Multipurpose proportional control valve

Abstract

The invention relates to the technical field of proportional control valves, in particular to a multipurpose proportional control valve. The oil return valve comprises a valve block, an ascending module and a descending module are installed on the valve block, and the valve block is provided with a pressure oil channel used for oil feeding, a first oil return channel used for oil returning and a second oil return channel used for oil returning. The rising module comprises an electromagnetic rising proportional valve and a pressure compensation valve which are integrally installed, one end of the rising proportional valve is connected to a pressure oil channel, the other end of the rising proportional valve is connected to an execution channel used for being connected with an oil cylinder, and the rear portion of the rising proportional valve is connected with a one-way valve module; the descending module comprises an electromagnetic descending proportional valve, the outlet end of the descending proportional valve is connected to the second oil return channel, and the descending proportional valve is further provided with an overflow valve module in parallel. The ascending module, the descending module, the overflow valve module and the one-way valve module are designed in a combined mode, the structure is compact, and under the condition that the walking machine space is limited, whole machine arrangement is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of proportional control valves, and particularly to a multi-purpose proportional control valve. Background Art

[0002] Proportional control valves are common components in hydraulic systems, and their main function is to regulate the flow and pressure of hydraulic oil. For example, in agriculture and construction machinery, proportional control valves are mostly used to control the lifting, steering and other actions of oil cylinders. However, traditional proportional control valves, such as valve groups using cartridge valves and plate valves, usually have problems such as large volume and high requirements for installation space. Summary of the Invention

[0003] The purpose of the present invention is to provide a multi-purpose proportional control valve with reasonable design to solve the above-mentioned defects and deficiencies in the prior art.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: It includes a valve block, on which an ascending module and a descending module are installed. The valve block is respectively provided with a pressure oil passage for oil inlet, and two oil return passages, namely oil return passage one and oil return passage two, for oil return; the ascending module includes an electromagnetic ascending proportional valve and a pressure compensation valve, which are integrally installed. One end of the ascending proportional valve is connected to the pressure oil passage, and the other end is connected to an execution passage for connecting an oil cylinder. A check valve module is connected behind the ascending proportional valve; the descending module includes an electromagnetic descending proportional valve, the outlet end of the descending proportional valve is connected to the oil return passage two, and an overflow valve module is also installed in parallel with the descending proportional valve.

[0005] Preferably, the ascending proportional valve includes an ascending proportional electromagnet with a manual operation button connected to the rear of the valve block. The front end of the ascending proportional electromagnet is connected to an ascending spool pressure balance pin, which has an external thread. An ascending spool positioning seat is installed in the valve block by step positioning. The tail end of the ascending spool pressure balance pin also has a stepped structure, and an ascending spool spring is arranged at the front end of the step. The front end of the ascending spool spring abuts on the ascending spool positioning seat. An ascending spool is arranged at the front end of the ascending spool positioning seat. A guide pin is installed inside the front end of the ascending spool. Both the guide pin and the ascending spool are provided with internal threads and are installed on the ascending spool pressure balance pin by threads. The pressure oil passage in the valve block is arranged at the front end of the ascending spool. The outlet of the ascending proportional valve is arranged at the outer side of the middle part of the ascending spool. An oil return passage two is arranged at the position behind the outlet of the ascending proportional valve.

[0006] Preferably, the pressure compensation valve includes a positioning screw inserted into the valve block. The top of the positioning screw is disposed in the pressure oil passage. A pressure compensation valve plug is installed at the front end inside the valve block. A pressure compensation valve spool is installed inside the pressure compensation valve plug, and a pressure compensation valve spring is provided between the two. The rear end of the pressure compensation valve spool abuts against the positioning screw. An oil return passage 1 is disposed outside the pressure compensation valve spool. A pressure feedback throttle hole is provided at the rear end of the pressure compensation valve spool, and the pressure feedback throttle hole is connected to the outlet of the rising proportional valve.

[0007] Preferably, the descending proportional valve includes a descending proportional electromagnet with a manual operation button installed at the rear side of the valve block. A descending valve sleeve is installed inside the valve block at the front end of the descending proportional electromagnet. The front end of the descending proportional electromagnet is connected to a descending valve spool that can slide inside the descending valve sleeve. The execution passage is connected to the outside of the descending valve sleeve. The front end of the descending valve spool is then connected to the oil return passage 2. An oil groove is provided inside the descending valve spool, and the on-off of the execution passage and the oil return passage 1 and the size of the oil flow cross-section can be controlled through the oil groove by its movement. A descending speed adjusting rod is also installed on the valve block in front of the descending valve spool by means of a thread. The rear end of the descending speed adjusting rod is connected to a spring support, and a descending spring is provided between the spring support and the descending valve spool.

