A pressure cut-off valve, closed piston pump system and engineering machine
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGSU ADVANCED CONSTR MASCH INNOVATION CENT LTD
- Filing Date
- 2025-12-08
- Publication Date
- 2026-07-14
Smart Images
Figure CN121676367B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of engineering machinery technology, and specifically relates to a pressure shut-off valve, a closed plunger pump system, and engineering machinery. Background Technology
[0002] Closed-loop piston pumps, as core power components of hydraulic systems, are widely used in construction machinery and mining machinery. Their performance directly affects the efficiency, controllability, and reliability of the entire system. Closed-loop pumps are typically equipped with a pressure shut-off function, designed to quickly reduce the pump's displacement to a minimum when the system pressure reaches a set value. At this point, the pump only maintains the necessary flow rate to compensate for system leakage, thereby limiting system pressure and protecting the system and components from damage.
[0003] However, the closed-loop pump pressure cutoff design in related technologies has the following problems:
[0004] A symmetrical cutting value design cannot meet the optimal matching of working conditions and has poor adaptability. Taking rotary drilling as an example, during drilling (motor forward rotation, high pressure at pump A), it is necessary to overcome the resistance of the formation (such as the shearing and fracturing resistance of soil and rock) to perform rotary cutting. During drilling retrieval (motor reverse rotation, high pressure at pump B), the main challenges are overcoming the friction between the drill string and the borehole wall, the weight of the drill string, and the adhesion force of the drilling mud. To prevent borehole instability, damage to the power head, and to ensure verticality, a light pressure and slow speed are generally used during drilling. To cope with sudden stuck drill bits, overcome vacuum suction, and ensure construction efficiency, the pressure value for retrieving the drill string is usually much higher than that for drilling.
[0005] Under pressure shut-off conditions, the discharge rate cannot be adjusted, and no micro-adjustments such as high-pressure micro-adjustments or pressure-holding creep can be performed, affecting operational efficiency and limiting equipment performance improvement. Taking rotary drilling as an example, when encountering hard rock formations, the system pressure reaches the set threshold of the pressure shut-off valve, reducing the pump's discharge rate to zero, causing the drill rod to stop rotating. It is necessary to appropriately lift the drill rod and then use a jogging, low-speed method to pass through the rock formation. Frequent lifting of the drill rod will lead to reduced work efficiency and extended construction period. Summary of the Invention
[0006] Objective: In view of at least one of the above technical problems, the present invention provides a pressure shut-off valve, a closed-loop plunger pump system, and engineering machinery. The plunger pump has independently stepless adjustment of pressure value and minimum displacement, fundamentally solving the problems of the inability to differentiate and steplessly adjust the pressure of the two working ports and the inability to adjust the minimum displacement under pressure shut-off conditions.
[0007] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:
[0008] In a first aspect, a pressure shut-off valve is provided, including a valve sleeve installed in a valve seat, the valve sleeve having a first oil port A, a second oil port B, a pilot oil port PS, a return oil port T, a first flow channel and a second flow channel; an elastic component, a shut-off valve core, a stepped valve core and a solid shuttle valve core are sequentially arranged inside the valve sleeve.
[0009] The stepped valve core has a first end face communicating with a first flow channel and a second end face communicating with a second flow channel, and the area of the first end face is smaller than the area of the second end face.
[0010] A solid shuttle valve core is used to control the connection and disconnection between the first oil port A and the first flow channel and between the second oil port B and the second flow channel, wherein one of the first oil port A and the first flow channel and the second oil port B and the second flow channel are in a connected state and the other is in a blocked state.
[0011] The shut-off valve core has a first end connected to the second end of the elastic component and a second end connected to the stepped valve core. It is used to control the on / off connection between the pilot port PS and the return port T by changing the position of the shut-off valve core.
[0012] The output pressure oil passage of the proportional valve is connected to the first end of the elastic component, which is used to control the opening degree of the pressure shut-off valve by the magnitude of the input current of the proportional valve.
[0013] In some embodiments, the pressure shut-off valve further includes a hollow shuttle valve core, which is installed in the valve seat. The first inlet is connected to the first oil port A, the second inlet is connected to the second oil port B, and the outlet is connected to the proportional valve. It is used to select the hydraulic oil with higher pressure between the first oil port A and the second oil port B as the pilot oil of the proportional valve.
