Crankshaft pump

Abstract

The application relates to a crankshaft pump which comprises a pump body, a crankshaft assembly, a plurality of piston assemblies and an inlet and outlet valve assembly. The pump body is internally provided with a water inlet, a water outlet, a crankshaft cavity, a piston cavity and a valve cavity. The crankshaft assembly is arranged in the crankshaft cavity, the piston assembly is arranged in the piston cavity, the valve cavity is connected with the piston cavity and the water inlet and outlet, and the inlet and outlet valve assembly is arranged in the valve cavity. The piston assembly comprises a piston rod, a sleeve block, a connecting block and a connecting rod. The piston rod is sealingly and slidably arranged in the piston cavity. The connecting block connects the piston rod and the connecting rod. The connecting rod is connected with the crankshaft assembly. The sleeve block is arranged in the pump body. The piston rod and the connecting rod are sealingly and slidably arranged at two ends in the sleeve block, so as to form a sealed annular gap. The piston rod is provided with a first cooling groove, and the connecting rod is provided with a second cooling groove which is internally arranged with a first one-way valve. The pump body is provided with a return channel which connects the second cooling groove with the water inlet. When the pump pumps water, the water opens the first one-way valve to enter the second cooling groove, and then returns to the water inlet through a connecting channel, the annular gap, an opening groove and the return channel, so as to form a circulating cooling, take away heat and ensure stable work of the pump and prolong the service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fluid delivery equipment, in particular to a crankshaft pump. BACKGROUND

[0002] As a common fluid delivery equipment, the crankshaft pump is widely used in industrial, agricultural, municipal and other fields. The crankshaft pump usually includes a crankshaft, a connecting rod, a piston, a pump body, an inlet and outlet water one-way valve and other components. The crankshaft, as a key component for power transmission, drives the piston to reciprocate in the cylinder body through the connecting rod; the pump body provides space for the piston movement and contains the liquid; the inlet and outlet water one-way valve is used to control the flow direction of the liquid to ensure that the liquid can only flow in one direction, thereby realizing the suction and discharge of the liquid.

[0003] During high-speed reciprocating movement of the piston rod, a large amount of heat is generated due to friction, medium impact and the like. The connecting rod is subjected to periodic alternating load and friction force during work, and is also prone to material performance degradation due to high temperature. If the crankshaft pump works in a high-temperature state for a long time, the working state of the pump will be unstable, the parameters such as pressure and flow will fluctuate greatly, the stability of the output cannot be guaranteed, and the overall service life of the pump will be greatly shortened. SUMMARY

[0004] In order to improve the heat dissipation effect of the crankshaft pump, the present application provides a crankshaft pump.

[0005] The crankshaft pump provided by the present application adopts the following technical scheme:

[0006] A crankshaft pump includes a pump body, a crankshaft assembly, a plurality of piston assemblies and an inlet and outlet water valve assembly. The pump body is provided with a water inlet, a water outlet, a crankshaft cavity, a plurality of piston cavities and a plurality of valve cavities. The crankshaft assembly is installed in the crankshaft cavity. The plurality of piston assemblies are respectively arranged in the plurality of piston cavities. The valve cavities are connected with the piston cavities, the water inlet and the water outlet. The inlet and outlet water valve assembly is installed in the valve cavity.

[0007] The piston assembly includes a piston rod, a sleeve block, a connecting block and a connecting rod. The piston rod is arranged in the piston cavity and sealingly and slidably connected with the inner wall of the piston cavity. The two ends of the connecting block are respectively installed on the piston rod and the connecting rod. The other end of the connecting rod is connected with the crankshaft assembly. The sleeve block is installed in the pump body. The piston rod and the connecting rod are both arranged in the sleeve block and sealingly and slidably connected with the two ends of the sleeve block. The sleeve block, the connecting rod and the piston rod form a sealed annular gap.

[0008] The piston rod is provided with a first cooling groove, the connecting rod is provided with a second cooling groove, the connecting block is provided with a communication groove in communication with the first cooling groove and the second cooling groove, the communication groove is provided with a first one-way valve for allowing fluid to enter the second cooling groove in one direction only, the inner wall of the second cooling groove is provided with a communication channel in communication with an annular gap, the sleeve block is provided with an opening groove in communication with the annular gap, and the pump body is provided with a return channel in communication with the opening groove and a water inlet.

[0009] By adopting the technical scheme, the piston rod and the connecting rod can be cooled by fluid in the pump body: when the piston rod pumps water, the first one-way valve is closed; when the piston rod pumps water, water can not only be pumped out from the water outlet, but also enter the second cooling groove by opening the first one-way valve, then the water in the second cooling groove enters the annular gap through the communication channel, and finally returns to the water inlet through the opening groove and the return channel, forming a circulating cooling path, effectively removing the heat generated by friction and medium impact of the piston rod and the connecting rod, avoiding the performance degradation of the two due to high temperature, thereby ensuring long-term stable operation of the crankshaft pump and prolonging the overall service life.

[0010] Preferably, the communication groove is provided with a nozzle, and the nozzle is located on the side of the first one-way valve facing the second cooling groove.

[0011] By adopting the technical scheme, the nozzle can spray the water entering the second cooling groove in the form of high-pressure jet, enhancing the contact efficiency and impact force of the water and the inner wall of the second cooling groove, and further improving the heat dissipation effect of the connecting rod, avoiding the performance degradation of the connecting rod due to high temperature.

[0012] Preferably, the nozzle is a hollow cone nozzle.

[0013] By adopting the technical scheme, the hollow cone nozzle can make the cooling fluid form a fan-shaped or conical diffusion spray, greatly expanding the contact area of the cooling fluid and the inner wall of the second cooling groove, and compared with an ordinary straight jet nozzle, the hollow cone nozzle can more evenly cover the heating area of the connecting rod, further optimizing the uniformity and efficiency of heat dissipation.

[0014] Preferably, the second one-way valve, the volume change assembly and the air intake balance assembly are further included, the second one-way valve is arranged in the communication channel and allows water in the second cooling groove to flow to the annular gap in one direction only, the volume change assembly includes a movable piston head, the piston head is slidably connected in the second cooling groove, the piston head divides the second cooling groove into a front groove and a rear groove which are not in communication with each other, the nozzle acts on the front groove, and the communication channel is in communication with the front groove only.

[0015] The piston head moves towards the front groove side when the piston rod is in the water pumping state, and the piston head moves towards the rear groove side when the piston rod is in the water pumping state; the air inlet balancing assembly is used to balance the air pressure in the rear groove during the movement of the piston head towards the front groove side, and balance the air pressure in the front groove and the rear groove during the movement of the piston head towards the rear groove side; the nozzle single water injection volume is less than the single volume change amount of the front groove.

[0016] By adopting the above technical scheme, the second one-way valve can prevent the fluid in the backflow channel from flowing back to the front groove, and ensure the one-way flow of the cooling circuit, especially for the case that the water inlet is connected to a high-pressure water source; when the piston rod is in the water pumping state, the piston head moves towards the front groove side, at this time the first one-way valve is closed, and under the volume change of the front groove, the piston head pushes the water in the front groove and the air back to the water inlet; when the piston rod is in the water pumping state, the piston head moves towards the rear groove side, at this time the first one-way valve is opened, the second one-way valve is closed, and the front groove is air-inletted, realizing circulation.

[0017] Preferably, the volume change assembly further comprises a fixed block and a butt joint block, the butt joint block is coaxially fixed on the side of the piston head facing the rear groove, the fixed block is L-shaped, the pump body is provided with a mounting groove matched with the fixed block, the top end of the fixed block is fixed in the mounting groove through a screw, the butt joint block is provided with a butt joint ring groove in the circumferential direction, the side wall of the rear groove facing the mounting groove is provided with a sliding groove for the sliding of the fixed block, and the bottom end of the fixed block is inserted into the butt joint ring groove through the sliding groove; the sliding groove is located on the side of the annular gap close to the crankshaft assembly, and the piston head is always located on the side of the sliding groove away from the crankshaft assembly.

[0018] By adopting the above technical scheme, the fixed block is fixed in the mounting groove of the pump body, and the fixed block is fixedly connected with the butt joint block, so that the piston head always keeps stationary with the pump body, and when the connecting rod is driven to move by the crankshaft assembly, the piston head can slide with the connecting rod, thereby controlling the volume change of the front groove.

[0019] Preferably, the air inlet balancing assembly comprises a third one-way valve, a mounting hole, a first groove and a second groove, the first groove is provided in the pump body, the first groove is located on the side of the annular gap close to the crankshaft assembly, the first groove is communicated with the sliding groove, the second groove is provided on the outer side wall of the fixed block in the length direction of the fixed block, and the first groove, the second groove and the sliding groove are communicated with each other; the mounting hole is provided on the connecting rod, the two ends of the mounting hole are communicated with the first groove and the front groove respectively, and the third one-way valve is installed in the mounting hole to allow only external air to enter the front groove.

[0020] By adopting the technical scheme, when the piston head moves towards the rear groove, the first one-way valve is opened, water is sprayed from the nozzle, the second one-way valve is closed, and meanwhile external gas can enter the front groove through the third one-way valve to balance the air pressure; when the piston head moves towards the front groove, the first one-way valve and the third one-way valve are both closed, the second one-way valve is opened, and the water and gas in the front groove are simultaneously pressed into the annular gap, so that efficient circulation of cooling is realized.

[0021] Preferably, when the piston rod moves to the limit position of the water pumping state, and the piston head moves to the abutting block abutting against the end wall of the rear groove, the bottom end of the fixed block is opposite to the abutting ring groove.

[0022] By adopting the technical scheme, reliable position relationship is provided for the abutting of the fixed block and the abutting block.

[0023] Preferably, a first ring groove is formed in the circumferential outer wall of the sleeve block, and the opening groove is communicated with the backflow channel through the first ring groove.

[0024] By adopting the technical scheme, no matter how the sleeve block is installed, the first ring groove can always be communicated with the backflow channel, and the convenience of installation of the sleeve block is improved.

[0025] The technical effects of the present application mainly embody in the following aspects:

[0026] 1. The present application can utilize the fluid in the pump body to cool the piston rod and the connecting rod: when the piston rod pumps water, water enters the piston cavity and the first cooling groove, and the pressure in the piston cavity is small, so that the first one-way valve is closed; when the piston rod pumps water, the pressure in the piston cavity is large, so that water can not only be pumped out from the water outlet, but also enter the second cooling groove by opening the first one-way valve, then the water in the second cooling groove enters the annular gap through the communication channel, and finally returns to the water inlet through the opening groove and the backflow channel, forming a circulating cooling path, effectively taking away the heat generated by the piston rod and the connecting rod due to friction and medium impact, avoiding the material performance degradation of the two due to high temperature, so as to ensure the long-term stable work of the crankshaft pump and prolong the overall service life thereof;

[0027] 2. The nozzle of the present application can spray the water entering the second cooling groove in the form of high-pressure jet, enhancing the contact efficiency and impact force of the water and the inner wall of the second cooling groove, and further improving the heat dissipation effect on the connecting rod, avoiding the material performance degradation of the connecting rod due to high temperature;

[0028] 3、The second one-way valve of the application can prevent the fluid in the backflow channel from flowing back to the front tank, ensuring the one-way flow of the cooling circuit, especially for the case that the water inlet is connected to a high-pressure water source; when the piston rod is in the water pumping state, the piston head moves towards the front tank side, at this time the first one-way valve is closed, and under the volume change of the front tank, the piston head will press the water and air in the front tank back to the water inlet; when the piston rod is in the water pumping state, the piston head moves towards the rear tank side, at this time the first one-way valve is opened, the second one-way valve is closed, and the front tank is inhaled, realizing the circulation. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the overall structure of the embodiment of the application.

[0030] Figure 2 is a sectional view along the A-A line in Figure 1

[0031] Figure 3 is an enlarged view of B in Figure 2

[0032] BRIEF DESCRIPTION OF DRAWINGS: 1, pump body; 11, water inlet; 12, water outlet; 13, crank cavity; 14, piston cavity; 15, inlet valve cavity; 16, outlet valve cavity; 17, backflow channel; 18, mounting groove; 2, crank assembly; 21, crankshaft; 22, pump shaft; 3, piston assembly; 31, piston rod; 311, first cooling tank; 32, connecting block; 321, communication groove; 33, connecting rod; 331, second cooling tank; 3311, front tank; 3312, rear tank; 333, sliding groove; 34, annular gap; 35, communication channel; 4, sleeve block; 41, left block; 42, right block; 421, first ring groove; 43, open groove; 44, sealing ring; 45, first sealing ring; 5, first one-way valve; 6, inlet and outlet valve assembly; 61, inlet one-way valve; 62, outlet one-way valve; 71, nozzle; 72, second one-way valve; 8, volume change assembly; 81, piston head; 82, fixed block; 83, butt block; 831, butt ring groove; 9, air inlet balance assembly; 91, third one-way valve; 92, mounting hole; 93, first groove; 94, second groove. DETAILED DESCRIPTION

[0033] The application will be further described in detail below in conjunction with the accompanying Figures 1-3 The application will be further described in detail below in conjunction with the accompanying

[0034] The application discloses a crankshaft pump.

[0035] Reference is made to Figures 1-3 ​​The crankshaft pump of the embodiment comprises a pump body 1, a crankshaft assembly 2, a plurality of piston assemblies 3 and an inlet and outlet valve assembly 6. The pump body 1 is provided with a water inlet 11, a water outlet 12, a crankshaft cavity 13, a plurality of piston cavities 14 and a plurality of valve cavities. The crankshaft assembly 2 is installed in the crankshaft cavity 13. The plurality of piston assemblies 3 are respectively arranged in the plurality of piston cavities 14. The valve cavities are connected with the piston cavities 14, the water inlet 11 and the water outlet 12. The inlet and outlet valve assembly 6 is installed in the valve cavities.

[0036] Referring to Figures 1-3 The plurality of valve cavities comprise a plurality of inlet valve cavities 15 and a plurality of outlet valve cavities 16. The plurality of inlet valve cavities 15 are connected with the piston cavities 14 and the water inlet 11. The plurality of outlet valve cavities 16 are connected with the piston cavities 14 and the water outlet 12. The inlet and outlet valve assembly 6 comprises a plurality of inlet one-way valves 61 and outlet one-way valves 62. The inlet one-way valves 61 are installed in the inlet valve cavities 15. The outlet one-way valves 62 are installed in the outlet valve cavities 16.

[0037] Referring to Figures 1-3 The crankshaft assembly 2 comprises a crankshaft 21 and a pump shaft 22. The crankshaft 21 is supported on the end walls of the crankshaft cavity 13 through bearings. The pump shaft 22 is eccentrically arranged in the middle of the crankshaft 21 and extends out of the pump body 1 for connecting with a motor.

[0038] Referring to Figures 1-3 The piston assembly 3 comprises a piston rod 31, a sleeve block 4, a connecting block 32 and a connecting rod 33. The piston rod 31 is arranged in the piston cavity 14 and sealingly and slidably connected with the inner wall of the piston cavity 14. The two ends of the connecting block 32 are respectively threadedly connected with the piston rod 31 and the connecting rod 33. The other end of the connecting rod 33 is connected with the crankshaft assembly 2. The sleeve block 4 is installed in the pump body 1. The piston rod 31 and the connecting rod 33 are both arranged in the sleeve block 4 and sealingly and slidably connected with the two ends of the sleeve block 4. A sealed annular gap 34 is formed between the sleeve block 4 and the connecting rod 33 and the piston rod 31.

[0039] Referring to Figures 1-3 A first cooling groove 311 is formed in the piston rod 31. A second cooling groove 331 is formed in the connecting rod 33. A communication groove 321 is formed in the connecting block 32 and communicates with the first cooling groove 311 and the second cooling groove 331. A first one-way valve 5 is installed in the communication groove 321 and allows fluid to enter the second cooling groove 331 in one direction only. A communication passage 35 is formed in the inner wall of the second cooling groove 331 and communicates with the annular gap 34. An open groove 43 is formed in the sleeve block 4 and communicates with the annular gap 34. A return channel 17 is formed in the pump body 1 and communicates with the open groove 43 and the water inlet 11.

[0040] Referring to Figures 1-3, the fluid in the pump body 1 can be used to cool the piston rod 31 and the connecting rod 33: when the piston rod 31 pumps water, the first one-way valve 5 is closed; when the piston rod 31 pumps water, water can not only be pumped out of the water outlet 12, but also open the first one-way valve 5 into the second cooling groove 331, and then the water in the second cooling groove 331 enters the annular gap 34 through the communication channel 35, and finally returns to the water inlet 11 through the open groove 43 and the backflow channel 17, forming a circulating cooling path, effectively removing the heat generated by the piston rod 31 and the connecting rod 33 due to friction and medium impact, preventing the two from causing material performance degradation due to high temperature, thereby ensuring that the crankshaft 21 pump works stably for a long time and prolongs the overall service life.

[0041] Referring to Figures 1-3 , in order to facilitate the installation of the sleeve block 4 and each component, the sleeve block 4 is split into a left block body 41 and a right block body 42, and the end faces of the left block body 41 and the right block body 42 are tightly abutted. The left block body 41 and the piston rod 31 are in sealing sliding fit, and a sealing ring 44 is installed therebetween. The right block body 42 and the connecting rod 33 are in sealing sliding fit, and a sealing ring 44 is installed therebetween. The outer walls of the left block body 41 and the right block body 42 are provided with sealing ring grooves, and the sealing ring grooves are provided with first sealing rings 45. The open groove 43 is provided on the right block body 42.

[0042] Referring to Figures 1-3 , the water inlet 11 is located below the water outlet 12, and the backflow channel 17 is located above the water inlet 11 and below the annular gap 34. The backflow channel 17 is located on the side of the water inlet 11 away from the valve cavity, and is inclined.

[0043] Referring to Figures 1-3 , the communication groove 321 is provided with a nozzle 71, and the nozzle 71 is located on the side of the first one-way valve 5 facing the second cooling groove 331.

[0044] Referring to Figures 1-3 , the nozzle 71 can spray the water entering the second cooling groove 331 in the form of high-pressure jet, thereby enhancing the contact efficiency and impact force of the water and the inner wall of the second cooling groove 331, and further improving the heat dissipation effect of the connecting rod 33, thereby preventing the connecting rod 33 from causing material performance degradation due to high temperature.

[0045] Referring to Figures 1-3 , the nozzle 71 is a hollow cone nozzle. The hollow cone nozzle can make the cooling fluid form a fan-shaped or conical diffusion spray, greatly expand the contact area of the cooling fluid and the inner wall of the second cooling groove 331, and more evenly cover the heating area of the connecting rod 33 compared with the ordinary straight nozzle 71, thereby further optimizing the uniformity and efficiency of heat dissipation.

[0046] Referring to Figures 1-3The second one-way valve 72 is arranged in the communication channel 35 and only allows water in the second cooling groove 331 to flow to the annular gap 34. The volume change assembly 8 comprises a movable piston head 81 which is slidably connected in the second cooling groove 331. The piston head 81 divides the second cooling groove 331 into a front groove 3311 and a rear groove 3312 which are not communicated with each other. The nozzle 71 acts on the front groove 3311, and the communication channel 35 only communicates with the front groove 3311.

[0047] With reference to Figures 1-3 When the piston rod 31 is in the water pumping state, the piston head 81 moves towards the front groove 3311. When the piston rod 31 is in the water pumping state, the piston head 81 moves towards the rear groove 3312. The air balance assembly 9 is used to balance the air pressure in the rear groove 3312 when the piston head 81 moves towards the front groove 3311, and balance the air pressure in the front groove 3311 and the rear groove 3312 when the piston head 81 moves towards the rear groove 3312. The single water injection amount of the nozzle 71 is less than the single volume change amount of the front groove 3311.

[0048] With reference to Figures 1-3 The second one-way valve 72 can prevent the fluid in the return channel 17 from flowing back to the front groove 3311, thereby ensuring the one-way flow of the cooling circuit. In particular, when the water inlet 11 is connected to a high-pressure water source, the water in the water inlet 11 can fill the annular gap 34 and surround the outer part of the connecting rod 33 for cooling. When the piston rod 31 is in the water pumping state, the piston head 81 moves towards the front groove 3311. At this time, the first one-way valve 5 is closed, and the piston head 81 pushes the water in the front groove 3311 and the air back to the water inlet 11 due to the volume change of the front groove 3311. When the piston rod 31 is in the water pumping state, the piston head 81 moves towards the rear groove 3312. At this time, the first one-way valve 5 is opened, the second one-way valve 72 is closed, and the front groove 3311 is supplied with air, thereby realizing the circulation.

[0049] With reference to Figures 1-3 The volume change assembly 8 further comprises a fixed block 82 and a butt joint block 83. The butt joint block 83 is coaxially fixed on the side of the piston head 81 facing the rear groove 3312. The fixed block 82 is arranged in an L shape. The pump body 1 is provided with a mounting groove 18 matched with the fixed block 82. The top end of the fixed block 82 is fixed in the mounting groove 18 by screws. The butt joint block 83 is provided with a butt joint ring groove 831 around it. The inner wall of the side of the rear groove 3312 facing the mounting groove 18 is provided with a sliding groove 333 for the sliding of the fixed block 82. The bottom end of the fixed block 82 is inserted into the butt joint ring groove 831 after passing through the sliding groove 333. The sliding groove 333 is located on the side of the annular gap 34 close to the crankshaft assembly 2. The piston head 81 is always located on the side of the sliding groove 333 away from the crankshaft assembly 2.

[0050] With reference to Figures 1-3The fixed block 82 is fixed in the mounting groove 18 of the pump body 1, and the fixed block 82 is fixedly connected with the abutting block 83, so that the piston head 81 is always kept stationary with the pump body 1, and when the connecting rod 33 is driven by the crankshaft assembly 2 to move, the piston head 81 can slide with the connecting rod 33, so as to control the volume change of the front groove 3311.

[0051] With reference to Figures 1-3 The intake balance assembly 9 comprises a third one-way valve 91, a mounting hole 92, a first groove 93 and a second groove 94. The first groove 93 is arranged in the pump body 1 and is located at the side of the annular gap 34 close to the crankshaft assembly 2. The first groove 93 is communicated with the sliding groove 333. The second groove 94 is arranged on the outer side wall of the fixed block 82 along the length direction of the fixed block 82. The first groove 93, the second groove 94 and the sliding groove 333 are communicated with each other. The mounting hole 92 is arranged on the connecting rod 33 and is communicated with the first groove 93 and the front groove 3311 at two ends respectively. The third one-way valve 91 is arranged in the mounting hole 92 and is used for allowing only external gas to enter the front groove 3311.

[0052] With reference to Figures 1-3 When the piston head 81 moves towards the rear groove 3312, the first one-way valve 5 is opened, the water is sprayed from the nozzle 71, and the second one-way valve 72 is closed. At the same time, the external gas can enter the front groove 3311 through the third one-way valve 91 to balance the gas pressure. When the piston head 81 moves towards the front groove 3311, the first one-way valve 5 and the third one-way valve 91 are both closed, and the second one-way valve 72 is opened. The water and the gas in the front groove 3311 are simultaneously pressed into the annular gap 34, so as to realize the efficient circulation of cooling.

[0053] With reference to Figures 1-3 When the piston rod 31 moves forward to the limit position of the water pumping state, and the piston head 81 moves to the abutting block 83 and abuts against the end wall of the rear groove 3312, the bottom end of the fixed block 82 is opposite to the abutting ring groove 831. A reliable position relationship is provided for the abutting of the fixed block 82 and the abutting block 83. In order to further facilitate the connection of the fixed block 82 and the abutting block 83, the end part of the abutting ring groove 831 is arranged in an expanded shape, so as to facilitate the insertion of the fixed block 82.

[0054] With reference to Figures 1-3 Figures 1-3 The first ring groove 421 is arranged on the right block body 42 along the circumferential outer wall, and the opening groove 43 is communicated with the backflow channel 17 through the first ring groove 421. No matter how the sleeve block 4 is installed, the first ring groove 421 can always keep communication with the backflow channel 17, so as to improve the convenience of the installation of the sleeve block 4.

[0055] Of course, the above is only a typical example of the present application, and in addition to this, the present application can have other various specific implementation manners. Any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection of the present application.

Claims

1. A crankshaft pump characterized by: The pump body (1) is provided with a water inlet (11), a water outlet (12), a crankshaft cavity (13), a plurality of piston cavities (14) and a plurality of valve cavities, the crankshaft assembly (2) is installed in the crankshaft cavity (13), a plurality of piston assemblies (3) are respectively arranged in the plurality of piston cavities (14), the valve cavities are communicated with the piston cavities (14), the water inlet (11) and the water outlet (12), and the water inlet and outlet valve assembly (6) is installed in the valve cavity; The piston assembly (3) comprises a piston rod (31), a sleeve block (4), a connecting block (32) and a connecting rod (33), the piston rod (31) is arranged in the piston cavity (14) and in sealing sliding fit with the inner wall of the piston cavity (14), the connecting block (32) is respectively installed on the piston rod (31) and the connecting rod (33), the other end of the connecting rod (33) is connected with the crankshaft assembly (2), the sleeve block (4) is installed in the pump body (1), the piston rod (31) and the connecting rod (33) are arranged in the sleeve block (4) and are in sealing sliding fit with the two ends of the sleeve block (4) respectively, and the sleeve block (4) and the connecting rod (33) and the piston rod (31) form a sealed annular gap (34) therebetween; The piston rod (31) is provided with a first cooling groove (311), the connecting rod (33) is provided with a second cooling groove (331), the connecting block (32) is provided with a communication groove (321) communicating the first cooling groove (311) and the second cooling groove (331), the communication groove (321) is provided with a first one-way valve (5) allowing fluid to enter the second cooling groove (331) in one direction only, the inner wall of the second cooling groove (331) is provided with a communication channel (35) communicating with the annular gap (34), the sleeve block (4) is provided with an opening groove (43) communicating with the annular gap (34), and the pump body (1) is provided with a backflow channel (17) communicating the opening groove (43) with the water inlet (11); The communication groove (321) is provided with a nozzle (71) located on the side of the first one-way valve (5) facing the second cooling groove (331); The second one-way valve (72), the volume change assembly (8) and the air inlet balance assembly (9) are further included, the second one-way valve (72) is arranged in the communication channel (35) and allows water in the second cooling groove (331) to flow to the annular gap (34) only, the volume change assembly (8) comprises a movable piston head (81), the piston head (81) is in sliding connection in the second cooling groove (331), the piston head (81) divides the second cooling groove (331) into a front groove (3311) and a rear groove (3312) which are not communicated with each other, the nozzle (71) acts on the front groove (3311), and the communication channel (35) is communicated with the front groove (3311) only. The piston head (81) moves towards the front groove (3311) side when the piston rod (31) is in the water pumping state, and the piston head (81) moves towards the rear groove (3312) side when the piston rod (31) is in the water pumping state; the air inlet balance assembly (9) is used to balance the air pressure in the rear groove (3312) during the movement of the piston head (81) towards the front groove (3311) side, and balance the air pressure of the front groove (3311) and the rear groove (3312) during the movement of the piston head (81) towards the rear groove (3312) side; the nozzle (71) has a single water injection amount less than the single volume change amount of the front groove (3311).

2. A crankshaft pump according to claim 1, wherein: The nozzle (71) is a hollow cone nozzle.

3. A crankshaft pump according to claim 1, wherein: The volume change assembly (8) further comprises a fixed block (82) and a butt joint block (83), the butt joint block (83) is coaxially fixed on the side of the piston head (81) facing the rear groove (3312), the fixed block (82) is arranged in an L shape, the pump body (1) is provided with a mounting groove (18) matched with the fixed block (82), the top end of the fixed block (82) is fixed in the mounting groove (18) through a screw, the butt joint block (83) is provided with a butt joint ring groove (831) on the circumference, the inner wall of the side of the rear groove (3312) facing the mounting groove (18) is provided with a sliding groove (333) for the sliding of the fixed block (82), the bottom end of the fixed block (82) is inserted into the butt joint ring groove (831) after passing through the sliding groove (333), the sliding groove (333) is located on the side of the annular gap (34) close to the crankshaft assembly (2), and the piston head (81) is always located on the side of the sliding groove (333) away from the crankshaft assembly (2).

4. A crankshaft pump according to claim 3, wherein: The air inlet balance assembly (9) comprises a third one-way valve (91), a mounting hole (92), a first groove (93) and a second groove (94), the first groove (93) is arranged in the pump body (1), the first groove (93) is located on the side of the annular gap (34) close to the crankshaft assembly (2), the first groove (93) is communicated with the sliding groove (333), the second groove (94) is arranged on the outer side wall of the fixed block (82) and penetrates along the length direction of the fixed block (82), and the first groove (93), the second groove (94) and the sliding groove (333) are communicated with each other; the mounting hole (92) is arranged on the connecting rod (33), the two ends of the mounting hole (92) are communicated with the first groove (93) and the front groove (3311) respectively, and the third one-way valve (91) is arranged in the mounting hole (92) and is used for allowing only external air to enter the front groove (3311).

5. A crankshaft pump according to claim 3, wherein: When the piston rod (31) moves forward to the limit position of the water pumping state, and the piston head (81) moves to the butt joint block (83) abutting against the end wall of the rear groove (3312), the bottom end of the fixed block (82) is opposite to the butt joint ring groove (831).

6. A crankshaft pump according to claim 1, wherein: The sleeve block (4) is provided with a first ring groove (421) on the circumferential outer wall, and the opening groove (43) is communicated with the reflux channel (17) through the first ring groove (421).

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