Switchable positive and negative proportional pressure reducing valve

Abstract

The present invention provides a pressure reducing valve that can switch between positive and negative proportions, and relates to the field of hydraulic control technology. The pressure reducing valve that can switch between positive and negative proportions includes a sliding valve assembly and a proportional electromagnet assembly; the sliding valve assembly includes a valve sleeve and a valve core, the valve core is provided with a working oil port, the valve sleeve is provided with an oil inlet and an oil outlet, and is sleeved with the valve core, slidingly cooperating with the valve core; the proportional electromagnet assembly includes a screw plug, a pole shoe, an armature, and an inner sleeve, the inner sleeve is sleeved with the armature, the first end of the pole shoe is inserted into the inner sleeve, and the proportional electromagnet assembly includes a first state and a second state; the first state is that the screw plug is inserted into the second end of the pole shoe, and the end of the valve sleeve away from the working oil port is inserted into the end of the inner sleeve away from the pole shoe; the second state is that the screw plug is inserted into the end of the inner sleeve away from the pole shoe, and the end of the valve sleeve away from the working oil port is inserted into the second end of the pole shoe; the armature is connected to the valve core to drive the valve core to slide. The present invention solves the technical problem that a single-function pressure reducing valve has a small scope of application.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic control, and in particular to a pressure reducing valve capable of switching between positive and negative proportions. Background Art

[0002] The proportional pressure reducing valve is a crucial electro-hydraulic conversion component. Its output pressure is solely dependent on the input current. Based on the different pressure reducing principles, it can be generally categorized as a direct proportional pressure reducing valve or an inverse proportional pressure reducing valve. A direct proportional pressure reducing valve's output pressure increases with increasing input current, while an inverse proportional pressure reducing valve's output pressure decreases with increasing input current. Both control methods are widely used in the hydraulic systems of construction machinery.

[0003] Currently, most proportional pressure reducing valves on the market have only one function: direct proportional or inverse proportional. However, in actual use, different functions are required according to the different requirements of different working conditions. A single function is far from meeting the requirements. Summary of the Invention

[0004] The object of the present invention is to provide a pressure reducing valve capable of switching between positive and negative proportions, so as to alleviate the technical problem in the prior art that the pressure reducing valve with a single function has a small application range.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] The pressure reducing valve capable of switching between positive and negative proportions provided by the present invention comprises a slide valve assembly and a proportional electromagnet assembly;

[0007] The sliding valve assembly includes a valve sleeve and a valve core, the valve core is provided with a working oil port, the valve sleeve is provided with an oil inlet and an oil outlet, and is sleeved with the valve core, and slidably cooperates with the valve core to achieve conduction or closing between the oil inlet, the oil outlet or the working oil port;

[0008] The proportional electromagnet assembly includes a screw plug, a pole shoe, an armature, and an inner bushing, wherein the inner bushing is sleeved with the armature, the first end of the pole shoe is inserted into the inner bushing, the pole shoe and the armature are spaced apart along the axial direction of the inner bushing, and the proportional electromagnet assembly includes a first state and a second state;

[0009] In the first state, the screw plug is inserted into the second end of the pole shoe, and the end of the valve sleeve away from the working oil port is inserted into the end of the inner sleeve away from the pole shoe. In the second state, the screw plug is inserted into the end of the inner sleeve away from the pole shoe, and the end of the valve sleeve away from the working oil port is inserted into the second end of the pole shoe.

[0010] The armature is connected to the valve core to drive the valve core to slide.

[0011] Preferably, the proportional solenoid assembly further comprises a first push rod and a second push rod, wherein the first push rod and the second push rod are respectively mounted on both sides of the armature;

[0012] One end of the second push rod facing away from the armature is inserted into the pole shoe to abut against the screw plug or the valve core, and one end of the first push rod facing away from the armature correspondingly abuts against the valve core or the screw plug.

[0013] Preferably, the proportional electromagnet assembly further comprises a limiting plate, and the limiting plate is located between the armature and the pole shoe.

