CN115711310A

CN115711310A - Electromagnetic change valve

Info

Publication number: CN115711310A
Application number: CN202211045076.7A
Authority: CN
Inventors: 黄路路; 李瑞锋; 刘蕾; 胡启辉; 陆文程
Original assignee: Bosch Rexroth Changzhou Co Ltd
Current assignee: Bosch Rexroth Changzhou Co Ltd
Priority date: 2022-08-30
Filing date: 2022-08-30
Publication date: 2023-02-24

Abstract

An electromagnetic directional valve comprising: a valve body defining a valve chamber; a spool mounted in the valve chamber in an axially slidable manner; the electromagnets are arranged at two axial ends of the valve body, and each electromagnet comprises a sleeve fixed on the valve body and a push rod which penetrates through the sleeve and faces to the corresponding end face of the valve core in the axial direction; in each of both axial ends of the valve body, a first spring and a second spring are arranged, respectively, the first spring and the second spring being configured to: in a neutral position of the electromagnetic directional valve, the first spring is axially precompressed by the spool and the corresponding sleeve, and the first end of the second spring is fixed to one of the spool and the sleeve, and the second end of the second spring is spaced apart from the other of the spool and the sleeve by a free distance in the axial direction. The electromagnetic directional valve has improved spring damping characteristics.

Description

Electromagnetic change valve

Technical Field

The present application relates to a solenoid directional valve for a hydraulic system.

Background

A solenoid operated directional valve is often used in hydraulic systems to control the direction of fluid flow. The electromagnetic directional valve generally includes a valve body, a valve core, and an electromagnet at both ends. When the electromagnet is electrified, the valve core can be pushed to axially slide in the valve body, and connection and disconnection between the hydraulic ports of the electromagnetic directional valve are realized. And two ends of the valve core are respectively provided with a return spring for keeping the valve core at a middle position when the two electromagnets are not electrified and providing damping when one electromagnet is electrified.

The return spring at each end of the prior art reversing valve is typically a single spring. The damping characteristic provided by the design is single, and higher requirements are difficult to meet.

Disclosure of Invention

It is an object of the present application to provide a solenoid directional valve with improved spring damping characteristics.

To this end, the present application provides, in one aspect thereof, an electromagnetic directional valve including: a valve body defining a valve chamber; a spool mounted in the valve chamber in an axially slidable manner; the electromagnets are arranged at the two axial ends of the valve body, and each electromagnet comprises a sleeve fixed on the valve body and a push rod which penetrates through the sleeve and faces the corresponding end face of the valve core axially; in each of both axial ends of the valve body, a first spring and a second spring are arranged, respectively, the first spring and the second spring being configured to: in the neutral position of the electromagnetic directional valve, the first spring is axially pre-compressed by the valve core and the corresponding sleeve, the first end of the second spring is fixed on one of the valve core and the sleeve, and the second end of the second spring is separated from the other of the valve core and the sleeve by a free distance in the axial direction; in the valve position switching process of the reversing valve from the middle position, the stroke of the valve core comprises a first section of stroke and a second section of stroke, wherein the first section of stroke is an axial distance which is passed by the valve core from the start of pushing by the push rod to the initial conduction of the reversing valve when the valve core is axially moved in the valve position switching process, and the second section of stroke is an axial distance which is passed by the valve core from the initial conduction of the reversing valve to the end of valve position switching; during the first stroke, only the first spring provides a damping force to the valve spool; the first and second springs in combination provide a damping force to the spool during at least a portion of the second stroke.

In one embodiment, the free distance and the first stroke satisfy: n is more than or equal to 1.05m and less than or equal to 1.45m.

In one embodiment, the first stroke and the outer diameter of the valve core satisfy the following condition: m is more than or equal to 0.09D and less than or equal to 0.15D.

In one embodiment, the first spring is sandwiched between a retainer ring axially supported by the spool and the sleeve.

In one embodiment, the sleeve has a groove formed therein, the groove having first and second annular surfaces formed therein at different axial positions; the first spring is clamped between the spool and the first annulus; the first end of the second spring is fixed on the second annular surface, and in the neutral position of the electromagnetic directional valve, the second end of the second spring is separated from the valve core by the free distance; or the first end of the second spring is fixed to the valve core, and the second end of the second spring is separated from the second annular surface by the free distance in the neutral position of the electromagnetic directional valve.

