GB2092224A - Fuel injection and spark ignition timing devices in i.c. engines - Google Patents

Abstract

A piston 5 mounted in the cylinder head 1 is moved by cylinder compression and combustion pressure to operate a fuel injection pump piston 7 or trigger spark ignition, after an engine speed variable time delay, at electrodes (21), Fig. 2 (not shown), formed in a screw-in unit (25) containing the pressure operated piston (20). The delivery of the pump piston 7 is adjustable by varying the permitted stroke of a pumping chamber piston 9 by means of an hydraulically operated piston 11 under accelerator pedal control. Connections 16, 17, 18, 19 provide coolant or lubricant inlets and outlets. The injection pump may provide pilot and main injections and injection may occur through the pressure operated piston (30), Fig. 3 (not shown). <IMAGE>

Description

SPECIFICATION Anti-knock fuel injection and ignition device for internal combustion engines BACKGROUND INFORMATION AND PURPOSE OF INNOVATIONS Present internal combustion engines, whether diesel or petrol go to great complication and expense in the former case, in order to synchronise the ignition and combustion processes in each cylinder, with the stroke positions of the several pistons. With many engine applications, particularly those concerned with transport, these synchronisations need to be continually adjusted to accommodate the continually changing relations between engine load and required speed and acceleration etc. This adds further to the cost of complication, particularly where some of those adjustments can be and are made automatically since they are only derivative from the basic driver/vehicle requirement.

The usual way of achieving these secondary synchronisations of injection a ignition timing, has been via a tortuous path from piston to crankshaft, to gearing and camshafts, fuel pumps and injectors and/or to governors and spark generators a distributors. In the petrol engine, the speed sensitive governors are needed to modify the synchronisation before the spark is delivered to the cylinder that was the start of that tortuous path and chain of apparatus. Such timing control with injection has been further complicated in diesel engines.

In general these ignition control systems are largely concerned with relating the combustion pressure to the most advantageous part of the piston stroke so that neither excessive stress and "knock" occurs, nor is the combustion applied too late in relation ta the instantaneous mechanical advantage and velocity ratio of the piston/crankshaft position and speed.

The object of the present inventions is to use and directly translate this very cylinder pressure to control and power the injection and ignition timing in each cylinder itself, and so eliminate much costly apparatus for translating revs. and crankshaft position into instantaneous combustion pressure assessment.

Combustion chamber expansion devices to simply allevaite "knock" and excessive stresses in internal combustion engines are the subject of much prior art. The similar concepts involved in the inventions here are however more concerned with the acceleration dynamics of the "expansion piston" movement relative to the speed of crankshaft rotation. Not only is the expansion piston movement here subject to external (driver) control, but in turn is itself designed to also control combustion pressure advance and retard, and advance and retard of the point of ignition.

For a simple combustion chamber expansion device, one can envisage a very strong spring inside the engine's piston, and which thus allowed the lightest possible moving mass of this main piston to be thus "decoupled" from another piston-type slide inside it and which held the "con-rod." Thus the essentially rapid acceleration of expansion of the combustion chamber could then be followed by the most rapid return of the spring's energy to the engine. The need for such rapid return being due to the speed of the piston expansion stroke with its consequent speed of loss of driving pressure.

The same principles are easier to achieve by using a separate piston in the cylinder head and this thus makes it accessible to external control and for activating fuel injection and ignition, and thus to speed control.

DESCRIPTION Existing methods of speed and ignition control such as "fuel by-pass" or air intake restriction, with fuel metering may be used in the diesel case, and normal carburettor and throttle methods in the patrol case. Accordingly FIG. 1 is a diagrammatic representation of an embodiment of the basic invention for a diesel engine, and in which 1 is the engine piston, 2, the cylinderhead, 3 is the "con-rod," 4 the exhaust valve, 5 the "expansion piston" and 6 its pressure spring, 7 the body of the "expansion piston pump unit," 8 is the fuel inlet pipe with valve and union, 9 the fuel outlet from its union and valve, 10 is the fuel pump piston and 11 the fuel injection nozzle.

