Reversing valve

Abstract

The utility model relates to the technical field of hydraulic pressure, in particular to a reversing valve. A reversing valve comprises a valve body, and a pressure oil duct, two working oil ducts and an oil return duct are arranged in the valve body; the valve core is assembled in the valve body in a sliding manner; the load holding valve is arranged aiming at the working oil duct, the load holding valve comprises a load holding cavity, and the load holding cavity is communicated with a valve core through an internal oil duct; the valve element controls connection and disconnection between the oil channels, and when the valve element is located at the middle position, the oil channels are not communicated with one another. When the valve element is located at the two working positions, the valve element controls one working oil duct to be communicated with the pressure oil duct, and the other working oil duct to be communicated with the oil return oil duct. When the valve element is located at the floating position, the valve element controls the two working oil channels, and the inner oil channel is communicated with the oil return channel. The technical problems that in the prior art, a reversing valve cannot give consideration to the load keeping function and the floating function, and use is limited are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulics, and particularly relates to a reversing valve. Background Art

[0002] In the prior art, a reversing valve is often used to control the oil inlet and outlet of an actuator (oil cylinder) so that the actuator can drive a working device to work. During the working process of the actuator, adjustments are often required. For example, when the spool of the reversing valve is in the middle position, due to the gravity of the working device, a certain pressure is generated on the actuator (oil cylinder). This pressure will be transmitted to the main valve through the pipeline. Since there must be a certain gap between the spools of the main valve, it is easy to cause a certain amount of leakage, resulting in the phenomenon of arm dropping. In actual use, the load cannot be maintained, thus affecting normal work. Another example is that for an excavator, it realizes the operation of pushing and leveling the ground through a bulldozing blade, and the bulldozing blade is controlled to rise and fall by the telescopic movement of the bulldozing blade oil cylinder. If the bulldozing blade in the bulldozing blade hydraulic system does not have a floating function, the efficiency is low during the operation of pushing and leveling the ground, and the bulldozing blade is easily damaged.

[0003] In order to solve the problem that the wall is easily dropped when the reversing valve is in the middle position, a document with the application number CN201721407634.4 discloses a load-holding slice-type multi-way valve, which includes a valve body, a spool arranged in the valve body, an oil port A, an oil port B, an oil port P, an oil port T and a TS oil passage located on the valve body. The valve body is provided with a check valve and a B-port safety valve. The valve body also has an eighth oil passage and an eleventh oil passage connected to the check valve. The eighth oil passage is connected to the B-port safety valve. The tenth oil passage and the ninth oil passage are successively connected to the eleventh oil passage. The ninth oil passage is connected to the spool. The spool moves to control the connection or disconnection of the ninth oil passage and the fourth oil passage. When the spool is in the middle position, the check valve, the eighth oil passage, the eleventh oil passage, the tenth oil passage, the ninth oil passage and the B-port safety valve are connected to form a closed cavity, and the pressure oil at the oil port B acts on the check valve to make the check valve reverse and cut off to maintain the load.

[0004] It realizes the function of load holding through a check valve, but it cannot have the floating function at the same time, so there are still limitations in its use. Content of the Utility Model

[0005] In order to solve the technical problem that the reversing valve in the prior art cannot take into account both the load-holding function and the floating function and has limitations in use, the utility model provides a reversing valve to solve the above technical problems.

[0006] In order to solve the above technical problems, the utility model provides a reversing valve, including:

[0007] A valve body, in which a pressure oil passage, two working oil passages and a return oil passage are arranged;

[0008] The spool valve is slidably assembled within the valve body;

[0009] The load holding valve is provided for the working oil passage. The load holding valve includes a load holding chamber, and the load holding chamber is communicated with the spool valve through an internal oil passage;

[0010] The spool valve controls the on-off between the oil passages. When the spool valve is in the middle position, the oil passages are not communicated with each other; when the spool valve is in two working positions, the spool valve controls one working oil passage to be communicated with the pressure oil passage, and the other working oil passage to be communicated with the oil return passage; when the spool valve is in the floating position, the spool valve controls both working oil passages and the internal oil passage to be communicated with the oil return passage.

