronously and at the same speed as the front right oil cylinder 11 and the front left oil cylinder 12, so as to realize the function of automatically synchronizing the rear wheel to follow the front wheel right turning. The oil in the rear right oil cylinder 24 large cavity and the rear left oil cylinder 23 small cavity flows back to the oil tank through the CL port, the T port of the rear flow amplification valve 17 and the oil return filter 34.

[0048] When the current wheel right steering reaches the limit position, the front right limit electromagnetic valve 10 is actuated, the valve core moves down, the P port of the front right limit electromagnetic valve 10 is communicated with the B port, the oil path to the R port of the front flow amplification valve 5 is disconnected, the front right oil cylinder 11 and the front left oil cylinder 12 are no longer driven to act, and the impact of the oil cylinder is prevented. When the rear wheel follows the front wheel right steering to reach the limit position, the rear right limit electromagnetic valve 22 is actuated, the valve core moves down, the P port of the rear right limit electromagnetic valve 22 is communicated with the B port, the oil path to the R port of the rear flow amplification valve 17 is disconnected, the rear right oil cylinder 24 and the rear left oil cylinder 23 are no longer driven to act, and the impact of the oil cylinder is prevented. Embodiment

[0049] Please refer to Figure 1 and Figure 3 When the driver turns the steering wheel in the rear cab to the left to start the rear wheel left steering, the rear steering column 33 is turned, the P port of the rear steering gear 18 is communicated with the inside of the L port, the hydraulic oil enters the P port of the rear steering gear 18 from the hydraulic oil tank through the oil suction filter 1, the variable plunger pump 2, the one-way valve 3, the high-pressure filter 4, the HP port and the P port of the rear flow amplification valve 17, and then enters the rear flow amplification valve 17 from the L port of the rear steering gear 18 through the third shuttle valve 19, the P port, the A port of the rear left limit electromagnetic valve 21 and the L port of the rear flow amplification valve 17. After being amplified by the rear flow amplification valve 17, the hydraulic oil enters the large cavity of the rear right oil cylinder 24 and the small cavity of the rear left oil cylinder 23 from the CL port of the rear flow amplification valve 17, pushes the rear right oil cylinder 24 and the rear left oil cylinder 23 to drive the rear wheel left steering, and realizes the rear wheel left steering function. At the same time, the first angle encoder 28 and the second angle encoder 29 respectively transmit the angle information of the front wheel and the rear wheel to the PLC controller 30, the PLC controller 30 performs function analysis and comparison on the angle values of the front wheel and the rear wheel. When the function value is greater than the set coefficient ε, the PLC controller 30 calculates and outputs the PWM proportional signal to the front proportional directional valve 13 in the proportional-differential (PD) control mode. When the function value is not greater than the set coefficient ε, the PLC controller 30 calculates and outputs the PWM proportional signal to the front proportional directional valve 13 in the proportional-integral-differential (PID) control mode. The valve core of the front proportional directional valve 13 moves to the left and adjusts the valve port opening degree in real time according to the proportional signal. The P port of the front proportional directional valve 13 is connected with the B port, part of the hydraulic oil from the variable plunger pump 2 enters the front flow amplification valve 5 through the P port, the B port of the front proportional directional valve 13, the first shuttle valve 7, the P port and the A port of the front left electromagnetic limit valve 9 and the L port of the front flow amplification valve 5. After being amplified by the front flow amplification valve 5, the hydraulic oil enters the large cavity of the front right oil cylinder 11 and the small cavity of the front left oil cylinder 12 from the CL port of the front flow amplification valve 5, pushes the front right oil cylinder 11 and the front left oil cylinder 12 to drive the front wheel left steering. Since the output hydraulic oil quantity of the front proportional directional valve 13 is controlled by the PWM proportional signal, the front right oil cylinder 11 and the front left oil cylinder 12 move synchronously and at the same speed with the rear right oil cylinder 24 and the rear left oil cylinder 23 respectively, so as to realize the function of the front wheel automatically following the rear wheel left steering.

