Geared rocker valve operation for internal combustion reciprocating piston engines which incorporate an overhead cam

An improved design for valve operation in internal combustion type engines which incorporate an overhead cam. This invention eliminates the valve spring. In current engines of this type an overhead cam lobe provides the force to the system to open an intake or exhaust valve and a compressed valve spring provides the stored energy to force the valve back closed. This invention uses two cam lobes on an overhead cam 15, an open cam lobe 16 and a close cam lobe 17; and two geared rockers, a open valve rocker 19 and a close valve rocker 20. A valve stem retainer assembly 12 is required to always engage the valve during operation. Positive force from the lobes of the overhead cam shaft is used to both open and close an intake or exhaust valve. The key is that only one of the cam shaft lobes drives the system at a time. If the close valve cam lobe 17 is providing the force to close the valve then the open valve cam lobe 16 is not engaged with the cam. Likewise, if the open valve cam lobe 16 is actively driving the roller on the open valve rocker 19, then the close valve cam lobe 17 is not engaged. Since the open and close valve rockers are geared and engaged into each other, the rocker that is not driving the system at any given time, is being driven by it.

BACKGROUND--FIELD OF INVENTION 
The field of this invention is in geared intake and exhaust valve operation 
in internal combustion reciprocating piston engines from an overhead cam. 
BACKGROUND--DESCRIPTION OF PRIOR ART 
U.S. Pat. No. 5,732,670 is related to the use of a pair of geared rockers, 
a pair of lifters, and two cam lobes per valve in order to positively 
actuate a single valve in an internal combustion reciprocating piston 
engine. The use of valve springs was eliminated. Additionally, the valve 
stem was attached to the end of one of the rocker arms by a retainer 
mechanism. 
This previous patent introduced above, only covered the use of the geared 
rocker combination as driven from a pair of lifters and pushrods riding on 
a centralized cam shaft located directly above the crankshaft. However, by 
modifying the rocker design, and using an overhead cam, the need for 
lifters and pushrods is eliminated. This results in a completely different 
engine design with fewer components thus increasing engine reliability and 
performance. Typical overhead cam engines use valve springs to close the 
valves, and a single cam lobe which engages a single rocker on one end. 
The other end of the rocker then presses against the top of the valve stem 
to open the valve. The stored energy held in the compressed valve spring 
must then force the valve to a closed position. 
As discussed in U.S. Pat. No. 5,732,670; the benefits of eliminating the 
use of valve springs in internal combustion engines are many. This is 
especially true when the engine is a high performance engine used for 
racing. The use of valve springs reduces the power output of the engine, 
due to the force required to compress the valve spring as the valve opens. 
Using a geared approach, there is no loss of horsepower due to spring 
compression. Also, when engines using valve springs turn at a high rate of 
speed, the valve springs will often experience lash causing the valves to 
float, because the spring is not strong enough to close the valve and keep 
the lifter flush against the camshaft as it travels down the backside of 
the cam shaft lobe. When a valve floats, it is left protruding into the 
combustion chamber during the upward stroke of the piston which may result 
in total destruction of the engine. In high performance engines, much 
stronger valve springs are used in an effort to combat this problem. 
However, stiffer valve springs greatly increase the rate of metal fatigue 
in the spring which causes rapid valve spring failure, which is one of the 
primary causes of engine failure (particularly in the high performance 
environment). 
Once the valve springs have been eliminated, a significant increase in 
engine reliability and performance may be achieved. At this point, 
incremental increases to reliability and performance may be obtained 
through design improvements and component reduction. With respect to U.S. 
Pat. No. 5,732,670 this invention eliminates several components by driving 
the geared rockers directly from an overhead cam (OHC), Whereas 
previously, the two geared rockers were driven from a cam located in the 
usual position directly over the crankshaft in the center of the engine. 
In this previous configuration, two lifters and two pushrods were required 
to transfer the energy from the lobes of the camshaft to the geared 
rockers. However, if the camshaft is located directly beside the pair of 
geared rockers inside of the cylinder head area, then a pair of lifters 
and a pair of pushrods are no longer required to transfer the energy to 
the geared rockers. 