[0011] According to an embodiment of the present invention, the two working oil passages are respectively a first working oil passage and a second working oil passage. The load holding valve is provided for the first working oil passage, and the spool valve controls the first working oil passage and the load holding chamber to return oil simultaneously.

[0012] According to an embodiment of the present invention, when the spool valve slides along the first axial direction to the first working position, the first working oil passage is supplied with oil, and the second working oil passage returns oil; when the spool valve slides along the second axial direction to the second working position, the second working oil passage is supplied with oil, and the first working oil passage and the load holding chamber return oil; when the spool valve continues to slide along the second axial direction to the floating position, the first working oil passage, the second working oil passage and the load holding chamber are all communicated with the oil return passage.

[0013] According to an embodiment of the present invention, in the floating position, the two working oil passages are directly communicated with the oil return passage through the spool valve.

[0014] According to an embodiment of the present invention, both ends of the oil return passage respectively extend to both sides of the two working oil passages, and the two working oil passages are communicated with the adjacent ends of the oil return passage through the spool valve.

[0015] According to an embodiment of the present invention, in the floating position, one of the working oil passages is communicated with the other working oil passage through the pressure oil passage under the control of the spool valve and then communicated with the oil return passage through the spool valve.

[0016] According to an embodiment of the present invention, the pressure oil passage includes a main oil passage and two branch oil passages that are communicated with each other. The two branch oil passages are located on both sides of the main oil passage. A compensation valve is provided at the connection of the main oil passage and the two branch oil passages. Under the control of the spool valve, one of the working oil passages is communicated with the other working oil passage through the two branch oil passages.

[0017] According to an embodiment of the present utility model, the load holding valve includes a holding valve spool, an elastic member, and a plug. The holding valve spool is slidably assembled in the valve body. The plug closes the installation space where the holding valve spool is located. The elastic member is arranged between the holding valve spool and the plug, and a load holding cavity is formed between the holding valve spool and the plug.

[0018] According to an embodiment of the present utility model, one end of the holding valve spool away from the plug extends into the first working oil passage. An oil passage is formed on the holding valve spool, and the oil passage communicates the first working oil passage and the load holding cavity.

[0019] Based on the above technical solutions, the technical effects that the present utility model can achieve are as follows:

[0020] 1. The directional control valve of the present utility model is provided with a load holding valve, and the spool has a floating position during operation, that is, the multi-way valve has both a load holding function and a floating function. When in the neutral position, the load holding valve can play a role in holding the load of the working oil passage; in the floating position, both working oil passages are communicated with the return oil passage, and the working device can be in the floating position during movement to adapt to uneven ground without being damaged; in addition, the oil drainage of the load holding valve and the control of the floating position are both controlled by the spool, with high structural integration and good cooperation.

[0021] 2. The directional control valve of the present utility model specifically sets the corresponding relationship between the load holding valve and the working oil passage and the spool state, so that when in the neutral position, the load holding valve can play a role in holding the load of the first working oil passage; when the spool controls the first working oil passage to return oil, the spool can control the load holding cavity to return oil without affecting the return oil of the first working oil passage; in the floating position, both working oil passages and the load holding cavity are communicated with the return oil passage to achieve the floating function.

[0022] 3. For the directional control valve of the present utility model, in the floating working position, it can be set that two working oil passages can be directly communicated with the return oil passage through the spool, or it can be set that one working oil passage is communicated with another working oil passage through a pressure oil passage under the control of the spool, and the other working oil passage is then communicated with the return oil passage through the spool. Both setting methods can play a floating function. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the directional control valve according to the first embodiment of the present utility model;

[0024] Figure 2 is Figure 1 The enlarged view of part C in

[0025] Figure 3 is Figure 1 A cross-sectional view at the internal oil passage;

[0026] Figure 4 Structural schematic diagram of the valve core of the first embodiment;

[0027] Figure 5 State diagram of the directional control valve of the first embodiment when in the first working position;

[0028] Figure 6 State diagram of the directional control valve of the first embodiment when in the second working position;

