Device for altering cam profile

A rocker arm adapter for use in the timing mechanism of an internal combustion engine is disclosed. The adapter is a method for altering the cam profile of the exhaust valve of the engine with respect to the intake valve. It includes a fluidic delay device mounted in either the first end or the second end of the rocker arm. The delay device includes a piston which is allowed to move various distances in a cavity formed in the rocker arm, the distance being directly related to the speed of movement of a push rod member. As the speed of the engine, and the speed of movement of the push rod, increases, the piston will be allowed to move a greater distance into the cavity so that the delay in actuation of the rocker arm by the push rod is increased.

TECHNICAL FIELD 
The invention refers to internal combustion engines having components which 
control cam action for operating the valves to effectuate more efficient 
and economic engine operation. 
BACKGROUND OF PRIOR ART 
Because of a number of factors, not the least important of which is the 
rising cost of gasoline, the development of automobiles which have engine 
components to accomplish efficient and economic use of gasoline fuel has 
become an urgent project of the world's technological community. Nor is 
there any indication that fuel costs will decline in the foreseeable 
future so as to reduce the importance of the development of inventions 
which effectuate more efficient combustion of the air/fuel mixture fed 
into the engine cylinders. 
In the four-stroke gasoline engine powering many automobiles, operation of 
the inlet and exhaust valves for each cylinder is coordinated with the 
position of the piston within the cylinder. During the first stroke of the 
piston, the induction stroke, the inlet valve is open so that an air/fuel 
mixture fed to the cylinder inlet from the carburetor via an intake 
manifold can be admitted into the cylinder. During the compression stroke 
the piston moves upwardly within the cylinder to compress the air/fuel 
mixture. During this stroke, therefore, both the inlet and exhaust valves 
must be closed. 
The third stroke, or power stroke, involves downward movement of the piston 
in response to combustion of the air/fuel mixture when it is ignited by a 
spark provided by a spark plug. Again, both valves must be closed in order 
to effectuate maximum downward force upon the piston. If one or both of 
the valves were open, the gases, while expanding, would, at least 
partially, be allowed to be vented through the open valve. 
The exhaust stroke begins as the piston again begins upward movement within 
the cylinder. During this stroke the exhaust valve must be open so that 
the by-products of combustion can be vented therethrough. After venting of 
these by-products occurs, the exhaust valve closes and the inlet valve 
again opens in order to begin a new cycle. 
Normally, the valves are biased to a closed position, and they are open 
according to a predetermined timing schedule. This timing is coordinated 
by a cam-push rod-rocker arm arrangement provided for each valve. As the 
cam rotates, it translates its rotary motion into axial motion of the push 
rod. The push rod, in turn, causes pivoting of the rocker arm to open the 
particular valve involved. Rotation of the cam is geared to rotation of a 
crank shaft common to all cylinders in the engine. The crank shaft is made 
to rotate by use of a connecting rod extending from the piston in each 
cylinder. Consequently, the up and down movement of the piston within the 
cylinder can be translated into appropriately timed opening and closing of 
the respective inlet and exhaust valves of the particular cylinder. 
In some engines, the volume of the air/fuel mixture introduced into the 
cylinders is dependent upon the speed of the engine and the particular 
mode of operation thereof. Specifically, if the engine is in a period of 
acceleration, the volume of fuel being admitted to the cylinder will 
likely be greater than during a period of constant speed cruising, 
deceleration, or idling. If the cam profile has not been varied, the 
valves will open in accordance with the same timing schedule as it would 
during other modes of operation of the engine, and complete and efficient 
combustion of all of the air/fuel mixture will not occur. 
Technology has provided devices to cure this defect to some degree. 
Different methods have been invented to alter the cam profile so that the 
exhaust valve stays closed longer and the intake valve opens later in 
order to effect more complete burning of the air and fuel. These devices 
are mechanical means which delay the opening of the exhaust valve and 
opening of the intake valve a fixed amount regardless of the speed and 
operational mode of the engine. Consequently, in certain modes of 
operation, complete and efficient combustion may have already occurred, 
and the valves have not yet opened. This gives rise to less efficient 
operation of the engine. 
Although valve opening and closing occurs at a high rate of speed, maximum 
engine efficiency is frequently not attained because of comparatively 
sluggish valve actuation. A high valve lift rate or speed of valve opening 
can improve performance significantly over that obtained where valve lift 
rate is low. 
It is to these problems to which the invention of the present application 
is directed. It provides a structure which effectuates an alteration in 
the operation of the intake and/or exhaust valves which is directly 
proportional to the engine speed. The alteration of valve operation, such 
as a delay in the opening of the intake valve, is directly proportional to 
the quantity of gasoline introduced into the cylinder. It, therefore, 
maximizes the efficiency of combustion regardless of the speed at which 
the engine operates and the richness of the air/fuel mixture. 
SUMMARY OF THE INVENTION 
The present invention is a device operable to alter the operation of a cam 
during use of the cam to transmit motion and force from the cam to a cam 
follower. The device has body means having a cavity accommodating manifold 
means and defining a first chamber means and a second chamber means for 
accommodating a fluid, such as a liquid. The second chamber means is 
separated into a plurality of chambers having different volumes. Each 
chamber has means for moving fluid out of the chamber. The manifold means 
has inflow passage means and diversion passage means obliquely 
intersecting the inflow passage means and open to the second chamber. The 
manifold means also has a plurality of outflow channels open to the inflow 
passage means and the plurality of each of the chambers. The piston means 
is movably mounted on the body means closing the second chamber means. A 
fluid fills both chamber means and passages and channels between the 
chamber means. In use, when movement from the cam is transferred to the 
piston means, the fluid in the second chamber means is forced through the 
inflow passage means and diversion passage means. The fluid in the 
diversion passage means shunts fluid in the inflow passage means into one 
or more outflow channels in accordance with the amount of force applied to 
the piston means. This provides additional volume or storage space for the 
fluid. The result is that the effective length of the device is changed in 
accordance with the force applied to the piston means. The greater the 
force, the greater the change in the length of the device. When the device 
is used with rotating cams, the speed of rotation of the cams is a 
function of the force transferred from the cams to the cam followers. 
Thus, the device changes the cam profile of a rotating cam. 
The fluid is preferably a liquid, such as oil. Special liquids that have 
the property of varying viscosity in response to the amount of pressure 
applied to the liquid can be used in the device. When this type of liquid 
is used in the device, the operation of the cam is altered during periods 
when the cam speed is increasing and decreasing. The operation of the cam 
is not substantially altered when it is operated at a constant speed. 
In one embodiment, the device is an adapter for use with the rocker arm of 
valves of an internal combustion engine of the type typically used in an 
automobile. It has as an objective the altering of the cam profile of one 
or both of the intake and exhaust valves of the engine. The adapter alters 
or changes the cam profile varying amounts depending on the speed of the 
engine. A conventional Otto cycle internal combustion engine has a rocker 
arm mounted in a see-saw manner for pivoting movement between first and 
second positions. The rocker arm has a first end engaged by a push rod 
adapted for longitudinal movement in response to cam actuation, and a 
second end engaging a valve stem of the exhaust valve of the engine. The 
rocker arm, as it moves from the first to its second position, opens the 
valve by overcoming a spring bias urging the valve to its closed position. 
The device includes a piston which is mounted for movement into and out of 
a cavity formed in a body associated with either the first or second end 
of the rocker arm. The portion of the rocker arm which comprises or 
engages the piston cooperated with either the push rod or the valve stem, 
depending upon the end of the rocker arm in which the cavity is formed. 
