Motor drive

Details Motor drive Motor drive

2001-06-15

2003-04-15

Masih, Karen (Department: 2837)

Electricity: motive power systems

Automatic and/or with time-delay means

Level of fluid or granular material

C318S264000, C318S265000, C318S280000, C318S283000, C318S281000, C318S286000, C318S282000

Reexamination Certificate

active

06548980

ABSTRACT:

TECHNICAL FIELD
This invention relates to a motor drive apparatus, e.g., the drive apparatus of a motor for opening and closing the power window of a vehicle.
BACKGROUND ART
A mechanism (power window) for opening and closing a window by the driving force of a motor is employed in many vehicles. Though one such mechanism which controls the forward and reverse rotation of the motor (the opening and closing of the window) directly by an operating switch is available, a variety of electronically controlled power window systems have recently come into widespread use. For example, one mechanism is such that if a foreign object of some kind becomes caught between the window frame and the window glass when the window is being closed, this is sensed and control is carried out to reverse the rotation of the motor and open the window. Another such mechanism remotely controls the opening and closing of the window by wireless communication.
In any case, many systems use relays to drive the window opening and closing motor in the forward and reverse directions and to halt the rotation thereof. Consequently, if an accident occurs in which the vehicle falls into the sea or into a river and sinks, the motor may be actuated, owing to malfunction of the relays, regardless of the fact that neither operation of the switch nor electronic control is carried out. For example, if the motor rotates in the reverse direction and the window closes, the driver and any passengers will become trapped inside the vehicle.
A motor drive apparatus using relays for the power window of a vehicle according to the prior art will be described with reference to
FIG. 6
a.
The window of a vehicle is opened and closed by the rotation of a motor
1
. There are provided a relay
2
for rotating the motor
1
in the forward direction (to open, i.e., lower, the window), and a relay
3
for rotating the motor
1
in the reverse direction (to close, i.e., raise, the window).
The relay
2
includes a relay coil
2
a
and relay contacts
2
b
. The relay contacts
2
b
include a normally open contact (make contact or a contact) NO and a normally closed contact (break contact or b contact) NC. The relay
3
includes a relay coil
3
a
and relay contacts
3
b
. The relay contacts
3
b
includes a normally open contact NO and a normally closed contact NC.
The contacts (or terminals) NO of these relay contacts
2
b
,
3
b
are connected to the line of a power supply E
1
, and the contacts (or terminals) NC of these relay contacts are connected to ground. Common terminals C of these relay contacts
2
b
,
3
b
are connected to positive and negative terminals ma, mb, respectively, of the motor
1
. The motor rotates forward when a positive voltage is applied to the terminal ma and in reverse when a positive voltage is applied to the terminal mb.
The relay coil
2
a
of relay
2
is connected between the line of a power supply E
2
and ground and in series with a window-opening operating switch
4
. Similarly, the relay coil
3
a
of relay
3
is connected between the line of the power supply E
2
and ground and in series with a window-closing operating switch
5
.
The two operating switches
4
,
5
are illustrated as being separately provided as operating switches. In actuality, however, the switches
4
and
5
usually are equipped with a common operating knob capable of being rocked back and forth. The structure used is such that the switch
4
is turned on when the knob is swung in one direction and the switch
5
is turned on when the knob is swung in the other direction.
Single-pole, double-throw contacts (transfer contacts or break-make contacts) are illustrated as the relay contacts
2
b
,
3
b
. It goes without saying, however, that the apparatus may have parallel-connected normally open contacts NO and normally closed contacts NC, as shown in
FIG. 6
b.
If the operating switch
4
is turned on, the relay coil
2
a
is energized to actuate the relay contacts
2
b
. The common terminal C in the relay contacts
2
b
is connected to the normally open contact NO and separates from the normally closed contact NC. Accordingly, current flows from the line of power supply E
1
to the positive terminal ma of motor
1
through the normally open contact NO and common terminal C of the relay contacts
2
b
, and current that flows out of the negative terminal mb of motor
1
flows to ground through the common terminal C and normally closed contact NC of relay contacts
3
b
. As a result, the motor
1
rotates in the forward direction and the window is opened. When the operating switch
5
is turned on, current from the power supply E
1
flows to ground through the contacts
3
b
, motor
1
and contacts
2
b
, so that the motor
1
rotates in the reverse direction and the window is closed.
The above-described motor drive apparatus is such that energization of the relay coils
2
a
,
3
a
is controlled directly by turning the operating switches
4
,
5
on and off. There is also an apparatus of the type in which the states of operating switches are judged by a single-chip microcomputer or the like and the energization of the relay coils is controlled based upon the judgment made.
FIG. 7
illustrates an example of a conventional motor drive circuit that relies upon such control by microcomputer. A controller (circuit)
13
typified by a microcomputer is provided in the diagram of FIG.
7
. An operating switch
14
has a common terminal C and two normally open contacts NO
1
, NO
2
. Under ordinary conditions, the common terminal C is not connected to either the contact NO
1
or the contact NO
2
. The common terminal C is connected to ground. A power-supply voltage E
3
is applied on the contacts NO
1
, NO
2
via pull-up resistors
15
,
16
, respectively. Under ordinary conditions, these voltages are applied to corresponding input ports of controller
13
.
In comparison with the circuits of
FIGS. 6
a
and
6
b
, the circuit of
FIG. 7
has relay control transistors
11
,
12
instead of the operating switches
4
,
5
connected in series with the relay coils
2
a
,
3
a
, respectively. The control terminals
11
,
12
are on/off controlled by the controller
13
. Under ordinary conditions, these transistors
11
,
12
are held in the off state.
If an operating knob is moved or swung in one direction so that the contact NO
1
of operating switch
14
is connected to the common terminal C, the contact NO
1
is brought to ground level. The ground-level voltage is sensed by the controller
13
. The controller
13
outputs a control signal (H level) that turns on the transistor
11
, and the relay coil
2
a
is energized to rotate the motor
1
in the forward direction. If the operating knob is swung in the other direction, the contact NO
2
of operating switch
14
is connected to the common terminal C. The controller
13
senses the ground level at the contact NO
2
and outputs a control signal that turns on the transistor
12
, as a result of which the relay coil
3
a
is energized to rotate the motor
1
in the reverse direction.
The above-described motor drive apparatuses are such that if the vehicle falls into the sea, a lake or a river and the apparatus becomes submersed, there is a possibility that a phenomenon (so-called leakage) will occur in which, depending upon the quality of the water, a current flows into either contact of the operating switches (switches
4
,
5
or switch
14
) despite the fact that the operating knob has not been operated. As a consequence, there is the possibility that problems will arise, such as the motor
1
being rotated in the forward or reverse direction, the reversely rotating motor being stopped or control over the motor being lost, regardless of the fact that the operating knob has not been operated.
In general, a relay has a hysteresis characteristic, in which the voltage for actuating the relay (the voltage, which shall be referred to as the “actuating voltage”, applied to a relay coil in order to turn on a normally open contact or turn off a normally closed contact) is higher than the voltage (wh

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