control device

Abstract

To provide a control device that can prevent deformation of a movable part or an abutting target as much as possible.SOLUTION: A motor current detection unit 42 operates at a positive power supply voltage and detects current in a motor 31. An abutting detection unit 44 assumes that a door and a stopper abut on each other when the current in the motor exceeds a current threshold previously determined such that a torque applied to the motor by rotation of the motor by a motor driver 41 in a prescribed direction does not reach a limit value. A controller 40 stops driving of the motor driver based on a result of detection by the abutting detection unit. The controller stops driving of the motor by the motor driver when abutting is detected by the abutting detection unit.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a control device.

Background Art

[0002] The applicant of the present application has proposed a motor control device described in Patent Document 1. According to this motor control device, the resistance value is read in order to obtain the absolute position information of the shaft portion of a potentiometer that rotates coaxially with the movable shaft of the servo mechanism, and thereby, the stop angle of the servo motor is detected. Due to problems in the manufacturing process, the linearity of the resistance value with respect to the absolute position of rotation of the potentiometer is poor. Therefore, a calibration unit is provided to calibrate the linearity of the resistance value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When calibrating the potentiometer, the movable part of the servo mechanism is brought into contact with the contact object in conjunction with the motor. However, if the motor is driven until the movable part contacts the contact object and the torque reaches the limit value, it is not preferable because the movable part or the contact object may be deformed. An object of the present disclosure is to provide a control device capable of suppressing deformation of the movable part or the contact object as much as possible.

Means for Solving the Problems

[0005] According to the invention described in claim 1, the control system comprises a motor driver, a servo mechanism, a potentiometer, and a calibration calculation unit. The motor driver drives the motor. The servo mechanism has a movable shaft that is linked to the rotation of the motor and a movable part that allows the motor to move until the torque applied to the motor reaches a limit value. The potentiometer acquires a resistance value linked to the movable shaft of the movable part for detecting the absolute position of the movable part of the servo mechanism. The calibration calculation unit calibrates the resistance value of the potentiometer based on the motor current and the resistance value of the potentiometer.

[0006] The motor current detection unit operates on a positive power supply voltage and detects the motor current. The contact detection unit determines that contact has occurred between the movable part and the object to be contacted when the motor current exceeds a predetermined current threshold, so as not to reach the torque applied to the motor when the motor driver rotates the motor in a predetermined direction.

[0007] The controller stops the motor driver's operation based on the detection result of the contact detection unit. According to the invention described in claim 1, the controller stops the motor's operation by the motor driver when contact is detected by the contact detection unit. Therefore, the amount of deformation of the movable part of the servo mechanism or the object it comes into contact with can be limited to less than or equal to the amount of deformation caused by the motor's torque when a current of the current threshold is flowed through the motor. This makes it possible to suppress deformation of the movable part or the object it comes into contact with as much as possible.

[0008] Also, Claim 1 According to the described invention, the motor current consists of a steady current proportional to the torque of the movable shaft, superimposed with surge pulses generated when the motor brushes contact or do not contact the commutator. The motor current changes such that the steady current increases in the positive direction when it changes in the initial stages of reverse starting, depending on the torque during reverse starting of the motor. When the effect of the repulsive force when the movable part separates from the object it is in contact with becomes greater than the effect of the torque during reverse starting of the motor, the motor current has the characteristic of changing to a negative value, including the superimposed surge pulses. The motor current detection unit includes a surge detection unit that detects when the surge pulse reaches a predetermined positive threshold.

[0009] The calibration calculation unit calculates the motor's rotational speed from the surge detection unit's detection result, calculates the ideal resistance value of the potentiometer which is proportional to the mechanical angle of the movable shaft from the rotational speed, and is configured to calibrate the resistance value detected by the potentiometer using the ideal resistance value.

[0010] For example, if the effect of the repulsive force when the movable part separates from the object it is in contact with becomes greater than the effect of the torque when the motor reverses and starts, the superimposed surge pulse also has the characteristic of changing to a negative value. For this reason, if the superimposed surge pulse does not reach the positive threshold of the surge detection unit, the surge pulse cannot be detected. Even if the calibration calculation unit calculates the motor rotation speed from the detection result of the surge detection unit, it will not be able to detect the motor rotation speed accurately, and even if the ideal resistance value of the potentiometer, which is proportional to the mechanical angle of the movable shaft, is calculated from the rotation speed, it will not be calculated accurately.

[0011] Therefore, 1 According to the described invention, the contact detection unit detects whether the movable part and the object to be contacted are in contact when a current threshold is set such that the surge pulse superimposed on the motor current reaches a positive threshold value. Therefore, even when the motor reverses and starts up, the effect of the repulsive force when the movable part separates from the object to be contacted is less than or equal to the effect of the torque when the motor reverses and starts up, and the motor current changes within a range of positive values ​​of at least zero for the superimposed surge pulse, and reaches a positive threshold value when the surge pulse is detected.

[0012] Claim 1 According to the described invention, since the surge pulse reaches a positive threshold, the surge pulse can be accurately detected. Therefore, the calibration calculation unit can detect the motor rotation speed with the utmost accuracy. The calibration calculation unit can accurately calculate the ideal resistance value of the potentiometer, which is proportional to the mechanical angle of the movable shaft, from the rotation speed, and can calibrate the deviation of the resistance value detected by the potentiometer with the utmost accuracy using the ideal resistance value. The surge detection unit can detect surge pulses that change in the positive and negative directions superimposed on the steady-state output current of the motor by comparing a value corresponding to the motor current with a plurality of different positive threshold values.

