Information
-
Patent Grant
-
6554590
-
Patent Number
6,554,590
-
Date Filed
Wednesday, April 18, 200123 years ago
-
Date Issued
Tuesday, April 29, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
US
- 417 505
- 123 506
- 251 12902
- 091 275
-
International Classifications
-
Abstract
A high pressure pump includes a cylinder body. The cylinder body has a cylinder and a valve recess communicated with the cylinder. A cover is attached to the cylinder body to surround the valve recess. A plunger reciprocates in the cylinder. An electromagnetic valve has a pressurizing chamber, a valve hole connected to the pressurizing chamber and a valve body. The valve body selectively opens and closes the valve hole. The electromagnetic valve is fixed to the cover. When fluid is pressurized in the pressurizing chamber, the valve hole is closed by the valve body and the plunger enters the pressurizing chamber. A seal ring is located between an outer surface of the electromagnetic valve and an inner surface of the valve recess. The seal ring seals the pressurizing chamber. This reliably seals a pressurizing chamber and improves the displacement efficiency.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a high pressure pump. More particularly, the present invention pertains to a high pressure pump that includes an electromagnetic valve that selectively opens and closes a pressurizing chamber defined adjacent to a cylinder in a cylinder body.
Japanese Unexamined Patent Publication No. 8-14140 discloses a high pressure pump that pressurizes fuel supplied to an internal combustion engine. This pump includes a plunger that is located in a cylinder, which is defined in a cylinder body. A pressurizing chamber is defined in the cylinder body adjacent to the plunger. The plunger is reciprocated to pressurize fuel in the pressurizing chamber. An electromagnetic valve is located adjacent to the pressurizing chamber. The valve is controlled to adjust the displacement of the pump.
A washer and a gasket are located between the opening of the cylinder and an end of the electromagnetic valve to seal the pressurizing chamber. The washer and the gasket are tightly held between the body of the valve the opening of the cylinder to so that the pressurizing chamber is reliably sealed. In other words, a relatively high pressure is applied to the opening of the cylinder, which may deform the cylinder. Since the cylinder is machined with a high precision, the deformation increases the friction between the cylinder and the plunger. Also, the orientation of the plunger may be displaced, which prevents smooth motion of the plunger.
To reduce the friction between the inner wall of the cylinder and the surface of the plunger, the clearance between the cylinder and the plunger must be relatively great to compensate for deformation of the cylinder. However, a greater clearance causes liquid to leak from the pressurizing chamber, which lowers the discharge efficiency of the high pressure pump.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a high pressure pump that reliably seals a pressurizing chamber and improves the displacement efficiency.
To attain the above-mentioned object, the present invention provides a high pressure pump. The high pressure pump includes a cylinder body. The cylinder body has a cylinder and a communication hole communicated with the cylinder. A cover is attached to the cylinder body to surround the communication hole. A plunger reciprocates in the cylinder. An electromagnetic valve has a pressurizing chamber, a valve hole connected to the pressurizing chamber and a valve body for selectively opening and closing the valve hole. The electromagnetic valve is fixed to the cover. When fluid is pressurized in the pressurizing chamber, the valve hole is closed by the valve body and the plunger enters the pressurizing chamber. A seal ring is located between an outer surface of the electromagnetic valve and an inner surface of the communication hole. The seal ring seals the pressurizing chamber.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
FIG. 1
is a cross-sectional view illustrating a high pressure pump according to a first embodiment of the present invention;
FIG. 2
is a diagram illustrating the fuel supply system of an internal combustion engine that has the high pressure pump of
FIG. 1
;
FIG. 3
is a cross-sectional view like
FIG. 1
when the valve body of the high pressure pump closes the valve hole;
FIG.
4
(A) is a cross-sectional view illustrating a high pressure pump according to a second embodiment, and
FIG.
4
(B) is a cross-sectional view illustrating a high pressure pump according to a third embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A high pressure pump
2
according to a first embodiment of the present invention will now be described with reference to
FIGS. 1
to
3
.
As shown in
FIG. 1
, the high pressure pump
2
includes a pump mechanism
4
and an electromagnetic valve
6
. The pump mechanism
4
includes a cover
8
, a cylinder body
10
and a plunger
12
. A cylinder
10
a
extends axially in the cylinder body
10
. A valve recess
10
b
is formed adjacent to the upper end of the cylinder
10
a.
The cover
8
is located on the cylinder body
10
and surrounds the valve recess
10
b.
The electromagnetic valve
6
has a cylindrical portion
6
a
at the lower end portion. The cylindrical portion
6
a
is received by the recess
10
b.
