Slow closing control air valve

Abstract

This invention relates to the control of control valves on dump trucks, specifically a slow-descent control valve. The valve body has a lifting valve core housed within a lifting valve hole. The control cover has a position positioning groove corresponding to the work position and adapted to the lower end of the handle. The valve body has corresponding process through holes and working air ports. The descent valve hole contains, from top to bottom, a steel ball, a descent valve core, a descent core spring, and a second sealing plug assembly. The slow-descent valve hole contains, from top to bottom, a push rod, an air guide sleeve, a push rod spring, a reversing core sleeve, and a reversing core spring. The air inlet connects to the lower cavity of the lifting and descent valve holes via the process through holes. The lifting, descent, and slow-descent air ports connect to the corresponding working chambers via the process through holes. The exhaust ports connect to the upper part of the lifting, descent, and slow-descent valve holes and open out of the valve body. The cam handle has a slow-descent working surface and a lifting and descent working surface. This invention solves the problems of existing products being too large and unable to meet the needs of industry development, and has the advantages of compact structure and suitability for diverse installations.

Description

Technical Field

[0001] This invention relates to the control of control valves on dump trucks, and in particular to a slow-descent control valve. Background Technology

[0002] A utility model patent with patent number 201620467607.5 discloses a slow-descent reversing valve. Its main technical structure includes a hand control device mounted on the top of a cam rod, consisting of a handle and a handle ball. The handle is adapted to the working groove and position on the surface of the operating disc on the cam. The valve body is located below the cam, and its interior has a first valve hole and a second valve hole arranged longitudinally and at intervals. The lower ends of the first and second valve holes are respectively sealed with a first sealing plug and a second sealing plug. A lifting core is provided inside the second valve hole for lifting. The top of the lifting core is elastically pressed against the lower end of the cam and axially limited by the inner surface of the operating disc. The middle part of the lifting core is sealed to the inner wall of the second valve hole and has longitudinal air holes inside. Corresponding working air passages and working interfaces are respectively opened on the valve body. The work station includes a lifting work station, a stop positioning hole, a slow descent positioning hole, and a descent positioning hole that are sequentially spaced on the surface of the working groove. A pressure sleeve and a sealing core are sequentially arranged from top to bottom in the first valve hole. The pressure sleeve is hollow inside and axially limited by the inner surface of the operating disc. The pressure sleeve is sealed by the first sealing ring. The moving assembly is mounted on the upper part of the first valve hole. The upper part of the sealing top core is squeezed and sealed with the pressure sleeve and the lower end of the top core respectively. The top core is coaxially fitted in the internal cavity of the pressure sleeve and is sealed with the upper part of the pressure sleeve through the second sealing ring. A steel ball is provided between the top core and the bottom of the cam, and a spring is set between the top core and the sealing top core. A vent hole is opened through the inside of the sealing top core. The working air passage includes a lifting air passage, a lowering air passage, a slow lowering air passage, and an air inlet passage, which are opened on the valve body and are not interconnected. The inner end of the air inlet passage is connected to the first sealing plug and the first valve hole, and the second sealing plug and the first valve hole respectively. The sealing cavity formed by the second valve hole has the inner end of the lifting air passage connected to the second valve hole between the third sealing ring and the second sealing plug, the inner end of the descending air passage connected to the inner cavity of the first valve hole between the lower sealing ring and the first sealing plug, and the inner end of the slow descending air passage connected to the inner cavity of the first valve hole between the upper sealing ring and the lower sealing ring. The cam is provided with a first cam surface and a second cam surface corresponding to the steel ball and the pressure sleeve, wherein the first cam surface corresponds to the steel ball and is sandwiched between the spaced second cam surfaces, and the second cam surfaces correspond to both sides of the upper surface of the pressure sleeve.The main problems with the existing technology are as follows: First, the valve body is machined from aluminum profiles, and due to limitations in the profile forming process, the control cover cannot be designed for embedded installation, and its size is relatively large. Second, with changes in the application environment and the continuous improvement of customer demands, new requirements have been placed on the miniaturization, functional integration, and diversification of installation methods for valves. This necessitates reducing the external dimensions of components while ensuring that the components can still meet the requirements for long-term use, which is also the main direction for optimizing the product's structural design. Third, because the pressure sleeve, steel ball, and sealing core adopt a coaxial assembly design, the downward movement of the components is achieved through segmented downward movement. The function of switching between lowering and slow lowering, while meeting the requirements for accommodating internal components, results in a larger cross-sectional area of ​​the outer pressure sleeve. To overcome the downward driving force of the components due to air pressure, the friction loss between the cam and the pressure sleeve is increased. Fourth, the sealing top core moves upward under the action of the spring and achieves end face sealing with the lower end of the pressure sleeve. Since the spring does not have a guiding function, the sealing top core cannot guarantee the perpendicularity of the sealing surface during the movement, resulting in an ineffective sealing effect. Fifth, the forces acting on the pressure sleeve and the sealing top core are different. When pushing the handle, the uneven operating force will increase the difficulty of entering the corresponding working position, and slippage and misalignment due to sudden changes in force are likely to occur. Summary of the Invention

