JP3435559B2 - Motor drive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device for controlling the driving and stopping of a motor which is reversibly driven to rotate, and more particularly to a motor drive device which has a simple circuit structure and can reliably ensure a predetermined position when an overcurrent occurs. The present invention relates to a technique for stopping rotation drive of a motor.

[0002]

2. Description of the Related Art For example, a door mirror mounted on an automobile can be automatically switched between a standing position (normally used state) and a stored position (folded state) by remote driving a motor. For driving operation of the door mirror, by connecting a DC motor to a DC power source obtained from a vehicle battery and switching the polarity by a switch operation, the rotation direction can be changed to rotate in the standing direction and the storage direction. As such a motor drive device, for example, Japanese Patent Application Laid-Open No. 4-110 has been known.
Japanese Patent No. 245, "Electric Storage Mirror Control Device" (hereinafter,
What is described in the conventional example) is known. Figure 2
FIG. 6 is an explanatory diagram showing a circuit configuration of the conventional example, in which the polarity of a direct current power source E from a battery is reversibly switched to supply the motor M, so that the motor M is raised and stored. It can be rotated in any direction. As shown in the figure, this door mirror control device
A polarity changeover switch circuit 101 for inverting and connecting the polarity of the DC power supply, an overcurrent detection sensor 102 for detecting whether or not the current value flowing in the motor M exceeds a predetermined value, an overcurrent operation circuit 103, and four Unidirectional current circuit 104, which is formed as a bridge circuit by the diode of, a delay circuit 105, a relay circuit 106 and a relay contact 107
It consists of and.

In the above structure, when the contacts of the polarity changeover switch circuit 101 are connected to the a11 and a12 sides,
A current flows through the motor M in the direction of I11 via the overcurrent detection sensor 102, and the motor M rotates in the standing direction. Then, when the door mirror reaches the final end and the rotation of the motor M is forcibly blocked, the current value increases, so the voltage across the overcurrent detection sensor 102 rises and the overcurrent operation circuit 10
The three transistors Q11 and Q12 become conductive. This allows
Since the relay R of the relay circuit 106 is turned on, the relay contact 107 is switched from the contact b21 to the contact a21 and from the contact b22 to the contact a22, and the current flowing into the motor M is cut off, so that the motor is stopped. When the contacts of the polarity changeover switch circuit 101 are connected to the opposite side, that is, the sides of b11 and b12, a current flows in the motor M in the direction of I12, so that the door mirror rotates in the retracted direction and reaches the final end.
The relay contact 107 is cut off and the motor M is stopped in the same procedure as described above.

[0004]

However, in the circuit described in the above-mentioned conventional example, although the current can be cut off when the door mirror reaches the final end,
Overcurrent operation circuit 103, delay circuit 105, relay circuit 1
Since a complicated circuit such as 06 is used, not only the number of parts increases, the circuit scale increases, but also the cost increases.

Further, since the relay contact 107 is used to switch the supply and interruption of the electric current to the motor M, a malfunction may often occur. That is, the DC power source E of the circuit shown in FIG. 2 uses a battery mounted in a vehicle, and in general, the battery mounted on the vehicle often has a fluctuation in power supply voltage. Despite the voltage being supplied to the coil, malfunctions such as the relay contact 107 coming off due to vibration or the like will occur. In such a case, the motor M may not rotate even if the switch circuit 101 is turned on, or conversely, the current supply to the motor M may not be interrupted even though the overcurrent is detected.

Further, the transistors Q11 and Q12 mounted in the overcurrent operation circuit 103 are made to conduct together when an overcurrent is detected. At the time of standing, a current flows through the transistor Q11, and at the time of storage, the transistor Q11 is turned on. Current flows through Q12. Therefore, although the transistors Q11 and Q12 use parts having the same characteristics, in reality, there is a slight difference in characteristics, so that a detection error occurs.
That is, although the transistors Q11 and Q12 use parts of the same standard, they do not always conduct when the same voltage is applied, and therefore the current values cut off at the time of standing up and at the time of storage differ, There is a drawback that the current detection tends to vary.

