Valve operating apparatus and method for an engine

Abstract

A valve operating apparatus for an internal combustion engine including: a housing (2); a reciprocating piston (1) residing wholly within the housing (2), the reciprocating piston (1) driving one or more poppet valves (7); 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 (16); 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 (17); wherein said reciprocating piston (1), 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 (7), and wherein a connector (9) passes through an aperture (14) in said housing (2) to connect said reciprocating piston (1) to said one or more poppet valves (7), said reciprocating piston (1) in co-operation with an internal wall of the housing forming a seal to prevent substantial egress of fluid from the housing (2) through said aperture (14).

Description

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 exam...

AI Technical Summary

Benefits of technology

"The present invention provides a valve operating apparatus for an internal combustion engine that includes a housing, a reciprocating piston, and one or more fluid supply and drain paths. The apparatus allows for precise control of the movement of the poppet valves through the use of control valves that regulate the flow of fluid to each piston end. The apparatus is more efficient and reduces friction as compared to prior systems, allowing for higher engine operating speeds. The apparatus also includes a connector rod that drives the poppet valves, and the movement of the piston is achieved through a pressure difference between the two ends. The apparatus is easy to control and operate at high speeds."

Problems solved by technology

However, either approach results in efficiency losses.

These systems tend to be very complicated and are not economic to manufacture.

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.

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.

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.

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.

Actuation methods based upon this principle of operation necessarily face difficulty in reaching the high operating speeds required by an internal combustion engine.

However, this again results in slowing down the system and causing difficulty in operating at the high speeds required for a combustion engine.

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.

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.

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.

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.

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