JPH10103289A - Water pump and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To omit the machining of an inside diameter face of a boss part of a housing and the shrinkage fitting and press-fitting works by connecting an outer cylinder of a bearing with the boss part of the housing by using an insert. SOLUTION: A shaft part assembly body A is integrally constituted in a boss part 2a of a housing 2 by using an insert. Here, the shaft part assembly body A is set in split molds 18a, 18b which have cavities 12a, 12b which form the housing 2, and a constituent material of the housing 2 which is in a melted condition, for example, aluminum alloy, is poured into the split molds 18a, 18b for molding. Consequently, an outer cylinder of the shaft part assembly body A is firmly connected with the boss part 2a of the housing part 2. In particular, since a plurality (two) of grooves 17 are provided on an outer peripheral face of the outer cylinder 9, the outer cylinder 9 is firmly connected with the boss part 2a of the housing 2 in the axial direction (direction of pulling out). As a result, it is possible to omit the mechanical machining for fitting bearing on an inside diameter face of the housing part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water pump in which a housing supports a bearing for supporting a rotating shaft having an impeller fixed to the tip, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a conventional water pump of this type, a bearing for supporting a rotating shaft and a housing for supporting the rotating shaft are separately formed, and both are integrated by shrink fitting. Also, grease is filled in the bearing space as lubricating oil.

[0003]

In the above-mentioned conventional configuration,
In addition to the bearing, it is necessary to make holes in the boss of the housing to fit this bearing, which increases the number of machining steps, and furthermore, these processing must be accurate. Therefore, many manufacturing steps are required. In addition, the bearing and the housing must be connected sufficiently firmly in the pulling-out direction and the rotating direction. However, a reliable connecting means using a simple method instead of the current shrink fit, crimping or the like is desired.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and eliminates the need for machining of a fitting portion of a housing boss with a bearing, thereby reducing the number of machining steps. Also, the resistance in the pull-out direction can be increased,
Further, it is an object of the present invention to provide a durable water pump and a method for manufacturing the same. The water pump supports an intermediate portion of a rotating shaft with a bearing fitted to a boss portion of a housing, and In a water pump in which a rotating body is fixed to a portion protruding outside the housing from a bearing, and a seal member such as a mechanical seal and an impeller are fixed to a portion protruding into the spiral chamber of the housing, the outer cylinder of the bearing is connected to a boss of the housing. It is configured to be connected by an insert. In the water pump having this configuration, the outer cylinder of the bearing and the boss of the housing are connected by the insert, so that the inner surface processing of the boss of the housing and the shrink-fitting work are omitted.

The rotary shaft is hollow, and the hollow portion and the bearing chamber are communicated with each other. The hollow portion and the bearing chamber are filled with lubricating oil, and the end of the rotary shaft protruding outside the housing. The lubricating oil supplied to the bearing chamber of the bearing of the rotary shaft is also filled in the hollow portion of the rotary shaft. , The filling amount increases. Lubricant is replenished from the stopper to the hollow part as needed.

In the method of manufacturing the water pump, a shaft assembly is constituted by a rotating shaft and a bearing fitted to the rotating shaft, and the shaft assembly is installed in a mold apparatus for molding a housing. Then, the outer cylinder of the bearing of the shaft assembly is inserted into the boss of the housing to form the housing.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a water pump according to the present invention. In the figure, reference numeral 1 denotes a rotating shaft, and an intermediate portion of the rotating shaft 1 is supported by a bearing 3 fitted to a boss 2a of a housing 2. A mechanical seal 5 and an impeller 6 are fitted to an inner end projecting from the bearing 3 to the inside of the housing 2 on the side of the spiral chamber 4, and an outer end projecting outside the housing 2 from the bearing 3. The boss member 7 of the pulley is fitted. Numeral 8 denotes a vortex chamber 4 which is a closed lid.

The rotating shaft 1 and the bearing 3 are pre-assembled as a shaft assembly A as shown in FIG. 2, and the shaft assembly A is provided outside the rotating shaft 1 and the bearing 3. A cylinder 9, a ball 10 interposed therebetween, and sealing members 11a, 1 closing both sides in the axial direction.
1b. The plurality of balls 10 are fitted in an inner race 12 provided annularly on the outer periphery of the rotating shaft 1 and an outer race 13 provided annularly on the inner periphery of the outer cylinder 9, and a plurality of the balls 10 are arranged in the circumferential direction. In two rows.
The inner race may be formed of a separate annular member.

The rotary shaft 1 is hollow from its outer end to the fitting portion with the bearing 3, and this hollow portion 14 rotates in the bearing chamber 3 a closed by the seal members 11 a and 11 b of the bearing 3. The connection is made through a communication hole 15 provided in the shaft 1. The open end of the hollow portion 14 is closed by a plug 16 after injecting grease into the hollow portion 14. The stopper 16 is made detachable, or grease is supplied to the stopper 16 using a grease nipple. Further, as shown by a chain line in FIG. 1, the rotary shaft 1 may be closed by a boss member 7 a fitted to the outer end thereof. An annular groove 17 is provided on the outer periphery of the outer cylinder 9 of the bearing 3. The rotating shaft 1 may be constituted by using a steel pipe as a constituent material thereof and squeezing the steel pipe from the outside in the diametrical direction to form a solid portion, and leave the tubular portion as the hollow portion 14.

