U.S. patent application number 11/386699 was filed with the patent office on 2006-10-05 for fuel pump having plunger and fuel supply system using the same.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Yoshitsugu Inaguma, Hiroshi Inoue, Kaoru Oda, Tatsumi Oguri, Nobuo Ohta.
Application Number | 20060222538 11/386699 |
Document ID | / |
Family ID | 36423634 |
Filed Date | 2006-10-05 |
United States Patent
Application |
20060222538 |
Kind Code |
A1 |
Inoue; Hiroshi ; et
al. |
October 5, 2006 |
Fuel pump having plunger and fuel supply system using the same
Abstract
A delivery valve is connected to a discharge passage, through
which fuel in a compression chamber is discharged. The delivery
valve is screwed to a mount hole formed in the cylinder. A
communication passage is formed in a body to extend through the
sidewall between a screwed part, in which the mount hole and the
body are screwed to each other, and a gasket. A small clearance is
formed between an inner peripheral surface of the mount hole and an
outer peripheral surface of the body. The communication passage
provides communication between a fuel passage downstream of a valve
seat member and the clearance. The clearance communicates with the
suction chamber through a return passage formed in the
cylinder.
Inventors: |
Inoue; Hiroshi; (Anjo-city,
JP) ; Oguri; Tatsumi; (Okazaki-city, JP) ;
Ohta; Nobuo; (Takahama-city, JP) ; Inaguma;
Yoshitsugu; (Chita-gun, JP) ; Oda; Kaoru;
(Toyokawa-city, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
448-8661
|
Family ID: |
36423634 |
Appl. No.: |
11/386699 |
Filed: |
March 23, 2006 |
Current U.S.
Class: |
417/470 |
Current CPC
Class: |
F02M 59/462 20130101;
F02M 2200/28 20130101; F02M 2200/60 20130101; F02M 59/447 20130101;
F02M 63/0225 20130101; F02M 59/102 20130101; F02M 63/005 20130101;
F02M 63/0036 20130101 |
Class at
Publication: |
417/470 |
International
Class: |
F04B 19/00 20060101
F04B019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2005 |
JP |
2005-98583 |
Nov 24, 2005 |
JP |
2005-339003 |
Claims
1. A fuel pump that supplies fuel to a delivery pipe, the fuel pump
comprising: a pump housing that has a compression chamber and at
least one mount hole; a plunger that is movable in the pump
housing, the plunger being adapted to pressurizing fuel drawn into
the compression chamber; a delivery valve that communicates the
compression chamber with the delivery pipe when fuel pressure in
the compression chamber is equal to or greater than a threshold;
and at least one functional component that is provided to the at
least one mount hole of the pump housing, wherein the at least one
functional component and the at least one mount hole define at
least one clearance therebetween, and fuel on a downstream side of
the delivery valve returns into a low-pressure side thereof through
the at least one clearance.
2. The fuel pump according to claim 1, wherein the at least one
clearance includes a plurality of clearances, and fuel on the
downstream side of the delivery valve passes through the plurality
of clearances to return into the low-pressure side.
3. The fuel pump according to claim 1, wherein the delivery valve
has an inlet of a return passage, through which fuel on the
downstream side of the delivery valve returns to a low-pressure
side thereof.
4. The fuel pump according to claim 1, wherein the delivery valve
is one of the at least one functional component.
5. The fuel pump according to claim 1, wherein the plunger is one
of the at least one functional component, and fuel on the
downstream side of the delivery valve returns to a low-pressure
side thereof through one of the at least one clearance defined in a
sliding part, in which the plunger slides on the pump housing.
6. The fuel pump according to claim 1, wherein the at least one
functional component includes at least one of a relief valve and a
metering valve, the relief valve restricts fuel pressure on the
downstream side of the delivery valve from rising, and the metering
valve is arranged between the upstream of the compression chamber
and the compression chamber, the metering valve being adapted to
communicating and blocking the upstream of the compression chamber
with the compression chamber.
7. The fuel pump according to claim 1, wherein fuel passing through
the at least one clearance returns into the pump housing.
8. The fuel pump according to claim 1, wherein the at least one
mount hole has an inner peripheral surface, which is substantially
circular in shape, and the at least one functional component has an
outer peripheral surface, which is substantially circular in
shape.
9. The fuel pump according to claim 1, wherein the at least one
clearance communicates the downstream side of the delivery valve
with an upstream side of the compression chamber at least in a
condition where fuel pressure in the compression chamber is less
than the threshold.
10. A fuel supply system including a fuel pump comprising: a pump
housing that has a compression chamber and at least one mount hole;
a plunger that is movable in the pump housing, the plunger being
adapted to pressurizing fuel in the compression chamber; a delivery
valve that communicates the compression chamber with a downstream
of the delivery valve when pressure in the compression chamber is
equal to or greater than a threshold; and at least one fluid
component that is adapted to communicating an upstream of the
compression chamber with a downstream of the compression chamber,
wherein at least one of the plunger, the delivery valve, and the at
least one of fluid component is provided to the at least one mount
hole of the pump housing, the at least one of the plunger, the
delivery valve, and the at least one of fluid component defines at
least one clearance with respect to the at least one mount hole,
and the at least one clearance communicates the downstream of the
delivery valve with the upstream of the compression chamber at
least in a condition where fuel pressure in the compression chamber
is less than the threshold.
11. The fuel supply system according to claim 10, wherein the at
least one fluid component includes at least one of a relief valve
and a metering valve, the relief valve is adapted to restricting
pressure in the downstream of the delivery valve from rising, and
the metering valve is arranged between the upstream of the
compression chamber and the compression chamber, the metering valve
being adapted to communicating and blocking the upstream of the
compression chamber with the compression chamber.
12. The fuel supply system according to claim 10, wherein the at
least one clearance includes a plurality of clearances, and the
downstream of the delivery valve communicates with the upstream of
the compression chamber through the plurality of clearances.
13. The fuel supply system according to claim 10, wherein the
delivery valve has an inlet of a return passage, through which the
downstream of the delivery valve communicates with the upstream of
the compression chamber.
14. The fuel supply system according to claim 10, wherein the
plunger defines a sliding part, in which the plunger slides through
one of the at least one mount hole of the pump housing, and the
plunger defines one of the at least one of the clearance with
respect to the one of the at least one mount hole in the sliding
part.
15. The fuel supply system according to claim 10, wherein the at
least one clearance communicates with an inside of the pump housing
upstream of the compression chamber.
