CN211852324U - Overhead working platform walking control system - Google Patents

Abstract

An oil port A of a closed pump is respectively connected with a port B of a shuttle valve and ports A of third to sixth electromagnetic directional valves; the oil ports B of the first electromagnetic reversing valve and the second electromagnetic reversing valve are respectively connected with the port A of the shuttle valve and the ports P of the seventh electromagnetic reversing valve and the eighth electromagnetic reversing valve; ports B of the third electromagnetic directional valve and the fifth electromagnetic directional valve are respectively connected with ports A of the right rear motor and the left rear motor, and ports B of the fourth electromagnetic directional valve and the sixth electromagnetic directional valve are respectively connected with ports A of the right front motor and the left front motor; ports A and B of the seventh and eighth electromagnetic directional valves are respectively connected with ports B of a right rear motor, a left rear motor, a right front motor and a left front motor; the port C of the shuttle valve is connected with the port A of the first electromagnetic reversing valve through a reducing valve, a second hydraulic control reversing valve and a one-way valve, and the ports A of the first electromagnetic reversing valve and the second electromagnetic reversing valve are connected; the P port of the first electromagnetic directional valve is respectively connected with the brake of each walking motor; the P port of the second electromagnetic directional valve is respectively connected with the variable control oil cylinder of each walking motor through a pipeline. The system has good adaptability to the steering and walking conditions and good stability.

Description

Overhead working platform walking control system

Technical Field

The utility model belongs to the technical field of hydraulic control, concretely relates to aerial working platform walking control system.

Background

The existing walking system of the aerial work platform usually adopts the forms of full hydraulic proportional control and double-axle four-wheel drive. The motor is a two-position variable motor: i.e. the motor displacement can only be operated at maximum or minimum displacement. The motor swash plate is held at maximum displacement by a biasing spring and when a control signal is present, the swash plate switches to minimum displacement of the motor. The closed pump (proportional variable plunger pump) is adopted to realize the proportional control of the flow of the motor, so that the whole vehicle can carry out stepless speed regulation. When the engine is at the highest speed, the highest running speed of the vehicle is achieved through the control of the closed pump and the double-displacement motor. The displacement selection of the double-speed motor is realized through the electromagnetic directional valve, so that the switching between high speed and low speed is realized.

In the prior art, as shown in fig. 1, an aerial work platform walking control system is provided with three flow distributing and collecting valves, and according to the principle of uniform flow distribution, synchronous operation of wheels at the same rotating speed is realized, but the flow required by each walking motor is different in the process of steering and walking, so that the existing walking control system has poor adaptability to the steering and walking conditions, and is easy to have the conditions of shaking, sudden stop and sudden speed change during walking.

Disclosure of Invention

Problem to above-mentioned prior art exists, the utility model provides an aerial working platform walking control system, this system turn to walking operating mode adaptability good, can effectively eliminate shake, the condition of stopping suddenly and suddenly changing speed that the walking in-process appears, can effectively promote the stationarity of walking.

In order to achieve the aim, the utility model provides an aerial work platform walking control system, which comprises a closed pump, a rotary operating handle, a controller and a walking control valve assembly; the closed pump is provided with an oil port A and an oil port B;

the walking control valve assembly comprises a third electromagnetic proportional directional valve, a fourth electromagnetic proportional directional valve, a fifth electromagnetic proportional directional valve, a sixth electromagnetic proportional directional valve, a first electromagnetic directional valve, a second electromagnetic directional valve, a seventh electromagnetic proportional directional valve, an eighth electromagnetic proportional directional valve, a first electromagnetic directional valve, a second hydraulic directional valve, a shuttle valve, a pressure reducing valve and a back pressure valve;

an oil port A of the closed pump is respectively connected with a port B of the shuttle valve, a port A of the third electromagnetic proportional directional valve, a port A of the fourth electromagnetic proportional directional valve, a port A of the fifth electromagnetic proportional directional valve and a port A of the sixth electromagnetic proportional directional valve through pipelines;

an oil port B of the closed pump is respectively connected with an opening A of the shuttle valve, an opening P of the seventh electromagnetic proportional directional valve and an opening P of the eighth electromagnetic proportional directional valve through pipelines;

the port B of the third electromagnetic proportional reversing valve and the port B of the fifth electromagnetic proportional reversing valve are respectively connected with the port A of the right rear walking motor and the port A of the left rear walking motor through pipelines, and the port B of the fourth electromagnetic proportional reversing valve and the port B of the sixth electromagnetic proportional reversing valve are respectively connected with the port A of the right front walking motor and the port A of the left front walking motor through pipelines;

the port A and the port B of the seventh electromagnetic proportional reversing valve are respectively connected with the port B of the right rear walking motor and the port B of the left rear walking motor through pipelines, and the port A and the port B of the eighth electromagnetic proportional reversing valve are respectively connected with the port B of the right front walking motor and the port B of the left front walking motor through pipelines;

the right rear walking motor, the left rear walking motor, the right front walking motor and the left front walking motor are respectively connected with a brake and a variable control oil cylinder; the oil drainage ports of the right rear walking motor, the left rear walking motor, the right front walking motor and the left front walking motor are all connected with an oil tank through pipelines; the oil paths of the ports A of the right rear walking motor, the left rear walking motor, the right front walking motor and the left front walking motor are respectively provided with a flowmeter A, a flowmeter C, a flowmeter B and a flowmeter D;

