U.S. patent application number 13/944270 was filed with the patent office on 2013-11-14 for plunger type high-pressure fuel pump.
The applicant listed for this patent is Hitachi, Ltd.. Invention is credited to Masami ABE, Junichi SHIMADA, Kenichiro TOKUO, Satoshi USUI, Hiroyuki YAMADA.
Application Number | 20130302192 13/944270 |
Document ID | / |
Family ID | 40263532 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130302192 |
Kind Code |
A1 |
TOKUO; Kenichiro ; et
al. |
November 14, 2013 |
Plunger Type High-Pressure Fuel Pump
Abstract
A plunger type high-pressure fuel pump includes a plunger
reciprocated in a cylinder. A fluid pressurizing chamber of the
pump has a chamber with a capacity that changes with reciprocation
of the plunger. An electromagnetic valve is provided between the
pressurizing chamber and a fluid suction passage; as well as a
discharge valve. The electromagnetic valve includes a valve member
including a suction valve; a solenoid coil adapted to displace the
valve member; an anchor made of a magnetic material provided
integrally with the valve member; and a core forming a magnetic
circuit to attract the anchor by the electromagnetic force and
dividing the inside of the electromagnetic valve into an internal
space and an external space communicating with the fluid suction
passage. The anchor or the core is provided with a fluid passage
through which fluid can flow between the internal space and the
external space formed by the anchor and the core, respectively,
when the suction valve is in an opened state.
Inventors: |
TOKUO; Kenichiro; (Munchen,
DE) ; USUI; Satoshi; (Hitachinaka, JP) ;
YAMADA; Hiroyuki; (Hitachinaka, JP) ; SHIMADA;
Junichi; (Tokyo, JP) ; ABE; Masami; (Hitachi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hitachi, Ltd. |
Tokyo |
|
JP |
|
|
Family ID: |
40263532 |
Appl. No.: |
13/944270 |
Filed: |
July 17, 2013 |
Current U.S.
Class: |
417/437 |
Current CPC
Class: |
F02M 63/0015 20130101;
F02M 2200/304 20130101; F04B 53/10 20130101; F02M 63/025 20130101;
F02M 59/367 20130101; F02M 63/0043 20130101; F02M 59/102 20130101;
F02M 59/366 20130101; F02M 63/0042 20130101; F02M 63/004 20130101;
F02M 2200/28 20130101; F02M 63/0078 20130101 |
Class at
Publication: |
417/437 |
International
Class: |
F04B 53/10 20060101
F04B053/10 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 2007 |
JP |
2007-280553 |
Claims
1. A plunger type high-pressure fuel pump comprising: a cylinder
provided in the pump; a plunger provided slidably in the cylinder
and reciprocated according to rotation of a cam; a fluid
pressurizing chamber formed by the plunger and the cylinder; an
electromagnetic valve provided in a space formed between the
pressurizing chamber and a fluid suction passage; and a discharge
valve provided in a space formed between the pressurizing chamber
and a fluid discharge passage; wherein the electromagnetic valve
includes: a valve member, including a suction valve, opening and
closing an inlet side of the pressurizing chamber; an elastic
member for biasing the valve member in a valve-closing direction; a
solenoid coil adapted to displace the valve member in an opening
direction; an anchor made of a magnetic material operated by
electromagnetic force of the solenoid coil, integrally provided
with the valve member; and a core forming a magnetic circuit to
attract the anchor in an opening direction by the electromagnetic
force and dividing the inside of the electromagnetic valve into a
hermetically closed space and an external space communicating with
the fluid suction passage; and wherein the anchor or the core is
provided with a fluid passage through which fluid can flow between
the hermetically closed space and the external space formed by the
anchor and the core, when the suction valve is in an opened
state.
2. The plunger type high-pressure fuel pump according to claim 1,
wherein the core has an insertion port to insert the valve member
into at a central portion of the core, the core has an abutment
surface in abutment against the anchor on the outside of the
insertion port, and a radial fluid passage-groove is formed on the
abutment surface.
3. The plunger type high-pressure fuel pump according to claim 1,
wherein the anchor has an abutment surface in abutment against the
fixed core, a radial fluid passage-groove is formed on the abutment
surface, and fluid in the hermetically closed space communicates
with the external space via the fluid passage-groove of the anchor
and via a clearance between the core and the valve member.
4. The plunger type high-pressure fuel pump according to claim 1,
wherein the core has an insertion port to insert the valve member
into at a central portion of the core, the core has an abutment
surface in abutment against the anchor on the outside of the
insertion port, the core has a non-abutment surface in non-abutment
against the anchor on the outside of the abutment surface, and a
fluid passage hole is formed in the core between the non-abutment
surface and a surface in contact with the external space.
5. The plunger type high-pressure fuel pump according to claim 1,
wherein the anchor has an abutment surface facing to and abutting
against the core inserted into the valve member, and a fluid
passage hole is formed in the anchor between the abutment surface
of the anchor facing to a clearance between the core and the valve
member and a surface of the anchor in contact with the hermetically
closed space.
6. The plunger type high-pressure fuel pump according to claim 1,
wherein the core has an insertion port to insert the valve member
into a central portion of the core, the core has an abutment
surface in abutment against the anchor on the outside of the
insertion port, and the abutment surface is provided with a plating
surface to be plated, the anchor has an abutment surface in
abutment against the fixed core, and the abutment surface is
provided with a plating surface to be plated, and at least one of
the plated surface of the core and the plated surface of the anchor
is provided with a radial fluid passage groove.
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/259,999, filed Oct. 28, 2008, the entire
disclosure of which is incorporated herein by reference, which, in
turn, claims priority under 35 U.S.C. .sctn.119 to Japanese
Application No. 2007-280553, filed Oct. 29, 2007, the priority of
which is also claimed here.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to a fuel supply
system for an internal combustion engine, and more specifically to
an electromagnetic valve structure suitable for stable closing
operation of an electromagnetic valve in a plunger type
high-pressure fuel pump.
[0004] 2. Description of the Related Art
[0005] Direct injection engines (in-cylinder injection internal
combustion engines) for today's automobiles are developed in order
to make emissions cleaner and improve fuel consumption in view of
environmental protection. The direct injection engines are such
that fuel is directly injected by a fuel injection valve into the
combustion chamber of a cylinder. In addition, the particle
diameter of fuel injected from the fuel injection valve is reduced
to promote combustion of the injected fuel, thereby reducing the
specific substance in the exhaust gas and improving fuel
consumption.
[0006] Reducing the particle diameter of fuel injected from the
fuel injection valve requires means for high pressurizing fuel. To
meet the requirement, various proposals are made of the technology
of a high-pressure fuel pump which supplies high-pressure fuel
under pressure to the fuel injection valve (see e.g.
JP-A-2006-256086). The technology described in JP-A-2006-256086
relates to a high-pressure fuel pump provided with a
normally-closed electromagnetic valve as a suction valve. During a
suction stroke, fluidic force is used to naturally open the suction
valve, thereby achieving reduction of hitting sound of the valve
body which may be caused at the time of valve-opening
operation.
[0007] An air gap between the attractive member and movable member
of an electromagnetic drive section in a hydraulic control valve is
minimized by electromagnetic force resulting from energization.
This makes it easy to cause negative pressure, which
disadvantageously leads to the occurrence of a cavity. To prevent
this, reform measures are disclosed in which the attractive member
or movable member is provided, in an end face, with an opening
portion formed as a fuel groove (see e.g. JP-A-2004-137996).
[0008] For example, JP-A-2005-511952 discloses a flow rate control
device that controls a flow rate of liquid flowing through a valve
operatively opened and closed by electromagnetic force. This device
is configured such that a movable element moved by the
electromagnetic force is provided with a swirling flow path to
thereby prevent uneven wear of a sliding portion and to speed up
valve opening and closing operation.
SUMMARY OF THE INVENTION
[0009] The high-pressure fuel pump described in JP-A-2006-250086
repeats the intermittent suction and discharge of fuel; therefore,
pressure pulsation is generated in piping upstream of and
downstream of the fuel pump. For example, pressure on the low
pressure piping side lowers when fuel is sucked by the high
pressure fuel pump and rises when discharged. If such pressure
variations occur, the opening and closing timing of the
electromagnetic valve becomes unstable. Thus, fuel to be discharged
cannot accurately be controlled.
[0010] JP-A-2004-137996 and 2005-511952 disclose the provision of
the fuel passage in the movable member or attractive member of the
electromagnetic valve. However, this structure is devised to
prevent the occurrence of the cavity resulting from the negative
pressure caused in the air gap portion. In addition, the structure
is devised to speed up the operation of the movable element in the
electromagnetic valve. In other words, consideration is not made in
view of stabilizing the closing timing of the electromagnetic valve
irrespective of the internal and external pressure variations of
the electromagnetic valve.
[0011] It is an object of the present invention to provide a
plunger type high-pressure fuel pump that can stabilize the closing
timing of an electromagnetic valve so as to discharge fuel at a
stable flow rate for each cycle while valve-closing operation is
not varied under a pressure difference between a hermetically
closed space in the electromagnetic valve of the plunger type
high-pressure fuel pump and an external space formed outside of the
hermetically closed space.
[0012] In accordance with an aspect of the present invention, a
plunger type high-pressure fuel pump includes: a cylinder provided
in the pump; a plunger provided slidably in the cylinder and
reciprocated according to rotation of a cam; a fluid pressurizing
chamber defined between the plunger and the cylinder; an
electromagnetic valve provided in a space defined between the
pressurizing chamber and a fluid suction passage; and a discharge
valve provided in a space defined between the pressurizing chamber
and a fluid discharge passage. The electromagnetic valve includes:
a valve body including a suction valve opening and closing an inlet
side of the pressurizing chamber; an elastic body for biasing the
valve body in a valve-opening direction; a solenoid coil adapted to
displace the valve body in an opening direction; an anchor made of
a magnetic material operated by electromagnetic force of the
solenoid coil and provided integrally with the valve body; and a
core forming a magnetic circuit to attract the anchor in an opening
direction by the electromagnetic force and dividing the inside of
the electromagnetic valve into a hermetically closed space and an
external space communicating with the fluid suction passage. The
anchor or the core is provided with a fluid passage through which
fluid can flow between the hermetically closed space and the
external space formed by the anchor and the core, respectively when
the suction valve is in an opened state.
[0013] According to the aspect of the present invention, the anchor
or the core is provided with the fluid passage through which fluid
can flow between the hermetically closed space of the
electromagnetic valve and the external space at the time of opening
the valve. This can stabilize the closing timing of the
electromagnetic valve. Thus, the plunger type high-pressure fuel
pump can discharge fuel at a stable flow rate for each cycle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 illustrates the entire structure of a fuel supply
system using a plunger type high-pressure fuel pump according to an
embodiment of the present invention.
[0015] FIG. 2 is a cross-sectional view illustrates the structure
of the high-pressure fuel pump according to the embodiment.
[0016] FIG. 3 is a diagram for assistance in explaining pressure
situations in an electromagnetic valve and around a pressurizing
chamber in the plunger type high-pressure fuel pump according to
the embodiment.
[0017] FIG. 4 is a cross-sectional view illustrating a detailed
structure of the electromagnetic valve in the plunger type
high-pressure fuel pump according to the embodiment.
[0018] FIG. 5 is a cross-sectional view illustrating a
configurational example in which a passage hole is provided in an
anchor (which is configured integrally with a valve body of the
electromagnetic valve and is magnetically attracted by a core) to
communicate between a hermetically closed space formed inside the
electromagnetic valve and an external space formed outside of the
hermetically closed space, in the plunger type high-pressure fuel
pump according to the present embodiment.
[0019] FIG. 6 is a cross-sectional view illustrating a
configurational example in which the passage hole is provided in
the core (which forms a magnetic circuit-forming body along with
the body of the electromagnetic valve) to communicate between the
hermetically closed space formed inside the electromagnetic valve
and the external space formed outside of the hermetically closed
space, in the plunger type high-pressure fuel pump according to the
present embodiment.
[0020] FIG. 7 illustrates another configurational example in which
the passage hole is provided in the core (which forms the magnetic
circuit-forming body along with the body of the electromagnetic
valve) to communicate between the hermetically closed space formed
inside the electromagnetic valve and the external space formed
outside of the hermetically closed space, in the plunger type
high-pressure fuel pump according to the present embodiment.
[0021] FIG. 8 illustrates other configurational examples in which
the passage hole is provided in each of the core and the anchor to
communicate between the hermetically closed space formed inside the
electromagnetic valve and the external space formed outside of the
hermetically closed space, in the plunger type high-pressure fuel
pump according to the present embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] A plunger type high-pressure fuel pump according to
embodiments of the present invention will hereinafter be described
in detail with reference to FIGS. 1 through 8.
[0023] FIG. 1 illustrates the entire structure of a fuel supply
system using the plunger type high-pressure fuel pump according to
an embodiment of the present invention. FIG. 2 is a cross-sectional
view illustrates the structure of the plunger type high-pressure
fuel pump according to the embodiment. FIG. 3 is a diagram for
assistance in explaining pressure situations in an electromagnetic
valve and around a pressurizing chamber in the plunger type
high-pressure fuel pump according to the embodiment. FIG. 4 is a
cross-sectional view illustrating a detailed structure of an
electromagnetic valve in the plunger type high-pressure fuel pump
relating to the embodiment.
[0024] FIG. 5 is a cross-sectional view illustrating a
configurational example in which a passage hole is provided in an
anchor (which is configured integrally with a valve body of the
electromagnetic valve and is magnetically attracted by a core) to
communicate between a hermetically closed space formed inside the
electromagnetic valve and an external space formed outside of the
hermetically closed space, in the plunger type high-pressure fuel
pump according to the present embodiment. FIG. 6 is a
cross-sectional view illustrating a configurational example in
which the passage hole is provided in the core (which forms a
magnetic circuit-forming body along with the body of the
electromagnetic valve) to communicate between the hermetically
closed space formed inside the electromagnetic valve and the
external space formed outside of the hermetically closed space, in
the plunger type high-pressure fuel pump according to the present
embodiment. FIG. 7 illustrates another configurational example in
which the passage hole is provided in the core (which forms the
magnetic circuit-forming body along with the body of the
electromagnetic valve) to communicate between the hermetically
closed space formed inside the electromagnetic valve and the
external space formed outside of the hermetically closed space, in
the plunger type high-pressure fuel pump according to the present
embodiment. FIG. 8 illustrates other configurational examples in
which the passage hole is provided in each of the core and the
anchor to communicate between the hermetically closed space formed
inside the electromagnetic valve and the external space formed
outside of the hermetically closed space, in the plunger type
high-pressure fuel pump according to the present embodiment.
[0025] With reference to FIG. 1, a description is first given of
the entire structure of the fuel supply system using the plunger
type high-pressure fuel pump 1 according to the embodiment. The
high-pressure fuel pump 1 is formed with a fuel suction passage 10,
a fuel discharge passage 11, and a pressurizing chamber 12. A
plunger 2, a pressurizing member, is slidably held by a cylinder
portion 62 inside the high-pressure fuel pump 1.
[0026] An end portion of the plunger 2 forms part of the
pressurizing chamber 12. The plunger 2 is reciprocated by the
rotation of a cam 100 to vary the volume of the pressurizing
chamber 12. A suction valve 5 and a discharge valve 6 are installed
in the fuel suction passage 10 and the fuel discharge passage 11,
respectively. The suction valve 5 and the discharge valve 6 are
held in one direction by springs 92 and 93, respectively, and each
serve as a check valve for limiting the flow direction of fuel.
[0027] An electromagnetic actuator 8 is held in the high-pressure
fuel pump 1 and includes a solenoid coil 90, a rod (a valve body)
91, and the spring 92. The rod 91 receives a biasing force applied
thereto by the spring 92 in the closing direction of the suction
valve 5 with a drive signal not given to the electromagnetic
actuator 8. Thus, the suction valve 5 is brought into a closed
state as shown in FIG. 1.
[0028] Fuel is led by a low-pressure pump 51 from a tank 50 to a
fuel introduction port 13 (see FIG. 2) of the high-pressure fuel
pump 1 while the pressure of the fuel is regulated to a given
pressure by a pressure regulator 52. Thereafter, the fuel is
pressurized by the high-pressure fuel pump 1 and supplied under
pressure from the fuel discharge passage 11 to a common rail 53.
Injectors 54, a pressure sensor 56, and a safety valve 58 are
attached to the common rail 53.
[0029] When the fuel pressure in the common rail 53 exceeds a
predetermined value, the safety valve 58 opens to prevent damage to
a high-pressure piping system. The injectors 54 attached have the
number made equal to that of cylinders of an engine and inject fuel
in response to signals of a controller 57. The controller 57
includes an upper controller 63, a pump controller 59, and an
injector controller 65.
[0030] The pressure sensor 56 sends pressure data obtained to the
upper controller 63. The upper controller 63 calculates an
appropriate amount of injection fuel and fuel pressure, etc. on the
basis of engine state amounts (a crank rotational angle, a throttle
opening angle, engine speed, fuel pressure, etc.) obtained from
various types of sensors. In addition, the upper controller 63
calculates timing to drive the high-pressure fuel pump 1 and the
injectors 54 and a flow rate and sends drive signals thereto. In
the figure, the controller 57 is separately configured to include
the upper controller 63 for calculating a command value; the pump
controller 59 for directly sending a drive signal to the
high-pressure fuel pump 1; and the injector controller 65 for
sending drive signals to the injectors 54. However, the controller
57 may be configured to bring them into one unit.
[0031] The plunger 2 is reciprocated by the cam 100 rotated by the
engine camshaft or the like to increase and reduce the volume of
the pressurizing chamber 12. If the plunger 2 is moved upward in
FIG. 1, the volume of the pressurizing chamber 12 is reduced. On
the other hand, the plunger 2 is moved downward, the volume of the
pressurizing chamber 12 is increased.
[0032] During the discharge stroke of the plunger 2, if the
electromagnetic actuator 8 is operated (by de-energizing the
solenoid coil 90) to close the suction valve 5, the pressure in the
pressurizing chamber 12 is increased to automatically open the
discharge valve 6. Thus, fuel is supplied under pressure to the
common rail 53. The suction valve 5 is automatically closed by the
spring 92 even if the pressure of the pressurizing chamber 12 is
lower than that of the fuel suction passage 10. However, the
opening of the suction valve 5 is determined by the on-operation of
the electromagnetic actuator 8.
[0033] The plunger type high-pressure fuel pump according to the
present embodiment is such that the closing timing of the
electromagnetic valve thereof is controlled by the pump controller
59 to thereby control the volume of fuel discharged through the
discharge valve. If the electromagnetic actuator 8 is given a drive
signal by the pump controller 59, the solenoid coil 90 is energized
to generate an electromagnetic field to thereby move the rod 91
rightward, in the example of the figure, against the biasing force
of the spring 92. Then, if the plunger 2 is moved downward during
the intake stroke, fuel is sucked from the suction passage 10 into
the pressurizing chamber 12. Next, if the plunger 2 is moved upward
from the bottom dead center to open the suction valve 5, since the
suction valve 5 is opened, the fuel in the pressurizing chamber 12
is returned to the suction passage 10 along with the upward
movement of the plunger 2. In this case, the discharge valve 6 is
set not to be opened by the pressure in the pressurizing chamber 12
(the so-called spill stroke is formed). In such a case, the
discharge flow rate of the high-pressure fuel pump is zero.
[0034] Subsequently, in the middle of the upward movement of the
plunger 2 (in the middle of the spill stroke), if the drive signal
sent to the electromagnetic actuator 8 is interrupted (if a drive
current is cut off), the rod 91 is shifted by the biasing force of
the spring 92 to bring the suction valve 5 into a closed state. The
further upward movement of the plunger 2 increases the pressure in
the pressurizing chamber 12 to a level higher than a predetermined
value to press and open the discharge valve 6. This brings the
spill stroke in the discharge stroke, in which fuel is supplied
under pressure to the common rail 53. In this way, timing to turn
off the drive signal sent to the electromagnetic actuator 8 is
adjusted to variably adjust the discharge flow rate in a range from
zero to the maximum discharge rate. In addition, the upper
controller 63 calculates appropriate discharge timing on the basis
of a signal of the pressure sensor 56. The pump controller 59 turns
on and off the drive signal sent to the electromagnetic actuator 8.
Thus, the pressure of the common rail 53 can be maintained at a
general steady value.
[0035] FIG. 2 depicts the structure of the plunger type
high-pressure fuel pump according to the present embodiment. In
this pump structure, fuel is led from the fuel introduction port 13
via the fuel suction passage 10 to the pressurizing chamber 12 in
which the fuel is increased in pressure and thus the pressurized
fuel is supplied to the fuel discharge passage 11. In FIG. 2, shown
are the plunger 2, the plunger-biasing spring 4, the suction valve
5, the discharge valve 6, the electromagnetic valve 20, the rod
(valve body) 91 of the suction valve 5, and an accumulator 21 (used
to absorb low-pressure side pressure pulsations).
[0036] FIG. 3 is a diagram for assistance in explaining pressure
situations in the electromagnetic valve 20 and around the
pressurizing chamber 12 in the plunger type high-pressure fuel
pump. FIG. 3 illustrates the spill stroke described above,
situations where the plunger 2 is moved upward to be increasing the
fuel pressure in the pressurizing chamber 12 and a state where the
solenoid coil 90 is just about to be de-energized to close the
suction valve 5. Since the solenoid coil 90 is turned on in this
situation, a right end of a left end side large-diameter portion of
the rod (the valve body) 91 is abutted at a left end against a
projecting portion 23 of the electromagnetic valve body so that a
hermetically closed space 38 surrounded by such components is
defined. Incidentally, when the solenoid coil 90 is energized, the
rod 91 is moved rightward so that the large-diameter portion right
end is abutted against the projecting portion 23 of the
electromagnetic valve body 22. Thus, the rod 91 is positioned and
stopped. In this stopped state, the hermetically closed space 38 is
defined inside the electromagnetic valve.
[0037] Consideration is now made to the pressure relationship
between the hermetically closed space described above and an
external space (in which the spring 92 of the electromagnetic valve
20, the periphery of the suction valve 5, the pressurizing chamber
12, the in-valve passage 15, and the suction passage 10 are
present) adjacent to the hermetically closed space. The pressure in
the hermetically closed space defined inside the electromagnetic
valve encountered when the electromagnetic valve is opened is equal
to in the external space encountered when the electromagnetic valve
is just opened. However, the pressure in the external space is
pulsated and momentarily varied due to the pressure variations of a
fuel source and to the operation of the plunger. This causes a
pressure difference between the internal space and the external
space. This pressure difference causes variations in the closing
operation of the electromagnetic valve even if timing to turn off
the drive current supplied to the solenoid coil is the same. For
example, if the inside pressure of the hermetically closed space is
low and the outside pressure of the external space is high, then
the valve-closing timing will be accelerated. Specifically, the
occurrence of the variations between the inside pressure and the
outside pressure varies the valve-closing operation (the valve body
operation varies even if the command of the valve-closing timing is
issued at the same time). Consequently, the variations of the
valve-closing operation affect the accurate control of the
discharge amount of fuel.
[0038] The object of the invention is to reduce the variations of
the closing operation of the electromagnetic valve used in the
plunger type high-pressure fuel pump. To that end, the major
characteristic, i.e., the outline, of the present embodiment is
that a fuel passage is provided to communicate between the
hermetically closed space defined inside the electromagnetic valve
and the external space formed outside of the hermetically closed
space while the electromagnetic valve is opened, thereby preventing
the occurrence of the internal-external pressure difference.
[0039] FIG. 4 is a cross-sectional view illustrating the detailed
structure of an electromagnetic valve in a plunger type
high-pressure fuel pump relating to the embodiment of the present
invention. In addition, FIG. 4 illustrates a basic configuration to
which the characteristic structure of the embodiment is applied. In
FIG. 4, shown are the suction valve 5, the fuel suction passage 10,
the in-valve passage 15 (a fluid passage in the electromagnetic
valve communicating with the suction passage 10 present in the
high-pressure fuel pump 1), the solenoid coil 90, the rod (the
valve body) 91, a core 30 (the electromagnetic valve body forming a
magnetic circuit), a core projecting portion 31 (an electromagnetic
valve body projecting portion), an anchor 32 (a magnetic body press
fitted into the valve body 91 and magnetically attracted by the
core 30), valve body guides 33, 34, a magnetic circuit-forming body
35, a frame 36 forming a magnetic path, a clearance 37, the
hermetically closed space 38, and the external space 39.
[0040] In FIG. 4, to open the suction valve 5, the solenoid coil 90
is energized to allow the core 30, the frame 36, the magnetic
circuit-forming body 35, and the anchor 32 to form the magnetic
circuit. Thus, the anchor 32 is magnetically pulled by the core
projecting portion 31 of the core 30 against the biasing force of
the spring 92 to define the hermetically closed space 38 inside the
electromagnetic valve. Specifically, in the figure, the right end
side of the anchor 32 is brought into close contact with the left
end side of the core projecting portion 31 to define the
hermetically closed space 38. A clearance 37 is defined between the
core projecting portion 31 and the rod (the valve body) 91 so as to
enable smooth left-right movement of the rod 91. Likewise, a
clearance 45 is defined between the outer circumferential surface
of the anchor 32 and the inner circumferential surface of the
magnetic circuit-forming body 35.
[0041] FIGS. 5 through 8 illustrate the characteristics of the
embodiments of the invention as configurational examples in which a
fuel passage communicates between the inside and outside of the
electromagnetic valve while the electromagnetic valve is opened.
The provision of this communicating fuel passage can stabilize the
closing timing of the electromagnetic valve. The configurational
examples of FIGS. 5 and 6 prevent the performance (attractive
force) of the electromagnetic valve from lowering by providing the
communicating fuel passage at a portion other than a magnetic
attractive surface.
[0042] In FIG. 5, the anchor 32 is internally and inclinedly formed
with a passage hole 41 as a passage allowing the inside of the
electromagnetic valve to communicate with the outside thereof while
the electromagnetic valve is opened, that is, as a communicating
passage between the hermetically closed space 38 and the external
space 39. The passage hole 41 is inclined because the right end of
the passage hole 41 is disposed to face the clearance 37 between
the core projecting portion 31 and the valve body 91. Thus, the
passage hole 41 communicates with the external space 39.
[0043] In this way, the fuel in the hermetically closed space 38
communicates with the fuel in the external space 39 via the
clearance 37. The fuel passage in the configurational example of
FIG. 5 is formed as the inclined passage hole 41. However, the fuel
passage is not limited to this. The fuel passage may be a passage
hole having any shape as long as the right end of the anchor 32 is
disposed to face the clearance 37. For example, an L-shaped passage
hole may be applicable in which a hole is formed to extend from a
position facing the clearance 45 between the magnetic circuit
forming body 45 and the anchor 32 toward the valve body 91 and
further extends along the inner circumferential side of the anchor
32.
[0044] In FIG. 6, a passage hole 42 is inclinedly formed inside the
core projecting portion 31 (a structure adapted to attract the
right end of the anchor 32) of the core 30 (which forms the body of
the electromagnetic valve and which is a magnetic path forming
body), as a passage communicating between the hermetically closed
space 38 and the external space 39 while the electromagnetic valve
is opened. Thus, the hermetically closed space 38 is allowed to
communicate with the external space 39 through the passage hole 42.
In the example of FIG. 6, the left end of the passage hole 42 is
disposed to be offset from a position opposed to the right end
portion of the anchor 32 (the passage hole 42 is disposed at a
position other than a magnetic attractive surface). This prevents
the core 30 from lowering the force of attracting the anchor
32.
[0045] With reference to FIGS. 7 and 8, a description is next given
of a configurational example in which a passage communicating
between the hermetically closed space 38 and the external space 39
at the time of opening the electromagnetic valve is provided in a
magnetic attractive surface. FIG. 7 depicts a passage-groove 43
provided at a portion of the magnetic attractive surface of the
core projecting portion 31 included in the core 30. In FIG. 7,
reference numeral 30 denotes a whole structure of the core, 31
denotes the core projecting portion of the core 30, 46 denotes a
valve body insertion hole, and 49 denotes a core upper-lower
lateral surface (see FIG. 6).
[0046] The passage-groove 43 shown in FIG. 7 is the same as a
passage groove 48 shown in FIG. 8(3). The hermetically closed space
38 is allowed to communicate with the external space 39 through the
passage-groove 43 formed at a portion of the magnetic attractive
surface of the core. As shown in FIG. 7, although the
passage-groove 43 causes the magnetic attractive force to slightly
lower, the magnetic attractive surface needs only groove machining
Thus, fabrication can be facilitated.
[0047] FIG. 8(2) illustrates a passage-groove 47 provided at a
portion of the magnetic attractive surface of the anchor 32 by way
of example. The function and operation of this configurational
example are the same as those of FIG. 8(3). FIG. 8(1) illustrates a
configurational example in which the core 30 and the anchor 32 are
provided with passage-grooves 48 and 47, respectively. This makes
the magnetic attractive force equal to that of the case where the
passage-grooves are individually provided and aims to facilitate
the fuel communication between the hermetically closed space 38 and
the external space 39. In other words, this can eliminate a
disadvantage that if fuel is hard to flow between the hermetically
closed space and the external space, the valve body operates
slowly.
[0048] In the examples of FIGS. 7 and 8, since the core or the
anchor is formed with the passage-groove on the magnetic attractive
surface, the magnetic attractive force slightly lowers. To prevent
such lowering, the magnetic attractive surfaces (the opposite
surfaces) of the core and of the anchor are each subjected to
plating and the passage-grooves are formed on the plated portions
as shown in FIGS. 7 and 8. With this structure, since the magnetic
attractive surfaces of the core and of the anchor are not ground,
it is possible to prevent the lowering of the magnetic attractive
force.
* * * * *