16. The fuel supply system according to claim 10, wherein the at
least one mount hole has an inner peripheral surface, which is
substantially circular in shape, and the at least one functional
component has an outer peripheral surface, which is substantially
circular in shape.
17. A fuel supply system including a fuel pump comprising: a pump
housing that has a compression chamber and a mount hole; a plunger
that is movable in the pump housing, the plunger being adapted to
pressurizing fuel in the compression chamber; a delivery valve that
communicates the compression chamber with a downstream of the
delivery valve when pressure in the compression chamber is equal to
or greater than a threshold; and wherein the delivery valve is
provided to the mount hole of the pump housing, the delivery valve
defines a clearance with respect to the mount hole, and the
clearance communicates the downstream of the delivery valve with
the upstream of the compression chamber at least in a condition
where fuel pressure in the compression chamber is less than the
threshold.
18. A fuel supply system including a fuel pump comprising: a pump
housing that has a compression chamber; a plunger that is movable
in the pump housing to pressurize fuel in the compression chamber;
and a delivery valve that communicates the compression chamber with
a downstream of the delivery valve when pressure in the compression
chamber is equal to or greater than a threshold, wherein the pump
housing at least partially defines at least one clearance that
communicates the downstream of the delivery valve with an upstream
of the compression chamber at least in a condition where fuel
pressure in the compression chamber is less than the threshold.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and incorporates herein by
reference Japanese Patent Applications No. 2005-98583 filed on Mar.
30, 2005 and No. 2005-339003 filed on Nov. 24, 2005.
FIELD OF THE INVENTION
[0002] The present invention relates to a fuel pump, which
pressurizes fuel in a compression chamber using a plunger in order
to supply the fuel, and a fuel supply system using the fuel
pump.
BACKGROUND OF THE INVENTION
[0003] According to US 2003/0161746A1 (JP-A-2001-295770), a
high-pressure fuel pump includes a plunger that reciprocates to
pressurize fuel drawn into a compression chamber in order to supply
the fuel into a delivery pipe connected to a fuel injection valve.
The fuel supplied to the delivery pipe is jetted into a combustion
chamber of an internal combustion engine from the fuel injection
valve.
[0004] Such a high-pressure fuel pump includes a delivery valve
mounted downstream of the compression chamber. The delivery valve
is opened when fuel pressure in the compression chamber increases
to be equal to or greater than predetermined pressure, thereby
supplying the fuel in the compression chamber into the delivery
pipe. The delivery valve also serves as a check valve that
restricts counterflow of fuel from the delivery pipe into the
compression chamber.
[0005] When a fuel injection valve is stopped by fuel cut in
operation of an engine or by stoppage of the engine, the downstream
side of the high-pressure fuel pump is blocked by a delivery valve
and the fuel injection valve. When a relief valve is provided to
restrict abnormal rise in fuel pressure on the downstream side of
the high-pressure fuel pump, the relief valve further blocks the
downstream side of the high-pressure fuel pump. Thus, fuel
downstream of the high-pressure fuel pump is maintained in high
pressure. Such fuel pressure is a control pressure when the fuel
injection valve is stopped. In addition, in the case where the
engine has been adequately warmed, fuel pressure further rises due
to heat transmitted from the engine.
[0006] When fuel pressure downstream of the high-pressure fuel pump
is maintained high, upstream of the fuel injection valve is also
maintained high. In this condition, fuel may leak from a valve
portion of the fuel injection valve, which is maintained in a
closed state during stoppage of the engine, into a combustion
chamber. When fuel leaks into the combustion chamber during
stoppage of the engine, a large amount of an unburned fuel
ingredient such as hydrocarbon may be discharged into exhaust gases
at the start of the engine. In addition, when fuel injection is
restarted from a state of fuel cut in the operation of the engine,
it is desired that an amount of fuel jetted from the fuel injection
valve be small to be adapted to the operating state. However, when
fuel upstream of the fuel injection valve is maintained in high
pressure, a large amount of fuel may be jetted from the fuel
injection valve in the restart of fuel injection. Consequently,
engine output may rapidly increase, and a shock may be applied on a
drive system of the engine.
[0007] Hereupon, a small passage such as a groove may be provided
in a seat surface of a valve portion of a delivery valve or a
relief valve in order to introduce fuel downstream of the
high-pressure fuel pump to a low-pressure side during stoppage of
the fuel injection valve. In this structure, fuel pressure on the
downstream side of the high-pressure fuel pump can be reduced
during stoppage of the fuel injection valve.
[0008] When the passage provided on the seat surface of the valve
portion of the delivery valve or the relief valve is excessively
large in area, an amount of fuel returning from the downstream of
the high-pressure fuel pump to the low-pressure side may increase.
Consequently, the amount of fuel returning to the low-pressure side
may increase during the operation of the fuel injection valve.
Accordingly, the high-pressure fuel pump needs to additionally
discharge the amount of the fuel returning to the low pressure side
in order to make up for the amount of the return fuel. As a result,
discharge capacity of the high-pressure fuel pump needs to be
increased.
SUMMARY OF THE INVENTION
[0009] In view of the foregoing and other problems, it is an object
of the present invention to produce a fuel pump capable of reducing
fuel pressure downstream of the fuel pump while reducing an amount
of fuel returning to a low-pressure side from the downstream of a
delivery valve of the fuel pump. It is another object of the
present invention to produce a fuel supply system using the fuel
pump.
[0010] According to one aspect of the present invention, a fuel
pump, which supplies fuel to a delivery pipe, includes a pump
housing, a plunger, a delivery valve, and at least one functional
component. The pump housing has a compression chamber and at least
one mount hole. The plunger is movable in the pump housing. The
plunger is adapted to pressurizing fuel drawn into the compression
chamber. The delivery valve communicates the compression chamber
with the delivery pipe when fuel pressure in the compression
chamber is equal to or greater than a threshold. At least one
functional component is provided to the at least one mount hole of
the pump housing. The at least one functional component and the at
least one mount hole define at least one clearance therebetween.
Fuel on a downstream side of the delivery valve returns into a
low-pressure side thereof through the at least one clearance.
[0011] Thus, fuel pressure downstream of the delivery valve can be
reduced, even when fuel is not discharged from the delivery pipe
downstream of the delivery valve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description made with reference to the accompanying
drawings. In the drawings:
[0013] FIG. 1 is a schematic view showing a structure of a fuel
supply system including a high-pressure fuel pump, according to a
first embodiment of the present invention;
[0014] FIG. 2A is a partially cross sectional side view showing the
high-pressure fuel pump and a delivery valve, and FIG. 2B is an
enlarged cross sectional side view showing the delivery valve,
according to the first embodiment;
[0015] FIG. 3 is a partially cross sectional side view showing the
high-pressure fuel pump and a piping joint, according to the first
embodiment;
[0016] FIG. 4 is a partially cross sectional view taken along the
line IV-IV in FIG. 2A;
[0017] FIG. 5A is a partially cross sectional side view showing a
high-pressure fuel pump and a relief valve, and FIG. 5B is an
enlarged cross sectional side view showing the relief valve,
according to a second embodiment of the present invention;
[0018] FIG. 6 is a cross sectional view taken along the line VI-VI
in FIG. 5A;
[0019] FIG. 7 is a partially cross sectional side view showing a
high-pressure fuel pump including a delivery valve and a relief
valve, according to a third embodiment of the present
invention;
[0020] FIG. 8 is a cross sectional view taken along the line
VIII-VIII in FIG. 7;
[0021] FIG. 9 is an enlarged cross sectional side view showing the
delivery valve according to the third embodiment;
[0022] FIG. 10 is an enlarged cross sectional side view showing the
relief valve according to the third embodiment;
[0023] FIG. 11 is a schematic view showing a structure of a fuel
supply system including a high-pressure fuel pump, according to a
fourth embodiment of the present invention;
[0024] FIG. 12 is a partially cross sectional side view showing a
high-pressure fuel pump according to a fifth embodiment of the
present invention;
[0025] FIG. 13 is a partially cross sectional side view showing a
high-pressure fuel pump according to a sixth embodiment of the
present invention;
[0026] FIG. 14 is a partially cross sectional side view showing a
high-pressure fuel pump according to a seventh embodiment of the
present invention; and
[0027] FIG. 15 is a partially cross sectional side view showing a
high-pressure fuel pump according to an eighth embodiment of the
present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
First Embodiment
[0028] As follows, a high-pressure fuel pump 10 in the first
embodiment is described in reference to FIGS. 1, 2A, 2B, 3, and 4.
FIG. 2A is the view taken along the line IIA-IIA in FIG. 4. FIG. 3
is the view taken along the line III-III in FIG. 4.
[0029] As shown in FIG. 1, a fuel supply system includes a
high-pressure fuel pump 10. In addition, the fuel supply system is
a direct injection gasoline supply system that jets fuel directly
into cylinders of a gasoline engine. The high-pressure fuel pump 10
supplies fuel into fuel injection valves 7.
[0030] The high-pressure fuel pump 10 uses an electromagnetic
driven type metering valve (solenoid valve) 60 to provide and
interrupt communication between a suction chamber 210 and a
compression chamber 220. Fuel from a low-pressure fuel pump 1 is
supplied into the suction chamber 210. A plunger 40 reciprocates
with rotation of a cam 2 to pressurize fuel drawn into the
compression chamber 220. Fuel pressurized in the compression
chamber 220 passes from a delivery valve 80 to be supplied to a
delivery pipe 6 through a fuel pipe 4 on the downstream side of the
high-pressure fuel pump 10. Fuel injection valves 7 are mounted to
the delivery pipe 6 to jet fuel, which is accumulated in the
delivery pipe 6, into combustion chambers of an engine. A relief
valve 8 is mounted to the fuel pipe 4 on the downstream side of the
high-pressure fuel pump 10. The relief valve 8 restricts abnormal
rise in fuel pressure on the downstream side of the high-pressure
fuel pump 10.
[0031] Subsequently, the construction of the high-pressure fuel
pump 10 is described. The high-pressure fuel pump 10 is constructed
of a cylinder 12, a housing cover 30, a plunger 40, a piping joint
50, the metering valve 60, the delivery valve 80, and the like.
[0032] The cylinder 12 and the housing cover 30 form a pump
housing. The cylinder 12 is formed of a magnetic material such as a
martensitic stainless steel. The cylinder 12 supports the plunger
40 to permit reciprocation thereof. The cylinder 12 has a sliding
portion 14, on which the plunger 40 slides. The sliding portion 14
is hardened by induction hardening or the like. Functional
components of the high-pressure fuel pump 10 are mounted directly
on the cylinder 12. The functional components of the high-pressure
fuel pump 10 include the piping joint 50, the metering valve 60,
the delivery valve 80, and the like. The piping joint 50 forms a
fuel inlet. The delivery valve 80 forms a fuel outlet. The cylinder
12 constructs a housing body of the high-pressure fuel pump 10.
[0033] In addition, the cylinder 12 has an introduction passage
202, a suction passage 212, the compression chamber 220, a relief
passage 222, a discharge passage 230, a return passage 244, and the
like. The suction chamber 210 is formed between the cylinder 12 and
the housing cover 30.
[0034] The sliding portion 14 of the cylinder 12 supports the
plunger 40 to permit reciprocation thereof. The compression chamber
220 is formed on one end side of the plunger 40 with respect to the
direction, in which the plunger 40 reciprocates. A head 42 formed
on the other end side of the plunger 40 joins to a spring seat 44.
A spring 46 is interposed between the spring seat 44 and the
cylinder 12. The spring seat 44 is pushed against an inner wall of
a bottom of a tappet 3 (FIG. 1) by the bias of the spring 46. As
the cam 2 (FIG. 1) rotates, an outer wall of the bottom of the
tappet 3 slides on the cam 2 whereby the plunger 40 reciprocates.
An oil seal 48 seals between an outer peripheral surface of the
plunger 40 on the side of the head 42 and an inner peripheral
surface of the cylinder 12, which receives the plunger 40 therein.
The oil seal 48 restricts intrusion of oil into the compression
chamber 220 from the inside of an engine, and restricts leakage of
oil into the engine from the inside of the compression chamber 220.
Fuel leaking from a sliding part, in which the plunger 40 and the
cylinder 12 slide on each other, toward the oil seal 48 returns to
the low-pressure side introduction passage 202 from the relief
passage 222. Thereby, high fuel pressure is restricted from being
applied on the oil seal 48.
[0035] As shown in FIG. 3, a body 52 of the piping joint 50 and the
cylinder 12 are screwed to each other, whereby the piping joint 50
is mounted to a mount hole 16 formed in the cylinder 12. A fuel
passage 200 being communicated with the introduction passage 202 is
formed in the body 52 of the piping joint 50, and a fuel filter 54
is mounted in the fuel passage 200.
[0036] The metering valve 60 is constructed of a valve member 62, a
guide 64, a spring 66, a valve seat member 68, an electromagnetic
drive unit 70, and the like. The valve member 62 is formed by
applying coating of high hardness on a cup-shaped magnetic material
or on a cup-shaped surface of a magnetic material. The valve member
62 is guided by the guide 64 to be able to reciprocate. The spring
66 biases the valve member 62 toward the valve seat member 68,
which is mounted on the side of the suction chamber 210 with
respect to the valve member 62. When the valve member 62 is seated
on the valve seat member 68, communication between the suction
chamber 210 and the suction passage 212 is interrupted. The valve
seat member 68 is screwed to the cylinder 12.
[0037] The electromagnetic drive unit 70 of the metering valve 60
is formed by insert-molding a center core 74 and a coil portion 76
into a resin portion 72. The center core 74 and the coil portion 76
are arranged outwardly eccentric from the valve member 62. The
center core 74 and the coil portion 76 are fitted into a recess 18
of the cylinder 12 provided on the outer peripheral side of the
compression chamber 220 on the opposite side of the suction chamber
210 with respect to the valve member 62. When the coil portion 76
is electrically turned ON, a magnetic attraction force acts between
an attracting portion 20 of the cylinder 12 and the valve member
62. The attracting portion 20 of the cylinder 12 is provided on the
opposite side of the valve seat member 68 with respect to the valve
member 62.
[0038] As referred to FIGS. 2A, 2B, the delivery valve 80 forming a
fuel outlet of the high-pressure fuel pump 10 is constructed of a
body 82, a valve member 84, a spring 85, a spring seat 86, and a
valve seat member 87. The delivery valve 80 is connected to a
discharge passage 230, through which fuel in the compression
chamber 220 is discharged. Female threads are formed on an inner
peripheral surface 23 of a mount hole 22 formed in the cylinder 12.
Male threads are formed on an outer peripheral surface 83 of the
body 82. The female threads of the mount hole 22 and male threads
are screwed to each other, whereby the delivery valve 80 is mounted
to the mount hole 22. A gasket 88 seals between the mount hole 22
and the delivery valve 80 inside the cylinder 12 with respect to a
screwed part, in which the mount hole 22 and the delivery valve 80
are screwed to each other. An O-ring 89 seals between the mount
hole 22 and the delivery valve 80 outside the cylinder 12 with
respect to the screwed part.
[0039] The spring 85 is latched at one end on the spring seat 86 to
bias the valve member 84 in the direction, in which the valve
member 84 is seated on the valve seat member 87. The body 82 is
formed with a fuel passage 232, such that communication between the
discharge passage 230 and the fuel passage 232 is interrupted when
the valve member 84 is seated on the valve seat member 87. A
communication passage 240 being a return passage is formed in the
body 82 to extend through the sidewall between the screwed part, in
which the mount hole 22 and the body 82 are screwed to each other,
and the gasket 88. The communication passage 240 communicates with
the fuel passage 232 downstream of the valve seat member 87. The
delivery valve 80 is provided with an inlet of a return passage. A
small clearance 242 is defined between the inner peripheral surface
23 of the mount hole 22 and the outer peripheral surface 83 of the
body 82 on the side of gasket 88. The small clearance 242 is formed
in the screwed part, in which the mount hole 22 and the body 82 are
screwed to each other, including a location, in which the
communication passage 240 is formed. The clearance 242 communicates
with the communication passage 240, thereby communicating with the
fuel passage 232 downstream of the valve seat member 87. In
addition, the clearance 242 communicates with the suction chamber
210 through the return passage 244 formed in the cylinder 12.
Accordingly, the fuel passage 232 downstream of the valve seat
member 87 communicates with the suction chamber 210 on the
low-pressure side through the clearance 242.
[0040] Subsequently, an operation of the high-pressure fuel pump 10
is described.
[0041] As follows, a suction stroke is described.
[0042] The plunger 40 descends, so that pressure in the compression
chamber 220 decreases in the suction stroke. In this suction
stroke, differential pressure, which is applied to the valve member
62 from the suction chamber 210 upstream of the valve member 62 and
the compression chamber 220 downstream thereof, varies.
Specifically, a seating force is applied to the valve member 62 by
fuel pressure in the compression chamber 220 in a seating
direction, in which the valve member 62 is seated on the valve seat
member 68. A lifting force is applied to the valve member 62 by
fuel pressure in the suction chamber 210 in a lifting direction, in
which the valve member is spaced from the valve seat member 68.
When the sum of the seating force applied to the valve member 62
and the bias of the spring 66 in the seating direction becomes less
than the lifting force applied on the valve member 62 in the
lifting direction, the valve member 62 is spaced from the valve
seat member 68. Thus, the valve member 62 is latched on the
attracting portion 20 of the cylinder 12. The attracting portion 20
of the cylinder 12 is provided on the opposite side of the valve
seat member 68 with respect to the valve member 62. Thereby, fuel
is drawn from the suction chamber 210 into the compression chamber
220 through the suction passage 212.
[0043] In a state, in which the valve member 62 and the attracting
portion 20 of the cylinder 12 abut against each other before the
plunger 40 reaches the bottom dead center, the coil portion 76 is
electrically turned ON. In this condition, the valve member 62 and
the cylinder 12 abut against each other, so that the magnetic
attraction force required to maintain a valve opened state, in
which the valve member 62 is latched on the attracting portion 20,
may be small in the metering valve 60.
[0044] As follows, a return stroke is described.
[0045] The magnetic attraction force acts between the attracting
portion 20 and the valve member 62, even when the plunger 40
ascends toward the top dead center from the bottom dead center in a
state, in which the coil portion 76 is electrically turned ON is
maintained. Therefore, the valve member 62 is sustained in a valve
opening position, in which it is latched on the attracting portion
20. Thereby, fuel is pressurized in the compression chamber 220 as
the plunger 40 ascends, and the fuel passes through the suction
passage 212 to return from the metering valve 60 into the suction
chamber 210.
[0046] As follows, a compression stroke is described.
[0047] When the coil portion 76 is electrically turned OFF in the
return stroke, the valve member 62 and the attracting portion 20
terminate generating the magnetic attraction force therebetween.
Consequently, the sum of the force applied on the valve member 62
by fuel pressure in the compression chamber 220 and the bias of the
spring 66 in the seating direction becomes greater than the force
applied on the valve member 62 in the lifting direction by fuel
pressure in the suction chamber 210. Consequently, the valve member
62 is seated on the valve seat member 68 by the differential
pressure, so that communication between the suction chamber 210 and
the suction passage 212 is interrupted. In this state, when the
plunger 40 ascends further toward the top dead center, fuel in the
compression chamber 220 is pressurized, so that fuel pressure
rises. When fuel pressure in the compression chamber 220 increases
to be equal to or greater than predetermined pressure, the valve
member 84 is spaced from the valve seat member 87 against the bias
of the spring 85, so that the delivery valve 80 is opened. Thereby,
fuel pressurized in the compression chamber 220 passes from the
discharge passage 230 to be discharged from the delivery valve 80
through the fuel passage 232. The fuel discharged from the delivery
valve 80 is fed to the delivery pipe 6 shown in FIG. 1 to be
accumulated therein, and is supplied into the fuel injection valves
7.
[0048] By repeating the above strokes, the high-pressure fuel pump
10 pressurizes fuel drawn thereinto to discharge the fuel. An
amount of fuel as discharged using the high-pressure fuel pump 10
is metered by controlling a period, in which the coil portion 76 of
the metering valve 60 is electrically turned ON.
[0049] The fuel passage 232 downstream of the valve seat member 87
in the delivery valve 80 communicates with the suction chamber 210
through the clearance 242. Therefore, fuel present between the
delivery valve 80 and the delivery pipe 6 regularly returns to the
suction chamber 210 on the low-pressure side through the clearance
242.
[0050] Consequently, when the fuel injection valves 7 are stopped
by fuel cut during the operation of the engine, for example, fuel
pressure downstream of the high-pressure fuel pump 10 decreases. In
this condition, fuel pressure upstream of the fuel injection valves
7 decreases. Thereby, an amount of fuel jetted from the fuel
injection valves 7 can be reduced, so that the amount of fuel
jetted from the fuel injection valves 7 can be adapted to the
operating state when the operation of the fuel injection valves 7
is restarted. Thus, engine output can be restricted from rapidly
increasing, so that a drive system of the engine can be protected
from a shock.
[0051] In addition, fuel pressure upstream of the fuel injection
valves 7 also decreases when the fuel injection valves 7 are
stopped by engine stoppage, for example. Therefore, fuel can be
restricted from leaking into a combustion chamber of the engine
through a valve portion of the fuel injection valves 7. Thereby, an
unburned fuel component, such as HC, contained in exhaust gases can
be reduced when the engine is restarted.
[0052] In the above structure, the inner peripheral surface 23 of
the mount hole 22 and the outer peripheral surface 83 of the body
82 of the delivery valve 80 are substantially circular in shape.
Therefore, the mount hole 22 and the body 82 can be easily
manufactured with high accuracy by a machining work, for example.
Accordingly, the clearance 242 formed between the mount hole 22 and
the body 82 can be adjusted with high accuracy. Thus, an amount of
fuel returning to the suction chamber 210 on the low-pressure side
through the clearance 242 can be restricted from excessively
increasing. Thereby, the high-pressure fuel pump 10 can be
restricted from increasing in discharge capacity in order to make
up for a flow rate of fuel returning to the suction chamber 210
through the clearance 242.
[0053] In addition, the clearance 242 is defined in the mount hole
22, through which the delivery valve 80 is mounted into the
cylinder 12. The delivery valve 80 is one of the functional
components of the high-pressure fuel pump 10. That is, the
clearance 242 is formed by the components necessary for the
high-pressure fuel pump 10. Therefore, machining work can be
restricted from increasing in order to introduce return fuel to the
low-pressure side, irrespective of forming the clearance 242.
Besides, the number of components can be restricted from
increasing, irrespective of forming the clearance 242.
[0054] In addition, the communication passage 240 is formed in the
body 82 of the delivery valve 80 to provide the inlet of the return
passage on the delivery valve 80. Therefore, machining work need
not be made in a downstream component such as the fuel pipe 4
and/or the delivery pipe 6 on the downstream side of the
high-pressure fuel pump 10 in order to form a return passage in
this component.
[0055] Hereupon, fuel on the downstream side of the delivery valve
80 may be introduced to a component on the low-pressure side
outside of the high-pressure fuel pump 10. In this structure,
components need to be additionally provided to form a return
passage. In addition, a sealing structure needs to be additionally
provided. Furthermore, the return passage may become lengthy.
[0056] However, in the first embodiment, return fuel flows from the
communication passage 240, which is provided in the delivery valve
80, into the suction chamber 210 inside the high-pressure fuel pump
10 after passing through the clearance 242, which is formed between
the mount hole 22 and the delivery valve 80, and the return passage
244 formed in the cylinder 12. Therefore, components constructing a
return passage and a sealing structure need not be additionally
provided. Further, the return passage constructed of the
communication passage 240 and the return passage 244 is short in
total length. Accordingly, machining work can be easily made to
form the return passage.
[0057] A clearance may be formed between the outer periphery of the
metering valve 60 and the receiving hole, in which the metering
valve 60 is accommodated in the cylinder 12. In this structure,
fuel downstream of the delivery valve 80 may be returned to the low
pressure side such as the suction chamber 210 through the clearance
between the metering valve 60 and the receiving hole of the
cylinder 12. Specifically, the clearance between the metering valve
60 and the receiving hole of the cylinder 12 may communicate the
communication passage 240 of the delivery valve 80 with the suction
chamber 210. Thus, fuel downstream of the delivery valve 80 may be
returned to the low pressure side such as the suction chamber 210
through the communication passage 240, the clearance 242, and the
clearance between the metering valve 60 and the receiving hole of
the cylinder 12. In this case, the receiving hole of the cylinder
12 serves as the mount hole.
Second Embodiment
[0058] As follows, a high-pressure fuel pump 90 in the second
embodiment is described in reference to FIGS. 5A, 5B, and 6. FIG.
5A is the view taken along the line VA-VA in FIG. 6.
[0059] As shown in FIGS. 5A, 5B, and 6, with the high-pressure fuel
pump 90 in the second embodiment, a relief valve 100 is mounted to
a mount hole 24 formed in the cylinder 12. In this construction,
the relief valve 8 (FIG. 1), which is mounted to the fuel pipe 4 on
the downstream side of the high-pressure fuel pump 90, may be
omitted. The relief valve 100 restricts abnormal rise in fuel
pressure on the downstream side of the high-pressure fuel pump 90.
The relief valve 100 serves as one of the functional components of
the high-pressure fuel pump 90.
[0060] The relief valve 100 is constructed of a body 102, a ball
104, a guide 105, a spring 106, and a valve seat member 107. The
relief valve 100 is connected to a discharge passage 250
communicated with a clearance 242. Female threads are formed on an
inner peripheral surface 25 of the mount hole 24. Male threads are
formed on an outer peripheral surface 103 of the body 102. The
female threads of the mount hole 24 and the male threads of the
body 102 are screwed to each other, so that the relief valve 100 is
mounted to the mount hole 24. A gasket 108 seals between the relief
valve 100 and the mount hole 24 on the side of the discharge
passage 250 with respect to the screwed part between the mount hole
24 and the body 102.
[0061] A fuel passage 252 communicated with a suction chamber 210
is formed in the body 102. The spring 106 biases the guide 105 and
the ball 104 in the direction, in which the ball is seated on the
valve seat member 107. Communication between the discharge passage
250 and the fuel passage 252 is interrupted when the ball 104 is
seated on the valve seat member 107. The ball 104 is spaced from
the valve seat member 107 against the bias of the spring 106 when
fuel pressure downstream of the delivery valve 80 becomes equal to
or greater than predetermined pressure. In this state, fuel in the
discharge passage 250 flows into the suction chamber 210 through
the fuel passage 252.
[0062] The valve seat member 107 is mounted to an inner peripheral
wall of an end of the body 102. A fuel passage 254 is formed to
extend axially through the valve seat member 107 to communicate
with the discharge passage 250. A communication passage 256 is
formed upstream of the location, in which the ball 104 is seated on
the valve seat member 107. That is, the communication passage 256
is formed on the side on the discharge passage 250 to extend
through the sidewall of the valve seat member 107 to communicate
with the fuel passage 254. Further, an annular passage 258 is
formed on an outer peripheral sidewall of the valve seat member 107
to communicate with the communication passage 256. A communication
passage 260 is formed to extend through the sidewall of the body
102 in a manner to communicate with the annular passage 258.
[0063] The mount hole 24 and the body 102, which are screwed to
each other, form a small clearance 262 therebetween. Specifically,
an outer peripheral surface 103 of the body 102 and an inner
peripheral surface 25 of the mount hole 24 form the small clearance
262 therebetween. The small clearance 262 extends from the screwed
part between the mount hole 24 and the body 102 to the gasket 108
through the location, in which the communication passage 260 is
formed.
[0064] The clearance 262 communicates with the communication
passage 260, thereby communicating with the fuel passage 232
downstream of the valve seat member 87 of the delivery valve 80
through the discharge passage 250 and the clearance 242 formed on
the side of the delivery valve 80. In addition, a slight clearance
is present in the screwed part, in which the mount hole 24 and the
body 102 are screwed to each other, and the clearance 262
communicates with the suction chamber 210 through the slight
clearance in the screwed part between the mount hole 24 and the
body 102. Accordingly, fuel downstream of the delivery valve 80
returns into the suction chamber 210 through the communication
passage 240, the clearance 242, the discharge passage 250, the fuel
passage 254, the communication passage 256, the annular passage
258, the communication passage 260, the clearance 262, and the
screwed part, in which the mount hole 24 and the body 102 are
screwed to each other. According to the second embodiment, the
communication passage 240, the discharge passage 250, the fuel
passage 254, the communication passage 256, the annular passage
258, and the communication passage 260 construct a return
passage.
[0065] According to the second embodiment described above, fuel
downstream of the delivery valve 80 passes through the small
clearances 242, 262 in two locations, thereby returning into the
suction chamber 210, so that an amount of fuel returning into the
suction chamber 210 can be further reduced.
Third Embodiment
[0066] As follows, a high-pressure fuel pump 110 in the third
embodiment is described in reference to FIGS. 7 to 10. FIG. 7 is
the view taken along the line VII-VII in FIG. 8.
[0067] With the high-pressure fuel pump 110 in the third
embodiment, small clearances 272, 284 are formed between outer
peripheral surfaces 125, 135 of valve seat members 124, 134 of each
of a delivery valve 120 and a relief valve 130 and inner peripheral
surfaces 23, 25 of mount holes 22, 24. The delivery valve 120 and
the relief valve 130 serve as functional components of the
high-pressure fuel pump 110. The delivery valve 120 and the relief
valve 130 are mounted to the inner peripheral surfaces 23, 25 of
mount holes 22, 24.
[0068] Specifically, as shown in FIG. 9, the valve seat member 124
of the delivery valve 120 is fitted onto an outside of an end of a
body 122 on the side of a discharge passage 230 to be coaxial with
the body 122. The delivery valve 120 defines a fuel outlet of the
high-pressure fuel pump 110. The clearance 272 formed between the
outer peripheral surface 125 of the valve seat member 124 and the
inner peripheral surface 23 of the mount hole 22 is substantially
the same with respect to the circumferential direction. A
communication passage 270 extends through the sidewall of the body
122 between the screwed part, in which the body 122 and the mount
hole 22 are screwed to each other, and the gasket 88. The
communication passage 270 communicates with a fuel passage 232
downstream of the valve seat member 124 and the clearance 272, so
that an inlet of a return passage is provided in the delivery valve
120.
[0069] The relief valve 130 restricts abnormal rise in fuel
pressure on the downstream side of the high-pressure fuel pump 110.
As shown in FIG. 10, a body 132 and a valve seat member 134 of the
relief valve 130 abut at end surfaces thereof against each other.
The body 132 is screwed to the mount hole 24, so that the valve
seat member 134 is pushed against the bottom of the mount hole
24.
[0070] The body 132 is formed with the fuel passage 252, which
communicates with the suction chamber 210. The spring 106 biases
the guide 105 and the ball 104 in the direction, in which the ball
104 is seated on the valve seat member 134. When the ball 104 is
seated on the valve seat member 134, communication between the
discharge passage 250 and the fuel passage 252 is interrupted. When
fuel pressure downstream of the delivery valve 120 attains
predetermined pressure or higher, the ball 104 is spaced from the
valve seat member 134 against the bias of the spring 106, so that
fuel in the discharge passage 250 is discharged into the suction
chamber 210 through the fuel passage 252.
[0071] The valve seat member 134 is formed with a fuel passage 280,
which extends axially therethrough to be communicated with the
discharge passage 250. A communication passage 282 is formed
upstream of the location, in which the ball 104 is seated on the
valve seat member 134. That is, the communication passage 282 is
formed on the side of the discharge passage 250 to extend through
the sidewall of the valve seat member 134 to be communicated with
the fuel passage 280. The communication passage 282 communicates
with the clearance 284.
[0072] The clearance 284 communicates with the communication
passage 282, thereby communicating with the downstream side of the
valve seat member 124 of the delivery valve 120 through the
discharge passage 250 and the clearance 272 formed on the delivery
valve 120. In addition, a slight clearance is present in the
screwed part, in which the mount hole 24 and the body 132 are
screwed to each other. The clearance 284 communicates with the
suction chamber 210 through this clearance in this screwed part
between the mount hole 24 and the body 132. Accordingly, fuel
downstream of the delivery valve 120 returns to the suction chamber
210 through the communication passage 270, the clearance 272, the
discharge passage 250, the fuel passage 280, the communication
passage 282, the clearance 284, and the screwed part, in which the
mount hole 24 and the body 132 are screwed to each other. According
to the third embodiment, the communication passage 270, the
discharge passage 250, the fuel passage 280, and the communication
passage 282 construct a return passage.
[0073] According to the third embodiment, fuel downstream of the
delivery valve 120 returns through two locations such as the
clearances 272, 284, similarly to the second embodiment. Therefore,
an amount of fuel returning to the suction chamber 210 can be
reduced.
[0074] In addition, the valve seat members 124, 134 are generally
formed of a material having high hardness as compared with the
bodies 122, 132, and the like, in order to reduce wear of seat
portions. Therefore, machining work such as grinding work can be
made in the valve seat members 124, 134 to define the outer
diameter thereof with high accuracy. Accordingly, the clearances
272, 284 formed between the valve seat members 124, 134 and the
inner peripheral surfaces 23, 25 of the mount holes 22, 24 can be
set to be further small. Thereby, an amount of fuel returning to
the suction chamber 210 can be further reduced.
Fourth Embodiment
[0075] As shown in FIG. 11, a fuel supply system according to a
fourth embodiment includes a high-pressure fuel pump 140. With this
high-pressure fuel pump 140, fuel leaking from the clearance 242
formed between the mount hole 22 and the delivery valve 80 passes
outside the high-pressure fuel pump 140 to return into the fuel
pipe 4 on the downstream side. Fuel is supplied from the fuel pump
1 into the high-pressure fuel pump 140 through the fuel pipe 4 on
the downstream side.
Fifth Embodiment
[0076] As shown in FIG. 12, with a high-pressure fuel pump 150 in
the fifth embodiment, a body 162 of a delivery valve 160 and the
cylinder 12 are formed integral with each other. The delivery valve
160 defines a fuel outlet. A ball 164 and a spring 165 are received
in the body 162. When fuel pressure in the compression chamber 220
attains predetermined pressure or higher, the ball 164 lifts
against the bias of the spring 165, so that high-pressure fuel in
the compression chamber 220 passes through the discharge passage
230 to be discharged from the delivery valve 160.
[0077] A communication passage 290 is formed in the cylinder 12. A
slide clearance 292 is formed in a sliding part, in which the
sliding portion 14 and the plunger 40 slide on each other. The
communication passage 290 communicates the slide clearance 292 with
the fuel passage 232, which is in the downstream of the ball 164 of
the delivery valve 160. According to the fifth embodiment, the
plunger 40 corresponds to one of the functional components. The
sliding portion 14 of the cylinder 12 corresponds to a mount hole,
to which the plunger 40 is mounted.
[0078] A low-pressure chamber 294 is formed between the sliding
part, in which the plunger 40 and the sliding portion 14 slide on
each other, and the oil seal 48. The low-pressure chamber 294
communicates with the suction chamber 210 through a discharge
passage 296. Fuel in the fuel passage 232 downstream of the ball
164 passes from the fuel passage 232 into the low-pressure chamber
294 through the slide clearance 292. That is, fuel upstream of the
fuel injection valves passes from the fuel passage 232 through the
slide clearance 292 to leak into the low-pressure chamber 294, and
passes through the discharge passage 296 to be returned into the
suction chamber 210. In this manner, fuel downstream of the
delivery valve 160 passes through the slide clearance 292 to return
into the low-pressure side, so that fuel pressure downstream of the
delivery valve 160 decreases, and fuel pressure upstream of the
fuel injection valves also decreases when the fuel injection valves
stop. According to the fifth embodiment, the communication passage
290, the low-pressure chamber 294, and the discharge passage 296
construct a return passage.
[0079] According to the fifth embodiment, the plunger 40 serves as
one of the functional components. Fuel downstream of the delivery
valve 160 returns to the suction chamber 210 of the high-pressure
fuel pump 150 through the slide clearance 292 formed between the
sliding portion 14 and the plunger 40. The sliding portion 14 of
the cylinder 12 serves as the mount hole for receiving the plunger
40. Thus, a clearance need not be additionally formed between the
plunger 40 and the sliding portion 14 to introduce return fuel
downstream of the delivery valve 160 into the low-pressure side.
Accordingly, machining work of the high-pressure fuel pump 150 can
be reduced.
[0080] In addition, machining works are made to highly accurately
define both the inner diameter of the sliding portion 14 and the
outer diameter of the plunger 40 in order to restrict seizure of
the sliding portion 14 with the plunger 40 and to restrict leakage
of fuel from the compression chamber 220 through the slide
clearance 292. Consequently, the slide clearance 292 is set to be
small, so that an amount of fuel passing through the slide
clearance 292 to return into the suction chamber 210 can be
reduced.
[0081] Thereby, the high-pressure fuel pump 150 can be restricted
from increasing in discharge capacity in order to make up for a
flow rate of fuel returning to the low-pressure side through the
slide clearance 292.
[0082] In FIG. 12, the length L depicts the length of the sealing
part between the communication passage 290 and the low-pressure
chamber 294. This sealing part is determined corresponding to the
location, in which the communication passage 290 and the slide
clearance 292 are communicated with each other. In this structure
of the fifth embodiment, the slide clearance 292, a passage
diameter d of the communication passage 290, and the length L of
the sealing part can be adjusted, so that pressure reduction in
fuel downstream of the delivery valve 160 can be desirably set.
That is, pressure reduction in fuel upstream of the fuel injection
valves 7 can be desirably set by adjusting the slide clearance 292,
the passage diameter d, and the length L.
Sixth Embodiment
[0083] As shown in FIG. 13, with a high-pressure fuel pump 170 in
the sixth embodiment, the communication passage 290 provides
communication between the clearance 242, which is formed between
the delivery valve 80 and the mount hole 22, and the slide
clearance 292. Accordingly, fuel downstream of the delivery valve
80 passes through the clearance 242, the communication passage 290,
the slide clearance 292, the low-pressure chamber 294, and the
discharge passage 296 to return into the suction chamber 210 on the
low-pressure side. According to the sixth embodiment, fuel
downstream of the delivery valve 80 returns to the suction chamber
210 through the clearance 242 and the slide clearance 292 in two
locations, so that it is possible to further reduce an amount of
fuel returning to the suction chamber 210.
Seventh and Eighth Embodiments
[0084] As shown in FIG. 14, with a high-pressure fuel pump 180
according to the seventh embodiment, an annular groove 185 is
formed on the outer peripheral surface of a sliding portion 184 of
a plunger 182. The plunger 182 serves as one of the functional
components, which slides on the sliding portion 14 of the cylinder
12. An annular fuel reservoir 298 is formed between a periphery of
the groove 185 and the sliding portion 14. The communication
passage 290 provides communication between the fuel passage 232
downstream of the delivery valve 160 and the fuel reservoir 298.
Fuel downstream of the delivery valve 160 passes from the fuel
passage 232 through the communication passage 290, the fuel
reservoir 298, a slide clearance 292, the low-pressure chamber 294,
and the discharge passage 296 to return into the suction chamber
210. According to the seventh embodiment, the communication passage
290, the fuel reservoir 298, the low-pressure chamber 294, and the
discharge passage 296 construct a return passage.
[0085] In the seventh embodiment, fuel downstream of the delivery
valve 160 is once accumulated in the annular fuel reservoir 298
from the communication passage 290 and then passes through the
slide clearance 292. Thereby, high-pressure fuel in the annular
fuel reservoir 298 applies fuel pressure uniformly on the entire
periphery of the sliding portion 184 of the plunger 182 even when
high-pressure fuel flows into the annular fuel reservoir 298 from
the communication passage 290 in one circumferential direction.
Accordingly, the sliding portion 184 of the plunger 182 can be
restricted from being eccentric with respect to the sliding portion
14 of the cylinder 12. Therefore, the sliding portion 184 of the
plunger 182 can be restricted from sliding on one side in the
circumferential direction. Thereby, plating or coating, which is
applied to the plunger 182 for restriction of seizure of the
sliding portion 14 with the sliding portion 184, can be protected
from abrasion, so that manufacturing cost of the plunger 182 can be
reduced.
[0086] Furthermore, the sliding portion 14 of the cylinder 12 can
be lubricated with the return fuel accumulated in the annular fuel
reservoir 298, while the plunger 182 slides on the sliding portion
14. Therefore, the sliding portion 184 of the plunger 182 can be
further restricted from causing seizure with the plunger 12.
[0087] As shown in FIG. 15, with a high-pressure fuel pump 190
according to the eighth embodiment, the communication passage 290
and the fuel reservoir 298 are communicated with each other through
the slide clearance 292 therebetween. Accordingly, fuel downstream
of the delivery valve 160 passes from the fuel passage 232 to
return into the suction chamber 210 through the communication
passage 290, the slide clearance 292, the fuel reservoir 298, the
slide clearance 292, the low-pressure chamber 294, and the
discharge passage 296.
[0088] The sliding portion 14 of the cylinder 12 can be lubricated
with the return fuel accumulated in the annular fuel reservoir 298,
thereby being further restricted from causing seizure with the
plunger 12, similarly to the eighth embodiment.
[0089] Summarizing the above embodiments, the fuel supply system
has the fuel pump that includes the pump housing, the plunger, the
delivery valve, and at least one fluid component. The pump housing
has the compression chamber and at least one mount hole. The
plunger is movable in the pump housing. The plunger is adapted to
pressurize fuel in the compression chamber. The delivery valve
communicates the compression chamber with the downstream of the
delivery valve when pressure in the compression chamber is equal to
or greater than the threshold, i.e., predetermined pressure. The at
least one fluid component is adapted to communicating the upstream
of the compression chamber with the downstream of the compression
chamber.
[0090] At least one of the plunger, the delivery valve, and the at
least one of fluid component is provided to the at least one mount
hole of the pump housing. The at least one of the plunger, the
delivery valve, and the at least one of fluid component defines at
least one clearance with respect to the at least one mount hole.
The at least one clearance communicates the downstream of the
delivery valve with the upstream of the compression chamber at
least in the condition where fuel pressure in the compression
chamber is less than the threshold.
[0091] The at least one fluid component may include at least one of
the relief valve and the metering valve. The relief valve is
adapted to restrict pressure in the downstream of the delivery
valve from rising. The metering valve 60 is arranged between the
upstream of the compression chamber and the compression chamber.
The metering valve is adapted to communicating and blocking the
upstream of the compression chamber with the compression
chamber.
Other Embodiments
[0092] According to the above embodiments, fuel downstream of the
delivery valve returns into the low-pressure side through at least
one of the small clearances. This at least one of the small
clearances is formed around at least one of the delivery valve, the
relief valve, and the plunger. However, fuel may be returned
through a clearance formed between another component, which serves
as one of the functional components of a high-pressure fuel pump,
and a mount hole. This mount hole may define a sliding part of one
of the functional components. In addition, a clearance, through
which fuel passes, formed between that functional component and a
mount hole is not limited to one or two locations. Clearances may
be provided in at least three locations for introducing fuel.
[0093] In addition, according to the above embodiments, the
cylinder supports the plunger to permit reciprocation thereof, and
the at least one of the functional components such as the piping
joint 50, the delivery valve, the relief valve are mounted directly
to the cylinder. However, the cylinder supporting the plunger and
the housing body, to which the functional components are mounted,
may be separate from each other.
[0094] Furthermore, the respective embodiments have been described
with respect to an example, in which the high-pressure fuel pump is
applied to a high-pressure fuel pump of a direct injection type
gasoline supply system. However, the high-pressure fuel pump is not
limited to those in the above embodiments, and may be applied to a
fuel supply system for diesel engines, for example.
[0095] The above structures of the embodiments can be combined as
appropriate. For example, the structures of the fuel reservoir
described in the seventh and eighth embodiments may be combined
with the structures of any one of the first to fourth
embodiments.
[0096] Various modifications and alternations may be diversely made
to the above embodiments without departing from the spirit of the
present invention.
* * * * *