[0014] In some embodiments, the pressure shut-off valve further includes a screw plug for limiting the valve core of the hollow shuttle valve and sealing the flow channel.
[0015] In some embodiments, the first oil port A and the first flow channel are connected and disconnected by the first part of the solid shuttle valve core, and the second oil port B and the second flow channel are connected and disconnected by the second part of the solid shuttle valve core.
[0016] In some embodiments, the elastic component includes a spring, a first spring seat at a first end, and a second spring seat at a second end, wherein the first end of the spring is compressed and mounted on the first spring seat, and the second end of the spring is compressed and mounted on the second spring seat.
[0017] In some embodiments, the pressure shut-off valve further includes an elastic preload adjustment device for adjusting the magnitude of the elastic preload of the elastic component.
[0018] In this embodiment, the elastic preload adjusting device includes an adjusting screw, which is mounted on the valve seat via a threaded sleeve. The adjusting screw is threadedly connected to the threaded sleeve, and the screw end of the adjusting screw makes pressure contact with the first end of the elastic component. Furthermore, the elastic preload adjusting device also includes a locking nut for fixing the relative position between the adjusting screw and the threaded sleeve.
[0019] In some embodiments, the pressure shut-off valve further includes a slider located at the first end of the elastic component. The inner hole of the slider is engaged with the lower end of the elastic preload adjustment device, and the outer diameter of the slider is engaged with the inner diameter of the valve sleeve. The slider can slide within the valve sleeve with the elastic component.
[0020] In some embodiments, the pressure shut-off valve further includes a shuttle valve seat disposed within a valve sleeve, the shuttle valve seat being close to the second end of the solid shuttle valve core for limiting the second end of the solid shuttle valve core.
[0021] Secondly, the present invention also provides a closed-loop piston pump system, including a control valve, a variable piston, a piston pump, a replenishing pump, and the pressure shut-off valve.
[0022] The first port A and the second port B of the pressure shut-off valve are respectively connected to the two working ports of the plunger pump, the pilot port PS is connected to the outlet of the replenishing pump and the inlet of the control valve, and the return port T is connected to the return oil channel of the closed plunger pump system.
[0023] The control valve is used to provide pilot fluid to the variable piston, thereby regulating the displacement of the plunger pump.
[0024] In some embodiments, the closed-loop piston pump system sets the required pressure cut-off value by adjusting the elastic preload of the elastic component;
[0025] When the pressure at the first port A is greater than that at the second port B, the solid shuttle valve core moves towards the first flow channel under the action of hydraulic pressure until it blocks the first flow channel. At the same time, the second flow channel opens, and the hydraulic pressure acts on the second end face of the stepped valve core. The resulting hydraulic pressure counteracts the elastic preload of the elastic component. Simultaneously, the hollow shuttle valve core moves towards closing the second port B under the action of hydraulic pressure. The hydraulic oil at the first port A passes through the central hole of the hollow shuttle valve core as the pilot oil for the proportional valve. When the system pressure rises to the point that the hydraulic pressure acting on the second end face of the stepped valve core is greater than the elastic preload, the shut-off valve core moves under the action of the stepped valve core, connecting the pilot port PS with the return port T. The control valve loses its pilot oil source, and the plunger pump becomes zero displacement, thereby limiting the system pressure.
[0026] When the pressure at the second port B is greater than that at the first port A, the solid shuttle valve core moves towards the second flow channel under the action of hydraulic pressure until it blocks the second flow channel. At the same time, the first flow channel opens, and the hydraulic pressure acts on the first end face of the stepped valve core. The resulting hydraulic pressure counteracts the elastic preload of the elastic component. Simultaneously, the hollow shuttle valve core moves towards closing the first port A under the action of hydraulic pressure. The hydraulic oil at the second port B passes through the central hole of the hollow shuttle valve core as the pilot oil for the proportional valve. When the system pressure rises to the point that the hydraulic pressure acting on the first end face of the stepped valve core is greater than the elastic preload, the shut-off valve core moves under the action of the stepped valve core, connecting the pilot port PS with the return port T. The control valve loses its pilot oil source, and the plunger pump becomes zero displacement, thereby limiting the system pressure.
[0027] In some embodiments, when the proportional valve is energized, the output pressure of the proportional valve acts on the first end of the elastic component, the elastic preload of the elastic component increases, and the elastic preload increases with the increase of the input current of the proportional valve, thereby realizing stepless adjustment of the pressure cut-off value and the input current of the proportional valve.
