High variable response closed-loop hydraulic piston pump and its usage method

Abstract

This invention discloses a closed-loop hydraulic piston pump with high variable response speed and its usage method. The variable system of the piston pump consists of a control valve and a variable mechanism. The variable mechanism includes a variable cylinder (10), a variable piston (11) is provided inside the variable cylinder (10), the middle part of the variable piston (11) is connected to the swashplate (40) of the piston pump, and both ends of the variable piston (11) form variable chambers (12). Both ends of the variable piston (11) are provided with copper rings (13), which are located between the variable piston (11) and the variable cylinder (10). The variable cylinder (10) supports and seals the variable piston (11) through the copper rings (13), and the copper rings (13) are clearance-fitted with the variable piston (11). This invention has the advantage of fast variable response speed.

Description

Technical Field

[0001] This invention belongs to the field of closed-loop hydraulic piston pumps, and particularly relates to a closed-loop hydraulic piston pump with high variable response speed and its usage method. Background Technology

[0002] The variable displacement system of a traditional closed-loop hydraulic piston pump consists of a control valve and a variable displacement mechanism. The control valve is a three-position, four-way spool valve. For example... Figure 4 As shown, the variable mechanism includes a variable cylinder, inside which is a variable piston. The middle part of the variable piston is connected to the swashplate of the plunger pump. Both ends of the variable piston form variable chambers. The variable cylinder is equipped with a step seal and a support ring made of composite material with a relatively rough surface. Both the step seal and the support ring are in contact with the outer cylindrical surface of the variable piston. The support ring supports the movement of the variable piston in the piston cylinder, and the step seal plays a sealing role to prevent pressure leakage in the variable chamber during variable movement.

[0003] The working principle of the variable system is as follows: the control oil output by the replenishing pump is introduced into the corresponding variable chamber through the control valve, which pushes the variable piston to move to the corresponding side in the variable cylinder, thereby changing the tilt angle of the swashplate and realizing the pump's variable displacement.

[0004] In some engineering applications, there are situations requiring high-frequency hydraulic oil reversal to frequently switch the direction of motion of the actuator. For example, in the soil-shaking operation of rotary drilling rigs: during soil shaking, high-frequency hydraulic oil reversal is needed to frequently switch the forward and reverse rotation of the winch motor, thereby causing the drill bit to vibrate up and down at high frequency to meet the soil-shaking requirements. Previously, an open system consisting of an open-type electrically controlled pump and an electro-proportional directional valve was used to achieve high-frequency hydraulic oil reversal. In recent years, due to energy-saving needs, closed-loop winch systems have emerged, requiring rapid bidirectional pump switching to achieve rapid and powerful up-and-down vibration of the drill rod to meet the soil-shaking requirements. However, the variable response speed of traditional closed-loop hydraulic piston pump systems is relatively slow and cannot meet such requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a closed-loop hydraulic piston pump with high variable response speed and its usage method. This invention has the advantage of fast variable response speed.

[0006] The technical solution of the present invention is a closed-loop hydraulic piston pump with high variable response speed. The variable system of the piston pump consists of a control valve and a variable mechanism. The variable mechanism includes a variable cylinder, a variable piston is provided in the variable cylinder, the middle part of the variable piston is connected to the swashplate of the piston pump, and both ends of the variable piston form variable chambers. Both ends of the variable piston are provided with copper rings, which are located between the variable piston and the variable cylinder. The variable cylinder supports and seals the variable piston through the copper rings, and the copper rings are in clearance fit with the variable piston.

[0007] In the aforementioned closed-loop hydraulic piston pump with high variable response speed, the control valve includes two parallel high-frequency electro-proportional pressure reducing valves. Each high-frequency electro-proportional pressure reducing valve is provided with a drain port T, an outlet port M, and an inlet port P. The drain port T and the outlet port M are normally open, while the outlet port M and the inlet port P are normally closed. The drain port T is connected to the return oil circuit of the piston pump, the outlet port M is connected to the corresponding variable chamber, and the inlet port P is connected to the control oil circuit of the piston pump.

[0008] In the aforementioned closed-loop hydraulic piston pump with high variable response speed, the control oil circuit connects the piston pump's replenishment pump and an external pressure oil, with the external pressure oil having a pressure ≥4MPa.

[0009] In the aforementioned closed-loop hydraulic piston pump with high variable response speed, the two drain ports T are connected in parallel to the return oil circuit of the piston pump, the two outlet ports M are respectively connected to the variable chambers at both ends of the variable piston, and the two inlet ports P are connected in parallel to the control oil circuit of the piston pump.

[0010] In the aforementioned high variable response speed closed hydraulic piston pump, the high frequency response proportional pressure reducing valve includes an electromagnet, an iron core is provided axially on the electromagnet, a valve sleeve is provided at one end of the electromagnet, one end of the valve sleeve is fixed to the electromagnet, and the other end of the valve sleeve forms an oil outlet M. An oil drain port T and an oil inlet port P are provided on the side wall of the valve sleeve. A valve core connected to the iron core is provided inside the valve sleeve. A pre-tightened spring is provided between the valve sleeve and the valve core. The spring provides elastic force for the valve core to move towards the iron core.

[0011] When the electromagnet is de-energized, the drain port T is connected to the outlet port M, and the inlet port P is disconnected from the outlet port M. When the electromagnet is energized, the valve core moves a certain distance towards the outlet port M, and then the drain port T is disconnected from the outlet port M, while the inlet port P is connected to the outlet port M.

[0012] In the aforementioned closed-loop hydraulic piston pump with high variable response speed, a blind hole is provided on the end face of the valve core facing the oil outlet M, and a first annular groove and a second annular groove are provided on the outer circumferential surface of the valve core. The first annular groove is connected to the drain port T, and the second annular groove is located on one side of the oil inlet P. A first oil hole is provided on the bottom surface of the first annular groove, and a second oil hole is provided on the bottom surface of the second annular groove. Both the first oil hole and the second oil hole are connected to the blind hole.

[0013] In the aforementioned closed-loop hydraulic piston pump with high variable response speed, the valve core extends radially outward at one end facing the iron core to form a convex ring, the valve sleeve is provided with a stepped groove facing the electromagnet, one end of the spring is connected to the bottom surface of the stepped groove, and the other end of the spring is connected to the convex ring.

[0014] The aforementioned method of using a closed-loop hydraulic piston pump with high variable response speed involves two high-frequency electro-proportional pressure reducing valves operating independently. When one of the high-frequency electro-proportional pressure reducing valves is energized, the other high-frequency electro-proportional pressure reducing valve is de-energized, thus achieving rapid variable displacement of the piston pump.

[0015] Compared with the prior art, the present invention improves the variable displacement system of the plunger pump based on the existing plunger pump. The variable displacement mechanism and control valve of the variable displacement system are both improved. The specific effects of the improvement are as follows:

[0016] 1) The control valve is composed of two independently operating high-frequency electro-proportional pressure reducing valves. The high-frequency electro-proportional pressure reducing valve has a higher response speed, enabling rapid pressure build-up in the variable chamber, increasing the variable response speed of the plunger pump, and allowing the pressure of the two variable chambers to be adjusted independently.

[0017] 2) The variable piston uses copper rings for support and sealing. Copper rings have a lower coefficient of friction. At the same time, the copper rings and the variable piston are in clearance fit. Oil is stored in the gap between the copper rings and the variable piston, which can reduce the friction force on the variable piston during the variable process, thereby improving the variable response speed of the plunger pump.

[0018] 3) Existing variable piston mechanisms use a tight-fitting support ring and step seal for support and sealing, which places high demands on the installation process of the variable piston. Improper installation can damage the support ring and step seal, thus affecting the sealing performance. This invention uses a copper ring with a clearance fit to the variable piston, which is less prone to damage during installation and provides better sealing performance.

[0019] 4) For the control oil supplied to the control valve, in addition to the existing oil pump, an external pressure oil line with a pressure ≥4MPa is added. According to the applicant's research, under normal circumstances, a significant drop in replenishment pressure occurs during the instantaneous switching of the plunger pump between forward and reverse directions, affecting the pressure within the variable displacement chamber and consequently the variable displacement response speed. This invention utilizes both the external pressure oil and the built-in replenishment pump to provide control oil, reducing the impact of insufficient replenishment pressure during rapid pump variable displacement on the variable displacement response speed, thereby improving the variable displacement response speed of the plunger pump.

[0020] In summary, this invention has the advantage of fast variable response speed. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the variable mechanism of the present invention.

[0022] Figure 2 This is a schematic diagram of the high-frequency response proportional pressure reducing valve of the present invention.

[0023] Figure 3 This is a hydraulic schematic diagram of the present invention.

[0024] Figure 4 This is a schematic diagram of the existing variable mechanism.

[0025] The labels in the attached diagram are as follows: 2-High-frequency electro-hydraulic proportional pressure reducing valve, 10-Variable cylinder, 11-Variable piston, 12-Variable chamber, 13-Copper ring; 20-Electromagnet, 21-Iron core, 22-Valve sleeve, 23-Valve core, 24-Spring, 25-Blind hole, 26-First ring groove, 27-Second ring groove, 28-First oil hole, 29-Second oil hole, 30-Convex ring, 31-Step groove; 40-Swashplate, 41-Maintenance pump, 42-Support ring, 43-Step seal. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0027] Example: A closed-loop hydraulic piston pump with high variable response speed, wherein the variable system of the piston pump consists of a control valve and a variable mechanism.

[0028] like Figure 1 As shown, the variable mechanism includes a variable cylinder 10, a variable piston 11 is provided inside the variable cylinder 10, the middle part of the variable piston 11 is connected to the swashplate 40 of the plunger pump, and both ends of the variable piston 11 form variable chambers 12. Both ends of the variable piston 11 are provided with copper rings 13, which are fixed to the variable cylinder 10 and are located between the variable piston 11 and the variable cylinder 10. The variable cylinder 10 supports and seals the variable piston 11 through the copper rings 13, and the copper rings 13 are in clearance fit with the variable piston 11.

[0029] The control valve includes two parallel high-frequency electro-hydraulic proportional pressure reducing valves 2, such as... Figure 2 and Figure 3 As shown, the high-frequency electro-hydraulic proportional pressure reducing valve 2 is equipped with an oil drain port T ( Figure 2 As shown at point T), oil outlet M ( Figure 2 (as shown at point M) and oil inlet P ( Figure 2 As shown at point P, the drain port T and the outlet port M are normally open, while the outlet port M and the inlet port P are normally closed.

[0030] The two drain ports T are connected in parallel to the return oil circuit of the plunger pump, and the oil reaches the return oil tank through the return oil circuit. The two outlet ports M are respectively connected to the variable chambers 12 at both ends of the variable piston 11. The two inlet ports P are connected in parallel to the control oil circuit of the plunger pump. The control oil circuit is connected to the original built-in replenishing pump 41 of the plunger pump and external pressure oil. The replenishing pump 41 and the external pressure oil together provide control oil for the control oil circuit. The supply pressure of the external pressure oil is ≥4MPa.

[0031] The high-frequency electro-electric proportional pressure reducing valve 2 includes an electromagnet 20, an iron core 21 axially mounted on the electromagnet 20, a valve sleeve 22 at one end of the electromagnet 20, one end of the valve sleeve 22 fixed to the electromagnet 20, and the other end of the valve sleeve 22 forming an oil outlet M. The side wall of the valve sleeve 22 is provided with an oil drain port T and an oil inlet port P. A valve core 23 is provided inside the valve sleeve 22 to abut against the iron core 21. A pre-tightened spring 24 is provided between the valve sleeve 22 and the valve core 23. The spring 24 provides elastic force to the valve core 23 to move toward the iron core 21, so that the valve core 23 and the iron core 21 are tightly attached.

[0032] When the electromagnet 20 is de-energized, the drain port T is connected to the outlet port M, and the inlet port P is disconnected from the outlet port M. When the electromagnet 20 is energized, the valve core 23 moves a certain distance towards the outlet port M, and then the drain port T is disconnected from the outlet port M, and the inlet port P is connected to the outlet port M.

