U.S. patent application number 11/873780 was filed with the patent office on 2009-05-07 for pump.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Mikio OOTA.
Application Number | 20090116987 11/873780 |
Document ID | / |
Family ID | 39440207 |
Filed Date | 2009-05-07 |
United States Patent
Application |
20090116987 |
Kind Code |
A1 |
OOTA; Mikio |
May 7, 2009 |
PUMP
Abstract
A pump includes a cylinder formed with a plunger chamber, a
low-pressure portion, to which low-pressure fuel is supplied, a
plunger reciprocating in the cylinder to pressurize fluid in the
chamber, which is drawn from the portion, and a magnet valve having
a valve body. A low-pressure passage communicates between the
chamber and the portion. The magnet valve blocks the passage with
the valve body when energized, to control timing, with which fluid
in the chamber starts to be pressurized by the plunger. Dynamic
pressure of fluid flowing from the chamber into the passage is
applied to the valve body in a direction in which the valve body
closes the passage. The valve body includes an inclined surface at
a portion of the valve body, to which the dynamic pressure is
applied. The surface is nonparallel to a plane, which is
perpendicular to a displacement direction of the valve body.
Inventors: |
OOTA; Mikio; (Anjo-city,
JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
901 NORTH GLEBE ROAD, 11TH FLOOR
ARLINGTON
VA
22203
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
39440207 |
Appl. No.: |
11/873780 |
Filed: |
October 17, 2007 |
Current U.S.
Class: |
417/505 |
Current CPC
Class: |
F02M 63/0017 20130101;
F02M 63/004 20130101; F04B 53/102 20130101; F04B 49/243 20130101;
F02M 63/0035 20130101; F04B 7/0076 20130101; F02M 63/0036 20130101;
F02M 63/0043 20130101; F02M 59/102 20130101; F02M 59/368 20130101;
F02M 63/0031 20130101 |
Class at
Publication: |
417/505 |
International
Class: |
F04B 39/08 20060101
F04B039/08 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2006 |
JP |
2006-287520 |
Claims
1. A pump comprising: a cylinder formed with a plunger chamber; a
low-pressure portion, to which low-pressure fuel is supplied,
wherein a low-pressure passage communicates between the plunger
chamber and the low-pressure portion; a plunger that reciprocates
in the cylinder to pressurize fluid in the plunger chamber which is
drawn from the low-pressure portion; and a magnet valve having a
valve body, wherein: the magnet valve blocks the low-pressure
passage with the valve body when energized, to control timing, with
which fluid in the plunger chamber starts to be pressurized by the
plunger; dynamic pressure of fluid flowing from the plunger chamber
into the low-pressure passage is applied to the valve body in a
direction in which the valve body closes the low-pressure passage;
the valve body includes an inclined surface at a portion of the
valve body, to which the dynamic pressure is applied; and the
inclined surface is nonparallel to a plane, which is perpendicular
to a displacement direction of the valve body.
2. The pump according to claim 1, wherein the inclined surface is
formed in a tapered shape.
3. The pump according to claim 1, wherein the inclined surface has,
when viewed from a direction perpendicular to the displacement
direction of the valve body, an arc-like appearance.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2006-287520 filed on Oct.
23, 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a pump.
[0004] 2. Description of Related Art
[0005] In a conventional pump, timing, with which fuel starts to be
pressurized by a plunger, is controlled by a valve body blocking a
low-pressure passage communicating between a plunger chamber and a
low-pressure portion upon energization. The conventional pump is
used for a fuel injection apparatus for injecting fuel into a
compression-ignition engine. The conventional pump is configured
such that dynamic pressure of fuel flowing from the plunger chamber
toward the low-pressure passage is applied to the valve body in a
direction in which the valve body is closed (e.g.,
JP64-73166A).
[0006] In recent years, however, there has been an increasing
demand for high fuel injection pressure in the compression-ignition
engine. Accordingly, fuel leakage from an injector increases, so
that a necessary discharge amount is increased, thereby increasing
a cam lift in a fuel injection pump.
[0007] The large cam lift results in a high fuel feed rate, and
high-speed rotation of a cam shaft brings about high dynamic
pressure of fuel in the plunger chamber. The valve body of a magnet
valve is easily closed by itself due to the dynamic pressure. When
the valve body is closed by itself, the timing, with which fuel
starts to be pressurized by the plunger, becomes earlier than
target timing, and consequently the discharge amount of the pump
cannot be controlled.