[0028] In some embodiments, the displacement is steplessly adjusted under pressure cut-off conditions: Under pressure cut-off conditions, the current of the proportional valve is increased, and the output pressure of the proportional valve acts on the first end of the elastic component, moving the valve core of the cut-off valve in the closing direction between the pilot port PS and the return port T. At this time, the opening of the pressure cut-off valve gradually decreases, and the oil is throttled through the opening of the pressure cut-off valve. At this time, the pilot port PS is not completely depressurized, and a certain pilot oil pressure remains to maintain the operation of the variable piston, so that the plunger pump still maintains a certain displacement output under pressure cut-off conditions. The opening of the pressure cut-off valve decreases as the input current of the proportional valve increases, thereby realizing the stepless adjustment of the plunger pump displacement and the input current of the proportional valve.
[0029] Thirdly, an engineering machine is equipped with the closed-loop piston pump system described in the second aspect.
[0030] Beneficial effects: The pressure shut-off valve, closed-loop piston pump system and engineering machinery provided by this invention can provide precise pressure protection according to the actual needs of different working conditions through differentiated setting and stepless adjustment of oil port pressure, significantly improving working condition adaptability and work efficiency.
[0031] By using the stepless adjustment of minimum displacement under pressure cut-off conditions, the ability to escape from difficult situations and the continuity of operation are greatly improved.
[0032] By digitizing and programmable pressure and displacement control and deeply integrating them with the overall controller, the oil port pressure cut-off value and minimum displacement can be dynamically adjusted, thereby achieving adaptive improvement of the main unit's intelligence level. Attached Figure Description
[0033] Figure 1 This is a schematic cross-sectional view of the pressure shut-off valve according to an embodiment of this application;
[0034] Figure 2 This is a schematic diagram of the closed-loop piston pump system according to an embodiment of this application;
[0035] Figure 3 This is a cross-sectional schematic diagram of the valve sleeve in an embodiment of the present invention;
[0036] Figure 4 This is a cross-sectional schematic diagram of the first embodiment of the stepped valve core in this invention;
[0037] Figure 5 This is a cross-sectional schematic diagram of the solid shuttle valve core in an embodiment of the present invention;
[0038] Figure 6 This is a cross-sectional schematic diagram of the first embodiment of the hollow shuttle valve core in this invention;
[0039] Figure 7 This is a cross-sectional schematic diagram of the second embodiment of the stepped valve core in this invention;
[0040] Figure 8 This is a cross-sectional schematic diagram of the second embodiment of the hollow shuttle valve core in this invention.
[0041] Reference numerals: shuttle valve seat 101, solid shuttle valve core 102, valve sleeve 103, stepped valve core 104, first end face 1041, second end face 1042, shut-off valve core 105, second spring seat 106, spring 107, slider 108, adjusting screw 109, screw sleeve 110, locking nut 111, valve seat 112, proportional valve 113, hollow shuttle valve core 114, center hole 1141, screw plug 115, first flow channel 116, second flow channel 117, first spring seat 118;
[0042] Pressure shut-off valve 1, control valve 2, variable piston 3, plunger pump 4, oil replenishment pump 5, first relief valve 6, second relief valve 7, third relief valve 8. Detailed Implementation
[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0044] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.
[0045] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0046] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0047] The related technologies have the following drawbacks:
[0048] (1) The working port pressure shut-off valve is designed with a symmetrical pressure setting, which makes it impossible to achieve differential adjustment of the port pressure;
[0049] (2) External control devices increase the number of leakage points, reduce reliability, and have many parts and complex structures;
[0050] (3) The pressure cut-off setting value cannot be steplessly adjusted;
[0051] (4) Adding a fixed throttling damper to the circuit, the pump's displacement is constrained by the size of the fixed throttling damper when the pressure is cut off, and the pump's displacement cannot be adjusted in real time.
[0052] To address this, this application provides a pressure shut-off valve, a closed-loop piston pump system, and engineering machinery. It breaks through the design limitations of traditional symmetrical pressure shut-off values, achieving independent, stepless pressure adjustment in two working directions. This enables precise and optimal pressure protection under different working conditions, thereby improving energy efficiency. It also breaks the traditional pump's "zero" displacement mode after pressure shut-off, allowing the piston pump to still achieve stepless adjustable minimum displacement capability under pressure shut-off protection, enabling high-pressure micro-motion precision operation and improving efficiency and escape capability under extreme working conditions. Furthermore, by programming pressure and displacement control, the intelligence level and working condition adaptability of the engineering machinery can be improved.
[0053] Example 1: As Figure 1 , Figure 2 As shown, this embodiment provides a pressure shut-off valve, including a valve sleeve 103 installed in a valve seat 112. Figure 3 This is a cross-sectional schematic diagram of valve sleeve 103 in an embodiment of the present invention; valve sleeve 103 is provided with a first oil port A, a second oil port B, a pilot oil port PS, a return oil port T, a first flow channel 116 and a second flow channel 117; elastic components, a shut-off valve core 105, a stepped valve core 104 and a solid shuttle valve core 102 are sequentially arranged inside valve sleeve 103.
[0054] The stepped valve core 104 has a first end face 1041 communicating with the first flow channel 116 and a second end face 1042 communicating with the second flow channel 117, and the area of the first end face is smaller than the area of the second end face.
[0055] The solid shuttle valve core 102 is used to control the connection and disconnection between the first oil port A and the first flow channel 116 and between the second oil port B and the second flow channel 117, wherein one of the first oil port A and the first flow channel 116 and the second oil port B and the second flow channel 117 is in a connected state and the other is in a blocked state.
[0056] The shut-off valve core 105 has a first end connected to the second end of the elastic component and a second end connected to the stepped valve core 104. It is used to control the on / off connection between the pilot port PS and the return port T by changing the position of the shut-off valve core 105.
[0057] The output pressure oil passage of the proportional valve 113 is connected to the first end of the elastic component, and is used to control the opening degree of the pressure shut-off valve by the magnitude of the input current of the proportional valve 113.
[0058] In some embodiments, the stepped valve core 104 has a stepped cylindrical structure. Figure 4 This is a cross-sectional schematic diagram of the first embodiment of the stepped valve core in this invention; Figure 7 This is a cross-sectional schematic diagram of the second embodiment of the stepped valve core in this invention; it should be noted that, since the area of the first end face is smaller than the area of the second end face, the pressure cut-off values of the first oil port A and the second oil port B can be set differently.
[0059] Figure 5 This is a cross-sectional schematic diagram of the solid shuttle valve core in an embodiment of the present invention.
[0060] In some embodiments, such as Figure 1 As shown, the pressure shut-off valve also includes a hollow shuttle valve core 114, which is installed in the valve seat 112. The first inlet is connected to the first oil port A, the second inlet is connected to the second oil port B, and the outlet is connected to the proportional valve 113. It is used to select the hydraulic oil with higher pressure between the first oil port A and the second oil port B as the pilot oil of the proportional valve 113. Figure 6 This is a cross-sectional schematic diagram of the hollow shuttle valve core in an embodiment of the present invention. Figure 8 This is a cross-sectional schematic diagram of the second embodiment of the hollow shuttle valve core in this invention.
[0061] In some embodiments, the pressure shut-off valve further includes a screw plug 115 for limiting the valve core 114 of the hollow shuttle valve and sealing the flow channel.
[0062] In some embodiments, such as Figure 1 As shown, the first oil port A and the first flow channel 116 are connected and disconnected through the first part of the solid shuttle valve core 102, and the second oil port B and the second flow channel 117 are connected and disconnected through the second part of the solid shuttle valve core 102.
[0063] Furthermore, in this embodiment, as Figure 5 As shown, the solid shuttle valve core 102 is a cylindrical structure with smaller diameters at both ends and a larger diameter in the middle. The first flow channel 116 is opened and closed through the first end face of the solid shuttle valve core 102, and the second flow channel 117 is opened and closed through the circumferential surface in the middle of the solid shuttle valve core 102.
[0064] In some embodiments, the elastic component includes a spring 107, a first spring seat 118 at a first end, and a second spring seat 106 at a second end, wherein the first end of the spring 107 is compressed and mounted on the first spring seat 118, and the second end of the spring 107 is compressed and mounted on the second spring seat 106.
[0065] In some embodiments, the pressure shut-off valve further includes an elastic preload adjustment device for adjusting the magnitude of the elastic preload of the elastic component.
