Overhead working truck and hydraulic system thereof

Abstract

The utility model belongs to the technical field of fluid working systems of movable working platforms, and particularly provides an overhead working truck and a hydraulic system thereof. The hydraulic system of the overhead working truck comprises a loading valve group, a supporting leg valve group, a public oil inlet path and a public oil return path, the public oil inlet path and the public oil return path are communicated with the loading valve group and the supporting leg valve group, a proportional flow valve is connected to the public oil inlet path, and the hydraulic system further comprises a hydraulic control logic valve connected with the proportional flow valve in parallel. An oil inlet of the hydraulic control logic valve is communicated with the public oil inlet way, an oil outlet of the hydraulic control logic valve is communicated with the public oil return way, and a hydraulic control port of the hydraulic control logic valve is communicated with an oil outlet of the proportional flow valve. The overhead working truck comprises the hydraulic system. The hydraulic control logic valve connected in parallel with the proportional flow valve on the public oil way is additionally arranged on the hydraulic system, so that the pressure difference between the two ends of the oil inlet and the oil outlet of the proportional flow valve is constant and is not influenced by external load change, and the action stability of the loading and landing leg system is improved. Meanwhile, the hydraulic system is simple in structure, and cost is easy to control.

Description

Technical Field

[0001] The utility model belongs to the technical field of fluid working systems of mobile working platforms, and particularly relates to an aerial work vehicle and its hydraulic system. Background Art

[0002] When maintaining and overhauling power systems, aerial work vehicles are commonly used equipment. The aerial work vehicle is equipped with an upper mounting system and outrigger systems. The upper mounting system includes an insulating boom, which can perform multi-directional movements such as left and right, up and down swinging to meet the requirements of different working environments. The outrigger systems generally include four outriggers. During operation, the outriggers extend downward and tighten the ground to ensure the stability of the aerial work vehicle.

[0003] In order to drive the movements of the insulating boom and each outrigger, the aerial work vehicle is generally also equipped with a hydraulic system. The actuators in the hydraulic system include multiple hydraulic cylinders and hydraulic motors, etc. The movement speed and movement stability of each actuator directly affect the movement stability of the insulating boom and the outriggers, thus relating to the user experience of the staff.

[0004] In the prior art, there are generally three ways to control the movements of each actuator. One is to directly use a switch reversing valve to control the direction of hydraulic oil in the oil circuit. However, this method cannot adjust the speed, and affected by the load change, the actuator is prone to phenomena such as unstable speed and swaying, and the movement stability is insufficient. The second is to add a proportional flow valve on the common inlet oil circuit of the upper mounting system and the outrigger systems to control the hydraulic oil flow, adjust the hydraulic oil volume entering each actuator of the upper mounting system and each actuator of the outrigger systems, and then adjust the speed of the actuator. Although this method can achieve the adjustment of the movement speed, affected by the load change, the pressure difference at both ends of the proportional flow valve is unstable, and the actuator will still have phenomena such as unstable speed and swaying, and the movement stability is insufficient. The third is that the upper mounting system and the outrigger systems use independent proportional reversing valves to control the direction of hydraulic oil and stabilize the flow. Although this can stably control the speed of the actuator, the number of control valve groups is large, the system is complex, resulting in too high cost of the hydraulic system. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a hydraulic system for an aerial work vehicle to solve the technical problems that in the hydraulic system with only a proportional flow valve in the prior art, the movement stability of each actuator is still insufficient, and the high cost of the hydraulic system caused by the need for multiple control valve groups to improve the movement stability of the actuator. The purpose of the utility model is also to provide an aerial work vehicle to solve the same technical problems.

[0006] To achieve the above purpose, the technical solution of the hydraulic system for the aerial work vehicle provided by the utility model is:

[0007] A hydraulic system for an aerial work vehicle, comprising an upper mounting valve group for controlling the actions of the executing elements of the upper mounting system, a outrigger valve group for controlling the actions of the executing elements of the outrigger system, as well as a common inlet oil circuit and a common return oil circuit that are both connected to the upper mounting valve group and the outrigger valve group. A proportional flow valve is connected to the common inlet oil circuit. The hydraulic system further includes a hydraulic control logic valve connected in parallel with the proportional flow valve. The inlet of the hydraulic control logic valve is connected to the common inlet oil circuit, the outlet is connected to the common return oil circuit, and the hydraulic control port is connected to the outlet of the proportional flow valve.