[0003] This invention provides a slow-descent control valve that achieves product miniaturization, diversified installation methods, good sealing reliability, easy operation, and high accuracy through structural optimization.

[0004] The overall technical structure of this invention is as follows:

[0005] The slow-descent control valve includes a handle ball mounted on the top of a cam handle lever. The valve body is located below the cam handle and has longitudinally distributed, parallelly spaced valve holes inside. A lifting valve core is located within the lifting valve hole. The top of the lifting valve core elastically presses against the lower end of the cam handle and is axially limited by an operating cover fixed to the valve body surface. A longitudinal air hole is opened in the middle cavity of the lifting valve core. A lifting core spring is located between the outer side of the lifting valve core and the boss in the inner cavity of the lifting valve hole, and a sealing component is provided at their adjacent portion. The operating cover has a position positioning groove corresponding to the work position and adapted to the lower end of the handle. A first sealing plug assembly is located at the bottom of the lifting valve hole. The valve body has corresponding process through holes and working air ports, including a lifting air port, a descent air port, a slow-descent air port, and an air inlet. It also includes the following structure:

[0006] A. From top to bottom, the lowering valve hole is provided with a steel ball, a lowering valve core, a lowering core spring, and a second sealing plug assembly. A lowering core spring is provided between the lowering valve core and the lower end boss of the lowering valve hole, and a sealing component is provided at the adjacent part of the two. The upper and lower surfaces of the steel ball are respectively in contact with the working surface of the cam handle and the top of the lowering valve core. From top to bottom, the slow lowering valve hole is provided with a push rod, an air guide sleeve, a push rod spring, a reversing core sleeve, and a reversing core spring. The top of the push rod is in contact with the working surface of the cam handle. The top of the air guide sleeve is positioned by the operating cover. A sealing component is provided at the adjacent part of the lower outer side of the air guide sleeve and the inner surface of the slow lowering valve hole. A push rod spring is provided between the push rod and the lower end boss of the air guide sleeve. A reversing core spring is provided between the lower outer side of the reversing core sleeve and the inner cavity of the slow lowering valve hole. A sealing component is provided at the adjacent part of the reversing core sleeve and the lower end of the air guide sleeve.

[0007] B. The air inlet is connected to the lower cavity of the lifting valve hole and the lowering valve hole through the air inlet process through hole. The lifting air inlet is connected to the inner cavity of the lifting valve hole located below the sealing component between the lifting valve core and the lifting valve hole through the lifting process through hole. The lowering air inlet is connected to the inner cavity of the lowering valve hole located below the sealing component between the lowering valve core and the lowering valve hole through the lowering process through hole. The slow lowering air inlet is connected to the inner cavity formed by the air guide sleeve, the reversing core sleeve and the slow lowering valve hole through the slow lowering process through hole. The inner cavity of the lowering valve hole located below the sealing component between the lowering valve core and the lowering valve hole and the cavity located below the sealing component between the reversing core sleeve and the air guide sleeve are connected through the slow lowering process through hole. The exhaust port is connected to the upper part of the lifting valve hole, the lowering valve hole and the slow lowering valve hole through the exhaust port process through hole and then opens to the body of the valve body.

[0008] C. The cam handle is provided with a slow descent working surface and a lifting and lowering working surface. The slow descent working surface corresponds to the steel ball, and the lifting and lowering working surface corresponds to the lifting valve core and the push rod.