[0013] Claim 2 As in the invention described, the surge detection unit may detect a surge pulse that changes in the negative direction and is superimposed on the steady current of the motor output. stomach. Brief Description of the Drawings

[0014] [Figure 1] Schematic diagram showing the internal structure of an air conditioner for a vehicle [Figure 2] Schematic diagram of the door opening / closing mechanism and internal structure diagram of the motor [Figure 3] Diagram schematically showing the control system in the first embodiment [Figure 4] Electrical configuration diagram showing a specific example of the control system [Figure 5] Diagram comparing and showing the motor current change when the motor current reaches the limit value and the motor current change when suppressed to a threshold value below the limit value [Figure 6] Diagram illustrating the comparison result when the surge detection unit compares with a positive threshold value [Figure 7] Diagram explaining the state when the door or stopper is deformed [Figure 8] Flowchart schematically showing the calibration process [Figure 9] Diagram explaining the contact detection method at the stopper located in the reverse rotation direction [Figure 10] Diagram showing the motor current and drive command signal near where the door and stopper contact [Figure 11] Diagram illustrating the resistance values of the potentiometer before and after correction [Figure 12] Diagram explaining the contact detection method for the stopper located in the reverse rotation direction in the second embodiment [Figure 13] Diagram showing the motor current and drive command signal near where the door and stopper contact [Figure 14] Electrical configuration diagram showing a specific example of the control system in the third embodiment [Figure 15] Diagram illustrating the comparison results when the surge detection unit compares with a plurality of positive threshold values [Figure 16] Diagram explaining that the negative direction change of the surge pulse is large [Figure 17] Diagram illustrating the method for detecting contact with a stopper located in the reverse rotation direction according to the fourth embodiment. [Modes for carrying out the invention]

[0015] Several embodiments of the control device will be described below with reference to the drawings. In the embodiments described below, identical or similar components in each embodiment may be denoted by the same or similar reference numerals, and their descriptions may be omitted. In particular, note that when the tens digit and the units digit are the same between different embodiments, it indicates that they are identical or similar components.

[0016] (First Embodiment) The first embodiment will be described with reference to Figures 1 to 11. The vehicle air conditioning unit 1 constitutes a control system for air conditioning installed in a vehicle, and adjusts the temperature inside the vehicle by performing heating, cooling, and dehumidification operations. The air conditioning unit 1 includes a case 2 in which an air path is formed. An interior air inlet 3 and an exterior air inlet 4 are formed in the case 2 as air intake ports.

[0017] In Case 2, a defroster vent 5 is formed on the front windshield of the vehicle to blow conditioned air. In Case 2, a face vent 6 is formed above the front seats to blow conditioned air. In Case 2, a foot vent 7 is formed below the front seats to blow conditioned air.

[0018] The air conditioning unit 1 comprises a blower 11, an evaporator 12, and a heater core 13. The blower 11 circulates air into the case 2. A refrigerant flows through the evaporator 12. The evaporator 12 is used as a heat exchanger to cool the air by generating heat of vaporization when the refrigerant vaporizes. The heater core 13 has high-temperature engine coolant flowing through it and is used as a heat exchanger to heat the surrounding air using the heat from the engine coolant.

[0019] The air conditioning unit 1 is equipped with an internal / external air switching door 14 for opening and closing the internal air inlet 3 and the external air inlet 4. The internal / external air switching door 14 is a door that adjusts the amount of air introduced into the air conditioning case 2 from the internal air inlet 3 and the external air inlet 4, and is also called a flap device. The internal / external air switching door 14 realizes an internal air mode in which conditioned air is circulated inside the vehicle by opening the internal air inlet 3 and closing the external air inlet 4. The internal / external air switching door 14 realizes an external air mode in which conditioned air is taken in from outside the vehicle by closing the internal air inlet 3 and opening the external air inlet 4.

[0020] The air conditioning unit 1 includes an air mixing door 15 for adjusting the temperature of the conditioned air. The air mixing door 15 is installed downstream of the evaporator 12 and upstream of the heater core 13. By controlling the opening of the air mixing door 15, the amount of air heated by passing through the heater core 13 can be adjusted.

[0021] The air conditioning unit 1 includes a defroster door 16, a face door 17, and a foot door 18. The defroster door 16 adjusts whether or not air conditioning is blown out from the defroster outlet 5 and the amount of air blown out. The face door 17 adjusts whether or not air conditioning is blown out from the face outlet 6 and the amount of air blown out. The foot door 18 adjusts whether or not air conditioning is blown out from the foot outlet 7 and the amount of air blown out.

[0022] The air conditioning unit 1 has multiple modes as outlet modes. The defroster door 16, face door 17, and foot door 18 are doors that switch modes, and the defroster door 16, face door 17, and foot door 18 rotate according to the indicated mode.

[0023] The aforementioned internal / external air switching door 14, air mixing door 15, defroster door 16, face door 17, and foot door 18 are all molded from resin. The internal / external air switching door 14 is rotatable within a range from when the internal air inlet 3 is closed to when the external air inlet 4 is closed.

[0024] For example, as schematically shown in Figure 2, the internal / external air switching door 14 abuts against stopper A3 when the internal air inlet 3 is closed, and abuts against stopper A4 when the external air inlet 4 is closed. At this time, the internal / external air switching door 14 is rotatable within the range until the internal air inlet 3 or external air inlet 4 is completely closed. Stoppers A3 and A4 are made of resin and represent the objects that abut against each other as described in this disclosure.

[0025] In addition, the air mixing door 15, defroster door 16, face door 17, and foot door 18 rotate within a range that allows them to be opened and closed from the fully open position until they contact a stopper (not shown). Since these operations are the same as those of the internal / external air switching door 14, they are not illustrated or described. The defroster door 16, face door 17, and foot door 18 may be configured as a single continuous door. For example, a rotary door may be used that rotates a door panel formed in an arc shape to open and close each air outlet.

[0026] Doors 14-18 are configured as movable parts whose door panel angles are adjusted by a servo mechanism 20. The airflow rate changes depending on the angle of each door 14-18. Therefore, it is desirable to control the position of doors 14-18 with the highest possible precision.

[0027] Doors 14-18 are attached to the servo mechanism 20. Figure 2 illustrates a structure in which the internal / external air switching door 14 is attached to the servo mechanism 20 and opens and closes the internal air inlet 3 and the external air inlet 4. In the following, the opening and closing drive of the internal / external air switching door 14 will be explained as an example, and the internal / external air switching door 14 will be abbreviated as "door 14".

