GB2138914A - Tappet - Google Patents

Abstract

A tappet is formed by a tubular shank 12 and a solid head 10. The head fits into the shank and is secured there, by interference or welding, so that a cavity is enclosed within the tappet, resulting in a substantial weight reduction. <IMAGE>

Description

SPECIFICATION Tappet This invention relatestoatappetforuse in an internal combustion engine.

It is always desirable to save mass, and therefore reduce the inertia, of valve train components in an internal combustion engine.

According to the invention, there is provided a tappet made from two parts secured together to enclose an internal cavity.

The present invention provides a simple way of reducing the inertia of the tappet by enabling the tappet to be made hollow.

Preferably one part is in the form of a tube with a closed end which forms a hollow shank for the tappet, and the other part comprises a head and a spigot, the spigot being adapted to fit into the open end of the tube.

The head may be secured to the tube by virtue of the spigot being a interference fit in the open end of the tube or by welding.

This construction has the advantage that the shank ofthe tappet can be of uniform outer diameter throughout its length, which results in the tappet having adequate strength.

The invention will now befurther described, by way of example, with reference to the accompanying drawing which shows a section through a tappet in accordance with the invention.

The tappet has a head 10 and a hollow shank 12. The shank 12 is formed by a steel thin-walled tube which is closed at its upper end 14and is shaped so asto engage with the end of a push rod.Thetube can be made in any convenient manner,forexample by extrusion and/or pressing.

The head 10, which will ride against a cam, has a spigot 16 which fits inside the open end of the tube, and is secured there. The head can be formed by sintering, casting, forging, or other suitable methods.

The assembled tappetthus has an internal cavity 18, the presence of which leads to a substantial reduction in the mass of the tappet. When the wall thickness and material specification of the tube are correctly chosen, this can be done without sacrificing strength.

1. Atappet made from two parts secured together to enclose an internal cavity.

2. Atappet as claimed in Claim 1,wherein one part is in the form of a tube with a closed end which forms a hollowshankforthe tappet, and the other part comprises a head and a spigot, the spigot being adapted to fit into the open end of the tube.

3. Atappet as claimed in Claim 2, wherein the shank is of uniform outer diameterthroughout its length.

4. Atappetsubstantially as herein described with reference to and as illustrated in the accompanying drawing.

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

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Tappet This invention relatestoatappetforuse in an internal combustion engine. It is always desirable to save mass, and therefore reduce the inertia, of valve train components in an internal combustion engine. According to the invention, there is provided a tappet made from two parts secured together to enclose an internal cavity. The present invention provides a simple way of reducing the inertia of the tappet by enabling the tappet to be made hollow. Preferably one part is in the form of a tube with a closed end which forms a hollow shank for the tappet, and the other part comprises a head and a spigot, the spigot being adapted to fit into the open end of the tube. The head may be secured to the tube by virtue of the spigot being a interference fit in the open end of the tube or by welding. This construction has the advantage that the shank ofthe tappet can be of uniform outer diameter throughout its length, which results in the tappet having adequate strength. The invention will now befurther described, by way of example, with reference to the accompanying drawing which shows a section through a tappet in accordance with the invention. The tappet has a head 10 and a hollow shank 12. The shank 12 is formed by a steel thin-walled tube which is closed at its upper end 14and is shaped so asto engage with the end of a push rod.Thetube can be made in any convenient manner,forexample by extrusion and/or pressing. The head 10, which will ride against a cam, has a spigot 16 which fits inside the open end of the tube, and is secured there. The head can be formed by sintering, casting, forging, or other suitable methods. The assembled tappetthus has an internal cavity 18, the presence of which leads to a substantial reduction in the mass of the tappet. When the wall thickness and material specification of the tube are correctly chosen, this can be done without sacrificing strength. CLAIMS

1. Atappet made from two parts secured together to enclose an internal cavity.

2. Atappet as claimed in Claim 1,wherein one part is in the form of a tube with a closed end which forms a hollowshankforthe tappet, and the other part comprises a head and a spigot, the spigot being adapted to fit into the open end of the tube.

3. Atappet as claimed in Claim 2, wherein the shank is of uniform outer diameterthroughout its length.

4. Atappetsubstantially as herein described with reference to and as illustrated in the accompanying drawing.