In one embodiment, the sleeve has a groove formed therein, the groove having a common annulus formed therein; the first spring is clamped between the spool and the common annulus; the first end of the second spring is fixed on the common annular surface, and in the neutral position of the electromagnetic directional valve, the second end of the second spring is separated from the valve core by the free distance; or the first end of the second spring is fixed on the valve core, and the second end of the second spring is separated from the common annular surface by the free distance in the neutral position of the electromagnetic directional valve.

In one embodiment, a dimple is formed in the end of the valve spool; the first end of the second spring is fixed on the sleeve, and in the middle position of the electromagnetic reversing valve, the second end of the second spring is separated from the pit bottom of the pit by the free distance; or the first end of the second spring is fixed at the bottom of the pit, and the second end of the second spring is separated from the sleeve by the free distance in the middle position of the electromagnetic directional valve.

In one embodiment, the end of the spool forms a reduced diameter section defining a step surface; the first end of the second spring is fixed to the sleeve, and in the middle position of the electromagnetic reversing valve, the second end of the second spring is separated from the step surface by the free distance; or the first end of the second spring is fixed on the step surface, and the second end of the second spring is separated from the sleeve by the free distance in the middle position of the electromagnetic directional valve.

In one embodiment, the second spring has an outer diameter smaller than an inner diameter of the first spring, and at least a portion of the second spring is radially surrounded by the first spring.

In one embodiment, the spring rate of the second spring is less than the spring rate of the first spring.

The return spring of the electromagnetic directional valve comprises two springs, wherein only one spring acts in a first section of stroke of the valve position switching stroke, and the two springs act simultaneously in a subsequent second section of stroke of the valve position switching stroke. Thereby, a better spring damping characteristic can be provided. In the first section of the valve position switching stroke, the high moving speed of the valve core can be kept; in the subsequent second-stage stroke, high damping can be provided, and valve core impact and hydraulic impact are avoided.

Drawings

The foregoing and other aspects of the present application will be more fully understood and appreciated by reference to the following detailed description, taken with reference to the accompanying drawings, in which:

FIG. 1 is a partial schematic cross-sectional view of the internal structure of a three-position, four-way solenoid directional valve that may embody techniques of the present application;

FIG. 2 is a partial cross-sectional view of one control end of the solenoid directional valve of FIG. 1;

fig. 3-6 are partial cross-sectional views of other possible configurations of the control end of the solenoid directional valve of the present application.

Detailed Description

The present application relates generally to a solenoid directional valve, which is a three-position directional valve. The oil ports can be divided into three-way, four-way, five-way, six-way and the like according to the number of the oil ports. The valve core transposition can be realized by electromagnets at the control ends at two sides.

Fig. 1 is a three-position, four-way solenoid directional valve that can implement the techniques of the present application having three valve positions, a mid position, a first side valve position, and a second side valve position, and having four oil ports, an oil inlet, an oil return, and two working oil ports. In fig. 1, the directional valve is in the neutral position.

The reversing valve comprises: a valve body 1 defining an axially extending valve chamber; a spool 2 installed in the valve chamber and axially movable to effect switching of valve positions; the electromagnets arranged on the two axial sides of the valve body 1 respectively form the control end of the reversing valve and are used for pushing the valve core 2 to move axially.

Each electromagnet has a sleeve (stopper) 3 fixedly mounted at a respective axial end of the valve body 1, and a push rod 4 extending axially through the sleeve 3. The electromagnet also includes an electromagnetic coil, an armature, and the like, which are not shown. When the solenoid is de-energized, the push rod 4 remains in place a small axial distance from the valve spool 2. When the electromagnetic coil is electrified, the armature is attracted, the push rod 4 is pushed to move towards the valve core 2, and the valve core 2 is pushed axially.

A valve cavity in the form of an undercut groove is formed in the inner wall of the valve chamber of the valve body 1 and is respectively a P cavity, an A cavity, a B cavity and two T cavities. The cavity P is communicated with an oil inlet of the reversing valve, the cavity A and the cavity B are respectively communicated with the two working oil ports, and the two cavity T are communicated with each other and the oil return port.

An annular boss 2a is formed on the valve core 2, and the two bosses 2a are axially separated and define an annular oil inlet groove 2b therebetween. The outer diameter of each boss 2a is D (i.e., the outer diameter of the spool 2). The two bosses 2a are slidably fitted with the inner wall of the valve chamber of the valve body 1.

A land 2d is formed on each end portion 2c of the spool 2. Each shoulder 2d is located axially outwardly of the adjacent boss 2 a. Between each land 2d and the adjacent boss 2a, an oil return groove 2e is formed, respectively.

