Three-position four-way proportional reversing valve suitable for low-viscosity working medium

Abstract

The invention discloses a three-position four-way proportional directional valve suitable for low-viscosity working media, and belongs to the technical field of hydraulic elements, the three-position four-way proportional directional valve comprises a main valve and a pilot valve, the main valve comprises a main valve body, a first oil inlet valve element, a first oil return valve element, a second oil inlet valve element, a second oil return valve element, two first reset springs and two second reset springs; a main valve oil inlet, a main valve oil return opening, a first working oil opening, a second working oil opening, a first oil inlet valve element mounting hole, a second oil inlet valve element mounting hole, a first oil return valve element mounting hole and a second oil return valve element mounting hole are formed in the main valve body at intervals. The pilot valve is provided with a first control oil output port and a second control oil output port which are communicated with control cavities of the first oil inlet valve element and the second oil inlet valve element respectively, the proportional adjustment pilot valve controls the pressure of the oil output ports to proportionally adjust the opening degree of the corresponding valve ports of the main valve, and the valve ports of the main valve are sealed in a seat type mode, so that sealing is more reliable. And the internal leakage amount is small when the device is used under a low-viscosity medium and a high-pressure working condition.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic components, and particularly relates to a three-position four-way proportional reversing valve suitable for low-viscosity working media. Background Art

[0002] As the core support equipment in the fully mechanized coal mining face, the action precision and reliability of the coal mine hydraulic support directly affect the coal mining efficiency and safety. The hydraulic system uses water-based emulsion as the working medium, with low viscosity, high working pressure, and large flow rate. Traditional coal mine hydraulic supports use on-off three-position four-way reversing valves, which can only achieve on-off control and cannot adjust the flow rate as required, resulting in insufficient action precision of the supports and large opening and closing impacts. With the development of intelligent coal mining technology, the limitations of existing on-off valves have become increasingly prominent, and the demand for proportional reversing valves suitable for this working condition is becoming more urgent.

[0003] The on-off three-position four-way reversing valve of traditional hydraulic supports is actually realized by the cooperation of two two-position three-way seat valves, and its hydraulic symbol is as Figure 1 shown. Due to the use of the seat valve structure, the valve port seal is reliable and can adapt to the low-viscosity characteristics of water-based emulsion; however, this structure can only achieve on-off control and cannot achieve proportional control. The reason is that the proportional reversing valve needs to adjust the valve port opening from port P to port A and from port P to port B, that is, it needs to work in the transition position between the left position and the right position for a long time. For this two-position three-way seat valve, it either works in the left position, completely closing port P, or works in the right position, completely closing port T, and cannot stay in the middle position for a long time. Otherwise, the working oil ports A / B will be connected to both port P and port T at the same time, and the oil supply from port P to the working oil port will directly flow back to the oil tank through port T, and the hydraulic system cannot work.

[0004] For traditional high-pressure large-flow three-position four-way electro-hydraulic proportional reversing valves, both the main valve and the electro-hydraulic proportional pressure reducing valve used for pilot control adopt spool valve forms. The pressure of the main valve control chamber is adjusted by the electro-hydraulic proportional pressure reducing valve to control the displacement of the main valve spool, so as to achieve proportional control of the valve port opening.

[0005] However, for the spool valve structure, there is a clearance fit between the spool and the valve chamber. The greater the flow rate demand, the larger the spool diameter, and the larger the leakage channel area of the clearance fit, the greater the leakage. For the pilot valve, due to the small flow rate, the spool diameter is small. When using the spool valve structure, the clearance fit is well controlled and the internal leakage is within an acceptable range; but when the main valve spool adopts the spool valve structure, due to the large working flow rate, the spool diameter is large. To ensure that the spool does not get stuck, the clearance fit cannot be too small, which results in a large internal leakage between the main valve spool and the valve chamber. When the working medium viscosity is very low and the working pressure is high, the spool clearance leakage will be seriously excessive. In other words, traditional high-pressure large-flow electro-hydraulic proportional reversing valves, due to the use of the spool valve structure for the main valve spool, are only suitable for working media with higher viscosities and are not suitable for low-viscosity water-based emulsions.

[0006] Therefore, how to design a high-pressure and large-flow proportional reversing valve that can adapt to low-viscosity working media is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention aims to provide a three-position four-way proportional reversing valve suitable for low-viscosity working media to at least to some extent solve the problems in the prior art that the seat valve type reversing valve can only achieve on-off control and cannot achieve proportional control, while the spool valve type proportional reversing valve can achieve proportional control of the valve port opening but has a large internal leakage.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A three-position four-way proportional reversing valve suitable for low-viscosity working media, comprising a main valve and a pilot valve,

[0010] The main valve includes a main valve body, a first oil inlet spool, a first oil return spool, a second oil inlet spool, a second oil return spool, two first return springs and two second return springs;

[0011] The main valve body is provided with a main valve oil inlet, a main valve oil return port, a first working oil port, a second working oil port, a first oil inlet spool installation hole, a second oil inlet spool installation hole, a first oil return spool installation hole and a second oil return spool installation hole arranged at intervals;

[0012] The first oil inlet spool is slidably connected in the first oil inlet spool installation hole, the second oil inlet spool is slidably connected in the second oil inlet spool installation hole, the first oil return spool is slidably connected in the first oil return spool installation hole; the second oil return spool is slidably connected in the second oil return spool installation hole;

[0013] The first oil inlet spool installation hole and the second oil inlet spool installation hole have the same structural characteristics, and both include a first control cavity, a first oil inlet cavity, a first oil passage cavity, a first output cavity and a first oil return cavity connected in sequence. The first control cavity, the first oil passage cavity and the first oil return cavity have the same inner diameter; wherein, the first oil inlet cavities of the first oil inlet spool installation hole and the second oil inlet spool installation hole are both connected to the main valve oil inlet, and their first oil return cavities are both connected to the main valve oil return port; the first output cavity of the first oil inlet spool installation hole is connected to the first working oil port, and the first output cavity of the second oil inlet spool installation hole is connected to the second working oil port;

[0014] The first oil inlet valve core and the second oil inlet valve core have the same structural features, and both include a first control section, a first oil inlet section, a first throttling section, a first sealing section, and a first oil return section connected in sequence; the first control section and the first oil return section have the same diameter and are respectively sealed and slid in the first control cavity and the first oil return cavity, the first sealing section is slidably installed in the first output cavity, and it is provided with a first sealing surface in the shape of a conical surface or a spherical surface, and the maximum cross-sectional diameter of the first sealing surface is greater than the inner diameter of the first oil passage cavity; the first throttling section is slidably located in the first oil passage cavity, and the flow area between it and the first oil passage cavity increases as the displacement of the first throttling section away from the first control cavity increases; the first return spring is installed between the first oil return section and the end wall of the first oil return cavity;

[0015] The first oil return valve core installation hole and the second oil return valve core installation hole have the same structural features, and both include a second control cavity, a second oil inlet cavity, a second oil passage cavity, and a second oil return cavity connected in sequence; the second control cavity and the second oil passage cavity have the same inner diameter; wherein, the second oil return cavities of the first oil return valve core installation hole and the second oil return valve core installation hole are both connected to the main valve oil return port; the second oil inlet cavity of the first oil return valve core installation hole is connected to the second working oil port; the second oil inlet cavity of the second oil return valve core installation hole is connected to the first working oil port;

[0016] The first oil return valve core and the second oil return valve core have the same structural features, and both include a second control section, a second oil inlet section, and a second sealing section connected in sequence; the second control section is sealed and slid in the second control cavity, the second sealing section is slidably installed in the second oil return cavity, and it is provided with a second sealing surface in the shape of a conical surface or a spherical surface, and the maximum cross-sectional diameter of the second sealing surface is greater than the inner diameter of the second oil passage cavity; the second return spring is installed between the second sealing section and the end wall of the second oil return cavity;

[0017] The pilot valve includes a pilot valve body and a pilot valve core. The pilot valve body is provided with a pilot valve oil inlet, a pilot valve oil return port, a first control oil output port, a second control oil output port, and a pilot valve core installation hole; the pilot valve core is slidably installed in the pilot valve core installation hole, and both the first control oil output port and the second control oil output port are selectively connected to the pilot valve oil inlet and the pilot valve oil return port through the pilot valve core;

[0018] Among them, the first control chamber of the first oil inlet valve core mounting hole is connected to the first control oil output port; the second control chamber corresponding to the first oil return valve core mounting hole is connected to the first control oil output port or the first working oil port; the first control chamber of the second oil inlet valve core mounting hole is connected to the second control oil output port, and the second control chamber of the second oil return valve core mounting hole is connected to the second control oil output port or the second working oil port.

