CN112065789A

CN112065789A - Closed hydraulic system

Info

Publication number: CN112065789A
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: 2020-12-11
Anticipated expiration: 2040-09-11
Also published as: CN112065789B

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 circuit A and the oil circuit B are respectively connected with an oil tank through oil supplementing circuits, and oil supplementing pumps are arranged on the oil supplementing circuits; an oil outlet valve is connected between the oil path A and the oil path B through an oil pipe and communicated to an oil tank; a throttle valve and/or a one-way sequence valve are/is arranged on the oil path A and/or the oil path B; the invention can solve the problem that the closed hydraulic system is uncontrollable in pressure fluctuation and oil temperature under the low-load working condition, and provides guarantee for the 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 sites 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 a 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 and are not communicated with the outside, oil liquid in the system is self-circulated, the contact probability with air is low, pollutants and water vapor are not easy to be mixed, and the oil tank can be designed to be small.

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 gauge, etc., under a low-load condition, when a pressure difference Δ P between two working oil lines of the main hydraulic pump is less than or equal to 1MPa, a hydraulic pressure of the Δ P acting on a spool of the oil compensating valve is insufficient to completely overcome a spring force of a spring acting on the spool, so that the spool generates a malfunction, which includes that the spool cannot be maintained at a left position or a right position, or the spool is in a middle position and does not act, or the spool acts unreliably, or the spool acts uncontrollably, so that pressure fluctuation and oil temperature of the system are uncontrollable, and continuous and stable operation is affected.

Disclosure of Invention

1. Technical problem to be solved by the invention

The invention aims to solve the problem that in the prior art, the closed hydraulic system has the influence on continuous and stable operation due to system pressure fluctuation and uncontrollable oil temperature because a valve core of an oil valve has misoperation under the low-load working condition.

2. Technical scheme

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

the invention discloses a closed hydraulic system which 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 circuit A and the oil circuit B are respectively connected with an oil tank through oil supplementing circuits, and oil supplementing pumps are arranged on the oil supplementing circuits; an oil-returning valve is connected between the oil circuit A and the oil circuit B through an oil pipe and communicated to an oil tank, the oil-returning valve can replace hot oil in the system, and redundant oil output by the oil-supplementing pump flows to the oil tank from the oil-returning valve; and a throttle valve and/or a one-way sequence valve are/is arranged on the oil path A and/or the oil path B.

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

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

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

Alternatively, at low load conditions: if the oil liquid flows from the oil circuit A to the oil circuit B through the hydraulic motor when the system works, only the one-way sequence valve is added to the oil circuit A; if the oil liquid flows to the oil circuit A from the oil circuit B through the hydraulic motor when the system works, only a one-way sequence valve is added to the oil circuit B; if the oil liquid has two working conditions that the oil liquid flows from the oil circuit A to the oil circuit B through the hydraulic motor and flows from the oil circuit B to the oil circuit A through the hydraulic motor when the system works, the oil circuit A and the oil circuit B both need to be additionally provided with one-way sequence valves. By adding the one-way sequence valve, the pressure difference delta P between the oil circuit A and the oil circuit B of the working oil circuit of the main hydraulic pump is increased, so that the hydraulic pressure of the delta P acting on the valve core is larger than the spring force of the spring acting on the valve core, and the valve core of the oil-filling valve can be ensured to act as required. The leakage form of the one-way sequence valve is leakage, and leaked oil directly returns 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 a positive angle and a negative angle, two oil paths with opposite flow directions are formed, so that the steering of the hydraulic motor is changed.

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

Preferably, an oil supplementing valve of an oil way A and an oil supplementing valve of an oil way B are arranged on the oil supplementing circuit, and an oil supplementing circuit between the oil supplementing valve of the oil way A and the oil supplementing valve of the oil way B is communicated with the oil tank through an oil supplementing pump; the oil supplementing valve of the oil circuit A and the oil supplementing valve of the oil circuit B are two check valves which are connected in series in an opposite direction, and oil is supplemented to the oil circuit A and the oil circuit B respectively.

Preferably, the oil drain valve is connected to the oil tank via an oil drain pressure valve.

