CN220037117U - Reversing valve, hydraulic system and working machine - Google Patents

Abstract

The utility model relates to a reversing valve, and in order to solve the problem that the main valve rod of the existing reversing valve leaks when being in the middle position, the reversing valve, a hydraulic system and an operation machine are constructed, wherein an oil inlet and an oil outlet of a cone valve in the reversing valve are respectively communicated with an A cavity and an A working port, a spring cavity is communicated with the A working port, a pressure relief oil duct communicated with the cone valve spring cavity is arranged in a valve body, and a second end of the pressure relief oil duct is arranged on the wall surface of a sealing section of the valve rod cavity; when the oil return valve port of the cavity A is opened, the second end of the pressure relief oil duct is communicated with the cavity T1; when the oil return valve port of the cavity A is closed, the second end of the pressure relief oil duct is shielded and closed by the shaft shoulder of the main valve rod. In the utility model, when the main valve rod is in the middle position, the working port A is blocked by the cone valve, so that oil is prevented from leaking through a gap between the main valve rod and the valve rod cavity, a hydraulic locking function is realized, and a load holding function of the working port A is realized.

Description

Reversing valve, hydraulic system and working machine

Technical Field

The present disclosure relates to a reversing valve, and more particularly, to a reversing valve, a hydraulic system, and a work machine.

Background

The reversing valve comprises a valve body and a valve rod, wherein a shaft shoulder and an annular oil through groove are formed in the valve rod, a valve rod cavity is formed in the valve body, and the valve rod cavity comprises a sealing section in clearance fit with the shaft shoulder on the valve rod and an oil cavity which is located at two ends of the sealing section and communicated with an oil inlet on the valve body. The valve rod axially moves in the valve body, so that the upper shaft shoulder of the sliding rod is in clearance fit with the corresponding sealing section of the valve rod cavity or the shaft shoulder is axially staggered with the sealing section of the valve rod cavity. When the shaft shoulder is axially staggered with the valve rod cavity sealing section, oil cavities at two ends of the valve rod cavity sealing section are communicated by an annular oil through groove on the valve rod, so that the valve port is opened, and corresponding oil paths are communicated. When the shaft shoulder is in clearance fit with the valve rod cavity sealing section, oil cavities at two ends of the valve rod cavity sealing section are separated by the valve rod shaft shoulder, the valve port is closed, and the corresponding oil way is cut off.

In the valve body of the reversing valve, an oil cavity adjacent to a working oil cavity communicated with a working oil port is generally provided with an oil return cavity communicated with an oil return port on the valve body and an oil inlet cavity communicated with an oil inlet on the valve body. The valve rod is usually provided with three axial positions of a left position, a middle position and a right position, so that the working oil cavity is communicated with the oil return cavity (blocked with the oil inlet cavity), the working oil cavity is blocked from the oil return cavity and the oil inlet cavity, and the working oil cavity is communicated with the oil inlet cavity (blocked with the oil return cavity). When the valve rod is in the middle position, the shaft shoulder on the valve rod is in clearance fit with the valve rod cavity sealing section, and if the working oil cavity is in a high-pressure state, oil in the working oil cavity flows to the oil return cavity through the clearance between the valve rod shaft shoulder and the valve rod cavity sealing section, so that internal leakage of the reversing valve is caused.

Reversing valves are used in various applications, such as controlling boom cylinders on work machines such as loaders, excavators, and the like. When the movable arm oil cylinder extends and the movable arm is in a lifting state, due to the dead weight and the load of the working device, the large cavity of the movable arm oil cylinder and the large cavity working oil cavity of the oil cylinder, which is communicated with the large cavity of the movable arm oil cylinder, are in a state with higher pressure, at the moment, if the valve rod is in the middle position, oil in the large cavity working oil cavity of the oil cylinder can slowly flow to the oil return cavity due to internal leakage, and if the valve rod is in the middle position for a long time, the movable arm oil cylinder slowly retracts due to the loss of the oil in the large cavity, so that the lifted working device is caused to subside.

Disclosure of Invention

The utility model aims to solve the technical problem that the main valve rod of the existing reversing valve is in the middle position and leaks, and provides the reversing valve, the hydraulic system and the operation machine, so that the internal leakage of the valve rod in the middle position is avoided.

The technical scheme for achieving the purpose of the utility model is as follows: the reversing valve comprises a valve body and a main valve rod arranged in a valve rod cavity in the valve body, and is characterized in that a cone valve is arranged in the valve body, and a first shaft shoulder, a first oil through groove adjacent to the first shaft shoulder, a second oil through groove adjacent to the second shaft shoulder and a third shaft shoulder adjacent to the second oil through groove are arranged on the main valve rod; the first oil passing groove and the second oil passing groove are arranged around the main valve rod;

the main valve stem cavity includes:

the first sealing section is matched with the first shaft shoulder;

the T1 cavity is communicated with a T port on the valve body;

the second sealing section is matched with the second shoulder to form an A cavity oil return valve port which is communicated or separated from the T1 cavity and the second oil through groove;

the cavity A is communicated with the second oil through groove;

the cavity D is communicated with a main oil inlet oil way on the valve body;

the third sealing section is matched with the third shaft shoulder to form an A valve port which is communicated with or cuts off the second oil through groove and the D cavity;

the oil inlet and outlet of the cone valve are respectively communicated with the cavity A and the working port A on the valve body; the spring cavity of the cone valve is communicated with the working port A;

the valve body is internally provided with a pressure relief oil duct, a first end of the pressure relief oil duct is communicated with a spring cavity of the cone valve, and a second end of the pressure relief oil duct is arranged on a wall surface of a first sealing section of the valve rod cavity;

when the oil return valve port of the cavity A is opened, the second end of the pressure relief oil duct is communicated with the first oil through groove; when the oil return valve port of the cavity A is closed, the second end of the pressure relief oil duct is shielded and closed by the first shaft shoulder.

