JPH10259789A - Impeller for pump and molding method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an impeller for a pump to eliminate a need to a cutting work after injection-molding and ensure plane precision of a surface and the back and provide a molding method thereof. SOLUTION: An impeller for a pump is formed such that the impeller is formed in the shape of a disc, a shaft hole 12a in the central part of which the rotary shaft of a motor is fitted is formed in a central part 12, a through- hole 12b extending through the two surfaces of a surface and a back (in the direction of plate thickness) is formed in a position in the vicinity of the outside of the shaft hole 12a, a plurality of blade grooves 13a are formed in both the surface and the back of an outer peripheral part 13, and plane parts 14 positioned facing the inner wall of a casing are formed on the inner wall of a casing with a slight gap between the outer peripheral part 13 and the central part 12. In this case, a gate position during injection molding is formed in an annular shape centering around the shaft hole 12a and is set at the central part 12 and the periphery of the through-hole 12b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impeller used for a pump such as a fuel pump for supplying fuel to an engine, and a method for forming the impeller.

[0002]

2. Description of the Related Art Conventionally, as this kind of pump, there is, for example, an on-vehicle fuel pump, and this fuel pump is mainly of an in-tank type disposed in a fuel tank. This in-tank type fuel pump is generally shown in FIG.
8 to FIG.

[0006] That is, reference numeral 1 in FIG. 6 denotes a casing having a substantially cylindrical shape whose both ends are closed. A suction port 1 a through which fuel is sucked is formed at one end of the casing 1, and the other is formed at the other end. Discharge port 1b through which fuel is discharged at the end
Are formed.

In the casing 1, a motor chamber 1e and an impeller chamber 1f are formed via a partition 1j, and a rotor 2 is rotatably disposed in the motor chamber 1e. Has a stator 3 attached.
One end of the rotation shaft 2a of the rotor 2 projects into the impeller chamber 1f, and this projection is formed in the impeller chamber 1f.
It fits in the shaft hole 4a of the impeller 4 disposed therein. A space 1 is provided around the impeller room 1f.
g is substantially C-shaped as shown in FIG. One end 1h of the space 1g is located at a position corresponding to the suction port 1a, and the other end 1i is connected to the motor chamber by a communication hole 1k provided in a partition 1j between the motor chamber 1e and the impeller chamber 1f. 1e.

The impeller 4 is made of a synthetic resin made of a thermosetting resin such as phenol resin and is formed in a disk shape. The shaft hole 4a is formed in the center, and the front and rear surfaces are formed in the outer periphery. In this example, a plurality of blade grooves 4b on the front side and a plurality of blade grooves 4b on the back side are formed so as to be out of phase by 1/2 pitch. In the vicinity of the shaft hole 4a, a total of four through holes 4c penetrating to the front and back sides are formed on the same circumference.

The through hole 4c faces the pools 1m and 1n of the impeller chamber 1f, while the blade groove 4b is
It faces the space 1g. The portion of the impeller 4 between the blade groove 4b and the through hole 4c is set to a small gap C with the inner wall surface of the impeller chamber 1f (see FIG. 7).

In the fuel pump having such a configuration, when the impeller 4 rotates with the rotation of the rotor 2 of the motor, the fuel in the impeller chamber 1f is pressurized, and the motor chamber 1f is pressurized.
e. Therefore, on the one hand, the fuel in a fuel tank (not shown) is sucked into the impeller chamber 1f from the suction port 1a, and on the other hand, the fuel is supplied from the motor chamber 1e to the carburetor or the fuel injection device via the outlet 1b. It will be.

During this operation, a part of the fuel in the motor chamber 1e returns to one reservoir 1m of the impeller chamber 1f through a small gap between the rotating shaft 2a and the bearing 5, and the impeller Due to the rotation of, the fluid flows toward the flow channel groove 1g. At this time, the fuel flows into the flow channel 1g through the gap C on the left side of the impeller 4 shown in FIG. 7, and flows into the reservoir 1n on the opposite side via the communication hole 1k provided in the impeller 4. 7 through the gap C on the right side in FIG. 7 of the impeller 4 toward the space 1g. As a result, a film of the fuel is formed in the gap C between the front and back sides of the impeller 4 and the inner wall of the impeller chamber 1f, and the flow of the fuel occurs. Therefore, the impeller 4 can rotate smoothly, Noise and low vibration are obtained, and durability is improved.

