External circulation water pump of small-displacement diesel engine

Abstract

The external circulation water pump of the small-displacement diesel engine comprises a water pump shell and a transmission shell installed on one side of the water pump shell, a water inlet and a water outlet are formed in the water pump shell, and the side, away from the transmission shell, of the water pump shell is detachably connected with an end cover used for sealing the water pump shell. A flexible impeller is installed in the water pump shell, a transmission shaft is installed in the transmission shell, and a water seal is arranged between the water pump shell and the transmission shell. The sealing performance between the transmission shell and the water pump shell can be improved through the water seal, in addition, even if the water seal loses efficacy, the transmission shell exists between the water pump shell and the diesel engine, seawater entering the transmission shell can be rapidly discharged through the through hole, and therefore the seawater cannot enter an engine gearbox, the influence on a diesel engine lubricating system is avoided, and the service life of the diesel engine is prolonged. Normal operation of the diesel engine is ensured.

Description

Technical Field

[0001] The present application relates to the field of water pumps, and in particular to an external circulation water pump for a small-displacement diesel engine. Background Art

[0002] According to the requirements of 4.5.1.1, Part 3 of the China Classification Society's "Rules for Classification of Sea-going Steel Ships", for small-displacement marine diesel engines, when equipped with one main engine, a main cooling water pump with sufficient capacity when the main engine outputs maximum power should be provided. In addition, according to the requirements of 9.4.2.2, Part 3 of the "Rules for Classification of Sea-going Steel Ships", a high-temperature alarm should be set for the water temperature of the diesel engine. This design can provide 10m 3 The flow rate of / h and the head of 6 meters can effectively control the outlet water temperature of small-displacement diesel engines at 90℃, meeting the design and use requirements of small-displacement diesel engines.

[0003] In addition, with the development of technology, users have higher and higher requirements for the ship engine room environment. The diesel engine is the largest heat source in the engine room. Its heat dissipation will cause the temperature in the engine room to rise rapidly, which is not conducive to the power torque output of the diesel engine, nor is it conducive to the maintenance personnel working in the engine room.

[0004] At present, the patent with announcement number CN216406955U discloses an onboard cooling water pump for a marine diesel engine, including an intermediate shaft and a cooling water pump body, a bearing housing and a gearbox housing; the cooling water pump body, the bearing housing and the gearbox housing are respectively installed with a cooling water pump impeller, a bearing and a driving gear connected to the intermediate shaft; the gearbox housing is connected to the diesel engine, and a driving gear meshing with the driving gear is installed on the diesel engine. The cooling water pump is integrated with the diesel engine, and the intermediate shaft is driven by the driving gear meshing with the driving gear, and the cooling water pump impeller is driven by the bearing supporting the intermediate shaft, thereby achieving a higher seawater head and seawater heat exchange, and effectively realizing the cooling and heat dissipation requirements of the diesel engine.

[0005] Regarding the above-mentioned related technologies, the inventors believe that the following defects exist: the water pump has a complex structure, the casting cost is high, the water chamber part and the driving part are very close, and once the water seal fails, seawater will leak into the driving part and mix with the engine oil, thereby affecting the normal operation of the diesel engine. Therefore, it needs to be improved. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present application provides an external circulation water pump for a small-displacement diesel engine, aiming to solve the above-mentioned problems.

[0007] An external circulation water pump for a small-displacement diesel engine comprises a water pump housing and a transmission housing installed on one side of the water pump housing, the water pump housing being provided with a water inlet and a water outlet, the side of the water pump housing facing away from the transmission housing being detachably connected with an end cover for closing the water pump housing, a flexible impeller being installed in the water pump housing, a transmission shaft being installed inside the transmission housing, one end of the transmission shaft extending into the water pump housing and connected with the impeller, the other end extending out of the transmission housing and connected with a driving gear, a water seal being arranged between the water pump housing and the transmission housing, the water seal sleeve being arranged on the transmission shaft, a card slot for the water seal to be inserted into the water pump housing, a plurality of through holes being spaced apart on the circumferential outer side wall of the transmission housing at one end close to the water pump housing, and a fixing portion for fixing to the diesel engine being connected to the outer wall of the transmission housing.

[0008] By adopting the above technical solution, the water seal can improve the sealing between the transmission housing and the water pump housing. In addition, even if the water seal fails, there is still a transmission housing between the water pump housing and the diesel engine, and the seawater entering the transmission housing can be quickly discharged through the through hole. Therefore, seawater cannot enter the engine gear box, thereby avoiding affecting the diesel engine lubrication system and ensuring the normal operation of the diesel engine.

[0009] Optionally, the transmission shaft is sleeved with a first rotating bearing and a second rotating bearing, and the inner side wall of the transmission housing is correspondingly provided with a first thrust groove for the first rotating bearing to be inserted into and a second thrust groove for the second rotating bearing to be inserted into.

[0010] Optionally, the first rotating bearing is a single-row deep groove ball bearing, and the second rotating bearing is a double-row deep groove ball bearing.

[0011] By adopting the above technical solutions, double-row deep groove ball bearings have higher radial and axial load capacity than single-row deep groove ball bearings, and can better withstand larger loads, ensuring the stability and reliability of the drive shaft under high load or unstable working conditions. Secondly, double-row deep groove ball bearings can provide better axial positioning and reduce the axial movement of the shaft, thereby improving the operating stability of the entire pump system, reducing vibration and noise, and extending the service life of the pump. Single-row deep groove ball bearings are suitable for applications with light to medium loads and perform well at high speeds, ensuring high precision of the drive shaft, reducing friction and wear, and improving the operating efficiency of the pump. In addition, deep groove ball bearings have a simple structure and are easy to maintain. Single-row deep groove ball bearings are easy to replace and maintain, while double-row deep groove ball bearings provide a longer service life and reduce maintenance frequency. This combined design can adapt to a variety of working conditions, whether it is light load or heavy load, it can provide good support and protection to ensure stable operation of the pump under various conditions.

[0012] Optionally, the transmission shaft is a spline transmission shaft, a copper sleeve is embedded in the middle of the impeller, and the copper sleeve is sleeved on the spline shaft of the transmission shaft.

[0013] Optionally, a filter grid is installed on the inner side wall of the water pump housing at the water inlet.

[0014] By adopting the above technical solution, the filter grid can prevent foreign matter from entering the water pump housing, while reducing cavitation and reducing the impact damage of cavitation on the impeller.

[0015] Optionally, the driving gear is sleeved on one end of a transmission shaft, and a gear bolt for fixing the driving gear is threadedly connected to the transmission shaft.

[0016] Optionally, a sealing ring is provided at one end of the transmission housing close to the driving gear.

[0017] By adopting the above technical solution, the sealing ring can improve the sealing performance between the transmission housing and the diesel engine.

[0018] Optionally, a sealant is provided between the end cover and the water pump housing, and the end cover and the water pump housing are fixed by a plurality of mounting bolts.

[0019] By adopting the above technical solution, the sealant can improve the sealing performance between the end cover and the water pump housing.

[0020] Optionally, the impeller is made of EPDM rubber.

[0021] By adopting the above technical scheme, firstly, EPDM rubber has excellent chemical corrosion resistance, can resist the erosion of various acid, alkali and other chemical substances, is suitable for conveying liquids containing corrosive media, and prolongs the service life of the impeller; secondly, EPDM rubber maintains good physical properties in a wide temperature range, can work normally in high or low temperature environments, and adapts to different working conditions; in addition, EPDM rubber has good wear resistance, can reduce the wear caused by solid particles in the liquid, and improve the durability of the impeller. EPDM rubber also has good softness and elasticity, can absorb vibration and impact to a certain extent, reduce noise, and improve the smooth operation of the pump. EPDM rubber material is easy to process and shape, and can produce precise impeller shapes to meet various design requirements.

[0022] Optionally, the end cover and the water pump housing are both made of copper-zinc alloy.

[0023] By adopting the above technical scheme, the copper-zinc alloy has good corrosion resistance, especially in water environment, which helps to extend the service life of the water pump. Secondly, the copper-zinc alloy has sufficient mechanical strength and hardness to withstand pressure and wear, ensuring the stability and reliability of the water pump. In addition, the copper-zinc alloy has good processing performance and is easy to cast, forge and machine, which is convenient for manufacturing parts with complex shapes. At the same time, its high thermal conductivity helps to improve heat exchange efficiency, which is particularly beneficial for parts that need heat dissipation. The copper-zinc alloy also has a good appearance and natural brightness, and can maintain its beauty without additional treatment.

