JP6922685B2 - DC motor over-rotation detector and vehicle - Google Patents

Description

The present invention relates to an over-rotation detection device for a DC motor and a vehicle.

Conventionally, there is known an over-rotation detection device for a DC motor in which a current due to over-rotation of the DC motor due to inertia is detected by a current detection unit (see, for example, Patent Document 1).

Patent Document 1 discloses a memory seat device for acquiring an absolute position of a vehicle seat moved by a driving force of a DC motor by outputting the rotation of the DC motor as a pulse signal. This memory sheet device stores a correction map in which different correction values are stored according to the moving direction of the sheet and the magnitude of the voltage value of the motor current signal when the current flowing through the DC motor is detected. .. Then, in the memory sheet device, the correction value of the correction map according to the moving direction of the sheet and the magnitude of the voltage value of the DC motor current signal is set at the position of the DC motor at the time when the DC motor is stopped detected by the pulse signal. By addition and subtraction, the absolute position of the DC motor is detected in consideration of the over-rotation of the DC motor.

Japanese Unexamined Patent Publication No. 2000-250629

However, in the memory seat device of Patent Document 1, when the load state on the seat is different from the assumption such as when a passenger is seated, the DC motor drives differently from the assumption at the time of creating the correction map. As a result, there is a disadvantage that the absolute position (virtual position) of the DC motor corrected by the correction value may differ (shift) from the actual absolute position of the DC motor. As a result, there is a problem that the positional deviation of the DC motor due to the over-rotation of the DC motor may not be accurately grasped.

The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to be able to accurately grasp the displacement of the DC motor due to the over-rotation of the DC motor. It is an object of the present invention to provide the over-rotation detection device of a DC motor and the vehicle provided with the over-rotation detection device.

In order to achieve the above object, the over-rotation detection device of the DC motor in the first aspect of the present invention is provided with the DC motor and the switch for intermittent operation, and when the current from the DC power supply to the DC motor is cut off. , A closed circuit forming unit through which a current due to over-rotation of the DC motor flows, and a current detecting unit connected to the closed circuit forming unit and detecting the current flowing through the DC motor are provided to generate a current to the DC motor. After shutting off, the intermittent operation switch is intermittently turned on and off, and the current is detected by the current detection unit due to the over-rotation of the DC motor due to inertia.

In the DC motor over-rotation detection device according to the first aspect of the present invention, by configuring as described above, when the intermittent operation switch of the closed circuit forming portion is turned off after cutting off the current to the DC motor. , The current caused by the over-rotation of the DC motor can be passed from the closed circuit forming portion to the current detecting portion side connected to the closed circuit forming portion. As a result, the current detection unit can directly detect the current that reflects the displacement of the DC motor due to the over-rotation of the DC motor, so that the displacement of the DC motor due to the over-rotation of the DC motor can be accurately detected. Can be grasped.

Further, in the DC motor over-rotation detection device according to the first aspect, when the intermittent operation switch of the closed circuit forming portion is turned on after the current to the DC motor is cut off, the DC motor is over-rotated due to inertia. The resulting current flows through the closed circuit forming part. As a result, the current caused by the over-rotation of the DC motor is a current generated based on the counter electromotive force. Can be added. As a result, the DC motor can be braked. Then, the intermittent operation in which the intermittent operation switch is intermittently turned on and off is performed to directly detect the current reflecting the displacement of the DC motor due to the over-rotation of the DC motor while braking the DC motor. can do.

In the DC motor over-rotation detection device according to the first aspect, preferably, the DC motor is arranged in a first motor drive switch and a closed circuit forming portion arranged between the DC power supply and the DC motor. The voltage polarity can be switched by the two-motor drive switch, and the intermittent operation switch is configured by the second motor drive switch.

With the above configuration, it is possible to directly detect the current that reflects the displacement of the DC motor due to over-rotation of the DC motor by using a part of the motor drive switch for switching the voltage polarity. The over-rotation detection device can be configured as possible. As a result, it is not necessary to provide the intermittent operation switch separately from the second motor drive switch, so that it is possible to suppress the complicated circuit configuration of the over-rotation detection device.

In this case, preferably, the second motor drive switch is turned on at the time of forward rotation of the DC motor and turned off at the time of reverse rotation, and is turned off at the time of forward rotation of the DC motor and turned on at the time of reverse rotation. After shutting off the current to the DC motor rotating in the forward direction, the first switch performs intermittent operation and cuts off the current to the DC motor rotating in the reverse direction. The two switches are configured to perform intermittent operation.

With the above configuration, when the current to the DC motor rotating in the forward direction is cut off, the current caused by the over-rotation of the DC motor flows in the direction of rotating the DC motor in the reverse direction, so it is turned off during the reverse rotation. By turning off the first switch, the current due to the over-rotation of the DC motor can flow to the current detection unit side connected to the closed circuit forming unit. Similarly, when the current to the DC motor rotating in the reverse direction is cut off, the current caused by the over-rotation of the DC motor flows in the direction of rotating the DC motor in the forward direction, so the second switch is turned off during the forward rotation. By turning off, the current caused by the over-rotation of the DC motor can be passed to the current detection unit side. As a result, the current detection unit can directly detect the current reflecting the displacement of the DC motor due to the over-rotation of the DC motor in both the forward rotation and the reverse rotation of the DC motor.

In the DC motor over-rotation detection device according to the first aspect, preferably, the current detection unit detects ripples included in the current due to the over-rotation of the DC motor after cutting off the current to the DC motor. Includes detector.

With the above configuration, for example, in a brushed DC motor in which ripple occurs when the contact between the brush and the commutator is switched, the over-rotation of the DC motor is rotated based on the ripple detected by the ripple detection unit. The amount (the amount of misalignment due to over-rotation) can be obtained directly. As a result, the displacement of the DC motor due to the over-rotation of the DC motor can be grasped more accurately.

