Expansible chamber devices – Collapsible chamber wall portion – Wall portion formed of flexible material
Reexamination Certificate
1999-10-29
2002-01-15
Look, Edward K. (Department: 3745)
Expansible chamber devices
Collapsible chamber wall portion
Wall portion formed of flexible material
C417S413100
Reexamination Certificate
active
06338295
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel pump, and particularly to a fuel pump to be installed in a high temperature environment.
BACKGROUND OF THE INVENTION
With a small outboard motor, as shown in
FIG. 4
, a fuel tank
40
is arranged internally of the boat, and a fuel pump
42
is arranged externally of the boat. The fuel pump
42
is generally secured directly to a cylinder head cover
46
of an engine
44
in consideration of space and to be driven by power from the engine. Fuel from the fuel pump
42
is introduced into the engine
44
through a carburetor
48
.
FIG. 5
shows a conventional fuel pump
42
, and
FIG. 6
is a sectional view taken on line A—A of FIG.
5
. The fuel pump
42
comprises a bottom body portion
50
secured to the cylinder head cover
46
, a top body portion
52
mounted thereon, and a cover
54
. A piston
56
driven by the engine
44
is set so as to move with a reciprocating motion relative to the bottom body portion
50
. A diaphragm assembly
60
having a diaphragm
58
is connected to the piston
56
. The top body
52
is provided with a suction valve
62
and the discharge valve
64
which separate top and bottom sections of the top body portion
52
, which sections communicate through the suction valve
62
and the discharge valve
64
.
The fuel pump
42
is assembled by fixing the bottom body
50
, the top body
52
and the cover
54
with the diaphragm
58
held between the bottom body
50
and the top body
52
. A seal member
66
, such as a gasket, is held between the top body portion
52
and the cover
54
. For fixing the bottom body portion
50
, the top body portion
52
and the cover
54
together in one step, the bottom body portion
50
is formed with a stepped thread insert hole
68
, the top body
52
is formed with a thread insert hole
70
, and the cover
54
is formed with an internal threaded hole
72
. A bolt
74
is inserted into the threaded insert holes
68
,
70
from the bottom body portion
50
side so that the bolt
74
is threadedly engaged with the internally threaded portion
72
of the cover
54
. The external thread
74
is tightened to the internal thread portion
72
of the cover
54
whereby the bottom body
50
, the top body
52
and the cover
54
are integrally fixed.
The diaphragm
58
is held between the bottom body portion
50
and the top body portion
52
whereby a pump chamber
76
is defined within the top body portion
52
adjacent the diaphragm
58
. The seal member
66
is held between the top body
52
and the cover
54
and closes a suction chamber
78
and a discharge chamber
80
which are formed independent of each other within the top body portion
52
above the seal member
66
. The suction chamber
78
communicates with the pump chamber
76
through the suction valve
62
, and the discharge chamber
80
communicates with the pump chamber
76
through the discharge valve
64
.
In the fuel pump
42
, when the piston
56
and the diaphragm
58
are moved downward in
FIG. 5
, the discharge valve
64
is closed and the suction valve
62
is opened so that fuel is introduced into the pump chamber
76
from the suction chamber
78
. Next, when the piston
56
and the diaphragm
58
move upward in
FIG. 5
, the suction valve
62
is closed and the discharge valve
64
is opened so that fuel is moved to the discharge chamber
80
from the pump chamber
76
.
For sealing the bottom body portion
50
with the cylinder head cover
46
, there is used a thermal setting resin such as a phenol resin (bakelite) which is light weight and heat resistant, and has a high strength. The top body portion
52
and the cover
54
are formed of metal, such as aluminum, by die casting. Aluminum is used for the cover
54
because, in order to provide a tight fit when tightening the diaphragm
58
, the top body
52
and the seal member
66
by the external thread
74
, the cover
54
with the internally threaded hole
72
is made of metal. Aluminum is used for the top body
52
in order to prevent compressed permanent strain due to the tightening of the bottom body
50
and the cover
54
.
However, there has been the drawback that when the top body
52
and the cover
54
are formed of aluminum, a rust-proof treatment is necessary, which treatments increases the cost, and increases the weight.
Preferably, the top body
52
and the cover
54
are made of synthetic resin in consideration of economy and weight. However, when the cover
54
is made of synthetic resin, slack occurs in the threaded engagement by the bolt
74
, resulting in a possibility of leakage of fuel. Further, when the top body portion
52
is made of synthetic resin, it is tightened between the bottom body
50
and the cover
54
, resulting in a compressed permanent strain. Therefore, the top body
52
and the cover
54
could not be made of synthetic resin.
Further, as shown in
FIG. 5
, the bolt
74
is inserted through the diaphragm
58
and the seal member
66
. Therefore, it has been necessary to increase the size of the diaphragm to extend to a location where the bolt
74
can be inserted through the diaphragm
58
and the seal member
66
. Further, it is necessary for the diaphragm
58
and the seal member
66
to be formed with a hole (not shown) through which the bolt
74
is inserted, resulting in a possible breakage of the diaphragm
58
and the seal member
66
from formation of the hole.
The present invention has been made in view of the foregoing and has, as its object to provide a fuel pump which is excellent in heat resistance and salt resistance, which is low in cost and light in weight, and which is free from leakage of fuel.
SUMMARY OF THE INVENTION
For achieving the aforementioned object, according to the present invention, there is provided a fuel pump in which a diaphragm is held between a bottom body and a top body, and a seal member is held between the top body and a cover, wherein a thermosetting resin is used for the bottom body, a thermoplastic resin is used for the top body and the cover, with the seal member held between said top body and said cover, and said top body and said bottom body, with said diaphragm therebetween, are fixed together by a fixing means.
REFERENCES:
patent: 4086036 (1978-04-01), Hagen et al.
patent: 5192198 (1993-03-01), Gebauer et al.
Chiba Noriaki
Kubota Kenichi
Takehana Norio
Leslie Michael
Look Edward K.
Lorusso & Loud
Mikuni Adec Corporation
LandOfFree
Fuel pump does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fuel pump, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel pump will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2832688