Title of Invention

AN AUTOMATIC CHOKE SYSTEM FOR AN AUTOMOBILE

Abstract

An automatic choke system for an automobile comprising a microcontroller provided with a timer and a comparator, the timer for being activated and deactivated by the comparator, the timer once activated being automatically de-activated on the expiry of a , predetennined interval of time; switching means connected to an electrically operated choke the switching means being turned ON and OFF by the timer in its activated and de-activated states respectively, to open and close the said choke; sensors for sensing the temperature and the rpm of the engine respectively, the comparator receiving, the output signals from the said sensors and activatmg the timer only If both - sensors sense the said temperature and rpm to be below respective predetennined values, the comparator otherwise not activating the timer and if the timer should already be in the activated state de-activating the timer.

Full Text

This invention relates to an automatic choke system far an automobil#. The automatic choke system proposed herein, which replaces the manual choke, improves the cold-start ability of the engine and saves fuel. Time and temperature dependent choke systems which turn on and off automatically after lapse of a specified interval of time are known to the art. However euch chokes are not efficient because they remain DN for a given interval of time whether or not there is any nued to do so e.g. when the engine has already started wi thin such interval of time. On the other hand the automatic choke system proposed herein is not merely time dependent, but also dependent an the temperature of the engine and i ts rpm so much- so that the said choke system operates "intelligently", economically and efficiently. In other words, the automatic choke system proposed herein will not operate if the engine temperature is above a predetermined value OR if the engine rpm is above a predeterminal value OR if, after going into operation, a predetermined interval of time elapses. Thus, the operation of the automatic choke system proposed herein 1B governed by the three conditions aforesaid. If the engine temperature is above a given value, the proposed automatic choke system will not be operative because a choke is not intended for use at such temperature level. By "engine temperature" is meant the temperature of the engine taken at any convenient location, such as, for examp 1e , the engine block temperature. Then again if the rpm of the engine is above a given value, the automatic choke system proposed herein will not operate, since rpm above the given value would indicate that the engine has started. The rpm of the engine is conveniently determined as being related to the rpm of the magneto in a vehicle, such as, a scooter or the rpm of the dynamo in a vehicle such as a motor car. The automatic choke system proposed herein will cease to operate after the said system has been in operation over a given interval of time, because much interval of time is considered sufficient for the engine to start, if it can start at all. Various other features of the automatic choke system proposed here will be discernible from the following further description thereof set out hereunder. The automatic choke system for an automobile, according to this invention, comprises a microcontroller provided wi th a timer and a comparator, the timer for be ing activated and de-activated by the comparator, the timer once activated being automatically de-activated on the expiry of a predetermined interval of time; switching means connected to an electrically operated choke, the switching means being turned DM and OFF by the timer in its activated and de-activated states, respectively, to open and close the said choke; sensors for sensing, the temperature and the rpm of the eng ine, respectively, the comparator receiving the output signal© from the said sensors and aeti vating the timer only if both sensors sense the said temperature and rpm to be below respective predetermined values, the comparator otherwise not activating the timer. This invention will now be described in further detail by referring to the accompanying drawings the single Figure in which i1 lustrates by way of example, and not by way of limitation, one of various possible embodiments of the automatic choke system proposed herein. The microcontroller M is provided with a timer T and a comparator C. The timer is activated and de-activated by the comparator in the c ircumstances set out herein. 8 is the battery of the said system. The timer is set for a predetermined interval of time, say, A seconds so that once the timer is activated by the microcontroller M. the timer remains in the activated state and thereafter automatically gets de~ activated on the expiry of A seconds, unless before the expiry of the said interval of A seconds the comparator C de-activates it. Switching means are connected to an electrically operated choke, such as, a solenoid choke B, the switching means being turned ON and OFF by the timer T in its activated and de-activated states, respectively, to open and close the said choke 0. In the embodiment i1 lustrated the switching means, in one of i ts possible forms, is exemplified by the transistor switch S connected to the timer T and the solenoid choke Q. Sensors F and " are provided for sensing, the temperature and the rpm of the engine, respect i vely, the comparator C receiving the output signals from the said sensors and activating the timer T only if both sensors sense the said temperature and rpm to be below respective predetermined values D and E. In the embodiment illustrated, the sensor H is the charging coi1 K of the magneto W. The comparator C does not otherwise activate the timer T. Once both the sensors simultaneously satisfy the conditions stated above, the comparator C activates the timer T which then turns the switch 3 ON to open the solenoid choke 6 to supply a rich fuel mixture to the engine, through the carburetor. The timer T will remain in the activated state until expiry of the predetermined interval of A seconds, before turning the switch S OFF and thereby closing the choke B. However, during this interval of A seconds (when the timer T is in the activated state) should the temperature of the engine become equal to or greater than D or if the rpm of the engine become equal to or greater than E the comparator C mi 11 switch off the timer T even though the predetermined interval of A seconds of the timer has not 1apsed. The automatic choke system becomes ready for use when the user cranks the engine by k icfc starting or by the use Df a starter motor. If the engine starts either at the first attempt or later, the rpm of the engine corresponding to the rpm of the magneto W or dynamo produces a related voltage at the output of the charging coil K twhich itself acts as the sensor H> corresponding to the engine speed and if this is equal to or above the value E, it indicates that the engine has started. The output voltage of the charging coil K is received by the comparator, which does not then activate the timer T, since the indication is that the engine has started and there is no need for the choke B to come into operation, On the other hand, if the voltage value at the output of the charging coil K indicates engine rpm below E which would be the case if the engine is not running, such value would be indicative of the engine not having started. In such a case, the comparator C would activate the timer T, which in turn would turn ON the switch S to result in the choke G being made to open and furnish a rich fuel mixture to the engine. However, in such event, the timer T will be in an activated state only for A seconds, during which the choke G will also be ON. On the expiry of A seconds, the timer T is automatically de-activated even if the engine has not started. Consequently the switch S is OFF and the choke closed. This is so because the predetermined interval of A seconds is so seleeted The temperature sensor F e.g. a negative temperature coefficient sensor senses the temperature of the engine e.g. the temperature of the engine block of the engine. The voltage of the said sensor is fed to the comparator C. Whenever the temperature sensed by the sensor T is below the value D (e.g.25 deg. C) the comparator will activate the timer T to turn the switch S ON and thus energUe the solenoid choke G to result in a rich fuel mixture being fed to the engine through the carburetor. As already explained above, such a state will last only over the predetermined interval of A second* during which the timer T will be in ita activated state. On expiry of A seconds, the time is deactivated, the switch S turns OFF and consequently the solenoid choke 0 will also turn OFF. This is so regardless of the fact that the engine might not have started. The reasons as to why this is so have been gi ven above with regard to sensing of the eng ine rpm. What is important to note is that if the comparator is to act ivate the timer to cause the choke to open, both the sensors F and H will have to register a sensed value of temperature and speed 1 ess than values D and E. So also after the timer T has been activated, and one of the sensors registers a sensed value of 1 ess than D or 1 ess than E, the comparator C de-activates the timer T although A seconds may not have been completed. The terms and expressions in this specification are of description and not of limitation, there being no intention in the use of such terms and expressions of excluding any equivalents of the features illustrated and described, but it is understood that various other embodiments of the automatic choke system are possible without departing from the scope and ambit of this invention. We Claim: 1. An automatic choke system for an automobile comprising a microcontroller provided with a timer and a comparator, the timer for being activated and deactivated by the comparator, the timer once activated being automatically de-activated on the expiry of a predetermined interval of time; switching means connected to an electrically operated choke the switching means being turned ON and OFF by the timer in its activated and de-activated states respectively, to open and close the said choke; sensors for sensing the temperature and the rpm of the engine respectively, the comparator receiving the output signals from the said sensors and activating the timer only if both sensors sense the said temperature and rpm to be below respective predetermined values, the comparator otherwise not activating the timer and if the timer should already be in the activated state de-activating the timer. 2. An automatic choke system as claimed in Claim 1 wherein the sensor for sensing the rpm of the engine consists of the charging coil of the magneto or dynamo of the automobile. 3. An automatic choke system as claimed in Claiml or Claim 2 wherein the switching means consist of a transistor switch. 4. An automatic choke system as claimed in any one of the preceding Claims wherein the electrically operated choke is a solenoid choke. 5. An automatic choke substantially as herein described with reference to and as illustrated in the accompanying drawings.

Documents:

0831-mas-2002 abstract.pdf

0831-mas-2002 claims duplicate.pdf

0831-mas-2002 claims.pdf

0831-mas-2002 correspondence-others.pdf

0831-mas-2002 correspondence-po.pdf

0831-mas-2002 description (complete) duplicate.pdf

0831-mas-2002 description (complete).pdf

0831-mas-2002 drawings.pdf

0831-mas-2002 form-1.pdf

0831-mas-2002 form-19.pdf

0831-mas-2002 form-26.pdf

0831-mas-2002 form-3.pdf