WO2020006932A1

WO2020006932A1 - Bucket leveling system for aerial work truck

Info

Publication number: WO2020006932A1
Application number: PCT/CN2018/111594
Authority: WO
Inventors: 董洪月; 耿艳杰; 胡景清; 陈时妹; 朱赛
Original assignee: 徐州海伦哲专用车辆股份有限公司
Priority date: 2018-07-03
Filing date: 2018-10-24
Publication date: 2020-01-09
Also published as: GB202011541D0; CN108658019A; GB2587267B; CN108658019B; GB2587267A

Abstract

A bucket leveling system for an aerial work truck, a main valve (28) being able to be a cartridge valve or a multi-way valve; the maximum load pressures on a telescopic cylinder (34) and a luffing cylinder (33) are both fed back to a load-sensing port LS of a constant-pressure differential variable pump (23); a reversing valve is provided on a liquid passage which connects a pressure port P of the main valve (28) and a pressure port P of a leveling valve (29), and when the reversing valve is in a spring position, the pressure of the pressure port P of the leveling valve (29) is zero, and when the reversing valve is reversed, the pressure port P of the constant-pressure differential variable pump (23) is in communication, by means of a speed regulating valve (281), with the port P of the leveling valve (29), and the pressure of the port P of the leveling valve (29) is fed back, by means of a one-way valve connected at the port of the reversing valve, to the load-sensing port LS of the constant-pressure differential variable pump (23). The bucket leveling system is easy to control, there is no lag in leveling action, and the system responds quickly; the entire system is a load-sensing system, saving energy consumption.

Description

Working bucket leveling system of high-altitude operation vehicle

Technical field

The invention relates to an engineering vehicle leveling system, in particular to a working bucket leveling system of an aerial work vehicle, and belongs to the technical field of hydraulic control of engineering machinery.

Background technique

High-altitude operation vehicle is a kind of equipment that transports workers and equipment to a specified height for operation. It belongs to special operation equipment. Its structure is shown in Figure 1. It includes chassis 1, turntable 2, luffing cylinder 3, telescopic cylinder 4, basic The arm 5, the two-joint arm 6, the leveling cylinder 7 and the working bucket 8, the luffing cylinder 3 drives the luffing of the boom, the telescoping cylinder 4 drives the expansion and contraction of the boom, and the leveling cylinder 7 is used to adjust the angle of the working bucket 8.

When working at height, the working bucket 8 is required to be always parallel to the horizontal plane to ensure the safety and comfort of the operator. Therefore, leveling performance is an important indicator for measuring vehicles. The working principle of the working bucket 8 leveling is shown in FIG. 2. When the boom is changed, the bottom surface of the working bucket 8 will no longer remain horizontal. At this time, the inclination sensor 9 collects the inclination signal of the working bucket 8 and after the controller 10 processes it, it drives the spool of the electro-hydraulic proportional valve 11 to make corresponding actions. The cylinder rod of the leveling cylinder 7 is extended or retracted, thereby directly driving the work bucket 8 up or down to achieve the level of the work bucket 8.

There are usually two ways of leveling oil supply for the working bucket 8: ① Gear pump (quantitative pump) supplies oil for leveling separately; ② The leveling action of the working bucket 8 shares a plunger pump (variable pump) with the boom telescopic and luffing action ). Among them, the second leveling oil supply method is widely used because it does not need to be equipped with a gear pump for leveling separate oil supply, and has the advantages of low cost and easy layout.

In the second method of leveling oil supply, the oil pump is usually located on the lower chassis, and the pipeline between the oil pump and the bucket 8 is relatively long. The working bucket 8 leveling flow is small. If a conventional load-sensitive system is used for the working bucket 8 leveling, the system response is slow and the leveling lag is serious. Therefore, most of the working bucket 8 leveling systems use a constant pressure system, that is, as long as the amplitude is changed. The system is a constant voltage system when in action.

The working bucket 8 leveling system in the prior art mainly includes a constant pressure differential variable pump, a main valve, a leveling valve, a telescopic oil cylinder 4, a luffing oil cylinder 3, and a leveling oil cylinder 7. The constant pressure differential variable pump controls the operation of the telescopic cylinder 4 and the luffing cylinder 3 through the main valve, and at the same time, supplies oil to the leveling cylinder 7. When stand-alone telescopic action, the system is a load-sensitive system. The outlet pressure of the constant pressure differential variable pump is higher than the load pressure by a preset fixed value, and the outlet flow rate is the load working flow. When the single variable amplitude action is used, the constant pressure differential variable pump is used. As a constant pressure variable pump, the system is a constant pressure system. The leveling flow is changed by changing the opening of the electromagnetic proportional valve in the leveling valve; when the telescopic and variable amplitude are combined, the constant pressure differential variable pump is used as a constant pressure. Variable pump. The system is a constant pressure system. The leveling flow is changed by changing the size of the electromagnetic proportional valve opening in the leveling valve.

The above-mentioned leveling system has the following technical defects: 1) When the single amplitude-change operation or the telescoping and amplitude-change composite operations are used, the system is a constant pressure system, so the outlet pressure of the constant pressure differential variable pump 13 has been maintained at the maximum value, and Compared with load-sensitive systems, the energy consumption is large; 2) The leveling action of the bucket will cause slow system response and lagging; 3) The pressure difference between the two ends of the electromagnetic proportional valve in the leveling valve changes with the load change. Therefore, the leveling of the bucket 8 is not easy to control.

