Digital hydraulic pump

Abstract

The present application relates to the technical field of hydraulic pressure, more particularly, to a kind of digital hydraulic pump, including digital pump, the high pressure port of the digital pump is connected with flow regulating unit, the flow regulating unit includes adjustable flow valve I, fixed displacement pump, unloading overflow valve and at least one energy accumulator, adjustable flow valve IA port is communicated with the high pressure port of digital pump, adjustable flow valve IB port is communicated with the liquid inlet of energy accumulator, and the fixed displacement pump is communicated with energy accumulator by unloading overflow valve.The present application is combined by multiple fixed displacement pumps and valve-controlled flow regulating unit, on the one hand, the flow regulating response speed of digital pump is guaranteed when larger flow, on the other hand, the flow regulating accuracy of digital pump is guaranteed when small flow, the pressure impact caused by the mismatch of pump control and valve control is reduced, compared with existing variable displacement plunger pump, the regulating speed is faster, the overall response speed and accuracy of hydraulic system are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of hydraulic technology, and more specifically, to a digital hydraulic pump. Background Technology

[0002] A multi-pump digitally controlled pump, or simply a digital pump, is a combination of multiple fixed displacement pumps, each controlled by a solenoid valve. This multi-pump system, controlled digitally by a microcomputer, can output different flow rates. Statistical data shows that while swashplate or swashplate variable displacement piston pumps are generally highly efficient, their cost becomes very high for large flow rates, and their operating noise is also higher than that of multi-pump digitally controlled pumps.

[0003] With the development of microcomputer and sensor technology, the operating conditions of hydraulic systems can be monitored in real time. After the monitoring signals are processed by the microcomputer, the solenoid valves are digitally controlled so that the multi-pump digital control pumps can output reasonable flow rates. Therefore, this type of digital pump is being used more and more.

[0004] Related research has found that multi-pump digitally controlled pumps exhibit fast flow regulation speeds at higher flow rates, effectively adapting to the instantaneous flow demands of actuators. However, at lower flow rates, flow fluctuations are significant, and both flow and pressure characteristics are relatively poor. Researchers combined multiple fixed-displacement pumps with a small-displacement variable-displacement pump, using a microcomputer to output command signals, achieving a complementary effect. This improved the flow regulation response speed of the digital pump at higher flow rates and enhanced its flow regulation accuracy at lower flow rates. However, experimental results show that the response speed of the small-displacement variable-displacement pump is still lower than that of the valve-controlled pump.

[0005] Therefore, it is necessary to improve existing technologies. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, a new digital hydraulic pump is provided, which combines multiple fixed displacement pumps with a valve-controlled flow regulation unit. On the one hand, it improves the flow regulation response speed of the digital pump at larger flow rates, and on the other hand, it improves the flow regulation accuracy of the digital pump at smaller flow rates. This is of great significance for improving the performance of hydraulic equipment and saving energy and reducing emissions.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A digital hydraulic pump includes a digital pump, wherein a flow regulating unit is connected to the high-pressure port of the digital pump, the flow regulating unit includes a flow control valve, a constant displacement pump, at least one accumulator and an unloading assembly, the A port of the flow control valve is connected to the high-pressure port of the digital pump, the B port of the flow control valve is connected to the inlet of the accumulator, and the constant displacement pump is connected to the accumulator through the unloading assembly.

[0009] Furthermore, the flow control valve is an adjustable flow valve I or a high-speed switching valve; the unloading assembly is a combination of a one-way valve I, a relief valve, and a two-way valve I, or an unloading relief valve.

[0010] To improve the adjustment range of the flow regulation unit, a three-way valve I is provided between the flow control valve and the accumulator. The confluence port of the three-way valve I is connected to the port of the adjustable flow valve IB, and the two branch ports of the three-way valve I are connected to the accumulator and the low-pressure oil source, respectively.

[0011] When a digital pump has one or more high-pressure ports or two digital pumps are used in parallel, in order to adjust the flow rate of different high-pressure ports, a three-way valve II is provided between the adjustable flow valve I and the digital pump. The confluence port of the three-way valve II is connected to port A of the flow control valve, and the two branch ports of the three-way valve II are respectively connected to different high-pressure ports of the digital pump.

[0012] To improve the regulation capability of the flow regulation unit, two accumulators are provided. The two accumulators are connected to different branch ports of the same three-way valve III. The confluence port of the three-way valve III is connected to the high-pressure port and unloading assembly of the digital pump.

[0013] Preferably, a pressure sensor is connected to the high-pressure port of the three-way valve III.

[0014] Preferably, the oil outlet of the constant displacement pump is connected to port A of a two-way valve I, and port B of the two-way valve I is connected to a low-pressure oil source.

[0015] Preferably, the digital pump includes at least three constant displacement suction and discharge oil units, each of which is connected to the same prime mover. The oil outlet of each constant displacement suction and discharge oil unit is connected in parallel to a one-way valve II and a two-way valve II. Port A of the two-way valve II is connected to the constant displacement suction and discharge oil unit, and port B of the two-way valve II is connected to a low-pressure oil source.

[0016] The oil inlet of check valve II is connected to the oil outlet of the fixed displacement suction and discharge unit, and the oil outlet of check valve II is connected to the high pressure port of the digital pump.

[0017] Furthermore, the high-pressure port of the digital pump is equipped with a pressure sensor.

[0018] The beneficial effects of this invention compared to the prior art are as follows:

[0019] 1. This invention combines multiple fixed displacement pumps with valve-controlled flow regulation units, which on the one hand ensures the flow regulation response speed of the digital pump at large flow rates, and on the other hand ensures the flow regulation accuracy of the digital pump at small flow rates. It reduces the pressure shock caused by the mismatch between pump control and valve control. Compared with existing variable displacement piston pumps, the regulation speed is faster, which greatly improves the overall response speed and accuracy of the hydraulic system.

[0020] 2. By setting a three-way valve II, the present invention can regulate the flow rate of a single-pump hydraulic pump with multiple high-pressure ports, and can also regulate the flow rate of a dual-pump system.

[0021] 3. By setting a three-way valve III, the present invention can connect two accumulators with different performance to achieve multi-stage regulation of flow rate. Attached Figure Description

[0022] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Figure 1 A schematic diagram of a flow regulation unit;

[0024] Figure 2 This is a schematic diagram of the structure of Example 1;

[0025] Figure 3 This is a schematic diagram of the structure of Example 2;

[0026] Figure 4 for Figure 3 Schematic diagram of the medium flow rate regulating unit;

[0027] Figure 5 This is a schematic diagram of another structure for the flow regulation unit;

[0028] Figure 6 This is a schematic diagram of the structure of Example 3;

[0029] Figure 7 This is a schematic diagram of the structure of Example 4;

[0030] Figure 8 for Figure 7 A schematic diagram of the flow rate regulation unit.

[0031] In the diagram: 1-Digital pump, 1.1-Constant displacement suction and discharge unit, 1.2-Check valve II, 1.3-Two-way valve II, 1.4-Adjustable flow valve II, 2-Flow regulating unit, 2.1-Adjustable flow valve I, 2.2-Constant displacement pump, 2.3-Unloading relief valve, 2.31-Check valve I, 2.32-Relief valve, 2.33-Two-way valve I, 2.4-Accumulator, 2.5-Three-way valve I, 2.6-Three-way valve II, 2.7-Three-way valve III, 2.8-Pressure sensor, 3-Low-pressure oil source, 4-Prime mover, 5-Hydraulic cylinder. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1:

[0034] like Figures 1 to 2 As shown, a digital hydraulic pump includes a digital pump 1. The high-pressure port of the digital pump 1 is connected to a flow regulating unit 2. The flow regulating unit 2 includes a flow control valve, a constant displacement pump 2.2, an unloading assembly, and an accumulator 2.4. The flow control valve is an adjustable flow valve I 2.1 or a high-speed switching valve. In this embodiment, an adjustable flow valve I is used. The unloading assembly is an unloading relief valve 2.3 or a combination of a check valve 2.31, a relief valve 2.32, and a two-way valve I 2.33. In this embodiment, an unloading relief valve is used.

