Electronic throttle control system for a vehicle

An electronic throttle control system is provided, which comprises an accelerator pedal position sensor, a control unit, and a biasing mechanism. The accelerator pedal position sensor detects a position of an accelerator pedal. The throttle actuator actuates a throttle valve to rotate. The control unit determines a target throttle position based on the accelerator pedal position, and controls an operation of the throttle actuator in accordance with the determined target throttle position. The biasing mechanism provides rotational force to the throttle valve such that an opening angle of the throttle valve while the throttle actuator is not powered is greater than a predetermined idle opening angle.

FIELD OF THE INVENTION

The present invention relates to an electronic throttle control system for the engine of a vehicle, and more particularly, to an electronic throttle control system in which the throttle valve is positioned to remain slightly open in case of a failure of the electronic throttle control system, in order to operate an engine at a predetermined speed.

BACKGROUND OF THE INVENTION

Generally, an electronic throttle control system determines a target throttle valve position, based on an accelerator pedal position and other engine operating parameters, and electronically regulates the position of the throttle valve. In a conventional electronic throttle control system the throttle valve is fully closed by a return spring when the throttle actuator is not powered. To draw air into the engine while the throttle valve is fully closed, a bypass line and a bypass valve are provided. The bypass valve closes or opens the bypass line. If the bypass valve is opened, air is induced into the engine even while the throttle valve is fully closed. Thus, the engine may operate at a predetermined speed.

The conventional electronic throttle control system must include the bypass line and the bypass valve so that the engine can function in case of a throttle control system failure. The addition of the bypass valve and bypass line complicates the system. In addition, control of the bypass valve is needed, so the conventional electronic throttle control system becomes even more complicated. Furthermore, as the return spring wears, precise control of the position of the throttle valve becomes difficult.

SUMMARY OF THE INVENTION

An electronic throttle control system, in a preferred embodiment of the invention includes: an engine control unit, with the engine control unit determining a target throttle position based on engine operating parameters; an accelerator pedal position sensor, with the pedal position sensor sending a signal indicative of an accelerator pedal position to the engine control unit; a throttle control unit, with the throttle control unit operating a throttle actuator according to a target throttle position signal from the engine control unit; a throttle valve positioned by the throttle actuator to the target throttle position; a first return spring acting on the throttle valve in a closing direction; and a second return spring acting on the throttle valve in an opening direction, with the first return spring and the second return spring being positioned and configured to position the throttle valve at an emergency position if the throttle control system fails.

Preferably, the second return spring is a coil spring, with one end being connected to a spring seat while the other end is connected to a throttle body. The first return spring and the second return spring are connected to opposite sides of the spring seat. Preferably, the first spring is also a coil spring and the spring seat is a circular plate.

In another preferred embodiment of the invention the electronic throttle control system includes: an accelerator pedal position sensor for detecting a position of an accelerator pedal; a throttle actuator for actuating a throttle valve to rotate; a control unit for determining a target throttle position based on the accelerator pedal position, and for controlling the throttle actuator in accordance with the target throttle position; and a biasing mechanism providing rotational force to the throttle valve so that, if the throttle actuator is not powered, an opening angle of the throttle valve is greater than an idle opening angle.

Preferably, the biasing mechanism includes: a connecting shaft fixedly connected to the throttle valve; a spring seat fixedly connected to the connecting shaft; a first return spring connected between the spring seat and a throttle body such that the first return spring urges the throttle valve to rotate in a closing direction; and a second return spring connected between the spring seat and the throttle body such that the second return spring urges the throttle valve to rotate in an opening direction.

A further preferred embodiment of the throttle control system includes: a throttle valve at a throttle position; a throttle valve actuator for positioning the throttle valve according to a target throttle position signal; a control unit for determining a target throttle position and for controlling the throttle valve actuator to position the throttle valve at the target throttle position; an accelerator pedal position sensor for detecting an accelerator pedal position and communicating the accelerator pedal position to the control unit, wherein the control unit determines the target throttle position based on the accelerator pedal position; a throttle position sensor for determining the throttle position and communicating the throttle position to the control unit; and a biasing mechanism, including a shaft, for positioning the throttle valve at an emergency position when the throttle control system fails.