[0029] Figure 7 State diagram of the directional control valve of the first embodiment when in the floating position;

[0030] Figure 8 Hydraulic schematic diagram of the directional control valve;

[0031] Figure 9 Structural schematic diagram of the directional control valve of the second embodiment of the present utility model;

[0032] Figure 10 Structural schematic diagram of the valve core of the second embodiment;

[0033] Figure 11 State diagram of the directional control valve of the second embodiment when in the first working position;

[0034] Figure 12 State diagram of the directional control valve of the second embodiment when in the second working position;

[0035] Figure 13 State diagram of the directional control valve of the second embodiment when in the floating position;

[0036] In the figure: 1 - valve body; 11 - pressure oil passage; 111 - main oil passage; 112 - branch oil passage; 12 - first working oil passage; 13 - second working oil passage; 14 - return oil passage; 15 - internal oil passage; 2 - valve core; 21 - first annular groove; 22 - second annular groove; 23 - third annular groove; 24 - fourth annular groove; 25 - fifth annular groove; 26 - sixth annular groove; 27 - seventh annular groove; 28 - eighth annular groove; 29 - ninth annular groove; 210 - tenth annular groove; 211 - eleventh annular groove; 212 - twelfth annular groove; 3 - load holding valve; 31 - holding valve core; 311 - oil passage; 32 - elastic member; 33 - plug; 34 - load holding cavity; 4 - compensation valve; 5 - actuator; 51 - rodless cavity; 52 - rod cavity. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present utility model and its application or use. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0039] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present utility model. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0040] In the description of the present utility model, it should be understood that the orientation or positional relationships indicated by orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description. Without contrary description, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus should not be construed as limiting the scope of protection of the present utility model; the orientation words "inner, outer" refer to the inside and outside relative to the contour of each component itself.

[0041] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper" etc. can be used here to describe the spatial positional relationship of a device or feature shown in the figure with other devices or features. It should be understood that the spatial relative terms are intended to cover different orientations in use or operation in addition to the orientation described in the figure for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the corresponding explanations are made for the spatial relative descriptions used here.

[0042] In addition, it should be noted that the use of terms such as "first", "second" etc. to define components is only for the convenience of differentiating the corresponding components. Without additional statements, the above terms have no special meanings, and thus cannot be construed as limiting the protection scope of the present utility model.

[0043] Embodiment 1

[0044] As Figure 1-8 shown, this embodiment provides a reversing valve, which includes a valve body 1 and a valve core 2. A pressure oil passage 11, a working oil passage and an oil return passage 14 are arranged in the valve body 1. The valve core 2 is slidably assembled in the valve body 1 to slidably control the on-off of the oil passages.

[0045] An installation hole is formed in the valve body 1 to assemble the valve core 2. The pressure oil passage 11, the working oil passage and the oil return passage 14 are all communicated with the installation hole where the valve core 2 is located, and the valve core 2 slidably controls the on-off of the oil passages.

[0046] Specifically, the pressure oil passage 11 is communicated with a pressure oil port P to introduce pressure oil; there are two working oil passages, namely a first working oil passage 12 and a second working oil passage 13. One end of the first working oil passage 12 is communicated with the installation hole, and the other end extends to the outer surface of the valve body 1 to form a working oil port A. One end of the second working oil passage 13 is communicated with the installation hole, and the other end extends to the outer surface of the valve body 1 to form a working oil port B. The oil return passage 14 is communicated with an oil return port T.

[0047] As a preferred technical solution of this embodiment, the pressure oil passage 11 includes a main oil passage 111 and branch oil passages 112 that communicate with each other. The main oil passage 111 communicates with the pressure oil port P. There are two branch oil passages 112, which are respectively located on both sides of the main oil passage 111, and the two branch oil passages 112 communicate with the mounting holes. The first working oil passage 12 and the second working oil passage 13 are respectively located on both sides of the pressure oil passage 11; both ends of the oil return passage 14 extend to both sides of the first working oil passage 12 and the second working oil passage 13. Preferably, a compensation valve 4 is provided at the connection of the main oil passage 111 and the branch oil passages 112.

[0048] For the working oil passage, a load holding valve 3 is provided so that when the spool 2 is in the middle position, the actuator 5 can achieve load holding. Specifically, the load holding valve 3 is assembled in the valve body 1. The load holding valve 3 includes a holding valve spool 31, an elastic member 32, and a plug 33. The holding valve spool 31 is slidably installed in the valve body 1. The plug 33 seals the installation space where the holding valve spool 31 is located. An elastic member 32 is provided between the holding valve spool 31 and the plug 33. A load holding chamber 34 is formed between the holding valve spool 31 and the plug 33, and the elastic member 32 is located in the load holding chamber 34.

[0049] As a preferred technical solution of this embodiment, the load holding valve 3 is provided for the first working oil passage 12. The end of the holding valve spool 31 of the load holding valve 3 extends into the first working oil passage 12. An oil passage 311 is formed on the holding valve spool 31, and the oil passage 311 communicates the first working oil passage 12 and the load holding chamber 34. When the spool 2 is in the middle position, the oil in the actuator 5 can enter the first working oil passage 12 through the working oil port A, and then enter the load holding chamber 34 through the oil passage 311. Under the action of the elastic member 32 and the oil pressure in the load holding chamber 34, the holding valve spool 31 blocks the first working oil passage 12, and the oil at the working oil port A cannot flow to the mounting hole to leak, thereby achieving load holding.

[0050] As a preferred technical solution of this embodiment, the load holding chamber 34 communicates with the mounting hole through an internal oil passage 15 and communicates with the oil return passage 14 under the control of the spool 2 to achieve oil return. When the actuator 5 needs to return oil through the first working oil passage 12, the spool 2 slides to control both the internal oil passage 15 and the first working oil passage 12 to communicate with the oil return passage 14. The oil in the load holding chamber 34 returns oil, and the oil in the actuator 5 can flow to the first working oil passage 12. The holding valve spool 31 is opened under the action of the oil pressure to overcome the acting force of the elastic member 32, and the first working oil passage 12 can return oil.

[0051] The spool 2 is slidably assembled within the valve body 1 and slidably controls the on-off of the oil passages. When the spool 2 is in the neutral position, the oil passages are not connected to each other; when the spool 2 is in the two working positions, the spool 2 controls one working oil passage to be connected to the pressure oil passage 11, and the other working oil passage to be connected to the return oil passage 14; when the spool 2 is in the floating position, the spool 2 controls both working oil passages and the internal oil passage 15 to be connected to the return oil passage 14.

[0052] As Figure 4 shown, the spool 2 has a rod-like structure, and several annular grooves are distributed on the outer surface of the spool 2. In this embodiment, the outer surface of the spool 2 is provided with a first annular groove 21, a second annular groove 22, a third annular groove 23, a fourth annular groove 24, a fifth annular groove 25 and a sixth annular groove 26. When the spool 2 is in the neutral position, as Figure 1 shown, the oil passages are not connected to each other; when the spool 2 is in the first working position (as Figure 5 shown, the spool 2 slides to the left), the oil distribution passage 112 of the pressure oil passage 11 close to the first working oil passage 12 is connected to the first working oil passage 12 through the sixth annular groove 26, the first working oil passage 12 is filled with oil, the second working oil passage 13 is connected to the return oil passage 14 through the first annular groove 21, the second working oil passage 13 returns oil, and the internal oil passage 15 is blocked by the shoulder on the spool 2 between the fourth annular groove 24 and the fifth annular groove 25; when the spool 2 is in the second working position (as Figure 6 shown, the spool 2 slides to the right), the oil distribution passage 112 of the pressure oil passage 11 close to the second working oil passage 13 is connected to the second working oil passage 13 through the first annular groove 21, the second working oil passage 13 is filled with oil, the first working oil passage 12 is connected to the return oil passage 14 through the sixth annular groove 26, the first working oil passage 12 returns oil, the internal oil passage 15 is connected to the return oil passage 14 through the fourth annular groove 24, and the load holding cavity 34 is in a low-pressure state.