[0066] In this embodiment, as Figure 1As shown, the elastic preload adjustment device includes an adjusting screw 109, which is mounted on the valve seat 112 via a threaded sleeve 110. The adjusting screw 109 is threadedly connected to the threaded sleeve 110, and the screw end of the adjusting screw 109 is in pressure contact with the first end of the elastic component. Furthermore, the elastic preload adjustment device also includes a locking nut 111 for fixing the relative position between the adjusting screw 109 and the threaded sleeve 110.
[0067] In some embodiments, such as Figure 1 As shown, the pressure shut-off valve also includes a slider 108 located at the first end of the elastic component. The inner hole of the slider 108 is engaged with the lower end of the elastic preload adjustment device, and the outer diameter of the slider 108 is engaged with the inner diameter of the valve sleeve 103. The slider 108 can slide within the valve sleeve 103 with the elastic component.
[0068] In some specific embodiments, the threaded sleeve 110 is threadedly connected to the valve seat 112, the adjusting screw 109 is threadedly connected to the threaded sleeve 110, the inner hole of the slider 108 is fitted with the adjusting screw 109, the outer diameter of the slider 108 is fitted with the valve sleeve 103, the slider 108 can slide within the adjusting screw 109 and the valve sleeve 103, one end of the slider 108 is attached to the spring seat 106, one end of the adjusting screw 109 acts on the first spring seat 118, and the shut-off valve core 105 and the stepped valve core 104 are pushed into the valve sleeve 103 by the spring 107 and the second spring seat 106. By changing the screwing depth of the adjusting screw 108, the elastic preload is changed. After adjustment, the adjusting screw 109 is locked with the lock nut 111.
[0069] In some embodiments, such as Figure 1 As shown, the pressure shut-off valve also includes a shuttle valve seat 101 disposed in the valve sleeve 103. The shuttle valve seat 101 is close to the second end of the solid shuttle valve core 102 and is used to limit the second end of the solid shuttle valve core 102.
[0070] Example 2: This example provides a closed-loop piston pump system, including a control valve 2, a variable piston 3, a piston pump 4, a replenishing pump 5, and the pressure shut-off valve described in any one of Examples 1;
[0071] The first oil port A and the second oil port B of the pressure shut-off valve are respectively connected to the two working oil ports of the plunger pump 4, the pilot oil port PS is connected to the outlet of the replenishing oil pump 5 and the inlet of the control valve 2, and the return oil port T is connected to the return oil channel of the closed plunger pump system.
[0072] The control valve 2 is used to provide pilot oil to the variable piston 3, thereby adjusting the displacement of the plunger pump 4.
[0073] In some embodiments, a first relief valve 6 and a second relief valve 7 are provided between the two working ports of the plunger pump 4; a third relief valve 8 is provided at the outlet of the replenishment pump 5.
[0074] The following is combined with, for example Figure 1 , Figure 2 The working principle of the closed-loop piston pump system in this embodiment is introduced as follows:
[0075] In this application, the required pressure cut-off value is set by adjusting the elastic preload of the elastic component;
[0076] When the pressure at the first port A is greater than that at the second port B, the solid shuttle valve core 102 moves towards the first flow channel 116 under the action of hydraulic pressure until it blocks the first flow channel 116. At the same time, the second flow channel 117 opens, and the hydraulic pressure acts on the second end face of the stepped valve core 104. The resulting hydraulic pressure counteracts the elastic preload of the elastic component. Meanwhile, the hollow shuttle valve core 114 moves towards closing the second port B under the action of hydraulic pressure. The hydraulic oil at the first port A passes through the central hole of the hollow shuttle valve core as the pilot oil for the proportional valve 113. When the system pressure rises to the point that the hydraulic pressure acting on the second end face of the stepped valve core 104 is greater than the elastic preload, the shut-off valve core 105 moves under the action of the stepped valve core 104, connecting the pilot port PS with the return port T. The control valve 2 loses its pilot oil source, and the plunger pump becomes zero displacement, thereby limiting the system pressure.