The device further includes means for precluding movement of the piston 
beyond certain defined positions which are dependent upon the speed with 
which the push rod longitudinally moves. When the cavity is formed in a 
body associated with the first end of the rocker arm, that is, the end 
which is engaged by the push rod, movement of the push rod toward the 
rocker arm will, for a time, be absorbed as the piston moves into the 
cavity a predetermined distance. After further movement of the piston is 
prohibited, the longitudinal movement of the push rod will be translated 
into pivoting movement of the rocker arm. This pivoting movement will, in 
turn, effect opening of the valve of the cylinder. In an embodiment in 
which the cavity is formed in a body associated with the second end of the 
rocker arm, the rocker arm will respond immediately to the longitudinal 
movement of the push rod toward the rocker arm. Opening of the valve will 
be delayed since the piston engagement with the end of the valve stem is 
moved into the cavity by the resistance of the bias urging the valve 
closed. When movement of the piston becomes precluded, the valve will 
respond to the pivoting movement of the rocker arm and open the valve. 
In a preferred embodiment, the distance which the piston will be allowed to 
move into the cavity in response to the speed of the push rod includes a 
manifold member mounted on the body in the cavity. The manifold member is 
fixedly mounted within the cavity to define an exterior chamber between 
one end of the member and the piston, and a plurality of variable volume 
interior chambers on the opposite side of the member. Each interior 
chamber has a maximum volume to which it can expand, and these maximums 
vary from chamber to chamber. 
In this embodiment, the exterior chamber is filled with a fluid. Fluid 
communication is provided from the exterior chamber to each of the 
interior chambers by a passageway network provided through the manifold 
member. An inflow passageway communicates with the exterior chamber and 
divides into a plurality of outflow channels, each of these channels 
entering into a different one of the interior chambers. 
Means are provided for channeling the bulk of fluid flow from the exterior 
chamber through the inflow passageway in response to piston movement, into 
a different one of the outflow channels depending upon the speed of the 
longitudinal movement of the push rod. When the speed of the push rod is 
great, fluid flow through the inflow passageway is directed to the outflow 
channel entering into that interior chamber having the greatest maximum 
volume to which any interior chamber can expand. As the longitudinal speed 
of movement of the push rod decreases, the bulk of fluid flow through the 
inflow passageway is redirected into an outflow channel which enters into 
an interior chamber having a maximum expansible volume smaller than that 
chamber into which the fluid flow empties at the higher rate of speed of 
the push rod. The bulk of flow through the inflow passageway is channeled 
into various other outflow channels entering into inner chambers having 
variable volumes expansible to maximum volumes progressively smaller as 
the speed of the push rod decreases even further. 
This channeling of flow can be accomplished by providing a diversion 
passageway communicating at one end with the exterior chamber and in which 
fluid flow is induced by movement of the piston. The diversion passageway 
intersects at its opposite end with the inflow passageway, and this 
intersection is oblique with respect to a directional axis along which the 
inflow passageway is oriented. Thus, as the speed of fluid flow through 
the diversion passageway, which speed is directly proportional to the 
speed of movement of the push rod, increases, flow through the diversion 
passageway will effect a greater deflection of the fluid flow through the 
inflow passageway. The outflow channel which flows into the interior 
chamber having the greatest maximum volume can, therefore, be disposed 
with respect to the directional axis along which the inflow passageway is 
oriented so that there is a degree of angular variation therebetween 
commensurate with the amount of fluid flow deflection which occurs at a 
high speed of longitudinal movement of the push rod. At low speeds of push 
rod movement, flow through the inflow passageway may be diverted only 
slightly, or even not at all. The outflow channel entering into the 
interior chamber having the smallest maximum volume can, therefore, be 
oriented substantially along the directional axis of the inflow 
passageway. Other outflow channels can have a measure of angular variation 
from the directional axis of a measure somewhere between that of the two 
channels heretofore discussed. 
When the device of the invention is used with a cam, push rod and rocker 
arm associated with an internal combustion exhaust valve, there is a time 
delay in the opening of the exhaust valve. The amount of time delay 
depends on the speed of operation of the engine. The greater the speed of 
the engine, the greater the delay in opening the exhaust valve up to a 
predetermined time delay. The delay in opening the exhaust valve causes a 
retention of some of the burned gases in the combustion chamber of the 
engine. These gases are stratified with the air/fuel mixture introduced 
into the combustion chamber on the intake stroke. A fuel saving is 
achieved since a smaller amount of fuel will produce a mixture rich enough 
to ignite when the spark plug fires. 
