JP2872400B2 - Motor overload protection method and motor control device - Google Patents

Description

The present invention relates to a motor overload protection method and a motor control device for detecting an overload state of a motor, controlling driving of the motor, and protecting the motor and the like. About.

[Conventional technology]

For example, in an automobile or the like, a configuration in which a movable member is moved by drive control of a motor provided in a mechanism or the like, such as a power seat, a power window, and various power-type mirrors, is widely known. In such a configuration, the drive of the motor is controlled by, for example, a motor control device including a microcomputer.

When such a motor is overloaded due to a mechanical lock or the like when the movable member is moved, an overcurrent flows through the motor, which may overheat and damage the motor, thereby lowering safety. Therefore, in a motor control device that controls such a motor, various methods are used.
By detecting the overload state of the motor and immediately shutting off the supply voltage to the motor, the motor is protected from an overcurrent caused by the overload, and the safety of the motor and the mechanism is ensured.

As a method of detecting such an overload state of the motor, for example, a method of determining the overload state of the motor from an overcurrent flowing through the motor (overcurrent detection method), and a method of detecting the number of rotations of the motor due to an increase in torque. There is known a method of detecting an overload state of a motor from a decrease (a method of detecting the number of rotations) and the like.

For example, the overcurrent detection method detects a terminal voltage of an overcurrent detection resistor connected in series to a motor, and detects an overload state of the motor from an increase in the voltage value of the detection resistor terminal.

On the other hand, the rotation number detection method monitors the generation cycle of the pulse accompanying the rotation of the motor, and detects the overload state of the motor based on the fluctuation of the generation cycle of the pulse. In such a rotation speed detection method, a pulse from a rotation sensor forming a position detection unit of the movable member is usually used.

[Problems to be solved by the invention]

However, in the overcurrent detection method, for example, the supply voltage from the vehicle battery or the like is applied to the motor after being consumed by the overcurrent detection resistor. , There is a possibility that characteristics such as rotation speed and torque may not be sufficiently obtained.

Further, the current flowing through the motor (motor current) is easily affected by the operating temperature condition, and the motor current fluctuates due to the rise and fall of the ambient temperature. In other words, since the terminal voltage of the overcurrent detection resistor fluctuates due to the fluctuation of the motor current due to the change of the operating temperature condition, the range of the operating torque of the motor is the minimum value of the fluctuation range of the motor current when the motor is overloaded. Or less. for that reason,
The area of use of the motor is reduced, and in this regard, the characteristics of the motor cannot be used effectively.

On the other hand, in the rotation speed detection method, the rotation speed of the motor is monitored from the pulse generation period, and the overload state may be detected from the reduction in the rotation speed. The rated motor characteristics can be obtained.
Also, it has good compatibility with microcomputer systems and is widely used in motor control devices equipped with microcomputers.

By the way, in a car or the like, usually, a battery of the car is used as a power source of the motor, but a supply voltage (motor voltage) Eb from the battery is not kept constant.
As shown by Eb1 to Eb4 in FIG. 5, it fluctuates according to the running condition of the automobile. Generally, the fluctuation range of the motor voltage is 9 to
The voltage is set to about 16 V, and the motor is driven within this fluctuation range.

Here, since the motor torque is proportional to the voltage of the motor, as shown in FIG. 5, the motor torque differs depending on the motor voltage even at the same rotation speed No. The size of is T1
As indicated by T4, the values greatly differ depending on the motor voltages Eb1 to Eb4. That is, when the motor is driven under the maximum motor voltage Eb4, for example, when the motor is restrained and the number of rotations of the motor becomes equal to or less than the set value No, the torque in the motor Eb4 becomes excessively large. For this reason, a mechanical part or the like to which the motor is attached is required to have strength enough to withstand excessive torque in a restrained state of the motor or the like. Therefore, there is a possibility that the size and weight of the mechanism and the like are increased, the configuration thereof is complicated, and the design work and the assembling process are complicated.