the port C of the shuttle valve is connected with the port A of the second hydraulic control reversing valve and the left hydraulic control port of the second hydraulic control reversing valve through a pressure reducing valve, and the port B of the second hydraulic control reversing valve is connected with the oil tank through a back pressure valve after being communicated with the right spring cavity of the second hydraulic control reversing valve; the port P of the second hydraulic control reversing valve is connected with the port A of the first electromagnetic reversing valve through a one-way valve and is also connected with the port A of the second electromagnetic reversing valve through a pipeline, and the port B of the first electromagnetic reversing valve is connected with the port B of the second electromagnetic reversing valve through a throttling element after being communicated; the P port of the first electromagnetic directional valve is respectively connected with brakes of a right rear walking motor, a left rear walking motor, a right front walking motor and a left front walking motor through pipelines; the P port of the second electromagnetic directional valve is respectively connected with variable control oil cylinders of the right rear walking motor, the left rear walking motor, the right front walking motor and the left front walking motor through pipelines.

The controller is respectively connected with the closed pump, the rotary operating handle, the third electromagnetic proportional reversing valve, the fourth electromagnetic proportional reversing valve, the fifth electromagnetic proportional reversing valve, the sixth electromagnetic proportional reversing valve, the seventh electromagnetic proportional reversing valve, the eighth electromagnetic proportional reversing valve, the flowmeter A, the flowmeter C, the flowmeter B and the flowmeter D.

Further, in order to ensure that the working pressure of the system is within a set range, the one-way valve is connected with the oil tank through an overflow valve.

Furthermore, in order to realize stepless adjustment control of the whole vehicle, the closed pump is a proportional variable plunger pump.

Preferably, the second hydraulic directional control valve is a two-position three-way directional control valve having ports a, B, and P, and when the second hydraulic directional control valve operates in the left position, the port B is blocked, and the oil passage between the port a and the port P is communicated, and when the second hydraulic directional control valve operates in the right position, the port a is blocked, and the oil passage between the port B and the port P is communicated.

Preferably, the first electromagnetic directional valve and the second electromagnetic directional valve have the same structure and each have port a, port B, and port P, and when left energized, the oil passage between port a and port P is communicated, and port B is closed, and when de-energized, the oil passage between port B and port T is communicated, and port a is closed.

Preferably, the seventh electromagnetic proportional directional valve and the eighth electromagnetic proportional directional valve have the same structure, are three-position three-way proportional directional valves, and each have an port a, a port B, and a port P, and when the seventh electromagnetic proportional directional valve and the eighth electromagnetic proportional directional valve operate in the upper position, the port B is blocked, the oil path between the port a and the port P is communicated, when the seventh electromagnetic proportional directional valve and the eighth electromagnetic proportional directional valve operate in the middle position, the port P is simultaneously communicated with the port a and the port B, when the seventh electromagnetic proportional directional valve and the eighth electromagnetic proportional directional valve operate in the lower position, the port a is blocked, and the oil path between the.

Preferably, the third electromagnetic proportional directional valve, the fourth electromagnetic proportional directional valve, the fifth electromagnetic proportional directional valve and the sixth electromagnetic proportional directional valve have the same structure, are all two-position two-way proportional electromagnetic directional valves, and have ports a and B, when the valves operate in the left position, the ports a and B are both blocked, and when the valves operate in the right position, the oil passages between the ports a and B are communicated.

Preferably, the controller is of the type SIMATIC S7-200.

The utility model discloses in, be provided with the flowmeter on each walking motor's oil supply line, can each walking motor of real-time detection walk or turn to the flow variation condition of in-process at aerial working platform walking through the flowmeter, and then adjust the opening size that corresponds the proportional valve in real time according to each walking motor's needs, with the flow of each walking motor of effective control, thereby can be when turning to the walking operating mode, carry out independent control to the oil inlet and the oil return opening of motor, can the flow that the nimble control got into each walking motor, better adaptation turns to the needs of walking. The straight-line walking working condition can be met, the conditions of shaking, sudden stop and sudden speed change in the walking process are effectively solved, the stability of the walking process is greatly improved, and the problems that a system adopting a flow distributing and collecting valve is mainly suitable for the non-steering walking working condition and the walking process is unstable are solved. The utility model discloses a stopper and variable control oil cylinder are controlled to the high-pressure oil circuit of closed pump, the effectual stationarity that promotes the walking, further avoid appearing the walking shake, stop suddenly to and the problem of sudden change appears in walking speed. The influence of the fluctuation of the return oil pressure on the pressure reducing valve and the hydraulic control proportional reversing valve is reduced by adopting the one-way valve for high-pressure isolation. By adopting the technical scheme of combining the two-position two-way proportional valve and the three-position three-way proportional valve, the purchasing cost of parts is favorably reduced, and the overall manufacturing cost can be further reduced.

Drawings

FIG. 1 is a hydraulic schematic of a prior art walk control system;

fig. 2 is a hydraulic schematic diagram of the present invention.

In the figure: 11. the closed type pump comprises a closed type pump body 12, a traveling control valve assembly 13, a first hydraulic control reversing valve, a 13a, a third electromagnetic proportional reversing valve, a 13b, a fourth electromagnetic proportional reversing valve, a 13c, a fifth electromagnetic proportional reversing valve, a 13d, a sixth electromagnetic proportional reversing valve, a 14a, a right rear traveling motor, a 14b, a right front traveling motor, a 14c, a left rear traveling motor, a 14d, a left front traveling motor, a 15a, a first electromagnetic reversing valve, a 15b, a second electromagnetic reversing valve, a 16a, a first shunting and collecting valve, a 16b, a second shunting and collecting valve, a 16c, a third shunting and collecting valve, 17, a one-way valve, 18, an overflow valve, 19a, a seventh electromagnetic proportional reversing valve, 19b, an eighth electromagnetic proportional reversing valve, 20, a second hydraulic control reversing valve, 21, a shuttle valve, 22, a pressure reducing valve, 23 and a back pressure valve.

