High-low pressure switching valve, pumping control valve group and pumping hydraulic system

Abstract

The invention belongs to the field of pumping control, and discloses a high-low pressure switching valve, a pumping control valve set and a pumping hydraulic system. The high-low pressure switching valve comprises a switching valve body and a switching valve rod, a switching valve rod cavity is formed in the switching valve body in the axial direction, the valve wall of the switching valve body is provided with a plurality of first side oil ports, a plurality of second side oil ports and a supplementing and draining oil cavity, the first side oil ports, the second side oil ports and the supplementing and draining oil cavity extend to the switching valve rod cavity, and the second side oil ports comprise a rod cavity connecting oil port set and a rodless cavity oil port set. The switching valve rod is arranged in the switching valve rod cavity in a sliding mode and used for controlling the first side oil ports to be selectively communicated with the rod cavity connecting oil port set or the rodless cavity oil port set according to the moving stroke of the valve rod, and the switching valve rod is internally provided with a valve rod oil supplementing and draining flow channel communicating with the oil supplementing and draining cavity and the second side oil ports. According to the high-low pressure switching valve, the high-low pressure pumping mode can be achieved with the simple structure and the low cost, the working condition adaptability is improved, the oil supplementing and discharging function can be integrated, and an external pipeline is not needed.

Description

Technical Field

[0001] The present application belongs to the field of pumping control, and in particular, relates to a high-low pressure switching valve, a pumping control valve group and a pumping hydraulic system. Background Art

[0002] When the hydraulic drive pumping cylinder group is in operation, if the high-pressure oil is connected to the rod chamber, it is a low-pressure drive mode, and the rodless chambers are connected to each other as passive chambers. Conversely, if the high-pressure oil is connected to the rodless chamber, it is a high-pressure drive mode, and the rod chambers are connected to each other as passive chambers. Therefore, the pumping control valve group should generally include a high-low pressure switching valve to improve the adaptability of working conditions.

[0003] In the prior art, there are designs of respective valve group structures to realize high and low pressure switching. For example, in Chinese patent application CN210461217U, a combination of a two-position six-way slide valve and a cartridge valve is used to realize high and low pressure switching. The two-position six-way slide valve is responsible for the oil chamber connection function in one state. When it is necessary to operate in a high-pressure or low-pressure state, one oil chamber (rod chamber or rodless chamber) of the two oil cylinders can be directly connected through the two-position six-way slide valve. However, the two-position six-way valve and two logic valves realize two high and low pressure pumping modes, which are complex in structure, difficult to process, and high in cost.

[0004] In addition, the pumping cylinder will inevitably leak oil during long-term operation or static operation, which will shorten the cylinder stroke. Therefore, it is necessary to control the oil replenishment or oil leakage. At this time, the replenishment and leakage of oil requires external pipes, the valves are dispersed, and the system pipeline connection cost is increased. Summary of the invention

[0005] In response to the above-mentioned defects or shortcomings, the present application discloses a high-low pressure switching valve, a pumping control valve group and a pumping hydraulic system, which realize high-low pressure pumping and oil replenishment and unloading functions with a simple structure and low cost, and improve the adaptability to working conditions.

[0006] To achieve the above object, according to a first aspect of the present application, a high-low pressure switching valve is disclosed for high-low pressure switching control of a pumping cylinder group, the high-low pressure switching valve comprising: A switching valve body, wherein an axial switching valve stem cavity is provided therein, a plurality of first side oil ports and a plurality of second side oil ports extending to the switching valve stem cavity are provided on a valve wall of the switching valve body, the plurality of second side oil ports comprising a rod cavity connecting oil port group for connecting to the rod cavity of the oil cylinder of the pumping oil cylinder group and a rodless cavity oil port group for connecting to the rodless cavity of the oil cylinder; A switching valve stem is slidably disposed in the switching valve stem cavity and is used to control the plurality of first side oil ports to selectively connect to the rod cavity connecting oil port group or to connect to the rodless cavity oil port group according to the valve stem movement stroke; The valve wall of the switching valve body is also provided with a drain oil chamber extending to the switching valve stem chamber, and the switching valve stem is also provided with a stem drain oil flow channel, and the stem drain oil flow channel is used to connect the drain oil chamber with the second side oil port.

[0007] In some embodiments, in the switching valve stem chamber, the plurality of first side oil ports are arranged axially in the middle and spaced apart, one of the rod chamber connecting oil port group and the rodless chamber oil port group is arranged between the plurality of first side oil ports, and the other is symmetrically arranged axially outside the plurality of first side oil ports; Among them, at the axial end of the switching valve stem cavity, an end connecting cavity extending to the switching valve stem cavity is also provided on the valve wall of the switching valve body, and the end connecting cavity is used to connect each oil port in the axial outer oil port group when multiple first side oil ports are connected to the axial inner oil port group of the first side oil port.