[0008] Preferably, the one-way valve module includes a one-way valve plug installed on the valve block. A one-way valve spool is provided inside the one-way valve plug, and a one-way valve spring is provided between the two. The chamber at the front end of the one-way valve spool is connected to the execution passage. A hole is opened in the one-way valve spool, and the hole communicates the execution passage with the spring chamber where the one-way valve spring is located.

[0009] Preferably, the overflow valve module includes an overflow valve plug installed on the valve block. An overflow valve conical spring is provided inside the overflow valve plug. An overflow valve small module is provided inside the overflow valve conical spring. The overflow valve small module includes an overflow valve spring support that fits behind the overflow valve conical spring. An overflow valve spool is installed inside the overflow valve spring support. An overflow valve spring is provided between the outside of the overflow valve spool and the overflow valve spring support. The rear end of the overflow valve spool is connected to an overflow valve sleeve by means of a thread. The spring chamber where the overflow valve spring is located is connected to the execution passage through a connection port opened in the valve block.

[0010] Preferably, a small hole communicating the front head and the outer tail end is opened in the rising valve spool pressure balance pin.

[0011] Preferably, a hexagonal center hole for controlling rotation is opened at the rear end of the overflow valve spool.

[0012] Preferably, a sealing nut is also provided at the opening on the valve block where the descending speed adjusting rod is installed. An internal hexagonal adjusting hole for adjustment is provided at the front end of the descending speed adjusting rod.

[0013] After adopting the above structure, the beneficial effects of the present invention are: 1. The present invention is used to control a single-acting oil cylinder to realize proportional control of the rise and fall of the oil cylinder. It can be used, for example, for the electric lifting of a tractor lifter and can control the tillage depth of the machine. It can also be used for the contour control of the mowing depth of a mowing robot, etc., and has a wide range of uses.

[0014] 2. The present invention combines the rising module, the descending module, the overflow valve module and the one-way valve module in a compact design. Compared with similar valve groups that use cartridge valves and plate valves to achieve this function, the volume is greatly reduced, which is convenient for the layout of the entire machine when the space of the mobile machinery is limited.

[0015] 3. The present invention has manual operation buttons for both the ascending and descending functions. In the special case that the electromagnet is not powered due to electrical failure or other reasons, manual operation can still be performed to ensure the reliability of control.

[0016] 4. The present invention designs a cone sealing structure of the one-way valve to ensure that the oil cylinder has no leakage when the proportional valve is in the middle position, avoids the oil cylinder from automatically sinking, and improves the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the external structure of the present invention; Figure 2 It is a bottom view of the present invention; Figure 3 is a front view of the present invention; Figure 4 is a top view of the present invention; Figure 5 It is a left side view of the present invention; Figure 6 It is a working principle diagram of the present invention; Figure 7 is a cross-sectional view of a one-way valve in the present invention; Figure 8 is an exploded view of the one-way valve of the present invention; Figure 9 is a cross-sectional view of the relief valve of the present invention; Figure 10 is an exploded view of the relief valve in the present invention; Figure 11 This is a hydraulic principle diagram of the present invention when controlling the oil cylinder to rise; Figure 12 is a cross-sectional view of the rising proportional valve in the present invention; Figure 13 It is an exploded view of the rising proportional valve in the present invention; Figure 14 is a cross-sectional view of a descending proportional valve in the present invention; Figure 15 This is the explosion diagram of the descending proportional valve in the present invention.

