CN112065789B

CN112065789B - Closed hydraulic system

Info

Publication number: CN112065789B
Application number: CN202010952949.7A
Authority: CN
Inventors: 王海; 杨永军; 翁秀明; 李德胜; 缪兵; 邹玉祥
Original assignee: Jiangsu Machinery Research & Design Institute Co ltd
Current assignee: Jiangsu Machinery Research & Design Institute Co ltd
Priority date: 2020-09-11
Filing date: 2020-09-11
Publication date: 2023-06-13
Anticipated expiration: 2040-09-11
Also published as: CN112065789A

Abstract

The invention discloses a closed hydraulic system, and belongs to the technical field of hydraulic systems. The closed hydraulic system comprises a hydraulic pump, a hydraulic actuator and an oil tank, wherein one end of the hydraulic pump is communicated with one end of the hydraulic actuator through an oil way A, and one end of the hydraulic pump is communicated with one end of the hydraulic actuator through an oil way B; the oil way A and the oil way B are respectively connected with the oil tank through oil supplementing ways, and oil supplementing pumps are arranged on the oil supplementing ways; an oil-adding valve is connected between the oil way A and the oil way B through an oil pipe, and the oil-adding valve is communicated to an oil tank; the A oil way and/or the B oil way are/is provided with a throttle valve and/or a one-way sequence valve; the invention can solve the problems of uncontrollable pressure fluctuation and oil temperature of the closed hydraulic system under the low-load working condition, and provides a guarantee for continuous and stable operation of the closed hydraulic system.

Description

Closed hydraulic system

Technical Field

The invention belongs to the technical field of hydraulic systems, and particularly relates to a closed hydraulic system.

Background

The closed hydraulic system has the characteristics of compact structure, high integration degree, small reversing impact and stable operation, and is widely applied to occasions with requirements on places and severe working conditions, such as industries of chemical industry, steel, engineering vehicles, ships and the like. The oil outlet and the oil inlet of the hydraulic pump in the closed hydraulic system are respectively and directly connected with the oil inlet and the oil return port of the hydraulic motor, the hydraulic pump is not communicated with the outside, the oil in the closed hydraulic system is self-circulated, the contact opportunity with air is less, pollutants and water vapor are not easy to mix, and the oil tank can be designed smaller.

As shown in fig. 1, a general closed hydraulic system includes a prime mover, a main hydraulic pump, a variable control mechanism, an oil compensating pump, an oil compensating valve, a pressure meter, etc., and under a low load condition, when the difference Δp of the pressures between two working oil paths of the main hydraulic pressure is less than or equal to 1MPa, the hydraulic pressure acting on the spool of the oil compensating valve is insufficient to completely overcome the spring force acting on the spool by the spring, so that the spool generates malfunction, including that the spool cannot be maintained in the left position or the right position, or the spool is in the middle position and is not operated, or the spool is not operated reliably, or the spool is operated uncontrollably, resulting in the pressure fluctuation and the oil temperature of the system, which affects the continuous stable operation.

Disclosure of Invention

1. Technical problem to be solved by the invention

The invention aims to solve the problems that in the prior art, in a closed hydraulic system, under a low-load working condition, a valve core of an oil valve is in misoperation, so that the pressure fluctuation and the oil temperature of the system are uncontrollable, and continuous and stable operation is influenced.

2. Technical proposal

In order to achieve the above purpose, the technical scheme provided by the invention is as follows:

the closed hydraulic system comprises a hydraulic pump, a hydraulic actuator and an oil tank, wherein one end of the hydraulic pump is communicated with one end of the hydraulic actuator through an oil way A, and one end of the hydraulic pump is communicated with one end of the hydraulic actuator through an oil way B; the oil way A and the oil way B are respectively connected with the oil tank through oil supplementing ways, and oil supplementing pumps are arranged on the oil supplementing ways; the oil supply system comprises an oil supply system, an oil supply system and an oil supply system, wherein an oil supply valve is connected between an oil line A and an oil line B through an oil pipe, the oil supply valve is communicated to an oil tank, the oil supply valve can replace hot oil in the system, and redundant oil output by an oil supplementing pump flows from the oil supply valve to the oil tank; and the A oil way and/or the B oil way are/is provided with a throttle valve and/or a one-way sequence valve.

