Receptacles – High-pressure-gas tank
Reexamination Certificate
1998-11-02
2002-05-07
Miller, Carl S. (Department: 3747)
Receptacles
High-pressure-gas tank
C220S612000, C123S467000
Reexamination Certificate
active
06382456
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This present invention relates to a sealing device for a high-pressure vessel, and especially to a sealing device for a surge absorption device, mainly in a high-pressure fuel pump such as is used in a cylinder-injected engine, capable of reducing surge amplitude and thus enabling stabilization of the amount of fuel injected and stabilization of the engine cycle.
2. Description of the Related Art
Diesel engines are the most widely known of the so-called “cylinder-injected” or “direct injection engines”, engines in which fuel is injected into the engine cylinder, but in recent years cylinder-injected spark ignition engines (gasoline engines) have also been proposed. Cylinder-injected engines of this kind demand that fuel pressure surges be minimized to maintain sufficiently high fuel injection pressure and ensure stable injection. To this end, compact single-cylinder high-pressure fuel pumps have been proposed which are of simple construction and inexpensive to manufacture. However, because there is only one plunger in the single-cylinder system, there are surges of quite some amplitude in the pressure of the fuel discharged, and so surge absorption devices with metal bellows or diaphragms have been proposed to absorb these surges.
FIG. 10
shows a high-pressure fuel supply system provided with a high-pressure accumulator which is a good example of a surge absorption device to which the sealing device of the present invention can be applied. In
FIG. 10
, a delivery pipe
1
, which is a fuel injection apparatus, is provided with a plurality of injectors
1
a
corresponding to the number of engine cylinders, which are not shown. A high-pressure fuel pump assembly
200
provided with a high-pressure fuel pump
3
is disposed between the delivery pipe
1
and a fuel tank
2
. The delivery pipe
1
and the high-pressure fuel pump
3
are connected by a high-pressure fuel passage
4
and the high-pressure fuel pump
3
and the fuel tank
2
are connected by a low-pressure fuel passage
5
. Together, the high-pressure fuel passage
4
and the low-pressure fuel passage
5
compose a fuel passage connecting the delivery pipe
1
to the fuel tank
2
. A filter
6
is disposed in the fuel intake of the high-pressure fuel pump
3
. A check valve
7
is disposed on the fuel discharge side of the high-pressure fuel pump
3
. A drain
8
attached to the high-pressure fuel pump
3
returns to the fuel tank
2
.
A low-pressure fuel pump
10
is disposed at the end of the low-pressure fuel passage
5
close to the fuel tank
2
. A filter
11
is disposed in the fuel intake of the low-pressure fuel pump
10
. A check valve
12
is disposed in the low-pressure fuel passage
5
on the fuel discharge side of the low-pressure fuel pump
10
. A low-pressure regulator
14
is disposed in the low-pressure fuel passage
5
between the high-pressure fuel pump
3
and the low-pressure fuel pump
10
. A filter
15
is disposed in the fuel intake of the low-pressure regulator
14
. A drain
16
attached to the low-pressure regulator
14
returns to the fuel tank
2
.
The high-pressure fuel pump
3
increases the pressure of the fuel supplied to it by the low-pressure fuel passage
5
and discharges it to the delivery pipe
1
. A dumper
30
is disposed on the low-pressure fuel passage
5
side of the high-pressure fuel pump
3
, i.e., the low-pressure side. A high-pressure accumulator
70
and a high-pressure regulator
32
are disposed on the high-pressure side of the high-pressure fuel pump
3
. A drain
33
attached to the high-pressure regulator
32
returns to the fuel input side of the high-pressure fuel pump
3
.
FIG. 11
is a cross-section showing details of the high-pressure fuel pump assembly
200
when fully assembled, comprising the high-pressure fuel pump
3
, dumper
30
, high-pressure accumulator
70
, high-pressure regulator
32
, filter
6
, and check valve
7
. In
FIG. 11
, a recess portion
40
c
is formed in the casing
40
on the right-hand side of the diagram, and the high-pressure accumulator
70
is secured to the recess portion
40
c
. A discharge passage
4
b
which communicates with a discharge passage
4
a
is formed as a recess in the bottom of the recess portion
40
c.
FIG. 12
is a cross-section showing details of the high-pressure accumulator
70
, which is a surge absorption device to which the sealing device of the present invention can be applied. The high-pressure accumulator
70
is provided with a case
85
, which is a high-pressure vessel roughly the shape of a thick disk, a flexible disk-shaped metal diaphragm
86
, supported by and sealed against the case
85
around its perimeter portion so that together they form a high-pressure chamber
71
, and a disk-shaped plate
89
, which is a stopper defining the limit of deformation of the diaphragm
86
.
The case
85
has a comparatively thin perimeter portion
72
, which supports and seals the outer perimeter portion of the diaphragm
86
by a sealing weld, and a comparatively thick central portion
73
, in which the high-pressure chamber
71
is formed. A male thread
91
is formed on the cylindrical outer surface of the peripheral portion
72
, and a comparatively shallow saucer-shaped recess portion
74
, which gradually deepens from the perimeter portion towards the central portion in a smooth curve to allow the diaphragm
86
to deform towards the high-pressure chamber
71
, is formed in the portion in close contact with the diaphragm
86
. An approximately-cylindrical recess portion
75
, which communicates with the shallow saucer-shaped recess portion
74
at the central portion, is formed in the central portion
73
and, together with the saucer-shaped recess portion
74
, forms the high-pressure chamber
71
.
A gas charge inlet
84
of circular cross-section about its central axis is formed in the ceiling portion of the high-pressure chamber
71
to introduce high-pressure gas to the high-pressure chamber
71
of the case
85
and seal it in, and a special thread member
87
is disposed therein as a sealing device to seal the gas charge inlet
84
. The gas charge inlet
84
is provided with a small-diameter portion
76
of comparatively small diameter on the high-pressure side facing the high-pressure chamber
71
, and a large-diameter portion
77
of comparatively large diameter on the low-pressure side facing the exterior of the case
85
. A shoulder portion
78
is formed between the small-diameter portion
76
and the large-diameter portion
77
, and a female thread is formed on the inner circumference surface of the small-diameter portion
76
. An annular groove
79
is disposed in the shoulder portion
78
to accommodate an O-ring
88
.
The special thread member
87
inserted into the gas charge inlet
84
has a large-diameter portion
81
, which is inserted into the large-diameter portion
77
of the gas charge inlet
84
, and a small-diameter portion
80
, which has a thread around its outer cylindrical surface which engages the female thread of the small-diameter portion
76
, and the large-diameter portion
81
inserted into the gas charge inlet
84
presses on the O-ring
88
and seals the gas charge inlet
84
.
The perimeter portion of the diaphragm
86
is sealed and supported on the outer perimeter portion of the case
85
by a weld portion
82
made by an electron beam or the like. In addition a saucer-shaped plate
89
is disposed on the diaphragm
86
as a stopper to define the limit of deformation of the diaphragm
86
, and the plate
89
is also fastened around its circumference by the weld portion
82
. A recess portion
83
shaped like one side of a convex lens is formed on the inner face of the plate
89
, which gradually deepens from the outer perimeter portion of the diaphragm
86
towards the center, and communicating holes
90
are formed as fuel channels which communicate with the recess portion
83
.
The case
85
, the metal diaphragm
86
, and the plate
89
are all hermetically sealed and bonded to each other around their outer
Arisue Kazuhiro
Nishitani Shoichiro
Onishi Yoshihiko
Suzuki Hiroyuki
Miller Carl S.
Sughrue & Mion, PLLC
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