[0019] The beneficial effects that can be achieved by the present invention are as follows: the four oil ports of the main valve body are connected by valve cores of a seat valve structure, which respectively control the on-off and valve port opening between the main valve oil inlet and the first working oil port, the main valve oil inlet and the second working oil port, the first working oil port and the main valve oil return port, and the second working oil port and the main valve oil return port. The seat valve core realizes seat sealing by pressing the oil cavity port, which is more reliable and has very small internal leakage, and can be suitable for low-viscosity working media and high-pressure working conditions; and the first oil inlet valve core and the first oil return valve core can be synchronously controlled by the movement of the pilot valve core, so that the oil flow between the main valve oil inlet and the first working oil port of the main valve can be controlled, and the proportion of the oil flow between the second working oil port and the main valve oil return port can be controlled; and the second oil inlet valve core and the second oil return valve core can be synchronously controlled, so that the oil flow between the main valve oil inlet and the second working oil port can be controlled, and the proportion of the oil flow between the first working oil port and the main valve oil return port can be controlled.

[0020] Preferably, the pilot valve core is provided with two groups, and the two groups of pilot valve cores each include a pilot valve core body and a pilot valve spring. There are two pilot valve core mounting holes, and the two pilot valve core bodies are respectively slidably mounted in the two pilot valve core mounting holes, and one end thereof is respectively transmission-connected to the output end of the first proportional solenoid and the second proportional solenoid; the first oil return chamber of the first oil inlet valve core mounting hole and the first oil return chamber of the second oil inlet valve core mounting hole are respectively coaxially connected to the two pilot valve core mounting holes, and the two first return springs are both abutted between the corresponding first oil return section and the pilot valve body; the pilot valve spring is spaced apart in the corresponding first return spring and its two ends are respectively abutted against the corresponding pilot valve core body and the first oil return section;

[0021] Among them, the first control oil output port is switched to connect the pilot valve oil inlet port and the pilot valve oil return port through the pilot valve spool body corresponding to the first oil inlet valve spool mounting hole; the second control oil output port is switched to connect the pilot valve oil inlet port and the pilot valve oil return port through the pilot valve spool body corresponding to the second oil inlet valve spool mounting hole.

[0022] Preferably, the first proportional electromagnet and the second proportional electromagnet are both dry electromagnets, and a differential seal assembly is installed between the dry electromagnet and the pilot valve core body; a differential seal assembly installation hole is provided on the pilot valve body, and the differential seal assembly installation hole includes a first sealing hole with an inner diameter larger than the pilot valve core installation hole and a second sealing hole with an inner diameter larger than the first sealing hole, and the first sealing hole connects the pilot valve core installation hole and the second sealing hole; the cavity between the first sealing hole and the second sealing hole is connected to the atmosphere; the end of the pilot valve core body close to the dry electromagnet slides and extends into the first sealing hole, and an oil return channel connecting the first sealing hole and the pilot valve oil return port is provided inside the pilot valve core body; the differential seal assembly includes:

[0023] A sealing sleeve, the sealing sleeve being sealingly installed in the second sealing hole;

[0024] A differential piston, one end of which is sealingly and slidably connected to the first sealing hole, and the other end of which is sealingly and slidably connected to the second sealing hole;

[0025] A differential piston spring, one end of which abuts against the differential piston, and the other end of which abuts against a step surface between the first sealing hole and the pilot valve core mounting hole;

[0026] A force transmission rod, one end of which is sealed and slides in the sealing sleeve and is drivingly connected to the output end of the dry electromagnet, and the other end of which passes through the differential piston and abuts against the valve core body of the pilot valve;

[0027] A force transmission rod spring is sleeved on the force transmission rod body and its two ends are respectively in contact with the differential piston and the force transmission rod.

[0028] Preferably, the first proportional electromagnet and the second proportional electromagnet are both intrinsically safe electromagnets.

[0029] Preferably, the pilot valve core is provided with one, whose two ends are respectively connected to the output ends of the third proportional solenoid and the fourth proportional solenoid; under the drive of the third proportional solenoid, the first control oil output port is switchably connected to the pilot valve oil inlet and the pilot valve oil return port through the pilot valve core; under the drive of the fourth proportional solenoid, the second control oil output port is switchably connected to the pilot valve oil inlet and the pilot valve oil return port through the pilot valve core.

[0030] Preferably, a pressure reducing valve is installed on the oil inlet passage of the oil inlet of the pilot valve.

[0031] Preferably, a second throttling section is provided between the second sealing section of the first oil return valve core and the second oil return valve core and the second oil inlet section. The second throttling section is slidably located in the second oil passage cavity, and the flow area between it and the second oil passage cavity increases as the displacement of the second throttling section away from the second control cavity increases.

[0032] Preferably, the first oil return valve core and the second oil return valve core further include a diversion platform, which is fixed at one end of the second sealing section away from the second control section, and its diameter is larger than the maximum cross-sectional diameter of the second sealing surface.

[0033] Preferably, a damping type hydraulic control reversing valve is installed between the first working oil port and the main valve oil return port and / or between the second working oil port and the main valve oil return port.

[0034] Preferably, throttle dampers are installed in the oil inlet channels of the first control cavity and the second control cavity.

[0035] Through the above technical solutions, compared with the prior art, the present invention discloses a three-position four-way proportional reversing valve applicable to low-viscosity working media, having the following beneficial effects.

[0036] 1. For a conventional three-position four-way electro-hydraulic proportional reversing valve, the main valve adopts a spool structure, and the internal leakage is too large when working in low-viscosity working media and under high-pressure conditions. The proportional reversing valve of the present invention adopts valve cores with multiple seat valve structures to respectively control the on-off and valve opening degrees between the main valve oil inlet and the first working oil port, the main valve oil inlet and the second working oil port, the first working oil port and the main valve oil return port, and the second working oil port and the main valve oil return port. The seat-type valve core realizes sealing by pressing the oil passage cavity opening, the sealing is more reliable, the internal leakage is very small, and it can be applied to low-viscosity working media and high-pressure conditions.

[0037] 2. The pilot valve used in the present invention is connected to the oil inlet valve core of the main valve through a pilot valve spring, and can detect and feedback the displacement of the controlled main valve core to realize internal closed-loop control, so that the displacement of the controlled main valve core is only related to the output force of the corresponding proportional electromagnet, and has nothing to do with the friction force and hydraulic force received by the main valve core, and has nothing to do with the stiffness of the return spring of the main valve. There are fewer control interference factors, so the control accuracy is higher.

[0038] 3. The pilot valve spool of the present invention is provided with two groups. By controlling the input current of the first proportional electromagnet, the synchronous control of the first oil inlet spool and the first oil return spool can be achieved. By controlling the input current of the second proportional electromagnet, the synchronous control of the second oil inlet spool and the second oil return spool can be achieved. Thus, while realizing the proportional control between the main valve oil inlet and the first working oil port, the proportional control between the second working oil port and the main valve oil return port can also be realized; while controlling the proportion between the main valve oil inlet and the second working oil port, the proportional control between the first working oil port and the main valve oil return port can also be realized.

[0039] 4. When the pilot valve adopts a dry-type electromagnet, by adding a differential seal assembly, the effective thrust of the proportional electromagnet acting on the pilot valve spool will not be reduced when the pressure of the pilot valve oil return port increases.

[0040] 5. A damping type hydraulic control reversing valve is installed between the first working oil port and the main valve oil return port and / or between the second working oil port and the main valve oil return port, which can prevent the pressure of the first working oil port / second working oil port from rising due to the internal leakage from the main valve oil inlet to the first working oil port / second working oil port during the standby state, and is especially suitable for the working conditions where a hydraulic lock or a balance valve is installed on the working oil port. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0042] Figure 1 It is a symbol diagram of a switching type three-position four-way reversing valve of the prior art.

[0043] Figure 2 It is a structural diagram of a three-position four-way proportional reversing valve suitable for low-viscosity working media provided by the present invention.

[0044] Figure 3 It is a structural diagram of the main valve provided by the present invention.

[0045] Figure 4 It is a structural diagram of the main valve body provided by the present invention.

[0046] Figure 5 It is a structural diagram of the pilot valve provided by the present invention.

[0047] Figure 6 It is a structural diagram of the first pilot valve spool assembly adopting a wet-type electromagnet provided by the present invention.

[0048] Figure 7Structural diagram of the first pilot valve spool assembly provided by the present invention, which adopts a dry electromagnet.

[0049] Figure 8 Structural diagram of the first oil inlet spool of the present invention.

[0050] Figure 9 Structural diagram of the installation of a second throttle section on the first oil return spool of the present invention.

[0051] Figure 10 Structural diagram of the installation of another second throttle section on the first oil return spool of the present invention.

[0052] Figure 11 Structural diagram of the installation of a diversion platform on the first oil return spool of the present invention.

[0053] Figure 12 Structural diagram of a damping type hydraulic control reversing valve.

[0054] Figure 13 A hydraulic schematic diagram of a proportional reversing valve.

[0055] Figure 14 For Figure 13 The corresponding simplified hydraulic symbol diagram of the proportional reversing valve.

[0056] Figure 15 Another hydraulic schematic diagram of a proportional reversing valve.

[0057] Figure 16 For Figure 15 The corresponding simplified hydraulic symbol diagram of the proportional reversing valve.

[0058] Figure 17 Hydraulic schematic diagram of the two-stage pilot valve set by the present invention.