[0008] In some embodiments, the first side oil port includes a first oil port and a second oil port, the rod cavity connecting oil port group includes a first rod cavity connecting oil port and a second rod cavity connecting oil port, and the rodless cavity connecting oil port group includes a first rodless cavity connecting oil port and a second rodless cavity connecting oil port; Among them, the rod chamber connecting oil port group is the axial outer oil port group, the end connecting chamber and one of the first rod chamber connecting oil port and the second rod chamber connecting oil port are arranged at the same axial end of the switching valve stem chamber with an oil port interval, and remain connected with the other of the first rod chamber connecting oil port and the second rod chamber connecting oil port.

[0009] In some embodiments, the switching valve stem comprises: An inner oil port communication groove arranged in the center and outer oil port communication grooves arranged at intervals on the axial outside of the inner oil port communication groove; The end communicating groove is used for controlling the communication between the end communicating cavity and the oil ports in the adjacent axial outer oil port group.

[0010] In some embodiments, one end of the valve stem drain oil flow channel extends to communicate with the inner oil port connecting groove, and the other end extends axially outward to the outside of the outer oil port connecting groove and is used to communicate with the drain oil chamber.

[0011] In some embodiments, the drain oil chamber and the end connecting groove are distributed at two axial ends of the switching valve stem chamber.

[0012] In some embodiments, the high-low pressure switching valve is further integrated with an oil replenishment and drain valve, and an oil replenishment outlet of the oil replenishment and drain valve is connected to the oil replenishment and drain chamber.

[0013] In some embodiments, the oil replenishment and discharge valve is integrally cast on the switching valve body.

[0014] According to the second aspect of the present application, a pumping control valve group is disclosed, which includes a reversing valve group for controlling the pumping cylinder group and the above-mentioned high and low pressure switching valve, and multiple first side oil ports are connected to the working oil port of the reversing valve group.

[0015] According to a third aspect of the present application, a pumping hydraulic system is also disclosed, and the pumping hydraulic system includes the above-mentioned pumping control valve group.

[0016] In the high-low pressure switching valve, pumping control valve group and pumping hydraulic system of the present application, two high and low pressure pumping modes are realized by a single valve structure, that is, by switching the valve stem, multiple first side oil ports are selectively connected to the rod chamber connecting oil port group to realize the low pressure pumping mode; or by switching the valve stem, multiple first side oil ports are selectively connected to the rodless chamber connecting oil port group to realize the high pressure pumping mode. Compared with the prior art that realizes the high and low pressure pumping switching mode by multiple valve parts, the product structure is greatly simplified, the integration is high, and the processing difficulty and cost are reduced. In addition, a supplementary oil chamber can be integrated and designed, and a valve stem supplementary oil flow channel is also provided in the switching valve stem to connect the supplementary oil chamber with the second side oil port. The supplementary oil chamber can be connected to the low pressure side of the rod chamber or the rodless chamber of the oil cylinder through the second side oil port to supply oil to the pumping oil cylinder in time or for the return of the oil in the oil cylinder. By integrating the supplementary oil function, the product integration can be improved and the system pipeline connection cost can be reduced.

[0017] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide an understanding of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present application but do not constitute a limitation to the present application. In the accompanying drawings: Figure 1 It is a structural schematic diagram of a reversing valve group according to a specific embodiment of the present application; Figure 2 for Figure 1 A schematic diagram of the structure of the reversing valve body in the reversing valve group shown; Figure 3 for Figure 1 A schematic diagram of the structure of a reversing valve stem in a reversing valve group shown; Figure 4 It is a structural schematic diagram of a high-low pressure switching valve according to a specific embodiment of the present application; Figure 5 for Figure 4 A schematic structural diagram of a switching valve body in a high-low pressure switching valve is shown; Figure 6 for Figure 4A schematic diagram of the structure of a switching valve stem in a high-low pressure switching valve shown; Figure 7 It is a hydraulic principle diagram of a pumping hydraulic system according to a specific embodiment of the present application.

[0019] Description of Reference Numerals DETAILED DESCRIPTION

[0020] The specific embodiments of the present application are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0021] The reversing valve group and the pumping hydraulic system according to the present application are described below with reference to the accompanying drawings.

[0022] The present application discloses a novel high-low pressure switching valve for high-low pressure switching control of a pumping cylinder group. Figures 4 to 6 As shown, in a specific embodiment, the high-low pressure switching valve 400 includes: A switching valve body 4 is provided with a switching valve stem cavity 5 along the axial direction, and a plurality of first side oil ports and a plurality of second side oil ports extending to the switching valve stem cavity 5 are provided on the valve wall of the switching valve body 4, and the plurality of second side oil ports include a rod cavity connecting oil port group for connecting to the rod cavity of the oil cylinder of the pumping oil cylinder group and a rodless cavity oil port group for connecting to the rodless cavity of the oil cylinder; The switching valve stem 6 is slidably disposed in the switching valve stem cavity 5 and is used to control the multiple first side oil ports to selectively connect to the rod cavity connecting oil port group or the rodless cavity oil port group according to the valve stem movement stroke.

