Electricity: motive power systems – Motor-reversing – Armature or primary circuit control
Reexamination Certificate
2000-10-25
2002-06-11
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Motor-reversing
Armature or primary circuit control
C318S286000, C318S375000, C318S443000
Reexamination Certificate
active
06404155
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a DC (direct current) motor drive circuit for use in a windshield wiper drive section or a power window drive section of automobiles, for example.
2. Description of the Prior Art
Heretofore, DC motor drive circuits using an electromagnetic relay have often been used in order to activate and control a windshield wiper drive section and a drive section for driving a power window mechanism to move a power window of automobile upward or downward
FIG. 1
of the accompanying drawings is a schematic circuit diagram showing an example of a prior-art DC motor drive circuit for use in a windshield wiper drive section.
FIG. 2
is a schematic circuit diagram showing an example of a prior-art DC motor drive circuit for use in a drive section of a power window drive mechanism to move a power window upward or downward.
First, an example of a DC motor drive circuit for use in a windshield wiper drive section will be described with reference to FIG.
1
. As shown in
FIG. 1
, one end of a windshield wiper driving DC motor
1
is connected to a terminal
2
a
connected to a movable contact (this movable contact is usually connected to a suitable means such as a contact spring driven by an armature) AR of an electromagnetic relay
2
. The above terminal
2
a
connected to the movable contact AR will hereinafter be referred to as “movable contact terminal”.
The other end of the DC motor
1
is connected to a terminal
2
b
connected to a normally closed contact N/C (i.e. break contact) of the electromagnetic relay
2
. The above terminal
2
b
connected to the normally closed contact N/C will hereinafter be referred to as “normally closed contact terminal”. A connection point
2
d
between the other end of the DC motor
1
and the normally closed contact
2
b
is connected to the ground.
A terminal
2
m
connected to a normally open contact N/O (i.e. make contact) of the electromagnetic relay
2
is connected to a power supply at a terminal
3
, at which a positive DC voltage (+B) is connected from a car battery (not shown). The above terminal
2
m
to which the normally open contact N/O is connected will hereinafter be referred to as “normally open contact terminal”.
The electromagnetic relay
2
includes a coil
2
C to which a controlling current responsive to user's operation is supplied from a windshield wiper drive controller
4
when the user operates a windshield wiper switch
5
. The windshield wiper switch
5
includes three switching positions of “OFF position”, “INTERMITTENT position” and “CONTINUOUS position”. Fixed contacts
5
a
,
5
b
,
5
c
at these switching positions are connected to the windshield wiper drive controller
4
.
When the windshield wiper switch
5
connects its movable contact
5
m
to the fixed contact
5
a
(OFF position), the coil
2
C is not energized by the controlling current from the windshield wiper drive controller
4
so that the electromagnetic relay
2
connects the movable contact AR to the normally closed contact N/C. As a result, one end and the other end of the DC motor
1
are connected to each other and thereby the DC motor
1
can be braked (or placed in the stationary state).
When the windshield wiper switch
5
connects the movable contact
5
m
to the fixed contact
5
b
(INTERMITTENT position), the coil
2
C of the electromagnetic relay
2
is intermittently energized by the controlling current from the windshield wiper drive controller
4
. As a result, the electromagnetic relay
2
connects the movable contact AR to the normally open contact N/O during the coil
2
C is being energized by the controlling current. When the coil
2
C is not energized by the controlling current, the electromagnetic relay
2
connects the movable contact AR to the normally closed contact N/C side. Specifically, the electromagnetic relay
2
alternately connects the movable contact AR to the normally closed contact N/C and the normally open contact N/O each time the coil
2
C is energized or is not energized by the controlling current.
When the electromagnetic relay
2
connects the movable contact AR to the normally open contact N/O, direct current flows through the DC motor
1
as shown by a solid-line arrow I in FIG.
1
and thereby the DC motor
1
can be driven. When the electromagnetic relay
2
connects the movable contact AR to the normally closed contact N/C, the DC motor
1
can be braked. In other words, the DC motor
1
may be driven intermittently. As this DC motor
1
is driven intermittently, the windshield wiper is driven intermittently.
When the windshield wiper switch
5
connects the movable contact
5
m
to the fixed contact
5
c
(CONTINUOUS position), the windshield wiper drive controller
4
continuously supplies a controlling current to the coil
2
C of the electromagnetic relay
2
. As a result, the electromagnetic relay
2
connects the movable contact AR to the normally open contact N/O to permit the DC current to flow through the DC motor
1
continuously as shown by the solid-line arrow I in FIG.
1
. Thus, the windshield wiper can be driven continuously.
When the windshield wiper switch
5
connects the movable contact
5
m
to the fixed contact
5
a
(OFF position), the coil
2
C of the electromagnetic relay
2
is not energized so that the electromagnetic relay
2
is released to connect the movable contact AR to the normally closed contact N/C.
Next, an example of a conventional DC motor drive circuit for use in a power window drive section will be described with reference to FIG.
2
.
As shown in
FIG. 2
, one end of a power window DC motor
11
is connected to a movable contact terminal
12
a
of an electromagnetic relay
12
that is used to move a power window upward. The other end of the DC motor
11
is connected to a movable contact terminal
13
a
of an electromagnetic relay
13
that is used to move a power window downward.
A normally closed contact terminal
12
b
of the electromagnetic relay
12
and a normally closed contact terminal
13
b
of the electromagnetic relay
13
are connected to each other. A connection point
12
d
between the normally closed contact terminal
12
b
and the normally closed contact terminal
13
b
is connected to the ground. A normally open contact terminal
12
m
of the electromagnetic relay
12
and a normally open contact terminal
13
m
of the electromagnetic relay
13
are connected to each other. A connection point
12
e
between the normally open contact terminal
12
m
and the normally open contact terminal
13
m
is connected to the power supply at the terminal
3
, at which a positive DC voltage (+B) is connected from a car battery (not shown), for example.
A power window ascending controller
14
supplies controlling current to the coil
12
C of the electromagnetic relay
12
each time the user operates a power window drive section to move the power window upward. A power window descending controller
16
supplies controlling current to the coil
13
C of the electromagnetic relay
13
each time the user operates the power window drive section to move the power window downward.
While the user is operating the power window drive section to move the power window upward, a power window switch
15
is being energized and the power window ascending controller
14
supplies controlling current to the coil
12
C of the electromagnetic relay
12
to energize the coil
12
c
to allow the electromagnetic relay
12
connect the movable contact AR to the normally closed contact N/O. Accordingly, direct current flows through the DC motor
11
in the direction shown by a solid-line arrow in
FIG. 2
so that the DC motor
11
is driven in the positive direction, for example, to move the power window upward, i.e. in the direction in which the power window closes.
When the user stops operating the power window drive section to move the power window upward, a power window switch
15
is de-energized to stop the supply of the controlling current to the coil
12
C of the electromagnetic relay
12
t
Funayama Hideo
Sato Hiromitsu
Oliff & Berridg,e PLC
Ro Bentsu
Taiko Device, Ltd.
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