When the device of the invention is used with an intake valve, the cam 
profile limits the amount of air/fuel mixture introduced into the 
combustion chamber by delaying the opening and advancing the closing time 
of the intake valve. The fluidic circuit of the device is programmed along 
the entire RPM range of the engine to provide a valve opening delay 
responsive to engine speed. 
The invention of this application is a fluidic controlled device which 
alters the cam profile varying amounts depending upon the speed of 
movement of the push rod. The device can be adapted to be located in the 
motion transmitting means between the cam and valve stem. The device 
achieves automatic adjustment of valve clearance and operation. Specific 
advantages of the invention will become apparent with reference to the 
accompanying drawings, detailed description of the invention, and claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, wherein like reference numerals denote like 
elements throughout the several views, FIG. 1 illustrates a portion of the 
timing mechanism for a cylinder of an internal combustion engine. The 
timing assembly includes a cam 10 mounted on a cam shaft 12 for rotation 
therewith. Cam 10 has an eccentric peripheral surface 14 which is engaged 
by one end of a push rod 16. As cam shaft 12 rotates and push rod 16 rides 
up eccentric surface 14 of cam 10, the rotational motion of cam 10 is 
translated into longitudinal motion of push rod 16. 
A rocker arm 18 is pivotally mounted proximate the opposite end of push rod 
16. In FIG. 1, the rocker arm 18 is shown as being pivotally mounted for 
movement about a pivot 20 intermediate opposite first and second ends 22, 
24 of rocker arm 18. Rocker arm 18 pivots on pivot 20 in a see-saw 
fashion. 
A first end 22 of rocker arm 18 is in operative engagement with a fluidic 
device 44 of the invention. Device 44 engages the second end of push rod 
16. As push rod 16 moves longitudinally toward rocker arm 18, it will 
cause rocker arm 18 to move from a first position, which is the most 
counterclockwise position that the rocker arm 18 can assume, to a second 
position, which is the most clockwise position that rocker arm 18 can 
assume. 
Second end 24 of rocker arm 18 engages the outer end of a valve stem 26. 
Valve stem 26 extends from a main valve portion or head 28 which occludes 
an exhaust port 30 providing egress from combustion chamber 32 to an 
exhaust passageway 34. The valve 28 is normally biased toward a closed 
position with coil spring 36. Spring 36 engages a shoulder 38 on the 
engine block and a collar 40 attached to valve stem 26. 
FIG. 1 shows the valve head 28 in a closed position and rocker arm 18 in 
its first position. As cam 10 rotates in a direction clockwise as viewed 
in FIG. 1, push rod 16 will move longitudinally upward and to the right 
and cause rocker arm 18 to rotate in a clockwise direction to its second 
position. This will, in turn, cause valve head 28 to be urged downwardly 
to its open position, overcoming the bias of spring 36. This particular 
functioning will occur during the exhaust stroke of piston 42 mounted for 
movement within the cylinder in the block. 
It is known that, during the operation of an automobile internal combustion 
engine, a substantial quantity of the air/fuel mixture introduced into 
combustion chamber 32 is not effectively and efficiently burned. This 
problem can be remedied by delaying the opening of the exhaust valve so 
that the mixture can be combusted within the combustion chamber for a 
longer period of time. Various devices have sought to achieve a solution 
to the problem, but, in each case, the valve has been held closed only for 
a set period of time. Since the amount of combustible air/fuel mixture 
introduced into the combustion chamber varies depending upon the mode of 
operation of the engine, the amount of delay in opening the valve should 
also vary in order to obtain most efficient operation. 
A fluidic delay device, generally indicated at 44, made in accordance with 
the present invention effectuates this variable delay. Such a device is 
shown, in FIG. 1, mounted in the first end 22 of rocker arm 18. It will be 
understood, however, by those of skill in the art, that such a fluidic 
delay device 44 could just as appropriately be formed in the second end 24 
of rocker arm 18. The fluidic device can be located in push rod 16 or 
between the lower end of rod 16 and cam 10. 