[0009] The specific technical structure of the present invention includes:

[0010] To facilitate the adaptation of the control cover and the handle and to clearly distinguish the workstations, the preferred technical means is that the gear positioning slot on the control cover is adapted to the lower end of the handle, and the surface of the gear positioning slot is provided with a lifting position, a stop position, a slow descent position, and a descent position in sequence.

[0011] To achieve the effect of the lifting core spring on the lifting valve core, the preferred technical means is to place the lifting core spring between the upper part of the lifting valve core and the boss in the middle of the inner cavity of the lifting valve hole.

[0012] To facilitate safe self-locking after the handle is switched to a different working position, the preferred technical means is that the handle ball is fixed to the top of the cam handle by a cylindrical nut, a handle spring is fitted on the surface of the cam handle between the bottom of the handle ball and the handle, and a handle is slidably fitted on the outside of the cam handle.

[0013] The main function of the sealing components is to achieve separation to form different isolation cavities and complete different function switching. The preferred technical means is that the sealing components provided at the junction of the lowering valve core and the lowering valve hole, the sealing components provided at the junction of the lifting valve core and the lifting valve hole, and the sealing components provided at the junction of the outer side of the lower end of the air guide sleeve and the inner surface of the slow lowering valve hole are all made of first radial O-rings; a second radial O-ring is provided at the junction of the outer surface of the push rod and the reversing core sleeve; a third radial O-ring is provided at the bottom of the inner surface of the reversing core sleeve that is adapted to the tapered surface of the lower end of the push rod; and an axial O-ring is provided at the junction of the reversing core sleeve and the lower end of the air guide sleeve.

[0014] The preferred technical implementation of the control cover fixed to the valve body surface is that the control cover is fixed to the valve body surface by fixing screws.

[0015] To facilitate the fit between the cam handle and the control cover, meet the positioning requirements of the cam handle, and reduce the motion friction between the cam handle and adjacent components, the preferred technical means is to have the cylindrical pin pass through the rear ends of the cam handle and be assembled into the positioning slots in the inner cavity of the control cover.

[0016] To facilitate diverse installation options, a preferred technical approach is to provide side-mounted screw holes and embedded screw holes on the outer wall of the valve body.

[0017] To facilitate the arrangement of working air ports and the design of pipelines, the preferred arrangement of working air ports on the valve body is that the lifting air port, the lowering air port, the slow lowering air port, and the air inlet are located on the lower end face of the valve body.

[0018] The working principle of this invention is as follows:

[0019] Mid-stop state: The handle moves under the action of the handle spring, and the lower end of the handle enters the mid-stop slot of the gear positioning slot to lock. The first sealing plug assembly and the second sealing plug assembly are in a closed state. The lifting air port, slow lowering air port, and lowering air port are connected to the outside through the corresponding process through holes and exhaust ports. The pneumatic control reversing valve connected to the lifting air port, slow lowering air port, and lowering air port is in a mid-stop state when not subjected to external force.

[0020] Lifting state: Pull the handle up to the gear positioning slot to release the lock on the lower end of the handle, move the handle ball to the lifting position, the cam lifting and lowering working surface of the cam handle pushes the lifting valve core downward and pushes open the first sealing plug assembly, the inner cavity of the lifting valve hole is connected to the lifting air port through the lifting process through hole, and the compressed air acts on the pneumatic control reversing valve connected to the lifting air port to put it in the lifting state.

[0021] Slow descent state: Pull the handle up to the gear positioning slot to release the lock on the lower end of the handle, move the handle ball to the slow descent slot, the cam slow descent working surface of the cam handle pushes the descent valve core downward through the steel ball and pushes open the second sealing plug assembly. The inner cavity of the descent valve hole and the cavity below the sealing part of the reversing core sleeve and the slow descent valve hole are connected through the slow descent process through hole. The slow descent air port is connected through the slow descent process through hole to the inner cavity between the air guide sleeve and the sealing part between the reversing core sleeve and the inner surface of the slow descent valve hole. Therefore, the slow descent air port and the descent air port are simultaneously connected. When the slow descent piston and the reversing piston in the pneumatic reversing valve driven by it work at the same time, the pneumatic reversing valve is in slow descent.

