GB2131539A

GB2131539A - Electric starting aids for internal combustion engines

Info

Publication number: GB2131539A
Application number: GB08327921A
Authority: GB
Inventors: Geoffrey Richard French
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1982-12-02
Filing date: 1983-10-19
Publication date: 1984-06-20
Also published as: GB2131539B; GB8327921D0

Abstract

The aid has a body part to be mounted in an inlet manifold of the engine. A fuel inlet is formed in the body part for connection in use to a source of fuel. A fuel vaporiser includes an electric heating element carried by the body part which in use receives fuel from the inlet. An orifice controls fuel flow from the inlet to the vaporiser and is located in or adjacent the vaporiser at a position such that the component in which the orifice is formed is heated by the electric heating element. This minimises the risk of the orifice being blocked in use by frozen fractions of fuel. The orifice is defined in a plate located in a tubular portion of the vaporiser. The plate is cup-shaped and is held in the extension by frictional engagement of a skirt portion. -

Description

SPECIFICATION Electric starting aids for internal combustion engines This invention relates to electric starting aids for use with internal combustion engines more particularly of the compression ignition type, the aids being of a kind comprising a body part which is adapted to be mounted in the inlet manifold of an engine, a fuel inlet formed in the body part for connection in use to a source of fuel and a fuel vaporiser including an electric heating element.

carried by the body part which in use receives fuel from said inlet and vaporises the fuel.

Such starting aids frequently incorporate an electric ignition element to ignite the air/fuel mixture which is produced by the action of the vaporising device, the resulting flame acting to heat the air flowing into the engine. Some forms of the aid do not have the ignition element and the vaporised fuel is drawn into the engine to assist the starting thereof.

The starting aids are usually supplied with fuel from a small header tank which during normal operation of the associated engine is maintained full of fuel and the control of fuel flow to the aid is by means of suitable control valve which is opened when it is required to effect operation of the aid. In order to control the rate of flow of fuel an orifice is provided, the size of the orifice being chosen to take into account the slight differences of fuel pressure in different engine installations and the different engine requirements. One form of starting aid of the kind specified is seen in British published specification 2078853 and in this example the aforesaid orifice is formed in an orifice plate which is located within the fuel inlet.

It will of course be understood that the starting aids are utilised when temperatures are low and the temperature prior to starting the engine may be so low that fractions of the fuel freeze and form globules of wax. Such globules of wax can block the aforesaid orifice with the result that no or an insufficient amount of fuel is delivered to the vaporiser.

The object of the present invention is to provide a starting aid of the kind specified in an improved form.

According to the invention an electric starting aid of the kind specified comprises an orifice for controlling fuel flow from the fuel inlet to the vaporiser said orifice being located in or adjacent the vaporiser at a postion such that the component in which the orifice is formed is heated by the electric heating element, thereby to minimise risk of the orifice being blocked in use by frozen fractions of fuel.

An example of a starting aid in accordance with the invention will now be described with reference to the accompanying drawing which shows the aid in section and also shows the associated fuel supply system.

The aid to be described is of the type which produces vaporised fuel which is entrained within the air flowing in the inlet manifold of a compression ignition engine.

Referring to the drawing the aid comprises a body part 10 which is of stepped cylindrical form and which has an hexagonal portion 11 and a threaded portion 12. The threaded portion 1 2 in use, is secured within a boss or other mounting on the air inlet manifold of the engine.

A central passage 1 3 is defined in the body and at one end this constitutes a fuel inlet 14 which by means of a control valve 1 5 communicates with a source of fuel in the form of header tank 1 6, this in use being disposed above the starting aid. The tank during normal operation of the engine is kept full of fuel in any convenient manner. Instead of being connected to a header tank, the fuel inlet may receive fuel from a pump.

At the end of the body remote from the inlet 14, there is located a fuel vaporiser generally indicated at 17 and which in the particular example, comprises a tubular portion 1 8 formed integrally with the body 10. The interior of the tubular portion 1 8 communicates with the passage 13 and its end remote from the inlet 14 is closed by a plug 1 9. The plus 19 carries a cylindrical member 20 which extends within the tubular portion 18 and defines an annular space with the inner wall of the tubular portion.

