An automatic leveling hydraulic system for the working platform of an aerial work vehicle

Abstract

The present invention proposes an automatic leveling hydraulic system for the working platform of an aerial work vehicle, comprising a platform leveling cylinder, a turntable leveling cylinder, a first load holding valve, a second load holding valve and an O-type mid-position function reversing valve; the working oil port A and the working oil port B of the reversing valve are respectively connected to the oil inlet of the first load holding valve and the second load holding valve; the large chamber of the platform leveling cylinder is connected to the oil outlet of the first load holding valve; the small chamber of the platform leveling cylinder is connected to the oil outlet of the second load holding valve; a third load holding valve is also arranged between the large chamber of the platform leveling cylinder and the oil outlet of the first load holding valve; a fourth load holding valve is also arranged between the small chamber of the platform leveling cylinder and the oil outlet of the second load holding valve; the working oil port A and the working oil port B of the reversing valve are also respectively connected to the first pressure relief valve and the second pressure relief valve. The present invention can reduce manufacturing costs and solve the hidden dangers of platform tilting during operation, and improve the safety performance of the work vehicle.

Description

Technical Field

[0001] The invention relates to the field of hydraulic control equipment for engineering machinery, and in particular to an automatic leveling hydraulic system for a working platform of an aerial work vehicle. Background Art

[0002] The platform leveling system of the hybrid arm or telescopic arm aerial work vehicle currently using hydraulic leveling is as follows Figure 1 For the convenience of operation, two reversing valves are installed at the rotating platform and the working platform to control the leveling of the working platform. The leveling system uses a balancing valve + two overflow valves + a hydraulic lock to achieve load retention. The reversing valve can only use one O-type center function + one O-type center function with throttling or two O-type center functions with throttling, otherwise the pressure cannot be established during active leveling, making the platform unable to perform leveling. The above leveling system has the following problems:

[0003] 1. The manufacturing cost of the O-type center position valve core with throttling is high, and the processing accuracy is difficult to ensure, resulting in unreliable leveling performance;

[0004] 2. The hydraulic lock is easy to open and the pilot pressure cannot be adjusted;

[0005] 3. Due to the inevitable hydraulic oil leakage between the sliding valve core and the valve body, when the vehicle is working, the leaked hydraulic oil accumulates to generate enough pressure to open the hydraulic lock, so that the leveling system is connected to the outside world, and the hydraulic oil in the leveling system flows out, causing the platform to tilt. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes an automatic leveling hydraulic system for the working platform of an aerial work vehicle, which can effectively reduce the manufacturing cost, solve the hidden danger of platform tilting during operation, and improve the safety performance of the work vehicle.

[0007] Technical solution: The present invention proposes an automatic leveling hydraulic system for the working platform of an aerial work vehicle, comprising a platform leveling cylinder, a turntable leveling cylinder, a first load holding valve, a second load holding valve and a plurality of reversing valves with O-type neutral position functions; the working oil ports A of the plurality of reversing valves are commonly connected to the oil inlet of the first load holding valve; the large chamber of the platform leveling cylinder and the large chamber of the turntable leveling cylinder are connected in parallel to the oil outlet of the first load holding valve; the working oil port B of the reversing valve is commonly connected to the oil inlet of the second load holding valve; the small chamber of the platform leveling cylinder and the small chamber of the turntable leveling cylinder are connected in parallel to the oil outlet of the second load holding valve;

[0008] A third load holding valve is further provided between the large chamber of the platform leveling oil cylinder and the oil outlet of the first load holding valve; the oil inlet of the third load holding valve is connected to the oil outlet of the first load holding valve, and the oil outlet of the third load holding valve is connected to the large chamber of the platform leveling oil cylinder;

[0009] A fourth load holding valve is further provided between the small chamber of the platform leveling oil cylinder and the oil outlet of the second load holding valve; the oil inlet of the fourth load holding valve is connected to the oil outlet of the second load holding valve, and the oil outlet of the fourth load holding valve is connected to the small chamber of the platform leveling oil cylinder;

[0010] The working oil ports A of the plurality of reversing valves are also commonly connected to a first pressure relief valve; the working oil ports B of the plurality of reversing valves are also commonly connected to a second pressure relief valve.

[0011] Further, the first load holding valve, the second load holding valve, the third load holding valve and the fourth load holding valve are all balancing valves;

[0012] The pilot pressure control oil port K1 of the first load holding valve is connected to the oil inlet V2 of the second load holding valve; the pilot pressure control oil port K2 of the second load holding valve is connected to the oil inlet V1 of the first load holding valve; the pilot pressure control oil port K3 of the third load holding valve is connected to the oil inlet V4 of the fourth load holding valve; the pilot pressure control oil port K4 of the fourth load holding valve is connected to the oil inlet V3 of the third load holding valve.

