Abstract:
Disclosed is an actuator having an electronic control module having a port and a controller in communication with the port, as well as software for instructing the controller to detect a calibration signal from the port and transmit an acknowledgment signal to the port. The actuator is placed in a calibration mode by monitoring the port be monitored for the calibration signal. Once it has been determined that the port has received the calibration signal, the actuator will be placed in the calibration mode and an acknowledgment signal will be transmitted to the port.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to a method of placing an electronic control module (ECM) of an actuator in a calibration mode and, more particularly, to a system and method of placing an ECM in a calibration mode with the ECM having only one input/output command line.  
         [0003]     2. Description of the Known Technology  
         [0004]     Automobiles are equipped with actuators to perform tasks, such as opening and closing the ventilation passageways of a heating, ventilation and air conditioning (HVAC) unit and the opening and closing of the intake manifold passageway of an internal combustion engine. The actuator itself is controlled by an ECM that includes a control input for receiving a control command, which will be interpreted by the ECM to command the actuator to either open or close the passageways. Many applications require that the passageways be opened and/or closed by a specific and predetermined amount. Therefore, the ECM must be calibrated so that the passageways are opened and/or closed by the actuator at the precise and predetermined amount.  
         [0005]     One such way of placing the ECM in a calibration mode requires that the ECM have a calibration input separate from the command input. With is system, a calibration signal is placed on the calibration input and the ECM will place itself in the calibration mode. Other solutions require that the ECM be connected to the Controller Area Network (CAN) in addition to having the separate command input. These solutions have the drawback of requiring that the ECM have multiple inputs.  
         [0006]     Therefore, it is desirable to provide a system and method for calibrating an ECM that requires only one input for placing the ECM in the calibration, as well as controlling the ECM.  
       BRIEF SUMMARY  
       [0007]     In overcoming the drawbacks and limitations of the known technology, a system and method for placing an actuator in a calibration mode is disclosed. As defined herein, the actuator includes an electronic control module having a port and a controller in communication with the port, as well as software for instructing the controller to detect a calibration signal from the port and transmit an acknowledgment signal to the port. The actuator may further include a motor in communication with the controller. The motor will turn a shaft, either directly or via a gear train. The method for placing an actuator in the calibration mode requires that the port be monitored for the calibration signal. Once it has been determined that the port has received the calibration signal, the actuator will be placed in the calibration mode. Thereafter, an acknowledgment signal will be transmitted to the port.  
         [0008]     By way of example, the calibration signal may be a 1 kHz signal for 250 ms followed by a 2 kHz signal for 250 ms. Alternatively, the calibration signal may vary and differ from that described above. The acknowledgment signal, as by way of example only, may be a 10% duty cycle signal. Obviously, the duty cycle may vary and differ from that described above.  
         [0009]     These and other advantages, features, and embodiments of the invention will become apparent from the drawings, detailed description, and claims, which follow. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a side view of an actuator embodying the principles of the present invention; and  
         [0011]      FIG. 2  is a cross-sectional view, generally taken along line  2 - 2 , of the actuator seen in  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0012]     Referring to  FIG. 1 , an actuator  10  is illustrated therein and includes a housing  12  having mounting points  14 ,  16 ,  18 . The housing is typically made of plastic but may be made of metal. Extending from a side  20  of the housing  12  is an electrical connector  22  that allows for outside communication with the actuator  10  via a pin  23 . Extending from a one side  24  of the housing  12  is an output shaft  26 . Generally, the shaft  26  is made of a metal, such as steel, but may alternatively be made of plastic.  
         [0013]     Referring now to  FIG. 2 , inside the housing  12  is located a motor  28 , preferably an electrical motor of conventional construction. At a first end  30  of the motor  28  is an output  32  extends from one end  30  of the motor  28 . Also extending from the motor  28  are motor control lines  38 ,  40 .  