[0033] The valve core 23 has a blind hole 25 on the end face facing the oil outlet M. The outer circumferential surface of the valve core 23 has a first annular groove 26 and a second annular groove 27. The first annular groove 26 is connected to the oil drain port T. The second annular groove 27 is located on one side of the oil inlet P. The bottom surface of the first annular groove 26 has a first oil hole 28. The bottom surface of the second annular groove 27 has a second oil hole 29. Both the first oil hole 28 and the second oil hole 29 are connected to the blind hole 25.

[0034] The valve core 23 extends radially outward at one end toward the iron core 21 to form a convex ring 30. The valve sleeve 22 is provided with a stepped groove 31 facing the electromagnet 20. One end of the spring 24 is pressed against the bottom surface of the stepped groove 31, and the other end of the spring 24 is pressed against the convex ring 30.

[0035] How to use the plunger pump: The two high-frequency electro-proportional pressure reducing valves 2 work independently. When one of the high-frequency electro-proportional pressure reducing valves 2 is energized, the other high-frequency electro-proportional pressure reducing valve 2 is de-energized, thus realizing the rapid variable displacement of the plunger pump.

[0036] Working principle of high-frequency electro-proportional pressure reducing valve 2: as follows Figure 2 As shown, when the electromagnet 20 is energized, the iron core 21 pushes the valve core 23 to move to the left against the elastic force of the spring 24. As the current increases, the thrust of the iron core 21 on the valve core 23 increases, further compressing the spring 24. The valve core 23 moves further to the left, connecting the oil outlet M with the oil inlet P. The control oil enters the corresponding variable chamber 12 from the oil inlet P through the oil outlet, pushing the variable piston 11 to move, thus changing the pump displacement.

[0037] like Figure 3As shown, when the left high-frequency electro-hydraulic proportional pressure reducing valve 2 (hereinafter referred to as the left valve) is energized and the right high-frequency electro-hydraulic proportional pressure reducing valve 2 (hereinafter referred to as the right valve) is de-energized, the oil inlet P of the left valve communicates with the oil outlet M, allowing control oil to enter the left variable chamber 12, pushing the variable piston 11 to the right. Hydraulic oil in the right variable chamber 12 flows from the oil outlet M and drain port T of the right valve back to the oil tank. At this time, the piston pump outputs high-pressure oil at port A. When the left valve is de-energized and the right valve is energized, the oil inlet P of the right valve communicates with the oil outlet M, allowing control oil to enter the right variable chamber 12, pushing the variable piston 11 to the left. Hydraulic oil in the left variable chamber 12 flows from the oil outlet M and drain port T of the left valve back to the oil tank. At this time, the piston pump outputs high-pressure oil at port B. Rapid variable switching of the piston pump is achieved by rapidly alternating energization and de-energization of the two electromagnets 20.

[0038] The gap between the copper ring 13 and the variable piston 11 is set to, for example, 0.035mm. When the variable piston is in motion, there is oil with a pressure of ≥4MPa in the corresponding variable chamber. This allows a small amount of oil to leak into the pump housing through the gap between the copper ring 13 and the variable piston 11. This ensures that a stable pressure is established in the variable chamber while providing lubrication for the movement of the variable piston and reducing the coefficient of friction.

[0039] The variable mechanism in the embodiment is similar to... Figure 4 The comparison of existing variable mechanisms shown:

[0040] In the existing variable mechanism, the support ring 42 provides support and guidance for the variable piston 11, and the step seal 43 provides a seal between the variable piston 11 and the variable cylinder 10. The support ring 42, the step seal 43 and the variable piston 11 are interference fit, and the surface of the support ring 42 is rough and has a large coefficient of friction. During the variable process, it generates a large friction force on the variable piston 11, which reduces the variable speed of the plunger pump.

[0041] In the variable mechanism of the embodiment, a copper ring 13 is used to provide support, guidance and sealing for the variable piston 11. The copper ring 13 is lubricating and has a low coefficient of friction. At the same time, the copper ring 13 and the variable piston 11 are in clearance fit. When the variable speed is changed, the gap between the copper ring 13 and the variable piston 11 is lubricated with oil, which reduces frictional resistance and improves the variable speed of the plunger pump.

[0042] Furthermore, in existing variable displacement mechanisms, the variable piston is prone to cutting the support ring and the step seal when installing the guide ring and the step seal, causing sealing failure; however, using a copper ring can avoid this problem.

