Load-sensing multi-way valve with variable differential pressure

Abstract

The present invention discloses a load-sensing multi-way valve with a variable differential pressure, where each valve group uses a new element: an electro-hydraulic pressure compensation valve, so as to implement continuous real-time adjustment and control of compensated differential pressure and real-time position feedback and monitoring of a compensation valve trim, and overcome a flow mismatch problem of a conventional LS system in a flow saturation working condition and problems of a fixed shunting proportion of an LUDV system and poor operation coordination of actuators. The load-sensing multi-way valve with a variable differential pressure disclosed in the present invention has advantages such as strong working condition applicability, high flow distribution accuracy, and strong technicality.

Claims

1. A load-sensing multi-way valve with a variable differential pressure, comprising at least one valve group, wherein each valve group comprises an oil-feed passage (1), a pilot-operated oil-feed passage (2), a pilot-operated oil-return passage (3), a load-sensing oil passage (4), an oil-return passage (5), a reversing valve (6), a check valve (7), a shuttle valve (8), a first one-way overflow valve (9), and a second one-way overflow valve (10); and an electro-hydraulic pressure compensation valve (11) and a first pilot-operated pressure reducing valve (12) are disposed in the load-sensing multi-way valve with a variable differential pressure, wherein the electro-hydraulic pressure compensation valve comprises a displacement sensor (13), a compensation valve body (14), a compensation valve trim (15), a spring (16), an oil inlet (A), an oil outlet (B), a first control cavity (P.sub.F), a second control cavity (P.sub.E), and a third control cavity (P.sub.G), wherein the compensation valve trim is arranged inside the compensation valve body, and comprises three spool lands: a first spool land (17), a second spool land (18), and a third spool land (19); one end of the spring acts on a left end surface (C) of the compensation valve trim, and the other end thereof acts on the compensation valve body and forms the first control cavity (P.sub.F) with the first spool land of the compensation valve trim; the displacement sensor is arranged on the compensation valve trim through the compensation valve body, and directly detects a position X and a velocity XV of the valve trim; and the second spool land and the third spool land of the compensation valve trim respectively form the third control cavity (P.sub.G) and the second control cavity (P.sub.E) with the compensation valve body; and the electro-hydraulic pressure compensation valve is connected to the system in the following two manners: a connection manner 1: the electro-hydraulic pressure compensation valve is arranged before the reversing valve; the oil inlet (A) of the electro-hydraulic pressure compensation valve is communicated with the oil-feed passage; the oil outlet (B) of the electro-hydraulic pressure compensation valve is communicated with an oil inlet of the check valve and the control cavity (P.sub.E) of the electro-hydraulic pressure compensation valve; the control cavity (P.sub.G) of the electro-hydraulic pressure compensation valve is communicated with a working oil port of the first pilot-operated pressure reducing valve; an oil inlet and an oil outlet of the first pilot-operated pressure reducing valve are respectively communicated with the pilot-operated oil-feed passage and the pilot-operated oil-return passage; the load-sensing oil passage is communicated with an oil detection port (F) of the reversing valve and the control cavity (P.sub.F) of the electro-hydraulic pressure compensation valve through the shuttle valve; and a connection manner 2: the electro-hydraulic pressure compensation valve is arranged after the reversing valve; an oil outlet of the check valve is communicated with the oil inlet (A) of the electro-hydraulic pressure compensation valve and the control cavity (P.sub.F) of the electro-hydraulic pressure compensation valve; the control cavity (P.sub.E) of the electro-hydraulic pressure compensation valve is communicated with the load-sensing oil passage; the control cavity (P.sub.G) of the electro-hydraulic pressure compensation valve is communicated with the working oil port of the first pilot-operated pressure reducing valve; and the oil inlet and the oil outlet of the first pilot-operated pressure reducing valve are respectively communicated with the pilot-operated oil-feed passage and the pilot-operated oil-return passage.

2. The load-sensing multi-way valve with a variable differential pressure according to claim 1, wherein the electro-hydraulic pressure compensation valve is one of a normally opened type and a normally closed type.

3. The load-sensing multi-way valve with a variable differential pressure according to claim 1, wherein in the compensation valve trim, an external diameter d.sub.1 of the first spool land and an external diameter d.sub.3 of the third spool land are the same, and are both less than an external diameter d.sub.2 of the second spool land.

4. The load-sensing multi-way valve with a variable differential pressure according to claim 1, wherein the reversing valve is one of an electro-proportional reversing valve, a hydraulic control reversing valve, and an electro-hydraulic proportional reversing valve.

5. The load-sensing multi-way valve with a variable differential pressure according to claim 1, wherein when the reversing valve is an electro-hydraulic proportional reversing valve, the load-sensing multi-way valve with a variable differential pressure further comprises a second pilot-operated pressure reducing valve (20) and a third pilot-operated pressure reducing valve (21); an oil inlet and an oil outlet of the second pilot-operated pressure reducing valve and an oil inlet and an oil outlet of the third pilot-operated pressure reducing valve are respectively communicated with the pilot-operated oil-feed passage and the pilot-operated oil-return passage; and working oil ports of the second pilot-operated pressure reducing valve and the third pilot-operated pressure reducing valve are respectively communicated with two ends of the reversing valve, and the second pilot-operated pressure reducing valve (20) and the third pilot-operated pressure reducing valve (21) output different pressure according to different control signals to control directions and displacements of the reversing valve.

6. The load-sensing multi-way valve with a variable differential pressure according to claim 1, wherein the multi-way valve is a single valve or multiple valves; and when the multi-way valve is multiple valves, the multiple valves are communicated with multiple actuators, and the multiple valves share the same oil-feed passage, pilot-operated oil-feed passage, pilot-operated oil-return passage, load-sensing oil passage, and oil-return passage, and have same elements and a same structure connection relationship.

7. The load-sensing multi-way valve with a variable differential pressure according to claim 1, further comprising a fourth pilot-operated pressure reducing valve (22), wherein the electro-hydraulic pressure compensation valve (11) further comprises a fourth control cavity (P.sub.H); the second spool land of the compensation valve trim forms the fourth control cavity (P.sub.H) with the compensation valve body; the fourth control cavity (P.sub.H) of the electro-hydraulic pressure compensation valve is communicated with a working oil port of the fourth pilot-operated pressure reducing valve (22); and an oil inlet and an oil outlet of the fourth pilot-operated pressure reducing valve (22) are respectively communicated with the pilot-operated oil-feed passage and the pilot-operated oil-return passage.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a compensated differential pressure control curve of a conventional pressure compensation valve;

(2) FIG. 2 is a schematic diagram of a system according to Embodiment 1 of the present invention;

(3) FIG. 3 is a schematic structural diagram of an electro-hydraulic pressure compensation valve according to the present invention;

(4) FIG. 4 is a structural diagram of a valve trim of an electro-hydraulic pressure compensation valve according to the present invention;

(5) FIG. 5 is a compensated differential pressure control curve of an electro-hydraulic pressure compensation valve according to the present invention; and

(6) FIG. 6 is a schematic diagram of a system according to Embodiment 2 of the present invention.

(7) FIG. 7 is a schematic diagram of a system according to Embodiment 3 of the present invention; and

(8) FIG. 8 is another schematic structural diagram of an electro-hydraulic pressure compensation valve according to the present invention.

(9) In the figures: 1-oil-feed passage; 2-pilot-operated oil-feed passage; 3-pilot-operated oil-return passage; 4-load-sensing oil passage; 5-oil-return passage; 6-reversing valve; 7-check valve; 8-shuttle valve; 9-first one-way overflow valve; 10-second one-way overflow valve; 11-electro-hydraulic pressure compensation valve; 12-first pilot-operated pressure reducing valve; 13-displacement sensor; 14-compensation valve body; 15-compensation valve trim; 16-spring; 17-first spool land; 18-second spool land; 19-third spool land; 20-second pilot-operated pressure reducing valve; 21-third pilot-operated pressure reducing valve; and 22-fourth pilot-operated pressure reducing valve.

DETAILED DESCRIPTION OF EMBODIMENTS

(10) The following further describes in detail the present invention with reference to FIG. 1 to FIG. 6.

Embodiment 1

(11) A load-sensing multi-way valve with a variable differential pressure is provided, and includes at least one valve group, where each valve group includes an oil-feed passage 1, a pilot-operated oil-feed passage 2, a pilot-operated oil-return passage 3, a load-sensing oil passage 4, an oil-return passage 5, a reversing valve 6, a check valve 7, a shuttle valve 8, a first one-way overflow valve 9, and a second one-way overflow valve 10, and the load-sensing multi-way valve with a variable differential pressure further includes an electro-hydraulic pressure compensation valve 11 and a first pilot-operated pressure reducing valve 12.

(12) As shown in FIG. 2, the electro-hydraulic pressure compensation valve 11 is arranged before the reversing valve 6; an oil inlet A of the electro-hydraulic pressure compensation valve 11 is communicated with the oil-feed passage 1; an oil outlet B of the electro-hydraulic pressure compensation valve 11 is communicated with an oil inlet of the check valve 7 and a second control cavity P.sub.E of the electro-hydraulic pressure compensation valve 11; a third control cavity P.sub.G of the electro-hydraulic pressure compensation valve 11 is communicated with a working oil port of the first pilot-operated pressure reducing valve 12; an oil inlet and an oil outlet of the first pilot-operated pressure reducing valve 12 are respectively communicated with the pilot-operated oil-feed passage 2 and the pilot-operated oil-return passage 3; and the load-sensing oil passage 4 is communicated with an oil detection port F of the reversing valve 6 and a first control cavity P.sub.E of the electro-hydraulic pressure compensation valve through the shuttle valve 8.

(13) As shown in FIG. 3 and FIG. 4, the electro-hydraulic pressure compensation valve 11 includes a displacement sensor 13, a compensation valve body 14, a compensation valve trim 15, a spring 16, an oil inlet A, an oil outlet B, a first control cavity P.sub.F, a second control cavity P.sub.E, and a third control cavity P.sub.G, where the compensation valve trim 15 is arranged inside the compensation valve body 14, and includes a first spool land 17, a second spool land 18, and a third spool land 19; one end of the spring 16 acts on a left end surface C of the compensation valve trim 15, and the other end thereof acts on the compensation valve body 14 and forms the first control cavity P.sub.F with the first spool land 17 of the compensation valve trim 15; the displacement sensor 13 is arranged on the compensation valve trim 15 through the compensation valve body 14, and directly detects a position X and a velocity XV of the valve trim; and the second spool land 18 and the third spool land 19 of the compensation valve trim 15 respectively form the third control cavity P.sub.G and the second control cavity P.sub.E with the compensation valve body 14.

(14) The electro-hydraulic pressure compensation valve 11 is one of a normally opened type and a normally closed type.

(15) In the compensation valve trim 15, an external diameter d.sub.1 of the first spool land 17 and an external diameter d.sub.3 of the third spool land 19 are the same, and are both less than an external diameter d.sub.2 of the second spool land 18.

(16) The reversing valve 6 is one of an electro-proportional reversing valve, a hydraulic control reversing valve, and an electro-hydraulic proportional reversing valve.

(17) The multi-way valve in the present invention may be a single valve or multiple valves; and when the multi-way valve is multiple valves, the multiple valves are communicated with multiple actuators, and the multiple valves share the same oil-feed passage 1, pilot-operated oil-feed passage 2, pilot-operated oil-return passage 3, load-sensing oil passage 4, and oil-return passage 5, and have same elements and a same structure connection relationship.

(18) An operating principle and process of changing compensated differential pressure in the system are as follows:

(19) A force balance equation of the compensation valve trim 15 can be obtained according to the external diameters of the foregoing compensation valve trim 15:

(20) $F_s+p_1•\frac{\pi d_1^2}{4}=p_2•\frac{\pi d_3^2}{4}+p_3•\frac{\pi \left(d_2^2-d_3^2\right)}{4}$

(21) It can be learned from the foregoing formula, stress of the compensation valve trim 15 mainly includes four parts: spring force F.sub.s, pressure p.sub.2 before the reversing valve, pressure p.sub.1 after the reversing valve, and output pressure p.sub.3 of the first pilot-operated pressure reducing valve, and differential pressure before and after the reversing valve is operating differential pressure Δp of the compensation valve. Therefore, compensated differential pressure Δp of the compensation valve compensation is as follows:

