JP3564008B2 - Motor control circuit and control method of motor control circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor control circuit, and more particularly to a position control technique, for example, a technique that is effective when used for a motor used in an electric feed screw type actuator for raising and lowering a bed of a medical bed.
[0002]
[Prior art]
2. Description of the Related Art In a medical bed, in order to reduce the burden of eating and sleeping on a patient, the bed of the bed is automatically raised or lowered by an electric feed screw type actuator (hereinafter, referred to as an actuator).
[0003]
As a conventional actuator of this type, a shaft that is rotatably supported by being inserted into a shaft insertion portion of a housing is configured to be driven forward and reverse by a motor via a reduction gear. Some of the formed male screw portions are configured such that a female screw member to which a moving cylinder that moves in the axial direction is connected is screwed forward and backward so that the front end of the moving cylinder is connected to a load.
[0004]
When controlling the moving amount and moving speed of the bed to be raised and lowered in a medical bed using such an actuator, a rotation sensor that outputs a detection signal along with the rotation of the rotation axis of the motor is built in, and the rotation sensor is controlled by the controller. It is conceivable to employ a motor control circuit that controls the driving of the motor by counting the pulses that are output signals and calculating the moving amount and moving speed of the bed.
[0005]
[Problems to be solved by the invention]
By the way, when the above-mentioned actuator is used for a medical bed, the bed may move even after the rotation of the motor is stopped when the bed is raised or laid down. In particular, when the bed is lying down, the bed of the bed may continue to fall down for a while even after the motor is stopped due to the weight of the bed.
[0006]
Therefore, in the motor control circuit described above, in consideration of the fact that the rotating shaft of the motor continues to rotate even after the switch for raising or lowering the bed is turned off, power is always supplied to the rotation sensor. It is considered necessary to monitor the rotation of the rotating shaft of the motor. However, if the power for monitoring is continuously supplied to the rotation sensor even after the bed is stopped, the power is wasted.
[0007]
An object of the present invention is to provide a motor control circuit that can reduce standby power.
[0008]
[Means for Solving the Problems]
The motor control circuit according to the present invention is a motor control circuit including a rotation sensor that detects the rotation of the rotation shaft of the motor and outputs a signal, and a controller that counts the number of rotations based on an output signal of the rotation sensor .
The controller monitors the presence or absence of the output signal of the rotation sensor by setting a waiting time after the operation for operating the motor is stopped, and there is an output signal of the rotation sensor during the waiting time. In this case, the waiting time is set again and the presence / absence of the output signal of the rotation sensor is monitored again. If there is no output signal of the rotation sensor during the waiting time, the rotation sensor is energized after the lapse of the waiting time. Is stopped .
[0009]
According to the above-described means, when there is no detection output of the rotation sensor when the operation for driving the motor is stopped, the power supply to the rotation sensor is immediately stopped, so that standby power can be reduced. . Further, when the operation for driving the motor is stopped, if there is a detection output of the rotation sensor, the energization of the rotation sensor is stopped after a lapse of a certain time from the stop of the driving operation. Monitoring related to the rotation speed of the vehicle can be continued.
[0010]
For example, if the motor is used in an electric lead screw actuator that automatically raises and lowers the bed of a medical bed, the controller can always properly monitor the standing position of the bed of the medical bed. . On the other hand, by reducing the standby power at the rotation sensor, it is possible to contribute to energy saving as a whole medical institution such as a hospital.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0012]
In the present embodiment, the motor control circuit according to the present invention is used to control a motor incorporated in an actuator that automatically raises and lowers the bed of the medical bed, and the controller constantly monitors the undulating position of the bed. It is configured so that it can be controlled.
[0013]
As shown in FIG. 4, a housing 8 on the fixed end side of the actuator 7 is rotatably supported on the frame 2 of the bed 1 by a pivot 4, and a movable cylinder 9 on the free end side of the actuator 7. Is rotatably connected by a connecting pin 6 to a link 5 for raising and lowering the bed 3. In a state where the actuator 7 is shortened, the bed 3 of the bed 1 is horizontally laid down as shown in FIG. 4A, and when the actuator 7 is extended, the bed 3 is shown in FIG. It is to be erected as it is. A motor with a worm gear reduction device (hereinafter, referred to as a motor) 10 is incorporated in the actuator 7.