[0009]

However, in such a conventional apparatus, the minute gap C between the impeller 4 and the inner wall of the impeller chamber 1f is required to reduce the size of the fuel pump and to stably supply the fuel. It must be kept as narrow and uniform as possible. Therefore, strict planar accuracy is required for the front and back surfaces of the impeller 4. For this reason, conventionally, after the impeller 4 is injection-molded, the front and rear surfaces including the space between the blade grooves 4b on the outer peripheral portion are finished by cutting. The reason is that, in the conventional injection molding, the position of the gate is changed as shown in FIG.
Is often provided at the position indicated by the X mark, and gate marks remain, and it is difficult to achieve a flatness because it is difficult to finish a uniform thickness between gate positions due to the effect of shrinkage. is there.

Further, when a thermosetting resin such as a phenol resin is used, there is a problem that the molding cycle becomes long, and it is difficult to improve the productivity. Accordingly, an object of the present invention is to provide an impeller for a pump, which does not require cutting after injection molding, can secure the flatness of the front and back surfaces, and can also improve the productivity, and a method of forming the impeller.

[0011]

In order to attain the object, the invention according to claim 1 has a disk shape, and has a shaft hole into which a rotation shaft of a motor is fitted at the center at the center. A through-hole penetrating the front and back surfaces is formed at a position near the outside of the shaft hole, a plurality of blade grooves are formed on both the front and back surfaces at the outer periphery, and an inner wall of the casing is provided between the outer periphery and the central portion. In a synthetic resin pump impeller in which flat portions opposed to each other with a small gap are formed on the front and back sides, the gate position during injection molding has a ring shape centering on the shaft hole, and the central portion has And a pump impeller set around the through hole.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the liquid crystal display device is formed of a liquid crystal polymer resin.

[0013] The invention according to claim 3 is the invention according to claims 1 and 2.
The method for molding a pump impeller according to any one of the above, wherein a molten resin is injected into a cavity of a mold from a ring-shaped gate corresponding to the gate position, and after being cured, is released from the mold for a pump. A method of forming an impeller is provided.

According to a fourth aspect of the present invention, in addition to the configuration of the third aspect, at the time of the mold release, the pump impeller is released from the mold by pressing substantially the entire flat surface of the pump impeller. It is characterized by making it.

[0015]

Embodiments of the present invention will be described below.

1 to 5 show an embodiment of the present invention.

First, the structure will be described. In the figure, reference numeral 11 denotes an impeller, and this impeller 11 is used for a fuel pump similar to the conventional fuel pump described with reference to FIG. Therefore, in the following description, the same members as those in the conventional example will be described using the same reference numerals.

The impeller 11 of this embodiment is formed in a disk shape by using a thermoplastic resin such as a liquid crystal polymer resin as a synthetic resin.

The impeller 11 has a central portion 12.
Is formed so as to be recessed from other portions, and is formed around a shaft hole 12a into which a rotation shaft 2a of a motor (more precisely, the rotor 2) is fitted. The shaft hole 12a has a substantially D shape. A plurality (four in this case) of through holes 12b penetrating on both front and back surfaces (in the thickness direction) are formed at equal intervals on the same circumference at a position near the outside of the shaft hole 12a.

As shown in FIG. 1, a ring-shaped gate trace 12c is left around the through hole 12b on one side of the central portion 12. This gate mark 12c is the gate position at the time of injection molding.

Further, the outer peripheral portion 13 has a plurality of blade grooves 13a formed on both the front and back surfaces. In this example, each of the blade grooves 13a on the front side and each of the blade grooves 13a on the back side are formed so as to be out of phase with each other by ピ ッ チ pitch.

Further, between the outer peripheral portion 13 and the central portion 12, flat surface portions 14 are formed on the front and back sides facing the inner wall of the impeller chamber 1f with a small gap C as shown in FIG. ing.

Next, a method of forming the impeller 11 will be described.

FIG. 3 shows a molding die for molding the impeller 11. The molding die has a fixed die 17 and a movable die 18. The fixed die 17 is provided with a movable piece 17a movably in the vertical direction.
A first pin 17b forming the shaft hole 12a of the impeller 11 and a second pin 17c forming the through hole 12b are inserted through 7a. The first and second pins 17b and 17c are fixed.

The movable mold 18 has a ring-shaped gate 1 for injecting the molten thermoplastic resin into the cavity 20.
8a is provided so that the movable mold 18 moves upward when the mold is released.

In order to mold the impeller 11 using such a molding die, first, the cavity 2 is closed while the mold is clamped.
The molten resin is injected and filled from the ring-shaped gate 18a into the space 0.

After the molten resin is cured, it is released from the mold. First, from the state shown in FIG.
As shown in FIG. 3B, after the movable die 18 is raised, the movable piece 17a is raised, whereby the molded impeller 11 is released.

By forming the impeller 11 in this manner, the flatness of the flat portion 14 is ensured without cutting.

That is, when the molten resin is injected from the ring-shaped gate 18a, the ring shape gradually flows toward the flat surface portion 14 so as to gradually increase in diameter, and the ring shape changes toward the shaft hole 12a. It flows so as to gradually reduce the diameter. Therefore, when the molten resin flows into the flat portion 14, the influence of the second pin 17c does not occur, and no weld phenomenon occurs in the flat portion 14 after molding. Therefore, since the flatness of the flat portion 14 is ensured in a released state, cutting work is not required.

On the other hand, on the central portion 12 side, a part of the molten resin hits the second pin 17c to change the flow, and after flowing around the second pin 17c, it merges. Therefore,
A weld phenomenon occurs at this confluence position, which affects the flatness of the central portion 12. However, since the flatness of the central portion 12 is not so required, even if the flatness is poor due to this weld phenomenon, the gate mark 12 c
There is no problem even if remains, and there is no need to perform cutting.

FIG. 4 is presented as evidence that the flatness of the flat portion 14 is improved. FIG. 4A shows the degree of undulation on an arbitrary circle of the impeller flat portion 14 of the present invention measured using a roundness meter. FIG.
(B) shows the result of measurement of the undulation of the flat portion 24 of the impeller 21 as shown in FIG.

In the impeller 21 shown in FIG. 5, a total of eight gate marks 22c are provided at equal intervals on a concentric circle around the through hole 22b in the central portion 22. Other configurations are the same as those of the impeller 11 of the present invention.

Although the flatness of the impeller 21 is considerably improved, the impeller 21 shown in FIG. 4B and the undulation amount B1 of the flat portion 14 according to the present invention shown in FIG. Comparing the undulation amount B2 of the flat portion 24, it can be seen that the undulation amount B1 is considerably smaller. This is because the impeller 21 shown in FIG. 5 is formed by injecting molten resin from a plurality of gates, so that a merged portion of the molten resin occurs and a weld phenomenon occurs at the merged portion. Things.

When the impeller 11 is released from the mold, the movable piece 17a presses the central portion 12 and the flat portion 14 of the impeller 11 over the entire surface, so that the flat portion 14 can be prevented from being deformed. That is, at the time of this release, the outer peripheral portion 1
Since a large number of blade grooves 13a are formed in 3, a large force is required when releasing this portion. Therefore,
When the flat portion 14 is pressed at several points, the flat portion 14 is damaged. When only the center portion 12 is pressed, the center portion 12 may be slightly damaged. In the process of transmitting the force to the outer peripheral portion 13, an external force such as bending may be generated on the flat portion 14 and may be deformed. On the other hand, as in the present embodiment, by pressing the substantially entire surface of the flat portion 14 and the central portion 12 of the impeller 11 with the moving piece 17a, such a problem can be prevented and the flatness can be improved. Can be.

Furthermore, if the impeller 11 is formed of a liquid crystal polymer resin, there are further advantages as follows. That is, this liquid crystal polymer resin has high fluidity and is suitable for thin-wall molding, and has a high solidification rate, so that burr does not easily appear and the impeller 11 can be molded in a high cycle.
Furthermore, since the shrinkage ratio during molding is small, molding can be performed with high dimensional accuracy, and in particular, the flatness of the plane portion 14 can be improved.

Although it has the advantages described above, the weld phenomenon is likely to occur due to the high solidification rate. However, as in the present invention, the molten resin is injected from the ring-shaped gate 18a around the through-hole 12b to form the flat portion 14 located outside the gate 18a. Regardless, the weld phenomenon does not occur.

Further, although the central portion 12 of the impeller 11 is formed thinner than the other portions, the flatness of the flat portion 14 will not be adversely affected even if the central portion 12 is formed to have the same thickness as the other portions. However, when formed thin, there is an advantage that the influence of sink marks is small and the shape accuracy of the shaft hole 12a and the like is easily maintained.

In the above embodiment, the impeller 11 provided in the fuel pump has been described. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to an impeller applied to another pump. Further, although the phase of the blade groove 13a is shifted by 1/2 pitch between the front and back surfaces, the present invention can be applied to a case where the phase shift is other than that, or to a case where the phase shift is the same.

[0039]

As described above, according to the invention described in each of the claims, by setting the gate position at the time of injection molding at the center of the impeller and around the through hole, the gate can be moved from the gate. Because the injected molten resin flows so that the ring shape gradually increases in diameter toward the flat surface side,
The welded phenomenon does not occur on the flat part after molding, and the flatness of this flat part can be ensured in a released state. There is no problem because it is not so required. Therefore, unlike the related art, there is no need to perform a cutting process after the injection molding, and the planar accuracy of the front and back surfaces can be secured.

According to the second aspect of the present invention, since the impeller is formed of a liquid crystal polymer resin, it has a high fluidity and can be formed into a thin wall. Further, since the solidification speed is high, burrs are hardly generated, and the impeller is hardly formed. The impeller can be formed in a cycle. Further, since the shrinkage at the time of molding is small, molding can be performed with high dimensional accuracy, and in particular, the flatness of the flat portion can be improved.

According to the fourth aspect of the invention, when the impeller is released from the mold, the flat portion is pressed over the entire surface, thereby preventing the flat portion from being damaged or deformed.

[Brief description of the drawings]

FIG. 1 is a plan view of an impeller according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the impeller according to the embodiment.

FIG. 3 is a sectional view of a molding die according to the embodiment;
(A) is a figure which shows a mold clamping state, (b) is a figure which shows a mold release state.

FIGS. 4A and 4B are graphs showing the amount of undulation in the plane portion of the impeller, wherein FIG. 4A is a diagram showing this embodiment, and FIG.

FIG. 5 is a plan view showing an impeller that has not been disclosed in the already filed application.

FIG. 6 is a sectional view of a fuel pump showing a conventional example.

FIG. 7 is an enlarged cross-sectional view of an impeller arrangement portion of the conventional example.

FIG. 8 is a diagram showing the same conventional example, viewed from line AA of FIG. 7;

[Description of Signs] 1 Casing 2 Rotor 2a Rotary shaft 11 Impeller 12 Center part 12a Shaft hole 12b Through hole 13 Outer part 13a Blade groove 14 Flat part 17 Fixed type 18 Movable type 18a Gate 20 Cavity C Gap

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryoichi Nakata 2-30-1 Namiki, Kawaguchi City, Saitama Prefecture Within Enplus Co., Ltd. (72) Inventor Tsutomu Sasaki 10-6 Minamidaira, Ogawara-machi, Shibata-gun, Miyagi (72) Invention Person Mitsuru Fukuda 56--11

Claims (4)

[Claims] A shaft hole into which a motor shaft is fitted at the center, and a through hole penetrating through the front and back surfaces at a position near the outside of the shaft hole at the center; A plurality of blade grooves are formed on each of the front and back surfaces, and a flat portion facing the inner wall of the casing with a small gap between the outer peripheral portion and the center portion is formed on the front and back surfaces. The pump impeller according to claim 1, wherein the gate position at the time of injection molding has a ring shape centering on the shaft hole, and is set at the center and around the through hole. Impeller. 2. The pump impeller according to claim 1, wherein the impeller is formed of a liquid crystal polymer resin. 3. The molding method of a pump impeller according to claim 1, wherein molten resin is injected into a mold cavity from a ring-shaped gate corresponding to the gate position. A method for forming a pump impeller, comprising releasing the mold after curing to form a pump impeller. 4. The method for forming a pump impeller according to claim 3, wherein, at the time of releasing the mold, the pump impeller is released from the mold by pressing substantially the entire flat surface of the pump impeller. .