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

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

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 circuit A and the oil circuit B are respectively connected with an oil tank through oil supplementing circuits, and oil supplementing pumps are arranged on the oil supplementing circuits; an oil outlet valve is connected between the oil path A and the oil path B through an oil pipe and communicated to an oil tank; a throttle valve and/or a one-way sequence valve are/is arranged on the oil path A and/or the oil path B; the invention can solve the problem that the closed hydraulic system is uncontrollable in pressure fluctuation and oil temperature under the low-load working condition, and provides guarantee for the continuous and stable operation of the closed hydraulic system.

Drawings

Fig. 1 is a schematic structural diagram of a closed hydraulic system in general in the prior art;

FIG. 2 is a schematic structural diagram of a closed hydraulic system provided with throttle valves at A, B oil paths;

FIG. 3 is a partial schematic view of a closed hydraulic system of the present invention, in which a check throttle is provided at both oil passages A, B;

fig. 4 is a partial schematic view of a closed hydraulic system provided with one-way sequence valves in oil paths A, B according to the present invention.

The reference numerals in the schematic drawings illustrate:

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

Detailed Description

The detailed description and exemplary embodiments of the invention will be better understood when read in conjunction with the appended drawings, where the elements and features of the invention are identified by reference numerals.

As shown in fig. 1, in general, a closed-type hydraulic system includes: the hydraulic control system comprises an oil tank 1, an oil circuit B2, a hydraulic motor 3, an oil supplementing pump 4, an oil supplementing circuit pressure instrument 5, an oil supplementing circuit 6, an oil circuit B pressure instrument 7, an oil supplementing valve B8, a main hydraulic pump 9, a prime motor 10, a variable control structure 11, an oil circuit A pressure instrument 12, an oil supplementing valve A13, an oil supplementing valve 14, an oil supplementing pressure valve 15, a cooler 16, an oil circuit A17 and an oil filter 18. The prime motor is generally an electric motor, an oil supplementing pump 4 and a main hydraulic pump 9 are driven through a coupler, the oil supplementing pump 4 absorbs oil from an oil tank 1, and the oil is conveyed to a low-pressure side oil circuit of the main hydraulic pump 9 through an oil supplementing valve. When oil flows from the oil circuit A17 to the oil circuit B2 through the hydraulic motor 3, the oil circuit A17 is an oil outlet oil circuit of the main hydraulic pump 9, the oil circuit B2 is an oil inlet oil circuit of the main hydraulic pump 9, the pressure of the oil circuit A17 is higher than that of the oil circuit B2, and the output oil of the oil supplementing pump 4 is output to the oil circuit B2 through an oil supplementing valve 8 of the oil circuit B2; on the contrary, when the oil flow direction changes, the output oil of the oil supply pump 4 is output to the oil passage A17 through the oil supply valve A17, and except the leakage in the oil supply system, the rest oil output by the oil supply pump 4 flows to the oil supply pressure valve 15 through the oil change valve 14, and then returns to the oil tank through the cooler 16 and the oil filter 18; in this embodiment, the oil control valve 14 is a hydraulic change valve. Under the working condition of low load, the load of the hydraulic motor 3 is very small, so the working pressure difference of the hydraulic motor 3 is very small, so that the pressure difference between the oil circuit A17 and the oil circuit B is very small, generally less than or equal to 1MPa, as can be seen from the schematic diagram of the hydraulic system in figure 2, the valve core of the oil valve 14 is in an initial state, the valve core is acted by spring forces at two ends and is in a neutral position, when the system operates, the pressure of the oil circuit A17 is acted on a left cavity of the valve core, the pressure of the oil circuit B2 is acted on a right cavity of the valve core, the reversing of the valve core is controlled by the pressure difference delta P between the oil circuit A17 and the oil circuit B2, when the hydraulic pressure of the delta P acted on the valve core is greater than the spring force acted on the valve core by the spring, the valve core is reversed to the left position or the right position and is kept, when the hydraulic pressure of the delta P, or the valve core is not moved in the middle position, or the valve core is not moved reliably, or the valve core is not controlled to move, so that the pressure of the oil supplementing circuit 6, the pressure of the oil circuit A17 and the pressure of the oil circuit B2 fluctuate, and the stable operation of the system is influenced.

The use method of the closed hydraulic system comprises the steps that a throttle valve 19 and a throttle valve 20 are added to an oil path A17, or a one-way throttle valve 21 and a one-way throttle valve 22 are added to an oil path A17, or a one-way sequence valve 23 and a one-way sequence valve 24 are added to an oil path B17 of the closed hydraulic system; a throttle valve 19 is added to the oil path A17, a one-way throttle valve 21 is added to the oil path A17, or a one-way sequence valve 23 is added to the oil path A17; or a throttle valve 20 is added to the B oil circuit 2 of the closed hydraulic system, or a one-way throttle valve 22 is added to the B oil circuit 2, or a one-way sequence valve 24 is added to the B oil circuit 2.

