Load-sensing mechanical precision control hydraulic system

Abstract

The utility model belongs to engineering machinery technical field discloses a kind of load-sensitive mechanical precision control hydraulic system, machine can be switched by switch to realize normal working condition and precision working condition according to need. Mainly by constant-power load-sensitive plunger pump, LS solenoid valve and load-sensitive main valve are composed. LS solenoid valve is opened and closed by electric signal control. When loader starts, electric signal does not control LS solenoid valve, and each control action of complete machine is normally operated according to design speed;When electric signal control LS solenoid valve opens, constant-power load-sensitive plunger pump is influenced by load pressure rise, and pump flow is reduced, so that each control action of machine is slowed down when heavy load, so as to realize precision control;When precision control is not needed, electric signal does not control LS solenoid valve, and machine can restore normal operation.

Description

Technical Field

[0001] This utility model relates to a load-sensitive hydraulic system for precise control of an excavator loader, belonging to the field of engineering machinery technology. Background Technology

[0002] After the design and trial production of the excavator loader equipped with a negative-sensitive constant-power controlled piston pump are completed, the flow rate and pressure required for each operating action have been adjusted. Therefore, the time of each operating action during the operation of the excavator loader is constant, meeting the requirements of most working conditions. However, some working conditions require the excavator loader to perform precise loading and unloading work. In these cases, since the overall operating action time is fixed, it is impossible to meet the precise adjustment requirements of the working condition. Therefore, there is an urgent need for a load-sensitive precision mechanical control hydraulic system, in which the whole machine can switch between normal working state and precision working state as needed via a switch. Utility Model Content

[0003] The problem this utility model aims to solve is to provide a load-sensitive mechanical precision control hydraulic system that is simple in principle, highly versatile, and widely applicable, thereby addressing the issue that excavators and loaders equipped with a load-sensitive constant power control hydraulic system require different operating speeds under different working conditions.

[0004] To achieve the above objectives, a load-sensitive hydraulic system for precise mechanical control is provided, comprising:

[0005] The plunger pump is a load-sensitive constant power plunger pump with an LS control port;

[0006] The load-sensitive main valve has its LS port connected to the LS control port of the plunger pump.

[0007] The LS solenoid valve has its inlet A connected to the LS port of the load-sensitive main valve, and its outlet B connected to the LS control port of the plunger pump.

[0008] The throttle orifice c is integrated inside the LS solenoid valve and connects the oil inlet A and the oil outlet B of the LS solenoid valve.

[0009] When the LS solenoid valve is de-energized, it is directly open, and PA=PB; when energized, the throttling orifice c is open, and PA>PB.

[0010] In this technical solution, the LS solenoid valve is normally closed. An electrical signal controls the opening and closing of the LS solenoid valve.

[0011] According to this utility model, when the LS solenoid valve is de-energized, the oil inlet A and the oil outlet B are directly connected, and the load pressure signal is transmitted to the plunger pump without attenuation.

[0012] According to this utility model, when the LS solenoid valve is energized, the load pressure signal is attenuated through the throttling orifice c and then transmitted to the plunger pump, thereby reducing the output flow of the plunger pump.

[0013] According to this utility model, the diameter of the throttling orifice c is 0.8mm-1.0mm, and the flow rate is less than that in the normal mode.

[0014] According to this utility model, the load-sensitive main valve is further connected to an oil cylinder.

[0015] According to this utility model, it further includes a hydraulic oil tank, which is connected to a piston pump and a load-sensitive main valve through a hydraulic output pipeline to form a connected oil circuit.

[0016] According to this utility model, the hydraulic oil tank is further connected to the return port T of the load-sensitive main valve through a hydraulic oil circuit, and a radiator is provided on the second hydraulic output pipeline to regulate the temperature of the hydraulic oil returning to the hydraulic oil tank 5.

[0017] When the excavator loader starts, the speed control rocker switch is in the near-closed state, and the LS solenoid valve is in the normally closed state. When the machine is working at the excavating end, all operating actions are optimally controlled without being affected by the LS solenoid valve. When the machine is performing precision operations, the speed control rocker switch should be opened in advance. Under heavy load and precision conditions, the operating actions will slow down, thus smoothly completing the precision operation. When the machine needs normal operation, simply close the speed control rocker switch.

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] This utility model adopts the above-mentioned structure, which has the characteristics of simple structure, good processability, strong versatility and convenient use.

[0020] This invention controls the LS solenoid valve's on / off state via a rocker switch: when de-energized, the LS oil circuit is directly open, and the system is in normal operating mode; when energized, the load signal is attenuated through a throttling orifice and transmitted to the plunger pump, reducing its output flow and switching to precision operating mode. This solves the problem that existing load-sensitive systems cannot adapt to precise adjustment conditions, and has the advantages of one-button switching, simple structure, and strong compatibility. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the load-sensitive mechanical precision control hydraulic system of this utility model.

[0022] In the diagram: 1-plunger pump, 2-LS solenoid valve, 3-load-sensitive main valve, 4-cylinder, 5-oil tank, 51-hydraulic output line, 52-hydraulic oil circuit, 6-radiator, c-throttle orifice. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0024] This utility model provides a load-sensitive hydraulic system for precise mechanical control, mainly equipped on excavators and loaders. It includes a load-sensitive constant-power piston pump 1 and a load-sensitive main valve 3 connected thereto. The LS port of the load-sensitive main valve 3 is connected to the LS control port of the piston pump 1 via a hydraulic pipeline. A hydraulic cylinder 4 is connected to the load-sensitive main valve 3. A hydraulic oil tank 5 is connected to the piston pump 1 and the load-sensitive main valve 3 via a hydraulic output pipeline 51, forming a continuous oil circuit.

[0025] Furthermore, it also includes an LS solenoid valve 2, whose inlet A is connected to the LS port of the load-sensitive main valve 3, and its outlet B is connected to the LS control port of the plunger pump 1; the LS solenoid valve 2 is provided with a throttling orifice c, and the bypass throttling orifice c connects the inlet A and outlet B of the LS solenoid valve 2; it also includes a fast / slow control rocker switch electrically connected to the LS solenoid valve 2 to control the on / off state of the LS solenoid valve 2. The fast / slow control rocker switch is an existing component and will not be described in detail here.

[0026] Specifically, the LS solenoid valve 2 is a two-position two-way valve. When de-energized, it is directly open (PA=PB), and when energized, the throttling orifice c is open (PA>PB). In the de-energized state, the LS solenoid valve 2 allows direct connection between its inlet A and outlet B, ensuring the load pressure signal is transmitted to the plunger pump 1 without attenuation. In the energized state, the load pressure signal is attenuated by the throttling orifice c before being transmitted to the plunger pump 1, thus reducing the output flow of the plunger pump 1. Preferably, the orifice c has a diameter of 0.8 mm - 1.0 mm to ensure linear flow attenuation, making the flow rate in precision operation mode 60%-80% of the normal mode.

[0027] In this embodiment, the hydraulic oil tank 5 is connected to the return port T of the load-sensitive main valve 3 via the hydraulic oil circuit 52, and a radiator 6 is provided on the second hydraulic output pipeline 52 to regulate the temperature of the hydraulic oil returning to the hydraulic oil tank 5.

[0028] The working principle of this utility model is as follows: After the excavator loader is started, when the electromagnet of the LS solenoid valve 2 is de-energized, the load-sensitive main valve 3 is operated. The load signal is transmitted through its LS port to the inlet A of the LS solenoid valve 2, and through the outlet B of the LS solenoid valve 2 to the LS control port of the load-sensitive constant-power piston pump 1, thereby controlling the opening size of the pump swashplate. In this state, the pressure PA at the inlet A and outlet B of the LS solenoid valve 2 is equal to PB, and the LS solenoid valve 2 has virtually no impact on the hydraulic system.

[0029] When the excavator loader requires precise operation after startup, the electromagnet of LS solenoid valve 2 is energized, and LS solenoid valve 2 is in a switching state. When the load-sensitive main valve 3 is operated, the load signal is transmitted to the inlet A of LS solenoid valve 2 through its LS port. Because LS solenoid valve 2 is in the valve core a position, the load signal at the inlet A of LS solenoid valve 2 is transmitted to the outlet B through the throttle orifice c of LS solenoid valve 2. The outlet B of LS solenoid valve 2 then transmits the signal to the LS control port of the load-sensitive constant power plunger pump 1, thereby controlling the opening size of the pump swashplate. In this state, because the hydraulic oil flows out from the outlet B through the throttle orifice c via the inlet A, the pressure PA at the inlet A and outlet B of LS solenoid valve 2 is greater than PB. Because plunger pump 1 is a constant power load-sensitive variable pump, when plunger pump 1 detects a falsely high pressure PB, which is higher than the normal state, the swashplate angle decreases. According to the principle that the flow rate decreases as the pressure increases, the constant power pump controls the plunger pump 1 power control cylinder 4 to reduce the pump swashplate angle, thereby reducing the flow rate supplied by plunger pump 1 to the load-sensitive main valve 3, thus achieving precise control.

[0030] To ensure the excavator loader can operate normally after startup, the electromagnet of LS solenoid valve 2 should be de-energized.

[0031] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A load-sensitive hydraulic system for precise mechanical control, characterized in that, include: The plunger pump is a load-sensitive constant power plunger pump with an LS control port; The load-sensitive main valve has its LS port connected to the LS control port of the piston pump via a hydraulic line. The LS solenoid valve has its inlet A connected to the LS port of the load-sensitive main valve, and its outlet B connected to the LS control port of the plunger pump. The throttle orifice c is integrated inside the LS solenoid valve and connects the oil inlet A and the oil outlet B of the LS solenoid valve. When the LS solenoid valve is de-energized, it is directly open, and PA=PB; when energized, the throttling orifice c is open, and PA>PB.

2. The load-sensitive mechanical precision control hydraulic system as described in claim 1, characterized in that: When the LS solenoid valve is de-energized, the oil inlet A and oil outlet B are directly connected, and the load pressure signal is transmitted to the plunger pump without attenuation.

3. The load-sensitive mechanical precision control hydraulic system as described in claim 1, characterized in that: When the LS solenoid valve is energized, the load pressure signal is attenuated through the throttling orifice c and then transmitted to the plunger pump, resulting in a decrease in the output flow of the plunger pump.

4. The load-sensitive mechanical precision control hydraulic system as described in claim 1, characterized in that, The diameter of the throttling orifice c is 0.8mm-1.0mm, and the flow rate is less than that in normal mode.

5. The load-sensitive mechanical precision control hydraulic system as described in claim 1, characterized in that, The load-sensitive main valve is connected to a hydraulic cylinder.

6. The load-sensitive mechanical precision control hydraulic system as described in claim 5, characterized in that, It also includes a hydraulic oil tank, which is connected to a piston pump and a load-sensitive main valve through a hydraulic output pipeline to form a connected oil circuit.

7. The load-sensitive mechanical precision control hydraulic system as described in claim 6, characterized in that, The hydraulic oil tank is connected to the return port T of the load-sensitive main valve via a hydraulic oil circuit. A radiator is installed on the second hydraulic output pipeline to regulate the temperature of the hydraulic oil returning to the hydraulic oil tank.

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