SUMMARY OF THE INVENTION
[0008] The present invention addresses the above disadvantages.
Thus, in a pump configured such that dynamic pressure of fluid
flowing from a plunger chamber toward a low-pressure passage is
applied to a valve body of a magnet valve in a direction in which
the valve body closes the low-pressure passage, it is an objective
of the present invention to prevent the valve body from closing the
low-pressure passage by itself due to the dynamic pressure. The
magnet valve of the pump controls timing, with which fluid starts
to be pressurized by a plunger, by blocking the low-pressure
passage communicating between the plunger chamber and a
low-pressure portion with the valve body upon energization.
[0009] To achieve the objective of the present invention, there is
provided a pump including a cylinder, a low-pressure portion, a
plunger, and a magnet valve. The cylinder is formed with a plunger
chamber. Low-pressure fuel is supplied to the low-pressure portion.
A low-pressure passage communicates between the plunger chamber and
the low-pressure portion. The plunger reciprocates in the cylinder
to pressurize fluid in the plunger chamber, which is drawn from the
low-pressure portion. The magnet valve has a valve body. The magnet
valve blocks the low-pressure passage with the valve body when
energized, to control timing, with which fluid in the plunger
chamber starts to be pressurized by the plunger. Dynamic pressure
of fluid flowing from the plunger chamber into the low-pressure
passage is applied to the valve body in a direction in which the
valve body closes the low-pressure passage. The valve body includes
an inclined surface at a portion of the valve body, to which the
dynamic pressure is applied. The inclined surface is nonparallel to
a plane, which is perpendicular to a displacement direction of the
valve body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention, together with additional objectives, features
and advantages thereof, will be best understood from the following
description, the appended claims and the accompanying drawings in
which:
[0011] FIG. 1 is a sectional view illustrating a pump according to
a first embodiment of the present invention;
[0012] FIG. 2 is a sectional view illustrating a magnet valve in
FIG. 1;
[0013] FIG. 3 is a schematic view illustrating a substantial
portion of a valve body in a pump according to a second embodiment
of the present invention;
[0014] FIG. 4 is a schematic view illustrating a substantial
portion of a valve body in a pump according to a third embodiment
of the present invention;
[0015] FIG. 5 is a schematic view illustrating a substantial
portion of a valve body in a pump according to a fourth embodiment
of the present invention; and
[0016] FIG. 6 is a schematic view illustrating a substantial
portion of a valve body in a pump according to a fifth embodiment
of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment
[0017] A first embodiment of the present invention is described
below with reference to FIGS. 1, 2.
[0018] A pump according to the first embodiment is used as a
fuel-supply pump, which supplies high-pressure fuel to a common
rail storing high-pressure fuel in a fuel injection apparatus for
injecting fuel into a compression-ignition engine.
[0019] As shown in FIGS. 1, 2, a pump housing 10 has a cam chamber
10a, a cylindrical slider insertion hole 10b, and a cylindrical
cylinder insertion hole 10c. The cam chamber 10a is located on a
lower end side of the pump housing 10. The slider insertion hole
10b extends in a direction from the cam chamber 10a toward an upper
portion of the pump housing 10. The cylinder insertion hole 10c
extends in a direction from the slider insertion hole 10b to an
upper end surface of the pump housing 10.
[0020] A cam shaft 11, which is driven by the compression-ignition
engine (not shown: hereafter referred to as an internal combustion
engine), is disposed in the cam chamber 10a. The cam shaft 11
having a cam 12 is rotatably held by the pump housing 10.
[0021] A cylinder 13 is fitted into the cylinder insertion hole 10c
in such a manner that the cylinder 13 blocks the cylinder insertion
hole 10c. The cylinder 13 has a cylindrical insertion hole 13a, and
a cylindrical plunger 14 is reciprocatably inserted into the
insertion hole 13a. A plunger chamber 15 is defined by an upper end
surface of the plunger 14 and an inner circumferential surface of
the cylinder 13.
[0022] A seat 14a is connected to a lower end portion of the
plunger 14, and is pressed on a slider 17 by a spring 16. The
slider 17 is cylindrically formed, and is reciprocatably inserted
into the slider insertion hole 10b. A cam roller 18 is rotatably
joined to the slider 17, and is in contact with the cam 12. When
the cam 12 is rotated by rotation of the cam shaft 11, the plunger
14 is driven to reciprocate together with the seat 14a, the slider
17, and the cam roller 18.