Each shoulder 2d axially supports a collar 5. The position of each retainer ring 5 on the axially inner side is restricted by an end step formed at the valve chamber end of the valve body 1. A first spring 6 is arranged axially between each sleeve 3 and the respective collar 5. The first springs 6 surround, on the one hand, the respective ends 2c and, on the other hand, are inserted inside the respective sleeves 3.

Furthermore, a second spring 7 is arranged in each sleeve 3, which second spring 7 at least partially surrounds the respective push rod 4. The second spring 7 is fixed at its outer end to the sleeve 3 and at its inner end to the adjacent end face 2f of the spool 2. The outer diameter of the second spring 7 is smaller than the inner diameter of the first spring 6. At least a part of the second spring 7 is surrounded by the first spring 6 in the radial direction. The spring rate of the second spring 7 is smaller than that of the first spring 6.

Herein, "inner" refers to an orientation toward the axial center of the spool 2, and "outer" refers to an orientation away from the axial center of the spool 2.

In the middle position of the reversing valve shown in fig. 1, the oil inlet groove 2B faces the cavity P in the radial direction, the two bosses 2a respectively block the cavity a and the cavity B, and each oil return groove 2e faces a corresponding cavity T.

Other configurations of diverter valves are well known in the art and will not be described herein.

Further, in the neutral position of the reversing valve, the first spring 6 is axially pre-compressed by the respective sleeve 3 and the collar 5, and the inner end of the second spring 7 is spaced from the adjacent end face 2f of the spool 2 by an axial free distance n, i.e. the second spring 7 is not axially compressed.

When the electromagnet on any side is electrified, the push rod 4 on the side moves axially towards the other side to contact the end face 2f on the side of the valve core 2, and then the valve core 2 is pushed axially towards the other side until the valve position is switched from the middle position to the valve position on the other side. In the valve position switching process, the stroke of the valve core 2 comprises a first stroke m and a second stroke. The first section of stroke m is the axial distance that the valve core 2 starts to axially move to the direction valve to initially conduct the valve core 2 in the valve position switching process, and the first section of stroke m is limited by the shortest axial distance between the oil inlet groove 2B and the cavity A or the cavity B. The second section of stroke is an axial distance from the initial conduction of the reversing valve in the valve position switching process to the end of the valve position switching of the valve core 2.

After the valve core 2 passes through the first stroke m, the oil inlet groove 2B is initially communicated with the oil cavity (the cavity A or the cavity B) on the other side of the cavity P. After the second stroke, the valve element 2 reaches a position where the maximum flow area is achieved between the oil groove 2B and the oil chamber (a chamber or B chamber) on the other side of the P chamber. After the valve position switching is completed from the middle position, one of the cavity A and the cavity B is communicated with the cavity P, and the other of the cavity A and the cavity B is communicated with the cavity T.

In the first stroke m, only the corresponding first spring 6 is axially compressed by the spool 2 (i.e. further compressed on pre-compression), while the second spring 7 is not axially compressed by the spool 2. In the second stroke, both the first spring 6 and the second spring 7 are compressed axially by the spool 2.

According to a further aspect of the present application, the free distance n of the second spring 7 may be set to satisfy the following condition:

n is more than or equal to 1.05m and less than or equal to 1.45m. For example, n =1.18m.

This condition ensures the above-described compression of the first spring 6 and the second spring 7 during the first and second stroke phases. At the same time, it is ensured that the second spring 7 is also compressed in the second stroke phase, so that the second spring 7 is compressed sufficiently for the second spring 7 to exert a damping action.

Further, the first stroke m of the present application may be set to satisfy the following condition:

m is more than or equal to 0.09D and less than or equal to 0.15D. For example, m =0.12D.

This condition ensures that the total stroke of the valve spool 2 during valve position switching is limited to a certain limit and the size of the electromagnet is not unnecessarily large.

An enlarged view of the reversing valve of figure 1 at either control end is shown in figure 2. As shown in fig. 2, a groove is formed in the inner end of the sleeve 3, in which a first ring surface 3a and a second ring surface 3b facing inwards are created between the different diameter portions. The first annular surface 3a is located axially inward of the second annular surface 3b. The diameter (pitch diameter) of the first annulus 3a is greater than the diameter (pitch diameter) of the second annulus 3b. The first spring 6 is axially clamped between the retainer ring 5 and the first annulus 3 a. The outer end of the second spring 7 is fixed adjacent to the second ring surface 3b, and the inner end of the second spring 7 faces the end surface 2f of the spool 2 in the axial direction and is axially spaced from the end surface 2f by a free distance n.

