Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Turbine regenerative pump
Reexamination Certificate
2000-01-28
2001-09-04
Verdier, Christopher (Department: 3745)
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Turbine regenerative pump
C415S169100
Reexamination Certificate
active
06283704
ABSTRACT:
TECHNICAL FIELD
This invention relates to a circumferential flow liquid pump and, more particularly, to a circumferential flow liquid pump for use in a vehicular internal combustion engine as a fuel pump for pumping a liquid fuel such as gasoline from a fuel tank.
BACKGROUND ART
FIG. 7
is a longitudinal sectional view showing a conventional circumferential flow liquid pump disclosed in Japanese Patent Publication No. 7-3239, for example.
FIG. 8
is an enlarged sectional view taken along line VII—VII of FIG.
7
.
FIG. 9
is an enlarged sectional view taken along line IX—IX of FIG.
8
.
In the figures,
1
designates an assembly of a pump casing, the assembly being constituted with the pump casing main body
2
and the cover
3
. Within the pump casing assembly
1
, an impeller
4
having vane portion
5
at its outer circumferential edge is disposed, the impeller
4
being supported by a central shaft
6
so that it is rotatable about its central axis relative to the pump casing assembly
1
.
The pump casing assembly
1
, as shown in
FIG. 8
, defines a pump flow path
7
of an annular band shape extending along the outer circumferential edge of the impeller
4
and a suction port
8
and a discharge port
9
opening to the opposite end portions of the pump flow path
7
, the pump casing assembly
1
also accommodating the vane portion
5
of the impeller
4
within the pump flow path
7
. Describing the further details of the pump casing assembly
1
, as shown in
FIG. 9
, an air vent passage
11
opening from the bottom portion
10
of the pump flow path
7
and extending radially with a step therebetween is provided in the vicinity of the impeller
4
of the inner circumferential portion of the pump flow path
7
of the cover
3
, and a through hole
12
having a sufficiently larger cross sectional area as compared to that of the air vent passage
11
for communicating the air vent passage
11
to the exterior of the pump casing assembly.
The central shaft
6
of the impeller
4
is constructed as the central shaft of the electric motor
15
connected to the circumferential liquid pump and its opposite end portions are rotatably supported by a bearing
17
and a bearing
18
.
19
is an end cover provided with a check valve
22
and the liquid outlet
23
and holding the bracket
24
. The pump casing assembly
1
and the end cover
19
are connected together by a yoke
20
of the electric motor
15
. The yoke
20
accommodates therein a rotor
16
, defines a liquid chamber
21
between the pump casing assembly
1
and the end cover
19
for storing the liquid such as a liquid fuel discharged from the discharge port
9
and has assembled to its inner circumferential portion a permanent magnet
25
serving as a stator. The liquid chamber
21
is communicated with the liquid outlet
23
having the check valve
22
disposed to the end cover
19
, and inserted within the bracket
24
is a power supplying brush
27
brought in a sliding contact with a commutator
26
of the rotor
16
.
Then, the operation of the conventional circumferential flow liquid pump will be described.
Also, within the pump flow path
7
, gas in the form of bubbles due to the evaporation of the fuel generates at the liquid contacting surface of the vane portion
5
and the impeller
4
and tends to flow out into the liquid chamber
21
. If these bubbles of gas flow into the liquid chamber
21
and reaches the internal combustion engine, various troubles can happen. Therefor, the arrangement is such that the gas in the form of the bubbles is discharged out of the pump casing assembly
1
as much as possible by the air vent passage
11
open to the inner circumferential portion of the pump flow path
7
and the vicinity of the impeller
4
and the through hole
12
.
This function will be described in more detail below. During the operation of the pump, the gas in the form of the bubbles of the fuel vapor, which is generated at the contacting surface between the liquid such as the fuel and the vane portion
5
of the impeller
4
within the pump flow path
7
, is collected at the inner circumferential portion of the pump flow path
7
in the vicinity of the impeller
4
due to the centrifugal force and the difference in specific weight from the liquid fuel and flows together with the liquid through the pump flow path
7
clockwise as viewed in
FIG. 8
or in the same direction as the direction of rotation of the impeller
4
.
When the gas bubbles reach about the air vent passage
11
which opens at the inner circumferential portion of the pump flow path
7
in the vicinity of the impeller
4
with a step raised from the bottom portion
10
of the pump flow path
7
and which extends in the direction coinciding with the direction of whirling flow
13
generated by the impeller
4
within the pump flow path
7
, then the gas collected in the vicinity of the impeller
4
due to the static pressure within the pump flow path
7
due to the pumping action and the dynamic pressure due to the whirling flow
13
generated by the impeller
4
within the pump flow path
7
is forced to be introduced into the air vent passage
11
. The introduced gas is discharged out of the pump casing assembly
1
through the through hole
12
having a cross sectional area sufficiently larger than that of the air vent passage
11
.
In the conventional circumferential liquid pump as above described, if the bubbles of the fuel vapor is generated within the pump flow path and accumulated within the pump flow path
7
, the so-called vapor lock may generate, impeding the flow of the liquid fuel and significantly decreasing the pump discharge rate. In view of these problems, the conventional circumferential flow liquid pump is arranged to discharge the bubbles out of the pump casing assembly through the air vent passage
11
open to the inner circumferential portion of the pump flow path
7
and in the vicinity of the impeller
4
as well as the through hole
12
.
With the above structure, the depth (H in
FIG. 9
) of the air vent passage
11
must be made small, and in order not to increase the flow path resistance against the gas flowing through the air vent passage
11
, it is desirable that the length of the air vent passage
11
is as short as possible. However, since the cross section of the through hole
12
is circular and the cross section of the air vent passage
11
is flat, the side wall of the air vent passage
11
for communicating the pump flow path
7
and the through hole
12
together are inevitably long. Therefore, under a bad condition in which a lot of fuel vapor is generated, the gas in the form of bubbles of the fuel vapor may not sufficiently discharged outside of the pump casing assembly
1
, leading to a fear that the generation of the vapor lock cannot completely be prevented.
This invention has been made to solve the above discussed problems and has as its object the provision of an improved circumferential flow liquid pump arranged such that the gas such as the fuel vapor bubbles generated within the pump flow path is ensured to be discharged from the pump flow path to the outside of the pump casing assembly and there is no fear that the vapor lock generates.
According to the present invention, the circumferential flow liquid pump comprises an impeller having a vane portion in an outer circumferential portion thereof, a pump casing assembly rotatably supporting the impeller and defining therein a pump flow path of an arcuate band-like shape extending along an outer circumferential portion of the impeller and an suction port and a discharge port open at the opposite end portions of the pump flow path, and an air vent hole defined in the pump casing assembly which opens at one end thereof in an inner circumferential portion of the pump flow path in the vicinity of the impeller and at a position radially inwardly spaced from the bottom portion of the pump flow path, opens at the other end thereof to the exterior of the pump casing assembly at a position radially inward of the opening at the one end and which has
Mitsubishi Denki & Kabushiki Kaisha
Sughrue Mion Zinn Macpeak & Seas, PLLC
Verdier Christopher
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