[0059] In the figure: 1. Main valve body, 101. Main valve oil inlet, 102. Main valve oil return port, 103. First working oil port, 104. Second working oil port, 105. First oil inlet spool installation hole, 1051. First control cavity, 1052. First oil inlet cavity, 1053. First oil passing cavity, 1054. First output cavity, 1055. First oil return cavity, 106. First oil return spool installation hole, 1061. Second control cavity, 1062. Second oil inlet cavity, 1063. Second oil passing cavity, 1064. Second oil return cavity; 107. Second oil inlet spool installation hole, 108. Second oil return spool installation hole;

[0060] 2. First oil inlet spool, 201. First control section, 202. First oil inlet section, 203. First throttle section, 2031. Throttle surface, 2032. Throttle notch, 204. First sealing section, 2041. First sealing surface, 205. First oil return section;

[0061] 3. First oil return valve core, 301. Second control section, 302. Second oil inlet section, 303. Second sealing section, 3031. Second sealing surface, 304. Second throttling section, 305. Flow guiding platform;

[0062] 4. Second oil inlet valve core;

[0063] 5. Second oil return valve core;

[0064] 6. First return spring;

[0065] 7. Second return spring;

[0066] 8. Pilot valve body, 801. Pilot valve oil inlet, 802. Pilot valve oil return port, 803. First control oil output port, 804. Second control oil output port, 805. Pilot valve spool mounting hole, 806. First sealing hole, 807. Second sealing hole, 808. Cavity;

[0067] 9. Pilot valve spool, 901. Pilot valve spool body, 9011. Oil return channel, 9012. First oil guiding ring groove, 9013. Second oil guiding ring groove, 902. Pilot valve spring;

[0068] 10. First proportional electromagnet;

[0069] 11. Second proportional electromagnet;

[0070] 12. Differential seal assembly, 1201. Sealing sleeve, 1202. Differential piston, 1203. Differential piston spring, 1204. Force transmission rod, 1205. Force transmission rod spring;

[0071] 13. Damping type hydraulic control reversing valve, 1301. Valve seat, 13011. Oil outlet hole, 1302. Damping valve core, 13021. Damping hole; 1303. Return spring;

[0072] 14. Valve sleeve, 1401. Valve sleeve oil passage. Specific embodiments

[0073] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0074] Please refer to Figures 2 - 17 , this embodiment discloses a three-position four-way proportional reversing valve suitable for low-viscosity working media, including a main valve and a pilot valve;

[0075] The main valve includes a main valve body 1, a first oil inlet valve core 2, a first oil return valve core 3, a second oil inlet valve core 4, a second oil return valve core 5, two first return springs 6 and two second return springs 7;

[0076] The main valve body 1 is provided with a main valve oil inlet 101 (hereinafter referred to as the P port), a main valve oil return port 102 (hereinafter referred to as the T port), a first working oil port 103 (hereinafter referred to as the A port), a second working oil port 104 (hereinafter referred to as the B port), a first oil inlet spool installation hole 105, a first oil return spool installation hole 106, a second oil inlet spool installation hole 107, and a second oil return spool installation hole 108, which are arranged at intervals;

[0077] The first oil inlet spool 2 is slidably connected in the first oil inlet spool installation hole 105, the second oil inlet spool 4 is slidably connected in the second oil inlet spool installation hole 107, the first oil return spool 3 is slidably connected in the first oil return spool installation hole 106, and the second oil return spool 5 is slidably connected in the second oil return spool installation hole 108;

[0078] The first oil inlet spool installation hole 105 and the second oil inlet spool installation hole 107 have the same structural characteristics, and both include a first control cavity 1051, a first oil inlet cavity 1052, a first oil passing cavity 1053, a first output cavity 1054, and a first oil return cavity 1055 that are connected in sequence. The first control cavity 1051, the first oil passing cavity 1053, and the first oil return cavity 1055 have the same inner diameter; among them, the first oil inlet cavities 1052 of the first oil inlet spool installation hole 105 and the second oil inlet spool installation hole 107 are both connected to the P port, and their first oil return cavities 1055 are both connected to the T port; the first output cavity 1054 of the first oil inlet spool installation hole 105 is connected to the A port, and the first output cavity 1054 of the second oil inlet spool installation hole 107 is connected to the B port.

[0079] The first oil inlet spool 2 and the second oil inlet spool 4 have the same structural characteristics, and both include a first control section 201, a first oil inlet section 202, a first throttling section 203, a first sealing section 204, and a first oil return section 205 that are connected in sequence; the first control section 201 and the first oil return section 205 have the same diameter and are respectively sealed and slid in the first control cavity 1051 and the first oil return cavity 1055. The first sealing section 204 is slidably installed in the first output cavity 1054, and it is provided with a first sealing surface 2041 in the shape of a conical surface or a spherical surface. The maximum cross-sectional diameter of the first sealing surface 2041 is greater than the inner diameter of the first oil passing cavity 1053; the first throttling section 203 is slidably located in the first oil passing cavity 1053, and the flow area between it and the first oil passing cavity 1053 increases as the displacement of the first throttling section 203 away from the first control cavity 1051 increases; the first return spring 6 is installed between the first oil return section 205 and the end wall of the first oil return cavity 1055.

[0080] Actually, the first oil return cavity 1055 is the inner cavity of the valve sleeve 14 installed in the first output cavity 1054. The valve sleeve 14 is provided because the maximum cross-sectional diameter of the first sealing section 204 is greater than the diameter of the first oil return section 205, and it cannot be directly installed through the first oil return cavity 1055. A sealing ring is provided between the valve sleeve 14 and the first output cavity 1054, and a valve sleeve oil passage 1401 is provided in it for communicating its inner cavity with the main valve oil return port 102.

[0081] The first oil return valve core installation hole 106 and the second oil return valve core installation hole 108 have the same structural characteristics, and both include a second control cavity 1061, a second oil inlet cavity 1062, a second oil passage cavity 1063, and a second oil return cavity 1064 that are connected in sequence; the inner diameters of the second control cavity 1061 and the second oil passage cavity 1063 are the same; among them, the second oil return cavities 1064 of the first oil return valve core installation hole 106 and the second oil return valve core installation hole 108 are both connected to the main valve oil return port 102; the second oil inlet cavity 1062 of the first oil return valve core installation hole 106 is connected to port B; the second oil inlet cavity 1062 of the second oil return valve core installation hole 108 is connected to port A.

[0082] The first oil return valve core 3 and the second oil return valve core 5 have the same structural characteristics, and both include a second control section 301, a second oil inlet section 302, and a second sealing section 303 that are connected in sequence; the second control section 301 is sealed and slid in the second control cavity 1061, the second sealing section 303 is slidably installed in the second oil return cavity 1064, and it is provided with a second sealing surface 3031 in the shape of a conical surface or a spherical surface, and the maximum cross-sectional diameter of the second sealing surface 3031 is greater than the inner diameter of the second oil passage cavity 1063; the second return spring 7 is installed between the second sealing section 303 and the end wall of the second oil return cavity 1064.

[0083] The pilot valve is a three-position four-way proportional pressure reducing valve, which includes a pilot valve body 8 and a pilot valve core 9. The pilot valve body 8 is provided with a pilot valve oil inlet 801 (hereinafter referred to as port Px), a pilot valve oil return port 802 (hereinafter referred to as port Tx), a first control oil output port 803 (hereinafter referred to as port X1), port X2 (hereinafter referred to as port X2), and a pilot valve core installation hole 805; the pilot valve core 9 is slidably installed in the pilot valve core installation hole 805, and both port X1 and port X2 can be selectively connected to port Px and port Tx through the pilot valve core 9.

[0084] Among them, the first control cavity 1051 of the first oil inlet valve core installation hole 105 is connected to port X1; the second control cavity 1061 corresponding to the first oil return valve core installation hole 106 is connected to port X1 or port A; the first control cavity 1051 of the second oil inlet valve core installation hole 107 is connected to port X2, and the second control cavity 1061 of the second oil return valve core installation hole 108 is connected to port X2 or port B.

[0085] In the initial state, each spool of the main valve can make the sealing surface tightly press against the outlet of the oil passage through the corresponding return spring to cut off the corresponding oil passage, forming a seat-type seal, which is more reliable in sealing and has a small internal leakage when used under low-viscosity media and high-pressure working conditions.

[0086] As Figure 2 shown, the pilot valve body 8 is connected in parallel with the main valve body 1. The end wall of the first oil return chamber 1055 connected to the first return spring 6 and the end wall of the second oil return chamber 1064 connected to the second return spring 7 refer to the end wall of the pilot valve body 8. When there is no contact between the pilot valve body 8 and the main valve body 1, valve covers should be provided in the first oil return chamber 1055 and the second oil return chamber 1064. At this time, the end wall of the first oil return chamber 1055 or the second oil return chamber 1064 connected to the corresponding return spring refers to the inner wall of its valve cover.

[0087] In actual production, the three-position four-way valve usually requires the performance of the two working positions on both sides to be symmetrical. Therefore, preferably, the structural dimensions of the first inlet spool 2 and the second inlet spool 4 are the same, the structural dimensions of the first inlet spool mounting hole 105 and the second inlet spool mounting hole 107 are the same, and the structural dimensions of the two first return springs 6 are the same; the structural dimensions of the first oil return spool 3 and the second oil return spool 5 are the same, the structural dimensions of the first oil return spool mounting hole 106 and the second oil return spool mounting hole 108 are the same, and the structural dimensions of the two second return springs 7 are the same. However, if the proportional directional valve requires the performance of the two working positions on both sides to be asymmetrical, the originally preferred same structural features can also be designed differently according to the working needs.

