Plunger pump with low-pressure-maintaining overflow valve

Abstract

The utility model relates to the technical field of high-pressure cleaning machines, in particular to a plunger pump with a low-pressure-maintaining overflow valve, which comprises a pump cover and a pump body, a water inlet channel, a water outlet channel, an overflow channel and a main valve are arranged in the pump cover, the water outlet channel is communicated with the overflow channel, the overflow valve is arranged in the overflow channel, and the main valve is communicated with the water outlet channel. A low-pressure one-way valve, a high-pressure one-way valve and a plunger cavity are arranged in the pump body, the plunger cavity is arranged between the low-pressure one-way valve and the high-pressure one-way valve, a plunger is arranged in the plunger cavity, a first communication cavity is arranged between the low-pressure one-way valve and the water inlet channel, and a second communication cavity is arranged between the high-pressure one-way valve and the main valve. The overflow channel is communicated with the first communication cavity through the first pressure relief hole and communicated with the second communication cavity through the second pressure relief hole. According to the plunger pump, when the water gun is closed, pressure relief can be conducted on water in the second communication cavity, then the overall performance of the plunger pump can be improved, and the service life of the plunger pump can be prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of high-pressure cleaners, in particular to a plunger pump with a low-pressure overflow valve. Background Art

[0002] A high-pressure cleaner refers to a cleaning device that pressurizes water through a high-pressure water conversion device (generally a high-pressure plunger pump) through several levels to make its pressure reach more than several hundred atmospheric pressures, and then shoots out through a high-pressure water gun.

[0003] The plunger pump is an important part of the high-pressure cleaner. The plunger pump includes a pump cover and a pump body. The pump cover is provided with a water inlet channel, a water outlet channel, an overflow channel and a main valve. The water outlet channel is communicated with the overflow channel. An overflow valve is also arranged in the overflow channel. A low-pressure check valve, a high-pressure check valve and a plunger cavity are arranged in the pump body. A plunger is arranged in the plunger cavity. A first communication cavity is arranged between the low-pressure check valve and the water inlet channel. A second communication cavity is arranged between the high-pressure check valve and the main valve. And the overflow channel is communicated with the first communication cavity through a first pressure relief hole. In the prior art, when the water gun of the high-pressure cleaner is opened, the water flow direction is the water inlet channel, the first communication cavity, the low-pressure check valve, the plunger cavity, the high-pressure check valve, the second communication cavity, the main valve and the water outlet channel. When the water gun of the high-pressure cleaner is closed, at this time, the water pressure in the water outlet channel is relatively high, the main valve will be closed and the overflow valve in the overflow channel will be opened at the same time. Then the water flow in the water outlet channel is guided to the water inlet channel through the overflow channel and the first pressure relief hole to realize pressure relief. However, when the water gun is closed, the water pressure in the second communication cavity is also relatively high, but the prior art cannot relieve the pressure of this part of the water pressure, so it may affect the overall performance and service life of the plunger pump. Content of the Utility Model

[0004] The technical solution to be solved by the utility model is: to provide a plunger pump with a low-pressure overflow valve, which can relieve the pressure of the water in the second communication cavity when the water gun is closed, thereby improving the overall performance and service life of the plunger pump.

[0005] The technical solution adopted by the present utility model is: a plunger pump with a low-pressure overflow valve, including a pump cover and a pump body. An inlet channel, an outlet channel, an overflow channel, and a main valve are arranged inside the pump cover. The outlet channel is communicated with the overflow channel, and an overflow valve is arranged inside the overflow channel. A low-pressure check valve, a high-pressure check valve, and a plunger chamber are arranged inside the pump body. The plunger chamber is arranged between the low-pressure check valve and the high-pressure check valve. A plunger is arranged inside the plunger chamber. A first communication chamber is arranged between the low-pressure check valve and the inlet channel. A second communication chamber is arranged between the high-pressure check valve and the main valve. The overflow channel is communicated with the first communication chamber through a first pressure relief hole. The overflow channel is communicated with the second communication chamber through a second pressure relief hole. And the overflow valve includes a push rod seat, a push rod, a sealing ring, a steel ball, a push rod, a spring, and a micro switch. The push rod seat is arranged inside the overflow channel. A push rod chamber and a push rod cavity are arranged inside the push rod seat. The push rod chamber and the push rod cavity are communicated through a communication hole. A first connection hole and a second connection hole communicated with the push rod chamber are arranged on the push rod seat corresponding to the push rod chamber, and both the first connection hole and the second connection hole are communicated with the second pressure relief hole. A third connection hole communicated with the push rod cavity is arranged on the push rod seat corresponding to the push rod cavity. The third connection hole is communicated with the first pressure relief hole. The push rod is arranged inside the push rod chamber. An installation groove is arranged at the front end of the push rod. The sealing ring is arranged inside the installation groove and is hermetically matched with the wall of the push rod chamber. The push rod is arranged inside the push rod cavity. The steel ball is arranged at the front end of the push rod, and the steel ball is hermetically matched with the communication hole. The micro switch is located behind the push rod. The spring is sleeved on the push rod and applies a thrust to the push rod.