[0050] When the driver turns the steering wheel to the right in the rear cab to start the right turning of the rear wheels, the rear steering column 33 rotates accordingly, the P port of the rear steering gear 18 is in communication with the R port inside, the hydraulic oil from the hydraulic oil tank enters the P port of the rear steering gear 18 through the oil suction filter 1, the variable plunger pump 2, the one-way valve 3, the high-pressure filter 4, the HP port and the P port of the rear flow amplification valve 17, from the R port of the rear steering gear 18 through the fourth shuttle valve 20, the P port and the A port of the rear right limit electromagnetic valve 22, the R port of the rear flow amplification valve 17 into the rear flow amplification valve 17, after the flow amplification of the rear flow amplification valve 17, from the CR port of the rear flow amplification valve 17 into the small cavity of the rear right oil cylinder 24 and the large cavity of the rear left oil cylinder 23, to push the rear right oil cylinder 24 and the rear left oil cylinder 23 to drive the right turning of the rear wheels, realize the right turning function of the rear wheels, at the same time, the first angle encoder 28 and the second angle encoder 29 respectively transmit the angle information of the front wheels and the rear wheels to the PLC controller 30, the PLC controller 30 analyzes and compares the angle values of the front wheels and the rear wheels, when the function value is greater than the set coefficient ε, the PLC controller 30 calculates and outputs the PWM proportional signal to the front proportional directional valve 13 in the proportional-differential (PD) control mode, when the function value is not greater than the set coefficient ε, the PLC controller 30 calculates and outputs the PWM proportional signal to the front proportional directional valve 13 in the proportional-integral-differential (PID) control mode, the spool of the front proportional directional valve 13 moves to the right and adjusts the valve port opening degree in real time according to the proportional signal, the P port and the A port of the front proportional directional valve 13 are connected, part of the hydraulic oil from the variable plunger pump 2 enters the front flow amplification valve 5 through the P port, the A port of the front proportional directional valve 13, the second shuttle valve 8, the P port and the A port of the front right limit electromagnetic valve 10, the R port of the front flow amplification valve 5, after the flow amplification of the front flow amplification valve 5, from the CR port of the front flow amplification valve 5 into the small cavity of the front right oil cylinder 11 and the large cavity of the front left oil cylinder 12, to push the front right oil cylinder 11 and the front left oil cylinder 12 to drive the right turning of the front wheels, because the output hydraulic oil quantity of the front proportional directional valve 13 is controlled by the PWM proportional signal, the front right oil cylinder 11 and the front left oil cylinder 12 move synchronously and at the same speed with the rear right oil cylinder 24 and the rear left oil cylinder 23 respectively, so as to realize the function of automatically following the right turning of the front wheels with the rear wheels. Embodiment

[0051] Please refer to Figures 1-2When the ladle transport vehicle is remotely controlled, the steering instruction is transmitted to the PLC controller 30 by operating the left steering handle in the remote controller 31, the PLC controller 30 proportionally controls the spool of the front proportional reversing valve 13 to move left, and the function of remotely controlling the left steering of the front wheels is realized. Meanwhile, the PLC controller 30 proportionally controls the spool of the rear proportional reversing valve 25 to move right and proportionally outputs the hydraulic oil according to the rotation angle information fed back by the first angle encoder 28 and the second angle encoder 29 after analysis and comparison, so that the front right oil cylinder 11 and the front left oil cylinder 12 move at the same speed synchronously with the rear right oil cylinder 24 and the rear left oil cylinder 23, and the function of automatically synchronously following the rear wheels with the left steering of the front wheels is realized. Similarly, the right steering handle in the remote controller 31 can also realize the functions of remotely controlling the right steering of the front wheels and automatically synchronously following the rear wheels with the right steering of the front wheels.

[0052] Comparative example:

[0053] As shown in the prior art, Figure 4 The front steering gear 6 and the rear front steering gear 18 are fluidly connected with a flow amplification valve 41 through a limiting electromagnetic valve 40, the flow amplification valve 41 is fluidly connected with the front right oil cylinder 11, the front left oil cylinder 12, the rear right oil cylinder 24 and the rear left oil cylinder 23, the rodless cavities of the front right oil cylinder 11, the front left oil cylinder 12, the rear right oil cylinder 24 and the rear left oil cylinder 23 are interconnected and fluidly connected with an oil supplementing circuit, the oil supplementing circuit includes an oil supplementing pump 35, an oil supplementing pump relief valve 36, an oil supplementing switch valve 37, an oil supplementing relief valve 38 and an oil supplementing ball valve 39. Due to the position difference between the near end and the far end of the four oil cylinders, the hydraulic oil flow is not evenly distributed, which causes the front and rear oil cylinders to move out of synchronization during steering, the steering is biased, the oil cylinder on one side is pressurized at the steering limit position, the deviation of the neutral position is large, manual oil supplementing adjustment of the neutral position is required, and the user is inconvenient and difficult to operate.