In the over-rotation detection device of the DC motor according to the first aspect, preferably, the intermittent operation of the intermittent operation switch is configured to be periodically repeated, and the frequency of the intermittent operation of the intermittent operation switch and the frequency of the intermittent operation are At least one of the duty-on periods is configured to be adjustable depending on the DC motor. The "intermittent operation frequency" is the time (1 cycle) from the time when the intermittent operation switch is turned on (start point) to the time when the switch is turned on next (end point), divided by 1 (second). means. Further, the "duty-on period" means the ratio of the period in which the current is detected by the current detector in the period (1 cycle) from the time when the intermittent operation switch is turned on to the time when the switch is turned on next. do.

With the above configuration, the ratio between the detection of over-rotation when the intermittent operation switch is off and the braking of the DC motor when the intermittent operation switch is on is determined by the frequency of intermittent operation and the duration of duty on. By adjusting at least one of the above, it can be adjusted to an appropriate ratio for each DC motor. Thereby, the DC motor can be adjusted so that the DC motor can be effectively braked while surely grasping the misalignment of the DC motor due to the over-rotation of the DC motor.

The vehicle in the second aspect of the present invention includes a DC power supply, a DC motor, a movable part moved by the driving force of the DC motor, and an over-rotation detection device for detecting the over-rotation of the DC motor. The rotation detection device is provided with a DC motor and a switch for intermittent operation, and when the current from the DC power supply to the DC motor is cut off, a closed circuit forming unit through which a current due to over-rotation of the DC motor flows and a closed circuit An intermittent operation is performed in which the intermittent operation switch is intermittently turned on and off after interrupting the current to the DC motor, including a current detection unit that is connected to the forming unit and detects the current flowing through the DC motor. At the same time, the current due to the over-rotation of the DC motor due to inertia is detected by the current detection unit, so that the amount of movement of the movable unit is acquired.

In the vehicle according to the second aspect of the present invention, by configuring as described above, the current that reflects the displacement of the DC motor due to the over-rotation of the DC motor while braking the DC motor by the over-rotation detection device. Can be directly detected, so that it is possible to provide a vehicle capable of accurately grasping the amount of movement of the moving portion due to the over-rotation of the DC motor.

[Additional Notes]
In this application, apart from the over-rotation detection device of the DC motor according to the first aspect, the following other configurations are also conceivable.

(Appendix 1)
In the DC motor over-rotation detection device according to the first aspect, the frequency of the intermittent operation of the intermittent operation switch is higher than the frequency of the ripple contained in the current passing through the DC motor before cutting off the current to the DC motor. big.

(Appendix 2)
In the over-rotation detection device of the DC motor according to the first aspect, the DC motor is a brushed DC motor.

(Appendix 3)
In the DC motor over-rotation detection device according to the first aspect, the current detection unit includes a shunt resistor arranged between the ground side contact and the ground point of the closed circuit forming unit.

(Appendix 4)
In the DC motor over-rotation detection device according to the first aspect, a plurality of DC motors are provided, and a common current detection unit is configured to detect currents flowing through the plurality of DC motors.

(Appendix 5)
In the DC motor over-rotation detection device according to the first aspect, the intermittent operation switch is a field effect transistor.

(Appendix 6)
In this case, the field effect transistor is intermittently driven by the pulse width modulation signal.

(Appendix 7)
In the over-rotation detection device of the DC motor according to the first aspect, the intermittent operation of the intermittent operation switch is configured to be periodically repeated, and the frequency of the intermittent operation of the intermittent operation switch is the DC motor. It is configured to decrease as the elapsed time from the interruption of the current to is increased.

It is a figure which showed typically the whole structure of the vehicle which comprises the seat control part by one Embodiment of this invention. It is a circuit diagram which showed the circuit provided with the DC motor and the seat control part by one Embodiment of this invention. It is a circuit diagram which extracted a part of the circuit diagram of FIG. 2 for demonstrating the switching of a switch when a DC motor performs forward rotation (rotation in one direction). It is a circuit diagram which extracted a part of the circuit diagram of FIG. 2 for demonstrating the switching of a switch when a DC motor performs reverse rotation (rotation in another direction). FIG. 5A is a diagram for explaining ripple detection according to an embodiment of the present invention. FIG. 5B is an enlarged view for explaining ripple detection according to an embodiment of the present invention. It is a figure for demonstrating the intermittent operation (PWM signal) of the motor downstream switch by one Embodiment of this invention. It is a figure for demonstrating the intermittent operation (PWM signal) of the motor downstream switch by the modification of one Embodiment of this invention.

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

With reference to FIGS. 1 to 6, the configuration of the vehicle 100 including the seat control unit 4 (an example of the over-rotation detection device (of the DC motor)) of the DC motor 10 (11 to 14) according to the embodiment of the present invention. explain. The forward direction of the vehicle 100 is the front, and the backward direction of the vehicle 100 is the rear.

As shown in FIG. 1, the vehicle 100 includes a seat 1 (an example of a movable portion) in which a passenger (not shown) is seated. The seat 1 includes a seat cushion 1a, a seat back 1b attached to the rear part of the seat cushion 1a, a headrest 1c attached to the upper part of the seat back 1b, and a leg rest 1d attached to the front part of the seat cushion 1a. Includes. Further, the seat 1 is a so-called power seat, and is configured to be electrically movable in the front-rear direction and the like. Specifically, the entire seat 1 is electrically movable so as to be movable in the front-rear direction and the up-down direction. Further, the seat back 1b and the headrest 1c of the seat 1 are electrically configured to be rotatable in the first rotation direction with respect to the rear portion of the seat cushion 1a. Further, the leg rest 1d of the seat 1 is configured to be electrically rotatable with respect to the front portion of the seat cushion 1a in the second rotation direction.

Four DC motors 10 for generating a driving force by electric power are attached to the seat 1. The DC motor 10 is for rotating the DC motor 11 for moving the seat 1 in the front-rear direction, the DC motor 12 for moving the seat 1 in the vertical direction, and the seat back 1b of the seat 1 in the first rotation direction. The DC motor 13 and the DC motor 14 for rotating the leg rest 1d of the seat 1 in the second rotation direction are included. The DC motors 11 and 12 are configured to move the seat 1 in the front-rear direction and the up-down direction, respectively, via a drive mechanism (not shown). Similarly, the DC motors 13 and 14 are configured to rotate the seat back 1b and the leg rest 1d, respectively, via a drive mechanism (not shown).

