Plunger pump for high-pressure cleaning machine

Abstract

The invention relates to the technical field of high-pressure cleaning machines, in particular to a plunger pump for a high-pressure cleaning machine, which comprises a pump cover and a pump shell, the pump cover and the pump shell form a pump body, a water inlet channel, a low-pressure one-way valve, a plunger cavity, a water outlet channel and an overflow channel are arranged in the pump body, the low-pressure one-way valve is arranged between the water inlet channel and the plunger cavity, and the overflow channel is arranged in the plunger cavity. An overflow valve is further arranged in the overflow channel, the overflow channel is communicated with the water outlet channel through a pressure relief hole, the plunger pump further comprises a transition channel, the transition channel is respectively communicated with the overflow channel, the water outlet channel and the plunger cavity, and a high-pressure one-way valve is arranged between the transition channel and the plunger cavity. A control valve used for controlling connection and disconnection between the transition channel and the water outlet channel is arranged in the transition channel, the plunger pump can well relieve pressure when the water gun is closed, and overall machining is convenient.

Description

Technical Field

[0001] This invention relates to the field of high-pressure cleaner technology, and more particularly to a plunger pump for use in high-pressure cleaners. Background Technology

[0002] A high-pressure washer is a cleaning device that uses a high-pressure water conversion device (usually a high-pressure plunger pump) to pressurize water through several stages to a pressure of several hundred atmospheres or more, and then ejects it through a high-pressure water gun.

[0003] The plunger pump is an important component of a high-pressure washer. Existing technology, such as the Chinese invention patent application filed by the applicant on August 30, 2024, with patent number 202411205915.6 and titled "A Plunger Pump with a High-Pressure Relief Valve," discloses a plunger pump equipped with an inlet channel, a low-pressure check valve, a plunger chamber, a high-pressure check valve, a main valve, an outlet channel, and an overflow channel. The outlet channel and the overflow channel are connected, and an overflow valve is also installed in the overflow channel. A plunger is installed in the plunger chamber. A first connecting chamber is provided between the low-pressure check valve and the inlet channel, and a connecting chamber is provided between the high-pressure check valve and the main valve. The pump has a second connecting chamber, with the overflow channel connected to the first connecting chamber via a first pressure relief hole, and the overflow channel connected to the second connecting chamber via a second pressure relief hole. This allows water in the second connecting chamber to be depressurized through the second pressure relief hole when the pump is shut off, significantly reducing the pressure and improving the overall performance and lifespan of the plunger pump. Furthermore, because of the second pressure relief hole, when the pump is in a shut-off state, the water pressure in the second connecting chamber, along with the spring's thrust, balances with the water pressure in the outlet channel, reducing the need for a very large spring thrust and saving costs. However, this structure requires a second pressure relief hole between the overflow channel and the second connecting chamber, which is not easily manufactured, potentially leading to inconsistent product performance. Summary of the Invention

[0004] The technical solution to be solved by the present invention is to provide a plunger pump for a high-pressure cleaner, which can effectively release pressure when the water gun is turned off, and is also relatively easy to process.

[0005] The technical solution adopted in this invention is: a plunger pump for a high-pressure washer, comprising a pump cover and a pump housing, the pump cover and pump housing forming a pump body. The pump body is provided with an inlet channel, a low-pressure check valve, a plunger chamber, an outlet channel, and an overflow channel. The low-pressure check valve is disposed between the inlet channel and the plunger chamber. An overflow valve is also disposed within the overflow channel. The overflow channel is connected to the outlet channel through a pressure relief hole. It also includes a transition channel, which is connected to the overflow channel, the outlet channel, and the plunger chamber. A high-pressure check valve is disposed between the transition channel and the plunger chamber, and a control valve for controlling the on / off connection between the transition channel and the outlet channel is disposed within the transition channel. When in normal working condition, the water outlet is open, the control valve is open, the overflow valve is closed, and the water flows out along the water inlet channel, low-pressure check valve, plunger chamber, high-pressure check valve, transition channel, and water outlet channel. When the gun is shut off and the backflush is in the state, the outlet of the water channel is closed, the control valve is open, and the overflow valve is fully open. At this time, the water flow in the outlet channel and the transition channel will be guided to the inlet channel through the overflow channel and the pressure relief hole. When the machine is in the shut-off and shutdown state, the water outlet is closed, the control valve is closed, and the overflow valve is partially open. At this time, the water outlet is isolated from the transition channel, and the transition channel is connected to the overflow channel.