Detailed Description

As shown in fig. 1, an aerial work platform walking control system in the prior art comprises a closed pump 11, wherein the closed pump 11 is provided with an oil port a and an oil port B, and is characterized by further comprising a walking control valve assembly 12; the walking control valve assembly 12 comprises a first hydraulic control reversing valve 13, a first electromagnetic reversing valve 15a, a second electromagnetic reversing valve 15b, a first flow dividing and collecting valve 16a, a second flow dividing and collecting valve 16b and a third flow dividing and collecting valve 16 c; an oil port A of the closed pump 11 is respectively connected with a port B of the first hydraulic control reversing valve 13, a right hydraulic control port of the first hydraulic control reversing valve 13 and a port P of the third shunting and collecting valve 16c through pipelines, a port A of the third shunting and collecting valve 16c is respectively connected with a port A of the right rear walking motor 14a and a port A of the left rear walking motor 14c through pipelines, and a port B of the third shunting and collecting valve 16c is respectively connected with a port A of the right front walking motor 14B and a port A of the left front walking motor 14d through pipelines; an oil port B of the closed pump 11 is respectively connected with an A port of the first hydraulic control reversing valve 13, a left hydraulic control port of the first hydraulic control reversing valve 13, a P port of the first flow dividing and collecting valve 16a and a P port of the second flow dividing and collecting valve 16B through pipelines, the A port and the B port of the first flow dividing and collecting valve 16a are respectively connected with a B port of the right rear traveling motor 14a and a B port of the left rear traveling motor 14c through pipelines, and the A port and the B port of the second flow dividing and collecting valve 16B are respectively connected with a B port of the right front traveling motor 14B and a B port of the left front traveling motor 14d through pipelines; the right rear travel motor 14a, the left rear travel motor 14c, the right front travel motor 14b, and the left front travel motor 14d are each connected with a brake and a variable control cylinder; the oil drainage ports of the right rear traveling motor 14a, the left rear traveling motor 14c, the right front traveling motor 14b and the left front traveling motor 14d are all connected with an oil tank through pipelines; the P port of the first hydraulic control reversing valve 13 is connected with the A port of the first electromagnetic reversing valve 15a through a one-way valve and is also connected with the A port of the second electromagnetic reversing valve 15B through a pipeline, and the B port of the first electromagnetic reversing valve 15a is connected with the B port of the second electromagnetic reversing valve 15B and then is connected with the oil tank; the port P of the first electromagnetic directional valve 15a is connected with the brakes of the right rear traveling motor 14a, the left rear traveling motor 14c, the right front traveling motor 14b and the left front traveling motor 14d through pipes, respectively; the P port of the second electromagnetic directional valve 15b is connected to variable control cylinders of the right rear traveling motor 14a, the left rear traveling motor 14c, the right front traveling motor 14b, and the left front traveling motor 14d, respectively, through pipes. The check valve 17 is connected to the tank via an overflow valve 18. The first hydraulic control reversing valve 13 is a two-position three-way reversing valve, which is provided with an A port, a B port and a P port, when the first hydraulic control reversing valve works at a left position, the A port is cut off, an oil path between the B port and the P port is communicated, when the first hydraulic control reversing valve works at a middle position, the P port, the A port and the B port are all cut off, when the first hydraulic control reversing valve works at a right position, the B port is cut off, and the oil path between the A port and the P port is communicated. The first electromagnetic directional valve 15a and the second electromagnetic directional valve 15B have the same structure and are provided with an opening a, an opening B and an opening P, when the left position is electrified, the oil path between the opening a and the opening P is communicated, the opening B is closed, the cross section of the passage between the opening a and the opening P is gradually increased along with the increase of current, the cross section of the passage between the opening a and the opening P is gradually decreased along with the decrease of current, and when the power is lost, the oil path between the opening B and the opening T is communicated and the opening a is closed.

The working principle of fig. 1 is as follows: when the electric vehicle runs forwards, the rotary operating handle is operated to move forwards (the inclination angle of the handle represents the speed requirement), after the inclination angle of the handle passes through the dead zone, the controller proportionally outputs current to the electromagnetic proportional solenoid valve YP11a arranged in the closed pump 11, the A port of the closed pump 11 proportionally outputs flow, and the left position Y11 of the first electromagnetic directional valve 15a is electrified and operated on the left position in a reversing mode. The high-pressure oil output from the port A of the closed pump 11 enters the port B of the first hydraulic control reversing valve 13 in the walking control valve 12 and the right hydraulic control port of the first hydraulic control reversing valve to enable the first hydraulic control reversing valve 13 to work at the right position in a reversing mode, the high-pressure oil output from the port A of the closed pump 11 also enters the port P of the third shunting and collecting valve 16c at the same time, because the first electromagnetic reversing valve 15a works at the left position in a reversing mode, the oil entering from the port B of the first hydraulic control reversing valve 13 flows out through the port P and enters the port A of the first electromagnetic reversing valve 15a through the check valve 17, and because the first electromagnetic reversing valve 15a works at the left position in a reversing mode, the oil entering from the port A flows out from the port P and is respectively supplied to the brakes of the motors, and the brakes are opened to have a walking state. Meanwhile, the high-pressure oil output from the port a of the third flow dividing and collecting valve 16c enters the ports a of the right rear traveling motor 14a and the left rear traveling motor 14c, the high-pressure oil output from the port B of the third flow dividing and collecting valve 16c enters the ports a of the right front traveling motor 14B and the left front traveling motor 14d, and the oil discharged from the ports B of the right rear traveling motor 14a and the left rear traveling motor 14c enters the first flow dividing and collecting valve 16a at almost the same flow rate and then returns to the low-pressure side of the closed pump through the port P entering the first flow dividing and collecting valve 16 a; similarly, the oil discharged from the ports B of the right front traveling motor 14B and the left front traveling motor 14d enters the second flow dividing and collecting valve 16B at almost the same flow rate, and then returns to the low-pressure side of the closed pump 11 through the port P of the second flow dividing and collecting valve 16B.