Particularly, in a configuration in which the movable member is forcibly stopped at the movement limit position of the movable member and the movement range of the movable member is determined by detecting the overload state of the motor, a high strength is provided to the stopper means for the movable member. Because of the demands, it is inevitable that the entire apparatus becomes larger, heavier, and complicated.

An object of the present invention is to provide a motor overload protection method and a motor control device that can detect an overload state of a motor without applying excessive torque to the motor.

[Means for solving the problem]

In order to achieve this object, according to the motor overload protection method of the present invention, a motor voltage converted into a pulse having a width corresponding to a voltage value is compared with a pulse output as the motor rotates. It is noted that if only the coincident pulse is detected as an overload detection signal by processing, the number of pulses is constant regardless of the motor voltage. Then, the number of pulses of the overload detection signal is counted, the overload detection signal is compared with a preset set value, and when the number of pulses of the overload detection signal becomes equal to or less than the set value,
It is determined that the motor is overloaded.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

A motor control device 10 for a motor overload protection method according to the present invention includes a rotation sensor 12 provided in a motor M, and a central processing unit 14, as shown in FIGS. The motor can be controlled by operating the switch means 16.

A DC geared motor is usually used as the motor M. The motor is a movable member such as a seating posture control device and various mirrors. For example, in a seat slide device 18 as shown in FIG. Is provided as a drive source for moving in the front-rear direction.

For example, as shown in FIG. 1, the rotation sensor 12 includes a disk-shaped permanent magnet 22 fixed to an output shaft (not shown) of the motor M, and a reed switch provided adjacent to the side of the permanent magnet. 24. In such a configuration, the permanent magnet 22 rotates integrally with the output shaft of the motor M, and the contact of the reed switch is opened and closed by the polarity of the permanent magnet passing by the side of the reed switch 24, and the contact is closed. A pulse is generated.

As shown in FIG. 1, the reed switch of the rotation sensor 12
24 is connected to, for example, the central processing unit 14, and is configured to output a pulse generated by driving the motor M to the central processing unit. And, for example,
In the central processing unit 14, the position of the sheet (movable member) 20 can be detected by monitoring the pulses from the rotation sensor 12 and counting the number of pulses by adding or subtracting the number of pulses. It is used as position detection means.

The motor M is driven, for example, by operating the switch means 16. As shown in FIG. 1 and FIG. 2, the switch means 16 is formed, for example, with a manual switch 26, and can be operated by a seated person (driver), for example, a seat cushion 28 of the driver seat 20. It is provided on the side and the like.

As shown in FIG. 1, as the manual switch 26,
For example, an automatic return type seesaw switch having a neutral position and two-position contacts, which can switch the rotation direction of the motor M depending on the operation direction, can be used. The manual switch 26 is connected to the central processing unit 14.

The central processing unit 14 is formed to include a microcomputer (microcomputer) 30, and the microcomputer is configured to process an input according to a stored program and generate an appropriate control signal. The control signal is output to, for example, a relay driver 32 as can be seen from FIG. Then, the relay driver 32 determines that the motor control relay RL
The drive of the motor is controlled by energizing a corresponding one of the relays 1 and RL2 and switching the relay contacts RL1a and R12a corresponding to each relay.

For example, when the manual switch 26 is operated in an arbitrary direction, a corresponding signal is output to the central processing unit 14, and the driving of the motor M is controlled to move the seat 20 in the front-rear direction, and the occupant (driver) The position can be set arbitrarily according to the taste and body shape of the user.

Further, for example, a memory switch 34 is provided in the switch means 16 so that the position of the seat 20 can be stored and reproduced from the rotation number of the motor M driven by the operation of the manual switch 26, that is, the pulse count number. I have. As shown in FIG. 1, the memory switch 34 includes, for example, a set switch 36 and a reproduction switch 38. As the set switch 36 and the reproduction switch 38, for example, an automatic reset type push-type switch can be used, and each switch is connected to the central processing unit 14. As shown in FIG. 2, the memory switch 34 is provided on the side of the seat cushion 28, for example, like the manual switch 26.

