JPS6257836B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water pump that supplies cooling water to an outboard engine.

Conventionally, a water pump is placed inside the casing of an outboard motor, and this water pump pumps up surrounding water and supplies it around the outboard engine to cool the engine. ing. On the other hand, exhaust gas from the outboard motor passes through the casing and is discharged into the seawater. Therefore, when the water pump pumps up surrounding water, exhaust gas or air may be mixed into the water, which may reduce the discharge capacity of the water pump. Particularly when the boat is moving backwards, the exhaust gas released into the surrounding water will cover the water intake port of the water pump, which may have a greater adverse effect on the water pump than when the boat is moving forward.

The present invention has been made in view of the above-mentioned conventional water pumps for outboard motors, and is designed to provide an outboard motor in which the discharge capacity of the water pump does not decrease even if exhaust gas etc. are mixed into the water pumped by the water pump. The purpose is to propose water pumps. In order to achieve this object, the present invention forms a gas vent hole on the upper surface of the housing of the water pump, and even if the exhaust air, etc. gets mixed into the seawater being pumped, the exhaust gas, etc. is released outside the water pump through the gas vent hole. Since the water is discharged, the discharge capacity of the water pump will not be reduced.

Preferred embodiments of the water pump for an outboard motor according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the lower end of a casing 10 of an outboard motor, and an engine (not shown in FIG. 1) is mounted on the upper part of the casing 10. As shown in FIG. An exhaust passage 12 extending vertically in FIG. 1 is formed inside the casing 10, and an exhaust pipe 14 extends through the exhaust passage 12 through which exhaust gas from the engine combustion chamber passes. As shown in FIG. 1, the exhaust passage 12 is bent at 90 degrees at its lower part 16 and communicates with the interior of the propeller boss 20. Therefore, the exhaust gas from the engine combustion chamber passes through the exhaust pipe 14, further through the exhaust passage 12 and the lower part 16 of the exhaust passage 12, and is discharged from the end face of the propeller boss 20 into the water.

An enlarged part 22 is formed in the exhaust passage 12, and a water pump 24 is installed in this enlarged part 22. This water pump 24 uses a drive shaft 26 as its power shaft. As shown in FIG. 1, the drive shaft 26 is connected to the propeller shaft 3 via a gear portion 28 at its lower end.
0 and transmits rotational force from the engine to the propeller boss 20. Note that a suction channel 32 is formed below the water pump 24, and this suction channel 32 is provided with a water intake port 34 in which a large number of pores are formed. This water inlet 34 serves as a filter to remove algae floating in the water.
This prevents dirt and the like from entering the water pump 24. Although not shown in FIG. 1, the suction channel 32 communicates with the suction port of the water pump 24.
On the other hand, a discharge port (not shown in FIG. 1) of the water pump 24 is communicated with a water pipe 36, which extends upward inside the casing 10 and supplies cooling water to the engine (not shown in FIG. 1). to cool down.

FIG. 2 is a cross-sectional view showing the structure of the water pump 24 shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along the upper line in FIG. A housing body 38 of the water pump 24 is made of synthetic resin, and an insert 42 as an inner wall member constituting the housing of the water pump 24 is disposed in a chamber 40 formed below the housing body 38. insert 42
is formed into a substantially cylindrical shape, and its lower end surface is connected to the bottom plate 44.
is fixed to the casing 1 by this bottom plate 44.
attached to 0. This bottom plate 44 has a third
A water pump inlet 46, shown in the figures, is formed therein, and a water pump outlet 48 is formed in the side surface of the insert 42. The suction port 46 is in communication with the suction channel 32 and draws water into the insert 42 through the suction channel 32 . Note that the center of the cylindrical insert 42 is arranged slightly eccentrically from the rotation center of the drive shaft 26. The housing of the water pump 24 includes a housing body 38, an insert 42 as an inner wall member of the housing, and a bottom plate 44.

An impeller 50 affixed to the drive shaft 26 is disposed within the insert 42 . The impeller 50 is made of rubber and is elastically deformable, and the impeller 50 has vanes 51 arranged at predetermined intervals as shown in FIG.
is formed. The vanes 51 of the impeller 50 are in contact with the inner periphery of the insert 42 as shown in FIG. 3, and the inner periphery of the insert 42 sandwiched between the two adjacent vanes 51, 51 A space defined by a part of the pump chamber 53 becomes the pump chamber 53. The impeller 50 is fixed to the drive shaft 26 as described above, so that the center of rotation of the impeller 50 is eccentric to the center of the insert 42. As a result, the volume of the pump chamber 53 defined by the vanes of the impeller 50 changes as the impeller 50 rotates. That is, at the position where the suction port 46 opens, the volume of the pump chamber 53 expands and sucks in surrounding water from the suction port 46, and at the position facing the discharge port 48, the volume decreases. Internal pressure increases and discharge port 4
Discharge this water towards 8.

A discharge passage 52 communicating with the discharge port 48 of the insert 42 is formed in the housing body 38, and a boss hole 54 is formed above the discharge passage 52.
is formed. This boss hole 54 is the discharge path 52
The boss hole 54 communicates with the water pipe 36 through a communication hole 56, and the end of the water pipe 36 is supported in the boss hole 54 via a rubber seal 58. Therefore, the water discharged into the discharge passage 52 is sent to the water pipe 36 through the communication hole 56, and is further supplied to the engine through the water pipe 36, thereby functioning as cooling water for the engine.

An insert 42 is provided inside the housing body 38.
A boss hole 59 is formed above the boss hole 5.
In order from the bottom, 9 is formed with a negative pressure chamber 60, a small diameter part 62 as a throttle, and an enlarged diameter part 64. The boss hole 54 of the housing body 38 and the enlarged diameter portion 64 above the small diameter portion 62 communicate with each other via a communication hole 65. Therefore, when water in the boss hole 54 is supplied into the enlarged diameter part 64 through the communication passage 65 by pump operation, a small diameter part 6 is formed between the enlarged diameter part 64 and the negative pressure chamber 60.
2 is formed, the inside of the negative pressure chamber 60 becomes negative pressure. The function of this negative pressure chamber 60 will be described later.

A gas vent hole 66 is formed in the upper surface of the insert 42, and the position of the gas vent hole 66 is shown in FIG. That is, the leading vane 51A of the vanes 51 of the impeller 50 is connected to the discharge port 4.
8, the trailing vane 51B adjacent to the leading vane 51A is still in contact with the inner circumferential surface of the insert 42, and when the vanes 51A, 51B are in this position, the gas vent hole 66 is adjacent to the leading vane 51A. A part of the hole opens into a pump chamber 53A defined by vanes 51A and 51B. Since the impeller 50 is rotated at high speed by the drive shaft 26, the vanes 51A,
When 51B comes to this position, that is, at the moment when the pump chamber 53A opens, the pressure in the pump chamber 53A still remains, and water with a heavy specific gravity is pushed toward the discharge port 48 by centrifugal force, but the specific gravity The light gas is concentrated near the center of the pump chamber.
Therefore, this collected gas is discharged to the outside from the gas vent hole 66 due to the internal pressure of the pump chamber 53A itself. The gas vent hole 66 communicates with a negative pressure chamber 60 shown in FIG. In order for the gas in the pump chamber 53A defined by the leading vane 51A and the trailing vane 51B to be released to the outside through the gas release hole 66, it is necessary that the internal pressure of the pump chamber 53A be higher than the external pressure. Negative pressure chamber 60 ensures this. That is, as described above, the negative pressure chamber 60 has a small diameter portion 62.
A constant negative pressure is created by the restricting structure of the pump chamber 53A defined by the vanes 51A and 51B. so that it leads to the chamber 60. Furthermore, this negative pressure chamber 60 eliminates the influence of the dynamic pressure of water, and exhaust gas can easily escape from the gas vent hole 66. The gas collected in the negative pressure chamber 60 rises through the gap between the drive shaft 26 and the housing body 38, and is discharged to the outside of the casing 10 at a position not shown in FIG.

As explained above, according to the water pump for an outboard motor according to the present invention, a gas vent hole is formed on the upper surface of the inner wall member of the water pump housing, and the gas vent hole is defined by two adjacent bases. A gas vent hole is formed in the upper surface of the housing to communicate the pump chamber to the outside of the housing, and the gas vent hole faces the discharge port of the leading vane among the two adjacent vanes, and the trailing vane is in contact with the wall surface. Since the leading vane opens near the base, the gas inside the pump chamber can be successfully discharged to the outside of the pump chamber. Furthermore, at the open position of the gas vent hole, gas can be discharged to the outside without reducing the discharge pressure of the pump, so even if gas gets mixed into the pump, the discharge capacity of the pump will not be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of the lower part of the casing of an outboard motor to which an embodiment of the present invention is applied, FIG. 2 is an enlarged sectional view showing the main parts of the embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along the top line in FIG. 2; 24...Water pump, 26...Drive shaft, 38...
Housing main body, 42... Insert as an inner wall member of the housing, 44... Bottom plate constituting the housing, 46... Suction port, 48... Discharge port, 5
0... Impeller, 66... Gas vent, 51A...
... Leading vane, 51B... Trailing vane, 53A...
…pump room.

Claims (1)

[Claims] 1. In a water pump for an outboard motor, a cylindrical housing has a suction port and a discharge port, and an impeller including a plurality of vanes is disposed in the housing with its center of rotation eccentric to the center of the housing. A gas vent hole is formed in the upper surface of the housing to communicate a pump chamber defined by two adjacent vanes to the outside of the housing, and the gas vent hole is connected to a leading vane of the two adjacent vanes. A water pump for an outboard motor, wherein the water pump opens near the base of the leading vane when the vane faces the discharge port and the trailing vane is in contact with a wall surface.