[0018] Description of reference numerals: 1. Pressure compensation valve; 2. Ascending proportional valve; 3. Descending proportional valve; 4. Check valve module; 5. Relief valve module; 6. Ascending module; 7. Descending module; 8. Pressure feedback throttle orifice 201. Pressure compensation valve plug; 202. Pressure compensation valve spring; 203. Pressure compensation valve spool; 204. Set screw; 205. Guide pin; 206. Ascending spool; 207. Ascending spool positioning seat; 208. Ascending spool spring; 209. Ascending spool pressure balance pin; 2010. Ascending proportional electromagnet 301. Sealing nut; 302. Descending speed adjusting rod; 303. Spring support; 304. Descending spring; 305. Descending spool; 306. Descending valve sleeve; 307. Descending proportional electromagnet 401. Check valve plug; 402. Check valve spring; 403. Check valve spool 501. Relief valve plug; 502. Relief valve conical spring; 503. Relief valve spring support; 504. Relief valve spring; 505. Relief valve spool; 506. Relief valve valve sleeve A. Execution channel; P. Pressure oil channel; T1. First oil return channel; T2. Second oil return channel; B. Ascending proportional valve outlet; α. Connection port Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] Refer to Figures 1 - 6 As shown, it includes a valve block, on which an ascending module 6 and a descending module 7 are installed. The valve block is respectively provided with a pressure oil channel P for oil inlet, and two oil return channels, namely the first oil return channel T1 and the second oil return channel T2, for oil return; the ascending module 6 includes an electromagnetic ascending proportional valve 2 and a pressure compensation valve 1, which are integrally installed. One end of the ascending proportional valve 2 is connected to the pressure oil channel P, and the other end is connected to an execution channel A for connecting an oil cylinder. A check valve module 4 is connected behind the ascending proportional valve 2; the descending module 7 includes an electromagnetic descending proportional valve 3. The outlet end of the descending proportional valve 3 is connected to the second oil return channel T2, and a relief valve module 5 is also installed in parallel with the descending proportional valve 3.

[0021] Refer toFigures 1 - 13 As shown in the figure, the rising proportional valve 2 includes a rising proportional electromagnet 2010 with a manual operation button connected to the rear of the valve block. The front end of the rising proportional electromagnet 2010 is connected to a rising valve core pressure balance pin 209. The rising valve core pressure balance pin 209 is provided with an external thread. Inside the valve block, a rising valve core positioning seat 207 is installed through step positioning. A stepped structure is also provided at the tail end of the rising valve core pressure balance pin 209, and a rising valve core spring 208 is arranged at the front end of the step. The front end of the rising valve core spring 208 abuts against the rising valve core positioning seat 207. A rising valve core 206 is arranged at the front end of the rising valve core positioning seat 207. A guide pin 205 is installed inside the front end of the rising valve core 206. Internal threads are opened in both the guide pin 205 and the rising valve core 206, and they are installed on the rising valve core pressure balance pin 209 through threads. The pressure oil passage P inside the valve block is arranged at the front end of the rising valve core 206. The outlet B of the rising proportional valve is arranged on the outer side of the middle part of the rising valve core 206. A second oil return passage T2 is arranged at the rear position of the outlet B of the rising proportional valve. A small hole communicating the front head and the outer tail end of the rising valve core pressure balance pin 209 is opened in the rising valve core pressure balance pin 209; The pressure compensation valve 1 includes a positioning screw 204 inserted into the valve block. The top end of the positioning screw 204 is arranged in the pressure oil passage P. A pressure compensation valve plug 201 is installed at the front end inside the valve block. A pressure compensation valve core 203 is installed inside the pressure compensation valve plug 201, and a pressure compensation valve spring 202 is arranged between the two. The rear end of the pressure compensation valve core 203 abuts against the positioning screw 204. The first oil return passage T1 is arranged on the outer side of the pressure compensation valve core 203. A pressure feedback throttle hole 8 is arranged at the rear end of the pressure compensation valve core 203. The pressure feedback throttle hole 8 is connected to the outlet B of the rising proportional valve.

