Abstract:
A driving control device for an actuator comprises a driving device to drive an actuator having an electric motor ( 30 ) and a driving control device ( 60 ) to control the rotation of the electric motor ( 30 ) by controlling the driving device. The driving control device includes an H bridge circuit constructed by four switching semiconductor elements (Tr 1  to Tr 4 ), and rotates the electric motor in normal and reverse directions by turning on and turning off the switching semiconductor elements (Tr 1  to Tr 4 ). The driving control device ( 50 ) conducts to activate and to stop the electric motor ( 30 ) by applying a PWM signal to the switching semiconductor elements (Tr 3  and Tr 4 ) constructing the lower arm of the H bridge circuit ( 51 ).

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a driving control device for an actuator which controls the driving of the actuator for opening and closing an air mix door of an air conditioning device for a vehicle, for example.  
           [0003]    2. Description of the Prior Art  
           [0004]    Conventionally, there has been known a driving control device for an actuator which controls the driving of the actuator for opening and closing an intake door.  
           [0005]    This type of actuator driving control device comprises a driving circuit for driving a DC electric motor and a driving control circuit for controlling the rotation of the electric motor by controlling the driving circuit.  
           [0006]    The driving control circuit compares a detected signal of a detecting device which detects the rotation position of the intake door and a targeted value, and controls the driving circuit so as to position the intake door in a targeted position.  
           [0007]    The driving circuit of the actuator driving control device is composed of an H bridge circuit  100  for rotating the DC electric motor in normal and reverse directions. The H bridge circuit  100  is composed of four MOS type transistors Tr 1  to Tr 4 , as shown in FIG. 6, for example.  
           [0008]    In the H bridge circuit, it has been known that at least two transistors of the four transistors are driven by PWM control (for example, reference to Japanese Patent 3199722).  
           [0009]    However, in this actuator driving control device, when the motor is actuated or is stopped, the output of the electric motor is rapidly changed by ON/OFF operations (turning on and/or turning off) of the MOS transistors, Tr 1  to Tr 4 , of the H bridge circuit  100 ,  
           [0010]    Consequently, there has been a problem that noise is generated by backlash of a gear, and the noise is offensive to ears, because especially in recent years, a sound of an engine has been reduced, and an interior of a car has been becoming noiseless.  
         SUMMARY OF THE INVENTION  
         [0011]    It is, therefore, an object of the present invention to provide a driving control device for an actuator capable of preventing a generation of noise when an electric motor is actuated or is stopped.  
           [0012]    In order to achieve above object, an driving control device for an actuator according to the present invention comprises a driving device to drive an actuator having an electric motor and a driving control device to control the rotation of the electric motor by controlling the driving device, and the driving device comprises an H bridge circuit constructed by a switching semiconductor element, and rotates the electric motor in normal and reverse directions by turning on and/or off the switching semiconductor element.  
           [0013]    The driving control device conducts activating and/or stopping the electric motor by applying a PWM signal to the switching element constructing the lower arm of the H bridge circuit, and regenerative braking is applied to the electric motor by applying the PWM signal to the switching semiconductor element constructing the lower arm.  
           [0014]    The driving control device may be constructed to be capable of selecting a mode for applying the PWM signal to the switching semiconductor element constructing the lower arm or a mode for applying the driving pulse.  
           [0015]    The driving control device may comprise a function for switching to apply the driving pulse when a radio is turned on and to apply the PWM signal when the radio is turned off.  
           [0016]    Moreover, the driving control device can comprise a construction for switching the mode to the mode for applying the driving pulse when a targeted torque is not obtained even if the PWM signal is applied. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a schematic view showing a construction of an air conditioning device for a vehicle in which a driving control device of an electric motor type actuator according to the present invention is applied.  
         [0018]    [0018]FIG. 2 is a view showing an example of the electric motor type actuator according to the present invention.  
         [0019]    [0019]FIG. 3 is a block diagram of the driving control device of the electric motor type actuator.  
         [0020]    [0020]FIG. 4 is a circuit diagram showing an enlarged H bridge circuit and an enlarged actuator driving control circuit according to the present invention.  
         [0021]    [0021]FIG. 5 is a timing chart describing soft start and soft stop of an electric motor.  
         [0022]    [0022]FIG. 6 is a circuit diagram showing an example of conventional H bridge circuit.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    Hereinafter, an embodiment of an air conditioning device for a vehicle to which a driving control device for an actuator according to the present invention is applied will be described with reference to the accompanying drawings.  