[0053] As a preferred technical solution of this embodiment, in the floating position, after one working oil passage is connected to the other working oil passage through the pressure oil passage 11 under the control of the spool 2, it is then connected to the return oil passage 14 through the spool 2. As Figure 7 shown, on the basis of the second working position, the spool 2 continues to slide to the right to the floating position. The second working oil passage 13 is connected to the oil distribution passage 112 through the first annular groove 21 of the spool 2, the oil distribution passage 112 is then connected to the first working oil passage 12 through the fifth annular groove 25, and the first working oil passage 12 is connected to the return oil passage 14 through the sixth annular groove 26. At this time, the internal oil passage 15 is connected to the return oil passage 14 through the fourth annular groove 24, and the load holding cavity 34 is in a low-pressure state.

[0054] The working oil port A and the working oil port B are connected to an actuator 5, and the actuator 5 can be set as an oil cylinder, including a rodless chamber 51 and a rod chamber 52. The rodless chamber 51 is connected to the working oil port A, and the rod chamber 52 is connected to the working oil port B. In addition, according to the specific working conditions, the rodless chamber 51 can also be connected to the working oil port B, and the rod chamber 52 can be connected to the working oil port A.

[0055] The hydraulic principle of the directional valve in this embodiment is as follows: The directional valve can be set as a four-position nine-way valve. When the directional valve is in the neutral position, none of the oil passages are connected; when the directional valve is in the first working position, it can control the pressure oil to enter the rodless chamber 51 through the first working oil passage 12, and the rod chamber 52 returns oil to the return oil passage 14 through the second working oil passage 13, and the cylinder rod of the actuator 5 extends; when the directional valve is in the second working position, it can control the pressure oil to enter the rod chamber 52 through the second working oil passage 13, the load holding chamber 34 is connected to the return oil passage 14 through the internal oil passage 15 for oil return, and the oil in the rodless chamber 51 returns to the return oil passage 14 through the first working oil passage 12, and the cylinder rod of the actuator 5 retracts; when the directional valve is in the floating position, it can control the rodless chamber 51, the rod chamber 52 and the load holding chamber 34 of the actuator 5 to be all connected to the return oil passage 14, and the working device controlled by the actuator 5 can adapt to the uneven ground.

[0056] Embodiment 2

[0057] As Figure 9-13 shown, this embodiment is basically the same as Embodiment 1, except that the setting of the spool 2 is slightly different from that of Embodiment 1, so that when the directional valve is in the floating position, both the first working oil passage 12 and the second working oil passage 13 are directly connected to the return oil passage 14 through the spool 2.

[0058] Specifically, the spool 2 is provided with a seventh annular groove 27, an eighth annular groove 28, a ninth annular groove 29, a tenth annular groove 210, an eleventh annular groove 211 and a twelfth annular groove 212, and the axial length of the annular groove and the axial spacing between the annular grooves are different from those of Embodiment 1.

[0059] As Figure 9 shown, when the spool 2 is in the neutral position, none of the oil passages are connected.

[0060] As Figure 11 shown, when the spool 2 is in the first working position, the oil branch passage 112 of the pressure oil passage 11 close to the first working oil passage 12 is connected to the first working oil passage 12 through the twelfth annular groove 212, the first working oil passage 12 admits oil, the second working oil passage 13 is connected to the return oil passage 14 through the eighth annular groove 28, the second working oil passage 13 returns oil, and the internal oil passage 15 is blocked by the shoulder on the spool 2 between the eleventh annular groove 211 and the twelfth annular groove 212.

[0061] As Figure 12As shown, when the valve core 2 is in the second working position, the oil distribution channel 112 of the pressure oil channel 11 close to the second working oil channel 13 is communicated with the second working oil channel 13 through the eighth ring groove 28, the second working oil channel 13 is supplied with oil, the first working oil channel 12 is communicated with the oil return channel 14 through the twelfth ring groove 212, the first working oil channel 12 returns oil, the internal oil channel 15 is communicated with the oil return channel 14 through the eleventh ring groove 211, and the load holding cavity 34 is in a low-pressure state.