Device 44 includes a piston 46 which is disposed within a cavity formed in 
a cylindrical body 45. Body 45 can be part of one of the ends of the 
rocker arm 18. Piston 46 includes a push rod engagement face 48 engaged by 
the upper end of push rod 16. In embodiments wherein the device is mounted 
on or formed in the second end 24 of rocker arm 18, face 48 of piston 46 
would engage the end of valve stem 26. 
Referring now to FIG. 2, the interior of the cavity formed in the body 45 
is illustrated. Piston 46 is disposed for movement into and out of the 
cavity. Positive means, such as a retaining ring 50, mounted on the inside 
of body 45, preclude complete withdrawal of piston 46 from the cavity. 
Mounted at a fixed location generally centrally within the cavity is a 
manifold member 52. Member 52 is maintained in a fixed axial position 
within the cavity by means of a retaining ring 54 mounted on the inside of 
body 45. 
An exterior or first chamber 56 is defined between manifold member 52 and 
piston 46. An interior or second chamber is defined between the opposite 
end of member 52 and the inner end of the cavity. This interior chamber 
is, in turn, subdivided into a plurality of smaller interior chambers 58, 
58', 58". FIGS. 2 and 7 show a cavity which is circularly cylindrical in 
cross section. The interior chamber is separated into three chambers 58, 
58', and 58". The first chamber 58 comprises a small circularly 
cylindrical chamber centrally positioned within the cavity. The second 
chamber 58' is an annular chamber surrounding the first chamber 58. The 
third chamber 58" is an annular chamber concentrically disposed about the 
second annular chamber 58'. Each interior chamber 58, 58', and 58" has a 
similar axial length, the volumes of these chambers increase in a radially 
outward direction. Each successive radially outward chamber 58, 58', 58" 
has a larger cross-sectional area than does the chamber immediately 
radially inward therefrom. 
The exterior chamber 56 is filled with a fluid, and fluid communication is 
provided between that chamber 56 and the interior chambers 58, 58', 58" 
through the manifold member 52. An inflow passageway 60 provides egress 
for the fluid from the exterior chamber 56. The inflow passageway 60 
thereafter divides into a plurality of outflow channels 64, 64', 64". The 
number of outflow channels 64, 64', 64" are the same as the number of 
interior chambers 58, 58', 58". 
Each interior chamber 58, 58', 58" can include means for normally 
maintaining said chambers empty of fluid. In one embodiment, these means 
can take the form of pistons 62, 62', 62" mounted within each chamber 58, 
58', and 58", respectively. These pistons are biased to occlude a second 
end of outflow channels 64, 64', 64" which empties into the respective 
interior chambers 58, 58', 58". Radial edges 66 of pistons 62, 62', 62" 
are sealed by use of O-rings 68 so that fluid caused to be passed through 
manifold member 52 will exert force on the face of pistons 62, 62', 62" 
rather than leaking around the edges 66. Similarly, piston 46 disposed in 
the exterior chamber 56 is sealed with an O-ring to preclude leakage of 
the fluid out of the cavity. 
Fluid delay device 44 includes means for precluding movement of piston 46 
operably disposed within exterior chamber 56 beyond various positions 
within this chamber. Movement of piston 46 can be precluded by preventing 
the volumetric expansion of the various interior chambers 58, 58', 58" 
beyond a certain volume as fluid in exterior chamber 56 is forced through 
the manifold member 52 and into the various interior chambers 58, 58', 
58". This is accomplished by providing a stop portion 70, 70', 70" on each 
piston disposed within the interior chambers so that each interior chamber 
cannot expand beyond a desired capacity. As each piston 62, 62', 62" is 
moved by the inflow of fluid through the outflow channels 64, 64', 64" and 
the volume of a chamber expands, the stop portion 70, 70', 70" attached to 
each piston engages base 72 of body 45 to preclude further expansion. 
