U.S. patent application number 12/687315 was filed with the patent office on 2010-08-05 for fuel supply system for engine.
This patent application is currently assigned to FUJI JUKOGYO KABUSHIKI KAISHA. Invention is credited to MASANORI NOGUCHI.
Application Number | 20100196179 12/687315 |
Document ID | / |
Family ID | 42397874 |
Filed Date | 2010-08-05 |
United States Patent
Application |
20100196179 |
Kind Code |
A1 |
NOGUCHI; MASANORI |
August 5, 2010 |
FUEL SUPPLY SYSTEM FOR ENGINE
Abstract
When a flywheel rotates and a first magnet comes close to and
opposes a fuel pump, a plunger is moved toward a partition wall of
a pump chamber against an urging force of a spring by a magnetic
repulsive force generated between the first magnet and a second
magnet in the fuel pump. When the first magnet separates from the
fuel pump, the plunger is moved and returned toward a protective
cover by the urging force of the spring. As a result, the plunger
in the fuel pump reciprocates with rotation of the flywheel, and
the capacity of the pump chamber increases and decreases, so that
fuel is sucked and discharged.
Inventors: |
NOGUCHI; MASANORI; (Saitama,
JP) |
Correspondence
Address: |
DICKSTEIN SHAPIRO LLP
1633 Broadway
NEW YORK
NY
10019
US
|
Assignee: |
FUJI JUKOGYO KABUSHIKI
KAISHA
Tokyo
JP
|
Family ID: |
42397874 |
Appl. No.: |
12/687315 |
Filed: |
January 14, 2010 |
Current U.S.
Class: |
417/415 |
Current CPC
Class: |
F04B 17/04 20130101;
F02M 37/14 20130101; F02M 59/10 20130101; F02M 37/007 20130101;
F04B 9/06 20130101; F04B 17/05 20130101; F02M 69/02 20130101 |
Class at
Publication: |
417/415 |
International
Class: |
F04B 35/04 20060101
F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2009 |
JP |
2009-024930 |
Claims
1. An engine fuel supply system that pressurizes fuel from a fuel
tank and supplies the pressurized fuel to a fuel injection valve,
the engine fuel supply system comprising: a first magnetic member
fixed to an outer peripheral portion of a rotor connected to a
rotation shaft of an engine; and a fuel pump opposing the outer
peripheral portion of the rotor and including a second magnetic
member that magnetically acts on the first magnetic member, wherein
at least one of the first magnetic member and the second magnetic
member is formed by a permanent magnet, and wherein the fuel pump
reciprocates the second magnetic member by a magnetic force between
the first magnetic member and the second magnetic member, the
magnetic force changing with rotation of the rotor, and sucks the
fuel from the fuel tank and discharges the fuel with a
predetermined pressure by the reciprocation.
2. The engine fuel supply system according to claim 1, wherein the
first magnetic member is a permanent magnet for generating ignition
power.
3. The engine fuel supply system according to claim 1, wherein the
fuel pump is a plunger-type pump that sucks and discharges the fuel
by reciprocating a plunger including the second magnetic member.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The disclosure of Japanese Patent Application No.
2009-024930 filed on Feb. 5, 2009 including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a fuel supply system for an
engine, which pressurizes fuel from a fuel tank and supplies the
fuel to a fuel injection valve without using driving power from a
battery.
[0004] 2. Description of the Related Art
[0005] In most general-purpose engines of a spark ignition type for
use in power generators and operating machines, a battery is not
mounted, starting is performed by manually pulling a recoil
starter, and power for ignition is supplied by a magneto. In a case
in which the amount of fuel injected from a fuel injection valve
provided in such a general-purpose engine is electronically
controlled in accordance with the operating condition of the
engine, it is a problem how to ensure power for the devices.
[0006] In this case, the fuel injection valve and an electronic
control device for controlling the fuel injection valve can be
driven by the voltage provided immediately after starting is
performed by pulling the recoil starter. However, it is difficult
to ensure sufficient power for a fuel pump for generating fuel
pressure that is the point of fuel control. For this reason, there
is no other choice but to use, as the fuel pump, a mechanical fuel
pump that is driven by the engine.
[0007] For example, in a battery-less electronic fuel injection
control device disclosed in Japanese Unexamined Patent Application
Publication No. 5-164010, fuel is pressurized by a mechanical pump
that is driven in conjunction with the rotation of a flywheel
connected to a crankshaft of the engine, and the fuel is then
supplied to a fuel injection valve.
[0008] Japanese Examined Utility Model Registration Application
Publication No. 7-52374 discloses a technique using a film-valve
pulse pump for pressurizing and supplying fuel by the change in
internal pressure of a crankcase, and a plunger-type fuel pump to
be driven by a cam attached to a crankshaft. Fuel in a fuel tank is
pressure-fed to the plunger-type fuel pump by the film-valve pulse
pump, is further pressurized by the plunger-type fuel pump, and is
then supplied to a fuel injection valve.
[0009] However, in the mechanical fuel pump driven by the engine,
the mechanism is complicated to obtain a stable pressure suitable
for fuel injection, and this leads to a rise in cost. Moreover, the
performance may be reduced by the influences of trouble and
heat.
SUMMARY OF THE INVENTION
[0010] The present invention has been made in view of the
above-described circumstances, and an object of the invention is to
provide an engine fuel supply system capable of obtaining a stable
pressure suitable for fuel injection.
[0011] In order to achieve the above object, an engine fuel supply
system according to the present invention pressurizes fuel from a
fuel tank and supplies the pressurized fuel to a fuel injection
valve without using driving power from a battery. The engine fuel
supply system includes a first magnetic member fixed to an outer
peripheral portion of a rotor connected to a rotation shaft of an
engine; and a fuel pump opposing the outer peripheral portion of
the rotor and including a second magnetic member that magnetically
acts on the first magnetic member. At least one of the first
magnetic member and the second magnetic member is formed by a
permanent magnet. The fuel pump reciprocates the second magnetic
member by a magnetic force between the first magnetic member and
the second magnetic member, the magnetic force changing with
rotation of the rotor, and sucks the fuel from the fuel tank and
discharges the fuel with a predetermined pressure by the
reciprocation.
[0012] According to the present invention, it is possible to obtain
a stable pressure suitable for fuel injection without using a
complicated mechanism, and to thereby realize an inexpensive fuel
supply system with high reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a structural view of an engine fuel supply system;
and
[0014] FIG. 2 is an enlarged view showing an exemplary structure of
a fuel pump.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] An embodiment of the present invention will be described
below with reference to the drawings.
[0016] An engine 1 shown in FIG. 1 is a general-purpose engine of a
spark ignition type, and is used as, for example, a motor for a
power generator, an operating machine, or a snowmobile. In FIG. 1,
the engine 1 is an air-cooled V-engine, in which a suction port 4
and an exhaust port 5 are open in a cylinder head 3a provided in an
upper part of a cylinder 3 inclined with respect to a crankcase 2.
The suction port 4 communicates with an air cleaner (not shown),
and the exhaust port 5 communicates with a muffler 6 provided above
the cylinder head 3a.
[0017] A crankshaft 1a protrudes from the crankcase 2 of the engine
1. The crankshaft 1a is connected, via a connecting rod, to a
piston that slidably reciprocates in the cylinder 3, and is
rotatably supported by the crankcase 2. A cooling fan 7 is fitted
on and rotatably supported by a protruding shaft of the crankshaft
1a. On the circumference of the cooling fan 7, a plurality of fins
7a are arranged at regular intervals. A flywheel 9 (see FIG. 2) is
provided integrally with a back side of the cooling fan 7. A magnet
(permanent magnet) 8 for ignition is fixed to an outer peripheral
portion of the flywheel 9.
[0018] A control unit 10 and a fuel pump 20 are provided beside the
cooling fan 7 of the crankcase 2 in a manner such as to face the
magnet 8 of the flywheel 9 with a predetermined gap being
therebetween. The control unit 10 includes a magneto coil and an
ignition coil facing the magnet 8 of the flywheel 9 with a
predetermined gap being therebetween, an ignition circuit, such as
a transistor or a mechanical contact, for energizes and interrupts
one side of the ignition coil, a power supply circuit for
generating control power by rectifying and smoothing magneto power,
and an electronic control circuit for engine control that mainly
includes a microcomputer.
[0019] An ignition plug 11 is connected to an output side of the
ignition circuit incorporated in the control unit 10. The ignition
plug 11 is provided in the cylinder head 3a, and has, at its
leading end, a discharging electrode exposed in a fuel chamber.
Further, an injector (fuel injection valve) 12 is connected to an
output side of the electronic control circuit incorporated in the
control unit 10. The injector 12 injects fuel, which is press-fed
from the fuel pump 20, into a suction passage of the engine 1.
[0020] In FIG. 1, for convenience of understanding of the fuel
supply system, the injector 12 that is actually provided near the
suction port 4 of the engine 1 is shown separately from the engine
1.
[0021] Next, a description will be given of the fuel pump 20 that
is a major component of the fuel supply system. The fuel pump 20
includes a suction-side joint portion 21a serving as a fuel suction
port, a discharge-side joint portion 21b serving as a fuel
discharge port, and flange portions 21c serving portions mounted to
the crankcase 2. The suction-side joint portion 21a is connected to
a fuel tank 14 via a pipe 13, and the discharge-side joint portion
21b is connected to the injector 12 via a pipe 15.
[0022] A fuel filter 16 is interposed in the pipe 13 that connects
the fuel tank 14 and the fuel pump 20, and a pulsation damper 17
for damping pulsation of fuel pressure is interposed in the pipe 15
that connects the fuel pump 20 and the injector 12. For example,
the fuel tank 14 is provided above the engine 1.
[0023] As will be described below, a first magnetic member is fixed
to an outer peripheral portion of a rotor that is connected to the
crankshaft 1a serving as the rotation shaft of the engine 1, and
the fuel pump 20 includes a second magnetic member that can
magnetically act on the first magnetic member. At least one of the
first magnetic member and the second magnetic member is formed by a
permanent magnet. The fuel pump 20 is a reciprocating pump that is
operated by magnetic force of the permanent magnet in a non-contact
manner.
[0024] In the embodiment, as illustrated in FIG. 2, the first
magnetic member is the ignition magnet (permanent magnet) 8 fixed
to the outer peripheral portion of the flywheel 9 serving as the
rotor connected to the crankshaft 1a, and the second magnetic
member is a magnet (permanent magnet) 31 fixed to a plunger 30 in
the fuel pump 20. The fuel pump 20 is a plunger-type pump in which
the plunger 30 reciprocates by magnetic forces of the magnets 8 and
31 with rotation of the flywheel 9.
[0025] More specifically, the fuel pump 20 includes a pump housing
21 and a protective cover 22. The suction-side joint portion 21a,
the discharge-side joint portion 21b, and the flange portions 21c
for mounting are provided outside the pump housing 21, and the
plunger 30 is provided in the pump housing 21 in a manner such as
to move forward and backward. The protective cover 22 covers an
opening provided in a side of the pump housing 21 opposite the
suction-side joint portion 21a and the discharge-side joint portion
21b. The pump housing 21 is formed of a nonmagnetic material such
as aluminum, and the protective cover 22 is formed of a
magnetically permeable material such that the magnetic force from
the magnet 8 of the flywheel 9 acts on the interior of the fuel
pump 20.
[0026] The pump housing 21 includes a pump chamber 23 accommodating
the plunger 30, a suction-valve chamber 25 accommodating a check
valve 24 that transmits fuel from the suction-side joint portion
21a only toward the pump chamber 23, and a discharge valve chamber
27 accommodating a check valve 26 that transmits fuel from the pump
chamber 23 only toward the discharge-side joint portion 21b.
[0027] The plunger 30 is shaped like a hollow cylinder having one
closed end, and the magnet (permanent magnet) 31 is fixed to the
closed end. The plunger 30 is provided in the pump chamber 23 with
the magnet 31 facing the protective cover 22 in a manner such as to
move into and out of the pump chamber 23. A spring 28 for urging
the plunger 30 toward the protective cover 22 is provided between a
back surface of the closed end in the plunger 30 and a partition
wall 23a for the valve chambers 25 and 27 of the pump chamber 23.
Further, a seal member 29, such as an O-ring or an oil seal, is
provided on an inner peripheral surface of the cylinder of the pump
chamber 23. The seal member 29 serves to maintain oil tightness
between the inner peripheral surface of the pump chamber 23 and an
outer peripheral surface of the cylinder of the plunger 30.
[0028] The magnet 31 fixed to the plunger 30 and the magnet 8 fixed
to the outer peripheral portion of the flywheel 9 are set in a
manner such that the same poles thereof oppose each other.
[0029] The fuel pump 20 having the above-described configuration is
located such that the moving axis direction of the plunger 30
points toward the rotation center of the flywheel 9 and such that a
specified distance is provided between the fuel pump 20 and the
magnet 8 of the flywheel 9. The fuel pump 20 is fixed to the
crankcase 2 by bolts with the flange portions 21c being disposed
therebetween. Next, a description will be given of how the engine 1
is driven by the fuel supply from the above-described fuel pump
20.
[0030] First, when the flywheel 9 is rotated by pulling the recoil
starter (not shown), the magnet 8 fixed to the outer peripheral
portion of the flywheel 9 circles to pass across the fronts of the
control unit 10 and the fuel pump 20. Then, control power is
generated from magnet power that is produced by the rotation of the
flywheel 9, and operates the ignition circuit and the electronic
control circuit in the control unit 10.
[0031] In this case, at a position where the magnet 8 of the
flywheel 9 is located close to and opposes the fuel pump 20, the
plunger 30 having the magnet 31 fixed thereto moves toward the
partition wall 23a of the pump chamber 23 against the urging force
of the spring 28 because of magnetic repulsive force generated
between the magnet 8 of the flywheel 9 and the magnet 31 in the
fuel pump 20. In contrast, when the magnet 8 separates from the
fuel pump 20, the repulsive force between the magnets 8 and 31
reduces or disappears, so that the plunger 30 moves and returns
toward the protective cover 22 because of the urging force of the
spring 28.
[0032] As a result, with the rotation of the flywheel 9, the
plunger 30 in the fuel pump 20 reciprocates toward the partition
wall 23a and the protective cover 22, whereby the capacity of the
pump chamber 23 increases and decreases to suck and discharge the
fuel. In other words, when the plunger 30 moves toward the
protective cover 22, the capacity of the pump chamber 23 increases,
the pressure in the pump chamber 23 decreases, the check valve 24
of the suction valve chamber 25 opens, so that fuel is sucked from
the fuel tank 14 into the pump chamber 23 through the suction-side
joint portion 21a. The fuel in the pump chamber 23 is pressurized
by the movement of the plunger 30 toward the partition wall 23a,
and the check valve 26 of the discharge valve chamber 27 opens at a
predetermined pressure, so that the fuel is discharged from the
discharge-side joint portion 21b and is supplied to the injector
12.
[0033] Then, the injector 12 is driven to inject the fuel at a
valve opening time calculated by a CPU of the electronic control
circuit in the control unit 10. Further, the ignition plug 11
sparks in response to a signal from the ignition circuit, and a
mixture of the fuel injected from the injector 12 and the sucked
air is ignited and burnt, whereby the engine 1 is driven.
[0034] In this way, in the embodiment, the fuel supply system for
supplying the fuel to the injector 12 is configured by utilizing
the magnet 8 fixed to the outer peripheral portion of the flywheel
9 of the magneto ignition engine. That is, it is possible to
realize an inexpensive fuel supply system in which the plunger 30
of the fuel pump 20 reciprocates by a magnetic force of the
ignition magnet 8 with the rotation of the flywheel 9.
[0035] In the fuel pump 20 of this fuel supply system, there is no
need to obtain pump driving force by mechanical connection to the
rotation shaft of the engine, a stable driving force can be
obtained without contact with the rotating section of the engine,
and a stable pressure suitable for fuel injection can be obtained.
In addition, since the pump is driven without contact with the
rotating section of the engine, it is possible to suppress
performance degradation due to trouble and heat, and to realize an
inexpensive fuel supply system with high reliability.
[0036] The fuel pump 20 that constitutes of the fuel supply system
in the above-described embodiment is just exemplary, and various
other modifications are possible. For example, the fuel supply
system can have the following configurations (1) to (3):
[0037] (1) The magnet 31 fixed to the leading end of the plunger 30
in the fuel pump 20 and the magnet 8 fixed to the outer peripheral
portion of the flywheel 9 are set in a manner such that opposite
poles thereof face each other, and the spring 28 for urging the
plunger 30 is formed by a tension spring.
[0038] (2) The magnet 31 fixed to the leading end of the plunger 30
in the fuel pump 20 is eliminated, and a magnetic member, such as a
steel member, is fixed to the leading end of the plunger 30.
Alternatively, the plunger 30 itself is formed by a magnetic
material. Also, the spring 28 for urging the plunger 30 is formed
by a tension spring.
[0039] (3) The fuel pump 20 is formed by a reciprocating pump using
a diaphragm, instead of the plunger 30.
* * * * *