CN115789000A - Reversing link and hydraulic system with load holding - Google Patents

Abstract

The invention relates to a hydraulic valve, and provides a load-holding reversing linkage, which comprises a main valve, a first holding valve, a second holding valve and a holding pilot valve, wherein the main valve comprises a main valve core and a main valve cavity, the main valve core can enable the main valve core to move in the main valve cavity under the control of hydraulic oil of a first control oil port and a second control oil port so as to control the communication state between the first working oil port and the second working oil port and between an oil inlet and an oil return port, the first holding valve is positioned between the second working oil port and the main valve so as to block an oil path between the second working oil port and the main valve, the second holding valve is arranged on an unloading oil path connected with a control end of the first holding valve, and a control end of the second holding pilot valve is connected with the holding pilot valve so as to block the unloading oil path connected with the control end of the first holding valve under the control of the holding pilot valve. Through the double seal that first holding valve and second held the valve and formed, greatly reduced leaks the risk, has improved load holding performance. The invention also provides a hydraulic system.

Description

Reversing link and hydraulic system with load holding

Technical Field

The invention relates to a hydraulic valve, in particular to a reversing linkage with load holding. In addition, the invention also relates to a hydraulic system.

Background

At present, along with the rapid development of the excavator, the performance requirements of people on the excavator are more and more strict. Since the excavator does not allow excessive settlement of the boom when stationary, the load holding performance of the excavator is an important indicator, which requires low leakage when controlling the link of the excavator to a neutral state.

In order to solve the leakage problem, in the prior art, the fit clearance between the valve rod and the valve hole is usually reduced, however, the requirement on the processing precision of the valve hole and the valve rod is particularly high, and the valve rod is easy to be blocked due to too small clearance; in addition, a load holding valve may be installed between the cylinder and the main valve element to cut off the oil path by a taper seal, thereby reducing leakage.

An existing reversing connection with a retaining valve is shown in fig. 1, and mainly comprises a valve body 9, a main valve core 10, an overflow valve 11, an end cover 12, a main valve core return spring 13, a one-way valve 14, a compensation valve 15, a retaining valve and the like, wherein the retaining valve is provided with a two-stage structure of a retaining main valve and a retaining pilot control valve, the retaining main valve mainly comprises a retaining valve core 1, a retaining valve core return spring 2 and a retaining valve positioning plug 3, and the retaining pilot valve mainly comprises a pilot valve plug 4, a pilot valve core return spring 5, a pilot valve core 6 and a pilot valve sleeve 7. The working principle of the reversing combination is shown in fig. 2, and is specifically explained as follows: the main valve element 10 controls the movement direction of the actuating mechanism under the action of pilot signals pa1 and pb 1; the overflow valve 11 plays a role in overload protection; the check valve 14 prevents the oil from flowing backwards; the compensating valve 15 maintains the front-back pressure difference of the main valve core 10 unchanged, so that the movement speed of the actuating mechanism is only controlled by the opening area of the main valve core. When the reversing valve is in the middle position, oil passages among P, A, B and T are cut off by the main valve element 10, meanwhile, the cone seal between the valve element 1 and the valve body 9 is kept to block oil from leaking from a load port B to the main valve element 10, and the load is kept static in the middle position; when pa1 is signaled, the main valve element 10 moves to the left, the valve element 1 is kept open in the positive direction, oil paths between P and A, B and T are communicated, and the load rises; when pb1 signal is given, a signal of a pilot valve control oil port is also given, the main valve element 10 moves rightwards, the pilot valve is kept reversed, the pilot valve is made to be opened reversely, oil paths between P and B, A and T are communicated, and the load is reduced.

The pilot valve that keeps in the switching-over of above-mentioned prior art allies oneself with is that solitary valve block installs on the valve body, and the part is many, and the structure is complicated, and is bulky, because the installation space of small-size machinery multiple unit valve is limited, makes its assembly space too compact, and the installation difficulty, and the control fluid port of pilot valve and draining port need pass through the external oil circuit of oil pipe, lead to the oil circuit of multiple unit valve mixed and disorderly, be not convenient for assemble in earlier stage and the maintenance in later stage.

In addition, the requirement of the excavator on the load holding performance cannot be met gradually, and therefore, how to further improve the load holding performance of the reversing linkage is also a problem to be solved by those skilled in the art.

Disclosure of Invention

The invention aims to solve the technical problem of providing a reversing connection with load retention, which has good load retention performance, compact structure and less external oil paths.

The invention also aims to solve the technical problem of providing a hydraulic system which can keep the load when the hydraulic actuating mechanism is in the middle position, has a compact structure and has few external oil paths.

In order to solve the technical problem, the invention provides a reversing connection with load holding, which is characterized by comprising a valve body provided with an oil inlet, an oil return port, a first working oil port, a second working oil port, a first control oil port and a second control oil port, wherein a main valve, a first holding valve, a second holding valve and a holding pilot valve are arranged inside the valve body; when the main valve core is in the middle position state, the oil inlet, the oil return port, the first working oil port and the second working oil port are mutually blocked; when the main valve core is in the second working position state, the second working oil port is communicated with the oil inlet, and the first working oil port is communicated with the oil return port; the first holding valve is located between the second working oil port and the main valve so as to be capable of blocking an oil path between the second working oil port and the main valve when the main valve core is in the neutral state, the second holding valve is arranged on an unloading oil path connected with a control end of the first holding valve, and a control end of the second holding valve is connected with the holding pilot valve so as to be capable of blocking an unloading oil path connected with the control end of the first holding valve under the control of the holding pilot valve.

Preferably, an unloading oil path connected to the control end of the first holding valve is connected to the main valve, the unloading oil path is communicated with the oil return port when the main valve spool is in the first working position state, and the unloading oil path is blocked when the main valve spool is in the middle position or the second working position state.

Preferably, a compensation valve is further arranged inside the valve body and connected with the main valve so as to control the front-back pressure difference of the main valve to be constant.

