JPH0972448A - Motor drive circuit - Google Patents

Abstract

(57) [PROBLEMS] To reduce the size of a drive circuit without damaging a motor even when signals are erroneously input to two contacts of a control switch such as a three-way motorized valve. SOLUTION: The electric current flowing through one field winding 8 is in only one direction, and the direction of the electric current flowing through the armature 2 is alternately changed by two transistors 5 and 6 to reciprocate the motor. Parallel circuits 9 and 10 bypassing the circuit that energizes the armature 2 and the field winding 8 from the micro-switches 3 and 4.
Set up. The parallel circuits 9 and 10 connect between the microswitches 3 and 4 and the control switch 1 and between the power supply 20 and the field winding 8, respectively. Even if a current is erroneously applied to both contacts 1a and 1b of the control switch,
The erroneous signal is guided to the parallel circuit and controlled by the transistor so as not to flow to the armature 2 and the field winding 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive circuit suitable for use in a motor-operated valve or the like, which prevents deterioration of function even if an erroneous signal is generated in the drive circuit. The present invention relates to a drive circuit suitable for the case.

[0002]

2. Description of the Related Art As a conventional three-way motorized valve, a drive shaft of an electric motor and a valve shaft of a three-way ball valve using a spherical valve body in the valve portion are connected to each other and a changeover switch for changing over the valve shaft is provided separately. It is known that the electric motor is normally or reversely rotated by the switching command of the control switch to switch the valve (for example, JP-A-49-8821). In this case, if an erroneous signal such that the two contacts of the control switch are simultaneously connected for some reason is input, there is a problem that the drive motor burns out. For example, the American standard MIL-V for aircraft fuel valves.
-8608 (miritary specificat)
Ion) drive circuits are known.

According to this standard, as shown in the circuit diagram of FIG. 5, microswitches 33 and 34 connected to both contacts 31a and 31b of a control switch 31 are provided, and each microswitch 33 and 34 has an armature 32. The field windings 38 and 39 for exciting the coil are provided in parallel, and the relay 35 for connecting / disconnecting the minus side of the armature 32 and the minus side of the power source.
A circuit connected to is provided, and this relay 35 bypasses the input of an erroneous signal (indicated by a dashed arrow) so as not to flow to the armature 32.

[0004]

With this standard, the burnout of the drive motor can be prevented even if there is an erroneous signal, but the field winding 3 for rotating the armature 32 in the forward or reverse direction is used.
Since both 8 and 39 are required and the relay 35 is used to prevent an erroneous signal, the width of the relay 35 itself is additionally required and there is a problem that the drive circuit becomes large. Moreover, if a relay is used, there is a problem that the contact of the relay is inevitably worn and damaged and reliability is lowered.

Further, since the current flowing through the armature 32 flows from the field windings 38, 39 side to the relay 35 side, the minus side brush is worn away from the plus side brush and is worn away. However, there is a problem that the life of the armature 32 is shortened.

Further, when the valve body connected to the armature 32 is in the intermediate position of the movement range, the operation switch 31 fails and the operation signals to the position 〓 and the position 〓〓 are simultaneously input, the field Since the current continues to flow through the windings 38, 39 and the armature 32, there is a problem that the field windings 38, 39 and the armature 32 burn out.

The present invention has been made in order to solve such a problem. Even if an erroneous signal is generated, the armature is prevented from being burnt out and the brush is worn out without using a relay. It is an object to provide a drive circuit for a motor.

[0008]

To this end, in the invention according to claim 1, an armature having a drive shaft around which a field winding is wound, and a plurality of armatures that are opened / closed to disconnect or energize the armature from different directions are provided. Switch, a control switch that distributes current to each switch and supplies it, a parallel circuit in which the armature is connected in parallel on the control switch side of each switch, and the direction of the current that flows to the armature is changed. And a transistor for guiding a signal to a parallel circuit.

In the invention according to claim 2, the field winding is wound and the armature is provided with a drive shaft, and the armature is connected to each pole side of the armature by opening and closing to cut off the current to the armature. The switch includes a switch, a control switch that distributes a current to each switch, and a parallel circuit that is connected in parallel with the armature on the control switch side of each switch. A transistor is provided, which supplies a current and causes an erroneous signal input to the other switch to flow into the parallel circuit.

In the invention according to claim 3, the field winding is wound and the armature is provided with a drive shaft, and the armature is connected to each pole side of the armature by opening and closing to supply and disconnect the current to the armature. A switch, a control switch for distributing current to each switch, a parallel circuit connected in parallel with the armature on the control switch side of each switch, an emitter on the armature side, and a field winding side on the side. A transistor with a collector connected and a base connected to the parallel circuit, a base current limiting resistor connected between the contact of the base and the negative side of the power supply, or ground, and between the armature and the switch. Each transistor is provided with a diode, and each transistor supplies a current to the armature when one switch is closed, and causes an erroneous signal input to the other switch to flow into the parallel circuit.

[0011]

1 is a circuit diagram showing an embodiment of the present invention. For example, an armature 2 for reciprocating a valve shaft of a three-way motorized valve to a position 〓 and a position 〓〓. The figure shows the case of use in a drive circuit. 1 in the figure
Is a control switch that distributes the current of the DC power source 20 to the contacts 1a and 1b. The contact 1a is connected to the microswitch 3 via the point A of the connection terminal, and the contact 1b is connected to the microswitch 4 via the point D as well. There is. Each of the micro switches 3 and 4 is connected to one of the two poles of the armature 2 so as to switch ON / OFF of energization of the armature 2. Therefore, in this example, since the armature 2 is energized from either one of the microswitches 3 and 4, the polarities of the two poles of the armature 2 are switched to the positive side and the negative side, so that the connected valve can be opened. Change in multiple directions.

In this example, when the micro switch 3 is in the ON state, the valve shaft position of the motor-operated valve is in position 〓, and when the micro switch 4 is in the ON state, the valve shaft position of the motor operated valve is in position 〓〓. , And each of the micro switches 3 and 4 has a circumference of a cam 2b which is rotated by the drive of the drive shaft 2a of the armature 2 like the known means shown in the partial sectional plan view of FIG. The ON / OFF is determined in synchronism by energizing one of the recesses provided in the. However, this method may be performed by other means.

Diodes 16 and 17 for preventing backflow are provided between the switches 3 and 4 and the armature 2 to prevent the current passing through the armature 2 from being supplied to the switches 3 and 4. There is. Further, between the armature 2 and the field winding 8,
PNP type transistors 5 and 6 are connected to each other, and an emitter is connected to the armature 2 side and a collector is connected to the field winding 8 side. Further, a field winding 8 is connected between the collectors of the transistors 5 and 6 and the power supply 20, and an operation display circuit 7 is formed in parallel with the field winding 8. The field winding 8 is connected to the negative side of the power source 20 via the contacts C and E of the connection terminals. An operation display lamp 13 is connected to the operation display circuit 7 so that the armature 2 emits light when it is energized and driven. The field winding 8 is wound around and integrated with the armature 2 to form a drive motor, and a current in one direction always flows through the field winding 8.

The bases of the transistors 5 and 6 branch between the contacts 1a and 1b of the control switch 1 and the microswitches 3 and 4 and are connected 19 between the field winding 8 and the power supply 20 in a parallel circuit. 9 and 10 are connected 14 and 15, respectively, and further, base current limiting resistors 11 and 12 are connected between the base contacts 14 and 15 and the contact 19.
However, the contacts 19 of the parallel circuits 9 and 10 may be grounded without being connected between the field winding 8 and the power supply 20.

In the drive circuit having the configuration shown in FIG. 1, the control switch 1 is on the contact 1a side (shown by a broken line), the micro switch 3 is OFF and the micro switch 4 is ON, so that the valve shaft is in the position 〓. And the circuit is in the OFF state. In order to switch the valve shaft from this state, the control switch 1 may be switched to the contact 1b as shown by the arrow (shown by a solid line). Then, a current flows to the armature 2 through the terminal D, the micro switch 4, and the diode 17, and further a current flows to the field winding 8 through the transistor 5, so that the drive motor is driven and the valve shaft is in the position 〓〓.
Moved to At this time, the transistor 5 is turned on because the base current of the parallel circuit 9 flows (indicated by the arrow) through the base current limiting resistor 11, and the emitter-collector is electrically connected to allow the current to flow. On the contrary, since a current flows in the parallel circuit 10, the emitter and collector of the transistor 6 become non-conductive. Further, the drive motor rotates to rotate the valve shaft, and at the same time, the above-described cam rotates to switch the contacts of the microswitches 3 and 4 to change the state of FIG. 1 to the state of FIG.

In FIG. 3, the valve shaft is in the position 〓 and the control switch 1 is at the contact point 1b (shown by the broken line). Therefore, the micro switch 3 is ON and the micro switch 4 is OF.
It is in the state of F. In order to switch the valve shaft to the position 〓 from this state, the contact of the control switch 1 may be switched to 1a (shown by the solid line). Then, a current flows to the armature 2 through the terminal A, the microswitch 3, and the diode 16, and further a current flows to the field winding 8 through the transistor 6, so that the drive motor is driven and the valve shaft is moved to the position 〓. .

At this time, the transistor 6 is turned on because the base current flows through the parallel circuit 9 through the base current limiting resistor 12 (indicated by the arrow), and the emitter-collector becomes conductive, allowing the current to flow. On the contrary, since the current flows in the parallel circuit 9, the emitter of the transistor 5
There is no conduction between the collectors. Then, in the armature 2, the valve shaft flows in the opposite direction to the movement from the position 〓 to the position 〓, so that the drive motor rotates in the reverse direction and moves from the position 〓 to the same 〓. Further, the drive motor rotates to rotate the valve shaft, and at the same time, the above-mentioned cam rotates to switch the contacts of the microswitches 3 and 4, and the state of FIG. 3 returns to the state of FIG. When the transistors 5 and 6 are energized, the operation display lamp 13 is turned on and can be visually checked.