[0043] In the description of the embodiments, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation.

Claims

1. A closed-loop hydraulic piston pump with high variable response speed, wherein the variable system of the piston pump consists of a control valve and a variable mechanism, the variable mechanism including a variable cylinder (10), a variable piston (11) is provided inside the variable cylinder (10), the middle part of the variable piston (11) is connected to the swashplate (40) of the piston pump, and both ends of the variable piston (11) form variable chambers (12), characterized in that: The variable piston (11) is provided with copper rings (13) at both ends. The copper rings (13) are located between the variable piston (11) and the variable cylinder (10). The variable cylinder (10) supports and seals the variable piston (11) through the copper rings (13). The copper rings (13) and the variable piston (11) are in clearance fit. The control valve includes two parallel high-frequency electro-proportional pressure reducing valves (2). The high-frequency electro-proportional pressure reducing valves (2) are provided with a drain port T, an outlet port M and an inlet port P. The drain port T and the outlet port M are normally open, and the outlet port M and the inlet port P are normally closed. The drain port T is connected to the return oil circuit of the plunger pump, the outlet port M is connected to the corresponding variable chamber (12), and the inlet port P is connected to the control oil circuit of the plunger pump. The high-frequency electro-electric proportional pressure reducing valve (2) includes an electromagnet (20), an iron core (21) is provided on the axial direction of the electromagnet (20), a valve sleeve (22) is provided at one end of the electromagnet (20), one end of the valve sleeve (22) is fixed to the electromagnet (20), the other end of the valve sleeve (22) forms an oil outlet M, an oil drain port T and an oil inlet port P are provided on the side wall of the valve sleeve (22), a valve core (23) connected to the iron core (21) is provided inside the valve sleeve (22), a pre-tightened spring (24) is provided between the valve sleeve (22) and the valve core (23), and the spring (24) gives the valve core (23) a spring force to move towards the iron core (21); When the electromagnet (20) is de-energized, the drain port T is connected to the outlet port M, and the inlet port P is disconnected from the outlet port M. When the electromagnet (20) is energized, the valve core (23) moves a certain distance to the outlet port M side, and then the drain port T is disconnected from the outlet port M, and the inlet port P is connected to the outlet port M.

2. The closed-loop hydraulic piston pump with high variable response speed according to claim 1, characterized in that: The control oil circuit connects the plunger pump's make-up pump (41) and the external pressure oil, with the external pressure oil pressure being ≥4MPa.

3. The closed-loop hydraulic piston pump with high variable response speed according to claim 1, characterized in that: The two drain ports T are connected in parallel to the return oil circuit of the plunger pump. The two outlet ports M are connected to the variable chambers (12) at both ends of the variable piston (11). The two inlet ports P are connected in parallel to the control oil circuit of the plunger pump.

4. The closed-loop hydraulic piston pump with high variable response speed according to claim 1, characterized in that: The valve core (23) has a blind hole (25) on the end face facing the oil outlet M. The outer circumferential surface of the valve core (23) has a first annular groove (26) and a second annular groove (27). The first annular groove (26) is connected to the drain port T. The second annular groove (27) is located on one side of the oil inlet P. The bottom surface of the first annular groove (26) has a first oil hole (28). The bottom surface of the second annular groove (27) has a second oil hole (29). The first oil hole (28) and the second oil hole (29) are both connected to the blind hole (25).

5. The closed-loop hydraulic piston pump with high variable response speed according to claim 1, characterized in that: The valve core (23) extends radially outward at one end toward the iron core (21) to form a convex ring (30). The valve sleeve (22) has a stepped groove (31) facing the electromagnet (20). One end of the spring (24) is connected to the bottom surface of the stepped groove (31), and the other end of the spring (24) is connected to the convex ring (30).

6. The method of using the closed-loop hydraulic piston pump with high variable response speed according to any one of claims 2 to 5, characterized in that: Two high-frequency electro-hydraulic proportional pressure reducing valves (2) work independently. When one of the high-frequency electro-hydraulic proportional pressure reducing valves (2) is energized, the other high-frequency electro-hydraulic proportional pressure reducing valve (2) is not energized, thus realizing the rapid variable displacement of the plunger pump.

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