Preferably, the main valve cavity includes a first spring cavity, a first oil return cavity, a first working cavity, a first pressure compensation cavity, an oil inlet cavity, a second pressure compensation cavity, a third pressure compensation cavity, a second working cavity, a second oil return cavity and a second spring cavity, the first spring cavity is connected to the first control oil port, the second spring cavity is connected to the second control oil port, the first oil return cavity and the second oil return cavity are both connected to the oil return port, the oil inlet cavity is connected to the oil inlet, the first pressure compensation cavity, the second pressure compensation cavity and the third pressure compensation cavity are all connected to the compensation valve, the first working cavity is connected to the first working oil port, the second working cavity is connected to the first holding valve, wherein, when the main valve core is in the first working position state, the oil inlet cavity is communicated to the second pressure compensation cavity, the first pressure compensation cavity is communicated to the first working cavity, and the second oil return cavity is communicated to the second working cavity and the second holding valve; when the main valve core is in the second working position state, the oil inlet cavity is communicated with the second pressure compensation cavity, the third pressure compensation cavity is communicated with the second working cavity, an oil way between the first oil return cavity and the first working cavity is communicated, and an oil way between the second oil return cavity and the second retaining valve is closed; when the main valve core is in the middle position state, an oil path between the oil inlet cavity and the second pressure compensation cavity is cut off, an oil path between the first working cavity and the first oil return cavity and the first pressure compensation cavity is cut off, the second working cavity is not communicated with the third pressure compensation cavity and the second oil return cavity, and an oil path between the second oil return cavity and the second retaining valve is cut off.

Preferably, the first retaining valve comprises a first retaining valve core, a first retaining valve return spring, a first retaining valve oil inlet communicated with the second working cavity, a first retaining valve oil outlet cavity communicated with the second working oil port, and a first retaining valve control cavity connected with the second retaining valve, and the first retaining valve return spring is arranged in the first retaining valve control cavity to enable one end of the first retaining valve core to be abutted against the first retaining valve oil inlet so as to form conical sealing between the first retaining valve oil inlet and the first retaining valve oil outlet cavity.

Preferably, the second holding valve includes a second holding valve core, a second holding valve return spring, a second holding valve oil inlet chamber, a second holding valve oil outlet and a second holding valve control chamber, the second holding valve return spring is disposed in the second holding valve control chamber to be able to press one end of the second holding valve core against the second holding valve oil outlet to form a cone seal between the second holding valve oil outlet and the holding valve oil inlet chamber, a first holding valve control oil passage, a second holding valve control oil passage and a second holding valve oil unloading passage are formed inside the valve body, the first holding valve control oil passage communicates the first holding valve control chamber with the second holding valve oil inlet chamber, the second holding valve control oil passage communicates the second holding valve control chamber with the holding pilot valve, the second holding valve oil unloading passage communicates the second holding valve oil outlet with the main valve chamber, wherein when the first working position of the first holding valve core is in the first working position state, the second holding valve oil unloading passage communicates with the second oil return chamber, when the second working position of the main valve core is in the second working position, or the second holding valve oil unloading passage is blocked with the second holding valve oil outlet in the second holding valve oil control chamber.

Preferably, the pilot valve holding body comprises a pilot valve holding body and a pilot valve holding body, the pilot valve holding body comprises a pilot valve signal oil chamber communicated with the first control oil port, a pilot valve oil inlet chamber communicated with the second pilot valve control oil passage, and a pilot valve oil discharge chamber communicated with the oil return port, and the hydraulic oil of the first control oil port controls the pilot valve holding body to move in the pilot valve holding body, so that the pilot valve oil inlet chamber is communicated with the pilot valve oil discharge chamber.

Preferably, a one-way valve is provided between the compensation valve and the main valve.

Preferably, a first overflow valve and a second overflow valve are respectively arranged between the first working oil port and the oil return port and between the second working oil port and the oil return port.

Further, the invention also provides a hydraulic system, which comprises the reversing link with the load holding function in any one of the technical schemes.

Through the scheme, the invention has the following beneficial effects:

the reversing connection with load holding is provided with two holding valves in series, so that double sealing is formed, the leakage risk is greatly reduced, the leakage is reduced, and the load holding performance is better. And the pilot valve is kept to be arranged in the valve body, so that the number of parts is reduced, the structure of the reversing connector is simpler and more compact, and the whole volume and weight of the valve body are reduced. Simultaneously, the connection oil circuit between each hydraulic structure all sets up in the inside of valve body, need not external oil pipe, has simplified the external oil circuit of switching-over antithetical couplet, makes earlier assembly and the maintenance in later stage more convenient high-efficient.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic structural diagram of a conventional reversing unit;

FIG. 2 is a hydraulic schematic of a prior art reversing link;

FIG. 3 is a hydraulic schematic of the reversing coupling with load holding of the present invention;

FIG. 4 is a schematic diagram of the configuration of the reversing train with load holding of the present invention;

FIG. 5 is an enlarged view of a portion of the reversing chain with load retention of the present invention;

FIG. 6 is a schematic view of a first retainer valve cartridge of the present invention;

fig. 7 is a schematic diagram of the pilot-holding spool of the present invention.

