CA2227124A1 - Attain's 2 new valve trains, or "a-2nvt" - Google Patents

Abstract

A camshaft-lobe of an SOHC/DOHC engine acts upon an Attain valve train component (Prior Art) through a valve-lash adjuster to open an Attain 1/2 Stem Valve (Prior Art), which is also closed by a second cam-lobe on the same camshaft, through a valve-lash adjuster and a closing fork (Prior Art), pulling the said valve shut by means of a pull-up collar on the said valve.

Description

1 ~i ATTAIN TECHNOLOGY INC.
"A - 2NVT"
Or Designed And Pre ared By NICHOLAS M. OTTLYIC
March 26, 1998 7 Aylesbury Road, Islington, Ontario M9A 2M3 Telephone: (416) 239-6242 intro - i INTRODUCTION
The submitted two - (2) valve trains by Attain deal predominantly with valve springs - or rather - with their absence in the valve trains, or their completely different applications.
As the said valve trains are not exactly common-place, some explanations are in order; as these comments do not really belong into claims sections, they are presented here, as an introductory material.
DESMODROMIC VALVE TRAINS
History Created in a Pre-World-War II era, desmodromic valve trains were applied to high-performance engines in racing cars and motocycles. From that era, of note are the French auto-maker Delage, that raced in Le Mans, British and Italian motocycles by Norton, designs by Tonti and then later, in the 1950's, in the Mercedes-Benz racing cars, also entered at Le Mans. Today, unfortunately, there is only one commercially available engine with desmodromic valves: it is the famous Italian make of Ducati.

intro - ii What Is A Desmodromic Valve Train ?
Briefly stated, it is a high-performance valve train that operates without main springs to close the valves shut; but even a Ducati uses a small helper-spring for its low-speed operation; the Mercedes-Benz had no springs at all. - As to the origin of the word "desmodromic", not even the automotive historians can agree on its true meaning, nor can they tell us how it originated.
Why Do Desmodromic Valve Trains Command Such High Res ect ?
With no resistance of the main spring, the desmodromic valve train doesn't meet too much mechanical resistance and can operate with less friction, and it is quieter. However, its main attribute lies in the fact that it allows a longer "open time"
for its valves, so that on the intake side, more air can be let into the cylinder during an intake down-stroke - which simply enhances the volumetric efficiency (Ve) of the engine. Similar benefits are available to the exhaust valve. It is its "radical timing" that causes the engine experts and analysts to state, that one desmodromic valve is equivalent to two "regular valves".
Hence, it is a performance booster - but it comes at a higher cost.
A 'desmo' valve train needs - if not a separate camshaft, then at least - an extra cam-lobe and a separate closing mechanisms to close the valve shut.
The only available desmo-type valve train today (Ducati) is built with extreme precision and quality approaching intro - iii desmo - cont'd a spring-wound Swiss watch, which makes its quite expensive.
Furthermore, Ducati engines can only be adjusted mechanically by shims, calling for high skills or the services of a competent technician. The service intervals are at the 12 to 15,000 km.
While this procedure is acceptable to a dedicated enthusiast, it does not fit the image of modern maintenance-free auto engines guaranteed to run without a tune-up for 160,000 kms.
To conclude, desmodromic valve trains are not new but Attains fully automatic valve-lash adjusters are a novelty and so are the previously claimed Attain valve Train Components and Engine Ports that will further enhance the performance of this very efficient valve train.
DSA
or DYNAMIC SPRING ASSEMBLY
The Dynamic Spring Assembly, or DSA, is an Attain designed derivative of a desmodromic valve train; its name stems from is operation. The valve opens by a mechanism similar to a desmo engine but while the cam-lobe opens the valve, a second cam-lobe releasesthe pressure of a smaller spring that is used to seal the valve. Hence, the opening of the valve is done as freely as in a desmo valve train. When the said valve is being closed, spring pressure is gradually applied to the valve till it is sealed.
The use of this "dynamic spring" eliminates the use of a second valve-lash adjuster used in desmo valve trains.

intro - iv dsa - cont'd But since the Dynamic Spring Assembly shares with Desmodromic Valve Trains virtually all 'Prior Art' components and engine ports, its performance should be almost the same as the latter one - but at reduced cost. - The DSA does not require any periodic valve-train adjustments neither, i.e. it is maintenance-free.
* *
PRESENTATION FORMAT
Section I of this Submission deals with Attains 2 New Valve Trains and their two claims.
Because both New Valve Trains employ many 'Prior Art' features, these have been assembled and duly listed in an Appendix.