In the utility model, if the valve port A is opened, the pressure of the cavity A is larger than that of the working port A, oil in the conical valve spring cavity flows to the working port A through the oil through hole, and the conical valve core moves to be opened under the pushing of the pressure oil in the cavity A. When the oil return valve port of the cavity A is opened, the oil outlet end of the pressure relief oil duct is exposed due to movement of the first shaft shoulder and is communicated with the first oil through groove, the spring cavity of the cone valve is relieved, the pressure oil of the working port A pushes the valve core of the cone valve open, the cone valve is conducted from the working port A to the cavity A, and the oil return of the working port A flows through the cone valve and the cavity A oil return valve port to the cavity T1 for oil return. When the main valve rod is in the middle position, the first shaft shoulder is matched with the wall surface of the first sealing section of the main valve rod cavity to shield the second end of the pressure relief oil duct, so that the oil in the spring cavity of the cone valve cannot flow out through the pressure relief oil duct, and at the moment, if the oil in the working port A is in a relatively high-pressure state due to the action of load, the valve core of the cone valve is in a closed state due to the action of the hydraulic oil pressure of the working port A and the elasticity of the spring cavity of the cone valve. Compared with a slide valve, the cone valve has better sealing performance, and the internal leakage is negligible and even zero, so that the cone valve has a hydraulic locking function and realizes the load maintaining function of the working port A.

In the reversing valve, the main valve rod is also provided with a third oil-through groove adjacent to the third shaft shoulder and a fourth shaft shoulder adjacent to the third oil-through groove; the third oil groove is arranged around the main valve rod;

the valve stem cavity further comprises:

the cavity B is communicated with the third oil-through groove and is connected with a working port B on the valve body;

the T2 cavity is communicated with a T port on the valve body;

the fourth sealing section is matched with the third shaft shoulder to form a valve port B which is communicated with or cuts off the third oil groove and the cavity D;

the fifth sealing section 37 cooperates with the fourth shoulder to form a B-chamber oil return valve port that communicates or blocks the third oil sump and the T2 chamber.

The working port A and the working port B can be connected with two working ports of the hydraulic braking part, for example, the working ports A and B are connected with a large cavity and a small cavity of a hydraulic cylinder to realize the telescopic bidirectional action of the cylinder, or the working ports A and B are connected with two working ports of a hydraulic motor to realize the forward and reverse rotation of the hydraulic motor.

In the reversing valve, the third shaft shoulder is provided with an annular fourth oil groove communicated with the D cavity, and the fourth oil groove is arranged around the main valve rod and divides the third shaft shoulder into a first middle shaft shoulder positioned between the second oil groove and the fourth oil groove and a second middle shaft shoulder positioned between the third oil groove and the fourth oil groove;

the third sealing section is matched with the first middle shaft shoulder to form an A valve port which is communicated with or cuts off the second oil through groove and the D cavity, and a regeneration valve port which is communicated with or cuts off the A cavity and the fourth oil through groove;

the fourth sealing section is matched with the second middle shaft shoulder to form a valve port B which is communicated or separated from the cavity D and the third oil groove.

In the utility model, when the main valve rod moves to open the valve port B, in the front-stage travel of the main valve rod, the third oil groove is communicated with the cavity D, and the valve port B is opened; the first middle shaft shoulder is matched with the third sealing section, the fourth oil groove and the cavity A are still in a separation state, and the oil in the cavity D enters the cavity B through the valve port B and flows to the working port B; and oil return of the working port A flows to the cavity T1 through the cavity A and the oil return valve port of the cavity A to realize oil return. When the main valve rod moves to the back-end stroke towards the first end direction under the action of negative load,

the first middle shaft shoulder is in contact with the third sealing section in a separation way, and enters the cavity A, the fourth oil groove is communicated with the cavity A, and the regeneration valve port is opened. And the oil in the cavity D enters the cavity B through the valve port B and flows to the working port B, when the oil supply from the cavity P to the cavity B is insufficient, the oil return from the working port A can be forced to enter the cavity B through the regeneration valve port, the cavity D and the valve port B to form flow regeneration, the negative pressure phenomenon generated by negative load of the working port B is effectively solved, and if the hydraulic actuating mechanism is an oil cylinder, differential connection is generated, so that the movement speed is accelerated.

In the reversing valve, a first safety valve is further arranged in the valve body, the oil inlet end of the first safety valve is communicated with the working port A, and the oil outlet end of the first safety valve is communicated with the cavity T1. Further, a second safety valve is further arranged in the valve body, the oil inlet end of the second safety valve is communicated with the working port B, and the oil outlet end of the second safety valve is communicated with the cavity T2.

In the reversing valve, the main valve rod is further provided with a fifth oil groove adjacent to the first shaft shoulder; the fifth oil groove is arranged around the main valve rod;

the valve stem cavity further comprises:

the P cavity is communicated with a P port on the valve body;

the cavity C is communicated with the fifth oil groove;

the sixth sealing section is matched with the first shaft shoulder to form a flow control valve port for communicating or isolating the C cavity and the fifth oil groove (21);

the main oil inlet oil path comprises: the oil duct of P chamber, fifth oil groove, C chamber, intercommunication C chamber and D chamber.

In the reversing valve of the utility model, the reversing valve may also be:

the main valve rod is provided with a fifth shaft shoulder, a fifth oil through groove and a sixth oil through groove which are adjacent to the fifth shaft shoulder; the fifth oil groove and the sixth oil groove are arranged around the main valve rod;

the valve stem cavity further comprises:

the P cavity is communicated with the fifth oil groove and communicated with a P port on the valve body;

the cavity C is communicated with the sixth oil through groove;

the sixth sealing section is matched with the fifth shaft shoulder to form a flow control valve port for communicating or blocking the P cavity with the sixth oil through groove and communicating or blocking the C cavity with the fifth oil through groove;

the main oil inlet oil path comprises: the oil duct of P chamber, fifth oil groove, sixth oil groove, C chamber, intercommunication C chamber and D chamber.

In the reversing valve, a compensating valve and/or a one-way valve of a load pressure signal leading-out oil way is arranged on an oil duct which is communicated with a C cavity and a D cavity in the valve body.

The technical scheme for achieving the purpose of the utility model is as follows: a hydraulic system is constructed which is characterized by comprising the reversing valve.

The technical scheme for achieving the purpose of the utility model is as follows: a work machine is constructed comprising the hydraulic system described above. The work machine may be an excavator, loader, roller, grader, industrial vehicle, or the like.

Compared with the prior art, in the utility model, when the main valve rod is in the middle position, the working port A is blocked by the cone valve, so that oil is prevented from leaking through a gap between the main valve rod and the valve rod cavity, a hydraulic locking function is realized, and a load maintaining function of the working port A is realized.