Description of the reference numerals

1 valve body 11 Main valve body

12 first end cap 13 second end cap

101 pilot signal oil passage 102 first holding valve control oil passage

103 pilot oil discharge passage 104 second holding valve control oil passage

105 second holding valve oil discharge passage 106 overflow passage one

107 overflow oil passage two 2 main valve

21 main spool 22 main valve chamber

201 first spring chamber 202 first oil return chamber

203 first working chamber 204 first pressure compensation chamber

205 into oil chamber 206 a second pressure compensation chamber

207 third pressure compensation chamber 208 second working chamber

209 second oil spill Cavity 210 third oil spill Cavity

211 second spring Chamber 3 first holding valve

31 first retainer spool 311 spring bore

312 center hole 313 damping hole

32 first holding valve return spring 33 first holding valve oil inlet

34 first holding valve oil outlet chamber 35 first holding valve control chamber

4 second holding valve 41 second holding spool

42 second holding valve return spring 43 second holding valve oil feed chamber

44 second holding valve outlet 45 second holding valve control chamber

5 hold pilot valve 51 hold pilot valve spool

511 control the 512 channel part of the sealing part

513 tapered seal 514 spring mount

52 pilot valve signal oil chamber 53 pilot valve oil inlet chamber

54 pilot valve oil relief cavity 55 pilot valve spring

6 first overflow valve 7 second overflow valve

8 one-way valve 9 compensating valve

91 compensating valve core 92 compensating valve oil inlet cavity

93 oil outlet cavity P oil inlet of compensation valve

T oil return opening A first working oil opening

B second working oil port a first control oil port

b second control oil port

Detailed Description

The following detailed description of the present invention is provided in conjunction with the accompanying drawings, and it is to be understood that the detailed description is provided only for the purpose of illustrating and explaining the present invention, and the scope of the present invention is not limited to the following detailed description.

In the description of the present invention, it should be noted that, unless otherwise explicitly stated or limited, the terms "formed," "provided," "disposed," "connected," and the like are to be construed broadly, and for example, the connection may be a direct connection, an indirect connection via an intermediate medium, a fixed connection, a detachable connection, or an integral connection; either directly or indirectly through intervening connectors, either internally or in any combination of the two or more elements. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

In the present invention, unless otherwise specified, the terms "left", "right", and the like, are used to indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are used merely for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention; for the orientation terms of the present invention, it should be understood in connection with the actual installation state.

The terms "first", "second", "third" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, and therefore the features defined "first", "second", "third" may explicitly or implicitly include one or more of the features described.

As shown in fig. 3 to 4, a specific embodiment of the reversing connection with load holding according to the present invention includes a valve body 1 having an oil inlet P, an oil return port T, a first working oil port a, a second working oil port B, a first control oil port a, and a second control oil port B, where the oil inlet P is used for externally connecting a hydraulic pump of a hydraulic system, the oil return port T is used for externally connecting an oil return tank of the hydraulic system, the first working oil port a and the second working oil port B are used for connecting a hydraulic actuator, and the first control oil port a and the second control oil port B are respectively used for connecting different control oil paths in the hydraulic system. The main valve 2 comprises a main valve core 21 and a main valve cavity 22, a first control oil port a and a second control oil port B are respectively connected to two ends of the main valve cavity 22 through oil ducts arranged in the valve body 1, the main valve core 21 is controlled to move in the main valve cavity 22 through hydraulic oil of the first control oil port a and the second control oil port B, the moving stroke range of the main valve core 21 at least comprises a first working position and a second working position for controlling a hydraulic execution element to move along opposite directions and a middle position located between the first working position and the second working position, wherein in the state that the main valve core 21 is in the first working position, the first working oil port A is communicated with the oil inlet P, and the second working oil port B is communicated with the oil return port T; when the main valve core 21 is in a middle state, the oil inlet P, the oil return port T, the first working oil port A and the second working oil port B are mutually stopped; when the main valve core 21 is in the second working position state, the second working oil port B is communicated with the oil inlet P, the first working oil port a is communicated with the oil return port T, and the communication state of the first working oil port a with the oil inlet P and the oil return port T and the communication state of the second working oil port B with the oil inlet P and the oil return port T are switched through the main valve core 2, so that the working states of hydraulic actuating elements on the first working oil port a and the second working oil port B are controlled; the first holding valve 3 is positioned between the second working port B and the main valve 2 so as to block an oil path between the second working port B and the main valve 2 when the main valve spool 21 is in a neutral state, the second holding valve 4 is disposed on an unloading oil path to which a control end of the first holding valve 3 is connected, and a control end of the second holding valve 4 is connected to the holding pilot valve 5 so as to block an unloading oil path to which a control end of the first holding valve 3 is connected under the control of the holding pilot valve 5. When the main valve core 21 is in a middle state, the second working oil port B, the oil inlet P and the oil return port T are all cut off, the valve core position of the second holding valve 4 is controlled by the holding pilot valve 5, so that the second holding valve 4 forms a conical seal of an internal oil passage thereof, the control end of the first holding valve 3 cannot unload the oil pressure through an unloading oil passage, the valve core position of the first holding valve 3 is always in a closed state, the conical seal of the internal oil passage of the first holding valve 3 is ensured, the oil passage between the second working oil port B and the main valve 2 is blocked, the hydraulic oil at the second working oil port B is prevented from leaking to the oil return port T through a gap between the main valve core 21 and the main valve cavity 22, and the leakage risk is greatly reduced through the double seal formed by the first holding valve 3 and the second holding valve 4, and the occurrence of the oil leakage situation is reduced, so that the reversing valve assembly with load holding of the invention has better load holding performance.

Referring to fig. 3 and 4, as a specific embodiment of the reversing valve with load holding of the present invention, an unloading oil path connected to a control end of a first holding valve 3 is connected to a main valve 2, the unloading oil path communicates with an oil return port T when a main valve body 21 is in a first operating position, and the unloading oil path is blocked when the main valve body 21 is in a neutral position or a second operating position, so that the unloading oil path and the oil return port T can be synchronously controlled by controlling the main valve body 21 to move in a main valve cavity 22.

As a preferred embodiment of the reversing linkage with load holding according to the present invention, referring to fig. 3 and 4, a compensation valve 9 is further disposed inside the valve body 1, and the compensation valve 9 is connected to the main valve 2 for performing pressure compensation on the hydraulic oil output through the main valve 2 to control the front-rear differential pressure of the main valve 2 to be constant, so that the flow rate of the hydraulic oil passing through the main valve 2 can be controlled only by the opening degree of the valve port of the main valve core 21, and further, the movement speed of the hydraulic actuator can be better controlled only by the opening degree of the valve port.

