JP7486892B2 - Structure of cooling water pump for internal combustion engine - Google Patents

Description

The present invention relates to the structure of a mechanical cooling water pump in a water-cooled internal combustion engine.

Internal combustion engines installed in vehicles, especially four-wheeled automobiles, are generally water-cooled. Therefore, a cooling water pump that draws in, discharges, and circulates the cooling water for the internal combustion engine is attached to the internal combustion engine.

The mechanical cooling water pumps used in commonly used internal combustion engines are driven by the crankshaft, which is the output shaft of the internal combustion engine, and rotate with engine torque supplied from the crankshaft. Between the crankshaft and the rotating shaft of the cooling water pump, there is a winding transmission mechanism consisting of a pulley and a belt.

The rotating shaft of the cooling water pump has an impeller at its end for pumping cooling water. The rotating shaft is rotatably supported in the pump housing (body) via bearings. A seal, typically a mechanical seal, is provided between the pump chamber in which the impeller is located and the bearing support chamber in which the bearing is installed to prevent the cooling water in the pump chamber from flowing into the bearing chamber.

In reality, the seals are not perfect at sealing the cooling water, and leakage of the cooling water from the pump chamber is inevitable. To prevent the leaked cooling water from filling the bearing chamber and impairing the function of the bearing, the pump housing is provided with an exhaust port that discharges the leaked cooling water to the outside through the area where the seal is installed, and a diffusion passage that discharges the cooling water vapor that has evaporated after leakage to the outside (for example, see the following patent document).

JP 2016-070094 A

Figure 3 shows the structure of a conventional cooling water pump. The above-mentioned discharge port 21 and diffusion passage 582 are connected. In the conventional cooling water pump, the diffusion passage 582 opens into the space 324 inside the bowl-shaped pulley 32, while the discharge port 21 opens in a direction away from the pulley 32.

The front wall 322 of the pulley 32 has through holes 323 that are hollowed out to reduce weight. When the pulley 32 rotates in response to the crankshaft of the internal combustion engine, the air in the space 324 inside the pulley 32 is drawn around by the pulley 32. This creates a flow in which air is sucked into the inner space 324 of the pulley 32 from the through holes 323 on the front side, as shown by the arrows in Figure 3, and then expelled outward from the rear end of the pulley 32.

This air flow creates negative pressure around the dissipation passage 582, creating a pressure difference between the inside of the dissipation passage 582 and the inside of the exhaust port 21. In addition, the wind blowing into the engine room (engine compartment) when the vehicle is moving and the wind generated by the electric fan attached to the radiator that air-cools the coolant enter the vicinity of the exhaust port 21. As a result, air flows into the pump housing 5 from the positively pressurized exhaust port 21, passes near the seal 52, and flows out of the dissipation passage 582. If foreign matter enters the pump housing 5 with the air flow, the foreign matter will get caught in the seal 52, compromising the sealing ability of the seal 52 and raising concerns that the amount of water leakage will increase.

The present invention was developed to address the above problems, and its intended purpose is to prevent foreign matter from entering the pump housing 5.

The cooling water pump for an internal combustion engine according to the present invention comprises a pump housing fixed to the body of the internal combustion engine, a pulley arranged to surround a part of the pump housing and rotating in response to the crankshaft of the internal combustion engine, a rotating shaft connected to the pulley and rotatably supported within the pump housing via a bearing, with an impeller provided at its end, a seal provided between the impeller and the bearing to prevent cooling water from flowing from the impeller side to the bearing side, a flow-down passage through which cooling water leaked through the part where the seal is provided flows down, a leakage water reservoir section for storing the cooling water that has flowed down the flow-down passage, a discharge port opening in the direction toward the pulley and discharging cooling water overflowing from the leakage water reservoir section, and a leakage gap separate from the discharge port, which communicates with the leakage water reservoir section and is not completely sealed to allow leakage of cooling water stored in the leakage water reservoir section. In addition, the leakage gap is configured as a gap between a secondary discharge port that communicates with the leakage water reservoir and opens in a direction toward the main body of the internal combustion engine, and a protrusion that protrudes toward the secondary discharge port and abuts or closely contacts the periphery of the secondary discharge port at a location where the secondary discharge port communicates with the leakage water reservoir, thereby substantially blocking communication between the secondary discharge port and the leakage water reservoir. Note that the height of the position where the secondary discharge port communicates with the leakage water reservoir may be higher than the height of the position of the lower end of the downflow passage that communicates with the leakage water reservoir of the downflow passage, and may be lower than the height of the position where the discharge port communicates with the leakage water reservoir.

The present invention makes it possible to prevent foreign matter from entering the pump housing of a cooling water pump attached to an internal combustion engine.

1 is a side cross-sectional view showing a structure of a cooling water pump for an internal combustion engine according to an embodiment of the present invention; FIG. 2 is a perspective view showing a pump housing of the cooling water pump according to the embodiment. FIG. 11 is a side cross-sectional view showing the structure of a conventional cooling water pump.

One embodiment of the present invention will be described with reference to the drawings. The cooling water pump of the internal combustion engine in this embodiment is a mechanical type that rotates by receiving engine torque from the crankshaft, which is the output shaft of the internal combustion engine, and sucks in and discharges cooling water to circulate it. Between the crankshaft and the rotating shaft 3 of the cooling water pump, there is a winding transmission mechanism consisting of a pulley 32 and a belt 4 as elements.

As is well known, the main body of an internal combustion engine, which is a four-stroke reciprocating engine, comprises a cylinder block 1 containing the cylinders, a cylinder head placed and fixed on the top of the cylinder block 1, a crankcase and oil pan fixed to the bottom of the cylinder block 1, and a front cover (timing chain cover or chain case) 2 attached to the front side of the cylinder block 1, cylinder head and crankcase. A cylinder head cover is attached to the cylinder head from above.

When facing the front cover 2 of the internal combustion engine body, the cooling water pump is disposed in the vertical middle of the front cover 2, and in a position toward the left on the intake side. A pulley 32 is fixed to each of the crankshaft and the rotating shaft 3 of the cooling water pump, which protrude forward from the front cover 2, and a belt 4 is wound around the pulleys 32 to form a transmission mechanism that allows engine torque to be transmitted from the crankshaft to the rotating shaft 3.

The basic structure of the cooling water pump of this embodiment shown in Figure 1 is almost the same as that of the existing one. This cooling water pump is equipped with a pump housing (body) 5 fixed to the outer surface, i.e., the front surface, of the front cover 2, a roughly bowl-shaped pulley 32 arranged to surround the front end of the pump housing 5, a rotating shaft 3 inserted into the pump housing 5 and having the pulley 32 fixed to its front end and the impeller 31 fixed to its rear end, a seal 52 provided in a portion between the impeller 31 and the bearing 56, a flow-down passage 591 for allowing the cooling water leaking through the portion where the seal 52 is provided to flow down, a leakage water reservoir 8 for storing the cooling water that has flowed down the flow-down passage 591, an outlet 592 for discharging the cooling water overflowing from the leakage water reservoir 8, and a leakage gap 9 that is connected to the leakage water reservoir 8 separately from the outlet 592.

The pulley 32 has a peripheral wall 321 around which the belt 4 is wound, and a front wall 322 that is continuous with the front edge of the peripheral wall 321. A shaft hole is provided in the center of the front wall 322, and the front end of the rotating shaft 3 of the cooling water pump is inserted and fixed into the shaft hole. A through hole 323 is drilled in the front wall 322 of the pulley 32 to reduce weight.

The impeller 31 is positioned in a pump chamber 6 formed between the front cover 2 and the cylinder block 1 of the internal combustion engine body. A cooling water intake port 7 and an exhaust port are connected to this pump chamber 6. The intake port 7 opens rearward along the axial direction of the rotating shaft 3 of the cooling water pump. The exhaust port opens toward the back along a direction perpendicular to the axial direction of the rotating shaft 3, i.e., perpendicular to the plane of the paper in FIG. 1. When the impeller 31 rotates around the axis together with the rotating shaft 3, the cooling water for the internal combustion engine is sucked in through the intake port 7 and exhausted through the exhaust port.

Inside the pump housing 5, there is a hollow chamber 51 connected to the pump chamber 6, and a bearing chamber 53 connected to the hollow chamber 51 and having a smaller inner diameter than the hollow chamber 51. An outer race 54 is fitted into the inner circumference of the bearing chamber 53. The rotating shaft 3 is rotatably supported by a bearing 56 held in the outer race 54.

The seal 52 is installed at the rear end of the bearing chamber 53, close to the pump chamber 6. The seal 52 is typically a so-called mechanical seal, and serves to prevent cooling water from flowing into the bearing chamber 53 from the pump chamber 6 and the hollow chamber 51. A seal ring 55 is also attached to the rear end of the outer race 54 as an auxiliary seal that slides against the rotating shaft 3. A buffer (gap) 57 is opened between the seal ring 55 and the mechanical seal 52, spaced apart along the axial direction of the rotating shaft 3. Cooling water leaking from the pump chamber 6 and the hollow chamber 51 through the seal 52 first flows into this buffer 57.

In addition, a steam vent passage 581 and a leakage water flow down passage 591 communicating with the buffer 57 are drilled in the pump housing 5. The steam vent passage 581 extends upward or forward away from the axis of the rotating shaft 3, and its upper end is connected to a steam diffusion passage 582 formed in the pump housing 5. The steam diffusion passage 582 extends approximately parallel to the axis of the rotating shaft 3 and opens at the front end face of the pump housing 5. The opening is located in the inner space 324 surrounded by the pulley 32, that is, the peripheral wall 321 and the front wall 322 of the pulley 32. The cooling water vapor that has evaporated after leaking through the seal 52 travels from the buffer 57 through the steam vent passage 581 to the steam diffusion passage 582 and is released outside the pump housing 5.

The leakage water flow passage 591 extends downward or rearward away from the axis of the rotating shaft 3, and its lower end is connected to the leakage water reservoir 8 between the pump housing 5 and the front cover 2. The leakage water reservoir 8 is formed by recessing the rearward surface of the flange portion of the pump housing 5, which is one of the mating surfaces between the pump housing 5 and the front cover 2, forward, and recessing the forward surface of the front cover 2, which is the other mating surface, rearward. Liquid cooling water that leaks through the seal 52 flows down from the buffer 57 via the leakage water flow passage 591 and temporarily accumulates in this leakage water reservoir 8.

As shown in Figures 1 and 2, the flange portion of the pump housing 5 facing the leakage water reservoir 8 has a discharge port 592 that penetrates through it. The discharge port 592 communicates with the leakage water reservoir 8, extends approximately parallel to the axial direction of the rotating shaft 3, and opens to the front surface of the flange portion of the pump housing 5. The opening faces the space 324 inside the pulley 32. The height of the position where the discharge port 592 communicates with the leakage water reservoir 8 is higher than the height of the position where the leakage water flow-down passage 591 communicates with the leakage water reservoir 8. When the cooling water that has flowed down into the leakage water reservoir 8 accumulates up to the height of the discharge port 592, the accumulated cooling water is discharged to the outside of the cooling water pump through the discharge port 592.

In addition, the front cover 2 facing the leakage water reservoir 8 is also provided with a secondary discharge port 21 that penetrates it. This secondary discharge port 21 corresponds to the discharge port provided in the conventional cooling water pump shown in FIG. 3. The secondary discharge port 21 communicates with the leakage water reservoir 8, extends approximately parallel to the axial direction of the rotating shaft 3, and opens on the rearward surface of the front cover 2 facing the cylinder block 1. In other words, the opening direction of the discharge port 592 and the opening direction of the secondary discharge port 21 are opposite. In addition, the height of the position where the secondary discharge port 21 communicates with the leakage water reservoir 8 is higher than the height of the position where the leakage water flow down passage 591 communicates with the leakage water reservoir 8, but is lower than the height of the position where the discharge port 592 communicates with the leakage water reservoir 8.

The cooling water pump of this embodiment differs from a conventional cooling water pump in that the above-mentioned forward-opening discharge port 592 is provided and the secondary discharge port 21 is purposely closed. As shown in Figs. 1 and 2, a protrusion 50 is formed on the rear surface of the flange portion of the pump housing 5, protruding rearward toward the portion of the secondary discharge port 21 that communicates with the leakage water reservoir 8. The outer diameter of this protrusion 50 is larger than the inner diameter or opening cross-sectional area of the secondary discharge port 21. When the pump housing 5 is assembled to the front cover 2, the protrusion 50 abuts or comes into close contact with the periphery of the portion of the secondary discharge port 21 that communicates with the leakage water reservoir 8, and substantially blocks communication between the secondary discharge port 21 and the leakage water reservoir 8. However, the secondary discharge port 21 is not completely sealed by the protrusion 50. The cooling water that accumulates in the leak water reservoir 8 is discharged, although only in small amounts, to the outside of the cooling water pump through the gap 9 between the protrusion 50 and the periphery of the secondary discharge port 21.

The flow rate of the cooling water leaking from the gap 9 is significantly less than the flow rate of the cooling water discharged from the normal outlet 592. The cooling water leaking from the gap 9 flows down between the front cover 2 and the cylinder block 1 of the internal combustion engine, where it is not easily noticeable to the user. Moreover, the leaked cooling water quickly vaporizes and evaporates due to the heat emitted from the cylinder block 1.

The cooling water pump of this embodiment comprises a pump housing 5 fixed to the body of an internal combustion engine, a pulley 32 arranged to surround a part of the pump housing 5 and rotated by the crankshaft of the internal combustion engine, a rotating shaft 3 connected to the pulley 32 and rotatably supported in the pump housing 5 via a bearing 56, and having an impeller 31 provided at its end, a seal 52 provided between the impeller 31 and the bearing 56 to prevent the cooling water from flowing from the impeller 31 side to the bearing 56 side, and a front The seal 52 is provided in a portion through which the cooling water leaks out through a flow passage 591, a water leakage reservoir 8 that stores the cooling water that has flowed down the flow passage 591, a discharge port 592 that opens toward the pulley 32 and discharges the cooling water that overflows from the water leakage reservoir 8, and a leakage gap 9 (i.e., a gap between the protrusion 50 and the periphery of the portion of the auxiliary discharge port 21 that connects to the water leakage reservoir 8) that is not completely sealed and allows leakage of the cooling water that has accumulated in the water leakage reservoir 8.

According to this embodiment, most of the cooling water that leaks through the seal 52 and accumulates in the leakage water reservoir 8 is discharged through the outlet 592 facing the inner space 324 of the pulley 32. Furthermore, compared to the structure of a conventional cooling water pump, the difference between the pressure inside the outlet 592 and the pressure inside the diffusion passage 582 is smaller. Therefore, the flow rate of air that flows into the pump housing 5 from the outlet 592, passes near the seal 52, and flows out of the diffusion passage 582 is reduced, and the possibility of foreign matter entering the pump housing 5 along with the air flow is reduced. Therefore, the problem of foreign matter getting caught in the seal 52 and compromising the sealing performance of the seal 52 can be effectively avoided.

Moreover, even if the cooling water freezes in the discharge port 592 during the winter in cold regions, the cooling water accumulated in the leakage reservoir 8 can be gradually discharged to the outside due to the capillary phenomenon that occurs in the leakage gap 9. The secondary discharge port 21 that is connected to the leakage gap 9 faces the cylinder block 1, and the leakage gap 9 and the secondary discharge port 21 are less likely to freeze than the discharge port 592.

The present invention is not limited to the embodiment described above. The specific configuration of each part and the content of the processing can be modified in various ways without departing from the spirit of the present invention.

Reference Signs List 1: Cylinder block 2: Front cover 3: Rotating shaft 31: Impeller 32: Pulley 5: Pump housing 52: Seal 56: Bearing 591: Flow passage 592: Discharge port 8: Leakage water reservoir 9: Leakage gap

Claims (2)

A pump housing fixed to a body of the internal combustion engine;
a pulley arranged to surround a portion of the pump housing and rotated by a crankshaft of an internal combustion engine;
a rotating shaft connected to the pulley and rotatably supported within the pump housing via bearings, the rotating shaft having an impeller at one end thereof;
a seal provided between the impeller and the bearing to prevent cooling water from flowing from the impeller side to the bearing side;
a flow passage for allowing cooling water leaking through the portion where the seal is provided to flow down;
a leakage water reservoir that accumulates the cooling water that has flowed down the flow passage;
a drain port that opens in a direction toward the pulley and drains the cooling water that overflows from the leakage water reservoir;
a leakage gap that is not completely sealed and communicates with the leakage reservoir portion and allows leakage of cooling water accumulated in the leakage reservoir portion, the leakage gap being separate from the discharge port;
A structure of a cooling water pump for an internal combustion engine, in which the leakage gap is a gap between a secondary discharge port that communicates with the leakage reservoir and opens in a direction toward the main body of the internal combustion engine, and a protrusion that protrudes toward the secondary discharge port and abuts or is in close contact with the periphery of the point where the secondary discharge port communicates with the leakage reservoir, thereby substantially blocking communication between the secondary discharge port and the leakage reservoir. 2. A cooling water pump structure for an internal combustion engine as described in claim 1, wherein the height of the position where the secondary discharge port is connected to the leakage water reservoir is higher than the height of the position of the lower end of the downflow passage where the downflow passage is connected to the leakage water reservoir, but lower than the height of the position where the discharge port is connected to the leakage water reservoir.

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