JPH0454887A - Rotational speed monitor for motor - Google Patents

Abstract

PURPOSE:To prevent malfunctions by not renewing a reference rotation speed, when a detected value of the rotational speed of a motor changes largely exceeding values in a stationary state because of a noise etc. CONSTITUTION:A maximum limit frequency Fmax and a frequency Fn are compared, and if the frequency Fn increases largely exceeding Fmax because of the mixture of high-frequency components by a noise, etc., with a detected rotational speed signal, while the motor 1 is rotating at an approximately constant speed in a usual condition, the frequency Fn at that time is rejected to read. In other words, performing control of not proceeding to the next step by judging that noises have entered, prevents malfunctions of rewriting reference frequencies Fsd by largely changed values by the noises. Incidentally, the rotational speed of the motor 1 is monitored by the frequency here, but a reference period can be used and the number of rotations can be monitored instead.

Description

[Detailed Description of the Invention] [Object of the Invention] <Industrial Application Field> The present invention relates to a motor rotation speed monitoring device, and particularly to a device for stably controlling the drive of a motor by preventing malfunctions caused by noise. The present invention relates to a motor rotation speed monitoring device.

<Prior Art> Conventionally, in a driving device for an opening/closing body such as a so-called sunroof or a power window installed in an automobile, it is necessary to close the opening/closing body with a sufficient pressing force when in the closed state. Therefore, when the opening/closing body reaches the fully closed position, the load on the motor increases, so the motor is stopped when the load increases beyond a predetermined value. To detect an increase in load, the rotational speed of the motor of the drive device is constantly monitored, and since the rotational speed is approximately constant while the opening/closing body is moving, the rotational speed is calculated based on the constant rotational speed. Some systems determine that the load has increased when the rotational speed falls below a predetermined lower limit.

By the way, if the viscosity of the grease attached to the drive mechanism changes due to temperature changes, the mechanical resistance will fluctuate, so the steady rotation speed will increase or decrease depending on the operating atmosphere.
For example, the standard rotational speed is updated every time a new maximum rotational speed is detected, so that fluctuations in mechanical resistance can be dealt with, and the lower limit value of the motor stop level can be calculated according to the operating atmosphere. . However, since the reference rotation speed is updated with the latest maximum rotation speed, if a high frequency component is included in the rotation speed detection signal due to noise etc. and a value higher than the actual value is read as the rotation speed, The reference rotation speed shifts to the higher side. Therefore,
If the motor stop level has also increased by 1 and the normal rotation speed is lower than the motor stop level that has been revised upward when the influence of noise disappears and the normal rotation speed is read, , there is a risk that the motor may be stopped at that time because it is mistakenly determined that the load has increased.

The above problem can be solved by adding a filter circuit to slow down the rotational speed detection signal, but there are problems such as an increase in the number of parts.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main purpose of the present invention is to solve the problem when the detected value of the rotational speed of the motor changes more than the normal value due to noise etc. An object of the present invention is to provide a motor rotation speed monitoring device that is improved in order to perform stable motor drive control by preventing malfunctions such as erroneously stopping the motor when the motor returns to a normal value.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, the present invention provides a drive circuit for driving a motor, and a rotation speed detection means for detecting the rotation speed of the motor. While sequentially monitoring the rotational speed, the latest maximum rotational speed is updated as the reference rotational speed, and if the rotational speed falls below a lower limit value calculated as a predetermined amount lower than the reference rotational speed, and control means for stopping the motor, wherein the control means does not update the reference rotation speed when the rotation speed exceeds a predetermined upper limit value. This is accomplished by providing a device.

<Operation> By doing this, if the detected value of the motor rotation speed changes more than the steady state value due to noise etc.,
Since the reference rotational speed is not updated, an accurate motor stop level can always be set using the reference rotational speed that is not affected by noise, and the motor can be stably controlled to stop.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram schematically showing a motor drive control circuit to which the present invention is applied. This motor drive control circuit is
For example, it may be used for sunroofs, power windows, etc. installed in automobiles, and as shown in FIG. The motor 1 includes a control circuit 2 having a drive circuit and a circuit for controlling the stoppage of the drive circuit, and a rotation detector 3 formed of, for example, a pulse generator as a rotation speed detection means of the motor 1. The motor 1 is controlled by a control circuit 2 so as to be rotated by a drive signal from an operation switch (not shown) and stopped by a switch operation or a stop signal described later.

