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Патент USA US3083704

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April 2, 1963
A. G. WALFORD
3,083,697
ENGINE GOVERNORS
Filed Nov. 7, 1958
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Patented Apr. 2, 1963
2
1
3383,59’?
ENGINE GQVEEPQ @123
Alexander G. Walford, Colchester, England, assignor to
Darcy, l>arman Sr flompzmy Limited, €olchesten Eng
land
Nov. 7, -953, Ser. No. 772,571
from a lever 44- connected to the piston rod passing
through a bushing 38.
The fulcrum 4-1 of the lever 25 connected to the per
manent droop control valve can be moved bodily to vary
the amount of movement given to the control valve by a
given movement of the power piston. In one position
of the fulcrum—in line with the central axis of the valve
:29 and its spring 27——this movement is reduced to zero.
This is for isochronous operation as will appear later.
The means for moving the fulcrum 41 include an
This invention relates to engine governors designed
adjusting screw 31 rotatable by a knob 36. Similar
to control the speed of an engine under varying condi
means is provided for adjusting the fulcrum 3d of lever
tions of load and in particular to a centrifugal ?yweight
44. This means comprises a fulcrum bracket 33 which
governor of the servo-operated type utilizing ?uid-pres
can be moved relative to a slide 32 by rotating an adjust
sure feedback on to the main pilot valve sleeve or, pref
15 ing screw 47 by means of a knob 37. A friction adjust
erably, on to the main pilot valve itself.
ment is provided in the form of a nut 35.
According to the invention, means is provided for
A load sensing unit (not shown) may be added to the
varying the steady state feedback pressure to vary the
governor at 42 to decrease the frequency variations on
equilibrium speed of the governor so as to obtain any
an alternator set. A solenoid, energized from a watt
desired value of permanent speed droop (i.e. a predeter
meter circuit in the alternator output, controls the move
mined speed variation in proportion to applied load).
ment of a pilot valve which in turn controls a piston in
Means is also provided for adjusting the governor to give
Qlaims priority, application Great Britain Nov. 12, 1957
4
(=Cl. 121-»42)
the feedback circuit. Displacement of this piston created
isochronous running when desired.
An embodiment of the invention will now be described
by a change in alternator load in turn causes a movement
with reference to the accompanying drawing. In this
embodiment, the feedback is on to the main pilot valve.
of the power piston, varying the engine power output to
suit the power required. This action will precede a
speed variation and will greatly reduce temporary vari
The basic governor comprises two units.
These may
ations of frequency during load changes.
be mounted together or separately with pipe connections
As applied to this embodiment the operation of the
(shown dotted). The two units are (a) the speed sens
load sensing unit is as follows.
ing and oil supply unit on the left, and (b) the power
30
The input to the solenoid corresponds to the load on
unit on the right.
the prime-mover, thus deflecting the solenoid core and
Unit (a) is the larger of the two units and is mounted
pilot valve controlled thereby against a spring. This ad
vertically. It contains the ?yweights 4, spring drive as—
mits oil to the space above the piston of the load sensing
sembly 3, pilot valve 9, oil pump 11, hydraulic accumu
lator 16 loaded by springs 17, speed setting mechanism 1
and 2 and the oil storage reservoir.
The fulcrum bearings 7 of the conventional ?yweights
4- are of the needle roller type to minimize friction. The
unit (or drains it) depending upon the variation of load.
35 The displacement of this piston causes a corresponding
movement of the sleeve of the speed sensing unit and
movement of the power piston. The movement of the
power piston causes a corresponding movement of the
basic droop piston, until the displacement of this piston
an angular contact ball race and spring carrier 5. The
pilot valve 9 moves inside a sleeve 1% which rotates with 40 cancels out the movement of the load sensing unit piston,
restoring the sleeve to its original position and causing
respect to it to minimize friction. The oil pump 11 is
movement to cease. In practice, due to the time delays
of the gear type and is driven together with the governor
in the system, exact follow up of the power piston to
from a drive shaft 13 by a set of change-speed gears 12
load change does not occur and a small variation of
for speed adjustment. The drive shaft 13 runs in bear
speed takes place. The speed sensing system corrects this
ings 14 and is provided with an oil seal 15. All the
in the normal way.