To summarize, valve springs severely limit an engine's performance and 
life-span. Using a geared rocker pair driven from a central cam shaft is a 
vast improvement over the use of valve springs. It enables a standard 
engine to be retrofitted in order to eliminate the use of valve springs, 
and provides a means to eliminate components so that improved engine 
reliability may be achieved. 
OBJECTS AND ADVANTAGES 
This invention improves the operation of valves in an internal combustion 
reciprocating piston engine by eliminating the requirement for valve 
springs. Several objects and advantages of this invention are: 
a. To provide for positive valve actuation without the need for valve 
springs, with the following advantages: 
1. Increased reliability (fatigue induced valve spring failure will no 
longer occur thus reducing the likelihood of engine destruction). 
2. Increased performance due to the increased operational speeds that are 
obtainable without valve springs (valve lash and floating will no longer 
be a problem). Only the mechanical inertia and strength of the components 
will limit the maximum speeds attainable. 
3. Increased performance since both the opening and closing acceleration 
and timing of the valve may be accurately controlled. With positive valve 
opening and closing, the valve may remain open longer and close faster 
which results in increased horsepower. 
4. Increased convenience due to the decreased amount of maintenance that is 
required when valve springs are not used. Changing valve springs out after 
each race will no longer be required. 
b. To provide a more reliable and simple design. For example: 
1. Increased reliability due to fewer components. The need to incorporate 
two lifters and two pushrods is eliminated by driving the geared rocker 
pair directly off of an overhead cam. 
2. Increased strength of design since no lifters and pushrods are required. 
These two components are typically more fragile than the geared rockers. 
c. To provide a means for overhead cam engines to gain the benefits of 
operation without valve springs. 
This invention offers a means of positively actuating a valve from a geared 
rocker pair driven directly from an overhead cam shaft so that no valve 
springs are required. In engines which are designed for overhead cams, 
this invention provides a means to obtain a significant improvement in 
engine performance and reliability. As compared to engines which 
incorporate a single cam shaft directly above the crankshaft and use a 
geared rocker approach, this invention eliminates the need to have two 
lifters and two pushrods per valve. Additionally, this invention should 
reduce the cost of maintaining engines since fragile valve springs will no 
longer be used.

DESCRIPTION--FIGS. 1 THROUGH 5B 
FIG. 1 shows a cross section of an internal combustion reciprocating piston 
type engine with overhead cams which incorporates this invention. Although 
only the intake port valves and related operational components are shown 
in this view, the exhaust ports are similar and their operational 
components are identical mirror images of the intake port components. Many 
basic components of an overhead cam engine are shown in this figure such 
as: an oil pan 1, a cylinder 5, a crankshaft 2, a connecting rod 3, a 
piston 6, and an exhaust pipe 7. In this view, the approximate location of 
the fuel injectors 13 and the velocity stacks 14 are also shown. However, 
the engine could just as well be carbureted, in which case a carburetor 
would replace both the fuel injectors and stacks. Since this is a overhead 
cam engine, the usual location of the cam shaft 4, is not used but rather 
a overhead cam 15 is used for both the right and left side of the engine. 
Since this view illustrates the components required to operate the intake 
port, only the intake port 8 is shown. However, the exhaust port could 
have just as easily been shown instead since operation of the two is 
identical. A valve stem 10 and the valve head 9 are also shown. The top of 
the valve stem 11 is held onto at all times by the valve stem retainer 
assembly 12. The overhead cam 15 has both a open valve cam lobe 16, and a 
close valve cam lobe 17. The open valve cam lobe is responsible for 
actuating the open valve rocker 19 just as the close valve cam lobe 17 is 
responsible for actuating the close valve rocker 20. 
FIG. 2 is a prior art depiction of how a overhead cam is typically driven 
from the crankshaft of an engine. Once again, several items are shown for 
reference purpose only such as: the oil pan 1, the exhaust pipes 7, the 
rocker covers 18, the fuel injectors 14, and the stacks 13. The crankshaft 
2 contains a drive gear 21 which engages a idler gear 22, which in turn 
engages a toothed belt drive 24. The toothed belt drive 24 engages the cam 
shaft drive belt 26. An idler 23, and a guide pulley 25, also press 
against the belt. The belt engages the two overhead cam shafts 27 which 
are responsible for driving the valves on both the left and right sides of 
the engine. 