[0014]
In this embodiment, as shown in FIG. 1, a forward rotation switch 15 and a reverse rotation switch 16 are connected to an input side of a controller 17 including a microcomputer, and an output side of the controller 17 is connected to an output side of the controller 17. Is connected to a motor drive circuit 13 configured to drive the motor 10 forward and reverse.
[0015]
The motor 10 is configured as a commutator type motor, and incorporates a rotation sensor 12. The rotation sensor 12 includes a Hall element for detecting rotation of a permanent magnet provided on a rotation shaft of the motor 10, and an output terminal of the rotation sensor 12 is connected to a controller 17. The controller 17 can measure the number of rotations of the motor 10 by counting the pulses which are the output signals of the rotation sensor 12.
[0016]
Power is supplied to the rotation sensor 12 from the battery 14 via the transistor 11, and a current is supplied to the rotation sensor 12 only when the transistor 11 is in a conductive state by an output signal to the transistor 11 of the controller 17. Outputs a rotation pulse to the controller 17. The controller 17 adds the pulse output from the rotation sensor 12 when the motor 10 rotates forward and subtracts the pulse output from the rotation sensor 12 when rotating the motor 10 to thereby drive the bed 3 of the bed 1 driven by the motor 10, for example. Is determined.
[0017]
Next, the operation of the motor control circuit will be described with reference to FIGS.
[0018]
When the forward rotation switch 15 is turned on by the operator to raise the bed 3 of the bed 1, a positive rotation drive signal is output from the controller 17 to the motor drive circuit 13, and the motor 10 is rotated forward by the motor drive circuit 13. As a result, the bed 3 is raised as shown in FIG. When the operator removes his / her hand from the forward rotation switch 15 and turns off the forward rotation switch 15, the forward rotation drive signal from the controller 17 is stopped, and the supply of power to the motor 10 of the motor drive circuit 13 is stopped. As a result, the motor 10 stops.
[0019]
On the other hand, when the forward rotation switch 15 is turned on, an ON signal is output from the controller 17 to the transistor 11, and the transistor 11 is turned on, so that power is supplied to the rotation sensor 12. In this state, when the motor 10 rotates forward by turning on the forward rotation switch 15, a pulse as an output signal is output from the rotation sensor 12, as shown in FIG. 3B. The standing position of the bed 3 is recognized by the controller 17 adding this pulse.
[0020]
Then, when the forward rotation switch 15 is turned off, the controller 17 stops the forward rotation drive signal of the motor 10 to stop the forward rotation operation, and stops the motor 10 as shown in FIG. Then, in step S1, it is recognized that the operation is completed, and the process proceeds to step S2.
[0021]
In step S2, the controller 17 determines "whether the waiting time t has elapsed". That is, as shown in FIG. 3C, the controller 17 counts the waiting time t after the operation of the motor 10 ends, and if it is determined that the waiting time t has elapsed (YES), the process proceeds to step S5. If the waiting time t has not elapsed (NO), the flow proceeds to step S3.
[0022]
In step S3, the controller 17 determines whether there is a detection signal of the rotation sensor during the waiting time t. If there is no detection signal from the rotation sensor 12 (NO), the process returns to step S2, and the waiting time t is counted. If the detection signal is input from the rotation sensor 12 during the waiting time t (YES), the controller 17 proceeds to step S4.
[0023]
In step S4, the controller 17 resets the waiting time t in order to recount the waiting time t because the detection signal of the rotation sensor 12 has been received during the waiting time t. Thereafter, the controller 17 returns to Step S2. That is, as long as the detection signal of the rotation sensor 12 is present, the controller 17 executes the rotation detection of the rotation shaft by the rotation sensor 12 and continuously monitors the state of the motor 10. That is, the controller 17 maintains the ON state of the transistor 11 to supply power to the Hall element of the rotation sensor 12.
[0024]
On the other hand, if it is determined in step S2 that the waiting time t has elapsed (YES), the controller 17 proceeds to step 5 and as shown in FIG. The power supply to the Hall element is immediately stopped. That is, the controller 17 turns off the transistor 11 to stop the power to the Hall element of the rotation sensor 12, thereby reducing standby power and power consumption.
[0025]
By the way, if a large load is applied to the rotating shaft of the motor 10 that has risen or fell down on the bed 3 of the medical bed 1 immediately after the stop of the supply of the driving power and the rotating shaft continues to rotate, the rotation sensor 12 becomes positive. The detection signal is input to the controller 17 even after the rotation switch 15 is turned off. That is, in such a case, the controller 17 repeats the closed loop of steps S2, S3, and S4 described above.