A pressurizing chamber
14
is defined in the cylindrical portion
6
a.
A plunger
12
is located in the cylinder
10
a
and is reciprocated by a cam
18
, which is attached to a camshaft
16
(see FIG,
2
). When reciprocated, the plunger
12
protrudes into and retracted from the pressurizing chamber
14
.
The electromagnetic valve
6
includes an annular coil
20
, a bobbin
22
, a stationary core
24
, an armature
26
, a poppet valve
28
, a housing
30
and a stopper
32
. The cylindrical portion
6
a
is formed in the lower portion of the housing
30
. The coil
20
is wound about the bobbin
22
. The bobbin
22
has a through hole
22
a.
The core
24
is fitted in the through hole
22
a
of the bobbin
22
.
The armature
26
is fixed to the upper end of the shaft of the poppet valve
28
. The armature
26
and the core
24
are coaxial and can enter the through hole
22
a
of the bobbin
22
. A compressed spring
34
is located between the core
24
and the armature
26
. The spring
34
urges the armature
26
and the poppet valve
28
toward the pressurizing chamber
14
.
The shaft of the poppet valve
28
extends through a shaft hole
31
formed in the housing
30
. The poppet valve
28
has a substantially conical valve body
28
a.
A valve hole
33
is formed in the electromagnetic valve
6
. The valve hole
33
is opened and closed by the valve body
28
a.
When current is not supplied to the coil
20
, the valve body
28
a
is separated from a valve seat
30
a,
which is defined about the lower opening of the valve hole
33
in the housing
30
, by the force of the spring
34
and abuts the stopper
32
. At this time, the valve hole
33
is opened. When an electronic control unit (ECU)
36
supplies current to the coil
20
, the core
24
, the armature
26
and the housing
30
produce a magnetic circuit. As a result, the armature
26
is moved toward the core
24
against the force of the spring
34
. Accordingly, the poppet valve
28
separates from the stopper
32
and the valve body
28
a
contacts the valve seat
30
a.
At this time, the valve hole
33
of the electromagnetic valve
6
is closed.
As shown in
FIGS. 1 and 3
, the stopper
32
faces the valve body
28
a
of the poppet valve
28
. Supply passages
38
are formed in the housing
30
. Holes
32
a
are formed in the stopper
32
. The holes
32
a
permit flow of fuel. When the electromagnetic valve
6
is opened as shown in
FIG. 1
, the holes
32
a
permit fuel to flow between the supply passages
38
and the pressurizing chamber
14
.
A gallery
40
is defined between the housing
30
and the cover
8
. A supply passage
38
is formed in the cover B. The supply passages
38
are connected to a low pressure passage
44
and a return passage
46
by the gallery
40
and the fuel passage
42
. The low pressure passage
44
is connected to a fuel tank
48
. As shown in
FIG. 2
, the high pressure fuel pump
2
receives fuel from a feed pump
48
a
in the fuel tank
48
. The return passage
46
is connected to a relief valve
52
. The relief valve
52
returns excess fuel from a fuel distribution pipe
50
to the pressurizing chamber
14
. The high pressure fuel pump
2
reuses fuel that is returned from the distribution pipe
50
through the relief valve
52
.
As shown in
FIGS. 1 and 3
, a large diameter portion
10
c
is formed in the upper portion of the cylinder
10
a.
The pressurizing chamber
14
communicates with the large diameter portion
10
c.
A high pressure passage
54
, a part of which is formed in the cylinder body
10
, is connected to the pressurizing chamber
14
through the large diameter portion
10
c.
In the cylinder body
10
, the high pressure passage
54
extends perpendicular to the pressurizing chamber
14
. A check valve
56
is located in the high pressure passage
54
. The pressurizing chamber
14
is connected to the fuel distribution pipe
50
by the high pressure passage
54
and the check valve
56
.
The check valve
56
permits fuel to flow from the pressurizing chamber
14
to the fuel distribution pipe
50
. The check valve
56
also prevents fuel from flowing from the distribution pipe
50
to the pressurizing chamber
14
. If the plunger
12
projects into the pressurizing chamber
14
when the electromagnetic valve
6
is closed, pressure of fuel in the pressurizing chamber
14
is increased. At this time, the pressurized fuel is sent to the distribution pipe
50
through the high pressure passage
54
and the check valve
56
. When the plunger
12
is retracted from the pressurizing chamber
14
, fuel is drawn to the pressurizing chamber
14
from the fuel passage
42
through the gallery
40
, the supply passage
38
and the holes
32
a.
A flange
30
b
is formed in the upper portion of the housing
30
. Bolt holes
30
c
(only one is shown in
FIG. 1
) are formed in the flange
30
b.
