Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2002-04-08
2004-03-16
Look, Edward K. (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C029S890131
Reexamination Certificate
active
06705590
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fuel supply apparatus, and more particularly to a fuel supply apparatus for supplying a fuel under a high pressure to a fuel injection type internal combustion engine, for example, an automobile engine.
2. Description of the Related Art
FIGS. 7-9
are drawings for describing a general fuel supply system for a fuel injection type internal combustion engine.
FIG. 7
schematically illustrates this fuel supply system.
FIG. 8
is a sectional view of a principal portion of a fuel supply apparatus included in the same fuel supply system, and
FIG. 9
an enlarged sectional view of a part of what is shown in FIG.
8
. Referring to
FIGS. 7-9
, the fuel supply system has as main elements a fuel tank
1
, a fuel supply apparatus
6
and fuel injection valves
10
, the fuel supply apparatus
6
having a filter
11
, a low-pressure damper
12
, a suction valve
13
, a pump
16
, a discharge valve
14
and an electromagnetic valve
40
.
A fuel
2
in the fuel tank
1
is sent out by a low-pressure pump
3
, and pressure-regulated in a low-pressure regulator
5
via a filter
4
, the resultant fuel being supplied to the fuel supply apparatus
6
. The pressure of only such a quantity of the fuel
2
thus supplied to the apparatus that is necessary for fuel injection is increased to a high level by the same apparatus
6
, and the resultant fuel is supplied to the interior of a common rail
9
of an internal combustion engine (not shown). The fuel is then injected in the form of a high-pressure mist from the fuel injection valves
10
into cylinders (not shown) of an internal combustion engine. A necessary quantity of the fuel during this injection operation is determined by a control unit (not shown), and controlled by the electromagnetic valve
40
, an excessive fuel being relieved from the electromagnetic valve
40
to the portion of a fuel passage which is between the low-pressure damper
12
and suction valve
13
. A reference numeral
7
in
FIG. 7
denotes a filter, and
8
a high-pressure relief valve. When the interior of the common rail
9
comes to have an abnormal pressure, the high-pressure relief valve
8
is opened to prevent the common rail
9
and fuel injection valve
10
from being broken.
Referring to
FIG. 8
showing a principal portion of the fuel supply apparatus
6
, the pump
16
includes a cylinder
25
installed in a casing
30
and provided therein with a pressure chamber
24
having a fuel suction port
22
and a fuel discharge port
23
, a plunger
26
adapted to be moved vertically in the interior of the cylinder
25
and thereby vary the volume of the pressure chamber
24
, and tappet
28
joined to the plunger
26
. A driving cam (not shown) provided coaxially with an engine cam shaft (not shown) is engaged with a pressure receiving surface at a lower end in the drawing of the tappet
28
, and the tappet
28
and plunger
26
are moved vertically in accordance with a rotation of this driving cam to cause the volume of the pressure chamber
24
to be varied.
Referring to
FIGS. 8-9
, the electromagnetic valve
40
has a core
41
and an electromagnetic coil
42
, and is fixed to a housing
43
. The core
41
and housing
43
are welded together via a connecting ring
50
having an L-shaped cross section. Namely, the connecting ring
50
has a first portion
51
welded to the core
41
, and a second portion
52
welded to the housing
43
. In other words, the core
41
and first portion
51
are welded at a welded portion
61
, and the housing
43
and second portion
52
at a welded portion
62
respectively. In
FIG. 9
, an illustration of the electromagnetic coil
42
is omitted so that such welded condition is understood easily.
In order to connect the core
41
and housing
43
together, the connecting ring
50
is press fitted therebetween first, and each abutting portion is welded over the whole circumference thereof by a regular method to form the welded portions
61
,
62
.
The welded portions
61
,
62
contract while they cool down after the welding operation finishes, and the connecting ring
50
of a low strength is deformed so as to be drawn to the core
41
and housing
43
as shown by arrows in
FIG. 9
, i.e., in such a manner that the first and second portions
51
,
52
thereof are drawn toward the core
41
and housing
43
respectively. The degree of this deformation is not uniform from a welding starting position toward a welding finishing position in the circumferential direction of the connecting ring
50
. As a result, an abominable problem arises, i.e., the core
41
inclines with respect to the axis thereof to cause the performance of the electromagnetic valve
40
to become unstable.
In the welded portions
61
,
62
, especially, in the welded portion
62
, stress including a large tensile component resides on the surface thereof due to the above-mentioned contraction thereof, and this residual stress causes a crack to occur in the welded portion
62
. The connecting ring
50
in use is formed in many cases of a nonmagnetic steel material, for example, stainless steel of austenite. Since the linear expansion coefficient of this material is larger than those of other metal materials, the problems mentioned above stand out more. Furthermore, when a pressure is applied to the interior of a fuel passage of the electromagnetic valve
40
, a clearance occurs between contact surfaces of the connecting ring
50
and housing
43
, especially, in the radial direction due to the deformation mentioned above of the connecting ring
50
. The above-mentioned pressure works in such a clearance, and a pressure receiving area gradually increases, the degree of deformation of the connecting ring also increasing. Therefore, there is the possibility that fatigue failure occurs in the above-mentioned deformed portions during an operation of the electromagnetic valve
40
to give rise to the leakage of the fuel.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned circumstances, and provides a fuel supply apparatus which has solved the problem occurring after the welding of a connecting ring, by which a core of an electromagnetic valve and a housing are connected together, finishes of the deformation of the connecting ring and a crack in a welded portion.
According to an aspect of the present invention, the fuel supply apparatus has a core of an electromagnetic valve and a housing which are welded together via a connecting ring having an L-shaped cross section, the housing being provided in the portion thereof which is in the vicinity of the part of the housing on which the housing is welded to the connecting ring therefor with a groove for at least reducing the degree of deformation of the connecting ring occurring after the welding operation finishes.
According to another aspect of the present invention, the fuel supply apparatus is in accordance with the above invention, in which the connecting ring has a first portion welded to the core, and a second portion welded to the housing, the thickness of the second portion being larger than that of the first portion.
According to still another aspect of the present invention, the fuel supply apparatus is in accordance with the second-mentioned invention, in which the thickness of the second portion is larger than the depth of a cut made in a corner of the housing and adapted to have the second portion fitted therein.
According to a further aspect of the present invention, the fuel supply apparatus is in accordance with the first-mentioned invention, in which an open surface of the welded portion of the housing and connecting ring project in a swollen state.
According to another aspect of the present invention, the fuel supply apparatus is in accordance with any one of the first to fourth inventions, in which the groove is cross-sectionally so shaped that the distance between both of opposite side walls thereof decreases gradually toward a bottom thereof.
According to still another aspect of
Onishi Yoshihiko
Tochiyama Sigenobu
Fristoe Jr. John K.
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
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