The closed hydraulic system is under the low load working condition: if the oil flows from the A oil path 17 to the B oil path 2 only through the hydraulic motor 3 during the system operation, the throttle valve 19, the one-way throttle valve 21 or the one-way sequence valve 23 can be added to the A oil path 17 only.

If the oil flows from the B oil path 2 to the A oil path 17 only through the hydraulic motor 3 during the system 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 that the oil liquid flows from the oil circuit A17 to the oil circuit B2 through the hydraulic motor 3 and flows from the oil circuit B2 to the oil circuit A17 through the hydraulic motor 3 when the system works, a throttle valve 19 can be singly added to the oil circuit A17, or a throttle valve 20 can be singly added to the oil circuit B2; or simultaneously adding a throttle 19 to the A oil path 17 and a throttle 20 to the B oil path 2 (as shown in FIG. 2); or simultaneously adding a one-way throttle valve 21 in the A oil way 17 and a one-way throttle valve 22 in the B oil way 2 (shown in FIG. 3); or simultaneously adding a one-way sequence valve 23 to the A oil way 17 and a one-way sequence valve 24 to the B oil way 2 (as shown in FIG. 4). The throttle valve or the one-way sequence valve can be added to increase the pressure difference delta P between the oil circuit 17A and the oil circuit 2B of the main hydraulic pump 9, so that the hydraulic pressure of the delta P acting on the valve core of the oil change valve 14 is larger than the spring force of the spring acting on the valve core, the valve core of the oil change valve 14 can be ensured to act as required, and the misoperation is avoided. The throttle valve or the one-way throttle valve can change the pressure loss flowing through the throttle valve by changing the section size 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 cross section size or the length of the flow passage; the throttle valve or the one-way throttle valve can be manually adjusted or cannot be manually adjusted; the throttle valve or the one-way throttle valve is mounted in a pipeline mode or a plate mode; and the specification of the throttle valve or the one-way throttle valve is matched and selected according to the flow of the closed hydraulic system. The one-way sequence valve adopts a leakage mode, leaked oil directly returns 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 installation is that a plate-type installation valve is selected, a special valve block for plate-type installation is used, and the plate-type installation valve is installed on the valve block.

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

Claims

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

2. A closed hydraulic system according to claim 1, characterized in that oil flows from the a oil path (17) to the B oil path (2), and a throttle valve and/or a one-way sequence valve are arranged on the a oil path (17);

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

3. A closed hydraulic system according to claim 1, characterized in that the throttle valve is a hydraulic throttle valve; and/or the one-way throttle valve is a one-way hydraulic throttle valve.

4. A closed hydraulic system according to claim 1, characterized in that the throttle valve and/or the one-way sequence valve are mounted by means of a line or plate.

5. A closed hydraulic system according to claim 1, characterized in that the hydraulic pump (9) is a variable displacement pump, and that the hydraulic pump (9) is provided with a variable control mechanism.

6. Closed hydraulic system according to claim 1, characterized in that the oil replenishment pump (4) and the hydraulic pump (9) are connected by a through shaft, the power input of which is connected to the prime mover (10).

7. The closed hydraulic system according to claim 1, characterized in that an oil supply path A (13) and an oil supply path B (8) are arranged on the oil supply path (6), and the oil supply path (6) between the oil supply path A (13) and the oil supply path B (8) is communicated with the oil tank (1) through an oil supply pump (4); the oil circuit A oil circuit oil supplementing valve (13) and the oil circuit B oil supplementing valve (8) are two one-way valves which are connected in series in an opposite direction.

8. Closed hydraulic system according to claim 1, characterized in that the oil-scavenging valve (14) is connected to the tank (1) via an oil-scavenging pressure valve (15).

9. Closed hydraulic system according to claim 8, characterized in that the oil spill valve is an overflow valve, the outlet of which is provided with a cooler and an oil filter.

10. The closed hydraulic system according to any one of claims 1 to 9, characterized in that a pressure gauge and/or a pressure transmitter and/or a pressure switch are arranged on the oil circuit A (17) and/or the oil circuit B (2) and/or the oil supply circuit (6).