[0077] When the pressure at the second port B is greater than that at the first port A, the solid shuttle valve core 102 moves towards the second flow channel 117 under the action of the hydraulic pressure until it blocks the second flow channel 117. At the same time, the first flow channel 116 opens, and the hydraulic pressure acts on the first end face of the stepped valve core 104. The hydraulic pressure generated counteracts the elastic preload of the elastic component. Meanwhile, the hollow shuttle valve core 114 moves towards closing the first port A under the action of the hydraulic pressure. The hydraulic oil at the second port B passes through the central hole 1141 of the hollow shuttle valve core as the pilot oil for the proportional valve 113. When the system pressure rises to the point that the hydraulic pressure acting on the first end face of the stepped valve core 104 is greater than the elastic preload, the shut-off valve core 105 moves under the action of the stepped valve core 104, connecting the pilot port PS with the return port T. The control valve 2 loses its pilot oil source, and the plunger pump becomes zero displacement, thereby limiting the system pressure.
[0078] When the proportional valve 113 is energized, the output pressure of the proportional valve 113 acts on the first end of the elastic component, the elastic preload of the elastic component increases, and the elastic preload increases with the increase of the input current of the proportional valve, thereby realizing stepless adjustment of the pressure cut-off value and the input current of the proportional valve.
[0079] Stepless displacement adjustment under pressure cut-off condition: Under pressure cut-off condition, the current of proportional valve 113 is increased by adjusting the proportional valve 113. The output pressure of proportional valve 113 acts on the first end of the elastic component, moving the valve core 105 of the cut-off valve in the direction of closing between the pilot port PS and the return port T. At this time, the opening of the pressure cut-off valve gradually decreases, and the oil is throttled by the opening of the pressure cut-off valve. At this time, the pilot port PS is not completely depressurized, and a certain pilot oil pressure remains to maintain the operation of the variable piston 3, so that the plunger pump still maintains a certain displacement output under pressure cut-off condition. The opening of the pressure cut-off valve decreases as the input current of the proportional valve increases, thereby realizing stepless adjustment of the plunger pump displacement and the input current of the proportional valve.
[0080] Furthermore, in some embodiments, the operation method of the closed-loop piston pump system may also include: the controller dynamically adjusts the input current of the proportional valve by acquiring the operating mode signal and the outlet pressure sensor signal of the piston pump, so as to achieve adaptive adjustment of the oil port pressure cut-off value and the minimum displacement.
[0081] Example 3: This example provides an engineering machine equipped with the closed-loop piston pump system described in Example 2.
[0082] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.
[0083] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A pressure shut-off valve, characterized in that, The valve sleeve is installed in the valve seat. The valve sleeve is provided with a first oil port A, a second oil port B, a pilot oil port PS, a return oil port T, a first flow channel and a second flow channel. The valve sleeve is sequentially provided with an elastic component, a shut-off valve core, a stepped valve core and a solid shuttle valve core. The stepped valve core has a first end face communicating with a first flow channel and a second end face communicating with a second flow channel, and the area of the first end face is smaller than the area of the second end face. A solid shuttle valve core is used to control the connection and disconnection between the first oil port A and the first flow channel and between the second oil port B and the second flow channel, wherein one of the first oil port A and the first flow channel and the second oil port B and the second flow channel are in a connected state and the other is in a blocked state. The shut-off valve core has a first end connected to the second end of the elastic component and a second end connected to the stepped valve core. It is used to control the on / off connection between the pilot port PS and the return port T by changing the position of the shut-off valve core. The output pressure oil passage of the proportional valve is connected to the first end of the elastic component, which is used to control the opening of the pressure shut-off valve by the magnitude of the input current of the proportional valve. The hollow shuttle valve core is installed inside the valve seat. The first inlet is connected to the first oil port A, the second inlet is connected to the second oil port B, and the outlet is connected to the proportional valve. It is used to select the hydraulic oil with higher pressure between the first oil port A and the second oil port B as the pilot oil of the proportional valve. The first oil port A and the first flow channel are connected and disconnected through the first part of the solid shuttle valve core, and the second oil port B and the second flow channel are connected and disconnected through the second part of the solid shuttle valve core.
2. The pressure shut-off valve according to claim 1, characterized in that, It also includes a screw plug for limiting the valve core of the hollow shuttle valve and sealing the flow channel.
3. The pressure shut-off valve according to claim 1, characterized in that, The elastic component includes a spring, a first spring seat at a first end, and a second spring seat at a second end. The first end of the spring is compressed and mounted on the first spring seat, and the second end of the spring is compressed and mounted on the second spring seat.
4. The pressure shut-off valve according to claim 1, characterized in that, It also includes an elastic preload adjustment device for adjusting the elastic preload of the elastic component.