For example, when the set switch 36 of the memory switch is operated at an arbitrary position of the seat 20, a predetermined signal is output to the central processing unit 14. Then, for example, the number of rotations of the motor M required to move from the reference point to an arbitrary position, that is, the number of pulses from the rotation sensor 12 is stored in the memory of the central processing unit 14 as the memory position of the sheet 20.

Further, for example, when the reproduction switch 38 of the memory switch is operated when the seat 20 is in a position other than the memory position, the central processing unit 14 first recognizes the current position of the sheet based on the pulse count of the rotation sensor 12. I do. Then, the count number (measured value) at the current position of the seat 20 is compared with the count number (stored value) stored at the memory position, and the motor M is driven until the measured value and the stored value match, and Is returned to the memory position.

As can be seen from FIG. 1, the motor M, the central processing unit 14 and the relay driver 32 are connected to, for example, a battery 40 of an automobile, and are driven by a supply voltage from the battery. Usually, the central processing unit 14
It is connected to a battery 40 via a stabilized power supply 42.

Here, according to the present invention, the motor voltage Eb is converted into a pulse having a width corresponding to the voltage value, and a pulse corresponding to the motor voltage is compared with a pulse output with the rotation of the motor to perform a process. An overload state of the motor is detected by outputting a load detection signal and monitoring the overload detection signal.

As shown in FIGS. 1 and 2, in the motor control device 10 of the present invention, for example, a triangular wave generating circuit 44 and an operational amplifier (op-amp) 46 are provided. As the operational amplifier 46, for example, a comparator that compares two input signals and outputs a high-level signal (pulse) when one of the reference voltage values exceeds the other voltage value can be used. Then, for example, the motor voltage Eb extracted by the wiring 48 is connected to a comparator (operational amplifier) 46 together with the triangular wave generation circuit 44.

As can be seen from FIG. 3, in such a configuration, when the motor voltage Eb becomes the reference value in the comparator 46 and the voltage value of the triangular wave becomes equal to or higher than the motor voltage Eb, the pulse of the corresponding width is output from the comparator. Is output. At this time, the output pulse from the comparator 46 is different from the motor voltage in inverse proportion to the level of the motor voltage Eb, as can be clearly understood by comparing, for example, (a), (b) and (c) in FIG. Converted to the corresponding width.

As shown in FIG. 1 and FIG. 2, the comparator 46 is connected to the gate circuit 50 together with the reed switch 24 of the rotation sensor, and the output pulse from the comparator and the output pulse from the rotation sensor 12 are compared by the gate circuit. It is processed. The gate circuit 50 is formed, for example, as an AMD gate, and is configured to output only a pulse at a location that matches the output pulse from the comparator 46, as shown in FIG. The gate circuit 50 includes the central processing unit 14
And an output pulse from the gate circuit is output to the central processing unit 14 as an overload detection signal. Then, the number of pulses output from the gate circuit 50 as the overload detection signal is counted in the central processing unit 14, for example, and compared with a preset value.

In such a configuration, for example, when the motor M enters a constrained state or the like and the number of rotations of the motor decreases, the generation cycle of the output pulse from the rotation sensor 12 increases, and the number of generations of the pulse decreases. Then, with this, the number of pulses (overload detection signal) from gate circuit 50 decreases. Therefore, according to the present invention, when the number of pulses of the overload detection signal becomes equal to or less than the design value, it is determined that the motor M is in an overload state, and the supply voltage to the motor is immediately cut off. .

According to such a configuration, the supply voltage is stopped in response to the occurrence of the overload state, so that the motor is sufficiently protected against an overcurrent generated when the motor M is overloaded.

Here, as can be clearly seen from FIGS. 3A, 3B, and 3C, the overload detection signal compared by the gate circuit 50 is independent of the level of the motor voltage Eb. A certain number of pulses are output. That is, according to such a configuration, as shown in FIG.
At a constant torque To without being affected by the fluctuation of the rotation speed N of the motor M proportional to the level (Eb1 to Eb4)
An overload condition of the motor is determined.