[0008] As a further improvement, a pressure limiting oil circuit is connected in parallel between the outlet of the proportional flow valve and the common return oil circuit, and a relief valve is provided on the pressure limiting oil circuit.

[0009] As a further improvement, a first damping is provided on the pressure limiting oil circuit, and the first damping is located upstream of the relief valve.

[0010] As a further improvement, a second damping is further provided between the hydraulic control port of the hydraulic control logic valve and the outlet of the proportional flow valve.

[0011] As a further improvement, a check valve is further provided on the common inlet oil circuit, and the check valve is located downstream of the proportional flow valve.

[0012] As a further improvement, the hydraulic system further includes a rotary joint, and the upper mounting valve group is connected to the common inlet oil circuit and the common return oil circuit through the rotary joint.

[0013] As a further improvement, the proportional flow valve has a return port, and the return port is connected to the common return oil circuit.

[0014] As a further improvement, the hydraulic system further includes a manual pump, and the manual pump is connected to the common inlet oil circuit.

[0015] As a further improvement, the hydraulic control logic valve is a normally closed two-position two-way directional control valve.

[0016] The beneficial effects are as follows: The present utility model belongs to an improved invention creation. Specifically, there is a proportional flow valve in the common oil inlet pipeline, and the opening degree of the valve port of the proportional flow valve can be adjusted to adjust the oil volume in the common oil inlet pipeline, thereby realizing the proportional speed regulation of all actions of the outriggers and the upper mounting system. Different from the prior art, a pilot-operated logic valve is added to the hydraulic system. The oil inlet and oil outlet of the pilot-operated logic valve are respectively communicated with the common oil inlet pipeline and the common oil return pipeline, the pilot port is communicated with the oil outlet of the proportional flow valve, and the pilot-operated logic valve is connected in parallel with the proportional flow valve. This ensures that the pressure difference between the two ends of the oil inlet and oil outlet of the proportional flow valve is constant. According to the throttling orifice pressure difference flow formula, the hydraulic oil flowing out of the oil outlet of the proportional flow valve is only related to the opening degree of the valve port of the proportional flow valve and is not affected by the change of the external load, thereby realizing the uniform speed control of the outriggers and the upper mounting actions and improving the system stability. Moreover, the present utility model does not require separate configuration of control valves for the upper mounting and the outriggers, and the hydraulic system has a simple structure and is easy to control costs.

[0017] To achieve the above object, the technical solution of the aerial work platform provided by the present utility model is:

[0018] An aerial work platform includes a hydraulic system. The hydraulic system includes an upper mounting valve group for controlling the actions of each actuator of the upper mounting system, an outrigger valve group for controlling the actions of each actuator of the outrigger system, and a common oil inlet pipeline and a common oil return pipeline that are both communicated with the upper mounting valve group and the outrigger valve group. A proportional flow valve is connected to the common oil inlet pipeline. The hydraulic system further includes a pilot-operated logic valve connected in parallel with the proportional flow valve. The oil inlet of the pilot-operated logic valve is communicated with the common oil inlet pipeline, the oil outlet is communicated with the common oil return pipeline, and the pilot port is communicated with the oil outlet of the proportional flow valve.

[0019] As a further improvement, a pressure-limiting oil pipeline is connected in parallel between the outlet of the proportional flow valve and the common oil return pipeline, and a relief valve is provided on the pressure-limiting oil pipeline.

[0020] As a further improvement, a first damping is provided on the pressure-limiting oil pipeline, and the first damping is located upstream of the relief valve.

[0021] As a further improvement, a second damping is further provided between the pilot port of the pilot-operated logic valve and the oil outlet of the proportional flow valve.

[0022] As a further improvement, a check valve is further provided on the common oil inlet pipeline, and the check valve is located downstream of the proportional flow valve.

[0023] As a further improvement, the hydraulic system further includes a rotary joint, and the upper mounting valve group is communicated with the common oil inlet pipeline and the common oil return pipeline through the rotary joint.

[0024] As a further improvement, the proportional flow valve has an oil return port, and the oil return port is communicated with the common oil return pipeline.

[0025] As a further improvement, the hydraulic system further includes a manual pump which is communicated with the common oil inlet pipeline.

[0026] As a further improvement, the hydraulic control logic valve is a normally-closed two-position two-way change-over valve.

[0027] The beneficial effects are as follows: The utility model belongs to an improved invention. Specifically, there is a proportional flow valve in the common oil inlet pipeline, and the opening degree of the valve port of the proportional flow valve can be adjusted to adjust the oil volume of the common oil inlet pipeline, so as to realize the proportional speed regulation of all actions of the outriggers and the upper mounting system. Different from the prior art, a hydraulic control logic valve is added to the hydraulic system. The oil inlet and oil outlet of the hydraulic control logic valve are respectively communicated with the common oil inlet pipeline and the common oil return pipeline, the hydraulic control port is communicated with the oil outlet of the proportional flow valve, and the hydraulic control logic valve is connected in parallel with the proportional flow valve, which ensures that the pressure difference between the two ends of the oil inlet and oil outlet of the proportional flow valve is constant. According to the throttling orifice pressure difference flow formula, the hydraulic oil flowing out of the oil outlet of the proportional flow valve is only related to the opening degree of the valve port of the proportional flow valve and is not affected by the change of the external load, so as to realize the uniform speed control of the outriggers and the upper mounting actions and improve the system stability. Moreover, the utility model does not need to separately configure control valves for the upper mounting and the outriggers, and the hydraulic system has a simple structure and is easy to control the cost. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the principle of the hydraulic system embodiment of the aerial work platform in the utility model.

[0029] Description of the Reference Numerals

[0030] 1. Proportional flow valve; 2. Second damper; 3. Hydraulic control logic valve; 4. First damper; 5. Relief valve; 6. Check valve; 7. Manual pump; 8. Outrigger valve group; 9. Rotary joint; 10. Upper mounting valve group; 100. Common oil inlet pipeline; 200. Common oil return pipeline; 8.1. First outrigger change-over valve; 8.2. Second outrigger change-over valve; 8.3. Third outrigger change-over valve; 8.4. Fourth outrigger change-over valve; 10.1. First upper mounting change-over valve; 10.2. Second upper mounting change-over valve; 10.3. Third upper mounting change-over valve; 10.4. Fourth upper mounting change-over valve; 10.5. Fifth upper mounting change-over valve; 10.6. Sixth upper mounting change-over valve. Detailed Embodiment

[0031] In order to provide a hydraulic system with low cost and capable of solving the problem of insufficient action stability of the upper mounting and outrigger systems of the aerial work platform, the basic technical concept of the utility model is to add a hydraulic control logic valve connected in parallel with the proportional flow valve on the common oil pipeline, so that the pressure difference between the two ends of the oil inlet and oil outlet of the proportional flow valve is constant and is not affected by the change of the external load, thereby improving the action stability of the upper mounting and outrigger systems.

[0032] The following further describes the present utility model in detail in conjunction with embodiments.

[0033] Specific embodiment of the hydraulic system of the aerial work platform provided by the present utility model:

[0034] The hydraulic system of the aerial work platform provided in this embodiment is applicable to an aerial work platform with an upper mounting system and outrigger system. The upper mounting system includes a turret, an upper arm, a lower arm, an inner arm and other movable components. The actuators for driving the actions of the components include hydraulic motors, hydraulic cylinders, etc. The outrigger system includes four retractable outriggers. The actuators for driving the up and down retraction of each outrigger include hydraulic cylinders. As Figure 1 shown, the actuators of the upper mounting system and the outrigger system share the same hydraulic pump (electric pump) and oil tank. Naturally, the hydraulic system also has a common inlet oil circuit 100 and a common return oil circuit 200. The hydraulic oil in the common inlet oil circuit 100 can enter the valve group for controlling the actions of the actuators of the upper mounting system, namely the upper mounting valve group 10, and the valve group for controlling the actions of the actuators of the outrigger system, namely the outrigger valve group 8, through branch oil circuits. The upper mounting valve group 10 includes six directional control valves, namely the first upper mounting directional control valve 10.1, the second upper mounting directional control valve 10.2, the third upper mounting directional control valve 10.3, the fourth upper mounting directional control valve 10.4, the fifth upper mounting directional control valve 10.5 and the sixth upper mounting directional control valve 10.6; the outrigger valve group 8 includes four directional control valves, namely the first outrigger directional control valve 8.1, the second outrigger directional control valve 8.2, the third outrigger directional control valve 8.3, the fourth outrigger directional control valve 8.4. Each directional control valve controls the oil inlet and outlet states of its corresponding actuator.

[0035] A proportional flow valve 1 is provided on the common inlet oil circuit 100. By adjusting the valve opening size of the proportional flow valve 1, the oil volume of the common inlet oil circuit 100 can be controlled, and further the hydraulic oil volume entering the upper mounting valve group 10 and the outrigger valve group 8 can be adjusted, so as to realize the speed regulation of each actuator of the upper mounting system and the outrigger system. Different from the prior art, the hydraulic system further includes a hydraulic control logic valve 3 connected in parallel with the proportional flow valve 1. The inlet of the hydraulic control logic valve 3 is communicated with the common inlet oil circuit 100, the outlet is communicated with the common return oil circuit 200, and the hydraulic control port is communicated with the outlet of the proportional flow valve 1. In this way, after the proportional flow valve 1 is powered on and opened, the hydraulic oil flowing out of the proportional flow valve 1 can enter the hydraulic control logic valve 3 from the hydraulic control port, so that both ends of the inlet and outlet of the proportional flow valve 1 are communicated with the hydraulic control logic valve 3. Since when the hydraulic control logic valve 3 is dynamically stable, according to the force balance, the pressure difference between both ends of the hydraulic control logic valve 3 corresponds to the spring force of the hydraulic control logic valve 3 itself. Since the influence of the spring deformation on the spring force is small, it can be considered that the spring force is a constant value, so that the pressure difference between the inlet and outlet of the proportional flow valve 1 is constant and not affected by the load change. According to the throttling orifice pressure difference flow formula, when the pressure difference on both sides of the throttling orifice remains unchanged and the fluid medium remains unchanged, the flow rate output by the proportional flow valve 1 is only related to the opening of the throttling orifice and is not affected by the external load change, thus realizing the uniform speed control of the outrigger and the upper mounting actions and improving the system stability. Moreover, since the proportional flow valve 1 is on the common inlet oil circuit 100, adjusting the throttling orifice opening of the proportional flow valve 1 can simultaneously control the flow rate entering the upper mounting system and the hydraulic system, which can simplify the structure of the hydraulic system and control costs.

[0036] Preferably, the hydraulic control logic valve 3 is a normally closed two-position two-way reversing valve. When the proportional solenoid valve is powered off and in the closed state, during standby, the hydraulic oil opens the valve port of the hydraulic control logic valve 3 through the pilot oil circuit of the hydraulic control logic valve 3, and the hydraulic oil is directly communicated with the return oil for unloading. At this time, there is no need to separately set an unloading valve, which further simplifies the structure of the hydraulic system and reduces costs.

[0037] A pressure limiting oil circuit is also connected in parallel between the outlet of the proportional flow valve 1 and the common return oil circuit 200. An overflow valve 5 is provided on the pressure limiting oil circuit. The overflow valve 5 can release the pressure of the hydraulic system to prevent the hydraulic system from overloading. Further, a first damper 4 is provided upstream of the overflow valve 5 on the pressure limiting oil circuit. The first damper 4 can improve the stability of the overflow when the hydraulic system overflows and prevent abnormal noises such as howling caused by the oscillation of the overflow valve 5 spool. In other embodiments, the pressure limiting circuit may not be provided. In this case, a proportional flow valve 1 and a hydraulic pump with higher controllability are selected to ensure the safety of the hydraulic system without overloading. Similarly, setting the first damper 4 can further improve the stability of the system. In other embodiments, the first damper 4 may not be provided upstream of the overflow valve 5.

[0038] A damping is also provided between the hydraulic control port of the hydraulic control logic valve 3 and the oil outlet of the proportional flow valve 1. This damping can be defined as the second damping 2. It is not difficult to understand that the second damping 2 can improve the dynamic stability of the logic valve, reduce vibration, and improve the reliability of the system. Similarly, in other embodiments, if a proportional flow valve 1 with higher controllability is selected, the second damping 2 may no longer be configured separately.

[0039] In addition, a check valve 6 is provided on the common inlet oil circuit 100. Specifically, the check valve 6 is located downstream of the proportional flow valve 1. Setting the check valve 6 can prevent oil from flowing back during the pressure building process of each action and avoid the "nodding phenomenon", further improving the stability of the hydraulic system.

[0040] Since the upper mounting system includes a rotatable turret, in order to avoid the disorderly winding of the hydraulic pipeline when the turret continuously rotates in one direction, preferably, the hydraulic system further includes a rotary joint 9. The upper mounting valve group 10 is connected to the common inlet oil circuit 100 and the common return oil circuit 200 through the rotary joint 9, so that the upper mounting of the hydraulic system can continuously rotate 360 degrees, and each hydraulic pipeline will not be disorderly wound. In other embodiments, if the rotary joint 9 is not used, during actual use, according to the operation requirements, in order to avoid the disorderly winding of the hydraulic pipeline, the rotation direction of the turret can be flexibly adjusted. For example, it can be rotated clockwise by a certain angle first, and the limit of the angle is based on the fact that the pipeline will not be irregularly wound (greater than 180 degrees and less than 360 degrees). On this basis, if it cannot be rotated to the appropriate position, it can be rotated counterclockwise by a certain angle (greater than 180 degrees and less than 360 degrees).

[0041] Furthermore, the proportional flow valve 1 is selected as a proportional flow valve 1 with an oil return port, that is, the proportional flow valve 1 is a three-way valve, and the oil outlet is connected to the common return oil circuit 200. This makes the oil return cavity of the proportional flow valve 1 communicate with the oil outlet of the hydraulic control logic valve 3, avoiding the phenomenon that the hydraulic control port of the hydraulic control logic valve 3 cannot be opened due to pressure buildup, making the hydraulic system more reliable. Of course, in other embodiments, through the actual measurement of the applicant, if the proportional flow valve 1 is a two-way valve without an oil return port, the hydraulic control port can also be opened smoothly. However, in the case of having an oil return port, it can fundamentally solve the possible phenomenon that the hydraulic control port cannot be opened.

[0042] In order to avoid the situation that the aerial work platform cannot move accidentally due to power failure or damage of the electric pump during use, as an emergency solution, the hydraulic system is also equipped with a manual pump 7. The manual pump 7 is connected to the common inlet oil circuit 100 and can be used emergently to send high-pressure oil to each valve group to ensure the normal progress of the operation. In other embodiments, if the manual pump 7 is not configured, in the case of an accidental failure, it can wait until the failure is eliminated before carrying out aerial work.

[0043] Specific embodiments of the aerial work platform in the present utility model:

[0044] The aerial work platform includes a hydraulic system, which is the hydraulic system described in the embodiment of the hydraulic system of the above-mentioned aerial work platform, and will not be specifically described here.

[0045] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative efforts, or make equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A hydraulic system for an aerial work platform, comprising an upper-mounted valve group for controlling the actions of each actuator of the upper-mounted system, a outrigger valve group for controlling the actions of each actuator of the outrigger system, and a common inlet oil circuit and a common return oil circuit that are both connected to the upper-mounted valve group and the outrigger valve group. A proportional flow valve is connected to the common inlet oil circuit. It is characterized in that, The hydraulic system further includes a pilot-operated logic valve connected in parallel with the proportional flow valve. The inlet port of the pilot-operated logic valve is communicated with the common inlet oil circuit, the outlet port is communicated with the common return oil circuit, and the pilot port is communicated with the outlet port of the proportional flow valve.

2. The hydraulic system of the aerial work platform according to claim 1, wherein, A pressure-limiting oil circuit is connected in parallel between the outlet of the proportional flow valve and the common return oil circuit, and a relief valve is provided on the pressure-limiting oil circuit.

3. The hydraulic system of the aerial work platform according to claim 2, characterized in that, A first damper is provided on the pressure-limiting oil circuit, and the first damper is located upstream of the relief valve.

4. The hydraulic system of the aerial work platform according to any one of claims 1-3, characterized in that, A second damper is further provided between the pilot port of the pilot-operated logic valve and the outlet port of the proportional flow valve.

5. The hydraulic system of the aerial work platform according to any one of claims 1-3, characterized in that A check valve is further provided on the common inlet oil circuit, and the check valve is located downstream of the proportional flow valve.

6. The hydraulic system of the aerial work platform according to any one of claims 1-3, characterized in that, The hydraulic system further includes a rotary joint, and the upper-mounted valve group is communicated with the common inlet oil circuit and the common return oil circuit through the rotary joint.

7. The hydraulic system of the aerial work platform according to any one of claims 1-3, characterized in that, The proportional flow valve has a return port, and the return port is communicated with the common return oil circuit.

8. The hydraulic system of the aerial work platform according to any one of claims 1-3, characterized in that, The hydraulic system further includes a manual pump, and the manual pump is communicated with the common inlet oil circuit.

9. The hydraulic system of the aerial work vehicle according to any one of claims 1-3, characterized in that, The pilot-operated logic valve is a normally-closed two-position two-way directional valve.

10. An aerial work platform, comprising a hydraulic system, characterized in that, The hydraulic system is the hydraulic system of the aerial work platform according to any one of claims 1-9.

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