[0028] As shown in Figure 2, the servo mechanism 20 includes an actuator 23. The actuator 23 consists of a motor 31, a reduction unit 32, a movable shaft 33, and a potentiometer 34 as shown in Figure 3. The motor 31 is a brushed DC motor or servo motor controlled by the control device 22.

[0029] The motor 31 includes a stator 31b having permanent magnets that function as field poles. The motor 31 includes a rotor 31c with an air gap on the inner circumference of the field poles. The motor 31 includes a commutator 31d on the rotor 31c. The commutator 31d is also called a commutator.

[0030] The motor 31 is equipped with brushes 31e that contact the commutator 31d to supply current to the commutator 31d. The motor 31 is configured such that the commutator 31d in contact with the brushes 31e is constantly switched when it is rotated. The door 14, which is a movable part, has a movable shaft 33 integrated into it. The movable shaft 33 is linked to the rotation of the rotor 31c of the motor 31, and the door 14 is movable until the torque applied to the motor 31 reaches its limit.

[0031] The reduction gear 32 is composed of a worm gear 32a and a gear 32b, and reduces the rotation of the motor 31. The reduction gear 32 can adjust the torque and rotational speed required for the actuator 23. The movable shaft 33 is rotatably supported with respect to the fixed member 33a. The movable shaft 33 is linked to the reduction gear 32 and rotatably supports the door 14. As a result, the motor 31 can drive the movable shaft 33 to a desired rotational position by rotationally driving it via the reduction gear 32.

[0032] The rotation angle of the movable shaft 33 and the absolute position of the motor 31 depend on and are proportional to a predetermined damping ratio. For example, the rotation angle of the movable shaft 33 is less than the rotation angle of the motor 31.

[0033] The potentiometer 34 shown in Figure 3 is provided for detecting the absolute position of the door 14 by the servo mechanism 20 and is a device for measuring the rotational position of the movable shaft 33 of the door 14. The potentiometer 34 is a variable resistor whose resistance value changes according to the rotational position of the movable shaft 33 of the door 14, and the resistance value is acquired as a detected value related to the rotational position of the movable shaft 33.

[0034] A predetermined voltage is applied to the potentiometer 34, and the change in the resistance value of the potentiometer 34 can be obtained as a change in voltage. By using the potentiometer 34, the current rotational position of the movable shaft 33 can be measured. Compared to rotational position detection sensors such as encoders, the potentiometer 34 is low-cost and easy to use for detecting rotational position.

[0035] The potentiometer 34, for example, has a configuration comprising a resistive film continuously provided along the circumferential direction with respect to the rotation axis coaxial with the output shaft portion 31a of the motor 31 shown in Figure 2, and a connecting terminal that slides on the resistive film. By applying a voltage to the resistive film of the potentiometer 34, a stepwise voltage drop is induced across the resistive film. This allows the position on the resistive film that the connecting terminal is in contact with to be detected by the magnitude of the voltage of the potentiometer 34. The rotational position of the connecting terminal can be obtained from the magnitude of the voltage of the potentiometer 34.

[0036] The air conditioning system 1 includes a control device 22 as shown in Figure 3. A specific example of the control device 22 is shown in Figure 4. The control device 22 includes a controller 40, a motor driver 41, a motor current detection unit 42, and a calibration calculation unit 46.

[0037] The motor driver 41, although not shown, is composed of, for example, an H-bridge circuit that operates on a positive power supply voltage, and drives the motor 31 based on a pulsed drive command signal S11 input from the controller 40. The motor driver 41 switches between the driven state and the non-driven state of the motor 31 by controlling the timing of applying the positive DC power supply voltage to the motor 31. The motor driver 41 drives the motor 31 while the drive command signal S11 is provided, and stops driving the motor 31 when the drive command signal S11 is not provided.

[0038] The controller 40 of the control device 22 controls the rotation of the motor 31 by the motor driver 41 based on position information obtained using the potentiometer 34. The position information is absolute position information indicating the rotational position of the potentiometer 34, which is linked to the movable shaft 33. However, although the potentiometer 34 has a tolerance as a component, there is a deviation between the ideal value and the actual value.

[0039] For example, variations in the resistive film of the potentiometer 34, which is a variable resistor, will cause the characteristic map showing the relationship between voltage and rotational position to deviate from an ideal characteristic map. Therefore, in order to determine the position of the movable shaft 33 more accurately, it is important to compensate for variations in the resistance value of the potentiometer 34.

[0040] The motor current detection unit 42 is composed of a circuit that operates on a positive power supply voltage and detects the current supplied to the motor 31. The motor current detection unit 42 includes a surge detection unit 43 and a contact detection unit 44.

[0041] The surge detection unit 43 detects fluctuations in the current of the motor 31. More specifically, the surge detection unit 43 detects surge pulses P by detecting changes that occur when the contact or non-contact between the brushes 31e and the commutator 31d of the motor 31 switches.

[0042] The contact detection unit 44 is used as a wall contact detection unit to determine whether the door 14 is in contact with or about to contact the stopper A4. The contact detection unit 44 is configured to detect a contact state, an imminent contact state, or a non-contact state by detecting the current of the motor 31. The contact detection unit 44 outputs a contact detection signal S13 to the controller 40.

[0043] The controller 40 receives a pulse signal S12, which is a pulse of a predetermined width obtained by a one-shot circuit (not shown) or the like, from the surge pulse P generated by the surge detection unit 43. The controller 40 detects rotational information such as the amount of rotation and rotational speed of the motor 31 from the pulse signal S12, for example, through a counter 40a. Based on this rotational information, the controller 40 controls the amount of rotation and rotational direction of the motor 31 by inputting a drive command signal S11 to the motor driver 41 so that the rotational position of the motor 31 matches a target stop position stored in memory 40b, for example, a register.

