Hydraulic motor single overflow valve assembly structure
By adopting a single relief valve assembly structure in the hydraulic motor, sharing the relief channel and check valve design, the problems of high processing difficulty, high cost and low integration of the existing hydraulic motor relief protection and oil replenishment scheme are solved, achieving higher integration and reliability and reducing maintenance frequency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JINING BAILU HYDRAULIC MACHINERY CO LTD
- Filing Date
- 2026-03-09
- Publication Date
- 2026-04-10
AI Technical Summary
Existing overflow protection and oil replenishment solutions for hydraulic motors suffer from problems such as high processing difficulty, large space occupation, high cost, low integration, and inconsistent pressure, which can easily lead to impact and off-center load phenomena.
It adopts a single relief valve assembly structure, and integrates the relief channel and check valve inside the valve cover through the design of sharing the relief channel and check valve to realize oil circuit switching, reduce the number of relief valve assemblies, and add check valves for oil circuit switching. The shared relief channel and check valve reduce leakage points and have a higher degree of integration.
It reduces product costs, extends service life, reduces maintenance frequency, avoids impacts and off-center loads, and achieves higher integration and reliability.
Smart Images
Figure CN121828279A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of hydraulic motors, in particular to a single overflow valve assembly structure of a hydraulic motor. BACKGROUND
[0002] The hydraulic motor is a core executive element in the hydraulic system, and its essence is an energy conversion device for converting the pressure energy of liquid into rotary mechanical energy. It is often used as a power output component to drive various mechanical equipment to operate, and is widely used in the industrial field. In the working circuit of the hydraulic motor, the overflow valve assembly is a core pressure control element for ensuring reliable operation of the motor and maintaining stability of the system. When the hydraulic motor encounters sudden overload circuit pressure, the pressure will rise sharply, far exceeding the pressure limit of the motor and the pipeline. At this time, the overflow valve assembly directly leaks high-pressure oil back to the tank to avoid damage such as breakdown of the internal seal of the motor, breakage of the transmission shaft, and explosion of the shell, and also prevents high pressure from impacting the upstream hydraulic pump and other elements.
[0003] The current overflow protection and oil supplement schemes for bidirectional hydraulic motors mainly fall into two categories. One is to use two independent overflow valve assemblies corresponding to the two working chambers of the motor, respectively set the overload pressure in the forward and reverse directions, and additionally configure an independent oil supplement pump and an oil supplement one-way valve group for low-pressure side oil supplement. The other is to integrate the two overflow valve assemblies inside the motor valve cover, eliminating the external connecting pipeline. However, the machining difficulty of the overflow valve assembly is high, and it requires precise product cooperation during assembly. The above-mentioned first occupies a large installation space, which is not conducive to the miniaturization design of the whole machine. More importantly, the setting of multiple overflow valve assemblies is prone to inconsistent pressure. Since the spring pre-tightening force and wear degree of the overflow valve assembly are easily affected, when the bidirectional braking characteristics are unbalanced, impact and unbalanced load are easily caused. Therefore, the existing hydraulic motor still has deficiencies in the overflow protection and oil supplement process, and needs to be improved in the direction of low cost and high integration. SUMMARY
[0004] The purpose of the present application is to provide a single overflow valve assembly structure of a hydraulic motor, which solves the problems mentioned in the background art.
[0005] To achieve the above purpose, the present application provides the following technical scheme: a single overflow valve assembly structure of a hydraulic motor, comprising a valve body, a valve cover is arranged on the valve body, an overflow valve assembly is assembled on the valve body, a flow distribution disc, a plunger motor are further arranged in the valve body, a plunger on the plunger motor is connected to a nine-hole disc, a lotus output shaft is fixedly connected to the bottom of the nine-hole disc, two cavities A and B are arranged on the flow distribution disc; The surface of the valve cover is provided with oil passing port one and oil passing port two which are communicated with the A and B cavities respectively, the side surface of the valve body is further provided with two one-way valves one, the two one-way valves one are arranged in the A cavity and B cavity respectively, the output ends of the two one-way valves one are communicated through a channel one, the overflow valve assembly is communicated with a common overflow channel, the common overflow channel is communicated with the channel one, the two sides of the common overflow channel are provided with one-way valves two, the output ends of the two one-way valves two are communicated with the A and B cavities through a channel two respectively.
[0006] Optionally, the outer periphery of the oil passing port one and the oil passing port two is provided with a positioning installation hole, and a hydraulic oil pipe is fixedly installed through the positioning installation hole.
[0007] Optionally, the inner wall of the hydraulic oil pipe is fixedly connected with an intercepting net, the intercepting net is arranged in an inclined manner, and the intercepting net is provided with filtering components on the high and low sides.
[0008] Optionally, the filtering component comprises a cavity one provided in the inner wall of the hydraulic oil pipe, a partition plate is slidably connected to the inner wall of the cavity one, the partition plate is matched with the cavity one, an electromagnetic driver is embedded in the hydraulic oil pipe, the output end of the electromagnetic driver is fixedly connected to the end of the partition plate, and a sealing ring is embedded in the inner wall of the cavity one, the sealing ring is installed on the outer side of the output end of the electromagnetic driver.
[0009] Optionally, the hydraulic oil pipe is rotatably connected with a signal identification plate through a torsion spring, the signal identification plate is opposite to the inclined direction of the intercepting net, an inductive chip is arranged in the signal identification plate, and an inductive assembly corresponding to the inductive chip is arranged in the electromagnetic driver.
[0010] Optionally, a drip filter plate is slidably connected to the inner wall of the hydraulic oil pipe and the cavity one, a cavity two is provided in the inner wall of the hydraulic oil pipe and communicated with the cavity one, the cavity two extends into the hydraulic oil pipe, an arc-shaped closing plate is arranged on the inner wall of the cavity two, the communication state of the cavity one and the cavity two is changed through the arc-shaped closing plate, and an arc-shaped groove matched with the arc-shaped closing plate is provided in the inner wall of the hydraulic oil pipe.
[0011] Optionally, a disc is fixedly connected to the end of the drip filter plate, a circular ring is rotatably connected to the outer periphery of the disc, and the surface of the arc-shaped closing plate is fixedly connected with the circular ring.
[0012] Optionally, two magnetites are embedded in the inner wall of the hydraulic oil pipe, two inductive iron sheets corresponding to the magnetites are embedded on the surface of the circular ring, an operating handle is fixedly connected to the surface of the circular ring, and anti-skid lines are provided on the surface of the operating handle.
[0013] Compared with the prior art, the present application has the following advantages: I. Since the overflow valve assembly is difficult to process, precise product matching is required. The present application adjusts the oil path structure of the hydraulic motor, adopts a single overflow valve assembly structure, the motor oil return shares a common overflow channel, and the oil path switching is realized by increasing the one-way valve, thereby realizing the working switching process of the single overflow valve assembly, reducing the demand for the number of overflow valve assemblies, and greatly reducing the cost of the product. By directly integrating the rectification oil path and the common overflow path in the casting flow channel of the valve cover, the one-way valve and the overflow valve share the same integrated flow channel, thereby further reducing the number of plug-in joints and sealing elements, the leakage points are fewer than those of the prior art, and the overall integration degree is higher.
[0014] II. The present application can recycle and process the residual metal iron filings in the hydraulic oil regardless of the working state of the plunger motor, greatly improves the service life of the product, and through the special setting of the inclined state, the area of the interception net is increased, the probability of the interception net being blocked is reduced to a certain extent, and the number of cleaning and maintenance is reduced.
[0015] III. When the present application needs to collect and maintain the intercepted iron filings, the hydraulic oil around the iron filings can be greatly reduced in advance, so that the hydraulic oil is not scattered on the ground when the drip plate is pulled out subsequently, and through the setting of the inductive iron sheet and the magnetite, the step of missing this step during operation can be avoided, so that the maintenance steps of the hydraulic motor are more standardized. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 is the first axonometric view of the present application; Figure 2 is the second axonometric view of the present application; Figure 3 is the first sectional view of the present application from the front view angle; Figure 4 is the sectional view of the present application from the right view angle; Figure 5 is the first sectional view of the present application from the right side top view angle; Figure 6 is the second sectional view of the present application from the right side top view angle; Figure 7 is the second sectional view of the present application from the front view angle; Figure 8 is the schematic view of the hydraulic oil pipe structure of the present application; Figure 9 is the positional relationship diagram of the interception net and the hydraulic oil pipe of the present application; Figure 10 is the first sectional view of the present application from the front view angle; Figure 9 is the enlarged view of structure A in the present application; Figure 11 A schematic diagram of the constraint of the ring of the present application; Figure 12 A hydraulic schematic diagram of the present application.
[0017] In the figure: 1, valve body; 2, valve cover; 3, overflow valve assembly; 4, flow distribution disc; 5, plunger motor; 6, nine-hole disc; 7, lotus output shaft; 8, oil passage one; 9, oil passage two; 10, one-way valve one; 11, passage one; 12, shared overflow passage; 13, one-way valve two; 14, passage two; 15, positioning mounting hole; 16, hydraulic oil pipe; 17, intercepting net; 18, cavity one; 19, isolation plate; 20, electromagnetic driver; 21, sealing ring; 22, signal identification plate; 23, trickling filter plate; 24, cavity two; 25, arc-shaped closing plate; 26, disc; 27, ring; 28, magnetite; 29, inductive iron sheet; 30, operating handle. DETAILED DESCRIPTION
[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.
[0019] Embodiment one, please refer to Figures 1 to 7 , Figure 12 The present application provides a single overflow valve assembly structure of a hydraulic motor, comprising a valve body 1, a valve cover 2 is arranged on the valve body 1, an overflow valve assembly 3 is assembled on the valve body 1, a flow distribution disc 4 and a plunger motor 5 are further arranged in the valve body 1, a plunger on the plunger motor 5 is connected to a nine-hole disc 6, a lotus output shaft 7 is fixedly connected to the bottom of the nine-hole disc 6, two cavities A and B are arranged on the flow distribution disc 4, an oil passage one 8 and an oil passage two 9 which respectively communicate with the two cavities A and B are formed in the surface of the valve cover 2, hydraulic oil enters from the oil passage one 8, passes through the cavity A of the flow distribution disc 4, enters a bottom cavity of the plunger at a corresponding position on the plunger motor 5, pushes the plunger outward, and the head of the plunger is tightly attached to the end surface of the inclined nine-hole disc 6, the reaction force of the nine-hole disc 6 on the plunger can be decomposed into two components, one of which is balanced with the hydraulic pressure at the bottom of the plunger in the direction of the plunger axis and does not generate a rotary torque, and the other of which is perpendicular to the plunger axis and generates a tangential torque on the central shaft of the plunger motor 5, thereby pushing the plunger motor 5 to rotate around the axis, when the plunger motor 5 rotates, the plunger which has done work will be turned to the position of the cavity B of the flow distribution disc 4, the plunger is pushed back into the cylinder body by the nine-hole disc 6, low-pressure oil is discharged from the cavity B and then from the oil passage two 9, and at the same time, the next plunger is turned to the position of the cavity A, and the above pushing process is repeated, so that the rotation is continued.
[0020] Since the size and pressure rating of the oil passage of the first oil passage 8 and the second oil passage 9 are the same, when steering is needed, only the input direction of the hydraulic oil is changed, that is, the first oil passage 8, which is the original oil inlet, becomes the oil return, and the second oil passage 9, which is the original oil return, becomes the oil inlet.
[0021] The side surface of the valve body 1 is further provided with two one-way valves 10, which are respectively arranged in the A cavity and the B cavity, and the output ends of the two one-way valves 10 are connected in communication through a channel 11. The overflow valve assembly 3 is connected in communication with a common overflow passage 12, the common overflow passage 12 is connected in communication with the channel 11, and the two sides of the common overflow passage 12 are provided with two one-way valves 13, and the output ends of the two one-way valves 13 are connected in communication with the A cavity and the B cavity through a channel 14, respectively.
[0022] In the embodiment, referring to the hydraulic schematic process shown in Figure 12 , when the normal forward rotation condition is met, the high-pressure oil enters the A cavity from the first oil passage 8, the plunger motor 5 drives the forward rotation, and the low-pressure oil after work flows out from the B cavity. At this time, the A cavity pressure is normal, the B cavity pressure is positive, the two one-way valves 10 are all cut off, and the oil only flows in the main circuit of the plunger motor 5. When the motor suddenly brakes, the A cavity pressure rises sharply, the one-way valve 10 at the A cavity is opened, the high-pressure oil flows into the channel 11, and then flows through the common overflow passage 12 to push the valve core of the overflow valve assembly 3 to open the pressure relief, and the high-pressure oil overflows to the common low-pressure cavity. At this time, the B cavity is in a negative pressure state, the one-way valve 13 at the B cavity is automatically conducted at this time, the oil overflowing to the low-pressure cavity directly supplements into the B cavity through the channel 14, avoids air erosion, realizes the weakening of the peak pressure, and the whole process is closed-loop buffering.
[0023] When the normal reverse rotation condition is met, the high-pressure oil enters the B cavity from the second oil passage 9, and drives the plunger motor 5 to reverse. At this time, the structure operation principle is the same as the above, the movement form is opposite to the above, the high-pressure oil also enters the common overflow passage 12 through the channel 11, and through the above process, the effect that both sides can overflow can be realized.
[0024] Since the overflow valve assembly 3 has a high machining difficulty and requires precise product matching, the structure adjusts the oil circuit structure of the hydraulic motor, adopts a single overflow valve assembly 3 structure, shares a common overflow passage 12, and realizes the working switching process of the single overflow valve assembly 3 through the oil circuit switching in the form of increasing the one-way valve, reduces the demand for the number of overflow valve assemblies 3, and greatly reduces the cost of the product.
[0025] In the embodiment, on the basis of the above embodiment: Please refer to Figure 1 , Figure 8 and Figure 9The outer periphery of the oil passing port one 8 and the oil passing port two 9 is provided with a positioning installation hole 15, and a hydraulic oil pipe 16 is fixedly installed through the positioning installation hole 15, the inner wall of the hydraulic oil pipe 16 is fixedly connected with an intercepting net 17, the intercepting net 17 is arranged in an inclined manner, and the intercepting net 17 is provided with a filtering component on both high and low sides.
[0026] In the embodiment, considering that the hydraulic oil rubs against the inner wall of the plunger motor 5 during the working of the plunger motor 5, metal debris is mixed in the hydraulic oil, which reduces the quality of the hydraulic oil and affects the working efficiency of the plunger motor 5 in the long run, the setting of the intercepting net 17 can intercept the metal impurities and avoid most of the impurities from entering the interior of the plunger motor 5 to damage the internal precision components and prolong the service life, and the special setting of the inclined state increases the area of the intercepting net 17 and reduces the probability of the clogging of the intercepting net 17 to some extent and reduces the number of cleaning and maintenance; Meanwhile, under the flow of the hydraulic oil, the iron filings impurities on the intercepting net 17 can be moved to the side of the intercepting net 17, as shown in Figure 9 If the flow direction of the hydraulic oil is from bottom to top, the iron filings are moved to the right upper side, if the flow direction of the hydraulic oil is from top to bottom, the impurities on the surface are pushed to the filtering component on the right lower side, the filtering component collects the iron filings impurities on the side, and such design can collect and process the impurities regardless of the working state of the plunger motor 5, that is, the plunger motor 5 is in forward rotation or reverse rotation.
[0027] In the embodiment, considering that the hydraulic oil rubs against the inner wall of the plunger motor 5 during the working of the plunger motor 5, metal debris is mixed in the hydraulic oil, which reduces the quality of the hydraulic oil and affects the working efficiency of the plunger motor 5 in the long run, the setting of the intercepting net 17 can intercept the metal impurities and avoid most of the impurities from entering the interior of the plunger motor 5 to damage the internal precision components and prolong the service life, the special setting of the inclined state increases the area of the intercepting net 17 and reduces the probability of the clogging of the intercepting net 17 to some extent and reduces the number of cleaning and maintenance; Please refer to Figure 9 and Figure 10 The filtering component comprises a cavity one 18 provided in the inner wall of the hydraulic oil pipe 16, the inner wall of the cavity one 18 is slidably connected with a partition plate 19, the partition plate 19 is matched with the cavity one 18, the hydraulic oil pipe 16 is embedded with an electromagnetic driver 20, the output end of the electromagnetic driver 20 is fixedly connected with the end of the partition plate 19, and the inner wall of the cavity one 18 is embedded with a sealing ring 21, the sealing ring 21 is installed on the outer side of the output end of the electromagnetic driver 20. In the embodiment, the start of the electromagnetic driver 20 can drive the partition plate 19 to be lowered, extended or retracted, when the partition plate 19 is extended, the cavity one 18 can be isolated, if the working state of the plunger motor 5 changes, this can avoid the collected iron filings from flowing out again and avoid damage again, since the hydraulic oil pipe 16 is rotatably connected with a signal identification plate 22 through a torsion spring, the signal identification plate 22 is opposite to the inclined direction of the intercepting net 17, the signal identification plate 22 is provided with a sensing chip, and the electromagnetic driver 20 is provided with a sensing assembly corresponding to the sensing chip.
[0028] from Figure 10It can be seen that when the flow direction of the hydraulic oil is from bottom to top, the signal recognition plate 22 opposite to the inclination direction of the intercepting net 17 is deflected at this time, that is, the signal recognition plate 22 is close to the electromagnetic driver 20, the internal sensing chip cooperates with the sensing assembly in the electromagnetic driver 20 at this time, and the electromagnetic driver 20 can be driven, that is, the isolation plate 19 is retracted at this time, and the cavity one 18 is in an open state. In this way, the signal recognition plate 22 on the other side is not matched with the position of the electromagnetic driver 20 due to the opening directly facing the hydraulic oil at this time, and the cavity one 18 on this side is in a closed state.
[0029] It should be emphasized that the electromagnetic driver 20 can also be started by manually connecting the control inductor, that is, the control state of the electromagnetic driver 20 is automatically changed according to the flow direction of the hydraulic oil.
[0030] In the fourth embodiment, based on the above-mentioned embodiments: Please refer to Figure 9 and Figure 10 , the drip filter plate 23 is slidably connected to the inner wall of the hydraulic oil pipe 16, the inner wall of the hydraulic oil pipe 16 is provided with a cavity two 24 in communication with the cavity one 18, the cavity two extends into the hydraulic oil pipe 16, the inner wall of the cavity two 24 is provided with an arc-shaped closing plate 25, the communication state between the cavity one 18 and the cavity two 24 is changed by the arc-shaped closing plate 25, and the inner wall of the hydraulic oil pipe 16 is provided with an arc-shaped groove matched with the arc-shaped closing plate 25. The end of the drip filter plate 23 is fixedly connected with a disc 26, the outer periphery of the disc 26 is rotatably connected with a circular ring 27, the surface of the arc-shaped closing plate 25 is fixedly connected with the circular ring 27, the inner wall of the hydraulic oil pipe 16 is embedded with two magnetites 28, the surface of the circular ring 27 is embedded with two sensing iron sheets 29 corresponding to the magnetites 28, the surface of the circular ring 27 is fixedly connected with an operation handle 30, and the surface of the operation handle 30 is provided with anti-skid lines.
[0031] In this embodiment: when the plunger motor 5 is not working, the hydraulic oil in the hydraulic oil pipe 16 can be pre-discharged first, and then the iron filings in the cavity one 18 are treated, at this time, the personnel need to rotate slightly after holding the operation handle 30, so that the circular ring 27 rotates, the sensing iron sheets 29 are dislocated from the magnetites 28, then the operation handle 30 can be normally pulled out, the disc 26 is pulled out through the circular ring 27, the drip filter plate 23 and the debris thereon are pulled out through the disc 26, and the debris can be normally collected. In the process of deflection of the circular ring 27, the arc-shaped closing plate 25 is deflected synchronously, because the arc-shaped closing plate 25 isolates the cavity two 24 from the cavity one 18 in the initial state, and after deflection, the two are in communication, at this time, the hydraulic oil mixed with the metal debris in the cavity one 18 flows into the hydraulic oil pipe 16 through the cavity two 24 and is discharged.
[0032] By the above manner, the hydraulic oil in the cavity can be greatly reduced in advance in each metal scrap cleaning process, avoiding the situation that the hydraulic oil at the opening is scattered on the ground when the filter plate is pulled out subsequently. Meanwhile, the setting of the induction iron sheet 29 and the magnetite 28 can avoid the omission of this step during the operation of the personnel, and the operation process is more standardized.
[0033] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.
Claims
1. A hydraulic motor single relief valve assembly structure, comprising a valve body (1), characterized in that: The valve body (1) is provided with a valve cover (2), the valve body (1) is equipped with an overflow valve assembly (3), the valve body (1) is also provided with a distribution plate (4), a plunger motor (5), the plunger on the plunger motor (5) is connected to a nine-hole plate (6), the bottom of the nine-hole plate (6) is fixedly connected with a lotus output shaft (7), and the distribution plate (4) is provided with two cavities A and B; The valve cover (2) has an oil passage port 1 (8) and an oil passage port 2 (9) that are respectively connected to cavities A and B. The valve body (1) also has two one-way valves 1 (10) on its side. The two one-way valves 1 (10) are respectively located in cavity A and cavity B. The output ends of the two one-way valves 1 (10) are connected through channel 1 (11). The overflow valve assembly (3) is connected to a common overflow channel (12). The common overflow channel (12) is connected to channel 1 (11). One-way valves 2 (13) are provided on both sides of the common overflow channel (12). The output ends of the two one-way valves 2 (13) are respectively connected to cavities A and B through channel 2 (14).
2. The hydraulic motor single relief valve assembly structure according to claim 1, characterized in that: Both the first oil outlet (8) and the second oil outlet (9) have positioning and mounting holes (15) on their outer periphery, and hydraulic oil pipes (16) are fixedly installed through the positioning and mounting holes (15).
3. The hydraulic motor single relief valve assembly structure according to claim 2, characterized in that: The inner wall of the hydraulic oil pipe (16) is fixedly connected to an interception net (17), which is inclined and has filter components on both the high and low sides.
4. The hydraulic motor single relief valve assembly structure according to claim 3, characterized in that: The filter component includes: A cavity (18) is formed on the inner wall of the hydraulic oil pipe (16). An isolation plate (19) is slidably connected to the inner wall of the cavity (18). The isolation plate (19) is adapted to the cavity (18). An electromagnetic actuator (20) is embedded in the hydraulic oil pipe (16). The output end of the electromagnetic actuator (20) is fixedly connected to the end of the isolation plate (19). A sealing ring (21) is embedded in the inner wall of the cavity (18). The sealing ring (21) is installed on the outside of the output end of the electromagnetic actuator (20).
5. The hydraulic motor single relief valve assembly structure according to claim 4, characterized in that: The hydraulic oil pipe (16) is rotatably connected to a signal recognition plate (22) via a torsion spring. The signal recognition plate (22) is tilted in the opposite direction to the interception net (17). A sensing chip is provided inside the signal recognition plate (22), and a sensing component corresponding to the sensing chip is provided inside the electromagnetic driver (20).
6. The hydraulic motor single relief valve assembly structure according to claim 4, characterized in that: The inner wall of the first cavity (18) and the inner wall of the hydraulic oil pipe (16) are slidably connected to a drip filter plate (23). The inner wall of the hydraulic oil pipe (16) is provided with a second cavity (24) that communicates with the first cavity (18). The second cavity (24) extends into the hydraulic oil pipe (16). The inner wall of the second cavity (24) is provided with an arc-shaped closing plate (25). The communication state between the first cavity (18) and the second cavity (24) is changed by the arc-shaped closing plate (25). The inner wall of the hydraulic oil pipe (16) is provided with an arc-shaped groove that matches the arc-shaped closing plate (25).
7. The hydraulic motor single relief valve assembly structure according to claim 6, characterized in that: The end of the drip filter plate (23) is fixedly connected to a disc (26), and a ring (27) is rotatably connected to the outer circumference of the disc (26). The arc-shaped closed plate (25) is fixedly connected to the surface of the ring (27).
8. The hydraulic motor single relief valve assembly structure according to claim 7, characterized in that: The inner wall of the hydraulic oil pipe (16) is embedded with two magnets (28), and the surface of the ring (27) is embedded with two sensing iron pieces (29) corresponding to the magnets (28). The surface of the ring (27) is fixedly connected with an operating handle (30), and the surface of the operating handle (30) is provided with anti-slip texture.