[0006] When in the normal working state, the outlet of the outlet channel is opened, the main valve is opened, and the water pressure received at the front end of the push rod is less than the thrust applied by the spring. At this time, the communication hole is blocked and sealed by the steel ball, so that the push rod chamber and the push rod cavity are separated, and the sealing ring is hermetically matched with the wall of the push rod chamber, so that the outlet channel and the push rod chamber are separated. At the same time, the micro switch is in an untriggered state.

[0007] When in the state of gun closing and backwashing, the outlet of the outlet channel is closed, the main valve is closed, and the water pressure received at the front end of the push rod is greater than the thrust applied by the spring. At this time, the push rod, the steel ball, and the push rod are pushed backward together. The first connection hole is communicated with the outlet channel, so that the outlet channel and the push rod chamber are conducted. The communication hole is conducted, so that the push rod chamber and the push rod cavity are conducted. At the same time, the micro switch is in a triggered state.

[0008] When in the state of gun closing and maintaining shutdown, the outlet of the outlet channel is closed, the main valve is closed, and the water pressure received at the front end of the push rod is less than the thrust applied by the spring. The push rod, the steel ball, and the push rod are pushed forward together until the sealing ring is hermetically matched with the first connection hole and the communication hole is conducted. At this time, the outlet channel and the push rod chamber are separated, the push rod chamber and the push rod cavity are conducted, and the micro switch is in a triggered state.

[0009] Preferably, three annular grooves are sequentially arranged on the outer side of the push rod seat corresponding to the push rod cavity, namely a first annular groove, a second annular groove and a third annular groove. Sealing elements are arranged on both the first annular groove and the third annular groove. The second annular groove forms a depression towards the first annular groove. A first connection hole is arranged at the bottom of the depression. A second connection hole is arranged at the bottom of the second annular groove. Both the first connection hole and the second connection hole communicate with the second pressure relief hole.

[0010] Preferably, the diameter of the part of the first connection hole close to the push rod cavity is smaller than the diameter of the part far from the push rod cavity.

[0011] Preferably, an installation cavity is arranged on the pump cover. The main valve is installed in the installation cavity. Both the water outlet channel and the second communication cavity communicate with the installation cavity. When the main valve is opened, the second communication cavity communicates with the water outlet channel. When the main valve is closed, the second communication cavity is cut off from the water outlet channel.

[0012] Preferably, the main valve includes a plug. One side of the installation cavity communicates with the second communication cavity, and the other side of the installation cavity is sealed by the plug.

[0013] Preferably, a first circular closed loop, a second circular closed loop and a triangular closed loop are arranged on the side of the pump cover close to the pump body. The first circular closed loop is arranged on the outer ring of one side of the installation cavity. The second circular closed loop is sleeved outside the first circular closed loop. The triangular closed loop is sleeved outside the second circular closed loop. The space between the second circular closed loop and the triangular closed loop belongs to the first communication cavity, and the first pressure relief hole is located between the second circular closed loop and the triangular closed loop. The space between the first circular closed loop and the second circular closed loop belongs to the second communication cavity, and the second pressure relief hole is located between the first circular closed loop and the second circular closed loop.

[0014] Compared with the prior art by adopting the above structure, the utility model has the following advantages: a second pressure relief hole is arranged, so that when the gun is closed, the water flow in the second communication cavity can be relieved through the second pressure relief hole, so that the pressure in the second communication cavity will be greatly reduced, improving the overall performance and service life of the plunger pump. And because the second pressure relief hole is arranged, when in the state of gun closing and standby shutdown, the water pressure in the second communication cavity will be balanced with the water pressure in the water outlet channel together with the thrust of the spring, so that the thrust of the spring itself does not need to be very large, thus saving a part of cost as a whole. And the overflow valve adopting this structure can also well realize the switching of three states.

[0015] Sealed by two sealing elements, so that the second pressure relief hole can be well sealed with other places and can only communicate with the push rod cavity through the first connection hole and the second connection hole.

[0016] Setting the main valve in the installation cavity can well achieve the on-off control between the second communication cavity and the water outlet channel.

[0017] The other side of the installation cavity is sealed by a plug. In this way, the plug can be opened when installing the main valve, and the plug is installed after the installation is completed, so the overall installation is more convenient.

[0018] Partially setting the first communication cavity and the second communication cavity on the pump cover can facilitate the opening of the first pressure relief hole and the second pressure relief hole, and the processing is more convenient. Brief Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of a plunger pump with a low-pressure overflow valve.

[0020] Figure 2 It is a cross-sectional view of a plunger pump with a low-pressure overflow valve from a perspective in a normal working state.

[0021] Figure 3 It is a cross-sectional view of a plunger pump with a low-pressure overflow valve from a perspective in a gun-closing and back-flushing state.

[0022] Figure 4 It is a cross-sectional view of a plunger pump with a low-pressure overflow valve from a perspective in a gun-closing and pressure-holding and shutdown state.

[0023] Figure 5 It is a cross-sectional view of a plunger pump with a low-pressure overflow valve from another perspective.

[0024] Figure 6 It is a schematic structural diagram of the pump cover in a plunger pump with a low-pressure overflow valve.

[0025] Figure 7 It is a schematic structural diagram of the push rod seat in a plunger pump with a low-pressure overflow valve.

[0026] Figure 8 It is a schematic structural diagram of the ejector rod in a plunger pump with a low-pressure overflow valve.

[0027] Figure 9 It is a front view of the pump body in a plunger pump with a low-pressure overflow valve.

[0028] Figure 10 It is a rear view of the pump body in a plunger pump with a low-pressure overflow valve.

[0029] As shown in the figure: 1. Pump cover; 2. Pump body; 3. Water inlet channel; 4. Water outlet channel; 5. Overflow channel; 6. Main valve; 7. Overflow valve; 8. Low-pressure check valve; 9. High-pressure check valve; 10. Plunger cavity; 11. First communication cavity; 12. Second communication cavity; 13. First pressure relief hole; 14. Second pressure relief hole; 15. Push rod seat; 16. Push rod; 17. Sealing ring; 18. Steel ball; 19. Push rod; 20. Spring; 21. Micro switch; 22. Push rod cavity; 23. Push rod cavity; 24. Communication hole; 25. First connection hole; 26. Second connection hole; 27. Third connection hole; 28. Installation groove; 29. First annular groove; 30. Second annular groove; 31. Third annular groove; 32. Sealing element; 33. Depression; 34. Installation cavity; 35. Plug; 36. First circular closed loop; 37. Second circular closed loop; 38. Triangular closed loop. Detailed implementation manners

[0030] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0031] Embodiment 1:

[0032] A plunger pump with a low-pressure overflow valve, as Figure 1 shown, includes a pump cover 1 and a pump body 2, wherein:

[0033] The pump cover 1, as Figure 6As shown, it is an integral unit, with an installation cavity 34 provided in the middle. The installation cavity 34 penetrates through the pump cover 1, that is, both the front and rear ends of the installation cavity 34 are open. On the outer part of the pump cover 1, there are respectively a water inlet channel 3, a water outlet channel 4, and an overflow channel 5. The water outlet channel 4 and the overflow channel 5 are both communicated with the installation cavity 34. One side of the pump cover 1 is for installing the pump body 2. On this side of the pump cover 1, there are a first circular closed loop 36, a second circular closed loop 37, and a triangular closed loop 38. The first circular closed loop 36 is on the outer circumference on one side of the installation cavity 34. The second circular closed loop 37 is outside the first circular closed loop 36. The triangular closed loop 38 is outside the second circular closed loop 37. A first communication cavity 11 is formed between the triangular closed loop 38 and the second circular closed loop 37. The water inlet channel 3 is communicated with the first communication cavity 11. A second pressure relief hole 14 is opened on the cavity wall of the first communication cavity 11. The second pressure relief hole 14 is communicated to the front part of the overflow channel 5, specifically to the cavity of the push rod 16 of the overflow valve 7 installed in the overflow channel 5. A second communication cavity 12 is formed between the second circular closed loop 37 and the first circular closed loop 36, and the second communication cavity 12 is communicated with one side of the installation cavity 34. A first pressure relief hole 13 is opened on the cavity wall of the second communication cavity 12. The first pressure relief hole 13 is communicated to the rear part of the overflow channel 5, specifically to the cavity of the push rod 19 of the overflow valve 7 installed in the overflow channel 5;

[0034] A main valve 6 is installed in the installation cavity 34. As Figure 5 shown, the main valve 6 includes a main valve seat, a main valve spool, a main valve spring, and a plug 35. The plug 35 is installed on the other side of the installation cavity 34 to play a sealing role, and the plug 35 can be taken out during installation and reinstalled after installing the main valve 6. The main valve seat is fixed in the installation cavity 34. The main valve spool is arranged in the main valve seat. One end of the main valve spring abuts against the main valve spool, and the other end abuts against the plug 35. And a guiding hole for one end of the main valve spool to extend into is also provided on the plug 35. The other end of the main valve spool is used to seal the other side of the installation cavity 34. Only when the water pressure in the second communication cavity 12 is greater than the thrust of the main valve spring, the main valve 6 will be opened. The structure and installation form of the main valve 6 itself are similar to those of the existing plunger pump, so the installation structure of the main valve 6 is not described in detail in this application;

[0035] The pump body 2, as Figure 9 connected to Figure 10 shown, is connected to the pump cover 1. Figure 10 is the upper end face of the pump body 2, which is connected to the pump cover 1. The pump body 2 is also provided with a first communication cavity 11 and a second communication cavity 12 that match the pump cover 1. And a low-pressure check valve 8 is provided on the first communication cavity 11 of the pump body 2. A high-pressure check valve 9 is provided on the second communication cavity 12 of the pump body 2. And a plunger cavity 10 is provided between the low-pressure check valve 8 and the high-pressure check valve 9. A plunger is arranged in the plunger cavity 10;

[0036] That is, the overall connected structure of this application includes, in sequential connection: an inlet passage 3, a first connection cavity 11, a low-pressure check valve 8, a plunger cavity 10, a high-pressure check valve 9, a second connection cavity 12, a mounting cavity 34, an outlet passage 4, and an overflow passage 5; and on this basis, the overflow passage 5 is further connected to the first connection cavity 11 through a first pressure relief hole 13, and the overflow passage 5 is also connected to the second connection cavity 12 through a second pressure relief hole 14;

[0037] An overflow valve 7 is also installed in the overflow passage 5, as Figure 2 shown. The overflow valve 7 includes a push rod seat 15, a push rod 16, a sealing ring 17, a steel ball 18, a push rod 19, a spring 20, a retaining ring, a nut, a slider, and a micro switch 21, where: The push rod seat 15, as Figure 7 shown, is arranged in the overflow passage 5. The push rod seat 15 abuts against the inside of the pump cover 1. The rear end of the push rod seat 15 abuts against the nut, and the nut is threadedly connected to the rear part of the overflow passage 5; The inner part of the push rod seat 15 is divided into a push rod cavity 22 and a push rod cavity 23, and the push rod cavity 22 and the push rod cavity 23 are connected through a communication hole 24;

[0038] On the outer wall of the push rod seat 15 corresponding to the push rod cavity 22, a first connection hole 25 and a second connection hole 26 are respectively arranged. On the outer wall of the push rod seat 15 corresponding to the push rod cavity 23, a third connection hole 27 is arranged. The first connection hole 25 and the second connection hole 26 are connected to the second pressure relief hole 14, and the third connection hole 27 is connected to the first pressure relief hole 13;

[0039] The push rod 16 is arranged in the push rod cavity 22, as Figure 8 shown. An installation groove 28 is arranged at the front end of the push rod 16. The sealing ring 17 is installed in the installation groove 28 and is hermetically sealed with the wall of the push rod cavity 22. The rear end of the push rod 16 extends into the communication hole 24 and is guided by the communication hole 24. However, there is still a certain gap between the rear end of the push rod 16 and the communication hole 24, so water can flow through the gap;

[0040] The push rod 19 is arranged in the push rod cavity 23. The diameter of the front part of the push rod 19 matches the push rod cavity 23. The steel ball 18 is fixed at the front end of the push rod 19, and the steel ball 18 can seal the communication hole 24. A retaining ring is fixed in the nut. The rear end of the push rod 19 passes through the retaining ring. The spring 20 is sleeved on the push rod 19. One end of the spring 20 abuts against the retaining ring, and the other end of the spring 20 abuts against the push rod 19. In this way, the spring 20 can give the push rod 19 a forward thrust;

[0041] A switch box is installed at the rear part of the nut. The micro switch 21 and the slider are both installed in the switch box. The rear end of the push rod 19 abuts against the slider. The contact part between the slider and the rear end of the push rod 19 is an inclined surface. In this way, the vertical movement of the push block can drive the horizontal movement of the slider, thereby controlling the on-off of the micro switch 21;

[0042] The overall working principle of this embodiment is:

[0043] When in normal working condition, such as Figure 2 As shown, that is, the state of firing and discharging water, at this time, the water outlet channel 4 is open, the micro switch 21 is energized, and because the water pressure in the second communicating chamber 12 is high, the main valve 6 is also open, and the water flows in from the water inlet channel 3, passes through the first communicating chamber 11, the low-pressure one-way valve 8, the plunger pressurization of the plunger chamber 10, the high-pressure one-way valve 9, the main valve 6, and finally flows out from the water outlet channel 4;

[0044] When in the state of gun closing recoil, such as Figure 3 As shown, that is, the initial period of time when the water gun is closed, at this time the water outlet channel 4 is closed, and the water flow pressure in the water outlet channel 4 is relatively large, so that the main valve 6 is closed, and then because the water pressure in the water outlet channel 4 is relatively large, the push rod 16 of the overflow valve 7 will be pushed open, and the steel ball 18 and the push rod 19 will be pushed back together. At this time, because the push rod 19 is also pushed back, the micro switch 21 is in a triggered state, and the water gun is in a power-off state. At the same time, because the push rod 16 pushes the steel ball 18 away from the sealing position of the connecting hole 24, the connecting hole 24 is connected at this time, so that the push rod cavity 22 is connected to the push rod cavity 23, and the position of the sealing ring 17 has passed the first connecting hole 2 5, so that the water outlet channel 4 is connected with the push rod chamber 22. At this time, the water flow in the water outlet channel 4 will first flow into the push rod chamber 22, and then flow into the push rod chamber 23 through the first connecting hole 25, the second connecting hole 26 and the connecting hole 24, and then flow back to the water inlet channel 3 through the third connecting hole 27, the first pressure relief hole 13 and the first connecting chamber 11, so as to achieve the pressure relief of the water outlet channel 4, and the water flow in the second connecting chamber 12 will flow into the push rod chamber 23 through the second pressure relief hole 14, the second connecting hole 26 and the connecting hole 24, and then this part of the water flow will also flow back to the water inlet channel 3 together with the water flow in the water outlet channel 4, so as to achieve the pressure relief of the second connecting chamber 12;

[0045] When the gun is closed and the machine is stopped, Figure 4As shown, after the gun-closing recoil state lasts for a period of time, the water outlet channel 4 and the second connecting chamber 12 are depressurized for a period of time, and the pressure has been reduced a lot. That is, the water pressure in the water outlet channel 4 can no longer completely push open the push rod 16. The push rod 16, the steel ball 18, and the push rod 19 will move forward under the action of the spring 20 until the sealing ring 17 moves to the position of the first connecting hole 25 and seals the first connecting hole 25. At this time, the water outlet channel 4 is separated from the push rod cavity 22, but because the push rod 16, the steel ball 18, and the push rod 19 are not completely pushed into place by the spring 20, the steel ball 18 does not support the connecting hole 24 at this time, the push rod cavity 22 and the push rod cavity 23 are still connected, and the microswitch 21 is still pushed open by the slider in the triggered state, and the water gun is still in the power-off state. At this time, the water pressure in the second connecting chamber 12 plus the thrust of the spring 20 is balanced with the water pressure in the water outlet channel 4.

[0046] Embodiment 2:

[0047] The difference from the first embodiment is that in the second embodiment, three annular grooves are sequentially arranged on the outer wall of the push rod seat 15 corresponding to the push rod cavity 22, namely a first annular groove 29, a second annular groove 30 and a third annular groove 31, wherein the first annular groove 29 and the third annular groove 31 are both provided with sealing members 32, the second annular groove 30 forms a recess 33 toward the first annular groove 29, a first connecting hole 25 is arranged at the bottom of the recess 33, and the diameter of the first connecting hole 25 close to the push rod cavity 22 is smaller than the diameter of the part away from the push rod cavity 22, so that the sealing ring 17 can better seal the first connecting hole 25, and a second connecting hole 26 is arranged on the bottom of the second annular groove 30, and the first connecting hole 25 and the second connecting hole 26 are both connected to the second pressure relief hole 14, and one side wall of the second annular groove 30 is inclined, so that the connecting space between the second connecting hole 26 and the second pressure relief hole 14 will be sealed by two sealing members 32, and this connecting space will also be relatively large.

[0048] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

[0049] For those skilled in the art, various changes and modifications will undoubtedly be obvious after reading the above description. Therefore, the attached claims should be regarded as covering all changes and modifications to the true intent and scope of the utility model. Any and all equivalent ranges and contents within the scope of the claims should be considered to still be within the intent and scope of the utility model.

Claims

1. A plunger pump with a low-pressure relief valve, comprising a pump cover (1) and a pump body (2), wherein the pump cover (1) is provided with a water inlet channel (3), a water outlet channel (4), an overflow channel (5) and a main valve (6), wherein the water outlet channel (4) is connected to the overflow channel (5), and the overflow channel (5) is provided with a relief valve (7), wherein the pump body (2) is provided with a low-pressure check valve (8), a high-pressure check valve (9) and a plunger cavity (10 ), a plunger cavity (10) is arranged between a low-pressure one-way valve (8) and a high-pressure one-way valve (9), a plunger is arranged in the plunger cavity (10), a first connecting cavity (11) is arranged between the low-pressure one-way valve (8) and the water inlet channel (3), a second connecting cavity (12) is arranged between the high-pressure one-way valve (9) and the main valve (6), and the overflow channel (5) is connected to the first connecting cavity (11) through a first pressure relief hole (13), characterized in that: The overflow channel (5) is connected to the second connecting chamber (12) through the second pressure relief hole (14), and the overflow valve (7) comprises a push rod seat (15), a push rod (16), a sealing ring (17), a steel ball (18), a push rod (19), a spring (20) and a micro switch (21). The push rod seat (15) is arranged in the overflow channel (5), and a push rod chamber (22) and a push rod chamber (23) are arranged in the push rod seat (15). The push rod chamber (22) and the push rod chamber (23) are connected through the connecting hole (24). The push rod seat (15) corresponding to the push rod chamber (22) is provided with a first connecting hole (25) and a second connecting hole (26) connected to the push rod chamber (22), and the first connecting hole (25) and the second connecting hole (26) are both connected to the second pressure relief hole (1 4), a third connecting hole (27) communicating with the push rod cavity (23) is provided on the push rod seat (15) corresponding to the push rod cavity (23), the third connecting hole (27) communicating with the first pressure relief hole (13), the push rod (16) is arranged in the push rod cavity (22), a mounting groove (28) is provided at the front end of the push rod (16), the sealing ring (17) is arranged in the mounting groove (28) and is matched and sealed with the cavity wall of the push rod cavity (22), the push rod (19) is arranged in the push rod cavity (23), the steel ball (18) is arranged at the front end of the push rod (19), and the steel ball (18) is matched and sealed with the connecting hole (24), the micro switch (21) is located at the rear side of the push rod (19), the spring (20) is sleeved on the push rod (19) and applies thrust to the push rod (19), When in normal working state, the outlet of the water outlet channel (4) is opened, the main valve (6) is opened, and the water pressure received by the front end of the push rod (16) is less than the thrust applied by the spring (20). At this time, the connecting hole (24) is supported and sealed by the steel ball (18), so that the push rod cavity (22) is separated from the push rod cavity (23), and the sealing ring (17) and the cavity wall of the push rod cavity (22) are matched and sealed, so that the water outlet channel (4) is separated from the push rod cavity (22), and the micro switch (21) is in an untriggered state; When the gun is in the closed recoil state, the outlet of the water outlet channel (4) is closed, the main valve (6) is closed, and the water pressure on the front end of the push rod (16) is greater than the thrust applied by the spring (20). At this time, the push rod (16), the steel ball (18) and the push rod (19) are pushed back together, and the first connecting hole (25) is connected with the water outlet channel (4), so that the water outlet channel (4) and the push rod cavity (22) are connected, and the connecting hole (24) is connected, so that the push rod cavity (22) and the push rod cavity (23) are connected, and at the same time, the micro switch (21) is in a triggered state; When the gun is in the shutdown state, the outlet of the water outlet channel (4) is closed, the main valve (6) is closed, the water pressure on the front end of the push rod (16) is less than the thrust applied by the spring (20), the push rod (16), the steel ball (18) and the push rod (19) are pushed forward together until the sealing ring (17) and the first connecting hole (25) are sealed and the connecting hole (24) is connected. At this time, the water outlet channel (4) is isolated from the push rod cavity (22), the push rod cavity (22) and the push rod cavity (23) are connected, and the micro switch (21) is in a triggered state.

2. A plunger pump with a low pressure relief valve according to claim 1, characterized in that: The outer side of the push rod seat (15) corresponding to the push rod cavity (22) is provided with three annular grooves in sequence, namely a first annular groove (29), a second annular groove (30) and a third annular groove (31); the first annular groove (29) and the third annular groove (31) are both provided with sealing members (32); the second annular groove (30) forms a depression (33) toward the first annular groove (29); a first connecting hole (25) is provided at the bottom of the depression (33); a second connecting hole (26) is provided at the bottom of the second annular groove (30); and the first connecting hole (25) and the second connecting hole (26) are both connected to the second pressure relief hole (14).

3. A plunger pump with a low pressure relief valve according to claim 2, characterized in that: The diameter of the first connecting hole (25) close to the push rod cavity (22) is smaller than the diameter of the first connecting hole (25) far from the push rod cavity (22).

4. A plunger pump with a low pressure relief valve according to claim 1, characterized in that: The pump cover (1) is provided with a mounting cavity (34), the main valve (6) is mounted in the mounting cavity (34), and the water outlet channel (4) and the second connecting cavity (12) are both connected to the mounting cavity (34); when the main valve (6) is opened, the second connecting cavity (12) is connected to the water outlet channel (4); when the main valve (6) is closed, the second connecting cavity (12) is isolated from the water outlet channel (4).

5. A plunger pump with a low pressure relief valve according to claim 4, characterized in that: The main valve (6) comprises a plug (35), one side of the installation cavity (34) is connected to the second communication cavity (12), and the other side of the installation cavity (34) is sealed by the plug (35).

6. A plunger pump with a high pressure relief valve according to claim 5, characterized in that: The pump cover (1) is provided with a first circular closed ring (36), a second circular closed ring (37) and a triangular closed ring (38) on one side close to the pump body (2); the first circular closed ring (36) is arranged on the outer ring of one side of the installation cavity (34); the second circular closed ring (37) is sleeved outside the first circular closed ring (36); the triangular closed ring (38) is sleeved outside the second circular closed ring (37); the second circular closed ring (37) and the triangular closed ring (38) form a first connecting cavity (11); the first pressure relief hole (13) is located between the second circular closed ring (37) and the triangular closed ring (38); the first circular closed ring (36) and the second circular closed ring (37) form a second connecting cavity (12); and the second pressure relief hole (14) is located between the first circular closed ring (36) and the second circular closed ring (37).

Images