Direct-acting zero-leakage balance valve and hydraulic system
Through the direct-moving structure and cone seal design, combined with O-ring and Glee ring sealing, the existing balance valves are solved, and the zero-leakage balance valves are achieved, reducing the processing difficulty and cost.
Patent Information
- Application Number
- CN202510748343.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-05
- Publication Date
- 2025-07-25
AI Technical Summary
The valve core and valve seat of the existing balance valve are installed in the valve body, making it difficult to achieve zero leakage, difficult to process and high cost, and poor leakage control consistency.
It adopts a direct-moving structure, and forms a conical seal through the valve core and the valve sleeve, and an O-ring and Glee ring seal is set between the valve sleeve and the valve body. Combined with the elastic component and the relief valve design, it achieves zero leakage of the balance valve.
Simplifies processing difficulty, reduces cost, improves concentric accuracy and consistency of leakage control, and ensures zero leakage performance of the balance valve.
Smart Images
Figure CN120367886A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the technical field of hydraulic valves, and particularly relates to a direct-acting zero-leakage balance valve and a hydraulic system. Background Art
[0002] The balance valve is a key hydraulic component installed on an oil cylinder or a motor for maintaining the position of a heavy object and controlling the descent of the heavy object. When the heavy object descends, the balance valve balances the gravity of the heavy object to achieve a stable descent of the heavy object; when the heavy object stops, the balance valve keeps the heavy object safely and reliably locked in a fixed position.
[0003] Currently, balance valves are mainly divided into two types. One is a structure where the check valve and the balance valve are separated, and the other is a structure where the balance valve and the check valve are integrated. The sealing of the balance valve generally uses soft seals such as O-rings and GLY seals, or conical seals.
[0004] The existing technology has the following defects: Currently, the spool and the valve seat of the balance valve are installed in the valve body. To achieve zero leakage of the balance valve, the concentricity of the spool hole, the valve seat, and the spool of the three components needs to be high, which is difficult to process, costly, and the consistency of leakage control is poor. Summary of the Invention
[0005] Objective: To overcome the deficiencies in the existing technology, this application provides a direct-acting zero-leakage balance valve and a hydraulic system.
[0006] Technical Solution: To solve the above technical problems, the technical solution adopted in this application is as follows: In the first aspect, a direct-acting zero-leakage balance valve is provided, which includes a valve body, a valve sleeve, a spool, a valve seat connected to the valve body, a check valve, and a relief valve; The valve body is provided with a control port K, a first working port A, a second working port B, and an installation hole for installing the valve sleeve. The control port K is connected to the first end of the spool, and an elastic component for setting the opening pressure of the balance valve is arranged at the second end of the spool; a spring cavity for installing the elastic component is arranged in the valve seat; the second working port B is respectively connected to the inlets of the check valve and the relief valve, and the first working port A is respectively connected to the outlets of the check valve and the relief valve; The spool includes a first end, a throttling groove portion, a conical sealing portion, and a second end connected in sequence; the valve sleeve is relatively fixedly and sealingly installed in the installation hole, the first end of the spool is movably and sealingly installed in the first end of the valve sleeve, and the second end of the spool is movably and sealingly installed in the first end of the valve seat; a throttling groove is provided between the throttling groove portion of the spool and the valve sleeve, and an openable and closable conical sealing connection is formed between the conical sealing portion of the spool and the inner wall of the second end of the valve sleeve to realize the communication or cutoff between the second working port B and the throttling groove; a valve sleeve hole for communicating the throttling groove with the first working port A is provided on the valve sleeve; the balance valve has at least a first working state, a second working state, and a third working state, corresponding to the first working port A being unidirectionally conducted to the second working port B through a check valve, the first working port A and the second working port B being non-conductive, or the second working port B being communicated back to the first working port A through a relief valve, and the second working port B being communicated to the first working port A through the throttling groove and the valve sleeve hole in sequence.
