The document describes an electromechanical system for governing the speed of a diesel engine powering a generator through torque sensing rather than speed sensing. A load cell is mounted on the generator to sense changes in torque demand. When load increases, the load cell detects additional thrust and sends a signal to adjust the fuel supply via a stepper motor before engine speed decreases. This aims to minimize speed fluctuations when load changes compared to conventional speed-sensing governors. The system converts load cell output to control a stepper motor that moves the fuel rack to regulate fuel supply and maintain constant engine speed.

1. INTERNATIONAL JOURNALEngineering and TechnologyRESEARCH IN
International Journal of Advanced Research in OF ADVANCED (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME
ENGINEERING AND TECHNOLOGY (IJARET)
ISSN 0976 - 6480 (Print)
ISSN 0976 - 6499 (Online) IJARET
Volume 4, Issue 2 March – April 2013, pp. 27-32
© IAEME: www.iaeme.com/ijaret.asp ©IAEME
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ELECTROMECHANICAL GOVERNING OF DIESEL ENGINE OF A
GENERATOR SET THROUGH TORQUE SENSING
1 2
Mohd Muqeem , Navneet Saini
1
Lecturer, Mechanical Engineering Department, Teerthanker Mahaveer University,
Uttar Pradesh, India – 244001
2
Lecturer, Mechanical Engineering Department, Teerthanker Mahaveer University,
Uttar Pradesh, India – 244001
ABSTRACT
Governing is the action of varying the fuel supply in accordance with the load demand
so that the engine runs at practically constant speed. In this article an attempt is made to
control the speed of the engine just before it goes down or high by torque sensing rather than
speed sensing. In actual practice, governor senses the change in the speed because of applied
load then it regulates the fuel supply to again maintain this speed. Here, we have made an
arrangement to generate a signal which will show that there is a change in the load and the
speed of the engine is also going to get changed. Before the speed of the engine gets changed,
this signal will stipulate the fuel regulating system to increase or decrease the fuel supply so
that the speed may not be fluctuated.
KEY WORDS: Alternator, Armature, Fuel Rack, Governor, Load Cell, Stepper Motor.
1. INTRODUCTION
Diesel engine speed is controlled solely by the amount of fuel injected into the engine
by the injectors. The governor provides the engine with the feedback mechanism to change
speed as needed and to maintain speed once reached. A governor is a speed-sensitive device,
designed to maintain a constant engine speed regardless of load variation. Since all governors
used on diesel engines control engine speed through the regulation of the quantity of fuel
delivered to the cylinders, these governors may be classified as speed-regulating governors.
The major function of the governor is determined by the application of the engine [1] [2].
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2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME
1.1 Operation of a Governor
The principles involved are common in any mechanical and hydraulic governor. The
governor controls the fuel rack position through a combined action of the hydraulic piston
and a set of mechanical flyweights, which are driven by the engine blower shaft. Figure 1
provides an illustration of a functional diagram of a mechanical governor. The position of the
flyweights is determined by the speed of the engine. As the engine speeds up or down, the
weights move in or out. The movement of the flyweights, due to a change in engine speed,
moves a small piston in the governor's mechanical system. This motion adjusts the fuel rack
for increased/decreased fuel supply to the engine which in turn regulates the engine speed [3].
Figure 1: Governing of diesel engine
1.2 Problem associated with the Governors
The general problem associated with the governors is that they regulate the fuel
supply of the engine by sensing the change in the RPMs. Once the engine speed gets changed
then these governors take some action to slide the fuel rack to compensate the RPM changes
[4] [5]. Here, it is observed that speed is governed once it has been changed, which is a
drawback because it should be controlled not to get changed by doing some prior
arrangements. In this article an attempt is made to control the fluctuations in the RPMs by
sensing the changes in torque requirement rather than speed so that some arrangements can
be made in advance to control the speed which is going to get changed due to changed torque
requirement.
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3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME
2. GOVERNING OF DIESEL ENGINE THROUGH TORQUE SENSING
The following Figure 2 shows block diagram of working of electromechanical speed
governor system through torque sensing. A 12 Horse Power Kirloskar diesel engine and a 7.5
KVA alternator are mounted on two separate foundations so that the vibrations of the engine
may not be transferred to the alternator. The engine and the alternator are connected by belt
and pulley arrangement. When viewed from the front, the engine and alternator rotates in the
clockwise direction and the alternator is located in the left and the engine in the right. To
achieve the desired purpose, a load cell is mounted below the two side legs of the alternator
to measure the thrust applied by it on the base. When the generator is running at no load, the
alternator will exert a small thrust on the load cell through right leg. The load cell will send
the signal to the control unit accordingly to convert it into pulses for stepper motor which in
turn will control the fuel rack to supply fuel to the engine to run at 1500 RPM (required
speed). Now, when some load is applied on the alternator suddenly, the armature of the
alternator will try to rotate the whole alternator unit and the torque requirement for the
alternator will increase. Due to this increase in torque requirement, it will try to lower the
speed of the engine but it will be controlled instantaneously by the load cell output signal to
the fuel rack regulating system. When the alternator torque requirement will increase, it will
exert more thrust on the load cell and left leg will tend to lift up. Due to this increase in the
thrust on load cell, a signal will be transmitted to the unit converting it into pulses for stepper
motor which in turn will regulate the fuel supply through fuel rack adjustment before the
engine speed get lowered. This shows that an attempt is already made to maintain the speed
just before it was going to get lowered due to increased torque requirement and speed will not
fluctuate.