FIGS. 3A and 3B illustrate the primary embodiment of this invention. FIG. 
3A shows the position of the valve operating components when the valve is 
forced closed. FIG. 3B shows the position of these same components when 
the valve is being forced open. The top of the valve stem 11 is grooved 
and is forcibly held in place at all times by a valve stem retainer 
assembly 12. This assembly contains a keeper 41 which snugly fits into the 
groves found at the top of the valve stem. The keeper 41 is locked into 
place by a nut 43 and a washer 42 which threads onto the keeper. A 
hardened retainer top plate 39, in conjunction with a hardened valve stem 
cap 40, keep the open valve rocker retainer roller 38 firmly confined at 
all times during the operation of the valve. The roller may move back and 
forth along the flat hardened surfaces, but very tight tolerances are kept 
vertically between the hardened surfaces so that the roller does not have 
significant play up and down. This is important since this tolerance 
directly effects how well the valve closes. Although hardened steel is 
recommended, any hardened material may be used so that the open valve 
rocker retainer roller 38 does not wear into the surfaces of the valve 
stem 11 or the hardened retainer top plate 39. The open valve rocker 19 
has an open valve retainer arm 37 which holds the open valve rocker 
retainer roller at it's end. The open valve rocker pivots around the open 
valve rocker shaft 29. The open valve rocker contains a open valve rocker 
cam roller 35 which is located at the end of the open valve rocker cam arm 
33. While the valve is opening, this open valve rocker cam roller 35 rides 
smoothly along the surface of the open valve cam lobe 16. While the valve 
is closed, there may a few thousandth's of an inch gap between the two. 
Likewise, the close valve rocker 20 contains a close valve rocker cam 
roller 36 which is located at the end of the close valve rocker cam arm 
34. While the valve is closing or is closed, this close valve rocker cam 
roller 36 rides smoothly along the surface of the close valve cam lobe 17. 
However, while the valve is open, there may be a few thousands of a gap 
between the two. The close valve rocker rotates about the close valve 
rocker shaft 30. At all times, the open valve rocker gear teeth 31 and the 
close valve rocker gear teeth 32 are positively engaged. This forces a 
strict interdependency between both the open valve rocker 19 and the close 
valve rocker 20. Therefore, only one of the rockers may drive the 
combination at a time. A stand 28 is located between each cylinder of the 
engine in order to support all of the rocker components and optionally, 
the overhead cam itself. 
FIG. 4 shows a top view of the assembly required to operate both the intake 
and exhaust port valves for a singe cylinder minus the overhead cam shaft. 
Since the rocker pair required for the exhaust port are an identical 
mirror image of the rocker pair required to operate the intake port, only 
the intake port pair have been shown in the previous side views. 
Alternatively, the exact same rocker pair could be used to open the 
exhaust port as is used to open the intake port. In this case, the lower 
half of FIG. 4 would look identical to the upper half of FIG. 4 rather 
than appearing as a mirror image. Either way would work just as well as 
the other. In FIG. 4 both the open valve rocker shaft 29 and the close 
valve rocker shaft 30 for a single cylinder assembly are shown as 
supported by a pair of stands 28. Each stand is held in place against the 
engine block by a pair of stand screws 44. The position of both the open 
valve rocker cam roller 35 and the open valve rocker retainer roller 38 
are shown in the open valve rocker 19. Likewise, the position of the close 
valve rocker cam roller 36 is shown in the close valve rocker 20. At the 
end of the open valve rocker 19, is the top view of the valve stem 
retainer assembly 12, and a top view of the hardened valve stem cap 40 
which is inserted into the top of the valve stem 11. 