As a preferred embodiment of the reversing linkage with load holding according to the present invention, referring to fig. 4, the main valve cavity 22 includes a first spring cavity 201, a first oil return cavity 202, a first working cavity 203, a first pressure compensation cavity 204, an oil inlet cavity 205, a second pressure compensation cavity 206, a third pressure compensation cavity 207, a second working cavity 208, a second oil return cavity 209, and a second spring cavity 211, which are sequentially arranged, the first spring cavity 201 is connected to a first control oil port a through an internal oil passage of the valve body 1, the second spring cavity 211 is connected to a second control oil port b through an internal oil passage of the valve body 1, the first oil return cavity 202 and the second oil return cavity 209 are both connected to an oil return port T through an internal oil passage of the valve body 1, the oil inlet cavity 205 is connected to an oil inlet P through an internal oil passage of the valve body 1, the first pressure compensation cavity 204, the second pressure compensation cavity 206, and the third pressure compensation cavity 207 are all connected to the compensation valve 9 through an internal oil passage of the valve body 1, the first working cavity 203 is connected to a first working cavity a through an internal oil passage of the valve body 1, and the second working cavity 208 is connected to the first holding valve 3 through an internal oil passage of the valve body 1.

When control oil is supplied into the first spring cavity 201 through the first control oil port a to push the main valve element 21 to move towards the second spring cavity 211, so that the main valve element 21 is in the first working position state, the oil inlet cavity 205 is communicated with the second pressure compensation cavity 206, the first pressure compensation cavity 204 is communicated with the first working cavity 203, and the second oil return cavity 209 is communicated with the second working cavity 208 and the second holding valve 4; the hydraulic oil at the oil inlet P can sequentially flow through the oil inlet cavity 205 and the second pressure compensation cavity 206 to flow into the compensation valve 9 for pressure compensation, the compensated hydraulic oil flows to the first pressure compensation cavity 204 and flows to the first working oil port a through the first working cavity 203 to supply oil to the hydraulic actuator, meanwhile, the pilot valve 5 is kept to control the opening of the valve core of the second holding valve 4, the hydraulic oil at the control end of the first holding valve 3 can flow to the second oil return cavity 209 through the second holding valve 4 and flow into the oil return port T to complete unloading, so that the valve core of the first holding valve 3 is opened, and the hydraulic actuator returns to the first holding valve 3 through the second working oil port B and flows through the first holding valve 3 sequentially through the second working cavity 208 and the second oil return cavity 209 to return oil to the oil return port T.

When control oil is supplied into the second spring cavity 211 through the second control oil port b to push the main valve element 21 to move towards the first spring cavity 201, so that the main valve element 21 is in a second working position state, the oil inlet cavity 205 is communicated with the second pressure compensation cavity 206, the third pressure compensation cavity 207 is communicated with the second working cavity 208, an oil path between the first oil return cavity 202 and the first working cavity 203 is communicated, and an oil path between the second oil return cavity 209 and the second holding valve 4 is closed; the hydraulic oil at the oil inlet P can sequentially pass through the oil inlet cavity 205 and the second pressure compensation cavity 206 to flow into the compensation valve 9 for pressure compensation, the compensated hydraulic oil flows to the third pressure compensation cavity 207 and flows to the first holding valve 3 through the second working cavity 208, the hydraulic oil pushes the valve core of the first holding valve 3 to open, the hydraulic oil flowing through the first holding valve 3 flows to the second working oil port B to supply oil to the hydraulic actuator, and meanwhile, the hydraulic actuator sequentially flows through the first working oil port a, the first working cavity 203 and the first oil return cavity 202 to return oil to the oil return port T.

When the main valve element 21 is in a neutral state, an oil path between the oil inlet cavity 205 and the second pressure compensation cavity 206 is cut off, an oil path between the first working cavity 203 and the first oil return cavity 202 and the first pressure compensation cavity 204 is cut off, an oil path between the second working cavity 208 and the third pressure compensation cavity 207 is not communicated with the second oil return cavity 209, an oil path between the second oil return cavity 209 and the second holding valve 4 is cut off, and a valve element of the second holding valve 4 is closed to keep a valve element closing state of the first holding valve 3, so that double sealing is formed.

As a preferred embodiment of the reversing linkage with load holding of the present invention, referring to fig. 4 and 5, the first holding valve 3 includes a first holding valve core 31, a first holding valve return spring 32, a first holding valve oil inlet 33 communicating with the second working chamber 208, a first holding valve oil outlet chamber 34 communicating with the second working oil port B, and a first holding valve control chamber 35 connected with the second holding valve 4, the first holding valve return spring 32 and the first holding valve core 31 are both installed in the chamber of the valve body 1, and a plug is installed at an opening of the chamber to form a seal, the first holding valve oil inlet 33 and the first holding valve control chamber 35 are respectively located at both ends of the first holding valve core 31, the first holding valve return spring 32 is disposed in the first holding valve control chamber 35 to be able to abut one end of the first holding valve core 31 against the first holding valve oil inlet 33, so as to abut a tapered sealing surface between the first holding valve core 31 and the first holding valve oil outlet chamber 33 to form a tapered sealing surface between the first holding valve core 33 and the first holding valve oil outlet chamber 34, thereby being able to well perform a hydraulic sealing of the first holding valve to maintain the oil outlet 33 in a state, and to keep the first holding valve oil outlet 34 in a hydraulic state, and to prevent the first holding valve oil outlet 33 from leaking in a hydraulic pressure state, and to maintain the first holding state, and maintain the first holding valve outlet chamber 33 in a hydraulic pressure. In addition, the first holding valve control cavity 35 is connected to the second holding valve 4, and in a valve core closed state of the second holding valve 4, the pressure of the hydraulic oil in the first holding valve control cavity 35 (i.e. the hydraulic oil at the control end of the first holding valve 3) cannot be unloaded through the unloading oil path, so that it is ensured that the oil pressure in the first holding valve control cavity 35 is not reduced, the abutting state between the first holding valve core 31 and the first holding valve oil inlet 33 is maintained, the conical sealing between the first holding valve control cavity 31 and the first holding valve oil inlet 33 is stable and reliable, the communication between the first holding valve control cavity 35 and the second working cavity 208 is blocked, and the leakage is effectively prevented.