[0024] In summary, the present application includes at least one of the following beneficial technical effects:

[0025] 1. The water seal can improve the sealing between the transmission housing and the water pump housing. In addition, even if the water seal fails, there is still a transmission housing between the water pump housing and the diesel engine. The seawater entering the transmission housing can also be quickly discharged through the through hole. Therefore, seawater cannot enter the engine gearbox, thereby avoiding affecting the diesel engine lubrication system and ensuring the normal operation of the diesel engine.

[0026] 2. Double-row deep groove ball bearings have higher radial and axial load capacity than single-row deep groove ball bearings, and can better withstand larger loads, ensuring the stability and reliability of the drive shaft under high load or unstable working conditions. Secondly, double-row deep groove ball bearings can provide better axial positioning and reduce the axial movement of the shaft, thereby improving the operating stability of the entire pump system, reducing vibration and noise, and extending the service life of the pump. Single-row deep groove ball bearings are suitable for applications with light to medium loads and perform well at high speeds, ensuring high precision of the drive shaft, reducing friction and wear, and improving the operating efficiency of the pump. In addition, deep groove ball bearings have a simple structure and are easy to maintain. Single-row deep groove ball bearings are easy to replace and maintain, while double-row deep groove ball bearings provide a longer service life and reduce maintenance frequency. This combined design can adapt to a variety of working conditions, whether it is light load or heavy load, it can provide good support and protection, ensuring stable operation of the pump under various conditions.

[0027] 3. EPDM has excellent chemical corrosion resistance and can resist the erosion of various acids, alkalis and other chemical substances. It is suitable for conveying liquids containing corrosive media and extending the service life of the impeller. Secondly, EPDM maintains good physical properties in a wide temperature range and can work normally in both high and low temperature environments and adapt to different working conditions. In addition, EPDM has good wear resistance, which can reduce the wear caused by solid particles in the liquid and improve the durability of the impeller. EPDM also has good softness and elasticity, which can absorb vibration and impact to a certain extent, reduce noise and improve the smooth operation of the pump. EPDM material is easy to process and shape, and can produce precise impeller shapes to meet various design requirements.

[0028] 4. Copper-zinc alloy has good corrosion resistance, especially in water environment, which helps to extend the service life of the water pump. Secondly, copper-zinc alloy has sufficient mechanical strength and hardness to withstand pressure and wear, ensuring the stability and reliability of the water pump. In addition, copper-zinc alloy has good processing performance and is easy to cast, forge and machine, making it convenient to manufacture parts with complex shapes. At the same time, its high thermal conductivity helps to improve heat exchange efficiency, which is particularly beneficial for parts that need heat dissipation. Copper-zinc alloy also has a good appearance, natural brightness, and can maintain its beauty without additional treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of an embodiment of the present application.

[0030] Figure 2 It is a cross-sectional schematic diagram of an embodiment of the present application.

[0031] Figure 3 It is an exploded schematic diagram of an embodiment of the present application.

[0032] Description of reference numerals:

[0033] 1. End cover; 11. Mounting bolts; 2. Impeller; 3. Pump housing; 31. Water inlet; 311. Filter grille; 32. Water outlet; 33. Water seal; 4. Transmission shaft; 41. First rotating bearing; 42. Second rotating bearing; 5. Transmission housing; 51. Fixing bolts; 52. Through hole; 6. Driving gear; 61. Gear bolts; 7. Sealing ring. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are for illustrative purposes only.

[0035] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0036] The present application embodiment discloses an external circulation water pump for a small displacement diesel engine. Figure 1 and Figure 2 , including a water pump housing 3 and a transmission housing 5 installed on one side of the water pump housing 3 through fixing bolts 51.

[0037] Reference Figure 2 and Figure 3 The water pump housing 3 is provided with a water inlet 31 and a water outlet 32. The side of the water pump housing 3 facing away from the transmission housing 5 is detachably connected with an end cover 1 for closing the water pump housing 3. The end cover 1 is made of copper-zinc alloy H59-GB / T5231, which has good corrosion resistance. The outer edge of the inner surface of the end cover 1 is milled with IT8 grade precision, and Loctite SI587 flat sealant is applied when sealing with the end face of the water pump housing 3. The end cover 1 is fixed to the water pump housing 3 by six mounting bolts 11. The mounting bolts 11 are high-strength flange bolts with a tightening torque of 35Nm. Considering that the cooling medium transported by the external circulation water pump in most cases is seawater, which is highly corrosive, the surface of the mounting bolts 11 is coated with zinc-aluminum coating for rust prevention, and Dacromet treatment can effectively inhibit seawater corrosion.

[0038] Reference Figure 2 and Figure 3A flexible impeller 2 is installed in the water pump housing 3, and a transmission shaft 4 is installed inside the transmission housing 5. One end of the transmission shaft 4 extends into the water pump housing 3 and is connected to the impeller 2, and the other end extends out of the transmission housing 5 and is connected to the driving gear 6. A water seal 33 is arranged between the water pump housing 3 and the transmission housing 5. The water seal 33 is sleeved on the transmission shaft 4. A slot for the water seal 33 to be inserted is provided on the water pump housing 3, and a dustproof felt is provided on the outer end of the water seal 33. A plurality of through holes 52 are spaced apart on the circumferential outer wall of the transmission housing 5 at one end close to the water pump housing 3, and a fixing part for fixing to the diesel engine is fixedly connected to the outer wall of the transmission housing 5. The maintenance, repair and replacement of the impeller 2 and the water seal 33 of the external circulation water pump are all carried out through the end cover 1. The end cover 1 is located on the side of the external circulation water pump, with sufficient space and convenient disassembly and assembly. The water seal 33 can improve the sealing performance between the transmission housing 5 and the water pump housing 3. In addition, even if the water seal 33 fails, there is still the transmission housing 5 between the water pump housing 3 and the diesel engine, and the seawater entering the transmission housing 5 can be quickly discharged through the through hole 52. Therefore, the seawater cannot enter the engine gearbox, thereby avoiding affecting the diesel engine lubrication system and ensuring the normal operation of the diesel engine. The impeller 2 is a flexible impeller 2, which is made of EPDM rubber. First, EPDM has excellent chemical corrosion resistance and can resist the erosion of various acids, alkalis and other chemical substances. It is suitable for conveying liquids containing corrosive media and extending the service life of the impeller 2. Secondly, EPDM maintains good physical properties in a wide temperature range and can work normally regardless of high or low temperature environments and adapt to different working conditions. In addition, EPDM has good wear resistance and can reduce the wear caused by solid particles in the liquid and improve the durability of the impeller 2. EPDM also has good softness and elasticity and can absorb vibration and impact to a certain extent, reduce noise and improve the smooth operation of the pump. EPDM is easy to process and shape, and can produce precise impeller 2 shapes to meet various design requirements.

[0039] Reference Figure 2 and Figure 3 The water pump housing 3 is made of copper-zinc alloy H59-GB / T 5231. The copper-zinc alloy has good corrosion resistance, especially in water environment, which helps to extend the service life of the water pump. Secondly, the copper-zinc alloy has sufficient mechanical strength and hardness to withstand pressure and wear, ensuring the stability and reliability of the water pump. In addition, the copper-zinc alloy has good processing performance, is easy to cast, forge and machine, and is convenient for manufacturing parts with complex shapes. At the same time, its high thermal conductivity helps to improve the heat exchange efficiency, which is particularly beneficial for parts that need to dissipate heat.

[0040] Reference Figure 2 and Figure 3The inner cavity of the water pump housing 3 is composed of two eccentric arcs intersecting, with a radius difference of 5mm and an eccentric distance of 10mm. When the impeller 2 rotates to the eccentric piece in the inner cavity of the water pump housing 3, the impeller 2 is squeezed and bent to form a vacuum. The pressure difference between the inside and the outside sucks the cooling medium into the water pump housing 3 through the water inlet 31. The impeller 2 rotates at a high speed. When the impeller 2 rotates to the eccentric piece again, it is squeezed by the inner cavity of the water pump housing 3. The cooling medium is discharged smoothly from the pump body through the water outlet 32. The high-speed rotation of the impeller 2 drives the cooling medium to enter the water inlet 31 and spray out from the water outlet 32. According to the test, the self-priming height of the water inlet 31 is 1.5m / 10s. When the speed of the small-displacement diesel engine reaches 3000rpm, the speed of the impeller 2 of the external circulation water pump is the same, and the pressure of the water inlet 31 reaches ≥60kPa, and the flow rate is ≥170L / min.

[0041] Reference Figure 2 and Figure 3 The inner wall of the water pump housing 3 is fixedly connected with a filter grid 311 at the water inlet 31. The filter grid 311 can prevent foreign matter from entering the water pump housing 3, and at the same time can reduce cavitation and reduce the impact damage of cavitation on the impeller 2.

[0042] Reference Figure 2 and Figure 3 The transmission shaft 4 is a spline transmission shaft, and a copper sleeve is embedded in the middle of the impeller 2. The impeller 2 and the copper sleeve are bonded by vulcanization. A spline inner hole is opened in the middle of the copper sleeve, and the copper sleeve is fixedly sleeved on the spline shaft of the transmission shaft 4 through the spline inner hole.

[0043] Reference Figure 2 and Figure 3, the transmission shaft 4 is sleeved with a first rotating bearing 41 and a second rotating bearing 42, and the inner side wall of the transmission housing 5 is correspondingly provided with a first thrust groove for the first rotating bearing 41 to be inserted into and a second thrust groove for the second rotating bearing 42 to be inserted into. The first thrust groove and the second thrust groove completely constrain the transmission shaft 4, the first rotating bearing 41 is a single-row deep groove ball bearing, and the second rotating bearing 42 is a double-row deep groove ball bearing. Compared with single-row deep groove ball bearings, double-row deep groove ball bearings have higher radial and axial load-bearing capacity, can better withstand larger loads, and ensure the stability and reliability of the drive shaft under high load or unstable working conditions. Secondly, double-row deep groove ball bearings can provide better axial positioning, reduce the axial movement of the shaft, thereby improving the operating stability of the entire pump system, reducing vibration and noise, and extending the service life of the pump. Single-row deep groove ball bearings are suitable for light to medium load applications, and perform well at high speeds, ensuring high precision of the drive shaft, reducing friction and wear, and improving the operating efficiency of the pump. In addition, deep groove ball bearings have a simple structure and are easy to maintain. Single-row deep groove ball bearings are easy to replace and maintain, while double-row deep groove ball bearings provide a longer service life and reduce maintenance frequency. This combination design can adapt to a variety of working conditions, whether it is light load or heavy load, it can provide good support and protection to ensure the stable operation of the pump under various conditions.

[0044] Reference Figure 2 and Figure 3 The driving gear 6 is sleeved on one end of the transmission shaft 4 , and a gear bolt 61 for fixing the driving gear 6 is threadedly connected on the transmission shaft 4 . The rotation direction of the water pump is consistent with the tightening direction of the gear bolt 61 .

[0045] Reference Figure 2 and Figure 3 A sealing ring 7 is sleeved on one end of the transmission housing 5 close to the driving gear 6, and the sealing ring 7 can improve the sealing performance between the transmission housing 5 and the diesel engine.

[0046] The implementation principle of the external circulation water pump of a small-displacement diesel engine in the embodiment of the present application is as follows: when the small-displacement diesel engine is working, its gear chamber drives the external circulation water pump driving gear 6 to rotate through the intermediate gear, with a speed ratio of 1:1, and the driving gear 6 drives the impeller 2 to rotate in the water pump housing 3 through the transmission shaft 4. The impeller 2 rotates to the eccentric piece of the inner cavity of the water pump housing 3, is squeezed and bent to form a vacuum, and the pressure difference between the inside and the outside sucks the cooling medium into the water pump housing 3 through the water inlet 31, and the external circulation water pump rotates at a high speed. When the impeller 2 rotates to the eccentric piece again, it is squeezed by the inner cavity of the water pump housing 3, and the cooling medium is smoothly discharged from the pump body through the seawater outlet. The high-speed rotation of the impeller 2 drives the cooling medium from the water inlet 31 to the water outlet 32. The high-speed rotation of the impeller 2 forms the flow and head of the external circulation water pump; the water seal 33 and the sealing ring 7 ensure the sealing state of the water cavity and the lubrication system. The driving gear 6 is lubricated by the oil splash in the gear chamber of the diesel engine, and the first rotating bearing 41 and the second rotating bearing 42 are maintenance-free bearings with the characteristics of high performance and long life. The impeller 2 and the water seal 33 are replaced by disassembling the end cover 1. The end cover 1 is located on the side of the water pump housing 3, which is convenient for disassembly and maintenance.

[0047] The present application can be directly installed on a small-displacement diesel engine, reducing the risks brought by the user's self-installation and improving the user experience; in addition, the use of gear transmission improves the transmission efficiency and avoids the use of a V-belt in a traditional seawater pump, where the aging and breakage of the belt will cause overheating and damage to the diesel engine; the present application has a simple structure and is easy to install. It adopts a proprietary water seal 33 and oil seal arrangement method to improve the sealing effect, while avoiding the impact of the failure of the water seal 33 on the lubrication system of the small-displacement diesel engine.

[0048] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An external circulation water pump for a small displacement diesel engine, characterized in that: The invention comprises a water pump housing (3) and a transmission housing (5) installed on one side of the water pump housing (3); the water pump housing (3) is provided with a water inlet (31) and a water outlet (32); a side of the water pump housing (3) facing away from the transmission housing (5) is detachably connected with an end cover (1) for sealing the water pump housing (3); a flexible impeller (2) is installed in the water pump housing (3); a transmission shaft (4) is installed inside the transmission housing (5); one end of the transmission shaft (4) extends into the water pump housing (3) and is connected to the impeller (2) is connected, and the other end extends out of the transmission housing (5) and is connected to a driving gear (6). A water seal (33) is arranged between the water pump housing (3) and the transmission housing (5). The water seal (33) is sleeved on the transmission shaft (4). The water pump housing (3) is provided with a slot for the water seal (33) to be inserted. A plurality of through holes (52) are spaced apart on the circumferential outer wall of the transmission housing (5) near one end of the water pump housing (3). A fixing portion for fixing to a diesel engine is connected to the outer wall of the transmission housing (5).

2. The external circulation water pump for a small displacement diesel engine according to claim 1, characterized in that: The transmission shaft (4) is sleeved with a first rotating bearing (41) and a second rotating bearing (42), and the inner side wall of the transmission housing (5) is correspondingly provided with a first thrust groove for the first rotating bearing (41) to be inserted into and a second thrust groove for the second rotating bearing (42) to be inserted into.

3. The external circulation water pump for a small displacement diesel engine according to claim 2, characterized in that: The first rotating bearing (41) is a single-row deep groove ball bearing, and the second rotating bearing (42) is a double-row deep groove ball bearing.

4. The external circulation water pump for a small displacement diesel engine according to claim 1, characterized in that: The transmission shaft (4) is a spline transmission shaft (4), a copper sleeve is embedded in the middle of the impeller (2), and the copper sleeve is sleeved on the spline shaft of the transmission shaft (4).

5. The external circulation water pump for a small displacement diesel engine according to claim 1, characterized in that: A filter grid (311) is installed on the inner side wall of the water pump housing (3) at the water inlet (31).

6. The external circulation water pump for a small displacement diesel engine according to claim 1, characterized in that: The driving gear (6) is sleeved on one end of the transmission shaft (4), and a gear bolt (61) for fixing the driving gear (6) is threadedly connected to the transmission shaft (4).

7. The external circulation water pump for a small displacement diesel engine according to claim 1, characterized in that: A sealing ring (7) is sleeved on one end of the transmission housing (5) close to the driving gear (6).

8. The external circulation water pump for a small displacement diesel engine according to claim 1, characterized in that: A sealant is provided between the end cover (1) and the water pump housing (3), and the end cover (1) and the water pump housing (3) are fixed by a plurality of mounting bolts (11).

9. The external circulation water pump for a small displacement diesel engine according to claim 1, characterized in that: The impeller (2) is made of EPDM rubber.

10. The external circulation water pump for a small displacement diesel engine according to claim 1, characterized in that: The end cover (1) and the water pump housing (3) are both made of copper-zinc alloy.

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