Valves and valve actuation – Electrically actuated valve – Rotary electric actuator
Reexamination Certificate
2001-07-16
2002-07-02
Doerrler, William C. (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Rotary electric actuator
C123S568230
Reexamination Certificate
active
06412753
ABSTRACT:
BACKGROUND OF THE INVENTION
1
. Field of the Invention
The present invention relates to an EGR (Exhaust Gas Recirculation) valve device which comprises, for example, a recycling system for exhaust gases.
Description of Related Art
Conventional examples of this type of EGR valve have been used with a stepping motor to open and close valves. However use of a DC motor instead of a stepping motor has developed in order to increase output, improve response characteristics and improve limits in the resolution of valve aperture regulation.
FIG. 1
is a longitudinal cross section of an EGR valve device as disclosed in Published Unexamined Japanese Patent Application H10-220620 (1998) for example. In
FIG. 1
, reference numeral
1
denotes a valve body,
2
denotes a motor case,
3
denotes a connector terminal,
11
denotes a valve which opens and closes an exhaust gas passage by vertical arrangement,
12
denotes a seat which maintains a degree of aperture in response to a vertical arrangement of the valve
11
,
13
denotes a guide bush,
14
denotes a shaft with a valve
11
fitted to a lower end,
15
denotes a guide seal,
16
denotes a guide plate,
17
denotes a guide seal cover,
18
denotes a spring seat,
19
denotes a spring which pushes the shaft
14
in a direction of closure of the valve
11
, and
20
denotes a motor.
21
denotes a rotor with a hollow space. A threaded portion is formed on an inner face of the hollow space.
22
denotes a coil,
23
denotes a yoke,
24
denotes a magnet,
25
denotes a slide ball, and
26
denotes a rotor shaft. A bearing, which supports an upper end of the rotor
21
, comprises the slide ball
25
and the rotor shaft
26
27
denotes a bearing which supports a lower end of the rotor
21
.
28
denotes a commutator which is integrally fitted to an upper end of the rotor
21
. The motor brush
30
and the commutator
28
are arranged at a position on an upper end of the rotor
21
and below the bearing which supports an upper end of the rotor
21
which is composed of the rotor shaft
26
and the slide ball
25
.
29
denotes a brush spring,
30
denotes a motor brush,
31
denotes a motor shaft which forms a threaded portion on an outer peripheral face. The threaded portion is threadably fitted to a threaded portion formed on an inner face of the hollow space of the rotor
21
.
40
denotes a position sensor.
The operation of the conventional EGR valve device will be described below.
In this type of EGR valve, a fixed return torque is generated in a direction of closure of the valve
11
due to the spring
19
, and a variable motor torque is generated in a direction of opening the valve
11
due to a current in one direction of the motor
20
. Thus the opening and closing of the valve
11
is controlled by the balance of these torque components.
In the conventional EGR valve device comprised as discussed above, because a DC motor is used as a source of required torque to open and close the valves
11
, a motor brush and a commutator are provided. The motor brush and the commutator are arranged below the slide ball
25
and on the upper end of the rotor
21
. The rotor
21
itself can deviate vertically in an axial direction due to the repulsive force operating in an axial direction of the rotor
21
in conjunction with the opening and closing of the valve
11
. Thus the problem has arisen that it is not possible to avoid adverse influence on a current carrying device such as a commutator or motor brush when a positional deviation of the rotor
21
occurs in an axial direction.
Furthermore, since the motor brush
30
and commutator
28
are arranged below the slide ball
25
and on the upper end of the rotor
21
, the problem has arisen that motor failure is facilitated by foreign objects such as particulate matter generated by wear in the motor brush
30
entering the interior of the DC motor and accumulating in the gap between the magnet
24
and the rotating components of the motor such as the coil
22
or the like.
The current carrying device having the motor brush
30
and the commutator
28
is integrally fitted to an upper end of the rotor
21
, and an upper end of the motor shaft
26
abuts with and rotates freely on the slide ball
25
. Furthermore the rotating component of the motor such as the coil
22
is assembled so as to have a fixed gap with respect to the magnet
24
. Thus the problem of low productivity during assembly has arisen.
SUMMARY OF THE INVENTION
The present invention is provided to solve the above-described problem, and the object of the present invention is to provide an EGR valve device which avoids adverse effects on the current carrying device by eliminating the possibility that the rotor will undergo a vertical deviation in an axial direction and which improves reliability of the device by preventing motor failure due to foreign objects such as particulate matter due to wear in the motor brush
30
.
The present invention has the further object of providing an EGR valve which improves productivity when assembling the device.
The EGR valve device as defined by the present invention is provided with a motor rotating unit having a stator, in which each of a fixed number of coils is arranged in a peripheral direction of a stator core, and a rotor in which each of a plurality of magnets is fitted to an outer peripheral face corresponding to one coil of the stator, a valve drive mechanism for driving a valve linearly according to the rotation of the rotor of the motor rotating unit, a bearing for rotatably supporting the rotor, to which the magnets are fitted, with respect to the stator, and a current carrying device, which is arranged at a position placed on an outer side opposite to a side arranging the magnets on a rotational axis of the rotor with respect to the bearing, for commutating a direct current supplied from a power source according to a position of the rotor and supplying the commutated current to one coil of the stator.
With such a structure, it is possible to prevent adverse effects on the current carrying device due to the positional deviation of the rotor in an axial direction due to a repulsive force acting on the rotor when the valve driving mechanism drives the valve. Such adverse effects are prevented by the provision of the bearing arranged between the current carrying device and rotor which has the magnets. Thus it is possible to improve reliability of the valve device.
The EGR valve device as defined by the present invention is provided with the current carrying device comprising a plurality of slip rings, a plurality of commutator pieces and a plurality of motor brushes. A disk-shaped feeding unit comprises the slip rings and the commutator pieces, and the disk-shaped feeding unit is integrally fitted to an extension of the rotor which extends to the outer side opposite to the side arranging the magnets on the rotational axis of the rotor with respect to the bearing.
With such a structure, it is possible to prevent adverse effects on the slip rings and commutator pieces formed on the disk-shaped feeding unit due to the positional deviation of the rotor in an axial direction due to a repulsive force acting on the rotor when the valve driving mechanism drives the valve. Such adverse effects are prevented by the provision of the bearing arranged between the feeding unit and the rotor which has the magnets. Thus it is possible to improve reliability of the valve device.
The EGR valve device as defined by the present invention is provided with a shielding member which shields an opening between the motor rotating unit and the current carrying device.
In this way, it is possible to prevent motor failure that results from the accumulation of foreign objects in the rotating parts of the motor. The foreign objects (such as particulate matter) are generated as the parts of the current carrying device become worn. Thus it is possible to improve reliability of the valve device.
The EGR valve device as defined by the present invention is provided with the shielding member which is tightly fitted to a
Fujita Youichi
Kawamura Satoshi
Miyake Toshihiko
Miyoshi Sotsuo
Buechner Patrick
Doerrler William C.
Mitsubishi Denki & Kabushiki Kaisha
Sughrue & Mion, PLLC
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