This basic device needs some explanation before the context of the proposed control devices of Figs. 3 a 4 can be fully appreciated. IE.

1. In the case of the Diesel of Fig. 1, if the air intake is restricted (with or without 'blower'), and the compression pressure is thus reduced, then the firing point is "automatically" retarded thereby, since the- expansion piston only opens when the pressure reaches a pre-determined level, which will now be later in the stroke.

2. When that level of pressure is reached however, and a small injection made, the combustion causes further opening of the expansion piston and more fuel is thus injected. IE there is in effect a "pilot injection," as is known to be advantageous.

3. In the case of less restriction of air intake, greater compression pressure ensues, and both earlier pilot and main injection occurs and also more movement of the expansion piston cause greater fuel injection quantity.

This basic device leads to further possibilities of control which are to be described. Firstly however, the simpler petrol engine ignition device is schematically depicted in Fig. 2, in which 25 is the body of the screw-in unit which replaces both spark plug and the ignition system.

20 is the pressure activated piston and 21 are the spark electrodes equivalent to the normal spark plug. 24 is the spark producing unit which could be of the piezo-electric type for instance.

Increased mixture intake as the throttle is opened, causes greater pressure in the combustion chamber and an earlier point at which piston 20 triggers ignition via the unit 24.

Since further control of ignition timing in relation to engine revs. will be required, a variable electronic time delay unit 22 can be used with the connections 23 to a simple electric rev. sensor.

The unit 22 translates the frequency of the impulses from the rev. counter, to time delay of the spark. This might also be done within the unit on the basis of the frequency of the expansion piston impulses, and thus eliminate the need for the external control connections 23.

In all these applications of diesel or petrol engine devices, an electrical pressure sensor in the cylinder head or in the particular unit itself, may be used to activate an electronic frequency sensitive device to act as rev. counter for any such control mechanism. Such electrical pressure sensor may of course be replaced by the expansion piston itself to provide the necessary impulses.

In fact, for independant use of such control on diesel engines also, the lower part of the unit with expansion piston 5 of Fig. 1, could also be of similar smaller diameter so that there was little effect upon the size of the combustion chamber.

Returning to the mechanical dynamics of control made possible by the basic "expansion piston pump" device of Fig. 1, Fig. 3 shows a basic embodiment of a speed control device in schematic form.

An expansion piston 30 with its pressure spring, is mounted in a body unit 31, 32, and 33 is a secondary piston held down via the spring 34, the pressure from which is varied by the ram 35 that is controlled by the externally operated cam 36, which in turn may be controlled by the accelerator pedal. 37 is the fuel inlet valve and union, and 38 is a fuel injection nozzle and valve mounted concentric within the compression piston 30.

If the cam 36 is fully open as shown in Fig. 3, then the piston 33 will be largely free to move upwards when the expansion piston is compressed, and so little or no fuel will be injected via its nozzle 38.

If the cam closes the spring 34 completely, then the maximum amount of fuel is injected at the most advanced time for ignition. When the cam is turned so as to release the pressure on the piston 33, this can then not only move upwards so as to reduce the amount of fuel being forced into the injection nozzle, but at the same time will increase the motion of piston 30 to reduce compression in the cylinder, and, due to the separate motion of piston 33, the ignition point will also be retarded by the time taken for this motion to cease. Thus a smoother slow run is obtained, as also at high RPM a higher compression, and more advanced ignition occurs with more thrust, as is required. If this is combined with blower or air intake throttle control, a very versatile diesel engine might be designed.

Finally the pilot injection efect already referred to, might be made more consistent if a graded spring or springs are used for the expansion piston. The same pilot effect could be achieved by having two "expansion" pistons instead of one.

These could be concentric in order to save both space and cost, and in which case the injection nozzle 38 would be replaced by the arrangement in Fig. 1, and a small, maybe free-floating piston, "resistively" air damped via a small orifice to the cavity behind the piston 30, Fig. 3. This "engine idling" piston would be self-returning as the piston 30 closed and the cylinder pressure dropped below that of the fuel chamber 39.