FIGS. 5A and 5B show the individual valve rockers in greater detail. In 
FIG. 5A a open valve rocker 19 is shown. This rocker has a open valve 
rocker retainer roller 38 located at the end of a open valve rocker 
retainer arm 37. This roller is what engages the valve stem retainer 
assembly 12 (shown in previous drawings), in order to transfer the opening 
and closing motion to the valve with as little friction as possible. The 
open valve rocker 19 also contains a open valve rocker cam roller 35 
located at the end of a open valve rocker cam arm 33. This roller is made 
to ride along the surface of the open valve cam lobe 16 (shown in previous 
figures) with as little friction as possible. The entire open valve rocker 
rotates about the open valve rocker shaft 29. Additionally, this rocker 
contains several open valve rocker gear teeth 31. In FIG. 5B a close-up of 
the close valve rocker 20 is shown. This rocker contains a close valve 
rocker cam roller 36 located at the end of a close valve rocker cam arm 
34. This roller is made to ride along the close valve cam lobe 17 (shown 
in previous figures) with as little friction as possible. The close valve 
rocker gear teeth 32 are designed to fit perfectly into the open valve 
rocker gear teeth 31 of FIG. 5A. Although these rockers are typically made 
of hardened steel, any high strength material such as ceramics, titanium, 
or alloys would work perfectly well. 
From the description above, a number of advantages of this invention become 
evident. 
A. Most engines which incorporate the use of an overhead cam could be 
modified to greatly benefit from this invention. Also, overhead cam 
engines built from the ground up could easily be designed to use this 
invention with very little changes to the existing production line. 
Therefore, many people could benefit from this invention in the present 
and in the future. 
B. The new valve operating assembly does not require valve springs and 
should increase performance and reliability. Typically, a design with 
fewer components is more reliable. This invention eliminates the need for 
both lifters and pushrods. 
C. Engine speed and performance will not be limited by the operating 
characteristics of the valve spring. Now only the inertial mass and 
strength of the components will limit the performance attainable. 
D. Race engines incorporating this invention will have enhanced 
performance. Positive valve opening and closing will enable the valve to 
remain open longer and close faster, generating more horse power and 
supporting higher RPM ranges. 
F. Engines incorporating this invention will require less maintenance than 
those that use valve springs. This is especially true for high performance 
race engines. 
OPERATION--FIGS. 1 TO 5 
The operation of this geared rocker internal combustion engine is such that 
a valve spring is no longer required and therefore the engine performance 
is greatly enhanced. Since this invention is operated from an overhead cam 
rather than a centralized cam shaft located directly above a crankshaft, 
the need for lifters and pushrods has also been eliminated. 
First, a quick discussion of how overhead cam engines are typically driven 
off of the crankshaft. As seen in FIG. 2 which is prior art, the 
crankshaft 2 has a drive gear 21 which engages a idler gear 22. The idler 
gear 22 in turn engages a toothed belt drive 24. The toothed belt drive 24 
drives the cam shaft drive belt 26. Therefore, the speed of the cam shaft 
drive belt is directly dependent on the revolution speed of the crankshaft 
2. The location of an idler 23 is adjustable so that the tension in the 
cam shaft drive belt 26, may be correctly set. A guide pulley 25 also 
makes contact with the cam shaft drive belt 26, and does not forcibly 
engage it. Its purpose is to control the travel path of the cam shaft 
drive belt so that it will reach both overhead cam shafts 27 without 
interference with other engine components. The overhead cam shafts 27 are 
geared so that their speed is precisely controlled by the cam shaft drive 
belt 26, and thus ultimately by the speed of the crankshaft 2. By 
maintaining a precise speed relationship between the crankshaft 2 and the 
overhead camshafts 27, it is ensured that the intake and exhaust valves 
will open and close at precisely the correct time in relation to the 
pistons travel in the cylinder. As seen in FIG. 1, the position of the 
piston 6 within the cylinder 5, is controlled by the crankshaft 2. This is 
due to the fact that the piston 6 is connected to an arm of the crankshaft 
2 by a connecting rod 3. 
In overhead cam engines using valve springs, a single cam lobe pushes the 
valve open (generally by means of a single rocker) and simultaneously 
compresses a valve spring in the process. The energy stored in the 
compressed valve spring must be sufficient to close the valve from its 
open position and press the single rocker back flush against the cam lobe. 
Since a valve spring can only store a limited amount of energy which is 
required to close the valve, the operational speed of an engine is 
significantly limited. If a valve spring can't close a valve fast enough, 
the valve may be left inside the cylinder and may be destroyed by an 
upward stroke of the piston. High performance engines typically use much 
stiffer valve springs in an effort to combat this problem. However, since 
these are brittle, they fatigue and fail quickly. This invention 
eliminates valve springs, providing a way to drive the valve open and 
closed directly off of the overhead cam shaft. 