[0088] To simplify the structure of the directional valve and reduce the external pipelines, the pilot valve is preferably internally controlled and internally drained, that is, the pressure oil at the Px port comes from the P port, and the Tx port converges to the T port; however, according to the specific working conditions, the pilot valve can also be set to internally controlled and externally drained, the pressure oil at the Px port comes from the P port while the Tx port is separately connected to the external oil tank; when externally controlled and internally drained, the pressure oil at the Px port comes from another pressure oil source while the Tx port converges to the T port, and when externally controlled and externally drained, the pressure oil at the Px port comes from another pressure oil source while the Tx port is separately connected to the external oil tank and other forms. These forms have their own advantages and disadvantages, which are common knowledge for those skilled in the art. Here, only the possible connection forms of several oil ports of the pilot valve component are described.

[0089] When the pressure oil at the Px port of the pilot valve component comes from the P port, preferably, a pressure reducing valve is installed between the P port and the Px port, that is, the P port is connected to the Px port after being reduced in pressure by the pressure reducing valve. The advantage is that the pressure at the Px port of the pilot valve is reduced, making the internal leakage of the pilot valve with a spool structure significantly reduced, which is very important for the working condition where the working medium is a low-viscosity water-based emulsion.

[0090] To reduce the risk of the pilot valve spool getting stuck, preferably, a filter is installed on the oil inlet passage of the Px port. When the P port is connected to the Px port after being decompressed by a pressure reducing valve, the filter is preferably installed at the inlet of the pressure reducing valve.

[0091] The pilot valve adopts internal control and internal drainage. The P port is connected to the Px port of the pilot valve through a filter and then a pressure reducing valve. In the middle position, the design is that P, A, B, and T are not connected to each other. The hydraulic schematic diagram of the proportional directional valve is as Figure 13 shown, and its corresponding simplified hydraulic symbol is as Figure 14 shown.

[0092] The pilot valve adopts internal control and internal drainage. The P port is connected to the Px port of the pilot valve through a filter and then a pressure reducing valve. In the middle position, the P port is blocked, and the A port and the B port are connected to the T port through a damped hydraulic control directional valve. The hydraulic schematic diagram of the proportional directional valve is as Figure 15 shown, and its corresponding simplified hydraulic symbol is as Figure 16 shown.

[0093] In one embodiment, as Figure 8 , the first throttling section 203 has a conical throttling surface 2031. When the first sealing surface 2041 is a conical surface, the cone angle of the throttling surface 2031 can be less than or equal to or greater than the cone angle of the first sealing surface 2041. In another embodiment, the first throttling section 203 is a cylindrical structure, and a plurality of throttling slots 2032 are circumferentially and uniformly opened on its side wall. The throttling slots 2032 penetrate through the end wall of the first throttling section 203 close to one end of the first control section 201. The throttling slots 2032 can be U-shaped or triangular. The purpose of setting the first throttling section 203 is that when the main valve inlet spool compresses the first return spring 6 and increases the displacement amount, the valve port opening can be increased through the first throttling section 203 to achieve proportional control. In actual production, the first throttling section 203 with a conical throttling surface 2031 is preferably selected for easy processing.

[0094] As Figure 9 , a second throttling section 304 is installed between the second sealing section 303 and the second oil inlet section 302 of the first oil return spool 3 and the second oil return spool 5. The second throttling section 304 slides in the second oil passing cavity 1063, and the flow area between it and the second oil passing cavity 1063 increases as the displacement amount of the second throttling section 304 away from the second control cavity 1061 increases. The second throttling section 304 has the same structure as the first throttling section 203, and a conical throttling surface 2031 or throttling slots 2032 can be selected to be set. However, a throttling loss will inevitably occur when the second throttling section is set on the oil return spool. Therefore, the throttling section can be selectively set or removed on the oil return spool according to needs.

[0095] As Figure 10, a diversion platform 305 can be provided on the first oil return valve core 3 and the second oil return valve core 5. The diversion platform 305 can be a cylindrical structure, which is fixed at one end of the second sealing section 303 away from the second control section 301, and its diameter is larger than the maximum cross-sectional diameter of the second sealing surface 3031 of the second sealing section 303. When the flow rate is large and the hydrodynamic force on the valve core is large, the hydrodynamic force can be compensated by adding the diversion platform 305.

[0096] Such as Figure 2 , in the initial state, the P port, A port, B port, and T port of the main valve are not interconnected. However, although a seat valve core structure with good sealing effect is adopted, there is still a small amount of internal leakage from the P port to the A port and B port, and there is also a small amount of internal leakage from the A port and B port to the T port, which may cause the pressure of the A port and B port to rise in the standby state. Especially for the case where a hydraulic lock or balance valve is installed at the A port and B port, it may cause the hydraulic lock or balance valve to open due to the increase in the pressure of its control chamber (from the working oil port), resulting in the slow sliding of the actuator. To eliminate the above risks, a damping type hydraulic control reversing valve can be added between the A port and the T port and / or between the B port and the T port.

[0097] In a specific embodiment, refer to Figure 12 , the damping type hydraulic control reversing valve 13 provided by the present invention is integrated on the first oil return valve core 3 and / or the second oil return valve core 5, and it includes a valve seat 1301, a damping valve core 1302, and a return spring 1303. The valve seat 1301 is provided with an oil outlet hole 13011 communicating with the T port. A damping hole 13021 for communicating the pressure oil hole 3021 with the oil outlet hole 13011 is provided inside the damping valve core 1302, and its head is in a spherical structure or a conical structure. When the pressure of the A port is low, the damping valve core 1302 is in the Figure 12 position shown, and the head of the damping valve core 1302 is disengaged from the orifice of the valve seat 1301. At this time, the oil leaked from the P port to the A port can be discharged to the T port through the damping hole 13021 inside the valve core, and the pressure of the A port will not rise; once the first oil inlet valve core 2 is reversed and the P port supplies oil to the A port, the through diameter of the damping hole 13021 inside the damping valve core 1302 is small, so the oil discharge amount is much lower than the oil supply amount from the P port to the A port, and the pressure of the A port rises. Then, the hydraulic pressure of the A port on the damping valve core 1302 overcomes the elastic force of the return spring 1303, driving the damping valve core 1302 to move upward. The head of the damping valve core 1302 presses against the bottom orifice of the valve seat 1301, cutting off the damping channel from the A port to the T port. The damping type hydraulic control reversing valve 13 can also adopt any hydraulic control reversing valve with damping in the prior art, and it can also be installed at other positions and not necessarily integrated on the first oil return valve core 3 or the second oil return valve core 5.

[0098] In a specific embodiment, such as Figure 2As shown, there are two groups of pilot valve cores 9, and both groups of pilot valve cores 9 include a pilot valve core body 901 and a pilot valve spring 902. There are two pilot valve core mounting holes 805. The two pilot valve core bodies 901 are respectively slidably mounted in the two pilot valve core mounting holes 805, and one end thereof is respectively transmission-connected to the output ends of the first proportional solenoid 10 and the second proportional solenoid 11; the first oil return chamber (1055) of the first oil inlet valve core mounting hole 105 and the first oil return chamber (1055) of the second oil inlet valve core mounting hole 107 are respectively coaxially connected to the two pilot valve core mounting holes 805, and the two first return springs 6 are both abutted between the corresponding first return oil section 205 and the pilot valve body 8; the pilot valve spring 902 is spaced apart in the corresponding first return spring 6, and its two ends are respectively abutted against the corresponding pilot valve core body 901 and the first return oil section 205;

[0099] Among them, under the drive of the first proportional solenoid valve 10, the first control oil output port 803 is switched to connect the pilot valve oil inlet port 801 and the pilot valve oil return port 802 through the pilot valve core body 901 corresponding to the first oil inlet valve core mounting hole (105); under the drive of the second proportional solenoid valve 10, the X2 port is switched to connect the pilot valve oil inlet port 801 and the pilot valve oil return port 802 through the pilot valve core body 901 corresponding to the second oil inlet valve core mounting hole (107).

[0100] In some embodiments, the coal mine hydraulic support usually has explosion-proof requirements, so the first proportional electromagnet 10 and the second proportional electromagnet 11 are both intrinsically safe electromagnets.

[0101] A first oil guide ring groove 9012 and a second oil guide ring groove 9013 are arranged on the pilot valve core body 901 at intervals; wherein, the first oil guide ring groove 9012 of the pilot valve core body 901 corresponding to the first oil inlet valve core 2 is used to connect the oil circuit between the Px port and the X1 port, and the second oil guide ring groove 9013 is used to connect the oil circuit between the X1 port and the Tx port; the first oil guide ring groove 9012 of the pilot valve core body 901 corresponding to the second oil inlet valve core 4 is used to connect the oil circuit between the Px port and the X2 port, and the second oil guide ring groove 9013 is used to connect the oil circuit between the X2 port and the Tx port.