[0007] Further, when the balance valve is in the first working state, the spool is in the first working position and the pressure of the first working port A is greater than the pressure of the second working port B, the first working port A is unidirectionally conducted to the second working port B through a check valve, and the oil cylinder or motor drives the heavy object to rise; When the balance valve is in the second working state, the spool is in the first working position and the pressure of the first working port A is less than the pressure of the second working port B, the first working port A and the second working port B are non-conductive, and the oil cylinder or motor is stationary; when the pressure of the second working port B is greater than the set pressure, the relief valve opens, and the second working port B is communicated back to the first working port A through the relief valve until the pressure of the second working port B is not greater than the set pressure, and the relief valve closes; When the balance valve is in the third working state, the spool moves under the action of the oil fluid at the control port K to compress the elastic component and moves to the second working position and the pressure of the second working port B is greater than the pressure of the first working port A, the second working port B is communicated to the first working port A through the throttling groove and the valve sleeve hole in sequence, and the oil cylinder or motor drives the heavy object to fall.
[0008] Further, a central hole communicating with the spring cavity is provided in the second end and the conical sealing portion of the spool, and the central hole communicates with the throttling groove of the spool; when the spool moves under the action of the oil fluid at the control port K, the oil fluid in the spring cavity is discharged to the first working port A through the central hole, the throttling groove, and the valve sleeve hole of the spool.
[0009] Further, the valve sleeve and the valve body are sealingly connected through a first O-ring and a second O-ring to separate the second working port B and the first working port A to ensure zero leakage; The circumferential direction between the first end of the spool and the valve sleeve is sealed through a first Gleitring to separate the control port K and the first working port A; the circumferential direction between the second end of the spool and the valve seat is sealed through a second Gleitring to separate the second working port B and the spring cavity of the valve seat to ensure zero leakage.
[0010] Further, the elastic component includes a spring and an adjusting screw. The first end of the spring is connected to the second end of the spool, and the second end of the spring abuts against the adjusting screw. The adjusting screw is arranged at the second end of the valve seat in a sealed connection with an adjustable axial position for adjusting the compression amount of the spring.
[0011] Further, a damping component is arranged between the control port K and the spool. The damping component includes a filter screen, a first damper, a damping joint, an ED seal and a second damper. The inlet end of the damping joint is provided with the filter screen and the first damper. The damping joint is installed in the valve body through an ED seal in a sealed connection, and the outlet of the damping joint communicates with the first end of the spool through the second damper.
[0012] Further, when the spool is in the first working position, a conical seal is formed between the conical sealing portion of the spool and the inner wall of the second end of the valve sleeve, and the second working port B is not communicated with the throttling groove of the spool. When the spool moves to the right under the action of the oil in the control port K and compresses the spring to be in the second working position, the conical seal between the spool and the inner wall of the second end of the valve sleeve is released, and the second working port B is communicated with the first working port A through the throttling groove of the spool and the valve sleeve hole on the valve sleeve in sequence.
[0013] Further, the bottom of the valve seat presses on the end face of the second end of the valve sleeve to fix the valve sleeve in the mounting hole of the valve body.
[0014] Further, a limiting protrusion is also arranged on the outer periphery of the second end portion of the spool near the conical sealing portion. The outer diameter of the limiting protrusion is larger than the inner diameter of the first end of the valve seat and the inner diameter of the valve sleeve for limiting the stroke of the spool through the valve seat.
[0015] Further, the spool hole for installing the spool in the valve sleeve and the spool are machined and formed in one clamping.
[0016] The present application also provides a hydraulic system, including the direct-acting zero-leakage balance valve described above.
[0017] Further, the hydraulic system also includes an oil cylinder or a motor falling control oil port, an oil cylinder or a motor rising port, and an oil cylinder or a motor falling port. The control port K is connected to the oil cylinder or the motor falling control oil port, the first working port A is connected to the oil cylinder or the motor rising port, and the second working port B is connected to the oil cylinder or the motor falling port.
[0018] Beneficial effects: The direct-acting zero-leakage balance valve and the hydraulic system provided by the present application have the following advantages: The balance valve of the present application adopts a direct-acting structure, which is simple in structure and low in cost.
[0019] The balance valve of the present application maintains a conical seal composed of a valve core and a valve sleeve, as well as a second Gleitring seal between the valve core and the valve seat.
[0020] When the balance valve of the present application is opened, the oil in the spring chamber can be discharged through the central hole on the valve core and the first working port A, with a simple and compact structure and low cost.