[0026]
That is, the controller 17 can recognize the rotation of the rotating shaft after the power supply is stopped by repeating the closed loop of steps S2, S3, and S4, and thus can accurately recognize the position of the bed of the bed.
[0027]
In the present embodiment, the controller 17 can recognize the rotation speed (including the rotation angle) of the rotating shaft after the power supply is stopped by counting the number of times the closed loop of steps S2, S3, and S4 is repeated. An error between the distance from the standing position of the bed 3 from the standing position, that is, an error between the recognized position based on the pulse counting until the forward rotation switch 15 is turned off and the moving distance therefrom can be obtained and corrected.
[0028]
The operation in the case of the forward rotation of the motor 10 that raises the bed 3 has been described above, but the same operation is performed in the case of the reverse rotation of the motor 10 that tilts the bed 3.
[0029]
According to the embodiment, the following effects can be obtained.
[0030]
1) By immediately stopping the supply of the bias power to the Hall element of the rotation sensor, it is possible to reduce the power consumption of the motor used for the actuator for raising and lowering the bed of the medical bed.
[0031]
2) By correcting the error in the standing position of the bed caused by the load-side reverse rotation acting force, it is possible to appropriately control the driving of the motor for raising and lowering the bed.
[0032]
It is needless to say that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist thereof.
[0033]
As the rotation sensor, not only a magnetic sensor using a combination of a permanent magnet and a Hall element but also an optical sensor using a combination of a light emitting element and a light receiving element may be used. The present invention is particularly effective when applied to a case where a rotation sensor requiring bias power is used for sensing.
[0034]
In the above embodiment, the case where the present invention is applied to the motor incorporated in the actuator for automatically raising and lowering the bed of the medical bed has been described, but the motor control circuit according to the present invention is mounted on a vehicle such as an automobile. The present invention can also be applied to a power seat motor, a power window motor, and the like.
[0035]
【The invention's effect】
As described above, according to the present invention, when there is no detection output of the rotation sensor when the operation for operating the motor is stopped, the power supply to the rotation sensor is immediately stopped, and the detection output of the rotation sensor is output. In the case where there is, the power supply to the rotation sensor is stopped after a certain period of time has elapsed after the driving operation is stopped, so that power consumption can be reduced by reducing standby power and motor monitoring can be performed. It can be maintained properly.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a motor control circuit according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating an operation.
FIG. 3 is a waveform chart for explaining the operation.
FIGS. 4A and 4B are partially omitted side views showing a medical bed using a motor controlled by a motor control circuit according to an embodiment of the present invention. FIG. ) Indicate the awakened state, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Bed, 2 ... Frame, 3 ... Bed, 4 ... Axis, 5 ... Link, 6 ... Connection pin, 7 ... Actuator, 8 ... Housing, 9 ... Moving cylinder, 10 ... Motor (motor with worm gear reduction device), 11: transistor, 12: rotation sensor, 13: motor drive circuit, 14: battery, 15: switch for forward rotation, 16: switch for reverse rotation, 17: controller.

Claims (3)

In a motor control circuit including a rotation sensor that detects the rotation of the rotation shaft of the motor and outputs a signal, and a controller that counts the number of rotations based on the output signal of the rotation sensor ,
The controller monitors the presence or absence of the output signal of the rotation sensor by setting a waiting time after the operation for operating the motor is stopped, and there is an output signal of the rotation sensor during the waiting time. In this case, the waiting time is set again and the presence / absence of the output signal of the rotation sensor is monitored again. If there is no output signal of the rotation sensor during the waiting time, the rotation sensor is energized after the lapse of the waiting time. A motor control circuit configured to stop the motor control. The motor control circuit according to claim 1, wherein the motor is used in an electric feed screw type actuator that automatically raises and lowers a bed of a medical bed . A control method of a motor control circuit, comprising: a rotation sensor that detects rotation of a rotation shaft of a motor and outputs a signal, and a controller that counts a rotation speed based on an output signal of the rotation sensor,
  Monitoring the presence or absence of the output signal of the rotation sensor by setting a waiting time after the operation for driving the motor is stopped,
  When there is an output signal of the rotation sensor during the waiting time, a step of setting a waiting time again and monitoring the presence or absence of the output signal of the rotation sensor again,
  If there is no output signal of the rotation sensor during the waiting time, stopping the power supply to the rotation sensor after the waiting time elapses,
  A method for controlling a motor control circuit, comprising:

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