FIG. 2 is a flowchart showing part of the program control performed by the control circuit 2. As shown in FIG. When the drive signal from the aforementioned operation switch is input manually, the drive signal is output from the control circuit 2 and the motor 1 begins to rotate in step ST1. Then, the pulse signal from the rotation detector 3 is input to the control circuit 2, and the rotation speed of the motor 1 is converted into a frequency using a clock built in the control circuit 2, and the initial frequency immediately after driving is determined in step ST2. Read the frequency as Fl. In the next step ST3, the initial frequency F1 is read as the reference frequency Fsd corresponding to the reference rotation speed, and in step ST4, a new frequency Fn is read. Then, in step ST5, the frequency F is compared with the maximum limit frequency Fmax as a predetermined limit rotation speed set in advance.
If n is smaller than the maximum limit frequency Frnax (determined to be within the normal rotational speed range), the process proceeds to step ST6.

In step ST6, if the ratio of the frequency Fn to the reference frequency Fsd is lower than the reference value (for example, 80%), the load on the motor 1 has increased due to the opening/closing body reaching the stop position or a foreign object etc. After determining that, the process proceeds to step ST7, and the motor 1 is stopped. By the way, if the steering knob ST6 determines that the frequency Fn does not drop significantly with respect to the reference frequency Fsd, that is, it is a steady load state, the process proceeds to step ST8.

In step ST8, the magnitude of the frequency Fn is compared with the reference frequency Fsd, and if a value larger than the reference frequency Fsd, that is, the maximum frequency read up to that point, is newly read, the process advances to step knob ST9, and in step ST9 , the frequency Fn with a larger value than before is rewritten as the new reference frequency Fsd, and the process returns to step ST4. Further, in step ST8, if the frequency Fn does not exceed the reference frequency Fsd, the process returns to step ST4 without rewriting the reference frequency Fsd. In this way,
Steps ST4 to ST9 are repeated until the process advances to step ST7 and the motor 1 is stopped.

By the way, in step ST5 described above, the maximum limit frequency Fmax and the frequency Fn are compared, and as shown in FIG. If a high frequency component due to noise etc. mixes into the rotation speed detection signal and the frequency Fn increases significantly beyond Fmax (the part indicated by arrow A in the figure), the frequency Fn at that time will not be read. In order to do this, a flow returning to step ST4 is programmed.

If step ST5 is not provided, if the frequency Fn changes significantly due to noise, the process passes through steps ST6 and ST8 and proceeds to step ST9, where the reference frequency Fsd is rewritten to a large value. Then, the stop level is set high based on that large value, so
According to the present invention, if the normal frequency Fn falls below the increased stop level when the noise disappears, it is incorrectly determined in step ST6 that an overload has been reached, that is, the stop position has been reached. For example, the frequency Fn is the maximum limit frequency Fmax
If it exceeds this, it means that slipping occurs between the opening/closing body and the transmission mechanism, which cannot occur due to the mechanism under normal driving conditions, and it is judged as noise in step ST5 and the process does not proceed to the next step ST6. This control prevents malfunctions in which the reference frequency Fsd is rewritten with a value that has changed significantly due to noise.

In this embodiment, the rotational speed of the motor 1 is monitored using the frequency, but it goes without saying that the period may be used as a reference or the rotational speed may be monitored.

[Effects of the Invention] As described above, according to the present invention, in order to prevent the change value from being updated as the reference rotation speed when the rotation speed changes greatly due to noise etc., the increase in motor load is replaced by a decrease in rotation speed. In the control that stops the motor based on the judgment, the reference rotation speed is not affected by noise, preventing malfunctions, and improves noise resistance without increasing the number of parts such as installing a filter circuit. obtain.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram schematically showing a motor drive circuit to which the present invention is applied. FIG. 2 is a flowchart according to the present invention. FIG. 3 is a diagram showing one example of a change in frequency corresponding to the rotational speed of the motor. 1... Motor 2... Control circuit 3... Rotation detector Patent applicant Yo Oshima, patent attorney representing Mitsuba Electric Co., Ltd. (1 other person) Figure 1 Figure 3 Figure 2 figure

Claims (1)

[Claims] a drive circuit for driving the motor; a rotation speed detection means for detecting the rotation speed of the motor; and a rotation speed detecting means for detecting the rotation speed of the motor; control means for stopping the motor when the rotation speed falls below a lower limit value calculated as a predetermined amount lower than a reference rotation speed; A motor rotation speed monitoring device characterized in that the reference rotation speed is not updated when the reference rotation speed exceeds a value.