[0022] Adopting a compact design, the pressure compensation valve core 203 is pressed towards the right to the positioning screw 204 by the elastic force of the pressure compensation valve spring 202, disconnecting the pressure oil passage P and the first oil return passage T1; The guide pin 205, the rising valve core 206, and the rising valve core pressure balance pin 209 form a moving module that moves together and is driven by the rising proportional electromagnet 2010. When the moving module moves back and forth, the rising valve core positioning seat 207 remains stationary, and the small hole in the rising valve core pressure balance pin 209 ensures the pressure balance on both its front and rear sides; The guide pin 205 and the rising valve core 206 are installed through threads, so their installation positions can also be adjusted during installation, thereby adjusting the compression amount of the rising valve core spring 208; When the rising proportional electromagnet 2010 is not energized, the pressure oil passage P and the outlet B of the rising proportional valve remain disconnected, and the outlet B of the rising proportional valve and the second oil return passage T2 remain connected; As Figure 2In the shown structure, when the proportional lift valve 2 is in the middle position, the oil circuit is as follows: the proportional lift solenoid 2010 is de-energized, the pressure oil in the pressure oil passage P pushes open the pressure compensation valve spool 203, the hydraulic oil flows towards the return oil passage T1, and the pressure feedback throttle orifice 8, the outlet B of the proportional lift valve, and the return oil passage T2 are connected. As the pressure in the spring chamber of the pressure compensation valve spool 203 drops until there is no pressure, the pressure in the pressure oil passage P is low; Combined with Figure 11 , when the proportional lift valve 2 ascends, the proportional lift solenoid 2010 is energized, the push rod pushes the above-mentioned movement module to move towards the left, opening the passage between the pressure oil passage P and the outlet B of the proportional lift valve. For the oil circuit between the outlet B of the proportional lift valve and the return oil passage T2, the pressure oil passes through the pressure oil passage P, passes through the outlet B of the proportional lift valve, then passes through the check valve module 4, and then reaches the lower chamber of the oil cylinder from the execution passage A of the valve block, causing the oil cylinder to rise. At this time, the pressure feedback throttle orifice 8 is connected to the outlet B of the proportional lift valve, and the pressure at the outlet B of the proportional lift valve is fed back to the spring chamber of the pressure compensation valve spool 203. When the pressure difference generated by the flow rate at the outlet B of the proportional lift valve is greater than the set pressure value of the pressure compensation valve spring 202, the pressure compensation valve spool 203 will move to the left, opening the oil circuit between the pressure oil passage P and the return oil passage T1, discharging the excess pressure oil, thereby realizing the adjustable rising speed of the oil cylinder. The proportional lift solenoid 2010 is equipped with a manual button, and it can still be manually operated in case of an electrical fault that causes the solenoid to be de-energized.

[0023] Refer to Figures 1 - 15 As shown, the proportional descent valve 3 includes a proportional descent solenoid 307 with a manual operation button installed at the rear side of the valve block. Inside the valve block at the front end of the proportional descent solenoid 307, a descent valve sleeve 306 is installed. The front end of the proportional descent solenoid 307 is connected to a descent valve spool 305 that can slide within the descent valve sleeve 306. The execution passage A is connected to the outside of the descent valve sleeve 306, and the front end of the descent valve spool 305 is connected to the return oil passage T2. An oil groove is provided inside the descent valve spool 305, and by its movement, the on-off of the execution passage A and the return oil passage T1 and the cross-sectional dimension of the oil flow can be controlled through the oil groove. On the valve block directly in front of the descent valve spool 305, a descent speed adjustment rod 302 is also installed by means of a thread. The rear end of the descent speed adjustment rod 302 is connected to a spring support 303. A descent spring 304 is provided between the spring support 303 and the descent valve spool 305. A sealing nut 301 is also provided at the opening on the valve block where the descent speed adjustment rod 302 is installed. The front end of the descent speed adjustment rod 302 is provided with an internal hexagonal adjustment hole for adjustment.

[0024] The descent speed adjustment rod 302 can be rotated through the adjustment hole at the front end, causing it to displace along the thread. When the descent speed adjustment rod 302 faces the rear end, that is Figure 14Among them, the greater the displacement generated towards the right, the greater the compression amount of the descending spring 304 caused by it through the spring support 303, and the smaller the opening degree of the descending valve core 305, thereby reducing the descending speed of the oil cylinder; When it is necessary to control the descent, the descending proportional solenoid valve 307 is energized, and the push rod pushes the descending spring 304 forward to open the passage between the execution channel A and the second oil return channel T2. The pressure oil in the lower chamber of the oil cylinder can then flow to the second oil return channel T2, and the oil cylinder starts to descend. During this process, the position of the descending valve core 305 determines the opening degree, which also controls the flow rate of the oil. Therefore, the current magnitude of the descending proportional solenoid valve 307 can control the descending speed of the oil cylinder to ensure adjustable proportion.

[0025] See Figures 1 - 8 As shown, the one-way valve module 4 includes a one-way valve plug 401 installed on the valve block. A one-way valve core 403 is provided inside the one-way valve plug 401, and a one-way valve spring 402 is provided between the two. The chamber where the front end of the one-way valve core 403 is located is connected to the execution channel A. A hole is opened in the one-way valve core 403, and the hole communicates the execution channel A with the spring chamber where the one-way valve spring 402 is located.