[0023] Among them, the pumping cylinder group may leak oil during operation or during non-operation, resulting in a shortened cylinder stroke. To this end, the high-low pressure switching valve 400 of this embodiment may also be integrated with a drain oil chamber 7 to supply oil to the pumping cylinder in a timely manner or to return the oil to the cylinder. Figure 5 The valve wall of the switching valve body 4 is also provided with a supplementary oil chamber 7 extending to the switching valve stem chamber 5; see Figure 6 A valve stem supplementary oil flow channel 64 is also provided in the switching valve stem 6, and the valve stem supplementary oil flow channel 64 is used to connect the supplementary oil chamber 7 with the second side oil port. The supplementary oil chamber 7 can be connected to the low-pressure side of the rod chamber or rodless chamber of the oil cylinder through the second side oil port. By integrating the supplementary oil function, the product integration can be improved and the system pipeline connection cost can be reduced.

[0024] Since the supplementary oil chamber 7 needs to be connected to the low-pressure side of the oil chamber of the oil cylinder to facilitate oil replenishment or pressure relief, as mentioned above, when the switching valve stem 6 moves to the left valve position, the rod chambers of the two oil cylinders of the pumping oil cylinder group are connected and are in the low-pressure pumping mode. At this time, the supplementary oil chamber 7 should be connected to the first rodless chamber connecting oil port A2 and the second rodless chamber connecting oil port B2. Similarly, when the switching valve stem 6 moves to the right valve position, the supplementary oil chamber 7 should be connected to the first rod chamber connecting oil port A1 and the second rod chamber connecting oil port B1.

[0025] To this end, Figure 6 A valve stem supplementary oil flow channel 64 is provided in the switching valve stem 6, one end of the valve stem supplementary oil flow channel 64 is connected to the inner oil port communication groove 61, and the other end is located outside the outer oil port communication groove 62 for connecting to the supplementary oil chamber 7. In other words, one end of the valve stem supplementary oil flow channel 64 extends to connect to the inner oil port communication groove 61, and the other end extends axially outward to the outside of the outer oil port communication groove 62 and is used to connect to the supplementary oil chamber 7.

[0026] In this embodiment, the drain oil chamber 7 and the end connecting groove C can be distributed at both axial ends of the switching valve stem chamber 5, so that the valve body structure can be designed to be smaller and more compact.

[0027] The new high-low pressure switching valve of the present application realizes two high-pressure and low-pressure pumping modes through a single valve body structure, that is, by switching the valve stem 6, multiple first side oil ports are selectively connected to the rod chamber connecting oil port group to realize the low-pressure pumping mode; similarly, by switching the valve stem 6, multiple first side oil ports are selectively connected to the rodless chamber connecting oil port group to realize the high-pressure pumping mode. In this way, compared with the prior art that realizes the high-low pressure pumping switching mode through multiple valve parts, the product structure is greatly simplified, the integration is high, and the processing difficulty and cost are reduced. In addition, a supplementary oil chamber is also integrated, and a valve stem supplementary oil flow channel is also provided in the switching valve stem to connect the supplementary oil chamber with the second side oil port. The supplementary oil chamber can be connected to the low-pressure side in the rod chamber or rodless chamber of the oil cylinder through the second side oil port to supply oil to the pumping oil cylinder in time or for the return of the oil in the oil cylinder. By integrating the supplementary oil function, the product integration can be improved and the system pipeline connection cost can be reduced.

[0028] To switch between high and low pressure pumping modes on a single valve body, refer to Figure 5 In the switching valve stem chamber 5 shown, a plurality of first side oil ports are arranged axially in the middle and spaced apart, one of the rod chamber connecting oil port group and the rodless chamber oil port group is arranged between the plurality of first side oil ports, and the other is symmetrically arranged axially outside the plurality of first side oil ports; Among them, at the axial end of the switching valve stem cavity 5, an end connecting cavity C extending to the switching valve stem cavity 5 is also provided on the valve wall of the switching valve body 4, and the end connecting cavity C is used to connect each oil port in the axial outer oil port group when multiple first side oil ports are connected to the axial inner oil port group of the first side oil port.

[0029] It should be noted that the directional words "inside" and "outside" here are based on Figure 5 The center of the switching valve stem chamber 5 shown in the figure is used as a reference. In this embodiment, firstly, a plurality of first side oil ports (including Figure 5 The first oil port A' and the second oil port B' shown in the figure are arranged in the center at intervals, and on this basis, the rodless chamber oil port group (including the first rodless chamber connecting oil port A2 and the second rodless chamber connecting oil port B2) are arranged at intervals between the multiple first side oil ports, located on the inner side of the first side oil port, while the rod chamber connecting oil port group (including the first rod chamber connecting oil port A1 and the second rod chamber connecting oil port B1) are arranged at intervals on the outer side of the first side oil port. In this way, when the first side oil port is connected to the rodless chamber oil port group by switching the valve stem 6, the various oil ports of the rod chamber connecting oil port group are interconnected, so that the rod chambers of the two cylinders of the pumping cylinder group are connected. Similarly, when the first side oil port is connected to the rod chamber oil port group by switching the valve stem 6, the various oil ports of the rodless chamber connecting oil port group are interconnected, so that the rodless chambers of the two cylinders of the pumping cylinder group are connected. Of course, the distribution of the various oil ports of the present application is not limited to Figure 5 As shown, for example, the rodless cavity connecting oil port group may be arranged on the outside of the first side oil port, while the rod cavity connecting oil port group may be arranged on the inside of the first side oil port.

