GB2107393A - I.C. engine with a fluid pressure valve operating system - Google Patents

Abstract

A fluid pressure operable piston 14 is operatively connected to the engine valve 10. Fluid under pressure can be admitted to the cylinder containing the piston by way of a first electromagnetic valve 20 and exhausted to a drain by way of a second electromagnetic valve 29. The system includes a control system to control the valves 20 and 29 and also a transducer 35 to sense the position of the piston 14. The respective valve 20 or 29 is closed just before the piston reaches the end of its stroke to slow the movement of the piston and is then re-opened to permit the piston to complete its stroke. <IMAGE>

Description

SPECIFICATION Engine valve operating system This invention relates to an operating system for a valve of a reciprocating piston engine.

British Patent Specification 1578019 describes two examples of operating systems for a valve of an internal combustion engine of the reciprocating piston type. In one example the usual form of valve spring is utilized to close the valve but a fluid pressure operable piston is provided to open the valve, the application of fluid under pressure to the piston being controlled by a first electromagnetic valve and the closure of the engine valve being controlled by a second electromagnetic valve. In the other example a further piston is provided and fluid under pressure acts thereon in the direction to close the valve. The valve operating mechanism and/or engine valve in each case is subject to high impact forces at the end of both the opening and closing strokes of the engine valve and these impact forces result in wear of the mechanism and/or the engine valve.

The object of the invention is to provide an operating system for an engine valve in a simple and convenient form.

According to the invention an operating system for a valve of a reciprocating piston engine comprises a piston operatively connected to the valve and contained within a cylinder, a first electromagnetic valve for controlling the flow of fluid under pressure to one end of the cylinder thereby to move the piston in the direction to open the valve, a second electromagnetically operable valve operable to allow fluid to escape from said one end of the cylinder, means for moving the engine valve to the closed position, the appropriate one of said electromagnetic valves being closed towards the end of the stroke of the engine valve to slow the movement thereof, the electromagnetic valve being reopened to allow the engine valve to complete its stroke.

Two examples of an engine valve operating system in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a diagrammatic view of a system for spring loaded valves and Figure 2 is a similar view for positively closed valves.

Referring to Figure 1 of the drawings four engine valves are indicated at 10, 11, 12, and 13 and each valve has associated therewith a valve spring which biases the engine valve to the closed position.

Operatively connected to the stems of the valves are pistons 14, 15, 16 and 17 respectively these being housed within respective cylinders. The system also includes a source 18 of liquid under pressure and this is connected to a supply gallery 19. The gallery is connected to the ends of the cylinders containing the pistons and which are remote from the valves, by branch passages each of which includes an electromagnetically operated valve, the valves being referenced 20, 21 22 and 23 in the drawing. The aforesaid branch passages also communicate with a drain gallery 24 by way of spring loaded non-return valves respectively, these being referenced 25, 26, 27 and 28. The gallery 24 can be placed in communication with a drain by way of a second electromagnetically operable valve 29.In order to effect opening of for example the valve which is referenced 10, the electromagnetically operated valve 20 is opened to permit fluid from the source 18 to pass into the cylinder containing the piston 14. The force exerted upon the piston effects opening of the valve. Whilst the valve 20 is open the valve 29 is maintained in the closed position so that no fluid will flow into the gallery 24. The remaining engine valves remain closed under the action of their associated springs because the valves 26, 27, 28 associated therewith will remain closed.

As the valve moves towards the fully open position the piston 14 will encounter the end wall ofthe cylinder or if an external stop is provided this will be engaged. A considerable impact occurs due to the energy attained by at least the piston, during its movement to open the valve. It is therefore arranged that just prior to the end of the stroke, the valve 20 is closed. This creates an hydraulic lock intermediate the valve 20 and the cylinder which halts or slows down the movement of the piston 14 before it reaches the mechanical stop. The valve 20 is then opened to permit the piston to move into contact with the stop.

Consider now the situation when the valve 20 is closed and the valve 29 opened. In this situation the valve spring acts upon the valve to urge the valve towards the closed position and in so doing the piston 14 is moved and displaces fluid by way of the non-return valve 25 to the gallery 24 and hence to a drain by way of the valve 29. If the valve is allowed to move without restriction, it will impact against its seating and continued movement of the piston 14 may take place. In order to minimise the impact of the valve 10 upon the seating the valve 29 is closed just prior to the valve engaging the seating and this acts to halt the movement of the piston. The valve 29 is then re-opened to allow the valve to seat.

It is obviously necessary to control the operation of the electromagnetically valves very carefully and in order to do this it is necessary to know the position of the piston during its movement and hence the associated valve. For this purpose the pistons have associated therewith transducers 35 which supply to an appropriate control system, signals indicative of the positions of the various pistons.

In the arrangement shown in Figure 2 the valve springs are omitted and the engine valves are returned to their closed positions by further pistons referenced 31,32,33 and 34 which are smaller in diameter than the first mentioned pistons. The further pistons are subject to the fluid pressure provided by the source 18 through a further gallery which is referenced 30.