[0021] The valve core of the balance valve of the present application is directly installed in the valve sleeve, and the valve core and the valve sleeve form a conical seal. The conical seal is only related to the machining accuracy of the two parts of the valve core and the valve sleeve, and the valve core hole on the valve sleeve and the valve core are machined and formed in one clamping, with high concentric accuracy, making it easier to ensure zero leakage, and the machining difficulty is low and the cost is low.
[0022] After installing the first O-ring and the second O-ring in the groove of the valve sleeve of the present application, it is installed in the hole of the valve body to separate the second working port B and the first working port A of the balance valve to ensure zero leakage.
[0023] The first Gleitring and the second Gleitring are installed in the groove of the valve core of the present application. The first Gleitring separates the pilot oil control port K and the first working port A of the balance valve to ensure zero leakage, and the second Gleitring separates the second working port B of the balance valve and the spring chamber to ensure zero leakage.
[0024] The bottom of the valve seat of the present application presses on the end face of the valve sleeve to fix the valve sleeve in the installation hole of the valve body and prevent it from moving. At the same time, the valve seat can also limit the stroke of the valve core, with a simple and reliable structure. Description of the Drawings
[0025] Figure 1 It is a schematic structural diagram of a direct-acting zero-leakage balance valve in an embodiment of the present application; Figure 2 It is a schematic principle diagram of a direct-acting zero-leakage balance valve in an embodiment of the present application; Figure 3 It is a front view schematic diagram of a direct-acting zero-leakage balance valve in an embodiment of the present application; Figure 4 It is a bottom view schematic diagram of a direct-acting zero-leakage balance valve in an embodiment of the present application; Figure 5 It is a top view schematic diagram of a direct-acting zero-leakage balance valve in an embodiment of the present application; In the figure: valve body 1, first O-ring 2, first Gleitring 3, valve sleeve 4, valve core 5, second O-ring 6, third O-ring 7, second Gleitring 8, valve seat 9, spring 10, fourth O-ring 11, setting screw 12, fifth O-ring 13, protective cap 14, first plug 15, second plug 16, check valve 17, relief valve 18, first damper 19, filter screen 20, damper joint 21, ED seal 22, second damper 23; valve sleeve hole 41; first end 51, throttle groove part 52, taper seal part 53, second end 54; throttle groove 55, central hole 56. Detailed implementation manners
[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way constitutes a limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.
[0027] In the description of the present application, the meaning of several is more than one, the meaning of multiple is more than two, and understandings such as greater than, less than, exceeding, etc. do not include the present number, and understandings such as above, below, within, etc. include the present number. If there is a description of first and second, it is only for the purpose of distinguishing technical features and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.
[0028] In the description of the present application, the description referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.
[0029] In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values.
[0030] It should be noted that: similar symbols and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.
[0031] Example 1: As Figures 1 to 5 shown, this example provides a direct-acting zero-leakage balance valve, which includes a valve body 1, a valve sleeve 4, a valve core 5, a valve seat 9 connected to the valve body 1, a check valve 17, and a relief valve 18; The valve body 1 is provided with a control port K, a first working port A, a second working port B, and a mounting hole for mounting the valve sleeve 4. The control port K is used to connect to the oil cylinder or motor's falling control oil port, the first working port A is used to connect to the rising port of the oil cylinder or motor, and the second working port B is used to connect to the falling port of the oil cylinder or motor; the control port K communicates with the first end of the valve core 5, and an elastic component for setting the opening pressure of the balance valve is arranged at the second end of the valve core 5; a spring cavity for mounting the elastic component is arranged in the valve seat 9; the second working port B is respectively connected to the inlets of the check valve 17 and the relief valve 18, and the first working port A is respectively connected to the outlets of the check valve 17 and the relief valve 18; The valve core 5 includes a first end portion 51, a throttling groove portion 52, a conical sealing portion 53, and a second end portion 54 connected in sequence; the valve sleeve 4 is relatively fixedly and sealedly mounted in the mounting hole, the first end portion 51 of the valve core 5 is movably and sealedly mounted in the first end portion of the valve sleeve 4, and the second end portion 