         [0014]     In addition to the motor  28 , disposed within the housing  12 , is an electronic control module (ECM)  42  that is connected to the motor  28  via the control lines  38 ,  40 . The ECM  42  includes a controller  44 , a memory unit  46 , and a Hall Effect sensor  48  and a diode  49 . Generally, the memory unit is a non-volatile memory unit in electrical communication with the controller  44 . Alternatively, the controller  44  may contain an integrated memory unit, thus relinquishing the need of the memory unit  46 .  
         [0015]     The output  32  of the motor  28  is coupled to the output shaft  26  of the actuator  10  by way of a gear train  50  the gear train  50  includes a worm gear  34 , a first sprocket  52 , and a second sprocket  54 . Generally, the first and second sprockets  52 ,  54  are made of plastic, but may be made of an alternative material, such as steel.  
         [0016]     The worm gear  34  is mounted on, and rotates with, the output  32  of the motor  28 . The worm gear  34  mechanically engages a first sprocket  52  and will rotate the sprocket  52  around the axis  56 . The first sprocket  52 , first is coupled to a second sprocket  54 , which is concentric therewith and will also rotate around the axis  56 .  
         [0017]     The teeth on the second sprocket  54  engage corresponding teeth on a shaft sprocket or bell gear  58 , which is in turn connected to the output shaft  26  of the actuator  10  so as to rotate therewith. Thus, when the second sprocket  54  is caused to rotate, the shaft sprocket  58  will rotate causing the output shaft  26  to correspondingly rotate.  
         [0018]     Also coupled to the shaft sprocket  58  is a magnet  60 . The Hall Effect sensor  48  is located proximate to the magnet  60  so that the magnetic field created by the magnet  60  can be detected by the Hall Effect sensor  48 . With regard to the magnet  60 , the magnet  60  is oriented such that during rotation of the shaft sprocket  58  the magnet&#39;s poles  61 ,  63  are caused to move relative to the Hall Effect sensor  48 . The diode  49  is also placed proximate to both the magnet  60  and the Hall Effect sensor  48 . The diode  49  is sensitive to temperature and will produce a voltage signal indicative of the temperature in the surrounding area, including the area near the Hall Effect sensor  48  and the magnet  60 . The magnet  60  may be a neodymium iron boron (NeFeB) magnet but may be a Samarian cobalt (SmCo) magnet.  
         [0019]     During operation of the actuator  10 , the controller  44  continuously monitors the pin  23  of the electrical connector  22  for a calibration signal. Since the pin  23  of the electrical connector  22  may be used for other purposes, such as for receiving a signal for instructing the actuator  10  to rotate the shaft  26 , the calibration signal must be unique enough for the controller  44  to differentiate it from other signals.  
         [0020]     One of many possible constructs for the calibration signal is a 1 kHz signal for 250 ms followed by a 2 kHz for 250 ms. The only requirement for this signal is that the calibration signal be unique enough for the controller  44  to differentiate it from other signals.  
         [0021]     Once the controller  44  has determined that the pin  23  of the electrical connector  22  has received the calibration signal, the controller  44  will place the actuator  10  in a calibration mode and output an acknowledgment signal, such as a 10% duty cycle signal, through the pin  23  of the electrical connector  22 . Alternatively, the acknowledgment signal, may vary from the example. The only requirement for the acknowledgment signal being that acknowledgment signal is unique enough for an outside device (connected to the pin  23  of the electrical connector  22 ) to be able to differentiate the acknowledgment signal from other signals.  
         [0022]     After the actuator  10  has been placed into the calibration mode, the actuator  10  may follow any number of calibration methods. One such method utilized relates to calibrating the output of the Hall Effect sensor  48  after final assembly of the actuator  10 .  