The four DC motors 10 are all so-called brushed DC motors. That is, the four DC motors 10 include a rotor having a coiled winding and a pair of commutators (not shown) and a stator having a pair of brushes 10a and 10b (not shown). It is configured to convert the direct current supplied to the winding into a driving force. In the DC motor 10, ripples as current turbulence are generated by switching the connection state between the commutator and the brushes 10a and 10b. Further, ripples are generated at time intervals according to the rotation speed of the DC motor 10.

Further, as shown in FIG. 2, the vehicle 100 further includes a DC power supply 2, an operation switch unit 3, and a seat control unit 4. The DC power supply 2 supplies electric power to the DC motor 10 and the like. The operation switch unit 3 receives operations related to the seat from passengers and the like. The seat control unit 4 is driven by the electric power from the DC power supply 2 and controls the drive on the seat 1.

The negative electrode side terminal 2a of the DC power supply 2 is grounded to the chassis (not shown) of the vehicle 100 which is the grounding point E. The positive electrode side terminal 2b of the DC power supply 2 is connected to the four DC motors 10 and the seat control unit 4.

The operation switch unit 3 is an operation switch operated by a passenger when the seat 1 is moved in the front-rear direction or the like. The operation switch unit 3 is provided with four operation switches (not shown) corresponding to the forward / backward movement and the vertical movement of the seat 1, the rotational movement of the seat back 1b, and the rotational movement of the leg rest 1d, respectively. ing. Then, an operation signal related to the operation performed on the operation switch unit 3 is transmitted to the seat control unit 4.

The seat control unit 4 has a control CPU 5, a memory 6, a plurality of (10) switches 7, one shunt resistor 81, and one current detection circuit 82 (an example of the ripple detection unit). The current detection unit 8 is included. The control CPU 5 executes arithmetic processing based on the control program and the map related to the control of the sheet 1 stored in the memory 6, and temporarily stores the arithmetic result in the memory 6. The control CPU 5 is connected to the operation switch unit 3, the memory 6, each of the plurality of switches 7, and the current detection circuit 82 of the current detection unit 8.

The memory 6 includes a ROM (Read Only Memory) in which a control program and a map related to sheet control are stored, a RAM (Random Access Memory) in which calculation results are temporarily stored, and the like.

The 10 switches 7 include 5 motor upstream switches 7a (70 to 74, an example of a switch for driving the first motor) arranged between the DC power supply 2 and the DC motor 10, and the DC motor 10 and a shunt resistor. It is composed of five motor downstream switches 7b (75 to 79, an example of a second motor drive switch) arranged between 81 and 81. The five motor upstream switches 7a electrically connect (on) or electrically disconnect (off) the corresponding DC motor 10 and the DC power supply 2. Further, the five motor downstream switches 7b electrically connect (on) or electrically disconnect (off) the corresponding DC motor 10 and the shunt resistor 81.

Further, the switch 7 is composed of a field effect transistor (FET). The switch 7 composed of FETs has a shorter time required for on / off switching and is less likely to be damaged and has high reliability as compared with a relay that mechanically switches contacts.

Of the five motor upstream switches 7a, the pair of motor upstream switches 7a are connected to the brush 10a on one side and the brush 10b on the other side of one DC motor 10, respectively. Specifically, the motor upstream switches 70 and 71 are connected to the brush 10a on one side and the brush 10b on the other side of the DC motor 11, respectively. The motor upstream switches 71 and 72 are connected to the brush 10a on one side and the brush 10b on the other side of the DC motor 12, respectively. The motor upstream switches 72 and 73 are connected to the brush 10a on one side and the brush 10b on the other side of the DC motor 13, respectively. The motor upstream switches 73 and 74 are connected to the brush 10a on one side and the brush 10b on the other side of the DC motor 14, respectively. The motor upstream switches 71 to 73 each correspond to two DC motors 10.

Further, of the five motor downstream switches 7b, the pair of motor downstream switches 7b are connected to the brush 10a on one side and the brush 10b on the other side of one DC motor 10, respectively. Specifically, the motor downstream switches 75 and 76 are connected to the brush 10a on one side and the brush 10b on the other side of the DC motor 11, respectively. The motor downstream switches 76 and 77 are connected to the brush 10a on one side and the brush 10b on the other side of the DC motor 12, respectively. The motor downstream switches 77 and 78 are connected to the brush 10a on one side and the brush 10b on the other side of the DC motor 13, respectively. The motor downstream switches 78 and 79 are connected to the brush 10a on one side and the brush 10b on the other side of the DC motor 14, respectively. The motor downstream switches 76 to 78 correspond to two DC motors 10, respectively.

Further, the closed circuit forming portion 20 is formed by the DC motor 10 and the pair of motor downstream switches 7b that correspond to the DC motor 10 and are in the ON state. Specifically, the DC motor 11 and the pair of motor downstream switches 75 and 76 in the ON state form the closed circuit forming portion 21. Further, the DC motor 12 and the pair of motor downstream switches 76 and 77 in the ON state form the closed circuit forming portion 22. Further, the DC motor 13 and the pair of motor downstream switches 77 and 78 in the ON state form the closed circuit forming portion 23. Further, the DC motor 14 and the pair of motor downstream switches 78 and 79 in the ON state form the closed circuit forming portion 24.

The current detection unit 8 detects the direct current flowing through the direct current motor 10. Specifically, the shunt resistor 81 of the current detection unit 8 is in contact with the ground side contact 20a provided in the closed circuit forming unit 20 on the side opposite to the DC motor 10 among the pair of motor downstream switches 7b. It is located between the point E and the point E. The shunt resistor 81 converts a current waveform including ripple into a voltage waveform.