[0044] While the motor 31 is rotating, the contact between the brush 31e and the commutator 31d is constantly switched. The surge detection unit 43 detects the surge pulse P generated when the contact between the brush 31e and the commutator 31d is switched, thereby obtaining the rotational speed of the motor 31 from the position where the detection started. The rotational speed of the motor 31 is linked to the amount of rotational movement of the movable shaft 33. Therefore, when the surge detection unit 43 detects the surge pulse P, the mechanical angle of rotation of the movable shaft 33 can be measured. The ideal resistance value of the potentiometer 34 is proportional to the mechanical angle of the movable shaft 33.

[0045] The calibration calculation unit 46 is configured to calibrate the variation in the resistance value of the potentiometer 34. The calibration calculation unit 46 is configured by a microcontroller, similar to the controller 40. The calibration calculation unit 46 may be configured as part of the functions of the controller 40, but as shown in Figures 3 and 4, it may be configured by separate hardware from the controller 40 and operated in synchronization with the controller 40. To make the functions of this embodiment easier to understand, the controller 40 and the calibration calculation unit 46 are shown separately in the diagram. As mentioned above, the potentiometer 34 deviates from its ideal value, so the calibration calculation unit 46 calibrates the resistance value of the potentiometer 34 based on the detected current by the motor current detection unit 42.

[0046] When the calibration calculation unit 46 calibrates the resistance value of the potentiometer 34, the controller 40 uses the motor driver 41 to change the rotation angle of the movable shaft 33 to a reference position so that the door 14 comes into contact with one of the stoppers A4. After that, the controller 40 reverses the rotation of the motor 31 to change the rotation angle of the movable shaft 33 so that the door 14 comes into contact with the other stopper A3.

[0047] The calibration calculation unit 46 calibrates the resistance value detected by the potentiometer 34 based on the detection results obtained by the motor current detection unit 42, which detects the change in the motor current 31 between the rotation angles of these movable shafts 33. More specifically, the calibration calculation unit 46 calculates the rotation speed of the motor 31 by counting the surge pulses P of the surge detection unit 43, and calculates the ideal resistance value of the potentiometer 34 from the mechanical angle of the movable shaft 33 which is linked to that rotation speed. The calibration calculation unit 46 uses this ideal resistance value to calibrate the resistance value detected by the potentiometer 34.

[0048] <Specific example of the configuration in Figure 3> A specific example of the configuration shown in Figure 3 is illustrated in Figure 4. The motor current detection unit 42 consists of a resistor 50 that converts the current of the motor 31 into a voltage, a surge detection unit 143, and an amplifier 144. The surge detection unit 43 shown in Figure 3 can be composed of the surge detection unit 143. The surge detection unit 143 is configured by cascading a bandpass filter 51, an amplifier 52, and a comparator 53, and outputs a pulse signal S12 after the output of the comparator 53 is waveform-shaped by a one-shot circuit (not shown) or the like.

[0049] The bandpass filter 51 here is composed of a differentiating circuit that attenuates the component of the relatively low-frequency steady-state current TE from the motor 31 current detected by the resistor 50, and has high-pass characteristics. For this reason, it may be composed of a high-pass filter rather than a bandpass filter 51. The amplifier 52 amplifies the component of the surge pulse P and inputs it to the comparator 53. The comparator 53 is configured using a positive power supply voltage VCC.

[0050] The comparator 53 receives a predetermined positive threshold value + Vref as input and compares it with the output of the amplifier 52 to detect the timing when the surge pulse P reaches the predetermined positive threshold value + Vref. The timing detected at this time may be the timing when the positive threshold value + Vref changes in the positive direction or the timing when it changes in the negative direction. In this embodiment, an example in which the positive threshold value + Vref is set to detect a change in the positive direction will be described. The surge detection unit 143 outputs a pulse signal S12 after binarizing based on the predetermined positive threshold value + Vref and shaping the waveform using a one-shot circuit or the like (not shown).

[0051] The contact detection unit 44 shown in Figure 3 can be configured with an amplifier 144 and an A / D converter 40c within the controller 40, as shown in Figure 4. The amplifier 144 analogously amplifies a voltage proportional to the current of the motor 31 and feeds it back to the controller 40. The controller 40 is composed of a control logic circuit equipped with a counter 40a, registers, volatile and non-volatile memories 40b, and an A / D converter 40c. The controller 40 digitally converts the output analog voltage of the amplifier 144. The controller 40 determines whether the door 14 has come into contact with the stopper A4 or is about to come into contact with it by comparing the digital value with a predetermined threshold.

[0052] <Description of problems related to this embodiment> Figure 5 shows the change in the steady-state current TE of the motor 31 detected by the motor current detection unit 42, along with a comparative example. The current change in this embodiment is shown by a solid line, and the current change in the comparative example is shown by a dashed line.

[0053] Figure 6 shows a waveform including a surge pulse P within a portion of the current Ta shown in Figure 5. The current of the motor 31 can be separated into the steady-state current TE shown in Figure 5 and the surge pulse P shown in Figure 6. The steady-state current TE is a current value proportional to the torque applied to the movable shaft 33. The surge pulse P is superimposed on the steady-state current TE and is a surge that occurs when the brush 31e makes contact with and does not make contact with the commutator 31d in response to the pulsating ripple component.

[0054] As shown in Figure 7, when calibration of the resistance value of the potentiometer 34 is started, the motor 31 rotates and the door 14 rotates in the forward direction and contacts the stopper A4. The forward direction corresponds to the predetermined direction in this disclosure. When the door 14 contacts the stopper A4, the torque applied to the door 14 increases, and therefore the current of the motor 31 also increases. However, as shown in timing t2 in Figure 5, when the current reaches its limit value It1, which is expected to be the limit value at which the torque applied to the motor 31 reaches its limit, the motor 31 stops rotating.

[0055] In such cases, since the door 14 and stopper A4 are made of resin, a physical force is applied to the door 14 and stopper A4 due to the torque applied to the door 14, as shown by the arrow in Figure 7. If this force is strong, deformation will occur in the door 14 or stopper A4.