Summary of the invention

In order to overcome the above-mentioned shortcomings of the prior art, the present invention provides a working bucket leveling system for an aerial work vehicle. The working bucket leveling is easy to control, the lagging action has no lag, the system responds quickly, and at the same time saves energy and reduces consumption.

In order to solve the above problems, the present invention provides a bucket leveling system for an aerial work vehicle, which includes a constant pressure variable pump, a main valve, a leveling valve, a telescopic oil cylinder, a luffing cylinder, and a leveling oil cylinder; the pressure of the constant pressure variable pump Port P is connected to the main valve pressure port P. The constant pressure differential variable pump load feedback port LS is connected to the main valve load feedback port LS. The hydraulic oil enters the telescopic cylinder and the luffing cylinder through the main valve to control the telescopic movement and variable The pressure port P of the main valve is connected to the pressure port P of the leveling valve. The return port T of the main valve is connected to the return port T of the leveling valve. The hydraulic oil enters the leveling cylinder through the leveling valve. Controls the leveling action of the leveling cylinder; it is characterized in that the main valve can be a cartridge valve or a multi-way valve; the maximum load pressure on the telescopic cylinder and the luffing cylinder is fed back to the load-sensitive oil of the constant pressure differential variable pump Port LS; the main valve pressure port P and the leveling valve pressure port P is provided with a directional valve on the oil line, when the directional valve is in the spring position, the pressure of the pressure port P of the leveling valve is zero, When the reversing valve is reversed, the constant pressure differential variable pump pressure port P passes The flow rate adjusting device is in communication with the P port of the leveling valve, and is fed back to the load-sensitive oil port LS of the constant pressure differential variable pump through a check valve connected to the oil outlet of the reversing valve.

Because the maximum load pressure on the telescopic cylinder and the luffing cylinder is fed back to the load-sensitive port LS of the constant pressure differential variable pump, and the pressure port P of the leveling valve is also fed back to the load of the constant pressure differential variable pump through the check valve. Sensitive oil port LS, so whether it is telescopic action, luffing action, or luffing telescoping action, the system is load-sensitive system, energy saving and environmental protection; when the telescopic action is alone, the directional valve is in the spring position, so there is no pressure oil When entering the leveling valve and the leveling cylinder, the directional valve is in the reversing direction when the luffing action is combined or the telescoping and luffing action is combined. Therefore, the pressure oil enters the leveling cylinder through the flow rate adjustment device and the reversing valve while entering the main valve. , Leveling action quickly without lag.

Further, the leveling valve includes a first shuttle valve, a three-position four-way electromagnetic proportional valve and a constant pressure differential valve, a port a, c port of the constant pressure differential valve, and oil inlet of the three-position four-way electromagnetic proportional valve. The port is connected in parallel to the pressure port P of the leveling valve. The first oil outlet of the three-position four-way electromagnetic proportional valve and the first oil inlet of the first shuttle valve are connected in parallel to the rod cavity end of the leveling cylinder. The second oil outlet of the four-way electromagnetic proportional valve and the second oil inlet of the first shuttle valve are connected in parallel to the rodless cavity end of the leveling cylinder. The oil outlet of the first shuttle valve feeds back pressure to the constant pressure differential valve. The d port, the return port of the three-position four-way electromagnetic proportional valve and the b port of the constant pressure differential valve are connected in parallel to the return circuit T of the system.

The first shuttle valve feedbacks the larger pressure at both ends of the leveling cylinder as a feedback pressure to the constant pressure differential valve, so that the pressure difference between the oil inlet and the oil return of the three-position four-way electromagnetic proportional valve is always kept constant. The flow rate of the four-way solenoid proportional valve is only related to the opening size of the three-way four-way solenoid proportional valve. Therefore, the leveling flow can be changed by changing the opening size of the first three-way four-way solenoid valve. Actions are more precise and faster.

Specifically, when the main valve is a cartridge valve, it includes an overflow valve, a proportional flow control valve, a three-position four-way electromagnetic directional valve, a shuttle valve, and a one-way valve. The oil inlet of the flow control valve and the oil inlet of the second proportional flow control valve are connected to the pressure oil port P of the main valve. The oil outlet of the first proportional flow control valve and the first three-position four-way electromagnetic directional valve The oil inlet of the second proportional flow control valve is connected to the oil inlet of the second three-position four-way electromagnetic directional valve, and the first oil outlet of the first three-position four-way electromagnetic directional valve is connected to The first oil inlet of the second shuttle valve is connected in parallel to the rod cavity end of the telescopic oil cylinder, and the second oil outlet of the first three-position four-way electromagnetic directional valve is connected in parallel with the second oil inlet of the second shuttle valve. The rod-less cavity end of the oil cylinder, the first oil outlet of the second three-position four-way electromagnetic directional valve and the first oil inlet of the third shuttle valve are connected in parallel at the rod cavity end of the luffing cylinder, and the second three-position four The second oil outlet of the electromagnetic switching valve and the second oil inlet of the third shuttle valve are connected in parallel at the rodless cavity end of the luffing cylinder. The oil outlet of the second shuttle valve and the second The oil inlet of the check valve is connected, and the oil outlet of the third shuttle valve is connected to the oil inlet of the third check valve. The oil outlets of the first, second and third check valves are all Connected to the load feedback port LS of the main valve, the return port of the first three-position four-way electromagnetic directional valve, the return port of the second three-position four-way electromagnetic directional valve, the return port of the directional valve and the overflow The outlet of the flow valve is connected to the return port T of the main valve.

