Abstract:
A vehicle throttle locking circuit and method are provided. A control unit receives detection voltages from a pedal sensor and, when a clamping actuation signal is ON, digital clamping voltages are gradually reduced according to the detection voltages. AD/A conversion unit converts the digital clamping voltages to analog clamping voltages. A variable voltage clamping unit clamps the detection voltages according to the analog clamping voltages. The gradual reduction of the digital clamping voltages are stopped when the detection voltages are already clamped at an idle condition so that the pedal is effectively locked at the idle condition. As such, the present invention not only provides anti-theft function, but also avoids traffic accident and hazard to the safety of the driver or passers due to the vehicle&#39;s sudden loss of power.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    (a) Technical Field of the Invention 
         [0002]    The present invention is generally related to anti-theft devices for vehicles, and more particular to a throttle locking circuit and a related method providing both anti-theft and road safety functions. 
         [0003]    (b) Description of the Prior Art 
         [0004]    Motor vehicles satisfy people&#39;s traveling requirement and provide people great convenience. However, vehicle theft is always a concern to vehicle owners. 
         [0005]    To address this concern, vehicle anti-theft devices equipped on the vehicles are widely popular. In early days, these devices aim at providing alarms to alert vehicle owners so as to deter the burglars. However the effectiveness of these devices is only limited. 
         [0006]    Therefore, there are teachings that cut off a stolen vehicle&#39;s power to prevent the stolen vehicle from getting away. These are effective means. However, there are safety concerns as a vehicle suddenly losing its power may cause harm to people around. 
         [0007]    To overcome this issue, R.O.C. Taiwan Patent No. M466837 teaches an anti-theft device that disables a vehicle&#39;s throttle. But the control unit of the teaching encounters difficulty in implementation and further improvement is required. 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, an objective of the present invention is to provide a vehicle throttle locking circuit and method so that both anti-theft and driving safety are effectively achieved. 
         [0009]    To achieve this and other objectives, the throttle locking circuit is applied to a vehicle equipped with an accelerator pedal sensor and an Electronic Control Unit (ECU). The pedal sensor outputs detection voltages corresponding to a depth of the pedal being stepped on to the ECU. 
         [0010]    The throttle locking circuit includes a control unit, a digital-analog (D/A) conversion unit, and a variable voltage clamping unit. The control unit is coupled to the pedal sensor for receiving a clamping actuation signal and, when the clamping actuation signal is ON, outputting digital clamping voltages according to the detection voltages. The D/A conversion unit is coupled to the control unit for converting the digital clamping voltages into analog clamping voltages. The variable voltage clamping unit is coupled to the D/A conversion unit for clamping the detection voltages according to the analog clamping voltages. 
         [0011]    In one embodiment, the detection voltages include a high voltage and a low voltage. The digital clamping voltages include a high digital value and a low digital value. The control unit outputs the digital clamping voltages of the high digital value and the low digital value in accordance with the high and low voltages of the detection voltages. 
         [0012]    In one embodiment, the D/A conversion unit includes two D/A converters converting the digital clamping voltages of the high digital value and the low digital value into analog clamping voltages including a high analog clamping voltage and a low analog clamping voltage, respectively. 
         [0013]    In one embodiment, the variable voltage clamping unit includes two variable voltage clamping circuits clamping the high and low voltages of the detection voltages according to the high and low analog clamping voltages, respectively. 
         [0014]    In one embodiment, each variable voltage clamping circuit includes an operational amplifier, a first resistor, a transistor, and a second resistor. The operational amplifier has a positive input terminal, a negative input terminal, and an output terminal The negative input terminal directly or indirectly receives the high or low analog clamping voltage. The first resistor has an end coupled to the output terminal The transistor has its base coupled to another end of the first resistor and its emitter connected to ground. The second resistor has its two ends coupled to the collector of the transistor and the positive input terminal, respectively. 
         [0015]    In one embodiment, the high and low analog clamping voltages are differential voltages, respectively. Each variable voltage clamping circuit further includes a differential amplifier between one of the D/A converter and the negative input terminal of the operational amplifier for amplifying one of the differential voltages. 
         [0016]    In one embodiment, each differential amplifier includes a second operational amplifier, a third resistor, a second transistor, a fourth resistor, and a fifth resistor. The second operational amplifier has a positive input terminal, a negative input terminal, and an output terminal where the positive and negative input terminals receive the differential voltages, respectively. The third resistor has an end coupled to the output terminal of the second operational amplifier. The second transistor has its base coupled to another end of the third resistor and its emitter connected to ground. The fourth resistor has its two ends coupled to the collector of the second transistor and the positive input terminal of the second operational amplifier, respectively. The fifth resistor has its two ends coupled to the collector of the second transistor and a power source, respectively. 
         [0017]    The throttle locking method is for a vehicle equipped with an accelerator pedal sensor and an ECU where the pedal sensor outputs detection voltages corresponding to a depth of the pedal being stepped on to the ECU. The method includes the following steps. 
