CN116241523A

CN116241523A - Electric control center-closing multi-way valve, full-variable hydraulic system and loader

Info

Publication number: CN116241523A
Application number: CN202310259958.1A
Authority: CN
Inventors: 乔战战; 马鹏鹏; 张安民; 范小童; 孙志远; 赵锦
Original assignee: Science and Technology Branch of XCMG
Current assignee: Science and Technology Branch of XCMG
Priority date: 2023-03-17
Filing date: 2023-03-17
Publication date: 2023-06-09

Abstract

The invention discloses an electric control closed center multi-way valve, a full variable hydraulic system and a loader, wherein the electric control closed center multi-way valve comprises a first main valve core and a second main valve core; when the first main valve core and the second main valve core do not act, the input oil port and the output oil ports A1 and B1 are separated through the first main valve core, and the input oil port and the output oil ports A2 and B2 are separated through the second main valve core; when the first main valve core and the second main valve core act, hydraulic oil enters the oil duct A1B1 and the oil duct A2B2 through the sixth check valve and the third check valve respectively, and the oil duct A1B1 and the oil duct A2B2 realize the on-off of an oil outlet through the first main valve core and the second main valve core respectively; the oil duct A1B1 and the oil duct A2B2 are respectively fed back to the LS oil port through a fifth check valve and a fourth check valve and are used for supplying hydraulic oil to the variable pump. The LS signal of the multi-way valve is selected by adopting the inlet one-way valve structure, so that the structure of the multi-way valve is simplified, the load of the multi-way valve is lightened, the efficiency is improved, and the complex action of the whole machine is conveniently realized.

Description

Electric control center-closing multi-way valve, full-variable hydraulic system and loader

Technical Field

The invention belongs to the technical field of multi-way valves, and particularly relates to an electric control closed center multi-way valve, a full-variable hydraulic system and a loader.

Background

As a scraper, a loader is used as a construction machine for which efficiency is desired. The shoveling and loading of the loader are realized through a hydraulic system of the loader, which is realized by combining and combining the steering, the movable arm and the tipping bucket, and the hydraulic system of the loader is generally mainly composed of a working hydraulic system and a steering hydraulic system.

The existing loader hydraulic system is provided with a quantitative hydraulic system and a constant-variable hydraulic system. The quantitative hydraulic system can realize independent control of the working hydraulic system and the steering hydraulic system, but the hydraulic system has low efficiency, can not realize combined and combined actions of steering, tipping bucket and movable arm, and has larger bypass throttling loss. The fixed-variable hydraulic system realizes the combination of steering and tipping bucket (movable arm), but due to the adoption of the open-center multi-way valve, the combination of the three or the combination of the movable arm and the tipping bucket cannot be realized, and meanwhile, when a working device acts, the variable pump is in a quantitative state, is output in full displacement, cannot play the regulation function of the variable pump according to the system requirement, and has poorer energy-saving effect.

In the past, the realization mode for realizing the compound action adopts a pressure compensator structure, which often leads to high load of the multi-way valve structure and higher processing and maintenance costs.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides the electric control closed center multi-way valve, the full-variable hydraulic system and the loader.

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

in a first aspect, there is provided an electrically controlled closed center multiple way valve comprising: the valve body is internally provided with a first main valve core and a second main valve core; when the first main valve core and the second main valve core do not act, the input oil port and the output oil ports A1 and B1 are separated by the first main valve core, and the input oil port and the output oil ports A2 and B2 are separated by the second main valve core; when the first main valve core acts, hydraulic oil input from the input oil port enters the oil duct A1B1 through the sixth one-way valve, and the oil duct A1B1 is communicated with the output oil ports A1 and B1 through the first main valve core; when the second main valve core acts, hydraulic oil input from the input oil port enters the oil duct A2B2 through the third one-way valve, and the oil duct A2B2 is communicated with the output oil ports A2 and B2 through the second main valve core; the oil duct A1B1 is fed back to the LS oil port through a fifth one-way valve, and the oil duct A2B2 is fed back to the LS oil port through a fourth one-way valve and used for supplying hydraulic oil to the variable pump.