         [0024]    In FIG. 1, reference numeral  1  denotes a body of air conditioning device for a vehicle. As well as a general air conditioning device for a vehicle, the body  1  is constructed by an intake unit  2  for selectively taking in outside air or inside air, a cooling unit  3  for cooling the intake air, and a heater unit  4  for blowing out the blended air in a vehicle after the intake air is blended and the temperature of the intake air is adjusted.  
         [0025]    The intake unit  2  is provided with an outside air intake  5  for taking in outside air and an inside air intake  6  for taking in inside air. The connection portion of the intakes  5  and  6  is provided with a rotatable intake door (driven mechanism)  7  for adjusting the ratios of the outside air and the inside air which are taken in the unit. The intake door  7  is rotated by an electric motor type actuator (not shown).  
         [0026]    The intake door  7  is rotated by transmitting the rotation of an actuator lever  30 L to the intake door  7  shown in FIG. 1 through a link mechanism (not shown). The rotation position of the intake door  7  is detected by a potentiometer  31  as described below.  
         [0027]    As shown in FIG. 1, the intake unit  2  comprises a fun  10  which is rotated at a predetermined speed by a fun motor  9 . Each outside air or inside air is selectively taken from the outside air intake  5  or the inside air intake  6  by the rotation of the fun  10 , and in accordance with the position of the intake door  7 . Moreover, the rotation speed of the fun  10  is changed by modulation of an applied voltage to the fun motor  9 , so that the volume of air to be blown inside a vehicle is adjusted. When the intake door  7  is positioned in A as shown in FIG. 1, an outside air entry (FRE) is adopted, and when the intake door  7  is positioned in B as shown in FIG. 1, an inside air circulation (REC) is adopted.  
         [0028]    An evaporator  11  for constructing a refrigeration cycle is installed in the cleaning unit  3 . Refrigerant is supplied to the evaporator  11  by activating a compressor (not shown), and the intake air is cooled down by a heat exchange with the refrigerant.  
         [0029]    A heat core  12  for circulating engine cooling water is installed in the heater unit  4 . An air mix door  13  for adjusting the ratio between the volume of air which is passed through the heat core  12  and the volume of air which is bypassed the heat core  12  is rotatably disposed in the upstream side of the heat core  12 .  
         [0030]    The air mix door  13  is rotated by an electric motor type actuator  30 A shown in FIG. 2 through a rink mechanism (not shown). A mixture ratio between the warm air which is heated by the heat exchange with the engine cooling water after passing through the heat core  12  and unheated cool air which is bypassed the heat core  12  is changed, so that the temperature of the air which is blown inside the vehicle is adjusted.  
         [0031]    The adjusted air is supplied inside the vehicle from any blower of a defrost blower  15 , a vent blower  16 , and a foot blower  17 . These blowers  15  to  17  are respectively provided with a defrost door  18 , a vent door  19 , and a foot door  20  rotatably.  
         [0032]    These doors  18  to  20  are rotated by an electric motor type actuator (not shown) through a rink mechanism (not shown). A blowing mode is arbitrarily set up by combining an opening and closing condition of each blower  15  to  17 .  
         [0033]    [0033]FIG. 2 is a view showing an example of an electric motor type actuator according to the present invention. The electric motor type actuator  30 A comprises an electric motor  30 , a worm  30   c  installed in a power output shaft  30   b  of the electric motor  30 , a reduction gear train mechanism  30   e  which is engaged with the worm  30   c , and the actuator lever  30 L which is rotated through the worm  30   c  and the reduction gear train mechanism  30   e.    
         [0034]    [0034]FIG. 3 is a block diagram showing the construction of a control unit (a driving control device for an actuator)  40  which controls the actuator  30 A and the like.  
         [0035]    The control unit  40  is provided with a power source circuit of 5V  41 , a circuit for protecting an internal power source  42 , a first LIN input circuit, a second LIN output circuit, a communication ID input setup circuit  80 , and a LIN communication processing circuit  45 .  
         [0036]    The power source circuit of 5V  41  generates 5V power source by receiving the electric power from a power source of battery +B. The internal power source protecting circuit  42  protects the 5V power source circuit  41 . The first LIN input circuit receives data from a main control unit (not shown). The second LIN output circuit sends data to the main control unit (not shown). The communication ID input setup circuit  80  sets up an ID cord for identifying each control unit  40 . The LIN communication processing circuit  45  extracts data having the same ID cord with the ID cord which is set up by the communication ID input setup circuit  80  from the data received by the LIN input circuit  43 . The LIN communication processing circuit  45  adds the ID cord set up by the ID input setup circuit  80  to required data, and then sends the data to the LIN output circuit  44 . At this point, the LIN communication processing is a communication in line with ISO9141 standard, and its communication method is UART.  