Next, a case will be described in which an erroneous signal that causes simultaneous connection to the contacts 1a and 1b of the control switch 1 is input. FIG. 4 is a circuit diagram showing a state in which the contact 1a is connected in FIG. 3 (the power supply current 20 is indicated by a solid line), but a state in which an erroneous signal is also input to the contact 1b is indicated by a broken line. . Since the current passing through the terminal A flows into the parallel circuit 9 and returns to the power supply 20 through the terminal E, the transistor 5 is made non-conductive, and the current does not flow from the microswitch 4 to the armature 2. At the same time, even if an erroneous signal is applied through the terminal D, this current flows to the parallel circuit 10 and makes the transistor 6 non-conductive to the power supply 20. However, since the transistor 5 is originally made non-conductive, the diode 10 , Does not pass through the armature 2 and the field winding 8. Therefore, problems such as burnout of the armature 2 do not occur. That is, the connection from the terminal A to the base of the transistor 5 and the connection from the terminal D to the base of the transistor 6 play the role of an interlock circuit.

In the explanation of FIG. 4, it is assumed that the valve shaft is in the position 〓〓, but the control is performed regardless of whether the valve shaft is in the position 〓 or 〓〓, or in the intermediate position. The current flowing through either of the contacts 1a, 1b of the switch 1 flows into the parallel circuit 9 or 10 to make the transistors 5 and 6 non-conductive, and the current flows or continues to flow in the armature 2, the field winding 8 and the like. Prevent the deterioration of the function of the drive motor.

As described above, according to this embodiment,
Even if an erroneous signal is generated in the control switch 1 of the drive motor and a current flows in the micro switches 3 and 4, the transistors 5 and 6 prevent the current from flowing to the armature 2, and the current due to the erroneous signal is paralleled to the parallel circuit. Armature 2 for flowing to 20, 21
The field winding 8 is not damaged.

Further, in this example, in order to safely avoid an erroneous signal, a relay is not adopted, various problems caused by adopting the relay can be solved, and moreover, a plurality of field windings are not used and a single field winding is used. Therefore, a small drive circuit can be realized by using a semiconductor. Further, since the direction of the current flowing through the armature 2 is switched according to the operating direction of the valve shaft,
It is possible to solve the problem that the minus-side brush is worn away from the plus-side brush as in the conventional case and is worn away, and as a result, the life of the armature 2 is shortened.

Further, when the operation switch 1 fails and the operation signals to the position 〓 and the position 〓〓 are simultaneously input while the valve body connected to the armature 2 is in the intermediate position of the movement range, It is possible to prevent the current from continuously flowing through the field winding 8 and the armature 2.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a drive circuit according to an embodiment of the present invention.

FIG. 2 is a front view showing a cam for opening and closing the micro switch according to the embodiment of the present invention.

FIG. 3 is a circuit diagram of a drive circuit according to an embodiment of the present invention.

FIG. 4 is a circuit diagram of a drive circuit according to an embodiment of the present invention.

FIG. 5 is a circuit diagram showing a conventional motor drive circuit.

[Explanation of symbols]

1 is a control switch, 1a is a contact, 1b is a contact, 2 is an armature, 3 is a microswitch, 4 is a microswitch, 5
Is a transistor, 6 is a transistor, 8 is a field winding, 9
Is a parallel circuit, 10 is a parallel circuit, 11 is a base current limiting resistor, 12 is a base current limiting resistor, 14 is a base contact, 1
Reference numeral 5 is a base contact, 16 is a diode, 17 is a diode, and 20 is a DC power supply.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Headquarters Chihiro Hiroshi 2-6-2 Otemachi, Chiyoda-ku, Tokyo Sanryo Electric Engineering Co., Ltd.

Claims (3)

[Claims] 1. An armature having a drive shaft wound with a field winding, a plurality of switches for opening and closing to supply and disconnect the current to the armature from different directions, and a control for distributing and supplying the current to each switch. A switch, a parallel circuit connected in parallel with the armature on the control switch side of each switch, and a transistor for changing the direction of the current supplied to the armature and guiding an erroneous signal to the parallel circuit. Motor drive circuit. 2. An armature having a drive shaft wound with a field winding, a switch connected to each pole side of the armature by opening and closing to supply and disconnect current to the armature, and a current to each switch. And a parallel circuit connected in parallel with the armature on the control switch side of each switch, and supplies a current to the armature when one switch closes and the other switch. A drive circuit for a motor, comprising a transistor for allowing an input erroneous signal to flow into the parallel circuit. 3. An armature having a drive shaft wound by winding a field winding, a switch connected to each pole side of the armature by opening and closing to supply and disconnect the current to the armature, and a current to each switch. Control switch of each switch, a parallel circuit in which the control switch side of each switch is connected in parallel with the armature, an emitter on the armature side, and a collector on the field winding side. Each transistor has a base connected transistor, a base current limiting resistor connected between the contact of the base and the negative side of the power supply, or ground, and a diode provided between the armature and the switch. A drive circuit for a motor, characterized in that when one of the switches is closed, a current is supplied to the armature to cause an erroneous signal input to the other switch to flow into the parallel circuit.