Further, a first electric proportional pressure reducing valve, a second electric proportional pressure reducing valve, a third electric proportional pressure reducing valve and a fourth electric proportional pressure reducing valve are arranged in the valve body; the output ends of the first electro-proportional pressure reducing valve and the fourth electro-proportional pressure reducing valve are connected with a spring cavity of the first main valve core and used for controlling the movement of the first main valve core; the output ends of the second electric proportional pressure reducing valve and the third electric proportional pressure reducing valve are connected with a spring cavity of the second main valve core and are used for controlling the movement of the second main valve core; when the first to fourth electric proportional reducing valves are not electrified, the first to fourth electric proportional reducing valves are positioned at a first working position, and an oil inlet of the first working position is communicated with an L port of the electric control center closing multi-way valve; when the first to fourth electric proportional reducing valves are powered, the first to fourth electric proportional reducing valves are positioned in a second working position, and an oil inlet of the second working position is communicated with a Pst port of the electric control center-closing multi-way valve.

Further, an LS overflow valve and a constant flow valve are arranged in the valve body; the LS oil port is connected with an oil inlet of the constant flow valve, and an oil outlet of the constant flow valve is communicated with a T port of the electric control closed center multi-way valve; the LS oil port is connected with an oil inlet of the LS overflow valve, and an oil outlet of the LS overflow valve is communicated with the T port; when the load feedback signal of the LS oil port is larger than the set pressure of the LS overflow valve, the LS oil port is communicated with the T port of the electric control closed center multi-way valve through the constant flow valve and the LS overflow valve.

Further, the output oil ports B1 and B2 are communicated through a first one-way valve and a second one-way valve and are used for supplementing oil to a rod cavity of an oil cylinder of the executing element.

In a second aspect, there is provided an all-variable hydraulic system comprising: the variable pump, the priority valve, the steering gear and the electric control center-closing multi-way valve in the first aspect; the variable pump inputs hydraulic oil into a steering hydraulic oil cylinder through a priority valve and a steering gear and is used for controlling steering; the variable pump inputs hydraulic oil into the first executing element and the second executing element through the priority valve and the electric control center closing multi-way valve, and is used for completing single action or compound action; and the LS port of the electric control center closing multi-way valve is connected with the LS3 port of the priority valve and is used for controlling the steering hydraulic cylinder, the first executing element and the second executing element to complete single action or compound action.

Further, the composite action includes: when the electric control handle is operated, electric control signals Xa1 and Xa2 are output to the third electric proportional pressure reducing valve and the fourth electric proportional pressure reducing valve respectively, so that Pst pilot pressure acts on the right ends of the first main valve core and the second main valve core respectively, and the first main valve core and the second main valve core are positioned at the right position; according to the angle of the electric control handle, the displacement proportioning of the first main valve core and the second main valve core is realized.

Further, the composite action includes: the first main valve core and the second main valve core are both reversed to the right, and an oil inlet of the first main valve core is communicated with an A1 port through a choke outlet from a sixth one-way valve to the first main valve core; the load pressure signal of the first execution element is fed back to the LS port through the fifth one-way valve and the LS port; the oil inlet of the second main valve core passes through the third one-way valve to the choke outlet of the second main valve core and is communicated with the A2 port; the second actuating element is communicated with the LS port through the fourth one-way valve, so that a load pressure signal of the second actuating element is fed back to the LS port, the higher pressure is transmitted to the LS port after the two load feedback pressures are compared, the lower pressure is cut off due to the one-way valve, and the variable pump can provide flow according to the opening requirements of the first main valve core and the second main valve core.

In a third aspect, there is provided a loader provided with the electrically controlled closed center multiple valve of the first aspect.

Compared with the prior art, the invention has the beneficial effects that:

(1) According to the invention, the first main valve core and the second main valve core are arranged in the valve body; when the first main valve core and the second main valve core do not act, the input oil port and the output oil ports A1 and B1 are separated by the first main valve core, and the input oil port and the output oil ports A2 and B2 are separated by the second main valve core; when the first main valve core acts, hydraulic oil input from the input oil port enters the oil duct A1B1 through the sixth one-way valve, and the oil duct A1B1 is communicated with the output oil ports A1 and B1 through the first main valve core; when the second main valve core acts, hydraulic oil input from the input oil port enters the oil duct A2B2 through the third one-way valve, and the oil duct A2B2 is communicated with the output oil ports A2 and B2 through the second main valve core; the oil duct A1B1 is fed back to the LS oil port through a fifth one-way valve, and the oil duct A2B2 is fed back to the LS oil port through a fourth one-way valve and is used for supplying hydraulic oil to the variable pump; the LS signal of the multi-way valve is selected by adopting the inlet one-way valve structure, so that the structure of the multi-way valve is simplified, the load of the multi-way valve is lightened, the efficiency is improved, and the complex action of the whole machine is convenient to realize;

