Constant and variable double-pump confluence hydraulic system and engineering machinery comprising same

Abstract

The utility model relates to a constant and variable double-pump confluence hydraulic system, which comprises a working loop, a steering circuit; a metering pump for supplying hydraulic fluid to the working circuit; a variable pump for supplying hydraulic fluid to the steering circuit; and a confluence control device, in which the confluence control device includes a priority valve configured to preferentially supply the hydraulic fluid provided by the variable pump to the steering circuit, the confluence control device comprises a variable pump, a constant displacement pump and a working loop, at least one part of hydraulic fluid provided by the variable pump and the hydraulic fluid provided by the constant displacement pump can be converged, and the converged hydraulic fluid is supplied to the working loop, and the confluence control device is characterized by further comprising an unloading valve which is arranged between the constant displacement pump and the working loop. And a control port for receiving a working pressure signal from the working circuit, and wherein the unloading valve unloads the metering pump when the working pressure signal exceeds a predetermined threshold value. The utility model further relates to engineering machinery comprising the hydraulic system.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulics, and more specifically to a hydraulic system for realizing the confluence of fixed and variable double pumps and an engineering machinery comprising the hydraulic system. Background Art

[0002] The fixed and variable dual pump confluence hydraulic system has been increasingly applied to loaders and other construction machinery. When the construction machinery is working, the excess flow of the steering hydraulic system is provided to the working hydraulic system, thereby improving the working efficiency of the construction machinery.

[0003] The fixed and variable dual pumps can achieve confluence, which is achieved by a special confluence control valve block.

[0004] When the current fixed and variable dual pump confluence hydraulic system is working, the logic valve in the confluence control valve block is fully opened. Regardless of the speed of the action, the variable steering pump will be in the maximum displacement state, and its function is the same as that of the fixed displacement pump, and the purpose of energy saving cannot be achieved.

[0005] The utility model aims to solve at least one of the above problems and other problems in the prior art. Utility Model Content

[0006] According to one aspect of the utility model, a fixed and variable dual pump confluence hydraulic system is provided, the hydraulic system comprising:

[0007] Working circuit;

[0008] Steering circuit;

[0009] a metering pump for supplying hydraulic fluid to the working circuit;

[0010] a variable displacement pump for supplying hydraulic fluid to the steering circuit; and

[0011] Confluence control device,

[0012] The merging control device includes a priority valve, which is configured to preferentially supply the hydraulic fluid provided by the variable displacement pump to the steering circuit, and to enable at least a portion of the hydraulic fluid provided by the variable displacement pump to merge with the hydraulic fluid provided by the fixed displacement pump and supply the merged hydraulic fluid to the working circuit.

[0013] It is characterized in that

[0014] The confluence control device also includes a relief valve, which is arranged between the metering pump and the working circuit and includes a control port for receiving a working pressure signal from the working circuit, wherein when the working pressure signal exceeds a predetermined threshold, the relief valve unloads the metering pump.

[0015] Advantageously, the confluence control device further comprises a shuttle valve, a first input port of the shuttle valve being used to receive the working pressure signal, a second input port being used to receive a steering pressure signal from a steering circuit, and an output port being used to transmit an output signal to a control valve of a variable pump.

[0016] Advantageously, the working circuit comprises a closed-center working valve, and the closed-center working valve is used to output the working pressure signal.

[0017] Advantageously, the fixed and variable dual pump combined flow hydraulic system further comprises a pilot control circuit, wherein the pilot control circuit is configured to output a pilot pressure signal to the working circuit to control the operation of the working circuit.

[0018] Advantageously, the confluence control device further comprises a pressure reducing valve, an oil inlet of the pressure reducing valve is fluidically connected to the variable pump, and an oil outlet of the pressure reducing valve is fluidically connected to the pilot control circuit.

[0019] Advantageously, when the working pressure signal is less than or equal to the predetermined threshold value, hydraulic fluid from the metering pump is supplied to the working circuit via the unloading valve.

[0020] Advantageously, the priority valve, the unloading valve and the shuttle valve are integrated into one valve block.

[0021] According to another aspect of the utility model, a construction machine including the hydraulic system is provided.

[0022] Advantageously, the construction machine is a loader.

[0023] The main advantages of the fixed and variable double pump confluence hydraulic system according to the utility model include:

[0024] (1) With the help of the unloading valve, the metering pump is unloaded or the metering pump provides hydraulic fluid to the working circuit according to the working pressure signal fed back from the working circuit.

[0025] (2) With the help of the shuttle valve, the variable pump outputs flow according to the working pressure signal fed back from the working circuit or the steering pressure signal fed back from the steering circuit.