[0030] As described above, when the switching valve stem 6 is moved to switch the valve position so that the first side oil port is connected to the rod chamber connecting oil port group or the rodless chamber oil port group located on the inner side of the first side oil port, the oil ports in the rodless chamber connecting oil port group or the rod chamber oil port group located on the outer side of the first side oil port need to be connected, but Figure 5 In the oil port distribution shown, it is obviously difficult to achieve by switching the connecting groove design or the hollow connecting tube cavity design on the valve stem 6, and the structure is complicated. For this reason, an end connecting cavity C is added, and the end connecting cavity C is used to connect the various oil ports in the axial outer oil port group when the multiple first side oil ports are connected to the axial inner oil port group of the first side oil port. In other words, the end connecting cavity C is used to connect the various oil ports outside the first side oil port. For example, Figure 5 The end connecting chamber C shown is an extended connecting chamber of the second rod chamber connecting oil port B1, which is arranged close to the first rod chamber connecting oil port A1, so that when the movement position of the switching valve stem 6 is not large, the second rod chamber connecting oil port B1 can be connected with the first rod chamber connecting oil port A1 through the end connecting chamber C.

[0031] In the present embodiment, as an example, the high-low pressure switching valve has 6 oil ports, namely, the first side oil port includes the first oil port A' and the second oil port B', the rod chamber connecting oil port group includes the first rod chamber connecting oil port A1 and the second rod chamber connecting oil port B1, and the rodless chamber connecting oil port group includes the first rodless chamber connecting oil port A2 and the second rodless chamber connecting oil port B2; wherein, the rod chamber connecting oil port group is an axially outer oil port group, and the end connecting chamber C is arranged at the same axial end of the switching valve stem chamber 5 with one of the first rod chamber connecting oil port A1 and the second rod chamber connecting oil port B1 at an oil port interval, and remains connected with the other of the first rod chamber connecting oil port A1 and the second rod chamber connecting oil port B1.

[0032] Based on the above oil port distribution, see Figure 6 , the switching valve stem 6 may also include: The inner oil port communication groove 61 is arranged in the center and the outer oil port communication groove 62 is arranged at intervals on the axial outside of the inner oil port communication groove 61; The end communicating groove 63 is used to control the communication between the end communicating cavity C and the oil ports in the adjacent axial outer oil port group.

[0033] See also Figure 4 , Figure 7 When the switching valve stem 6 moves to the left valve position, the first oil port A' is connected to the first rod cavity connecting oil port A1 through the outer oil port connecting groove 62 at the left end, and the second oil port B' is connected to the second rod cavity connecting oil port B1 through the outer oil port connecting groove 62 at the right end; at the same time, the first rodless cavity connecting oil port A2 and the second rodless cavity connecting oil port B2 are connected through the inner oil port connecting groove 61, see Figure 7 At this time, the rod chambers of the two cylinders of the pumping cylinder group are connected and are in low-pressure pumping mode.

[0034] When the switching valve stem 6 moves to the right valve position, at this time, the first oil port A' is connected to the first rodless cavity connecting oil port A2 through the outer oil port connecting groove 62 at the left end, and the second oil port B' is connected to the second rodless cavity connecting oil port B2 through the inner oil port connecting groove 61, and the first rod cavity connecting oil port A1 and the second rod cavity connecting oil port B1 are connected. Figure 7 At this time, the rodless chambers of the two cylinders of the pumping cylinder group are connected and are in high-pressure pumping mode.

[0035] After the supplementary oil-drain chamber 7 is provided, an external supplementary oil-drain control valve can be connected. In the present embodiment, the high-low pressure switching valve 400 is also integrated with a supplementary oil-drain valve 500, and the supplementary oil outlet of the supplementary oil-drain valve 500 is connected to the supplementary oil-drain chamber 7. In this way, the high-low pressure switching valve can not only realize the high-low pressure pumping switching function, but also has the supplementary oil-drain function. Compared with the external supplementary oil control valve method which requires external piping and has a low degree of integration, the high-low pressure switching valve of the present application does not require external piping and does not need to increase the system pipeline connection cost. In actual manufacturing, the high-low pressure switching valve can be cast as an integral part, that is, the supplementary oil-drain valve 500 can be cast integrally on the switching valve body 4.

[0036] Those skilled in the art will understand that the oil replenishment and draining function is mainly to control the stroke of the pumping cylinder. A piston stroke detection element may be provided in the pumping cylinder group. When it is detected that the cylinder stroke in the pumping cylinder group is insufficient, the piston stroke detection element may be provided. Figure 7 , the end electromagnet DT4 of the oil-supply valve 500 can be controlled to be energized, and oil can be injected into the oil-supply chamber 7 and its cylinder connecting chamber, so that the pumping cylinder stroke increases; when it is detected that the cylinder stroke is too long, the end electromagnet DT3 can be controlled to be energized, so that the cylinder connecting chamber of the oil-supply chamber 7 is depressurized, and the oil in the cylinder chamber is partially returned, thereby shortening the pumping cylinder stroke.

[0037] The present application also discloses a pumping control valve group, comprising a reversing valve group (see below) for controlling a pumping oil cylinder group and a high-low pressure switching valve, wherein a plurality of first side oil ports of the high-low pressure switching valve are connected to a working oil port of the reversing valve group. Figure 7 , that is, the first oil port A' is connected to the second working oil chamber A, and the second oil port B' is connected to the first working oil chamber B. This pumping control valve group has high integration, simple valve body structure, small hydraulic shock during switching control, can realize high and low pressure pumping modes, and integrated supplementary oil valve, which can control the switching of high and low pressure modes by controlling the connection between the working oil port and the supplementary oil chamber, and can also play the role of supplementary oil.

[0038] Correspondingly, the present application also discloses a pumping hydraulic system, including a pumping control valve group according to the present application. After adopting this highly integrated pumping control valve group, only two basic valve groups are provided between the pumping cylinder group and the oil pump or the main oil circuit of the system, and the control function is perfect, the control operation is smooth, and the cost is low.

[0039] In addition, the present application also discloses a novel reversing valve group. Figures 1 to 3 In a specific embodiment, the reversing valve group includes an integrated reversing valve 100 and a unloading valve 200, the reversing valve 100 is a sliding valve and the reversing valve stem 1 is used to control the unloading valve 200 to switch to an unloading closed state at the end stroke position of the valve stem and to switch to an unloading open state at the midpoint stroke position of the valve stem.

[0040] The present application aims to integrate the unloading valve 200 into the reversing valve 100, and use the stroke of the reversing valve stem 1 to control the opening or closing of the unloading valve 200 to avoid pressure shock. When the reversing valve stem 1 is at the midpoint stroke position of the valve stem, the unloading valve 200 is controlled to be in the unloading open state, that is, the hydraulic control chamber of the unloading valve 200 returns oil, and at this time, the high-pressure oil at the P port will be unloaded through the unloading valve 200 at a large flow rate. Before the reversing valve stem 1 moves to the working position (such as the valve stem end stroke position in this embodiment), the high-pressure oil at the P port can be at least partially unloaded through the unloading valve 200, and the high-pressure oil will not cause oil blockage or pressure shock at the P port. Alternatively, when the reversing valve stem 1 moves to a position close to the midpoint of the valve stem, the unloading valve 200 will switch from the unloading closed state to the unloading open state, and the high-pressure oil at the P port will be unloaded through the unloading valve 200, rather than suddenly released to the T port or the oil return channel. In addition, since the pressure release of the hydraulic control chamber of the unloading valve 200 is gradual, the high-pressure oil at the P port will not be suddenly released to the T port or the oil return channel. Therefore, during the pumping reversing process, the unloading valve opening speed can be limited by the reversing valve stem 1, which can greatly reduce the instantaneous pressure impact of the main pump high-pressure oil on the T port, avoiding radiator damage and other faults.

[0041] Comparably, in the Chinese patent application CN210461217U, for example, the large flow slide valve used is of M-type function. When in the middle position, the P port is connected to the T port through the valve stem to achieve middle position unloading; in the reversing position, the valve stem disconnects the P port and the T port, and the pumping works normally. However, when the valve stem is used for unloading in the middle position M function, the high-pressure oil is suddenly released to the oil return channel during unloading, and the pressure shock in the oil return channel is large, which is easy to damage the radiator and other components. In the Chinese patent application CN112096683A, for example, the valve stem is of O-type function and cannot be unloaded. A solenoid unloading valve is specially added to unload. However, in winter, at low temperatures, the reversing of the large flow slide valve will slow down. It often happens that after the solenoid unloading valve is closed, the large flow slide valve has not yet been reversed to the right position and is still in the O-type function position. At this time, the P port is a closed cavity, which produces a pressure shock. The pressure shock of the P port will cause the engine to drop in speed or stall. To this end, the energized closing delay time of the electromagnetic unloading valve can be increased to avoid pressure shock at the pumping oil port of the main pump, but this also reduces the pumping efficiency and reduces product reliability due to the addition of the electromagnetic unloading valve.

[0042] In order to realize the integration of the reversing valve and the unloading valve and avoid oil shock, as an example, the reversing valve 100 of this embodiment may include: The reversing valve body 2 is provided with a reversing valve stem chamber 3 in the axial direction and an oil inlet chamber P, an oil return chamber T and a working oil chamber extending to the reversing valve stem chamber 3; and The reversing valve stem 1 is slidably arranged in the reversing valve stem cavity 3, and a valve stem inner flow channel is arranged in the reversing valve stem 1; Among them, the unloading valve 200 is installed on the valve wall of the reversing valve body 2, and the hydraulic control chamber of the unloading valve 200 (that is, the spring chamber of the unloading valve 200 shown in the figure) extends to the reversing valve stem chamber 3 through the flow channel in the valve wall; at the end stroke position of the valve stem, the flow channel in the valve wall is aligned to connect the flow channel in the valve stem with the oil inlet chamber P, and at the midpoint stroke position of the valve stem, the flow channel in the valve wall can be connected to the oil return chamber T.

[0043] It can be seen that, through the setting of the flow channel in the valve wall of the hydraulic control chamber of the unloading valve 200, the flow channel in the valve stem of the reversing valve stem 1 and their position distribution in the reversing valve body 2, it is possible to use the stroke of the reversing valve stem 1 to control the opening or closing of the unloading valve 200, that is, the unloading valve 200 can be switched to the unloading closed state at the end stroke position of the valve stem and can be switched to the unloading open state at the midpoint stroke position of the valve stem. Therefore, compared with the method of using the unloading solenoid valve alone, the unloading solenoid valve can be eliminated, and the unloading valve can be opened or closed by controlling the reversing valve stem.

[0044] Among them, at the midpoint stroke position of the valve stem, in order to enable the flow channel in the valve wall to connect to the oil return chamber T, Figure 3 The reversing valve stem 1 shown may include a shift groove 12, which is used to connect the flow channel in the valve wall to the oil return chamber T at the midpoint stroke position of the valve stem. Figure 1 In addition, the reversing valve stem 1 may further include a conducting groove 11, and the conducting groove 11 is used to control the working oil chamber to selectively connect to the oil inlet chamber P or the oil return chamber T, which will be described in detail below.

[0045] See also Figure 1 At this time, the reversing valve stem 1 is at the mid-point stroke position of the valve stem, and the oil in the hydraulic control chamber of the unloading valve 200 is connected to the return oil inner flow channel L and the return oil chamber T through the flow channel in the valve wall and the gear groove 12. While the pressure in the hydraulic control chamber gradually decreases, the pressure oil at the P port will gradually open the valve port of the unloading valve 200, so that the oil inlet chamber P is connected to the return oil chamber T, thereby directly unloading and returning the oil. This can avoid the problem of pressure shock caused by the sudden direct connection between the oil inlet chamber P and the return oil chamber T when the valve stem is at the mid-point stroke position. In other words, at the mid-point stroke position of the valve stem, since the unloading of the unloading valve spring chamber requires time, a delay time is also required between the P and T ports before the unloading can be opened, that is, no pressure shock will be generated at the T port.

[0046] Since at the midpoint stroke position of the valve stem, the pressure oil at port P will be unloaded and returned by opening the unloading valve 200, the reversing valve 100 itself can adopt a three-position four-way valve with an O-type mid-position function. The three-position four-way valve with an O-type mid-position function is relatively conventional, with a simple structure and low cost.

[0047] In this embodiment, in order to achieve large flow unloading and avoid pressure shock, the oil inlet chamber P or the oil return chamber T uses a relatively large cross-sectional channel. At the same time, the flow channel in the valve stem and the flow channel in the valve wall are used to establish or release the oil pressure in the hydraulic control chamber of the unloading valve 200, so a relatively small cross-sectional channel is used to play a delay or damping role. As an example, the flow cross-sectional area of ​​the flow channel in the valve stem and the flow channel in the valve wall should not be greater than 1 / 5 of the minimum flow cross-sectional area of ​​the oil inlet chamber P or the oil return chamber T.

[0048] On the basis of realizing the above-mentioned reversing and unloading functions, in order to achieve the purpose of simple arrangement of each oil channel and chamber, see Figure 2 , on the reversing valve body 2, the unloading valve 200 is centrally arranged and radially distributed, the oil inlet chamber P extends to the valve port end of the reversing valve body 2, the working oil chamber includes a first working oil chamber B and a second working oil chamber A which are arranged on both axial sides of the oil inlet chamber P, and the return oil chamber T is located on the first axial side of the oil inlet chamber P and is spaced apart on the axial outside of the first working oil chamber B; wherein, the return oil chamber T is connected to the valve port end of the reversing valve body 2 through the return oil inner flow channel L, and the return oil inner flow channel L extends to the second axial side of the oil inlet chamber P and is spaced apart on the axial outside of the second working oil chamber A. It can be seen that in this reversing valve 100, when the reversing valve stem 1 moves to the middle position, it is the above-mentioned valve stem midpoint stroke position, and when the reversing valve stem 1 moves to the left end or the right end, it is the working valve position or the valve stem end stroke position. Of course, this is only an example, Figures 1 to 3 The directional control valve 100 shown is a three-position four-way electro-hydraulic directional control valve, see Figure 7 However, it is obvious that the reversing valve 100 can have more valve positions and oil ports.

[0049] Specific to Figure 7 The three-position four-way electro-hydraulic directional control valve shown in FIG. 1 is used to realize the directional control function of the directional control valve 100 and the unloading function of the unloading valve 200. Figure 3 The above-mentioned valve stem inner flow channel may include a first valve stem inner flow channel 13 and a second valve stem inner flow channel 14 arranged at both axial ends of the reversing valve stem 1; see Figure 2 The inner flow channel of the valve wall may include a first inner flow channel 21 and a second inner flow channel 22 extending from the hydraulic control chamber toward both axial sides; wherein the axial outer end of the first valve stem inner flow channel 13 is used to align with the first valve wall inner flow channel 21 and the axial inner end is used to connect with the first working oil chamber B, and the axial outer end of the second valve stem inner flow channel 14 is used to align with the second valve wall inner flow channel 22 and the axial inner end is used to connect with the second working oil chamber A.