5. The pressure shut-off valve according to claim 1, characterized in that, It also includes a slider located at the first end of the elastic component. The inner hole of the slider is engaged with the lower end of the elastic preload adjustment device, and the outer diameter of the slider is engaged with the inner diameter of the valve sleeve. The slider can slide within the valve sleeve with the elastic component.
6. The pressure shut-off valve according to claim 1, characterized in that, It also includes a shuttle valve seat disposed within the valve sleeve, the shuttle valve seat being close to the second end of the solid shuttle valve core, for limiting the second end of the solid shuttle valve core.
7. A closed-loop plunger pump system, characterized in that, Includes a control valve, a variable piston, a plunger pump, a make-up pump, and a pressure shut-off valve as described in any one of claims 1 to 6; The first port A and the second port B of the pressure shut-off valve are respectively connected to the two working ports of the plunger pump, the pilot port PS is connected to the outlet of the replenishing pump and the inlet of the control valve, and the return port T is connected to the return oil channel of the closed plunger pump system. The control valve is used to provide pilot fluid to the variable piston, thereby regulating the displacement of the plunger pump.
8. The closed-loop plunger pump system according to claim 7, characterized in that, The required pressure cut-off value can be set by adjusting the elastic preload of the elastic component; When the pressure at the first port A is greater than that at the second port B, the solid shuttle valve core moves towards the first flow channel under the action of hydraulic pressure until it blocks the first flow channel. At the same time, the second flow channel opens, and the hydraulic pressure acts on the second end face of the stepped valve core. The resulting hydraulic pressure counteracts the elastic preload of the elastic component. Simultaneously, the hollow shuttle valve core moves towards closing the second port B under the action of hydraulic pressure. The hydraulic oil at the first port A passes through the central hole of the hollow shuttle valve core as the pilot oil for the proportional valve. When the system pressure rises to the point that the hydraulic pressure acting on the second end face of the stepped valve core is greater than the elastic preload, the shut-off valve core moves under the action of the stepped valve core, connecting the pilot port PS with the return port T. The control valve loses its pilot oil source, and the plunger pump becomes zero displacement, thereby limiting the system pressure. When the pressure at the second port B is greater than that at the first port A, the solid shuttle valve core moves towards the second flow channel under the action of hydraulic pressure until it blocks the second flow channel. At the same time, the first flow channel opens, and the hydraulic pressure acts on the first end face of the stepped valve core. The resulting hydraulic pressure counteracts the elastic preload of the elastic component. Simultaneously, the hollow shuttle valve core moves towards closing the first port A under the action of hydraulic pressure. The hydraulic oil at the second port B passes through the central hole of the hollow shuttle valve core as the pilot oil for the proportional valve. When the system pressure rises to the point that the hydraulic pressure acting on the first end face of the stepped valve core is greater than the elastic preload, the shut-off valve core moves under the action of the stepped valve core, connecting the pilot port PS with the return port T. The control valve loses its pilot oil source, and the plunger pump becomes zero displacement, thereby limiting the system pressure.
9. The closed-loop plunger pump system according to claim 7, characterized in that, When the proportional valve is energized, the output pressure of the proportional valve acts on the first end of the elastic component, increasing the elastic preload of the elastic component. The elastic preload increases with the increase of the input current of the proportional valve, thereby realizing stepless adjustment of the pressure cut-off value and the input current of the proportional valve.
10. The closed-loop plunger pump system according to claim 7, characterized in that, Stepless displacement adjustment under pressure cut-off conditions: Under pressure cut-off conditions, the proportional valve current is increased, and the output pressure of the proportional valve acts on the first end of the elastic component, moving the valve core of the cut-off valve towards the closed direction between the pilot port PS and the return port T. At this time, the opening of the pressure cut-off valve gradually decreases, and the oil is throttled through the opening of the pressure cut-off valve. At this time, the pilot port PS is not completely depressurized, and a certain amount of pilot oil pressure remains to maintain the operation of the variable piston, so that the plunger pump still maintains a certain displacement output under pressure cut-off conditions. The opening of the pressure cut-off valve decreases as the input current of the proportional valve increases, thereby realizing stepless adjustment of the plunger pump displacement and the input current of the proportional valve.
11. An engineering machinery, characterized in that, The system is equipped with a closed-loop piston pump system as described in any one of claims 7 to 10.