Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
--1--
Description
~ `
Rotation Sensitive Pressure Regulator
. .
Technical Field
This invention relates generally to fuel
delivery systems for combustion ignition engines and
more particularly to apparatus for limiting exhaust
smoke and/or the rise in engine torque.
10
- Background Art
When a compression ignition engine is
operating at full speed and a load is applied to the
engine, the engine speed decreases until a lug
condition results. As the engine speed decreases, the
delivery of the fuel pump increases and a greater
volume of fuel is delivered to the combustion
chambers. The increased fuel delivery results in an
inherent increase in the output torque of the engine.
In some engines, particularly turbocharged engines, the
natural torque rise under such conditions is also
detrimental to effective control of exhaust emissions
in as much as smoke is produced from the engine.
It has been found that excessive smoke
production and damaging increases in torque can be
prevented by decreasing the amount of fuel delivered to
the combustion chambers as the engine speed decreases
from its rated to its peak torque speed.
The task of decreasing the amount of fuel
delivered as engine speed decreases typically cannot be
performed by a conventional governor alone. A governor
increases the delivery of fuel as engine speed
decreases in order to maintain engine speed constantO
This is the primary function of a governor. On some
engines a fuel air ratio controller and a speed
~.
;' , , ;'
.
.
~5,t3~4~
--2--
sensitive regulator are used in combination with a
governor to override the governor. Such fuel air ratio
controllers are disclosed in U.S. Patent 3,313,283
entitled "Fuel Ratio Control Override" issued on April
11, 1967 to R. H. Miller; U.S. Patent 4,068,642
entitled "Fuel Ratio Control with ~lanually Operated Air
Override" issued on January 17, 1978 to J. P. Little,
Jr.; and U.S. Patent 4,149,507 entitled "Fuel~Air Ratio
Control with Torque-Limiting Spring for Supercharged
Engines" issued on April 17, 1979 to J. P. Little, Jr.
et al. One device for regulating a fuel air ratio
controller is disclosed in U.S. Patent 4,136,658,
entitled "Speed Sensitive Pressure Regulator System"
issued on January 30, 1979 to Gates and assigned to the
assignee of the present application. Other work in
this field of technology includes U.S. Patent 3,~95,245
entitled "Fuel Supply System for Internal Combustion
Engines" by Ishida issued on October 3, 1972; U.S.
Patent 3,916,~62 entitled "Torque Rise Limiting Device1'
by Clouse et al issued on November 4, 1975; U.S. Patent
3,532,082 entitled "Minimum-Maximum Governor With
Midrange Regulation" by Clouse et al issued on October
6, 1970; and U.S. Patent 3,911,855 entitled "Torque
Rise Limiting Governor" by Hammond issued on October
14, 1975.
Previous devices for controlling torque rise
have not always provided the desired service life.
These prior controllers, for example, employ springs
that can change in elasticity and/or diaphragms that
can rupture due to wear.
Further, there are only a limited number of
engines that actually require such a controller. Thus,
there is a continuing search for a device which will
satisfy these tasks and can be easily installed as an
accessory to a conventional governor.
: - .
--3--
The present invention is directed to over-
coming one or more of the problems as set forth above.
Disclosure of the Invention
In one aspect of the present invention, a
rotation sensitive pressure regulator is provided
having an inlet, an outlet, a vent conduit, and valve
means for regulating fluid pressure from the inlet to
the outlet wherein the valve means includes a
reciprocable spool valve sequentially movable between a
first position communicating fluid pressure from the
inlet to the outlet, a second position blocking the
outlet from the inlet, and a third position
communicating the outlet with the vent conduit. The
rotation sensitive pressure regulator further includes
fly~weight means for moving the spool valve in a first
direction and towards its first position in response to
increased rotation of the fly-weight means and means
for urging the spool valve in a second direction
opposite to the first direction and towards its third
position in response to fluid pressure in the outlet
and decreased rotation of the fly-weight means.
- The problem of providing an apparatus that
will utilize existing equipment is met by providing a
regulator that requires just an engine speed input
shaft and a source of fluid pressure and can be
conveniently attached at many locations on the engine.
The foregoing and other aspects will become
apparent from the following detailed description of the
invention when considered in conjuncution with the
accompanying drawings. It is to be expressly
understood, however, that the drawings are not intended
as a definition of the invention but are for the
purpose of illustration only.
.
,~
5 ~,. ~,
.