Preferably, oil flows from an oil way A to an oil way B, and a throttle valve and/or a one-way sequence valve are arranged on the oil way A;

and/or oil flows from the oil way B to the oil way A, and a throttle valve and/or a one-way sequence valve are arranged on the oil way B.

Under low load conditions: if the oil flows from the oil line A to the oil line B only through the hydraulic motor when the system works, a throttle valve is only required to be added to the oil line A; if the oil flows from the oil line B to the oil line A only through the hydraulic motor when the system works, a throttle valve is only required to be added to the oil line B; if the working conditions of oil flowing from the oil line A to the oil line B and from the oil line B to the oil line A exist during the system working, the throttle valves are required to be added at the oil line A and the oil line B. By increasing the throttle valve, the resistance of oil flowing through the throttle valve is improved, the pressure difference delta P between the oil ways A and B of the main hydraulic pump is increased, so that the hydraulic pressure acting on the valve core by delta P is larger than the spring force acting on the valve core by the spring, and the valve core of the oil-adding valve can act as required. The throttle valve can change the pressure loss flowing through the throttle valve by changing the size of the cross section of the flow passage or the length of the flow passage; the throttle valve is a hydraulic throttle valve or a unidirectional hydraulic throttle valve; the throttle valve can be manually adjusted or not manually adjusted; the throttle valve adopts a pipeline installation form or a plate installation form.

Alternatively, under low load conditions: if the oil flows from the oil line A to the oil line B through the hydraulic motor during the operation of the system, a one-way sequence valve is only needed to be added to the oil line A; if the oil flows from the oil line B to the oil line A through the hydraulic motor during the operation of the system, a one-way sequence valve is only needed to be added to the oil line B; if the system works under two working conditions that oil flows from the oil way A to the oil way B through the hydraulic motor and from the oil way B to the oil way A through the hydraulic motor, one-way sequence valves are added to the oil way A and the oil way B. By adding the one-way sequence valve, the difference delta P of the pressure between the working oil ways A and B of the main hydraulic pump is increased, so that the hydraulic force acting on the valve core by delta P is larger than the spring force acting on the valve core by the spring, and the valve core of the oil-more valve can act as required. The leakage mode of the one-way sequence valve is leakage, and the external oil leakage is directly returned to the oil tank; the one-way sequence valve adopts a pipeline installation form or a plate installation form; the pressure set value of the one-way sequence valve can be manually adjusted according to actual operation; the specification of the one-way sequence valve can be matched and selected according to the flow of the closed hydraulic system.

Preferably, the throttle valve is a hydraulic throttle valve; and/or the one-way throttle valve is a one-way hydraulic throttle valve.

Preferably, the hydraulic pump is a variable pump, and a variable control mechanism is arranged on the hydraulic pump; when the swash plate controlled by the variable control mechanism is changed between the positive angle and the negative angle, two oil paths with opposite flow directions are formed, so that the steering of the hydraulic motor is changed.

Preferably, the oil supplementing pump and the hydraulic pump are connected by a through shaft, and a power input end of the through shaft is connected to a prime motor, which can be an electric motor.

Preferably, the oil supplementing path is provided with an A oil supplementing valve and a B oil supplementing valve, and the oil supplementing path between the A oil supplementing valve and the B oil supplementing valve is communicated with the oil tank through an oil supplementing pump; the oil supplementing valve of the oil way A and the oil supplementing valve of the oil way B are two reverse series-connected one-way valves, and oil is respectively supplemented to the oil way A and the oil way B.

Preferably, the oil-filled valve is connected to the oil tank via an oil-filled valve.

Preferably, the oil-adding pressure valve is an overflow valve, which is used for adjusting the oil-adding pressure in the closed system, and the pressure set value can be manually adjusted; the oil outlet of the oil overflow valve is provided with a cooler and an oil filter, the cooling medium of the cooler is cooling water or air, and the oil filter is an oil return oil filter.