[0035] Port A of the adjustable flow valve I2.1 is connected to the high-pressure port of the digital pump 1. A three-way valve I2.5 is installed between the adjustable flow valve I2.1 and the accumulator 2.4. The confluence port of the three-way valve I2.5 is connected to the B port of the adjustable flow valve I2.1. The two branch ports of the three-way valve I2.5 are connected to the accumulator 2.4 and the low-pressure oil source 3, respectively. The constant displacement pump 2.2 is connected to the accumulator 2.4 through the unloading overflow valve 2.3.

[0036] The flow rate into and out of the accumulator 2.4 is controlled by the adjustable flow valve I2.1, and the hydraulic oil from the high-pressure port of the digital pump 1 is controlled by the three-way valve I2.5 to enter the accumulator or discharge into the low-pressure oil source, thus achieving a wider range of flow rate regulation.

[0037] The digital pump 1 can be an existing digital pump or a digital pump disclosed in this embodiment.

[0038] A digital pump includes at least three constant displacement suction and discharge oil units 1.1. Each constant displacement suction and discharge oil unit 1.1 is connected to the same prime mover 4, which drives the oil units 1.1. A one-way valve II 1.2 and a two-way valve II 1.3 are connected in parallel to the oil outlet of each constant displacement suction and discharge oil unit 1.1. Port A of the two-way valve II 1.3 is connected to the constant displacement suction and discharge oil unit 1.1, and port B of the two-way valve II 1.3 is connected to a low-pressure oil source 3. The oil inlet of the one-way valve II 1.2 is connected to the oil outlet of the constant displacement suction and discharge oil unit 1.1, and the oil outlet of the one-way valve II 1.2 is connected to the high-pressure port of the digital pump 1. A pressure sensor is installed at the high-pressure port of the digital pump 1.

[0039] When the hydraulic system is not in operation, the flow rate of the constant displacement pump 2.2 in the flow regulation unit 2 flows back to the low-pressure oil source through the unloading relief valve 2.3. When the hydraulic system is in operation, according to the flow rate required by the hydraulic cylinder 5, the digital pump 1 controls multiple two-way valves II 1.3. When the working pressure is less than 1 / 2 of the rated working pressure, the flow rate output by the digital pump 1 is slightly greater than the flow rate required by the hydraulic cylinder 5. The difference in flow rate between the digital pump 1 and the digital cylinder 5 is discharged back to the low-pressure oil source 3 through the adjustable flow valve I 2.1 in the flow regulation unit 2, so that the output flow rate of the digital pump 1 is equal to the required flow rate of the hydraulic cylinder 5, and the hydraulic cylinder 5 outputs at a predetermined speed. When the working pressure is greater than 1 / 2 of the rated working pressure, the flow rate output by the digital pump 1 is slightly less than the required flow rate of the hydraulic cylinder 5. The flow rate from the accumulator and the constant displacement pump 2.2 is supplemented to the digital pump 1 through the adjustable flow valve I 2.1 in the flow regulation unit 2, so that the output flow rate of the digital pump 1 is equal to the required flow rate of the hydraulic cylinder 5, and the hydraulic cylinder 5 outputs at a predetermined speed.

[0040] Example 2:

[0041] like Figure 3 , Figure 4 As shown, based on Example 1, when there are two digital pumps 1 and the high-pressure ports of the two digital pumps are respectively connected to hydraulic cylinders, in order to adjust the flow rate of the two high-pressure ports, a three-way valve II 2.6 is provided between the adjustable flow valve I 2.1 and the digital pump 1, based on Example 1. The confluence port of the three-way valve II 2.6 is connected to the A port of the adjustable flow valve I 2.1, and the two branch ports of the three-way valve II 2.6 are respectively connected to the high-pressure ports of the two digital pumps 1.