[0026] (3) With the help of the closed-center working valve of the working circuit, the corresponding working pressure signal is output according to the working demand, and the working pressure signal is fed back to the confluence control device to complete the desired control logic, including the variable pump outputting flow according to demand, the fixed-flow pump unloading, or the fixed-flow pump providing hydraulic fluid to the working circuit.

[0027] (4) The hydraulic system can change the output flow of the variable pump according to the demand of the working circuit for the hydraulic fluid flow, thereby realizing the variable function.

[0028] (5) Through the hydraulic system, the fixed and variable pumps can be merged to improve the working efficiency, and the variable pump 2 can output the displacement according to the demand to achieve the purpose of energy saving.

[0029] (6) In the hydraulic system, the variable pump is the main working pump, and the working hydraulic system is easier to achieve high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be described in more detail below with reference to the schematic drawings. The drawings and corresponding embodiments are for illustrative purposes only and are not intended to limit the present invention. Among them:

[0031] Figure 1 The hydraulic principle diagram of a fixed and variable dual pump confluence hydraulic system according to a preferred embodiment of the utility model is schematically shown.

[0032] List of reference numerals:

[0033] 1 Fixed displacement pump 2 Variable displacement pump

[0034] 3 Confluence control device 4 Pilot control circuit

[0035] 5 Working circuit 6 Steering circuit

[0036] 7 Hydraulic oil tank 8 Priority valve

[0037] 9 Closed center working valve 10 Unloading valve

[0038] 11 Shuttle valve 12 Pressure reducing valve

[0039] 13 Working pressure signal 14 Check valve

[0040] 15 first valve 16 second valve

[0041] 100 Hydraulic system DETAILED DESCRIPTION

[0042] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, many specific details are set forth so that those skilled in the art can more fully understand and implement the present invention. However, it is obvious to those skilled in the art that the implementation of the present invention may not have some of these specific details. In addition, it should be understood that the present invention is not limited to the specific embodiments described. On the contrary, any combination of the features and elements described below may be considered to implement the present invention, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims unless clearly stated in the claims.

[0043] Figure 1The hydraulic principle diagram of a fixed and variable dual pump confluence hydraulic system 100 according to a preferred embodiment of the utility model is schematically shown. The hydraulic system 100 is suitable for engineering machinery such as loaders or other types of machinery with similar working conditions.

[0044] like Figure 1 As shown, the hydraulic system 100 includes a metering pump 1, a variable pump 2, a working circuit 5, a steering circuit 6 and a hydraulic oil tank 7. The metering pump 1 is used to draw hydraulic fluid (hydraulic oil) from the hydraulic oil tank 7 and deliver the hydraulic fluid to the working circuit 5, and the variable pump 2 is used to draw hydraulic fluid from the hydraulic oil tank 7 and deliver the hydraulic fluid to the steering circuit 6.

[0045] The hydraulic system 100 further includes a merging control device 3. Figure 1 In the illustrated embodiment, the confluence control device 3 includes a priority valve 8 , a relief valve 10 and a shuttle valve 11 .

[0046] The priority valve 8 is configured to preferentially supply the hydraulic fluid provided by the variable pump 2 to the steering circuit 6 , and to merge at least a portion of the hydraulic fluid provided by the variable pump 2 with the hydraulic fluid provided by the fixed displacement pump 1 and supply the merged hydraulic fluid to the working circuit 5 .

[0047] The unloading valve 10 is arranged between the metering pump 1 and the working circuit 5, and includes a control port for receiving a working pressure signal 13 from the working circuit 5, wherein when the working pressure signal 13 exceeds a predetermined threshold, the unloading valve 10 unloads the metering pump 1.

[0048] Advantageously, the working circuit 5 includes a closed-center working valve 9, and the working pressure signal 13 is output by the closed-center working valve and fed back to the unloading valve 10. Depending on the size of the working pressure signal 13, the unloading valve 10 can be used to enable the metering pump 1 to provide hydraulic fluid to the working circuit 5 or unload the metering pump 1.

[0049] exist Figure 1 In the illustrated embodiment, the unloading valve 10 comprises a one-way valve 14, a first valve 15 and a second valve 16. The first valve 15 and the second valve 16 are respectively configured as 2 / 2-way valves.

[0050] An oil inlet of the one-way valve 14 is fluidly connected to the metering pump 1 , and an oil outlet of the one-way valve 14 is fluidly connected to the working circuit 5 , so as to deliver the hydraulic fluid from the metering pump 1 to the working circuit 5 .