1. An operating system for a valve of a reciprocating piston internal combustion engine compris

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Engine valve operating system This invention relates to an operating system for a valve of a reciprocating piston engine. British Patent Specification 1578019 describes two examples of operating systems for a valve of an internal combustion engine of the reciprocating piston type. In one example the usual form of valve spring is utilized to close the valve but a fluid pressure operable piston is provided to open the valve, the application of fluid under pressure to the piston being controlled by a first electromagnetic valve and the closure of the engine valve being controlled by a second electromagnetic valve. In the other example a further piston is provided and fluid under pressure acts thereon in the direction to close the valve. The valve operating mechanism and/or engine valve in each case is subject to high impact forces at the end of both the opening and closing strokes of the engine valve and these impact forces result in wear of the mechanism and/or the engine valve. The object of the invention is to provide an operating system for an engine valve in a simple and convenient form. According to the invention an operating system for a valve of a reciprocating piston engine comprises a piston operatively connected to the valve and contained within a cylinder, a first electromagnetic valve for controlling the flow of fluid under pressure to one end of the cylinder thereby to move the piston in the direction to open the valve, a second electromagnetically operable valve operable to allow fluid to escape from said one end of the cylinder, means for moving the engine valve to the closed position, the appropriate one of said electromagnetic valves being closed towards the end of the stroke of the engine valve to slow the movement thereof, the electromagnetic valve being reopened to allow the engine valve to complete its stroke. Two examples of an engine valve operating system in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a diagrammatic view of a system for spring loaded valves and Figure 2 is a similar view for positively closed valves. Referring to Figure 1 of the drawings four engine valves are indicated at 10, 11, 12, and 13 and each valve has associated therewith a valve spring which biases the engine valve to the closed position. Operatively connected to the stems of the valves are pistons 14, 15, 16 and 17 respectively these being housed within respective cylinders. The system also includes a source 18 of liquid under pressure and this is connected to a supply gallery 19. The gallery is connected to the ends of the cylinders containing the pistons and which are remote from the valves, by branch passages each of which includes an electromagnetically operated valve, the valves being referenced 20, 21 22 and 23 in the drawing. The aforesaid branch passages also communicate with a drain gallery 24 by way of spring loaded non-return valves respectively, these being referenced 25, 26, 27 and 28. The gallery 24 can be placed in communication with a drain by way of a second electromagnetically operable valve 29.In order to effect opening of for example the valve which is referenced 10, the electromagnetically operated valve 20 is opened to permit fluid from the source 18 to pass into the cylinder containing the piston 14. The force exerted upon the piston effects opening of the valve. Whilst the valve 20 is open the valve 29 is maintained in the closed position so that no fluid will flow into the gallery 24. The remaining engine valves remain closed under the action of their associated springs because the valves 26, 27, 28 associated therewith will remain closed. As the valve moves towards the fully open position the piston 14 will encounter the end wall ofthe cylinder or if an external stop is provided this will be engaged. A considerable impact occurs due to the energy attained by at least the piston, during its movement to open the valve. It is therefore arranged that just prior to the end of the stroke, the valve 20 is closed. This creates an hydraulic lock intermediate the valve 20 and the cylinder which halts or slows down the movement of the piston 14 before it reaches the mechanical stop. The valve 20 is then opened to permit the piston to move into contact with the stop. Consider now the situation when the valve 20 is closed and the valve 29 opened. In this situation the valve spring acts upon the valve to urge the valve towards the closed position and in so doing the piston 14 is moved and displaces fluid by way of the non-return valve 25 to the gallery 24 and hence to a drain by way of the valve 29. If the valve is allowed to move without restriction, it will impact against its seating and continued movement of the piston 14 may take place. In order to minimise the impact of the valve 10 upon the seating the valve 29 is closed just prior to the valve engaging the seating and this acts to halt the movement of the piston. The valve 29 is then re-opened to allow the valve to seat. It is obviously necessary to control the operation of the electromagnetically valves very carefully and in order to do this it is necessary to know the position of the piston during its movement and hence the associated valve. For this purpose the pistons have associated therewith transducers 35 which supply to an appropriate control system, signals indicative of the positions of the various pistons. In the arrangement shown in Figure 2 the valve springs are omitted and the engine valves are returned to their closed positions by further pistons referenced 31,32,33 and 34 which are smaller in diameter than the first mentioned pistons. The further pistons are subject to the fluid pressure provided by the source 18 through a further gallery which is referenced 30. CLAIMS

1. An operating system for a valve of a reciprocating piston internal combustion engine compris ing a piston operatively connected to the valve and contained within a cylinder, a first electromagnetic valve for controlling the flow of fluid under pressure to one end of the cylinder thereby to move the piston in the direction to open the valve, a second electromagnetically operable valve operable to allow fluid to escape from said one end of the cylinder, means for moving the engine valve to the closed position, the appropriate one of said electromagnetic valves being closed towards the end of the stroke of the engine valve to slow the movement thereof, the electromagnetic valve being reopened to allow the engine valve to complete its stroke.

2. A system according to claim 1 including a transducer for sensing the position of the piston and a control circuit for said valves, said transducer providing a signal representing the position of the piston to said control circuit.

3. A system according to claim 1 or claim 2 in which the means for moving the valve to a closed position comprises a further piston operatively connected to the valve.

4. An operating system for a valve of a reciprocating piston internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with referpence to Figure 1 of the accompanying drawings.

5. An operating system for a valve of a reciprocating piston internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.