[0013] Further, the first pressure relief valve and the second pressure relief valve are both two-position, two-way normally open solenoid valves.

[0014] Furthermore, each of the reversing valves is provided with a travel switch detection block and a travel detection switch; the travel switch detection block is connected to the valve core of the reversing valve; the extension and retraction movement of the valve core drives the extension and retraction movement of the travel switch detection block, and the extension and retraction movement of the travel switch detection block triggers the contact of the turntable travel detection switch, and the travel detection switch 4 sends an electrical signal to cause the first pressure relief valve and the second pressure relief valve to switch.

[0015] Further, the first pressure relief valve and the second pressure relief valve are both flow valves.

[0016] Furthermore, there are two reversing valves, one for operation on the working platform and the other for operation on the rotating platform.

[0017] Beneficial effect: When the present invention performs conventional operations such as amplitude change, extension and retraction or rotation, the two reversing valves are in the middle position and all the oil ports of the reversing valves are closed; the first pressure relief valve and the second pressure relief valve remain open, and the hydraulic oil leaking from the reversing valve and flowing into the pipeline flows back to the oil tank through the first pressure relief valve and the second pressure relief valve, and no pilot pressure is established at the oil inlet V1 of the first load holding valve and the oil inlet V2 of the second load holding valve to open the two balancing valves for reverse flow, so that the platform can remain in a horizontal state during operation.

[0018] When the working platform needs to be tilted forward or backward, the first pressure relief valve and the second pressure relief valve are both closed; after operating any one of the reversing valves, the hydraulic oil flowing out of the reversing valve can build up pressure at the inlet of the oil inlet balancing valve, so that after the pilot pressure of the oil return balancing valve reaches a certain value, the oil return balancing valve is reversed, and the platform can now tilt forward or backward. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the prior art;

[0020] Figure 2 A schematic diagram of the structure of an embodiment of the present invention;

[0021] Figure 3 It is a structural schematic diagram of another embodiment of the present invention. DETAILED DESCRIPTION

[0022] like Figure 2 As shown, an automatic leveling hydraulic system for the working platform of an aerial work vehicle comprises a platform leveling cylinder 11, a turntable leveling cylinder 8, a first load holding valve 6, a second load holding valve 7 and two O-type center-position function reversing valves 3. The two reversing valves 3 are used for operating on the working platform and on the rotating platform respectively.

[0023] The working oil ports A of the two reversing valves 3 are commonly connected to the oil inlet of the first load holding valve 6; the large chamber of the platform leveling cylinder 11 and the large chamber of the turntable leveling cylinder 8 are connected in parallel to the oil outlet of the first load holding valve 6; the working oil ports B of the reversing valve 3 are commonly connected to the oil inlet of the second load holding valve 7; the small chamber of the platform leveling cylinder 11 and the small chamber of the turntable leveling cylinder 8 are connected in parallel to the oil outlet of the second load holding valve 7.

[0024] A third load holding valve 9 is also arranged between the large chamber of the platform leveling cylinder 11 and the oil outlet of the first load holding valve 6; the oil inlet of the third load holding valve 9 is connected to the oil outlet of the first load holding valve 6, and the oil outlet of the third load holding valve 9 is connected to the large chamber of the platform leveling cylinder 11.

[0025] A fourth load holding valve 10 is also arranged between the small chamber of the platform leveling cylinder 11 and the oil outlet of the second load holding valve 7; the oil inlet of the fourth load holding valve 10 is connected to the oil outlet of the second load holding valve 7, and the oil outlet of the fourth load holding valve 10 is connected to the small chamber of the platform leveling cylinder 11.

[0026] Preferably, the first load holding valve 6, the second load holding valve 7, the third load holding valve 9 and the fourth load holding valve 10 are all balancing valves. The first load holding valve 6 includes an oil inlet V1, an oil outlet C1 and a pilot pressure control oil port K1; the second load holding valve 7 includes an oil inlet V2, an oil outlet C2 and a pilot pressure control oil port K2; the third load holding valve 9 includes an oil inlet V3, an oil outlet C3 and a pilot pressure control oil port K3; the fourth load holding valve 10 includes an oil inlet V4, an oil outlet C4 and a pilot pressure control oil port K4.

[0027] The balancing valve allows the oil to flow from the oil inlet V to the oil outlet C in one direction; when the oil pressure of the pilot pressure control oil port K reaches a certain value, the oil can flow from the oil outlet C to the oil inlet V; when the oil pressure of the pilot pressure control oil port K is insufficient, the oil flow from the oil outlet C to the oil inlet V is cut off.