(2) The valve body of the multi-way valve is simple in structure and low in processing and maintenance cost;

(3) The full variable hydraulic system can realize the combined and combined actions of the steering, the movable arm and the tipping bucket of the loader, fully exert the variable effect of the variable pump and realize energy conservation.

Drawings

FIG. 1 is a hydraulic schematic diagram of an electrically controlled closed center multiway valve according to an embodiment of the present invention;

fig. 2 is a schematic view of a first view angle structure of an electrically controlled closed center multi-way valve according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a central section of an electrically controlled closed center multi-way valve according to an embodiment of the present invention;

FIG. 4 is a bottom view of FIG. 2;

FIG. 5 is a schematic cross-sectional view of a first main valve element of an electrically controlled closed center multi-way valve according to an embodiment of the present invention;

FIG. 6 is a schematic cross-sectional view of a second main valve element of an electrically controlled closed center multi-way valve according to an embodiment of the present invention;

FIG. 7 is a schematic cross-sectional view of a fourth check valve and a sixth check valve of an electrically controlled closed center multi-way valve according to an embodiment of the present invention;

FIG. 8 is a left side view of FIG. 2;

FIG. 9 is a schematic diagram of an all-variable hydraulic system employing an electronically controlled closed-center multi-way valve provided by an embodiment of the present invention;

FIG. 10 is a graph showing current versus pressure control for first through fourth electro-proportional pressure reducing valves in accordance with an embodiment of the present invention;

in the figure: 1. a variable displacement pump; 2. a diverter; 3. a steering hydraulic cylinder; 4. a priority valve; 5. a pilot oil source valve; 6. a first actuator; 7. a second actuator; 8. electrically controlling the central multi-way valve; 9. an oil return filter; 10. a heat sink; 11. an electric control handle; 12. a hydraulic oil tank;

51. a first electro proportional pressure reducing valve; 52. a second electro proportional pressure reducing valve; 53. a third electro proportional pressure reducing valve; 54. a fourth electro proportional pressure reducing valve; 55. a first main spool; 56. a second main spool; 57. a main safety valve; 58. LS overflow valve; 59. a constant flow valve; 60. a first overload valve; 61. a first one-way valve; 62. a second overload valve; 63. a second one-way valve; 64. a third one-way valve; 65. a fourth one-way valve; 66. a fifth check valve; 67. and a sixth one-way valve.

Detailed Description

The invention is further described below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention.

Embodiment one:

as shown in fig. 1 to 9, an electrically controlled closed center multiple-way valve includes: a valve body in which a first main spool 55 and a second main spool 56 are provided; when the first main valve core 55 and the second main valve core 56 are not operated, the input oil port and the output oil ports A1 and B1 are separated by the first main valve core 55, and the input oil port and the output oil ports A2 and B2 are separated by the second main valve core 56; when the first main valve core 55 acts, hydraulic oil input from the input oil port enters the oil duct A1B1 through the sixth one-way valve 67, and the oil duct A1B1 is connected with the output oil ports A1 and B1 through the first main valve core 55; when the second main valve core 56 acts, hydraulic oil input from the input oil port enters the oil duct A2B2 through the third one-way valve 64, and the oil duct A2B2 is connected with the output oil ports A2 and B2 through the second main valve core 56; the oil passage A1B1 is fed back to the LS port through the fifth check valve 66, and the oil passage A2B2 is fed back to the LS port through the fourth check valve 65 for the variable pump 1 to supply hydraulic oil.

The electric control center closing multi-way valve 8 consists of a P1 port, a P2 port, an MP port, an LS2 port, a T port, an A1 port, an A2 port, a B1 port, a B2 port, an A1 port, an A2 port, a B1 port, a B2 port, a Pst port and an L port.

The electrically controlled center-closing multiple-way valve 8 includes a first main valve core 55 of a three-position and center-closing core, a second main valve core 56 of a four-position and center-closing core, a first electro proportional pressure reducing valve 51, a second electro proportional pressure reducing valve 52, a third electro proportional pressure reducing valve 53, a fourth electro proportional pressure reducing valve 54, a main relief valve 57, an LS overflow 58, a constant flow valve 59, a first overload valve 60, a first one-way valve 61, a second overload valve 62, a second one-way valve 63, a third one-way valve 64, a fourth one-way valve 65, a fifth one-way valve 66, and a sixth one-way valve 67.

The three functional positions of the first main valve element 55 are left, middle, and right, respectively, and the oil inlet passage is blocked at the middle position, and the pressure oil for driving the first actuator 6 cannot be output through the first main valve element 55. The first actuator 6, i.e. the skip cylinder of the loader. The small cavity B1 of the first executing element 6 is communicated with the oil outlet of the first one-way valve 61, the oil inlet of the first one-way valve 61 is communicated with the T-port, and the small cavity B1 is used for supplementing oil to the small cavity of the first executing element 6 and preventing suction. The port B1 of the small cavity of the first actuating element 6 is communicated with the oil inlet of the first overload valve 60, the oil outlet of the first overload valve 60 is communicated with the port T, and overload protection is performed on the ports A1 and B1 of the large cavity and the small cavity of the first actuating element 6.

The four functional positions of the second main spool 56 are left one position, left two position, middle position, and right position, respectively, and the oil inlet passage is blocked at the middle position, and the pressure oil for driving the second actuator 7 cannot be outputted through the second main spool 56. The left one-position port A2 and the B2 of the oil outlet of the second main valve core 56 are communicated with the oil return at the same time, and the oil inlet is cut off. The second actuator 7 is the boom cylinder of the loader. The small cavity B2 of the second executing element 7 is communicated with the oil outlet of the second one-way valve 63, and the oil inlet of the second one-way valve 63 is communicated with the T-port for supplementing oil to the small cavity of the second executing element 7, so that suction is prevented.

The port P1 is connected with the EF port of the second working oil port of the priority valve 4, the port LS is connected with the port LS3 of the priority valve 4, the port LS1 of the priority valve 4 is connected with the port LS of the steering gear 2, the port LS2 of the priority valve 4 is connected with the port X of the variable pump 1, and the pressure of the port LS2 of the priority valve 4 is fed back to the variable pump 1 after comparing the steering load signal with the working load signal, so that the variable pump 1 can provide pressure oil according to the load demand.

The port T is connected with a hydraulic oil tank 12 through a radiator 10 and an oil return filter 9 and is used for oil return of the hydraulic system. The L port is connected with a hydraulic oil tank 12 and is used for recovering leakage oil of the electrically-controlled closed center multi-way valve.

The port A1 and the port B1 are connected with the large and small cavities of the skip bucket cylinder of the first executing element 6 and are used for outputting flow to the skip bucket cylinder of the first executing element 6.

The port A2 and the port B2 are connected with the large cavity and the small cavity of the movable arm cylinder of the second execution element 7 and are used for outputting flow to the movable arm cylinder of the second execution element 7.

The Mp port is communicated with the P1 port through an oil duct, the Mp port is connected with the P1 port of the pilot oil source valve 5, and the A port of the pilot oil source valve 5 is connected with the Pst port of the electric control closed core multi-way valve.

When the first main valve core 55 is in the middle position, the oil inlet of the first main valve core 55 is in a cut-off state, when the first main valve core 55 is changed in direction, the oil inlet of the first main valve core 55 passes through a left or right oil path of the first main valve core 55, passes through a sixth one-way valve 67, enters a throttle of the first main valve core 55, is output from an oil outlet A1 or a B1 port of the throttle, supplies oil to the first executing element 6, and the oil return of the first executing element 6 passes through the other oil outlet and returns oil through the first main valve core 55.

When the second main valve core 56 is in the middle position, the oil inlet of the second main valve core 56 is in a cut-off state, when the second main valve core 56 is changed in direction, the oil inlet of the second main valve core 56 passes through a right or left one-position oil path of the second main valve core 56, passes through the third one-way valve 64, flows out to a throttle of the second main valve core 56, is output from an oil outlet A2 or a B2 of the throttle, supplies oil to the second executing element 7, and the oil return of the second executing element 7 passes through the other oil outlet and returns oil through the second main valve core 56. When the second main valve core 56 is reversed to the left position, the oil inlet of the second main valve core 56 returns to the second main valve core 56 again through the third one-way valve 64 to be communicated with the oil return port T, the oil ports A2 and B2 of the second main valve core 56 are simultaneously communicated with the oil return port T through the left position of the second main valve core 56, and the second actuator 7 is in a floating state.

