Electrical flow control valve

Details Electrical flow control valve Electrical flow control valve

1999-06-08

2003-06-24

Gartenberg, Ehud (Department: 3754)

Valves and valve actuation

Electrically actuated valve

Rotary electric actuator

C310S090000, C123S568240

Reexamination Certificate

active

06581903

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an electrical flow control valve used in devices such as exhaust gas re-circulation control devices for the purpose of reducing exhaust gas emissions of NOx or the like from internal combustion engines.
BACKGROUND OF THE INVENTION
FIG. 1
is a block diagram which shows conventional exhaust gas re-circulation control device. In
FIG. 1
, reference numeral
1
denotes an internal combustion engine,
2
is an intake pipe allowing inflow of air to the engine,
3
is an intake manifold allowing inflow of air to each pipe branching from the intake pipe
2
,
4
is an air cleaner provided upstream of the intake pipe
2
,
5
is an injector which is provided in the intake pipe
2
and injects fuel. Air entering the intake pipe
2
through the air cleaner
4
flows into the engine
1
together with fuel supplied from the injector
5
.
6
represents a throttle valve which varies the degree of air intake into the engine
1
and
7
is an idle rotation speed control valve provided in a bypass which bypasses the throttle valve
6
. The gas mixture which enters the engine
1
is ignited by an ignition plug not shown in the figure. After combustion, the exhaust gases pass through the exhaust gas pipe
8
, are purified by the purification device
9
comprising a catalytic converter and are expelled into the atmosphere.
10
is an electrical flow control valve of a step motor type which is disposed in the exhaust gas re-circulation passage and controls the flow of exhaust gases in the passage.
11
is an electronic control unit which generates control signals to the electrical flow control valve
10
on the basis of information received from the driving state detection means comprising elements such as a throttle aperture sensor
12
which detects the degree of aperture of the throttle valve
6
, a pressure sensor
13
which detects the pressure in the intake pipe, a water temperature sensor
14
which detects the temperature of the engine cooling water, and the ignition device made up of the ignition coil
15
and the igniter
16
.
FIG. 2
is a diagram which shows the above electrical flow control valve
10
.
21
is a valve housing having an inlet port
21
a
which communicates with the engine exhaust gas pipe
8
, an outlet port
21
b
which communicates with the engine intake pipe
2
and a rotary flow passage
21
c
which is the passage between the inlet port
21
a
and the outlet port
21
b
.
22
is a valve seat provided in the rotary flow passage
21
c
of the valve housing
21
.
23
is a valve body which opens and closes the aperture of the valve seat
22
.
24
is a valve shaft on one end of which the valve body
23
is mounted and which displaces the valve body
23
to the open and closed position by reciprocating motion as a valve rod.
25
is a bush which acts as a bearing for the valve shaft
24
mounted in the valve housing
21
.
27
is a spring holder mounted on the other end of the valve shaft
24
which projects externally from the valve housing
21
.
28
is a bracket, for example made of cast iron, formed as a unit with the valve housing
21
on the side from which the valve shaft
24
projects from the valve housing
21
. The bracket
28
is in a cup shape of fixed height in the shape of a truncated cylindrical concavity on the step motor side (hereafter called the indented part).
A flange element
28
b
which mounts the stepping motor
29
with a spacing member
31
and a mounting screw
32
through the holder
30
is formed on the stepping motor
29
side of the bracket
28
. The cross sectional size of the flange
28
b
is of a size having the minimum necessary strength to support the stepping motor
29
or is of a slightly larger size (for example a size having a surface area twice that of the necessary strength).
Furthermore around the flange element
28
b
, an aperture
28
c
is formed which communicates with the indented part
28
a
. Then on the valve housing side
21
of the bracket
28
, a holder
26
is formed which prevents the build-up of deposits within the vertical range of the bush
25
displaced by the valve shaft
24
.
The motor holder
30
is made of material having good thermal conductivity, a lower bearing
33
is mounted in the central lower hollow part, and the length of an integrated heat radiating fin
35
forms a gap
34
between the valve housing on the valve housing side. These components make it possible to decrease the transmission of high temperature exhaust gases to the step motor
29
.
Next, the components of the step motor
29
will be explained.
36
is a hollow motor housing,
37
is a rotor which is supported in free rotation by a ball
49
and a sleeve bearing
38
at its upper end, and by a lower bearing
33
at its lower end. A magnet
39
is mounted on its outer periphery. The central part of the rotor
37
is hollow in the vertical direction, displaces vertically and has a threaded section
37
a
formed on its inner face.
40
a
and
40
b
are upper and lower yokes which are mounted on the inner part of the motor housing
36
so as to face the magnet
39
of the rotor
37
and in the inner part of which are housed bobbins
41
a
and
41
b
.
42
a
1
and
42
a
2
are coils wound around the bobbin
41
a
,
42
b
1
and
42
b
2
are coils wound around the bobbin
41
b
, and
43
is a plate magnetically separating the upper and lower yokes
40
a
and
40
b
.
44
is a protective plate which is provided in the upper part of the motor housing
36
for preventing entry of resinous material into the insertion part of the rotor when forming the motor housing
36
.
45
is an actuator rod which is supported in a threadedly engaged state by the threaded section
37
a
of the inner part of the rotor
37
and which projects downwardly from the motor holder
30
. The tip of the actuator rod
45
displaces vertically and pushes against the valve shaft
24
.
Due to the fact that the actuator rod
45
is prevented from rotating by the bearing of the actuator rod and the motor bush
54
which has a rotation prevention function, the actuator rod
45
displaces vertically in response to the rotations of the rotor
37
. A stopper
45
b
is provided in the actuator rod which pushes against and detaches from the stopper
37
b
of the rotor
37
and limits the upward displacement above a fixed amount.
46
is a plate which is assembled in the indented part
37
c
which is provided on the upper end of the rotor
37
.
47
is an indented part which is formed on the protective plate
44
on the shaft line of the rotor
37
, and which centers the ball
49
on the plate
46
.
50
is a SPL washer for providing pre-load to the lower bearing
33
.
51
is a connector which supplies electrical pulses to each coil. As shown in
FIG. 4
, the connector
51
comprises the terminals{circle around (
1
)}-{circle around (
6
)} which are electrically connected to the coils
42
a
1
,
42
a
2
,
42
b
1
,
42
b
2
, and the connector housing
51
a
. As shown in
FIG. 3
, switching transistors Tr
1
-Tr
4
are connected to the ground line of the terminals, {circle around (
1
)}, {circle around (
3
)}, {circle around (
4
)}, {circle around (
6
)}. Terminal {circle around (
2
)} to which one end of the coils
42
a
1
and
42
a
2
is connected and terminal
5
to which one end of the coils
42
b
1
and
42
b
2
is connected, are connected to the electrical supply terminal +B through the switch SW. The connector housing
51
a
and the motor housing
36
are integrated by resinous material.
52
is a coil spring which intercalates between the spring holder
27
and the bracket
28
. The coil spring pushes the valve shaft
24
upwardly towards the middle of the figure through the spring holder
27
and maintains the valve body
23
in a closed state. While in a closed state, a gap is formed between the valve shaft
24
and the actuator rod
45
and the valve body
23
is maintained in an accurately closed state.
Next the operation of the electrical flow control valve will be explained. The rotor
37
of the stepping motor
29

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