The present invention has been made in order to solve such a conventional problem, and an object thereof is to reduce the number of parts, prevent malfunction, and detect variations in current. It is to provide a motor drive device.

[0008]

Means for Solving the Problems] To achieve the above object, the invention according to the claims 1, causes reversibly rotatably driven DC motor, the supply voltage is in the overcurrent and test knowledge In a motor drive device to be stopped, a DC power supply, a polarity reversing switch installed on the output side of the DC power supply and reversibly switching the polarity, a DC motor installed on the output side of the polarity reversing switch, and a DC motor A bridge circuit that is installed in the latter stage side and always flows current in the same direction regardless of the connection state of the polarity reversing switch, and is installed in the latter stage side of the bridge circuit when the current value exceeds a certain level. A current detection circuit for interrupting the current to stop the rotation of the DC motor, the current detection circuit being conductive when the power is turned on and supplying a drive current to the DC motor. The point switch, a second proximity switch for interrupting the conduction of said first non-contact switch when an overcurrent occurs, while at least have a first resistor
(R1) and the first contactless switch as the first contactless switch.
Series connection with transistor (Q1), second resistor (R2)
And a second transistor as the second contactless switch.
(Q2) in series connection, and the third resistor (R3) and
Series connection with 4 resistors (R4), 3 parallel connection times
And is parallel to the fourth resistor.
A capacitor (C1) is placed in the
The connection point of the fourth resistor is connected to the base of the second transistor.
The connection point between the second resistor and the second transistor is
Characterized by being connected to the base of one transistor
It

[0009]

According to a second aspect of the present invention, when the second transistor is turned on, the current flowing through the current detection circuit is smaller than the drive current of the DC motor. The resistance value of the fourth resistor is set.

According to the present invention constructed as described above, since the voltage supplied from the DC power source is reversibly applied to the DC motor by the polarity reversing switch, the rotation direction of the DC motor is reversed by operating this switch. be able to. Also, on the rear side of the DC motor, a voltage is always applied in a fixed direction by the bridge circuit regardless of the connection state of the polarity reversing switch, so the current detection circuit installed on the rear side of the bridge circuit always operates. Current will flow from the same direction. Therefore, since it is not necessary to install a current detection circuit for each of the forward rotation and the reverse rotation, it is possible to reduce the number of components, and a current detection circuit configured of the same circuit element for both the forward rotation and the reverse rotation is used. Since the overcurrent is detected and the current supply to the DC motor is cut off, the motor can be stopped at the same overcurrent value during forward rotation and reverse rotation.

Further, when the power is turned on, the first contactless switch is turned on to supply the power supply voltage to the DC motor, and the second contactless switch is turned on to turn on the first contactless switch.
Since the non-contact switch is cut off and the current supply to the DC motor is stopped, compared to a relay contact, it is more resistant to battery voltage fluctuations and mechanical vibrations and can be switched on and off reliably. Like

Further, as the first and second contactless switches
Two transistors Q1, Q2, and the resistors R1 to R4,
A current detection circuit is constituted by the capacitor C1 and the first transistor Q1 is turned on when the power is turned on, so that a current flows through the route passing through the resistor R1 and the transistor Q1, thereby driving the DC motor. Further, in the invention described in claim 2, when an overcurrent occurs in the circuit, such as when the rotation of the motor reaches the final end, the second transistor Q2 is turned on, which turns off the first transistor Q1. . At this time, a dark current flows, but since this current value is smaller than the drive current of the DC motor, the drive of the DC motor is stopped.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration of an embodiment of a motor drive device to which the present invention is applied, in which a voltage supplied from a battery power source E is reversibly applied to a DC motor M.
The motor M can be rotated in the normal direction and the reverse direction, and the motor M can be stopped when the motor M rotates and reaches the final end.

As shown in the figure, this drive device has a switch S1 (polarity reversing switch) for reversibly switching the output end of a power source E, a DC motor M connected to the contact c1 side of the switch S1, and a switch S1. a PTC element connected to the contact c2 side of the (element resistance value with increasing current increases), a bridge circuit 21 consisting of D1 to D4, the current detection known circuits disposed downstream side of the bridge circuit 31
, And are roughly divided into.

The current sense latch circuit 31, the cathode side of the diode D1 (D3) constituting the bridge circuit 21 (this is the point P1), (and which the point P2) anode side of the diode D2 (D4) It is installed between and and is mainly divided into three systems. That is, point P1
Is connected via a resistor R1 to the collector of a transistor Q1 whose emitter is connected to a point P2. The point P1 is connected to the base of the transistor Q1 and the collector of the transistor Q2 via the resistor R2, and the emitter of the transistor Q2 is connected to the point P2. Further, the point P1 is connected to the base of the transistor Q2 and the resistor R4 via the resistor R3, and the emitter of the transistor Q2 and the other end of the resistor R4 are connected to the point P2. A capacitor C1 is arranged in parallel at both ends of the resistor R4.

Further, in the above description, the resistance R1 is set to a resistance value sufficiently smaller than the resistances R2, R3 and R4. That is, R1 << R2, R3, R4.

Next, the operation of this embodiment configured as described above will be described. Now switch S1 to contact a
When connected to the side of 1, a2, the current is from the power source E to the contact a.
1, c1, DC motor M, diode D1, resistor R3,
Capacitor C1, diode D2, PTC, contact c2,
It will flow through a2. That is, at the time of power-on, the transistors Q1, Q2 are both set OFF state, and, since the capacitor C1 charge is not accumulated, in the current detection Intellectual circuit 31 at the time of power-on, the resistor R3, capacitor C1 An electric current will flow through.

When this current value is I1, a voltage of I1 * R3 is applied to both ends of the resistor R3, and this voltage I1 * R3 is applied between the points P1 and P2. Therefore, this voltage is also applied between the base and emitter of the transistor Q1, and the transistor Q1 is rendered conductive. That is, a current flows through the resistor R1 and the transistor Q1, and as described above, since the resistance value of the resistor R1 is set to a small value, the voltage drop is small, and the current flowing through this path causes The motor M will continue to be driven. It should be noted that, after a lapse of a certain time from the power-on, the capacitor C1 is saturated and the conduction is cut off, and the current flowing through the resistor R3 is guided to the point P2 via the resistor R4. That is, when the motor M is driven, a weak current flows through the resistors R3 and R4.

When the motor M reaches the final end and is forcibly stopped, an overcurrent is generated, so that the resistance R1
As the value of the current passing through the resistor increases, the value of the current flowing through the resistors R3 and R4 also increases. Therefore, the voltage across the resistor R4 increases, and when this voltage exceeds a certain value, the transistor Q2 becomes conductive and the transistor Q2 becomes conductive.
Since the base and the emitter of 1 are short-circuited, the conduction of the transistor Q1 is blocked. As a result, the current flowing through the resistor R1 and the transistor Q1 is cut off, and the flowing current is only the current flowing through the resistors R3 and R4 and the current flowing through the resistor R2 and the transistor Q2. Here, since the resistance values of the resistors R2, R3 and R4 are respectively set to large values, the current value becomes extremely small and the rotation of the motor M is stopped. That is, the current flowing through the resistor R2, the transistor Q2, and the resistors R3 and R4 becomes a dark current.

On the other hand, when the connection of the switch S1 is reversed, this time the contacts a2, c2, PTC, diode D
3, point P1, point P2, diode D4, DC motor M,
A current flows through the contacts c1 and a1, and a current flows through the motor M in the opposite direction to the above. That is, the motor M rotates in the reverse direction. Where switch S1
Since no current flows through the circuit during the inversion operation, the electric charge accumulated in the capacitor C1 is discharged, and when the switch S1 inverts, the current again flows through the capacitor C1.