Preferably, the oil circuit A and/or the oil circuit B and/or the oil supplementing circuit are/is provided with a pressure gauge and/or a pressure transmitter and/or a pressure switch.

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:

the closed hydraulic system comprises a hydraulic pump, a hydraulic actuator and an oil tank, wherein one end of the hydraulic pump is communicated with one end of the hydraulic actuator through an oil way A, and one end of the hydraulic pump is communicated with one end of the hydraulic actuator through an oil way B; the oil way A and the oil way B are respectively connected with the oil tank through oil supplementing ways, and oil supplementing pumps are arranged on the oil supplementing ways; an oil-adding valve is connected between the oil way A and the oil way B through an oil pipe, and the oil-adding valve is communicated to an oil tank; the A oil way and/or the B oil way are/is provided with a throttle valve and/or a one-way sequence valve; the invention can solve the problems of uncontrollable pressure fluctuation and oil temperature of the closed hydraulic system under the low-load working condition, and provides a guarantee for continuous and stable operation of the closed hydraulic system.

Drawings

FIG. 1 is a schematic diagram of a closed hydraulic system of the prior art;

FIG. 2 is a schematic diagram of a closed hydraulic system according to the present invention, wherein throttle valves are disposed in oil passages A, B;

FIG. 3 is a schematic view of a closed hydraulic system according to the present invention, wherein the closed hydraulic system is provided with one-way throttle valves in the oil paths A, B;

fig. 4 is a schematic structural part view of a closed hydraulic system of the present invention, in which one-way sequence valves are disposed in oil paths A, B.

Reference numerals in the schematic drawings illustrate:

1. an oil tank; 2. b, an oil way; 3. a hydraulic motor; 4. a make-up pump; 5. an oil circuit pressure supplementing instrument; 6. an oil supplementing way; 7. b, an oil way pressure instrument; 8. b an oil circuit oil supplementing valve; 9. a main hydraulic pump; 10. a prime mover; 11. a variable control structure; 12. an oil way pressure instrument; 13. an oil circuit oil supplementing valve; 14. an oil-adding valve; 15. a more oil pressure valve; 16. a cooler; 17. an oil way A; 18. an oil filter; 19. an oil way throttle valve; 20. b an oil way throttle valve; 21. a oil way one-way throttle valve; 22. b oil way one-way throttle valve; 23. a, an oil way one-way sequence valve; 24. and B, an oil way one-way sequence valve.

Detailed Description

The following detailed description and example embodiments of the invention may be better understood when read in conjunction with the accompanying drawings, in which elements and features of the invention are identified by reference numerals.