[0102] The two pilot valve cores 9 work in the same way. Take the pilot valve core 9 corresponding to the first oil inlet valve core 2 as an example:

[0103] In the initial state, port X1 is connected to port Tx, and after reversing, port X1 is connected to port Px. The valve port flow distribution of port X1 adopts zero cover or negative cover.

[0104] Taking the pilot valve core 9 corresponding to the first oil inlet valve core 2 as an example, zero coverage means that the width of the distribution cylinder (i.e., the width of the pilot valve core body 901 between the first oil guide ring groove 9012 and the second oil guide ring groove 9013) is exactly equal to the diameter of the distribution hole of the X1 port (i.e., the diameter of the oil path hole connecting the X1 port with the pilot valve core mounting hole 805). In this way, when the distribution cylinder of the pilot valve core body 901 is just aligned with the distribution hole on the pilot valve body 8, the X1 port is in a critical state of being connected and disconnected with the Px port and the Tx port at the same time. In this critical state, if the valve core moves down slightly, the X1 port is connected to the Px port and disconnected from the Tx port, so that the pressure of the X1 port rises; if the valve core moves up slightly, the X1 port is disconnected from the Px port and connected to the Tx port, so that the pressure of the X1 port drops.

[0105] Negative covering means that the width of the distribution cylinder is slightly smaller than the diameter of the X1 distribution hole. The advantage of using negative covering is that when the distribution cylinder is in the middle of the distribution hole, the X1 port is connected to the Px port and the Tx port with a small opening, forming a hydraulic half bridge, and the pressure fluctuation of the X1 port is smaller. Therefore, the best distribution method is negative covering.

[0106] Taking the first oil inlet valve core 2 as an example, the first proportional solenoid 10 push rod extends downward and drives the pilot valve core body 901 to move downward to open the X1 port and Px port channels, so that the X1 port pressure rises. The increase in X1 port pressure drives the first oil inlet valve core 2 on the main valve to move upward, and the upward movement of the first oil inlet valve core 2 compresses the pilot valve spring 902 to increase its force on the pilot valve core body 901. When the elastic force of the pilot valve spring 902 is greater than the push rod thrust, the spring force drives the solenoid push rod to retract, and the pilot valve core body 901 moves upward until the distribution cylinder of the pilot valve core body 901 is aligned with the distribution hole of the X1 port and stops. The greater the input current of the first proportional solenoid 10, the greater the thrust of its push rod on the pilot valve core 9, so the first oil inlet valve core 2 needs to be displaced upward and the pilot valve spring 902 needs to be compressed more to overcome the thrust of the solenoid push rod, so that the pilot valve core body 901 stops when the distribution cylinder is aligned with the distribution hole. That is, the pilot valve detects the displacement of the first oil inlet valve core 2 of the control object through the pilot valve spring 902, and the displacement of the first oil inlet valve core 2 determines the valve opening from the P port to the A port, which is converted into an elastic force signal feedback to act on the pilot valve core body 901, and is balanced with the thrust of the proportional solenoid push rod on the pilot valve core body 901, thereby forming a displacement-force feedback closed-loop control between the control input proportional solenoid input current and the displacement of the controlled first oil inlet valve core 2. The displacement control accuracy of the first oil inlet valve core 2 mainly depends on the input current-output force characteristic curve of the proportional solenoid, and has nothing to do with the hydraulic force and friction force exerted on the first oil inlet valve core 2. Therefore, the control accuracy of the main valve core can be effectively improved.

[0107] The proportional solenoid can be selected as dry type or wet type according to the needs.

[0108] When a dry-type electromagnet is adopted, the push rod of the electromagnet should be self-sealed or a differential seal assembly 12 is installed between the push rod of the electromagnet and the pilot valve spool body 901. When installing the differential seal assembly 12, a differential seal assembly installation hole is formed in the pilot valve body 8. The differential seal assembly installation hole includes a first seal hole 806 with an inner diameter larger than that of the pilot valve hole and a second seal hole 807 with an inner diameter larger than that of the first seal hole 806. The first seal hole 806 communicates with the pilot valve spool installation hole 805 and the second seal hole 807; one end of the pilot valve spool body 901 close to the dry-type electromagnet slides and extends into the first seal hole 806, and an oil return passage 9011 communicating the first seal hole 806 with the pilot valve oil return port 802 is formed inside it.

[0109] The differential seal assembly 12 includes: a seal sleeve 1201, a differential piston 1202, a differential piston spring 1203, a force transmission rod 1204 and a force transmission rod spring 1205. The seal sleeve 1201 is hermetically installed in the second seal hole 807 through a sealing ring; one end of the differential piston 1202 is hermetically and slidably connected in the first seal hole 806, and the other end is hermetically and slidably connected to the second seal hole 807; one end of the differential piston spring 1203 abuts against the differential piston 1202, and the other end abuts against the step surface between the first seal hole 806 and the pilot valve spool installation hole 805; one end of the force transmission rod 1204 is hermetically and slidably in the inner cavity of the seal sleeve 1201 and is in transmission connection with the push rod of the dry-type electromagnet, and the other end passes through the differential piston 1202 and abuts against the pilot valve spool body 901, and a limiting ring is connected to the side wall of the other end; the force transmission rod spring 1205 is sleeved on the rod body of the force transmission rod 1204, and its two ends respectively abut against the differential piston 1202 and the limiting ring.

[0110] When the pressure at the Tx port increases, the pressure oil at the Tx port flows through the gap between the force transmission rod 1204 and the differential piston 1202, and acts on both ends of the differential piston 1202 at the same time. Since the upper area of the differential piston 1202 is larger than the lower area, the pressure oil drives the differential piston 1202 to move downward to compress the differential piston spring 1203 until the differential piston 1202 stops moving when the downward hydraulic pressure it receives is equal to the upward spring force. The spring force received by the differential piston 1202 includes the force of the differential piston spring 1203 and the force of the force transmission rod spring 1205; when the differential piston 1202 moves downward, it compresses the differential piston spring 1203 and also compresses the force transmission rod spring 1205. The greater the pressure at the Tx port, the greater the stroke of the differential piston 1202, the greater the compression amount of the force transmission rod spring 1205, and the greater the downward spring force acting on the force transmission rod 1204.

[0111] By matching the diameters at both ends of the differential piston 1202, the diameter of the force transmission rod 1204, and the stiffnesses of the differential piston spring 1203 and the force transmission rod spring 1205, it is possible to achieve that the downward force of the force transmission rod spring 1205 on the force transmission rod 1204 exactly cancels out the upward hydraulic pressure generated by the pressure oil at the Tx port on the force transmission rod 1204. Thus, when the pressure at the Tx port changes, the force of the force transmission rod spring 1205 is automatically adjusted to compensate for the hydraulic pressure.

[0112] To make the downward force of the force transmission rod spring 1205 on the force transmission rod 1204 equal to the upward hydraulic pressure of the pressure oil at the Tx port on the force transmission rod 1204, it is necessary to match well the diameters at both ends of the differential piston 1202, the diameter of the force transmission rod 1204, and the stiffnesses of the differential piston spring 1203 and the force transmission rod spring 1205 in the design. The specific matching method is as follows:

[0113] Let the pressure at the Tx port be P tx , the diameter of the force transmission rod 1204 be d, the stiffness of the force transmission rod spring 1205 be k1, and the compression of the force transmission rod spring 1205 be Δ. To ensure complete compensation of the hydraulic pressure on the force transmission rod 1204 theoretically, it can be set that when P tx is 0, the compressions of both the force transmission rod spring 1205 and the differential piston spring 1203 are 0. Then when P tx rises, the downward displacement of the differential piston 1202, the compression of the differential piston spring 1203, and the compression of the force transmission rod spring 1205 are all Δ. Then the force balance equation of the force transmission rod 1204 is:

[0114]

[0115] During design, the value of the diameter d of the force transmission rod 1204 and P tx the maximum compression of the force transmission rod spring 1205 expected during the period of maximum pressure can be set according to the needs of the layout; and according to the operating conditions, P tx maximum value can be determined. Substituting the d value, P tx maximum value and the maximum compression Δ of the force transmission rod spring 1205 into equation (1), the stiffness k1 of the force transmission rod spring 1205 can be calculated.

[0116] Furthermore, let the difference in the effective acting areas of the hydraulic pressures at both ends of the differential piston 1202 be a, and the stiffness of the differential piston spring 1203 be k2. Then the force balance equation of the differential piston 1202 is:

[0117] P tx ·a = k 1 ·Δ + k 2 ·Δ (2)

[0118] Substituting the calculation data of formula (1) into formula (2), the relational expression between the area difference a of the differential piston 1202 and the stiffness k2 of the differential piston spring 1203 can be obtained. By setting one of the parameters, the other parameter can be calculated. After determining the area difference a of the differential piston 1202, according to the layout requirements, set one of the parameters of the diameters at both ends of the differential piston 1202, and then calculate the other parameter.