Drawings

Fig. 1 is a schematic structural view of a reversing valve according to a first embodiment of the present utility model.

FIG. 2 is a schematic illustration of a main valve stem according to an embodiment of the present utility model.

FIG. 3 is a schematic view of a valve body according to an embodiment of the present utility model.

Fig. 4 is a schematic structural diagram of a reversing valve in the second embodiment of the present utility model.

Fig. 5 is a schematic diagram of a valve body structure of a reversing valve in the second embodiment of the present utility model.

FIG. 6 is a schematic diagram of a main valve stem according to a second embodiment of the present utility model.

Part names and serial numbers in the figure:

the valve stem 10, the first shoulder 13, the second shoulder 14, the third shoulder 15, the first middle shoulder 151, the second middle shoulder 152, the fourth shoulder 16, the fifth shoulder 12 and the sixth shoulder 11.

First oil passing groove 26, second oil passing groove 23, third oil passing groove 24, fourth oil passing groove 25, fifth oil passing groove 21, and sixth oil passing groove 22.

The valve body 30, the first seal segment 33, the second seal segment 34, the third seal segment 35, the fourth seal segment 36, the fifth seal segment 37, the sixth seal segment 32, the seventh seal segment 31, and the eighth seal segment 38.

P-chamber 41, C-chamber 42, T1-chamber 43, a-chamber 44, D-chamber 45, B-chamber 46, T2-chamber 47.

The check valve 51, the compensation valve 52, the cone valve 53, the relief oil passage 54, the first relief valve 55, the second relief valve 56 and the oil passing hole 57.

The end cover 60, the spring return mechanism 61, the spring seat 62, the return spring 63, the first spring seat 64, the second spring seat 65, and the plug 66.

A first electric proportional pilot valve 70, a pilot oil inlet 71, a pilot oil return port 72, a pilot pipeline 73 and a second electric proportional pilot valve 80.

Detailed Description

The following describes specific embodiments with reference to the drawings.

In the description of the present utility model, ordinal words are not intended to limit elements modified with or combined with ordinal words to the order of the elements or the amount of the elements. The use of ordinal numbers is used only as a convenient expression method for distinguishing two or more elements from each other. Thus, for example, the statement "first X" and the statement "second X" are expressions for distinguishing between two xs, and do not necessarily mean that the total number of xs is 2, nor that the first X must precede the second X. The term "first" does not necessarily mean "first".

Embodiment one.

As shown in fig. 1, the reversing valve in the embodiment of the present utility model includes a valve body 30, a main valve stem 10 disposed in a valve stem cavity within the valve body 30, a check valve 51, a first relief valve 55, and two electric proportional pilot valves.

As shown in fig. 2, the main valve stem 10 is provided with a sixth shoulder 11, a fifth oil groove 21, a first shoulder 13, a first oil groove 26, a second shoulder 14, a second oil groove 23, and a third shoulder 15 in this order from the first end to the second end (from left to right in fig. 2). Each oil through groove is an annular oil through groove.

As shown in fig. 3, the valve stem cavity structure includes: seventh seal segment 31, P cavity 41, sixth seal segment 32, C cavity 42, first seal segment 33, T1 cavity 43, second seal segment 34, a cavity 44, third seal segment 35, D cavity 45, eighth seal segment 38.

The valve stem cavity is matched with the main valve stem as shown in fig. 1, and the valve stem cavity is specifically as follows:

the seventh sealing section 31 is matched with the sixth shaft shoulder 11, and forms a sealing structure to block the communication between the pilot control cavity at the first end of the main valve rod and the oil path (P cavity) in the valve body. The seventh seal segment 31 supports and guides the first end of the main valve stem 10 such that the main valve stem 10 is capable of axial movement within the stem cavity of the valve body.

The P chamber 41 communicates with a P port on the valve body 30 for introducing pressure oil for driving the hydraulic actuator to operate and communicates with the fifth oil groove 21 on the main valve stem 10.

The sixth seal segment 32 is in clearance fit with the first shoulder 13 to form a flow control valve port that communicates or blocks the C cavity 42 and the fifth oil groove 21. A plurality of first axial oil guiding grooves 121 with variable cross sections are arranged on the cylindrical side surface of the section, facing the first end, of the first shaft shoulder 13, and the first axial oil guiding grooves 121 are communicated with the fifth oil guiding groove 21 on the main valve rod 10.

When the main valve rod 10 moves axially towards the second end, the section, facing the first end, of the first shaft shoulder 13 on the main valve rod 10 is matched with the sixth sealing section 32 of the valve rod cavity, the fifth oil groove 21 is communicated with the C cavity 42 through the first axial oil guide groove 121 to form a flow control valve port with the valve port opening corresponding to the stroke of the main valve rod, and a pressure difference is formed between the front end (P cavity) and the rear end (C cavity) of the flow control valve port. The P chamber 41 communicates with the fifth oil passage groove 21.

The first sealing section 33 is in clearance fit with a section, facing the second end, of the first shaft shoulder 13, and is used for isolating the C cavity 42 from the T1 cavity 43; the T1 chamber 43 communicates with a T port in the valve body. In the hydraulic system, the T port is connected with a hydraulic oil tank through a pipeline to realize oil return of the hydraulic system. The T1 chamber 43 communicates with the first oil passage 26 on the main valve stem.

The second seal segment 34 is in clearance engagement with the second shoulder 14 and forms an a-cavity oil return valve port that communicates or blocks the T1 cavity 43 and the second oil sump 23. The second oil drain groove 23 communicates with the a cavity 44. When the main valve rod 10 moves from the middle position to the first end direction, the A cavity oil return valve port is opened after the positioning movement, the opening of the A cavity oil return valve port is increased along with the increase of the movement stroke of the main valve rod, and the A cavity oil return valve port is fully opened. After the oil return valve port of the cavity A is opened, the oil in the cavity A44 flows to the cavity T1 43 through the oil return valve port of the cavity A, so that oil return of the working port A is realized. When the main valve rod 10 moves from the middle position to the second end direction, the oil return valve port of the cavity A is always in a closed and cut-off state.

The A cavity 44 is communicated with the second oil vent groove 23 on the main valve rod and is connected with an A working port on the valve body through a cone valve 53.