When the vehicle runs backwards, the rotary operating handle is operated to carry out the backward movement, after the inclination angle of the handle passes through the dead zone, the controller outputs current in proportion to the electromagnetic proportional electromagnetic valve YP11b arranged in the closed pump 11, the closed pump 11 outputs flow in proportion, and the left position Y11 of the first electromagnetic directional valve 15a is electrified and operated in a reversing mode to be in the left position. The high-pressure oil output from the port B of the closed pump 11 enters the port a of the first pilot-controlled directional control valve 13 and the port-left pilot-controlled port of the first pilot-controlled directional control valve in the traveling control valve 12, so that the first pilot-controlled directional control valve 13 operates in a left-position in a reversing manner, the high-pressure oil output from the port B of the closed pump 11 also enters the port P of the first flow-dividing/collecting valve 16a and the port P of the second flow-dividing/collecting valve 16B simultaneously, because the first electromagnetic directional control valve 15a operates in a left-position in a reversing manner, the high-pressure oil entering from the port a of the first pilot-controlled directional control valve 13 flows out from the port P thereof, then enters the port a of the first electromagnetic directional control valve 15a through the check valve 17, and then flows out from the port P of the first electromagnetic directional control valve 15a and enters the brakes of the motors. Meanwhile, the high-pressure oil entering from the port P of the first flow dividing and collecting valve 16a is output from the port a and the port B thereof and supplied to the port B of the right rear traveling motor 14a and the port B of the left rear traveling motor 14c, the high-pressure oil entering from the port P of the second flow dividing and collecting valve 16B is output from the port a and the port B thereof and supplied to the port B of the right front traveling motor 14B and the port B of the left front traveling motor 14d, respectively, the driving motor moves backward, and the oil discharged from the ports a of the right rear traveling motor 14a, the left rear traveling motor 14c, the right front traveling motor 14B, and the left front traveling motor 14d flows back to the low-pressure side of the closed pump 11 through the third flow dividing and collecting valve 16 c. The sum of the oil discharged from the right rear traveling motor 14a and the left rear traveling motor 14c is almost the same as the sum of the flow rates discharged from the right front traveling motor 14b and the left front traveling motor 14d, enters a flow dividing and combining valve (16 c in the sequence of fig. 1), and then returns to the low-pressure side of the closed pump.

The arrangement of the flow distributing and collecting valve ensures that the flow passing through each motor is almost equal, so that the aerial work platform can walk according to a straight line. When the fast walking is needed, the fast mode is switched, the left position Y12 of the second electromagnetic directional valve 15b is electrified, the pressure oil enters the variable control oil cylinders of the motors, so that the variable control oil cylinders of the motors move, the motors move at small displacement, and the walking speed is increased.

By qualitatively analyzing fig. 1, when the vehicle turns during driving, it can be obtained that:

v1=ωR；v2=ω(R+L)；

in the formula

v 1: inner wheel speed, v 2: outside wheel speed, ω: turning angular velocity of vehicle, R: turning radius L of vehicle: the width of the axle;

for each wheel can be obtained

v1=ω1r；v2=ω2r；

In the formula

ω 1: angular velocity of the inner wheel, ω 2: angular velocity of the outer wheel, r: the effective radius of the wheel;

for each wheel can also be obtained

ω1=2πQ1/ qm；ω2=2πQ2/ qm；

In the formula

Q1: hydraulic flow of the inner wheel, Q2: hydraulic flow of the outer wheel, qm: displacement of the hydraulic motor;

the flow difference between the two wheels in steering can be found as follows:

△Q=Q1-Q2=ωLqm/2πr

since the turning angular velocity is a variable, the flow rate difference Δ Q of the drive motor is related to the change in the turning angular velocity ω. And the turning angular velocity ω is limited to the running speed V and the turning radius R of the vehicle. Thus, when the vehicle is traveling at different speeds and turning radii, different flow rates between the wheels may be required. The main function of the flow distributing and collecting valve is to make the flow rates of the inlet and the outlet of the flow distributing and collecting valve the same, so that the design is difficult to meet the control requirement when the vehicle turns to walk; in practical use, the error of the flow dividing and collecting valve is often used for realizing control during steering, but the error of the flow dividing and collecting valve is limited after all. When the aerial work platform works, the steering is a common working condition, so that the performance of the walking system is greatly required to be improved.

The present invention will be further explained with reference to fig. 2.

As shown in fig. 2, the present application provides a walking control system for an aerial work platform, which comprises a closed pump 11, a rotary operating handle, a controller and a walking control valve assembly 12; the closed pump 11 has an oil port a and an oil port B;

the walking control valve assembly 12 comprises a third electromagnetic proportional directional valve 13a, a fourth electromagnetic proportional directional valve 13b, a fifth electromagnetic proportional directional valve 13c, a sixth electromagnetic proportional directional valve 13d, a first electromagnetic directional valve 15a, a second electromagnetic directional valve 15b, a seventh electromagnetic proportional directional valve 19a, an eighth electromagnetic proportional directional valve 19b, a first electromagnetic directional valve 15a, a second electromagnetic directional valve 15b, a second hydraulic directional valve 20, a shuttle valve 21, a pressure reducing valve 22 and a back pressure valve 23; the swing control valve assembly 12 may be integrally provided as needed, or may be divided into several portions as needed, and is preferably integrally provided.

An oil port A of the closed pump 11 is respectively connected with a port B of the shuttle valve 21, a port A of the third electromagnetic proportional directional valve 13a, a port A of the fourth electromagnetic proportional directional valve 13B, a port A of the fifth electromagnetic proportional directional valve 13c and a port A of the sixth electromagnetic proportional directional valve 13d through pipelines;

an oil port B of the closed pump 11 is respectively connected with a port A of the shuttle valve 21, a port P of the seventh electromagnetic proportional directional valve 19a and a port P of the eighth electromagnetic proportional directional valve 19B through pipelines;

a port B of the third electromagnetic proportional reversing valve 13a and a port B of the fifth electromagnetic proportional reversing valve 13c are respectively connected with a port A of the right rear traveling motor 14a and a port A of the left rear traveling motor 14c through pipelines, and a port B of the fourth electromagnetic proportional reversing valve 13B and a port B of the sixth electromagnetic proportional reversing valve 13d are respectively connected with a port A of the right front traveling motor 14B and a port A of the left front traveling motor 14d through pipelines;

the port A and the port B of the seventh electromagnetic proportional reversing valve 19a are respectively connected with the port B of the right rear traveling motor 14a and the port B of the left rear traveling motor 14c through pipelines, and the port A and the port B of the eighth electromagnetic proportional reversing valve 19B are respectively connected with the port B of the right front traveling motor 14B and the port B of the left front traveling motor 14d through pipelines;

the right rear travel motor 14a, the left rear travel motor 14c, the right front travel motor 14b, and the left front travel motor 14d are each connected with a brake and a variable control cylinder; the oil drainage ports of the right rear traveling motor 14a, the left rear traveling motor 14c, the right front traveling motor 14b and the left front traveling motor 14d are all connected with an oil tank through pipelines; the oil paths of the ports A of the right rear traveling motor 14a, the left rear traveling motor 14C, the right front traveling motor 14B and the left front traveling motor 14D are respectively provided with a flowmeter A, a flowmeter C, a flowmeter B and a flowmeter D;

the C port of the shuttle valve 21 is connected with the A port of the second hydraulic control reversing valve 20 and the left hydraulic control port of the second hydraulic control reversing valve 20 through a pressure reducing valve 22, and the B port of the second hydraulic control reversing valve 20 is connected with the oil tank through a back pressure valve 23 after being communicated with the right spring cavity of the second hydraulic control reversing valve so as to ensure certain back pressure; a port P of the second hydraulic control reversing valve 20 is connected with a port A of the first electromagnetic reversing valve 15a through a one-way valve 17 and is also connected with a port A of the second electromagnetic reversing valve 15B through a pipeline, and a port B of the first electromagnetic reversing valve 15a is communicated with a port B of the second electromagnetic reversing valve 15B and then is connected with an oil tank through a throttle; the port P of the first electromagnetic directional valve 15a is connected with the brakes of the right rear traveling motor 14a, the left rear traveling motor 14c, the right front traveling motor 14b and the left front traveling motor 14d through pipes, respectively; the P port of the second electromagnetic directional valve 15b is connected to variable control cylinders of the right rear traveling motor 14a, the left rear traveling motor 14c, the right front traveling motor 14b, and the left front traveling motor 14d, respectively, through pipes.

The controller is respectively connected with the closed pump 11, the rotary operating handle, the third electromagnetic proportional reversing valve 13a, the fourth electromagnetic proportional reversing valve 13B, the fifth electromagnetic proportional reversing valve 13C, the sixth electromagnetic proportional reversing valve 13D, the seventh electromagnetic proportional reversing valve 19a, the eighth electromagnetic proportional reversing valve 19B, the flowmeter A, the flowmeter C, the flowmeter B and the flowmeter D.

In order to ensure that the operating pressure of the system is within a set range, the non-return valve 17 is connected to the tank via a relief valve 18.

In order to realize the stepless adjustment control of the whole vehicle, the closed pump 11 is a proportional variable plunger pump.

Preferably, the second hydraulic directional control valve 20 is a two-position three-way directional control valve having ports a, B, and P, and when the valve is operated at the left position, the port B is closed, and the oil passage between the ports a and P is communicated, and when the valve is operated at the right position, the port a is closed, and the oil passage between the port B and the port P is communicated.

Preferably, the first electromagnetic directional valve 15a and the second electromagnetic directional valve 15B have the same configuration, and each of the first electromagnetic directional valve 15a and the second electromagnetic directional valve 15B has ports a, B, and P, and when left-hand position is energized, the oil passage between the ports a and P is communicated, and the port B is closed, and when no power is applied, the oil passage between the ports B and T is communicated, and the port a is closed.