As a preferred embodiment of the reversing valve with load holding of the present invention, referring to fig. 4 and 5, the second holding valve 4 includes a second holding valve core 41, a second holding valve return spring 42, a second holding valve oil inlet chamber 43, a second holding valve oil outlet 44 and a second holding valve control chamber 45, the second holding valve core 41 and the second holding valve return spring 42 are both installed in the chamber of the valve body 1, and a plug is installed at the opening of the chamber to form a seal, the second holding valve oil outlet 44 and the second holding valve control chamber 45 are respectively located at both ends of the second holding valve core 41, the second holding valve return spring 42 is disposed in the second holding valve control chamber 45 to be able to abut one end of the second holding valve core 41 against the second holding valve oil outlet 44 to form a taper seal between the second holding valve oil outlet 44 and the holding valve oil inlet chamber 43, a first holding valve control oil passage 102, a second holding valve control oil passage 104 and a second holding valve oil discharge passage 105 are formed inside the valve body 1, the first holding valve control oil passage 102 communicates the first holding valve control chamber 35 with the second holding valve oil inlet chamber 43, the second holding valve oil discharge passage 105 communicates the second holding valve oil outlet 44 with the main valve chamber 22, the first holding valve control oil passage 102 and the second holding valve oil discharge passage 105 together constitute an unloading oil passage to which the control end of the first holding valve 3 is connected, the second holding valve control oil passage 104 communicates the second holding valve control chamber 45 with the holding pilot valve 5 so that the hydraulic oil in the second holding valve control chamber 45 can be unloaded through the second holding valve control oil passage 104 under the control of the holding pilot valve 5, wherein, in the first operating position state of the main valve core 21, the second holding valve oil discharge passage 105 of the main valve core 21 communicates with the second oil return chamber 209, when the main valve spool is in the second working position or neutral state, the gap between the second holding valve oil drain 105 and the second oil return chamber 209 is blocked by the main valve spool 21.

It should be noted that, the structure of the first holding valve core 31 is the same as that of the second holding valve core 41, taking the first holding valve core 31 as an example, referring to fig. 4 and 6, a spring hole 311 for installing the first holding valve return spring 32 is provided at one end of the first holding valve core 31, a conical sealing surface for abutting against the first holding valve oil inlet 33 to form a conical seal is formed at the other end, a central hole 312 is provided at the bottom of the spring hole 311, the central hole 312 is a blind hole, and a damping hole 313 communicating with the central hole 312 is formed on the circumferential outer side surface of the first holding valve core 31, so that the hydraulic oil in the first holding valve oil outlet chamber 34 can flow to the first holding valve control chamber 35 through the damping hole 313, the central hole 312 and the spring hole 311 in sequence, so that the first holding valve control chamber 35 can form a pressure acting on the end surface of the first holding valve core 31, and can abut against the pressure of the oil pressure of the first holding valve oil outlet chamber 34 acting on the end surface of the other end of the first holding valve core 31, and the first holding valve core 31 can always form a conical seal 33 under the elastic force of the first holding valve return spring 32. In the case of unloading the oil pressure of the first holding valve control chamber 35, due to the presence of the orifice 313, a hydraulic pressure difference is formed between the first holding valve control chamber 35 and the first holding valve oil outlet chamber 34, and this hydraulic pressure difference acts on the first holding valve spool 31, forming a force that urges the first holding valve spool 31 to move toward the first holding valve control chamber 35 against the elastic force of the first holding valve return spring 32, so that the first holding valve oil outlet chamber 34 communicates with the first holding valve oil inlet port 33. Since the second holding spool 41 has the same structure as the first holding spool 31, the structure and operation principle of the second holding spool 41 should be known to those skilled in the art with the knowledge of the structure and operation principle of the first holding spool 31, and will not be described herein.

As a preferred embodiment of the direction change coupling with load holding according to the present invention, referring to fig. 4 and 5, the pilot holding valve 5 includes a pilot holding valve spool 51 and a pilot holding valve chamber, the pilot holding valve chamber includes a pilot signal oil chamber 52 communicated with a first control oil port a, a pilot oil inlet chamber 53 communicated with a second pilot holding valve control oil chamber 104, and a pilot oil discharge chamber 54 communicated with an oil return port T, a pilot signal oil passage 101 and a pilot oil discharge passage 103 are formed inside the valve body 1, the pilot signal oil passage 101 communicates the first spring chamber 201 with the pilot signal oil chamber 52, hydraulic oil of the first control oil port a can flow into the pilot signal oil chamber 52, the pilot holding valve spool 51 is controlled to move inside the pilot holding valve chamber so that the pilot oil inlet chamber 53 is communicated with the pilot oil discharge chamber 54, the pilot oil discharge passage 103 is connected with the oil return port T, so that hydraulic oil in the second pilot holding valve control chamber 45 can be communicated with the oil return port T for discharging, wherein a pilot spring 55 is provided inside the pilot holding valve spool 51 to move toward the pilot signal oil chamber 52, thereby reducing the weight of the valve assembly, and reducing the overall assembly difficulty of the valve body 1 and the weight of the pilot valve assembly.

It should be noted that, referring to fig. 4 and fig. 7, the pilot valve holding core 51 includes a control sealing portion 511, a channel portion 512, a conical sealing portion 513 and a spring mounting portion 514, which are arranged in sequence, the control sealing portion 511 is located between the pilot valve signal oil chamber 52 and the pilot valve oil inlet chamber 53 to isolate them from each other, the channel portion 512 is located between the pilot valve oil inlet chamber 53 and the pilot valve oil discharge chamber 54 to form a circulating oil passage for communicating them with each other, the conical sealing portion 513 is located in the pilot valve oil discharge chamber 54, the pilot valve spring 55 is mounted on the spring mounting portion 514 to form an elastic force for pushing and holding the pilot valve core 51 to move towards the pilot valve signal oil chamber 52, so as to abut the conical sealing portion 513 on the end surface of the pilot valve oil discharge chamber 54 close to the pilot valve oil inlet chamber 53 side to seal the cone between the pilot valve oil inlet chamber 53 and the circulating oil passage; when the pilot oil is input from the first control oil port a, the pilot oil can enter the pilot valve signal oil chamber 52 to push and keep the pilot valve spool 51 moving toward the pilot valve oil discharge chamber 54, so that the pilot valve oil inlet chamber 53 is communicated with the circulation oil passage.