As shown in fig. 1, a cone valve 53 is provided in the valve body at an oil passage between the a chamber 44 and the a working port for communicating or blocking the flow of oil between the a chamber 44 and the a working port. Two oil ports of the cone valve 53 are respectively communicated with the A cavity 44 and the A working port; the valve core of the cone valve 53 is provided with an oil through hole 57 for communicating the cone valve spring cavity with the working port A, and the valve body 30 is internally provided with a pressure relief oil duct 54 communicated with the cone valve spring cavity. The first end of the pressure relief oil duct 54 is communicated with the cone valve spring cavity, the second end of the pressure relief oil duct 54 is arranged on the wall surface of the first sealing section 33 of the valve rod cavity, when the main valve rod 10 moves towards the first end direction to enable the oil return valve port of the cavity A to be opened, the first shaft shoulder 13 moves relative to the first sealing section 33 to expose the second end of the pressure relief oil duct 54, the second end of the pressure relief oil duct 54 is communicated with the T1 cavity 43 through the first oil through groove 26, and oil in the cone valve spring cavity can flow out through the pressure relief oil duct 54. When the main valve rod 10 is in the middle position, the first shaft shoulder 13 is matched with the wall surface of the first sealing section 33 to shield the second end of the pressure relief oil duct 54, so that the pressure relief oil duct 54 is blocked, and the spring cavity oil of the cone valve 53 cannot flow out through the pressure relief oil duct 54.

The third seal segment 35 cooperates with the segment of the third shoulder 15 facing the first end to form an a port that communicates or blocks the second oil drain groove 23 and the D cavity 45. When the main valve rod 10 moves from the middle position to the second end direction, the second oil vent groove 23 is communicated with the cavity D45, the valve port A is opened, and oil in the cavity D flows to the cavity A44 through the valve port A when the displacement of the main valve rod exceeds a certain value.

The eighth seal segment 38 cooperates with the segment of the third shoulder 15 facing the second end and forms a seal structure that blocks the pilot control chamber at the second end of the main valve stem from oil communication with the oil passage (D chamber) in the valve body. The eighth seal segment 38 supports and guides the second end of the main valve stem 10 so that the main valve stem can move axially within the stem cavity of the valve body.

The C cavity 42 is communicated with the oil inlet end of the check valve 51, and the oil outlet end of the check valve 51 is communicated with the D cavity 45. When the valve port A is opened, the one-way valve 51 can prevent the oil in the working port A from flowing backwards towards the direction of the main oil inlet oil path.

In the present embodiment, the main oil intake passage includes a P chamber 41, a fifth oil passage 21, a C chamber 42, and a check valve 51 provided in an oil passage communicating between the C chamber 42 and the D chamber 45. In some hydraulic systems, the main oil feed passage may eliminate the fifth oil passage 21 and the C-chamber 42, and in some embodiments, the check valve 51 may also be eliminated, i.e., the P-chamber 41 may be directly connected to the D-chamber 45 through an oil passage in the valve body.

As shown in fig. 1, the oil inlet end of the first relief valve 55 is communicated with the working port a, and the oil outlet end is communicated with the cavity T1. When the pressure of the working port a exceeds the set pressure of the first relief valve 55, the first relief valve 55 is opened to relieve the pressure of the working port a, so as to avoid the occurrence of the condition that the pipeline bursts or the related hydraulic devices are damaged due to the excessively high pressure.

As shown in fig. 1, the valve body 30 is provided with an end cap 60 for forming a pilot control chamber at an end of the main valve stem, and a spring return mechanism 61 for pushing the neutral position of the main valve stem 10 is provided in the pilot control chamber at each end. The first electric proportional pilot valve 70 and the second electric proportional pilot valve 80 are installed in the valve body 30, and the pilot control output ports of the first electric proportional pilot valve 70 and the second electric proportional pilot valve 80 are respectively connected with the pilot control cavities of the first end and the second end of the main valve rod 10 through the pilot pipeline 73 in the valve body. The valve body 30 is provided with a pilot oil inlet 71 and a pilot oil return port 72 connected to the first electric proportional pilot valve 70, and a pilot oil inlet and a pilot oil return port connected to the second electric proportional pilot valve 80. In the hydraulic system, a pilot oil inlet is connected with a pilot pump or a pilot oil source valve and is used for supplying oil to the electric proportional pilot valve. The pilot oil return port is connected with the hydraulic oil tank through a pipeline and is used for returning oil of the electric proportion pilot valve. The pilot valve is integrated in the valve body, the pilot oil way is integrated in the valve body, the design of a complex end cover is omitted, and the cost is effectively reduced.

In the present embodiment, as shown in fig. 1, a spring return mechanism 61 is provided in the pilot control chamber at each end of the main valve stem 10, and the spring return mechanism 61 includes a spring seat 63 that abuts against an end portion of the main valve stem 10, and a return spring 62 whose both ends abut against the spring seat 63 and the end cap 60, respectively.

The reversing valve in this embodiment is used in a hydraulic system. In the hydraulic system, a P port of a valve body is connected with a hydraulic pump through a pipeline, a T port is connected with a hydraulic oil tank through a pipeline, oil return is realized, and an A working port is connected with a hydraulic executing piece to form a hydraulic loop. The hydraulic actuators are typically hydraulic cylinders for lifting actions of the working device, e.g. hydraulic cylinders are lifting cylinders of a forklift truck for lifting a fork carriage of the forklift truck. The large cavity (rodless cavity) of the lifting oil cylinder is connected with the working port A of the reversing valve. When the large cavity of the lifting oil cylinder is filled with oil, the lifting oil cylinder stretches, and the fork frame moves upwards. When the reversing valve is reversed to the opening of the oil return valve port of the cavity A, the piston rod of the lifting oil cylinder is retracted under the action of load, and the oil in the large cavity of the lifting oil cylinder returns to the oil tank through the port T of the reversing valve.

In this embodiment, when the main valve rod 10 moves from the middle position to the second end direction, when the movement displacement of the main valve rod is greater than the set value, the flow control valve port and the valve port a are opened by corresponding opening degrees, and the pressure oil entering the valve body from the port P flows from the port P to the large hydraulic cylinder cavity through the fifth oil groove 21, the flow control valve port, the cavity C42, the check valve 51, the cavity D45, the valve port a, the cavity a 44 and the cone valve 53 from the working port a, and the piston rod of the hydraulic cylinder extends. When pressure oil flows from the A cavity 44 to the A working port through the cone valve 53, the spring cavity of the cone valve 53 is communicated with the A working port through the oil through hole 57 on the valve core of the cone valve, and the pressure oil in the A cavity pushes up the valve core of the cone valve to flow to the A working port.