'
, ' ~
i4~
Brief ~escription of the Drawings
Fig. 1 is a diagrammatic side elevational view
- in cross section of one embodiment of the present
invention, and
Fig. 2 is a graphic illustration of the torque
curves, the generation of smoke and the fuel rack
position of an engine that is operated both with and
without the embodiment of Fig. 1.
Best Mode for Carrying Out the Invention
Fig. 1 illustrates a rotation sensitive
pressure regulator 7 that is used on a compression
ignition engine (not shown). The regulator includes a
speed input shaft 8 that is driven by the engine at a
speed proportional to the crankshaft speed. The input
shaft is mounted for rotation within two duplex
bearings 9 that are rigidly mounted in a base 10. The
base attaches the regulator 7 to the engine (not shown)
and seals the bottom of the regulator 7 from
contamination by dirt and oil. The regulator 7 further
includes a body or housing 11 which houses the
apparatus. The base 10 and the body 11 are sealed by
an O-ring 12.
The speed input shaft 8 rotates a fly-weight
assembly 13 that includes a disc shaped carrier 14 on
which is mounted a plurality of clevices 15. On each
clevice is a pin 16 that acts as a pivot for a
fly-weight 17. The fly-weights are located between the
clevices and pivot about the pins 16. When the sha~t 8
rotates, the carrier 14 rotates at the same speed and
the fly-weights pivot outwardly away from the axis of
rotation due to centrifugal force.
Each fly-weight 17 has a toe 18 that engages
the outer race or ring of a bearing 20. The inner race
:
,. ~
--5--
!
of the bearing is rigidly attached to a nondeformable
actuator member 19 that is an integral part of a valve
means 21 Eor regulating the outlet fluid pressure of
the regulator 7. More precisely, the member 19 is a
stem located on the lower end of a spool valve 21a and
serves as a rigid coupling directly engaged by both the
fly-weight assembly 13 and the spool valve for moving
the spool valve in an upward direction in response to
rotation of the fly-weight assembly. The bearing 20
10 permits the fly-weights to rotate relative to the spool
valve during operation. The spool valve has upper and
lower relieved portions 22, 23, respectively, that form
a control land 24. Throughout the range of motion of
the spool valve 21a, the upper relieved portion 22
15 communicates with a vent conduit 28 in the body 11 and
the lower relieved portion 23 communicates with a
supply conduit or inlet 26. The supply conduit is
connected to a source o~ fluid pressure (not shown).
When used on a supercharged or turbocharged engine, the
20 supply conduit 26 is connected to the intake manifold
so that the regulator is supplied with pressurized air
corresponding to the manifold pressure.
As illustrated in Fig. 1, the control land 24
covers a controlled air conduit or outlet 29. During
25 operation, regulated air at a predetermined pressure is
provided through this conduit 29 to a fuel air ratio
controller 31 as described below. ~he spool valve 21a
slides up and down within a bushing 33 that is rigidly
mounted within the body 11 of the regulator 7. The
30 conduits 26, 28 and 29 communicate with the spool valve
through the bushing. The clearance between the spool
valve and the bushing is approximately 3.30X10 6m
(130 millionths of an inch) so that air may be
controlled by this spool valve. The spool valve 21a
, ,,~
.-- .
5~6~
-6-
and the bushing 33 can be fabricated from either
stainless steel or porcelain. Porcelain is preferred
if high temperature moisture laden air is to be
encountered from the intake manifold.
Referring now to the upper portion of Fig. 1,
the regulator 7 is provided with means 32 for urging
the spool valve 21a in a downward direction in
opposition to the fly-weight assembly 13 in response to
fluid pressure in the outlet 29.
The urging means includes a cavity or chamber
34 formed around the top of the bushing 33 by a cover
35 and a gasket 36 secured to the regulator housing 11
by a plurality of bolts 37 and which seal the fluid
pressure within the regulator. The cavity is connected
to the controlled air conduit 29 by a passage 38.
The urging means 32 further includes a
compression spring 40 which urges the spool valve 21a
in a downward direction and places a static force on
the spool valve 21a that opposes the upward force
generated by the rotation of the fly-weights 17. The
spring provides a way to vary the effect of the
fly-weights and to move the operating curve of the
regulator as described below in connection with Fig.
2. When the adjustment screw 39 is properly
positioned, the screw is locked in place with a jam nut
42 that engages the adjustment screw 39 and the cover
35~ A rubber seal washer 43 is used to prevent the
escape of fluid pressure from around the screw.