[0054] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A ladle car automatic follow-up steering control hydraulic system installed on a ladle car, characterized in that: The variable piston pump (2), the front steering control system, the front steering execution element, the front steering follow-up system, the rear steering control system, the rear steering execution element, the rear steering follow-up system, the front wheel position feedback device, the rear wheel position feedback device, the PLC controller (30) and the remote controller (31) are included. The front steering control system is fluidly connected with the variable piston pump (2) and the front steering execution element, and is used for actively controlling the front wheel steering. The front steering execution element comprises a front right oil cylinder (11) and a front left oil cylinder (12), and is used for driving the front wheel steering. The rear steering control system is fluidly connected with the variable piston pump (2) and the rear steering execution element, and is used for actively controlling the rear wheel steering. The rear steering execution element comprises a rear left oil cylinder (23) and a rear right oil cylinder (24), and is used for driving the rear wheel steering. The front steering follow-up system is fluidly connected with the variable piston pump (2) and the front steering control system, and is electrically connected with the PLC controller (30), and is used for automatically following the rear wheel steering when the front wheel is actively controlled to steer. The rear steering follow-up system is fluidly connected with the variable piston pump (2) and the rear steering control system, and is electrically connected with the PLC controller (30), and is used for automatically following the front wheel steering when the rear wheel is actively controlled to steer. The front wheel position feedback device is arranged on the front wheel axle and is electrically connected with the PLC controller (30), and is used for measuring the front wheel position information and transmitting the measurement value to the PLC controller (30). The rear wheel position feedback device is arranged on the rear wheel axle and is electrically connected with the PLC controller (30), and is used for measuring the rear wheel position information and transmitting the measurement value to the PLC controller (30). The remote controller (31) is wirelessly connected with the PLC controller (30). The front steering follow-up system comprises a front proportional directional valve (13), a P port of the front proportional directional valve (13) is fluidly connected with an oil outlet of the variable piston pump (2), A and B ports of the front proportional directional valve (13) are respectively fluidly connected with a second shuttle valve (8) and a first shuttle valve (7). The front proportional directional valve (13) is fluidly connected with a fifth shuttle valve (14), two oil inlets of the fifth shuttle valve (14) are respectively communicated with A and B ports of the front proportional directional valve (13), the fifth shuttle valve (14) is fluidly connected with a sixth shuttle valve (15), one oil inlet of the sixth shuttle valve (15) is communicated with an oil outlet of the fifth shuttle valve (14), another oil inlet of the sixth shuttle valve (15) is communicated with an Ls port of the front steering gear (6), an oil outlet of the sixth shuttle valve (15) is communicated with an Ls port of the front flow amplification valve (5) and is fluidly connected with a seventh shuttle valve (16), an oil outlet of the seventh shuttle valve (16) is fluidly connected with an X port of the variable piston pump (2). The rear steering follow-up system comprises a rear proportional directional valve (25), a P port of the rear proportional directional valve (25) is fluidly connected with an oil outlet of the variable piston pump (2), A and B ports of the rear proportional directional valve (25) are respectively fluidly connected with a third shuttle valve (19) and a fourth shuttle valve (20). The rear proportional directional valve (25) is fluidly connected with an eighth shuttle valve (26), two oil inlets of the eighth shuttle valve (26) are in communication with A and B ports of the rear proportional directional valve (25) respectively, the eighth shuttle valve (26) is fluidly connected with a ninth shuttle valve (27), one oil inlet of the ninth shuttle valve (27) is in communication with an oil outlet of the eighth shuttle valve (26), another oil inlet of the ninth shuttle valve (27) is in communication with an Ls port of the rear steering gear (18), the oil outlet of the ninth shuttle valve (27) is in communication with an Ls port of the rear flow amplification valve (17) and is fluidly connected with the seventh shuttle valve (16); The front wheel position feedback device comprises a first angle encoder (28), the first angle encoder (28) is installed on a front wheel axle, the first angle encoder (28) is electrically connected with a PLC controller (30), and the first angle encoder (28) is used for measuring and transmitting a front wheel steering angle; The rear wheel position feedback device comprises a second angle encoder (29), the second angle encoder (29) is installed on a rear wheel axle, the second angle encoder (29) is electrically connected with the PLC controller (30), and the second angle encoder (29) is used for measuring and transmitting a rear wheel steering angle; The first angle encoder (28) and the second angle encoder (29) respectively transmit angle information of the front wheel and the rear wheel to the PLC controller (30), the PLC controller (30) performs function analysis and comparison on angle values of the rear wheel and the front wheel, when a function value is greater than a set coefficient ε, the PLC controller (30) calculates and outputs a PWM proportional signal to the rear proportional directional valve (25) in a proportional-differential (PD) control mode, when the function value is not greater than the set coefficient ε, the PLC controller (30) calculates and outputs the PWM proportional signal to the rear proportional directional valve (25) in a proportional-integral-differential (PID) control mode, the rear proportional directional valve (25) adjusts a valve port opening degree in real time according to the proportional signal, so that the rear right oil cylinder (24) and the rear left oil cylinder (23) move synchronously and at the same speed with the front right oil cylinder (11) and the front left oil cylinder (12) respectively, thereby realizing a rear wheel automatic synchronous following front wheel left steering function.