[0119] In another specific embodiment, refer to Figure 6 , both the first proportional electromagnet 10 and the second proportional electromagnet 11 are wet electromagnets. At this time, an oil chamber is reserved between the pilot valve spool body 901 and the push rod of the wet electromagnet. The oil return passage 9011 on the pilot valve spool body 901 is communicated with the oil chamber, so that the push rod of the wet electromagnet can be immersed in the oil, reducing the movement resistance of the pilot valve spool body 901 and improving the reliability and durability of commutation.

[0120] In some other embodiments, for the case where the output force of the proportional electromagnet used is relatively large, such as when there is no explosion-proof requirement for the pilot valve, and thus a proportional electromagnet with a larger power is used, the pilot valve can adopt a conventional three-position four-way proportional pressure reducing valve, that is, the pilot valve spool 9 is provided with one, and its two ends are respectively connected to the output ends of the third proportional electromagnet and the fourth proportional electromagnet. Driven by the third proportional electromagnet, the X1 port can be switched to communicate with the pilot valve inlet 801 and the pilot valve return port 802 through the pilot valve spool 9; driven by the fourth proportional electromagnet, the X2 port can be switched to communicate with the pilot valve inlet 801 and the pilot valve return port 802 through the pilot valve spool 9. The third proportional electromagnet and the fourth proportional electromagnet can select appropriate proportional electromagnets according to needs. At this time, although its control accuracy is relatively low, there is no mechanical connection relationship between the pilot valve spool 9 and the inlet spool of the main valve, so the installation position of the pilot valve relative to the main valve is more flexible.

[0121] For the case where the pilot valve adopts a three-position four-way proportional pressure reducing valve and the output force of the proportional electromagnet used is relatively small, such as when the proportional electromagnet is required to be intrinsically safe, the electromagnet has a small power and a small output force, and it is advisable to amplify the output signal of the pilot valve, that is, adopt a two-stage or more pilot valve. Figure 17 Shown is the hydraulic schematic diagram of the pilot valve of the proportional directional valve being a two-stage pilot valve.

[0122] In a specific embodiment, during the process of the pilot valve spool 9 and the main valve spool maintaining dynamic balance, due to reasons such as friction force fluctuations and external vibrations, the pilot valve spool may vibrate up and down at the critical point position, causing the pressure of the first control oil outlet 803 to vibrate, and then causing the main valve spool position to vibrate up and down, resulting in fluctuations in the valve opening and fluctuations in the oil supply flow rate. To suppress the position vibration of the main valve spool, throttle dampers are installed in the oil inlet channels of the first control chamber 1051 and the second control chamber 1061.

[0123] The working principle of a three-position four-way proportional directional control valve applicable to low-viscosity working media according to the present invention is as follows:

[0124] When the first proportional solenoid 10 is de-energized, or when its input current is small and the thrust of the solenoid push rod is not sufficient to overcome the force of the pilot valve spring 902, the pilot valve spool body 901 is in the Figure 2 shown initial position under the pre-pressure of the pilot valve spring 902. The metering cylinder surface cuts off the Px port and the X1 port, and the X1 port is connected to the Tx port. Then, the first control chamber connected to the X1 port is in a pressure relief state; for the solution where the second control chamber at the lower end of the first oil return spool 3 is also connected to the X1 port, the second control chamber at the lower part of the first oil return spool 3 is also in a pressure relief state.

[0125] At this time, for the first oil inlet spool 2, the first oil inlet spool 2 is pressed against the orifice of the first oil passage chamber 1053 by the first return spring 6 to form a seat-type seal, and the P port and the A port are cut off; since the diameters of the first control chamber 1051 and the first oil passage chamber 1053 are equal, the upward acting area and the downward acting area of the P port pressure on the first oil inlet spool 2 are equal, and the upward acting force and the downward acting force are equal, that is, the hydraulic pressure of the P port on the first oil inlet spool 2 is balanced by the first oil inlet spool 2 itself; since the diameters of the first oil passage chamber 1053 and the first oil return chamber 1055 are also equal, the upward acting area and the downward acting area of the A port pressure on the first oil inlet spool 2 are equal, and the upward acting force and the downward acting force are equal, that is, the hydraulic pressure of the A port on the first oil inlet spool 2 is also balanced by the first oil inlet spool 2 itself.

[0126] For the first oil return spool 3, the first oil return spool 3 is pressed against the outlet of the second oil passage chamber 1063 by its second return spring 7 to form a seat-type seal, and the B port and the T port are cut off. Since the diameters of the second control chamber 1061 and the second oil passage chamber 1063 are equal, the upward acting area and the downward acting area of the B port pressure on the first oil return spool 3 are equal, and the upward acting force and the downward acting force are equal, that is, the hydraulic pressure of the B port on the first oil return spool 3 is balanced by the first oil return spool 3 itself.

[0127] Similarly, when the second proportional solenoid 11 is de-energized or when the input current of the proportional solenoid is small and the thrust of the solenoid push rod is not sufficient to overcome the force of the pilot valve spring 902, the P port and the B port are cut off, and the A port and the T port are cut off. The hydraulic pressures of the P port pressure and the B port pressure on the second oil inlet spool 4 are balanced by the second oil inlet spool 4 itself, and the hydraulic pressure of the A port pressure on the second oil return spool 5 is balanced by the second oil return spool 5 itself.

[0128] Since the hydraulic pressures of the P port, the A port, and the B port on each spool are balanced by the spool itself, the control pressures required to control the axial displacement of each spool are theoretically independent of the pressures of the P port, the A port, and the B port.

[0129] It should be noted that, in order to achieve sealing by pressing the valve core sealing section against the orifice with spring force, it is necessary to ensure that the contact stress between the sealing surface and the corresponding oil-passing valve cavity outlet is greater than the maximum oil port pressure, and the required spring force is relatively large. Taking the first oil inlet valve core 2 as an example, if the spring force is to be reduced, the inner diameter of the first control cavity 1051 can be made slightly larger than the inner diameter of the first oil-passing cavity 1053. Accordingly, the dimensions of various parts of the first oil inlet valve core 2 are changed accordingly to maintain the sliding gap between the cavity wall. In this way, the hydraulic pressure of the first oil inlet valve core 2 by the pressure of the P port cannot be balanced, but a downward hydraulic pressure is generated, which acts together with the spring force to press the orifice. If this solution is adopted, because the first control section 201 of the first oil inlet valve core 2 has a large diameter and cannot be installed from the top through the first oil-passing cavity 1053, the bottom of the first control cavity 1051 needs to be opened and covered with a valve cover plate. At the same time, the first oil-passing section 202 and the first sealing section 204 of the first oil inlet valve core 2 need to be designed as a split type, which are installed from both sides and then connected together. Similarly, other valve cores can also adopt similar solutions, so that the hydraulic pressure of the oil port on the valve core is unbalanced and works together with the spring force to compress the orifice. However, when this solution is adopted, the fluctuation of the oil port pressure after the valve port is opened will destroy the balance state of the valve core, which is easy to cause the valve port opening to fluctuate, and then cause the oil supply flow to fluctuate. Unless the required spring force is too large and the layout is difficult, it is not recommended to use this solution.

[0130] When it is necessary for port P to supply oil to port A and port B to return oil to port T at the same time, the first proportional solenoid 10 is energized. The greater the current, the greater the thrust of the solenoid push rod. When the thrust of the solenoid push rod is greater than the thrust of the pilot valve spring 902 on the pilot valve spool, the pilot valve spool body 901 is driven to move downward, the distribution cylinder disconnects the channel between port X1 and port Tx, and opens the channel between port Px and port X1 at the same time, then the pressure at port X1 increases, the pressure in the first control chamber of the first oil inlet valve spool 2 and the second control chamber of the first oil return valve spool 3 increases, and after the liquid pressure of the pressure oil acting on the valve spool overcomes the spring pre-pressure of the corresponding valve spool, the first oil inlet valve spool 2 and the first oil return valve spool 3 move upward, the first sealing surface 2041 of the first oil inlet valve spool 2 is disconnected from the cavity port 1053 of the first oil passage cavity, the P port supplies oil to the A port, the second sealing surface 3031 of the first oil return valve spool 3 is disconnected from the cavity port 1063 of the second oil passage cavity, and the B port supplies oil to the T port.

[0131] When the first oil inlet valve core 2 moves upward, it will compress its corresponding pilot valve spring 902. Then, the spring force on the pilot valve core body 901 increases with the increase of the upward displacement of the first oil inlet valve core 2. The upward thrust of the pilot valve spring 902 on the pilot valve core body 901 counteracts the downward thrust of the proportional solenoid valve push rod on the pilot valve core body 901. Therefore, during the upward displacement of the first oil inlet valve core 2, the gradually increasing force of the pilot valve spring 902 will push the pilot valve core body 901 upward, causing the push rod of the proportional solenoid valve to retract until the flow distribution column surface of the pilot valve core body 901 aligns with the flow distribution hole, and the pressure at port X1 remains stable. Then, the pilot valve core body 901 and the first oil inlet valve core 2 stay at the current position. Because at this time, both between port X1 and port Px and between port X1 and port Tx of the pilot valve are at the on-off critical point. If the first oil inlet valve core 2 moves slightly upward, it will increase the force of the pilot valve spring 902, causing the pilot valve core body 901 to move upward, and then the pressure at port X1 will decrease. As a result, the first oil inlet valve core 2 will move downward and reset due to the decrease in the control oil pressure, and then the force of the pilot valve spring 902 will decrease, and the pilot valve core body 901 will move downward and reset. If the first oil inlet valve core 2 moves slightly downward, it will decrease the force of the pilot valve spring 902, causing the pilot valve core body 901 to move downward, and then the pressure at port X1 will increase. As a result, the first oil inlet valve core 2 will move upward due to the increase in the control oil pressure, and then the force of the pilot valve spring 902 will increase, and the pilot valve core body 901 will move upward and reset. In short, only when the pilot valve core body 901 stays at the critical point position and the flow distribution column surface aligns with the flow distribution hole can the dynamic balance be maintained, the pressure at port X1 remain unchanged, and the first oil inlet valve core 2 stay at the current position.