The directional valve is a two-position three-way electromagnetic directional valve, and the flow rate adjusting device is a speed regulating valve.

Specifically, when the main valve is a multi-way valve, it includes a first coupling, a telescopic coupling, a luffing coupling, a leveling coupling, and a tail coupling, where the telescopic coupling, luffing coupling, and leveling coupling all include a constant pressure differential valve and a hydraulic control ratio. The inlets of the directional valve and check valve, the first hydraulic proportional valve, the second hydraulic proportional valve, and the third hydraulic proportional valve are connected to the pressure port P of the main valve. The oil return ports of one hydraulically controlled proportional directional valve, the second hydraulically controlled proportional directional valve, and the third hydraulically controlled proportional directional valve are connected to the oil return port T of the main valve; The control ports of the differential pressure valve and the third fixed differential pressure valve are connected to the load-sensitive port LS of the main valve; the left control port of the first hydraulic proportional valve is connected to the first electric proportional pressure reducing valve. The right control port of the first hydraulic proportional valve is connected to the second electric proportional pressure reducing valve, the left control port of the second hydraulic proportional valve is connected to the third electric proportional pressure reducing valve, and the second The right control port of the hydraulic proportional valve is connected to the fourth electric proportional pressure reducing valve, and the left control port of the third hydraulic proportional valve is connected to the fifth electric proportional pressure reducing valve. In addition, the right control oil port of the third hydraulic proportional proportional valve is directly connected to the fuel tank.

Further, the first hydraulically controlled proportional directional valve, the second hydraulically controlled proportional directional valve, and the third hydraulically controlled proportional directional valve are all three-position eight-way directional valves, and the a and c ports of the directional valve Connected and connected in parallel to the oil return port T, the b port is connected to the pressure port T, the d port and the h port of the first hydraulic proportional valve are connected to the rod end and the rodless end of the telescopic oil cylinder, respectively. The cavity ends are connected. The d port and the h port of the second hydraulic proportional proportional valve are respectively connected to the rod cavity end and the rodless cavity end of the luffing cylinder, and the d port and the third hydraulic controlled proportional valve are connected. The h port is connected to the pressure port P and the oil return port T of the main valve respectively. The e port and the g port of the first hydraulic proportional valve are connected in parallel to the oil outlet of the first constant pressure differential valve. The oil outlet of the first certain differential pressure valve is connected to the oil inlet of the fourth check valve, and the e and g ports of the second hydraulic proportional proportional valve are connected in parallel to the oil outlet of the second constant pressure differential valve. At the same time, the oil outlet of the second constant pressure differential valve is connected to the oil inlet of the fifth check valve, and the e and g ports of the third hydraulic proportional proportional valve are connected in parallel to the third constant pressure valve. At the oil outlet, the third constant pressure differential valve The oil outlet is connected to the oil inlet of the sixth check valve; the f port of the first hydraulic proportional valve is connected to the oil inlet of the first fixed differential pressure valve, and the f of the second hydraulic proportional valve is The oil port is connected to the oil inlet of the second fixed differential pressure valve, and the f port of the third hydraulic control proportional directional valve is connected to the oil inlet of the third fixed differential pressure valve.

The constant pressure differential variable pump in the present invention supplies oil to the bucket leveling operation at a constant flow through the main valve and the leveling valve. Because of the constant pressure differential valve provided at both ends of the three-position four-way electromagnetic proportional valve in the leveling valve, Therefore, it is possible to ensure that the pressure difference between the two ends of the three-position four-way electromagnetic proportional valve is constant. Its passing flow is only related to the opening of the three-position four-way electromagnetic proportional valve. Therefore, the leveling of the working bucket is convenient for control. During operation, no hydraulic oil flows into the leveling valve. When the luffing or telescoping compound action is performed, the hydraulic oil flows into the luffing cylinder and also flows into the leveling valve through the speed regulating valve. Therefore, the system of the bucket leveling action will not appear in the system. Slow response and leveling hysteresis; at the same time, the boom is a load-sensitive system when it is in separate telescopic action, single luffing action and telescoping luffing action, which saves energy and reduces consumption; at the same time, the main valve in this system is not limited to cartridge valves. It can also be applied to multi-way valves, so it can be used in a variety of operating conditions and has a wider range of applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of an aerial work vehicle;

2 is a schematic structural diagram of the working principle of the bucket leveling in FIG. 1;

3 is a schematic structural diagram of a bucket leveling system according to the present invention;

4 is a schematic structural diagram of another working bucket leveling system according to the present invention;

5 is an enlarged schematic diagram of the first hydraulically controlled proportional directional valve or the second hydraulically controlled proportional directional valve or the third hydraulically controlled proportional directional valve in FIG. 4;

In the picture: 1, chassis, 2, turntable, 3, luffing cylinder, 4, telescopic cylinder, 5, basic boom, 6, two-joint arm, 7, leveling cylinder, 8, bucket, 9, tilt sensor, 10 , Controller, 11, electro-hydraulic proportional valve, 12, leveling cylinder balance valve;

23. Constant pressure differential variable pump, 28, main valve, 281, speed regulating valve, 282, relief valve, 283, first proportional flow control valve, 284, first three-position four-way electromagnetic directional valve, 285, first Two shuttle valve, 286, second proportional flow control valve, 287, second three-position four-way electromagnetic directional valve, 288, third shuttle valve, 289, two-position three-way electromagnetic directional valve, 2810, second one-way Valve, 2811, third check valve, 2812, first check valve, 29, leveling valve, 291, first three-position four-way electromagnetic directional valve, 292, first shuttle valve, 293, constant pressure differential valve , 33, Luffing Cylinder, 34, Telescopic Cylinder, 37, Leveling Cylinder, 41, First Coupling, 42, Telescopic Coupling, 421, First Electric Proportional Pressure Reducing Valve, 422, Second Electric Proportional Pressure Reducing Valve, 423, First hydraulic proportional proportional valve, 424, first constant pressure differential valve, 425, fourth check valve, 43, variable amplitude coupling, 431, third electric proportional pressure reducing valve, 432, fourth electric proportional pressure reducing valve Valve, 433, second hydraulic proportional proportional valve, 434, second constant pressure differential valve, 435, fifth check valve, 44, leveling joint, 441, fifth electric proportional pressure reducing valve, 442, third Hydraulic proportional proportional valve, 443, third Pressure valve, 444, a sixth one-way valve 45, with the tail

detailed description

The present invention will be described in detail below with reference to the drawings and specific embodiments.

Example one

As shown in FIG. 3, a working bucket leveling system for an aerial work vehicle includes a constant pressure variable pump 23, a main valve 28, a leveling valve 29, a telescopic cylinder 34, a luffing cylinder 33, and a leveling cylinder 37; The differential pressure pump 23 pressure port P is connected to the main valve 28 pressure port P, the constant differential pressure pump 23 load feedback port LS is connected to the main valve 28 load feedback port LS, and the hydraulic oil enters the telescopic cylinder through the main valve 28 34 and luffing cylinder 33 to control telescopic and luffing movements; pressure port P1 of main valve 28 is connected to pressure port P of leveling valve 29, and oil return port T1 of main valve 28 and return of leveling valve 29 The oil port T is connected, and the hydraulic oil enters the leveling cylinder 37 through the leveling valve 29 to control the leveling action of the leveling cylinder 37. The main valve 28 is a cartridge valve; the maximum load on the telescopic cylinder 34 and the luffing cylinder 33 The pressure is fed back to the load-sensitive port LS of the constant pressure differential variable pump 23;

The main valve 28 includes an overflow valve 282, a proportional flow control valve, a three-position four-way electromagnetic directional valve, a shuttle valve, a one-way valve, a two-position three-way electromagnetic directional valve 289, and a speed regulating valve 281. The oil inlet of the relief valve 282, the oil inlet of the first proportional flow control valve 283, and the oil inlet of the second proportional flow control valve 286 are connected to the pressure oil port P of the main valve 28. The first ratio The oil outlet of the flow control valve 283 is connected to the oil inlet of the first three-position four-way electromagnetic directional valve 284, and the oil outlet of the second proportional flow control valve 286 is connected to the second three-position four-way electromagnetic directional valve 287. The oil inlets are connected. The first oil outlet of the first three-position four-way electromagnetic directional valve 284 and the first oil inlet of the second shuttle valve 285 are connected in parallel at the rod cavity end of the telescopic cylinder 34. The second oil outlet of the electromagnetic switching valve 284 and the second oil inlet of the second shuttle valve 285 are connected in parallel at the rodless cavity end of the telescopic cylinder 34, and the first outlet of the second three-position four-way electromagnetic switching valve 287 The oil port is connected in parallel with the first oil inlet of the third shuttle valve 288 at the rod cavity end of the luffing cylinder 33, and the second oil outlet of the second three-position four-way electromagnetic directional valve 287 and the third shuttle valve 288 The second oil inlet is connected in parallel to the rodless cavity end of the luffing cylinder 33. The oil outlet of the second shuttle valve 285 is connected to the oil inlet of the second check valve 2810. The oil outlet of the third shuttle valve 288 is connected to the first Three orders The inlet of the check valve 2811 is connected. The outlets of the first check valve 2812, the second check valve 2810 and the third check valve 2811 are connected to the load feedback port LS of the main valve 28. The oil return port of the four-way electromagnetic directional valve 284, the oil return port of the second three-position four-way electromagnetic directional valve 287, the oil return of the directional valve 289, and the oil outlet of the relief valve 282 are all connected to the main valve 28. The oil return port T is connected; the main valve 28 pressure port P and the leveling valve 29 pressure port P are connected on the oil line with a two-position three-way electromagnetic directional valve 289. When 289 loses power, the pressure port P of the leveling valve 29 is zero. When the two-position three-way electromagnetic directional valve 289 is switched by electricity, the pressure port P of the constant pressure variable pump 23 passes the speed regulating valve 281 and The P port of the leveling valve 29 is in communication, and is fed back to the load-sensitive oil port LS of the constant pressure differential variable pump 23 through the first check valve 2812 connected to the oil outlet of the two-position three-way electromagnetic directional valve 289;