As shown in fig. 1, in general, a closed hydraulic system includes: the hydraulic system comprises an oil tank 1, a B oil circuit 2, a hydraulic motor 3, an oil supplementing pump 4, an oil supplementing circuit pressure instrument 5, an oil supplementing circuit 6, a B oil circuit pressure instrument 7, a B oil circuit oil supplementing valve 8, a main hydraulic pump 9, a prime motor 10, a variable control structure 11, an A oil circuit pressure instrument 12, an A oil circuit oil supplementing valve 13, an oil adding valve 14, an oil adding pressure valve 15, a cooler 16, an A oil circuit 17 and an oil filter 18. The prime motor is generally an electric motor, the oil supplementing pump 4 and the main hydraulic pump 9 are driven through a coupling, the oil supplementing pump 4 absorbs oil from the oil tank 1, and oil is conveyed to a low pressure side oil path of the main hydraulic pump 9 through an oil supplementing valve. When oil flows from the oil line A17 to the oil line B2 through the hydraulic motor 3, the oil line A17 is an oil outlet line of the main hydraulic pump 9, the oil line B2 is an oil inlet line of the main hydraulic pump 9, at the moment, the pressure of the oil line A17 is higher than that of the oil line B2, and the output oil of the oil supplementing pump 4 is output to the oil line B2 through the oil supplementing valve 8 of the oil line B2; conversely, when the flow direction of the oil is changed, the output oil of the oil supplementing pump 4 is output to the oil line A17 through the oil supplementing valve A17, the oil output by the oil supplementing pump 4 flows to the oil pressure valve 15 after passing through the oil pressure valve 14 except the leakage in the supplementing system, and returns to the oil tank through the cooler 16 and the oil filter 18; the oil-adding valve 14 in this embodiment is a hydraulic reversing valve. Under the low load working condition, the load of the hydraulic motor 3 is small, so that the working pressure difference of the hydraulic motor 3 is small, the pressure difference of the oil way 17A and the oil way B is small and is generally less than or equal to 1MPa, as can be seen from the schematic diagram of the hydraulic system in fig. 2, the oil valve 14 is in an initial state, the valve core is acted by spring force at two ends and is in a middle position, the pressure of the oil way 17A acts on the left cavity of the valve core, the pressure of the oil way 2B acts on the right cavity of the valve core, the reversing of the valve core is controlled by the pressure difference delta P of the oil way 17A and the oil way 2B, when the hydraulic pressure of the delta P acts on the valve core is larger than the spring force acting on the valve core, the valve core is reversed to the left position or the right position and is kept, and when the hydraulic pressure of the delta P acts on the valve core is not larger than the spring force acting on the valve core, the valve core can generate misoperation, the misoperation of the valve core can not be kept in the left position or the middle position is not acted, or the operation of the valve core is not reliable, or the operation of the valve core is not controlled, the pressure of the oil way 6 is influenced, the pressure of the oil way 17 and the pressure of the oil way 2B is stably fluctuated, and the stable operation is influenced.

The application method of the closed hydraulic system comprises the steps of adding a throttle valve 19 to an oil way A17 and a throttle valve 20 to an oil way B of the closed hydraulic system, or adding a one-way throttle valve 21 to the oil way A17 and a one-way throttle valve 22 to the oil way B, or adding a one-way sequence valve 23 to the oil way A17 and a one-way sequence valve 24 to the oil way B; or a throttle valve 19 is added to the A oil way 17, or a one-way throttle valve 21 is added to the A oil way 17, or a one-way sequence valve 23 is added to the A oil way 17; or a throttle valve 20 is added to the B oil way 2 of the closed hydraulic system, or a one-way throttle valve 22 is added to the B oil way 2, or a one-way sequence valve 24 is added to the B oil way 2.

The closed hydraulic system is under a low-load working condition: if the oil flows from the oil line a 17 to the oil line B2 via the hydraulic motor 3 only during the operation of the system, the throttle valve 19, the one-way throttle valve 21, or the one-way sequence valve 23 may be added to the oil line a 17 only.

If the oil flows from the B oil path 2 to the a oil path 17 through the hydraulic motor 3 only when the system is in operation, the throttle valve 20, the one-way throttle valve 22 or the one-way sequence valve 24 can be added to the B oil path 2 only.

If the oil liquid has two working conditions of flowing from the oil line A17 to the oil line B2 through the hydraulic motor 3 and flowing from the oil line B2 to the oil line A17 through the hydraulic motor 3 during the working of the system, a throttle valve 19 can be added to the oil line A17 alone or a throttle valve 20 can be added to the oil line B2 alone; or simultaneously adding a throttle valve 19 to the A oil path 17 and a throttle valve 20 to the B oil path 2 (as shown in FIG. 2); or simultaneously, a one-way throttle valve 21 is added to the oil way A17, and a one-way throttle valve 22 is added to the oil way B2 (as shown in figure 3); or simultaneously, a one-way sequence valve 23 is added to the oil line A17, and a one-way sequence valve 24 is added to the oil line B2 (as shown in figure 4). The differential delta P of the pressure between the A oil way 17 and the B oil way 2 of the main hydraulic pump 9 can be increased by adding a throttle valve or a one-way sequence valve, so that the hydraulic pressure acting on the valve core of the oil-filling valve 14 by delta P is larger than the spring force acting on the valve core by a spring, thereby ensuring that the valve core of the oil-filling valve 14 can act as required and avoiding misoperation. The throttle valve or the one-way throttle valve can change the pressure loss flowing through the throttle valve by changing the size of the section of the flow passage or the length of the flow passage; the throttle valve or the one-way throttle valve is a hydraulic throttle valve or a one-way hydraulic throttle valve or an element capable of changing the size of the section of the flow passage or the length of the flow passage; the throttle valve or the one-way throttle valve can be manually adjusted or not manually adjusted; the throttle valve or the one-way throttle valve adopts a pipeline installation form or a plate installation form; and the specifications of the throttle valve or the one-way throttle valve are matched and selected according to the flow of the closed hydraulic system. The one-way sequence valve adopts a leakage mode of leakage, the external oil leakage is directly returned to the oil tank, the sequence valve adopts a pipeline installation mode or a plate installation mode, and the pressure set value of the sequence valve can be manually adjusted; the specification of the sequence valve can be matched and selected according to the flow of the closed hydraulic system. The plate type mounting valve is selected and used, a plate type mounting special valve block is used, and the plate type mounting valve is mounted on the valve block.

The invention has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will be understood that various modifications and changes may be made without departing from the scope of the invention as defined by the appended claims. The detailed description and drawings are to be regarded in an illustrative rather than a restrictive sense, and if any such modifications and variations are desired to be included within the scope of the invention described herein. Furthermore, the background art is intended to illustrate the status and meaning of the development of the technology and is not intended to limit the invention or the application and field of application of the invention.

Claims

1. The closed hydraulic system is characterized by comprising a hydraulic pump (9), a hydraulic actuator (3) and an oil tank (1), wherein one end of the hydraulic pump (9) is communicated with one end of the hydraulic actuator (3) through an A oil way (17), and one end of the hydraulic pump (9) is communicated with one end of the hydraulic actuator (3) through a B oil way (2); the oil way A (17) and the oil way B (2) are respectively connected with the oil tank (1) through an oil supplementing way (6), and an oil supplementing pump (4) is arranged on the oil supplementing way (6); an oil-adding valve (14) is connected between the oil way A (17) and the oil way B (2) through an oil pipe, and the oil-adding valve (14) is communicated to the oil tank (1); a throttle valve and/or a one-way sequence valve are arranged on the oil way A (17) and/or the oil way B (2);

the oil flows from the oil way A (17) to the oil way B (2), and a throttle valve and/or a one-way sequence valve are arranged on the oil way A (17);

and/or oil flows from the oil way B (2) to the oil way A (17), and a throttle valve and/or a one-way sequence valve are arranged on the oil way B (2);

the throttle valve is a hydraulic throttle valve;

the hydraulic pump (9) is a variable pump, and a variable control mechanism is arranged on the hydraulic pump (9).

2. A closed hydraulic system according to claim 1, wherein the throttle valve and/or the one-way sequence valve are mounted by piping or plate mounted.

3. A closed hydraulic system according to claim 1, characterized in that the oil supplementing pump (4) and the hydraulic pump (9) are connected by means of a through shaft, the power input end of which is connected to the prime mover (10).

4. A closed hydraulic system according to claim 1, characterized in that the oil compensating path (6) is provided with an a-path oil compensating valve (13) and a B-path oil compensating valve (8), and the oil compensating path (6) between the a-path oil compensating valve (13) and the B-path oil compensating valve (8) is communicated with the oil tank (1) through the oil compensating pump (4); the oil-way oil-compensating valve A (13) and the oil-way oil-compensating valve B (8) are two reverse series check valves.

5. A closed hydraulic system according to claim 1, characterized in that the oil-filled valve (14) is connected to the oil tank (1) via an oil-filled pressure valve (15).

6. A closed hydraulic system according to claim 5, characterized in that the oil-filled pressure valve (15) is an overflow valve, the outlet of which is provided with a cooler and an oil filter.

7. A closed hydraulic system according to any one of claims 1-6, characterised in that the a oil circuit (17) and/or the B oil circuit (2) and/or the oil compensating circuit (6) are provided with pressure gauges and/or pressure transmitters and/or pressure switches.