The current detection circuit 82 is connected to both ends of the shunt resistor 81. The current detection circuit 82 detects ripples contained in the direct current flowing through the direct current motor 10. Specifically, the current detection circuit 82 is converted by the shunt resistor 81 and is output from the analog-to-digital conversion circuit 82a that converts the analog voltage waveform for monitoring the current waveform into a digital signal and the analog-digital conversion circuit 82a. It has a bunt path filter 82b for extracting a ripple waveform component by removing a high frequency portion (noise) and the like from the digital signal. Further, the current detection circuit 82 raises the pulse signal at the timing when the extracted ripple waveform component is increased by the first amplitude threshold (first voltage threshold) and only the second amplitude threshold (second voltage threshold). It further includes a ripple determination unit 82c that generates a pulse signal indicating the detected ripple by lowering the pulse signal at the reduced timing. Further, the current detection circuit 82 further adds a cutoff control unit 82d that acquires a frequency component or the like to be removed by the buntpass filter 82b based on the signal output from the ripple determination unit 82c and transmits it to the buntpass filter 82b. Have. Then, the pulse signal generated in the current detection circuit 82 is supplied to the control CPU 5.

The control CPU 5 controls the DC motor 10 (control of the sheet 1) based on the control program stored in the memory 6 and the supplied pulse signal. As a result, the control CPU 5 is configured to control the movement of the seat 1 (forward / backward movement, vertical movement, two types of rotational movement).

When controlling the drive of the DC motor 10, the seat control unit 4 drives only the DC motor 10 corresponding to any one of the movements (forward / backward movement, vertical movement, and two types of rotational movement) at a time. It is configured as follows. That is, the seat control unit 4 is configured so as not to drive a plurality of DC motors 10 at one time. The seat control unit 4 is configured such that the common current detection unit 8 (shunt resistor 81 and current detection circuit 82) detects the currents flowing through the DC motors 11 to 14, respectively. Hereinafter, specific control of the seat control unit 4 (control CPU 5) will be described.

(DC motor drive control)
When the DC motor 10 of any one of the plurality of DC motors 10 (11 to 14) is driven to rotate (forward rotation) in a predetermined drive direction (for example, in the forward direction), the control CPU 5 drives the DC motor 10 Of the pair of motor upstream switches 7a corresponding to the above, one motor upstream switch 7a corresponding to the drive direction (positive direction) is turned on, and the other motor upstream switch 7a not corresponding to the drive direction (positive direction) is turned on. The three motor upstream switches 7a that do not correspond to the DC motor 10 to be driven are turned off. Further, the control CPU 5 turns on one of the pair of motor downstream switches 7b corresponding to the DC motor 10 to be driven, which corresponds to the drive direction (positive direction) (an example of the first switch). , The other motor downstream switch 7b (an example of the second switch) that does not correspond to the drive direction (forward direction) and the three motor downstream switches 7b that do not correspond to the DC motor 10 to be driven are turned off. Note that "forward rotation" means rotation in one direction of the axial rotation of the DC motor 10, and "reverse rotation" means rotation in the other direction of the axial rotation of the DC motor 10. It means (rotation in the opposite direction to forward rotation).

As a result, the current (direct current) from the DC power supply 2 flows from one side to the other side of the DC motor 10 and then flows to the shunt resistor 81. As a result, the DC motor 10 rotates (forward rotation) in the drive direction (forward direction), and the current waveform including ripples generated due to the switching of the connection state of the brushes 10a (10b) becomes a voltage due to the shunt resistor 81. It is changed into a waveform and passed to the current detection circuit 82. Then, in the current detection circuit 82, the ripple waveform is converted into a pulse waveform and supplied to the control CPU 5. As a result, the control CPU 5 grasps the amount of rotation of the DC motor 10 and acquires the amount of movement of the sheet 1 corresponding to the amount of rotation of the DC motor 10 in the corresponding direction.

Further, when the voltage polarity of the DC motor 10 is changed to rotate (reverse rotation) in a direction opposite to a predetermined drive direction (reverse direction), the control CPU 5 is a pair of motors corresponding to the DC motor 10 to be driven. Of the upstream switches 7a, the other motor upstream switch 7a corresponding to the drive direction (reverse direction) is turned on, and one motor upstream switch 7a not corresponding to the drive direction (reverse direction) and the DC motor 10 to be driven are used. Turn off the three non-corresponding motor upstream switches 7a. Further, the control CPU 5 turns on the other motor downstream switch 7b corresponding to the drive direction (reverse rotation) of the pair of motor downstream switches 7b corresponding to the DC motor 10 to be driven, and also turns on the drive direction (reverse rotation). One motor downstream switch 7b that does not correspond to the above and three motor downstream switches 7b that do not correspond to the DC motor 10 to be driven are turned off. As a result, the DC motor 10 rotates (reverse rotation) in the driving direction (reverse direction).

Specifically, each of the DC motors 11 to 14 will be described in detail. When the DC motor 11 is rotated in the forward direction, the control CPU 5 turns on the motor upstream switch 70 and the motor downstream switch 76 (an example of the first switch). , Motor upstream switches 71-74 and motor downstream switches 75 and 77-79 are turned off. When the DC motor 11 is rotated in the reverse direction, the control CPU 5 turns on the motor upstream switch 71 and the motor downstream switch 75 (an example of the second switch), and also turns on the motor upstream switches 70, 72 to 74 and the motor. Turn off the downstream switches 76 to 79.

When rotating the DC motor 12 in the forward direction, the control CPU 5 turns on the motor upstream switch 71 and the motor downstream switch 77 (an example of the first switch), and also turns on the motor upstream switches 70 and 72 to 74 and the motor downstream switch. Turn off 75, 76, 78 and 79. When the DC motor 12 is rotated in the reverse direction, the control CPU 5 turns on the motor upstream switch 72 and the motor downstream switch 76 (an example of the second switch), and also causes the motor upstream switches 70, 71, 73 and 74. , Motor downstream switches 75 and 77-79 are turned off.

When the DC motor 13 is rotated in the forward direction, the control CPU 5 turns on the motor upstream switch 72 and the motor downstream switch 78 (an example of the first switch), and also turns on the motor upstream switches 70, 71, 73 and 74 and the motor. Turn off the downstream switches 75-77 and 79. When the DC motor 13 is rotated in the reverse direction, the control CPU 5 turns on the motor upstream switch 73 and the motor downstream switch 77 (an example of the second switch), and also turns on the motor upstream switches 70 to 72 and 74 and the motor. Turn off the downstream switches 75, 76, 78 and 79.