[0062] As Figure 13 shown, in the floating position, the valve core 2 continues to slide to the right to the floating position on the basis of the second working position, the second working oil channel 13 is directly communicated with the oil return channel 14 through the seventh ring groove 27 of the valve core 2, and the first working oil channel 12 is communicated with the oil return channel 14 through the twelfth ring groove 212. At this time, the internal oil channel 15 is communicated with the oil return channel 14 through the eleventh ring groove 211, and the load holding cavity 34 is in a low-pressure state.

[0063] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A reversing valve, characterized in that: include: A valve body (1), wherein a pressure oil passage (11), two working oil passages and an oil return passage (14) are arranged in the valve body (1); A valve core (2) is slidably assembled in the valve body (1); A load holding valve (3) is arranged for the working oil passage, the load holding valve (3) comprising a load holding chamber (34), the load holding chamber (34) being in communication with the valve core (2) via an internal oil passage (15); The valve core (2) controls the on-off of the oil passages. When the valve core (2) is in the middle position, the oil passages are not connected to each other. When the valve core (2) is in two working positions, the valve core (2) controls one working oil passage to be connected to the pressure oil passage (11), and the other working oil passage to be connected to the return oil passage (14). When the valve core (2) is in the floating position, the valve core (2) controls the two working oil passages and the internal oil passage (15) to be connected to the return oil passage (14).

2. A reversing valve according to claim 1, characterized in that: The two working oil passages are respectively a first working oil passage (12) and a second working oil passage (13); the load holding valve (3) is arranged for the first working oil passage (12); and the valve core (2) controls the first working oil passage (12) and the load holding chamber (34) to return oil simultaneously.

3. A reversing valve according to claim 2, characterized in that: When the valve core (2) slides along the first axial direction to the first working position, the first working oil passage (12) is supplied with oil, and the second working oil passage (13) is supplied with oil; when the valve core (2) slides along the second axial direction to the second working position, the second working oil passage (13) is supplied with oil, and the first working oil passage (12) and the load holding chamber (34) are supplied with oil; when the valve core (2) continues to slide along the second axial direction to the floating position, the first working oil passage (12), the second working oil passage (13) and the load holding chamber (34) are all connected to the return oil passage (14).

4. A reversing valve according to any one of claims 1 to 3, characterized in that: When in the floating position, the two working oil passages are directly connected to the oil return passage (14) via the valve core (2).

5. A reversing valve according to claim 4, characterized in that: The two ends of the oil return passage (14) extend to the two sides of the two working oil passages respectively, and the two working oil passages are connected to the ends of the adjacent oil return passages (14) through the valve core (2).

6. A reversing valve according to any one of claims 1 to 3, characterized in that: When in the floating position, one of the working oil passages is connected to another working oil passage through the pressure oil passage (11) under the control of the valve core (2), and then connected to the oil return passage (14) through the valve core (2).

7. A reversing valve according to claim 6, characterized in that: The pressure oil passage (11) comprises a main oil passage (111) and two branch oil passages (112) which are interconnected. The two branch oil passages (112) are located on both sides of the main oil passage (111). A compensation valve is provided at the connection between the main oil passage (111) and the two branch oil passages (112). Under the control of the valve core (2), one of the working oil passages is connected to the other working oil passage through the two branch oil passages (112).

8. A reversing valve according to claim 2, characterized in that: The load holding valve (3) comprises a holding valve core (31), an elastic member (32) and a plug (33); the holding valve core (31) is slidably assembled in the valve body (1); the plug (33) closes the installation space where the holding valve core (31) is located; the elastic member (32) is arranged between the holding valve core (31) and the plug (33); and the load holding chamber (34) is formed between the holding valve core (31) and the plug (33).

9. A reversing valve according to claim 8, characterized in that: One end of the holding valve core (31) away from the plug (33) extends into the first working oil passage (12), and an oil passage (311) is formed on the holding valve core (31), wherein the oil passage (311) communicates with the first working oil passage (12) and the load holding chamber (34).

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