[0022] Descending state: Pull the handle up to the gear positioning slot to release the lock on the lower end of the handle, move the handle ball to the descending slot, the cam of the cam handle lifts and the descending working surface pushes the push rod down, the conical surface at the bottom of the push rod seals with the third radial O-ring, at the same time the reversing core sleeve moves down, the axial O-ring between the reversing core sleeve and the air guide sleeve releases its sealing function, the slow descending air port is connected to the exhaust port through the slow descending process through hole, the slow descending piston in the pneumatic reversing valve loses pressure and resets, at this time the working state of the reversing piston remains unchanged, and the pneumatic reversing valve is in the descending state.

[0023] The essential features and significant technical advancements achieved by this invention are as follows:

[0024] 1. This invention optimizes the design by improving the stress conditions of components and the air circuit layout. It can effectively reduce the manual operation force and reduce the size of components while meeting the working requirements, thereby reducing the overall volume of the valve. This lays the foundation for diversified installation, miniaturization, and integration. At the same time, it can ensure the stability of the working state and reduce the mechanical wear of components, which is in line with the requirements of the product structure design optimization direction.

[0025] 2. This invention optimizes the structural design of the cam handle and the cam working surface, integrating the cam slow-descent working surface and the cam lifting and lowering working surface onto a single cam, making the structural design more compact while meeting functional requirements; the descent and slow-descent functions are achieved through two independent but interconnected cavities, simplifying the structural complexity of the functional cavities and improving the operational reliability of the components.

[0026] 3. This invention employs various sealing structures, including radial sealing, axial sealing, and conical sealing. The lifting valve core, lowering valve core, push rod, and reversing sleeve all adopt a guide sliding fit under radial sealing, which improves the effectiveness of radial sealing. At the same time, the reliability of axial sealing of components is achieved because the perpendicularity is guaranteed.

[0027] 4. In this invention, the lifting, lowering, slow descent, and mid-stop of the slow-descent control valve are achieved by relatively independent structures. When the corresponding structural components move in each working state, there is no obvious change in operating force. The corresponding work position switching is simple and not prone to misoperation.

[0028] 5. The present invention has a structural design with side-mounted screw holes and embedded screw holes on the outer wall of the valve body, which meets the needs of different assembly methods such as fixed plate and embedded installation, and provides design space for the improvement of the cab layout of engineering vehicles. Attached Figure Description

[0029] Figure 1 This is an external view of the present invention.

[0030] Figure 2 yes Figure 1 A bottom view.

[0031] Figure 3 yes Figure 1 Top view.

[0032] Figure 4 yes Figure 1 The left view.

[0033] Figure 5 yes Figure 1 AA view.

[0034] Figure 6 yes Figure 4 BB view.

[0035] Figure 7 yes Figure 6 The CC view.

[0036] Figure 8 yes Figure 6 FF view.

[0037] Figure 9 yes Figure 6 DD view.

[0038] Figure 10 yes Figure 6 EE view.

[0039] Figure 11 This is a diagram of the cam's outline.

[0040] Figure 12 yes Figure 10 The right view.

[0041] Figure 13 yes Figure 10 The left view.

[0042] Figure 14 This is a 3D view of the cam.

[0043] The reference numerals in the attached figures are as follows:

[0044] T-1, Lifting air inlet; T-1-1, Lifting process through hole; T-2, Slow descent air inlet; T-2-1, Slow descent process through hole; T-3, Descent air inlet; T-3-1, Descent process through hole; T-4, Air inlet; T-4-1, Air inlet process through hole; T-5, Side mounting screw hole; T-6, Exhaust port; T-6-1, Exhaust port process through hole; T-7, Mounting screw hole; T-8, Gear positioning slot; H-1, Cam slow descent working surface; H-2, Cam lifting and descent working surface; F-1, Lifting valve hole; F-2, Descent valve hole; F-3, Slow descent valve hole; M-1, First sealing group Components; M-2, Second sealing assembly; 1. Steel ball; 2. Lowering valve core; 3. Lowering core spring; 4. Handle ball; 5. Handle spring; 6. Handle; 7. Cam handle; 8. Control cover; 9. Valve body; 10. Cylindrical nut; 11. Cylindrical pin; 12. Lifting valve core; 13. Fixing screw; 14. Lifting core spring; 15A. First radial O-ring seal; 15B. Second radial O-ring seal; 15C. Third radial O-ring seal; 16. Reversing core spring; 17. Push rod; 18. Air guide sleeve; 19. Push rod spring; 20. Axial O-ring seal; 21. Reversing core sleeve. Detailed Implementation

[0045] The accompanying drawings illustrate embodiments of the present invention. The embodiments of the present invention will be further described below with reference to the accompanying drawings, but should not be construed as limiting the present invention. The scope of protection of the present invention is determined by the contents of the claims. Any equivalent technical means substitutions made in accordance with the specification do not depart from the scope of protection of the present invention.

