Abstract:
Disclosed is a calibration apparatus for an airbag inflator resistance. The calibration apparatus for an airbag inflator resistance includes: an airbag inflator unit for applying a deployment signal for deployment of an airbag; a resistance detection unit for detecting a change in the resistance of the airbag inflator connector; and a control unit for self-cleaning the airbag inflator connector in accordance with the resultant resistance detected by the resistance detection unit. The calibration apparatus is effective in preventing malfunction of an airbag warning light and ensuring reliability by preventing an increase in resistance due to the contamination of the airbag inflator by the self-diagnosing and self-cleaning effect using an electric current.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Application No. 2007-0084080, filed Aug. 21, 2007 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a calibration apparatus for an airbag inflator resistance, and more particularly, to a calibration apparatus for an airbag inflator resistance, which prevents malfunction of an airbag warning light and ensures reliability of the airbag device by preventing an increase in resistance occurring due to the contamination of the airbag inflator by use of the self-cleaning effect using an electric current. 
     2. Description of the Related Art 
     Generally, an airbag device is a safety device for protecting a driver or a fellow passenger, which alleviates an impact applied to the driver or the fellow passenger by detecting an impact at the moment of a vehicle crash and deploying the airbag instantaneously before the passengers hit the vehicle body, thereby protecting the driver or the fellow passenger from a secondary impact caused by the vehicle crash. 
     The airbag cushion of airbag device is expanded by an inflator and the inflator is connected with airbag inflator connector. In the event the sensors of the airbag device sense a vehicle condition for which inflation of the air bag cushion is desired, a controller sends an electric actuating signal to the airbag inflator connector. Therefore, the reliability of the airbag device sometimes depends on the status of the airbag inflator connector as explained next. 
     Such an airbag device is equipped with a self-diagnosis function, and thus informs the driver of the current state of airbag device by turning on a warning light or the like depending upon the failure situation in the event of an airbag failure. 
     In an airbag self-diagnosis system of a mass-produced vehicle, the airbag self-diagnosis system sometimes malfunctions due to an increase in contact resistance caused by an accumulation formed by the contamination of an airbag inflator connector terminal because of pollutants such as cigarette smoke, soot, an aromatic agent, etc. Hence, it occurs often that the warning light is turned on even if there is no malfunction in the condition of the airbag, which hurts the reliability of the self-diagnosis system of the airbag device. 
     Accordingly, there is a need for a measure for preventing malfunction of the self-diagnosis system of the airbag device by eliminating the contamination formed on the airbag inflator connector terminal after self-diagnosis of the contamination. 
     The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to solve the aforementioned problems associated with prior arts. 
     Accordingly, it is an object of the present invention to prevent malfunction of an airbag warning and ensure reliability by self-cleaning the contamination of an airbag inflator connector terminal by using an electric current. 
     In order to achieve the aforementioned object and other objects, a calibration apparatus for an airbag inflator resistance in accordance with the present invention comprises: an airbag inflator unit for applying a deployment signal for deployment of an airbag; a resistance detection unit for detecting a change in the resistance of the airbag inflator connector; and a control unit for self-cleaning the airbag inflator connector in accordance with the result resistance detected by the resistance detection unit. 
     Meanwhile, a method for controlling a calibration apparatus for an airbag inflator resistance in accordance with the present invention comprises: the self-diagnosis step of measuring the resistance of an airbag inflator connector in real time; the detection step of comparing the measured resistance of the airbag inflator connector with a reference resistance; and the self-cleaning step of applying a current for self-cleaning the airbag inflator connector of the airbag inflator if the measured resistance is higher than the reference resistance. 
     The above features and advantages of the present invention will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated in and form a part of this specification, and the following Detailed Description of the Invention, which together serve to explain by way of example the principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated the accompanying drawings which are given hereinbelow by way of illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a block diagram showing the configuration of a calibration apparatus for measuring a resistance of the airbag inflator connector and its self-cleaning in accordance with one embodiment of the present invention; 
         FIG. 2  is circuit diagram showing the configuration of the circuit of the calibration apparatus for measuring a resistance of the airbag inflator connector and its self-cleaning in accordance with one embodiment of the present invention; 
         FIG. 3  is a view showing a result of an experiment in which a self-cleaning current for airbag inflator connector of the calibration apparatus in accordance with one embodiment of the present invention is set in two types of 100 mA and 40 mA; and 
         FIG. 4  is a sequence view showing a method for controlling a calibration apparatus for measuring a resistance of the airbag inflator connector and its self-cleaning in accordance with one embodiment of the present invention. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     Hereinafter, the present invention will be described with reference to the drawings. 
       FIG. 1  is a block diagram showing the configuration of a calibration apparatus for measuring a resistance of the airbag inflator connector and its self-cleaning in accordance with one embodiment of the present invention. 
     Referring to  FIG. 1 , the calibration apparatus for measuring a resistance of the airbag inflator connector and its self-cleaning includes an alarm mechanism  10 , a control unit  20 , an airbag inflator unit  30 , and a resistance detection unit  40 . 
     The control unit  20  transmits a signal for diagnosing the malfunction of the airbag inflator unit  30 , and lets a self-cleaning current flow to eliminate impurities on the airbag inflator unit  30  or outputs an operating signal of the alarm mechanism in the event of a malfunction of the airbag inflator unit  30 . 
     The self-cleaning effect refers to the effect of eliminating pollutants by applying the same or more than a predetermined amount of current to a contact end portion, such as a connector terminal. 
     In detail, when the control unit  20  transmits a current signal for diagnosing the airbag inflator unit  30 , the resistance detection unit  40  detects the current signal flowing through the airbag inflator unit  30  and measures the resistance of the airbag inflator unit  30 , and feedback the measured result thereof to the control unit  20  in an exemplary embodiment of the present invention. 
     Based on the transmitted resistance value, the control unit  20  determines whether the control unit  20  may output a signal for operating the alarm mechanism  10  and/or apply a self-cleaning current to the airbag inflator unit  30 . 
       FIG. 2  is circuit diagram showing the configuration of the circuit of the calibration apparatus for measuring a resistance of the airbag inflator connector and its self-cleaning in accordance with one embodiment of the present invention. 
     Referring to  FIG. 2 , the circuit includes an integrated controller  50  and an airbag controller  60  in the control unit  20 , an airbag inflator connector  70  and an airbag inflator  80  in the airbag inflator unit  30 , a resistance detection unit  40  for measuring the resistance of the airbag inflator connector  70 , and an alarm mechanism  10 . 
     First of all, the self-diagnosis mechanism will be explained hereinafter. 
     To apply a self-diagnosis current V, first, the integrated controller  50  of the control unit  20  applies a HS (high side) voltage signal and an LS (low side) voltage signal and thus the HS switch and LS switch of the airbag controller  60  are opened. Then a self-diagnosis current V flows to the airbag inflator connector  70  in the airbag inflator unit  30 . 
     As for the specification of the self-diagnosis current V, the cycle ranges from 200 to 400 ms, and a current of about 35 to 40 mA is inputted for 2 ms. The self-diagnosis current V goes out through the HS switch and returns into the control unit  20  through the LS switch as shown in  FIG. 2 . 
     The resistance detection unit  40  detects a current before and after the self-diagnosis current V passes through the airbag inflator connector  70  to measure the resistance and feedback the result of detection to the integrated controller  50  in the control unit  20 . 
     The airbag inflator connector  70  is connected to the airbag inflator  80  by ultrasonic welding. The ultrasonic welding refers to melting and bonding by converting an electrical energy into a mechanical energy through a vibration difference and then generating an instantaneous frictional heat on a bonded surface upon transferring the mechanical energy to a welding material through a horn, and is used for plastic welding, fabric and film stitching, and metal welding. 
     The reference resistance of the airbag inflator connector  70  is 1.8 to 2.29Ω. Although different depending on types of cars due to the accumulation formed by the contamination of the connector terminal by cigarette smoke, soot, an aromatic agent, etc., usually an increase in resistance of 5 to 8Ω is recognized and transmitted to the integrated controller  50  by the resistance detection unit  40 . 