Specifically, when the first control oil port a has control pressure, the main valve element 21 moves towards the second control oil port B to be in the first working position, and hydraulic oil of the first control oil port a flows into the pilot valve signal oil chamber 52 through the pilot signal oil passage 101, so as to push the pilot valve element 51 to move towards the pilot valve spring 55, and hydraulic oil of the second holding valve control chamber 45 can return to the oil return port T through the second holding valve control oil passage 104 for unloading, so as to control the second holding valve element 41 to move, so that the first holding valve control oil passage 102 is communicated with the second holding valve oil discharge passage 105, so that hydraulic oil in the first holding valve control chamber 35 sequentially flows through the first holding valve control oil passage 102, the second holding valve 4, the second holding valve oil discharge passage 105 and the second oil return chamber 209 for returning to the oil return port T for unloading, and further controls the first holding valve element 31 to move, so as to realize communication between the second working oil port B and the second working chamber 208, so as to return oil to the second working port B; when the first control oil port a has no control pressure, that is, the main valve element 21 is in the second working position or the middle position, the oil passage between the second holding valve oil discharge passage 105 and the second oil return chamber 209 is blocked by the main valve element 21, the pilot valve element 51 is maintained to return to the original position under the elastic force of the pilot valve spring 55, and the second holding valve control oil passage 104 and the pilot oil discharge passage 103 are blocked, so that the valve elements of the first holding valve 3 and the second holding valve 4 are both in the closed state, when the main valve element 21 is in the second working position, the high-pressure oil flowing from the oil inlet P to the second working chamber 208 can push open the first holding valve element 31 to supply oil to the second working port B, and when the main valve element 21 is in the middle position, the second working chamber 208 and the oil inlet P are blocked, so that the valve elements of the first holding valve 3 and the second holding valve element 4 are always in the closed state under the spring force and the oil pressure, so as to form double sealing.

As a preferred embodiment of the inventive reversing connection with load holding, a non-return valve 8 is arranged between the main valve 2 and the compensating valve 9, see fig. 4, to prevent the hydraulic oil in the main valve 2 from flowing backwards towards the compensating valve 9. Specifically, the compensation valve 9 includes a compensation valve core 91 and a compensation valve cavity, the compensation valve cavity includes a compensation valve oil inlet cavity 92 communicated with the second pressure compensation cavity 206, and a compensation cavity oil outlet cavity 93 communicated with the first pressure compensation cavity 204 and the third pressure compensation cavity 207 respectively, when the oil inlet P feeds oil into the second pressure compensation cavity 206, the oil pressure change in the second pressure compensation cavity 206 can make the compensation valve core 91 move in the compensation valve cavity, so as to control the oil flow between the compensation valve oil inlet cavity 92 and the compensation valve oil outlet cavity 93, so as to keep the pressure difference between the first working cavity 203 or the second working cavity 208 and the second pressure compensation cavity 206 constant, and a check valve 8 is arranged between the compensation valve oil outlet cavity 93 and the first pressure compensation cavity 204 and the third pressure compensation cavity 207, so as to ensure that the hydraulic oil in the compensation valve oil outlet cavity 93 flows into the first pressure compensation cavity 204 or the third pressure compensation cavity 207 in a one-way.

As a preferred embodiment of the reversing connection with load holding according to the present invention, referring to fig. 4 and 5, a first relief valve 6 and a second relief valve 7 are respectively provided between the first working port a and the oil return port T and between the second working port B and the oil return port T. Specifically, the oil inlet of the first overflow valve 6 is communicated with the first working chamber 203, the oil outlet of the first overflow valve 6 is communicated with the first oil return chamber 202, and when the hydraulic oil pressure of the first working oil port a exceeds a set value, the first overflow valve 6 can be directly unloaded to the oil return port T: because the first holding valve 3, the second holding valve 4 and the holding pilot valve 5 are arranged in the valve body 1 at the second working oil port B, in order to facilitate installation of the second overflow valve 7, an overflow oil duct i 106 and an overflow oil duct i 107 are further formed in the valve body 1, the main valve cavity 22 further comprises a third oil return cavity 210 located between the second oil return cavity 209 and the second spring cavity 211, the third oil return cavity 210 is communicated with the oil return port T, an oil inlet of the second overflow valve 7 is communicated with the first holding valve oil outlet cavity 34 through the overflow oil duct i 107, an oil return port of the second overflow valve 7 is communicated with the third oil return cavity 210 through the overflow oil duct i 106, when the hydraulic oil pressure of the second working oil port B exceeds a set value, direct unloading can be directly conducted through the second overflow valve 7 to the oil return port T, so as to ensure that a hydraulic actuator works under a set pressure, and ensure work safety.

It should be noted that, in order to facilitate maintenance of the main valve 2 and the oil passage inside the valve body 1, referring to fig. 4, the valve body 1 adopts a split design, and includes a main valve body 11, a first end cap 12 and a second end cap 13, the main valve cavity 22 penetrates through the main valve body 11, the first end cap 12 and the second end cap 13 are respectively installed on two sides of the main valve body 11 to close two end openings of the main valve cavity 22 on the main valve body 11, so as to form a completed main valve cavity 22, wherein a first spring cavity 201 is disposed in the first end cap 12, a first control oil port a is formed in the first end cap 12, a second spring cavity 211 is disposed in the second end cap 13, and a second control oil port b is formed in the second end cap 13.

