Balanced non-leakage low friction hydraulic cylinder

Abstract

The present invention relates to the technical field of hydraulic cylinders, and discloses a balanced, leak-free, low-friction hydraulic cylinder, comprising a main oil pump, a servo valve, a rodless chamber oil port, a rod chamber oil port, a first oil port, an oil supply pipeline, a piston balancing groove arranged on a piston, a second oil port, a guide sleeve balancing groove arranged on a guide sleeve, an auxiliary oil pump, a first pressure reducing valve, a second pressure reducing valve, and a one-way valve. By opening a balancing groove on the piston and the guide sleeve and introducing high-pressure oil, the pressure of the rod chamber or the rodless chamber is equal to the pressure of the rod chamber or the rodless chamber, and the oil in the rod chamber and the rodless chamber cannot leak at this time, so that the system pressure is stable and the control accuracy is high, and the high-pressure seal between the piston and the cylinder barrel is eliminated, so that the friction of the entire hydraulic cylinder system is reduced, the mechanical loss is reduced, and the efficiency and motion performance of the system are improved, which is particularly suitable for working conditions with high pressure, low speed and extremely high control accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic cylinders, and in particular to a balanced, leak-free, low-friction hydraulic cylinder. Background Art

[0002] Hydraulic cylinder is one of the most commonly used components in the hydraulic industry. It converts hydraulic energy into mechanical energy and is widely used in linear reciprocating motion or swinging motion. It has a simple structure and reliable operation.

[0003] A typical hydraulic cylinder is basically composed of a cylinder bottom, a cylinder barrel, an end cover, a piston, a piston rod, a sealing device and a guide device. It can be divided into single-acting and double-acting types according to the hydraulic pressure, and can be divided into piston type, plunger type, multi-stage telescopic sleeve type, gear rack type, etc. according to the structural form. The pressure of the hydraulic cylinder can reach extremely high. When the hydraulic cylinder needs to be fine-tuned, it brings great challenges to the control accuracy.

[0004] Most of the current hydraulic cylinders are sealed with sealing rings, so friction always exists in the hydraulic cylinder system, reducing the efficiency and motion performance of the system and affecting the control performance. In addition, internal and external leakage of hydraulic cylinders is difficult to avoid on existing hydraulic cylinders. Leakage will lead to unstable system pressure and unstable actuator speed, which cannot meet the control requirements and directly affect the stability and reliability of the equipment. Especially in the case of high pressure, low speed and extremely high control accuracy requirements, leakage will directly lead to the system failing to meet the control accuracy requirements or even breaking the loop, and leakage will also lead to oil pollution and waste. Summary of the invention

[0005] The purpose of the present invention is to provide a balanced, leak-free, low-friction hydraulic cylinder, which can solve one of the problems in the prior art of seals causing large friction, loss of performance or oil leakage.

[0006] In order to achieve the above-mentioned object, the present invention provides a balanced, leak-free, low-friction hydraulic cylinder, comprising a main oil pump, a servo valve, a rodless chamber oil port, a rod chamber oil port, a first oil port, an oil supply pipeline, a piston balancing groove arranged on a piston, a second oil port, a guide sleeve balancing groove arranged on a guide sleeve, an auxiliary oil pump, a first pressure reducing valve, a second pressure reducing valve, and a one-way valve;

[0007] The main oil pump is connected to the rodless chamber oil port and the rod chamber oil port respectively through the servo valve; the first oil port is connected to the piston balance groove through the oil supply pipeline, and the second oil port is connected to the guide sleeve balance groove; the auxiliary oil pump is connected to the first oil port through the first pressure reducing valve; the auxiliary oil pump is connected to the first oil port and the second oil port at the same time through the second pressure reducing valve; a one-way valve is arranged between the first pressure reducing valve and the second pressure reducing valve, which only allows oil to flow from the second pressure reducing valve to the first pressure reducing valve; when the servo valve controls the oil to flow to the rodless chamber oil port, the first pressure reducing valve opens; when the servo valve controls the oil to flow to the rod chamber oil port, the second pressure reducing valve opens.

[0008] Furthermore, the balanced, leak-free, low-friction hydraulic cylinder also includes a sealing ring, which is arranged between the cylinder barrel and the guide sleeve.