The feedback port of the first main valve core 55 is communicated with the feedback port of the second main valve core 56 through a fifth one-way valve 66 and is communicated with the LS port or LS2 port of the electric control closed center multi-way valve 8 through a fourth one-way valve 65, the LS port is communicated with the inlet of the constant flow valve 59, and the oil outlet of the constant flow valve 59 is communicated with the T port.

The LS port is communicated with an oil inlet of the LS overflow valve 58, and an oil outlet of the LS overflow valve 58 is communicated with the T port.

The P1 port and the P2 port are connected with an oil inlet of a main safety valve 57, and an oil outlet of the main safety valve is communicated with the T port.

The oil outlet of the first electro proportional pressure reducing valve 51 is communicated with the left cavity of the first main valve core 55, and the first main valve core 55 is controlled to move to the right, so that the first main valve core 55 is at the left position. The oil outlet of the first electro proportional pressure reducing valve 51 is communicated with the leaked oil L port in the first working position; when the first electro proportional pressure reducing valve 51 is powered on, the first electro proportional pressure reducing valve is in a second working position, so that the oil outlet is communicated with the PST oil outlet. And the spool of the first electro-proportional pressure relief valve 51 may be placed between the first and second operating positions when the first electro-proportional pressure relief valve 51 is signaled with an appropriate current or voltage.

The oil outlet of the second electro proportional pressure reducing valve 52 is communicated with the left cavity of the second main valve core 56, and the second main valve core 56 is controlled to move to the right, so that the second main valve core 56 is in a left one position or a left two position. The oil outlet of the second electro proportional pressure reducing valve 52 is communicated with the leaked oil L port in the first working position; when the second electro proportional pressure reducing valve 52 is powered on, it is in the second working position, so that the oil outlet is communicated with the PST oil outlet. And the spool of second electro-proportional pressure relief valve 52 may be placed between the first and second operating positions when second electro-proportional pressure relief valve 52 is energized with an appropriate current or voltage signal.

The oil outlet of the third electro proportional pressure reducing valve 53 is communicated with the right cavity of the second main valve core 56, and the second main valve core 56 is controlled to move leftwards, so that the second main valve core 56 is positioned at the right position. The oil outlet of the third electro proportional pressure reducing valve 53 is communicated with the leaked oil L port in the first working position; when the third electro proportional pressure reducing valve 53 is powered on, the second working position is adopted, so that the oil outlet is communicated with the PST oil outlet. While the second electro-proportional pressure relief valve 52 may be configured to spool the third electro-proportional pressure relief valve 53 between the first and second operating positions when a suitable current or voltage signal is applied thereto.

The oil outlet of the fourth electro proportional pressure reducing valve 54 is communicated with the right cavity of the first main valve core 55, and the first main valve core 55 is controlled to move leftwards, so that the first main valve core 55 is positioned at the right position. The fourth electro proportional pressure reducing valve 54 is communicated with the leakage oil L port when the oil outlet is in the first working position; when the fourth electro proportional pressure reducing valve 54 is powered on, the fourth electro proportional pressure reducing valve is in the second working position, so that the oil outlet is communicated with the PST oil outlet. And the fourth electro-proportional pressure relief valve 54 may be spool between the first and second operating positions when the fourth electro-proportional pressure relief valve 54 is signaled with the appropriate current or voltage.

The current and pressure control curves of the first electro proportional pressure reducing valve 51, the second electro proportional pressure reducing valve 52, the third electro proportional pressure reducing valve 53, and the fourth electro proportional pressure reducing valve 54 are shown in fig. 10.

From the current curve, the first and second proportional

pressure reducing valves

51 and 52 are given; a first electro proportional pressure reducing valve 51, a third electro proportional pressure reducing valve 53; a fourth electro proportional pressure reducing valve 54, a second electro proportional pressure reducing valve 52; a fourth electric proportional pressure reducing valve 54, a third electric proportional pressure reducing valve 53; the different currents are combined two by two to correspond to different pressures, so that the first main valve core 55 and the second main valve core 56 are positioned at different positions, and a compound action is realized. Therefore, corresponding displacement matching is realized by corresponding different currents corresponding to different angles of the handle to corresponding positions of the valve core, and the compound action is ensured.