SECONDARY CONSIDERATIONS OF FUNCTION It has been described above how increased throttle or air intake leads to more movement of the expansion piston and thus more fuel injection and advance of ignition for higher rev. working. At very high revs. however the inertia of the expansion piston could begin to counter the fuel increase, ignition advance, and, depending largely on the mass of this piston there could even be a net overall static dispiacement over the whole cycle at very high revs.

To counter this, the fuel chamber with piston 33 (Fig. 3) could provide a mechanical advantage of pressure via a larger piston face on the rear of the expansion piston. A iarger movement path of the piston 33 could then accommodate large movements of the expansion piston at low revs, whilst the inertia of this same longer piston 33 at high revs. would be able to counter the lower displacements of the expansion piston where its inertia at high revs. could so reduce the amplitude of its oscillations. Likewise the above mechanical advantage could be designed to eliminate any static displacement of the main compression piston, since the force of piston 33's return spring 34 would be multiplied accordingly.

Fig. 4 schematically depicts such a construction and also includes some working refinements to demonstrate some possible avenues of practical development for the basic concepts. Accordingly Fig. 4 shows body parts 2, 3 a 4 mounted in a cylinder head 1. 5 is the "compression piston" and 6 its pressure spring. 7 is the larger dia. fuel pump piston made in a comparatively heat resisting material or with such a lining on its upper surface.

8 is the fuel chamber, and 9 the longer secondary piston with its control spring 10. 11 is the controlling ram, which is here hydraulically operated via the union 12 which can be fed from the accelerator pedal. 13 a 14 are fuel inlet and outlet valves respectively, and 1 5 are fuel by-pass ports for further control if needed for some applications. 16 8 17 are oil inlet and outlet unions for lubrication and/or cooling purposes. 18 a 19 are "semi-Venturi" type inlet and outlet vent type values for air cooling flow round the lower end of the compression piston. Such air outlet might be shrouded and collected for some preheating purpose. 20 is a cylinder vent placed low to "cushion" large travel of 9 by air trapped between 9 all.

It will be seen that there are also considerable maintenance advantages in this whole concept.

Most of the ancilliary engine functions that depend on small mechanisms which are usually the object of most service attention. Such as fuel supply and ignition and the synchronisation mechanisms associated therewith are here housed in one simpler single unit which is nearly as readily replaceable as a spark plug and air filter.

Furthermore the concept of function control by basic dynamics that depend mainly upon the almost unalterable mass of simple moving parts, should lead to more trouble-free performance. The fact that each cylinder incorporates its own system of control, will further reduce the factor that one single component failure can bring a vehicle to a halt.

Claims (6)

1. A member or members operated by pressure in the cylinder-head of an internal combustion engine, which member(s) controls or operates and powers fuel injection and/or supply, and/or ignition, without any mechanism connected via the crankshaft.

2. A member or members as in "1", which can also move to allow effective expansion of the combustion chamber volume.

3. A member or members as in "1" or "2", where the control or operation of injection and/or ignition, can also be accompanied by control from a source external to the cylinder, whethersthat source is driven by the engine or by a source external to the engine including a manual or other driver-operated control.

4. A member or members as in "1", "2" or "3" which exercises control over enginespeed a/or acceleration a/or toraue.

5. A member or members as in "1", "2", "3" or "4", which is in the form of a piston in the cylinder head, and will retract at a pre-determined cylinder pressure, and in so doing will act to force fuel into the injection nozzle in the cylinder head, or to operate an ignition device.

6. A position as in "5", which itself is controlled by its own dynamic qualities of "mass", "compliance" of associated spring members, and similarly associated "mechanical resistance" factors, and similar associated members included for such purpose, but also by factors external to the cylinder combustion chamber and these devices, such external factors including engine speed sensiti,/e devices and manual type controls.