The shaft assembly A is a housing 2
The boss portion 2a is integrally formed by an insert. FIG. 3 shows the casting means.
The shaft assembly A is set in the split molds 18a and 18b having the cavities 12a and 12b for molding
Then, the split molds 18a and 18b are clamped, and a constituent material of the housing 2 in a molten state, for example, an aluminum alloy is poured into the cavities 12a and 12b and molded. At this time, either normal casting under normal pressure or pressurized die casting may be used. At this time, the outer cylinder 9 of the shaft assembly assembly A and the boss 2 of the housing 2
a is firmly bound. In particular, since a plurality of (two) grooves 17 are provided on the outer peripheral surface of the outer cylinder 9, the outer cylinder 9 and the boss portion 2 a of the housing 2 are aligned in the axial direction (pull-out direction).
Is firmly bound to It should be noted that this is not limited to the groove, but may simply have irregularities.

The constituent material of the housing 2 is not particularly limited as long as it has a predetermined strength and can be molded. Incidentally, as this constituent material, other than the aluminum alloy, a non-ferrous lightweight alloy such as a magnesium alloy or a metal material such as cast iron is used. In addition, a synthetic resin may be used. Examples of the synthetic resin include a thermosetting resin such as a phenol resin, an amino resin, and an epoxy resin; a thermoplastic resin such as a polyamide resin, a polyacetal resin, and a fluororesin; and a high strength (containing glass fiber), heat resistance, and heat resistance. Engineering plastics with excellent chemical properties are available.

After the above-mentioned molding, the housing 2 is taken out of the mold and machined if necessary. At this time, since the processing of the housing 2 is performed with reference to the shaft assembly A, the overall finishing accuracy can be improved.
For example, since the inner peripheral surface of the spiral chamber 4 of the housing 2 is inserted with reference to the shaft assembly body A, the inner peripheral surface of the spiral chamber 4 is accurately molded, and is formed between the inner periphery of the spiral chamber 4 and the outer periphery of the impeller 6. The chip clearance, which is a gap, is narrowed despite being unprocessed.

After processing the housing 2, the mechanical seal 5 and the impeller 6 are attached to the rotating shaft 1 of the shaft assembly A.
And the boss member 7 of the pulley is fitted. At this time, before the mechanical seal 5 is fitted, a water draining hole 19 is formed from the outside of the housing 2 toward the inside of the mechanical seal fitting portion, and chips from the water draining hole 19 are removed to clean the mechanical seal. 5 is press-fitted. At the time of this assembling, grease is press-fitted into the hollow portion 14 of the rotary shaft 1 through the communication hole 15 until it is press-fitted into the bearing chamber 3a, and closed with the stopper 16. Further, the cover 8 is fixed to the housing 2 to complete the assembly.

In the above configuration, a water draining hole 19 provided in advance in the outer cylinder 9 of the bearing 3 so as to communicate with the outside of the boss portion 2a of the housing 2 is formed in advance. A rod-shaped or tubular plug is attached to 19,
It may be inserted so as to extend from the outer cylinder 9 to the outside of the boss 2a.

When the housing is made of a synthetic resin or the like whose melting temperature during molding is 200 ° C. or less, a lubricating oil used for the rotating shaft may be made of a heat-resistant base oil such as lithium grease or sodium grease. Is used, the rotating shaft is composed of solid, before the insert,
These greases may be filled in the bearing chamber of the bearing 3. However, when grease having a risk of thermal deterioration is used, one of the seal members 11a and 11b is removed at the time of insertion, grease is injected into the bearing chamber after the housing is formed, and the removed seal member is fitted. Can be sealed.

In the above embodiment, the mechanical seal 5
Is a shaft assembly A after the housing 2 is inserted.
However, if the rubber portion of the mechanical seal 5 can withstand the heat when the housing 2 is inserted, it may be assembled before the insert and then inserted. In this case, drain hole 1
9 needs to be opened before the insert and before fitting of the mechanical seal 5 as described above. Before the insert, this is closed with a plug, and after the insert molding, the plug is removed or the plug is removed. The steel pipe used for the above is fixed.

The first conventional example in which the water pump in the embodiment using the aluminum alloy as the constituent material of the housing 2 of the present invention having the above-described structure, the fitting between the bearing and the housing is press-fitted, FIG. 4 shows the result of comparing the force of the outer cylinder 9 with respect to the shaft portion 2a of the housing 2 to the second conventional example in which press fitting and caulking at the end of the outer cylinder are combined. In the figure, a shows an embodiment of the present invention, and b
Indicates the first conventional example, and c indicates the second conventional example. In the embodiment of the present invention, the resistance in the pull-out direction is much higher.

Further, the rotating shaft 1 is made hollow, and the bearing 3
The water pump according to the embodiment of the present invention in which the grease in the bearing chamber 3a is press-fitted, and the bearing chamber 3a of the bearing 3 is filled with grease in advance at the time of assembling the bearing 3 without making the rotary shaft 1 hollow. Each of the conventional water pumps has a rotational speed of 7200 r.p.m. p. As a result of comparing the temperature rise of the bearing portion when rotating at m, the results are as shown in FIG. In the figure, a shows an example of the present invention, and b shows a conventional example. This is presumably because the heat radiating area was increased by hollowing the rotating shaft 1 and a large amount of grease in the hollow portion 14 promoted heat conduction and prevented an excessive rise in temperature.

In addition, as a result of examining the starting torque of the above comparative body, the result is as shown in FIG. 6. The rotating shaft 1 is made hollow, and the grease is injected into this.
Was smaller than b in the conventional example. This is probably due to the fact that sufficient lubrication results were obtained with a large amount of grease.

Further, in the above-mentioned comparative body, both
00r. p. water temperature 90 ° C
(± 3 ° C.), the results are as shown in FIG. 7. The results of the water pump according to the present invention using the grease-filled hollow rotary shaft are a for 600 hr and 4 for conventional b.
It has much higher durability than 50Hr. This is probably because a large amount of grease could be supplied into the bearing.

[0021]

According to the present invention, since the outer cylinder of the bearing of the water pump is connected to the boss of the housing by the insert, machining for bearing fitting on the inner diameter surface of the boss of the housing can be omitted. Thus, machining can be reduced and caulking is not required, and a heating device conventionally required for shrink fitting is not required. Furthermore, since the bearing is not pressed into the conventional housing,
Damage to the bearing balls due to press fitting can be completely eliminated. Further, the connection between the outer cylinder of the bearing and the housing is strengthened, and the resistance in the pull-out direction can be extremely increased as compared with the conventional means such as shrink fit and press-fitting, thereby improving reliability. it can. Further, since the machined portion of the other part of the housing can be machined based on the bearing already integrated with the housing, the overall machining accuracy can be improved.

In this water pump, the rotary shaft supported by the bearing is hollow, the hollow portion is communicated with the bearing chamber, and the hollow portion and the bearing chamber are filled with lubricating oil. As a result, the amount of lubricating oil filled in the bearing is increased and cooling heat transfer is improved, and the rise in temperature of the bearing part is suppressed by the heat dissipation effect due to the hollow rotating shaft. Was completed. In addition, by increasing the amount of the lubricating oil, the starting torque of the rotating shaft was reduced and the high-speed durability was significantly improved.

Further, according to the method of manufacturing a water pump, a shaft assembly is constituted by a rotating shaft and a bearing fitted to the rotating shaft, and the shaft assembly is installed in a mold apparatus for molding a housing. By inserting the boss of the housing into the outer cylinder of the bearing, the shaft assembly is insert-coupled to the boss of the housing at the same time as the insert of the housing. Also, the number of manufacturing steps can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a water pump to which the present invention is applied.

FIG. 2 is a partially broken cross-sectional view showing a shaft assembly.

FIG. 3 is a cross-sectional view showing a state where the shaft assembly is installed in a housing molding die.

FIG. 4 is a diagram showing a comparison of a pull-out force.

FIG. 5 is a diagram showing a comparison of a temperature rise of a bearing unit.

FIG. 6 is a diagram showing a comparison of starting torques.

FIG. 7 is a diagram showing a comparison of endurance times.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating shaft, 2 ... Housing, 2a ... Boss part, 3 ... Bearing, 3a ... Bearing chamber, 4 ... Spiral chamber, 5 ... Mechanical seal, 6 ... Impeller, 7, 7a ... Boss member, 8 ... Lid,
9: outer cylinder, 10: ball, 11a, 11b: seal member, 12: inner race, 13: outer race, 14:
Hollow part, 15 communication hole, 16 plug, 17 annular groove, 18
a, 18b: split mold, 19: drain hole, A: shaft assembly.

Claims (3)

[Claims] An intermediate portion of a rotating shaft is supported by a bearing fitted to a boss portion of a housing, and a rotating body is fixed to a portion of the rotating shaft protruding outside the housing. A water pump in which a seal member such as a mechanical seal and an impeller are fixed to a protruding portion of the water pump, wherein an outer cylinder of the bearing is connected to a boss portion of a housing by an insert. 2. The rotating shaft is hollow, and the hollow portion and the bearing chamber are communicated with each other. The hollow portion and the bearing chamber are filled with lubricating oil, and the end of the rotating shaft protruding outside the housing. 2. The water pump according to claim 1, wherein a plug body capable of replenishing lubricating oil is provided in the hollow portion of the rotating shaft. 3. A shaft assembly comprising a rotating shaft and a bearing fitted to the rotating shaft, the shaft assembly is installed in a mold apparatus for molding a housing, and the shaft assembly is provided. A method for manufacturing a water pump, wherein the outer cylinder of the bearing is inserted into a boss of the housing to form the housing.