[0132] During the process of the pilot valve core body 901 maintaining dynamic balance, once the input current of the proportional solenoid valve is adjusted to change the push rod thrust of the proportional solenoid valve, the current balance will be broken until a new balance is re-established.

[0133] If the input current of the proportional solenoid valve is increased at this time, the downward thrust of the proportional solenoid valve push rod on the pilot valve core body 901 increases, driving the pilot valve core body 901 to move downward. While opening the channel between port X1 and port Px, it closes the channel between port X1 and port Tx. Then, the pressure at port X1 rises, and the first oil inlet valve core 2 moves upward. The upward displacement of the first oil inlet valve core 2 will further compress the corresponding pilot valve spring 902, increasing the upward spring force on the pilot valve core body 901, driving the proportional solenoid valve push rod to retract until the flow distribution column surface of the pilot valve core body 901 aligns with the flow distribution hole again, and the first oil inlet valve core 2 stays at the new position.

[0134] If the input current of the proportional solenoid is reduced at this time, the downward thrust of the proportional solenoid push rod on the pilot valve spool body 901 decreases, and the pilot valve spring 902 drives the pilot valve spool body 901 to move upward. While closing the channel between port X1 and port Px, the channel between port X1 and port Tx is opened. Then the pressure at port X1 decreases, and the first inlet valve spool 2 moves downward. The downward movement of the first inlet valve spool 2 will further reduce the compression amount of the pilot valve spring 902. The proportional solenoid push rod extends due to the decrease in spring force and drives the pilot valve spool body 901 to move downward until the metering cylinder surface of the pilot valve spool body 901 is aligned with the metering hole again, and the first inlet valve spool 2 stays at the new position.

[0135] Thus, by adjusting the output force of the first proportional solenoid, the displacement of the first inlet valve spool 2 can be adjusted, that is, the valve port channel area from port P to port A is adjusted, so as to realize the proportional control of the valve port opening from port P to port A. When the first proportional solenoid controls the displacement of the first inlet valve spool 2, the output force of the proportional solenoid push rod determines the compression amount of the pilot valve spring 902, and thus determines the displacement of the first inlet valve spool 2. The displacement determines the valve port opening. Therefore, the displacement of the first inlet valve spool 2 has nothing to do with the hydrodynamic force and frictional force acting on the first inlet valve spool 2, and has nothing to do with the stiffness of the corresponding first return spring 6, so the control accuracy is higher.

[0136] Furthermore, when the displacement of the first inlet valve spool 2 is determined, the axial force acting on the first inlet valve spool 2 is balanced. Ignoring the influence of the frictional force of the seal and the hydrodynamic force of the valve port, the upward acting force of the pressure oil input into the first control chamber on the valve spool is equal to the downward pressing force of the first return spring 6 on the first inlet valve spool 2. The spring stiffness is a fixed value. Therefore, the pressure at the first control oil inlet 105 is proportional to the displacement of the first inlet valve spool 2.

[0137] When the pressure oil at the X1 port is also connected to the second control chamber 1061 at the bottom of the first oil return spool 3, if the spring parameters and pre-compression amounts of the first oil inlet spool 2 and the first oil return spool 3 are the same and the inner diameter of the first control chamber 1051 where the first oil inlet spool 2 is located is the same as the inner diameter of the second control chamber 1061 where the first oil return spool 3 is located, then under the same control pressure, the theoretical displacement amounts of the first oil inlet spool 2 and the first oil return spool 3 are the same, and the theoretical opening degrees of the valve ports from the P port to the A port and from the B port to the T port are also the same. When the flow rate from the P port to the A port is the same as the flow rate from the B port to the T port, the hydrodynamic forces acting on the first oil inlet spool 2 and the first oil return spool 3 are also the same. Thus, by adjusting the output force of the first proportional electromagnet 10, proportional control of the valve port opening degree from the P port to the A port can be achieved, and at the same time, proportional control of the valve port opening degree from the B port to the T port can also be achieved. However, the control of the displacement amount of the first oil inlet spool 2 by the pilot valve is a displacement-force feedback closed-loop control, while the control of the displacement amount of the first oil return spool 3 is an open-loop control. Therefore, the control accuracy of the displacement amount of the first oil inlet spool 2 by the pilot valve is better than that of the displacement amount of the first oil return spool 3.

[0138] Similarly, by adjusting the output force of the second proportional electromagnet 11, proportional control of the valve port opening degree from the P port to the B port can be achieved, and at the same time, proportional control of the valve port opening degree from the A port to the T port can also be achieved.

[0139] In actual usage requirements, it may be required to only implement proportional control of the valve port opening degrees from the P port to the A port and from the P port to the B port, and it is not desired to have excessive throttling losses in the oil return from the A port to the T port and from the B port to the T port, thereby reducing energy loss and heat generation. Then, the first oil return spool 3 and the second oil return spool 5 are not provided with a throttling section. When there is no throttling section, a relatively small spool displacement amount can obtain a relatively large valve port opening degree.

[0140] Since the hydrodynamic force of the valve port tends to close the valve port, a flow guiding platform 305 can be added to the first oil return spool 3 and the second oil return spool 5 to compensate for the hydrodynamic force. The impact force of the valve port jet on the flow guiding platform 305 makes the valve port opening degree tend to increase, thereby realizing the compensation of the hydrodynamic force. By adjusting the structural parameters of the flow guiding platform 305, part or all of the hydrodynamic force can be offset, and the jet impact force can also be made greater than the valve port hydrodynamic force to further increase the valve port opening degree.

[0141] Further, if the minimum working pressure of port A and the minimum working pressure of port B in actual work are greater than the control pressure required for the maximum opening of the first oil return valve core 3 and the second oil return valve core 5, the second control chamber 1061 corresponding to the first oil return valve core 3 can be connected to port A, and the second control chamber 1061 corresponding to the second oil return valve core 5 can be connected to port B. Then, after the oil supply from port P to port A, the pressure oil at port A drives the first oil return valve core 3 to move, so that the valve port between port B and port T is fully opened. After the oil supply from port P to port B, the pressure oil at port B drives the second oil return valve core 5 to move, so that the valve port between port A and port T is fully opened.

[0142] In addition, it should be noted that when the working medium of the reversing valve is water-based emulsion, the parts in direct contact with the working medium need to be treated with rust prevention and corrosion protection, or anti-rust and anti-corrosion materials are used, such as stainless steel with strength and hardness meeting the working requirements.

[0143] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description in the method part.