When the main valve rod moves from the middle position to the first end direction, the flow control valve port is in a cut-off state, the corresponding opening degree of the oil return port of the cavity A is opened after the main valve rod moves for a set stroke, the third shaft shoulder 15 is matched with the third sealing section 35, the valve port A is in a closed state, and oil in the cavity D45 cannot enter the cavity A. The oil return of the large cavity of the hydraulic oil cylinder flows to the hydraulic oil tank through the working port A, the cone valve 53, the oil return valve port of the cavity A and the cavity T1 43, so that the oil return is realized. When pressure oil flows from the working port A to the cavity A through the cone valve 53, the second end of the pressure relief oil duct 54 communicated with the spring cavity of the cone valve is exposed due to the movement of the first shaft shoulder 13 and is communicated with the first oil through groove 26, the spring cavity of the cone valve 53 is relieved, the pressure oil of the working port A pushes up the valve core of the cone valve, the cone valve 53 is communicated from the working port A to the cavity A, and return oil of the working port A flows through the cone valve 53 and the cavity A return oil valve port to return oil of the cavity T1.

When the main valve rod 10 is in the middle position, the first shaft shoulder 13 is matched with the wall surface of the first sealing section 33 of the valve rod cavity to shield the second end of the pressure relief oil duct 54, so that the oil in the spring cavity of the cone valve 53 cannot flow out through the pressure relief oil duct 54, and at the moment, if the oil in the working port A is in a relatively high pressure state due to the load action of the hydraulic oil cylinder, the valve core of the cone valve is in a closed state due to the hydraulic oil pressure of the working port A and the elastic action of the spring cavity of the cone valve. The cone valve 53 has better sealing performance than a slide valve, and has negligible internal leakage and even zero, thereby playing a role of hydraulic locking and realizing the load maintaining function of the working port A.

Embodiment two.

As shown in fig. 4, the reversing valve in the embodiment of the present utility model includes a valve body 30, a main valve stem 10 disposed in a valve stem cavity in the valve body, a compensation valve 52 having a load pressure lead-out oil path, a check valve 51, two safety valves, and two electric proportional pilot valves.

As shown in fig. 6, the main valve stem 10 is provided with a sixth shaft shoulder 11, a sixth oil passage groove 22, a fifth shaft shoulder 12, a fifth oil passage groove 21, a first shaft shoulder 13, a first oil passage groove 26, a second shaft shoulder 14, a second oil passage groove 23, a third shaft shoulder 15, a third oil passage groove 24, and a fourth shaft shoulder 16 in this order from left to right in the drawing from the first end to the second end. A fourth oil groove 25 is provided on the third shoulder 15, the fourth oil groove 25 dividing the third shoulder into a first middle shoulder 151 and a second middle shoulder 152. Each oil through groove is an annular oil through groove.

As shown in fig. 5, the valve stem cavity structure includes: seventh seal segment 31, P cavity 41, sixth seal segment 32, C cavity 42, first seal segment 33, T1 cavity 43, second seal segment 34, a cavity 44, third seal segment 35, D cavity 45, fourth seal segment 36, B cavity 46, fifth seal segment 37, T2 cavity 47, eighth seal segment 38.

The valve stem cavity is matched with the main valve stem as shown in fig. 4, and the following is concrete:

the seventh sealing section 31 is matched with the sixth shaft shoulder 11, and forms a sealing structure to block the communication between the pilot control cavity at the first end of the main valve rod and the oil path (P cavity) in the valve body. The seventh seal segment 31 supports and guides the first end of the main valve stem 10 such that the main valve stem 10 is capable of axial movement within the stem cavity of the valve body.

The P chamber 41 communicates with a P port on the valve body 30 for introducing pressure oil for driving the hydraulic actuator to operate, and communicates with the sixth oil passage groove 22 on the main valve stem 10.

The sixth seal segment 32 cooperates with the fifth shoulder 12 to form a flow control valve port that communicates or blocks the P chamber 41 and the C chamber 42.

The cylindrical side surface of the fifth shaft shoulder 12 is provided with a plurality of first axial oil guiding grooves 121 and second axial oil guiding grooves 122 with variable cross sections, wherein the second axial oil guiding grooves 122 are communicated with the sixth oil through grooves 22 on the main valve rod 10, and the first axial oil guiding grooves 121 are communicated with the fifth oil through grooves 21 on the main valve rod 10.

When the main valve rod 10 moves axially, the fifth shaft shoulder 12 on the main valve rod 10 is matched with the sixth sealing section 32 of the valve rod cavity, the sixth oil through groove 22 is communicated with the P cavity 41 through the second axial oil guiding groove 122 or the fifth oil through groove 21 is communicated with the C cavity 42 through the first axial oil guiding groove 121, a flow control valve port with the opening corresponding to the stroke of the main valve rod is formed, and a pressure difference is formed between the front end (P cavity) and the rear end (C cavity) of the flow control valve port. The C-chamber 42 communicates with the sixth oil passage 22.

The first sealing section 33 is matched with the first shaft shoulder 13 and used for isolating the C cavity 42 from the T1 cavity 43; the T1 chamber 43 communicates with a T port in the valve body. In the hydraulic system, the T port is connected with a hydraulic oil tank through a pipeline to realize oil return of the hydraulic system. The T1 chamber 43 communicates with the first oil passage 26 on the main valve stem.

The second seal segment 34 cooperates with the second shoulder 14 to form an a-cavity oil return valve port that communicates or blocks the T1 cavity 43 and the second oil sump 23. The second oil drain groove 23 communicates with the a cavity 44. When the main valve rod 10 moves from the middle position to the first end direction, the A cavity oil return valve port is opened after the movement of the main valve rod 10 is positioned, and the opening of the A cavity oil return valve port is increased along with the increase of the movement stroke of the main valve rod until the valve port is fully opened. After the oil return valve port of the cavity A is opened, the oil in the cavity A44 flows to the cavity T1 43 through the oil return valve port of the cavity A, so that oil return of the working port A is realized. When the main valve rod 10 moves from the middle position to the second end direction, the oil return valve port of the cavity A is always in a closed and cut-off state.