Working parts are immersed in oil except the ?yweight
?yweight force is transmitted to the speeder spring 3 by
system and spring drive.
The speed sensing and oil supply unit also comprises
a feedback receiver having a ?oating spring-loaded pis
to 18 in a cylinder, the force from spring 2% being trans
mitted through a point contact strut 19 so that lateral
forces are minimized.
Unit (1)) comprises the power piston 22, feedback
It is to be understood that the load sensing unit need
not be electrically operated nor indeed is its presence in
any way essential to the working of the invention.
The operation of this embodiment will now be de—
scribed under various working conditions.
Increase of Load (lsochronous Setting)
An increase in load causes the speed of the prime
transmitter elements and integral action control valve 40.
The power piston 22 which operates the mechanism 55 mover to drop. The ?ywe-ights 4 move inwards because
the force exerted by the speeder spring 3 overcomes the
for taking the necessary corrective action is of the dif
force exerted by the flyweights. This causes the pilot
ferential area type, thus eliminating a return spring with
valve 9 to move downwards resulting in a flow of high
in the governor. (A return spring to perform the re
pressure oil past the control land of the pilot valve and
quired duty at the pressures involved would be of ex
cessively large proportions.) The di?erential areas of 60 through connection 43 to the underside of the power
piston 22 causing it to move upwards and increase the
the piston are so arranged that the return force is 75%
fuel supply to the prime mover by rotating the control
of the force to increase fuel. This allows a return spring
shaft 21. Cont-r01 shaft 21 which rotates with lever 23
giving a force equivalent to 25 % of the governor force
connected to piston 22 may be operatively connected for
to be ?tted on the external linkage acting in the direc 65 example by linkage 51 to a ‘suitable throttle valve assem
tion to reduce fuel in order to eliminate backlash.
bly 52 disposed in a fuel conduit 53 for supplying more
The basic droop piston 39 and the spring guide 26 of
fuel to the prime mover. This upward movement of the
the permanent droop control valve 29, which is of the
power piston causes a downward movement of the basic
spring-loaded ball-type, are mechanically connected to
droop piston 39 via the links 24-, the control lever 23,
the power piston 22. by an adjustable linkage 59, allow 70 and the adjustable feed back lever 44. The levers 25 and
ing the amounts of basic and permanent droop to be
44 although shown separately have their left hand ends on
varied to suit requirements. The piston 39 is operated
the same axis so that they move in synchronism. The
3,083,697
3
4
downward movement of the basic droop piston 39 causes
a ?ow of oil from the space below the piston to the feed
back circuit. This oil is .forced into the feedback re
ceiver via connetion .45 and causes the piston 18‘ therein
to rise, compressing its spring 20. The increase of force
exerted by this spring causes the pressure under the feed
back piston and in the- feedback circuit to rise. Asa
connection 48) pushes it downwards to decrease the fuel
input to the prime mover; the downward movement is
transmitted to the basic droop piston 39 causing the feed
back pressure to drop, which in turn tends to cause the
pilot valve to close the oil port.
If operating with a
permanent droop the pressure setting of the permanent
result, the pressureentering through conduit 54 into the
space under the main pilot valve 9 rise-s causing an up
ward force on-thepilot valve, acting in the same direction 10
as the ?ywheel force. 'This increase in force tends to
cause the pilot valve to rise and shut off the ?ow of the
control oil to the power piston 22. The rise in pressure
droop valve will decrease, resulting in a drop in feedback '
system pressure and an increase in the equilibrium speed
of the governor.
Shut Down
This is effected by draining the control oil by means
of a solenoid-controlled valve (not shown). The valve
. movement exerts a force on the pilotvalve equivalent to a 15 used is of the pilot-operated type eliminating the need for
a large solenoid.
certain increase in speed, hence, before further power pis
When the solenoid is de-energized to shut down the
ton movement takes place, the speed must drop until
engine the oil in the space above this valve is allowed to
equilibrium exists between the force exerted by thechange
escape. The spring force under the valve pushes the
in feedback pressure and the force reduction caused by the
created in the feedback circuit'by upward power piston
Thus, if 20 valve upwards, cutting off the oil supply from the main
control ports to the underside of the power piston and
draining the oil under the power piston. ' The high pres
the pilot valve ‘system dependent upon the power piston
sure oil on the upper surface of the power piston pushes
position and the ratio of the adjustable feedback lever
it downwards, cutting the energy supply to the prime
44. Inpractice, leakage does exist, and in time, the feed—
reduced rotational speed of the ?yweights.
the feedback did not leak, a force would be exerted on
back pressure would vfall to atmospheric unless oil were 25 mover.
