Title of Invention

APPARATUS FOR ROAD SPEED LIMITING

Abstract

The present invention relates to an effective method and apparatus for vehicle speed control by limiting the speed of the vehicle to a maximum road speed set. More particularly, the invention relates to a tamper proof system for vehicle speed control. The invention also provides for method and apparatus which can be fitted to the automobiles like trucks, buses and other heavy vehicles without disturbing any of the original fitments.

Full Text

PATENT APPLICATION NO: 620/CHE/2004 APPARATUS FOR ROAD SPEED LIMITING BACKGROUND OF THE INVENTION FIELD OF INVENTION The present invention relates to an effective method and apparatus for vehicle speed control by limiting the speed of the vehicle to a maximum road speed set. More particularly, the invention relates to a tamper proof system for vehicle speed control. DESCRIPTION OF PRIOR ART Road speed limiting device are well known in the contemporary art. Speed limiting systems are used for reasons of economy and safety. Speed limitation reduces the amount of fuel consumption during vehicle operation. Speed limitation also minimizes the overall vehicle maintenance particularly that required by the engine. Further, speed limitation increases vehicle operating safety through adherence of posted speed limits. Speed limiter devices limit the speed of the vehicle to a predetermined maximum. Speed limiting is typically accomplished by either a fuel bypass, a shutdown lever, or engine oil pressure control means. In the past, speed limiter devices have been used and proposed to limit the speed of motor vehicles, and some of these prior art devices are generally complex, difficult to construct and install, and are inefficient and often unsafe to use. Specifically, some prior art devices are susceptible to manipulation by the operator to exceed the preset maximum speed limit. This practice, referred to as "teasing", involves repeatedly accelerating and decelerating the vehicle by depressing and releasing the accelerator pedal. These prior art devices have a long lag period before regaining control of the speed. This allows the PATENT APPLICATION NO: 620/CHE/2004 vehicle speed to overshoot the speed limit momentarily, thereby increasing the average speed of the vehicle over the cycle of teasing. Such practices are inherently unsafe. Some prior art devices are ineffective at limiting the vehicle speed to the preset maximum, particularly under windy weather conditions, heavy loads, steep grades or fast acceleration. These devices cause the vehicle to surge under these condhions. The surge phenomenon is both uncomfortable for the operator and unsafe. Other prior art speed limiting devices provide rough and inaccurate speed limitation which results in disconcerting speed variations. Such variations lead to operator dissatisfaction and rejection of the use of the device. Conventional road speed limiting devices use techniques relating to pneumatic systems or mechanical limiters, and these road speed limiting devices can be easily tampered which result in device failure. Further, existing road speed limiting devices pose inherent limitations on the smooth operation, especially during transitions from a constant speed to the limited speed which also reduces the fuel efficiency. Despite the need for a speed limiter device in the art which provides efficient and reliable speed limitation for vehicles, which is simple to manufacture, install and use, and which overcomes the limitations and problems of the prior art, none insofar as is known has been proposed or developed. Whereby, it is desirable to provide a road speed limiting device and system which would avoid the problems noted above with respect to effective, smooth and tamper proof operation and overcome other problems encountered in conventional road speed limiting devices. PATENT APPLICATION NO: 620/CHE/2004 SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved road speed limiting device and method that overcomes many of the disadvantages of the prior art road speed limiting devices. The object of the present invention is attained by a novel tamper proof road speed limiting system of the present invention. It is another object of the present invention to provide a method and apparatus which can be fitted to the automobiles like cars, trucks, buses and other heavy vehicles. It is yet another object of the present invention to provide a road speed limiting device that provides for the speed to be limited to a set level (like 40 km/hr, 60 km/hr etc.) and ensuring that no tampering can be done to exceed the set limit at any point of time. It is accordingly an object of the present invention to provide an improved road speed limiting devices and method of manufacturing the road speed limiting device. Accordingly, it is an object of the present invention to provide a speed limiting device which reliably adheres to a predetermined maximum under a variety of weather, load, grade and acceleration conditions. It is another object of the invention to provide a road speed limiting device that can be retrofitted to any vehicle without disturbing any of the original fitments. According to yet another aspect the invention provides a limp-home mode if there is a failure in the arrangement or incase of tampering. PATENT APPLICATION NO: 620/CHE/2004 It is still a another object of the present invention to provide a road speed limiting device that offers smoother transition during the limiting action as well as in normal conditions than that has heretofore been achieved. In accordance with a further aspect of the present invention, the system ensures a constant speed resulting in an increase in the fuel efficiency of the vehicle. It is a further object of the present invention to provide a speed limiter which is not susceptible to overshoot and droop. Also, it is an object of this invention to provide a speed limiter which is compact, unitary and easy to manufacture, install and maintain. These and other features of the present invention will be disclosed and are apparent from the following detailed description of preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, may be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and is therefore not to be considered limiting of the invention's scope as it may admit to other equally effective embodiments. Fig.l illustrates the overview of the proposed road speed limiting system PATENT APPLICATION NO: 620/CHE/2004 PREFERRED EMBODIMENTS The present invention provides a speed limiter system for use with the fuel pump throttle of a motor vehicle and which limits the speed of the motor vehicle to a predetermined level. The speed limiting system consists of the following: 1. A DC motor which controls the fuel inflow into the engine and restricts the speed to the maximum set point. 2. An electronic (micro controller based) system that controls the motor. 3. A mechanical linkage arrangement that couples the motor with the fuel flow system of the engine of the vehicle. 4. A clutch arrangement. 5. A speed sensor. Fig.l illustrates the overview of the proposed road speed limiting system. The Electronic control system (1) comprises a speed sensor (2) attached to a dc motor (3) which provides outputs of variable signals which are a function of the speed of the vehicle. The DC motor (3) controls the fuel inflow into the engine and restricts the speed to the maximum set point. The limiter system further comprises a mechanical linkage (4) arrangement which is a spring rod assembly. The mechanical linkage (4) arrangement couples the motor with the fuel flow system (5) of the engine throttle of the vehicle to control the speed. Control function is obtained by controlling the acceleration pedal/fuel input. The dc motor (3) has a clutch arrangement and a worm gear arrangement for locking the output arm for power efficiency. The worm gear has a gear ratio of 1:800 for fine and sensitive movements. A helical gear arrangement is used for reduced backlash error. The inbuilt clutch mechanism ensures a small speed only, when the supply to electronic unit is cut or supply to motor (4) is cut making it tamper proof The control cable and a dc PATENT APPLICATION NO: 620/CHE/2004 motor (3) provide a simple arrangement between acceleration pedal and fuel input to limit the speed. The dc motor (3) is controlled by an electronic control system (1) which is a micro controller (6) based electronic system using special PID algorithm (Proportional Integral Derivative Algorithm) which is a real time closed loop system that ensures smooth transition and stabilization at the set speed levels. The electronic control system is electrically powered and has a memory and a stored program for program control of said micro controller and adjustment means. The speed sensor (2) can be either a hall-effect type or reed type or a combination of both. The speed sensor (2) comprises a magnetic reference means fixed to the vehicle drive shaft for rotation therewith, and stationary magnetic sensing means disposed adjacent to the reference means. The sensing means produces a variable output electrical signal, related to the rotational speed of the reference means, which represents the instantaneous speed of the vehicle. The micro controller (6) calculates the speed from the speed sensor (2) and the software compares the variable output signal from the speed sensor (2) with a preset reference signal which represents the maximum speed desired for the vehicle. The electronic control system (1) provides signals to limit vehicle speed when the vehicle speed reaches the preset limit. The electronic control (1) unit can be programmed for different speed limitations and hence cater to different segments (of speed requirements). PATENT APPLICATION NO: 620/CHE/2004 We claim 1. A tamper proof speed limiting device for limiting the speed of vehicles at a predetermined level, comprising: a. a micro controller based electronic system; b. a dc motor that is controlled by the electronic system; c. a spring rod assembly comprising the linkage means that transmits the acceleration from the pedal and couples the said d.c. motor with the vehicle fuel flow system of the engine throttle to control speed; d. said electronic system having a speed sensor that senses the speed of the vehicle and provides instantaneous outputs and adapted to control the fuel input upto a limited speed. 2. A speed limiting device of claim 1, wherein the said dc motor controls the fuel flow of the vehicle. 3. A speed limiting device of claim 1, wherein the said dc motor comprises: a. a worm gear arrangement for locking the output arm for power efficiency; b. a preset gear ratio for fine and sensitive movements; c. a helical gear arrangement for reduced backlash error; d. an inbuilt clutch mechanism. 4. A speed limiting device of claim 3, wherein the inbuilt clutch mechanism ensures small speeds only upto said limited speed, when the supply to electronic unit is cut or supply to motor is cut. PATENT APPLICATION NO: 620/CHE/2004 5. A speed limiting device of claim 1, wherein the micro controller has a memory and a stored program for program control of said micro controller, adjustment means, and a power supply connection. 6. A speed limiting device of claim 5, wherein the micro controller based electronic system uses proportional integral derivative algorithm which is a real time closed loop system that ensures smooth transition and stabilization at the set speed levels. 7. A speed limiting device of claim 1, wherein the speed sensor is of Hall Effect type, or Reed type or a combination of both. 8. A speed limiting device of claim 3 wherein the gear ratio is approximately 1:800.

Documents:

620-che-2004-abstract.pdf

620-che-2004-assignement.pdf

620-che-2004-claims.pdf

620-che-2004-correspondnece-others.pdf

620-che-2004-correspondnece-po.pdf

620-che-2004-description(complete).pdf

620-che-2004-description(provisional).pdf

620-che-2004-drawings.pdf

620-che-2004-form 1.pdf

620-che-2004-form 13.pdf

620-che-2004-form 26.pdf

620-che-2004-form 3.pdf

620-che-2004-form 5.pdf