         [0037]    Furthermore, the control unit  40  comprises a data latch circuit  46 , a D/A converter  47 , an input circuit  48 , a comparator  49 , and an actuator driving output control circuit (driving control device)  50 , and an H bridge circuit (driving device)  51 .  
         [0038]    The data latch circuit  46  maintains the data extracted by the LIN communication processing circuit  45 . The D/A converter  47  conducts D/A conversion for the data maintained by the data latch circuit  46 . The input circuit  48  inputs the output voltage of the potentiometer  31  which detects an opening of the intake door  7 . The comparator  49  compares the output voltage of the potentiometer  31  which is supplied through the input circuit  48  and the voltage which is output from the D/A converter  47 , and then outputs an output signal in accordance with the difference of those voltages. The actuator driving output control circuit  50  generates PWM signal, which controls the electric motor, based on the output signal of the comparator  49 , and outputs the PWM signal. The H bridge circuit  51  drives the electric motor  30  based on the PWM signal which is output from the actuator driving output control circuit  50 .  
         [0039]    The control unit  40  is also provided with an over-current detection circuit  53 , an over-voltage detection circuit  54 , and an over-temperature detection circuit  55 . The over-current detection circuit  53  generates an over-current detection output when the current supplied to the electric motor  30  through the H bridge circuit  51  exceeds a predetermined acceptable value. The over-voltage detection circuit  53  generates an over-current detection output when the voltage (voltage of power source of battery +B) applied to the electric motor  30   e  exceeds a predetermined acceptable value. The over-temperature detection circuit  55  observes a temperature of the electric motor  30  based on a detected output of a temperature detection element (not shown) such as a thermistor installed in the electric motor  30 , and generates an over-temperature detection output when a temperature of the electric motor  30  exceeds a predetermined acceptable temperature.  
         [0040]    When the over-current, the over-voltage, and the over-temperature are detected by these detection circuits  53 ,  54 , and  55 , the H bridge circuit  51  and the electric motor  30  are adopted to be protected by stopping the driving of the electric motor  30 .  
         [0041]    [0041]FIG. 4 is a partly enlarged view of the H bridge circuit and the actuator driving control circuit. The H bridge circuit  51  is constructed by first and second transistors, Tr 1  and Tr 2 , which construct an upper arm, a transistor Tr 3  which constructs one of the lower arms, and a transistor Tr 4  which constructs the other lower arm.  
         [0042]    The actuator driving output control circuit  50  judges about whether or not the driving of the electric motor  30  is required based on the output voltage of the comparator  49 . In other words, when the output voltage of the comparator  49  is higher than a reference voltage by a predetermined value, the actuator driving output control circuit  50  determines that the door should be driven in an opening direction by normally driving the electric motor  30 . When the output voltage of the comparator  49  is lower than the reference voltage by a predetermined value, the actuator driving output control circuit  50  determines that the door should be driven in a closing direction by reversely driving the electric motor  30 . When the output voltage of the comparator  49  is within a predetermined value range with respect to the reference voltage, the actuator driving output control circuit  50  determines that the electric motor  30  should be stopped.  
         [0043]    While the driving of the electric motor  30  is stopped, the actuator driving output control circuit  50  outputs a driving pulse to the transistors Tr 3  and Tr 4  such that the transistor Tr 3  is turned on, and the transistor Tr 4  is turned on. In FIG. 5, a reference numeral T denotes a zone that the driving pulse is input in the transistors Tr 3  and Tr 4 .  
         [0044]    As shown in FIG. 5, when the electric motor  30  is driven in the normal direction, a driving pulse P 1  is output from a driving signal output terminal Q 1  to the transistor Tr 1 , and the transistors Tr 4  and Tr 3  are turned off once. Next, PWM signal is output from a driving signal output terminal Q 4  to the transistor Tr 4 . The PWM signal is controlled such that a duty ratio of the PWM signal is increased by 8% per second during the time ta from 0% to 100% adopting a targeted value of rotation frequency as 100%.  
         [0045]    When the transistor Tr 4  is turned on, an electric current shown in arrow A 1  of FIG. 4 is flowed into the electric motor  30 , and the rotation frequency of the electric motor  30  is gradually increased during the time ta, after that the electric motor  30  is rotated by a constant rotation frequency.  