SECTION I

DESMODROMIC VALVE TRAINS
BY ATTAIN
T~~fr»~
A camshaft-lobe of an SOHC/DOHC engine acts upon an Attain valve train component (Prior Art) through a valve-lash adjuster to open an Attain ~ Stem Valve (Prior Art), which is also closed by a second cam-lobe on the same camshaft, through a valve-lash adjuster and a closing fork (Prior Art), pulling the said valve shut by means of a pull-up collar on the said valve.
Attains Desmodromic Valve Trains Recognizing the very high performance potential of the desmodromic valve trains - but also its lack of functionality in every-day's automobile, Attain Technology has designed several models of this type of mechanism; they all have one feature in common: their valve train tolerances are adjusted automatically, so that the engines using them, do not require any adjustmenents for the duration of their normal ilfe.
These new design features immediately transform the desmodromic valve trains into:
a) a practical, every-day engine, and b) dramatically reduce its component costs.

- 2 -desmo - valve trains - cont'd Also, by adopting certain Attain components and engine ports, the proposed valve trains by Attain not only retain their previous performance potential, but they are increased by:
1) a reduced reciprocating weight, since many of Attains valve trains components are lighter, allowing the engine to achieve even higher RPM's than previously possible, and -2) Attains Parallel Flow Ports add further to the already very high volumetric efficiency of the said engine.
The two camshaft lobes employed in a desmodromic valve train are used in such a way, that the first camshaft-lobe opens the valve, either by means of an intermediate component -like a rocker-arm - while the closing of the valve is performed by a second cam-lobe; however, since the closing of the valve entails the lifting of the said valve, the closing mechanism -most likely a rocker again - must be applied to the underneath portion of the camshaft.
In the Attain-Desmo Valve Trains both the opening and the closing mechanisms are provided with automatic valve-lash adjusters that eliminate the periodic adjustment service demanded by a "regular" (read: Ducati) desmo valve train.
As stated above, the Attain Desmodromic Valve Trains can operate only in SOHC and DOHC engines, which excludes any OHV engines.

- 3 -desmo valve trains - cont'd Main Advantages Of An Attain Desmo Valve Train a) an Attain Desmo Valve Train is completely maintence-free b) the production cost of the said valve train should be considerably below its present expenditures. as its tolerances are far more 'liberal', eliminating a lot of precision parts c) the said valve train uses many components that are substantially lighter, allowing it to reach ~ even higher RPM
(revolutions per minute), thus achieving even higher terminal horsepower d) using Attains Parallel Flow Ports, the volumetric efficiency of the said valve-train - already of very high order -should be enhanced even further e) the Attain Desmo valve train has a great deal of design flexibility, since its valve-closing and valve-opening mechanisms can operate either from a single, or two fulcrums.

- 4 -Figures For Attains Desmo Valve Trains Figure 1, is an enlarged schematic - in cross-section of an Attains Desmodromic Valve Train.
The valve shown is opened by an Opening Rocker OR, which terminates with a Sliding Roller Adjuster at the camshaft end. (SRA - Prior Art). The said valve is closed by a Closing Rocker - CR, which pivots in a rotating adjuster, actuated by a hydraulic adjuster. Thus, both the opening and closing mechanisms are fully compensated for tolerances and do not require any periodic adjustments. While the Closing Rocker is 'straight' - the Opening.- Rocker is off-set - and so are the cam-lobes, sharing the same camshaft.
The valve mechanism shown is installed in an Attain Parallel-Flow Port Type IB (Prior Art).
Figure 2, is an enlarged top view of the desmodromic valve mechanism shown in Figure 1.
Both the Opening ~ Closing Rockers are encased in Carrier - CA, which is supported by two End Bearings - EB. -The Adjustment Lever- AL, rotates the inside of adjuster assembly, in which the pivot of the Closing Rocker -CR, is mounted eccentrically, so that the motion of the said lever causes the fulcrum of the said rocker to operated from a different geometrical center - effecting a tolerance adjustment.
Figure 3, shows the above valve train installed in a high-performance, D/CIH (Prio:r Art) cylinder head, with an Attain Parallel-Flow Port Type IB (Prior Art).