Preferably, the seventh electromagnetic proportional directional valve 19a and the eighth electromagnetic proportional directional valve 19B have the same structure, and are each a three-position three-way proportional directional valve, which has ports a, B, and P, and when the valve is operated at the upper position, the port B is blocked, the oil passage between the ports a and P is communicated, when the valve is operated at the middle position, the port P is simultaneously communicated with the ports a and B, and when the valve is operated at the lower position, the port a is blocked, and the oil passage between the port B and the port P is communicated.

Preferably, the third electromagnetic proportional directional valve 13a, the fourth electromagnetic proportional directional valve 13B, the fifth electromagnetic proportional directional valve 13c, and the sixth electromagnetic proportional directional valve 13d have the same structure, and are all two-position two-way proportional electromagnetic directional valves, each of which has ports a and B, and when the valve operates in the left position, the ports a and B are both blocked, and when the valve operates in the right position, the oil passages between the ports a and B are communicated.

Preferably, the controller is of the type SIMATIC S7-200.

The utility model discloses the theory of operation as follows:

1.1 Walking movement

When the electric vehicle runs forwards, the rotary operating handle is operated to move forwards (the inclination angle of the handle represents the speed requirement), after the inclination angle of the handle passes through the dead zone, the controller proportionally outputs current to the left YP21a of the electromagnetic proportional solenoid valve arranged in the closed pump 11, the closed pump 11 proportionally outputs flow, and controls the Y21 of the first electromagnetic directional valve 15a to be electrified and operated on the left in a reversing mode. High-pressure oil output from the port a of the closed pump 11 enters a port B of a shuttle valve 21, a port a of a third electromagnetic proportional directional valve 13a, a port a of a fourth electromagnetic proportional directional valve 13B, a port a of a fifth electromagnetic proportional directional valve 13c and a port a of a sixth electromagnetic proportional directional valve 13d in the travel control valve 12, wherein the oil output from the shuttle valve 21 passes through a pressure reducing valve 22 and then enters a port a of a second hydraulic directional valve 20 and a left hydraulic control port of the second hydraulic directional valve 20, so that the second hydraulic directional valve 20 works in a left position in a reversing manner, and since the first electromagnetic directional valve 15a works in the left position when being electrified, the decompressed oil enters brakes of the travel motors through a passage between the port a and the port P of the first electromagnetic directional valve 15a, so that the brakes are opened to have a travel state. Meanwhile, the controller respectively controls the right positions of the third electromagnetic proportional directional valve 13a, the fourth electromagnetic proportional directional valve 13B, the fifth electromagnetic proportional directional valve 13c and the sixth electromagnetic proportional directional valve 13d to be electrified so as to enable the valves to work on the right positions, and the seventh electromagnetic proportional directional valve 19a is not electrified so as to work on the middle position, so that high-pressure oil output from the port A of the closed pump 11 also respectively passes through the passages between the ports A and B of the third electromagnetic proportional directional valve 13a, the fourth electromagnetic proportional directional valve 13B, the fifth electromagnetic proportional directional valve 13c and the sixth electromagnetic proportional directional valve 13d to be divided into four passages and respectively enters the ports A of the right rear walking motor 14a, the right front walking motor 14B, the left rear walking motor 14c and the left front walking motor 14 d; the oil discharged from the ports B of the right rear traveling motor 14a and the left rear traveling motor 14c flows back to the low-pressure side of the closed pump through a passage between the ports a and P and a passage between the ports B and P of the seventh electromagnetic proportional directional valve 19a, respectively; similarly, the oil discharged from the ports B of the right front traveling motor 14B and the left front traveling motor 14d flows back to the low-pressure side of the closed pump through the passage between the ports a and P and the passage between the ports B and P of the eighth electromagnetic proportional switching valve 19B.

The control method during forward motion comprises the following steps: 1) under the walking working condition of a non-steering state, the current obtained by the third electromagnetic proportional directional valve 13a, the fourth electromagnetic proportional directional valve 13b, the fifth electromagnetic proportional directional valve 13c and the sixth electromagnetic proportional directional valve 13d is controlled to be the same, so that the openings in the valves are the same, and the phenomenon that the flow rates of left and right motors are different can occur due to the fact that the loads of the motors are not completely the same, the flow meters connected to the A ports of the walking motors can respectively measure the flow rates of the corresponding motors, the flow rates are fed back to the controller in real time, the controller adjusts the openings of the seventh electromagnetic proportional directional valve 19a and the eighth electromagnetic proportional directional valve 19b in real time according to the fed-back flow rates, and further controls the pressure difference of the inlet and the outlet of the motors by controlling the pressure of the outlets of the motors, so that the flow rates of the motors are flexibly controlled, and the. 2) Under the walking working condition in the steering state, the opening sizes of the corresponding third electromagnetic proportional directional valve 13a, fourth electromagnetic proportional directional valve 13b, fifth electromagnetic proportional directional valve 13c and sixth electromagnetic proportional directional valve 13d are controlled according to the flow demand of the left and right motors, and because the loads of the motors are not identical, the phenomenon that the left and right motor flows cannot meet the left and right demands can occur, the openings of the seventh electromagnetic proportional directional valve 19a and the eighth electromagnetic proportional directional valve 19b are adjusted in real time according to the signals fed back by the corresponding flow meters, so that the pressure difference of the inlet and the outlet of the motors is controlled by controlling the pressure of the outlet of the motors, and the flow of the motors is controlled.

