GB2150976A

GB2150976A - Starting aids for internal combustion engines

Info

Publication number: GB2150976A
Application number: GB08428843A
Authority: GB
Inventors: Brian John Chalke
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1983-12-07
Filing date: 1984-11-15
Publication date: 1985-07-10
Also published as: FR2556414A1; ES8606577A1; GB8332581D0; GB8428843D0; ES538348A0

Abstract

The engine is fitted with an electrical starting aid 15 including a heating element connected in series with a resistor 20 the purpose of which is to control the current flow in the heating element. In order to dissipate the heat generated in the resistor 20 it is associated with a fuel filter 14 or a housing 21 through which fuel flows to the pump 11. The fuel flowing to the engine serves to remove heat from the resistor. The starting aid is mounted in the air inlet manifold of the engine and ignites fuel drawn from a supplementary fuel tank 16. <IMAGE>

Description

SPECIFICATION Engine system This invention relates to an internal combustion engine system including an engine having a fuel supply system and a starting aid system, the starting aid system including a starting aid of the kind having an electrically operated heating element, a resistor connected in series with said heating element, the series combination of heating element and resistor being connected in use across the terminals of a source of electric supply, said resistor acting in use to allow the heating element to reach its working temperature quickly and then acting to control the power input to the heating element.

In one form of such an aid the heating element is exposed within a combustion space of the associated engine but in another form of aid the heating element is used to ignite fuel which is burnt within the air inlet manifold of the engine. In both forms the heat generated assists the starting of the engine.

The resistor may be a simple ballast resistor which becomes heated by the current flowing therethrough so that its resistance gradually increases. It may however be a less temperature sensitive resistor and be provided with a switch in parallel therewith which can be opened to reduce the power input to the heating element of the starting aid. In use both forms of resistor dissipate a considerable amount of heat and have to be constructed in a manner to withstand the heat. The resistor also has to be shrouded and its mounting position has to be carefully chosen to avoid damage to adjacent parts.

The object of the present invention is to provide an engine system of the kind specified in a simple and convenient form.

According to the invention in an engine system of the kind specified said resistor is associated with the fuel system of the engine so that the fuel flowing in the fuel system acts to remove heat from the resistor.

Examples of engine system in accordance with the invention will now be described with reference to the accompanying diagrams.

Referring to Fig. 1 there is indicated an engine 10 of the compression ignition type and to which fuel is supplied by a high pressure fuel pump 11. The fuel pump 11 receives fuel drawn from a tank 1 2 by a low pressure pump 1 3 the fuel delivered by the pump 1 3 passing through a fuel filter 1 4 before it is supplied to the pump 11.

In order to facilitate starting of the engine a starting aid 1 5 is provided, the starting aid being of the kind which is mounted in the air inlet manifold of the engine and which vaporises and ignites fuel which is drawn from a supplementary fuel tank 16. For this purpose the starting aid 1 5 includes an electrically operated heating element. The aid incorporates a temperature responsive valve which opens to allow fuel flow through the aid.

However, the aid may incorporate a solenoid operated valve which is energised at the same time as the heating element for the same purpose. It will be understood that the solenoid operated valve could be provided as a separate item. The engine is provided with an electric starting motor 1 7 which draws power upon closure of a switch 1 8 from a storage accumulator 1 9.

The heating element of the starting aid is energised at the same time as the starting motor 17, electrical current being supplied to the heating element by way of resistor 20.

The resistor is of the type which is formed from a special material which exhibits a substantial increase in its resistance as its temperature increases. Upon closure of the switch 18, the starting motor is brought into operation and the heating element of the starting aid energised. This causes vaporisation and ignition of the fuel which is burnt in the air inlet manifold. The heating element of the starting aid achieves its working temperature very quickly but due to the passage of electric current through the resistor 20 the latter also becomes heated and the increase in resistance serves to limit and possibly also effect a reduction in the current flowing in the heating element so that the latter is protected.

A considerable amount of heat is dissipated in the resistor 20 and in order to dissipate this heat the resistor is mounted on the filter so that the heat is passed to the fuel flowing to the pump 11. The fuel therefore acts to cool the resistor and the filter also acts as a convenient means for mounting the resistor.

In addition, the heat which is supplied to the fuel serves to minimise the risk of, in cold weather, fractions of the fuel freezing and thereby clogging the filter element of the filter. The resistor instead of being mounted in or on the housing of the filter may be mounted in a separate housing positioned upstream of the filter, this position being indicated in dotted outline at 21.

Turning now to Fig. 2, the various components which have the same function as those of Fig. 1 are assigned the same reference numerals. In the arrangement of Fig. 1 the supplementary tank 1 6 is filled, once the engine has started, in any convenient manner.

In the arrangement shown in Fig. 2 the starting aid 1 5 is supplied with fuel directly from the engine system, the fuel flowing by way of a solenoid operated on/off valve 22 and a pressure regulator 23. These two components can be mounted in the same housing or can be replaced by a motorised pump which includes its own pressure regulator. In this example the resistor 24 is a tapped resistor and for controlling the on/off valve the resistor and the starting aid, a control box 25 is provided which in the particular example, is supplied with a temperature signal by a temperature sensor 26. The sensor 26 may be responsive to the engine temperature so that the starting aid is not brought into operation when the temperature is above a predetermined value or it may be responsive to the temperature of the starting aid.

The control box upon closure of the switch 18 will, if the temperature is below the predetermined value, effect opening of the valve 22 and the supply of current to the starting aid 1 5. Initially the flow of current will be high to achieve rapid heating of the heating element but thereafter a portion or both portions of the resistor 24 will be switched into circuit to reduce the current flowing in the heating element. Again the heat dissipated in the resistor 24 will be carried away by the fuel flow to the engine. The control box will include switches shown diagramaticaliy in the drawing, to short circuit or otherwise the portions of the resistor and the switches may be operated by a timer forming part of the control box or they may be controlled in accordance with the temperature signal where the sensor 26 is responsive to the temperature of the starting aid. The control box may also be arranged to maintain the starting aid in operation when the switch 1 8 is opened following starting of the engine. In this case the control box will also be responsive to the voltage of the accumulator which when the starting motor is deenergised, will rise substantially.

It will be understood that the forms of starting aid and fuel supply systems in the two examples can be interchanged.

Claims

1. An internal combustion engine system including an engine having a fuel supply system and a starting aid system, the starting aid system including a starting aid of the kind having an electrically operated heating element, a resistor connected in series with said heating element, the series combination of heating element and resistor being connected in use across the terminals of a source of electric supply, said resistor acting in use to allow the heating element to reach its working temperature quickly and then acting to control the power input to the heating element characterised in that said resistor is associated with the fuel system of the engine so that the fuel flowing in the fuel system acts to remove heat from the resistor.

2. An engine system according to Claim 1 characterized in that said resistor is mounted on a fuel filter forming part of the fuel supply system and through which fuel flows to the engine.

3. An engine system according to Claim 1 characterized in that said resistor is mounted on a housing through which fuel flowing in the fuel system passes.

4. An engine system according to Claim 1 characterized in that the resistor is formed from a material having a high positive temperature coefficient of resistance.

5. An engine system according to Claim 1 characterised by switch means operable to switch in the whole or part of said resistor to control the current flow in the starting aid.

6. An internal combustion engine system comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

7. An internal combustion engine system comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.