         [0046]    Next, when the actuator driving output control circuit  50  determines that the electric motor  30  should be stopped, PWM signal in which a duty ratio is decreased from 100% to 0% by 8% per second is output from the driving signal output terminal Q 4  to the transistor Tr 4  during time tb. The rotation frequency of th electric motor  30  is thereby decreased. At this point, the electric current flowed into the positive terminal of the electric motor  30  becomes a reference numeral G 1  of FIG. 5.  
         [0047]    While the actuator driving output control circuit  50  turns off the transistor Tr 1  for softly applying a regeneration brake to the electric motor  30 , the actuator driving outputs control circuit  50  outputs the PWM signal in which the duty ratio is increased from 0% to 100% from the driving signal output terminals Q 3  and Q 4  to the transistors Tr 3  and Tr 4  during the time tb. The electric current in the direction of arrow A 2  is thereby flowed into the electric motor  30  based on an electromotive force accompanying the inertia rotation of the electric motor  30 , and the regeneration brake is softly applied to the electric motor  30 , and then the rotation of the electric motor is stopped.  
         [0048]    As shown in FIG. 5, when the electric motor  30  is driven in the reverse direction, a driving pulse P 2  is output from the driving signal output terminal Q 2  to the transistor Tr 2 , and the transistors Tr 3  and Tr 4  are turned off once. Next, PWM signal is output from the driving signal output terminal Q 3  to the transistor Tr 3 . The PWM signal is controlled such that the duty ratio of PWM signal is increased by 8% per second during the time ta from 0% to 100% adopting a targeted value of revolution frequency as 100%.  
         [0049]    When the transistor Tr 3  is turned on, an electric current shown in arrow B 1  is flowed into the electric motor  30 , and the rotation frequency of the electric motor  30  is gradually increased during the time ta. After that the electric motor  30  is rotated in the reverse direction at a constant rotation frequency.  
         [0050]    Next, when the actuator driving output control circuit  50  determines that the electric motor  30  should be stopped, the PWM signal in which the duty ratio is decreased from 100% to 0% by 8% per second is output from the driving signal output terminal Q 3  to the transistor Tr 3  during the time tb. The rotation frequency of the electric motor  30  is thereby decreased. At this point, the electric current flowed into the negative terminal of the electric motor  30  becomes a reference numeral G 2  of FIG. 5.  
         [0051]    While the actuator driving output control circuit  50  turns off the transistor Tr 2  for softly applying a regeneration brake to the electric motor  30 , the actuator driving output control circuit  50  outputs the PWM signal in which the duty ratio is increased from 0% to 100% from the driving signal output terminals Q 3  and Q 4  to the transistors Tr 3  and Tr 4  during the time tb.  
         [0052]    Consequently, the electric current in the direction of the arrow B 2  in FIG. 4 is flowed into the electric motor  30  based on an electromotive force accompanying the inertia rotation of the electric motor  30 , and the regeneration brake is softly applied to the electric motor  30 , and then the rotation of the electric motor is stopped.  
         [0053]    In this embodiment of the present invention, when the electric motor is activated, the rotation frequency of the electric motor  30  is adopted to increase from 0% to 100%, and when the electric motor is stopped, the rotation frequency of the electric motor  30  is adopted to decrease from 100% to 0%, so that the noise caused by backlash of a gear is reduced by using the PWM signal.  
         [0054]    However, when avoiding a generation of radio noise caused by the PWM signal rather than reducing the noise caused by backlash of a gear, a bit for controlling ON/OFF of the PWM signal (turning on and turning off of the PWM signal) is provided in the LIN communication signal, and the actuator driving output control circuit  50  may determine the ON/OFF of the PWM signal. With the above described construction, when the PWM signal is ON, the actuator driving output control circuit  50  adopts a mode for applying the PWM signal, and when the PWM signal is OFF, the actuator driving output control circuit  50  adopts a mode for applying a driving pulse in which the transistors Tr 3  and Tr 4  are turned on and are turned off without being late.  
         [0055]    The actuator driving output control circuit  50  may comprise a function for switching to apply the driving pulse when a radio is turned on and to apply the PWM signal when the radio is turned off.  
         [0056]    The actuator driving output control circuit  50  may comprise a function for switching the mode to the mode for applying the driving pulse when a targeted torque cannot be obtained even if the PWM signal is applied.  
         [0057]    As described above, according to the present invention, an electric motor can be started softly and can be stopped softly, so that when the electric motor is activated or is stopped, the noise generated by a power transmission mechanism such as a reduction mechanism or a driven mechanism such as an opening and closing mechanism can be reduced without changing a circuit construction drastically.