Speed governor working principle- dynamics Of Machine I diesel engine speed control

The various types of governors:-

The classification of governor can be made depending on their operation.
(a) Centrifugal governors
(b) Inertia and flywheel governors
(c) Pickering governors.
Centrifugal Governors
In these governors, the change in centrifugal forces of the rotating masses due to
a change in the speed of the engine is utilized for the movement of the governor sleeve.
One of these types of governors is commonly used because of its simplicity in operation.
Inertia and Flywheel Governors
In these governors, the inertia forces caused by the angular acceleration of the
engine shaft or flywheel by the change in speed are utilized for the movement of the
balls. The movement of the balls is due to the rate of change of speed instead of
the change in speed itself as in the case of centrifugal governors. Thus, these governors
are more sensitive than centrifugal governors.
Pickering Governors
This type of governor is used for driving a gramophone. As compared to the
centrifugal governors, the sleeve movement is very small. It controls the speed by
dissipating the excess kinetic energy. It is very simple in construction and can be
used for a small machine.

Types of Centrifugal Governors
Depending on the construction these governors are of two types :
(a) Gravity controlled centrifugal governors, and
(b) Spring-controlled centrifugal governors.
Gravity Controlled Centrifugal Governors
In this type of governors, there is gravity force due to weight on the sleeve or
weight of sleeve itself which controls the movement of the sleeve. These governors
are comparatively larger in size.
Spring Controlled Centrifugal Governors
In these governors, a helical spring or several springs are utilized to control the
movement of the sleeve or balls. These governors are comparatively smaller in size.

There are three commonly used gravity controlled centrifugal governors :
(a) Watt governor
(b) Porter governor
(c) Proell governor

1. Watt Governor:- It is the simplest type of centrifugal governor. If N is the speed of the arm and ball about the spindle axis, then the height of the governor (h) is given by…

 h = 895 / N2 metres.

From this expression, we see that the height of a governor is inversely proportional to N2. This governor may only work satisfactorily at low speeds i.e. from 60 to 80 r.p.m.

2. Porter governor:- It is a modification of a watt governor, with a central load attached to the sleeve. When the sleeve moves upward, the governor speed increases, and when the sleeve moves downwards the governor speed decrease.

The ratio of the height of a porter governor (when the length of arms and links are equal) to the height of watt’s governor is…,                                                                             m + M / m,

when m and M are the masses of the ball and sleeve respectively.

In these governors, springs are used to counteract the centrifugal force. They can be
designed to operate at high speeds. They are comparatively smaller in size. Their speed
range can be changed by changing the initial setting of the spring. They can work with
an inclined axis of rotation also. These governors may be very suitable for IC engines, etc.
The most commonly used spring controlled centrifugal governors are :
(a) Hartnell governor
(b) Wilson-Hartnell governor
(c) Hartung governor

3Hartnell governor:- It is a spring-controlled governor. In a Hartnell governor, the compression of the spring or lift of the sleeve (h) is given by…

  h = (r2 – r1) y/x

and stiffness of the spring,                s = S2 – S1 / h                         Where,

r1 = minimum radius of rotations.

r2 = Maximum radius of rotation.

S1 = spring force exerted at the min rad. of rotation.

S2 = spring force exerted at the max rad. of rotation.

x = length of the vertical or ball arm of the lever.

y = length of the horizontal or sleeve arm of the lever.

 

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