(22) $\Delta p=F_s-p_3•\frac{\left(d_2^2-d_3^2\right)}{4}=p_2-p_1$

(23) Assuming that the spring force F.sub.s is unchanged, it can be learned from the foregoing formula that, the compensated differential pressure Δp of the compensation valve is related to the output pressure p.sub.3 of the first pilot-operated pressure reducing valve. When a control signal I.sub.signal of the first pilot-operated pressure reducing valve is zero, the output pressure p.sub.3 of the first pilot-operated pressure reducing valve is zero, and the compensated differential pressure of the compensation valve is the highest; and an operating mode of the pressure compensation valve is the same as that of a conventional pressure compensation valve. When the first pilot-operated pressure reducing valve outputs pressure p.sub.3, the compensated differential pressure of the compensation valve begins to decrease, and is in a linear relationship with the control signal I.sub.signal of the pressure reducing valve, so as to implement continuous control of a change in the compensated differential pressure of the compensation valve. A compensated differential pressure control curve is shown in FIG. 5.

Embodiment 2

(24) As shown in FIG. 6, the present invention provides a second implementation of the load-sensing multi-way valve with a variable differential pressure; a structural composition is the same as that in Embodiment 1; a difference lies in that: A connection manner between the electro-hydraulic pressure compensation valve 11 and the system is changed, and the reversing valve 6 is an electro-hydraulic proportional reversing valve.

(25) The electro-hydraulic pressure compensation valve 11 is arranged after the reversing valve 6; an oil outlet of the check valve 7 is communicated with the oil inlet A of the electro-hydraulic pressure compensation valve 11 and the second control cavity P.sub.E of the electro-hydraulic pressure compensation valve 11; the first control cavity P.sub.F of the electro-hydraulic pressure compensation valve 11 is communicated with the load-sensing oil passage 4; the third control cavity P.sub.G of the electro-hydraulic pressure compensation valve 11 is communicated with the working oil port of the first pilot-operated pressure reducing valve 12; and the oil inlet and the oil outlet of the first pilot-operated pressure reducing valve 12 are respectively communicated with the pilot-operated oil-feed passage 2 and the pilot-operated oil-return passage 3.

(26) When the reversing valve 6 is an electro-hydraulic proportional reversing valve, the system further includes a second pilot-operated pressure reducing valve 20, and a third pilot-operated pressure reducing valve 21, where an oil inlet and an oil outlet of the second pilot-operated pressure reducing valve 20 and the third pilot-operated pressure reducing valve 21 are respectively communicated with the pilot-operated oil-feed passage 2 and the pilot-operated oil-return passage 3; and working oil ports of the second pilot-operated pressure reducing valve 20 and the third pilot-operated pressure reducing valve 21 are respectively communicated with two ends of the reversing valve 6, and the second pilot-operated pressure reducing valve 20 and the third pilot-operated pressure reducing valve 21 output different pressure according to different control signals to control directions and displacements of the reversing valve 6.

Embodiment 3

(27) As shown in FIG. 7 and FIG. 8, the present invention provides a third implementation of the load-sensing multi-way valve with a variable differential pressure. A connection manner of the system is the same as that in Embodiment 1, and a difference lies in that: The load-sensing multi-way valve with a variable differential pressure further includes a fourth pilot-operated pressure reducing valve 22, where the electro-hydraulic pressure compensation valve 11 further includes a fourth control cavity P.sub.H. The second spool land of the compensation valve trim forms the fourth control cavity P.sub.H with the compensation valve body; the fourth control cavity P.sub.H of the electro-hydraulic pressure compensation valve is communicated with a working oil port of the fourth pilot-operated pressure reducing valve; and an oil inlet and an oil outlet of the fourth pilot-operated pressure reducing valve are respectively communicated with the pilot-operated oil-feed passage and the pilot-operated oil-return passage.

(28) In a motion process of the valve trim, due to impact of dynamic flow force, its direction makes the valve trim tend to be closed. As shown in FIG. 8, features of this embodiment are provided: the fourth pilot-operated pressure reducing valve 22 and the fourth control cavity P.sub.H, and the fourth pilot-operated pressure reducing valve 22 is controlled to output pressure, so as to implement real-time compensation of dynamic flow force exerted on the valve trim in the motion process of the compensation valve trim. In addition, when a single actuator conducts an operation, the fourth pilot-operated pressure reducing valve 22 is controlled to output pressure, which can make the electro-hydraulic pressure compensation valve 11 be in a normally open failure state, to reduce a throttling loss of the system.