[0014] Preferably, the inner sleeve is provided with a first through hole, and the pole shoe is provided in the first through hole;

[0015] A rectangular groove is provided on the inner wall of the first through hole, and the rectangular groove is arranged along the axis direction of the first through hole.

[0016] Preferably, an outer wall of the valve sleeve is provided with a protrusion, and the protrusion extends along the circumference of the valve sleeve.

[0017] Preferably, one end of the valve core is provided with a blind hole to form the working oil port;

[0018] The side wall of the blind hole is provided with a plurality of groups of oil holes, and the plurality of groups of oil holes are arranged at intervals along the axial direction of the blind hole.

[0019] Preferably, the outer wall of the valve core is provided with a plurality of groups of throttling grooves, and the plurality of groups of throttling grooves are arranged at intervals along the axial direction of the blind hole.

[0020] Preferably, the sliding valve assembly further comprises a compression spring and a connecting rod;

[0021] One end of the connecting rod is threadedly connected to the valve core, and the other end is provided with a first countersunk hole, and the inner wall of the first countersunk hole is provided with an internal thread;

[0022] One end of the compression spring is connected to the bottom wall of the first countersunk hole, and the other end is connected to the first push rod or the second push rod.

[0023] Preferably, the sliding valve assembly further comprises a housing;

[0024] The housing is provided with the proportional electromagnet assembly;

[0025] One end of the shell is provided with a hexagonal hole, one end of the inner sleeve is provided with a hexagonal head, the hexagonal head is matched with the hexagonal hole, and the other end of the shell is fixedly connected to the pole shoe.

[0026] Preferably, one end of the screw plug is provided with a second countersunk hole, and the other end is provided with a mounting hole, and the sliding valve assembly further includes a second elastic member;

[0027] The outer wall of the second countersunk hole is threadedly connected to the inner bushing or the pole shoe;

[0028] One end of the second elastic member abuts against the bottom wall of the second countersunk hole, and the other end abuts against the inner bushing or the pole shoe.

[0029] Based on the above technical solutions, the technical effects achieved by the present invention are analyzed as follows:

[0030] and a valve core, the valve core being provided with a working oil port, the valve core being provided with an oil inlet and an oil outlet, and being sleeved with the valve core, slidingly cooperating with the valve core to realize conduction or closure between the oil inlet, the oil outlet or the working oil port; the proportional electromagnet assembly comprising a screw plug, a pole shoe, an armature and an inner sleeve, the inner sleeve being sleeved with the armature, the first end of the pole shoe being inserted in the inner sleeve, the pole shoe and the armature being spaced apart along the axial direction of the inner sleeve, and the proportional electromagnet assembly comprising a first state and a second state; the first state is that the screw plug is inserted into the second end of the pole shoe, and the end of the valve sleeve away from the working oil port is inserted into the end of the inner sleeve away from the pole shoe, and the second state is that the screw plug is inserted into the end of the inner sleeve away from the pole shoe, and the end of the valve sleeve away from the working oil port is inserted into the second end of the pole shoe; the armature is connected to the valve core to drive the valve core to slide.

[0031] The operating principle of the switchable positive and negative proportional pressure reducing valve provided by the present invention is as follows: when the proportional solenoid assembly operates in the negative proportional function, the proportional solenoid assembly is in a first state, namely, the screw plug is installed on the pole piece and the slide valve assembly is installed on the inner sleeve. When the proportional solenoid is de-energized, the valve core is in an open state, the oil inlet is connected to the working oil port, and the oil return port is closed. At this time, the working oil port pressure is maximum and equal to the pressure at the oil inlet. When the proportional solenoid is energized, the valve core moves under the action of the electromagnetic force, connecting the working oil port and the oil return port, and the oil inlet is closed. At this time, the working oil port pressure is partially discharged at the oil return port, reducing the pressure at the working oil port. When the pressure at the working oil port drops to a certain level, the valve core moves, shutting off the working oil port, the oil return port, and the oil inlet. As the input current continues to increase, the pressure discharged in the working chamber continues to increase, and the output pressure continues to decrease, thereby achieving the negative proportional function of the proportional pressure reducing valve.