         [0018]    Firstly, digital clamping voltages are provided according to the detection voltages when a clamping actuation signal is ON. Secondly, the digital clamping voltages are converted to analog clamping voltages. And the detection voltages are clamped according to the analog clamping voltages. 
         [0019]    The detection voltages include a high voltage and a low voltage. The method further includes the step of determining and recording a type of the pedal sensor according to the high and low voltages of the detection voltages. 
         [0020]    The method further includes the step of adjusting and providing the digital clamping voltages according to relatively low values of the high and low voltages of the detection voltages and the type of the pedal sensor when the detection voltages suggest that the pedal is released to reduce speed so as to effectively lock the acceleration function of the pedal. 
         [0021]    Reducing to the digital clamping voltage is stopped when the detection voltages are already clamped at an idle condition so as to effectively lock the pedal at the idle condition. 
         [0022]    As described, the throttle locking circuit and method, when the clamping actuation signal is ON, gradually reduce the clamping voltages until the detection voltages are at an idle voltage. Therefore traffic accident and hazard to the safety of the driver or passers due to the vehicle&#39;s sudden loss of power are avoided. The present invention therefore not only provides anti-theft function, but also ensures driving safety. 
         [0023]    The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
         [0024]    Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is a functional block diagram showing a vehicle throttle locking circuit according to an embodiment of the present invention. 
           [0026]      FIG. 2  is a schematic diagram showing a variable voltage clamping circuit of  FIG. 1 . 
           [0027]      FIG. 3  is a flow diagram showing a vehicle throttle locking method according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
         [0029]      FIG. 1  is a functional block diagram showing a vehicle throttle locking circuit according to an embodiment of the present invention. As illustrated, the throttle locking circuit  10  is applied to a vehicle equipped with an accelerator pedal sensor  1  and an Electronic Control Unit (ECU)  2 . The pedal sensor  1  outputs detection voltages including a high voltage HV and a low voltage LV corresponding to a depth of the pedal being stepped on to the ECU  2  so that the ECU  2  is able to control the acceleration and speed of the vehicle. 
         [0030]    In  FIG. 1 , the throttle locking circuit  10  includes a control unit  11 , a digital-analog (D/A) conversion unit  21  including D/A converters  12  and  14 , and a variable voltage clamping unit  31  including variable voltage clamping circuits  13  and  15 . 
         [0031]    The control unit  11  is coupled to the pedal sensor  1  and receives a clamping actuation signal CV initiated by a user or by an anti-theft device. 
         [0032]    When triggered by the clamping actuation signal CV, the control unit  11  outputs digital clamping voltages including a high digital value (h) and a low digital value ( 1 ) in accordance with the detection voltages HV and LV. 
         [0033]    The digital clamping voltages of high digital value (h) and low digital value ( 1 ) output from the control unit  11  are converted by the D/A converters  12  and  14  of the D/A conversion unit  21  into analog clamping voltages including a high analog clamping voltage H and a low analog lamping voltage L, respectively. The variable voltage clamping circuits  13  and  15  of the variable voltage clamping unit  31  then clamp the high and low detection voltages HV and LV according to high and low analog clamping voltages H and L, respectively. 
         [0034]      FIG. 2  is a schematic diagram showing the variable voltage clamping circuit  13  or  15  of  FIG. 1 . As illustrated, the high and low analog clamping voltages H and L output from the D/A converters  12  and  14  are differential voltages. They are first amplified by a differential amplifier  131  of the variable voltage clamp circuit  13  or  15  positioned between the D/A converters  12  or  14  and an operational amplifier  1321 . The amplified result is then fed into a negative input terminal of the operational amplifier  1321  so as to conduct clamping to the detection voltages including the high and low voltages HV and LV. 
         [0035]    In  FIG. 2 , the differential amplifier  131  includes an operational amplifier  1311 , resistors  1313 ,  1314 , and  1315 , and a transistor  1312 . The operational amplifier  1311  has a positive input terminal, a negative input terminal, and an output terminal The positive and negative input terminals receive differential voltages of the high and low analog clamping voltages H and L, respectively. 
         [0036]    The resistor  1315  has an end coupled to the output terminal of the operational amplifier  1311 . The transistor  1312  has its base coupled to another end of the resistor  1315 , its emitter connected to ground, and its collector coupled to an end of the resistor  1313 . Another end of the resistor  1313  is coupled to the positive input terminal of the operational amplifier  1311 . The resistor  1314  has its two ends coupled to the collector of the transistor  1312  and a power source, respectively. 
         [0037]    The high and low analog clamping voltages H and L amplified by the differential amplifier  131  are fed into the negative input terminals of the operational amplifiers  1321  of the variable voltage clamping circuits  13  and  15 . Or, if the high and low analog clamping voltages H and L output from the D/A converters  12  and  14  are not differential voltages, they may be fed directly into the negative input terminals of the operational amplifiers  1321  of the variable voltage clamping circuits  13  and  15 . The clamping to the detection voltages including the high and low voltages HV and LV are then conducted. 
