JPH07274565A - Method of detecting overload of motor - Google Patents

Abstract

PURPOSE:To detect a constant overload at all times without being subject to the effect of the magnitude of applied voltage by discriminating load as overload when pulses are not generated next before a timer interrupt time passes after the time of the preceding generation of pulses. CONSTITUTION:When an interrupt signal is generated at an earlier time than pulses are generated, a period tn+1 based on the current generation of pulses is measured at the step ST6, and a step ST7 is returned to a step ST3 while using the period tn+1 as a pre-period tn in the next cycle at the step ST7. When current pulses are not generated when the interrupt signal is generated, load fluctuation reaches an overload level, and a step ST5 proceeds to a step ST8. Accordingly, the measured period is compared with a discriminating value multiplied by a coefficient read on the basis of a pre-period measured at a time before by one step and the pre-period from prepared map data, and overload is discriminated, thus allowing the detection of overload not affected by the fluctuation of the applied voltage of a motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an overload of a motor, and more particularly, it calculates a cycle of the motor from a predetermined number of generation times of pulses generated by the rotation of the motor, and changes the cycle of the motor. The present invention relates to a motor overload detection method for determining overload.

[0002]

2. Description of the Related Art For example, some automobiles are equipped with a device for opening and closing an opening and closing body such as a power window and a sunroof by a motor. When an opening / closing operation of such an opening / closing member causes an overload on the motor due to some external factor such as freezing, it is necessary to detect the overload and stop the motor.

Conventionally, in the motor overload detection of the above-mentioned device, the motor cycle is constantly monitored, and the overload can be detected by the abnormal cycle change. The period can be calculated by measuring the generation time of a predetermined number of pulses generated with the rotation of the motor and converting it into a period for each pulse generation. For example, the cycle at the time of this detection is t _n ,
The period at the time of the next detection is t _{n + 1,} and their ratio t _n / t
By comparing _{n + 1} with a preset discrimination value k, it is possible to detect that the fluctuation of the period is too large (t _n / t _{n + 1} > = k) and discriminate the overload state.

However, according to the above-mentioned conventional method, when the motor is locked due to abnormal overload, the motor cannot rotate and the next pulse is not generated. There was a problem that could not be detected.

[0005]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the main object of the present invention is to reliably detect an overload even when the motor is locked and stopped. To provide an overload detection method.

[0006]

According to the present invention, such an object is to have map data in which a coefficient that increases as the motor cycle becomes longer is linearly approximated at arbitrary cycle intervals. Then, the process of calculating the cycle of the motor based on the pulse continuously generated with the rotation of the motor,
Calculating the timer interrupt time by multiplying the previous cycle by the coefficient read from the map data corresponding to the previous cycle of the motor at the time of the previous occurrence of the pulse, from the time of the previous occurrence of the pulse This is achieved by providing a motor overload detection method characterized in that it is determined that an overload has occurred if the next occurrence of the pulse does not occur before the timer interrupt time has elapsed.

[0007]

In the DC motor, the relationship between the rotation speed N and the output shaft torque T is a straight line with a constant inclination regardless of the magnitude of the voltage applied to the motor on the graph with the horizontal axis and the vertical axis. It is a characteristic that can be expressed (see FIG. 5). As shown in FIG. 5, when the load increases by ΔT due to overload, the rotation speed decreases by a constant rotation speed ΔN regardless of the voltage. Therefore, the increase in load can be determined using the rotation speed difference ΔN. . That is, if the current rotation speed N _{n + 1} decreases by ΔN or more from the previous rotation speed N _n , the torque increase corresponding to the rotation speed difference ΔN occurs, and the overload level is reached. The rotational speed difference ΔN corresponding to the torque increase is set, and the present rotational speed N _{n + 1} is equal to or more than the value obtained by subtracting the rotational speed difference ΔN from the previous rotational speed N _n (N _{n + 1} > = N _n − If it is ΔN), it is normal, and if it is outside the normal range, it can be determined that overload has occurred.

The equation using the difference in the number of revolutions is calculated by using the cycle t (mse
When expressed using c), t _{n + 1} > = 60000t _n / (60000−ΔN × t _n ) ... Equation (1) If the above equation is linearly approximated for each period range,

[0009] a _{t n + 1> = k m} × t n. The coefficient k _{m in the} above equation is stored in advance as map data for each arbitrary cycle range, and is read from the map data according to the measured cycle, whereby overload can be determined depending on the cycle.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 shows a main part of a control circuit of a vehicle power window to which the present invention is applied. In FIG. 1, in a controller 1 of a power window control circuit, a forward / reverse drive circuit 3 of a motor 2 for opening / closing a window glass as an opening / closing body (not shown), a manual open switch 4 and an automatic open switch 5 are provided. A CPU 8 is provided as a control means for appropriately operating the drive circuit 3 in accordance with the operation of each switch of the manual close switch 6 and the automatic close switch 7. Further, in the controller 1, a positive voltage supplied from an on-vehicle battery (not shown) is supplied to the CPU 8 and the drive circuit 3 via each power supply terminal V.

