GB2211889A

GB2211889A - Engine throttle valve

Info

Publication number: GB2211889A
Application number: GB8726013A
Authority: GB
Inventors: Keith Gordon Hall
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-11-05
Filing date: 1987-11-05
Publication date: 1989-07-12
Also published as: GB8726013D0

Abstract

A rotary spool throttle valve (1) controls the air inlet pipes (9, Fig. 2) of two cylinders. The body 2 of the throttle valve may form an integral part of the engine cylinder head or the engine inlet manifold. The slotted edge (7, 8 Figs 2 and 3) of each spool through bore determines the flow cross-section at small valve openings and the spool is mounted in roller bearings 3. <IMAGE>

Description

THROTTLE VALVE.

This invention relates to a throttle valve for controlling the power output of internal or external combustion engines.

Throttle valves control the flow of fuel and/or air entering an engine. In most cases the throttle valve controls air flow by restricting the cross-sectional area of the engine air inlet pipe. Such controls should be inherently fail-safe and reduce the flow area to that required for engine idling when no operating pressure is exerted on the throttle control. They should also be able to increase progressively the flow area of the inlet pipe using a minimum operating force and provide an unobstructed passage when fully open. Additionally, for rapid engine response, there should be an individual throttle valve for each port in order to minimise the volume downstream of each throttle valve which may cause the engine to respond sluggishly to changes in the throttle control position.

Normal practice is to use one or two throttle plate valves for multi-cylinder engines. These are cheap and require only a low operating force. However, they obstruct the flow area of the pipe when fully open and in their simplest form have poor progression. Racing engines use slide throttles as the flow area is unrestricted when the slide is fully open. However, these are expensive and have poor progression and require high operating forces.

According to the present invention there is provided a rotary throttle valve for an air breathing engine having two or more cylinders, characterised in that the throttle valve is formed by a rotary shaft which extends through the air inlet pipes to each cylinder and, unless fully open, restricts the effective cross-section of each pipe according to its angular position.* The rotor of the throttle valve comprises a simple shaft having through slots therein for each inlet port. Rotation of the shaft varies the effective cross-section of the inlet pipe to each cylinder. A slot of variable width on the controlling edge of the rotor provides the initial throttle progression. The rotary throttle valve offers a low cost method of providing multiple throttles with both a smooth progression and unobstructed flow area when fully open.Mounting the shaft on rolling element bearings provides a throttle control with a very low operating force.

In order that the invention may be clearly understood it will now be described with reference to the accompanying drawings in which: Figure 1 shows a cross-section through a rotary throttle valve according to the invention for use with a two cylinder engine in the fully open position, Figure 2 shows a further cross-section through the rotary throttle shown in Figure 1 taken at right angles, Figure 3 shows a series of sections through a pipe containing the throttle valve showing four positions of the rotor, idle, 33% open, 66% open and fully open.

A rotary throttle valve, see Figure 1, consists of a rotor 1 within a housing 2. Bearings 3 located in end caps 4 at each end of the housing 2 ensure smooth rotation of the rotor 1 with little frictional resistance. A throttle arm 5 controls the angle of the rotor 1 with respect to the housing 2 and a return spring 6 urges the throttle to its closed position in the absence of any operating force on the throttle arm 5. Throttle stops are not shown for the sake of clarity.

The rotor 1 has a controlling edge 7, see Figure 2, with a profile that ensures even engine speed progression from idling to full throttle. The edge 7 carries a slot 8 located centrally with respect to each inlet pipe 9. The slot 8 is designed for allow the correct rate of air flow when the engine is idling. A combination of pressure effects around the rotor and/or counter balancing of the rotor ensures that the rotor will inherently act to close the throttle area when no controlling force is applied to it.

The rotor 1 is offset with respect to the inlet pipe, see Figure 3. The degree of offset is chosen to suit individual requirements. While offset enables a smaller diameter rotor two be used it increases the required angle of rotation from idling to full throttle. An optional bridge 10 aids rotor stiffness. The controlling rotor edge is shown by way of example on the downstream side of the rotor however it could be located on the upstream side.

It is clear that the rotary throttle valve may be extended to control a large number of air inlet pipes to the cylinders of an engine. However due to the cylinder arrangement frequently chosen for multi-cylinder engines it is often convenient to have two separate throttle valves so that half the pipes are controlled by one valve and half by the other. The two rotary throttle valves are coupled, preferably mechanically, to ensure that the sets of cylinders respond identically.

The low operating force for the preferred embodiments of the throttle valve facilitates non-manual control by electrical or hydraulic servo mechanisms. Systems of this nature allow constant speed operation.

When fuel injection is used it is convenient to have the throttle valve located close to the inlet ports of the cylinders. For this reason the body of the throttle valve may form an integral part of the engine cylinder head or the engine inlet manifold.

Claims

1. A rotary throttle valve for an air breathing engine having two or more cylinders, characterised in that the throttle valve is formed by a rotary shaft which extends through the air inlet pipes to each cylinder and, unless fully open, restricts the effective cross-section of each pipe according to its angular position.

2. The rotary throttle valve according to Claim 1, characterised in that the rotary shaft is mounted on roller bearings.

3. The rotary throttle valve according to Claims 1 or 2, characterised in that the shaft has a controlling edge whose profile is shaped for to provide consistent idling and smooth progression to maximum engine speed.

4. The rotary throttle valve according to Claim 3, characterised in that the controlling edge of the shaft in each pipe carries a central slot which defines the cross-section of the pipe when the engine is idling.

5. The rotary throttle valve according to any of the preceding claims, characterised in that the rotary throttle valve forms an integral part of an engine cylinder head.

6. The rotary throttle valve according to any of the claims 1 to 4, characterised in that the rotary throttle valve forms an integral part of an engine inlet manifold.

7. Rotary throttle valves according to Claim 1 as herein described with respect to the accompanying drawings.

8. An air breathing engine, characterised in that the engine has at least two cylinders and a throttle valve, as claimed in any of the claims 1 to 7, to control the air flow to the cylinders.

9. An air breathing engine, characterised in that the engine has an even number of cylinders and a pair of throttle valves, as claimed in any of the claims 1 to 7, to control the air flow to the cylinders, half the pipes being controlled by one valve and half by the other.