[0056] When the motor 31 reverses its driving direction from the position where this deformation occurred, the steady-state current TE changes such that, when the motor 31 changes during the reversal start, it increases in proportion to the torque at the time of the reversal start in the direction of the positive value.

[0057] When the door 14 separates from the stopper A4, it generates a strong repulsive force, which strongly affects the movable shaft 33. From timing t2 onward in Figure 5, when the motor 31 is reversed to the opposite direction of forward rotation, the motor current detection unit 42 detects the change in current based on the repulsive force in addition to the steady current TE mentioned above. Therefore, the motor current detection unit 42 detects a current that depends on the torque of the motor 31 when it is reversed, as well as the repulsive force when the door 14 repels the stopper A4.

[0058] At timing t2 in Figure 5, when the motor 31 applies force to press the door 14 against the stopper A4 up to its torque limit, the effect of the repulsive force when the door 14 separates from the stopper A4 becomes greater than the effect of the motor 31's torque during reverse start. At this time, the motor current detection unit 42 detects a current that initially changes to positive from timing t3, but then inputs a current that changes from positive to negative, as shown by the dashed line in Figure 5 representing the current change during period T.

[0059] In other words, when the door 14 is pushed against the stopper A4, energy is applied due to the deformation of the resin. If the effect of this rebound energy becomes greater than a predetermined value, the current of the motor 31 changes from a positive value to a negative value, and the motor current detection unit 42 receives this current as input.

[0060] If the motor current detection unit 42 is configured with a circuit that operates on a positive power supply voltage VCC, it will be unable to detect the steady-state current TE, which changes from a positive value to a negative value, and the surge pulse P superimposed on the steady-state current TE. In such a case, it will be impossible to accurately detect the rotational speed of the motor 31, which is undesirable.

[0061] <Operation of this embodiment> Therefore, in this embodiment, a predetermined current threshold It, lower than the limit value It1, is stored and set in the non-volatile memory (memory 40b) of the controller 40 so that the torque applied to the motor 31 does not reach the limit value. The controller 40 uses the current threshold It to stop driving the motor driver 41 at timing t1 in Figure 5. The current threshold It should be set to a degree that allows detection of surge pulses P that change in the positive or negative direction superimposed on the steady current TE. Here, a value obtained by repeating experiments and simulations is set in advance.

[0062] The controller 40 receives an analog input of a voltage corresponding to the current of the motor 31 amplified by the amplifier 144, and determines whether the digital value converted digitally by the A / D converter 40c exceeds the current threshold It. The controller 40 considers that the door 14 and the stopper A4 will come into contact when the current of the motor 31 exceeds the current threshold It. In this case, the controller 40 stops the motor 31 using the motor driver 41. This minimizes deformation of the door 14 or the stopper A4.

[0063] <Calibration process> Next, the calibration process for the resistance value of the potentiometer 34 will be explained, including Figure 8. The controller 40 drives the motor driver 41 to drive the motor 31 by outputting a drive command signal S11 at S1 in Figure 8. This causes the servo mechanism 20 to rotate the door 14 in the forward direction to the reference position.

[0064] As described above, the controller 40 changes the rotational position of the movable shaft 33 until the current of the motor 31 reaches the current threshold It. When the current of the motor 31 reaches the current threshold It, it is considered that the door 14 and the stopper A4 have come into contact. As a result, as shown in S2 of Figure 8, the position just before the door 14 and stopper A4 come into contact can be determined, and the movable shaft 33 can be rotated to stop. In S2 of Figure 8, even if the door 14 or stopper A4 deforms, the movable shaft 33 may be rotated to stop in a way that limits the amount of deformation to an acceptable range.

[0065] Next, the controller 40 outputs a drive command signal S11 at timing t3 in Figures 5 and 9, thereby starting the door 14 to rotate in the reverse direction. At S4 in Figure 8, the calibration calculation unit 46 records the timing of the surge pulse P detected by the surge detection unit 43 in its internal memory 40b. The calibration calculation unit 46 acquires the resistance value of the potentiometer 34 in synchronization with one or more cycles of that timing and records it in its internal memory 40b. The number of surge pulse P occurrences changes in conjunction with the rotation speed of the motor 31. As a result, the calibration calculation unit 46 can associate the number of surge pulse P occurrences, i.e., the rotation speed of the motor 31, with the resistance value of the potentiometer 34 and store them in the memory 40b.

[0066] As shown in Figure 9, which illustrates the current change in motor 31, the current in motor 31 temporarily increases with the temporary increase in torque during reverse starting, but decreases as rotation continues. At this time, as explained earlier, since the motor 31 is stopped when the current reaches the current threshold It, the effect of the repulsive force of stopper A4 is small, and the steady-state current TE of motor 31 changes in a way that it does not go from a positive value to a negative value. The motor current detection unit 42 can detect the steady-state current TE which remains at a positive value. Here, we show a form in which the steady-state current TE remains at a positive value, but strictly speaking, it is sufficient for the surge pulse P superimposed on the steady-state current TE by the surge detection unit 43 to reach the positive threshold + Vref and be detected, so it is also acceptable for the steady-state current TE to momentarily reach a negative value.

[0067] As shown in Figure 6, the bandpass filter 51 of the surge detection unit 43 removes the steady-state current TE component and extracts the surge pulse P superimposed on the steady-state current TE component. The amplifier 52 amplifies the pulse component, and the comparator 53 compares the surge pulse P with a positive threshold value + Vref and outputs the result as a rectangular pulse signal S12. This allows surge pulses P to be detected without being missed.

[0068] As shown in Figure 6, surge pulses P are pulses that protrude in both the positive and negative directions of the steady-state current TE. By appropriately setting the threshold value + Vref, surge pulses P that change in the positive direction can be detected. Furthermore, by changing the comparison criterion of the comparator 53, surge pulses P that change in the negative direction can also be detected.