The leveling valve 29 includes a first shuttle valve 292, a three-position four-way electromagnetic proportional valve 291, and a constant pressure differential valve 293. The a, c ports of the constant pressure differential valve 293, and the three-position four-way electromagnetic proportional valve 291. The oil inlet is connected in parallel to the pressure port P of the leveling valve 29. The first oil outlet of the three-position four-way electromagnetic proportional valve 291 and the first oil inlet of the first shuttle valve 292 are connected in parallel to the leveling cylinder 37. The rod outlet end, the second oil outlet of the three-position four-way electromagnetic proportional valve 291 and the second oil inlet of the first shuttle valve are connected in parallel to the rodless cavity end of the leveling cylinder, and the oil output of the first shuttle valve 292 is The port feeds back pressure to the d port of the constant pressure differential valve 293, and the oil return port of the three-position four-way electromagnetic proportional valve 291 and the b port of the constant pressure differential valve 293 are connected in parallel to the oil return path T of the system.

The specific working principle is as follows:

a) When the telescopic action is performed separately, the first three-position four-way electromagnetic directional valve 284 is energized, the second three-position four-way electromagnetic directional valve 287 and the two-position three-way electromagnetic directional valve 289 lose power, and the hydraulic oil flows in separately. Telescopic oil cylinder 34, the two-port three-way electromagnetic directional valve 289 is connected to the oil return port, that is, the inlet pressure of the first check valve 2812 is zero, that is, the pressure of the P port of the leveling valve 29 is also zero; The shuttle valve 285 transmits the telescopic action load pressure to the LS port of the constant pressure differential variable pump 23 through the second check valve 2810. At this time, the system is a load-sensitive system.

b) When the amplitude is changed separately, the first three-position four-way electromagnetic directional valve 284 loses power, the second three-position four-way electromagnetic directional valve 287 and the two two-way electromagnetic directional valve 289 are energized, and hydraulic oil flows in. Luffing cylinder 33; The two-position three-way electromagnetic directional valve 289 is connected to the oil inlet and the oil outlet, the oil return port is closed, and the hydraulic oil is supplied to the P port of the leveling valve 29 at a constant flow through the speed regulating valve 281. The flow rate flows away from the constant pressure differential valve 293. At this time, the leveling action of the bucket will not cause slow system response and leveling lag; the constant pressure differential valve 293 makes the three-position four-way electromagnetic proportional valve 291 have a constant pressure difference across the two ends. The flow through the three-position four-way electromagnetic proportional valve 291 is only related to the opening of the three-position four-way electromagnetic proportional valve 291. Changing the leveling flow by changing the opening size of the three-position four-way electromagnetic proportional valve 291 is more convenient to control; The three shuttle valve 288 is used to select the load pressure of the luffing action. The third check valve 2811 and the first one-way valve 2812 compare the luffing action load pressure and the leveling action load pressure, and transfer a larger load to the constant load. The LS port of the differential pressure variable pump 23, and the amplitude-changing action system is a load-sensitive system at this time.

c) When the telescopic and luffing combined action, the first three-position four-way electromagnetic directional valve 284, the second three-position four-way electromagnetic directional valve 287 and the two-position three-way electromagnetic directional valve 289 are energized, and the hydraulic oil is simultaneously It flows into the telescopic oil cylinder 34 and the luffing oil cylinder 33; the two-position three-way electromagnetic directional valve 289 communicates with the oil inlet and the oil outlet, the oil return port is closed, and the hydraulic oil passes through the speed regulating valve 281 to the P of the leveling valve 29 at a constant flow rate. The port is supplied with oil, and the excess flow flows away from the constant pressure differential valve 293. At this time, the leveling action of the working bucket will not cause slow system response and leveling lag; the constant pressure differential valve 293 makes the three-position four-way electromagnetic proportional valve 291 at both ends. The pressure difference is constant. At this time, the flow rate through the three-position four-way electromagnetic proportional valve 291 is only related to the opening of the three-position four-way electromagnetic proportional valve 291. The leveling flow is changed by changing the opening size of the three-position four-way electromagnetic proportional valve 291. More convenient to control; the second shuttle valve 285 takes the telescopic action load pressure, the third shuttle valve 288 takes the luffing action load pressure, the first check valve 2812, the second check valve 2810 and the third check valve 2811 will be leveled Compare operating load pressure, telescopic operation load pressure, and luffing operation load pressure The large difference in load transfer to the constant pressure variable pump LS port 23, this time stretching, compound action luffing load sensing system.

Example two

A bucket leveling system for an aerial work vehicle includes a constant pressure differential variable pump 23, a main valve 28, a leveling valve 29, a telescopic oil cylinder 34, a luffing cylinder 33, and a leveling oil cylinder 37; and the pressure of the constant pressure differential variable pump 23 The oil port P is connected to the pressure port P of the main valve 28, and the load feedback port LS of the constant pressure variable pump 23 is connected to the load feedback port LS of the main valve 28. The hydraulic oil enters the telescopic cylinder 34 and the luffing cylinder 33 through the main valve 28. Thus, the telescopic action and the luffing action are controlled; the pressure port P1 of the main valve 28 is connected to the pressure port P of the leveling valve 29, and the return port T1 of the main valve 28 is connected to the return port T of the leveling valve 29. The oil enters the leveling cylinder 37 through the leveling valve 29 to control the leveling action of the leveling cylinder 37. The main valve is a multi-way valve, which includes a first connection 41, a telescopic connection 42, a luffing connection 43, a leveling connection 44 and Tail coupling 45, of which telescopic coupling 42, amplitude-changing coupling 43 and leveling coupling 44 all include constant pressure differential valve, hydraulic proportional proportional valve and check valve, first hydraulic proportional valve, 423 and second hydraulic valve The oil inlets of the proportional directional valve 433 and the third hydraulically controlled proportional directional valve 442 are connected to the pressure port P of the main valve. The first hydraulically controlled proportional directional valve 423 and the second The return ports of the proportional control valve 433 and the third hydraulic proportional valve 442 are connected to the return port T of the main valve; the first constant pressure differential valve 424, the second constant pressure differential valve 434, and the third fixed pressure The control port of the differential pressure valve 443 is connected to the load-sensitive port LS of the main valve; the left control port of the first hydraulic proportional proportional valve 423 is connected to the first electric proportional pressure reducing valve 421, and the first hydraulic control The right control oil port of the proportional valve 423 is connected to the second electric proportional pressure reducing valve 422. The left control oil port of the second hydraulic proportional valve 433 is connected to the third electric proportional pressure reducing valve 431. The right control oil port of the hydraulic proportional valve 433 is connected to the fourth electric proportional pressure reducing valve 432, and the left control oil port of the third hydraulic valve is connected to the fifth electric proportional pressure reducing valve 441. The right control oil port of the third hydraulic proportional proportional valve 442 is directly connected to the fuel tank;

As shown in Figures 4 and 5, the first hydraulically controlled proportional directional valve 423, the second hydraulically controlled proportional directional valve 433, and the third hydraulically controlled proportional directional valve 442 are three-position eight-way directional valves. The a port and the c port of the valve communicate with each other and are connected in parallel to the return port T. The b port is connected to the pressure port T. The d port and the h port of the first hydraulic proportional valve 423 are connected to The rod cavity end and the rod cavity end of the telescopic oil cylinder 34 are connected. The d and h ports of the second hydraulic proportional proportional valve 433 are connected to the rod cavity end and the rodless cavity end of the luffing cylinder 33, respectively. The d and h ports of the third hydraulic proportional valve 442 are connected to the pressure port P1 and the return port T1 of the main valve, respectively. The e and g ports of the first hydraulic proportional valve 423 are connected. Connected in parallel to the oil outlet of the first constant pressure differential valve 424. At the same time, the oil outlet of the first constant pressure differential valve 424 is connected to the oil inlet of the fourth one-way valve 425. The e port and the g port are connected in parallel to the oil outlet of the second constant pressure differential valve 434, while the oil outlet of the second constant pressure differential valve 434 is connected to the oil inlet of the fifth check valve 435, and the third fluid The e port and g port of the proportional control valve 442 are connected in parallel to the At the oil outlet of the constant pressure differential valve 443, at the same time, the oil outlet of the third constant pressure differential valve 443 is connected to the oil inlet of the sixth check valve 444; the f port of the first hydraulic proportional proportional valve 423 is connected to The oil inlet of the first certain differential pressure valve 424 is connected, the f port of the second hydraulic proportional proportional valve 433 is connected to the oil inlet of the second fixed differential pressure valve 434, and the third hydraulic controlled proportional valve 442 is connected. f The oil port is connected to the oil inlet of the third fixed differential pressure valve 443;

When the fifth electric proportional pressure reducing valve 441 in the leveling unit loses power, there is no pressure input at the control end of the third hydraulic proportional proportional valve 442, so it acts in the neutral position. At this time, no hydraulic oil passes the third hydraulic proportional proportional valve. To the valve 442, so the pressure of port P1 and T1 of the leveling union 44 is zero, and the inlet pressure of the sixth check valve 444 is zero; when the fifth electric proportional pressure reducing valve 441 is powered, the hydraulic proportional proportional valve 442 Working in the left position, the control end of the third hydraulic proportional proportional valve 442 has a constant pressure to control its reversing, and the hydraulic oil is transmitted to the sixth through the third hydraulic proportional proportional valve 442 and the third constant pressure differential valve 443. The oil inlet of the one-way valve 444 is fed back to the leveling pressure port P1 through the third hydraulic proportional proportional valve 442. The three constant pressure differential valve 443, so that the pressure at both ends is constant, so the P1 port of the leveling union 44 supplies oil to the leveling valve 29 at a constant flow rate. At this time, the fifth electric proportional pressure reducing valve 441 and the third hydraulic proportional valve The common effect of the directional valve 442 and the third constant pressure differential valve 443 is the same as that of the two-position three-way electromagnetic directional valve and the speed regulating valve in the cartridge valve.

The specific working principle is as follows:

a) When the telescopic action is performed separately, the fifth electric proportional pressure reducing valve 441 loses power, the third hydraulic proportional proportional valve 442 works in the neutral position, and the pressure of port P1 and T1 of the leveling union 44 is zero. The inlet pressure of the check valve 444 is zero; the load pressure of the telescopic coupling 42 is transmitted to the LS port of the constant pressure differential variable pump 23 through the fourth check valve 425, and the system is a load-sensitive system at this time.

b) When the amplitude is changed separately, the fifth electric proportional pressure reducing valve 441 is energized and the voltage is a constant value. The third hydraulic proportional proportional valve 442 works in the left position, and the P1 port of the leveling union 44 is constant. The flow supplies oil to the leveling valve 29, and the excess flow flows away from the constant pressure differential valve 293. At this time, the leveling action of the bucket will not cause slow system response and leveling lag; the constant pressure differential valve 293 makes the three-position four-way electromagnetic The pressure difference between the two ends of the proportional valve 291 is constant. At this time, the flow rate through the three-position four-way electromagnetic proportional valve 291 is only related to the opening of the three-position four-way electromagnetic proportional valve 291. The leveling flow is changed; the fifth check valve 435 and the sixth check valve 444 compare the luffing action load pressure and the leveling action load pressure, and transmit a larger load to the LS port of the constant pressure differential variable pump 23, In this case, the system is a load-sensitive system.

c) When the telescopic and variable amplitude combined actions are performed, the fifth electric proportional pressure reducing valve 441 is energized and the voltage is a constant value. The third hydraulic proportional proportional valve 442 works in the left position, and the P1 port of the leveling union 44 is leveled. Supply oil to the leveling valve 29 at a constant flow rate, and the excess flow will flow off from the constant pressure differential valve 293. At this time, the leveling action of the bucket will not cause slow system response and leveling lag; The pressure difference between the two-way electromagnetic proportional valve 291 is constant. At this time, the flow through the three-position four-way electromagnetic proportional valve 291 is only related to the opening of the three-position four-way electromagnetic proportional valve 291. By changing the opening of the three-position four-way electromagnetic proportional valve 291 Size to change the leveling flow; the fourth check valve 425, the fifth check valve 435, and the sixth check valve 444 compare the telescopic action load pressure, the luffing action load pressure, and the leveling action load pressure, which will be larger The load is transferred to the LS port of the constant pressure differential variable pump 23, and the system is a load-sensitive system at this time.

Claims

A bucket leveling system for an aerial work vehicle includes a constant pressure variable pump (23), a main valve (28), a leveling valve (29), a telescopic oil cylinder (34), a luffing oil cylinder (33), and a leveling Cylinder (37); constant pressure difference variable pump (23) pressure port P is connected to main valve (28) pressure oil port P, constant pressure difference variable pump (23) load feedback port LS and main valve (28) load feedback The oil port LS is connected, and the hydraulic oil enters the telescoping cylinder (34) and the luffing cylinder (33) through the main valve (28) to control the telescoping and luffing action; the pressure port P1 of the main valve (28) and the leveling valve ( The pressure oil port P of 29) is connected, the oil return port T1 of the main valve (28) is connected to the oil return port T of the leveling valve (29), and the hydraulic oil enters the leveling cylinder (37) through the leveling valve (29) to thereby Control the leveling action of the leveling cylinder (37); characterized in that the main valve (28) can be a cartridge valve or a multi-way valve; the maximum load pressure on the telescopic cylinder (34) and the luffing cylinder (33) Both are fed back to the load-sensitive port LS of the constant-pressure differential variable pump (23); the main valve (28) pressure port P and the leveling valve (29) pressure port P are provided with a directional valve on the oil line, When the selector valve is in the spring position, the pressure port P of the leveling valve (29) The force is zero. When the reversing valve is reversing, the pressure port P of the constant pressure differential variable pump (23) communicates with the P port of the leveling valve (29) through the flow rate adjusting device, and is connected to the oil outlet of the reversing valve. The check valve at the position is fed back to the load-sensitive port LS of the constant pressure differential variable pump (23).
The bucket leveling system for an aerial work vehicle according to claim 1, wherein the leveling valve (29) comprises a first shuttle valve (292), a three-position four-way electromagnetic proportional valve (291), and a fixed Differential pressure valve (293), constant pressure difference valve (293) a port, c port and three-position four-way electromagnetic proportional valve (291) inlet are connected in parallel to the pressure port of the leveling valve (29) At P, the first oil outlet of the three-position four-way electromagnetic proportional valve (291) and the first oil inlet of the first shuttle valve (292) are connected in parallel to the rod cavity end of the leveling cylinder (37). The second oil outlet of the electromagnetic proportional valve (291) and the second oil inlet of the first shuttle valve are connected in parallel to the rodless cavity end of the leveling cylinder. The oil outlet of the first shuttle valve (292) feeds back pressure to The d port of the constant pressure difference valve (293), the oil return port of the three-position four-way electromagnetic proportional valve (291) and the b port of the constant pressure difference valve (293) are connected in parallel to the oil return path T of the system.
The bucket leveling system for a high-altitude operation vehicle according to claim 2, characterized in that when the main valve (28) is a cartridge valve, it comprises a relief valve (282), a proportional flow control valve, and a three-position four-way solenoid Reversing valve, shuttle valve and check valve, oil inlet of the relief valve (282), oil inlet of the first proportional flow control valve (283), and oil inlet of the second proportional flow control valve (286) The ports are connected to the pressure oil port P of the main valve (28). The oil outlet of the first proportional flow control valve (283) is connected to the oil inlet of the first three-position four-way electromagnetic directional valve (284). The oil outlet of the proportional flow control valve (286) is connected to the oil inlet of the second three-position four-way electromagnetic directional valve (287), and the first oil outlet of the first three-position four-way electromagnetic directional valve (284) Parallel to the first oil inlet of the second shuttle valve (285) at the rod cavity end of the telescopic oil cylinder (34), the second oil outlet of the first three-position four-way electromagnetic directional valve (284) and the second shuttle The second oil inlet of the valve (285) is connected in parallel to the rodless cavity end of the telescopic cylinder (34), and the first oil outlet of the second three-position four-way electromagnetic directional valve (287) and the third shuttle valve (288) The first oil inlet is connected in parallel with the rod of the luffing cylinder (33) End, the second oil outlet of the second three-position four-way electromagnetic directional valve (287) and the second oil inlet of the third shuttle valve (288) are connected in parallel at the rodless cavity end of the luffing cylinder (33). The oil outlet of the second shuttle valve (285) is connected to the oil inlet of the second check valve (2810), and the oil outlet of the third shuttle valve (288) is connected to the oil inlet of the third check valve (2811). The oil outlets of the first check valve (2812), the second check valve (2810) and the third check valve (2811) are connected to the load feedback port LS of the main valve (28). The oil return port of the four-way electromagnetic directional valve (284), the oil return port of the second three-position four-way electromagnetic directional valve (287), the oil return port of the directional valve (289), and the relief valve (282). The oil outlets are connected to the oil return port T of the main valve 28.
The bucket leveling system for a high-altitude operation vehicle according to claim 3, wherein the directional valve is a two-position three-way electromagnetic directional valve (289), and the flow rate adjusting device is a speed regulating valve (281 ).
The working bucket leveling system for an aerial work vehicle according to claim 2, characterized in that when the main valve is a multi-way valve, it comprises a first coupling (41), a telescopic coupling (42), a luffing coupling (43), a regulating The flat coupling (44) and tail coupling (45), among which the telescopic coupling (42), the luffing coupling (43) and the leveling coupling (44) all include a constant pressure differential valve, a hydraulic proportional proportional valve and a check valve. The oil inlets of the first hydraulic proportional valve (423), the second hydraulic proportional valve (433), and the third hydraulic proportional valve (442) are connected to the pressure port P of the main valve. The oil return ports of the first hydraulic proportional valve (423), the second hydraulic proportional valve (433) and the third hydraulic proportional valve (442) are all connected to the oil return port T of the main valve; The control ports of the first constant differential pressure valve (424), the second constant differential pressure valve (434), and the third constant differential pressure valve (443) are connected to the load-sensitive port LS of the main valve; the first hydraulic control ratio The left control oil port of the directional valve (423) is connected to the first electric proportional pressure reducing valve (421), and the right control oil port of the first hydraulic proportional valve (423) is connected to the second electric proportional pressure reducing valve. (422) connected, the left control port of the second hydraulic proportional proportional valve (433) and the third electric proportional The pressure valve (431) is connected, the right control port of the second hydraulic proportional valve (433) is connected to the fourth electric proportional pressure reducing valve (432), and the left side of the third hydraulic proportional valve (442) The side control oil port is connected to the fifth electric proportional pressure reducing valve (441), and the right control oil port of the third hydraulic proportional valve (442) is directly connected to the fuel tank.
The bucket leveling system for an aerial work vehicle according to claim 5, characterized in that the first hydraulically controlled proportional reversing valve (423), the second hydraulically controlled proportional reversing valve (433), and the third hydraulically controlled proportional The reversing valves (442) are three-position eight-way reversing valves. The a port and the c port of the reversing valve communicate with each other and are connected in parallel to the return port T. The b port is connected to the pressure port T. The d port and the h port of a hydraulically controlled proportional directional valve (423) are connected to the rod cavity end and the rodless cavity end of the telescopic oil cylinder (34), respectively. The oil port and the h port are respectively connected to the rod cavity end and the rodless end of the luffing cylinder (33), and the d port and the h port of the third hydraulic proportional proportional valve (442) are respectively connected to the main valve. The pressure port P1 is connected to the oil return port T1. The e port and the g port of the first hydraulic proportional valve (423) are connected in parallel to the oil outlet of the first constant pressure differential valve (424). The oil outlet of the constant pressure differential valve (424) is connected to the oil inlet of the fourth check valve (425), and the e and g ports of the second hydraulic proportional proportional valve (433) are connected in parallel to the second fixed valve. The oil outlet of the differential pressure valve (434), while the oil outlet of the second constant pressure differential valve (434) and the fifth The oil inlet of the valve (435) is connected. The e and g ports of the third hydraulic proportional valve (442) are connected in parallel to the oil outlet of the third constant pressure differential valve (443). The oil outlet of the constant pressure differential valve (443) is connected to the oil inlet of the sixth check valve (444); the f port of the first hydraulic proportional proportional valve (423) is connected to the first fixed differential pressure valve (424 ) Is connected to the oil inlet, the f port of the second hydraulic proportional proportional valve (433) is connected to the oil inlet of the second fixed differential pressure valve (434), and the third hydraulic controlled proportional valve (442) f The oil port is connected to the oil inlet of the third fixed differential pressure valve (443).