JPS61281981A - Dc motor rotor inspecting device - Google Patents

Abstract

PURPOSE:To discriminate defective goods by discriminating whether the variance of the voltage detected by a voltage detecting means provided in series for a DC motor is between upper and lower limit reference values or not. CONSTITUTION:A certain voltage is applied to a motor 1, and a voltage generated in proportional to the current outputs a waveform which is changed to indicate a maximum value in each slot of a rectifier of a rotor of the motor 1. This output waveform is amplified by an amplifying circuit 3 and has the noise eliminated by a filter 4 to take out a signal having required frequency components. The height of all peaks of the output waveform is constant in case of an indefectible work but is varied in case of a defective work. This height is discriminated by the first and the second comparing circuits 5 and 7, and the first comparing circuit 5 outputs a defect work discrimination signal if it is higher than a reference voltage determined by a resistor 6, and the second comparing circuit 5 outputs said signal if it is lower than a reference voltage determined by a resistor 8. Thus, a defective good discriminating circuit 9 is operated to discriminate defective goods.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Use] The present invention relates to an inspection device for determining whether a rotor of a DC motor is good or bad.

"Conventional Technology" Conventional inspection equipment converts changes in the current flowing through the rotor of a DC motor via a commutator into changes in the voltage across the resistors and displays them on an oscilloscope, allowing an operator to visually check whether the rotor is in good condition or not. The judgment criteria were not clear, and incorrect judgments were sometimes made.In other words, there were variations and errors in visual judgment by workers, and they could mistakenly classify defective products as non-defective. There is a possibility that the judgment will be incorrect, which is a problem from the perspective of reliability.Also, if the judgment criteria changes due to a change of worker, or if the judgment is made by an unskilled worker. However, there were problems such as difficulty in making decisions and reducing work efficiency.

"Problems to be Solved by the Invention" The present invention was made to solve the above-mentioned problems, and it provides a DC motor that can accurately determine defective products and eliminates the need for an oscilloscope. The purpose of the present invention is to provide a rotor inspection device.

[Means for Solving the Problems] According to the present invention, the voltage detection means provided in a path in series with the DC motor and the change in voltage detected by the voltage detection means have an upper limit and a lower limit. There is provided a DC motor rotor inspection device characterized by comprising a determining means for determining whether or not the value is between two reference values, and a display means for displaying the determination result of the determining means.

"Operation" According to the above configuration, the determination means determines whether the rotor is good or bad, and the display means displays whether the rotor is good or bad. Therefore, when a quick voltage change is visually judged on the oscilloscope screen, it is possible to By comparison, it is possible to accurately determine whether the product is defective.

"First Embodiment" According to the first embodiment of the present invention, the voltage detection means is a resistor connected in series to the DC motor, and the determination means is connected to both ends of the resistor. An amplifier circuit that amplifies changes in the generated voltage signal, a noise filter that removes noise from the signal amplified by the amplifier circuit, and a parallel-connected circuit that compares the output of the noise filter with different reference voltage values. and a determination circuit that outputs a pulse signal when the rotor is defective based on the output signals of the first and second comparison circuits. I can do it. According to this first embodiment, there is an advantage that an inspection device that can display stable judgment results with a relatively simple structure can be obtained.

[Second Embodiment 11] According to the second embodiment of the present invention, in the first embodiment, further, the reference voltage value of the first comparison circuit is equal to the reference voltage value of the second comparison circuit. The voltage value is set to be higher than the reference voltage value of the circuit, and both reference voltage values are configured to be arbitrarily set by respective variable resistors. According to the second embodiment, there is an advantage that the quality of the rotor can be easily and accurately determined even for DC motors having various rated currents, etc.

"Embodiment" A first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

#1 In the block diagram shown in Figure 1, 1 is a DC motor. The quality of this DC motor is determined. 2 is a variable resistor. The output waveform necessary for determining whether both ends of this resistor 2 are rising is detected. 3 is an amplifier circuit, and 64 is a noise filter that amplifies the change in the input voltage, which removes noise from the input voltage waveform and outputs only the necessary waveform.

A first comparison circuit 5 compares the reference voltage set by the variable resistor 6 with the input voltage, and generates an output when the voltage at the input terminal is higher than the reference voltage set by the variable resistor 6. The variable resistor 6 is for setting a reference voltage for comparison of the first comparison circuit 5, and 7 is a second comparison circuit.
The reference voltage set by the variable resistor 8 is compared with the input voltage, and when the input voltage is smaller than the reference voltage set by the variable resistor 8, an output is generated. Here, the case where the input W voltage is smaller than the reference voltage does not mean the lower limit of the waveform, but as shown in Figure #12 (f), the maximum value of the input voltage waveform is lower than the reference voltage. refers to a case,
This is a waveform abnormality that occurs when a defect occurs, such as when the winding is not sufficiently caught in the commutator claw, and is easily overlooked by visual inspection.

The variable resistor t18 sets a reference voltage for comparison of the second comparator 7. 9 is a defective judgment circuit, and the first or second
Based on the presence or absence of outputs from the comparison circuits 5 and 7, it is determined whether the DC motor 1 is a defective product or a non-defective product, and an output is generated when the DC motor 1 is a defective product. The i-indicator circuit 10 notifies the operator of the determination signal output by the determination circuit 9 using a lamp, a buzzer, or the like.