The working principle of the reversing linkage with load holding according to the present invention is described below with reference to a relatively preferred embodiment, in which the hydraulic actuator is a hydraulic cylinder, the first working fluid port a is connected to a rod chamber of the hydraulic cylinder, and the second working fluid port B is connected to a rodless chamber of the hydraulic cylinder:

when no control oil is input into the first control oil port a and the second control oil port B, the main valve core 21 is in the middle position, and oil paths among the first working oil port a, the second working oil port B, the oil return port T and the oil inlet T are all cut off by the seal formed by the main valve core 21 and the main valve cavity 22. Meanwhile, the oil path between the second holding valve oil discharge passage 105 and the oil return port T is also cut off by the seal formed by the main spool 21 and the main spool chamber 22, and the pilot valve 5 is kept in a closed state, under the action of the oil pressure in the second holding valve control chamber 45 and the second holding valve return spring 42, the second holding spool 41 tightly abuts against the second holding valve oil outlet 44 to form a conical seal between the second holding valve oil outlet 44 and the second holding valve oil inlet chamber 43, the hydraulic oil in the first holding valve control chamber 35 is blocked to flow through the first holding valve oil control passage 102 and the second holding valve oil discharge passage 105 to leak from the gap between the main spool 21 and the main spool chamber 22, so that the oil pressure in the second holding valve oil discharge passage 105 is not reduced, the hydraulic oil in the first holding valve control chamber 35 and the action of the first holding valve return spring 32, the first holding spool 31 can always abut against the first holding valve oil inlet 33 to form a seal between the first holding valve oil inlet 33 and the first holding valve oil outlet chamber 34, the hydraulic oil is greatly kept from the second holding valve oil outlet chamber 21B to maintain the double working oil port connection between the hydraulic cylinder, and the hydraulic cylinder load is not changed by the original working oil port B, and the hydraulic cylinder load is not increased.

When the first control oil port a inputs control oil, the main valve element 21 is at a first working position, the oil inlet cavity 205 is communicated with the second pressure compensation cavity 206, the first pressure compensation cavity 204 is communicated with the first working cavity 203, the second oil return cavity 209 is communicated with the second working cavity 208, and the second holding valve oil discharge passage 105 is communicated with the second oil return cavity 209. The high-pressure hydraulic oil in the oil inlet P sequentially flows into the compensating valve 9 from the oil inlet cavity 205 and the second pressure compensation cavity 206, and sequentially flows into the rod cavity from the first pressure compensation cavity 204, the first working cavity 203 and the first working oil port a after pressure compensation; meanwhile, the control hydraulic oil of the first control oil port a flows into the pilot valve signal oil chamber 52 through the first spring chamber 201 and the first arrival signal oil passage 101 in sequence, the pilot valve holding valve core 51 is pushed to open the flow oil passage between the pilot valve oil inlet chamber 53 and the pilot valve oil unloading chamber 54, the second holding valve control chamber 45 is unloaded through the second holding valve control oil passage 104 to push the second holding valve core 41 to open, so that the first holding valve control chamber 35 is communicated with the oil return port T to realize unloading, the first holding valve core 31 is pushed to open, the hydraulic oil in the rodless chamber of the hydraulic cylinder sequentially flows through the first holding valve oil outlet chamber 34, the first holding valve oil outlet language 33, the second working chamber 208 and the second oil return strength 209 through the second working port B to return oil to the oil return port T, and further realize the retraction of the piston rod of the hydraulic cylinder.

When the second control oil port b inputs control oil, the main valve element 21 is at a second working position, the oil inlet cavity 205 is communicated with the second pressure compensation cavity 206, the third pressure compensation cavity 207 is communicated with the second working cavity 208, the first oil return cavity 202 is communicated with the first working cavity 203, and an oil path between the second oil return cavity 209 and the second holding valve oil unloading oil duct 105 is closed by the seal formed by the main valve element 21 and the main valve cavity 22. The high-pressure hydraulic oil at the oil inlet P sequentially flows into the compensation cavity 9 from the oil inlet cavity 205 and the second pressure compensation cavity 206, sequentially flows through the third pressure compensation cavity 207 and the second working cavity 208 after pressure compensation, flows to the first holding valve oil inlet 33, pushes the first holding valve property 31 to enable the first holding valve oil inlet 33 and the first holding valve oil outlet cavity 34 to be the same, and further flows to the second working oil port B to supply oil to the rodless cavity; meanwhile, hydraulic oil in a rod cavity of the hydraulic cylinder sequentially flows through the first working oil port a through the first working cavity 203 and the first oil return cavity 202 to return oil to the oil return port T, so that the piston rod of the hydraulic cylinder extends out.

The present invention also provides a hydraulic system including the inventive reversing coupling with load retention, which therefore has all the benefits of the inventive reversing coupling with load retention and will not be described in any greater detail herein.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the foregoing embodiments may be combined in any suitable manner without contradiction. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims (10)

1. The reversing connection with the load holding function comprises a valve body (1) provided with an oil inlet (P), an oil return port (T), a first working oil port (A), a second working oil port (B), a first control oil port (a) and a second control oil port (B), wherein a main valve (2), a first holding valve (3), a second holding valve (4) and a holding pilot valve (5) are arranged inside the valve body (1), the main valve (2) comprises a main valve core (21) and a main valve cavity (22), the main valve core (21) is controlled to move in the main valve cavity (22) through hydraulic oil of the first control oil port (a) and the second control oil port (B), the moving stroke range of the main valve core (21) at least comprises a first working position and a second working position for controlling a hydraulic execution element to move along opposite directions, and a middle position located between the first working position and the second working position, wherein the first working oil port (A) is communicated with the second working oil port (P) and the oil return port (B) is communicated with the oil inlet (T); when the main valve core (21) is in the middle position state, the oil inlet (P), the oil return port (T), the first working oil port (A) and the second working oil port (B) are mutually blocked; when the main valve core (21) is in the second working position state, the second working oil port (B) is communicated with the oil inlet (P), and the first working oil port (A) is communicated with the oil return port (T); the first holding valve (3) is located between the second working oil port (B) and the main valve (2) so as to be capable of blocking an oil path between the second working oil port (B) and the main valve (2) when the main valve core (21) is in the neutral state, the second holding valve (4) is arranged on an unloading oil path connected with a control end of the first holding valve (3), and a control end of the second holding valve (4) is connected with the holding pilot valve (5) so as to be capable of blocking the unloading oil path connected with the control end of the first holding valve (3) under the control of the holding pilot valve (5).