Like numerals refer to similar elements throughout the several drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIG. 1, the electronic throttle control system according to a preferred embodiment of the present invention eliminates the bypass line, bypass valve, and the corresponding control. In the throttle control system an accelerator position sensor3detects a position of an accelerator pedal1. A control unit30determines a target throttle position based on the accelerator position and various engine operation conditions, such as engine speed (RPM), and directs the positioning of a throttle valve7. The control unit30, may include an engine control unit (ECU)5and a throttle control unit (TCU)9in communication with each other. The engine control unit5determines a target throttle position based on an output signal (for example, a voltage signal) of the accelerator pedal sensor3. The output signal of the accelerator pedal sensor3is indicative of the accelerator pedal position. The throttle control unit9controls a throttle actuator (for example, a motor, or a stepper motor)11according to a target throttle position signal input from the engine control unit5. The throttle valve7is moved by the throttle actuator11to the target throttle position.

The engine control unit5and the throttle control unit9preferably include a processor, a memory, and other necessary hardware and software components, as will be understood by persons of ordinary skill in the art, to permit the control unit to communicate with sensors and execute the control function as described herein. The engine control unit5receives the throttle position signal from the throttle position sensor13, and determines the throttle position.

The electronic throttle control system according to a preferred embodiment of the present invention also includes a biasing mechanism20for positioning the throttle valve7slightly open when the throttle actuator11does not operate, due to, for example, system failure or loss of power. The biasing mechanism20includes a first return spring15that urges the throttle valve7to rotate in a closing direction. A second return spring17urges the throttle valve7to rotate in an opening direction. The biasing mechanism20further includes a connecting shaft21, and a spring seat23having a circular plate shape.

The spring seat23is fixedly connected to the connecting shaft21that is itself fixedly connected to the throttle valve7. The first return spring15is disposed on one side of the spring seat23, and the second return spring17is disposed on an opposite side of the spring seat23. One end of the first return spring15is connected to the spring seat23, and the other end of the first return spring15is connected to the throttle body19. The first return spring15is arranged to bias the spring seat23to rotate in a closing direction. Similarly, the second return spring17connects the spring seat23and the throttle body19such that the spring seat23is biased to rotate in an opening direction.

As shown inFIG. 2, both the first return spring15and the second return spring17are preferably coil springs. The number of winds of the first return spring15is greater than that of the second return spring17so that the throttle is positioned slightly open while the throttle actuator11is not powered. That is, the first return spring15generates a lesser rotating force than the second return spring17so that the first and second return springs15and17position the throttle valve7slightly open when the throttle actuator does not operate. This slightly open state of the throttle valve7can be referred to as an emergency state of the throttle valve7, that allows the engine to operate at a predetermined speed.

Referring toFIG. 3, the first return spring15is connected between an inner side (left side inFIG. 3) of the spring seat23and the throttle body19, and the second return spring17is connected between an outer side (right side inFIG. 4) of the spring seat23and the throttle body19. While the electronic throttle control system is not powered (that is, the throttle actuator11(FIG. 1) does not operate), the throttle valve7is positioned slightly open by the equilibrium of the rotating forces of the first return spring15and the second return spring17. As shown inFIG. 4, it is preferable that the opening angle of the throttle valve7is a predetermined opening angle α when the throttle actuator11does not operate, or fails. To operate the engine at the predetermined speed while the throttle actuator is not powered, it is further preferable that the predetermined opening angle α is greater than a predetermined idle opening angle β, shown inFIG. 5, where the engine idles.

In a high acceleration state, shown inFIG. 6, the throttle opening angle becomes greater than the idle opening angle. Thus, it is preferable that the predetermined opening angle α is set as a value at which the engine can be operated at the predetermined speed, enabling the vehicle to move.

Returning toFIG. 1, if a signal indicative of the position of the accelerator pedal1is input to the engine control unit5, the engine control unit5determines a target throttle opening angle based in part on the accelerator pedal position, and outputs the corresponding signal. The throttle control unit9controls the throttle actuator11to actuate the throttle valve7such that the throttle valve7is positioned in the target position (for example, in an acceleration position, in a deceleration position, or in an idle position), based on the signal of the engine control unit5. If the electronic throttle control system is not powered due to a failure of the electronic throttle control system, the throttle valve7is positioned to be slightly open (where the throttle valve angle is α) by the resultant force of the rotating forces provided by the first return spring15and the second return spring17.

Consequently, the bypass line that is needed to operate the engine in case of the failure of a conventional throttle control system may be removed. This decreases the manufacturing cost of the electronic throttle control system. Furthermore, the bypass valve that is disposed in a bypass line may also be removed so that the overall control of the electronic throttle control system becomes simpler and, therefor, the possibility of failure decreases.

Although preferred embodiments 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 sprit and scope of the present invention, as defined in the appended claims.

Throughout this specification and the claims which follow, unless explicitly described to the contrary, the word “comprise” or variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.