Abstract:
A control system of a starting motor for an automatic transmission vehicle includes a starting switch having a plurality of nodes and an ignition key for connecting the plurality of nodes to a battery, a position sensor detecting a shift lever position and generating a pulse width modulation signal corresponding thereto, a shift control module receiving the pulse width modulation signal from the position sensor and generating a starting control signal, and a starting relay electrically connected to the starting switch and the shift control module and applying the battery power to the starting motor, wherein the shift control module generates the starting control signal if the shift lever position is a P position or an N position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2005-0120952 filed in the Korean Intellectual Property Office on Dec. 9, 2005, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a control system of a starting motor for an automatic transmission vehicle. More particularly, the present invention relates to a control system of a starting motor for an automatic transmission vehicle that prevents a malfunction of the starting motor. 
     (b) Description of the Related Art 
     An engine of an automatic transmission vehicle can be started only when a shift lever position is parking (P) or neutral (N). Such function is controlled by an inhibitor switch. If the D, 2, L, or R node is selected in the inhibitor switch, the engine is not started. 
     However, the inhibitor switch may not determine an exact position of the shift lever because of a complex structure of the inhibitor switch and wearing of the nodes of the inhibitor switch. 
     To solve such problems, a control system of a starting motor using a position sensor has been designed. 
     In such a system, a position sensor detects a shift lever position and generates a signal corresponding thereto. A shift control module receives the signal and determines whether the shift lever position is the parking (P) or neutral (N) position. The shift control module controls the starting relay so as to operate the starting motor. 
     However, when the vehicle is exposed to very low temperatures, battery voltage drops rapidly in a few milliseconds. Accordingly, the processor does not operate normally because of the low battery voltage. Therefore, the processor does not control the starting relay. The engine thus may not start in very low temperatures. 
     To solve such problems, the shift control module further includes a buffer so that the engine can be started in very low temperatures when the processor does not operate normally. The buffer amplifies the starting control signal transmitted from the processor and outputs the starting control signal to a first switching element. 
     However, since the buffer is used to start the engine in very low temperatures, many problems may occur. Since the starting control signal of the processor is amplified by the buffer during a predetermined time ΔT 1 , the starting control signal applied to the starting relay is delayed. 
     Therefore, if the shift lever position is changed to a drive (D) position or a reverse (R) position during the delay time, the starting relay is turned on regardless of the shift lever position. Thus, problems such as a quick start may occur. Such problems may occur under normal conditions as well as in very low temperatures. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY OF THE INVENTION 
     A control system of a starting motor for an automatic transmission vehicle according to an exemplary embodiment of the present invention may include: a starting switch having a plurality of nodes and an ignition key for connecting the plurality of nodes to the battery; a position sensor detecting a shift lever position and generating a pulse width modulation signal corresponding thereto; a shift control module receiving the pulse width modulation signal from the position sensor and generating a starting control signal; and a starting relay electrically connected to the starting switch and the shift control module, and applying the battery power to the starting motor, wherein the shift control module generates the starting control signal when the shift lever position is a P position or an N position. 
     The shift control module may include: a buffer for amplifying the starting control signal applied to the starting relay; a first switching element for receiving the starting control signal from the buffer and performing a switching operation; a processor for transmitting the starting control signal to the buffer, the processor connected to the position sensor and receiving the signal corresponding to the shift lever position; and a second switching element for receiving the starting control signal from the processor and performing a switching operation, the second switching element connected to the first switching element. 
     The first switching element and the second switching element may be coupled in series with each other. 
     The first switching element may include: a drain terminal connected to a terminal of the starting relay; a gate terminal connected to an output terminal of the buffer; and a source terminal. 
     The second switching element may include: a drain terminal connected to the source terminal of the first switching element; a gate terminal connected to an output terminal of the processor; and a source terminal connected to ground. 
     The second switching element may perform the switching operation according to the starting control signal of the processor when the processor operates normally. 
     The second switching element may perform the switching operation according to the starting control signal of the buffer when the processor does not operate normally. 
     The shift control module may further include a resistor and a diode coupled in parallel to the first and second switching elements. 
     The diode may rectify the starting control signal of the processor so the signal is not directly input to the first switching element. 
     The processor may receive the pulse width modulation signal from the position sensor and generate the starting control signal only when a starting condition is satisfied. 
