Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2002-05-07
2004-05-18
Yu, Justine R. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C137S102000, C137S512400, C123S567000, C123S566000, C417S443000, C417S560000, C417S570000
Reexamination Certificate
active
06736613
ABSTRACT:
REFERENCE TO RELATED APPLICATION
Applicant claims priority of Japanese Patent Application Serial No. 2001-149,268, filed May 18, 2001.
TECHNICAL DESCRIPTION
The present invention relates to a carburetor and more particularly to an acceleration fuel pump of a float-type carburetor for a combustion engine.
BACKGROUND OF THE INVENTION
Carburetors for combustion engines are known to have acceleration fuel pumps designed to enrich a fuel-and-air mixture for combustion during acceleration of an engine. Referring to
FIG. 7
, an acceleration fuel pump
10
of a known float-type carburetor
12
has a body
14
with a float chamber
16
. The acceleration pump
10
has a primary machined cylindrical bore
18
carried by the body
14
which intersects a fuel passage
20
that communicates between the float or fuel chamber
16
and a carburetor fuel-and-air mixture passage that typically extends between an air intake filter and the combustion chamber or crankcase of an engine, not shown.
A variable volume fuel reservoir portion of the primary bore
18
is disposed below a reciprocating plunger
24
disposed within the bore
18
and sealably engaging the cylindrical wall. Fuel is drawn into the reservoir portion of the bore
18
from an upstream side of the fuel feed passage
20
when the plunger
24
begins to retract out of the primary bore
18
causing the reservoir portion to enlarge which draws fuel into the reservoir from an upstream side of the fuel feed passage
20
. Passage
20
communicates with the fuel chamber
16
of the carburetor
12
through a normally closed inlet check valve
22
disposed in the feed passage and adjacent to the fuel chamber
16
and a normally closed outlet check valve
26
disposed in a downstream side of the feed passage
20
. Fuel is drawn into the reservoir by retraction or upward movement of the plunger
24
caused by the force of a compressed spring
28
disposed between the bottom of the plunger
24
and the bottom of the bore
18
and creates a vacuum or subatmospheric pressure which draws or causes fuel to flow into the bore
18
. When the running engine begins an acceleration period, a rod
46
engaged to the top of the plunger
24
pushes or advances the plunger against the force of the resilient spring
28
into the fuel filled bore
18
. The inlet check valve
22
closes and the outlet check valve
26
opens so that fuel from the reservoir is pushed or flows through the downstream side of the fuel feed passage
20
through the open outlet check valve
26
and into the fuel-and-air mixing passage. When the acceleration of the engine is complete, the spring
28
once again causes the plunger
24
to retract in the bore
18
causing fuel from the fuel chamber
16
to once again fill the expanding reservoir portion of the bore
18
.
The inlet check valve
22
has a sleeve
32
press fitted into a machined cylindrical bore in a cavity of the carburetor body
14
. The sleeve
32
has a through bore
30
with a seat against which a metallic sphere or ball bearing
34
is forced by a compressed coil spring
36
to bias the check valve
22
closed. The fuel pressure in the upstream side of the bore
30
must be sufficiently greater than the fuel pressure within the primary bore
18
for the net hydraulic force to move the ball
34
away from the seat of the sleeve
32
permitting fuel to flow through the fuel feed passage
20
into the primary bore
18
.
The outlet check valve
26
also has a sleeve
40
press fitted into a machine bore
41
. However, unlike the inlet check valve
22
, a ball bearing
44
is forced against a seat carried by the carburetor body
14
within the bore
41
and below the sleeve
40
. When the ball bearing
44
is received on the seat, the check valve
26
is closed and fuel flow into the fuel-and-air mixing passage from the feed passage
20
or air flow into the feed passage
20
from the fuel-and-air mixing passage is blocked. A compression spring
42
is disposed between the sleeve
40
and the ball bearing
44
to yieldably urge the ball bearing against the body seat. During acceleration of the engine and as the plunger
24
is inserted further into the bore
18
the fuel pressure within the fuel feed passage
20
increases moving the ball
44
of the outlet check valve
26
upward and away from the seat against the force of the spring
42
so that fuel can flow into the fuel-and-air mixing passage of the carburetor. When the outlet check valve
26
is open, the inlet check valve
22
remains closed via the ball bearing
34
so that reverse air and/or fuel flow back into the fuel chamber
16
of the carburetor does not occur.
Unfortunately, the construction of the check valves
22
,
26
requires additional machining of the carburetor body
14
and requires many component parts which increases manufacturing costs. In addition, dirt and debris can cause malfunction of either check valve which can degrade the efficiency or cause malfunction of the acceleration pump
10
.
SUMMARY OF THE INVENTION
An acceleration fuel pump of a carburetor for combustion engine is part of the carburetor body and provides an additional flow of fuel to the fuel-and-air mixing passage of the carburetor during acceleration of the engine. The acceleration fuel pump has a plunger which inserts sealably into a cylindrical cavity carried by the body of the carburetor. During acceleration of the engine, the plunger inserts further into the cavity against the resilient force of a spring and toward a resilient check valve member causing the member to deform or expand into a fuel feed state. A fuel feed passage which extends between the bottom of a fuel chamber of the carburetor and the fuel-and-air mixing passage of the carburetor is intersected by the cavity and the resilient check valve member.
A leading portion of the resilient valve member has a slit which opens when the member is in the fuel feed state permitting fuel, displaced by the plunger, to flow out of a fuel reservoir carried by the cavity and into an outlet leg of the fuel feed passage which supplies fuel to the fuel-and air-mixing passage. During insertion of the plunger, pressure within the fuel reservoir overcomes the pressure within the upstream side or inlet leg of the fuel feed passage causing a trailing segment of the member to expand radially outward and engage the internal cylindrical wall of the cavity preventing any reverse flow from the fuel reservoir and into the inlet leg of the fuel passage which extends from the cavity to the fuel chamber. When the engine is done accelerating, insertion of the plunger terminates or has stopped and the internal spring forces the plunger to retract in an outward direction from the cavity. This retraction causes a pressure reduction within the fuel reservoir causing the slit of the leading segment of the check valve member to close and the peripheral rim of the trailing segment to separate or space from the cylindrical wall of the cavity. Fuel then is drawn from the fuel chamber through the inlet leg of the fuel passage into the fuel reservoir in preparation for the next acceleration period of the combustion engine.
Objects, features and advantages of this invention includes an acceleration fuel pump which is significantly impervious to dirt and debris, has a greatly reduced number of parts, requires less machining during manufacturing and may be readily incorporated into existing acceleration fuel pump designs. Additional advantages are improved acceleration of the engine, a relatively simple design and economical manufacture and assembly and in service a significantly increased useful life.
REFERENCES:
patent: 2912999 (1959-11-01), Kersh
patent: 3604451 (1971-09-01), Delamater
patent: 3664774 (1972-05-01), Tupper et al.
patent: 3788615 (1974-01-01), Bishop
patent: 4084606 (1978-04-01), Mittleman
patent: 4278618 (1981-07-01), Higashigawa et al.
patent: 4824337 (1989-04-01), Lindner et al.
patent: 4832582 (1989-05-01), Buffet
patent: 5237309 (1993-08-01), Frantz et al.
patent: 5301707 (1994-04-01), Hofsteenge
patent: 5305777 (1994-04-01),
Reising Ethington Barnes Kisselle P.C.
Sayoc Emmanuel
Walbro Japan, Inc.
Yu Justine R.
LandOfFree
Acceleration fuel pump having a resilient check valve member... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Acceleration fuel pump having a resilient check valve member..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Acceleration fuel pump having a resilient check valve member... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3210041