The A cavity 44 is communicated with the second oil vent groove 23 on the main valve rod and is connected with an A working port on the valve body through a cone valve 53.

As shown in fig. 4, a cone valve 53 is provided in the valve body at the oil passage between the a chamber 44 and the a working port for communicating or blocking the flow of oil between the a chamber 44 and the a working port. Two oil ports of the cone valve 53 are respectively communicated with the A cavity 44 and the A working port; the valve core of the cone valve 53 is provided with an oil through hole 57 for communicating the cone valve spring cavity with the working port A, and the valve body 30 is internally provided with a pressure relief oil duct 54 communicated with the cone valve spring cavity. The first end of the relief oil passage 54 communicates with the cone valve spring cavity, and the second end of the relief oil passage 54 is disposed on the wall of the first seal segment 33 of the valve stem cavity. When the main valve rod 10 moves towards the first end direction, the first shaft shoulder 13 moves relative to the first sealing section 33 for corresponding displacement to expose the second end of the pressure relief oil duct 54 during opening of the oil return valve port of the cavity A, so that the second end of the pressure relief oil duct 54 is communicated with the cavity T1 through the first oil through groove 26, and oil in the conical valve spring cavity can flow out through the pressure relief oil duct 54. When the main valve rod 10 is in the middle position, the first shaft shoulder 13 is matched with the wall surface of the first sealing section 33 to shield the second end of the pressure relief oil duct 54, so that the pressure relief oil duct 54 is blocked, and the spring cavity oil of the cone valve 53 cannot flow out through the pressure relief oil duct 54.

The third seal segment 35 cooperates with the first intermediate shoulder 151 to form a port a that communicates or blocks the second oil sump 23 and the D cavity 45. When the main valve rod 10 moves from the middle position to the second end direction, the second oil vent groove 23 is communicated with the cavity D45, the valve port A is opened, and oil in the cavity D flows to the cavity A44 through the valve port A when the displacement of the main valve rod exceeds a certain value. When the main valve rod 10 moves from the neutral position to the first end direction, and when the main valve rod displacement exceeds a certain value, the fourth oil groove 25 is communicated with the A cavity 44, the regeneration valve port is opened, and the oil in the A cavity 44 flows to the direction of the D cavity 45 through the regeneration valve port.

The fourth seal segment 36 cooperates with the second intermediate shoulder 152 to form a port B that communicates or blocks the D cavity 45 and the third oil sump 24. When the main valve rod 10 moves from the middle position to the first end direction, and when the displacement of the main valve rod 10 exceeds a certain value, the third oil groove 24 is communicated with the D cavity 45, the B valve port is opened, and the oil in the D cavity 45 flows to the B cavity direction through the B valve port.

The B chamber 46 communicates with the third oil sump 24 and is connected to the B working port on the valve body.

The fifth seal segment 37 cooperates with the fourth shoulder 16 to form a B-chamber oil return port that communicates or blocks the third oil sump 24 and the T2 chamber 47. The T2 chamber 47 communicates with a T port in the valve body. The main valve rod 10 starts to move from the middle position to the second end direction, the third oil-through groove 24 is communicated with the T2 cavity 47 when the valve port A is opened, the oil return valve port B is opened, and oil in the cavity B46 flows to the cavity T2 through the third oil-through groove 24.

When the main valve rod 10 moves from the neutral position to the second end direction, the valve port B is always in a closed and cut-off state.

The eighth seal segment 38 is in clearance fit with the segment of the fourth shoulder 16 facing the second end and forms a seal that blocks the pilot control chamber at the second end of the main valve stem from communicating with the oil passage (T2 chamber) in the valve body. The eighth seal segment 28 supports and guides the main valve stem second end so that the main valve stem can move axially within the valve stem cavity of the valve body.

The oil inlet end of the compensation valve 52 is communicated with the C cavity, the oil outlet end of the compensation valve 52 is communicated with the oil inlet end of the one-way valve 51, and the oil outlet end of the one-way valve 51 is communicated with the D cavity 45. The pressure oil from the C chamber 42 flows through the compensation valve 52 and the check valve 51 to the D chamber 45, and flows to the a working port or the B working port through the a port or the B port, respectively. The load pressure signal is directed out through an oil passage in the compensating valve 52 to an LS port in the valve body. In this embodiment, the reversing valve directs out the load pressure signal through the compensating valve to form a load sensitive reversing valve for the load sensitive variable hydraulic system.

In the present embodiment, the main oil intake passage includes the P chamber 41, the fifth oil passage 21 or the sixth oil passage 22, the C chamber 42, the compensation valve 52 and the check valve 51 provided on the oil passage that communicates the C chamber and the D chamber. In some hydraulic systems, the main oil feed passage may eliminate fifth oil passage 21, sixth oil passage 22, and C-chamber 42. In some embodiments, the check valve 51 and the compensating valve 52 may be omitted, i.e., the P chamber 41 is directly connected to the D chamber through an oil passage in the valve body.

As shown in fig. 4, the oil inlet end of the first relief valve 55 communicates with the a working port, and the oil outlet end communicates with the T1 chamber. The oil inlet end of the second safety valve 56 is communicated with the working port B, and the oil outlet end is communicated with the cavity T2. When the pressure of the working port A or the working port B exceeds the set pressure of the corresponding safety valve, the corresponding safety valve is opened, the corresponding working port is decompressed, and the situation that a pipeline bursts or a hydraulic device is damaged due to the fact that the pressure is too high is avoided.

As shown in fig. 4, the valve body 30 has an end cap 60 for forming a pilot control chamber mounted in a position facing the first end of the main stem, and a plug for forming a pilot control chamber mounted in a position facing the second end of the main stem. The first electric proportional pilot valve 70 and the second electric proportional pilot valve 80 are installed in the valve body, and the pilot control output ports of the first electric proportional pilot valve 70 and the second electric proportional pilot valve 80 are respectively connected with the pilot control cavities of the first end and the second end of the main valve rod 10 correspondingly through the pilot pipeline 73 in the valve body. The valve body 30 is provided with a pilot oil inlet 71 and a pilot oil return port 72 which are communicated with the first electric proportional pilot valve 70, and a pilot oil inlet and a pilot oil return port which are communicated with the second electric proportional pilot valve 80. In the hydraulic system, a pilot oil inlet is connected with a pilot pump or a pilot oil source valve and is used for supplying oil to the electric proportional pilot valve. The pilot oil return port is connected with the hydraulic oil tank through a pipeline and is used for returning oil of the electric proportion pilot valve. The pilot valve is integrated in the valve body, the pilot oil way is integrated in the valve body, the design of a complex end cover is omitted, and the cost is effectively reduced.

In this embodiment, the spring return mechanism 61 is disposed only in the pilot control chamber at one end of the main valve stem, for example, in the pilot control chamber at the first end of the main valve stem, the pilot control chamber at the second end of the main valve stem is formed by the cooperation of the plug 66 or the end cap and the valve body 30 at the second end of the main valve stem, and the spring return mechanism is not disposed in the pilot control chamber at the second end of the main valve stem.

As shown in fig. 4, the spring return mechanism 61 disposed in the pilot control chamber at the first end of the main valve rod is a bidirectional return mechanism, and includes a first spring seat 64, a second spring seat 65, and a return spring 63 with two ends respectively abutting against the first spring seat 64 and the second spring seat 65, where the first spring seat is slidably sleeved on the extension rod 101 at the end of the main valve rod 10, and is used to push the main valve rod to move under the pushing of the return spring 63 towards the elastic force of the valve body and to abut against the valve body at the stroke terminal. The second spring seat 65 is slidably sleeved on the extension rod 101 at the end of the main valve rod, and is used for pushing the main valve rod to move under the pushing of the elastic force of the return spring 63 back to the valve body and abutting against the end cover 60 at the travel terminal.

When the main valve rod 10 moves from the middle position in the first end direction under the pushing of the pilot oil pressure of the pilot control cavity at the second end, the second spring seat 65 is kept in contact with the end cover 60, the first end of the main valve rod 10 pushes the first spring seat 64 to compress the return spring 63, and when the main valve rod 10 returns to the second end, the return spring 63 pushes the main valve rod 10 to move in the second end direction through the first spring seat 64 until the first spring seat 64 is in contact with the valve body 30.

When the main valve rod 10 moves from the middle position to the second end direction under the pushing of the pilot oil pressure of the pilot control cavity at the first end, the first spring seat 64 is kept in contact with the valve body 30, the extension rod 101 at the first end of the main valve rod 10 pulls the second spring seat 65 to compress the return spring 63, and when the main valve rod 10 returns to the first end, the return spring 63 pulls the main valve rod to move to the first end direction through the second spring seat until the second spring seat is in contact with the end cover.

In this embodiment, the cavity a 44 and the cavity B46 are adjacent to the cavity D45, and the oil flowing to the valve ports a and B is from the cavity D, so that the backflow of the oil in the working ports a and B towards the compensating valve 52 can be prevented by providing a check valve in the direction of the oil coming from the cavity D.

The reversing valve in this embodiment is used in a hydraulic system. In the hydraulic system, a P port of a valve body is connected with a hydraulic pump through a pipeline, and a T port is connected with a hydraulic oil tank through a pipeline, so that oil return is realized. The working port A and the working port B are connected with a hydraulic executing piece to form a hydraulic loop, and the hydraulic executing piece can be a hydraulic cylinder or a hydraulic motor and the like. Hydraulic systems are used in work machines such as loaders, excavators, and the like.

In the embodiment, when the main valve rod 10 moves from the middle position to the second end direction, when the movement displacement of the main valve rod is larger than the set value, the corresponding opening degrees of the flow control valve port, the A valve port and the B cavity oil return valve port are opened, pressure oil entering the valve body from the P port flows from the P cavity 41 to the hydraulic actuator from the A working port after flowing through the flow control valve port, the compensation valve 52, the one-way valve 51, the A valve port and the cone valve 53, and oil return of the hydraulic actuator flows to the hydraulic oil tank through the B working port, the B cavity oil return valve port and the T2 cavity 47, so that oil return is realized. When pressure oil flows from the A cavity 44 to the A working port through the cone valve 53, the spring cavity of the cone valve 53 is communicated with the A working port through the oil through hole 57 on the valve core of the cone valve, and the pressure oil in the A cavity pushes up the valve core of the cone valve to flow to the A working port.

In the front-stage travel, the flow control valve port, the oil return port of the cavity A and the corresponding opening of the valve port B are matched with the third sealing section 35, the valve port A is in a closed state, and oil in the cavity D45 cannot enter the cavity A. The oil return of the hydraulic executing part flows to the hydraulic oil tank through the working port A, the cone valve 53, the oil return valve port of the cavity A and the cavity T1 43, so that the oil return is realized. When pressure oil flows from the working port A to the cavity A through the cone valve 53, the second end of the pressure relief oil duct 54 communicated with the spring cavity of the cone valve is exposed due to the movement of the first shaft shoulder 13 and is communicated with the first oil through groove 26, the spring cavity of the cone valve 53 is relieved, the pressure oil of the working port A pushes up the valve core of the cone valve, the cone valve 53 is communicated from the working port A to the cavity A, and return oil of the working port A flows through the cone valve 53 and the cavity A return oil valve port to return oil of the cavity T1.

When the main valve rod 10 continues to move towards the first end direction and enters the rear-stage stroke, the valve port B is kept open, the first middle shaft shoulder 151 and the third sealing section 35 are separated from contact and enter the cavity A44, the fourth oil groove 25 is communicated with the cavity A44, and the regeneration valve port is opened. And the oil in the cavity D enters the cavity B through the valve port B and flows to the working port B, when the oil supply from the cavity P to the cavity B is insufficient, the oil return from the working port A can be forced to enter the cavity B through the regeneration valve port, the cavity D45 and the valve port B to form flow regeneration, the negative pressure phenomenon generated by negative load of the working port B is effectively solved, and if the hydraulic actuating mechanism is a hydraulic cylinder, differential connection is generated, so that the movement speed is accelerated.

When the main valve rod 10 is in the middle position, the first shaft shoulder 13 is matched with the wall surface of the first sealing section 33 of the valve rod cavity to shield the second end of the pressure relief oil duct 54, so that the oil in the spring cavity of the cone valve 53 cannot flow out through the pressure relief oil duct 54, and at the moment, if the oil in the working port A is in a relatively high pressure state due to the load action of the hydraulic oil cylinder, the valve core of the cone valve is in a closed state due to the hydraulic oil pressure of the working port A and the elastic action of the spring cavity of the cone valve. The cone valve 53 has better sealing performance than a slide valve, and has negligible internal leakage and even zero, thereby playing a role of hydraulic locking and realizing the load maintaining function of the working port A.