     The starting condition may be satisfied when an ACC or ON node of the starting switch is selected and the engine is not running. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a control system of a starting motor for an automatic transmission vehicle according to an exemplary embodiment of the present invention; 
         FIG. 2  illustrates operational timings of a starting control signal under normal conditions according to an exemplary embodiment of the present invention; and 
         FIG. 3  illustrates operational timings of the starting control signal at very low temperatures according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
     As shown in  FIG. 1 , a control system of a starting motor for an automatic transmission vehicle according to an exemplary embodiment of the present invention includes a battery  100 , a starting switch  200 , a position sensor  300 , a shift control module  400 , a starting relay  500 , and a starting motor  600 . 
     The battery  100  is mounted on the vehicle and supplies a power to the starting motor  600  when an engine starts. 
     The starting switch  200  has a plurality of nodes, for example, LOCK, ACC, ON, and ST. When one of the nodes is selected by an ignition key  210 , the battery power is supplied to loads. If the ST node is selected, the starting motor  600  starts the engine. 
     The position sensor  300  transforms a signal corresponding to a shift lever position into a pulse width modulation (PWM) signal, and transmits the PWM signal to the shift control module  400 . 
     If a starting condition is satisfied and the engine is not running, the shift control module  400  receives the PWM signal from the position sensor  300  and determines the shift lever position. If the shift lever position is park (P) or neutral (N), the shift control module  400  outputs a starting control signal to the starting relay  500 . The starting condition may be satisfied when an ACC or ON node of the starting switch is selected and the engine is not running. 
     When the starting control signal is transmitted to the starting relay  500  from the shift control module  400 , and the ST node of the starting switch is selected, an inner coil  510  of the starting relay  500  is magnetized and generates a magnetic force. Therefore, an inner switch  520  of the starting relay  500  is turned on and the battery power is supplied to the starting motor  600 . The starting motor  600  is thus operated by the battery power supplied from the starting relay  500  and starts the engine. 
     The shift control module  400  includes a processor  410 , a buffer  420 , a first switching element Q 11 , a second switching element Q 21 , a resistor R 11 , and a diode D 11 . 
     The processor  410  controls an overall process of the shift control module  400 . 
     When the starting condition is satisfied and the engine is not running, the processor  410  receives the PWM signal from the position sensor  300 . If the shift lever position is the P or N position, the processor  410  outputs the starting control signal to the buffer  420  and the second switching element Q 21 . 
     The buffer  420  amplifies the starting control signal transmitted form the processor  410  so as to improve a startability of the engine in very cold temperatures. 
     The first switching element Q 11  has a drain terminal D 1  connected to a terminal of the starting relay, a gate terminal G 1  connected to an output terminal of the buffer  420 , and a source terminal S 1 . The first switching element performs a switching operation according to the starting control signal transmitted from the buffer  420 . 
     The second switching element Q 21  has a drain terminal D 2  connected to the source terminal S 1  of the first switching element Q 11 , a source terminal S 2  connected to ground, and a gate terminal G 2  connected to an output terminal of the processor  410 . The second switching element Q 21  performs a switching operation according to the starting control signal directly transmitted from the processor  410  when the processor  410  operates normally. However, the second switching element Q 21  performs the switching operation according to the starting control signal indirectly transmitted from the buffer  420  when the processor  410  does not operate normally. 
     The first switching element Q 11  and the second switching element Q 21  are coupled in series with each other. 
     The resistor R 11  and the diode D 11  are coupled in series with each other, parallel to the first switching element Q 11  and the second switching element Q 21 . 
     The diode D 11  transmits the starting control signal of the first switching element Q 11  to the second switching element Q 21  when the processor  410  does not operate normally. 
     Therefore, the second switching element Q 21  receives the starting control signal of the buffer  420  transmitted to the first switching element Q 11  and performs the switching operation when the processor  410  does not operate normally, such as in very cold temperatures. The second switching element Q 21  receives the starting control signal of the processor  410  and performs the switching operation when the engine is started and the processor  410  operates normally. 
     The diode D 11  rectifies the starting control signal of the processor  410  so as not to be directly input to the first switching element Q 11 . 
