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Valve operating apparatus and method for an engineRelated Patent Categories: Internal-combustion Engines, Poppet Valve Operating Mechanism, Hydraulic SystemValve operating apparatus and method for an engine description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070113804, Valve operating apparatus and method for an engine. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to a means and method of operating the intake and/or exhaust valves of an internal combustion engine. More particularly the invention relates to a connection arrangement between the operating apparatus and the valves, and the use of pressurised fluid to actuate valves during operation of an engine. BACKGROUND OF THE INVENTION [0002] Controlling the lift and timing of intake and/or exhaust (poppet) valves in an automotive engine is a necessary aspect of operating an engine. Traditionally, control has been achieved by mechanical systems using a cam to drive the stem of the intake or exhaust poppet valves, while a throttle was used to control the air flow supplied to individual cylinders. More recently, it has been known to have a cam which allows the poppet valve lift to be adjusted. However, either approach results in efficiency losses. [0003] Many solutions have been proposed to address the efficiency loss problem. For example, mechanical solutions have been proposed to shift the phase of the camshaft or the lift of the poppet valves to improve efficiency. There have also been hydraulic-mechanical proposals attempting to shift the phase of the camshaft or lift of the valves. These systems tend to be very complicated and are not economic to manufacture. [0004] Electro-magnetic solutions using a solenoid to drive the poppet valves have also been proposed, however a solenoid of sufficient size is relatively big, heavy and expensive, and thus not suitable for mass production. [0005] Hydraulic solutions without a camshaft have been proposed, however the complexity of previous attempts to replace a valve train cam and throttle with a hydraulic solution has made them difficult to manufacture and thus uneconomic. The previously proposed hydraulically driven poppet valves generally include both a high and a low pressure fluid supply, requiring major modifications to an existing engine using a camshaft. [0006] Hence, the retrofitting of such devices is expensive because prior art proposals require the hydraulic system to be mounted in-line with the longitudinal axis of the poppet valve and as a result, the existing cylinder head requires extensive modification. Such solutions are generally considered to only be suitable for incorporating into purpose built engines. [0007] Some prior solutions tend to rely on a surface area difference at each end of the actuating piston, actuating the valve in one direction by the resulting force of a surface area difference. By supplying fluid constantly to a first end of the piston and alternately supplying and draining fluid to the second end, the fluid pressure at the first end, having smaller surface area, causes the piston to move when there is no pressure at the second end, and the fluid pressure multiplied by a larger surface area at the second end results in a greater force to return the piston when fluid is supplied to the second end. Accordingly, the solution involving differing surface areas remains inefficient, as the force applied by the pressure at the larger end must overcome the constant force applied by the pressure at the smaller end, slowing down the system and causing difficulty in operating at the high speeds required for a combustion engine. [0008] For example, DE19826047A1 and WO03106820A1 disclose hydraulic actuation of the poppet valve by supplying fluid to a reciprocating piston at a nominally constant pressure. The force driving the piston, which may be approximated as Force=Pressure.times.Area, is dependent on the difference in surface area of each end of the piston. Actuation methods based upon this principle of operation necessarily face difficulty in reaching the high operating speeds required by an internal combustion engine. [0009] Other prior solutions rely on constantly supplying fluid at a lower pressure to one piston end, and supplying fluid at a higher pressure to the other end to drive the piston. By alternately supplying and draining the higher pressure end of the piston, the piston is caused to reciprocate. However, this again results in slowing down the system and causing difficulty in operating at the high speeds required for a combustion engine. [0010] Further efficiency problems exist in the above systems and in the electro-hydraulic valve operating apparatus systems disclosed in DE19826047A1, WO9207172 and U.S. Pat. No. 6,321,703. Problems experienced by such electro-hydraulic valve operating apparatus include the difficulty of sealing fast moving parts, in particular the poppet valves themselves. Where a valve stem passes through the wall of a chamber that is required to contain fluid under pressure, a seal extending around the stem is necessarily required to prevent a significant leakage of fluid from the chamber around the valve stem. Accordingly, the stem requires a "high pressure" seal extending around the stem to prevent loss of fluid. Of course, a high pressure seal causes a significant frictional force that must be overcome in order to operate the valve, hence requiring higher fluid pressures in the valve operating apparatus in order to operate the piston. This in turn requires a stronger seal to prevent pressurised fluid from leaking out of a chamber around the poppet valve stem. The frictional force presented by a high pressure seal and the greater fluid pressure required to operate the valve results in less precision of control of the position of the poppet valve(s), less ability to provide variable control and hence lower overall engine efficiency, as the lift and timing of the poppet valves, the amounts of air being fed into the engine and hence thermodynamic efficiency of the engine cannot be controlled with the desired precision. [0011] The prior art does not provide a simple, reliable and in particular, efficient, variable engine valve control system. Previously proposed solutions are complex and inefficient to operate. The inefficiencies of fluid pressures working against each other and the internal friction caused by high pressure seals around valve stems result in less precision of control and difficulties in achieving operation at high speed. Ultimately, the inability to operate the engine in the most efficient way inhibits the ability to operate a hydraulic valve actuating apparatus at the speeds required. The prior art is also not generally suitable for retrofitting to existing engines that include a camshaft. [0012] As the characteristics of simplicity, reliability and efficiency are important attributes for components of complex machines such as engines, it is a primary object of the present invention to provide a means and method of operating valves that embodies one or more of these characteristics moreso than devices proposed in the prior art. [0013] Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art on or before the priority date of the claims herein. SUMMARY OF THE INVENTION [0014] A first aspect of the present invention provides a valve operating apparatus for an internal combustion engine including: [0015] a housing; [0016] a reciprocating piston residing wholly within the housing, the reciprocating piston driving one or more poppet valves; [0017] a first fluid supply path and a first fluid drain path, each path being controllable to supply or drain fluid to/from a first reciprocating piston end; [0018] a second fluid supply path and a second fluid drain path, each path being controllable to supply or drain fluid to/from a second reciprocating piston end; [0019] wherein said reciprocating piston, in use, is driven between a first position and a second position by controlling said fluid in said supply and drain paths, thereby operating said one or more poppet valves, and wherein a connector passes through an aperture in said housing to connect said reciprocating piston to said one or more poppet valves, said reciprocating piston in co-operation with an internal wall of the housing forming a seal to prevent substantial egress of fluid from the housing through said aperture. [0020] In a particularly preferred embodiment, said aperture is substantially sealed by at least a portion of the external surface of said reciprocating piston to prevent egress of fluid from the housing through said aperture. [0021] Prior hydraulic valve operating apparatus requires a seal between the moving poppet valve stem and the hydraulic fluid supply at the point where the poppet valve stem passes through the housing. Advantageously, the present arrangement avoids such a seal. Instead, the reciprocating piston itself acts as a seal to prevent pressurised fluid from reaching the aperture from within the housing. Continue reading about Valve operating apparatus and method for an engine... Full patent description for Valve operating apparatus and method for an engine Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Valve operating apparatus and method for an engine patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Valve operating apparatus and method for an engine or other areas of interest. ### Previous Patent Application: Air-hybrid and utility engine Next Patent Application: Internal combustion engine comprising a variable valve lift system and a method for controlling valve lift shifting Industry Class: Internal-combustion engines ### FreshPatents.com Support Thank you for viewing the Valve operating apparatus and method for an engine patent info. 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