54 of the valve core 5 is movably and sealedly mounted in the first end portion of the valve seat 9; a throttling groove 55 is arranged between the throttling groove portion 52 of the valve core 5 and the valve sleeve 4, and an openable and closable conical sealing connection is formed between the conical sealing portion 53 of the valve core 5 and the inner wall of the second end of the valve sleeve 4 to realize the communication or cut-off between the second working port B and the throttling groove 55; a valve sleeve hole 41 for connecting the throttling groove 55 to the first working port A is opened on the valve sleeve 4; the balance valve has at least a first working state, a second working state, and a third working state; When the balance valve is in the first working state, the valve core 5 is in the first working position and the pressure of the first working port A is greater than the pressure of the second working port B (the first working port A is connected to the oil inlet port, and the second working port B is connected to the oil return port), the first working port A is unidirectionally conducted through the check valve 17 to the second working port B, and the oil cylinder or motor drives the heavy object to rise; When the balance valve is in the second working state, the valve core 5 is in the first working position and the pressure of the first working port A is less than the pressure of the second working port B (the second working port B is connected to the oil inlet port, and the first working port A is connected to the oil return port), the first working port A and the second working port B are not conducted, and the oil cylinder or motor is stationary; when the pressure of the second working port B is greater than the set pressure, the relief valve 18 opens, and the second working port B is connected back to the first working port A through the relief valve 18 until the pressure of the second working port B is not greater than the set pressure, and the relief valve 18 closes; When the balance valve is in the third working state, the valve core 5 is moved to the second working position by compressing the elastic component under the action of the oil fluid at the control port K, and the pressure at the second working port B is greater than the pressure at the first working port A (the second working port B is connected to the oil inlet port, and the first working port A is connected to the oil return port). The second working port B is communicated to the first working port A through the throttle groove 55 and the valve sleeve hole 41 in sequence, and the oil cylinder or the motor drives the heavy object to fall.
[0032] In this embodiment, the check valve 17 and the relief valve 18 are installed in the cartridge valve holes of the valve body 1 by threads.
[0033] In this embodiment, the valve seat 9 is installed in the valve body 1 by threads.
[0034] In some embodiments, such as Figure 1 , Figure 2 shown, the direct-acting zero-leakage balance valve further includes: a third O-ring 7, a fourth O-ring 11, a first plug 15 and a second plug 16; the third O-ring 7 is installed in the groove on the valve body 1 for sealing the second working port B; the first plug 15 and the second plug 16 are respectively installed on the valve body 1 by threads as process plugs to seal the oil passage, and are respectively arranged at Figure 2 the MB port and the A1 port of
[0035] The fourth O-ring 11 is installed on the valve seat 9 for sealing between the valve seat 9 and the valve body 1.
[0036] In some embodiments, such as Figure 1 shown, a central hole 56 communicating with the spring cavity is provided in the second end portion 54 and the tapered sealing portion 53 of the valve core 5, and the central hole 56 is communicated with the throttle groove 55 of the valve core 5; when the valve core 5 moves under the action of the oil fluid at the control port K, the oil fluid in the spring cavity is discharged to the first working port A through the central hole 56, the throttle groove 55 and the valve sleeve hole 41 of the valve core 5.
[0037] In some embodiments, such as Figure 1 shown, the valve sleeve 4 and the valve body 1 are sealed and connected through a first O-ring 2 and a second O-ring 6. In this embodiment, the first O-ring 2 and the second O-ring 6 are installed in the grooves of the valve sleeve 4. The first O-ring 2 is used for sealing between the first part of the valve sleeve 4 and the valve body 1, and the second O-ring 6 is used for sealing between the second part of the valve sleeve 4 and the valve body 1, so as to separate the second working port B and the first working port A to ensure zero leakage.
[0038] In some embodiments, such as Figure 1As shown, the circumferential direction between the first end of the spool 5 and the valve sleeve 4 is sealed by a first Gleason ring 3, which is used to separate the control port K and the first working port A; the circumferential direction between the second end of the spool 5 and the valve seat 9 is sealed by a second Gleason ring 8, which is used to separate the second working port B and the spring chamber of the valve seat 9 to ensure zero leakage. In this embodiment, the first Gleason ring 3 and the second Gleason ring 8 are installed in the grooves of the spool 5.