The regulator 7 controls the pressure in the
controlled air conduit 29 by moving ~he control land 2
on the spool valve 21a with respect to the conduit 29.
The position of the control land is controlled by a
plurality of forces. The downward force on the spool
valve includes a force due to the fluid pressure in the
,
' , . ' ~
'I ''
, - ' ~
. .
--7--
cavity 34 under the cover 35. The pressure in this
cavity 34 is equal to the pressure in the controlled
air conduit 29 and is communicated to the cavity via
the passage 38. In addition, there is a downward force
acting on the spool valve due to the static force of
the spring 40. The upward force on the spool valve 21a
includes the force due to the rotation of the
fly-weights 17. This force is equal to a constant K
times the square of the speed of the shaft 8 so that
the upward force is proportional to the square of the
engine speed. The constant K includes the number and
mass of the fly-weights, the distance between the
center of mass of the fly-weights and the pin 16 and
the distance between the toe 18 and the pin 16. The
cavity around the fly-weights is vented to the
atmosphere so that no fluid pressure acts on the bottom
of the spool valve 21a.
The pressure in the controlled air conduit 29
is directed to the fuel air ratio controller 31. The
controller includes an upper chamber 45 and a lower
chamber 46 separated by a diaphragm 47. The diaphragm
is spring loaded with a spring 48 that eliminates
preloading the diaphragm. The pressure from the
regulator 7 is directed into the upper chamber 45 and
~5 the lower chamber 46 is constantly at atmospheric
pressure. The bottom of the diaphragm 47 is connected
to a bolt 49 that engages a fuel rack collar 50 that
positions a fuel rack 51. The purpose of the fuel air
ratio controller 31 is to resist the movement of the
fuel rack 51 during acceleration and to coordinate
movement of the fuel rack 51 with the amount of air
available in the intake manifold (not shown). The
construction and operation of the fuel air ratio
controller is described in the U.S. patents to Miller
and Little cited above.
''
~36~
--8--
Industrial ApplicabilitY
Referring to Fig. 1, the regulator 7 controls
the fluid pressure in the controlled air conduit 29 as
a function of the rotation of the speed input shaft 8.
The speed input shaft is operatively connected to the
crankshaft of an engine (not shown) so that the shaft 8
turns at an integral multiple of the speed of the
engine. The regulator is connected to a source of
fluid pressure such as the intake manifold of a
turbocharged engine via the supply conduit 26. The
regulator is also vented to the atmosphere through the
vent conduit 28.
In operation, the engine turns the speed input
shaft 8 at a multiple of the crankshaft speed. If the
input shaft 8 increases in speed, the fly-weights 17
tend to move outward away from the axis of rotation and
thus the toes 18 tend to move the spool valve 21a in an
upward direction via the actuator member 19. This
upward motion tends to connect the fluid pressure in
conduit 26 to the controlled air conduit 29 via the
lower relieved portion 23 of the spool valve. When the
pressure in conduit 29 increases, the pressure in the
cavity 34 under the cover 35 increases via passage 38
and tends to force the top of the spool valve 21a in a
downward direction against the upward force of the
fly-weights. The pressure in conduit 29 is increased
until the control land 24 again covers the controlled
air conduit 29. A balanced condition results with a
predetermined pressure in conduit 29 and with the
fly weight force exactly opposing the spring and output
pressure forces.
When the speed of the shaft 8 decreases, the
fly-weights 17 tend to move toward the axis of rotation
which causes the spool valve 21a to move in a downward
direction. In addition, the elevated pressure in
.,
, : .
- ~ ~
g
conduit 29 also acts through passage 38 to Eorce the
spool valve in a downward direction. When the spool
valve moves downward, the control land 24 vents conduit
29 to the atmosphere via the upper relieved portion 22
of the spool valve 21a and the vent conduit 28. This
venting lowers the force on the top of the spool valve
and tends to permit the spool valve to move upward.
The pressure in conduit 29 is thereby decreased until
the control land 24 again covers the controlled air
conduit and the opposing forces are balanced.
The regulator 7 through the predetermined
pressure in conduit 29 controls the pressure in the
upper chamber 45 of the fuel air ratio controller 31.
This controller, in turn, controls the position of the
fuel rack 51 which regulates the amount of fuel
delivery per pump stroke to the cylinders of the engine
(not shown). When the pressure in the upper chamber 45
of the controller 31 increases, the bolt 49 permits a
larger amount of fuel delivery to the cylinders. The
opposite occurs when the pressure in the upper chamber
is decreased.
