JPH0533639U - DC motor restraint detection device - Google Patents

Abstract

(57) [Summary] [Purpose] Since a conventional DC motor restraint detection device uses a heat-sensitive element such as a posistor connected in series with a motor, it is possible to detect malfunctions such as fluctuations in power supply voltage or ambient temperature. There is a problem that the accuracy is lowered. A voltage comparison circuit 11 for comparing a terminal voltage Vt of a DC motor 20 connected in series with a power supply voltage Vc to a resistor R1 and a predetermined reference voltage Vr generated by a reference voltage generation circuit 12, and The reference voltage generating circuit 12 is corrected in proportion to the power supply voltage Vc applied to the DC motor 20 and the temperature characteristic of the DC motor 20. This enables detection in a wide voltage and temperature range and improves reliability.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a drive device for a direct current motor, such as a motor for driving a power window of an automobile. More specifically, it is possible to detect that the direct current motor has been restrained by some factor, which may lead to a more serious accident. It relates to a restraint detection device for prevention.

[0002]

[Prior Art]

 FIG. 4 shows an example of a conventional restraint detection device 90 of this type, in which a DC motor 20 is connected in series with a posistor 91, and the posistor 91 has a characteristic that its resistance value increases as the temperature rises. Therefore, the current passing through the posistor 91 also increases due to the increase in the current due to the constraint of the DC motor 20, and the constraint value increases due to the increase in the resistance value of the posistor 91 due to the increase in the heat generation amount. It is intended to detect the occurrence and burnout of the motor 20.

[0003]

[Problems to be solved by the device]

 However, in the above-described conventional constraint detection device 90, the detection state changes due to environmental changes such as fluctuations in power supply voltage and fluctuations in ambient temperature. For example, when the ambient temperature is low and the power supply voltage drops, the DC motor 20 Detection is not possible even if there is a constraint on the DC motor 20, or if there is a constraint on the DC motor 20 when the ambient temperature is high and the power supply voltage has risen, the constraint has occurred. However, there is a problem in that this problem is generated, and the solution to this problem has become an issue.

[0004]

[Means for Solving the Problems]

 The present invention is, as a concrete means for solving the above-mentioned conventional problems, in a DC motor restraint detecting device for detecting restraint of the DC motor by monitoring a current flowing into the DC motor. The device is a voltage comparison circuit for comparing the terminal voltage of the DC motor connected in series with a resistor to a power source and a predetermined reference voltage by a reference voltage generation circuit, and the reference voltage generation circuit Improves the detection accuracy by providing a DC motor restraint detection device characterized in that the correction is performed in proportion to the power supply voltage applied to the DC motor and the temperature characteristic of the DC motor. This is to solve the above-mentioned conventional problems.

[0005]

【Example】

 Next, the present invention will be described in detail based on an embodiment shown in the drawings. Reference numeral 1 in FIG. 1 denotes a DC motor restraint detecting device according to the present invention (hereinafter simply referred to as detecting device 1). The detecting device 1 is connected in series to the power source side with respect to the power source voltage Vc. Connected to the connection point A between the resistor R1 and the power supply terminal 21a of the control circuit 21 for switching the rotation direction or adjusting the rotation speed, for example, when the direct current motor 20 is restricted and the inflow current increases. Since the voltage drop due to the resistor R1 is increased and the detection potential Vt at the connection point A is decreased, the constraint due to the current flowing into the DC motor 20 can be detected.

Here, the detection device 1 includes a voltage comparison circuit 11 and a reference voltage generation circuit 12 that applies a predetermined reference voltage Vr to the voltage comparison circuit 11, and the inverting input terminal 11 a of the voltage comparison circuit 11 is provided. Is connected to the connection point A, the non-inverting input 11b is connected to the reference voltage generation circuit 12, and the output terminal 11c thereof has a detection potential Vt at the connection point A, that is, the terminal voltage of the DC motor 20 and the reference voltage. If the result of the comparison with Vr is the detection potential Vt> the reference voltage Vr, the L level is output, and if the detection potential Vt <the reference voltage Vr, the H level is output.

In addition, in the present invention, it is assumed that the reference voltage generating circuit 12 is also corrected, and firstly, the reference voltage generating circuit 12 has a voltage divider composed of a resistor R2 and a resistor R3. It is assumed that the circuit is directly connected to the power supply voltage Vc and that the reference voltage Vr also changes in proportion to the voltage fluctuation of the power supply voltage Vc as shown in FIG. 2, and the detection potential Vt is crossed by the fluctuation of the power supply voltage. To prevent malfunctions.

Further, in the present invention, the temperature characteristic of the DC motor 20 is also corrected, and in general, the DC motor 20 has a higher ambient temperature depending on the temperature characteristic of the copper winding used. Since it has a positive temperature characteristic in which the inflow current increases when it rises, the resistor R3 of the reference voltage generating circuit 12 is a resistance element having a positive temperature characteristic, such as a thermistor, so that the reference voltage Vr is increased as shown in FIG. It is intended to prevent malfunction by giving a positive temperature characteristic.

Next, the operation and effect of the detection device 1 of the present invention having the above-described configuration will be described. The present invention corrects the reference voltage Vr for power supply fluctuation and ambient temperature. , Specifically, detection of restraint without causing malfunction even for the DC motor 20 in automobile equipment that is expected to be used in an extremely wide range such as power supply fluctuation of 9 to 18V and operating temperature range of -30 to 80 ° C. Shall be possible.

[0010]

[Effect of the device]

 As described above, according to the present invention, the voltage comparison circuit for comparing the terminal voltage of the DC motor connected in series with the power source and the predetermined reference voltage by the reference voltage generation circuit, Since the voltage generator circuit is a DC motor restraint detection device that is corrected in proportion to the power supply voltage and temperature characteristics, it can be used in automobile equipment etc. where voltage and temperature are used in an extremely wide range. Also, the constraint of the motor can be surely detected, and the excellent effect of improving the reliability of this type of detection device can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a DC motor restraint detection device according to the present invention.

FIG. 2 is a graph showing the operation of voltage correction in the same embodiment.

FIG. 3 is a graph similarly showing the effect of temperature correction.

FIG. 4 is a circuit diagram showing a conventional example.

[Explanation of symbols]

 1 ... DC motor restraint detection device 11 ... Voltage comparison circuit 12 ... Reference voltage generation circuit 20 ... DC motor 21 ... Drive circuit Vc ... Power supply voltage Vt ... Detection potential Vr ... Reference voltage

Claims (1)

[Scope of utility model registration request] 1. A direct current motor restraint detecting device for detecting restraint of the direct current motor by monitoring a current flowing into the direct current motor, wherein the direct current motor restraint detecting device is connected to a power source in series with a resistor. Is a voltage comparison circuit for comparing the terminal voltage of the DC motor with a predetermined reference voltage generated by a reference voltage generation circuit, and the reference voltage generation circuit includes a power supply voltage applied to the DC motor and the DC motor. A DC motor restraint detection device characterized in that a correction proportional to temperature characteristics is performed.