Therefore, the magnitude of the torque generated when the motor M is overloaded can be specified, and no excessive load acts on the motor and the mechanism, so that the mechanism has sufficient strength to withstand a predetermined torque. Is enough. Accordingly, the reinforcement of the mechanism and the like can be sufficiently suppressed, and the size and weight of the mechanism and the like can be prevented, and the configuration is not complicated.

And, since excessive torque does not act on the motor M,
The configuration of the motor can be simplified, and the size of the motor itself can be sufficiently reduced.

Further, when the motor M is constrained and the number of revolutions decreases, the motor is immediately stopped by judging the overload state. Therefore, the overcurrent generated at the time of overload does not flow for a long time to the motor M in the constrained state, and adverse effects on the life of the motor and the relay contacts RL1a and RL2a can be prevented.

Further, by detecting the overload state of the motor M,
In the configuration for detecting the movement limit position of the movable member such as 20 or the like, the motor stops immediately due to a decrease in the number of revolutions of the motor when the movement limit position is reached. Does not act on Therefore, since the load from the sheet 20 acting on the stopper and the like can be specified, reinforcement of the stopper and the like can be suppressed, and the size of the stopper, that is, the size of the entire apparatus can be reduced.

Then, the specification of the motor torque simplifies the configuration of the motor and the mechanism section, so that the design work and the assembly work are simplified, and the workability is improved.

Further, according to the method of detecting an overload state of the motor based on a decrease in the number of revolutions of the motor M due to an increase in torque as in the present invention, the supply voltage is not consumed by an overcurrent detection resistor or the like. The use efficiency of the motor is improved, and the motor characteristics almost as rated can be obtained.

Further, since the overload state of the motor M is detected by specifying the motor torque, the motor M is hardly affected by the ambient temperature, and the motor torque up to a predetermined set value can be used to the maximum. Therefore, also in this respect, the characteristics of the motor M can be sufficiently utilized.

According to the motor control device 10 of the present invention, the above-described overload protection method can be appropriately performed in spite of the simple configuration, and the safety of the motor M, the mechanism, and the like can be sufficiently ensured. .

Here, in the embodiment, the overload detection signal from the gate circuit 50 is compared with the set value in the central processing unit 14 to determine the overload state of the motor. However, the present invention is not limited to this. For example, a configuration in which an individual comparison circuit such as a preset counter or the like is provided between the gate circuit 50 and the central processing unit 14 and the motor M is controlled by an output from the preset counter or the like. Good.

Further, the overload state of the motor M is detected by using the rotation sensor 12 as a position detecting means capable of detecting the position of the seat 20. However, any configuration is possible as long as a pulse can be output with the rotation of the motor M. The present invention is not limited to this. For example, an overload state of the motor may be detected by a rotation sensor separate from the position detection unit. . However, if the pulse from the rotation sensor 12 forming the position detecting means is used as in the embodiment,
Multiple configurations can be prevented.

In the embodiment, the motor control device 10 for the seat slide device 18 is embodied. But,
The present invention is not limited to this. For example, the present invention may be applied to other seating posture control devices such as a reclining device and a seat lifter, a movable headrest, and a motor control device such as various mirrors of a power seat.

Further, the present invention is not limited to an automobile, and can be widely applied as a motor control device for moving a movable member.

The embodiments described above are intended to explain the present invention, and do not limit the present invention in any way. All modifications and alterations within the technical scope of the present invention are included in the present invention. Needless to say.

〔The invention's effect〕

As described above, according to the motor overload protection method according to the present invention, the motor voltage is converted into a pulse having a width corresponding to the voltage value, and the pulse corresponding to the motor voltage is output as the motor rotates. And outputs an overload detection signal. And an overload detection signal,
By comparing with a preset set value, when the number of pulses of the overload detection signal becomes equal to or less than the set value, it is determined that the motor is overloaded, and the supply voltage to the motor is immediately cut off. I have.