When the DC motor 14 is rotated in the forward direction, the control CPU 5 turns on the motor upstream switch 73 and the motor downstream switch 79 (an example of the first switch), and also turns on the motor upstream switches 70 to 72 and 74 and the motor downstream switch. Turn off 75-78. When the DC motor 14 is rotated in the reverse direction, the control CPU 5 turns on the motor upstream switch 74 and the motor downstream switch 78 (an example of the second switch), and also turns on the motor upstream switches 70 to 73 and the motor downstream switch. Turn off 75-77 and 79.

Hereinafter, the drive control of any of the DC motors 10 among the DC motors 11 to 14 will be described. At this time, as shown in FIGS. 3 and 4, the motor upstream switch 7a and the motor downstream switch 7b, which are turned on when the DC motor 10 is rotated in the forward direction and turned off when the DC motor 10 is rotated in the reverse direction, are switched to the first upstream switch, respectively. 7a1 and the first downstream switch 7b1 (an example of the first switch). Further, the motor upstream switch 7a and the motor downstream switch 7b, which are turned on when the DC motor 10 is rotated in the reverse direction and turned off when the DC motor 10 is rotated in the forward direction, are the second upstream switch 7a2 and the second downstream switch 7b2 (second switch, respectively). An example).

(After stopping the DC motor)
As shown in FIG. 3, the control CPU 5 turns off the first upstream switch 7a1 from the state in which the DC motor 10 is rotating in the forward direction, and supplies a current from the DC power supply 2 to the DC motor 10 in the forward rotation. It is configured to turn on the second downstream switch 7b2 when shutting off. As a result, the closed circuit forming portion 20 is formed by the DC motor 10 and the pair of motor downstream switches 7b in the on state.

Even after the current from the DC power supply 2 is cut off, the DC motor 10 does not stop immediately due to inertia and continues to rotate in the same direction. At this time, in the DC motor 10, the over-rotation of the DC motor 10 generates a counter electromotive force that causes a current to flow in a direction opposite to the direction in which the direct current supplied to the DC motor 10 flows. Then, the current due to the counter electromotive force flows in the closed circuit forming portion 20, so that a force (braking force) is applied in the direction of restricting the over-rotation of the DC motor 10 in the DC motor 10. As a result, the DC motor 10 is braked. As a result, the rotation speed of the DC motor 10 gradually decreases with the passage of time, so that the ripple period λ1 ( (See FIG. 5) gradually increases with the passage of time.

Here, in the present embodiment, the control CPU 5 of the seat control unit 4 keeps the second downstream switch 7b2 on while interrupting the current from the DC power supply 2 to the DC motor 10 that has been rotating in the forward direction. The first downstream switch 7b1 (an example of an intermittent operation switch) is configured to be controlled so as to perform an intermittent operation in which the first downstream switch 7b1 (an example of an intermittent operation switch) is intermittently turned on and off. That is, the first downstream switch 7b1 (switch 7 surrounded by a thin alternate long and short dash line in FIG. 3), which is one of the ten switches 7 used to drive the DC motor 10, is configured to perform intermittent operation. Has been done.

As a result, when the first downstream switch 7b1 is on, the DC motor 10 is braked as described above. On the other hand, when the first downstream switch 7b1 is off, the current generated by the over-rotation of the DC motor 10 flows through the shunt resistor 81 connected to the closed circuit forming unit 20. Then, as shown in FIG. 5, the shunt resistor 81 detects the direct current flowing through the direct current motor 10, and the current detection circuit 82 detects the ripple contained in the current due to over-rotation to generate a pulse signal. Will be done. Then, the generated pulse signal is supplied to the control CPU 5.

Further, in the present embodiment, as shown in FIGS. 5 and 6, the intermittent operation of the first downstream switch 7b1 is cycled at a constant cycle λ2 by a pulse width modulation (PWM) signal from the control CPU 5. It is configured to be repeated. At this time, the frequency of the intermittent operation of the first downstream switch 7b1 (frequency of the PWM signal) is set to be larger than the frequency of the ripple included in the current passing through the DC motor 10 before the current to the DC motor 10 is cut off. It has been adjusted to. As a result, the period λ2 of the intermittent operation of the first downstream switch 7b1 is smaller than the period λ3 of the ripple included in the current passing through the DC motor 10 before cutting off the current from the DC power supply 2.

Here, since the rotation speed of the DC motor 10 in over-rotation is equal to or lower than the rotation speed of the DC motor 10 before the current from the DC power supply 2 is cut off, the DC motor 10 is before the current from the DC power supply 2 is cut off. The ripple cycle λ3 included in the current passing through the DC motor 10 is equal to or greater than the ripple cycle λ1 included in the current flowing through the DC motor 10 after the current from the DC power supply 2 is cut off. Therefore, the period λ2 of the intermittent operation of the first downstream switch 7b1 is smaller than the period λ1 of the ripple included in the direct current after the current from the direct current power supply 2 is cut off. As a result, even if the first downstream switch 7b1 is operated intermittently, it is possible to reliably detect the ripple contained in the direct current from the direct current motor 10 due to the over-rotation.

Of the ripple period λ1 included in the direct current after the current from the DC power supply 2 is cut off, the minimum period λ1min is the ripple period λ1 detected immediately after the current from the DC power supply 2 is cut off. .. Here, the period λ2 (<λ1min) of the intermittent operation of the first downstream switch 7b1 is 1/10 times or less of the minimum period λ1min of the ripple contained in the direct current after the current from the direct current power supply 2 is cut off. Is preferable, and 1/20 times or less is more preferable.

Since the first downstream switch 7b1 (switch 7) is composed of an FET in which the time required for switching on / off is short as described above, the frequency of the intermittent operation of the first downstream switch 7b1 (the frequency of the PWM signal) can be set. The frequency of the ripple contained in the direct current passing through the direct current motor 10 before the current from the direct current power supply 2 is cut off can be easily increased.

Further, it is preferable that the period in which the first downstream switch 7b1 is off and the current is detected by the current detection unit 8 (duty-on period) is equal to or less than the period other than duty-on (duty-off period). That is, the on period of the PWM signal from the control CPU 5 is preferably equal to or less than the off period of the PWM signal. For example, the duty-on period of the first downstream switch 7b1 is preferably 10% or less (more preferably 5% or less) of the period λ2 of the intermittent operation of the first downstream switch 7b1. As a result, the period during which the first downstream switch 7b1 is turned off can be shortened, and the period during which the first downstream switch 7b1 is turned on can be sufficiently secured, so that it is possible to suppress that the DC motor 10 is not sufficiently braked. Is. The duty-on period of the first downstream switch 7b1 may be longer than the period during which the current detection unit 8 can correctly detect the current.

Further, the frequency of the intermittent operation of the motor downstream switch 7b and the duty-on period are configured to be adjustable for each of the different types of DC motors 10. For example, it is possible to optimize the frequency of intermittent operation and the duty-on period according to the type of the DC motor 10 at the time of designing. The frequency and duty-on period of the intermittent operation measured in advance are stored in the memory 6 of the seat control unit 4 at the time of shipment, and the control CPU 5 stores the frequency and duty of the intermittent operation stored in the memory 6. Generates a PWM signal based on the on period.

Further, the intermittent operation of the first downstream switch 7b1 is continued until a ripple having a sufficient magnitude is not detected. That is, it continues until a ripple of a magnitude that allows the pulse signal to rise or fall is no longer detected. Then, the control CPU 5 grasps the amount of over-rotation of the DC motor 10 due to inertia, so that the positional deviation of the DC motor 10 is grasped. As a result, the amount of movement due to the over-rotation of the sheet 1 in the corresponding direction corresponding to the amount of rotation of the DC motor 10 is acquired.

When the DC motor 10 is rotated in the reverse direction, as shown in FIG. 4, the current from the DC power supply 2 to the DC motor 10 that has been rotated in the reverse direction is cut off, and then the first downstream switch 7b1 is turned on. The second downstream switch 7b2 (an example of an intermittent operation switch) is configured to be controlled so as to perform an intermittent operation of intermittently turning on and off. That is, the second downstream switch 7b2 (switch 7 surrounded by a thin alternate long and short dash line in FIG. 4), which is one of the ten switches 7 used to drive the DC motor 10, is configured to perform intermittent operation. Has been done. As a result, when the second downstream switch 7b2 is on, the DC motor 10 is braked, while when the second downstream switch 7b2 is off, the current generated by the over-rotation of the DC motor 10 is generated. Detected. Since the intermittent operation of the second downstream switch 7b2 is substantially the same as the intermittent operation of the first downstream switch 7b1 of the forward rotation of the DC motor 10, the description thereof will be omitted.

[Effect of this embodiment]
In this embodiment, the following effects can be obtained.

In the present embodiment, as described above, after the current from the DC power supply 2 to the DC motor 10 is cut off, the motor downstream switch 7b is intermittently turned on and off, and the DC motor 10 is operated by inertia. The current due to over-rotation is detected by the current detection unit 8. As a result, when the motor downstream switch 7b of the closed circuit forming unit 20 is turned off after cutting off the current to the DC motor 10, the current caused by the over-rotation of the DC motor 10 is transferred from the closed circuit forming unit 20 to the closed circuit. It can flow to the current detection unit 8 side connected to the forming unit 20. As a result, the current detection unit 8 can directly detect the current reflecting the displacement of the DC motor 10 due to the over-rotation of the DC motor 10, so that the DC motor 10 caused by the over-rotation of the DC motor 10 can be directly detected. It is possible to accurately grasp the misalignment of.

Here, in order to detect the current caused by the over-rotation of the DC motor and to brake the DC motor with a configuration different from that of the present embodiment, a closed circuit is formed in which both the current detection unit and the DC motor are arranged. It is conceivable to provide a part. In this case, a circuit in which a current flows through the DC motor and the current detection unit to the ground point during driving, and both the current detection unit and the DC motor are arranged when stopped, and the DC motor is over-rotated. It is necessary to switch to the closed circuit forming part where the current due to the circulation is circulated. Therefore, in this case, it is necessary to additionally provide a new circuit in which the switch is arranged. On the other hand, in the present embodiment, since it is not necessary to additionally provide a new circuit in which the switch is arranged by the above-described configuration, it is possible to suppress the complicated circuit configuration of the seat control unit 4. can.

Further, in the present embodiment, when the motor downstream switch 7b of the closed circuit forming unit 20 is turned on after the current to the DC motor 10 is cut off, the current caused by the over-rotation of the DC motor 10 due to inertia is closed. It flows through the forming portion 20. As a result, the current caused by the over-rotation of the DC motor 10 is a current generated based on the counter electromotive force. Therefore, the current flows through the DC motor 10 to regulate the over-rotation of the DC motor 10. Braking force) can be applied. As a result, the DC motor 10 that over-rotates can be braked. Then, by performing an intermittent operation in which the motor downstream switch 7b is intermittently turned on and off, the DC motor 10 is braked, and the current reflecting the displacement of the DC motor 10 due to the over-rotation of the DC motor 10 is directly transmitted. Can be detected. Therefore, it is possible to provide the vehicle 100 capable of accurately grasping the amount of movement of the seat 1 due to the over-rotation of the DC motor 10.

Further, in the present embodiment, the motor downstream switch 7b is configured to operate intermittently. This makes it possible to directly detect the current reflecting the displacement of the DC motor 10 due to the over-rotation of the DC motor 10 by using a part of the switch 7 for switching the voltage polarity. 4 can be configured. As a result, since it is not necessary to provide the intermittent operation switch separately from the motor downstream switch 7b, it is possible to suppress the complicated circuit configuration of the seat control unit 4.

Further, in the present embodiment, after interrupting the current to the DC motor 10 rotating in the forward direction, the first downstream switch 7b1 that is turned off in the reverse rotation is configured to perform an intermittent operation. As a result, when the current to the DC motor 10 rotating in the forward direction is cut off, the current caused by the over-rotation of the DC motor 10 flows in the direction of rotating the DC motor 10 in the reverse direction, so that the current is turned off during the reverse rotation. By turning off the first downstream switch 7b1, the current due to the over-rotation of the DC motor 10 can flow to the current detection unit 8 side connected to the closed circuit forming unit 20. Further, after interrupting the current to the DC motor 10 rotating in the reverse direction, the second downstream switch 7b2, which is turned off during the forward rotation, is configured to perform an intermittent operation. As a result, when the current to the DC motor 10 rotating in the reverse direction is cut off, the current caused by the over-rotation of the DC motor 10 flows in the direction of rotating the DC motor 10 in the forward direction, so that the current is turned off during the forward rotation. By turning off the second downstream switch 7b2, the current caused by the over-rotation of the DC motor 10 can flow to the current detection unit 8 side. As a result, the current detection unit 8 directly detects the current reflecting the misalignment of the DC motor 10 due to the over-rotation of the DC motor 10 in both the forward rotation and the reverse rotation of the DC motor 10. be able to.

Further, in the present embodiment, the current detection unit 8 is provided with a current detection circuit 82 that detects ripples included in the current caused by the over-rotation of the DC motor 10 after cutting off the current to the DC motor 10. As a result, in the DC motor 10 with a brush in which ripple is generated when the contact between the brushes 10a and 10b and the commutator is switched, the over-rotation of the DC motor 10 is based on the ripple detected by the current detection circuit 82. The amount (the amount of misalignment due to over-rotation) can be obtained directly. As a result, the positional deviation of the DC motor 10 due to the over-rotation of the DC motor 10 can be grasped more accurately.

Further, in the present embodiment, the frequency of the intermittent operation of the motor downstream switch 7b and the duty-on period are configured to be adjustable according to the DC motor 10. Thereby, the ratio of the detection of over-rotation when the motor downstream switch 7b is off and the braking of the DC motor 10 when the motor downstream switch 7b is on is adjusted by adjusting the frequency of intermittent operation and the duty-on period. Therefore, it can be adjusted to an appropriate ratio for each DC motor 10. As a result, the DC motor 10 can be adjusted so that the DC motor 10 can be effectively braked while reliably grasping the positional deviation of the DC motor 10 due to the over-rotation of the DC motor 10. ..

Further, in the present embodiment, the frequency of the intermittent operation of the motor downstream switch 7b is set to be larger than the frequency of the ripple included in the current passing through the DC motor 10 before the current to the DC motor 10 is cut off. As a result, even if the motor downstream switch 7b is operated intermittently, the ripple included in the direct current from the direct current motor 10 during over-rotation can be reliably detected.

Further, in the present embodiment, by configuring as described above, while braking the DC motor 10 with a brush, the current reflecting the misalignment of the DC motor 10 due to the over-rotation of the DC motor 10 is directly transmitted. Can be detected.

Further, in the present embodiment, by arranging the shunt resistor 81 of the current detection unit 8 between the ground side contact 20a of the closed circuit forming unit 20 and the ground point E, the current flowing through the DC motor 10 is reliably detected. can do. Further, unlike the case where the current detection unit (shunt resistor) is provided in the closed circuit forming unit, it is possible to prevent the current from the DC power supply 2 from directly flowing into the shunt resistor 81 when the DC motor 10 is driven. As a result, it is not necessary to increase the voltage detection range of the current detection circuit 82 so as to correspond to the voltage of the DC power supply 2, so that the circuit configuration of the current detection circuit 82 becomes complicated (the circuit cost increases). Can be suppressed.

Further, in the present embodiment, the common current detection unit 8 is configured to detect each of the currents flowing through the plurality (4) DC motors 10 (11 to 14). As a result, it is not necessary to provide the current detection unit 8 for each of the DC motors 11 to 14, so that it is possible to effectively suppress the complicated circuit configuration of the seat control unit 4.

Further, in the present embodiment, since the motor downstream switch 7b is a field effect transistor, the time interval (cycle) of the intermittent operation can be surely shortened because the time required for switching on / off is short. As a result, it is possible to prevent the periodic ripple from being sufficiently detected by the current detection circuit 82 of the current detection unit 8 due to the long time interval of the intermittent operation.

Further, in the present embodiment, the motor downstream switch 7b composed of the field effect transistor is intermittently driven by the PWM signal. As a result, the motor downstream switch 7b can be reliably and intermittently driven.

[Modification example]
It should be noted that the embodiments disclosed this time are exemplary in all respects and are not considered to be restrictive. The scope of the present invention is shown by the scope of claims rather than the description of the above-described embodiment, and further includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims.

For example, in the above embodiment, an example is shown in which the intermittent operation of the motor downstream switch 7b (intermittent operation switch) is periodically repeated at a constant period λ2, but the present invention is not limited to this. .. In the present invention, the intermittent operation of the intermittent operation switch does not have to be performed at regular intervals. For example, as shown in FIG. 7, the intermittent operation cycle (PWM signal cycle) λ2 of the intermittent operation switch may be increased as the elapsed time from cutting off the current to the DC motor increases. .. That is, the frequency of the intermittent operation of the intermittent operation switch may be configured to decrease as the elapsed time from the interruption of the current to the DC motor increases.

Here, as described above, the period λ1 of the ripple included in the DC caused by the over-rotation of the DC motor after the current from the DC power supply is cut off gradually increases with the passage of time, so that the elapsed time increases. Therefore, even if the period λ2 of the intermittent operation of the intermittent operation switch is increased, the periodic ripple is not sufficiently detected by the current detection circuit 82 of the current detection unit 8 due to the long time interval of the intermittent operation. It is possible to suppress. Further, the duty-on period of the first downstream switch 7b1 may be longer than the period during which the current detection unit 8 can correctly detect the current, and it is not necessary to lengthen the duty-on period. The duty-off period other than the period can be lengthened as the elapsed time increases. This makes it possible to effectively brake the DC motor 10.