Basic embodiment of operation: Although FIG. 1 shows the paired rocker 
assembly positioned relative to an engine cross-section. FIGS. 3A and 3B 
will be used to describe in detail the operation of this invention. This 
is preferable since FIGS. 3A and 3B are really just a close-up taken 
directly out of the overhead cam areas of FIG. 1. 
FIG. 3A shows the geared rocker pair being driven from the overhead cam 
shaft 15 to close a valve, and FIG. 3B shows the geared rocker pair being 
driven to open the valve. It is important to note that the valve may be 
either an intake port valve or an exhaust port valve since the geared 
operation to open and close either one is identical. Also, one must keep 
in mind that the camshaft is rotating in a counter clockwise (CCW) 
direction. Additionally, the open valve rocker 19 pivots around the open 
valve rocker shaft 29 just as the close valve rocker 20 pivots around the 
close valve rocker shaft 30. Beginning with FIG. 3A, the valve is actively 
being driven into a closed position. The closed valve cam lobe 17 is 
forcibly pressing against the close valve rocker cam roller 36. In the 
still frame view of FIG. 3A the close valve rocker cam arm 34 (and thus 
the entire close valve rocker 20) has been forced into its lowest position 
possible. In other words, the close valve rocker 19 cannot be driven any 
further in a CW rotation. Remember that the entire close valve rocker 20 
pivots around the close valve rocker shaft 30. Since the close valve 
rocker gear teeth 32 have forcibly engaged the open valve rocker gear 
teeth 31, the open valve rocker has been forced to rotate CCW to its 
furthest most upward position. The force exerted on the open valve rocker 
gear teeth at this point, is the only force which controls the rotational 
position of the of the open valve rocker 19. Now the open valve rocker cam 
roller 35 is just short of coming in contact with the backside of the open 
valve cam lobe 16 by a few thousandths of an inch. Therefore, the entire 
geared rocker assembly, including valve stem 11, is being positioned and 
driven by the close valve rocker cam roller 36 riding along the close 
valve cam lobe 17. Since the open valve rocker 19 is being forced into its 
upper most position by its gear engagement into the close valve rocker 20, 
the open valve rocker retainer arm 37 and open valve rocker retainer 
roller 38 are also in their uppermost CCW position. Therefore, the valve 
stem retainer assembly 12 and the top of the valve stem 11 are also in 
their uppermost position. By pulling the top of the valve stem upward as 
far as possible, the valve head 9 (as seen in FIG. 1) is pulled up flush 
against the port in the cylinder 5 (also seen in FIG. 1) thus completely 
closing the port. 
This valve close position described above is maintained as long as the 
close valve rocker cam roller 36 continues to roll along the wide portion 
of the close valve cam lobe 17. However, as the close valve rocker cam 
roller 36 begins to roll down the decline portion of the close valve cam 
lobe 17, the entire close valve rocker 20 begins to rotate CCW. Due to the 
geared nature of the two rockers, the open valve rocker 19 is then forced 
to begin rotating CW about its open valve rocker shaft 29 thus causing the 
open valve rocker retainer arm 37 and roller 38 to travel downwards. Since 
the valve stem retainer assembly 12 holding the top of the valve stem 11 
engages the open valve rocker retainer roller 38, it also begins to move 
downward thus opening the valve into the port. 
A key point of interest in the operation of the geared rocker pair is when 
the valve just starts to move into the cylinder. At this point the close 
valve rocker cam roller 36 is just starting down the decline in the close 
valve cam lobe 17, and the open valve rocker cam roller 35 is just 
starting up the incline of the open valve cam lobe 16. At this point, the 
open valve rocker 19 takes over control of the rocker assembly from the 
close valve rocker 20. This is because the close valve rocker cam roller 
36 begins to float away from the close valve cam lobe 17 (by only a few 
thousandths of an inch) and at the same time the open valve rocker cam 
roller 35 begins to experience forced contact with the open valve cam lobe 
16. By paying careful attention to the design of the open and close cam 
lobe profiles, this transition as to which cam lobe is controlling the 
system is a smooth one. 
