Abstract:
A throttle valve control system for internal combustion engines includes an accelerator pedal switch for detecting a depression amount of an accelerator pedal, an actuator for actuating a throttle valve according to electric signals from an ECU, an accelerator pulley fixedly mounted on a throttle spindle, and an accelerator cable one end of which is wound around the accelerator pulley and other end of which is connected to the accelerator pedal.

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a throttle valve control system for internal combustion engines and, more particularly, to an improved throttle valve control system for an Intelligent Speed Adaptation (ISA) system. 
     (b) Description of the Related Art 
     In recent years, much research and development have taken place regarding the concept of intelligent speed adaptation (ISA). Such a system is based on control of the throttle valve to restrict the injection of fuel into the engine when the vehicle reaches specific speed limit. 
     A conventional throttle valve control device for controlling fuel injection is shown in FIG.  4 . Reference numeral  2  in the drawing indicates the throttle valve control device. 
     The throttle valve control device  2  is provided in a throttle body  4 . The throttle valve control device  2  comprises a throttle valve  6 , a rotational throttle shaft  8  for actuating the throttle valve  6 , a first rotational plate  14  fixedly mounted at one end of the throttle shaft  8  and connected to an accelerator pedal  10  by an accelerator cable  12 , and a second rotational plate  22  fixedly mounted at the other end of the throttle shaft  8  and connected to a motor  18  via a throttle cable  20 . 
     The throttle valve control device  2  has two sources of operation, driver manipulation of the accelerator pedal  10  which operates the acceleration cable  12  then the first rotational plate  14 , and the motor  18  which is controlled by an ECU  16  and operates the throttle cable  20  and the second rotational plate  22 . Accordingly, the throttle valve control device  2  is operated in  3  operational modes: a manual mode, an automatic, and a dual mode. 
     In the manual mode, the throttle valve  6  is controlled by driver manipulation of the accelerator pedal  10 . In this case, the depressing force applied by the driver on the accelerator pedal  10  is transmitted to the throttle shaft  8  via the acceleration cable  12  and the first rotational plate  14 . That is, the first rotational plate  14  rotates in one direction in direct proportion to the degree to which the accelerator pedal  10  is depressed by the driver, and rotates in the other direction as the driver releases the depressing force on. At this time, although the motor  18  is connected to the second rotational plate  22 , the motor  18  does not affect accelerator pedal manipulation because the ECU  16  does not supply electricity to the motor  18  in the manual mode. 
     In the automatic mode, the throttle valve  6  is actuated by the motor  18  by control of the ECU  16 . In more detail, if the ECU  16  determines that the driver is not performing manual control of the throttle valve  6 , the ECU  16  operates the motor  18  by supplying electricity thereto according to a driving state of the vehicle determined on the basis of the data detected by various sensors on the vehicle. In this case, the rotational force of the motor  18  is transmitted to the throttle shaft  8  via the throttle cable  20  and the second rotational plate  22 . In the automatic mode, because the first rotational plate  12  is also fixedly connected to the throttle shaft  8 , the accelerator pedal  10  moves without driver manipulation of the same in accordance with the rotation of the throttle shaft  8  in the automatic mode, 
     In the dual mode, the throttle valve  6  can be controlled by both driver manipulation of the accelerator pedal  10  and the ECU  16 . That is, a counterforce to the acceleration pedal  10  is given whenever the driver tries to depress the accelerator pedal  10  beyond a predetermined level (i.e., beyond a level which would driver the vehicle past a specific speed limit). However, in the dual mode, since driver manipulation of the accelerator pedal  10  ultimately has priority over automatic control of the throttle valve  6 , it is not possible to control vehicle speed electrically if the driver continues to operate the accelerator pedal  10 . 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to solve the above problems of the prior art. 
     It is an object of the present invention to provide an improved throttle valve control system for limiting the speed of a vehicle according to signals from speed limit beacons installed on roads, whenever a driver tries to depress an accelerator pedal beyond a pre-set speed limit. 
     To achieve the above object, the throttle valve control system of the present invention comprises an accelerator pedal switch for detecting a depression amount of an accelerator pedal, an actuator for actuating a throttle valve according to electric signals from an ECU, an accelerator pulley fixedly mounted on a throttle spindle, and an accelerator cable one end of which is wound around the accelerator pulley and other end of which is connected to the accelerator pedal, wherein the actuator is directly mounted to the throttle spindle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention: 
     FIG. 1 is a perspective view of a throttle valve control device according to a preferred embodiment of the present invention; 
     FIG. 2 is a schematic view of the throttle valve control device of FIG.  1 . 