[0051] The oil inlet of the first valve 15 is fluidly connected to the metering pump 1, and the oil outlet of the first valve 15 is fluidly connected to the hydraulic oil tank 7. The first end of the valve core of the first valve 15 is provided with a control port fluidly connected to the oil outlet of the one-way valve 14, and the second end of the valve core is provided with a first spring and a control port fluidly connected to the oil inlet of the second valve 16. The first spring biases the valve core toward a position where the oil inlet and the oil outlet of the first valve 15 are fluidly disconnected.

[0052] The oil inlet of the second valve 16 is used to receive the working pressure signal 13 from the working circuit 5, and the oil outlet of the second valve 16 is fluidly connected to the hydraulic oil tank 7. The first end of the valve core of the second valve 16 is provided with a second spring (the spring is advantageously adjustable), and the second end of the valve core is provided with a control port fluidly connected to the oil inlet of the second valve 16. The second spring biases the valve core toward a position where the oil inlet and the oil outlet of the second valve 16 are fluidly disconnected.

[0053] According to the utility model, when the working pressure signal 13 from the working circuit 5 is less than or equal to a predetermined threshold value, the oil inlet and oil outlet fluids of the first valve 15 are disconnected, and the hydraulic fluid from the metering pump 1 is supplied to the working circuit 5 via the unloading valve 10 (more specifically, via the one-way valve 14). When the working pressure signal 13 exceeds the predetermined threshold value, the first valve 15 is switched to a position where the oil inlet and oil outlet fluids are connected, and the hydraulic fluid from the metering pump 1 returns to the hydraulic oil tank 7 via the unloading valve 10 (more specifically, via the first valve 15), and the metering pump 1 is unloaded.

[0054] It is understandable that the unloading valve 10 may also adopt any other appropriate structure as long as it can achieve the functions described above, that is, unloading the metering pump 1 or enabling the metering pump 1 to provide hydraulic fluid to the working circuit 5 according to the working pressure signal 13 from the working circuit 5.

[0055] like Figure 1 As shown, the first input port of the shuttle valve 11 is used to receive the working pressure signal 13, the second input port is used to receive the steering pressure signal from the steering circuit 6, and the output port is used to transmit the output signal (i.e., the larger one of the working pressure signal 13 and the steering pressure signal) to the control valve of the variable pump 2 so as to control the output of the variable pump 2.

[0056] The hydraulic system 100 further includes a pilot control circuit 4, which is configured to output a pilot pressure signal to the working circuit 5 to control the operation of the working circuit 5. Advantageously, the pilot control circuit 4 may include one or more pilot valves for outputting the pilot pressure signal to the working circuit 5. The pilot valve is, for example, a control handle or other control device.

[0057] Advantageously, the confluence control device 3 further includes a pressure reducing valve 12, the oil inlet of the pressure reducing valve 12 is fluidly connected to the variable pump 2, and the oil outlet of the pressure reducing valve 12 is fluidly connected to the pilot control circuit 4. The pressure reducing valve 12 reduces the pressure of a portion of the hydraulic fluid from the variable pump 2 and transmits it to the pilot control circuit 4, providing a pilot oil source for the pilot control circuit 4.

[0058] Advantageously, some or all valve elements of the confluence control device 3 can be integrated into one valve block. For example, in one embodiment, the priority valve 8, the unloading valve 10, and the shuttle valve 11 are integrated into one valve block. In another embodiment, the priority valve 8, the unloading valve 10, the shuttle valve 11, and the pressure reducing valve 12 are integrated into one valve block.

[0059] Industrial Applicability

[0060] The hydraulic system 100 according to the present invention is applicable to a variety of engineering machinery (such as excavators, loaders, bulldozers, etc.) or other types of machinery with similar working conditions. The working principle of the hydraulic system 100 is described below using a loader as an example.

[0061] When the loader is only turning, the steering pressure signal of the steering circuit 6 is transmitted to the variable pump 2 through the shuttle valve 11 of the merging control device 3. The variable pump 2 provides a certain flow of hydraulic fluid on demand and supplies the hydraulic fluid to the steering circuit 6 through the priority valve 8 of the merging control device 3 to complete the steering operation.

[0062] When the loader is only working, the working pressure signal 13 of the working circuit 5 is transmitted to the unloading valve 10, and the metering pump 1 is unloaded or the metering pump 1 provides hydraulic fluid to the working circuit 5 according to the size of the working pressure signal 13. At the same time, the variable pump 2 provides a corresponding flow of hydraulic fluid according to the working pressure signal 13, and the hydraulic fluid is provided to the working circuit 5 through the merging control device 3 to achieve merging.

[0063] When the loader is steering and working, the variable pump 2 outputs flow as required according to the working pressure signal or the steering pressure signal. At the same time, the priority valve 8 in the merging control device 3 ensures that the hydraulic fluid provided by the variable pump 2 is supplied to the steering circuit 6 first, and the excess hydraulic fluid is supplied to the working circuit 5 to achieve merging.

[0064] The main advantages of the hydraulic system 100 are as follows:

[0065] (1) With the help of the unloading valve 10, the metering pump 1 is unloaded or the metering pump 1 provides hydraulic fluid to the working circuit according to the working pressure signal fed back from the working circuit.

[0066] (2) With the help of the shuttle valve 11, the variable pump 2 outputs flow as required according to the working pressure signal fed back from the working circuit or the steering pressure signal fed back from the steering circuit.

[0067] (3) With the help of the closed-center working valve 9 of the working circuit, the corresponding working pressure signal is output according to the working requirements, and the working pressure signal is fed back to the confluence control device to complete the desired control logic, including the variable pump 2 outputting the flow as required, the metering pump 1 unloading, or the metering pump 1 providing hydraulic fluid to the working circuit.

[0068] (4) The hydraulic system 100 can change the output flow of the variable pump according to the demand of the working circuit for the hydraulic fluid flow, thereby realizing the variable function.

[0069] (5) Through the hydraulic system 100, the fixed and variable pumps can be merged to improve the working efficiency, and the variable pump 2 can output the displacement according to the demand, thereby achieving the purpose of energy saving.

[0070] (6) In the hydraulic system 100, the variable displacement pump 2 is the main working pump, and the working hydraulic system can more easily achieve high pressure.

[0071] The fixed and variable dual pump confluence hydraulic system of the utility model is described above with the help of specific embodiments. It is obvious to those skilled in the art that various changes and deformations can be made to the hydraulic system of the utility model without departing from the design principles of the utility model. For example, the implementation of the utility model may not include some of the specific features described, and the utility model is not limited to the specific embodiments described, but any combination of the described features and elements can be envisioned. Other embodiments will be obvious to those skilled in the art in combination with consideration of the specification and practice of the disclosed hydraulic system. The description and examples are to be regarded as exemplary only, and the true scope is represented by the appended claims and their equivalents.

Claims

1. A fixed and variable dual pump confluence hydraulic system, comprising: Working circuit (5); Steering circuit (6); a metering pump (1) for supplying hydraulic fluid to the working circuit; a variable displacement pump (2) for supplying hydraulic fluid to the steering circuit; and Confluence control device (3), The merging control device includes a priority valve (8) configured to preferentially supply the hydraulic fluid provided by the variable displacement pump to the steering circuit, and to merge at least a portion of the hydraulic fluid provided by the variable displacement pump with the hydraulic fluid provided by the fixed displacement pump and supply the merged hydraulic fluid to the working circuit. It is characterized in that The confluence control device further comprises an unloading valve (10), which is arranged between the metering pump and the working circuit and comprises a control port for receiving a working pressure signal from the working circuit, wherein when the working pressure signal exceeds a predetermined threshold, the unloading valve unloads the metering pump.

2. The fixed and variable dual pump confluence hydraulic system according to claim 1, characterized in that: The confluence control device further comprises a shuttle valve (11), wherein a first input port of the shuttle valve is used to receive the working pressure signal, a second input port is used to receive a steering pressure signal from a steering circuit, and an output port is used to transmit an output signal to a control valve of a variable pump.

3. The fixed and variable dual pump confluence hydraulic system according to claim 1 or 2, characterized in that: The working circuit comprises a closed-center working valve (9), which is used to output the working pressure signal.

4. The fixed and variable dual pump confluence hydraulic system according to claim 1 or 2, characterized in that: The fixed and variable dual pump confluence hydraulic system further comprises a pilot control circuit (4), which is configured to output a pilot pressure signal to the working circuit to control the operation of the working circuit.

5. The fixed and variable dual pump confluence hydraulic system according to claim 4, characterized in that: The confluence control device further comprises a pressure reducing valve (12), an oil inlet of the pressure reducing valve is fluidically connected to the variable pump, and an oil outlet of the pressure reducing valve is fluidically connected to the pilot control circuit.

6. The fixed and variable dual pump confluence hydraulic system according to claim 1 or 2, characterized in that: When the working pressure signal is less than or equal to the predetermined threshold, the hydraulic fluid from the metering pump is supplied to the working circuit via the unloading valve.

7. The fixed and variable dual pump converging hydraulic system according to claim 2, characterized in that: The priority valve, the unloading valve and the shuttle valve are integrated into one valve block.

8. An engineering machine, characterized in that: The engineering machinery includes a fixed and variable displacement dual pump converging hydraulic system according to any one of claims 1 to 7.

9. The engineering machine according to claim 8, characterized in that: The engineering machine is a loader.

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