As the overhead cam continues to turn in the CCW direction, the valve fully 
open position of FIG. 3B is reached. At this point the open valve rocker 
cam roller 35 is at the peak of the open valve cam lobe 16. This forces 
the open valve rocker 19 as far in the CW direction as possible. This is 
because the contact point of the open valve rocker 19 with the open valve 
cam lobe 16 is to the right of the open valve rocker shaft 29 about which 
the open valve rocker 19 rotates. At the farthest most CW rotation of the 
open valve rocker 19, the open valve rocker retainer arm 37 and roller 38 
are in the lowest position possible. Since the valve stem retainer 
assembly 12, and thus the top of the valve stem 11, are positioned by the 
open valve rocker retainer roller 38, the valve head 9 (shown in FIG. 1) 
is pushed open as far it can go into the cylinder 5 (also shown in FIG. 
1). At this point, the position of the close valve rocker 20 is solely 
determined by it's gear teeth 32 engaging the gear teeth of the open valve 
rocker 31. Since the open valve rocker 19 is rotated as far in the CW 
direction as possible, the close valve rocker 20 has been forcibly rotated 
as far in the CCW direction as possible. Due to careful design, the close 
valve rocker cam arm 34 and roller 36, although rotated upward as far as 
possible, still clear from hitting the backside of the close valve cam 
lobe 17 by a few thousandths of an inch. 
Once again, another key point in the operation of the geared rocker pair is 
reached when the open valve rocker cam roller 35 just begins to start 
traveling down the backside of the open valve cam lobe 16. At this instant 
the close valve rocker cam roller 36 is just starting up the incline of 
the close valve cam lobe 17. At this point the transfer of control is 
switched back to the close valve rocker 19 from the open valve rocker 20. 
The open valve rocker cam roller 35 begins to float away from the open 
valve cam lobe 16 (by a few thousandths of an inch), while the close valve 
rocker cam roller 36 begins to be forced upon by the close valve cam lobe 
17. 
As the overhead cam shaft continues to turn in a CCW direction, the fully 
closed position of FIG. 3A is again reached. From here, the entire cycle 
as described above starts all over again. Each time a complete revolution 
of the overhead cam shaft occurs, the valve is opened and closed. Since 
only one geared rocker may control the pair of geared rockers at a time 
(and thus the valve), careful design attention must be paid to ensure that 
both valve rocker cam rollers 35 and 36, are not driven by their 
respective cam lobes 16 or 17 at the same time or an interference will 
result. When one of the valve rockers is being driven by its associated 
cam lobe, the other geared rocker must not be. In fact, the other geared 
rocker that is not being driven from the cam shaft is being controlled by 
the one that is via the gear teeth found between the two rockers. 
At this point a quick discussion of the valve stem retainer assembly 12 is 
in order. The sole purpose of this assembly is to engage and exactly 
follow the up and down movement of the open valve rocker retainer roller 
38. Very tight tolerances between the hardened retainer top plate 39 and 
the hardened valve stem cap 40 are required so that there is almost no 
play in the up and down movement of the open valve rocker retainer roller 
between the two plates. Approximately one thousandths of an inch or less 
would be best. The hardened valve stem cap 40 is desirable to prevent the 
open valve rocker retainer roller 38 from damaging and wearing at the top 
of the valve stem 11. This way, the tight tolerances discussed above may 
be better maintained. The top of the valve stem 11 requires some type of 
notching or alteration so that the keeper 41 may positively retain it 
during the up and down stroke of the valve. An example of two small groves 
in the top of the valve stem 11 are shown FIGS. 3A and 3B to suit this 
purpose. A washer 42 and a nut 43 are used to tighten the keeper 41 firmly 
against the top of the valve stem 11. 
The operational description of a valve system as discussed above applies in 
an identical fashion whether it is an intake port valve or an exhaust port 
valve. Although the components for the two ports may be a mirror image of 
each other as shown in the top view of FIG. 4. they need not be. The 
identical components (without mirroring them) could be used to operate 
both the intake and exhaust ports. In the interest of conciseness and 
length, replicating the entire operating description above twice; once 
referring to the intake port valve and once again referring to the exhaust 
port valve has been avoided. This patent is intended to cover both the 
intake and exhaust valve operation. This patent is also intended to cover 
multiple intake and exhaust valves per cylinder. 