Each of the switches 4 to 7 is a normally open contact,
One end of the manual open switch 4 is grounded and the other end is connected to the input terminal I2 of the CPU 8, and
Input terminal I of CPU 8 via automatic open switch 5
Connected to 1. The automatic open switch 5 and the terminal I1 and the manual open switch 4 and the terminal I2 are connected to the power supply terminal V via the resistors R1 and R2, respectively. The manual close switch 6 and the automatic close switch 7 and the resistors R4 and R3 connected to the power supply terminal V are connected to the input terminals I4 and I3 of the CPU 8 in the same configuration as described above.

The manual open switch 4 is adapted to be operated in an interlocking manner when the automatic open switch 5 is operated. When the manual open switch 4 is operated, a low level signal is input only to the input terminal I2. Entered,
When the automatic open switch 5 is operated, a low level signal is input to both input terminals I1 and I2. In this way, the operating states of the switches 4 and 5 can be determined. The same applies to the signal input state to both input terminals I3 and I4 in the case of each of the close switches 6 and 7.

The normal drive output terminal O1 of the CPU 8 is connected to one end of the solenoid of the relay RL1 via the amplifier AP1, and the other end of the solenoid is connected to the power supply terminal V. The normally open terminal of the contact of the relay RL1 is connected to the power supply terminal V, the normally closed terminal thereof is grounded, and the common terminal thereof is connected to one end of the motor 2. The reverse rotation drive terminal O2 of the CPU 8 is connected to the amplifier AP2 and the relay RL2 configured in the same manner as above, and the common terminal of the relay RL2 is connected to the other end of the motor 2.

The motor 2 has, for example, a pair of Hall elements 9a and 9b for generating a pulse wave in synchronization with its rotation.
Is provided. As shown in FIG. 2, these Hall elements 9a and 9b generate pulse waves with a predetermined rotation angle difference and a predetermined width as the motor 2 rotates, and input them to the frequency dividing circuit 10. There is. From the frequency dividing circuit 10, pulse waves are generated at the rising and falling edges of the pulse waves from the Hall elements 9a and 9b, and are input to the input terminal I5 of the CPU 8. The period of the motor 2 can be measured by measuring, for example, a predetermined number of generation times of pulse waves from the frequency dividing circuit 10. By counting the waves of this pulse, it is possible to know where the position of the window glass is.

Next, the operation routine in the CPU 8 will be described below with reference to the flow chart of FIG. 3 showing the closing operation. First, in step ST1, the rising signal of the rotation pulse generated with the rotation of the motor 2 is read, and in the next step ST2, the cycle t _n as the previous cycle of the motor 2 is measured. In step ST3, in order to obtain a discrimination value for discriminating overload, a coefficient corresponding to the measured cycle t _n is read out from the coefficients k _m stored in the memory of the CPU 8 in advance as map data.

A method of setting the above coefficient k _{m will be} described with reference to FIG. In FIG. 4, the horizontal axis represents the previous cycle (t _n ), and the vertical axis represents the current prediction cycle (t _{n + 1} ). In consideration of shortening the processing time, t _{n + 1} = k × t _{n is applied} to the above equation (1).
When expressed by / (k-t _n ), the curve is represented by an imaginary line in the figure. Actually, it is used in the smooth range of the curve. The coefficient k _{m of} the linear approximation formula t _{n + 1} = k _m × t _n
Is

Since k _m = k / (k−t _n ) Equation (2), the linear approximation equation is

T _{n + 1} = [k / (k−t _m )] × t _n Equation (3) can be converted. Here, t _m is a delimiter of the cycle range and can be appropriately determined by design, and in the figure,
It is represented by t _m = t ₁ , t ₂ , t ₃ , .... T _m = t ₁ set them in advance, t _2, t _3, ... to each cycle range with separators, seeking coefficients k _m, based on the equation (2), may be linear approximation for each of the periods range you create a map data that defines the coefficient k _m. In the map data created on the basis of FIG. 4, for example, in the during period until t ₁ and the coefficient k _m and k _1, t ₁ ~t is located between the _second coefficient k _m a k ₂
And then, as k ₃ coefficient k _m In the between t ₂ ~t _3, fitted to a linear approximation, used to overload discriminant.

[0020] After reading the coefficient k _m at step ST3, the step ST4, sets the timer interrupt signal having a timer interrupt time ti multiplied by the period t _n to the coefficient k _m. Then, in step ST5, the interrupt signal generation timing after the timer interrupt time ti has elapsed after the previous pulse generation is compared with the next pulse generation timing. That is, when the pulse generation is earlier than the interrupt signal generation, the load fluctuation is small and within the allowable range. In that case, in step ST6, the cycle t _n based on the current pulse generation is generated. ₊₁ is measured, and the cycle t _{n + 1} is set as the previous cycle t _{n in the} next cycle in step ST7, and the process returns to step ST3.

If the current pulse is not generated when the interrupt signal is generated, it means that the load fluctuation has reached the overload level. In that case, the process proceeds to step ST8.
In step ST7, it is preferable to stop the motor 2, but for example, it is possible that something is pinched due to the occurrence of overload when the opening / closing body is closed. In that case, the motor 2 is rotated in reverse to open the opening / closing body. You can

In this way, the measured cycle is compared with the previous cycle measured immediately before (for example, one pulse before) and the discriminant value obtained by multiplying the coefficient read based on the previous cycle from previously created map data. Then, the overload is determined. As described above, even when the motor applied voltage (battery voltage in this embodiment) changes, the rate of change between the rotation speed and the shaft torque is constant, so that the change in the rotation speed corresponding to the load increase is changed in the cycle. map as represented, represents represents expression in the period by the multiplier k _m × t _n of the cycle change amount Δt coefficients and the previous period by linear approximation for every arbitrary cycle range, the coefficient k _m for each cycle range It is set as data to determine overload, and it is possible to determine overload that is not affected by voltage fluctuations.
Further, even when the motor 2 is stopped due to overload and the next pulse is not generated, the overload can be determined after the timer interrupt time has expired, and therefore the overload can always be determined. The above process counts the pulse wave and determines whether something is pinched by the closing action of the window glass when the window glass is not near the fully open position.However, when the window glass is near the fully open position, Step S
By increasing the constant B of T3 by a predetermined amount with respect to the previous processing, it is possible to ensure the full opening of the window glass.

[0023]

As described above, according to the present invention, when the discriminant equation of the torque change is converted into an equation using a cycle, it becomes non-linear. However, the coefficient for linearly approximating the equation for each cycle range is set. Since it is set as map data and the coefficient is read according to the measurement cycle and the judgment is made by the linear approximation formula, overload judgment can be performed by the cycle measurement, so conversion to the number of revolutions is not required. Therefore, the calculation process can be simplified and the overload can be detected without being affected by the fluctuation of the voltage applied to the motor.

[Brief description of drawings]

FIG. 1 is a control circuit diagram of a main part of an automobile power window to which the present invention is applied.

FIG. 2 is an explanatory diagram showing a measuring procedure of a pulse wave accompanying rotation of a motor.

FIG. 3 is a motor overload detection flow chart to which the present invention is applied.

FIG. 4 is a diagram for explaining a linear approximation formula when performing overload determination based on a cycle.

FIG. 5 is a diagram showing a relationship between a motor rotation speed and torque.

[Explanation of symbols]

 1 Controller 2 Motor 3 Drive Circuit 4 Manual Open Switch 5 Automatic Open Switch 6 Manual Close Switch 7 Automatic Close Switch 8 CPU 9a / 9b Hall Element 10 Frequency Divider

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location H02P 7/06 K (72) Inventor Katsuya Shigematsu 1-2681 Hirosawa-cho, Kiryu-shi, Gunma Stock Company Sansan Co., Ltd. Inside the Tsuba Electric Works (72) Inventor Masashi Shimada 1268-1, Hirosawa-cho, Kiryu-shi, Gunma Mitsuba Electric Works Co., Ltd.

Claims (1)

[Claims] 1. It has map data which is set by linearly approximating a coefficient that increases as the cycle of the motor becomes longer at every arbitrary cycle interval, and based on pulses continuously generated with the rotation of the motor. A step of calculating the cycle of the motor, and a step of calculating a timer interrupt time by multiplying the previous cycle by the coefficient read from the map data corresponding to the previous cycle of the motor at the time of the previous generation of the pulse. An overload detection method for a motor, characterized in that if there is no next occurrence of the pulse before the timer interrupt time has elapsed from the time of the previous occurrence of the pulse, an overload is determined.