[0046] The overall structure of this embodiment is shown in the figure. It includes a handle ball 8 mounted on the top of the cam handle 7, a valve body 9 located below the cam handle 7 with valve holes longitudinally distributed and spaced parallel inside, a lifting valve core 12 inside the lifting valve hole F-1, the top of the lifting valve core 12 elastically presses against the lower end of the cam handle 7 and is axially limited by an operating cover 8 fixed to the surface of the valve body 9, an air hole longitudinally opened in the middle of the inner cavity of the lifting valve core 12, a lifting core spring 14 between the outer side of the lifting valve core 12 and the inner cavity boss of the lifting valve hole F-1, and a sealing member is provided at the adjacent part of the two, a gear positioning groove T-8 corresponding to the work position and adapted to the lower end of the handle 6 is provided on the operating cover 8, a first sealing plug assembly M-1 is provided at the bottom of the lifting valve hole F-1, and corresponding process through holes and working air ports are opened on the valve body 9 respectively, the working air ports include lifting air port T-1, lowering air port T-3, slow lowering air port T-2, and air inlet T-4; it also includes the following structure:

[0047] A. Inside the descending valve hole F-2, from top to bottom, are arranged a steel ball 1, a descending valve core 2, a descending core spring 3, and a second sealing plug assembly M-2. A descending core spring 3 is located between the descending valve core 2 and the lower end boss of the descending valve hole F-2, and a sealing component is provided at their adjacent portion. The upper and lower surfaces of the steel ball 1 are respectively in contact with the working surface of the cam handle 7 and the top of the descending valve core 2. Inside the slow descending valve hole F-3, from top to bottom, are arranged a push rod 17, an air guide sleeve 18, a push rod spring 19, and a reversing core sleeve 21. The reversing core spring 16 is provided, wherein the top end of the push rod 17 is in contact with the working surface of the cam handle 7, the top of the air guide sleeve 18 is fixed by the operating cover 8, the lower outer side of the air guide sleeve 18 is provided with a sealing member adjacent to the inner surface of the slow descent valve hole F-3, the push rod spring 19 is provided between the push rod 17 and the lower boss of the air guide sleeve 18, the reversing core spring 16 is provided between the lower outer side of the reversing core sleeve 21 and the inner cavity of the slow descent valve hole F-3, and the lower adjacent part of the reversing core sleeve 21 and the air guide sleeve 18 is provided with a sealing member;

[0048] B. The air inlet T-4 is connected to the lower cavity of the lifting valve port F-1 and the lowering valve port F-2 through the air inlet process through-hole T-4-1. The lifting air inlet T-1 is connected to the inner cavity of the lifting valve port F-1, located below the sealing component between the lifting valve core 12 and the lifting valve port F-1, through the lifting process through-hole T-1-1. The lowering air inlet T-3 is connected to the inner cavity of the lowering valve port F-2, located below the sealing component between the lowering valve core 2 and the lowering valve port F-2, through the lowering process through-hole T-3-1. The slow lowering air inlet T-2 is connected to the slow lowering process... The through hole T-2-1 connects the inner cavity formed by the air guide sleeve 18, the reversing core sleeve 21 and the slow descent valve hole F-3. The inner cavity of the descent valve hole F-2, located below the sealing component between the descent valve core 2 and the descent valve hole F-2, is connected to the cavity located below the sealing component between the reversing core sleeve 21 and the air guide sleeve 18 through the slow descent process through hole T-2-1. The exhaust port T-6 opens outside the valve body 9 after being connected to the upper part of the lifting valve hole F-1, the descent valve hole F-2 and the slow descent valve hole F-3 through the exhaust port process through hole T-6-1.

[0049] C. The cam handle 7 is provided with a cam slow descent working surface H-1 and a cam lifting and lowering working surface H-2. The cam slow descent working surface H-1 corresponds to the steel ball 1, and the cam lifting and lowering working surface H-2 corresponds to the lifting valve core 12 and the push rod 17.