It is pointed out that the bias of spring 36 urging valve 28 to its closed 
position must exceed the bias of an individual spring 74, 74', 74" urging 
each piston 62, 62', 62" operatively disposed within an interior chamber 
to a position adjacent manifold member 52. If the reverse were true, the 
motion of push rod 16 would not be absorbed by the fluidic delay device 
44, and the valve movement would directly correspond to the movement of 
push rod 16. Since, however, the relative biases are as stated, the device 
will function to delay opening of the valve even as push rod 16 moves 
longitudinally. 
The aggregate biasing effect of two of the springs 74, 74', 74" within 
interior chambers 58, 58', 58" exceeds the biasing effect of spring 36 
urging the valve to its closed position. This is the relative relationship 
so that, as one of pistons 62, 62', 62" within an interior chamber 58, 
58', 58" moves to allow expansion of the chamber to its maximum, spring 36 
biasing valve 28 to its closed position will not be capable of resisting 
the force tending to urge rocker arm 18 to its second position since the 
fluid within delay device 44 would then be working to overcome the bias of 
the second spring in addition to the first. Consequently, as movement of 
push rod 16 causes piston 46 disposed in exterior chamber 56 to force 
fluid into the inflow passageway 60 and into primarily one of the interior 
chambers 58, 58', 58" by a method to be described hereinafter, the force 
biasing piston 62, 62', 62" in that particular chamber to a position 
adjacent manifold member 52 will be overcome and piston 62, 62', 62" will 
move. As the interior chamber 58, 58', 58" expands to its maximum volume, 
further movement of that particular piston 62, 62', 62" will be precluded 
and fluid flow will tend to be diverted into another one of the outflow 
channels 64, 64', or 64". Since the fluid flow would then be directed to 
overcoming the bias of two of the interior chamber springs 74, 74', 74", 
the least resistance would be encountered at the spring 36 biasing the 
valve 28 to its closed position, and further movement of piston 46 in the 
exterior chamber 56 would be precluded. Pivoting motion would then be 
imparted to rocker arm 18, and the valve 28 would be opened. 
Manifold member 52 has a diversion passageway 76 operable to automatically 
direct fluid flowing from passageway 60 into one or more outflow channels 
64, 64', and 64" in response to the speed of movement of push rod 16. As 
shown in FIG. 6, diversion passageway 76 has an elongated arcuate inlet 
opening 78 in the end of manifold member 52 facing piston 46. The inlet 
opening 78 is offset from central passageway 60. Passageway 76 converges 
and extends radially inwardly to an outlet opening 80 in communication 
with a side of passageway 60. The longitudinal axis of passageway 76 
intersects the center of the opening or mouth of outflow channel 64". 
Passageway 76 obliquely intersects main inflow passageway 60. Fluid is 
forced from chamber 56 when movement is imparted to piston 46 by push rod 
16. With this structuring, fluid flow through both of passageways 60, 76 
will increase directly as the speed of longitudinal movement of push rod 
16 increases. 
The inflow passageway 60 is oriented along a directional axis 82. As the 
flow of fluid through the inflow passageway 60 is struck by the fluid flow 
through deflection passageway 76, deflection of the main fluid flow path 
will occur toward channels 64' and 64". 
Referring now to FIGS. 3, 4, and 5, when the speed of push rod 16 is slow, 
fluid flow rates through both inflow passageway 60 and diversion 
passageway 76 are also low, and the main flow will continue substantially 
undivided. Outflow channels 64 are oriented substantially along the 
directional axis 82 of inflow passageway 60. 
As the speed of the push rod 16 increases, the rates of flow through both 
passageways 60, 76 will also increase, and the force obliquely applied to 
the main fluid flow by the fluid flow through diversion passageway 76 will 
cause some angular diversion of the fluid flow. Outflow channel 64' 
channels the fluid flow to annular interior chamber 58', as shown by 
arrows in FIG. 4. 
When the speed of push rod 16 increases even further, so will the rates of 
fluid flow through inflow passageway 60 and diversion passageway 76. The 
diversion fluid flow will cause an even greater oblique force to be 
applied to the main fluid flow, and the greatest angular diversion of the 
main flow will occur. A third outflow channel 64" is provided to conduct 
the fluid flow to interior annular chamber 58", as shown by arrows in FIG. 