SUMMARY, RAMIFICATIONS, AND SCOPE 
As seen by the description and operational discussion presented above, this 
invention offers many advantages and benefits by replacing the valve 
spring in internal combustion engines incorporating an overhead cam, and 
replacing it with a positive operating mechanism which derives it's force 
directly from the overhead cam shaft at all times. Without the negative 
liabilities of a valve spring, engines based on this invention will be 
able to turn at higher speeds and run for longer periods of time before 
requiring servicing. This invention has the following additional 
advantages. 
It permits overhead cam internal combustion engines to be upgraded with the 
new components of this invention using the existing engine block, 
crankshaft, pistons, and manifolds. This invention is not limited to new 
production engines, but to all internal combustion engines with an 
overhead cam. 
It provides enhanced reliability for internal combustion engines. Valve 
springs are a leading cause of catastrophic engine failure. High 
performance engines will no longer require constant valve spring 
replacements. 
It reduces the cost of maintenance of internal combustion engines which are 
used for competition. 
It enables internal combustion engines to operate at higher sustainable 
speeds or RPM's. By using positive force derived from overhead cam shaft 
lobes to open and close the valve, valve floating will no longer occur. 
It increases the efficiency of internal combustion engines by replacing the 
valve springs with a valve closing mechanism which derives it's force 
directly from the cam shaft. While opening the valve, the cam shaft will 
no longer be required to overcome the constant resistance presented by the 
valve spring. 
The use of an overhead cam eliminates a pair of lifters and pushrods per 
valve. Fewer components typically results in increased reliability and 
lower manufacturing costs. 
Although the description above contains many specifications, these should 
not be construed as limiting the scope of the invention but as merely 
providing illustrations of some of the presently preferred embodiments of 
this invention. For example, instead of the close valve rocker shown in 
FIG. 5B having an extended width gear design in order to engage the gear 
teeth of the open valve rocker shown in FIG. 5A, it could easily be the 
other way around. The open valve rocker of FIG. 5A could have the extended 
gear teeth design, and the close valve rocker of FIG. 5B could have the 
narrow gear teeth equal to the width of the rest of the rocker. Also, a 
number of variations to the valve stem retainer assembly 12 could easily 
be used instead of the version shown here. For example, a pin could go 
through the top of the valve stem and into some type of keeper that is 
around the top of the valve stem. Perhaps a roller at the end of the open 
valve rocker 19 is not required at all, since simply using a flexible pin 
between the top of the valve stem and the end of the open valve rocker arm 
would work in some cases. The point is that there are many methods that 
could be used to retain the top of the valve stem to the end of the open 
valve rocker arm, and this patent should not be limited to any particular 
one. Also, the position of the open valve rocker relative to the close 
valve rocker is very flexible. With some minor redesign, the open valve 
rocker could just as easily be located to the left of the close valve 
rocker arm. Additionally, both valve rockers could be located differently 
with respect to the overhead cam. For example, they could be to the left 
or right of it. Such movement would require very little redesign, since 
the operational principles would remain the same as the particular 
implementation shown in the drawing figures. 
Additionally, the overhead cam may indirectly actuate the pair of geared 
rockers. In this similar embodiment some means of transferring energy from 
the overhead cam to the individual geared rockers would exist such as: 
pins, shafts, levers, or connecting rods. Another variation which could 
easily be implemented would be to have the cam shaft move in a CW 
direction rather than a CCW direction. In this case, the operation as 
described above would be identical. 
All of the components of this invention do not have to be made of hardened 
tool steel as the original evaluation model was. Any material which proves 
to be durable and wear resistant enough to provide adequate performance 
would do. For example, titanium, and some ceramics may work perfectly 
well. Also, combinations of materials would suffice such as using hardened 
steel only at locations of contact and mild steel or aluminum for the 
majority of the components volume. 
While a preferred embodiment of the invention has been presented and 
described, it will be appreciated that there is no intent to limit the 
invention by such disclosure. Rather, the disclosure is intended to cover 
all modifications and alternate embodiments falling within the spirit and 
the scope of the invention as defined in the appended claims.