[0028] The pilot pressure control oil port K1 of the first load holding valve 6 is connected to the oil inlet V2 of the second load holding valve 7; the pilot pressure control oil port K2 of the second load holding valve 7 is connected to the oil inlet V1 of the first load holding valve 6; the pilot pressure control oil port K3 of the third load holding valve 9 is connected to the oil inlet V4 of the fourth load holding valve 10; the pilot pressure control oil port K4 of the fourth load holding valve 10 is connected to the oil inlet V3 of the third load holding valve 9.

[0029] The working oil ports A of the two reversing valves 3 are also commonly connected to a first pressure relief valve 4 ; the working oil ports B of the two reversing valves 3 are also commonly connected to a second pressure relief valve 5 .

[0030] The working process of the present invention is as follows:

[0031] a. When performing routine operations such as amplitude change, telescopic or rotation, the two reversing valves 3 are in the middle position. Since the middle position function of the reversing valve 3 is an O-type function, all the oil ports of the reversing valve 3 are closed; the first load holding valve 6 and the second load holding valve 7 cannot flow in the reverse direction, and the platform leveling cylinder 11 and the turntable leveling cylinder 8 remain stopped. However, there is inevitable hydraulic oil leakage in the reversing valve 3, so the first pressure relief valve 4 and the second pressure relief valve 5 remain open, and the hydraulic oil flowing into the pipeline flows back to the oil tank through the first pressure relief valve 4 and the second pressure relief valve 5, and no pilot pressure that can open the two balance valves for reverse flow will be established at the oil inlet V1 of the first load holding valve 6 and the oil inlet V2 of the second load holding valve 7, so that the platform can remain horizontal during operation.

[0032] When the amplitude is changed, the piston of the turntable leveling cylinder 8 will move. If the large chamber of the turntable leveling cylinder 8 is compressed, the oil pressure will increase, and the oil will flow into the large chamber of the platform leveling cylinder 11 through the third load holding valve 9; the oil pressure of the oil inlet V3 of the third load holding valve 9 will increase, and after the pilot pressure of the fourth load holding valve 10 reaches a certain value, the oil outlet C4 of the fourth load holding valve 10 will be reversely connected to the oil inlet V4, and the oil in the small chamber of the platform leveling cylinder 11 can flow back to the small chamber of the turntable leveling cylinder 8, so that the platform leveling cylinder 11 follows the turntable leveling cylinder 8 to maintain the leveling state of the working platform. If the small chamber of the turntable leveling cylinder 8 is compressed, the working process is similar to the above.

[0033] b. When the working platform needs to tilt forward or backward, the first pressure relief valve 4 and the second pressure relief valve 5 are both closed; after any reversing valve 3 is operated, when the hydraulic oil enters the working oil port A from the pressure oil port P, because the middle position function of the reversing valve 3 is an O-type function, the hydraulic oil will not return from the working oil port A and the working oil port B of the other reversing valve 3. The hydraulic oil passes through the first load holding valve 6 and the third load holding valve 9 and enters the large chamber of the platform leveling cylinder 11. With the rapid accumulation of hydraulic oil, the oil pressure of the oil inlet V1 of the first load holding valve 6 and the oil pressure of the oil inlet V3 of the third load holding valve 9 increase. After the pilot pressure of the second load holding valve 7 and the fourth load holding valve 10 reaches a certain value, the oil outlet C2 of the second load holding valve 7 is reversely conducted to the oil inlet V2, and the oil outlet C4 of the fourth load holding valve 10 is reversely conducted to the oil inlet V4. The oil in the small chamber of the platform leveling cylinder 11 can flow back to the working oil port B of the first reversing valve 3, and the working platform can tilt forward or backward at this time. When the hydraulic oil enters the working oil port B from the pressure oil port P, the working process is similar to the above.

[0034] The first pressure relief valve 4 and the second pressure relief valve 5 can be selected from the following two types of valves:

[0035] 1. If Figure 2 , the first pressure relief valve 4 and the second pressure relief valve 5 are both two-position, two-position normally open solenoid valves. Each of the reversing valves 3 is provided with a travel switch detection bumper 2 and a travel detection switch 1; the switch contact of the travel detection switch 1 is just located at the position of the middle notch of the travel switch detection bumper 2. The travel switch detection bumper 2 is connected to the valve core of the reversing valve 3; the telescopic action of the valve core drives the telescopic action of the travel switch detection bumper 2, and the telescopic action of the travel switch detection bumper 2 triggers the contact of the travel detection switch 1, and the travel detection switch 1 sends an electrical signal to make the first pressure relief valve 4 and the second pressure relief valve 5 reversing action. The first pressure relief valve 4 and the second pressure relief valve 5 can automatically follow the action of the reversing valve to adjust the switch state.