Further, in the above embodiment, an example in which the switch 7 (intermittent operation switch, second motor drive switch) is composed of a field effect transistor is shown, but the present invention is not limited to this. For example, the intermittent operation switch may be configured to include a relay that mechanically switches contacts. Further, for example, in the above embodiment, the five motor upstream switches 7a are composed of relays, and only the five motor downstream switches 7b (intermittent operation switch, second motor drive switch) that are intermittently driven have a field effect. It may be composed of transistors.

Further, in the above embodiment, an example is shown in which a common current detection unit 8 is configured to detect currents flowing through a plurality of (4) DC motors 11 to 14, but the present invention is limited to this. I can't. In the present invention, a current detection unit may be provided in each of the plurality of DC motors. Further, while each of the plurality of DC motors is provided with only the shunt resistor of the current detection unit, the ripple detection unit of the current detection unit may be shared.

Further, in the above embodiment, examples are shown in which the motor upstream switches 71 to 73 and the motor downstream switches 76 to 78 correspond to two DC motors 10, respectively, but the present invention is not limited to this. For example, the over-rotation detection device may be configured from a switch corresponding to only one DC motor without providing a switch corresponding to two DC motors. That is, in order to switch the voltage polarity of the DC motor (configure so that it can rotate in both forward and reverse directions), four switches may be provided for one DC motor.

Further, in the above embodiment, an example in which the seat 1 (movable portion) is moved in the front-rear direction, the up-down direction, and the two rotation directions by the driving force of the four DC motors 10 is shown. Not limited. In the present invention, the seat (moving part) may be moved in a predetermined direction by the driving force of 1 to 3 or 5 or more DC motors. Further, the "moving part" is not limited to the seat of the vehicle. For example, in a vehicle, "moving parts" that are moved by a DC motor include an electric window, an electric sunroof, an electric sliding door, and an electric wiper. In addition to vehicles, there are electric massage chairs and electric reclining beds as "moving parts" that are moved by a DC motor. The over-rotation detection device of the present invention can be used in place of the Hall element that detects the rotation of the DC motor based on the change in magnetic force. In particular, the over-rotation detection device of the present invention can be suitably used in a place where it is difficult to use a Hall element and has a large temperature change (for example, in the engine room of a vehicle).

Further, in the present invention, a pulse width modulation (PWM) signal may be used as the current from the DC power supply. In this case, in order to generate the PWM signal, the DC power supply itself may be configured to be switchable and controllable by the control CPU, or the first motor drive switch arranged between the DC power supply and the DC motor may be configured. As a switch for generating a PWM signal, a control CPU may be configured to enable switching control.

Further, in the above embodiment, an example is shown in which the frequency of the intermittent operation and the duty-on period of the motor downstream switch 7b (switch for intermittent operation) are configured to be adjustable for each of the different types of DC motors 10. The present invention is not limited to this. In the present invention, only one of the intermittent operation frequency and the duty-on period of the intermittent operation switch may be adjusted for each DC motor. Further, even if the DC motors 10 are of the same type, the frequency of the intermittent operation and the duty-on period of the intermittent operation switch may be adjusted for each DC motor 10.

1 sheet (moving part)
2 DC power supply 4 Seat control unit (over-rotation detector (of DC motor))
7a (70, 71, 72, 73, 74) Motor upstream switch (first motor drive switch)
7b (75, 76, 77, 78, 79) Motor downstream switch (second motor drive switch, intermittent operation switch)
7b1 1st downstream switch (1st switch)
7b2 2nd downstream switch (2nd switch)
8 Current detection unit 10 (11, 12, 13, 14) DC motor 20 (21, 22, 23, 24) Closed circuit forming unit 81 Shunt resistor 82 Current detection circuit (ripple detection unit)

Claims (6)

A closed circuit forming unit in which a DC motor and a switch for intermittent operation are provided and a current due to over-rotation of the DC motor flows when the current from the DC power supply to the DC motor is cut off.
It is connected to the closed circuit forming unit and includes a current detecting unit that detects a current flowing through the DC motor.
After interrupting the current to the DC motor, the intermittent operation switch is intermittently turned on and off, and the current due to the over-rotation of the DC motor due to inertia is detected by the current detection unit. DC motor over-rotation detector configured to. The voltage polarity of the DC motor is switched by a first motor drive switch arranged between the DC power supply and the DC motor and a second motor drive switch arranged in the closed circuit forming portion. Is composed of
The over-rotation detection device for a DC motor according to claim 1, wherein the intermittent operation switch is composed of the second motor drive switch. The second motor drive switch is a first switch that is turned on and turned off when the DC motor is rotating in the forward direction and a second switch that is turned off when the DC motor is rotating in the forward direction and is turned on when the DC motor is rotating in the reverse direction. Including switch
After interrupting the current to the DC motor rotating in the forward direction, the intermittent operation is performed in the first switch, and after cutting off the current to the DC motor rotating in the reverse direction, the second switch performs the intermittent operation. The overspeed detection device for a DC motor according to claim 2, which is configured to perform the intermittent operation. The current detection unit includes any one of claims 1 to 3 including a ripple detection unit that detects ripples included in the current caused by the over-rotation of the DC motor after interrupting the current to the DC motor. The DC motor over-rotation detection device described in 1. The intermittent operation of the intermittent operation switch is configured to be periodically repeated.
The invention according to any one of claims 1 to 4, wherein at least one of the frequency of the intermittent operation and the period of duty-on of the intermittent operation switch is configured to be adjustable according to the DC motor. DC motor over-rotation detector. DC power supply and
DC motor and
A moving part that is moved by the driving force of the DC motor and
A super-rotation detection device for detecting the over-rotation of the DC motor is provided.
The over-rotation detection device is
A closed circuit forming portion in which the DC motor and a switch for intermittent operation are provided and a current due to over-rotation of the DC motor flows when the current from the DC power supply to the DC motor is cut off.
It includes a current detection unit that is connected to the closed circuit forming unit and detects a current flowing through the DC motor.
After cutting off the direct current to the DC motor, the intermittent operation switch is intermittently turned on and off, and the current due to the over-rotation of the DC motor due to inertia is detected by the current detection unit. By doing so, the vehicle is configured so that the amount of movement of the movable portion is acquired.

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