[0006] Preferably, the overflow valve includes an overflow valve cover, an overflow valve core, an overflow valve seat, and an overflow spring. The overflow valve cover has a first connecting hole, and the transition channel communicates with the overflow channel through the first connecting hole. The overflow valve seat is disposed within the overflow channel and has an overflow chamber. The overflow valve core is disposed within the overflow chamber, and one end of the overflow valve core has a sealing head for sealing the first connecting hole. The overflow spring is sleeved on the overflow valve core and applies a thrust to the overflow valve core. The control valve includes a control valve head, a control valve core, a control valve seat, and a control spring. The control valve seat is disposed within the transition channel and has an outlet that communicates with the water outlet channel. The control valve seat has a transition cavity, and the control valve core is disposed within the transition cavity. One end of the control spring abuts against the control valve seat, and the other end of the control spring abuts against one end of the control valve core. The other end of the control valve core has a first sealing surface, and one end of the control valve head has a second sealing surface. When the control valve core abuts against the control valve head, the first sealing surface and the second sealing surface match and seal. The other end of the control valve head has a pusher for pressing against the sealing head and thus opening the overflow valve core. The outer side of the control valve head has a second connecting hole, which communicates with one end of the control valve head. The control valve core also has a pressure-holding valve connecting the water outlet channel and the transition channel. When in normal working condition, the outlet of the water outlet channel is open, and the control valve core is subjected to water flow pressure in the transition channel that is greater than the elastic force of the control spring. At this time, the control valve core separates from the control valve head, the control valve opens, and the overflow valve core is pressed against the first connecting hole by the overflow spring, and the overflow valve closes. When the nozzle is in the reverse recoil state, the outlet of the water channel is closed. The water pressure in the control valve core is greater than the spring force of the overflow spring, causing the control valve core to push the control valve head and then fully open the overflow valve core. At this time, the overflow valve is fully open to relieve pressure in the transition channel, and the pressure holding valve is open to relieve pressure in the water channel. When the nozzle is shut off and the machine is stopped, the outlet of the water channel is closed, the control valve core is subjected to a decrease in water pressure from the water channel, and the overflow valve core will return to its original position under the action of the overflow spring. At this time, the overflow valve is partially opened, the transition channel is connected to the overflow channel, and the pressure holding valve is closed, thus isolating the water channel from the transition channel.

[0007] Preferably, the pressure-holding valve includes a pressure-holding valve cover, a pressure-holding valve seat, a pressure-holding valve core, a pressure-holding spring, and a pressure-holding sealing ring. The pressure-holding valve seat is disposed in the transition cavity, and the pressure-holding valve cover is disposed at one end of the pressure-holding valve seat, forming a pressure-holding cavity between the pressure-holding valve seat and the pressure-holding valve cover. The pressure-holding valve seat is provided with a third connecting hole for connecting the pressure-holding cavity and the water outlet channel. The pressure-holding valve core is disposed in the pressure-holding cavity, and a groove is provided at the front end of the pressure-holding valve core. The pressure-holding valve core matches the pressure-holding sealing ring, and the pressure-holding spring is sleeved on the pressure-holding valve core and applies a thrust to the pressure-holding valve core.

[0008] Preferably, the matching and sealing of the first sealing surface and the second sealing surface means that a sealing groove is provided on the first sealing surface, and a control sealing ring is embedded in the sealing groove. When the control valve core and the control valve head abut, the control sealing ring on the first sealing surface will abut against the second sealing surface and thus seal.

[0009] Preferably, both the end of the mandrel used to press the sealing head and the end of the sealing head used to be pressed by the mandrel are planar.

[0010] Preferably, a flow guide groove is provided at the other end of the control valve head.

[0011] Preferably, the pump casing includes a housing, a side pipe, and an inlet pipe. The inlet channel is disposed inside the inlet pipe. The housing is provided with a plunger port and an outlet. The inlet pipe is connected to the outlet. The side pipe is provided with an inlet and is connected to the inlet pipe through a pressure relief hole. The inlet is connected to a transition channel. The outlet channel and the overflow channel are respectively disposed on both sides of the transition channel. The control valve is disposed inside the transition channel, and the overflow valve is disposed inside the overflow channel.