[0144] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A three-position four-way proportional reversing valve suitable for low-viscosity working media, comprising a main valve and a pilot valve, characterized in that: The main valve comprises a main valve body (1), a first oil inlet valve core (2), a first oil return valve core (3), a second oil inlet valve core (4), a second oil return valve core (5), two first return springs (6) and two second return springs (7); The main valve body (1) is provided with a main valve oil inlet (101), a main valve oil return port (102), a first working oil port (103), a second working oil port (104), a first oil inlet valve core mounting hole (105), a second oil inlet valve core mounting hole (107), a first oil return valve core mounting hole (106) and a second oil return valve core mounting hole (108) arranged at intervals; The first oil inlet valve core (2) is slidably connected in the first oil inlet valve core mounting hole (105); the second oil inlet valve core (4) is slidably connected in the second oil inlet valve core mounting hole (107); the first oil return valve core (3) is slidably connected in the first oil return valve core mounting hole (106); the second oil return valve core (5) is slidably connected in the second oil return valve core mounting hole (108); The first oil inlet valve core mounting hole (105) and the second oil inlet valve core mounting hole (107) have the same structural features, and both include a first control chamber (1051), a first oil inlet chamber (1052), a first oil passage chamber (1053), a first output chamber (1054) and a first oil return chamber (1055) which are connected in sequence, and the first control chamber (1051), the first oil passage chamber (1053) and the first oil return chamber (1055) have the same inner diameter; wherein the first oil inlet valve core mounting hole (105 ) and the first oil inlet valve core mounting hole (107) are both connected to the main valve oil inlet port (101), and the first oil return chamber (1055) thereof is both connected to the main valve oil return port (102); the first output chamber (1054) of the first oil inlet valve core mounting hole (105) is connected to the first working oil port (103), and the first output chamber (1054) of the second oil inlet valve core mounting hole (107) is connected to the second working oil port (104); The first oil inlet valve core (2) and the second oil inlet valve core (4) have the same structural features, and both comprise a first control section (201), a first oil inlet section (202), a first throttling section (203), a first sealing section (204) and a first oil return section (205) which are connected in sequence; the first control section (201) and the first oil return section (205) have the same diameter and are sealed and slidable in the first control chamber (1051) and the first oil return chamber (1055) respectively; the first sealing section (204) is slidably mounted in the first output chamber (1054), and is provided with a first sealing surface (2041) in a conical or spherical shape, wherein the maximum cross-sectional diameter of the first sealing surface (2041) is larger than the inner diameter of the first oil passage cavity (1053); the first throttling section (203) is slidably located in the first oil passage cavity (1053), and the flow area between the first throttling section (203) and the first oil passage cavity (1053) increases as the displacement of the first throttling section (203) away from the first control cavity (1051) increases; and the first return spring (6) is installed between the first oil return section (205) and the end wall of the first oil return cavity (1055); The first oil return valve core mounting hole (106) and the second oil return valve core mounting hole (108) have the same structural features, and both include a second control chamber (1061), a second oil inlet chamber (1062), a second oil passage chamber (1063) and a second oil return chamber (1064) which are connected in sequence; the second control chamber (1061) and the second oil passage chamber (1063) have the same inner diameter; wherein the second oil return chamber (1064) of the first oil return valve core mounting hole (106) and the second oil return valve core mounting hole (108) are both connected to the main valve oil return port (102); the second oil inlet chamber (1062) of the first oil return valve core mounting hole (106) is connected to the second working oil port (104); the second oil inlet chamber (1062) of the second oil return valve core mounting hole (108) is connected to the first working oil port (103); The first oil return valve core (3) and the second oil return valve core (5) have the same structural features, and both comprise a second control section (301), a second oil inlet section (302) and a second sealing section (303) which are connected in sequence; the second control section (301) is sealingly slidable in the second control chamber (1061), the second sealing section (303) is slidably mounted in the second oil return chamber (1064), and is provided with a second sealing surface (3031) in a conical or spherical shape, the maximum cross-sectional diameter of the second sealing surface (3031) being larger than the inner diameter of the second oil passage chamber (1063); the second return spring (7) is mounted between the second sealing section (303) and the end wall of the second oil return chamber (1064); The pilot valve comprises a pilot valve body (8) and a pilot valve core (9); the pilot valve body (8) is provided with a pilot valve oil inlet (801), a pilot valve oil return port (802), a first control oil output port (803), a second control oil output port (804) and a pilot valve core mounting hole (805); the pilot valve core (9) is slidably mounted in the pilot valve core mounting hole (805); the first control oil output port (803) and the second control oil output port (804) are both switchably connected to the pilot valve oil inlet (801) and the pilot valve oil return port (802) through the pilot valve core (9); The first control chamber (1051) of the first oil inlet valve core mounting hole (105) is connected to the first control oil output port (803); the second control chamber (1061) corresponding to the first oil return valve core mounting hole (106) is connected to the first control oil output port (803) or the first working oil port (103); the first control chamber (1051) of the second oil inlet valve core mounting hole (107) is connected to the second control oil output port (804), and the second control chamber (1061) of the second oil return valve core mounting hole (108) is connected to the second control oil output port (804) or the second working oil port (104).

2. A three-position four-way proportional reversing valve suitable for low-viscosity working media according to claim 1, characterized in that: The pilot valve core (9) is provided with two groups, and the two groups of the pilot valve core (9) each include a pilot valve core body (901) and a pilot valve spring (902). The pilot valve core mounting holes (805) are provided with two, and the two pilot valve core bodies (901) are respectively slidably mounted in the two pilot valve core mounting holes (805), and one end of each pilot valve core body is respectively transmission-connected to the output end of the first proportional solenoid (10) and the output end of the second proportional solenoid (11); the first return line of the first oil inlet valve core mounting hole (105) is provided with a first return line of the first oil inlet valve core mounting hole (105). The oil chamber (1055) and the first oil return chamber (1055) of the second oil inlet valve core mounting hole (107) are coaxially connected to the two pilot valve core mounting holes (805), and the two first return springs (6) are both abutted between the corresponding first oil return section (205) and the pilot valve body (8); the pilot valve spring (902) is sleeved in the corresponding first return spring (6) at intervals, and its two ends are respectively abutted against the corresponding pilot valve core body (901) and the first oil return section (205); The first control oil output port (803) is connected to the pilot valve oil inlet port (801) and the pilot valve oil return port (802) by switching through the pilot valve core body (901) corresponding to the first oil inlet valve core mounting hole (105); the second control oil output port (804) is connected to the pilot valve oil inlet port (801) and the pilot valve oil return port (802) by switching through the pilot valve core body (901) corresponding to the second oil inlet valve core mounting hole (107).

3. A three-position four-way proportional reversing valve suitable for low-viscosity working media according to claim 2, characterized in that: The first proportional electromagnet (10) and the second proportional electromagnet (11) are both dry-type electromagnets, and a differential seal assembly (12) is installed between the dry-type electromagnet and the pilot valve core body (901); the pilot valve body (8) is provided with a differential seal assembly installation hole, and the differential seal assembly installation hole includes a first sealing hole (806) having an inner diameter greater than the pilot valve core installation hole (805) and a second sealing hole (807) having an inner diameter greater than the first sealing hole (806), and the first sealing hole (806) is provided with a plurality of sealing holes (807) having a plurality of sealing holes (807) having a plurality of sealing holes (806). ) connects the pilot valve core installation hole (805) and the second sealing hole (807); the chamber (808) between the first sealing hole (806) and the second sealing hole (807) is connected to the atmosphere; the end of the pilot valve core body (901) close to the dry electromagnet slides and extends into the first sealing hole (806) and is provided with an oil return channel (9011) connecting the first sealing hole (806) and the pilot valve oil return port (802); the differential seal assembly (12) comprises: A sealing sleeve (1201), the sealing sleeve (1201) being sealingly mounted in the second sealing hole (807); A differential piston (1202), one end of the differential piston (1202) is sealingly and slidably connected in the first sealing hole (806), and the other end of the differential piston (1202) is sealingly and slidably connected in the second sealing hole (807); A differential piston spring (1203), one end of the differential piston spring (1203) abuts against the differential piston (1202), and the other end abuts against a step surface between the first sealing hole (806) and the pilot valve core mounting hole (805); A force transmission rod (1204), one end of which is sealingly slidable in the sealing sleeve (1201) and drivingly connected to the output end of the dry electromagnet, and the other end of which passes through the differential piston (1202) and abuts against the pilot valve core body (901); A force transmission rod spring (1205), wherein the force transmission rod spring (1205) is sleeved on the rod body of the force transmission rod (1204) and its two ends are respectively in contact with the differential piston (1202) and the force transmission rod.

4. A three-position four-way proportional reversing valve suitable for low-viscosity working media according to claim 2 or 3, characterized in that: The first proportional electromagnet (10) and the second proportional electromagnet (11) are both intrinsically safe electromagnets.

5. A three-position four-way proportional reversing valve suitable for low-viscosity working media according to claim 1, characterized in that: The pilot valve core (9) is provided with one end, and its two ends are respectively connected to the output ends of the third proportional solenoid and the fourth proportional solenoid; under the drive of the third proportional solenoid, the first control oil output port (803) is switchably connected to the pilot valve oil inlet (801) and the pilot valve oil return port (802) through the pilot valve core (9); under the drive of the fourth proportional solenoid, the second control oil output port (804) is switchably connected to the pilot valve oil inlet (801) and the pilot valve oil return port (802) through the pilot valve core (9).

6. A three-position four-way proportional reversing valve suitable for low-viscosity working media according to claim 1, characterized in that: A pressure reducing valve is installed on the oil inlet passage of the pilot valve oil inlet (801).

7. A three-position four-way proportional reversing valve suitable for low-viscosity working media according to claim 1, characterized in that: A second throttling section (304) is provided between the second sealing section (303) and the second oil inlet section (302) of the first oil return valve core (3) and the second oil return valve core (5); the second throttling section (304) is slidably located in the second oil passage chamber (1063), and a flow area between the second throttling section (304) and the second oil passage chamber (1063) increases as the displacement of the second throttling section (304) away from the second control chamber (1061) increases.

8. The three-position four-way proportional reversing valve suitable for low-viscosity working medium according to claim 1, characterized in that: The first oil return valve core (3) and the second oil return valve core (5) further include a guide platform (305), the guide platform (305) being fixed to an end of the second sealing section (303) away from the second control section (301), and having a diameter greater than the maximum cross-sectional diameter of the second sealing surface (3031).

9. A three-position four-way proportional reversing valve suitable for low-viscosity working media according to claim 1, characterized in that: A damping type hydraulically controlled reversing valve is installed between the first working oil port (103) and the main valve oil return port (102) and / or between the second working oil port (104) and the main valve oil return port (102).

10. A three-position four-way proportional reversing valve suitable for low-viscosity working media according to claim 1, characterized in that: The oil inlet passages of the first control chamber (1051) and the second control chamber (1061) are both equipped with throttling dampers.

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