[0050] The left-right symmetrical design of the flow channel in the valve stem and the flow channel in the valve wall makes it possible for the hydraulic control chamber of the unloading valve 200 to be connected with the relatively high-pressure oil chambers in the first working oil chamber B and the second working oil chamber A through the flow channel in the valve wall and the flow channel in the valve stem in sequence when the reversing valve stem 1 moves to the left valve stem end stroke position or the right valve stem end stroke position, thereby closing the unloading valve 200.

[0051] For the convenience of processing, any of the first valve stem inner flow channel 13, the second valve stem inner flow channel 14, the first valve wall inner flow channel 21 and the second valve wall inner flow channel 22 includes an axial flow channel and a radial flow channel. It should be noted that, Figure 3 In the first valve stem inner flow channel 13 and the second valve stem inner flow channel 14 shown, due to the sectional viewing angle, only the respective radial flow channels are shown in the form of circles.

[0052] In this embodiment, if Figure 1 The reversing valve group shown may also include a relief valve 300, which is integrated on the valve wall of the reversing valve body 2 and the valve mouth is arranged between the return oil inner flow channel L and the oil inlet chamber P. After the integration of the relief valve 300, the reversing valve group has a higher degree of integration, a compact structure, and more comprehensive functions. Among them, the return oil inner flow channel L extends to the second axial side of the oil inlet chamber P and is arranged at intervals on the axial outer side of the second working oil chamber A, which not only facilitates the hydraulic control chamber of the unloading valve 200 to communicate with the return oil chamber T through the gear slot 12, but also facilitates the setting of the relief valve 300.

[0053] In addition, in order to realize large flow rate oil return, the unloading valve 200 adopts the form of a cartridge valve. Figure 7 After adopting the cartridge valve, even when the reversing valve with the O-type center position function is in the center position, the high-pressure oil at the P port can open the cartridge valve in the positive direction, thereby realizing large-flow unloading, and will not cause pressure accumulation or pressure shock to the oil inlet chamber P of the reversing valve.

[0054] On the basis of the above, the present application also discloses a pumping hydraulic system, including a pumping cylinder group and the above-mentioned reversing valve group, and the reversing valve 100 is used to control the pumping cylinder group. Through the integrated optimization design of the above-mentioned reversing valve group, not only is the integration high and the cost low, but also the use is smooth, the reversing process is unloaded in time, and no pressure shock is caused.

[0055] Specifically, during the pumping reversing process, the reversing valve stem 1 is used to control the opening or closing of the unloading valve 200, which avoids the pressure shock of the P port and greatly reduces the instantaneous pressure shock of the high-pressure oil of the P port on the oil return chamber T. Figure 7 When the reversing valve 100 is in the middle position, the spring chamber of the unloading valve 200 can be connected with the oil return chamber T through the flow channel in the valve wall and the gear groove 12 from both ends, so that the unloading valve 200 is opened under the action of the pressure oil in the oil inlet chamber P, and the pumping oil port of the main pump is unloaded.

[0056] In the process of the reversing valve stem 1 moving from the middle position to the left end until it reaches the bottom, as the valve stem reversing stroke increases, the gear groove 12 at the left end can successively disconnect the connection between the flow channel 22 in the second valve wall and the return oil chamber T, the oil inlet chamber P is connected with the first working oil chamber B, the second working oil chamber A is connected with the return oil chamber T, the gear groove 12 at the right end disconnects the connection between the flow channel 21 in the first valve wall and the return oil chamber T, the flow channel 13 in the first valve stem is connected with the first working oil chamber B and the flow channel 21 in the first valve wall, the unloading valve 200 is closed, and the main pump pressure oil enters the first working oil chamber B through the oil inlet chamber P, driving the pumping cylinder group to operate.

[0057] In the process of the reversing valve stem 1 moving from the middle position to the right until it reaches the bottom, as the valve stem reversing stroke increases, the gear groove 12 at the right end disconnects the flow channel 21 in the first valve wall and the return oil chamber T, the oil inlet chamber P is connected with the second working oil chamber A, and the first working oil chamber B is connected with the T chamber, the gear groove 12 at the left end disconnects the flow channel 22 in the second valve wall and the return oil chamber T, the flow channel 14 in the second valve stem connects the second working oil chamber A with the flow channel 22 in the second valve wall, the unloading valve 200 is closed, and the main pump pressure oil enters the second working oil chamber A through the oil inlet chamber P, driving the pumping cylinder group to operate.

