JPH0477542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for inspecting commutation angle of a DC motor.

In order to improve the characteristics of a DC motor, it is necessary that the commutation angle is appropriate. For example, in a small DC motor that has a stator with a pair of permanent magnets as the field and a rotor with a three-pole configuration on the armature coil side and a pair of brushes, each armature coil The current is 2
In other words, it is ideal that the rectification is performed every time the rotor rotates by 60 degrees, provided there is no deviation in the rectification angle.

However, in reality, slight deviations in the commutating angle occur due to dimensional accuracy of motor parts, deviations in the mounting positions of permanent magnets and commutators, errors in the brush contact angle, and the like. For this reason, in the past, after the motor was completed, the current waveform of the armature coil was displayed on a synchroscope, etc., and the worker visually checked this complex waveform pattern to judge whether the commutation angle was good or not, and then depending on the results. The positions of the permanent magnets and brushes were adjusted using the machine. However, this method has disadvantages in that the waveform pattern recognition process is complicated, automation is difficult, and inspection work is inefficient.

The present invention has been proposed in view of the above points, and its purpose is to detect the current waveform of the armature coil of a DC motor in synchronization with a synchronous timing signal obtained from a rotor position detection signal by a magnetic detection element. By converting the time required for the current in each armature coil to switch, which is determined from the differential waveform of the current waveform, into the rotation angle of the rotor, and calculating the deviation of the commutation angle based on this rotation angle, it is possible to To provide a method for inspecting the rectification angle of a DC motor, which can automatically and non-contactly, extremely easily and accurately inspect the commutation angle deviation without requiring complicated waveform recognition processing work.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram for carrying out the present invention. Mainly, a small DC motor 1 is equipped with a magnetic detection element (not shown) such as a Hall element that detects the position of the rotor from its leakage magnetic flux. The output signal of this magnetic flux detection element is processed as appropriate, such as by being pulsed by the synchronization signal detection circuit 2, and the current waveform of the armature coil of the rotor is detected from the moment the rotor is at a predetermined position. The device is configured to output a synchronization timing signal at the same time. However, in response to this synchronization timing signal, the current waveform of the armature coil detected by the current waveform detection circuit 3 as shown in FIG. A pulse-like differential waveform can be obtained. In FIG. 2B, if T is one rotation period of the rotor, _T11 is the time from the synchronization timing signal is issued to the first differential waveform,
That is, it is the time until the current in one armature coil is switched to another armature coil by rectification, and T ₁₂ to _{T 16} are also the times between each differential waveform,
T ₂₁ and T ₂₂ indicate the respective times in the second period. As a result, for example, the rotation angle of the rotor corresponding to T ₁₁ becomes θ ₁ = 360°×T ₁₁ /T, and below, θ ₂ = 360°×T ₁₂ /T, etc., and in the second period.
The rotation angle of the rotor corresponding to T ₂₁ is θ ₂₁ = 360°×
T ₂₁ /T.

Therefore, by calculating the deviation Δθ between θ ₁ converted from T ₁₁ and T and the theoretical value (for example, 60°), the deviation of the rectification angle is determined by the period calculation circuit 5 at the subsequent stage of the differential processing circuit 4. The determination processing circuit 6 at the subsequent stage determines whether the deviation Δθ is within an allowable range, and displays whether the rectification angle is good or bad through an appropriate display means. Note that the above measurement is sufficient if the synchronization timing signal is accurately generated at the moment when the rotation angle of the rotor is always 0 degrees, but this may not necessarily be the case depending on the positional relationship of the rotor. In this case, the period calculation circuit 5
By determining Δθ′=θ ₂₁ −θ ₁ as follows, the deviation in the initial position of the rotor can be corrected, and more accurate detection can be performed.

As described above, according to the present invention, a magnetic detection element for detecting leakage magnetic flux is disposed close to the DC motor,
The current waveform of the armature coil of the DC motor is detected in synchronization with the synchronization timing signal obtained from the rotor position detection signal by this magnetic detection element, and the current of each armature coil is determined from the differential waveform of this current waveform. The time it takes for the rectification to change is converted to the rotation angle of the rotor, and the shift in the rectification angle is calculated based on this rotation angle, so there is no need for the complicated waveform recognition process that was required in the past. Moreover, it has the effect of allowing the deviation of the rectification angle to be inspected very easily and accurately without contact. In particular, because we do not use the armature current waveform, which is the original waveform, but instead use a steep pulse-like waveform obtained by differentiating it, the characteristics of the current waveform become even clearer, making inspection easier. There are advantages that can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for implementing the present invention;
FIG. 2 is an explanatory diagram of the operation, in which A shows the current waveform of the armature coil, and B shows the differential waveform. 1... Motor, 2... Synchronous signal detection circuit, 3...
...Current waveform detection circuit, 4... Differential processing circuit, 5...
...Period calculation circuit, 6...Judgment processing circuit.

Claims (1)

[Claims] 1. A magnetic detection element for detecting leakage magnetic flux is arranged close to the DC motor, and the current waveform of the armature coil of the DC motor is synchronized with a synchronization timing signal obtained from a rotor position detection signal by this magnetic detection element. is detected, the time required for the current in each armature coil to switch, which is determined from the differential waveform of this current waveform, is converted to the rotation angle of the rotor, and the deviation in the commutation angle is calculated based on this rotation angle. A method for inspecting the rectification angle of a DC motor.