[0032] When the proportional solenoid assembly operates in direct proportional mode, it is in its second state, with the plug installed on the inner sleeve and the spool assembly installed on the pole piece. When the proportional solenoid is de-energized, the valve core is fully closed, the return oil port communicates with the working oil port, and the oil inlet is closed. At this point, the working chamber pressure is minimal, equal to the return oil port pressure. When the proportional solenoid is energized, the valve core moves, connecting the working oil port with the oil inlet, while the return oil port is closed. At this point, the working oil port pressure increases due to the oil inlet, causing the pressure at the working oil port to increase. When the working oil port pressure reaches a certain level, the valve core moves, isolating the working oil port, the return oil port, and the oil inlet from each other. As the input current continues to increase, the working chamber pressure and the output pressure continue to increase, thus achieving the direct proportional function of the proportional pressure reducing valve.

[0033] The solenoid proportional pressure reducing valve can switch between the positive and negative proportional functions by exchanging the relative positions of the slide valve assembly and the screw plug, greatly expanding the application range of the proportional pressure reducing valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 An assembly diagram of a pressure reducing valve in a first state with switchable positive and negative proportions provided by an embodiment of the present invention;

[0036] Figure 2 This is an assembly diagram of the second state of the pressure reducing valve with switchable positive and negative proportions provided by an embodiment of the present invention.

[0037] icon:

[0038] 1-screw plug; 2-small stiffness spring; 3-pole shoe; 4-terminal; 5-injection molded connector; 6-coil; 7-magnetic ring; 8-inner sleeve; 9-large stiffness spring; 10-housing; 11-second push rod; 12-limiting plate; 13-armature; 14-first push rod; 15-small screw plug; 16-compression spring; 17-steel ball; 18-valve core; 19-first sealing ring; 20-second sealing ring; 21-third sealing ring; 22-skeleton; 23-valve sleeve; 24-connecting rod; T-oil return port; P-oil inlet port; A-working oil port. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0041] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0042] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0043] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0044] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0045] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0046] Most proportional pressure reducing valves on the market have only one function: direct proportional or inverse proportional. However, in actual use, different functions are required according to different working conditions, and a single function is far from sufficient to meet the requirements.

[0047] In view of this, the embodiment of the present invention provides a switchable positive and negative proportional pressure reducing valve, which includes a sliding valve assembly and a proportional electromagnet assembly; the sliding valve assembly includes a valve sleeve 23 and a valve core 18, the valve core 18 is provided with a working oil port A, the valve sleeve 23 is provided with an oil inlet P and an oil outlet, and is sleeved with the valve core 18, and slides with the valve core 18 to achieve conduction or closure between the oil inlet P, the oil outlet or the working oil port A; the proportional electromagnet assembly includes a screw plug 1, a pole shoe 3, an armature 13 and an inner sleeve 8, the inner sleeve 8 is sleeved with the armature 13, and the first end of the pole shoe 3 is sleeved with the armature 13. Inserted in the inner sleeve 8, the pole shoe 3 and the armature 13 are spaced apart along the axial direction of the inner sleeve 8, and the proportional solenoid assembly includes a first state and a second state; the first state is that the screw plug 1 is inserted into the second end of the pole shoe 3, and the end of the valve sleeve 23 away from the working oil port A is inserted into the end of the inner sleeve 8 away from the pole shoe 3; the second state is that the screw plug 1 is inserted into the end of the inner sleeve 8 away from the pole shoe 3, and the end of the valve sleeve 23 away from the working oil port A is inserted into the second end of the pole shoe 3; the armature 13 is connected to the valve core 18 to drive the valve core 18 to slide.