2. The automatic following and steering hydraulic system of the ladle transport vehicle according to claim 1, characterized in that: The front steering control system comprises a front flow amplification valve (5), a front steering gear (6), a front left limiting electromagnetic valve (9), and a front right limiting electromagnetic valve (10). The HP port of the front flow amplification valve (5) is fluidly connected with the oil outlet of the variable plunger pump (2). The P port of the front flow amplification valve (5) is fluidly connected with the P port of the front steering gear (6). The L port of the front steering gear (6) is fluidly connected with the P port of the front left electromagnetic limiting valve (9) through the first shuttle valve (7). The A port of the front left electromagnetic limiting valve (9) is fluidly connected with the L port of the front flow amplification valve (5). The R port of the front steering gear (6) is fluidly connected with the P port of the front right electromagnetic limiting valve (10) through the second shuttle valve (8). The A port of the front right electromagnetic limiting valve (10) is fluidly connected with the R port of the front flow amplification valve (5). The CL port of the front flow amplification valve (5) is fluidly connected with the large cavity of the front right oil cylinder (11) and the small cavity of the front left oil cylinder (12). The CR port of the front flow amplification valve (5) is fluidly connected with the small cavity of the front right oil cylinder (11) and the large cavity of the front left oil cylinder (12).

3. The automatic following and steering hydraulic system for a ladle car, according to claim 1, characterized in that: The rear steering control system comprises a rear flow amplification valve (17), a rear steering gear (18), a rear left limiting electromagnetic valve (21), and a rear right limiting electromagnetic valve (22). The HP port of the rear flow amplification valve (17) is fluidly connected with the oil outlet of the variable plunger pump (2). The P port of the rear flow amplification valve (17) is fluidly connected with the P port of the rear steering gear (18). The L port of the rear steering gear (18) is fluidly connected with the P port of the rear left electromagnetic limiting valve (21) through the third shuttle valve (19). The A port of the rear left electromagnetic limiting valve (21) is fluidly connected with the L port of the rear flow amplification valve (17). The R port of the rear steering gear (18) is fluidly connected with the P port of the rear right limiting electromagnetic valve (22) through the fourth shuttle valve (20). The A port of the rear right limiting electromagnetic valve (22) is fluidly connected with the R port of the rear flow amplification valve (17). The CL port of the rear flow amplification valve (17) is fluidly connected with the large cavity of the rear right oil cylinder (24) and the small cavity of the rear left oil cylinder (23). The CR port of the rear flow amplification valve (17) is fluidly connected with the small cavity of the rear right oil cylinder (24) and the large cavity of the rear left oil cylinder (23).

4. The automatic follow-up turning control hydraulic system of the ladle car according to claim 1, characterized in that: The front proportional directional valve (13) and the rear proportional directional valve (25) are three-position four-way servo proportional directional valves.

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