[0009] Furthermore, a pressure relief groove is provided on the guide sleeve, the pressure relief groove is communicated with the guide sleeve balancing groove, and the pressure relief groove is communicated with the oil tank through a third oil port.

[0010] Furthermore, the balanced leakage-free low-friction hydraulic cylinder also includes a low-pressure sealing ring, a dust ring and a long guide ring, wherein the low-pressure sealing ring and the dust ring are arranged between the piston rod and the end cover, and the long guide ring is installed between the piston rod and the guide sleeve.

[0011] Furthermore, the balanced, leak-free, low-friction hydraulic cylinder also includes a pressure regulating valve, the outlet of the pressure regulating valve is connected to the oil tank, and the inlet of the pressure regulating valve is connected to the outlet of the main oil pump.

[0012] Furthermore, the balanced, leak-free, low-friction hydraulic cylinder also includes a safety valve, an inlet of the safety valve is connected to the auxiliary oil pump, and an outlet of the safety valve is connected to the oil tank.

[0013] Furthermore, at least two short guide rings are arranged on the piston, and the piston balancing groove is arranged between the two short guide rings.

[0014] Furthermore, the main oil pump inlet and the auxiliary oil pump inlet are connected to the oil tank.

[0015] Furthermore, the servo valve includes oil ports Y1, Y2, A, and B, the oil port Y1 is connected to the rodless chamber oil port, the oil port Y2 is connected to the rod chamber oil port, the oil port A is connected to the main oil pump outlet, and the oil port B is connected to the oil tank.

[0016] Furthermore, the rod chamber oil port is arranged on the cylinder barrel and communicated with the rod chamber, and the rodless chamber oil port is communicated with the rodless chamber.

[0017] The beneficial effects of the present invention are:

[0018] (I) The present invention opens a balancing groove on the piston and the guide sleeve and introduces high-pressure oil to make the pressure of the rod chamber or the rodless chamber equal to it. At this time, the oil in the rod chamber and the rodless chamber cannot leak, achieving leakage-free, making the system pressure stable and the control accuracy high, which is suitable for extremely high precision requirements.

[0019] (ii) The present invention eliminates the high-pressure seal between the piston and the cylinder barrel, thereby reducing the friction of the entire hydraulic cylinder system, reducing mechanical losses, and improving the efficiency and motion performance of the system.

[0020] (III) The present invention is connected to the oil tank via a pressure relief groove. At this time, the oil in the pressure relief groove is low-pressure oil, so a low-pressure sealing ring is used for sealing, which effectively reduces the friction of the system.

[0021] (iv) The present invention achieves zero leakage and low friction through these structures, which is particularly suitable for working conditions with high pressure, low speed and extremely high control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Figure 2 It is a structural schematic diagram of the piston assembly of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the guide sleeve assembly of the present invention.

[0025] The accompanying drawings are marked as follows: cylinder bottom 1, rodless chamber oil port 2, cylinder barrel 3, piston 4, short guide ring 5, piston balancing groove 6, piston rod 7, first oil port 8, rod chamber oil port 9, guide sleeve 10, second oil port 11, third oil port 12, guide sleeve balancing groove 13, pressure relief groove 14, sealing ring 15, long guide ring 16, low-pressure sealing ring 17, dust ring 18, flange 19, end cover 20, bolt 21, main oil pump 22, servo valve 23, pressure regulating valve 24, auxiliary oil pump 25, safety valve 26, first pressure reducing valve 27, second pressure reducing valve 28, one-way valve 29, oil tank 30, and oil supply pipeline 31. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0027] In the present invention, unless otherwise stated, the directional words such as "upper" and "lower" usually refer to the orientation in the assembled state. "Inside" and "outside" refer to the inside and outside relative to the outline of each component itself.