The working principle of the hydraulic system in this embodiment is as follows:

1. no operation acts: the first main spool 55 and the second main spool 56 are both in the neutral position. The LS feedback ports of the variable pump are disconnected with the oil inlet and the oil outlet through the main valve core, the LS port oil way is communicated with the T port through the constant flow valve 59, and no load feedback pressure exists, so that the variable pump 1 operates at minimum displacement, and the standby pressure of the variable pump port is maintained.

The method comprises the following steps: the electric control closed core multi-way valve P1 oil duct and P2 oil duct are isolated from the T port through the first main valve core 55 and the second main valve core 56, so as to realize the closed core principle. The A1B1' oil duct is separated from the oil ports A1 and B1 by a first main valve core 55; the A2B2' oil passage is separated from the oil ports A2 and B2 by a second main valve core 56; and thus no load feedback pressure is fed back to the variable displacement pump 1.

2. Single action: taking the operation arm linkage as an example, when the electric control handle 11 acts, an electric control signal Xb2 is output to the second electric proportional pressure reducing valve 52, so that the second main valve core 56 is reversed to the right, and an oil inlet of the second main valve core 56 passes through the third one-way valve 64 to a throttling port of the second main valve core 56 to be communicated with the port B2; the load pressure signal of the second actuator 7 is fed back to the LS port through the fourth one-way valve 65 and fed back to the X port of the variable pump 1 through the LS3 port of the priority valve 4 to the LS2 port of the priority valve 4, so that the variable pump 1 can provide flow according to the opening requirement of the second main valve core 56. When the load pressure of the second actuator 7 is higher than the set pressure of the LS relief valve 58, the LS relief valve 58 is opened, and LS port oil flows back to the hydraulic oil tank 12 through the constant flow valve 59 and the LS relief valve 58 through the T port of the electric control closed-core multi-way valve 8.

The method comprises the following steps: second main spool 56 moves to the right a distance when oil passage B2 communicates with oil passage A2B2' through second main spool 56, and oil passage A2 communicates with oil passage T through second main spool 56. The P1 oil gallery passes through second main spool 56, through third check valve 64, and into oil gallery A2B2'. The oil passage A2B2' communicates with the LS oil passage through the fourth check valve 65, thereby feeding back the load signal to the X port of the variable displacement pump 1.

When the electric control handle 11 is continuously operated and the electric control signal Xb2 is output until the second electric proportional reducing valve 52 reaches a set value, the second main valve core 56 is reversed to a left second position, the oil inlet of the second main valve core 56 returns to the second main valve core 56 again through the third one-way valve 64 to be communicated with the oil return T, the oil port A2 and the oil port B2 of the second main valve core 56 are simultaneously communicated with the oil return T through the left two positions of the second main valve core 56, and the second executing element 7 is in a floating state. At this time, the LS port has no pressure feedback, and the variable pump 1 is in the minimum displacement and standby pressure state.

The method comprises the following steps: the second main spool 56 continues to move rightward to the set point, at which time the oil passage B2 communicates with the oil passage A2B2' through the second main spool 56, the oil passage B2 communicates with the oil passage T through the second main spool 56, and the oil passage A2 communicates with the oil passage T through the second main spool 56. The P1 oil passage passes through the second main spool 56 and through the third check valve 64 into the oil passage A2B2', thereby forming the oil ports P, A, B2, T communicating.