[0026] The main function of the one-way valve is for pressure holding. When both the ascending proportional valve 2 and the descending proportional valve 3 are in the right position (that is, when the proportional control valve is in the middle position), the pressure oil at the inlet of the one-way valve module 4 passes through the right position of the ascending proportional valve 2 and then is sent to the second oil return channel T2. The oil inlet of the one-way valve is connected to the oil return, and the pressure in the lower chamber of the oil cylinder enters the one-way valve core 403 through the execution channel A of the proportional control valve, that is, port A; due to the conical sealing structure of the one-way valve core 403, zero leakage of the pressure oil in the lower chamber of the oil cylinder can be ensured, so that the oil cylinder can stop at any position when the proportional control valve is in the middle position; During the working process, the one-way valve core 403 is pressed against the valve body conical surface under the action of the one-way valve spring 402. The hole in the center of the one-way valve leads the pressure oil at port A to the spring chamber of the one-way valve, forming a reliable pressure oil acting area. When the proportional control valve is in the middle position, the one-way valve core 403 forms a reliable sealing surface under the combined action of the pressure oil at port A, that is, in the lower chamber of the oil cylinder, and the one-way valve spring 402, ensuring that the leakage amount is basically zero and preventing the oil cylinder from automatically descending.

[0027] See Figures 1 - 10As shown in the figure, the overflow valve module 5 includes an overflow valve plug 501 installed on the valve block. Inside the overflow valve plug 501, there is an overflow valve conical spring 502. Inside the overflow valve conical spring 502, there is an overflow valve small module. The overflow valve small module includes an overflow valve spring support 503 that fits behind the overflow valve conical spring 502. Inside the overflow valve spring support 503, an overflow valve spool 505 is installed. Between the outside of the overflow valve spool 505 and the overflow valve spring support 503, there is an overflow valve spring 504. The rear end of the overflow valve spool 505 is threadedly connected to an overflow valve sleeve 506. The overflow valve small module is kept pressed against the valve body cone surface under the action of the overflow valve conical spring 502. The spring chamber where the overflow valve spring 504 is located is connected to the execution channel A through a connection port α opened in the valve block. The rear end of the overflow valve spool 505 is provided with a hexagonal center hole for controlling rotation. The part of the front end rod head of the overflow valve spool 505 that extends out of the overflow valve spring support 503 is welded to the overflow valve spring support 503 to form the overflow valve small module.

[0028] The hexagonal center hole at the tail of the overflow valve spool 505 can be rotated by a wrench, and then its front and rear positions can be adjusted to adjust the compression amount of the overflow valve spring 504. During use, when the pressure in the lower chamber of the oil cylinder exceeds the set pressure of the overflow valve, the oil pressure can drive the overflow valve spool 505 to overcome the resistance of the overflow valve spring 504 and move to the right, so that the valve port opens to relieve pressure, protect the safety of the oil cylinder, and prevent overload.

[0029] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundary of the appended claims, or equivalent forms of such scope and boundary.

Claims

1. A multi-purpose proportional control valve, which comprises a valve block, characterized in that: An ascending module (6) and a descending module (7) are installed on the valve block. A pressure oil passage (P) for oil inlet and two oil return passages, namely an oil return passage one (T1) and an oil return passage two (T2), are respectively provided on the valve block. The ascending module (6) includes an electromagnetic ascending proportional valve (2) and a pressure compensation valve (1), which are integrally installed. One end of the ascending proportional valve (2) is connected to the pressure oil passage (P), and the other end is connected to an execution passage (A) for connecting an oil cylinder. A check valve module (4) is connected behind the ascending proportional valve (2). The descending module (7) includes an electromagnetic descending proportional valve (3). The outlet end of the descending proportional valve (3) is connected to the oil return passage two (T2), and an overflow valve module (5) is also installed in parallel with the descending proportional valve (3). The check valve module (4) includes a check valve plug (401) installed on the valve block. A check valve spool (403) is provided inside the check valve plug (401), and a check valve spring (402) is provided between them. The chamber where the front end of the check valve spool (403) is located is connected to the execution passage (A). A hole is opened in the check valve spool (403), and the hole communicates the execution passage (A) with the spring chamber where the check valve spring (402) is located. The overflow valve module (5) includes an overflow valve plug (501) installed on the valve block. An overflow valve conical spring (502) is provided inside the overflow valve plug (501). An overflow valve small module is provided inside the overflow valve conical spring (502). The overflow valve small module includes an overflow valve spring seat (503) attached to the rear of the overflow valve conical spring (502). An overflow valve spool (505) is installed inside the overflow valve spring seat (503). An overflow valve spring (504) is provided between the outside of the overflow valve spool (505) and the overflow valve spring seat (503). The rear end of the overflow valve spool (505) is threadedly connected to an overflow valve sleeve (506). The spring chamber where the overflow valve spring (504) is located is connected to the execution passage (A) through a connection port (α) opened in the valve block.

