Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Reexamination Certificate
2003-06-09
2004-08-31
Tang, Minh N. (Department: 2829)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
C324S1540PB, C318S434000
Reexamination Certificate
active
06784687
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a diagnostic device for electric mechanism drive circuits for diagnosing drive circuits of electric mechanisms including motors, and more particularly to a diagnostic device for electric mechanism drive circuits which diagnoses the state of an electric mechanism when the electric mechanism is to operate and the state of connection between the electric mechanism drive circuit and the electric mechanism, and thereby prevents the electric mechanism from running into trouble or being burnt.
2. Description of the Related Art
Known motor drive circuits according to the prior art for driving a motor for bidirectional revolutions include one having a pair of relays each provided with a normally closed contact, a normally open contact, a movable contact and a drive coil for switching over and driving the movable contact, and a control section supplying the drive coils of the relays with switching signals for switching over their movable contacts. In this motor drive circuit, both normally closed contacts are connected to a grounding point (reference potential point), both normally open contacts are connected to a power supply terminal and both terminals of the motor are connected between the two movable contacts. In response to a switching signal from the control section, if the movable contact of one relay is switched over towards the normally open contact, the motor is driven for revolution in one direction (forward direction), or if the movable contact of the other relay is switched over towards the normally open contact, the motor is driven for revolution in the other direction (reverse direction).
This kind of motor drive circuit, when it is to drive a motor, if there is any trouble in the motor itself, such as short circuiting between terminals, disconnection of a coil or the like, or any trouble in wiring for connecting the motor and a pair of relays, such as short circuiting between lines, disconnection or the like, will not only be unable to normally drive the motor but even invite a major accident, such as burning of the motor. In view of this risk, a diagnostic device for predicting any possible trouble in the motor or its connection wiring is used.
FIG. 4
here is a circuit diagram showing one example of configuration of such a known diagnostic device for motor drive circuits.
As shown in
FIG. 4
, this motor drive circuit diagnostic device is provided with a control unit
40
made up of a microcomputer having an operation controller
40
(
1
) for controlling the overall operation and a diagnostic section
40
(
2
) and the like; a motor
41
constituting a load; a first relay
42
having a movable contact
42
(
1
), a normally closed contact
42
(
2
), a normally open contact
42
(
3
) and a drive coil
42
(
4
); a second relay
43
having a movable contact
43
(
1
), a normally closed contact
43
(
2
), a normally open contact
43
(
3
) and a drive coil
43
(
4
); a first transistor drive circuit
44
which has a first transistor
44
(
1
) and drives the first relay
42
; a second transistor drive circuit
45
which has a second transistor
45
(
1
) and drives the second relay
43
; a first connection wiring section
46
having connection terminals
46
(
1
) and
46
(
2
) for connecting one end of the motor
41
and the first relay
42
; and a second connection wiring section
47
having connection terminals
47
(
1
) and
47
(
2
) for connecting the other end of the motor
41
and the second relay
43
. It is further provided with a switching circuit
48
having a field effect transistor
48
(
1
); a first resistance voltage dividing circuit
49
made up of two series resistors
49
(
1
) and
49
(
2
); a second resistance voltage dividing circuit
50
made up of two series resistors
50
(
1
) and
50
(
2
), and a power supply terminal
51
.
One end of the motor
41
is connected to the first connection wiring section
46
, and the other end, to the second connection wiring section
47
. In the first relay
42
, the movable contact
42
(
1
) is connected to the first connection wiring section
46
, the normally closed contact
42
(
2
), to the drain of the field effect transistor
48
(
1
), the normally open contact
42
(
3
), to the power supply terminal
51
, one end of the drive coil
42
(
4
), to the power supply terminal
51
and the other end, to the collector of the first transistor
44
(
1
). In the second relay
43
, the movable contact
43
(
1
) is connected to the second connection wiring section
47
, the normally closed contact
43
(
2
), to the drain of the field effect transistor
48
(
1
), the normally open contact
43
(
3
), to the power supply terminal
51
, one end of the drive coil
43
(
4
), to the power supply terminal
51
and the other end, to the collector of the second transistor
45
(
1
). In the first transistor drive circuit
44
, the base of the first transistor
44
(
1
) is connected to the operation controller
40
(
1
) via a series resistor (no reference numeral assigned) and grounded via a base resistor (no reference numeral assigned) and a shunt capacitor (no reference numeral assigned), and the emitter of the same is directly grounded. In the second transistor drive circuit
45
, the base of the second transistor
45
(
1
) is connected to the operation controller
40
(
1
) via a series resistor (no reference numeral assigned) and grounded via a base resistor (no reference numeral assigned) and a shunt capacitor (no reference numeral assigned), and the emitter of the same is directly grounded.
In the switching circuit
48
, the gate of the field effect transistor
48
(
1
) is connected to the operation controller
40
(
1
) and grounded via a resistor (no reference numeral assigned), and the source of the same is directly grounded. In the first resistance voltage dividing circuit
49
, one end of the resistor
49
(
1
) is connected to the first connection wiring section
46
, and the other end of the same is connected to the diagnostic section
40
(
2
) and to one end of the resistor
49
(
2
). One end of the resistor
49
(
2
) is connected to the diagnostic section
40
(
2
), and the other end of the same is grounded. In the second resistance voltage dividing circuit
50
, one end of the resistor
50
(
1
) is connected to the second connection wiring section
47
and the other end of the same is connected to the diagnostic section
40
(
2
) and to one end of the resistor
50
(
2
). One end of the resistor
50
(
2
) is connected to the diagnostic section
40
(
2
) and the other end of the same is grounded.
The motor drive circuit diagnostic device of the configuration described above operates as described below.
When the motor
41
is to be revolved in the forward direction, first an ON signal is supplied from the operation controller
40
(
1
) to the field effect transistor
48
(
1
) of the switching circuit
48
to turn on the field effect transistor
48
(
1
); next an ON signal is supplied from the operation controller
40
(
1
) to the first transistor
44
(
1
) of the first transistor drive circuit
44
to turn on the first transistor
44
(
1
); and a drive current is fed to the drive coil
42
(
4
) of the first relay
42
. Then the movable contact
42
(
1
) is switched over from the normally closed contact
42
(
2
) side to the normally open contact
42
(
3
) side, and a current flows from the power supply terminal
51
to a grounding point via the first connection wiring section
46
, the motor
41
and the second connection wiring section
47
thereby to revolve the motor
41
in the forward direction.
On the other hand, when the motor
41
is to be revolved in the reverse direction, first an ON signal is supplied from the operation controller
40
(
1
) to the field effect transistor
48
(
1
) of the switching circuit
48
to turn the field effect transistor
48
(
1
); next an ON signal is supplied the operation controller
40
(
1
) to the second transistor
45
(
1
) of the second transistor drive circuit
45
to turn on the second transistor
45
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Tang Minh N.
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