[0048] The operating principle of the switchable positive and negative proportional pressure reducing valve provided by the present invention is as follows: When the proportional solenoid assembly operates in the negative proportional function, the proportional solenoid assembly is in the first state, namely, the screw plug 1 is mounted on the pole piece 3, and the slide valve assembly is mounted on the inner sleeve 8. When the proportional solenoid is de-energized, the valve core 18 is in the open state, the oil inlet P is connected to the working oil port A, and the oil return port T is closed. At this time, the pressure in the working oil port A is maximum and equal to the pressure at the oil inlet P. When the proportional solenoid is energized, the valve core 18 moves under the action of the electromagnetic force, connecting the working oil port A with the oil return port T, and the oil inlet P is closed. At this time, the pressure in the working oil port A is partially discharged at the oil return port T, reducing the pressure at the working oil port A. When the pressure at the working oil port A drops to a certain level, the valve core 18 moves, shutting off the working oil port A, the oil return port T, and the oil inlet P. As the input current increases, the pressure discharged from the working chamber increases, and the output pressure decreases, thereby achieving the negative proportional function of the proportional pressure reducing valve.

[0049] When the proportional solenoid assembly operates in direct proportional mode, it is in its second state, with the plug 1 mounted on the inner sleeve 8 and the spool assembly mounted on the pole piece 3. When the proportional solenoid is de-energized, the valve core 18 is fully closed, the return port T communicates with the working port A, and the oil inlet P is closed. At this point, the working chamber pressure is minimal, equal to the pressure at the return port T. When the proportional solenoid is energized, the valve core 18 moves, connecting the working port A to the oil inlet P, while the return port T is closed. At this point, the pressure at the working port A increases slightly under the influence of the oil inlet P, causing the pressure at the working port A to increase. When the pressure at the working port A reaches a certain level, the valve core 18 moves, disconnecting the working port A, the return port T, and the oil inlet P. As the input current continues to increase, the working chamber pressure and the output pressure continue to increase, thus achieving the direct proportional function of the proportional pressure reducing valve.

[0050] The solenoid proportional pressure reducing valve can realize the switching of the positive and negative proportional functions of the proportional pressure reducing valve by exchanging the relative positions of the slide valve assembly and the screw plug 1, which greatly expands the application range of the proportional pressure reducing valve.

[0051] The following is a detailed description of the structure and shape of the pressure reducing valve that can switch between positive and negative proportions:

[0052] In the optional solutions of the embodiments of the present invention, please refer to Figure 1 and Figure 2 The sliding valve assembly includes a valve sleeve 23, a valve core 18, a small screw plug 15, a compression spring 16, a steel ball 17, a connecting rod 24, a first sealing ring 19, a second sealing ring 20, and a third sealing ring 21. The proportional solenoid assembly includes a screw plug 1, a low-rigidity spring 2, a pole piece 3, a terminal 4, an injection-molded connector 5, a coil 6, a magnetic ring 7, an inner sleeve 8, a high-rigidity spring 9, a housing 10, a second push rod 11, a stopper 12, an armature 13, a first push rod 14, and a frame 22. The valve sleeve 23 is threadedly connected to the inner sleeve 8 or pole piece 3 of the proportional solenoid assembly, and the valve core 18 is connected to the second push rod 11 or the first push rod 14 of the proportional solenoid assembly via a connecting rod 24.

[0053] The structure and shape of the slide valve assembly are described in detail below:

[0054] In an optional embodiment of the present invention, the valve sleeve 23 is a hollow structure with a first through-hole. Four circumferentially distributed oil inlet ports P and oil return ports T are defined on the outer surface of the valve sleeve 23. The end face of the valve sleeve 23 facing away from the working oil port A is externally threaded for connection with the threaded holes of the inner bushing 8 or the pole piece 3. A protrusion is provided on the outer wall of the valve sleeve 23. The end face of the valve sleeve 23 facing away from the working oil port A is provided with a first through-hole connecting to the oil return port T. The first, second, and third sealing rings 19, 20, and 21 are all mounted on the outer surface of the valve sleeve 23. A rectangular groove is defined on the inner wall of the first through-hole for connecting the oil circuit.