2. The multi-purpose proportional control valve according to claim 1, characterized in that: The rising proportional valve (2) includes a rising proportional electromagnet (2010) with a manual operation button connected to the rear of the valve block. The front end of the rising proportional electromagnet (2010) is connected to a rising valve core pressure balance pin (209). The rising valve core pressure balance pin (209) is provided with an external thread. Inside the valve block, a rising valve core positioning seat (207) is installed by step positioning. A stepped structure is also provided at the tail end of the rising valve core pressure balance pin (209), and a rising valve core spring (208) is arranged at the front end of the step. The front end of the rising valve core spring (208) abuts against the rising valve core positioning seat (207). A rising valve core (206) is provided at the front end of the rising valve core positioning seat (207). A guide pin (205) is installed at the inner side of the front end of the rising valve core (206). Internal threads are opened in both the guide pin (205) and the rising valve core (206), and they are installed on the rising valve core pressure balance pin (209) through threads. The pressure oil passage (P) in the valve block is arranged at the front end of the rising valve core (206). The rising proportional valve outlet (B) is arranged at the outer side of the middle part of the rising valve core (206). A second oil return passage (T2) is arranged at the position behind the rising proportional valve outlet (B).

3. The multi-purpose proportional control valve according to claim 2, characterized in that: The pressure compensation valve (1) includes a positioning screw (204) inserted into the valve block. The top end of the positioning screw (204) is arranged in the pressure oil passage (P). A pressure compensation valve plug (201) is installed at the front end inside the valve block. A pressure compensation valve core (203) is installed inside the pressure compensation valve plug (201), and a pressure compensation valve spring (202) is arranged between them. The rear end of the pressure compensation valve core (203) abuts against the positioning screw (204). The first oil return passage (T1) is arranged at the outer side of the pressure compensation valve core (203). A pressure feedback throttle hole (8) is arranged at the rear end of the pressure compensation valve core (203), and the pressure feedback throttle hole (8) is connected to the rising proportional valve outlet (B).

4. A multi-purpose proportional control valve according to claim 1, characterized in that: The falling proportional valve (3) includes a falling proportional electromagnet (307) with a manual operation button installed at the rear side of the valve block. Inside the valve block at the front end of the falling proportional electromagnet (307), a falling valve sleeve (306) is installed. The front end of the falling proportional electromagnet (307) is connected to a falling valve core (305) that can slide inside the falling valve sleeve (306). The execution passage (A) is connected to the outer side of the falling valve sleeve (306). The front end of the falling valve core (305) is connected to the second oil return passage (T2). An oil groove is arranged inside the falling valve core (305). By its movement, the on-off of the execution passage (A) and the first oil return passage (T1) and the size of the oil flow cross-section can be controlled through the oil groove. A falling speed adjusting rod (302) is also installed on the valve block directly in front of the falling valve core (305) through threads. The rear end of the falling speed adjusting rod (302) is connected to a spring support (303), and a falling spring (304) is arranged between the spring support (303) and the falling valve core (305).

5. The multi-purpose proportional control valve according to claim 2, wherein: A small hole communicating the front head and the outer tail end is opened in the rising valve core pressure balance pin (209).

6. The multi-purpose proportional control valve according to claim 1, characterized in that: The rear end of the overflow valve spool (505) is provided with a hexagonal center hole for controlling rotation.

7. A multi-purpose proportional control valve according to claim 4, characterized in that: A sealing nut (301) is also provided at the opening on the valve block where the descending speed adjusting rod (302) is installed. The front end of the descending speed adjusting rod (302) is provided with an internal hexagonal adjusting hole for adjustment.

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