'. When the solenoid is energized the oil in the space vabove
supplied to the system to make up leakage. In this system,
the valve is trapped and oil coming through the restriction
the leakage is made up through the permanent droop
will push the valve downward, opening the passage be
control valve restriction 28 which is in the axial passage
tween the control port and the power piston and so allow
through the valve sleeve .30. When the governor is set
isochronously the pressure setting of this valve 29 re 30 ing the governor to operate in the normal manner.
It is to be noted that in addition to operating isochro
mains'constant irrespective of power piston position. This
riously and with a “positive” droop, i.e. speed falling as
valve is connected .to the feedback system via the integral
load increases, the power unit can ‘be adjusted to give
adjust-ment‘restriction 40 which allows oil to ?ow from
or to the feedback system at a predetermined rate, depend- '
operation with a negative droop, i.e. speed rising as load
ing upon the pressure variation across this restriction.
increases. The term droop should therefore be taken in
When an increase of’ load occurs-the pressure in the feed
back system will rise due to the displacement of the feed
back system oil by the basic droop piston into the feed
back receiver. A pressure diiference, will then exist
its broadest sense to cover both modes of operation. . '
ing principal advantages.
feedback system, through the pressure control valve 29 to
the need for linkage between the power piston and the
main pilot valve, simplfying the construction of I the
The governor according to the invention has the follow
(1) The permanent droop control obtained by varying
across the restriction ‘and ?ow will take place from the 40 the steady state pressure in the feedback system eliminates
drain via connection 46. As this flow occurs, the feed
governor.
'
back receiver piston 18 will drop, the pressure decreasing
(2) The use of the system allows,the power piston to .
proportionately until the pressure in the feedback system
is equal to the set pressure of the pressure control valve, 45 be remote from the ?yweight speed sensing mechanism
and pilot valve.
and ?ow across the integral restrictor 40 ceases. In prac
(3) The use of the feedback system operating at above
tice, the setting of the restrictor is adjusted to give opti
atmospheric pressure allows large transient feedback pres
mum rate of return to a steady state, dependent upon the
sures to be used, so that large forces are, exerted on the
characteristics of the prime mover. When the pressures
have equalised, the forces acting on the pilot valve 9 will 50 pilot valve. This in turn allows large ?yweight forces to
be used (obtained by running the ?yweights at high speed)
return to their original values and the equilibrium speed
and requires sti? speeder springs giving the ?yweights a
high natural frequency and good response characteristics.
of the governor will return to its original value. 7
"Increase of Load (With Permanent Droop)
(4) The use of a feedback system operating at above
When the ‘governor is :set to give permanent droop, 55 atmospheric pressure eliminates troubles caused by aera
tion of the fluid in the feedback circuit (as would occur
power piston movement causes a proportional movement
in systems where the feedback pressure became sub
of the permanent droop valve spring 27 altering the pres
atmospheric).
sure setting of the permanent droop valve 29. ‘ When an
I claim:
increase of load occurs, the power piston 22 moves up
,
1. Apparatus for controlling the speed of an engine
wards, the compression of spring 27 is increased and the
pressure output of the valve 29 increases; thus the pressure
in response to changes in load on the engine comprising a
in the-feedback circuit-will attain an increased steady'state
value. This increases the force acting on the pilot valve
governor responsive to engine speed, means for varying
trol lever'25, which, in turn, varies the relationship be
tween power piston movement and the pres'sur'echange of
direction for actuating said engine speed varying means
to change the engine speed in the other direction, feed
the engine speed, means including a ?uid pressure motor
operably connected to said engine speed varying means ~
9 causing the equilibrium speed to decrease. The amount
of spaced variation with change inload is varied by ad 65 and a source of control ?uid pressure operated by the
governor in response to a change in engine speed in one
justment of the ‘fulcrum 41 of the permanent droop con
the permanent droop control valve 29.
Decrease of Load
back means actuated by said governor operated means
'
70 for opposing action of said governor operated means for
Decrease of load causes the prime mover speed to
rise. The ?yweights 4 then move outwards releasing the
control oil under the power piston. The high pressure
oil on the upper surface of the piston (supplied through 75
attaining a desired variable engine speed condition, .and
time delay means operable after actuation of said feed
back means for varying the action of said feedback
means, said feedback means comprising a conduit system
containing ?uid pressure at least above atmospheric pres
3,083,697
5
6
sure and having a pressure equalizing restricted connec
tion to said control ?uid pressure means.
is operably connected to said linkage and, opening in
2. Apparatus for controlling the speed of an engine in
response to a transient pressure rise in said system, con
trols the pressure in said system.
response to changes in load on the engine comprising a
4. Apparatus for controlling the speed of an engine in
governor responsive to engine speed, means for varying
the engine speed comprising a ?uid pressure responsive
response to load changes on the engine comprising a
motor, means operated by the governor in response to a
governor responsive to engine speed changes, means for
controlling the engine fuel supply, a power piston operably
change in engine speed in one direction for applying a
control ?uid pressure to said motor for actuating said
connected to said fuel control means, a source of control
?uid pressure connected by conduit means to said power
engine speed varying means to change the engine speed 10 piston, a movable pilot valve in said conduit means op
erably connected to said governor so that a change in
in the other direction, feedback means actuated by said
governor operated means for opposing action of said
engine speed acts through the governor to apply said
governor operated means for attaining a desired variable
control ?uid pressure to the power piston to cause actua—
tion of said fuel control means to effect a change in engine
engine speed condition, said feedback means comprising a
system wherein said control ?uid pressure is varied by 15 speed opposing that which acted through the governor,
feedback means between the power piston and pilot valve
action of said governor operated means, and means for
comprising a ?uid pressure transmitting system contain
varying the action of said feedback means comprising a
ing a droop piston, means providing a pressure equalizing
restricted pressure equalizing connection for gradually
connection between said conduit means and said system
restoring the ?uid pressure in said feedback means to
equalization with said control ?uid pressure.
p
20 for restoring the ?uid pressure in said system to equal said
3. Apparatus ‘for controlling the speed of an engine
in response to load changes on the engine comprising a
governor responsive to engine speed changes, means for
controlling the engine fuel supply, a power piston operably
connected to said fuel control means, a source of control
?uid pressure connected by conduit means to said power
piston, a movable pilot valve in said conduit means
operably connected to said governor so that a change in
engine speed acts through the governor to apply said con
trol ?uid pressure to the power piston to cause actuation
of said fuel control means to effect a change in engine
speed opposing that which acted through the governor,
feedback means between the power piston and pilot valve
comprising a ?uid pressure transmitting system containing
a droop piston, means providing a pressure equalizing 35
connection between said conduit means and said'system
for restoring the ?uid pressure in said system to equal
said control ?uid pressure; and linkage interconnecting the
power and droop pistons so that actuation of said droop
control ?uid pressure; and linkage interconnecting the
power and droop pistons so that actuation of said droop
piston by the power piston changes the ?uid pressure in
said system applied to move said pilot valve, and means
for adjusting the connection between said linkage and said
permanent droop valve, said means providing the pressure
equalizing connection and comprising a passage having a
restriction to control the pressure equalization and a per
manent droop valve which is operably connected to said
linkage and, opening in response to a transient pressure
rise in said system, controls the pressure in the said
system.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,364,115
2,623,504
Whitehead ____________ __ Dec. 5, 1944
Rodeck et al __________ __ Dec. 30, 1952
piston by the power piston changes the ?uid pressure in 40
2,734,490
Moulton ____ --~ ______ __ Feb. 14, 1956
said system applied to move said pilot valve, said means
providing the pressure equalizing connection and com
prising a passage having a restriction to control the pres
sure equalization time and a permanent droop valve which
2,756,725
2,762,384
2,769,431
2,769,432
Parker _______________ __ July 31,
Rosenberger _________ __ Sept. 11,
Massey ________________ __ Nov. 6,
Massey _______________ __ NOV. 6,
1956
1956
1956
1956
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