     Depending on an amount in the resistance of the airbag inflator connector  70 , the integrated controller  50  transmits, to the airbag controller  60 , a signal for applying a current self-cleaning the airbag inflator connector  70 , or informs the driver of an airbag failure state by outputting an operating signal of the alarm mechanism  10 . 
     Hereinafter, the self-cleaning mechanism will be explained in detail. 
     In order to prevent the phenomenon of resistance increase caused by pollutants adhered on the airbag inflator connector  70 , when a measured resistance higher than the reference resistance of the airbag inflator connector is detected by the control unit  20  in real time through the resistance detection unit  40 , the self-cleaning current is applied to the airbag inflator connector  70  to eliminate the pollutants on the connector terminal by applying a current of 90 to 110 mA for about 3 seconds in an exemplary embodiment of the present invention. However the time period to eliminate the pollutants is not limited thereto. 
     Regarding the self-cleaning current, a current of 90 to 110 mA, preferably, a current of 100 mA, is applied for about 3 seconds. A detailed description of the amount of application of the self-cleaning current will be made. 
       FIG. 3  is a view showing a result of an experiment in which a self-cleaning current of the calibration apparatus for an airbag inflator resistance in accordance with one embodiment of the present invention is set in two types of 100 mA and 40 mA. 
     Referring to  FIG. 3 , a voltage drop at a current of 40 mA shows an amplitude of about 130 mV at maximum, while a voltage drop in a circuit of 100 mA shows an amplitude of about 20 mV, which is more stable. 
     At 40 mA, the average value of contact resistance hardly changes, but there is a possibility of an increase in contact resistance. At 100 mA, any significant change is not observed, and there is shown a self-cleaning effect of pollutants. 
       FIG. 4  is a sequence view showing a method for controlling a calibration apparatus for measuring a resistance of the airbag inflator connector and its self-cleaning in accordance with one embodiment of the present invention. 
     The first self-diagnosis for measuring a resistance of the airbag inflator connector in real time is performed (S 100 ). At this step, the resistance of the airbag inflator connector  70  is measured and the measured resistance and a reference resistance are compared with each other (S 102 ). 
     As a result of comparison of S 102 , if the measured resistance is not greater than the reference resistance, the self-diagnosis step is performed again, while if the measured resistance is equal to or greater than the reference resistance, the self-diagnosis mode is stopped and starts the self-cleaning step of eliminating pollutants on the airbag inflator connector  70  (S 104 ). 
     In the self-cleaning step of S 104 , the self-cleaning current set forth above is applied to the airbag inflator connector  70  to eliminate the pollutants on the connector terminal by applying a current of 90 to 110 mA for about 3 seconds. 
     The reference resistance refers to a resistance when the airbag inflator connector  70  is not contaminated, and has a range of 1.8 to 2.2Ω. The measured resistance refers to a resistance measured by the resistance detection unit  40  before the airbag controller  60  performs the self-cleaning step on the airbag inflator connector  70 . The measured resistance may have a resistance of 5 to 8Ω, though different depending upon vehicle type, if the airbag inflator connector  70  is contaminated by pollutants, such as cigarette smoke, sot, an aromatic agent, etc. 
     After the self-cleaning, the re-self-diagnosis step of re-measuring the resistance of the airbag inflator connector  70  is performed (S 108 ). 
     After the re-self-diagnosis step, the re-detection step for comparing the re-measured resistance of the airbag inflator connector with the reference resistance is performed (S 110 ). If the re-measured resistance is not greater than the reference resistance, the first self-diagnosis step of S 100  is performed again, while if the re-measured resistance is equal to or greater than the reference resistance, the alarm mechanism  10  is operated. 
     Upon operating the alarm mechanism  10 , the driver detects a malfunction of the airbag, and if the measured resistance is not greater than the reference resistance, self-diagnosis is continuously and/or periodically performed to repeat the above-described process. 
     As aforementioned, the preferred embodiment of the present invention has been shown and described, but the present invention is not limited to the specific embodiments described above, and can be implemented in various modifications by those skilled in the art to which the present invention pertains without departing from the scope of the present invention recited in the appended claims, and such modifications should not be understood to depart from the technical spirit or prospect of the present invention.