[0039] In some embodiments, as Figure 1 shown, the elastic component includes a spring 10 and an adjusting screw 12. The first end of the spring 10 is connected to the second end of the spool 5, the second end of the spring 10 abuts against the adjusting screw 12, and the adjusting screw 12 is arranged in a sealed and connected manner with an axially adjustable position at the second end of the valve seat 9 for adjusting the compression amount of the spring 10. Further, in this embodiment, the adjusting screw 12 is installed in the valve seat 9 by means of a thread. Further, a protective cap 14 is also arranged outside the adjusting screw 12, and a fifth O-ring 13 is arranged between the protective cap 14 and the valve seat 9 for sealing.
[0040] In some embodiments, as Figure 1 、 Figure 2 shown, a damping component is arranged between the control port K and the spool 5. The damping component includes a filter screen 20, a first damper 19, a damping joint 21, an ED seal 22 and a second damper 23. The inlet end of the damping joint 21 is installed with the filter screen 20 and the first damper 19. The damping joint 21 is installed in the valve body 1 in a sealed connection manner through the ED seal 22, and the outlet of the damping joint 21 is communicated to the first end of the spool 5 through the second damper 23. Further, in this embodiment, the first damper 19, the filter screen 20, the damping joint 21 and the ED seal 22 are assembled together, and the second damper 23 is installed in the valve body 1 by means of a thread.
[0041] In this embodiment, when the spool 5 is in the first working position (balance valve held), a conical seal is formed between the conical sealing portion 53 of the spool 5 and the inner wall of the second end of the valve sleeve 4, and the second working port B is not communicated with the throttling groove 55 of the spool 5; When the spool 5 moves to the right under the action of the oil in the control port K and compresses the spring 10 to be in the second working position (balance valve opened), the conical seal between the spool 5 and the inner wall of the second end of the valve sleeve 4 is released, and the second working port B is communicated to the first working port A through the throttling groove 55 of the spool 5 and the valve sleeve hole 41 on the valve sleeve 4 in sequence, with a simple and compact structure and low cost.
[0042] In some embodiments, as Figure 1 shown, the bottom of the valve seat 9 presses on the end face of the second end of the valve sleeve 4 to fix the valve sleeve 4 in the installation hole of the valve body 1 and prevent it from moving axially.
[0043] In some embodiments, asFigure 1 As shown, a limiting projection is further provided on the outer periphery of the second end portion 54 of the valve core 5 near the position of the conical sealing portion 53. The outer diameter of the limiting projection is greater than the inner diameter of the first end of the valve seat 9 and the inner diameter of the valve sleeve 4, and is used to limit the stroke of the valve core 5 through the valve seat 9. The structure is simple and reliable.
[0044] In this embodiment, the valve core hole in the valve sleeve 4 for installing the valve core 5 and the valve core 5 are formed by one-time clamping and processing.
[0045] The balance valve spool of the present application is directly installed in the valve sleeve, and the spool and the valve sleeve form a conical seal. The conical seal is only related to the machining accuracy of the two parts of the spool and the valve sleeve. Moreover, the spool hole on the valve sleeve and the spool are formed by one-time clamping and processing, with high concentric accuracy, which is easier to ensure zero leakage, and has low machining difficulty and low cost.
[0046] The balance valve of the present application adopts a direct-acting structure, with a simple structure and low cost.
[0047] Embodiment 2: This embodiment provides a hydraulic system, including the above-mentioned direct-acting zero-leakage balance valve.
[0048] Furthermore, in some embodiments, the hydraulic system further includes an oil cylinder or motor falling control oil port, an oil cylinder or motor rising port, and an oil cylinder or motor falling port. The control port K is connected to the oil cylinder or motor falling control oil port, the first working port A is connected to the oil cylinder or motor rising port, and the second working port B is connected to the oil cylinder or motor falling port.