[0055] In an optional scheme of the embodiment of the present invention, the valve core 18 is installed in the first through hole of the valve sleeve 23; a blind hole is opened on one end face of the valve core 18 to form a working oil port A; three groups of oil holes are opened on the side wall of the blind hole; each group of holes is distributed on two circles; a hexagonal hole is opened on the end face of the valve core 18 close to the blind hole; a threaded hole is opened on the end face of the valve core 18 away from the working oil port A; and two groups of throttling grooves are opened on the outer surface of the valve core 18.

[0056] In an optional solution of the embodiment of the present invention, the surface of the small screw plug 15 is provided with an external thread; the external thread is connected to the internal thread of the connecting rod 24 for fixing the compression spring 16; one end surface of the small screw plug 15 is provided with a hexagonal hole for easy installation and disassembly.

[0057] In an optional scheme of an embodiment of the present invention, an external thread is provided on one end face of the connecting rod 24; the external thread is connected to the threaded hole of the valve core 18; the other end face is provided with a first countersunk hole; a threaded hole is provided on the side wall of the connecting rod 24 close to the first countersunk hole; the threaded hole is used to install the steel ball 17, the compression spring 16 and the small screw plug 15; the steel ball 17 and the spherical groove of the second push rod 11 or the first push rod 14 are tightly fitted under the action of the compression spring 16.

[0058] The following is a detailed description of the structure and shape of the proportional solenoid assembly:

[0059] One end of the plug 1 is provided with a second countersunk hole and a countersunk groove. A hexagonal socket is provided on the end of the plug 1 facing away from the second countersunk hole and the countersunk groove. The second countersunk hole is used to mount the high-rigidity spring 9, while the countersunk groove is used to mount the low-rigidity spring 2. External threads are provided on the sidewall of the plug 1 near the countersunk groove. These threads connect to threaded holes in the inner bushing 8 or the pole piece 3. A mounting hole is provided on the end of the plug 1 facing away from the second countersunk hole to facilitate installation and removal of the plug 1.

[0060] The two ends of the small stiffness spring 2 are ground flat. When the proportional electromagnet is in the second state, it is installed between the second push rod 11 and the valve sleeve 23 to reset the valve core 18; when the proportional electromagnet is in the first state, it is installed in the recessed groove of the screw plug 1.

[0061] A threaded hole is formed on one end face of the pole shoe 3 to connect with the screw plug 1 or the valve sleeve 23. A third countersunk hole and a second through hole are formed on the end face of the pole shoe 3 away from the threaded hole. The pole shoe 3 is made of soft magnetic material.

[0062] The terminal 4 is used to connect the coil 6 and an external power supply.

[0063] The injection-molded plug 5 is used to encapsulate the coil 6 , the frame 22 , the magnetic ring 7 and the terminal 4 ; a standard socket is integrated on the surface of the injection-molded plug 5 .

[0064] The coil 6 is wound with enameled wire and installed in the annular groove of the frame 22 .

[0065] A fourth through hole is defined inside the magnetic conductive ring 7 , and the inner sleeve 8 is installed in the fourth through hole. The magnetic conductive ring 7 is made of a soft magnetic material.

[0066] Both ends of the high-rigidity spring 9 are ground flat and installed in the second countersunk hole of the screw plug 1; the high-rigidity spring 9 is used to balance the electromagnetic force and the feedback pressure of the working oil port A when the proportional pressure reducing valve works in the inverse proportional function.

[0067] One end face of the housing 10 has a hexagonal hole. This hole mates with the hexagonal head of the inner bushing 8 to prevent relative rotation between the two. The end face of the housing 10 facing away from the hole is welded to the pole piece 3. The interior of the housing 10 is hollow and is used to house the internal components of the proportional electromagnet. The housing 10 is made of a soft magnetic material.