Engine (Prime Mover)
Stepper
Alternator
Motor
Regulating
Fuel Rack
Belt and Pulley
arrangement
Load Cell
A Unit
Converting Load Cell Output Signal into
Useful Pulses for stepper Motor to move
fuel rack to and fro accordingly
Figure 2: Governing of diesel engine through torque sensing
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4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME
2.1 Conversion of Load Cell Output Voltage into Pulsating Voltage for Stepper Motor
The circuit diagram in figure 3 shows the amplification and conversion of load cell
output voltage into pulsating voltage required to drive the stepper motor. Here, the
microcontroller is controlling the motor according to the variation in the thrust applied by the
alternator right leg on load cell. When the thrust on the load cell increases, the
microcontroller sends the signal to the stepper motor to rotate in the clockwise direction
which in turn will move the fuel rack in the forward direction. Similarly, when the thrust on
the load cell decreases, the microcontroller sends the signal to the stepper motor to rotate in
the anti-clockwise direction which in turn will move the fuel rack in the backward direction.
Figure 3: controller circuit
2.2 Stepper motor pinion and fuel rack mechanism
The rack and pinion arrangement is used to convert rotary motion of the motor into
linear motion of fuel rack. Here, pinion is mounted on the motor shaft to move the fuel rack
to and fro according to the direction of motion of the motor. The figure 4 shows how rack and
pinion works.
Pinion mounted
on motor shaft
Rack of Fuel Injector
.
Figure 4: Rack and pinion mechanism
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5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME
2.3 Cutaway view of fuel Injector
The cutaway view of fuel injector shown in figure 5 shows that when the fuel rack is
moved to and fro by the stepper motor, it rotates the gear fitted inside the injector. Due to the
rotation of the gear fitted on the plunger, the fuel supply to the engine is regulated [3].
Figure 5: cutaway view of fuel injector
5
2.4 Adjustment of setup for first use
For the smooth running of the generator set, an efficient adjustment is needed before
the first use. Once the engine is started, it needs fuel regulation to run at required 1500 rpm.
On other hand, the alternator is at no load, so it will send the signal to the stepper motor
according to its exerted thrust on load cell. At this moment, the setup is required to send the
signal to the stepper motor to supply minimum required quantity of fuel to the e
tepper engine so the
setup is adjusted accordingly. The setup will not lower the fuel supply below this quantity
.
because at this moment the generator is at no load and it requires minimum quantity of fuel.
Now, as the load increases on the alternator, the thrust on the load cell also increases which in
turn will send the signal to the stepper motor to increase the fuel supply and when the thrust
decreases, to decrease the fuel supply
supply.
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6. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 2, March – April (2013), © IAEME
3. CONCLUSION
From this article we have concluded that on using this setup we can acquire minimum
fluctuation in rpm of engine from no load to full load condition. In an alternator, when the
rpm fluctuates, the output voltage from the alternator can be regulated by some electrical
engineering techniques but the frequency of the output cannot be regulated because it
depends on rpm. So, to get minimum fluctuation in frequency of alternator output it is
necessary to reduce the fluctuation in speed of the engine from no load to full load which can
be achieved by using the above technique.
4. ACKNOWLEDGEMENT
The experimental setup was carried out in a private generator repairing workshop with
the co-operation of senior technician and owner Mohd Yunus at NH-24, Pakbara, Moradabad
and Mr. Farjand Ali from Akanksha Automobiles Pvt. Ltd. Moradabad, Uttar Pradesh, India -
244102
REFERENCES
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10980
[2] John B. Heywood, “Internal Combustion Engine Fundamentals”, McGraw-Hill series in
mechanical engineering.
[3] DOE Fundamentals Handbook, Mechanical Science, Volume 1 of 2, U.S. Department of
Energy , Washington, D.C. 20585, DOE-HDBK-1018/1-93, January 1993
[4] APECS® 500 Electronic Engine Speed Governing System, Manual SE-4107,
WOODWARD 2004.
[5] “Design and Development of Microcontroller Based Electronic Speed Governor for
Genset/Automotive Engine” Sushant R. Burje, Prof.S.A.Kulkarni and N.B.Dhande,
International Journal of Engineering and Science, ISSN: 2278-4721, Vol. 1, Issue 5
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