[0049] When the oil cylinder or motor is stationary, the valve core 5 is in the first working position and the pressure of the first working port A is less than the pressure of the second working port B. The pressure oil of the second working port B is sealed by the conical seal formed by the valve core 5 and the valve sleeve 4, and the second O-ring 8 between the valve core 5 and the valve seat 9. The first working port A and the second working port B are not communicated, and at this time, the heavy object is held in a fixed position. When the ambient temperature rises and the oil expands, resulting in the pressure of the second working port B rising above the set pressure, the relief valve 18 opens, and the second working port B is connected to the first working port A through the relief valve 18 and returns to the first working port A until the pressure of the second working port B is not greater than the set pressure, and the relief valve 18 closes, so that the pressure of the second working port B no longer rises, avoiding high-pressure damage to the oil cylinder or motor.
[0050] When the oil cylinder or motor drives the heavy object to rise, the valve core 5 is in the first working position and the pressure of the first working port A is greater than the pressure of the second working port B. The oil passes through the first working port A to open the check valve 17 to the second working port B to the rising port of the oil cylinder or motor, and pushes the oil cylinder or motor to drive the heavy object to rise.
[0051] When the oil cylinder or the motor drops with a heavy load, the oil fluid at the oil port for controlling the dropping of the oil cylinder or the motor passes through the control port K, the filter screen 20, the first damper 19, and the second damper 23 to push the valve core 5 to move rightward. At the same time, the valve core 5 compresses the spring 10 and moves to the second working position. The conical seal between the valve core 5 and the valve sleeve 4 is separated, and the pressure at the second working port B is greater than the pressure at the first working port A. At this time, the oil fluid at the dropping port of the oil cylinder or the motor flows to the first working port A through the second working port B, the throttling groove of the valve core 5, and the valve sleeve hole 41 on the valve sleeve 4, and the oil cylinder or the motor drives the heavy load to drop. When the valve core 5 moves rightward, the oil fluid in the spring cavity can be connected to the first working port A through the central hole 56, the throttling groove 55 on the valve core 5, and the valve sleeve hole 41 and discharged; by adjusting the setting screw 12, the compression amount of the spring 10 can be adjusted, so as to achieve different opening pressures of the balance valve.
[0052] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the protected content of the present application.
[0053] The above are only the preferred embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.
Claims
1. A direct-acting zero-leakage balance valve, characterized in that It includes a valve body, a valve sleeve, a valve core, a valve seat connected to the valve body, a check valve and a relief valve; The valve body is provided with a control port K, a first working port A, a second working port B and a mounting hole for installing the valve sleeve. The control port K is communicated to the first end of the valve core. An elastic component for setting the opening pressure of the balance valve is arranged at the second end of the valve core. A spring cavity for installing the elastic component is arranged in the valve seat. The second working port B is respectively connected to the inlets of the check valve and the relief valve. The first working port A is respectively connected to the outlets of the check valve and the relief valve; The valve core includes a first end portion, a throttle groove portion, a conical sealing portion and a second end portion which are connected in sequence. The valve sleeve is relatively fixedly and sealingly installed in the mounting hole. The first end portion of the valve core is movably and sealingly installed in the first end portion of the valve sleeve. The second end portion of the valve core is movably and sealingly installed in the first end portion of the valve seat. A throttle groove is arranged between the throttle groove portion of the valve core and the valve sleeve. A separable conical sealing connection is formed between the conical sealing portion of the valve core and the inner wall of the second end of the valve sleeve to realize the connection or cut-off between the second working port B and the throttle groove. A valve sleeve hole for communicating the throttle groove with the first working port A is opened on the valve sleeve. The balance valve has at least a first working state, a second working state and a third working state, which respectively correspond to that the first working port A is unidirectionally conducted through the check valve to the second working port B, the first working port A and the second working port B are not conducted or the second working port B is communicated back to the first working port A through the relief valve, and the second working port B is communicated to the first working port A through the throttle groove and the valve sleeve hole in sequence.