The arrangement of the two springs is not necessarily limited to that shown in fig. 1 and 2, but may be replaced with other various possible structures.

For example, in one modification, as shown in the enlarged view at either control end of the diverter valve in figure 3, a recess is formed in the inner end of the sleeve 3 in which an inwardly facing common annulus 3c is formed. The first spring 6 is axially clamped between the collar 5 and the common annular face 3c. The outer end of the second spring 7 is fixed adjacent the common ring surface 3c. In the valve neutral position, the inner end of the second spring 7 faces the end face 2f of the valve slide 2 in the axial direction and is axially spaced from the end face 2f by a free distance n.

In another modification, as shown in the enlarged view at either control end of the diverter valve in figure 4, a groove is formed in the inner end of the sleeve 3 in which an inwardly facing common annulus 3c is formed. The first spring 6 is axially clamped between the collar 5 and the common annular surface 3c. Further, a recess 2g facing axially outward is formed in the end portion 2c of the valve element 2. The outer end of the second spring 7 is fixed abutting the common annular face 3c and the inner end of the second spring 7 is inserted into the recess 2g. In the valve neutral position, the inner end of the second spring 7 faces the bottom of the recess 2g in the axial direction and is axially spaced from the bottom by a free distance n.

As an alternative to the variant shown in fig. 4 (not shown), it is also possible to fix the inner end of the second spring 7 abutting the bottom of the recess 2g, the outer end facing axially the common annular surface 3c and being axially spaced from the common annular surface 3c by the free distance n.

It will be appreciated that in the variant shown in figure 4 and in its alternative, the common annulus 3c may also be replaced by the first and

second annuli

3a, 3b shown in figure 2.

In another modification, as shown in the enlarged view at either control end of the diverter valve in figure 5, a groove is formed in the inner end of the sleeve 3 in which an inwardly facing common annulus 3c is formed. The first spring 6 is axially clamped between the collar 5 and the common annular surface 3c. Further, the end portion 2c of the spool 2 is formed into a reduced diameter section to produce a step surface 2h facing axially outward. The inner end of the second spring 7 surrounds the reduced diameter section, and the inner end face of the second spring 7 is fixed adjacent to the step face 2h. In the valve neutral position, the outer end of the second spring 7 faces the common annular surface 3c in the axial direction and is axially spaced from the common annular surface 3c by a free distance n.

In the modification shown in fig. 5, the common annular surface 3c may also be replaced with the first annular surface 3a and the second annular surface 3b shown in fig. 2.

In another modification, as shown in the enlarged view at either control end of the diverter valve in figure 6, a groove is formed in the inner end of the sleeve 3 in which an inwardly facing common annulus 3c is formed. The first spring 6 is axially clamped between the collar 5 and the common annular surface 3c. Further, the end portion 2c of the spool 2 is formed with a reduced diameter section to produce a step surface 2h facing axially outward. The outer end of the second spring 7 is fixed adjacent the common ring surface 3c. In the valve neutral position, the inner end of the second spring 7 faces the step surface 2h in the axial direction and is axially spaced from the step surface 2h by a free distance n.

In the variant shown in fig. 6, the common annular face 3c may also be replaced by the first annular face 3a and the second annular face 3b shown in fig. 2.

The fixing of the inner or outer end of the second spring 7 on the spool 2 or the sleeve 3 can be achieved by form-fitting, using additional fasteners or fastening structures, etc. This is readily accomplished by those skilled in the art.

Other modifications to the control end of the diverter valve may be made by those skilled in the art, given the benefit of this disclosure.

It should be noted that both control ends of the reversing valve of the present application may employ the dual spring arrangement described above. However, the dual spring configuration described above may be used on only one control end of the directional valve, on the other control end of the directional valve, or in a configuration that includes another number of springs, as desired.

It should be noted that the principles of the present application are equally applicable to three-position directional valves having other valve cartridge configurations.

The reset spring of the electromagnetic directional valve comprises two springs, wherein in the neutral position of the electromagnetic directional valve, the first spring is axially pre-compressed by the valve core and the sleeve, the first end of the second spring is fixed on one of the valve core and the sleeve, and the second end of the second spring is separated from the other of the valve core and the sleeve by an axial free distance. In this way, only one spring is active during a first portion of the valve position switching stroke, and both springs are active simultaneously during a second, subsequent portion of the valve position switching stroke. Thereby, a better spring damping characteristic can be provided. In the first section of the valve position switching stroke, the high moving speed of the valve core can be kept; in the subsequent second stroke, high damping can be provided, and valve core impact and hydraulic impact are avoided.