[0028] To solve the problem of large friction of seals, loss of performance or oil leakage in the prior art, such as Figure 1-Figure 3 As shown, the present invention provides a balanced, leak-free, low-friction hydraulic cylinder, comprising a main oil pump 22, a servo valve 23, a rodless chamber oil port 2, a rod chamber oil port 9, a first oil port 8, an oil supply pipeline 31, a piston balancing groove 6 arranged on a piston 4, a second oil port 11, a guide sleeve balancing groove 13 arranged on a guide sleeve 10, an auxiliary oil pump 25, a first pressure reducing valve 27, a second pressure reducing valve 28, and a one-way valve 29;

[0029] The main oil pump 22 is connected to the rodless chamber oil port 2 and the rod chamber oil port 9 respectively through the servo valve 23; the first oil port 8 is connected to the piston balance groove 6 through the oil supply pipeline 31, and the second oil port 11 is connected to the guide sleeve balance groove 13; the auxiliary oil pump 25 is connected to the first oil port 8 through the first pressure reducing valve 27; the auxiliary oil pump 25 is connected to the first oil port 8 and the second oil port 11 at the same time through the second pressure reducing valve 28; a one-way valve 29 is arranged between the first pressure reducing valve 27 and the second pressure reducing valve 28, which only allows the oil to flow from the second pressure reducing valve 28 to the first pressure reducing valve 27; when the servo valve 23 controls the oil to flow to the rodless chamber oil port 2, the first pressure reducing valve 27 is opened; when the servo valve 23 controls the oil to flow to the rod chamber oil port 9, the second pressure reducing valve 28 is opened.

[0030] By opening a balancing groove on the piston and the guide sleeve and introducing high-pressure oil, the pressure in the rod chamber or the rodless chamber is made equal. At this time, the oil in the rod chamber and the rodless chamber cannot leak, making the system pressure stable and the control accuracy high. The high-pressure seal between the piston and the cylinder barrel is eliminated, so that the friction of the entire hydraulic cylinder system is reduced, the mechanical loss is reduced, and the efficiency and movement performance of the system are improved. This is especially suitable for working conditions with high pressure, low speed and extremely high control accuracy.

[0031] It should be noted that the arrangement of the above structure is based on the basic structure of the hydraulic cylinder described below: in a preferred case, the cylinder bottom 1 is coaxially fixedly connected to the cylinder barrel 3, and the cylinder barrel 3 is a hollow structure with both ends passing through. More preferably, the two can be welded or integrally formed. The piston rod 7 is coaxially fixedly connected to the piston 4. More preferably, the two can be welded or integrally formed. The piston 4 and the piston rod 7 are arranged in the inner cavity of the cylinder barrel 3 to slide freely. With the piston 4 as the boundary, the cavity in the cylinder barrel 3 is divided into a rod cavity with a piston rod 7 and a rodless cavity without a piston rod 7. An end cover 20 is provided at the end of the cylinder barrel 3 away from the cylinder bottom 1, and the flange 19 is fixedly connected to the end cover by bolts 21. The guide sleeve 10 is arranged to be sleeved on the piston rod 7, and its right end face is in close contact with the end cover.

[0032] The rodless chamber oil port 2 and the first oil port 8 are arranged on the cylinder bottom 1 , and the second oil port 11 is arranged on the cylinder barrel 3 .

[0033] In order to improve the sealing performance between the cylinder barrel 3 and the guide sleeve 10 and prevent oil leakage, the balanced non-leakage low-friction hydraulic cylinder further includes a sealing ring 15 , which is arranged between the cylinder barrel 3 and the guide sleeve 10 .

[0034] In order to guide out the excess oil that may leak in the guide sleeve balance groove 13 to prevent oil leakage, the guide sleeve 10 is further provided with a pressure relief groove 14, which is connected to the guide sleeve balance groove 13, and the pressure relief groove 14 is connected to the oil tank 30 through the third oil port 12. The third oil port 12 is provided on the cylinder barrel 3.

[0035] Preferably, the pressure relief groove 14 and the guide sleeve balancing groove 13 are arranged along the radial direction of the guide sleeve 10 and are connected through the gap between the guide sleeve 10 and the piston rod 7.