3. And (5) compound action. When the electric control handle 11 is manipulated, electric control signals Xa1 and Xa2 are output to the third electric proportional pressure reducing valve 53 and the fourth electric proportional pressure reducing valve 54, respectively, so that Pst pilot pressures are applied to right ends of the first main spool 55 and the second main spool 56, respectively, so that the first main spool 55 and the second main spool 56 are in the right position. According to the angle of the electric control handle 11, the displacement proportioning of the first main valve core 55 and the second main valve core 56 is realized. Since the first main valve core 55 and the second main valve core 56 are both reversed to the right, the oil inlet of the first main valve core 55 is communicated with the port A1 through the choke outlet of the sixth check valve 67 to the first main valve core 55; communicate with the LS port via the fifth check valve 66, thereby feeding back the load pressure signal of the first actuator 6 to the LS port; the oil inlet of the second main valve core 56 passes through the third one-way valve 64 to the throttle outlet of the second main valve core 56 and is communicated with the port A2; the load pressure signal of the second actuator 7 is fed back to the LS port through the fourth check valve 65, the higher pressure is transmitted to the LS port after the two load feedback pressures are compared, and the lower pressure is blocked by the check valve. For example, the load pressure of the first actuator 6 is high, the load feedback pressure is transmitted to the LS port through the fifth check valve 66, and the load pressure of the second actuator 7 is blocked by the fourth check valve 65. The LS port pressure is fed back to the X port of the variable pump 1 from the LS3 port of the priority valve 4 to the LS2 port of the priority valve, so that the variable pump 1 can provide flow according to the opening requirements of the first main valve core 55 and the second main valve core 56

The method comprises the following steps: the first main spool 55 moves to the left a certain distance, and at this time, the oil passage A1 and the oil passage A1B1' communicate through the first main spool 55, and the oil passage B1 and the oil passage T communicate through the first main spool 55. The P1 oil passage passes through the first main spool 55, through the sixth check valve 67, and into the oil passage A1B1'. The oil passage A1B1' communicates with the LS oil passage through the fifth check valve 66; second main spool 56 moves to the left a distance when oil passage A2 communicates with oil passage A2B2' through second main spool 56 and oil passage B2 communicates with oil passage T through second main spool 56. The P1 oil gallery passes through second main spool 56, through third check valve 64, and into oil gallery A2B2'. The oil passage A2B2' communicates with the LS oil passage through a fourth check valve 65. Compared with the two, the high-pressure oil pipe is communicated with the LS oil pipe, and the low-pressure one-way valve is communicated with the LS oil pipe in a reverse cut-off way.

Embodiment two:

based on the electrically controlled closed center multiway valve of the first embodiment, the present embodiment provides an all-variable hydraulic system, which includes: the variable pump 1, the priority valve 4, the steering gear 2 and the electric control center-closing multi-way valve 8 in the first embodiment; the variable pump 1 inputs hydraulic oil into the steering hydraulic oil cylinder 3 through the priority valve 4 and the steering gear 2 for controlling steering; the variable pump 1 inputs hydraulic oil into the first executive component 6 and the second executive component 7 through the priority valve 4 and the electric control center closing multi-way valve 8, and is used for completing single action or compound action; the LS port of the electric control center closing multi-way valve 8 is connected with the LS3 port of the priority valve 4 and is used for controlling the steering hydraulic cylinder 3, the first executing element 6 and the second executing element 7 to complete single action or compound action.

Embodiment III:

based on the electrically controlled closed center multi-way valve of the first embodiment and the all-variable hydraulic system of the second embodiment, the embodiment provides a loader, wherein the loader is configured with the electrically controlled closed center multi-way valve of the first embodiment or the all-variable hydraulic system of the second embodiment.

The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.

Claims

1. An electrically controlled closed center multiple-way valve, comprising: a valve body in which a first main valve element (55) and a second main valve element (56) are provided;

when the first main valve core (55) and the second main valve core (56) do not act, the input oil port and the output oil ports A1 and B1 are separated by the first main valve core (55), and the input oil port and the output oil ports A2 and B2 are separated by the second main valve core (56);

when the first main valve core (55) acts, hydraulic oil input from the input oil port enters the oil duct A1B1 through the sixth one-way valve (67), and the oil duct A1B1 is connected with the output oil ports A1 and B1 through the first main valve core (55);

when the second main valve core (56) acts, hydraulic oil input from the input oil port enters the oil duct A2B2 through the third one-way valve (64), and the oil duct A2B2 is connected with the output oil ports A2 and B2 through the second main valve core (56);

the oil passage A1B1 is fed back to the LS oil port through a fifth one-way valve (66), and the oil passage A2B2 is fed back to the LS oil port through a fourth one-way valve (65) for supplying hydraulic oil to the variable pump (1).

2. The electrically controlled closed center multiway valve according to claim 1, wherein a first electrically proportional pressure reducing valve (51), a second electrically proportional pressure reducing valve (52), a third electrically proportional pressure reducing valve (53) and a fourth electrically proportional pressure reducing valve (54) are further arranged in the valve body;

the output ends of the first electro proportional pressure reducing valve (51) and the fourth electro proportional pressure reducing valve (54) are connected with a spring cavity of the first main valve core (55) and are used for controlling the movement of the first main valve core (55);

the output ends of the second electro proportional pressure reducing valve (52) and the third electro proportional pressure reducing valve (53) are connected with a spring cavity of the second main valve core (56) and are used for controlling the movement of the second main valve core (56);

when the first to fourth electric proportional reducing valves are not electrified, the first to fourth electric proportional reducing valves are positioned at a first working position, and an oil inlet of the first working position is communicated with an L port of the electric control center closing multi-way valve;

when the first to fourth electric proportional reducing valves are powered, the first to fourth electric proportional reducing valves are positioned in a second working position, and an oil inlet of the second working position is communicated with a Pst port of the electric control center-closing multi-way valve.

3. The electrically controlled closed center multiway valve of claim 1, wherein an LS relief valve (58) and a constant flow valve (59) are also provided in the valve body; the LS oil port is connected with an oil inlet of the constant flow valve (59), and an oil outlet of the constant flow valve (59) is communicated with a T port of the electric control center-closing multi-way valve; the LS oil port is connected with an oil inlet of the LS overflow valve (58), and an oil outlet of the LS overflow valve (58) is communicated with the T port; when the load feedback signal of the LS oil port is larger than the set pressure of the LS overflow valve (58), the LS oil port is communicated with the T port of the electric control closed center multi-way valve through the constant flow valve (59) and the LS overflow valve (58).

4. The electrically controlled closed center multi-way valve according to claim 1, wherein the output ports B1 and B2 are communicated through a first check valve (61) and a second check valve (63) and are used for supplementing oil to a rod cavity of an oil cylinder of the actuating element.

5. An all-variable hydraulic system, comprising: a variable pump (1), a priority valve (4), a steering gear (2) and an electrically controlled closed center multi-way valve (8) according to any one of claims 1 to 4; the variable pump (1) inputs hydraulic oil into the steering hydraulic oil cylinder (3) through the priority valve (4) and the steering gear (2) for controlling steering; the variable pump (1) inputs hydraulic oil into the first executing element (6) and the second executing element (7) through the priority valve (4) and the electric control center closing multi-way valve (8) and is used for completing single action or compound action; the LS port of the electric control center closing multi-way valve (8) is connected with the LS3 port of the priority valve (4) and is used for controlling the steering hydraulic cylinder (3), the first executing element (6) and the second executing element (7) to complete single action or compound action.

6. The all-variable hydraulic system of claim 5, wherein the compound action comprises:

when the electric control handle (11) is operated, electric control signals Xa1 and Xa2 are output to the third electric proportional pressure reducing valve (53) and the fourth electric proportional pressure reducing valve (54) respectively, so that Pst pilot pressure acts on the right ends of the first main valve core (55) and the second main valve core (56) respectively, and the first main valve core (55) and the second main valve core (56) are in the right position; according to the angle of the electric control handle (11), the displacement ratio of the first main valve core (55) to the second main valve core (56) is realized.

7. The all-variable hydraulic system of claim 6, wherein the compound action comprises:

the first main valve core (55) and the second main valve core (56) are both reversed to the right, and an oil inlet of the first main valve core (55) is communicated with an A1 port through a choke outlet of the sixth check valve (67) to the first main valve core (55); is communicated with the LS port through a fifth one-way valve (66) so as to feed back a load pressure signal of the first actuator (6) to the LS port; an oil inlet of the second main valve core (56) passes through a third one-way valve (64) to be discharged from a throttle orifice of the second main valve core (56) and is communicated with an A2 port; the variable pump (1) is communicated with the LS port through the fourth one-way valve (65), so that a load pressure signal of the second execution element (7) is fed back to the LS port, the higher pressure is transmitted to the LS port after the two load feedback pressures are compared, the lower pressure is cut off due to the one-way valve, and the variable pump (1) provides flow according to the opening requirements of the first main valve core (55) and the second main valve core (56).

8. A loader provided with an electrically controlled closed center multiple valve according to any one of claims 1 to 4.