Throttle valve control system for internal combustion engine

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.

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.

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 S10. 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 S20. 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 S30. On the other hand, if it is
 determined that electrical control is not being performed in step S20, the
 ECU 42 sets the throttle valve control device to a mechanical mode in step
 S40.
 In step S10, 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 S50. 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 S60. On the other hand, if it
 is determined that electrical control is not being performed in step S50,
 the progress restarts.
 In the dual mode established in step S30, 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 S40, 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 S60, 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.