[0036] In order to prevent oil leakage from the pressure relief groove 14 on the piston rod 7 and dust from adhering to the circumference of the piston rod 17, the balanced non-leakage low-friction hydraulic cylinder also includes a low-pressure seal ring 17, a dust ring 18 and a long guide ring 16. The low-pressure seal ring 17 and the dust ring 18 are arranged between the piston rod 7 and the end cover 20, and the long guide ring 16 is installed between the piston rod 7 and the guide sleeve 10. Although the low-pressure seal ring 17 is provided, the pressure is very low, so even with the low-pressure seal ring 17, the friction resistance is very small, and non-leakage and low friction resistance are achieved. The dust ring 18 blocks external dust from entering the internal oil.

[0037] Furthermore, the balanced non-leakage low-friction hydraulic cylinder further includes a pressure regulating valve 24, the outlet of the pressure regulating valve 24 is connected to the oil tank 30, and the inlet is connected to the outlet of the main oil pump 22. The pressure regulating valve 24 is used to adjust the outlet pressure of the main oil pump 22 so that the outlet pressure is constant at a specific value.

[0038] Furthermore, the balanced non-leakage low-friction hydraulic cylinder further includes a safety valve 26, the inlet of the safety valve 26 is connected to the auxiliary oil pump 25, and the outlet is connected to the oil tank 30. The safety valve 26 is used to discharge oil to prevent the oil pressure between the auxiliary oil pump 25 and the pressure reducing valve from being too high.

[0039] Since the piston balancing groove 6 plays a balancing role when the balancing hydraulic cylinder is extended and retracted, in order to make the force of the piston balancing groove 6 in the two formations close to the same, at least two short guide rings 5 ​​are provided on the piston 4, and the piston balancing groove 6 is arranged between the two short guide rings 5. Preferably, there are two short guide rings 5, and the piston balancing groove 6 is arranged in the middle. Preferably, the balancing groove 6 is an annular groove arranged around the piston 4.

[0040] In order to supply oil to the main oil pump 22 and the auxiliary oil pump 25 , the inlet of the main oil pump 22 and the inlet of the auxiliary oil pump 25 are connected to the oil tank 30 .

[0041] In order to output the modulated oil flow and pressure and input oil into the two cavities respectively, the servo valve 23 includes oil ports Y1, Y2, A, and B. The oil port Y1 is connected to the rodless chamber oil port 2, the oil port Y2 is connected to the rod chamber oil port 9, the oil port A is connected to the outlet of the main oil pump 22, and the oil port B is connected to the oil tank 30.

[0042] It should be noted that the rod chamber oil port 9 is arranged on the cylinder tube 3 and communicates with the rod chamber, and the rodless chamber oil port 2 is communicated with the rodless chamber.

[0043] The specific working process of the present invention is as follows:

[0044] When the electromagnet YA of the servo valve 23 is not energized, the main oil pump 22 draws oil from the oil tank 30 and supplies oil to the rodless chamber of the hydraulic cylinder. The pressure regulating valve 24 is used to adjust the outlet pressure of the main oil pump 22, and the outlet pressure is P. At this time, the auxiliary oil pump 25 adjusts the outlet pressure to P1 through the first pressure reducing valve 27. When P=P1, the oil pressure in the rodless chamber is balanced with the pressure in the piston balance groove 6, and there is no oil leakage in the rodless chamber. The oil in the piston balance groove 6 can leak into the rod chamber. Although the oil in the piston balance groove 6 can leak, it does not affect the pressure in the rodless chamber, which makes the system pressure stable; when the electromagnet YA of the servo valve 23 is energized, the main oil pump 22 supplies oil to the rod chamber of the hydraulic cylinder, and the outlet pressure is P. At this time, the outlet of the auxiliary oil pump 25 passes through the second pressure reducing valve 28. The pressure is set to P2 through the second pressure reducing valve 28, and the oil enters the first oil port 8 through the one-way valve 29, and enters the piston balance groove 6 along the oil supply pipeline 31. In addition, the oil will flow to the second oil port 11 through the second pressure reducing valve 28 and enter the guide sleeve balance groove 13. When P=P2, the rod chamber oil pressure is balanced with the oil pressure in the piston balance groove 6 and the guide sleeve balance groove 13, and there is no leakage in the rod chamber. The oil in the guide sleeve balance groove 13 can leak to the pressure relief groove 14, and then a part of it flows back to the oil tank 30. The low-pressure sealing ring 17 prevents the other part of the oil from leaking. Because the pressure is very low, even if there is a sealing ring, the friction resistance is very small, and no leakage and low friction resistance are achieved, so that the system pressure is stable and the control accuracy is high, which is suitable for extremely high precision requirements. In addition, the high-pressure seal between the piston 4 and the cylinder barrel 3 is cancelled, so that the friction of the entire hydraulic cylinder system is reduced, the mechanical loss is reduced, and the efficiency and motion performance of the system are improved. The present invention is particularly suitable for working conditions with high pressure, low speed and extremely high control accuracy.

[0045] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0046] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0047] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A balanced, leak-free, low-friction hydraulic cylinder, characterized in that: It comprises a main oil pump (22), a servo valve (23), a rodless chamber oil port (2), a rod chamber oil port (9), a first oil port (8), an oil supply pipeline (31), a piston balance groove (6) arranged on a piston (4), a second oil port (11), a guide sleeve balance groove (13) arranged on a guide sleeve (10), an auxiliary oil pump (25), a first pressure reducing valve (27), a second pressure reducing valve (28), and a one-way valve (29); The main oil pump (22) is connected to the rodless chamber oil port (2) and the rod chamber oil port (9) respectively through the servo valve (23); the first oil port (8) is connected to the piston balance groove (6) through the oil supply pipeline (31), and the second oil port (11) is connected to the guide sleeve balance groove (13); the auxiliary oil pump (25) is connected to the first oil port (8) through the first pressure reducing valve (27); the auxiliary oil pump (25) is connected to the first oil port (8) and the second oil port (11) at the same time through the second pressure reducing valve (28); a one-way valve (29) is provided between the first pressure reducing valve (27) and the second pressure reducing valve (28) for only allowing oil to flow from the second pressure reducing valve (28) to the first pressure reducing valve (27); when the servo valve (23) controls the oil to flow to the rodless chamber oil port (2), the first pressure reducing valve (27) is opened; when the servo valve (23) controls the oil to flow to the rod chamber oil port (9), the second pressure reducing valve (28) is opened.

2. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: The balanced, leak-free, low-friction hydraulic cylinder also includes a sealing ring (15), and the sealing ring (15) is arranged between the cylinder barrel (3) and the guide sleeve (10).

3. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: The guide sleeve (10) is also provided with a pressure relief groove (14), the pressure relief groove (14) is in communication with the guide sleeve balance groove (13), and the pressure relief groove (14) is in communication with the oil tank (30) via a third oil port (12).

4. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: The balanced, leak-free, low-friction hydraulic cylinder further comprises a low-pressure sealing ring (17), a dust ring (18) and a long guide ring (16); the low-pressure sealing ring (17) and the dust ring (18) are arranged between the piston rod (7) and the end cover (20); and the long guide ring (16) is installed between the piston rod (7) and the guide sleeve (10).

5. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: The balanced, leak-free, low-friction hydraulic cylinder also includes a pressure regulating valve (24), the outlet of the pressure regulating valve (24) being connected to an oil tank (30), and the inlet of the pressure regulating valve (24) being connected to the outlet of the main oil pump (22).

6. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: The balanced non-leakage low-friction hydraulic cylinder further comprises a safety valve (26), the inlet of the safety valve (26) being connected to the auxiliary oil pump (25), and the outlet of the safety valve (26) being connected to the oil tank (30).

7. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: At least two short guide rings (5) are arranged on the piston (4), and the piston balancing groove (6) is arranged between the two short guide rings (5).

8. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: The inlet of the main oil pump (22) and the inlet of the auxiliary oil pump (25) are connected to the oil tank (30).

9. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: The servo valve (23) includes an oil port Y1, an oil port Y2, an oil port A, and an oil port B. The oil port Y1 is connected to the rodless chamber oil port (2), the oil port Y2 is connected to the rod chamber oil port (9), the oil port A is connected to the outlet of the main oil pump (22), and the oil port B is connected to the oil tank (30).

10. A balanced, leak-free, low-friction hydraulic cylinder according to claim 1, characterized in that: The rod chamber oil port (9) is arranged on the cylinder barrel (3) and is in communication with the rod chamber, and the rodless chamber oil port (2) is in communication with the rodless chamber.

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