[0068] The second push rod 11 is a stepped shaft structure and is installed inside the pole shoe 3; a boss is provided on one end surface of the second push rod 11; and a spherical groove is provided near the boss surface of the second push rod 11.

[0069] A third through hole is formed inside the limiting plate 12 to provide interference fit with the stepped shaft of the second push rod 11. The limiting plate 12 is made of non-magnetic material.

[0070] The armature 13 has two blind holes on its two end faces, a shoulder on one end face, and a recessed groove on the end face away from the shoulder. The armature 13 is made of soft magnetic material.

[0071] The first push rod 14 is a stepped shaft structure; the smaller diameter shaft of the first push rod 14 is interference-connected with the armature 13; and a spherical groove is formed on the surface of the larger diameter shaft of the first push rod 14.

[0072] An annular groove is provided on the surface of the skeleton 22 ; a fifth through hole is provided inside the skeleton 22 , and the inner bushing 8 is installed in the fifth through hole.

[0073] The working principle of the proportional pressure reducing valve is:

[0074] When the proportional solenoid works as Figure 1 In the inverse proportional function shown, the screw plug 1 is installed on the pole shoe 3, the sliding valve assembly is installed on the inner sleeve 8, the small stiffness spring 2 is installed in the sink groove of the screw plug 1, and the large stiffness spring 9 is installed in the second sink hole of the screw plug 1.

[0075] When the proportional solenoid is de-energized, the valve core 18 is fully open due to the action of the high-rigidity spring 9. At this point, the oil inlet P is connected to the working oil port A, and the oil return port T is closed. The pressure at the working oil port A is maximum, equal to the pressure at the oil inlet P. Simultaneously, the pressure at the working oil port A is directed through the leftmost oil port of the valve core 18 into the annular cavity formed by the valve core 18 and the valve sleeve 23, reducing the effective pressure area at the working oil port A.

[0076] When the proportional solenoid is energized, the armature 13 drives the valve core 18 to move to the left under the action of the electromagnetic force. After the valve core 18 moves a certain distance, the working oil port A is connected to the return oil port T, and the oil inlet P is in a closed state. At this time, the pressure at the working oil port A will be partially unloaded at the return oil port T, reducing the pressure at the working oil port A. At the same time, the pressure at the working oil port A is introduced into the annular cavity formed by the valve core 18 and the valve sleeve 23 through the leftmost oil port of the valve core 18, reducing the equivalent effective area of ​​the pressure at the working oil port A. When the pressure at the working oil port A drops to a certain level, the valve core 18 moves to the right, and the spring force of the high-rigidity spring 9, the electromagnetic force, and the feedback liquid pressure of the working oil port A are balanced again at the new position. The working oil port A, the return oil port T, and the oil inlet P are all cut off from each other. At this time, the force balance equation of the valve core 18 is:

[0077] F b =F e +p A (S A -S B )

[0078] Where, F b is the spring force of the high-rigidity spring 9; F e is the electromagnetic force generated by the proportional solenoid; p A is the pressure at the working oil port A; S A is the right side end surface area of ​​the valve core 18; S B It is the end surface area of ​​the annular cavity on the left side of the valve core 18.

[0079] The electromagnetic force F generated by the proportional solenoid e The approximate relationship with the input current i is:

[0080] F e =k*i

[0081] Where, k is the proportional coefficient of the proportional electromagnet, which is a positive value; i is the input current of the proportional electromagnet.

[0082] Spring force F of high-rigidity spring 9 b for:

[0083] F b =k b *Δx1

[0084] Where k b is the spring stiffness of the high-stiffness spring 9; Δx1 is the compression amount of the high-stiffness spring 9.

[0085] Therefore, the pressure at the working oil port A is:

[0086]

[0087] Since the structure of the valve core 18 is determined, the right end surface area S of the valve core 18 is A The end surface area S of the annular cavity on the left side of the valve core 18 B is a constant value. Since the compression amount Δx1 of the high-rigidity spring 9 changes very little, the spring force of the high-rigidity spring 9 can be approximated to a constant value. Therefore, as the proportional electromagnet input current i continues to increase, the pressure p at the working oil port A A Continuously decreasing, thus achieving the inverse proportional function.