         [0038]    As shown in  FIG. 2 , in addition to the optional differential amplifier  131 , the variable voltage clamping circuit  13  or  15  further includes an operational amplifier  1321 , resistors  1323  and  1324 , and a transistor  1322 . The operational amplifier  1321  has a positive input terminal, a negative input terminal, and an output terminal The negative input terminal receives the high or low analog clamping voltages H or L, respectively. The resistor  1324  has an end coupled to the output terminal of the operational amplifier  1321 . The transistor  1322  has its base coupled to another end of the resistor  1324 , its emitter connected to ground, and its collector coupled to an end of the resistor  1323 . Another end of the resistor  1323  is coupled to the positive input terminal of the operational amplifier  1321 . 
         [0039]      FIG. 3  is a flow diagram showing a vehicle throttle locking method according to an embodiment of the present invention. Firstly, in step  301 , a control unit  11  accesses detection voltages including a high voltage HV and a low voltage LV from an accelerator pedal sensor  1 . The process then enters step  302 , and a status of the pedal is determined. If the vehicle is idle and the pedal is not stepped on, the process returns to step  301 . Otherwise, the process enters step  303  and a type of the pedal sensor  1  is determined and recorded according to variations of the high and low voltage HV and LV. The initialization of the process is completed at this stage. 
         [0040]    In general, the pedal sensor  1  may be of one of the following types. Firstly, the pedal sensor  1  may be of a parallel type where the high and low voltages HV and LV of the detection voltages have an identical initial value for idle and identical increments. For example, the high and low voltages HV and LV both vary within the same range between 0.3V and 4V. Secondly, the pedal sensor may be of a fixed parallel type where the high and low voltages HV and LV of the detection voltages have different initial values for idle but identical increments. For example, the high voltage HV varies within a range between 1.6V and 4V whereas the low voltage LV varies within a range between 0.8V and 3.2V. Thirdly, the pedal sensor may be of a multiple type where the high and low voltages HV and LV of the detection voltages have different initial values and different increments but one is a multiple of the other. For example, the high voltage HV varies within a range between 0.7V and 4V whereas the low voltage LV varies within a range between 0.35V and 2V. 
         [0041]    Therefore, step  303  is able to determine and record the type of the pedal sensor  1  according to variations of the high and low voltage HV and LV for subsequent steps. 
         [0042]    In step  304 , whether a clamping actuation signal CV is initiated is determined. If the clamping actuation signal CV is not initiated, the process returns to step  304 . Otherwise, the process enters step  305  where the high and low voltages HV and LV of the detection voltages output from the pedal sensor  1  is accessed. Then, in step  306 , whether the pedal is released to reduce speed is determined. If the pedal is not released to reduce speed, the process enters step  308 . Otherwise, if the pedal is released to reduce speed, the process enters step  307  where digital clamping voltages are adjusted according to relatively low (or high) values of the high and low voltages HV and LV and the type of the pedal sensor  1  recorded in step  303 , and output the digital clamping voltages. 
         [0043]    For example, if the pedal sensor  1  is of the parallel type, and the high and low voltages HV and LV are both 3.6V before the pedal is released, and the high voltage HV becomes 3.0V and the low voltage LV becomes 2.9V after the pedal is released, step  307  adjusts and output digital clamping voltages so that the high and low voltages HV and LV are both clamped at the relatively low value 2.9V. 
         [0044]    If the pedal sensor  1  is of the fixed parallel type, and the high and low voltages HV and LV are 3.6V and 2.8V, respectively, before the pedal is released, and the high voltage HV becomes 3.0V and the low voltage LV becomes 2.1V after the pedal is released, step  307  adjusts and output digital clamping voltages so that the high and low voltages HV and LV are clamped at the relatively low values 2.9V and 2.1V, respectively. 
         [0045]    If the pedal sensor  1  is of the multiple type, and the high and low voltages HV and LV are 3.6V and 1.8V, respectively, before the pedal is released, and the high voltage HV becomes 3.0V and the low voltage LV becomes 1.4V after the pedal is released, step  307  adjusts and output digital clamping voltages so that the high and low voltages HV and LV are clamped at the relatively low values 2.8V and 1.4V, respectively. 
         [0046]    In step  308 , whether the clamping actuation signal CV is still ON is determined. If it is not ON, the process enters step  310  and clamping to the high and low voltages HV and LV are released so that the vehicle is restored a normal driving condition. Otherwise, the process enters step  309  and whether the detection voltages are already clamped at an idle condition is determined. If yes, the process returns to the step  308  so as to wait for the clamping actuation signal CV to be OFF and to release the clamping to the high and low voltages HV and LV. Otherwise, the process enters step  305  and repeats a next cycle of operation. 
         [0047]    While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the claims of the present invention.