U.S. patent application number 12/299231 was filed with the patent office on 2009-07-23 for fuel supply pump.
Invention is credited to Koji Hatanaka, Masatsugu Hayashida, Sakae Sato.
Application Number | 20090185923 12/299231 |
Document ID | / |
Family ID | 38667664 |
Filed Date | 2009-07-23 |
United States Patent
Application |
20090185923 |
Kind Code |
A1 |
Sato; Sakae ; et
al. |
July 23, 2009 |
FUEL SUPPLY PUMP
Abstract
The invention provides fuel supply pump that can improve the
durability of a fuel inlet valve and stably pressure-feed high
pressure fuel of a large flow rate. In the fuel inlet valve
according to the invention, a valve piston includes, in its outer
surface in the vicinity of an end portion on an opposite side of a
collar portion, a groove portion to which a fastener for fixing the
valve piston and a spring seat locks. The spring seat includes an
open portion into which the valve piston is inserted and includes,
along an edge of the open portion, a step portion to which the
fastener locks. The valve piston is inserted into the open portion
of the spring seat, and the fastener is thereafter caused to lock
to the groove portion of the valve piston. The spring seat is
energized by a spring to cause the fastener to lock to the step
portion, whereby the spring seat is fixed to the valve piston. A
clearance is disposed between the fastener and at least one of an
edge portion of the groove portion on an energizing direction side
and an edge portion of the step portion on the opposite side of the
energizing direction.
Inventors: |
Sato; Sakae; (Saitama,
JP) ; Hayashida; Masatsugu; (Saitama, JP) ;
Hatanaka; Koji; (Saitama, JP) |
Correspondence
Address: |
RONALD E. GREIGG;GREIGG & GREIGG P.L.L.C.
1423 POWHATAN STREET, UNIT ONE
ALEXANDRIA
VA
22314
US
|
Family ID: |
38667664 |
Appl. No.: |
12/299231 |
Filed: |
April 23, 2007 |
PCT Filed: |
April 23, 2007 |
PCT NO: |
PCT/JP2007/058697 |
371 Date: |
October 31, 2008 |
Current U.S.
Class: |
417/545 |
Current CPC
Class: |
F01L 3/10 20130101; F04B
1/0452 20130101; F02M 59/102 20130101; F04B 53/1032 20130101; F02M
59/464 20130101 |
Class at
Publication: |
417/545 |
International
Class: |
F04B 53/12 20060101
F04B053/12 |
Foreign Application Data
Date |
Code |
Application Number |
May 1, 2006 |
JP |
2006-127448 |
Claims
1-6. (canceled)
7. A fuel supply pump comprising a fuel pressurization chamber for
pressurizing fuel to a high pressure and a fuel inlet valve for
supplying fuel to the fuel pressurization chamber, wherein the fuel
inlet valve is disposed with a valve body, a valve piston that
includes a collar portion on one end side and is slidably held in
the valve body, a spring that energizes the valve piston in a valve
closing direction, and a spring seat that is fixed in the vicinity
of an end portion of the valve piston on an opposite side of the
one end side and which receives one end of the spring, the valve
piston includes, in its outer surface in the vicinity of the end
portion on the opposite side, a groove portion to which a fastener
for fixing the valve piston and the spring seat locks, the spring
seat includes an open portion into which the valve piston is
inserted and includes, along an edge of the open portion, a step
portion to which the fastener locks, the valve piston is inserted
into the open portion of the spring seat, the fastener is
thereafter caused to lock to the groove portion of the valve
piston, and the spring seat is energized by the spring to cause the
fastener to lock to the step portion, whereby the spring seat is
fixed to the valve piston, and a clearance is disposed between the
fastener and at least one of an edge portion of the groove portion
on an energizing direction side and an edge portion of the step
portion on an opposite side of the energizing direction.
8. The fuel supply pump of claim 7, wherein the groove portion or
the step portion has a cross-sectional shape of a circular are, and
the clearance is disposed by offsetting a center of a circle that
draws the circular arc from an outer surface position of the valve
piston.
9. The fuel supply pump of claim 7, wherein a frictional force
generating member is intervened between the groove portion and the
fastener or the step portion and the fastener.
10. The fuel supply pump of claim 8, wherein a frictional force
generating member is intervened between the groove portion and the
fastener or the step portion and the fastener.
11. The fuel supply pump of claim 7, wherein the fastener is a
C-ring that comprises an alloy that has high elasticity.
12. The fuel supply pump of claim 7, wherein the valve piston and
the spring seat are made of carburized steel or bearing steel.
13. A fuel supply pump comprising a fuel pressurization chamber for
pressurizing fuel to a high pressure and a fuel inlet valve for
supplying fuel to the fuel pressurization chamber, wherein the fuel
inlet valve is disposed with a valve body, a valve piston that
includes a collar portion on one end side and is slidably held in
the valve body, a spring that energizes the valve piston in a valve
closing direction, and a spring seat that is fixed in the vicinity
of an end portion of the valve piston on an opposite side of the
one end side and which receives one end of the spring, the valve
piston includes, in its outer surface in the vicinity of the end
portion on the opposite side, a groove portion to which a fastener
for fixing the valve piston and the spring seat locks, the spring
seat includes an open portion into which the valve piston is
inserted and includes, along an edge of the open portion, a step
portion to which the fastener locks, the valve piston is inserted
into the open portion of the spring seat, the fastener is
thereafter caused to lock to the groove portion of the valve
piston, and the spring seat is energized by the spring to cause the
fastener to lock to the step portion, whereby the spring seat is
fixed to the valve piston, and a contact portion between the groove
portion and the fastener and a contact portion between the step
portion and the fastener are connected in a diagonal direction with
respect to an energizing direction.
Description
TECHNICAL FIELD
[0001] The present invention relates to a fuel supply pump that is
disposed with a fuel inlet valve and particularly to a fuel supply
pump that is suited for pressure-feeding high pressure fuel of a
large flow rate.
[0002] Conventionally, in diesel engines and the like, various
accumulator fuel injection devices (CRS: Common Rail Systems) that
use a pressure accumulator (common rail) in order to efficiently
inject high pressure fuel have been proposed.
[0003] FIG. 13 shows an example of a fuel supply pump that is used
in such accumulator fuel injection system. This fuel supply pump
410 is disposed with a cam 429 in a pump housing 421 and includes a
cylindrical space 421a in which a plunger barrel 415 is attached
above the cam 429, with a fuel inlet valve 422 being attached to an
upper open portion of the plunger barrel 415 that is attached in
this cylindrical space 421a. Further, inside the plunger barrel
415, a fuel pressurization chamber 425 that is closed off by a
plunger 423 and the fuel inlet valve 422 is formed, and a fuel
passage 431 that is connected to a fuel outlet valve 428 is
disposed in the portion that faces the fuel pressurization chamber
425. In this fuel supply pump 410, fuel that has been supplied to
the fuel pressurization chamber 425 via the fuel inlet valve 422 is
pressurized by the plunger 423 that reciprocally moves in
accompaniment with the rotation of the cam 429 and is pressure-fed
with respect to a common rail via the fuel outlet valve 428.
[0004] Here, the fuel inlet valve 422 that is used in the fuel
supply pump is disposed with a valve body 433, a valve piston 435
that includes a collar portion 436 on one end and is slidably held
in the valve body 433, a spring 441 that energizes the valve piston
435 in a valve closing direction, and a spring seat 437 that is
fixed in the vicinity of an end portion of the valve piston 435 on
the opposite side of the end portion where the collar portion 436
is disposed and which receives one end of the spring 441 (see
Patent Document 1). Fuel is supplied to a fuel reservoir portion
433a via a fuel inlet hole, the fuel inlet valve 422 is opened when
the difference between the pressure inside the fuel pressurization
chamber 425 and the pressure inside the fuel reservoir portion 433a
exceeds a predetermined pressure value, and the fuel is supplied to
the inside of the fuel pressurization chamber 425. Meanwhile, the
pressure inside the fuel pressurization chamber 425 rises in
accompaniment with the rising of the plunger 423 and the pressure
inside the fuel reservoir portion 433a drops, whereby the valve
piston 435 is seated on a seat portion of the valve body 433 and
the fuel inlet valve 422 is closed.
Patent Document 1: JP-A-2004-211580 (FIG. 1, FIG. 13)
DISCLOSURE OF THE INVENTION
Problem that the Invention is to Solve
[0005] However, in the fuel inlet valve that is used in the fuel
supply pump disclosed in Patent Document 1, the valve piston and
the spring seat are configured as separate bodies for assembly
reasons. Additionally, this fuel inlet valve usually has a size of
about 3 to 4 cm, so when the valve piston and the spring seat are
to be fixed, laser welding is employed as an easy fixing method.
Consequently, it is necessary to select a material that is easy to
weld as the material of the valve piston, and it has been difficult
to employ a relatively high-strength material such as high-carbon
steel. As a result, there has been the potential for the portion of
the valve piston that is seated in the valve body to easily wear
and for its durability to become poor. In particular, when,
beginning with accumulator fuel injection devices, the fuel supply
pump is rotated at a high speed in order to pressure-feed even
higher pressure fuel in a large amount, there has been the
potential for the durability of the valve piston to drop
excessively and for the valve piston to become unable to stably
pressurize the fuel.
[0006] Thus, as a result of their extensive investigations, the
inventors of the present Invention have discovered that this
problem can be solved by employing a mechanical fixing method that
uses a predetermined fastener rather than welding as the method of
fixing the valve piston and the spring seat and giving the place of
the valve piston or the spring seat to which the fastener locks a
predetermined structure.
[0007] That is, it is an object of the present invention to provide
a fuel supply pump where, even when the fuel supply pump is driven
at a high speed to pressure-feed high pressure fuel of a large flow
rate, it is difficult for the fuel inlet valve to sustain damage
and whose durability is improved.
Means for Solving the Problem
[0008] According to the present invention, there is provided a fuel
supply pump comprising a fuel pressurization chamber for
pressurizing fuel to a high pressure and a fuel inlet valve for
supplying fuel to the fuel pressurization chamber, wherein the fuel
inlet valve is disposed with a valve body, a valve piston that
includes a collar portion on one end side and is slidably held in
the valve body, a spring that energizes the valve piston in a valve
closing direction, and a spring seat that is fixed in the vicinity
of an end portion of the valve piston on the opposite side of the
one end side and which receives one end of the spring, the valve
piston includes, in its outer surface in the vicinity of the end
portion on the opposite side, a groove portion to which a fastener
for fixing the valve piston and the spring seat locks, the spring
seat includes an open portion into which the valve piston is
inserted and includes, along an edge of the open portion, a step
portion to which the fastener locks, the valve piston is inserted
into the open portion of the spring seat, the fastener is
thereafter caused to lock to the groove portion of the valve
piston, and the spring seat is energized by the spring to cause the
fastener to lock to the step portion, whereby the spring seat is
fixed to the valve piston, and a clearance is disposed between the
fastener and at least one of an edge portion of the groove portion
on the energizing direction side and an edge portion of the step
portion on the opposite side of the energizing direction, and the
aforementioned problem can be solved.
[0009] Further, in configuring the fuel supply pump of the present
invention, it is preferable for the cross-sectional shape of the
groove portion or the step portion to be a circular arc shape and
for the clearance to be disposed by offsetting the center of a
circle that draws the circular arc from an outer surface position
of the valve piston.
[0010] Below, in the present specification, "outer surface position
of the valve piston" means a surface position on the
circumferential direction outer side with respect to the axial line
of the valve piston and a surface position that exists when it is
assumed that that surface position on the circumferential direction
outer side extends.
[0011] Further, in configuring the fuel supply pump of the present
invention, it is preferable for a frictional force generating
member to be intervened between the groove portion or the step
portion and the fastener.
[0012] Further, in configuring the fuel supply pump of the present
invention, it is preferable for the fastener to be a C-ring that
comprises an alloy that has high elasticity.
[0013] Further, in configuring the fuel supply pump of the present
invention, it is preferable for the valve piston and the spring
seat to comprise carburized steel or bearing steel.
[0014] Further, another aspect of the present invention is a fuel
supply pump comprising a fuel pressurization chamber for
pressurizing fuel to a high pressure and a fuel inlet valve for
supplying fuel to the fuel pressurization chamber, wherein the fuel
inlet valve is disposed with a valve body, a valve piston that
includes a collar portion on one end side and is slidably held in
the valve body, a spring that energizes the valve piston in a valve
closing direction, and a spring seat that is fixed in the vicinity
of an end portion of the valve piston on the opposite side of the
one end side and which receives one end of the spring, the valve
piston includes, in its outer surface in the vicinity of the end
portion on the opposite side, a groove portion to which a fastener
for fixing the valve piston and the spring seat locks, the spring
seat includes an open portion into which the valve piston is
inserted and includes, along an edge of the open portion, a step
portion to which the fastener locks, the valve piston is inserted
into the open portion of the spring seat, the fastener is
thereafter caused to lock to the groove portion of the valve
piston, and the spring seat is energized by the spring to cause the
fastener to lock to the step portion, whereby the spring seat is
fixed to the valve piston, and a contact portion between the groove
portion and the fastener and a contact portion between the step
portion and the fastener are connected in a diagonal direction with
respect to the energizing direction.
EFFECTS OF THE INVENTION
[0015] According to the fuel supply pump of the present invention,
the valve piston and the spring seat are fixed by a mechanical
fixing method that uses a predetermined fastener, so the degree of
freedom of selecting the material that configures the valve piston
expands, and a high-strength material that is not suited for
welding can be selected. Consequently, the strength of the valve
piston is raised and wear of the portion that is seated with
respect to the valve body can be reduced.
[0016] Further, the fastener and at least one of the groove portion
of the valve piston and the step portion of the spring seat to
which the fastener locks are placed in a predetermined state of
contact, so a situation where shear force acts on the fastener due
to the downward pushing force of the valve piston resulting from
fuel pressure and the energizing force of the spring can be
controlled, and a situation where the fastener sustains damage can
be prevented.
[0017] Consequently, the durability of the fuel inlet valve
improves, so even when the pump is caused to rotate at a high speed
and is used, the fuel supply pump can stably pressure-feed high
pressure fuel of a large flow rate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 A side diagram including a partial cutout of a fuel
supply pump pertaining to an embodiment of the present
invention.
[0019] FIG. 2 A cross-sectional diagram of the fuel supply pump
pertaining to the embodiment of the present invention.
[0020] FIG. 3 Cross-sectional diagrams of a fuel inlet valve that
is disposed in the fuel supply pump.
[0021] FIG. 4 Diagrams provided for describing parts that configure
the fuel inlet valve.
[0022] FIG. 5 Diagrams provided for describing a method of
assembling the fuel inlet valve.
[0023] FIG. 6 A diagram provided for describing the directions of
forces that act on a fastener.
[0024] FIG. 7 Diagrams provided for describing other configuration
examples of the fuel inlet valve.
[0025] FIG. 8 Diagrams provided for describing a groove portion of
a valve piston and a step portion of a spring seat that have
circular arc-shaped cross sections.
[0026] FIG. 9 A diagram provided for describing a groove portion of
a valve piston and a step portion of a spring seat that have linear
cross sections.
[0027] FIG. 10 A diagram provided for describing the configuration
of the fuel inlet valve in which a frictional force generating
member is intervened.
[0028] FIG. 11 A diagram provided for describing an accumulator
fuel injection system with a pressure amplifying piston
(APCRS).
[0029] FIG. 12 A diagram conceptually showing a fuel pressure
amplification method resulting from the accumulator fuel injection
system with a pressure amplifying piston (APCRS).
[0030] FIG. 13 A diagram provided for describing the structure of a
conventional fuel supply pump.
BEST MODE FOR IMPLEMENTING THE INVENTION
[0031] Below, an embodiment relating to a fuel supply pump of the
present invention will be specifically described with reference to
the drawings. However, this embodiment represents one aspect of the
present invention, is not intended to limit this invention, and is
capable of being arbitrarily altered within the scope of the
present invention.
[0032] It will be noted that, in each of the drawings, members to
which identical reference numerals have been added represent
identical members, and description will be appropriately
omitted.
[0033] The embodiment of the present invention is a fuel supply
pump that comprises a fuel pressurization chamber for pressurizing
fuel to a high pressure and a fuel inlet valve for supplying fuel
to the fuel pressurization chamber.
[0034] In the fuel supply pump of the present embodiment, the fuel
inlet valve is disposed with a valve body, a valve piston that
includes a collar portion on one end side and is slidably held in
the valve body, a spring that energizes the valve piston in a valve
closing direction, and a spring seat that is fixed in the vicinity
of an end portion of the valve piston on the opposite side of the
one end side where the collar portion is disposed and which
receives one end of the spring, the valve piston includes, in its
outer surface in the vicinity of the end portion on the opposite
side, a groove portion to which a fastener for fixing the valve
piston and the spring seat locks, the spring seat includes an open
portion into which the valve piston is inserted and includes, along
the edge of the open portion, a step portion to which the fastener
locks, the valve piston is inserted into the open portion of the
spring seat, the fastener is thereafter caused to lock to the
groove portion of the valve piston, and the spring seat is
energized by the spring to cause the fastener to lock to the step
portion, whereby the spring seat is fixed to the valve piston, and
a clearance is disposed between the fastener and at least one of an
edge portion of the groove portion on the energizing direction side
and an edge portion of the step portion on the opposite side of the
energizing direction.
[0035] Below, the fuel supply pump of the present embodiment will
be divided into its respective members and specifically
described.
1. Overall Configuration
[0036] The overall configuration of the fuel supply pump of the
present invention is not particularly limited, and one example
thereof is shown in FIG. 1. This fuel supply pump 1 is a so-called
line-type pump where cylinders (cylindrical spaces) 11b and 11c in
which plungers 13 that pressurize fuel are disposed are disposed in
parallel, and the fuel supply pump 1 is disposed with a pump body
portion 10 that pressurizes fuel to a high pressure and
pressure-feeds the fuel, a feed pump 3 for sucking up fuel from a
fuel tank (not shown), and a control valve 5 for regulating the
flow rate of the fuel that is to be pressurized.
[0037] It will be noted that the example of this fuel supply pump 1
has a configuration that uses the two plungers 13 to pressurize
fuel to a high pressure and pressure-feed the fuel, but the number
of the plungers can also be increased to an even greater number in
order to pressurize an even larger amount of fuel to a high
pressure.
2. Feed Pump
[0038] The feed pump 3 is a part for sucking up the fuel inside the
fuel tank and delivering the fuel with respect to the control valve
5. This feed pump 3 comprises a gear pump structure that includes a
drive gear that is coupled to an end portion of a cam shaft 23 and
a passive gear that is coupled to the drive gear, for example, and
the feed pump 3 is driven directly or via an appropriate gear ratio
with the cam shaft 23. This feed pump 3 is driven, whereby the fuel
is sucked up from the fuel tank and delivered with respect to the
control valve 5 utilizing negative pressure.
[0039] Further, when a prefilter (not shown) is intervened between
the feed pump 3 and the fuel tank and foreign particles are mixed
in with the fuel inside the fuel tank, those foreign particles can
be primarily trapped such that they do not flow into the inside of
the fuel supply pump 1.
3. Control Valve
[0040] The control valve 5 is attached to the pump body portion 10
and is a part which, when delivering the fuel that has been
delivered from the feed pump 3 to fuel pressurization chambers 14
of the pump body portion 10, regulates the amount of that fuel.
This control valve 5 can be given a configuration that uses a
proportional control valve, for example. Because of this control
valve 5, the amount of fuel can be regulated in correspondence to
the fuel pressure that internal combustion requires, and the fuel
can be sent to the fuel pressurization chambers 14 of the pump body
portion 10.
4. Overflow Valve
[0041] Further, although it is not illustrated, the fuel supply
pump is disposed with an overflow valve that branches from the
middle of a fuel passage that interconnects the feed pump and the
control valve and is disposed in parallel with the control valve.
Because of this overflow valve, when the pressure of the fuel that
is delivered to the control valve exceeds a stipulated value or
when the flow rate of the fuel that is delivered to the control
valve exceeds a stipulated amount, the fuel can be refluxed to the
fuel tank or the like via the overflow valve.
[0042] At this time, fuel flowing to the overflow valve side can
also be delivered to the inside of a later-described cam chamber of
the pump body portion and be used as a lubricant. Thus, the fuel
can be effectively utilized without having to separately supply
lubricating oil or the like as a lubricant inside the cam chamber,
and an increase in the size of the entire fuel supply pump and an
increase in the complexity of its configuration can be
prevented.
5. Pump Body Portion
(1) Basic Configuration
[0043] The pump body portion 10 is a part for pressurizing the fuel
that is delivered via the control valve 5 to a high pressure and
pressure-feeding the fuel to a common rail and the like on the
downstream side.
[0044] Here, FIG. 2 shows a cross-sectional diagram when an XX
cross section of the fuel supply pump 1 of FIG. 1 is seen from the
direction of the arrows. As shown in this FIG. 2, the pump body
portion 10 is, for example, disposed with a pump housing 11, a
plunger barrel 12 that is attached inside the cylindrical space 11b
of the pump housing 11, the plunger 13 that is slidingly held in an
inner space 12a of the plunger barrel 12, a spring seat 19 that is
locked to an end portion of the plunger 13, a spring 15 whose both
ends are locked to the plunger barrel 12 and the spring seat 19 and
which is for energizing the plunger 13 downward, and a tappet
structure body 18 that is intervened between the plunger 13 and a
cam 21 and is for centering and pushing up the plunger 13 in
accompaniment with the rotation of the cam 21. Further, a fuel
inlet valve 20 is disposed in an upper open portion of the inner
space 12a of the plunger barrel 12, and a fuel outlet valve 22 is
disposed via a fuel passage 12b that extends sideways from the
inner space 12a of the plunger barrel 12.
[0045] Further, part of the inner space 12a of the plunger barrel
12 forms the fuel pressurization chamber 14 that is closed off by
the inner peripheral surface of the plunger barrel 12, the plunger
13 and the fuel inlet valve 20. Additionally, fuel that is supplied
via the fuel inlet valve 20 is pressurized to a high pressure
inside this fuel pressurization chamber 14 by the plunger 13 that
is pushed up in accompaniment with the rotational movement of the
cam 21 and is pressure-fed to the common rail and the like on the
downstream side via the fuel outlet valve 22.
(2) Pump Housing
[0046] The pump housing 11 is a casing to which the plunger barrel
12 is attached and in which the plunger 13, the tappet structure
body 18 and the cam 21 are housed. This pump housing 11 can, for
example, be given a configuration that is disposed with a cam
chamber 11a and the cylindrical space 11b that opens above the cam
chamber 11a and in which the plunger barrel 12 is attached.
[0047] It will be noted that the configuration of the pump housing
beginning with the number of the cylindrical spaces can be
appropriately altered in correspondence to the type of the fuel
supply pump.
(3) Plunger Barrel
[0048] The plunger barrel 12 is a casing that is attached in the
cylindrical space 11b of the pump housing 11, slidably holds the
plunger 13 in its inner space 12a, and where the fuel inlet valve
20 is disposed in the upper open portion of the inner space 12a.
Further, the inner space 12a of the plunger barrel 12 becomes an
element that configures the fuel pressurization chamber 14 for
pressurizing fuel to a high pressure together with the plunger 13
and the fuel inlet valve 20.
[0049] It will be noted that when the type of the fuel supply pump
is an inline type or a radial type, the configuration of the
plunger barrel can be appropriately altered in correspondence to
the respective types.
(4) Plunger
[0050] The plunger 13 is slidably held in the inner space 12a of
the plunger barrel 12, is pushed up in accompaniment with the
rotation of the cam 21, and is a part for pressurizing the fuel
inside the fuel pressurization chamber 14 to a high pressure.
Further, the spring seat 19, which receives one end of the spring
15 and pulls down the plunger 13 toward the cam 21 side by the
energizing force of the spring 15, is locked to an end portion of
the plunger 13. Additionally, the plunger 13 is held such that it
may freely rise and fall by downward force resulting from the
energizing force of the spring 15 and by rising force accompanying
the rotation of the cam 21.
(5) Fuel Pressurization Chamber
[0051] The fuel pressurization chamber 14 is a small chamber that
is closed off and formed by the plunger 13 and the fuel inlet valve
20 in the inner space 12a of the plunger barrel 12. In this fuel
pressurization chamber 14, fuel that flows in via the fuel inlet
valve 20 can be pressurized efficiently and in a large amount as a
result of the plunger 13 being driven at a high speed. Further, the
fuel that has been pressurized by the plunger 13 is supplied to the
common rail and the like via the fuel outlet valve 22.
(6) Cam
[0052] The cam 21 is disposed with one or several cam mountains and
is a main element for causing the plunger 13 to rise via the tappet
structure body 18 in accompaniment with the rotation of the cam
shaft 23. This cam 21 attaches and is fixed to the cam shaft 23
that continues into a diesel engine inside the cam chamber 11a.
Additionally, the cam shaft 23 is coupled via a gear to a
crankshaft of the engine and is configured such that the cam 21
rotates by the driving of the engine.
[0053] This cam 21 is positioned below the cylindrical space 11b of
the pump housing 11 and is disposed in parallel with a
predetermined clearance in an axial line direction of the cam shaft
23.
(7) Tappet Structure Body
[0054] The tappet structure body 18 is intervened between the
plunger 13 and the cam 21 and is a member for causing the plunger
13 to move up and down while performing centering of the plunger 13
in correspondence to the rotation of the cam 21 that accompanies
the rotation of the cam shaft 23. The configuration of this tappet
structure body 18 is not particularly limited; for example, the
tappet structure body 18 shown in FIG. 2 is configured by the
spring seat 19, a tappet body portion 16 that comprises a roller
holding portion 16b and a sliding portion 16a, and a roller 17. In
addition, for example, a tappet that does not include a roller can
also be used.
(8) Fuel Inlet Valve
[0055] The fuel inlet valve 20 is disposed in the upper open
portion of the inner space 12a that is disposed in the plunger
barrel 12 and is a part for supplying the fuel delivered via the
control valve to the fuel pressurization chamber 14.
[0056] FIG. 3(a) shows an enlarged cross-sectional diagram of the
periphery (the portion indicated by A in FIG. 2) of the fuel inlet
valve 20 in the fuel supply pump 1 of the present embodiment, and
FIG. 3(b) shows an enlarged cross-sectional diagram of the portion
indicated by B in FIG. 3(a).
[0057] The fuel inlet valve 20 shown in this FIG. 3(a) is disposed
with a holder portion 31, a valve body 33, a valve piston 35 that
includes a collar portion 35a on one end side and is slidably held
in the valve body 33, a spring 41 that energizes the valve piston
35 in a valve closing direction, and a spring seat 37 that is fixed
in the vicinity of an end portion of the valve piston 35 on the
opposite side of the end portion where the collar portion 35a is
disposed and which receives one end of the spring 41. Further, a
seal ring groove 45 is disposed in the outer peripheral surface of
the holder portion 31, and sealing between the holder portion 31
and the pump housing 11 is ensured by a seal ring 43 that is
disposed inside this seal ring groove 45. Further, the inside of a
space portion 31a of the holder portion 31 is filled with fuel that
serves as a lubricant for ensuring lubricity of the sliding surface
of the valve piston 35, and a plug 47 is press-inserted from above
the space portion 31a into the space portion 31a to contain the
lubricating fuel. Moreover, a clearance 49 that serves as a passage
for fuel that flows into an inlet path 33b of the valve body 33 is
disposed between the valve body 33 and the pump housing 11 in the
outer peripheral direction (sideways in the drawing) of the valve
body 33. Because of this clearance 49, it becomes possible to suck
in fuel from the inlet path 33b that is radially disposed in the
valve body 33.
[0058] In this fuel inlet valve 20, the valve piston 35 is always
energized in the valve closing direction by the spring 41.
Additionally, fuel that is delivered via the control valve passes
through the clearance 49 and the radially formed inlet path 33b and
flows into a fuel reservoir chamber 33a, and when the difference
between the pressure inside the fuel pressurization chamber 14 and
the pressure inside the fuel reservoir chamber 33a exceeds a
predetermined pressure value, the fuel inlet valve 20 is opened and
the fuel is supplied to the inside of the fuel pressurization
chamber 14. Thereafter, when the pressure inside the fuel reservoir
chamber 33a drops and the fuel inside the fuel pressurization
chamber 14 rises in accompaniment with the rising of the plunger 13
inside the fuel pressurization chamber 14, the fuel inlet valve 20
is again closed by the energizing force of the spring 41.
[0059] At this time, the fuel inside the fuel reservoir chamber 33a
of the valve body 33 or inside the space portion 31a of the holder
portion 31 enters the sliding surface of the valve piston 35 that
is slidably held in the valve body 33, lubricity is ensured, and
burning is prevented.
[0060] Here, as shown in FIG. 3 (b), the fuel inlet valve in the
fuel supply pump of the present invention is characterized in that
the valve piston 35 includes, in its circumferential direction
outer surface in the vicinity of the end portion on the opposite
side of the collar portion, a groove portion 51 to which a fastener
40 for fixing the valve piston 35 and the spring seat 37 locks, the
spring seat 37 includes an open portion 37a into which the valve
piston 35 is inserted or press-inserted and includes, along the
edge of the open portion 37a, a step portion 53 to which the
fastener 40 locks, the valve piston 35 is inserted or
press-inserted into the open portion 37a of the spring seat 37, the
fastener 40 is thereafter caused to lock to the groove portion 51
of the valve piston 35, and the spring seat 37 is energized by the
spring 41 to cause the fastener 40 to lock to the step portion 53,
whereby the spring seat 37 is fixed to the valve piston 35, and a
clearance S is disposed between the fastener 40 and at least one of
an edge portion 51a of the groove portion 51 on the energizing
direction side and an edge portion 53a of the step portion 53 on
the opposite side of the energizing direction.
[0061] More specifically, in the conventional fuel inlet valve, as
shown in FIG. 13, the valve piston 435 and the spring seat 437 have
been fixed by laser welding, so carburized steel or bearing steel
whose Joining strength resulting from welding is low could not be
used as the material of the valve piston 435. For that reason, the
wear resistance of the valve piston 435 has been relatively low,
and as the pump is caused to rotate at a high speed and the fuel
pressure becomes a high pressure, there has been the potential for
the portion that contacts the seat portion of the valve body 433 to
easily wear and for its durability to be poor. Further, carburized
steel or the like could not be used for the spring seat 437 either,
and it has been necessary to intervene a high-hardness shim (not
shown) in order to protect the receiving surface of the spring 441
from damage.
[0062] For that reason, the fuel inlet valve that is used in the
fuel supply pump of the present invention employs, as shown in FIG.
3(b), a fixing method that uses the predetermined fastener 40 as
the method of fixing the valve piston 35 and the spring seat 37 in
the fuel inlet valve 20. Consequently, the valve piston 35 and the
spring seat 37 can be configured using a material such as
carburized steel or bearing steel that deforms relatively
difficultly. Thus, the strength of the valve piston 35 is raised,
and even when the pump is caused to rotate at a high speed and the
fuel pressure becomes a high pressure, the fuel can be stably
pressure-fed. Further, the strength of the spring seat 37 is also
raised, and it becomes possible for the one end of the spring 41 to
be directly received by the spring seat 37, so it becomes
unnecessary to intervene a shim or the like and the number of parts
can be reduced.
[0063] The fuel inlet valve 20 shown in FIG. 3(a) to (b) is
assembled using the spring seat 37, a C-ring 40A that serves as the
fastener 40, the valve body 33 and the valve piston 35, which are
respectively shown in FIG. 4(a) to (d).
[0064] That is, first, as shown in FIG. 5(a), the valve piston 35
is inserted into the valve body 33, and the spring 41 is disposed
on the upper surface of the valve body 33. Next, as shown in FIG.
5(b), the valve piston 35 is inserted or press-inserted into the
inside of the open portion 37a of the spring seat 37 such that the
spring 41 is pushed and compressed. In this state, as shown in FIG.
5(c), the C-ring 40A is caused to lock to the groove portion 51 of
the valve piston 35 and, thereafter, as shown in FIG. 5(d), the
spring seat 37 is energized by the spring 41 such that the C-ring
40A is caused to lock to the step portion 53 of the spring seat 37.
Assembled in this manner, the spring seat 37 is fixed to the valve
piston 35.
[0065] However, when this fixing method is employed, the energizing
force of the spring and the downward pushing force of the valve
piston resulting from the fuel pressure inside the fuel reservoir
chamber push the spring seat and the valve piston in mutually
opposite directions, so it becomes easy for shear force resulting
from the edge of the groove portion of the valve piston and the
edge of the step portion of the spring seat to work on the fastener
that respectively locks to the groove portion of the valve piston
and the step portion of the spring seat.
[0066] Thus, in the present invention, as shown in FIG. 3(b), the
clearance S is disposed between the fastener 40 and at least one of
the edge portion 51a of the groove portion 51 of the valve piston
35 on the energizing direction side of the spring 41 (the opposite
side of the collar portion of the valve piston 35) and the edge
portion 53a of the step portion 53 of the spring seat 37 on the
opposite side of the energizing direction of the spring 41 (the
collar portion side of the valve piston 35), whereby shear force
that acts on the fastener 40 is reduced and damage to the fastener
40 is prevented.
[0067] In other words, a contact portion P1 between the groove
portion 51 of the valve piston 35 and the fastener 40 and a contact
portion P2 between the step portion 53 of the spring seat 37 and
the fastener 40 are configured such that they are connected in a
diagonal direction with respect to the energizing direction of the
spring 41.
[0068] For example, in the fuel inlet valve shown in FIG. 3 (b),
the clearance S is respectively disposed between the fastener 40
and the edge portion 51a of the groove portion 51 of the valve
piston 35 on the energizing direction side of the spring 41 (the
upper side in the drawing) and between the fastener 40 and the edge
portion 53a of the step portion 53 of the spring seat 37 on the
opposite side of the energizing direction of the spring 41 (the
lower side in the drawing). Thus, as shown in FIG. 6, the force
that acts on the fastener 40 from the spring seat 37 resulting from
the energizing force of the spring 41 and the force that acts on
the fastener 40 from the valve piston 35 by the downward pushing
force of the valve piston 35 resulting from the fuel pressure
inside the fuel reservoir chamber act in diagonal directions, and
the forces that act on the fastener 40 are changed from a shearing
direction to a compressing direction. Additionally, usually, if
they are the same material, the allowable compressive stress is
higher than the allowable shear stress, so the durability of the
fastener 40 becomes improved.
[0069] In this manner, in order to reduce shear force that acts on
the fastener, it is alright even if the clearance is disposed only
between the fastener and the edge portion of the groove portion of
the valve piston on the energizing direction side of the spring or
between the fastener and the edge portion of the step portion of
the spring seat on the opposite side in the energizing direction of
the spring.
[0070] For example, FIG. 7 (a) is an example where the clearance S
is disposed only between the fastener 40 and the edge portion 51a
of the groove portion 51 of the valve piston 35 on the energizing
direction side of the spring 41 (the upper side in the drawing). By
configuring the fuel inlet valve in this manner also, the force
that acts on the fastener 40 from the spring seat 37 and the force
that acts on the fastener 40 from the valve piston 35 can be caused
to act in diagonal directions. Consequently, the forces that act on
the fastener 40 are changed from a shearing direction to a
compressing direction, shear force that acts on the fastener 40 can
be reduced, and the durability of the fastener 40 can be
improved.
[0071] Further, FIG. 7(b) is an example where the clearance S is
disposed only between the fastener 40 and the edge portion 53a of
the step portion 53 of the spring seat 37 on the opposite side of
the energizing direction of the spring 41 (the lower side in the
drawing) By configuring the fuel inlet valve in this also, the
force that acts on the fastener 40 from the spring seat 37 and the
force that acts on the fastener 40 from the valve piston 35 can be
caused to act in diagonal directions. Consequently, the forces that
act on the fastener 40 are changed from a shearing direction to a
compressing direction, shear force that acts on the fastener 40 can
be reduced, and the durability of the fastener 40 can be
improved.
[0072] In this manner, when disposing the clearance between the
fastener and the edge portion of the groove portion of the valve
piston on the energizing direction side of the spring and/or
between the fastener and the edge portion of the step portion of
the spring seat on the opposite side of the energizing direction of
the spring, the predetermined clearance can be disposed by giving
the cross-sectional shape of the groove portion or the step portion
a circular arc shape whose diameter is larger than the diameter of
the cross section of the fastener and offsetting the center of the
circle that draws that circular arc from an outer surface position
of the valve piston.
[0073] That is, when the clearance is to be disposed between the
fastener and the predetermined edge portion of the groove portion
of the valve piston, as shown in FIG. 8(a), a center position Q of
the circle of the circular arc-shaped cross section of the groove
portion 51 of the valve piston 35 is offset outward in the outer
peripheral direction from an outer surface position of the valve
piston 35, whereby the curvature of the groove portion 51 becomes
larger than the curvature of the fastener 40 and the predetermined
clearance S can be formed. Similarly, when the clearance is to be
disposed between the fastener and the cut portion of the spring
seat, as shown in FIG. 8 (b), the center position Q of the circle
of the circular arc-shaped cross section of the cut portion 53 of
the spring seat 37 is offset in the inside direction of the valve
piston 35 from an outer surface position of the valve piston 35'
whereby the curvature of the cut portion 53 becomes larger than the
curvature of the fastener 40 and the predetermined clearance S can
be formed.
[0074] It will be noted that "outer surface position of the valve
piston" means a surface position on the circumferential direction
outer side with respect to the axial line of the valve piston and a
surface position that exists when it is assumed that that surface
position on the circumferential direction outer side extends.
[0075] Further, as shown in FIG. 9, the predetermined clearance S
can also be formed by giving the cross-sectional shapes of the
groove portion 51 of the valve piston 35 and the step portion 53 of
the spring seat 37 linear shapes.
[0076] However, when the cross-sectional shapes of the groove
portion 51 and the step portion 53 are given such linear shapes,
the fastener and the valve piston, or the spring seat and the
fastener, linearly contact each other, the contact area ends up
becoming excessively small, and there is the potential for pressure
to become concentrated. Speaking in terms of this standpoint, it is
more preferable for the cross-sectional shapes to be given circular
arc shapes because the contact area between the groove portion of
the valve piston and the fastener and the contact area between the
step portion of the spring seat and the fastener can be ensured as
largely as possible and rattling between the valve piston and the
spring seat can be prevented.
[0077] Further, as shown in FIG. 10, it is preferable for a
frictional force generating member 55 to be intervened between the
groove portion 51 of the valve piston 35 and the fastener 40 or
between the step portion 53 of the spring seat 37 and the fastener
40.
[0078] By intervening this frictional force generating member 55,
the contact position between the groove portion 51 of the valve
piston 35 or the step portion 53 of the spring seat 37 and the
fastener 40, that is, the acting points P1 and P2 of the forces
that act on the fastener 40, can be held in positions away From the
edges of the groove portion 51 and the step portion 53.
Consequently, the force that acts on the fastener 40 from the valve
piston 35 and the force that acts on the fastener 40 from the
spring seat 37 can be easily caused to act in diagonal directions
and shear force that acts on the fastener 40 can be easily
reduced.
[0079] Further, as long as the fastener that locks to the groove
portion of the valve piston and the step portion of the spring seat
is one that can be caused to lock with respect to both the groove
portion and the step portion, it is not particularly limited, and a
clip member or the like can be used in addition to the
aforementioned C-ring.
[0080] However, in order to be able to dispose the fastener inside
the space in the holder portion of the fuel inlet valve, it is
preferable to use a C-ring because it can be configured as a
relatively small fastener, and it is particularly preferable to use
a C-ring that comprises a high-elasticity alloy. By using such a
C-ring as the fastener, the strength of the C-ring can be ensured,
and the shape of the C-ring can be returned to its initial shape
and reliably locked to the groove portion of the valve piston after
the C-ring is widened and the valve piston is inserted during
assembly of the fuel inlet valve.
[0081] Examples of the high-elasticity alloy include an Ni--Ti
alloy and a Co--Cr alloy, but the high-elasticity alloy is not
limited to these.
[0082] Further, it is preferable to configure the valve piston and
the spring seat that configure the fuel inlet valve using
carburized steel or bearing steel. This is because, as has been
mentioned up to now, the fuel inlet valve in the fuel supply pump
of the present invention employs a fixing method that uses a
predetermined fastener as the method of fixing the spring seat to
the valve piston, so in terms of the material that configures the
spring seat and the valve piston, joining force resulting from
welding is no longer called into question.
[0083] Consequently, the strength of the valve piston and the
spring seat can be raised and, even when fuel of an even higher
pressure is to be pressure-fed in a large amount, the durability of
the fuel supply pump improves and the fuel can be stably
pressure-fed. Further, it becomes unnecessary for the fuel inlet
valve to be disposed member with a high-strength shim or the like
that prevents wear of the spring seat, the number of parts can be
reduced, and assembly efficiency can be improved.
(9) Fuel Outlet Valve
[0084] Further, the fuel outlet valve 22 shown in FIG. 2 is
disposed on the side of the fuel pressurization chamber 14 in the
cylindrical space 11b of the pump housing 11 and is a part for
delivering the fuel that has been pressurized to a high pressure to
the common rail and the like.
[0085] For example, a ball valve 61 is always energized in a valve
closing direction by a spring 63 and, when the plunger 13 is pushed
up by the cam 21 and the inside of the fuel pressurization chamber
14 reaches a high pressure, the fuel outlet valve 22 can be opened
by the pressure of the fuel and allow the fuel to pass
therethrough.
6. Example of Use in an Accumulator Fuel Injection System with a
Pressure-Amplifying Piston
[0086] The fuel supply pump of the present invention that has been
described up to now can be suitably used as a fuel supply pump that
is used in an accumulator fuel injection system with a pressure
amplifying piston (APCRS) that further amplifies, with a pressure
amplifying piston, the pressure of high pressure fuel that has been
supplied from a pressure accumulator (common rail) and thereafter
injects that fuel from injectors.
[0087] FIG. 11 shows a configuration example of an APCRS. This
APCRS is configured by a fuel tank 62, the fuel supply pump 1 that
pressurizes the fuel inside the fuel tank 62 to a high pressure and
pressure-feeds the high pressure fuel, a pressure accumulator
(common rail) 66 for pressure-accumulating the high pressure fuel
that has been pressure-fed from this fuel supply pump 1, pressure
amplifying devices (pressure amplifying pistons) 68 for further
amplifying the pressure of the fuel that has been
pressure-accumulated by the common rail 66, and injectors 70.
[0088] The configuration of the common rail 66 is not particularly
limited, and a publicly known configuration can be used. The plural
injectors 70 are connected to the common rail 66, the fuel that has
been pressurized to a high pressure by the fuel supply pump 1 is
supplied equally with respect to all of the injectors 70, and the
injectors 70 are controlled such that the injectors 70 can be
caused to inject the fuel at a desired injection timing to an
internal combustion engine (not shown). Because the APCRS is
disposed with this common rail 66, the fuel can be injected to the
engine via the injectors 70 at an injection pressure commensurate
with the number of rotations without the rotation of the pump
directly affecting the injection pressure.
[0089] Further, a pressure detector (not shown) is connected to the
common rail 66, and a pressure-detection signal obtained by this
pressure detector is sent to an electronic control unit (ECU:
Electrical Controlling Unit). Additionally, the ECU receives the
pressure-detection signal from the pressure detector and controls
an electromagnetic control valve (not shown) similarly disposed in
the common rail 66 such that the common rail pressure becomes a
predetermined pressure.
[0090] Further, each of the pressure amplifying devices can be
given a configuration which, as exemplified in FIG. 11, includes a
cylinder 75, a mechanical piston (pressure amplifying piston) 74, a
pressure reception chamber 78, a pressurization chamber 79, an
electromagnetic valve 80 and a circulation path 77, with a pressure
receiver 72 and a pressurizer 76 whose area is relatively smaller
than that of the pressure receiver 72 being disposed in the
mechanical piston 74.
[0091] In each of these pressure amplifying devices, the mechanical
piston 74 that is housed inside the cylinder 75 is pushed by fuel
that has the common rail pressure in the pressure receiver 72 and
moves such that the fuel inside the pressurization chamber 79 is
compressed and its pressure is amplified by the pressurizer 76.
[0092] That is, as shown in the schematic diagram of FIG. 12, by
configuring the pressure amplifying device as a mechanical piston
that is disposed with the pressure receiver and the pressurizer
whose area is relatively smaller than that of the pressure receiver
and considering the stroke amount of the piston, it is possible to
efficiently amplify the pressure of the fuel that has the common
rail pressure while reducing pressure loss as much as possible.
[0093] More specifically, the fuel from the common rail (pressure:
p1, volume: V1, workload: W1) can be made into even higher pressure
fuel (pressure: p2, volume: V2, workload: W2) by the mechanical
piston that is disposed with the pressure receiver whose area is
relatively large and the pressurizer whose area is relatively
small.
[0094] Each of the pressure amplifying devices 68 shown in FIG. 11
uses the fuel that has the common rail pressure in a large amount
in order to push the mechanical piston 74, but after
pressurization, the fuel is refluxed to the fuel tank 62 via the
electromagnetic valve 80. That is, a large portion of the fuel that
has the common rail pressure pushes the mechanical piston 74, is
thereafter refluxed to the fuel tank 62 via a line 93, for example,
and can again be used as high pressure fuel.
[0095] On the other hand, fuel whose pressure has been amplified by
the pressurizer 76 is sent to injection holes 73 side of the
injectors and injected, and fuel that has been used in back
pressure control of the injectors 70 and discharged from the
electromagnetic valve 71 becomes refluxed to the fuel tank 62 via
the line 93.
[0096] By disposing this pressure amplifying device, the mechanical
piston can be effectively pushed by the fuel that has the common
rail pressure in an arbitrary time period and without making the
common rail excessively large.
[0097] Further, the configuration of the injectors 70 is not
particularly limited and can, as exemplified in FIG. 11, be given a
configuration that is disposed with a nozzle body 103 that includes
a seat surface 102 on which a needle valve body 101 sits and an
injection hole 73 that is formed further on the downstream side
than the valve body abutment portion of this seat surface 102, with
the ejector 70 guiding, to the injector hole 73, fuel that is
supplied from the upstream side of the seat surface 102 when the
needle valve body 101 lifts.
[0098] Further, in each of the injectors 70, the needle valve body
101 is always energized toward the seat surface 102 by a spring 104
or the like, and the needle valve body 101 can be configured as an
electromagnetic valve type that is opened and closed by switching
between energization/no energization of a solenoid (not shown).
[0099] In this pressure amplifying accumulator fuel injection
system, a fuel supply pump that can pressure-feed even higher
pressure fuel to the common rail in a large amount is required, but
when the fuel supply pump is the fuel supply pump of the present
invention such as has been described above, the durability of the
fuel inlet valve is improved and the fuel supply pump can withstand
long-term use even in use in an APCRS. Consequently, even when the
fuel supply pump is caused to operate at a high pressure and a high
speed over a long period of time, the fuel supply pump can stably
supply a large amount of high pressure fuel.
* * * * *