[0042] By setting a three-way valve II2.6, the flow rate regulation of the dual digital pumps can be achieved by a single flow rate regulation unit.

[0043] When the hydraulic system is not working, the flow rate of the pump in the flow control unit flows back to the low-pressure oil source through the unloading relief valve.

[0044] Two digital pumps, designated as pump #1 and pump #2, are configured. When the hydraulic system is operating, if the working pressure of pump #1 is greater than or equal to (or less than) the working pressure of pump #2, the adjustable flow valve I 2.1 is opened, switching the oil circuit of the three-way valve II 2.6 to pump #1 (or pump #2). When the maximum working pressure of digital pump 1 is less than half of its rated working pressure, based on the required flow values ​​of the two hydraulic cylinders 5, pumps #1 and #2 control multiple two-way valves to ensure that the sum of the output flow of pumps #1 and #2 is slightly greater than the required flow values ​​of hydraulic cylinders 1 and 2. The difference in flow between pumps #1 and #2 and digital cylinders 1 and 2 is returned to the low-pressure oil source through the adjustable flow valve I 2.1 in the flow regulation unit 2, making the output flow of pumps #1 and #2 equal to the required flow of hydraulic cylinders 1 and 2. Finally, the adjustable flow valve II 1.4 causes hydraulic cylinders 1 and 2 to output at a predetermined speed.

[0045] When the maximum working pressure of the digital pump is greater than or equal to 1 / 2 of the rated working pressure, the sum of the flow rates output by pumps #1 and #2 is slightly less than the flow rates required by hydraulic cylinders 1 and 2, according to the required flow rates of hydraulic cylinders 1 and 2. The flow rate of accumulator 2.4 and constant displacement pump 2.2 is supplemented to the digital pump through the adjustable flow valve I 2.1 in the flow regulation unit 2, so that the output flow rate of pumps #1 and #2 is equal to the required flow rate of hydraulic cylinders 1 and 2. The hydraulic cylinders 1 and 2 are then output at a predetermined speed through the adjustable flow valve II 1.4.

[0046] Example 3:

[0047] like Figure 5 , Figure 6 As shown, a digital hydraulic pump includes a digital pump 1. The high-pressure port of the digital pump 1 is connected to a flow regulating unit 2. The flow regulating unit 2 includes a flow control valve, a constant displacement pump 2.2, an unloading assembly, and two accumulators 2.4. The flow control valve is an adjustable flow valve I 2.1. The unloading assembly is a combination of a check valve 2.31, a relief valve 2.32, and a two-way valve I 2.33. The oil inlets of the check valve 2.31, relief valve 2.32, and two-way valve I 2.33 are connected. The oil outlets of the relief valve 2.32 and two-way valve I 2.33 are connected to a low-pressure oil source. The oil outlet of the check valve 2.31 is connected to the two accumulators through a three-way valve III 2.7. The two accumulators are of different specifications, with the first accumulator being smaller than the second. Both accumulators 2.4 are connected to different ports of the same three-way valve Ⅲ 2.7. The confluence port of three-way valve Ⅲ 2.7 is connected to three-way valve Ⅰ 2.5. Three-way valve Ⅲ 2.7 is connected to a pressure sensor 2.8, which monitors the oil pressure.

[0048] Port A of the adjustable flow valve I2.1 is connected to the high-pressure port of the digital pump 1. A three-way valve I2.5 is installed between the adjustable flow valve I2.1 and the accumulator 2.4. The confluence port of the three-way valve I2.5 is connected to the B port of the adjustable flow valve I2.1. The two branch ports of the three-way valve I2.5 are connected to the accumulator 2.4 and the low-pressure oil source 3, respectively.