- 5 _ desmo figures - cont'd Figure 4, is a cross-section of desmodromic valve train using an RLB (Roller Lift-Bucket) as a valve-opening mechanism, which eliminates a rocker altogether. While the RLB
(Prior Art) has its own valve-lash adjuster, the closing fork has its own adjustment mechanism, which is mounted eccentrically on a rotating component.
Figure 5, is a cross-section of a desmodromic valve-train which employs a Y-Rocker as an opening mechanism; the valve-lash adjustment in the said Y-Rocker is in its valve-tappet portion and the closing fork is adjusted by an eccentric, rotating element, as in Figure 4, above.
Figure 6, shows an alternate valve-lash adjustment mechanism, named "Rising Shoe", in which a hydraulic lifter is incorporated in the arm of the closing rocker.
Figure 7, - depicts a "Rising Shoe" valve lash adjuster installed desmodromic valve train emplyoing an RLB
valve mechanism. As can be seen, the closing fork rotated on a solid, horizontal shaft, but its contact point with the closing cam is regulated by the said adjuster.
Figure 8 a, show a cross-section of a desmodromic valve train applied to T-Bar Mechanism (Prior Art). operating in an Attain Type V (Prior Art) intake engine port; only 3 cam-lobes are needed to operate 2 valves; the closing forks are mounted on an eccentric rotating element.

- 6 -desmo figures - cont'd Figure 8 B, is an overhead view of the engine shown in Figure 8 A. It shows the location of the camshaft and its opening rocker, which is mounted on a common, rotating element with the closing rockers; the arms of the latter are not shown, as they are placed below the rocker shaft and neither are the elements of the T-Bar Mechanism.

-DYNAMIC SPRING ASSEMBLY
or DSA
Abstract A camshaft-lobe of an SOHC/DOHC engine acts upon an Attain Valve Train component (Prior Art), provided with a valve-lash adjuster to open an Attain ~ Stem Valve (P-A) which also closed by a second cam-lobe on the same camshaft through a mechanism that is connected by a small spring to a closing fork, lifting the valve shut by means of a pull-up collar on the said valve.
DSA
The DSA, or the Dynamic Spring Assembly is a derivative of Attains Desmodromic Valve Train and makes use of all Attains Valve Train Components and Parallel Flow Ports.
employed in the latter mechanism. Again, it can be used in conjunction with SOHC and DOHC engines only.
Just like in the Desmo Valve Train the DSA Mechanisms employ.two.cam-lobes: one opens the valve, the second one closes it. The name "dynamic" was chosen to indicate, that in one valve event the force of the closing spring is cancelled when it is not needed - and then re-applied to seal the valve into its seat.
The valve-closing mechanism is not connected rigidly to the valve-closing spring, so that when the closing cam-dsa valve train - cont'd lobe begins to move - it turns the mechanism freely but in its last degrees it has to work against the force of the closing spring to seal the valve off.
This arrangement also means that in the DSA mechanism the second valve-lash adjuster is not required.
The operation of the DSA Valve Train is as follows:
1. the valve is opened by an Attain valve component - and simultaneously, the spring pressure keeping the valve closed is released 2. the valve is kept open as long as it is needed 3. closing of the valve starts when the closing cam begins to push on the closing rocker 4. the valve is completely closed when the cam-lobe pushes further against the 2- part rocker and thus seals the valve 5. hence, in one complete valve-event, the spring pressure is released when it is not needed - and applied - only when it is really required to seal t:he valve 6. only the valve-opening portion of the DSA valve train needs a valve-lash adjuster; the closing portion's tolerance are taken upby the spring's action.
Attains Dynamic Spring Assembly - just like the Desmo Valve Train - can operate only in SOHC and DOHC (Single, or Dual, Overhead Camshaft) engines.