When the vehicle runs backwards, the rotary operating handle is operated to carry out the backward movement, after the inclination angle of the handle passes through the dead zone, the controller proportionally outputs current to the electromagnetic proportional solenoid valve YP21b arranged in the closed pump 11, the closed pump 11 proportionally outputs flow, and controls the Y21 of the first electromagnetic directional valve 15a to be electrified and operated on the left position in a reversing way. High-pressure oil output from the port B of the closed pump 11 enters the port A of the shuttle valve 21 in the traveling control valve 12, the port P of the seventh electromagnetic proportional directional valve 19a and the port P of the eighth electromagnetic proportional directional valve 19B, wherein the oil output from the shuttle valve 21 passes through the pressure reducing valve 22 and then enters the port A of the second hydraulic directional valve 20 and the left hydraulic control port of the second hydraulic directional valve 20, so that the second hydraulic directional valve 20 works in a left position in a reversing manner, and since Y21 of the first electromagnetic directional valve 15a works in a left position in a reversing manner at this time, the decompressed oil enters the brakes of the traveling motors through the passages between the port A and the port P of the first electromagnetic directional valve 15a, so that the brakes are opened to achieve a traveling state. Meanwhile, the controller respectively controls the right position of the third electromagnetic proportional directional valve 13a, the fourth electromagnetic proportional directional valve 13b, the fifth electromagnetic proportional directional valve 13c and the sixth electromagnetic proportional directional valve 13d to be electrified, so that the valves all work at the right position. High-pressure oil output by a port B of the closed pump 11 is divided into two paths through a port P of a seventh electromagnetic proportional directional valve 19a, passes through a port P of an eighth electromagnetic proportional directional valve 19B, and respectively enters ports B of a right rear traveling motor 14a, a left rear traveling motor 14c, a right front traveling motor 14B and a left front traveling motor 14 d; oil liquid discharged from the ports a of the right rear traveling motor 14a and the left rear traveling motor 14c respectively passes through a passage between the ports B and a of the third electromagnetic proportional directional valve 13a and a passage between the ports B and a of the fifth electromagnetic proportional directional valve 13c, and then returns to the low-pressure side of the closed pump 11; similarly, the oil discharged from the ports a of the right and left front traveling motors 14B and 14d passes through the passage between the ports B and a of the four electromagnetic proportional directional valves 13B and the passage between the ports B and a of the sixth electromagnetic proportional directional valve 13d, and then returns to the low-pressure side of the closed pump 11.

The control method during the backing-off comprises the following steps: 1) under the walking working condition of a non-steering state, the openings of the seventh electromagnetic proportional directional valve 19a and the eighth electromagnetic proportional directional valve 19b are controlled to be the same, because the loads of the motors are not completely the same, the phenomenon that the flow rates of the left motor and the right motor are different can occur, the flow meters connected to the A ports of the walking motors can respectively measure the flow rates of the corresponding motors and feed the flow rates back to the controller in real time, the controller adjusts the openings of the seventh electromagnetic proportional directional valve 19a and the eighth electromagnetic proportional directional valve 19b in real time according to the fed-back flow rates, and then the pressure difference of the inlet and the outlet of the motors is controlled by controlling the pressure of the outlet of the motors, so that the flow rates of the motors are flexibly controlled, and the requirements of. 2) Under the running working condition of a steering state, the sizes of the openings of the corresponding seventh electromagnetic proportional directional valve 19a and the eighth electromagnetic proportional directional valve 19b are controlled according to the flow demands of the left motor and the right motor, and because the loads of the motors are not completely the same, the phenomenon that the flow of the left motor and the right motor cannot meet the left-right demands can also occur, the openings of the third electromagnetic proportional directional valve 13a, the fourth electromagnetic proportional directional valve 13b, the fifth electromagnetic proportional directional valve 13c and the sixth electromagnetic proportional directional valve 13d are adjusted in real time according to signals fed back by the corresponding flow meters, and the pressure difference of the inlet and the outlet of the motors is controlled by controlling the pressure of the outlet of the motors, so that the flow of the motors is controlled.

Claims (8)

1. A walking control system of an aerial work platform comprises a closed pump (11), a rotary operating handle and a controller, wherein the closed pump (11) is provided with an oil port A and an oil port B, and is characterized by further comprising a walking control valve assembly (12);

the walking control valve assembly (12) comprises a third electromagnetic proportional directional valve (13 a), a fourth electromagnetic proportional directional valve (13 b), a fifth electromagnetic proportional directional valve (13 c), a sixth electromagnetic proportional directional valve (13 d), a first electromagnetic directional valve (15 a), a second electromagnetic directional valve (15 b), a seventh electromagnetic proportional directional valve (19 a), an eighth electromagnetic proportional directional valve (19 b), a first electromagnetic directional valve (15 a), a second electromagnetic directional valve (15 b), a second hydraulic directional valve (20), a shuttle valve (21), a pressure reducing valve (22) and a back pressure valve (23);

an oil port A of the closed pump (11) is respectively connected with a port B of the shuttle valve (21), a port A of the third electromagnetic proportional directional valve (13 a), a port A of the fourth electromagnetic proportional directional valve (13B), a port A of the fifth electromagnetic proportional directional valve (13 c) and a port A of the sixth electromagnetic proportional directional valve (13 d) through pipelines;

an oil port B of the closed pump (11) is respectively connected with an A port of the shuttle valve (21), a P port of the seventh electromagnetic proportional directional valve (19 a) and a P port of the eighth electromagnetic proportional directional valve (19B) through pipelines;