Next, the operation will be explained using the waveform diagram shown in FIG. By applying a constant voltage VDD to the DC motor 1, a voltage proportional to the current is generated across the resistor 2. This voltage changes to a maximum value for each slot of the commutator in the DC motor 1, and is output in the state shown in FIG. 2(a). This output waveform is amplified by the amplifier circuit 3 to a size that can be compared by the next-stage comparison circuit 5.7. Figure 2 (
Since the output waveform shown in b) has amplified noise, there is a risk of erroneous judgment if compared as is. Therefore, the noise is filtered through a filter 4 and the necessary frequency components are extracted from the output waveform. In the case of a good workpiece, the waveform outputted through the noise filter 4, which extracts the signal shown in Figure 2(c), has a nearly constant height for all peaks as shown in Figure 2(d). However, when data of a defective workpiece is measured, the size of the waveform is 6. This is determined by the first comparison circuit 5 and the second comparison circuit 7. The first comparator circuit 5 detects that the maximum value of the output voltage of the motor 1 is vi
As shown in FIG. 2(e), every time the voltage becomes higher than the reference voltage determined by the resistor 6, a signal is output which is the basis for determining whether the voltage is defective. The second comparator circuit 7 outputs a signal that serves as the basis for a defective judgment every time the maximum value of the output voltage of the motor 21 becomes lower than the reference voltage determined by the resistor 8 (the signal for a good judgment is missing). When either one of these two signals is output, the defect judgment circuit 9 is activated and outputs a defect judgment signal that allows the display circuit 10 to operate stably. is displayed on the display circuit 10 to notify the operator of the quality of the motor 1. According to the configuration of the first embodiment described above, a stable determination result can be displayed based on the signal detected from the motor 1. It has the advantage of being possible.

Next, a second embodiment of the present invention is shown in the circuit example shown in FIG.

By rotating the motor 1, the current waveform from the resistor 2 is detected as a voltage. This is amplified by an amplifier circuit 3 using an operational amplifier, and noise is removed by a noise filter 4 also using an operational amplifier. T, , T are waveform terminals for indicating the states of the output waveforms of the amplifier circuit 3 and the noise filter 4, respectively. 5 is a first comparison circuit using an operational amplifier, and a variable resistor 6 sets an upper limit reference voltage. When the inverting terminal (-) of the operational amplifier of the first comparison circuit 5 becomes a higher voltage than the non-inverting terminal (+),
The signal at the waveform terminal T of the defect determination circuit 9 becomes a high-level defect signal via the transistor 91 and the inverting amplifier 92, and it is determined that the motor 1 is defective. 7 is a second comparison circuit, and a lower limit reference voltage is set by a variable resistor 8.

The lower limit reference voltage here is not for determining an abnormality in the minimum voltage of the waveform, but for determining an abnormality in the maximum voltage, as described in the previous section 12.

Therefore, in the case of a non-defective workpiece, at the peak 7α of all waveforms, the transistor 93 is applied to the waveform terminal T via the inverting amplifier 94.
, the point at which a pulse signal is output at a predetermined interval T^ determined by the rotational speed of the motor 1 is the adjustment value of the variable resistor 8. Therefore, in the case of defective workpieces, when a waveform with a low peak value is input to the NS2 comparator circuit 7, the pulse signal from the waveform/terminal T is lost, so the one-shot multivibrator 95 is and waveform terminal T
.

A high level defect signal is output. And this 2
Two defective signals are displayed by the display circuit 10.

The one-shot multivibrator 95 is controlled by a variable resistor so as to wait for a time constant T that is slightly longer than the predetermined interval T^ and shorter than twice the predetermined interval T^.
According to the second embodiment, in which the number is set to 6 or more (T^<T<2T^), a stable determination result can be displayed.

“Effect” As mentioned above, the inspection of the present invention! ! The device has the above-mentioned configuration, and detects changes in the current flowing through the motor's circuit as a change in voltage, and determines whether the change in voltage is between two reference values, an upper limit value and a lower limit value. Because of this, it is possible to detect and judge defects in both large and small waveform disturbances compared to non-defective products, and it has advantages such as being able to accurately judge defective products and having a simple structure. It has a positive effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the first embodiment of the present invention, FIG. 2 is a waveform diagram explaining the waveform state of each block, t1
FIG. 43 is a circuit diagram showing a circuit example of the second embodiment. 1... DC motor, 2, 6.8... Variable resistor, 3
...Amplification circuit, 4...Noise filter, 5,7...
- Comparison circuit, 9... Defective judgment circuit, 10... Display circuit. 21!1112 Book No. 20

Claims (3)

[Claims] (1) A DC motor is operated with a predetermined voltage applied, changes in the current flowing through the DC motor are converted into changes in voltage, and based on the changes, it is determined whether the rotor of the DC motor is good or bad. In an inspection device, a voltage detection means installed in a path in series with the DC motor detects whether a change in voltage detected by the voltage detection means is between two reference values, an upper limit value and a lower limit value. A direct current motor rotor inspection device comprising: a determining means for making a determination; and a display means for displaying a determination result of the determining means. (2) The voltage detection means is a resistor connected in series to the DC motor, and the determination means includes an amplifier circuit that amplifies a change in the voltage signal generated across the resistor, and the amplifier circuit. a noise filter that removes noise from the amplified signal; first and second comparison circuits connected in parallel that compare the outputs of the noise filter with different reference voltage values;
A DC motor rotor according to claim 1, further comprising a determination circuit that outputs a pulse signal when the rotor is defective based on the output signals of the first and second comparison circuits. Inspection equipment. (3) The reference voltage value of the first comparison circuit is set to a higher voltage value than the reference voltage value of the second comparison circuit, and both reference voltage values can be set arbitrarily by variable resistors. A DC motor rotor inspection device as claimed in claim 2.