Threaded holes
8
a,
the number or which corresponds to the number of the bolt holes
30
c,
are formed in the cover
8
. A bolt
58
extends through each bolt hole
30
c
and threaded to the corresponding threaded hole
8
a,
which fastens the electromagnetic valve
6
to the pump mechanism
4
.
The diameter of each bolt hole
30
c
is greater than the diameter of the shaft
58
a
of each bolt
58
by a predetermined value. Therefore, before the bolts
58
are fastened tightly to the threaded holes
8
a,
the housing
30
can be moved relative to the cover
8
within a predetermined range. The housing
30
is fixed to the cover
8
by fastening the bolts
58
.
An annular groove
6
b
is formed in the circumference of the cylindrical portion
6
a
of the electromagnetic valve
6
. An O-ring
60
is fitted in the groove
6
b.
The O-ring
60
is elastically deformed and is supported between the surface of The cylindrical portion
6
a
and the recess
10
b
to seal the pressurizing chamber
14
. The O-ring
60
is made of elastic material such as silicone rubber.
The electromagnetic valve
6
is installed in the following manner. First, the cover
8
, the cylinder body
10
and other parts are integrated by an assembler (not shown) to form a pump mechanism
4
.
Then, the cylindrical portion
6
a
of the electromagnetic valve
6
is inserted into the recess
10
b
of the cylinder body
10
. A small clearance exists between the cylindrical portion
6
a
and the recess
10
b.
However, the O-ring
60
, which is fitted about the cylindrical portion
6
a,
contacts the recess
10
b
and is elastically deformed to seal the pressurizing chamber
14
. As the O-ring
60
is deformed, the axis of the cylindrical portion
6
a
matches with the axis of the recess
10
b.
Since the diameter of the bolt holes
30
c
is greater than that of the shafts
58
a
of the bolts
58
, the cylindrical portion
6
a
can be moved radially within a predetermined range even if the bolts
58
is partially engaged with the threaded holes
8
a.
Therefore, the position of the cylindrical portion
6
a
is determined by the O-ring
60
. Thereafter, the bolts
58
are fastened to fix the flange
30
b
to the cover
8
.
The gallery
40
is sealed by an O-ring
62
that is located between the cover
8
and the flange
30
b
and an O-ring
64
that is located between the cover
8
and the cylinder body
10
.
As shown in
FIG. 2
, the high pressure fuel pump
2
is used in a fuel supply system of an in-cylinder fuel injection type gasoline engine
68
. In the engine
68
, fuel is directly injected into combustion chambers (not shown). When the engine
68
is running, the camshaft
16
, which is coupled to the crankshaft, is rotated. Accordingly, the cam
16
is rotated, which reciprocates the plunger
12
in the cylinder
10
a.
When the plunger
12
is moved downward away and retracts from the pressurizing chamber
14
as shown by an arrow in
FIG. 1
, the volume of the pressurizing chamber
14
is increased. This stroke is referred to as suction stroke. In the suction stroke, fuel is supplied to the pressurizing chamber
14
from the low pressure passage
44
or from the return passage
46
through the fuel passage
42
, the gallery
40
, the supply passage
38
and the holes
32
a.
When the plunger
12
is moved upward into the pressurizing chamber
14
, the volume of the pressurizing chamber
14
is decreased. This stroke will be referred to as a pressurizing stroke. If the electromagnetic valve
6
is opened during a pressurizing stroke, fuel in the pressurizing chamber
14
is returned to the fuel passage
42
through the holes
32
a,
the supply passage
38
and the gallery
40
. The valve body
28
a
of the poppet valve
28
closes the valve hole
33
at an appropriate timing during the pressurizing stroke, which raises the pressure in the pressurizing chamber
14
. The pressurized fuel in the pressurizing chamber
14
is supplied to the fuel distribution pipe
50
through the high pressure passage
54
, the check valve
56
. Accordingly, the pressurized fuel is supplied to fuel injectors
66
, which are shown in FIG.
2
. That is, fuel is supplied to each fuel injector
66
when the corresponding compression chamber is in the compression stroke. The timing at which the electromagnetic valve
6
closes the valve hole
33
is controlled by the ECU
36
in accordance with the pressure detected by a fuel pressure sensor
50
a
located in the distribution pipe
50
and the amount of fuel injected from the fuel injectors
66
. In this manner, the flow rate of pressurized fuel that is sent from the high pressure pump
2
to the distribution pipe
50
is controlled such that the pressure of injected fuel is appropriate.
The embodiment of
FIGS. 1
to
3
has the following advantages.
