Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
2001-09-25
2004-01-06
Gimie, Mahmoud (Department: 3747)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
C251S129110
Reexamination Certificate
active
06672293
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an exhaust gas recirculation valve device disposed in an exhaust gas recirculation passage of an internal combustion engine for example of an automobile.
BACKGROUND TO THE INVENTION
FIG. 1
is a cross sectional figure showing the internal structure of a conventional exhaust gas recirculation valve device. In the figure, the valve housing
1
has an inlet port
2
communicating with an exhaust system (not shown) of an engine which is an internal combustion engine, an outlet port
3
which communicates with an air intake system (not shown) of the engine and a passage
4
interposed between the outlet port
3
and the inlet port
2
. A valve seat
5
is press fitted into the passage
4
.
6
is a valve rod passing through a bushing
7
. A valve
8
is mounted on the lower end of the valve rod
6
to separate or abut with the valve seat
5
.
9
is a holder to prevent deposition of substances in the bushing
7
.
10
is a spring holder which is pushed upwardly by a coil spring
11
. A through hole
12
is formed in the central section of the spring holder
11
. The tip
6
a
of the valve rod
6
is fixed by caulking through the through hole
12
. The valve rod
6
and the spring holder
10
are integrated by caulking and the valve
8
mounted on the lower section of the valve rod
6
is normally pushed in a closed position with respect to the valve seat
5
by the coil spring
11
.
13
is a cooling water passage cooling the motor to be described below and the valve body.
20
is a stepping motor main body functioning as a stator assembly with respect to the rotor section to be discussed below. A motor holder
21
is fixed to the lower section of the stepping motor
20
by a clamp screw
23
through an O-ring
22
in order to prevent the entry of water into the stepping motor main body
20
. A motor brush
25
is disposed to retain the motor shaft
24
in a central opening of the motor holder
21
. The lower section of the motor shaft
24
is fixed by caulking to the spring holder
26
and a joint
27
.
28
is a spring which is disposed between the motor holder
21
and the spring holder
26
and which pushes the motor shaft
24
in a direction opening the valve.
30
are bobbins which are wound coils
31
.
32
and
33
are yokes. A magnetic path is formed through the outer periphery of the yokes
32
and
33
.
34
are terminals which are electrically connected to coils
31
. The terminals
34
and a motor housing
35
form a connector.
36
is a plate which shields the two coil sections magnetically.
37
is a plate preventing resin from flowing into the coil inner section when the motor housing
35
is exterior molded.
40
is a magnet.
41
is a rotor retaining a magnet. The magnet
41
has a threaded section
41
a
threadably attached to a threaded section
24
a
of the motor shaft
24
on an inner periphery and an axial stopper
41
b
of the motor shaft
24
.
42
are bearings mounted on both ends of the rotor
41
.
43
is a stopper pin press fitted to the motor shaft
24
.
This type of stepping motor main body
20
maintains a waterproof structure due to the motor holder
21
fixed to the lower section of the stepping motor main body
20
and is mounted on the top section of the valve housing
1
so that the axial centers are aligned by a mounting screw
44
.
The operation will be described below.
Firstly, when the engine is started and the valve is completely closed, the rotor
41
which contains a magnet
40
rotates in a stepwise manner in a direction of valve opening due to a pulsed voltage sent from the control unit (not shown) to the terminals
34
during the valve opening operation. The stepwise rotation is converted into linear motion by the threaded section
41
a
of the rotor
41
and the threaded section
24
a
of the motor shaft
24
and the motor shaft
24
displaces in a direction of valve opening (downwardly). As the displacement continues, at the moment when the upper face of the tip
6
a
of the valve rod
6
near the valve housing
1
abuts with the lower face of the motor shaft
24
near the motor housing
35
, the valve rod
6
is depressed by the drive force of the motor shaft
24
against the pushing upward force of the coil spring
11
. Also the valve
8
which is mounted on the lower section of the valve rod
6
is lowered and opens with respect to the valve seat
5
and the inlet port
2
and the outlet port
3
are connected by the passage
4
.
During the valve closure operation, the rotor
41
which contains a magnet
40
rotates in a stepwise manner in a direction of valve closure due to a pulsed voltage sent from the control unit (not shown) to the terminals
34
in an operation which is the opposite of the above. The motor shaft
24
displaces in a direction of valve closure (upwardly) due to the rotation. In addition to the rotation, the valve rod
6
is raised by the upward pushing force of the coil spring
11
and the valve
8
covers the opening of the valve seat
5
.
The waterproofing structure of the stepping motor main body
20
in this type of exhaust gas recirculation valve device is realized by pressing a motor holder
21
by an O-ring
22
onto the lower section of the stepping motor main body
20
and by covering and closing the space between the stepping motor main body
20
and the motor holder
21
with a clamp screw
23
as the O-ring is compressed.
However the unit price of O-rings is relatively high and thus in order to reduce the overall cost of the exhaust gas recirculation valve device, it is required to maintain the waterproofing structure of the stepping motor main body
20
without using an O-ring
22
.
The present invention is proposed to solve the above problems and has the object of providing an exhaust gas recirculation valve device which maintains a waterproof structure in the stepping motor main body
20
without using an O-ring
22
.
DISCLOSURE OF THE INVENTION
The exhaust gas recirculation valve device according to the present invention is provided with a motor main body which has a motor driving a valve with a valve rod in an opening or a closing direction, and a motor holder which covers the lower opening of the motor main body. One of the lower opening of the motor main body and the upper section of the motor holder is formed a circular groove and the other of the lower opening of the motor main body and the upper section of the motor holder is formed in a protrusion which fits in the circular groove. A liquid sealant is applied between the top of the protrusion and the bottom of the circular groove facing the top of the protrusion. In this way in contrast to the prior art, it is not necessary to use an O-ring which has a relatively high unit price and thus it is possible to reduce the overall manufacturing costs of the exhaust gas recirculation valve device. Furthermore it is possible to ensure maintenance of the waterproofing structure of the motor main body without a threaded stopper since a liquid sealant is used which can be easily adapted to the surface structure of the section to which the sealant is applied.
The present invention is provided with a circular groove which has a bottom and an innermost circular periphery which is adjacent to the bottom and a protrusion which has a top and an innermost circular periphery which is adjacent to the top. The present invention is adapted so that the top of the protrusion and the bottom of the circular groove are placed in contact through the liquid sealant with the innermost periphery of the protrusion fitted to the innermost periphery of the circular groove. Thus excess liquid sealant which is interposed between the bottom of the circular groove and the top of the protrusion is prevented from flowing into the motor main body by a fitted section comprising the circular groove and the protrusion. Therefore it is possible to prevent unexpected defects in motor operation due to the liquid sealant.
Since the present invention fixes a section of the outermost periphery of the circular groove by caulking to the
Ikai Takeshi
Kato Yasuhiko
Yokoyama Hisashi
Gimie Mahmoud
Mitsubishi Denki & Kabushiki Kaisha
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