[0023] A fuel pool 19 serving as a low-pressure portion is formed
between the cylinder 13 and the pump housing 10. Low-pressure fuel
discharged from a low-pressure supply pump (not shown) is supplied
to the fuel pool 19 through a low-pressure fuel pipe (not shown).
The fuel pool 19 communicates with the plunger chamber 15 via a
low-pressure communicating passage 13b formed in the cylinder 13
and a low-pressure passage 31a formed in a magnet valve 30, which
is described in greater detail hereinafter.
[0024] A high-pressure communicating passage 13c, which is in
constant communication with the plunger chamber 15, is formed in
the cylinder 13. The plunger chamber 15 is connected to a common
rail (not shown) through the high-pressure communicating passage
13c, a delivery valve 20, and a high-pressure fuel pipe (not shown)
in this order. The high-pressure communicating passage 13c and the
high-pressure fuel pipe constitute a high-pressure fuel supply
route.
[0025] The delivery valve 20 is joined to the cylinder 13 on a
downstream side of the high-pressure communicating passage 13c. The
delivery valve 20 includes a valve body 20a and a spring 20b. The
valve body 20a opens or closes the high-pressure fuel supply route.
The spring 20b urges the valve body 20a in a direction in which the
valve body 20a is closed. Fuel pressurized in the plunger chamber
15 displaces the valve body 20a in a direction in which the valve
body 20a is opened, against urging force of the spring 20b, and is
force fed into the common rail.
[0026] The magnet valve 30 is disposed in opposition to the upper
end surface of the plunger 14, and is threaded and fixed to the
cylinder 13 to block the plunger chamber 15.
[0027] The magnet valve 30 has a body 31, which includes the
low-pressure passage 31a and a seat portion 31b. One end portion of
the low-pressure passage 31a communicates with the plunger chamber
15, and the other end portion communicates with the low-pressure
communicating passage 13b. The seat portion 31b is formed in the
low-pressure passage 31a.
[0028] The magnet valve 30 has a solenoid 32, an armature 33, a
spring 34, a valve body 35, and a stopper 36. The solenoid 32
generates attraction force upon energization. The armature 33 is
attracted by the solenoid 32. The spring 34 urges the armature 33
in an opposite direction from a direction in which the armature 33
is attracted. The valve body 35 is displaced integrally with the
armature 33 and closes or opens the low-pressure passage 31a by
engaging or disengaging from the seat portion 31b, respectively.
The stopper 36 restricts displacement of the valve body 35 when the
valve body 35 is opened.
[0029] The stopper 36 is held between the magnet valve 30 and the
cylinder 13, and has a plurality of communicating holes 36a, which
communicate between the low-pressure passage 31a and the plunger
chamber 15.
[0030] Dynamic pressure (hereinafter referred to as overflowing
dynamic pressure) of fuel flowing from the plunger chamber 15 to
the low-pressure passage 31a is applied to the valve body 35 in a
direction in which the valve body 35 is closed. An inclined surface
35a is formed on a surface of the valve body 35, to which the
overflowing dynamic pressure is applied. The inclined surface 35a
is not parallel to a plane, which is perpendicular to a
displacement direction X of the valve body 35 (which, in the
present example, coincides with a direction in which the
overflowing dynamic pressure is applied).
[0031] More specifically, the inclined surface 35a is a tapered
surface having a diameter that increases at a constant rate in the
direction in which the overflowing dynamic pressure is applied.
That is, a portion of the valve body 35 including the inclined
surface 35a has a truncated cone shape. In other words, the
inclined surface 35a has, when viewed from a direction
perpendicular to the displacement direction X of the valve body 35,
a linear appearance. The inclined surface 35a of the valve body 35
has a tapered shape because it is easily formed. The inclined
surface 35a is inclined by, for example, 45 degrees with respect to
the displacement direction X.
[0032] The valve body 35 has a seat surface 35b, which engages or
disengages from the seat portion 31b of the body 31.
[0033] Workings of the pump having the above-described
configuration are described below. When the solenoid 32 of the
magnet valve 30 is not energized, the valve body 35 is displaced to
a position in which the valve body 35 is opened by urging force of
the spring 34. That is, the seat surface 35b of the valve body 35
is disengaged from the seat portion 31b, and thereby the
low-pressure passage 31a is opened.
[0034] When the plunger 14 is displaced in a downward direction in
FIG. 1 with the low-pressure passage 31a being opened, low-pressure
fuel discharged from the low-pressure supply pump is supplied to
the plunger chamber 15 through the fuel pool 19, the low-pressure
communicating passage 13b, and the low-pressure passage 31a in this
order.