a port B of a third electromagnetic proportional directional valve (13 a) and a port B of a fifth electromagnetic proportional directional valve (13 c) are respectively connected with a port A of a right rear walking motor (14 a) and a port A of a left rear walking motor (14 c) through pipelines, and a port B of a fourth electromagnetic proportional directional valve (13B) and a port B of a sixth electromagnetic proportional directional valve (13 d) are respectively connected with a port A of a right front walking motor (14B) and a port A of a left front walking motor (14 d) through pipelines;

the port A and the port B of the seventh electromagnetic proportional directional valve (19 a) are respectively connected with the port B of the right rear traveling motor (14 a) and the port B of the left rear traveling motor (14 c) through pipelines, and the port A and the port B of the eighth electromagnetic proportional directional valve (19B) are respectively connected with the port B of the right front traveling motor (14B) and the port B of the left front traveling motor (14 d) through pipelines;

the right rear walking motor (14 a), the left rear walking motor (14 c), the right front walking motor (14 b) and the left front walking motor (14 d) are respectively connected with a brake and a variable control oil cylinder; oil drainage ports of the right rear traveling motor (14 a), the left rear traveling motor (14 c), the right front traveling motor (14 b) and the left front traveling motor (14 d) are connected with an oil tank through pipelines; the oil paths of the ports A of the right rear traveling motor (14 a), the left rear traveling motor (14C), the right front traveling motor (14B) and the left front traveling motor (14D) are respectively provided with a flow meter A, a flow meter C, a flow meter B and a flow meter D;

a port C of the shuttle valve (21) is connected with a port A of the second hydraulic control reversing valve (20) and a left hydraulic control port of the second hydraulic control reversing valve (20) through a reducing valve (22), and a port B of the second hydraulic control reversing valve (20) is communicated with a right spring cavity of the second hydraulic control reversing valve and then is connected with an oil tank through a back pressure valve (23); a port P of the second hydraulic control reversing valve (20) is connected with a port A of the first electromagnetic reversing valve (15 a) through a one-way valve (17) and is also connected with a port A of the second electromagnetic reversing valve (15B) through a pipeline, and a port B of the first electromagnetic reversing valve (15 a) is communicated with a port B of the second electromagnetic reversing valve (15B) and then is connected with an oil tank through a throttle; the P port of the first electromagnetic directional valve (15 a) is respectively connected with brakes of a right rear walking motor (14 a), a left rear walking motor (14 c), a right front walking motor (14 b) and a left front walking motor (14 d) through pipelines; a P port of the second electromagnetic directional valve (15 b) is respectively connected with variable control oil cylinders of a right rear walking motor (14 a), a left rear walking motor (14 c), a right front walking motor (14 b) and a left front walking motor (14 d) through pipelines;

the controller is respectively connected with the closed pump (11), the rotary operating handle, the third electromagnetic proportional reversing valve (13 a), the fourth electromagnetic proportional reversing valve (13B), the fifth electromagnetic proportional reversing valve (13C), the sixth electromagnetic proportional reversing valve (13D), the seventh electromagnetic proportional reversing valve (19 a), the eighth electromagnetic proportional reversing valve (19B), the flowmeter A, the flowmeter C, the flowmeter B and the flowmeter D.

2. The aerial work platform walking control system of claim 1, wherein the one-way valve (17) is connected with the oil tank through an overflow valve (18).

3. An aerial work platform walking control system as claimed in claim 1 or 2 wherein the closed pump (11) is a proportional variable plunger pump.

4. The overhead working platform walking control system according to claim 3, wherein the second hydraulic control directional control valve (20) is a two-position three-way directional control valve, which has an A port, a B port and a P port, when the second hydraulic control directional control valve works in the left position, the B port is blocked, the oil path between the A port and the P port is communicated, when the second hydraulic control directional control valve works in the right position, the A port is blocked, and the oil path between the B port and the P port is communicated.

5. The aerial work platform walking control system of claim 4, wherein the first electromagnetic directional valve (15 a) and the second electromagnetic directional valve (15B) are identical in structure and are provided with an A port, a B port and a P port, when the left position is electrified, an oil path between the A port and the P port is communicated, the B port is closed, when the power is off, an oil path between the B port and the T port is communicated, and the A port is closed.

6. The walking control system of the aerial work platform according to claim 5, wherein the seventh electromagnetic proportional directional valve (19 a) and the eighth electromagnetic proportional directional valve (19B) are of the same structure, and are both three-position three-way proportional directional valves, which have ports A, B and P, wherein when the valves are operated at the upper position, the port B is closed, the oil path between the port A and the port P is communicated, when the valves are operated at the middle position, the port P is simultaneously communicated with the port A and the port B, and when the valves are operated at the lower position, the port A is closed, and the oil path between the port B and the port P is communicated.

7. The overhead working platform walking control system according to claim 6, wherein the third electromagnetic proportional directional valve (13 a), the fourth electromagnetic proportional directional valve (13B), the fifth electromagnetic proportional directional valve (13 c) and the sixth electromagnetic proportional directional valve (13 d) are identical in structure, are two-position two-way proportional electromagnetic directional valves, and are provided with ports A and B, when the valves operate in the left position, the ports A and B are both blocked, and when the valves operate in the right position, oil passages between the ports A and B are communicated.

8. The aerial work platform travel control system of claim 7 wherein the controller is of the type SIMATIC S7-200.

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