Patent Publication Number: US-7717085-B1

Title: Virtual throttle position sensor diagnostics with a single channel throttle position sensor

Description:
FIELD 
     The present disclosure relates to replicating a throttle position sensor (TPS) signal during TPS signal diagnostics. 
     BACKGROUND 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     Referring now to  FIG. 1 , a prior art throttle control system  10  for use with an internal combustion engine  14  is shown. Throttle control system  10  includes a throttle body  12  that throttles air to the engine  14  based on a throttle control signal  16 . Throttle body  12  includes first and second throttle position sensors  18 ,  20  that generate respective throttle position signals. Each throttle position signal  18 ,  20  indicates the same degree of opening of throttle body  12 . Using the two throttle positions signals provides redundancy that improves self-diagnostic capabilities. An analog-to-digital converter module  22  digitizes each throttle position signals. A diagnostic module  24  compares the signals to each other and to predetermined diagnostic thresholds. Results of the comparisons indicate whether throttle position signals are valid or corrupted. Examples of corrupted signals include shorted to ground, shorted to a signal excitation voltage, and irrational. 
     Referring now to  FIG. 2 , a second embodiment is shown of a throttle control system  10 ′ having a single throttle position sensor. Dual throttle position sensors, such as that illustrated in  FIG. 1 , are typically not used. Currently, most vehicles use a single throttle position sensor  18  and an analog-to-digital converter  22  that generates a single throttle position sensor signal TP 1 . However, it is expected that the use of dual throttle position sensing systems will expand. However, single throttle position sensing systems will continue to be used for many years. 
     The diagnostic module  24 ′ includes diagnostics for diagnosing errors in the single throttle position signal whereas the diagnostic module  24  of  FIG. 1  includes diagnostics for sensing errors in two throttle position sensors. Developing and maintaining two sets of diagnostic codes is expensive since two sets of diagnostic codes and two sets of software codes must be maintained. 
     SUMMARY 
     The present disclosure allows a common configuration for providing diagnosis for both one- and two-throttle position sensor systems. 
     In one aspect of the disclosure, a method includes receiving an encoded throttle position sensor signal from a throttle body, forming a first replicated throttle position sensor signal and a second replicated second throttle position sensor signal from the encoded signal and communicating the first replicated throttle position sensor signal and the second throttle position sensor signal to a diagnostics module. 
     In a further aspect of the disclosure, a system includes a throttle body generating a throttle position sensor signal and encoding the throttle position sensor signal to form an encoded throttle position sensor signal. The system also includes an electronic control module receiving the encoded throttle position sensor signal from a throttle body, forming a first replicated throttle position sensor signal and a second replicated second throttle position sensor signal from the encoded signal and communicating the first replicated throttle position sensor signal and the second throttle position sensor signal to a diagnostics module. 
     Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a block diagrammatic view of a two-throttle position sensor throttle control system according to the prior art; 
         FIG. 2  is a block diagrammatic view of a single-throttle position sensor throttle control system according to the prior art; 
         FIG. 3  is a block diagrammatic view of a throttle control system according to the present disclosure; 
         FIG. 4  is a timing plot of a SENT signal according to the present disclosure; 
         FIG. 5  is a schematic view of the transmitter and the receiver of  FIG. 3 ; 
         FIG. 6  is a plot of percentage of reference voltage versus percent of throttle rotation for throttle position sensor measurements; 
         FIG. 7  is a flowchart of a method for operating the throttle position sensor and diagnostics associated therewith. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure. 
     As used herein, the term module refers to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
     Referring now to  FIG. 3 , a throttle body  110  includes a throttle  112 , a controlling motor  114  and two throttle position sensors  116  and  118 . As mentioned above, both one- and two-throttle position sensor systems are known. The present disclosure allows both single-throttle position sensor and dual-throttle position sensor systems. The signals generated by the throttle position sensor  1  (TPS 1 ) and throttle position sensor  2  (TPS 2 ) may be referred to as raw signals. An interface module  120  receives the signals from the throttle position sensors  116 ,  118  and ultimately communicates a representation of the signals to an electronic control module  122 . A transmitter module  124  is used to format and encode the throttle position sensor or sensor signals for communication to the electronic control module  122 . 
     The electronic control module  122  includes a receiver module  134  receiving the encoded throttle position sensor signals from the transmitter module  124 . It should be noted that the throttle body and thus the transmitter module  124  within the interface module  120  are separated physically within a vehicle. A bus or other connection  132  may be used to transmit the signals therebetween. A replication module  132  may also be included within the receiver module. The replication module may be used to replicate a second throttle position sensor signal should the system include only one throttle position sensor. The replication module  132  may also be used to form replicated throttle position sensor signals (replicated TP 1 , replicated TP 2 ). The replicated throttle position signals are communicated to a diagnostic module  134  that generates diagnostic trouble codes (DTC). The diagnostic trouble codes may be communicated to an external diagnostic reader  140 . 