[0069] After the steady current TE decreases, when the door 14 contacts the stopper A3 on the reverse rotation side, the torque applied to the motor 31 increases, and the steady current TE of the motor 31 also increases again during period T1 in Figure 9. The controller 40 detects whether the door 14 is considered to have contacted the stopper A3 on the reverse rotation side by detecting whether the current of the motor 31 detected through the contact detection unit 44 has risen to a predetermined current threshold It2.

[0070] When the controller 40 detects that the door 14 has come into contact with the stopper A3 at timing t4 in Figure 9, it stops the output of the drive command signal S11, stops the motor driver 41, and stops the motor 31. Up to this point, the calibration calculation unit 46 can store the characteristics of the resistance value of the potentiometer 34 before correction in memory 40b, linked to the rotational speed of the motor 31, as shown in the upper left diagram of Figure 11.

[0071] Figure 10 shows a magnified view of the behavior of the motor 31 near the timing when it is stopped. When the current of the motor 31 rises to or above the current threshold It2 at timing t4 in Figure 10, the controller 40 will stop outputting the drive command signal S11 at timing t5 after the processing time of the air conditioning unit 1.

[0072] The calibration calculation unit 46 calculates the ideal resistance value from the time the drive command signal S11 is activated until the output of the drive command signal S11 is stopped. Since the rotation angle of the door 14 is limited to between stopper A4 and stopper A3, the change in the mechanical angle of the movable shaft 33 is also limited.

[0073] The calibration calculation unit 46 calculates the number of rotations of the output shaft portion 31a of the motor 31 from the initial rotation position to the final rotation position within the mechanical angle limit range of the movable shaft 33. From the number of rotations calculated in S6 of Figure 8, the calibration calculation unit 46 calculates the ideal resistance value of the potentiometer 34, which is proportional to the mechanical angle of the movable shaft 33. As shown in the upper right figure of Figure 11, the ideal resistance value can be derived as a linear characteristic that changes linearly from the initial rotation position to the final rotation position of the movable shaft 33.

[0074] The calibration calculation unit 46 calibrates the resistance value detected by the potentiometer 34 using the ideal resistance value. In this process, the calibration calculation unit 46 calculates a correction value from the difference between the ideal resistance value and the measured resistance value of the potentiometer 34 in S7 of Figure 8. Since the calibration calculation unit 46 has measured the resistance value of the potentiometer 34, it can calculate how much it deviates from the linear ideal resistance value. Then, in S8 of Figure 8, the calibration calculation unit 46 maps the deviation value from the ideal resistance value to the correction value by storing it in the memory 40b.

[0075] As a result, the calibration calculation unit 46 can calibrate the linearity by adding or subtracting a correction value to the measured resistance value of the potentiometer 34. The calibration calculation unit 46 may also store the resistance value obtained by adding or subtracting the correction value in the memory 40b. Since the calibration calculation unit 46 can determine the correction value of the resistance value of the potentiometer 34, the calibrated resistance value with respect to the rotational speed of the motor 31 will have a linear characteristic that is generally close to the ideal resistance value. As a result, when the controller 40 actually uses the resistance value of the potentiometer 34, it can read the calibrated correction value or the corrected resistance value from the memory 40b and use it, thereby determining the rotational position of the motor 31 as accurately as possible from the corrected resistance value of the potentiometer 34.

[0076] <Summary of the First Embodiment> As described above, according to this embodiment, the contact detection unit 44 determines that the door 14 and the stopper A4 come into contact when the current of the motor 31 exceeds a predetermined current threshold It, which is set so that the torque applied to the motor 31 does not reach a limit value. The controller 40 stops the motor 31 from driving using the motor driver 41 when the contact detection unit 44 determines that contact has occurred.

[0077] The current threshold It is set to less than the current threshold It1, which is determined from the torque limit of the motor 31. Therefore, the amount of deformation of the door 14 and stopper A4 can be limited to the amount of deformation caused by the torque of the motor 31 when the current threshold It is passed through the motor 31. As a result, deformation of the door 14 or stopper A4 can be minimized. Alternatively, the current threshold It may be set so that the amount of deformation of the door 14 and stopper A4 is adjusted to zero.

[0078] <Comparative Example> For example, if the effect of the repulsive force when the door 14 separates from the stopper A4 becomes greater than the effect of the torque when the motor 31 reverses and starts, the current of the motor 31 has the characteristic of changing to a negative value, including the superimposed surge pulse P, as shown by the dashed line for period T in Figure 5. As a result, the surge pulse P superimposed on the current of the motor 31 does not reach the positive threshold of the surge detection unit 143, and the surge pulse P cannot be detected. In this case, even if the calibration calculation unit 46 calculates the rotational speed of the motor 31 from the detection result of the surge detection unit 143, it will not be able to detect the motor rotational speed with accuracy. Even if the calibration calculation unit 46 calculates the ideal resistance value of the potentiometer 34, which is proportional to the mechanical angle of the movable shaft 33, from the rotational speed, it will not be able to calculate it with accuracy.

[0079] <Effects of this embodiment> According to this embodiment, the current threshold It of the motor 31 is set such that the surge pulse P included in the current of the motor 31 reaches at least a positive threshold + Vref when detected. For example, the current threshold It of the motor 31 is set so that the current does not become negative when the rotation axis 33 of the servo mechanism 20 is rotated in the reverse direction and the door 14 separates from the stopper A4. The contact detection unit 44 determines or detects whether the door 14 and the stopper A4 are in contact in this state. Therefore, even when the motor 31 is started in reverse, the effect of the repulsive force when the door 14 separates from the stopper A4 is less than or equal to the effect of the torque of the motor 31 when it is started in reverse. The current of the motor 31 changes to at least a positive value range of zero or greater for the superimposed surge pulse P, and reaches a positive threshold when the surge pulse P is detected.

[0080] As illustrated above, the surge detection unit 143 is equipped with a comparator 53 that operates with a positive power supply voltage VCC and detects when a surge pulse P reaches a predetermined positive threshold value + Vref. Therefore, surge pulses P superimposed on the steady current TE of the motor 31 can be detected without fail. This allows the rotational speed of the motor 31 to be detected as accurately as possible. The calibration calculation unit 46 can accurately calculate the ideal resistance value of the potentiometer 34, which is proportional to the mechanical angle of the movable shaft 33, from the rotational speed, and can calibrate the deviation of the resistance value detected by the potentiometer 34 as accurately as possible using the ideal resistance value. As a result, the accuracy of the calibration can be improved.