5. 
In FIG. 3, wherein the speed of the push rod 16 is lowest, fluid flow is 
channeled to the interior chamber 58 having the smallest of the maximum 
volumes to which any of chambers 58, 58', 58" can expand. As the speed of 
push rod 16 and rates of flow through the passageways 60, 76 increases, 
flow will be channeled to interior chamber 58' having a somewhat larger 
maximum expansible volume so that pivoting of rocker arm 18 will be 
delayed somewhat longer. When the speed of push rod 16 and the fluid flow 
rates through the passageways 60, 76 are greatest, fluid flow deflection 
will be greatest, and the flow will be channeled to interior chamber 58" 
having the greatest maximum expansible volume. Consequently, acutation of 
pivoting movement of rocker arm 18 will be delayed the longest in this 
instance. FIGS. 3, 4, and 5 illustrate the maximum movement of piston 46 
disposed in the exterior chamber 56, axially with respect to the cavity, 
in these three discussed instances. It is observed that, as the speed of 
push rod 16 and fluid flow rate through passageways 60, 76 increases, 
piston 46 will be allowed to move a greater axial distance into the 
exterior chamber 56. 
In order to increase the response rate once the desired delay has been 
accomplished, a relatively incompressible fluid can be used. The delay 
will be effected by the diversion of fluid flow into interior chambers 58, 
58', 58" having different maximum expansible volumes rather than by 
compression of the fluid. Another factor which bears on the selection of 
the fluid to be used is the ability to accomplish desired deflection of 
the main fluid flow by the diversion flow. 
The fluid contained within the cavity of body 45 by piston 46 can be a 
pressure sensitive fluid which has a viscosity that increases when 
subjected to pressure. In other words, the viscosity of the fluid 
increases in proportion to the compression force or pressure applied to 
the fluid. An example of this type of fluid is SONOTRAC liquid made by 
Monsanto Chemical Company, of St. Louis, Mo. The speed of rotation of cam 
10 determines the force applied to fluidic device 44 and the compression 
force on the fluid contained therein. As the speed of cam 10 increases, 
the force on the fluid increases and the viscosity of the fluid increases. 
Increased viscosity of the fluid causes reduced movement of fluid in 
channels 64, 64', and 64". Thus, the delay device 44 will remain at a 
substantially fixed length when subjected to high forces associated with 
high speeds. At slow cam speeds the fluid freely flows through the 
channels between the first and second chambers of the manifold member 
providing a time delay operation of the valve. At high cam speeds, the 
increased viscosity of the fluid retards the flow of fluid through the 
channels 64, 64', 64" in manifold 52. This reduces the time delay 
actuation of fluidic device 44. The pressure sensitive fluid senses the 
change of engine speed and operates to change operating characteristics or 
cam profile of the cam. At full acceleration, device 44 will simulate a 
racing cam profle. During steady speed conditions, the fluid will relax 
and revert to an economy cam profile. A maximum economy cam profile is 
attained during deceleration of the engine. 
As will be apparent to one of skill in the art, the arrangement 
hereinbefore described has other advantages. In addition to effectuating a 
desired delay in the opening of valves, it also causes the interior 
chambers 58, 58', 58" to be emptied of fluid as the push rod withdraws so 
that the proper delay can be again imposed during subsequent exhaust 
strokes of the cylinders' piston 42. 
Additionally, so structuring the fluidic delay device 44 will increase the 
valve lift rate so that an exhaust valve will open sharply, allow the 
combustion products to be exhausted, and close again sharply prior to 
allowing intake of more air/fuel mixture during the next stroke of the 
cylinder. This is so both because of the bias of the springs 74, 74', 74" 
within the interior chambers 58, 58', 58" and because of some measure of 
compressibility in the fluid. 
Numerous characteristics and advantages of the invention have been set 
forth in this detailed description. It will be understood, of course, that 
this disclosure is only illustrative. Changes may be made in many 
respects, particularly in matters of shape, size, and arrangement of parts 
without exceeding the scope of the invention. The invention's scope is 
defined in the language of the appended claims.