[0050] The gear positioning slot T-8 on the control cover 8 is adapted to the lower end of the handle 6. The surface of the gear positioning slot T-8 is provided with a lifting position, a stop position, a slow descent position, and a descent position in sequence.

[0051] The lifting core spring 14 is located between the upper part of the lifting valve core 12 and the boss in the middle of the inner cavity of the lifting valve hole F-1.

[0052] The handle ball 4 is fixed to the top of the cam handle 7 by the cylindrical nut 10. The handle spring 5 is fitted on the surface of the cam handle 7 between the bottom of the handle ball 4 and the handle 6. The handle 6 is fitted on the outer side of the cam handle 7.

[0053] The sealing components provided at the junction of the lowering valve core 2 and the lowering valve hole F-2, the sealing components provided at the junction of the lifting valve core 12 and the lifting valve hole F-1, and the sealing components provided at the junction of the outer side of the lower end of the air guide sleeve 18 and the inner surface of the slow lowering valve hole F-3 are all first radial O-ring seals 15A; the outer surface of the push rod 17 is provided at the junction with the reversing core sleeve 21 with a second radial O-ring seal 15B; the bottom of the inner surface of the reversing core sleeve 21 is provided with a third radial O-ring seal 15C that is adapted to the tapered surface of the lower end of the push rod 17; and the sealing components provided at the junction of the reversing core sleeve 21 and the lower end of the air guide sleeve 18 are axial O-ring seals 20.

[0054] The control cover 8 is fixed to the surface of the valve body 9 by fixing screws 13.

[0055] The cylindrical pin 11 passes through the cam handle 7 and its two ends are assembled into the positioning slots inside the control cover 8.

[0056] To facilitate diverse installation options, a preferred technical approach is to provide a side-mounted screw hole T-5 and an embedded screw hole T-7 on the outer wall of the valve body 9.

[0057] The lifting air port T-1, the lowering air port T-3, the slow lowering air port T-2, and the air inlet T-4 are located on the lower end face of the valve body 9.

Claims

1. A slow-descent control valve, including a handle ball (4) mounted on the top of a cam handle (7), a valve body (9) located below the cam handle (7) with valve holes longitudinally distributed and spaced parallel inside, wherein a lifting valve core (12) is provided in the lifting valve hole (F-1), the top of the lifting valve core (12) is elastically pressed against the lower end of the cam handle (7) and is axially limited by an operating cover (8) fixed to the surface of the valve body (9), and an air hole is longitudinally opened in the middle cavity of the lifting valve core (12), and the outer side of the lifting valve core (12) is connected to the lifting valve hole. (F-1) A lifting core spring (14) is provided between the inner cavity bosses and a sealing component is provided at the adjacent part of the two. The operating cover (8) is provided with a gear positioning slot (T-8) that corresponds to the work position and is adapted to the lower end of the handle (6). The bottom of the lifting valve hole (F-1) is provided with a first sealing plug assembly (M-1). The valve body (9) is provided with corresponding process through holes and working air ports. The working air ports include a lifting air port (T-1), a lowering air port (T-3), a slow lowering air port (T-2), and an air inlet (T-4). The feature is that: A. The lowering valve hole (F-2) is provided with a steel ball (1), a lowering valve core (2), a lowering core spring (3), and a second sealing plug assembly (M-2) from top to bottom. The lowering valve core (2) and the lower end boss of the lowering valve hole (F-2) are provided with a lowering core spring (3), and the adjacent part of the two is provided with a sealing component. The upper and lower surfaces of the steel ball (1) are respectively in contact with the working surface of the cam handle (7) and the top of the lowering valve core (2). The slow lowering valve hole (F-3) is provided with a push rod (17), an air guide sleeve (18), a push rod spring (19), and a reversing core sleeve (21) from top to bottom. A reversing core spring (16) is provided, wherein the top end of the push rod (17) is in contact with the working surface of the cam handle (7), the top of the air guide sleeve (18) is positioned by the operating cover (8), a sealing component is provided at the junction of the lower outer side of the air guide sleeve (18) and the inner surface of the slow-descent valve hole (F-3), a push rod spring (19) is provided between the push rod (17) and the lower boss of the air guide sleeve (18), a reversing core spring (16) is provided between the lower outer side of the reversing core sleeve (21) and the inner cavity of the slow-descent valve hole (F-3), and a sealing component is provided at the junction of the reversing core sleeve (21) and the lower end of the air guide sleeve (18); B. The air inlet (T-4) is connected to the lower cavity of the lifting valve hole (F-1) and the lowering valve hole (F-2) through the air inlet process through hole (T-4-1). The lifting air inlet (T-1) is connected to the inner cavity of the lifting valve hole (F-1) located below the sealing component between the lifting valve core (12) and the lifting valve hole (F-1) through the lifting process through hole (T-1-1). The lowering air inlet (T-3) is connected to the inner cavity of the lowering valve hole (F-2) located below the sealing component between the lowering valve core (2) and the lowering valve hole (F-2) through the lowering process through hole (T-3-1). The slow lowering air inlet (T-2) is connected to the lowering process through hole (T-3-1). The hole (T-2-1) connects to the inner cavity formed by the air guide sleeve (18), the reversing core sleeve (21) and the slow descent valve hole (F-3). The inner cavity of the descent valve hole (F-2) located below the sealing member between the descent valve core (2) and the descent valve hole (F-2) is connected to the cavity located below the sealing member between the reversing core sleeve (21) and the air guide sleeve (18) through the slow descent process through hole (T-2-1). The exhaust port (T-6) is connected to the upper part of the lifting valve hole (F-1), the descent valve hole (F-2) and the slow descent valve hole (F-3) through the exhaust port process through hole (T-6-1) and opens to the outside of the valve body (9). C. The cam handle (7) is provided with a cam slow descent working surface (H-1) and a cam lifting and lowering working surface (H-2). The cam slow descent working surface (H-1) corresponds to the steel ball (1), and the cam lifting and lowering working surface (H-2) corresponds to the lifting valve core (12) and the push rod (17).