[0035] Next, when the plunger 14 starts to be displaced in an
upward direction in FIG. 1, the plunger 14 moves to pressurize fuel
in the plunger chamber 15. However, when the plunger 14 starts to
be displaced upward, since the magnet valve 30 is not energized so
that the low-pressure passage 31a is opened, fuel in the plunger
chamber 15 overflows into the fuel pool 19 through the low-pressure
passage 31a and the low-pressure communicating passage 13b in this
order, and thereby is not pressurized.
[0036] When the magnet valve 30 is energized while fuel in the
plunger chamber 15 is overflowing, the armature 33 and the valve
body 35 are attracted, against the spring 34, so that the seat
surface 35b engages the seat portion 31b to block the low-pressure
passage 31a. Accordingly, fuel in the plunger chamber 15 stops
overflowing into the fuel pool 19, and starts to be pressurized by
the plunger 14. The delivery valve 20 is opened due to pressure of
fuel in the plunger chamber 15, so that fuel is force fed into the
common rail.
[0037] In the first embodiment, the inclined surface 35a is formed
on the surface of the valve body 35, to which the overflowing
dynamic pressure is applied. Accordingly, when the overflowing
dynamic pressure is applied to the valve body 35, the inclined
surface 35a generates components of force in the direction
perpendicular to the displacement direction X of the valve body 35,
to decrease force applied in a direction in which the valve body 35
is closed by itself. As a result, the closing of the valve body 35
by itself due to the overflowing dynamic pressure is restricted, so
that a fuel discharge amount of the pump is accurately
controlled.
Second Embodiment
[0038] A second embodiment of the present invention is described
below with reference to FIG. 3.
[0039] The inclined surface 35a of the valve body 35 in the first
embodiment has, when viewed from the direction perpendicular to the
displacement direction X of the valve body 35, a linear appearance.
However, an inclined surface 35a of a valve body 35 in the second
embodiment has, when viewed from the direction perpendicular to the
displacement direction X, an arc-like appearance. More
specifically, a diameter of the inclined surface 35a gradually
increases in the direction in which the overflowing dynamic
pressure is applied, and then sharply increases. In other words,
the diameter of the inclined surface 35a gradually increases on its
side near the plunger chamber 15, and sharply increases on its side
distant from the plunger chamber 15.
Third Embodiment
[0040] A third embodiment of the present invention is described
below with reference to FIG. 4.
[0041] The inclined surface 35a in the first embodiment has, when
viewed from the direction perpendicular to the displacement
direction X, a linear appearance. However, an inclined surface 35a
of a valve body 35 in the third embodiment has, when viewed from
the direction perpendicular to the displacement direction X, an
arc-like appearance. More specifically, a diameter of the inclined
surface 35a sharply increases in the direction in which the
overflowing dynamic pressure is applied, and then gradually
increases. In other words, the diameter of the inclined surface 35a
sharply increases on its side near the plunger chamber 15, and
gradually increases on its side distant from the plunger chamber
15.
Fourth Embodiment
[0042] A fourth embodiment of the present invention is described
below with reference to FIG. 5.
[0043] The inclined surface 35a in the first embodiment has, when
viewed from the direction perpendicular to the displacement
direction X, a linear appearance. However, an inclined surface 35a
of a valve body 35 in the fourth embodiment has, when viewed from
the direction perpendicular to the displacement direction X, an
arc-like appearance. More specifically, the inclined surface 35a
has a hemispherical shape.
Fifth Embodiment
[0044] A fifth embodiment of the present invention is described
below with reference to FIG. 6.
[0045] The inclined surface 35a of the valve body 35 in the first
embodiment is formed in a tapered shape. However, a valve body 35
in the fifth embodiment has a cylindrical portion 35c, and an
inclined surface 35a is formed such that a portion of the
cylindrical portion 35c, to which the overflowing dynamic pressure
is applied, is trimmed diagonally with respect to the displacement
direction X.
Other Embodiments
[0046] In the above-described embodiments, the present invention is
applied to the fuel-supply pump in the fuel injection apparatus for
the internal combustion engine. Nevertheless, the present invention
may be broadly applied to a pump, which draws and discharges
fluid.
[0047] Additional advantages and modifications will readily occur
to those skilled in the art. The invention in its broader terms is
therefore not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
* * * * *