[0049] When the hydraulic system is not in operation, the flow rate of the pump in the flow regulating unit 2 flows back to the low-pressure oil source through the unloading assembly. When the hydraulic system is in operation, according to the required flow rate of the hydraulic cylinder, the digital pump 1 controls multiple two-way valves II1.3. When the working pressure is less than 1 / 3 of the rated working pressure, the flow rate output by the digital pump 1 is slightly greater than the required flow rate of the hydraulic cylinder 5. The difference in flow rate between the digital pump 1 and the digital cylinder 5 is discharged back to the low-pressure oil source through the adjustable flow valve I2.1 in the flow regulating unit 2, so that the output flow rate of the digital pump 1 is equal to the required flow rate of the hydraulic cylinder 5, and the hydraulic cylinder outputs at a predetermined speed.

[0050] When the working pressure is greater than 1 / 3 and less than 2 / 3 of the rated working pressure, the flow rate output by digital pump 1 is slightly less than the flow rate required by hydraulic cylinder 5. The flow rate of the first accumulator and the constant displacement pump 2.2 is supplemented to digital pump 1 through the adjustable flow valve I 2.1 in flow regulating unit 2, so that the output flow rate of digital pump 1 is equal to the flow rate required by hydraulic cylinder 5, and hydraulic cylinder outputs at a predetermined speed.

[0051] When the working pressure is greater than 2 / 3 of the rated working pressure, the flow rate output by digital pump 1 is slightly less than the flow rate required by hydraulic cylinder 5. The flow rate of the second accumulator and constant displacement pump 2.2 is supplemented to digital pump 1 through the adjustable flow valve I 2.1 in flow regulation unit 2, so that the output flow rate of digital pump 1 is equal to the flow rate required by hydraulic cylinder 5, and hydraulic cylinder 5 outputs at a predetermined speed.

[0052] Example 4:

[0053] like Figure 7 , Figure 8 As shown, based on the digital hydraulic pump disclosed in Embodiment 3, when the digital pump includes pump #1 and pump #2 arranged in parallel, a three-way valve II 2.6 is provided between the adjustable flow valve I 2.1 and the digital pump 1. The confluence port of the three-way valve II 2.6 is connected to port A of the adjustable flow valve I 2.1, and the two branch ports of the three-way valve II 2.6 are connected to the high-pressure ports of pump #1 and pump #2, respectively. The flow rate of pump #1 or pump #2 is adjusted by the flow rate adjustment unit controlled by the three-way valve II 2.6.

[0054] When the hydraulic system is not working, the flow rate of the pump in the flow control unit flows back to the low-pressure oil source through the two-way valve I2.33.

[0055] When the hydraulic system is working, if the working pressure of pump #1 is greater than or equal to (or less than) the working pressure of pump #2, the adjustable flow valve I 2.1 will be opened, and the oil circuit of the three-way valve II 2.6 will be switched to pump #1 (or pump #2). When the maximum working pressure of the digital pump is less than 1 / 3 of the rated working pressure, according to the required flow values ​​of hydraulic cylinders 1 and 2, the digital pump controls multiple two-way valves to make the sum of the output flow of pumps #1 and #2 slightly greater than the required flow values ​​of hydraulic cylinders 1 and 2. The difference in flow between pumps #1 and #2 and digital cylinders 1 and 2 is returned to the low-pressure oil source through the adjustable flow valve I 2.1 in the flow regulation unit 2, so that the output flow of digital pumps 1 and 2 is equal to the required flow of hydraulic cylinders 1 and 2. The adjustable flow valve II 1.4 makes hydraulic cylinders 1 and 2 output at a predetermined speed.

[0056] When the maximum working pressure of the digital pump is greater than 1 / 3 of the rated working pressure but less than 2 / 3 of the rated working pressure, the sum of the output flow of pumps #1 and #2 is made slightly less than the required flow of hydraulic cylinders 1 and 2 according to the required flow values ​​of hydraulic cylinders 1 and 2. Based on the flow difference between the digital pump and the digital cylinder, the flow of the first accumulator and the constant displacement pump 2.2 is supplemented to the digital pump through the adjustable flow valve I 2.1 in the flow regulation unit 2, so that the output flow of pumps #1 and #2 is equal to the required flow of hydraulic cylinders 1 and 2. The hydraulic cylinders 1 and 2 are made to output at a predetermined speed through the adjustable flow valve II 1.4.

[0057] When the maximum working pressure of the digital pump is greater than 2 / 3 of the rated working pressure, the sum of the output flow of pumps #1 and #2 is made slightly less than the required flow of hydraulic cylinders 1 and 2 according to the required flow values ​​of hydraulic cylinders 1 and 2. Based on the flow difference between the digital pump and the digital cylinder, the flow of the second accumulator and the constant displacement pump is supplemented to the digital pump through the adjustable flow valve I2.1 in the flow regulation unit 2, so that the output flow of pumps #1 and #2 is equal to the required flow of hydraulic cylinders 1 and 2. The hydraulic cylinders 1 and 2 are made to output at a predetermined speed through the adjustable flow valve II1.4.

[0058] The above description only illustrates the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention, and all such changes should be included within the protection scope of the present invention.

Claims

1. A digital hydraulic pump, comprising a digital pump (1), characterized in that: The high-pressure port of the digital pump (1) is connected to a flow regulating unit (2). The flow regulating unit (2) includes a flow control valve, a constant displacement pump (2.2), at least one accumulator (2.4), and an unloading assembly. The A port of the flow control valve is connected to the high-pressure port of the digital pump (1), and the B port of the flow control valve is connected to the inlet of the accumulator (2.4). The constant displacement pump (2.2) is connected to the accumulator (2.4) through the unloading assembly. The flow control valve is an adjustable flow valve I (2.1). A three-way valve I (2.5) is provided between the flow control valve and the accumulator (2.4). The confluence port of the three-way valve I (2.5) is connected to the B port of the adjustable flow valve I (2.1), and the two branch ports of the three-way valve I (2.5) are connected to the accumulator (2.4) and the low-pressure oil source (3) respectively. A three-way valve II (2.6) is provided between the adjustable flow valve I (2.1) and the digital pump (1). The confluence port of the three-way valve II (2.6) is connected to the A port of the flow control valve, and the two branch ports of the three-way valve II (2.6) are respectively connected to different high-pressure ports of the digital pump (1).

2. A digital hydraulic pump according to claim 1, characterized in that: The unloading assembly is a combination of one-way valve I (2.31), overflow valve (2.32), and two-way valve I (2.33).

3. A digital hydraulic pump according to claim 1, characterized in that: The unloading assembly is an unloading overflow valve (2.3).

4. A digital hydraulic pump according to claim 1, characterized in that: There are two accumulators (2.4), and the two accumulators (2.4) are connected to different branches of the same three-way valve III (2.7). The confluence of the three-way valve III (2.7) is connected to the three-way valve I (2.5) and the unloading assembly.

5. A digital hydraulic pump according to claim 4, characterized in that: The high-pressure port of the three-way valve III (2.7) is connected to a pressure sensor (2.8).

6. A digital hydraulic pump according to claim 1, characterized in that: The digital pump (1) includes at least three constant displacement suction and discharge oil units (1.1). Each constant displacement suction and discharge oil unit (1.1) is connected to the same prime mover (4). The oil outlet of each constant displacement suction and discharge oil unit (1.1) is connected in parallel with a one-way valve II (1.2) and a two-way valve II (1.3). The A port of the two-way valve II (1.3) is connected to the constant displacement suction and discharge oil unit (1.1), and the B port of the two-way valve II (1.3) is connected to the low-pressure oil source (3). The inlet of check valve II (1.2) is connected to the outlet of the fixed displacement suction and discharge unit (1.1), and the outlet of check valve II (1.2) is connected to the high pressure port of digital pump (1).

7. A digital hydraulic pump according to claim 6, characterized in that: The high-pressure port of the digital pump (1) is equipped with a pressure sensor.

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