2. The reversing coupling with load holding according to claim 1, characterized in that an unloading oil path connected to the control end of the first holding valve (3) is connected to the main valve (2), and in the first operating position of the main valve spool (21), the unloading oil path is connected to the oil return port (T), and in the neutral position or the second operating position of the main valve spool (21), the unloading oil path is blocked.

3. The reversing union with load holding according to claim 1, characterized in that a compensation valve (9) is further arranged inside the valve body (1), and the compensation valve (9) is connected with the main valve (2) to control the constant differential pressure across the main valve (2).

4. The reversing coupling with load holding according to claim 3, characterized in that the main valve chamber (22) comprises a first spring chamber (201), a first oil return chamber (202), a first working chamber (203), a first pressure compensation chamber (204), an oil inlet chamber (205), a second pressure compensation chamber (206), a third pressure compensation chamber (207), a second working chamber (208), a second oil return chamber (209) and a second spring chamber (211), the first spring chamber (201) is connected with the first control oil port (a), the second spring chamber (211) is connected with the second control oil port (b), the first oil return chamber (202) and the second oil return chamber (209) are both connected with the oil return port (T), the oil inlet chamber (205) is connected with the oil inlet (P), the first pressure compensation chamber (204), the second pressure compensation chamber (206) and the third pressure compensation chamber (207) are all connected with the compensation valve (9), the first working chamber (203) is connected with the first working chamber (208A), and the second working chamber (208) is connected with the first working port (3), wherein the first working chamber (208) is connected with the first oil return chamber (3),

when the main valve element (21) is in the first working position state, the oil inlet cavity (205) is communicated with the second pressure compensation cavity (206), the first pressure compensation cavity (204) is communicated with the first working cavity (203), and the second oil return cavity (209) is communicated with the second working cavity (208) and the second retaining valve (4);

when the main valve core (21) is in the second working position state, the oil inlet cavity (205) is communicated with the second pressure compensation cavity (206), the third pressure compensation cavity (207) is communicated with the second working cavity (208), an oil path between the first oil return cavity (202) and the first working cavity (203) is communicated, and an oil path between the second oil return cavity (209) and the second holding valve (4) is cut off;

when the main valve core (21) is in the middle position state, an oil path between the oil inlet cavity (205) and the second pressure compensation cavity (206) is cut off, an oil path between the first working cavity (203) and the first oil return cavity (202) and the first pressure compensation cavity (204) is cut off, the second working cavity (208) is not communicated with the third pressure compensation cavity (207) and the second oil return cavity (209), and an oil path between the second oil return cavity (209) and the second retaining valve (4) is cut off.

5. The reversing coupling with load holding according to claim 4, characterized in that the first holding valve (3) comprises a first holding valve spool (31), a first holding valve return spring (32), a first holding valve oil inlet (33) communicating with the second working chamber (208), a first holding valve oil outlet chamber (34) communicating with the second working oil port (B), and a first holding valve control chamber (35) connected with the second holding valve (4), the first holding valve return spring (32) being arranged within the first holding valve control chamber (35) to be able to hold one end of the first holding valve spool (31) against the first holding valve oil inlet (33) forming a cone seal between the first holding valve oil inlet (33) and the first holding valve oil outlet chamber (34).

6. The commutating linkage with load holding according to claim 5, characterized in that the second holding valve (4) comprises a second holding valve spool (41), a second holding valve return spring (42), a second holding valve oil inlet chamber (43), a second holding valve oil outlet (44) and a second holding valve control chamber (45), the second holding valve return spring (42) is disposed in the second holding valve control chamber (45) to be able to hold one end of the second holding valve spool (41) against the second holding valve oil outlet (44) forming a cone seal between the second holding valve oil outlet (44) and the holding valve oil inlet chamber (43), the valve body (1) has formed inside thereof a first holding valve control oil passage (102), a second holding valve control oil passage (104) and a second holding valve oil discharge oil passage (105), the first holding valve control oil passage (102) communicates the first holding valve control chamber (35) with the second holding valve chamber (43), the second holding valve control oil passage (104) communicates the second holding valve control oil outlet (45) with the second holding valve oil outlet (22), and the second holding valve oil discharge oil control oil outlet (105) communicates with the pilot valve (22),

when the main valve element (21) is in the first working position state, the second holding valve oil unloading channel (105) is communicated with the second oil return cavity (209), and when the main valve element is in the second working position or the middle position state, the second holding valve oil unloading channel (105) and the second oil return cavity (209) are blocked by the main valve element (21).

7. The commutating linkage with load holding according to claim 6, characterized in that the holding pilot valve (5) comprises a holding pilot valve spool (51) and a holding pilot valve cavity, the holding pilot valve cavity comprises a pilot valve signal oil cavity (52) communicated with the first control oil port (a), a pilot valve oil inlet cavity (53) communicated with the second holding valve control oil passage (104), and a pilot valve oil discharge cavity (54) communicated with the pilot oil return port (T), and the hydraulic oil of the first control oil port (a) controls the holding pilot valve spool (51) to move in the holding pilot valve cavity to communicate the pilot valve oil inlet cavity (53) with the pilot valve oil discharge cavity (54).

8. A reversing coupling with load retention according to claim 3, characterized in that a non-return valve (8) is arranged between the compensation valve (9) and the main valve (2).

9. The reversing coupling with load holding according to any one of claims 1-8, characterized in that a first overflow valve (6) and a second overflow valve (7) are provided between the first working oil port (A) and the oil return port (T) and between the second working oil port (B) and the oil return port (T), respectively.

10. A hydraulic system comprising a reversing line with load retention according to any one of claims 1-9.

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