Formed in the tubular portion 1 8 is an aperture or apertures 21 and these communicate with the aforesaid annular space.

Surrounding the tubular member 18 is a heating element 22. The heating element is formed from electrically conductive tape and one end of the tape is secured to the plug 19 so as to make electrical connection therewith. The other end of the heating element is connected to a conductive member 23 which is integrally formed with an electrical terminal member 24. The conductor 23 extends within a bore 25 formed in the body, the bore being filled with an electrical insulation material 26 such for example as fused glass. The terminal member is electrically insulated from the body.Either the heating element 22 or the exterior surface of the tubular portion 1 8 is provided with an insulating coating and the arrangement is such that when the body and the terminal member are connected to the terminals of a d.c. supply, the heating element will heat the tubular portion to a temperature such that when the valve 1 5 is opened, fuel flowing through the outlets 21 will be vaporised. The flow of fuel into the vaporiser is controlled by an orifice 27 which conveniently is formed in an orifice plate 28 which is of cup-shaped form having an integral skirt portion. The orifice plate is located in the passage 1 3 at a position such that it will receive heat from the heating element.The orifice plate is retained in position by frictional engagement of the skirt portion with the inner wall of the tubular extension. If therefore under cold conditions fractions of the fuel supplied to the aid are frozen, any globules of wax flowing down the passage 13 towards the vaporiser, will upon contact with the orifice plate, melt thereby to minimise the risk of blockage of the orifice 27 and an interruption in the flow of fuel to the vaporiser.

The starting aid also includes a tubular shield 29 which extends around the vaporiser in spaced relationship therewith, the shield being provided with apertures 30 through which air can enter into the space surrounding the vaporiser thereby to carry the vaporised fuel into the air stream flowing within the air inlet manifold.

By the arrangement described the orifice plate is heated during the use of the starting aid and as compared with the starting aid shown in British published specification 2078853, the orifice plate will become heated very quickly once electric power has been supplied to the aid. If the orifice plate is located within the body as shown in the aid illustrated in the aforesaid specification, the mass of the body together with the manifold will act as a heat sink so that even when the aid has been in use for some time, the temperature of the orifice plate may still not be sufficient to prevent clogging of the orifice by frozen fractions of fuel.

As mentioned the starting aid may also incorporate an electric ignition element this being wound in spaced relationship about the vaporiser and in spaced relationship to the inner surface of the shield 29. The ignition element ignites the air/fuel mixture created as a result of the mixing of air entering the apertures 30 with the vaporised fuel. If desired the apertures may have deflector plates associated therewith, the plates conveniently being formed by partial piercing of the apertures. The plates are bent inwardly and extend in the same circumferential direction to promote swirling of the air and thorough mixing of the air and fuel.

Claims

1. An electric starting aid for use with internal combustion engines more particularly of the compression ignition type, the aid being of the kind comprising a body part which is adapted to be mounted in the inlet manifold of the engine, a fuel inlet formed in the body part for connection in use to a source of fuel, a fuel vaporiser including an electric heating element carried by the body part which in use receives fuel from said inlet and vaporises the fuel, an orifice for controlling fuel flow from the fuel inlet to the vaporiser said orifice being located in or adjacent the vaporiser at a position such that the component in which the orifice is formed is heated by the electric heating element, thereby to minimise risk of the orifice being blocked in use by frozen fractions of fuel.

2. A starting aid according to Claim 1 in which said vaporiser includes a tubular portion through which fuel can flow from said inlet, said orifice being defined in an orifice plate located within said tubular portion.

3. A starting aid according to Claim 2 in which said orifice plate is of cup-shaped form, the orifice plate being held within the extension by frictional engagement of the skirt portion of the orifice plate with the inner wall of the tubular portion.

4. An electric starting aid for use with an internal combustion engine comprising-the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawing.