Friday, September 26, 2014
Car Fuel Efficiency Enhancer Circuit
The presented fuel efficiency enhancer circuit can be installed in your car dashboard and used for visualizing the optimal engine speed while driving, this will ensure that your car is never exceeds the higher or the lower inefficient regions of the specified engine speeds of your vehicle.
To augment the visual indication of the flashing red LEDs when the engine speed becomes too high, a tone generator (not exactly stereo hi—fi) has been provided. The generator is switched on and off in time with the red LEDs. Diode D6 applies the high level at the output of A4 to frequency·determining network R19/Fl20/C10. A 555 timer, lC3, connected as a rectangular-pulse oscillator generates an audio signal. As the output (pin 3) of IC3 is logic high during nonoperation, capacitor C11 has been connected in series with the loudspeaker: otherwise a constant direct current would flow through R21 and the loudspeaker. Resistor R21 limits the pulsating current during operation of the alarm. This shows yet another unwelcome aspect of the 555: it reacts to a low logic level at its input (pin 2) but not to a trailing edge, which in some cases would be very useful. As long as the voltage at pin 2 is smaller than 0.7 L the output of IC3 (pin 3) remains logic HIGH! This is something to bear in mind if ever you have difficulties with one of your own designs based on the 555
The basic setting (that of P1) has already been discussed: it is valid for most family cars with a maximum safe engine speed of around 6000 rev/min. Next, you need some information from your cars workshop manual. lf you have no copy of this, you should be able to get the information from the supplier or manufacturer.
What you need to know regarding this car fuel efficiency enhancer circuit is : a) maximum engine speed, Nmax rev/min; this value should never be exceeded to prevent possible serious damage to the engine; if you want to be kind to the engine, take the maximum rev/min for the present purpose at a somewhat lower value than that stated by the manufacturer; b) limits of the economic range, N] and N2 (see figure 47), of engine speed; depending upon the type of engine, these limits lie usually at 90. . .95 per cent of maximum moment. Here you have to be a little careful: when this range is kept too narrow (particularly with small engines), it will be difficult to drive within these limits. On the other hand, when it is too wide, you can hardly talk of an optimum range any more. If you have any doubts about all this, have a quiet word with the foreman or manager of your regular service station about where he thinks these limits lie.
Our sample engine had the following limits: N1 = 3000 rev/min; N2 : 4000 rev/min; Nmax : 5800 rev/min. c) the engine speed for a contact breaker frequency of 100 Hz. You may actually calculate this easily when you know how many cylinders your engine has and whether it is a four-stroke or a two-stroke type. If is the frequency of the contact breaker in Hz, N is the engine speed in rev/min, and Z is the number of cylinders, f = NZ/120 (four—stroke), orf = NZ/60 (two-stroke) Everything is now ready for the calibration. The setting of P2 (5 V at MP2) is the yardstick for all further settings: 5 V at l/IP2 correspond to Nmax = 5800 rev/min (set with P2); N1/Nmax 5 V = 3.1 V correspond to N1 = 3000 rev/min (set with P4); N2/Nmax 5 V = 3.8 V correspond to N2 = 4000 rev/min (set with P3). Calibration of the rev counter (strictly, frequency/voltage converter) has already been carried out with the 100 Hz generator.
Capacitor C2 should only be adapted to your vehicle if the engine (four cylinder and four-stroke) has a maximum speed of much higher than 6000 rev/min. The correct value for C2 is calculated from: C2n€W = 200/fmax x 68 nF = 6000 x 68/Nmax x Z nF Fitting the car fuel efficiency enhancer unit in the car is relatively simple. Plug PL1 must be connected be/7/hd the ignition switch so that the unit is only switched on when the ignition is on. Plug PL3 must be connected to a good earth/hg po/ht (=car body = negative terminal of battery). Plug PL2 must be connected to the contact breaker (take off at the ignition coil) with a screened cable. The screen of this cable must on/y be connected to earth in the economy indicator unit.
All cables should be fixed securely to prevent movement and away from moving or hot parts. As it may be that the value of R2 has to be adapted to your car, one of the LEDs may light momentarily totally independently from engine speed. This slight malfunction is soon put right by reducing the value of R2 in steps (minimum value 4k7). lf a rev counter is fitted in the car, you can readily check (and, if necessary, correct) the setting of P1. This can, of course, also be done at your local service station with a test rev counter.
lt’s up to you now to recover the cost of the economy indicator from improved petrol consumption, but, of course, the indicator cannot tell you whether your tyre pressures are correct, whether the engine timing is right, whether the carburettor is adjusted properly, and so on. And, need it be said, racing-type move offs from traffic lights, and screeching to a halt at the next set do not improve your consumption figures. You will soon get used to driving with an eye on your economy indicator and discover that you normally travel just as quickly economically as with those fast get·aways. The often heard remark that economy drivers are traffic obstacles is, you will find, totally unfounded.
lf your car has no space where you can mount the indicator in good view, get a small plastic case and just mount the LEDs in this. This little unit can then be mounted in the instrument panel and connected to the main unit (which is mounted anywhere there is space) by a suitable multi core cable. A tip. It is possible to fit two units (for instance, the economy indicator and the choke alarm) into one case for a very economical package. The two boards are kept separate by suitable spacers.
To augment the visual indication of the flashing red LEDs when the engine speed becomes too high, a tone generator (not exactly stereo hi—fi) has been provided. The generator is switched on and off in time with the red LEDs. Diode D6 applies the high level at the output of A4 to frequency·determining network R19/Fl20/C10. A 555 timer, lC3, connected as a rectangular-pulse oscillator generates an audio signal. As the output (pin 3) of IC3 is logic high during nonoperation, capacitor C11 has been connected in series with the loudspeaker: otherwise a constant direct current would flow through R21 and the loudspeaker. Resistor R21 limits the pulsating current during operation of the alarm. This shows yet another unwelcome aspect of the 555: it reacts to a low logic level at its input (pin 2) but not to a trailing edge, which in some cases would be very useful. As long as the voltage at pin 2 is smaller than 0.7 L the output of IC3 (pin 3) remains logic HIGH! This is something to bear in mind if ever you have difficulties with one of your own designs based on the 555
The basic setting (that of P1) has already been discussed: it is valid for most family cars with a maximum safe engine speed of around 6000 rev/min. Next, you need some information from your cars workshop manual. lf you have no copy of this, you should be able to get the information from the supplier or manufacturer.
What you need to know regarding this car fuel efficiency enhancer circuit is : a) maximum engine speed, Nmax rev/min; this value should never be exceeded to prevent possible serious damage to the engine; if you want to be kind to the engine, take the maximum rev/min for the present purpose at a somewhat lower value than that stated by the manufacturer; b) limits of the economic range, N] and N2 (see figure 47), of engine speed; depending upon the type of engine, these limits lie usually at 90. . .95 per cent of maximum moment. Here you have to be a little careful: when this range is kept too narrow (particularly with small engines), it will be difficult to drive within these limits. On the other hand, when it is too wide, you can hardly talk of an optimum range any more. If you have any doubts about all this, have a quiet word with the foreman or manager of your regular service station about where he thinks these limits lie.
Our sample engine had the following limits: N1 = 3000 rev/min; N2 : 4000 rev/min; Nmax : 5800 rev/min. c) the engine speed for a contact breaker frequency of 100 Hz. You may actually calculate this easily when you know how many cylinders your engine has and whether it is a four-stroke or a two-stroke type. If is the frequency of the contact breaker in Hz, N is the engine speed in rev/min, and Z is the number of cylinders, f = NZ/120 (four—stroke), orf = NZ/60 (two-stroke) Everything is now ready for the calibration. The setting of P2 (5 V at MP2) is the yardstick for all further settings: 5 V at l/IP2 correspond to Nmax = 5800 rev/min (set with P2); N1/Nmax 5 V = 3.1 V correspond to N1 = 3000 rev/min (set with P4); N2/Nmax 5 V = 3.8 V correspond to N2 = 4000 rev/min (set with P3). Calibration of the rev counter (strictly, frequency/voltage converter) has already been carried out with the 100 Hz generator.
All cables should be fixed securely to prevent movement and away from moving or hot parts. As it may be that the value of R2 has to be adapted to your car, one of the LEDs may light momentarily totally independently from engine speed. This slight malfunction is soon put right by reducing the value of R2 in steps (minimum value 4k7). lf a rev counter is fitted in the car, you can readily check (and, if necessary, correct) the setting of P1. This can, of course, also be done at your local service station with a test rev counter.
lt’s up to you now to recover the cost of the economy indicator from improved petrol consumption, but, of course, the indicator cannot tell you whether your tyre pressures are correct, whether the engine timing is right, whether the carburettor is adjusted properly, and so on. And, need it be said, racing-type move offs from traffic lights, and screeching to a halt at the next set do not improve your consumption figures. You will soon get used to driving with an eye on your economy indicator and discover that you normally travel just as quickly economically as with those fast get·aways. The often heard remark that economy drivers are traffic obstacles is, you will find, totally unfounded.
lf your car has no space where you can mount the indicator in good view, get a small plastic case and just mount the LEDs in this. This little unit can then be mounted in the instrument panel and connected to the main unit (which is mounted anywhere there is space) by a suitable multi core cable. A tip. It is possible to fit two units (for instance, the economy indicator and the choke alarm) into one case for a very economical package. The two boards are kept separate by suitable spacers.
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