2. The direct-acting zero-leakage balance valve according to claim 1, wherein, When the balance valve is in the first working state, the valve core is in the first working position and the pressure of the first working port A is greater than the pressure of the second working port B. The first working port A is unidirectionally conducted through the check valve to the second working port B, and the oil cylinder or the motor drives the heavy object to rise; When the balance valve is in the second working state, the valve core is in the first working position and the pressure of the first working port A is less than the pressure of the second working port B. The first working port A and the second working port B are not conducted. The oil cylinder or the motor remains stationary. When the pressure of the second working port B is greater than the set pressure, the relief valve opens. The second working port B is communicated back to the first working port A through the relief valve until the pressure of the second working port B is not greater than the set pressure, and the relief valve closes; When the balance valve is in the third working state, the valve core moves under the action of the oil fluid in the control port K to compress the elastic component and moves to the second working position and the pressure of the second working port B is greater than the pressure of the first working port A. The second working port B is communicated to the first working port A through the throttle groove and the valve sleeve hole in sequence, and the oil cylinder or the motor drives the heavy object to fall.
3. The direct-acting zero-leakage balance valve according to claim 2, characterized in that, The second end portion and the conical sealing portion of the valve core are provided with a central hole communicated with the spring cavity, and the central hole is communicated with the throttle groove of the valve core. When the valve core moves under the action of the oil fluid in the control port K, the oil fluid in the spring cavity is discharged to the first working port A through the central hole, the throttle groove and the valve sleeve hole of the valve core.
4. The direct-acting zero-leakage balance valve according to claim 1, characterized in that, The valve sleeve and the valve body are sealingly connected through a first O-ring and a second O-ring to separate the second working port B and the first working port A to ensure zero leakage; And / or, the circumferential direction between the first end of the spool and the valve sleeve is sealed by a first O-ring to separate the control port K and the first working port A; the circumferential direction between the second end of the spool and the valve seat is sealed by a second O-ring to separate the second working port B and the spring chamber of the valve seat, ensuring zero leakage.
5. The direct-acting zero-leakage balance valve according to claim 1, characterized in that, The elastic component includes a spring and an adjusting screw. The first end of the spring is connected to the second end of the spool, the second end of the spring abuts against the adjusting screw, and the adjusting screw is arranged in a sealed connection with an axially adjustable position at the second end of the valve seat for adjusting the compression amount of the spring.
6. The direct-acting zero-leakage balance valve according to claim 1, characterized in that, A damping component is arranged between the control port K and the spool. The damping component includes a filter screen, a first damper, a damping joint, an ED seal and a second damper. Among them, a filter screen and a first damper are installed at the inlet end of the damping joint. The damping joint is installed in the valve body through an ED seal in a sealed connection, and the outlet of the damping joint is communicated to the first end of the spool through the second damper.
7. The direct-acting zero-leakage balance valve according to claim 1, characterized in that When the spool is in the first working position, a conical seal is formed between the conical sealing part of the spool and the inner wall of the second end of the valve sleeve, and the second working port B is not communicated with the throttling groove of the spool. When the spool moves to the right under the action of the oil in the control port K and compresses the spring to be in the second working position, the conical seal between the spool and the inner wall of the second end of the valve sleeve is released, and the second working port B is communicated to the first working port A through the throttling groove of the spool and the valve sleeve hole on the valve sleeve in sequence.
8. The direct-acting zero-leakage balance valve according to claim 1, characterized in that, The bottom of the valve seat presses on the end face of the second end of the valve sleeve to fix the valve sleeve in the installation hole of the valve body.
9. The direct-acting zero-leakage balance valve according to claim 1, characterized in that, A limiting protrusion is further arranged on the outer circumference of the position near the conical sealing part at the second end of the spool. The outer diameter of the limiting protrusion is larger than the inner diameter of the first end of the valve seat and the inner diameter of the valve sleeve, and is used to limit the stroke of the spool through the valve seat.
10. The direct-acting zero-leakage balance valve according to claim 1, characterized in that, The spool hole in the valve sleeve for installing the spool and the spool are machined in one clamping.
11. A hydraulic system, characterized in that, It includes the direct-acting zero-leakage balance valve according to any one of claims 1-10.
12. The hydraulic system according to claim 11, wherein, It further includes an oil cylinder or motor falling control oil port, an oil cylinder or motor rising port, and an oil cylinder or motor falling port. The control port K is connected to the oil cylinder or motor falling control oil port, the first working port A is connected to the oil cylinder or motor rising port, and the second working port B is connected to the oil cylinder or motor falling port.