Although the present application has been described herein with reference to specific exemplary embodiments, the scope of the present application is not intended to be limited to the details shown. Various modifications may be made to these details without departing from the underlying principles of the application.

Claims

1. A solenoid directional valve comprising:

a valve body (1) defining a valve chamber;

a spool (2) axially slidably mounted in the valve chamber;

the electromagnets are arranged at two axial ends of the valve body, each electromagnet comprises a sleeve (3) fixed on the valve body and a push rod (4) which penetrates through the sleeve and axially faces the corresponding end face (2 f) of the valve core;

wherein in each of the two axial ends of the valve body there is arranged a first spring (6) and a second spring (7), respectively, said first and second springs being arranged to: in a neutral position of the electromagnetic directional valve, the first spring is axially precompressed by the spool and the corresponding sleeve, the first end of the second spring is fixed to one of the spool and the sleeve, and the second end of the second spring is separated from the other of the spool and the sleeve by a free distance (n) in the axial direction;

in the valve position switching process of the reversing valve from the middle position, the stroke of the valve core comprises a first section of stroke (m) and a second section of stroke, wherein the first section of stroke is an axial distance which is passed by the valve core from the valve core which starts to be pushed by the push rod and moves axially to the initial conduction of the reversing valve in the valve position switching process, and the second section of stroke is an axial distance which is passed by the valve core from the initial conduction of the reversing valve to the end of the valve position switching; during the first stroke, only the first spring provides a damping force to the valve spool; the first and second springs in combination provide a damping force to the spool during at least a portion of the second stroke.

2. An electromagnetic directional valve as claimed in claim 1, wherein between the free distance (n) and the first stroke (m) there is satisfied:

1.05m≤n≤1.45m。

3. the electromagnetic directional valve as set forth in claim 2, wherein between the first stroke (m) and the outer diameter (D) of the spool:

0.09D≤m≤0.15D。

4. the electromagnetic directional valve according to any of claims 1-3, wherein the first spring is clamped between a retainer ring (5) axially supported by the spool and the sleeve.

5. The electromagnetic directional valve according to any of claims 1-4, wherein the sleeve has a groove formed therein, the groove having a first annular surface (3 a) and a second annular surface (3 b) formed therein at different axial positions;

the first spring is clamped between the spool and the first annulus;

the first end of the second spring is fixed on the second annular surface, and in the neutral position of the electromagnetic directional valve, the second end of the second spring is separated from the valve core by the free distance; or the first end of the second spring is fixed to the valve core, and the second end of the second spring is separated from the second annular surface by the free distance in the neutral position of the electromagnetic directional valve.

6. The electromagnetic directional valve as set forth in any one of claims 1-4, wherein the sleeve has a groove formed therein, the groove having a common annulus (3 c) formed therein;

the first spring is clamped between the spool and the common annulus;

the first end of the second spring is fixed on the common annular surface, and in the neutral position of the electromagnetic directional valve, the second end of the second spring is separated from the valve core by the free distance; or the first end of the second spring is fixed on the valve core, and the second end of the second spring is separated from the common annular surface by the free distance in the neutral position of the electromagnetic directional valve.

7. The electromagnetic directional valve as set forth in any one of claims 1-4, wherein a dimple (2 g) is formed in an end portion of the spool;

the first end of the second spring is fixed on the sleeve, and in the middle position of the electromagnetic reversing valve, the second end of the second spring is separated from the pit bottom of the pit by the free distance; or the first end of the second spring is fixed at the bottom of the pit, and the second end of the second spring is separated from the sleeve by the free distance in the middle position of the electromagnetic directional valve.

8. The electromagnetic directional valve as set forth in any one of claims 1-4, wherein the end of the spool forms a reduced diameter section defining a step surface (2 h);

the first end of the second spring is fixed to the sleeve, and in the middle position of the electromagnetic reversing valve, the second end of the second spring is separated from the step surface by the free distance; or the first end of the second spring is fixed on the step surface, and the second end of the second spring is separated from the sleeve by the free distance in the middle position of the electromagnetic directional valve.

9. The electromagnetic directional valve as set forth in any one of claims 1-8, wherein the second spring has an outer diameter smaller than an inner diameter of the first spring, and at least a portion of the second spring is radially surrounded by the first spring.

10. The electromagnetic directional valve as set forth in any one of claims 1-9, wherein the spring rate of the second spring is less than the spring rate of the first spring.