The pressurizing chamber
14
is sealed by the O-ring
60
, which is located between the cylindrical portion
6
a
of the electromagnetic valve
6
and the recess
10
b.
Therefore, unlike the prior art high pressure valves, the electromagnetic valve
6
need not be pressed in the axial direction toward the cylinder body
10
. Thus, the part surrounding the cylinder
10
a
does not receive load from the valve
6
. As a result, the cylinder
10
a
is not deformed.
The pressurizing chamber
14
is sealed without deforming the cylinder
10
a.
Thus, the clearance between the cylinder
10
a
and the plunger
12
can be reduced, which increases the discharge efficiency.
The cylindrical portion
6
a
of the electromagnetic valve
6
is inserted into the recess
10
b
of the cylinder body
10
. The volume of the pressurizing chamber
14
is relatively small. Specifically, the volume of the pressurizing chamber
14
is smaller than the volume of the recess
10
b
substantially by the volume of part of the cylindrical portion
6
a
that is located in the recess
10
b.
Therefore, as the plunger
12
strokes, the pressure of fuel in the pressurizing chamber
14
is quickly increased, which improves the discharge efficiency.
When the plunger
12
projects into the pressurizing chamber
14
, the plunger
12
must be accurately guided into the pressurizing chamber
14
by the cylinder
10
a.
In the embodiment of
FIGS. 1
to
3
, the cylinder
10
a
is prevented from being deformed. Thus, the plunger
12
is accurately and easily guided into the pressuring chamber
14
by the cylinder
10
a.
The clearance between the pressurizing chamber
14
and the plunger
12
can be reduced. Accordingly, the volume of the pressurizing chamber
14
is reduced, which improves the discharge efficiency.
The O-ring
60
is located between the outer surface of the electromagnetic valve
6
and the wall of the recess
10
b.
When the electromagnetic valve
6
is installed by inserting the cylindrical portion
6
a
into the recess
10
b
of the cylinder body
10
, the elastic force of the O-ring
60
equally acts on the cylinder body
10
in the radial directions. Therefore, the axis of the cylindrical portion
6
a
is matched with the axis of the recess
10
b.
In other words, the O-ring
60
permits the electromagnetic valve
6
to be accurately installed in the cylinder body
10
. Also, the diameter of the bolt holes
30
c
is greater than the diameter of the shafts
58
a
of the bolts
58
. Therefore, the shape and the position of each bolt
58
need not be highly accurate. That is, the bolts
58
do not require high machining accuracy. Also, the position of each threaded hole
8
a
need not be highly accurate. This structure reduces the machining cost of the high pressure pump
2
.
Since the valve
6
is installed with a high accuracy in the recess
10
b,
the clearance between the pressurizing chamber
14
and the plunger
12
can be reduced compared to the prior art pumps. As a result, leak of fuel from the pressurizing chamber
14
is reduced. Thus, as the plunger
12
strokes, the pressure of fuel is quickly increased, which improves the discharge efficiency.
The electromagnetic valve
6
is fixed to the cover
8
, which is separately formed from the cylinder body
10
. Therefore, deformation of the cylinder
10
a
due to installation of the electromagnetic valve
6
is decreased. As a result, the clearance between the cylinder
10
a
and the plunger
12
can be further reduced, which improves the discharge efficiency.
FIG.
4
(A) illustrates a second embodiment. The second embodiment is different from the embodiment of
FIGS. 1
to
3
in that an annular absorber
70
is located between the lower face
6
c
of the cylindrical portion
6
a
of the electromagnetic valve
6
and the bottom
10
d
of the recess
10
b.
The absorber
70
prevents pressure pulsation.
The absorber
70
is made of a material that is durable against fuel and pressure pulsation. For example, the absorber
70
is made of a metal or a resin. The axial dimension of the absorber
70
is determined such that the force of the absorber
70
does not deform the cylinder
10
a.
For example, axial dimension of the absorber
70
is smaller than the distance between the lower face
6
c
and the bottom
10
d.
FIG.
4
(B) illustrates a third embodiment. In the third embodiment, an annular absorber
72
that has a rectangular cross section is used.
In addition to the advantages of the embodiment shown in
FIGS. 1
to
3
, the embodiments of FIGS.
4
(A) and
4
(B) have the following advantages.
If the valve body
28
a
of the poppet valve
28
contacts the valve seat
30
a
when the plunger
12
is being pressurizing fuel in the pressurizing chamber
14
, the pressure of the fuel is abruptly increased. Then, pressure pulsation is transmitted from the pressurizing chamber
14
to the O-ring
60
through the space between the cylindrical portion
6
a
and the recess
10
b.