[0081] <Examples of the calibration process> In the previous example, the resistance value of the potentiometer 34 was recorded in synchronization with the timing of the surge pulse P in S4 of Figure 8, but this is not the only option. The timing for acquiring the resistance value of the potentiometer 34 does not need to be synchronized with the timing of the surge pulse P. If the calibration calculation unit 46 has a built-in timer, the timing for acquiring the resistance value of the potentiometer 34 may be set periodically using the timer. In other words, the timing for acquiring the resistance value of the potentiometer 34 may be set independently of the surge pulse P.

[0082] In this case as well, the calibration calculation unit 46 performs processing in the same manner as in Figure 8, but in S4, it is preferable to perform the processing as follows. The calibration calculation unit 46 calculates the rotational speed of the motor 31 when the door 14 rotates from stopper A4 to stopper A3, stepwise as the relative position from the moment the door 14 started moving from the initial stopper A4 position. The calibration calculation unit 46 obtains time information from the position where detection began using a built-in timer, and stores in memory 40b the rotational speed of the motor 31 detected at which timing, linked to the time information.

[0083] The calibration calculation unit 46 acquires the resistance value of the potentiometer 34 as absolute position information in step order, in parallel with the rotational speed information of the motor 31. The calibration calculation unit 46 acquires time information from the position where detection started using a built-in timer, and stores in memory 40b the timing at which the resistance value of the potentiometer 34 was detected, linked to the time information.

[0084] The calibration calculation unit 46 calculates the ideal resistance value in S5-S6 of Figure 8, and then in S7-S8 calculates a correction value from the difference between the ideal resistance value and the measured value, and records it in the memory 40b. This allows calibration to be performed in the same manner as in the above embodiment. Therefore, in S4 of Figure 8, the resistance value of the potentiometer 34 can be recorded without detecting the surge pulse P.

[0085] (Second Embodiment) A second embodiment will be described with reference to Figures 12 and 13. In the first embodiment, the change in the current of the motor 31 reached a current threshold It2, which was used to detect that the door 14 had come into contact with the stopper A3, i.e., to consider it as contact. However, the embodiment is not limited to this.

[0086] As shown in Figure 12, the derivative of the current of the motor 31 may be calculated, and when the change in this derivative reaches the current derivative threshold It3, it may be detected that the door 14 has come into contact with the stopper A3, or in other words, it may be considered that contact has occurred.

[0087] Figure 13 shows a magnified view of the behavior of the motor 31 near the timing when it is stopped. When the current of the motor 31 rises to or above the current derivative threshold It3 at timing t6 in Figure 13, the controller 40, after the system processing time, stops outputting the drive command signal S11 at timing t7. This embodiment also produces the same effects as the previously described embodiment.

[0088] (Third embodiment) A third embodiment will be described with reference to Figures 14 to 16. The air conditioning unit 301 shown in Figure 14 includes a control device 322. The control device 322 includes a motor current detection unit 342, which includes a plurality (for example, two) of surge detection units 343a and 343b. The surge detection units 343a and 343b each include a bandpass filter 51, an amplifier 52, and a comparator 53, respectively. The calibration calculation unit 346 includes a digital filter function. The digital filter is a filter provided to recognize a surge pulse P as a single pulse even if the surge pulse P changes in the positive and negative directions at approximately simultaneous timings. The other configurations of the air conditioning unit 301 are the same except for the setting values ​​of the thresholds +Vref1 and +Vref2 of the comparator 53, so their description will be omitted.

[0089] The thresholds +Vref1 and +Vref2 have the relationship +Vref1 > +Vref2. As shown in Figure 15, the thresholds +Vref1 and +Vref2 are set as thresholds for detecting surge pulses P contained in the output of amplifier 52. As shown in Figure 16, each time the commutator 31d changes between contact and non-contact with the brush 31e, the current in motor 31 changes direction. When the brush 31e and commutator 31d separate and no current flows, the current decreases instantaneously, and the change in the motor 31 current becomes larger in the negative direction.

[0090] While the motor 31 with brushes 31e is continuously rotating, comparing the period during which the brushes 31e and commutator 31d are in contact with each other with the period during which the brushes 31e are separated from the commutator 31d, the period during which they are separated is overwhelmingly shorter. Therefore, the slope of the current in the motor 31 is greater when it changes in the negative direction than when it changes in the positive direction.

[0091] The bandpass filter 51 shown in Figure 14 attenuates the steady-state current TE component and passes the slope of this current as a surge pulse P through a differentiating circuit, and the amplifier 52 amplifies the surge pulse P. At this time, surge pulses P that change in the negative direction are more strongly emphasized and output. Therefore, it is considered that detecting surge pulses P that change in the negative direction is easier than detecting surge pulses P that change in the positive direction.

[0092] In the configuration of this embodiment, as shown in Figure 15, the comparator 53 of the surge detection unit 343a detects surge pulses P that change in the positive direction superimposed on the steady current TE by comparing the output of the amplifier 52 with a first positive threshold + Vref1. The comparator 53 of the surge detection unit 343b detects surge pulses P that change in the negative direction superimposed on the steady current TE by comparing the output of the amplifier 52 with a second positive threshold + Vref2. Since the surge detection unit 343b detects surge pulses P that change in the negative direction, it can detect surge pulses P with greater reliability. The calibration calculation unit 46 recognizes surge pulses P as a single pulse even if they change in the positive and negative directions at approximately the same timing due to the function of the digital filter. As a result, the timing of the occurrence of surge pulses P can be detected with greater reliability.