     The electronic control module  122  may also include a control signal generator module  144 . The control signal generator module  144  may generate a control signal  146  that is used to control the motor  114  and thus operate and control the throttle  112 . The control signal generator module  144  may receive the replicated throttle signals and generate control signals in response thereto. 
     Referring now to  FIG. 4 , the signal from the transmitter module  124  to the receiver module  130  may include various formats. One suitable format is that described in the Society of Automotive Engineers (SAE) J2716 Report. In the following example, a signal message  200  for two 12-bit sensor values assuming a three microsecond clock tick is illustrated. A synchronization or calibration pulse  202  having a predetermined length may be provided so that corrections may be made for the transmitter clock variations. A status and communication portion  204  may also be provided. This portion may be reserved for a sensor or sensors to communicate various information such as part numbers or fault information. Various data for a first signal may be provided at signal/data portions  206 ,  208  and  210 . Data portions for a second signal may be provided at  212 ,  214  and  216 . A cyclic redundancy check or check sum portion  218  may also be provided within the signal  200 . The Signal1 portion and Signal2 portion may correspond to two throttle position sensor signals. Of course, in a one-throttle position sensor signal system, only one of the signal portions may be provided. 
     As can be seen by the above signal, a simpler lower-cost communication scheme is provided than that of the analog-to-digital signals produced in the prior art  FIGS. 1 and 2 . The sensor signals provided within the signal  200  may be transmitted as a series of pulses with data measured as a time between consecutive falling edges. It is envisioned that a throttle position sensor may have a defined sequence using a calibration pulse followed by a constant number of short “nibble” pulses. 
     Referring now to  FIG. 5 , the transmitter module  124  in communication with the receiver module  130  through wiring  132  is illustrated in further detail. A protocol generator or encoder  310  is used to encode the signals from the throttle position sensor or sensors into the proper format. As mentioned above, the SENT format which uses falling-edge-to-falling-edge timing to communicate data may be used. As illustrated, a 120 ohm resistor and a 2 nanofarad capacitor is in communication with an output pin  312  to attenuate RF energy on the external communication line  132 . The receiver module  130  may also include a resistance such as a 120 ohm resistor and a capacitance such as a 6 nanofarad capacitor to reduce radiated EMC emissions. The wiring may also include a power source signal line  314  and a ground signal line  316 . Other RF components may include another resistance such as resistor R f  and another capacitance such as capacitor C f  together with yet another resistance such as 10 kiloohm resistor. The 10 kiloohm resistor may be coupled between the reference voltage and the signal wire  318 . The resistor R f  and the capacitor C f  may be in series with the output pin and signal wire  318 . A CPU chip  320  may receive the signal line and generate a replicated throttle position sensor based upon the timing. In this example, the timing is determined between consecutive falling edges. The time between the falling edges may thus correspond to data. 
     Referring now to  FIG. 6 , the diagnostic module  134  illustrated in  FIG. 3  may generate diagnostic signals corresponding to the state of the replicated throttle position sensor signal or signals. Should only one throttle position sensor be present, the receiver module  130  generates a replicated second throttle position sensor signal that is the inverse of the first throttle position sensor signal. Thus, both of the throttle signals have a corresponding out-of-range signal. The first out-of-range signal is generated when the first throttle position sensor signal is too high or out of range high. The second out-of-range signal is generated when the second throttle position sensor is out of range low. Diagnostics, throttle waiting and remedial actions are well understood in response to various fault combinations. 
     Referring now to  FIG. 7 , a method for controlling the throttle and generating diagnostic signals is set forth. In step  410 , the throttle is generally controlled in response to a vehicle operator input such as an input from a throttle pedal. Throttle position signals may be generated at one- or two-throttle position sensors. In step  414 , a fault check may be performed on the throttle position sensor signal or signals. In step  416 , SENT signals may be encoded and communicated to the receiving module. As mentioned above, the SENT signals may have data corresponding to the time between falling edges of a signal. In step  418 , the SENT signals are communicated to the electronic control module and the receiver module therein. In step  420 , the time between the falling edges of the SENT signals is determined. In step  422 , the SENT signals are converted to replicated throttle position sensor signals. If only one throttle position sensor signal is provided, a second signal corresponding to the first signal is determined. The second signal may be an inverse signal corresponding to the first throttle position sensor signal. 
     After the SENT signals are converted to replicated signals corresponding to the original throttle position sensor signals, the replicated signals are communicated to the diagnostic module  134  of  FIG. 3  to determine any irregularities in the signals. Diagnostic codes may be set when comparing the various signals. 
     As can be seen by the above, a one-throttle position sensor system is converted into a two-throttle position signal system. Thus, common codes and software may be used in the diagnostic module  134 . The diagnostic module coding may thus be used for a single-throttle position sensor signal and a dual-throttle position sensor signal system without modification. 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification, and the following claims.