Internal-combustion engines – Poppet valve operating mechanism – Spring
Reexamination Certificate
2002-09-17
2004-06-08
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Spring
C123S090140, C123S090120, C123S090150
Reexamination Certificate
active
06745738
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to valve return springs. More particularly it relates to a device which replaces conventional metal valve return springs with pneumatic spring returns. The device is suited for use on a wide variety of applications where metal return springs are conventionally employed to bias valves toward a first position opposing a mechanical or other force which moves the valves toward and to, a second position. The device is especially well suited for retrofiting conventional mechanical valve return spring assemblies used on internal combustion and other cycled engines. However, it would also serve well as an original equipment pneumatic valve return spring to replace conventional spring assemblies and provide a wide degree of utility and performance improvement in both the function and timing of such valve assemblies used on internal combustion and other engines employing valves for venting and/or intake.
2. Prior Art
Valve springs are widely used throughout the world on a wide variety of applications. Generally, the valve spring is used to bias the valve against an opposing force usually generated by a cam or valve actuating lever acting on the valve to force it toward, and to, a second or open position. The force provided by the valve return spring acts to return the valve to the first or closed position where the valve head is seated in a valve seat thus sealing the aperture inside the valve seat communicating with a chamber which is vented or filled through the aperture in the valve seat surrounding the valve head.
Such an arrangement is quite popular in the operation of internal combustion engines using gasoline, diesel, or similar combustive fuels where valve springs are conventionally used to bias intake and exhaust valves toward a first closed position by imparting a biasing force to counter the biasing force from a mechanical lever such as a valve lifter or cam lobe that imparts force on the actuating end of the valve to bias it toward a second or open position.
Conventional spring and valve assemblies suffer from a number of problems. One such problem is that of metal fatigue of the springs themselves which can cause them to break and the valve to fail with major mechanical failure consequences in engines turning at high revolutions. A second concern is that of valve timing which tends to be set by the mechanical cam or other device powering the valve lifter imparting force to the valve stem. In purely mechanical valve spring arrangements, varying the timing of the valves to achieve better fuel economy or engine performance is extremely complicated and unreliable and thus generally not worth the effort due to the potential consequences from an increased risk of failure of the valve system. Such purely mechanical valve spring systems also suffer from other maladies during high revolutions of the engine in that they tend to float or fail to close the valve quickly enough resulting in loss of performance and sometimes engine failure should the float be too extreme.
In an attempt to overcome such problems associated with mechanical spring systems, pneumatic or fluid actuated valve systems have been tried to provide the biasing means for such valves to resist the force imparted by the valve lever and return the valve to its seat once the cycle is complete. Pneumatic systems, using compressible gas, provide the ability to vary the force and timing of the valve closure and to overcome the shortcomings of mechanical spring valve biasing systems. Such pneumatic assemblies however, often require exotic dedicated cylinder head assembly machining utilizing drilled air supply distribution passages, integral valve return spring operating bores, complex valve stem seals, oiling arrangements, sealing bellows and sophisticated air control arrangements. Such exotic purpose-built or dedicated cylinder head valve operating systems remain largely unavailable due to the extreme costs involved with engineering, testing and manufacturing. All of these attempts add to the complexity and cost of a high performance competitive engine and tend to reduce the inherent reliability of the same. As a consequence, such pneumatic valve biasing assemblies are virtually impossible to use to retrofit the millions of existing internal combustion engines and are not cost effective when used as original equipment due to the major amount of machining and retooling required to implement the current complicated systems. However, various prior art has attempted to provide a pneumatic valve spring system suitable for use on internal combustion engines.
U.S. Pat. No. 4,592,313 (Speckhart) teaches a pneumatic valve return for intake or exhaust valves. Speckhart uses an upper piston attached to and acting on a valve stem when pressure from a pressurized gas supply is communicated to the upper piston. However, Speckhart is not easily retrofited to the millions of existing engines due to its interface with the valve. Also, Speckhart communicates the pressurized air in the pneumatic spring directly to the valve stem itself thereby causing sealing problems.
U.S. Pat. No. 5,586,529 (Vallve) discloses a pneumatic valve spring member that replaces the conventional valve spring. However, the dual donut or flexible baffle arrangement taught by Vallve would be unreliable in the high heat and friction environment encountered by valve springs in internal combustion engines.
U.S. Pat. No. 5,943,988 (Burger) teaches a gas change valve for internal combustion engines. However, Burger requires the use of an electromagnetic structure and a switching system in combination with an electro-pneumatic means for gas pressure. Burger is thus not an easy or desirable retrofit to existing vehicles and requires a complicated electromagnet system which would increase cost and would be prone to failure in the high heat and oily environment of engine valves.
U.S. Pat. No. 5,109,812 (Ericson) features a double pneumatic spring to translate a valve in both directions and eliminate the requirement for a valve actuating lever and/or cam. However, Ericson by design is not easily installed to retrofit existing valve springs on engines and even as original equipment would require a complete redesign of valve actuation in conventional internal combustion engines.
As such, there is a continuing need for improvement in valve biasing devices used to provide a force to bias valves which seal chambers to their closed or sealed position. Such a device should be simple in both operation and construction rendering it simple to install and maintain. Further, such a device should be easily installed as a retrofit to currently used valve springs on internal combustion engines in use today. Still further, such a device should be constructed to operate reliably in the high heat and oily environment of valve springs of internal combustion engines and should not easily fail.
SUMMARY OF THE INVENTION
The applicant's device is an improved pneumatic valve return spring and system for operation, biasing force control, and operation thereof. The device in its simplest form to replace a conventional circular valve spring features a plurality of housings.
A static housing that is essentially donut shaped is mounted to a fixed position on a cylinder head wherein an aperture defined by an inner wall of the housing surrounds a conventional valve stem. An outer wall of the static housing, circumferentially parallel and substantially equally spaced from its inner wall, communicates with the inner wall on a bottom side and thereby defines a static housing chamber. An open side opposite the bottom side forms a static circular aperture communicating with the static housing chamber.
A dynamic housing, is shaped similar to the static housing also has an inner wall that surrounds a valve stem and is dimensioned for lateral engagement with the static housing. The inner wall is connected by a top wall to a circumferentially parallel outer wall equally spaced from the inner wall. A reciprocating chamber is def
Corrigan Jaime
Denion Thomas
Harms Donn K.
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