[0058] It can be seen that the unloading solenoid valve is cancelled in the pumping hydraulic system of the present application, and the opening or closing of the unloading valve 200 is controlled by the reversing valve stem 1 to avoid the pressure shock of the pumping oil port of the main pump during the pumping reversing process. Damping can also be set in the flow channel inside the valve stem of the reversing valve stem 1 to limit the opening speed of the unloading valve 200, which can avoid the pressure oil of the pumping oil port of the main pump from impacting the return oil chamber T, causing the instantaneous pressure of the return oil chamber T to be too high, and damaging the radiator and other components. In short, the present application adopts the reversing valve stem 1 to control the opening or closing of the unloading valve 200, which can avoid the pressure shock caused by the pumping oil port of the main pump during the reversing process, and avoid the engine from dropping speed or stalling. During the pumping reversing process, the opening speed of the unloading valve 200 is limited by the reversing valve stem 1, which can greatly reduce the instantaneous pressure shock of the high-pressure oil of the main pump on the return oil chamber T, and avoid radiator damage and other faults.

[0059] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0060] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0061] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0062] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. High and low pressure switching valve, used for high and low pressure switching control of pumping cylinder group, characterized by: The high-low pressure switching valve (400) comprises: A switching valve body (4) is provided with an axial switching valve stem cavity (5) therein, a plurality of first side oil ports and a plurality of second side oil ports extending to the switching valve stem cavity (5) are provided on a valve wall of the switching valve body (4), the plurality of second side oil ports comprising a rod cavity connecting oil port group for connecting to the oil cylinder rod cavity of the pumping oil cylinder group and a rodless cavity connecting oil port group for connecting to the oil cylinder rodless cavity; A switching valve stem (6) is slidably disposed in the switching valve stem cavity (5) and is used to control the plurality of first side oil ports to selectively connect to the rod cavity connecting oil port group or to connect to the rodless cavity oil port group according to the valve stem movement stroke; The valve wall of the switching valve body (4) is further provided with a drain oil chamber (7) extending to the switching valve stem chamber (5); a valve stem drain oil flow channel (64) is further provided in the switching valve stem (6); the valve stem drain oil flow channel (64) is used to connect the drain oil chamber (7) with the second side oil port.

2. The high-low pressure switching valve according to claim 1, characterized in that: In the switching valve stem chamber (5), the plurality of first side oil ports are arranged axially in the middle at intervals, one of the rod chamber connecting oil port group and the rodless chamber oil port group is arranged between the plurality of first side oil ports at intervals, and the other is symmetrically arranged axially outside the plurality of first side oil ports; Wherein, at the axial end of the switching valve stem cavity (5), an end connecting cavity (C) extending to the switching valve stem cavity (5) is further provided on the valve wall of the switching valve body (4), and the end connecting cavity (C) is used to connect each oil port in the axial outer oil port group when a plurality of the first side oil ports are connected to the axial inner oil port group of the first side oil ports.

3. The high-low pressure switching valve according to claim 2, characterized in that: The first side oil port includes a first oil port (A') and a second oil port (B'), the rod cavity connecting oil port group includes a first rod cavity connecting oil port (A1) and a second rod cavity connecting oil port (B1), and the rodless cavity connecting oil port group includes a first rodless cavity connecting oil port (A2) and a second rodless cavity connecting oil port (B2); Wherein, the rod chamber connecting oil port group is the axial outer oil port group, the end connecting chamber (C) and one of the first rod chamber connecting oil port (A1) and the second rod chamber connecting oil port (B1) are arranged at the same axial end of the switching valve stem chamber (5) with an oil port interval, and are kept in communication with the other of the first rod chamber connecting oil port (A1) and the second rod chamber connecting oil port (B1).

4. The high-low pressure switching valve according to claim 2, characterized in that: The switching valve stem (6) comprises: An inner oil port communication groove (61) arranged in the center and outer oil port communication grooves (62) arranged at intervals on the axial outside of the inner oil port communication groove (61); The end communicating groove (63) is used to control the communication between the end communicating cavity (C) and the oil ports in the adjacent axial outer oil port group.

5. The high-low pressure switching valve according to claim 4, characterized in that: One end of the valve stem drain oil flow channel (64) extends to communicate with the inner oil port connecting groove (61), and the other end extends axially outward to the outside of the outer oil port connecting groove (62) and is used to communicate with the drain oil chamber (7).

6. The high-low pressure switching valve according to claim 4, characterized in that: The drain oil chamber (7) and the end connecting groove (C) are distributed at two axial ends of the switching valve stem chamber (5).

7. The high-low pressure switching valve according to any one of claims 1 to 6, characterized in that: The high-low pressure switching valve (400) is further integrated with an oil replenishment and drain valve (500), and the oil replenishment outlet of the oil replenishment and drain valve (500) is connected to the oil replenishment and drain chamber (7).

8. The high-low pressure switching valve according to claim 7, characterized in that: The oil replenishment and drain valve (500) is integrally cast on the switching valve body (4).

9. Pumping control valve group, characterized in that: The pumping control valve group includes a reversing valve group for controlling the pumping cylinder group and a high-low pressure switching valve according to any one of claims 1 to 8, and the plurality of first side oil ports are connected to the working oil port of the reversing valve group.

10. Pumping hydraulic system, characterized in that, The pumping hydraulic system includes the pumping control valve group according to claim 9.

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