[0088] When the proportional solenoid works as Figure 2 In the illustrated proportional function, plug 1 is mounted on inner sleeve 8, the spool assembly is mounted on pole piece 3, a low-rigidity spring 2 is installed between valve sleeve 23 and second push rod 11, and a high-rigidity spring 9 is installed in the second countersunk hole of plug 1. When the proportional solenoid is de-energized, valve core 18 is closed by low-rigidity spring 2. At this point, the return oil port T is connected to the working oil port A, and the oil inlet P is closed. The pressure at working oil port A is minimal, equal to the pressure at return oil port T. Simultaneously, the pressure at working oil port A is diverted through the leftmost oil port of valve core 18 into the annular cavity formed by valve core 18 and valve sleeve 23, reducing the effective pressure area at working oil port A.

[0089] When the proportional solenoid is energized, the armature 13 drives the valve core 18 to move to the right under the action of the electromagnetic force. After the valve core 18 moves a certain distance, the working oil port A is connected to the oil inlet P, and the return oil port T is in a closed state. At this time, the pressure at the working oil port A will increase due to the action of the oil inlet P, causing the pressure at the working oil port A to increase. At the same time, the pressure at the working oil port A is introduced into the annular cavity formed by the valve core 18 and the valve sleeve 23 through the leftmost oil port of the valve core 18, reducing the equivalent effective area of ​​the pressure at the working oil port A. When the pressure at the working oil port A increases to a certain level, the valve core 18 moves to the left, and the spring force of the small stiffness spring 2, the electromagnetic force, and the feedback liquid pressure of the working oil port A are balanced again at the new position. The working oil port A, the return oil port T, and the oil inlet P are all in a cut-off state. At this time, the force balance equation of the valve core 18 (18) is:

[0090] F e =F s +p A (S A -S B )

[0091] Where, F s is the spring force of the small stiffness spring 2; F e is the electromagnetic force generated by the proportional solenoid; p A is the pressure at the working oil port A; S A is the right side end surface area of ​​the valve core 18; S B It is the end surface area of ​​the annular cavity on the left side of the valve core 18.

[0092] The electromagnetic force F generated by the proportional solenoid e The approximate relationship with the input current i is:

[0093] F e =k*i

[0094] Where, k is the proportional coefficient of the proportional electromagnet, which is a positive value; i is the input current of the proportional electromagnet.

[0095] Spring force F of low-stiffness spring 2 s for:

[0096] F s =k s *Δx2

[0097] Where k s is the spring stiffness of the small stiffness spring 2; Δx2 is the compression of the small stiffness spring 2.

[0098] Therefore, the pressure at the working oil port A is:

[0099]

[0100] Since the structure of the valve core 18 is determined, the right end surface area S of the valve core 18 is A The end surface area S of the annular cavity on the left side of the valve core 18 (18) B is a constant value. Since the compression amount Δx2 of the small stiffness spring 2 changes very little, the spring force of the small stiffness spring 2 can be approximated as a constant value. Therefore, as the proportional solenoid input current i continues to increase, the pressure p at the working oil port A A Continuously increasing, thus achieving the function of direct proportion.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pressure reducing valve capable of switching between positive and negative proportions, characterized in that: include: Spool valve assembly and proportional solenoid assembly; The sliding valve assembly comprises a valve sleeve (23) and a valve core (18), wherein the valve core (18) is provided with a working oil port (A), and the valve sleeve (23) is provided with an oil inlet (P) and an oil outlet, and is sleeved with the valve core (18) and slidably cooperates with the valve core (18) to realize conduction or closing between the oil inlet (P), the oil outlet or the working oil port (A); The proportional electromagnet assembly comprises a screw plug (1), a pole shoe (3), an armature (13) and an inner bushing (8), wherein the inner bushing (8) is sleeved with the armature (13), the first end of the pole shoe (3) is inserted into the inner bushing (8), the pole shoe (3) and the armature (13) are spaced apart along the axial direction of the inner bushing (8), and the proportional electromagnet assembly comprises a first state and a second state; The first state is that the screw plug (1) is inserted into the second end of the pole shoe (3), and the end of the valve sleeve (23) facing away from the working oil port (A) is inserted into the end of the inner sleeve (8) away from the pole shoe (3); the second state is that the screw plug (1) is inserted into the end of the inner sleeve (8) away from the pole shoe (3), and the end of the valve sleeve (23) facing away from the working oil port (A) is inserted into the second end of the pole shoe (3); The armature (13) is connected to the valve core (18) to drive the valve core (18) to slide; The proportional electromagnet assembly further comprises a first push rod (14) and a second push rod (11), wherein the first push rod (14) and the second push rod (11) are respectively mounted on both sides of the armature (13); One end of the second push rod (11) facing away from the armature (13) is inserted into the pole shoe (3) to abut against the screw plug (1) or the valve core (18); and one end of the first push rod (14) facing away from the armature (13) correspondingly abuts against the valve core (18) or the screw plug (1); When the proportional electromagnet is in the first state, the small stiffness spring (2) is installed in the sink groove of the screw plug (1), and the large stiffness spring (9) is installed in the second sink hole of the screw plug (1) to balance the electromagnetic force and the feedback pressure of the working oil port (A); When the proportional electromagnet is in the second state, the large stiffness spring (9) is installed in the second countersunk hole of the screw plug (1), and the small stiffness spring (2) is installed between the second push rod (11) and the valve sleeve (23) for resetting the valve core (18).

2. The pressure reducing valve capable of switching between positive and negative proportions according to claim 1, characterized in that: The proportional electromagnet assembly further comprises a limiting plate (12), wherein the limiting plate (12) is located between the armature (13) and the pole shoe (3).

3. The switchable positive and negative proportional pressure reducing valve according to claim 2, characterized in that: The inner sleeve (8) is provided with a first through hole, and the pole shoe (3) is provided in the first through hole; A rectangular groove is provided on the inner wall of the first through hole, and the rectangular groove is arranged along the axis direction of the first through hole.

4. The switchable positive and negative proportional pressure reducing valve according to claim 3, characterized in that: The outer wall of the valve sleeve (23) is provided with a protrusion, and the protrusion extends along the circumference of the valve sleeve (23).

5. The switchable positive and negative proportional pressure reducing valve according to claim 4, characterized in that: One end of the valve core (18) is provided with a blind hole to form the working oil port (A); The side wall of the blind hole is provided with a plurality of groups of oil holes, and the plurality of groups of oil holes are arranged at intervals along the axial direction of the blind hole.

6. The pressure reducing valve capable of switching between positive and negative proportions according to claim 5, characterized in that: The outer wall of the valve core (18) is provided with a plurality of groups of throttling grooves, and the plurality of groups of throttling grooves are arranged at intervals along the axial direction of the blind hole.

7. The switchable positive and negative proportional pressure reducing valve according to claim 6, characterized in that: The slide valve assembly further includes a compression spring (16) and a connecting rod (24); One end of the connecting rod (24) is threadedly connected to the valve core (18), and the other end is provided with a first countersunk hole, and the inner wall of the first countersunk hole is provided with an internal thread; One end of the compression spring (16) is connected to the bottom wall of the first countersunk hole, and the other end is connected to the first push rod (14) or the second push rod (11).

8. The pressure reducing valve capable of switching between positive and negative proportions according to claim 7, characterized in that: The sliding valve assembly further includes a housing (10); The housing (10) is sleeved with the proportional electromagnet assembly; One end of the outer shell (10) is provided with a hexagonal hole, one end of the inner sleeve (8) is provided with a hexagonal head, the hexagonal head cooperates with the hexagonal hole, and the other end of the outer shell (10) is fixedly connected to the pole shoe (3).

Images