However, the absorbers
70
,
72
of FIGS.
4
(A) and
4
(B) prevent pressure pulsation from being transmitted to the O-ring
60
. Therefore, wear of the O-ring
60
is reduced, which extends the life of the O-ring
60
.
The present invention may be applied to other types of high pressure pumps. For example, the present invention may be applied to a high pressure pump that changes the displacement by adjusting the opening timing of an electromagnetic valve during suction stroke to control the amount of fuel that is drawn to a pressurizing chamber.
The present invention may be applied to a high pressure pump that pressurizes fluid other than fuel.
Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.
Claims
- 1. A high pressure pump comprising:a cylinder body, wherein the cylinder body has a cylinder and a communication hole communicated with the cylinder; a cover attached to the cylinder body to surround the communication hole; a plunger that reciprocates in the cylinder; an electromagnetic valve having a pressurizing chamber, a housing attached to the cover, wherein the housing has a valve seat and a valve hole connected to the pressurizing chamber, and a valve body for selectively contacting to and separating from the valve seat to selectively open and close opening and closing the valve hole, wherein the electromagnetic valve is fixed to the cover, wherein, when fluid is pressurized in the pressurizing chamber, the valve hole is closed by the valve body and the plunger enters the pressurizing chamber; and a seal ring located between an outer surface of the electromagnetic valve and an inner surface of the communication hole, wherein the seal ring seals the pressurizing chamber, wherein the electromagnetic valve has a cylindrical portion, which is located in the communication hole, wherein the pressurizing chamber is formed in the cylindrical portion, and wherein the seal ring is located between an outer surface of the cylindrical portion and the inner surface of the communication hole.
- 2. The high pressure pump according to claim 1, wherein the seal ring positions the electromagnetic valve such that the communication hole and the electromagnetic valve are coaxial.
- 3. The high pressure pump according to claim 1, wherein, when the valve hole is opened by the valve body, the valve body enters the pressurizing chamber, wherein, when the valve hole is closed, the valve body is away from the pressurizing chamber.
- 4. The high pressure pump according to claim 1, wherein an absorber is located between the inner surface of the communication hole and the outer surface of the cylindrical portion, wherein the absorber prevents transmission of pressure pulsation to the seal ring.
- 5. The high pressure pump according to claim 1, wherein the seal ring is O-ring made of rubber.
- 6. The high pressure pump according to claim 1, wherein a part that the electromagnetic valve corresponds to the seal ring is exposed to the pressurizing chamber.
- 7. A high pressure pump comprising:a cylinder body, wherein the cylinder body has a cylinder and a communication hole communicated with the cylinder; a cover attached to the cylinder body to surround the communication hole, wherein the cover has a through hole; a plunger that reciprocates in the cylinder; an electromagnetic valve having a pressurizing chamber, a housing attached to the cover, wherein the housing has a valve seat and a valve hole connected to the pressurizing chamber, and a valve body for selectively contacting to and separating from the valve seat to selectively open and close opening and closing the valve hole, wherein, when fluid is pressurized in the pressurizing chamber, the valve hole is closed by the valve body and the plunger enters the pressurizing chamber; a fastener located in the through hole cover, wherein the fastener fixes the electromagnetic valve to the cover; and a seal ring located between an outer surface of the electromagnetic valve and an inner surface of the communication hole, wherein the seal ring seals the pressurizing chamber, wherein the electromagnetic valve has a cylindrical portion, which is located in the communication hole, wherein the pressurizing chamber is formed in the cylindrical portion, and wherein the seal ring is located between an outer surface of the cylindrical portion and the inner surface of the communication hole.
- 8. The high pressure pump according to claim 7, wherein the fastener is annular, and wherein the diameter of the through hole is greater than outer diameter of the fastener.
- 9. The high pressure pump according to claim 7, wherein the seal ring positions the electromagnetic valve such that the communication hole and the electromagnetic valve are coaxial.
- 10. The high pressure pump according to claim 7, wherein, when the valve hole is opened by the valve body, the valve body enters the pressurizing chamber, wherein, when the valve hole is closed, the valve body is away from the pressurizing chamber.
- 11. The high pressure pump according to claim 7, wherein an absorber is located between the inner surface of the communication hole and the outer surface of the cylindrical portion, wherein the absorber prevents transmission of pressure pulsation to the seal ring.
- 12. The high pressure pump according to claim 7, wherein the seal ring is O-ring made of rubber.
- 13. The high pressure pump according to claim 7, wherein a part that the electromagnetic valve corresponds to the seal ring is exposed to the pressurizing chamber.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-116418 |
Apr 2000 |
JP |
|
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