At this time, the direction of the current flowing to the current detection circuit 31 is the same as that in the normal rotation of the motor M. Therefore, the motor M rotates in the same procedure as described above, and stops when it reaches the final end. Will be done. That is, it is not necessary to prepare the current detection circuit 31 for each of the forward rotation and the reverse rotation, and one circuit can be used for both the forward rotation and the reverse rotation.

Thus, in the motor drive device according to this embodiment, the transistors Q1 and Q2 (first and second transistors) are provided.
Non-contact switch) and a few other components to form the current detection circuit, the number of components can be significantly reduced, and the size and cost can be reduced. Further, since the contactless switch is used, malfunction is less likely to occur due to battery voltage fluctuations and mechanical vibrations, and reliability is improved. Further, when the motor M rotates in the forward direction and in the reverse direction, the current is detected by the same circuit configuration and the motor M is stopped, so that there is no influence of the variation of the circuit elements, and the position is surely set to the predetermined position. Thus, the rotation of the DC motor M can be stopped. Further, the capacitor C1 can also serve as a filter for current noise.

The present invention is not limited to the motor drive device used to control the rotation of the door mirrors of an automobile.
Of course, it can be applied to the rotation control of other DC motors.

[0025]

As described above, in the motor drive device of the present invention, the bridge circuit is installed at the rear stage side of the DC motor, and the current detection circuit is mounted at the rear stage side of the bridge circuit. Since this current detection circuit is composed of only the first contactless switch, the second contactless switch and several other elements, it is possible to significantly reduce the number of parts as compared with the conventional one. Therefore, the circuit can be downsized and the cost can be reduced. Further, since the first contactless switch conducts the current and the second contactless switch interrupts the conduction, compared with the conventional relay contact, the influence of the battery voltage fluctuation and mechanical vibration is reduced. It is difficult to receive and can prevent malfunction.

Furthermore, since always be the voltage of a predetermined direction is applied to the current sensing circuit regardless of the rotational direction of the direct current motor, a current detection circuit for stopping the motor overcurrent was examined knowledge, the forward rotation , It is not necessary to separately provide each for reverse rotation, and one circuit can be commonly used, and there is no influence of variations in circuit elements.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of a motor drive device to which the present invention is applied.

FIG. 2 is a circuit diagram showing a configuration of a conventional motor drive device.

[Explanation of symbols]

21 bridge circuit 31 Current detection circuit R1 to R4 resistance D1-D4 diode Q1 1st transistor (1st contactless switch) Q2 Second transistor (second contactless switch) C1 capacitor PTC PTC element E DC power supply M DC motor S1 switch (polarity inversion switch)

Claims (2)

(57) [Claims] 1. A with driving reversibly rotating the direct current motor, when an overcurrent has been examined knowledge in the motor driving apparatus for stopping the supply of the voltage, a DC power supply, is installed at the output side of the DC power source, A polarity reversing switch that reversibly switches the polarity, a DC motor that is installed on the output side of the polarity reversing switch, and a DC motor that is installed on the rear side of the DC motor, always in the same direction regardless of the connection state of the polarity reversing switch. A bridge circuit for passing a current, and a current detection circuit which is installed on the rear side of the bridge circuit and interrupts the current to stop the rotation of the DC motor when the current value exceeds a certain level. However, the current detection circuit connects the first contactless switch that conducts a drive current to the DC motor when the power is turned on and the first contactless switch that conducts when an overcurrent occurs. A second proximity switch to disconnection, together with at least have a, as the first resistor (R1) a first proximity switch
Connected in series with the first transistor (Q1) of the
The anti (R2) and the second contactless switch as the second
Series connection with transistor (Q2) and third resistor
(R3) and a fourth resistor (R4) connected in series, three systems
And a parallel connection circuit for the fourth resistor.
A capacitor (C1) is arranged in parallel to the
The connection point between the third resistor and the fourth resistor is the second transistor.
Connected to the base of the second resistor and the second transistor
The connection point of is connected to the base of the first transistor.
And a motor drive device. 2. The second transistor is turned on
When the current flowing through the current detection circuit is the DC motor
So that the driving current becomes smaller than the driving current of
2. The resistance value of the resistor is set.
Motor drive.