Note: Descriptions are shown in the official language in which they were submitted.
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Description
ENGINE LUBRICATION SYSTEM
Technical Field
This invention relates to a lubrication
system for an engine, and more particularly to a
system having a prelube pump and means for preventing
the supply of lubrication fluid from reaching certain
elevated components when the engine is not running.
Backqround Art
U.S. Patent No. 4,270,5S2 which issued to
Oberth, et al. on June ~, 1981 illustrates a
lubrication system for relati~ely large engines. In
such engines, it is desirable to prelube the engine,
i.e. to force the lubrication of the engine prior to
startup so that certain components such as the
crankshaft, connecting rods and the camshaft bearings
are properly lubricated. If the bearings are not
provided with sufficient lubrication at the initial
rotation of the engine, damage of the bearings could
occur. Normally, a preestablished time delay prevents
the starting circuit from being energized until
prelube has been accomplished. For example, due to
the size of the larger engines it may require several
minutes to pump lubricating fluid to the bearings by
way of the various engine galleries and passages.
Engines used to power standby generators or
the like, must be started in a matter of seconds in
order to respond to an emergency. Prelube for these
engines is accomplished by continually pumping
lubrication fluid to the bearings of the crankshaft,
camshaft and rocker arms, and this permits the engine
to be started without delay.
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Typical prior art prelube systems have an
electric or air driven pump separate from the main
engine pump that supplies lubrication fluid to the
engine when the engine is not running. Starting of
the engine where the prelube pump has failed, whether
by a los~ of power to drive the pump or a problem with
the pump itself, could r~sult in a drastic reduction
in the service life of the engine.
During long periods of continuous prelube,
where the engine has not run for a considerable amount
of time, lubricating fluid being pumped upward into
the rocker arm area drips onto the valve mechanism,
and can even run down valve guides, past any open
valve into one or more of the engine combustion
chambers. An accumulation of the incompressible fluid
in a combustion chamber while cranking the engine
could result in the damage of expensive engine
` components and require a considerable amount of time
- to repair.
Accordingly, what is desired is a
lubrication system that will prevent lubrication fluid
from entering certain elevated portions of an engine
such as the rocker arm area, where fluid could
otherwise find its way into a combustion chamber, when
the engine is not running. The system must not be
affected by engine oil temperature, viscosity or a
wide range of prelube pump capacities and pressures.
Moreover, when the engine is running the system must
allow the supply of lubrication fluid to promptly
reach the rocker arm area for lubrication of the valve
operating mechanism. Also what is desired is a system
that allows the engine starting mechanism to be
energized solely when it is sensed that there is a
sufficient supply of lubrication ~luid in the critical
areas of the engine, and to prevent the starting
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mechanism from being energized if there is an
insufficient supply.
The present invention is directed ~o
overcoming one or more of the problems as set forth
above.
Disclosure of the Invention
In one aspect of the invention, an angine
lubrication system is provided with a first
lo pressurized source of lubrication fluid when the
engine is not running, a s~cond pressurized source
when the engine is running, first means or preventing
the supply of lubrication fluid from reaching the
rocker arm area when the engine is not running and
second means for disabling the first means when the
engine is running and allowing lubrication fluid to
reach the rockPr arm area.
In another a~pect of the invention, an
engine lubrication system is provided with pressurized
source of a lubrication fluid when the engine is not
running, a device for establishing a preselected
maximum elevational height of lubrication fluid
accumulated in the engine from the pressurized source
when the engine is not running, and means for
ef~ectively blocking and disabling the device when the
engine is running.
In another aspect of the invention, sensor
means senses the presence of a lubrication fluid in
the engine at a preselected elevational level above
the normal elevational range in the sump from a
prelubxiaation pressure source, allows the starting
mechanism to be energized, and prevents the starting
mechanism from being energized if there i5 no presence
of lubrication fluid thereat.
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srief Description of the Drawinqs
Fig. 1 is a diagrammatic illustration of an
engine utilizing a lubrication system in accordance
with the present invention; and
Fig. 2 is a greatly simplified diagrammatic
end elevational view of an engine with a portion
broken away to show details o~ construction thereof,
and illustrating in broken lines the internal
lubrication galleries and passages thereinO
Best Mode for Carryin~ out the Invention
Re~erring now to Figs. 1 and 2, a
lubrication system 10 is shown for a relative large
internal combustion engine 12 of the type used to
drive emergency standby generators, pumps or the like.
The engine 12 includes a block 14 having a
top head mounting surface 16, a plurality of cylinder
heads 18 removably secured to the top surface, a fluid
reservoir or sump 20 for holding an engine lubricant
such as oil and having a normal maximum elevational
range of lubrication fluid therein, and a plurality of
cylinders 22, one of which is shown. In the specific
instance the sump 20 is integral with the engine 12,
but it is recognized that the sump could be remotely
2~ located. Each cylinder 22 has a piston 24 slidably
disposed therein for driving a crankshaft 26 in a
conventional manner. The crankshaft 26 i5 rotatable
supported in the engine 12 by a plurality of bearings
one of which is shown at 28.