When the fuel rack 51 is positioned for
maximum horsepower at rated speed and the engine is
then placed under load so that it begins to lug, the
fuel pump (not shown) automatically increases the
delivery of fuel to the cylinder. This increase in
fuel delivery is a function of the change of e-Eficiency
of the fuel pump as the engine speed decreases. As
described in detail above, when the engine lugs down~
the speed input shaft 8 turns at a slower speed. This
slower speed decreases the fly-weight force and along
with the pressure in the passage 38 causes the spool
valve to move downward. This vents a portion of the
air pressure in the upper chamber 45 out to the
,~
'' ~ ' '' ~" ,.
~ ~1 5~
-9a-
atmosphere through the vent conduit 28. The diaphragm
47 in turn moves the rack 51 to reduce the amount of
fuel delivery.
Fig. 2 illustrates the performance curves
..
~ , ,
.
--10-
of an engine that utilizes a rotation sensitive
pressure regulator 7 according to the present
invention. Graph 56 is the curve of torque (brake
mean effective pressure in kPa or psi) vs. engine
speed (rpm). Graph 57 illustrates the production of
smoke vs. engine speed, and graph 58 illustrates the
position of the fuel rack with respect to engine
speed. In graph 58 zero indicates the center of the
travel of the rack and the graph has an abscissa of
plus or minus (.254 cm) (0.10 inches) either side of
center.
Referring to graph 58, Fig. 2, Point A
indicates the high idle position where at 2200 rpm
there is no load on the engine. Point B is the
balance point where maximum horsepower is developed
at the rated speed of the engine.
If the eng~ne is started at high idle with
no load (Point A) and then is increasingly loaded,
the fuel rack moves from Point A to Point B as the
engine speed decreases. Once Point B is reached, the
rack position is fixed against a mechanical stop (not
shown) and the engine beings to lug. The horizontal
portion of graph 58 is termed "the fixed rack lug
curve.'l As the engine is loaded down from 2000 rpm
(Point B) the torque developed on the engine rises as
indicated by graph 56. In addition, the production
of smoke increases as illustrated by graph 57.
The broken line portions of the performance
curves below 1400 rpm illustrate the operation of the
engine if the speed sensitive pressure regulator 7 and
the fuel air ratio controller 31 are not used. As
shown below 1400 rpm the torque developed by the
engine peaks and then falls off (graph 56), the
production of smoke increases dramatically (graph 57),
and the position of the fuel rack remains fixed (graph
58) .
5~
--11--
On an engine equipped with a rotation
sensitive pressure regulator 7 and a fuel air ratio
controller 31 as described above, the production of
smoke and the elevation of torque is substantially
changed when the engine speed decreases below 1400
rpm. On graph 58 Point C illustrates where the
regulator begins to take effect. At that point the
fuel rack is moved in a negative direction and the
amount of fuel delivered to the cylinders per stroke is
decreased. In graph 56 it can be seen that at 1400 rpm
and below the torque developed by the engine is
dramatically decreased. In addition, the production of
smoke is likewise limited at engine speeds below 1400
rpm.
Referring to Fig. 2, the effect of the
pressure regulator 7 is indicated by the upward sloping
linear curve 65. The slope of this curve is fixed by
the number, mass, and geometry of the fly-weights and
the area of the top of the spool valve 21a. The
position of this curve crosses 65 along the horizontal
axis is controlled by the spring 40. That is to say,
the spring controls the speed at which Point C occurs
which is the point at which the regulated fuel rack
curve 65 crosses the fixed rack lug curve~ For
example, if the compression on the spring is increased,
starred curves 56', 57' and 65' are produced. Thus, it
can be seen that by adjusting the compression of the
spring, the maximum elevation in torque and the net
production of smoke can be controlled by the apparatus
described herein.
In summary, the present invention controls
the generation of smoke and limits the rise in
engine torque by pulling the fuel rack back when the
engine lugs. Stability of the system and reliable
' '' ' '
-12-
performance are obtained by utilizing the spool valve
21a, the actuator member 19 and the spring 40.
Other aspects, objects, and advantages of this
invention can be obtained from a study of the drawings,
the disclosure and the appended claims.
' ' ~ ' ' ` ' '
j, : , ' . . ~` . ".
'