2. The slow-descent control valve according to claim 1, characterized in that... The gear positioning slot (T-8) on the control cover (8) is adapted to the lower end of the handle (6). The surface of the gear positioning slot (T-8) is provided with a lifting position, a stop slot, a slow descent slot and a descent slot in sequence.

3. The slow-descent control valve according to claim 1, characterized in that... The lifting core spring (14) is located between the upper part of the lifting valve core (12) and the boss in the middle of the inner cavity of the lifting valve hole (F-1).

4. The slow-descent control valve according to claim 1, characterized in that... The handle ball (4) is fixed to the top of the cam handle (7) by the cylindrical nut (10). The handle spring (5) is fitted on the surface of the cam handle (7) between the bottom end of the handle ball (4) and the handle (6). The handle (6) is fitted on the outside of the cam handle (7).

5. The slow-descent control valve according to claim 1, characterized in that... The sealing components provided at the junction of the lowering valve core (2) and the lowering valve hole (F-2), the sealing components provided at the junction of the lifting valve core (12) and the lifting valve hole (F-1), and the sealing components provided at the junction of the outer side of the lower end of the air guide sleeve (18) and the inner surface of the slow lowering valve hole (F-3) are all first radial O-ring seals (15A); the outer surface of the push rod (17) is provided at the junction of the reversing core sleeve (21), the second radial O-ring seal (15B) is provided, the bottom of the inner surface of the reversing core sleeve (21) is provided with a third radial O-ring seal (15C) that is adapted to the tapered surface of the lower end of the push rod (17), and the sealing components provided at the junction of the reversing core sleeve (21) and the lower end of the air guide sleeve (18) are axial O-ring seals (20).

6. The slow-descent control valve according to claim 1, characterized in that... The control cover (8) is fixed to the surface of the valve body (9) by fixing screws (13).

7. The slow-descent control valve according to claim 1, characterized in that... The cylindrical pin (11) passes through the cam handle (7) and its two ends are fitted into the positioning slots inside the operating cover (8).

8. The slow-descent control valve according to claim 1, characterized in that... A side-mounted screw hole (T-5) and an embedded screw hole (T-7) are provided on the outer side wall of the valve body (9).

9. The slow-descent control valve according to claim 1, characterized in that... The lifting air port (T-1), lowering air port (T-3), slow lowering air port (T-2), and air inlet (T-4) are located on the lower end face of the valve body (9).

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