[0093] According to this embodiment, the surge detection units 343a and 343b compare a value corresponding to the current of the motor 31 with a plurality of mutually different positive thresholds +Vref1 and +Vref2. The surge detection units 343a and 343b detect surge pulses P that change in the positive and negative directions superimposed on the steady current TE of the output of the motor 31. Therefore, by comparing the surge detection units 343a and 343b with both positive thresholds +Vref1 and +Vref2, respectively, the reliability of detecting surge pulses P can be improved. For example, even if the surge pulse P is offset in the positive or negative direction, or if its amplitude is reduced due to some influence, it is possible to detect at least one of the surge pulses P that fluctuates in the positive or negative direction as much as possible. As a result, the rotational speed of the motor 31 can be calculated as accurately as possible, and the accuracy of calibration can be improved.

[0094] (Fourth Embodiment) A fourth embodiment will be described with reference to Figures 4 and 17. The counter 40a shown in Figure 4 is connected to the output of the one-shot pulse circuit downstream of the surge detection unit 43. The calibration calculation unit 46 determines whether the door 14 has come into contact with the stopper A3 based on the count result of the counter 40a and the output of the surge detection unit 43.

[0095] As shown in Figure 17, after the controller 40 starts outputting the drive command signal S11, when the surge detection unit 43 detects a surge pulse P, the counter 40a counts the pulse signal S12 of the surge pulse P. The calibration calculation unit 46 inputs the count value of the counter 40a and detects when the count value reaches a predetermined count threshold, thereby detecting the timing when the door 14 contacts the stopper A3. Even with this configuration, the rotational speed of the motor 31 can be calculated as accurately as possible, and the accuracy of the calibration of the resistance value of the potentiometer 34 can be improved.

[0096] (Other embodiments) The present invention is not limited to the embodiments described above, and can be implemented with various modifications and is applicable to various embodiments without departing from its essence. As explained in the modified example above, if it is not necessary to detect surge pulses P, the motor 31 may be a brushless motor, not just a motor with brushes 31e.

[0097] The controller 40 may also sweep a current threshold It within a predetermined range to dynamically change and learn the current threshold It for detecting when the door 14 is deemed to be in contact with the stopper A4, and then automatically set it. In this case, the controller 40 may determine whether the surge pulse P superimposed on the steady current TE has changed to a positive threshold + Vref1 or a positive threshold + Vref2, and then derive and automatically set a current threshold It that satisfies the determination condition.

[0098] While doors 14-18 were used as the movable parts, this can be applied to any movable body other than doors 14-18, and can be applied to various control systems other than air conditioning units 1, 301, and 401.

[0099] Although the present invention has been described in accordance with the embodiments described above, it is understood that the present invention is not limited to such embodiments or structures. The present invention also encompasses various modifications and variations within the equivalence range. In addition, various combinations and forms, as well as other combinations and forms that include one, more, or fewer elements, fall within the scope and conceptual range of the present invention. [Explanation of Symbols]

[0100] In the drawing, 1, 301, and 401 represent the air conditioning unit (control system), 14 is the internal / external air switching door (movable part), 15 is the air mixing door (movable part), 16 is the defroster door (movable part), 17 is the face door (movable part), 18 is the foot door (movable part), 20 is the servo mechanism, 22 and 322 are the control devices, 31 is the motor, 33 is the movable shaft, 34 is the potentiometer, 40 is the controller, 41 is the motor driver, 42 is the motor current detection unit, 44 is the contact detection unit, 144 is the amplifier (contact detection unit), 40a is the A / D converter (contact detection unit), 46 is the calibration calculation unit, and A3 and A4 are the stoppers (objects to be contacted).

Claims

1. A control device comprising a motor driver (41) for driving a motor, a servo mechanism (20) having a movable shaft (33) linked to the rotation of the motor and movable parts (14-18) that allow the torque applied to the motor to move until it reaches a limit value, a potentiometer (34) for acquiring a resistance value linked to the movable shaft (33) of the movable part for detecting the absolute position of the movable part of the servo mechanism, and a calibration calculation unit (46) for calibrating the resistance value of the potentiometer based on the motor current and the resistance value of the potentiometer, wherein A motor current detection unit (42) operates with a positive power supply voltage and detects the current of the motor, A contact detection unit (44; 144, 40a) rotates the motor in a predetermined direction using the motor driver and determines that contact has occurred when the current of the motor exceeds a predetermined current threshold (It) so that the torque applied to the motor does not reach the limit value, and the movable part and the object to be contacted are deemed to be in contact. The system includes a controller (40) that stops the motor driver's operation based on the detection result of the contact detection unit, The controller stops the motor drive by the motor driver when contact is detected by the contact detection unit. The current of the motor consists of a steady current proportional to the torque of the movable shaft, superimposed with surge pulses generated when the motor brushes come into contact with or do not come into contact with the commutator. The current of the motor changes such that the steady-state current increases in the positive direction when it changes in the initial stages of the motor's reverse start, depending on the torque during the motor's reverse start, and changes to a negative value, including the superimposed surge pulse, when the effect of the repulsive force when the movable part separates from the object it is in contact with becomes greater than the effect of the torque during the motor's reverse start. The motor current detection unit includes a surge detection unit (43) that detects when the surge pulse reaches a predetermined positive threshold value (+Vref; +Vref1, +Vref2), The calibration calculation unit is configured to calculate the rotational speed of the motor from the detection result of the surge detection unit, calculate the ideal resistance value of the potentiometer which is proportional to the mechanical angle of the movable shaft from the rotational speed, and calibrate the resistance value detected by the potentiometer using the ideal resistance value. The contact detection unit detects whether the movable part and the object to be contacted are in contact when the current threshold is set such that the surge pulse superimposed on the motor current reaches the positive threshold, The surge detection units (343a, 343b) are control devices that detect surge pulses that change in the positive and negative directions superimposed on the steady-state output current of the motor by comparing a value corresponding to the motor current with a plurality of mutually different positive thresholds (+Vref1, +Vref2).

2. The control device according to claim 1, wherein the surge detection unit (343b) detects the surge pulse that changes in the negative direction and is superimposed on the steady current of the output of the motor.

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