As representatively illustrated, each
cylinder 22 has at least one valve 30 that is slidably
disposed in a cylindrical guide 32 formed in the
cylinder head 18 and opening into a combustion chamber
34 formed by the cylinder head 18, the cylinder 22,
and the piston 24. A oscillating rocker arm 36 acts
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on the valve 30 in response to rotation oE a camshaft
38 supported in the engine 12 by bearings, one of
which is shown at 40. The valves 30 control the flow
of inlet air and exhaust gases into and out of the
cylinders 22 during engine operation in a conventional
manner. A plurality of covers 42 are removably
secured to ~ach cylinder head 18 and define an upper
rocker arm area 44 elevationally spaced above each
cylinder head.
The lubrication system 10 includes a first
pressure source 46, a second pressure source 48, a
lubricant temperature regulator 50, a lubricant cooler
52, a plurality of lubricant filters 54 and a first
means or a ~luid level control device 56 for
preventin~ the supply of l~bricant from reaching the
rocker arm area 44 under certain conditions, and a
infinitely variably, pressure actuated,
three-position, priority valve 64~
The engine 12 further includes a main fluid
gallery 66 and a secondary fluid gallery 68 integral
with the block 14. The priority valve 64 is in fluid
communication with the secondary fluid gallery 68 and
with the sump 20. A plurality of passages, one of
which is shown at 70, transmit lubricant downward from
the main fluid gallery 66 to the bearings 28 for the
crankshaft 26. Lubricant is also transmitted from the
main fluid gallery 66 upward to the bearings 40 for
the camshaft 38 by a plurality of passages one of
which is shown at 72. From the bearings 40 lubricant
is transmitted to the rocker arm area 44 by a
plurality of passages in the block 14 and the heads
18, one of which is shown at 74. Lubrication is
transmitted from the secondary ~luid gallery 68 to a
; plurality of jets, one of which is shown at 76, for
cooling of the pistons 24.
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The first pressure source 46 includes a
prelube pump 78 in fluid communication with the sump
20 via a conduit 80, and is operable only when the
engine 12 is not running. The prelube pump 78 is of a
relatively low capacity, and has a low pressure
capability. By the term low capacity it is meant
approximately 23 liters per minute (6 gpm) by the term
low pressure it is meant approximately 137.8 kPa
(20 psi). In this specific instance the prelube pump
82 is driven by an AC electric motor 82 which receives
power ~rom an electrical source 84 having for example
220 volts. It is also recognized that the prelube
pump 78 could be driven by a DC electric motor or an
air motor.
Lubrication fluid is supplied from the
prelube pump 78 via a conduit 86 to an inlet conduit
88 that connects with the priority valve 64 and the
main fluid gallery 66. The regulator housing 50,
cooler 52, filters 54 and fluid level control device
56 are located in the inlet conduit 88. A one way
check valve 89 is located in conduit 86. Fluid is
also supplied via a branch conduit 90 to the priority
valve 64. A lubrication system relief valve 92 is
connected to the conduit 88 and has a relief setting
of for example 1000 kPa (145 psi). The priority valve
64 is connected to the secondary fluid gallery 68 via
a conduit 98 and to the sump 20 via a conduit 100.
The priority valve 64 is biased downward,
whQn viewing Fig.l, by a spring 104 towards a first
position 106 as shown blocking the delivery of the
fluid from the inlet conduit 88 to the secondary fluid
gallery 68 until the pressure in the inlet conduit 88
reaches a value to overcome the bias of the spring in
a manner to be described presently. In the ~irst
position 106 the conduit 100 connected to the sump 20
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is blocked. The priority valve 64 has a second
position 108 in which the fluid is modulateably
directed to the secondary fluid gallery 68 and the
conduit 100 remains blocked and a third position 110
wherein fluid is modulateably directed to the second
fluid gallery and to the sump 20 via conduit 100 from
conduit 90. It is noted that flow to the main îluid
gallery 66 is never obstructed in any way.
The ~Eluid level control devic::e 56 in the
inlet conduit 88 establishes a preselected maximum
elevational height of the lubrication fluid
accumulated in the engine 12 from the prelube pump 78.
The device 56 includes a spillway 118 connected to a
return conduit 120 connected to the sump 20 of the
engine 12. Preferably the slevational height "S" of
the spillway 118 is above the normal maximum
elevational range of the lubrication fluid in the sump
20 or adjacent or slightly below the top surface 16 of
the block 14. In all instances the spillway 118
should be above the camshaft bearings 40 and below the
upper rocker arm area 44.