_ g _ dsa valve trains - cont'd Main Advantages Of The DSA Valve Train a) uses only a very short spring - which is applied only when it is needed b) the short spring is much cheaper than a second valve -lash adjuster in the Desmo Valve Train c) takes advantage of all Attain valve train components and new engine ports available to a Desmo Valve Train d) an engine that uses a DSA Valve Train will probably achieve an 85~ to 90~ performance plateau of a Desmo Valve Train.
e) flexibility of application: the DSA Valve Trains can use a variety of springs - and can be applied in both single, and dual fulcrum configurations, giving the designer a wide selection of mechanisms to choose from.

Figures For DSA Valve Trains Figure 10 and Figure 11, portray in a schematic fashion the 'Four Valve-Timing Events' that a valve in a Dynamic Valve Train Assembly goes through; it shows a intake valve being actuated by two rockers, placed in two different fulcrums, being driven by one common camshaft with two cam-lobes.
Figure 10:
1. Valve Is about To be Opened - the Closing Lobe (CL) releases the spring pressure applied against the closing fork, coupled to the Closing Rocker (CR) by a Twist Coil Spring; the said valve is now 'free' to be opened without any spring resistance.
2. Valve is now fully opened - the Opening Rocker (OR) pushes the valve open without any resistance of the spring force -- which was "dialed-out."
Figure 11:
3. The Valve is in its seat - the Closing Rocker (CR) doesn't meet any springs resistance - as yet.
4. The Closing Rocker (CR) is being supplied with an ever-increasing spring pressure) as the Closing Lobe (CL) rises, being and the Twist Coil Spring and transmits its force against the closing fork of the Closing Rocker Aseembly.

dsa figures - cont'd Figure 12, is a.n analysis of spring pressure application to a DSA valve; as seen in the graph, the pressure that seals the valve in its seat is "dialed out" during its entire 'open time' - and brought in again only when it is really needed: to close it firmly shut, at the end of its time event.
Figure 13, shows two - of the several possible -- spring applications to the closing arm. The upper image is a top view of a concentric, short-torsion spring installation, where the said spring is coupled to both ends of the device by splines: in order to close the valve, the roller-ended closing arm must be placed below the camshaft.
The lower image shows a Twist-Coil Spring being applied to the closing fork; the shaded area on the closing cam-lobe indicates the zone of applied pressure of the spring.
Figure 14, shows two different methods of application of the closing rocker in a DSA 'Jalve Train. The upper image a) -is a single-fulcrum installation, where both the opening and closing rockers operate from the same geometric center. The lower image b) shows two fulcrums, where the opening rocker and the closing one are pivoting from two different geometric centers.
Figure 15, is an actual-size cross-section of a DSA
mechanism using an RLB valve train component.

- .L2 -dsa figures - cont-d Figure 16, is a DSA valve train with a Flat Spring applied to the closing arm; please note, that it is the closing arm that aligns directly with the closing cam, while the opening cam-lobe is off-set.
Figure 17, shows a DSA valve train, in which two adjacent valves are serviced by 3 cam-lobes, instead of the four, that would be normally required.
Each valve is opened by its own cam-lobe - but the closing action for both emanates from a single cam-lobe, connected to 2 closing arms by splines of a short torsion spring.
The mechanisms uses an RLB component and is installed in an Attain Type IV engine port.
Figure 18, is a cross-section of a DSA Valve Train adapted to a XANTA II mechanism (Prior Art). Its rendition is in 'double-actual-size', or DSA, and shows a 1999 Porsche 911, boxer 6 motor.
Its bore is 96 mm, the intake valve is 39 mm (dia. ) x 44 mm long and its Upper Valve Guide employs a spherical hydr.
tappet. - The Return fork is connected to a short Twist Coil Spring.
It should be noted that the entire Attain DSA Valve Train is only about 90 mm tall (vertically up from the deck line); the original Porsche motor is 195 to 205 mm tall, which makes the Attain offering a little lower than 50$.

Claims