[0036] 2. If Figure 3The first pressure relief valve 4 and the second pressure relief valve 5 are both flow valves.

[0037] Before operation, adjust the flow valve throttle holes of the first pressure relief valve 4 and the second pressure relief valve 5 to appropriate sizes.

[0038] When performing operations such as amplitude change, extension, or rotation, the hydraulic oil leaked into the pipeline by the reversing valve 3 can flow back to the oil tank through the oil outlets of the first pressure relief valve 4 and the second pressure relief valve 5, and no pilot pressure will be established at the oil inlet V1 of the first load holding valve 6 and the oil inlet V2 of the second load holding valve 7 to open the two balancing valves for reverse flow, so that the working platform can remain in a horizontal state during operation.

[0039] When the working platform needs to tilt forward or backward, the reversing valve 3 is turned on, and the hydraulic oil enters the hydraulic pipeline. However, due to the small throttling openings of the first pressure relief valve 4 and the second pressure relief valve 5, the first pressure relief valve 4 and the second pressure relief valve 5 cannot completely release the hydraulic oil that quickly enters the hydraulic pipeline under the set safety overflow pressure. The hydraulic oil can still accumulate quickly, so that the pilot pressure that can open the reverse flow of the two balance valves is established at the oil inlet V1 of the first load holding valve 6 and the oil inlet V2 of the second load holding valve 7. At this time, the working platform can tilt forward or backward.

Claims

1. An automatic leveling hydraulic system for an aerial work vehicle working platform, characterized in that: It includes a platform leveling cylinder, a turntable leveling cylinder, a first load holding valve, a second load holding valve and a plurality of O-type reversing valves with neutral position functions; the working oil ports A of the plurality of reversing valves are connected to the oil inlet of the first load holding valve; the large chamber of the platform leveling cylinder and the large chamber of the turntable leveling cylinder are connected in parallel to the oil outlet of the first load holding valve; the working oil port B of the reversing valve is connected to the oil inlet of the second load holding valve; the small chamber of the platform leveling cylinder and the small chamber of the turntable leveling cylinder are connected in parallel to the oil outlet of the second load holding valve; A third load holding valve is further provided between the large chamber of the platform leveling oil cylinder and the oil outlet of the first load holding valve; the oil inlet of the third load holding valve is connected to the oil outlet of the first load holding valve, and the oil outlet of the third load holding valve is connected to the large chamber of the platform leveling oil cylinder; A fourth load holding valve is further provided between the small chamber of the platform leveling oil cylinder and the oil outlet of the second load holding valve; the oil inlet of the fourth load holding valve is connected to the oil outlet of the second load holding valve, and the oil outlet of the fourth load holding valve is connected to the small chamber of the platform leveling oil cylinder; The working oil ports A of the plurality of reversing valves are also commonly connected to a first pressure relief valve; the working oil ports B of the plurality of reversing valves are also commonly connected to a second pressure relief valve; There are two reversing valves, one for operation on the working platform and the other for operation on the rotating platform.

2. The automatic leveling hydraulic system for the working platform of an aerial work vehicle according to claim 1 is characterized in that: The first load holding valve, the second load holding valve, the third load holding valve and the fourth load holding valve are all balancing valves; The pilot pressure control oil port K1 of the first load holding valve is connected to the oil inlet V2 of the second load holding valve; the pilot pressure control oil port K2 of the second load holding valve is connected to the oil inlet V1 of the first load holding valve; the pilot pressure control oil port K3 of the third load holding valve is connected to the oil inlet V4 of the fourth load holding valve; the pilot pressure control oil port K4 of the fourth load holding valve is connected to the oil inlet V3 of the third load holding valve.

3. The automatic leveling hydraulic system for the working platform of an aerial work vehicle according to claim 1 or 2, characterized in that: The first pressure relief valve and the second pressure relief valve are both two-position, two-way normally open solenoid valves.

4. The automatic leveling hydraulic system for the working platform of an aerial work vehicle according to claim 3 is characterized by: Each of the reversing valves is provided with a travel switch detection block and a travel detection switch; the travel switch detection block is connected to the valve core of the reversing valve; the extension and retraction movement of the valve core drives the extension and retraction movement of the travel switch detection block, and the extension and retraction movement of the travel switch detection block triggers the contact of the travel detection switch, and the travel detection switch sends an electrical signal to cause the first pressure relief valve and the second pressure relief valve to switch.

5. The automatic leveling hydraulic system for the working platform of an aerial work vehicle according to claim 1 or 2, characterized in that: The first pressure relief valve and the second pressure relief valve are both flow valves.

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