Therefore, irrespective of the fluctuation of the motor voltage, the torque at the time of overload of the motor becomes constant, the torque can be specified, and even in the overload state of the motor, an excessive load does not act on the motor and the mechanism, and the It is sufficient that the parts and the like have sufficient strength to withstand a predetermined torque. Accordingly, the reinforcement of the mechanism and the like can be sufficiently suppressed, and the size and weight of the mechanism and the like can be prevented, and the configuration is not complicated.

And, by specifying the motor torque at the time of overload, it is possible to simplify the configuration of the motor and the mechanical unit, etc.
Design work and assembly work are simplified, and workability is improved.

In addition, since the supply voltage is not consumed by the overcurrent detection resistor or the like, the supply voltage utilization efficiency is improved, the motor characteristics almost as rated can be obtained, and the motor torque up to a predetermined set value is determined by specifying the motor torque. Is available to the fullest. Therefore, the characteristics of the motor can be fully utilized.

According to the motor control device of the present invention, the above-described overload protection method can be appropriately performed irrespective of the simple configuration, and the safety of the motor, the mechanism, and the like can be sufficiently ensured.

[Brief description of the drawings]

FIG. 1 is a block diagram of a motor control device according to the present invention, FIG. 2 is a schematic block diagram of a motor control device, FIG. 3 is an output waveform diagram of an operational amplifier and a gate circuit, and FIG. FIG. 5 is a motor torque-rotation speed (TN) characteristic diagram in the motor overload protection method according to the invention; FIG. 5 is a motor torque-rotation speed (TN) in a known motor overload protection method; It is a characteristic diagram. 10: motor control device, 12: rotation sensor, 14: central processing unit, 16: switch means, 18: seat slide device (seating posture control device), 20: driver seat (movable member), 30:
Microcomputer (microcomputer), 44: triangular wave generation circuit, 46: operational amplifier (comparator), 50: gate circuit (AND gate).

Continuation of the front page (56) References JP-A-55-162826 (JP, A) JP-A-57-114730 (JP, A) JP-A-59-72986 (JP, A) JP-A-3-112385 (JP) JP-A-3-164024 (JP, A) JP-A-3-200440 (JP, A) JP-A-4-2530 (JP, A) Japanese Utility Model No. 56-129196 (JP, U) Japanese Utility Model Application 62-111743 (JP, U) Japanese Utility Model 1-16134 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60N 2/00-2/54 H02H 7/08-7 / 097 H02P 3/00-3/26 H02P 7/04-7/34

Claims (2)

(57) [Claims] 1. A motor voltage is converted into a pulse having a width corresponding to a voltage value, a pulse corresponding to the motor voltage is compared with a pulse generated with rotation of the motor, and only a matching pulse is detected. Output as an overload detection signal, count the number of pulses of the overload detection signal, compare the overload detection signal with a preset set value, and set the number of pulses of the overload detection signal. An overload protection method that determines that the motor is overloaded when the value falls below the value and immediately shuts off the supply voltage to the motor. 2. A motor for moving a movable member, a rotation sensor for generating a pulse according to rotation of the motor, switch means for arbitrarily driving the motor and adjusting a position of the movable member, Process the information in accordance with a predetermined program,
A central processing unit that controls the driving of the motor; a triangular wave generating circuit that generates a predetermined triangular wave; an operational amplifier that compares the motor voltage with the predetermined triangular wave and converts it into a pulse having a width corresponding to the voltage value; And a gate circuit that compares the pulse from the rotation sensor with the pulse from the rotation sensor and outputs only a coincident pulse as an overload detection signal. The gate circuit counts the number of pulses of the overload detection signal, The load detection signal is compared with a preset set value, and when the number of pulses of the overload detection signal becomes equal to or less than the set value, it is determined that the motor is overloaded, and the supply voltage to the motor is determined. Motor control device that shuts off immediately.