Second means or a disabling apparatus 121
for blocking the fluid level control device 56
includes in this specific instance a pilot operated,
two position valve 122 located in the return conduit
120. The valve 122 is biased to the left when viewing
Fig. 1 towards a first normally open position 124 by a
spring 126 that permits unrestricted flow of fluid to
the sump 20 via conduit 120 until a pilot pressure in
a pilot line 130 connected between the valve 122 and
the conduit 90 reaches a value to overcome the spring
and shift the valve to a second position 128. In the
second position 128 flow is blocked to the sump 20
disabling the device 56. It is recognized that the
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two position valve 122 could also be pneumatic or
electrically operated.
One side of a start switch 134 is connected
to a pow~r source 136 such as a battery 138 via an
electrical line 140. This electrical line 140 can be
interrupted by an enyine speed sensing switch 142.
The opposite side of the start switch 134 is connected
to an air start solenoid valve 144 for operation o~ an
air starting motor, not shown, which is used to crank
the engine 12 in a conventional manner. The opposite
side of the solenoid valve 144 is connected to an
electrical ground 146 via an electrical line 148 and a
sensor or liquid-level detector 150. A siynal light
152 is lighted when an electrical circuit is completed
through the detector 150.
The detector 150 is preferably attached to
the block 14 and has a probe portion 154 that extends
into one o~ the passages 74 ~or sensing the presence
of lubrication fluid therein. Preferably the
elevational height "P" of the probe 154 above the
normal range o~ maximum fluid level in the sump 20 is
adjacent or slightly below the top surface 16 of the
block. In all instances the probe 154 will be located
at an elevational level above the camsha~t bearing 40
and at or below the spillway 118. The detector 150 is
of the type marketed by Robertshaw Controls Company,
Tennessee Division, Knoxville, Tennessee as model 624.
Electrical energy is also provided via an
electrical line 156 to a solenoid switch 158 which
controls when electrical energy is directed to the
electric motor 82. The second pressure source 48
includes a helical gear primary pump 160 driven, in
this speci~is instance, by the engine 12. It is
recognized that the pump 160 could alternatively be
driven by air or an electric motor. The pump 160 is
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in fluid communication with the sump 20 via thP
conduit 80 and connected via a conduit 162 to the
conduit 88. The pump 160 is operable only when the
engine 12 is running and is of a relatively high
capacity and is capable of supplying lubricant at
moderate pressure levels via the lubrication system 10
to all areas of the engine 12 that requires
lubrication including the camshaft bearings 40, the
crankshaft bearings 2~ and the upper rocker a~m area
44. By the term high capacit~ it is meant less than
approximately lOoo to 1800 liters per minute (260 to
468 gailons per minute~ and by the term moderate
pressure level it is meant less than approximately
1000 kPa (145 psi).
Industrial Applicability
With the engine 12 in the standby mode
lubrication fluid is pumped by the prelube pump 78
from the sump 20 at a relatively low pressure to the
main fluid gallery 66 and to the passages 70, 72, and
74 for lubrication of the cranXshaft bearings 28 and
the camshaft bearings 40. The prelube pump 78 is
driven by the electric motor 82 which receives
electrical energy from source 84. Prelubrication of
the critical areas of the engine 12 permits the engine
to be started in a matter of seconds without damage to
the engine.
Lubrication fluid is pumped via inlet
conduit 88 through the regulator 50, the filter
assembly 54 and the level control device 56 to the
priority valve 64 and to the main gallery 66. Fluid
to the secondary gallery 68 is blocked by the priority
valve 64. Fluid will fill the passages 70, 72 and 74
until it reaches a predetermined elevational height
"S" above the normal range of maximum fluid level in
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the sump 20 to a level as det rmined by the spillway
118 of the control device 56. Whereupon exc~ss
lubrication fluid accumulated in the engine 12 is
returned into return conduit 120 where it is returned
to the sump 20 in a unrestricted manner. The system
has the advantage of not being affected by engine oil
temperature, viscosity or a wide range of prelube pump
78 capacities and pressures. Valve 122 is biased to
it normally open position by the spring 126 when the
engine 12 is stopped. The control device 56 prevents
the supply of fluid from reaching certain elevated
portions of the engine 12 such as the upper rocker arm
area 44. In this specific instance the level of fluid
in the engine 12 is maintained at slightly below the
top surface 16 of the block 1~ and above the camshaft
bearings 40. It is readily recognized that for a
predetermined elevational location of the control
device 56 a specific l~vel of fluid in the engine can
be controlled.
The probe 154 of the liquid detector 150
extends into one of the passages 74 at a preselected
an elevational height "P" above the normal range of
maximum fluid level in the sump 20 is adjacent or
slightly below the elevational level of the spillway
118. The probe 154 produces a change in electrical
"capacitance" when liquid displaces air immediately
surrounding the probe. The electrical capacitance
change is then converted within the unit into an
on-off solid state switch closure to indicate the
absence or the presence of fluid around the probe 154.
The detector 150 is used to determine if there is
lubrication fluid present in passage 74 at the
elevational level of the probe 154. If there is a
presence of fluid the eleotrical circuit between the
solenoid valve 144 and the electrical ground 146 will
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be completad. Signal light 152 will be lighted when
the circuit through the detector 150 is completed. By
then closing start switch 134 the solenoid valve 144
for the starting motor will be energized permitting
the engine 12 to be started. In the absence of fluid
in the passage 74 the detector will not complete the
circuit between the solenoid valve 144 and the ground
146 and the engine 12 can not be started. Absence of
fluid in the conduit 74 at the lev~l of the probe 154
would be an indication that the bearings 28 and 40 may
not be receiving prelubrication and it would be
detrimental to start the engine 12 without possible
damage to expensive engine components.
With tha presence of electrical energy at
the solenoid switch 158 the switch will be closed and
the motor 82 will receive power from the electrical
source 84 to drive the motor. When engine 12 is
started, the engine driven pump 160 becomes the source
of pressurized fluid for the lubrication system 10.
The pressure in the system 10 is dependent upon the
speed of engine 12. Upon a rise of the pressure in
conduit 88 and pilot line 130 to a point that exceeds
a level as determined by the preload o~ the spring 126
of valve 122 the valve will shift to its second
position 128 blocking the ~low of ~luid to ~he sump 20
from the fluid level control device 56 via conduit 120
disabling the device 56. ~hus all the flow from pump
160 is directed to the main fluid gallery 66.
When the engine 12 is operating at a
preselected speed, for example 250 revolutions per
minute, as sensed by speed sensing switch 142 the
elect~ical energy to the solenoid switch 158 from the
battery 138 is interrupted by the sensing switch 142.
This opens the solenoid switch 158 preventing
electrical energy ~rom the source 84 to reach the
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motor 82. Once pump 78 is stopped fluid from the
relatively high pressure engine driven pump 160 is
prevented from flowing through line 86 by the check
valve 89. Because of the close internal working
tolerances of the helical gear pump 160 fluid is
prevented from flowing back through the pump to the
sump 20 when the relatively low capa~ity and low
pressure prelube pump is operating.
Once the engine 12 is operating at a
sufficient speed so that the pump 160 is producing
fluid above a pressure for example 1~0 kPa t20 psi)
the pressure in inlet conduit ~8 will exceed a level
as determined by the preload of spring 104 and the
priority valve 64 will be shifted to its second
position 108. In the position 108 lubrication fluid
will be modulateably directed from the inlet conduit
88 to the secondary gallery 68 and to the cooling jets
76 for cooling of the pistons 24.
When the engine 12 is operating at even a
higher speed so that the pump 160 is producing a
pressure of for example 430 kPa (63 psi) the pressure
in inlet conduit 94 will exceed a level as determined
by the preload of spring 104 and the priority valve 64
will be shifted to its third position 110. In the
position 110 lubrication fluid will be modulateably
directed from the inlet conduit 88 to the secondary
gallery 68 and from conduit 90 to the sump 20 via the
conduit 100. The third position 110 of the priority
valve 64 provides a bypass of a portion of the ~luid
from pump 160 to the sump 20 so that smaller size
cooler 60 and filter assembly 62 can be used. This
assures that any reasonably small pressure loss which
may take place in the filters does not in any way
effect the regulation of the operating pressure at the
main gallery 66 and the secondary gallery 68. For a
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more complete understanding of the operation of the
priority valve 64 reference is made to the U.S. Patent
No. 4,270,562 referred to aboveO
In summary, it can be appreciated that when
the engine 12 is not running and the engine is being
prelubricated, lubricant is prevented from reaching `
certain elevatsd portions o* the engine such as the
upper rocker arm area 44 by a fluid level control
device 56 that establi~hes a pre~elected maximum
elevational height of the lubricant in the engine by
returning excess fluid to the sump 20. When the
engine 12 is running the control device 56 is disabled
by the blocking the return of fluid to the sump 20 and
allowing the supply of lubricant to reach the rocker
arm area 44 for lubrication of the valve operating
mechanism. A fluid detector 150 senses the presence
of fluid in the passage 74 at a preselected
elevational height. When it is sensed that there is a
sufficient supply of lubricant in the critical area of
the engine the engine start mechanism can be
energized. Because the lubricant in the engine 12 is
maintained at a relatively high level, lubrication
fluid will promptly reach the rocker arm area 44 when
the engine is started.
Although the present system has been
described and disclosed with respect tv an inline type
engine 12, it is recognized that the system could
equally be used on vee type engines.
Other aspects, objects and advantages can be
obtained from a study of the drawings, the disclosure
and the appended claims.