[0012] Preferably, the pump cover is provided with a first cavity communicating with the outlet, a second cavity communicating with the plunger port, and a third cavity communicating with the inlet. The second cavity is a plunger cavity. The first cavity is communicating with the second cavity, and the second cavity is communicating with the third cavity. A low-pressure check valve is provided in the first cavity, a plunger is provided in the second cavity, and a high-pressure check valve is provided in the third cavity.

[0013] Compared with the prior art, the present invention has the following advantages by adopting the above structure: by setting a transition channel and replacing the previous main valve with the current control valve, and positioning it between the transition channel and the outlet channel, the function is still similar to the previous one. However, the high pressure water between the high pressure check valve and the outlet channel can be directly released from the pressure relief hole through the transition channel and the overflow channel, so there is no need to set a second pressure relief hole, and the overall processing is also more convenient.

[0014] The overflow valve, control valve, and pressure holding valve with this structure can effectively switch between the three states, resulting in a good overall performance.

[0015] This two-sealing-surface structure provides a good overall sealing effect and is easy to match.

[0016] Both the top head and the sealing head are made into flat surfaces, which facilitates their contact and thus pushes the overflow valve core.

[0017] The flow guide groove is designed so that even if the control valve head is completely pressed against the overflow valve cover, the control valve head will not completely seal the first connecting hole.

[0018] The pump casing and cover with this structure are easy to process and install, and can effectively connect various channels and cavities. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a plunger pump used in a high-pressure washer.

[0020] Figure 2 yes Figure 1 A cross-sectional view from one perspective.

[0021] Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0022] Figure 4 yes Figure 1 A schematic diagram of the structure without the pump cover.

[0023] Figure 5 yes Figure 4 A schematic diagram of the structure without the pump casing.

[0024] Figure 6 This is a schematic diagram of the pump cover.

[0025] Figure 7 This is a schematic diagram of the pump casing.

[0026] Figure 8 This is a schematic diagram of the control valve head.

[0027] Figure 9 This is a schematic diagram of the control valve core. Figure 10 This is a schematic diagram of the pressure-holding valve core.

[0028] As shown in the figure: 1. Pump cover; 2. Pump casing; 3. Inlet channel; 4. Low-pressure check valve; 5. Plunger chamber; 6. High-pressure check valve; 7. Outlet channel; 8. Overflow channel; 9. Pressure relief hole; 10. Transition channel; 11. Overflow valve cover; 12. Overflow valve core; 13. Overflow valve seat; 14. Overflow spring; 15. First connecting hole; 16. Sealing head; 17. Control valve head; 18. Control valve core; 19. Control valve seat; 20. Control spring; 21. Outlet; 22. First seal 23. Second sealing surface; 24. Top head; 25. Second connecting hole; 26. Pressure holding valve cover; 27. Pressure holding valve seat; 28. Pressure holding valve core; 29. ​​Pressure holding spring; 30. Pressure holding sealing ring; 31. Third connecting hole; 32. Groove; 33. Sealing groove; 34. Control sealing ring; 35. Guide groove; 36. Housing; 37. Side pipe; 38. Inlet pipe; 39. Plunger port; 40. Outlet; 41. Inlet; 42. First chamber; 43. Second chamber; 44. Third chamber. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein 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 with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] Example 1: A plunger pump for use in high-pressure cleaners, such as Figure 1 As shown, it includes a pump housing 2 and a pump cover 1, wherein: Pump casing 2, such as Figure 7As shown, the device includes a housing 36, an inlet pipe 38, and a side pipe 37. Both the inlet pipe 38 and the side pipe 37 are fixed to the housing 36 and are arranged in parallel. The housing 36 has three outlets 40 and three plunger ports 39. The three plunger ports 39 allow the plunger to extend and compress the plunger chamber 5. The three outlets 40 are connected to the inlet pipe 38, allowing water flowing into the inlet pipe 38 to flow out through the outlets 40. The side pipe 37 has an inlet 41 in its middle section. The interior of the side pipe 37 is divided into a transition channel 10, an outlet channel 7, and an overflow channel 8. The transition channel 10 is located in the middle, the outlet channel 7 and the overflow channel 8 are located on both sides of the transition channel 10, and the inlet 41 is connected to the transition channel 10, that is, the water flows to the transition channel 10 first. A control valve is installed between the transition channel 10 and the outlet channel 7, which can be used to control the opening and closing of the transition channel 10 and the outlet channel 7. An overflow valve is installed in the overflow channel 8, which can be used to control the opening and closing of the transition channel 10 and the overflow channel 8. The overflow channel 8 is also connected to the inlet pipe 38 through the pressure relief hole 9.

[0031] Pump cover 1, such as Figure 6 As shown, it is provided with a first chamber 42, a second chamber 43 and a third chamber 44. When the pump cover 1 and the pump housing 2 are combined to form the pump body, the first chamber 42 covers the outlet 40 and a low-pressure check valve 4 is provided in the first chamber 42. The second chamber 43 covers the plunger port 39 and forms a plunger chamber 5 after the second chamber 43 covers the plunger port 39. That is, the plunger can move up and down in the second chamber 43 to pressurize the water flow. The third chamber 44 is connected to the outlet 40 and a high-pressure check valve 6 is provided in the third chamber 44. The first chamber 42 is connected to the second chamber 43 and the second chamber 43 is connected to the third chamber 44.

[0032] An overflow valve, located within the overflow channel 8 of the side pipe 37, includes an overflow valve cover 11, an overflow valve core 12, an overflow valve seat 13, and an overflow spring 14. The overflow valve cover 11 is integrally formed within the side pipe 37 and has a first connecting hole 15. The overflow valve seat 13 is installed within the overflow channel 8, and a sealing ring is provided on its outer side to seal against the inner wall of the side pipe 37. The overflow valve core 12 can slide within the overflow valve seat 13, and a sealing head 16 is provided at one end of the overflow valve core 12. The sealing head 16 includes an inclined sealing surface and a flat abutting surface. The inclined sealing surface is matched and sealed with the first connecting hole 15, and the flat abutting surface is used to abut against the top head 24 to seal against the first connecting hole 15. One end of the overflow spring 14 abuts against the overflow valve seat 13, and the other end of the overflow spring 14 abuts against the overflow valve core 12 to apply a thrust to the overflow valve core 12.

[0033] The control valve, located within the transition channel 10, includes a control valve head 17, a control valve core 18, a control valve seat 19, and a control spring 20, wherein: The control valve seat 19 is detachable and is connected to the side pipe 37 by a thread. A baffle is provided inside the control valve seat 19, and a water outlet 21 is provided on the baffle. In this embodiment, three water outlets 21 are evenly arranged along the circumference of the baffle, and a sealing ring is also provided between the control valve seat 19 and the side pipe 37 for sealing. The control valve core 18 slides within the control valve seat 19, such as... Figure 9 As shown, one end of the valve is provided with a first sealing surface 22, the first sealing ring is an inclined sealing surface, and a sealing groove 33 is provided on the first sealing surface 22. A control sealing ring 34 is embedded in the sealing groove 33, and the control valve core 18 itself can also be used as a pressure holding valve, with a pressure holding valve structure inside. The control spring 20 has one end abutting against the baffle on the control valve seat 19 and the other end abutting against the other end of the control valve core 18, and is used to provide thrust to the control valve core 18; Control valve head 17, such as Figure 8 As shown, it includes a main body and a platform. A top head 24 is installed in the middle of one end of the platform. One end of the top head 24 is flat and is used to abut against the sealing head 16. A guide groove 35 is also provided on the circumference of one end of the platform. So even if the control valve head 17 fully pushes open the overflow valve core 12, the first connecting hole 15 is connected to the guide groove 35. Thus, the control valve head 17 will not seal the first connecting hole 15. At this time, the transition channel 10 is connected to the overflow channel 8. A second connecting hole 25 is provided on the circumference of the platform. A through hole is provided inside the main body. The second connecting hole 25 is connected to this through hole. Thus, the water flow can pass through the control valve head 17 along the second connecting hole 25 and the through hole. A sealing ring is also provided on the outer circumference of the main body for sealing with the inner wall of the side pipe 37. The pressure-holding valve, i.e., the entire control valve core 18, includes a pressure-holding valve cover 26, a pressure-holding valve seat 27, a pressure-holding valve core 28, a pressure-holding spring 29, and a pressure-holding sealing ring 30. The pressure-holding valve cover 26 and the pressure-holding valve seat 27 form the outer shell of the control valve core 18, which is located inside the control valve seat 19. After the pressure-holding valve cover 26 and the pressure-holding valve seat 27 are combined, a pressure-holding chamber is formed inside. A third connecting hole 31 is provided in the middle of the pressure-holding valve cover 26 for connecting the pressure-holding chamber and the water outlet channel 7. A through hole is provided at the end of the pressure-holding valve seat 27 away from the pressure-holding valve cover 26 for connecting the pressure-holding chamber and the transition channel 10. The pressure-holding valve core 28 slides in the pressure-holding chamber. The pressure-holding spring 29 is sleeved on the pressure-holding valve core 28 and applies a thrust to the pressure-holding valve core 28. Figure 10 As shown, the front end of the pressure holding valve core 28 is provided with a groove 32, which can match the pressure holding sealing ring 30 installed in the pressure holding chamber. That is, when the groove 32 part of the pressure holding valve core 28 moves to the position of the pressure holding sealing ring 30, the third connecting hole 31 is opened, and the pressure holding chamber is connected to the water outlet channel 7. Furthermore, since the pressure holding chamber is always connected to the transition channel 10, it is equivalent to the water outlet channel 7 being connected to the transition channel 10. The overall working principle of this embodiment is as follows: When in normal working condition, i.e., when the nozzle is open and water is being dispensed, the outlet of the water outlet channel 7 is open, while the overflow valve is closed. Because the water pressure in the transition channel 10 is high, the control valve is open in the forward direction. At this time, the high-pressure water flow will pass through the second connecting hole 25 and impact the control valve core 18. The control valve core 18 will then press against the control valve seat 19. Under the action of water pressure, the control valve core 18 will squeeze the control spring 20, thereby causing the first sealing surface 22 to separate from the second sealing surface 23. The water flow will pass sequentially between the first sealing surface 22 and the second sealing surface 23, between the control valve core 18 and the control valve seat 19, and through the water outlet 21, and finally flow out from the outlet of the water outlet channel 7. When in the backflow state after the nozzle is turned off, i.e., for a short period after the nozzle is turned off, the outlet of water outlet channel 7 is closed, causing the water pressure in transition channel 10 and water outlet channel 7 to increase rapidly. First, the overflow valve is fully opened. At this time, the top head 24 on the control valve core 18 will squeeze the sealing head 16 on the overflow valve core 12, thus completely opening the overflow valve core 12. At this time, the first connecting hole 15 is fully opened, and transition channel 10 is connected to overflow channel 8. The water flow in transition channel 10 will pass through overflow channel 8 and release pressure. After the pressure is released from the hole 9, it is released into the water inlet channel 3. At the same time, the control valve will be opened in reverse. That is, the water pressure in the water outlet channel 7 will squeeze the pressure holding valve core 28, which will drive the pressure holding valve core 28 to compress the pressure holding spring 29. When the groove 32 of the pressure holding valve core 28 moves to the position of the pressure holding sealing ring 30, the pressure holding chamber is connected to the water outlet channel 7. The water flow in the water outlet channel 7 will flow from the pressure holding chamber into the transition channel 10, and finally flow from the overflow channel 8 and the pressure relief hole 9 back to the water inlet channel 3, thus realizing the pressure relief of the water outlet channel 7 and the transition channel 10. When the machine is in the shut-off and stop-operation state, that is, after the shut-off and back-flush state has lasted for a period of time, the water outlet channel 7 and the transition channel 10 have been depressurized for a period of time, and their pressure has dropped significantly. At this time, the water pressure in the water outlet channel 7 can no longer push open the pressure holding valve core 28. The pressure holding valve core 28 will be reset under the action of the pressure holding spring 29. The groove 32 of the pressure holding valve core 28 does not correspond to the position of the pressure holding sealing ring 30. At this time, the pressure holding chamber is isolated from the water outlet channel 7, that is, the control valve is in the closed state. At the same time, because the water pressure supplied to the control valve core 18 is not enough to completely push open the overflow valve core 12, the overflow valve core 12 will return to its original position slightly under the action of the overflow spring 14 and then maintain balance. At this time, the second connecting hole 25 is still in the open state, and the transition channel 10 and the overflow channel 8 are still in the connected state.

[0034] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0035] For those skilled in the art, various changes and modifications will undoubtedly be apparent after reading the above description. Therefore, the appended claims should be construed as covering all changes and modifications that encompass the true intent and scope of the invention. Any and all equivalent scope and content within the scope of the claims should be considered to remain within the intent and scope of the invention.

Claims

1. A plunger pump for a high-pressure washer, comprising a pump cover (1) and a pump housing (2), the pump cover (1) and the pump housing (2) forming a pump body, wherein the pump body is provided with an inlet channel (3), a low-pressure check valve (4), a plunger chamber (5), an outlet channel (7), and an overflow channel (8), wherein the low-pressure check valve (4) is disposed between the inlet channel (3) and the plunger chamber (5), and an overflow valve is also disposed in the overflow channel (8), wherein the overflow channel (8) is connected to the outlet channel (7) through a pressure relief hole (9), characterized in that: It also includes a transition channel (10), which is connected to the overflow channel (8), the outlet channel (7), and the plunger chamber (5) respectively. A high-pressure check valve (6) is provided between the transition channel (10) and the plunger chamber (5), and a control valve for controlling the opening and closing between the transition channel (10) and the outlet channel (7) is provided in the transition channel (10). When in normal working condition, the outlet of the water outlet channel (7) is open, the control valve is open, and the overflow valve is closed. At this time, the water flows out along the water inlet channel (3), the low-pressure check valve (4), the plunger chamber (5), the high-pressure check valve (6), the transition channel (10), and the water outlet channel (7). When the gun is in the reverse recoil state, the outlet of the water channel (7) is closed, the control valve is opened, and the overflow valve is fully opened. At this time, the water flow in the water channel (7) and the transition channel (10) will be guided to the water inlet channel (3) through the overflow channel (8) and the pressure relief hole (9). When the machine is in the shut-off and shutdown state, the outlet of the water channel (7) is closed, the control valve is closed, and the overflow valve is partially opened. At this time, the water channel (7) is isolated from the transition channel (10), and the transition channel (10) is connected to the overflow channel (8).

2. A plunger pump for a high-pressure washer according to claim 1, characterized in that: The overflow valve includes an overflow valve cover (11), an overflow valve core (12), an overflow valve seat (13), and an overflow spring (14). The overflow valve cover (11) has a first connecting hole (15). The transition channel (10) and the overflow channel (8) are connected through the first connecting hole (15). The overflow valve seat (13) is located within the overflow channel (8), and an overflow cavity is provided within the overflow valve seat (13). The overflow valve core (12) is located within the overflow cavity. One end of the core (12) is provided with a sealing head (16) for sealing the first connecting hole (15). The overflow spring (14) is sleeved on the overflow valve core (12) and applies a thrust to the overflow valve core (12). The control valve includes a control valve head (17), a control valve core (18), a control valve seat (19), and a control spring (20). The control valve seat (19) is provided in the transition channel (10). The control valve seat (19) is provided with an outlet hole that communicates with the outlet channel (7). (21) A transition cavity is provided in the control valve seat (19), and the control valve core (18) is disposed in the transition cavity. One end of the control spring (20) abuts against the control valve seat (19), and the other end of the control spring (20) abuts against one end of the control valve core (18). A first sealing surface (22) is provided at the other end of the control valve core (18), and a second sealing surface (23) is provided at one end of the control valve head (17). When the control valve core (18) and the control valve head (17) are in contact... When the valve is in contact with the sealing head (16), the first sealing surface (22) and the second sealing surface (23) are matched and sealed. The other end of the control valve head (17) is provided with a top head (24) for pressing against the sealing head (16) and thus pushing open the overflow valve core (12). The outer side of the control valve head (17) is provided with a second connecting hole (25), which is connected to one end of the control valve head (17). The control valve core (18) is also provided with a pressure holding valve that connects the water outlet channel (7) and the transition channel (10). When in normal working condition, the outlet of the water outlet channel (7) is opened, and the control valve core (18) is subjected to water flow pressure in the transition channel (10) that is greater than the elastic force of the control spring (20). At this time, the control valve core (18) separates from the control valve head (17), the control valve is opened, and at the same time, the overflow valve core (12) is pressed against the first connecting hole (15) under the action of the overflow spring (14), and the overflow valve is closed. When the gun is in the reverse recoil state, the outlet of the water outlet channel (7) is closed, and the control valve core (18) is subjected to water flow pressure in the water outlet channel (7) greater than the elastic force of the overflow spring (14), causing the control valve core (18) to push the control valve head (17) and then fully open the overflow valve core (12). At this time, the overflow valve is fully open to allow the transition channel (10) to release pressure, and at the same time the pressure holding valve is opened to allow the water outlet channel (7) to release pressure. When the nozzle is shut off and the machine is stopped, the outlet of the water outlet channel (7) is closed, the control valve core (18) is reduced by the water pressure of the water outlet channel (7), the overflow valve core (12) will return to its original position under the action of the overflow spring (14), at this time the overflow valve is partially opened, the transition channel (10) is connected to the overflow channel (8), and the pressure holding valve is closed, the water outlet channel (7) is isolated from the transition channel (10).

3. A plunger pump for a high-pressure washer according to claim 2, characterized in that: The pressure-holding valve includes a pressure-holding valve cover (26), a pressure-holding valve seat (27), a pressure-holding valve core (28), a pressure-holding spring (29), and a pressure-holding sealing ring (30). The pressure-holding valve seat (27) is disposed in the transition cavity. The pressure-holding valve cover (26) is disposed at one end of the pressure-holding valve seat (27), and a pressure-holding cavity is formed between the pressure-holding valve seat (27) and the pressure-holding valve cover (26). The pressure-holding valve seat (27) is provided with a third connecting hole (31) for connecting the pressure-holding cavity and the water outlet channel (7). The pressure-holding valve core (28) is disposed in the pressure-holding cavity. The front end of the pressure-holding valve core (28) is provided with a groove (32). The pressure-holding valve core (28) matches the pressure-holding sealing ring (30). The pressure-holding spring (29) is sleeved on the pressure-holding valve core (28) and applies a thrust to the pressure-holding valve core (28).

4. A plunger pump for a high-pressure washer according to claim 2, characterized in that: The matching and sealing of the first sealing surface (22) and the second sealing surface (23) means that the first sealing surface (22) is provided with a sealing groove (33), and the sealing groove (33) is embedded with a control sealing ring (34). When the control valve core (18) and the control valve head (17) abut against each other, the control sealing ring (34) on the first sealing surface (22) will abut against the second sealing surface (23) and thus seal.

5. A plunger pump for a high-pressure washer according to claim 2, characterized in that: The top head (24) used to squeeze one end of the sealing head (16) and the sealing head (16) used to be squeezed by the top head (24) are both flat.

6. A plunger pump for a high-pressure washer according to claim 2, characterized in that: The other end of the control valve head (17) is provided with a guide groove (35).

7. A plunger pump for a high-pressure washer according to claim 2, characterized in that: The pump casing (2) includes a housing (36), a side pipe (37), and an inlet pipe (38). The inlet channel (3) is located inside the inlet pipe (38). The housing (36) is provided with a plunger port (39) and an outlet (40). The inlet pipe (38) is connected to the outlet (40). The side pipe (37) is provided with an inlet (41). The side pipe (37) is connected to the inlet pipe (38) through a pressure relief hole (9). The inlet (41) is connected to the transition channel (10). The outlet channel (7) and the overflow channel (8) are respectively located on both sides of the transition channel (10). The control valve is located inside the transition channel (10), and the overflow valve is located inside the overflow channel (8).

8. A plunger pump for a high-pressure washer according to claim 7, characterized in that: The pump cover (1) is provided with a first chamber (42) communicating with the outlet (40), a second chamber (43) communicating with the plunger port (39) and a third chamber (44) communicating with the inlet (41). The second chamber (43) is a plunger chamber (5). The first chamber (42) is connected to the second chamber (43), and the second chamber (43) is connected to the third chamber (44). A low-pressure check valve (4) is provided in the first chamber (42), a plunger is provided in the second chamber (43), and a high-pressure check valve (6) is provided in the third chamber (44).

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