     FIG. 3 is a flowchart describing an operation of the throttle valve control device of FIG. 1; and 
     FIG. 4 is a perspective view of a conventional throttle valve control device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will be described hereinafter with reference to the accompanying drawings. 
     FIG.  1  and FIG. 2 are respectively a perspective and schematic view of a throttle valve control device of the present invention. 
     As shown in FIG.  1  and FIG. 2, a throttle disc  32  is fixedly mounted at one end of a throttle spindle  34  for opening and closing a throttle bore (not shown), and a motor  44  which is controlled by an ECU  42  is directly mounted at the other end of the throttle spindle  34  for operating the throttle disc  32 . An accelerator pulley  40 , connected to an accelerator pedal  36  via an accelerator cable  38 , is fixedly mounted on the throttle spindle  34  between the throttle disc  32  and the motor  44 . The motor  44  is a step motor that can be controlled by electric signals. An accelerator pedal switch  46  is provided for detecting levels at which the accelerator pedal  36  has been depressed, after which corresponding data are sent to the ECU  42 . 
     An operation of the throttle valve control device of the present invention will now be described with reference to FIG.  3 . 
     First, the ECU  42  determines whether the accelerator pedal  36  is being operated by the driver in step S 10 . At this time, if the accelerator pedal  36  is being operated by the driver, the accelerator pedal switch  46  detects the amount the accelerator pedal  36  is depressed and sends a corresponding electric signal to the ECU  42 . If the depression of the accelerator pedal  36  is detected, the ECU  42  determines whether electrical control is being performed in step S 20 . If it is determined that electrical control is being performed, the ECU  42  sets the throttle valve control device to a dual mode in which the device is controlled both mechanically and electrically in step S 30 . On the other hand, if it is determined that electrical control is not being performed in step S 20 , the ECU  42  sets the throttle valve control device to a mechanical mode in step S 40 . 
     In step S 10 , if the ECU  42  determines that the accelerator pedal  36  is not being operated by the driver, then it is determined whether electrical control is being performed in step S 50 . If it is determined that electrical control is being performed, the ECU  42  sets the throttle valve control device to an electrical mode in step S 60 . On the other hand, if it is determined that electrical control is not being performed in step S 50 , the progress restarts. 
     In the dual mode established in step S 30 , electrical control has priority over mechanical control. That is, the power of the motor  44  is such that it is greater than the power that can be exerted on the accelerator pedal  36  by the driver. 
     Thus, while the ECU  42  controls the motor  44  based on the data of the depression amount of the accelerator pedal  36  detected by the accelerator pedal switch  46 , the driving of the engine is not affected by the depression amount of the accelerator pedal  36 , because the power from the depression amount of the accelerator pedal  36  is already reflected in the throttle spindle  34  by the motor  44  through control of the ECU  42 . 
     In the mechanical mode established in step S 40 , the electricity supplied to the motor  44  is cut by signals from the ECU  42  such that the throttle spindle  34  can freely rotate by driver manipulation of the acceleration pedal  36 . The throttle valve control device is set in the manual mode at speed levels below the pre-set maximal speed. 
     In the electrical mode S 60 , the throttle disc  32  is actuated by the motor  44  under the control of the ECU  42 . In this case, the accelerator pedal  36  moves according to the rotation amount of the motor  44  because the accelerator pedal  36  is connected to the throttle spindle  34  via the acceleration cable  38  and the acceleration pulley  40 . 
     Since the ECU  42  has priority control over the throttle disc  32 , when using the inventive throttle valve control device with an ISA system, the ECU  42  receives a wireless signal of maximal speed from beacons installed in a specific area and ensures that the vehicle does not exceed the speed limit in that area even if the driver depresses the accelerator pedal  36  past a level that would beyond the speed limit. 
     In the throttle valve control device of the present invention, the motor is directly connected with the throttle spindle such that the throttle valve opening can be precisely adjusted. Also, since the throttle valve control device is simple in structure through the use of one throttle pulley and one throttle cable by directly connecting the motor with the spindle disc, the weight and size of the device is reduced and its manufacturing costs are minimized. 
     Also, the throttle valve control device according to the present invention is ideal for application with an ISA system because the ECU controls the throttle valve to fully ensure the pre-set speed limit even if the driver tries to depress the accelerator pedal beyond a point that would drive the vehicle over the speed limit. 
     Although preferred embodiment of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims.