Expansible chamber devices – With guide or seal on cylinder end portion for piston or... – Non-metallic seal means between piston or member and end...
Reexamination Certificate
2002-11-04
2004-06-22
Look, Edward K. (Department: 3745)
Expansible chamber devices
With guide or seal on cylinder end portion for piston or...
Non-metallic seal means between piston or member and end...
Reexamination Certificate
active
06752068
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high pressure fuel supply apparatus chiefly for use in a cylinder fuel injection engine or the like.
2. Description of the Related Art
FIG. 10
is a configuration diagram showing a fuel supply system in an internal combustion engine for a vehicle, including a related-art high pressure fuel supply apparatus. In
FIG. 10
, fuel
2
in a fuel tank
1
is delivered from the fuel tank
1
by a low pressure pump
3
, passed through a filter
4
, adjusted in pressure by a low pressure regulator
5
, and then supplied to a high pressure fuel supply apparatus
6
which is a high pressure pump. Only a flow rate of the fuel
2
required for fuel injection is boosted by the high pressure fuel supply apparatus
6
, and supplied into a delivery pipe
9
of a not-shown internal combustion engine. A surplus of the fuel
2
is relieved between a low pressure damper
12
and a suction valve
13
by an electromagnetic valve
17
.
In addition, the required fuel flow rate is determined by a not-shown control unit, which also controls the electromagnetic valve
17
. The high pressure fuel supplied thus is injected into a cylinder of the internal combustion engine in the form of high pressure mist from a fuel injection valve
10
connected to the delivery pipe
9
. When abnormal pressure (high relief valve opening pressure) is placed in the delivery pipe
9
, a filter
7
and a high pressure relief valve
8
are opened to prevent the delivery pipe
9
from being broken.
The high pressure fuel supply apparatus
6
which is a high pressure pump, has a filter
11
for filtering the supplied fuel, a low pressure damper
12
for absorbing the pulsation of the low pressure fuel, and a high pressure fuel pump
16
for pressurizing the fuel supplied through the suction valve
13
and discharging the high pressure fuel through a discharge valve
14
.
FIG. 11
is a sectional view showing a related-art high pressure fuel supply apparatus. In
FIG. 11
, the high pressure fuel supply apparatus
6
has a casing
61
, a high pressure fuel pump
16
, an electromagnetic valve
17
, and a low pressure damper
12
, integrally. The high pressure fuel pump
16
is a plunger pump provided in the casing
61
.
A fuel pressurizing chamber
163
surrounded by a sleeve
160
and a plunger
161
inserted slidably in the sleeve
160
is formed in the high pressure fuel pump
16
. The other end of the plunger
161
abuts against a tappet
164
, and the tappet
164
abuts against a cam
100
so as to drive the high pressure fuel pump
16
. The cam
100
is provided integrally or coaxially with a cam shaft
101
of the engine so as to reciprocate the plunger
161
along the profile of the cam
100
in cooperation with the rotation of a crank shaft of the engine. The volume of the fuel pressurizing chamber
163
is changed by the reciprocating motion of the plunger
161
so that the fuel boosted to high pressure is discharged from the discharge valve
14
.
In the high pressure fuel pump
16
, a plate
162
, the suction valve
13
and the sleeve
160
are held between the casing
61
and an end surface of a spring guide
165
, and fastened with a bolt
180
. The plate
162
forms a fuel suction port
162
a
for sucking fuel from the low pressure damper
12
to the fuel pressurizing chamber
163
, and a fuel-discharge port
162
b
for discharging the fuel from the fuel pressurizing chamber
163
.
The suction valve
13
shaped into a thin plate is formed in the fuel suction port
162
a
. The discharge valve
14
is provided on the fuel discharge port
162
b
so as to communicate with the delivery pipe
9
through a high pressure fuel discharge passageway
62
provided in the casing
61
. In addition, in order to suck fuel, a spring
167
for pushing the plunger
161
down in a direction to expand the fuel pressurizing chamber
163
is disposed in the state where the spring
167
has been compressed between the spring guide
165
and a spring holder
168
. An oil seal
169
is provided to isolate the fuel in the fuel pressurizing chamber
163
from the lubricating oil of the engine.
The electromagnetic valve
17
has an electromagnetic valve body
170
, a valve seat
173
, a valve
174
, and a compression spring
175
. The electromagnetic valve body
170
is incorporated in the casing
61
of the high pressure fuel supply apparatus
6
so as to have a fuel channel
172
inside the electromagnetic valve body
170
. The valve seat
173
is provided in the fuel channel
172
of the electromagnetic valve body
170
. The valve
174
is held on/off the valve seat
173
in the electromagnetic valve body
170
so as to close/open the fuel channel
172
. The compression spring
175
presses the valve
174
onto the valve seat
173
.
At a point of time when a flow rate requested from a not-shown control unit has been discharged in a discharge stroke of the high pressure fuel pump
16
, a solenoid coil
171
of the electromagnetic valve
17
is excited to open the valve
174
. Thus, the fuel
2
in the fuel pressurizing chamber
163
is released to the low pressure side between the low pressure damper
12
and the suction valve
13
so that the pressure in the fuel pressurizing chamber
163
is reduced to be not higher than the pressure in the delivery pipe
9
. Thus, the discharge valve
14
is closed. After that, the valve
174
of the electromagnetic valve
17
is opened till the high pressure fuel pump
16
proceeds to a suction stroke. The timing to open the electromagnetic valve
17
is controlled so that the amount of fuel discharged into the delivery pipe
9
can be adjusted.
However, the related-art high pressure fuel supply apparatus has problems as follows.
FIG. 12
is an enlarged sectional view showing the vicinity of the oil seal in the high pressure fuel pump of the related-art high pressure fuel supply apparatus. As shown in
FIG. 12
, the oil seal
169
is constituted by an annular portion
169
a
, a seal portion
169
b
made of rubber, and a spring
169
c
. The annular portion
169
a
is fixed to the inner wall surface of the bolt
180
by press fitting. The seal portion
169
b
is fitted to one end of the annular portion
169
a
so as to slide on the outer circumferential wall of the plunger
161
. The spring
169
c
is attached to the seal portion
169
b
so as to always press the outer circumferential wall of the plunger
161
at predetermined pressure. In addition, the other end of the annular portion
169
a
opposite to the seal portion
169
b
is formed as an open end
169
d.
As for the method for manufacturing the oil seal
169
, first, an adhesive agent is applied to the surface of the annular portion
169
a
. After that, the rubber seal portion
169
b
is bonded and fixed, by vulcanizing molding, to the edge of an insertion hole for the plunger
161
formed at one end of the annular portion
169
a
. At this time, the adhesive agent applied to the surface of the annular portion
169
a
also adheres to a portion abutting against the inner wall surface of the bolt
180
. When the adhesive agent is dried, the adhesion state of the adhesive agent varies markedly. When press fitting is carried out in this state, there is a problem that a failure in sealing occurs in the abutment portion.
FIG. 13
is a graph showing the relationship between the press-in load and the press-in stroke of the oil seal
169
. In
FIG. 13
, the ordinate designates the press-in load (kN), and the abscissa designates the press-in stroke. In addition,
FIG. 14
is a graph showing the surface pressure distribution generated in the abutment portion between the oil seal
169
and the bolt
180
. In
FIG. 14
, the ordinate designates the axial position of the abutment portion between the oil seal
169
and the bolt
180
, and the abscissa designates the surface pressure (MPa).
As shown in
FIG. 13
, at the beginning of press fitting of the annular portion
169
a
, that is, at the beginning of a press-in stroke, a high press-in load is generated. After that, however,
Ichinose Yuta
Onishi Yoshihiko
Uryu Takuya
Leslie Michael
Look Edward K.
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