Circumferential flow pump
A circumferential flow pump in which the quantity of swelling by alcohol or toluene contained in fuel, is curbed and an impeller thereof is prevented from locking is provided. A circumferential flow pump for feeding into an internal combustion engine, fuel from the fuel tank thereof includes an impeller, made of fiber-reinforced PPS, having a base portion fitted to a motor rotor, a vane portion provided outer-circumferentially on the base portion, and an outer ring portion provided outer-circumferentially on the vane portion; the vane portion is composed of a plurality of vanes arranged radially protruding straightly from the base portion and each vane includes a bend thereon; and furthermore, given that a projected area of the entire vane portion is S1, that of the ring portion, S2, that of the base portion, S3, when the impeller, is projected from a direction along a motor shaft of the motor rotor, the ratio of S3 to S1 is made to fall between 9:1 to 15:1, and the ratio of S2 to S1 is made to fall between 0.10:1 to 0.13:1.
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1. Field of the Invention
The present invention relates to circumferential flow pumps that are housed in the fuel tank of, for example, an automobile, and supply fuel to the internal combustion engine thereof at a predetermined pressure.
2. Description of the Related Art
An impeller mounted on a circumferential flow pump is provided with a base portion that is fitted to a motor rotor, a vane portion that is formed outer-circumferentially on the base portion, and an outer ring portion that is formed outer-circumferentially on the vane portion. In conventional circumferential flow pumps, impellers have being developed for the purpose of raising efficiency or lowering noise. As an impeller of this king, it is known that the vane portion is made thinner, and that fiber-reinforced polyphenylene sulfide(PPS), being excellent in moldability and dimensional stability, is used. It is also known that a bend is formed on each vane (e.g., Japanese Patent Laid-Open No. 2003-336558).
SUMMARY OF THE INVENTIONIn conventional circumferential flow pumps, resin's flow during injection molding tends to be blocked due to bends on the vane portion. When fiber-reinforced PPS is used as the molding resin, the orientation of the fiber, being reinforcing material, tends to be uniform at the bends of the vane portion. During the injection molding, the molding resin is injected through the vane portion into the outer ring portion, in which fiber's orientation tends to be uniform also in the ring under the effect of the vane portion. It is effective to enhance randomness of the fiber-orientation or enhance crystallinity of the fiber-reinforced PPS, in order to curb its swelling by alcohol and toluene that are contained in fuel. In the base portion, dwelling operation during the injection molding can enhance the crystallinity of the PPS, but in the vane portion and the ring portion, the dwelling pressure cannot be transferred thereto to such an extent that the crystallinity thereof can be enhanced. Consequently, due to the low randomness of fiber-orientation in the vane portion and the ring portion, the quantity of swelling thereof by alcohol and toluene becomes large compared with that in the base portion. When the impeller swells so much as to contact with a pump-housing, there arises a problem in that the impeller locks.
To curb the quantity of the swelling, it might be an alternative way to use a thermosetting resin, such as a phenolic resin, however, operations in later processes, such as deburring, become necessary.
The present invention is made in order to solve above-described problems and provide a circumferential flow pump, in which the impeller mounted on the circumferential flow pump is made of fiber-reinforced PPS, so as to curb the quantity of swelling by alcohol and toluene contained in the fuel, so that the impeller is prevented from locking.
In the present invention, a circumferential flow pump that feeds into an internal combustion engine, fuel from a fuel tank, includes:
a disc-shaped impeller fitted to a motor rotor, and
a pump-housing for housing the impeller; wherein the impeller is made of fiber-reinforced PPS and composed of a base portion fitted to a motor rotor,
a vane portion provided outer-circumferentially on the base portion, and
an outer ring portion provided outer-circumferentially on the vane portion, and the vane portion is composed of a plurality of vanes arranged radially protruding straightly from the base portion and each vane includes a bend; and furthermore, given that a projected area of the entire vane portion is S1, that of the ring portion, S2, that of the base portion, S3, when the impeller is projected from a direction along the shaft of the motor rotor, the ratio of S3 to S1 is made to fall between 9:1 and 15:1, and the ratio of S2 to S1 is made to fall between 0.10:1 and 0.13:1.
According to the present invention, because a circumferential flow pump having an impeller made of fiber-reinforced PPS is provided, the quantity of swelling by alcohol and toluene contained in the fuel can be curbed, so that a circumferential flow pump can be provided in which the impeller is prevented from locking.
When the motor rotor 3 is driven with the pump 1 being immersed in the fuel tank, the fuel is led from the inlet 5b into the pump room by the rotation of the impeller 2. Through an outlet 6e of a pump room and the motor room, the fuel is sent from a spout 4 to the internal combustion engine. In addition, in order to prevent the rotation of the impeller 2 from being hampered, a clearance 7a is provided between the impeller 2 and the pump-housing 7.
Although the shape of the impeller 2 varies due to specifications of the circumferential flow pump, it is assumed in the following description that the diameter of the impeller is 20-30 mm and its thickness is 3-4 mm. The impeller 2 is formed by injection molding with fiber-reinforced PPS in which a reinforcing material, such as glass fiber, is used. In the injection molding, the glass-fiber-reinforced PPS is in a molten state of high temperature, and the PPS is injected into a mold portion for the base portion 2a, and passing through that for the vane portion 2b, then is injected into that for the outer ring portion 2c.
In this aspect of the present invention, given that a projected area of the entire vane portion 2b is S1, that of the ring portion 2c, S2, that of the base portion 2a, S3, when the impeller 2 is projected from a direction along a motor shaft of the motor rotor 3, the ratio of S3 to S1 is made to fall between 9:1 and 15:1. And the ratio of S2 to S1 is made to fall between 0.10:1 and 0.13:1.
When molding the above-described impeller 2, the glass-fiber-reinforced PPS injected into the mold portion for the base portion 2a, fills uniformly the portion and then passes, with a constant high pressure, through that for the vane portion 2b, which can keep, even at the bends, the randomness of fiber orientation relatively high. Then, pressure is removed from the fiber; thereby, the PPS flowing into the mold portion for the outer ring-portion 2c, from that for the vane portion 2b also obtains a relatively high randomness of the fiber orientation.
Consequently, because the swelling quantities of the vane portion 2b and outer ring portion 2c of the impeller 2, by alcohol and toluene contained in fuel, can be curbed, in a circumferential flow pump 1 provided with an impeller according to Embodiment, the impeller 2 can be prevented from locking without widening the clearance 7a between the impeller 2 and the pump-housing 7.
Claims
1. A circumferential flow pump that feeds into an internal combustion engine, fuel from a fuel tank, including:
- a disc-shaped impeller fitted to a motor rotor, and
- a pump-housing for housing the impeller; characterized in that the impeller is made of fiber-reinforced polyphenylene sulfide and comprises:
- a base portion fitted to the motor rotor,
- a vane portion provided outer-circumferentially on the base portion, and
- an outer ring portion provided outer-circumferentially on the vane portion; and the vane portion comprises a plurality of vanes arranged radially protruding straightly from the base portion and each vane includes a bend; and furthermore, given that a projected area of the entire vane portion is S1, that of the ring portion, S2, that of the base portion, S3, when the impeller is projected from a direction along a motor shaft of the motor rotor, the ratio of S3 to S1 is made to fall between 9:1 and 15:1, the ratio of S2 to S1 is made to fall between 0.10:1 and 0.13:1.
Type: Application
Filed: Nov 30, 2006
Publication Date: Aug 9, 2007
Applicant: MITSUBISHI ELECTRIC CORPORATION (Chiyoda-Ku)
Inventors: Masahiro Koyama (Chiyoda-ku), Seizou Inoue (Chiyoda-ku)
Application Number: 11/606,143
International Classification: F04D 5/00 (20060101);