         [0023]     This method first requires that the shaft  26  is moved to a first position. This may be accomplished by an external force or by the motor  28 . If the motor  28  is used to rotate the shaft  26  to the first position, the controller  44  instructs the motor  28  to rotate the shaft  26  in a first direction while the controller  44  monitors the output of the Hall Effect sensor  48 . When the output of the Hall Effect sensor  48  is no longer changing over a period of time, the controller  44  determines that the shaft  26  has reached the first position and the controller  44  instructs the motor  28  to stop rotating the shaft  26  in the first direction. Afterward, the controller  44  takes a reading from the Hall Effect sensor  38  and stores the reading in the memory unit  46  as a first stop value.  
         [0024]     Next, the shaft  26  is moved to a second position. Similarly, this may be accomplished by an external force or by the motor  28 . If the motor  28  is used to rotate the shaft  26  to the second position, the controller  44  instructs the motor  28  to rotate the shaft in a second direction and the controller  44  monitors the output of the Hall Effect sensor  48 . When the output of the Hall Effect sensor  48  is no longer changing, the shaft  26  has reached the second position and the controller  44  instructs the motor  28  to stop rotating the shaft  26  in the second direction. Afterward, the controller  44  takes a reading from the Hall Effect sensor  48  and stores the reading in the memory unit  46  as a second stop value.  
         [0025]     When operation, the shaft  26  will be required to rotate to either the first position or the second position. Using the previously stored first and second stop values, the controller  44  is be able to determine when the shaft  26  has reached either the first position or the second position. This is done by having the controller  44  monitor the output of the Hall Effect sensor  48  and compare the output of the Hall Effect sensor  48  to the first and second stop values. When the output of the Hall Effect sensor  48  approximately matches the first or second stop value, the controller determines that the shaft  26  has reached either the first position or the second position and instructs the motor  28  to stop rotating the shaft  26 .  
         [0026]     Another method that may be used in calibrating the actuator  10  is adjusting the output of the Hall Effect sensor  48  for changes in the temperature in the magnet  60  and the Hall Effect sensor  48 . Similar to the previously described method, the shaft  26  is moved to the first position and the second position by either and external force or the motor  28 . Likewise, the first stop value and second stop value are stored in the memory unit  46 .  
         [0027]     Additionally, a reading from a diode  49  is stored in the memory unit  46  as a calibration temperature value. The calibration temperature value is representative of the temperature near the magnet  60  and the Hall Effect sensor  48 . Preferably the first stop value, the second stop value and the calibration temperature value is measured and stored in the memory unit  46  when the temperature of the magnet  60  and the Hall Effect sensor  48  is 25 degrees C.  
         [0028]     When in operation, the output of the Hall Effect sensor  48  will vary as the temperature of the Hall Effect sensor  48  and the magnet change. The output of the diode  48 , being near the Hall Effect sensor  48  and the magnet  60 , will change in accordance to the change in temperature to the Hall Effect sensor  48  and the magnet  60 .  
         [0029]     During operation, the output of the diode  49  is monitored and converted to a current temperature value. The current temperature value is then subtracted from the calibration temperature value to obtain a temperature difference value. Using the temperature difference value, the controller calculates a correction factor. The correction factor may be calculated by using empirical data stored in the memory unit  46 . The correction factor is then added to the first stop value and subtracted from the second stop value to obtain a compensated first stop value and a compensated second stop value.  
         [0030]     In operation, the shaft  26  will be required to rotate to either the first position or the second position. Using the previously calculated compensated first and second stop values, the controller  44  will be able to determine when the shaft  26  has reached either the first position or the second position. These is done by having the controller  44  monitor the output of the Hall Effect sensor  48  and compare the output of the Hall Effect sensor  48  to the compensated first and second stop values. When the output of the Hall Effect sensor  48  approximately matches the compensated first or second stop value, the controller will determine that the shaft  26  has reached either the first position or the second position and instruct the motor  28  to stop rotating the shaft  26 .  
         [0031]     The foregoing description of the embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiment disclosed. Numerous modifications or variations are possible in light of the above teaching. The embodiment discussed was chosen and described to provide the best illustration of the principles of the invention in its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particulate use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.