     Hereinafter, referring to the drawings, a control process of the control system of the starting motor for the automatic transmission vehicle according to the exemplary embodiment of the present invention will be described in detail. 
     As shown in  FIG. 2 , a driver controls the starting switch  200  when the engine is not running. Then, the processor  410  of the shift control module  400  detects that the ACC or ON node of the starting switch  200  is selected. 
     The processor  410  then determines that the starting condition is satisfied. The processor  410  receives the PWM signal from the position sensor  300  and determines the shift lever position according to the PWM signal. 
     If the shift lever position is park or neutral, the processor  410  outputs the starting control signal to the gate terminal G 2  of the second switching element Q 21 , and to the buffer  420 . 
     The buffer  420  amplifies the starting control signal input from the processor  410  during a predetermined time ΔT 11 , and then transmits the starting control signal to the gate terminal G 1  of the first switching element Q 11 . 
     Therefore, the starting control signal is applied to the starting relay  500  by a switching operation of the first switching element Q 11  and the second switching element Q 21  coupled in series with each other. 
     In this state, if the starting relay  500  detects a selection of the ST node in the starting switch  200 , the inner coil  510  of the starting relay  500  is magnetized and generates the magnetic force. Therefore, the inner switch  520  of the starting relay  500  is turned on. 
     Thus, the battery power is supplied to the starting motor  600  which starts the engine. 
     When the starting control signal of the processor  410  is not supplied to the buffer  420  and the second switching element Q 21  when the engine is being started, the second switching element Q 21  directly controlled by the processor  410  is turned off. 
     In addition, the first switching element Q 11  controlled by the buffer  420  is maintained to be turned on during a delay time ΔT 12 . 
     However, since the second switching element Q 21  is turned off regardless of the switching operation of the first switching element Q 11 , the starting control signal is not applied to the starting relay  500 . 
     Therefore, if the shift lever position is changed to the drive (D) or reverse (R) position when the engine is being started, the vehicle does not start. 
     As shown in  FIG. 3 , in very low temperatures, a driver controls the starting switch  200  when the engine is not running. Then, the processor  410  of the shift control module  400  detects that the ACC or ON node of the starting switch  200  is selected. 
     The processor  410  then determines that the starting condition is satisfied. The processor  410  receives the PWM signal from the position sensor  300  and determines the shift lever position according to the PWM signal. 
     If the shift lever position is park or neutral, the processor  410  outputs the starting control signal to the gate terminal G 2  of the second switching element Q 21 . 
     Since the processor  410  is not operating normally due to very low temperatures, the second switching element Q 21  is not turned on. 
     The buffer  420  amplifies the starting control signal of the processor  410  during the predetermined time ΔT 11 , and then transmits the starting control signal to the gate terminal G 1  of the first switching element Q 11 . 
     The starting control signal of the first switching element Q 11  is transmitted to the second switching element Q 21 , and the second switching element Q 11  is turned on. Therefore, the starting control signal is applied to the starting relay  500  by the switching operation of the first switching element Q 11  and the second switching element Q 21  coupled in series with each other. 
     In this state, if the starting relay  500  detects the selection of the ST node in the starting switch  200 , the inner coil  510  of the starting relay  500  is magnetized and generates the magnetic force. Therefore, the inner switch  520  of the starting relay  500  is turned on. 
     Thus, the battery power is supplied to the starting motor  600  which starts the engine. 
     When the engine is being started, the processor  410  is restored to a normal state. Thus, the second switching element Q 21  is directly controlled by the processor  410 . 
     Therefore, when the starting control signal of the processor  410  is not supplied to the buffer  420  and the second switching element Q 21 , the second switching element Q 21  directly controlled by the processor  410  is turned off. 
     In addition, the first switching element Q 11  controlled by the buffer  420  is maintained to be turned on during the delay time ΔT 12 . 
     However, since the second switching element Q 21  is turned off regardless of the switching operation of the first switching element Q 11 , the starting control signal is not applied to the starting relay  500 . 
     Therefore, if the shift lever position is changed to the D or R position when the engine is started, the vehicle does not start. 
     As described above, according to the exemplary embodiments of the present invention, startability of a vehicle in very low temperatures is enhanced and the starting motor does not operate when the shift lever position is the D or R position. Therefore, stability and reliability may be enhanced since the vehicle is prevented from a quick start. 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.