Embodiment three.

The present embodiment provides a hydraulic system having the reversing valve in the first or second embodiment.

Example four.

The present embodiment provides a working machine having the hydraulic system of the third embodiment, which may be an excavator, a loader, a road roller, a grader, an industrial vehicle such as a forklift, or the like.

Claims (10)

1. The reversing valve comprises a valve body (30) and a main valve rod (10) arranged in a valve rod cavity in the valve body, and is characterized in that a cone valve is arranged in the valve body, and a first shaft shoulder (13), a first oil through groove (26) adjacent to the first shaft shoulder, a second shaft shoulder (14), a second oil through groove (23) adjacent to the second shaft shoulder and a third shaft shoulder (15) adjacent to the second oil through groove are arranged on the main valve rod; the first oil passing groove and the second oil passing groove are arranged around the main valve rod;

the main valve stem cavity includes:

a first sealing section (33) which is matched with the first shaft shoulder (13);

a T1 cavity (43) communicated with a T port on the valve body;

the second sealing section (34) is matched with the second shoulder (14) to form an A cavity oil return valve port which is communicated or separated from the T1 cavity and the second oil through groove (23);

the cavity A (44) is communicated with the second oil through groove (23);

the cavity D is communicated with a main oil inlet oil way on the valve body;

the third sealing section (35) is matched with the third shaft shoulder (15) to form an A valve port which is communicated with or cuts off the second oil through groove (23) and the D cavity (45);

an oil inlet and an oil outlet of the cone valve (53) are respectively communicated with the cavity A and the working opening A on the valve body; the spring cavity of the cone valve is communicated with the working port A;

a pressure relief oil duct (54) is arranged in the valve body, a first end of the pressure relief oil duct is communicated with a spring cavity of the cone valve (53), and a second end of the pressure relief oil duct is arranged on a wall surface of a first sealing section of the valve rod cavity;

when the oil return valve port of the cavity A is opened, the second end of the pressure relief oil duct is communicated with the first oil through groove; when the oil return valve port of the cavity A is closed, the second end of the pressure relief oil duct is shielded and closed by the first shaft shoulder.

2. A reversing valve according to claim 1, characterized in that the main valve stem is further provided with a third oil groove (24) adjacent to the third shoulder (15), a fourth shoulder (16) adjacent to the third oil groove; the third oil groove is arranged around the main valve rod;

the valve stem cavity further comprises:

the cavity B (46) is communicated with the third oil-through groove (24) and is connected with a working port B on the valve body (30);

a T2 cavity (47) communicated with a T port on the valve body;

the fourth sealing section (36) is matched with the third shaft shoulder (15) to form a valve port B which is communicated with or cuts off the third oil groove (24) and the D cavity (45);

the fifth sealing section (37) is matched with the fourth shaft shoulder (16) to form a B cavity oil return valve port which is communicated or separated from the third oil groove (24) and the T2 cavity (47).

3. The reversing valve of claim 2, wherein:

an annular fourth oil groove (25) communicated with the D cavity is formed in the third shaft shoulder (15), the fourth oil groove surrounds the main valve rod and divides the third shaft shoulder (15) into a first middle shaft shoulder (151) located between the second oil groove (23) and the fourth oil groove and a second middle shaft shoulder (152) located between the third oil groove (24) and the fourth oil groove;

the third sealing section (35) is matched with the first middle shaft shoulder (151) to form an A valve port which is communicated with or cuts off the second oil through groove (23) and the D cavity, and a regeneration valve port which is communicated with or cuts off the A cavity (44) and the fourth oil through groove (25);

the fourth sealing section (36) is matched with the second middle shaft shoulder (152) to form a port B which is communicated or separated from the cavity D (45) and the third oil-through groove (24).

4. The reversing valve of claim 2, wherein:

a first safety valve (55) is further arranged in the valve body, the oil inlet end of the first safety valve is communicated with the working port A, and the oil outlet end of the first safety valve is communicated with the cavity T1.

5. The reversing valve of claim 4, wherein:

and a second safety valve (56) is further arranged in the valve body, the oil inlet end of the second safety valve is communicated with the working port B, and the oil outlet end of the second safety valve is communicated with the cavity T2.

6. A reversing valve according to claim 1, characterized in that the main valve stem (10) is further provided with a fifth oil groove (21) adjacent to the first shoulder (13); the fifth oil groove is arranged around the main valve rod;

the valve stem cavity further comprises:

the P cavity (41) is communicated with a P port on the valve body;

the C cavity (42) is communicated with the fifth oil groove (21);

a sixth sealing section (32) which is matched with the first shaft shoulder (13) to form a flow control valve port for communicating or isolating the C cavity and the fifth oil groove (21);

the main oil inlet oil path comprises: the oil duct comprises a P cavity (41), a fifth oil groove (21), a C cavity (42) and an oil duct which communicates the C cavity and the D cavity.

7. A reversing valve according to claim 2, characterized in that the main valve stem is further provided with a fifth shoulder (12), a fifth oil groove (21) and a sixth oil groove (22) adjoining the fifth shoulder; the fifth oil groove and the sixth oil groove are arranged around the main valve rod;

the valve stem cavity further comprises:

the P cavity (41) is communicated with the fifth oil groove (21) and communicated with a P port on the valve body;

the C cavity (42) is communicated with the sixth oil through groove (22);

the sixth sealing section (32) is matched with the fifth shaft shoulder (12) to form a flow control valve port for communicating or blocking the P cavity with the sixth oil through groove (22) and communicating or blocking the C cavity with the fifth oil through groove (21);

the main oil inlet oil path comprises: the oil duct is characterized by comprising a P cavity (41), a fifth oil through groove (21), a sixth oil through groove (22), a C cavity (42) and an oil duct which is communicated with the C cavity and the D cavity.

8. Reversing valve according to claim 6 or 7, characterized in that a compensating valve (52) and/or a non-return valve (51) of a load pressure signal lead-out oil circuit is arranged in the valve body on an oil duct communicating the C-chamber and the D-chamber.

9. A hydraulic system comprising a reversing valve according to any one of claims 1 to 8.

10. A work machine comprising the hydraulic system of claim 9.