NZ299267A - Diesel engine conversion to run on gas: well in piston and offset chamber in head - Google Patents

Description

f 14 NOV 1996 " PATENTS FORM NO. 5 Fee No. 4: $260.00 PATENTS ACT 1953 COMPLETE SPECIFICATION After Provisional No: 299267 Dated: 30 August 1996 Gas Converted Internal Combustion Engines i/WE Transport Fuel Systems Limited, a New Zealand company of 5/179 Harris Road, East Tamaki, Auckland, New Zealand hereby declare the invention for which <E7We pray that a patent may be granted to ine/us, and the method by which it is to be performed to be particularly described in and by the following statement: 29 9 2 6 Z.

GAS CONVERTED INTERNAL COMBUSTION ENGINES Technical Field Petrol and diesel combustion engines can be converted to run on gas with appropriate modifications.

Diesel engines, although initially more costly than equivalent petrol engines are acknowledged as having a longer life and lower maintenance costs and this is considered to be an appealing factor in high use situations.

The conversion of petrol engines to gas requires no substantial engine modifications however the conversion of diesel engines does necessitate substantial modification to the cylinder head of the engines as there is a requirement to convert from a pressure ignition system, to a spark ignition system and compression ratio changes may be required. The provision of a speed governing system is also desirable.

It is an object of the present invention to provide a method of and means by which a diesel engine can be converted to run on gas.

Further objects and advantages of the present invention will become apparent from the ensuing description which is given by way of example. disclosure of invention According to the present invention there is provided a method of converting a diesel engine to run on gas comprising replacing or modifying the cylinder head to increase the size of the combustion chamber and to provide for spark ignition, the conversion including 29 9 creating a combustion chamber defined by a cavity within the crown of the engine piston and an adjacent off set cavity in the cylinder head.

The off-setting of the cavity in the cylinderhead can provide a partial overlap between the cavity in the cylinder head and the cavity within the crown of the engine piston.

The overlap between the cavity in the cylinder head and the cavity in the crown of the piston can be less than the width of the cavity in the cylinderhead.

The overlap between the cavity in the cylinderhead and the cavity in the crown of the piston can be approximately equivalent to one third of the width of the cavity in the cylinderhead.

The method can be applied to a single or multicylinder engine.

The method may further include providing ignition and governing means which in combination controls the gas valve for fuelling the engine to limit engine speed.

According to a further aspect of the present invention there is provided a converted piston engine of the type described herein, having a combustion chamber defined by a cavity within the crown of the engine piston and an adjacent off-set cavity in the engine cylinder head.

The off-setting of the cavity in the cylinderhead can provide a partial overlap between the cavity in the cylinderhead and the cavity within the crown of the engine piston.

The overlap between the cavity in the cylinderhead and the cavity in the piston can be less than the width of the cavity in the cylinder head. 29 9 2 67 The overlap between the cavity in the cylinderhead and the cavity in the crown of the piston is approximately equivalent to one third of the width of the cavity in the cylinder head.

The converted piston engine wherein can have one or more cylinders.

The converted piston engine can include ignition and governing means which in combination control a gas valve for fuelling the engine and limiting engine speed.

The cavity in the crown of the piston can be of the so called omega configuration.

The cavity in the cylinderhead can be substantially semi-spherical.

Brief Description of Drawings Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1 is a diagrammatic sectional view of a piston block and modified cylinder head of an engine in accordance with the present invention, and Figure 2 is a diagrammatic top view of the arrangement of figure 1, and Figure 3 of the drawings illustrate the overlap of a cavity of the engine cylinderhead with the cavity in a engine piston, and Figure 4 is a schematic drawing illustrating aspects of governing and ignition system for the modified engine of figures 1 and 4 figure 2 and 3, and Figure 5 is a schematic diagram of the speed governor output and gas valve arrangement of the present invention.

Best Modes for Carrying out the Invention With respect to figures 1 and 2 of the drawings an engine modification in accordance with the present invention comprises replacing or modifying the cylinder head generally indicated by arrow 1 to provide an enlarged combustion chamber generally indicated by arrow 2 defined by the crown 3 of piston 4 and a cavity 5 in the cylinder head 1.

A chamber 6 provides a seat for a spark plug 7 adjacent the cavity 5 and conventional inlet and outlet valves 8, 9 are provided. The cylinder head is provided with a cooling jacket which in part is indicated by numeral 10.

The drawings illustrate that the cavity 5 in cylinder head 1 is substantially semi-spherical and (in the example illustrated) overlaps an "Omega" type cavity 11 in the crown 3 of the piston 4. The shape and size of the cavities 5, 11 may vary and the illustrated shapes are by way of example only.

With respect to figure 3 of the drawings in a converted engine in accordance with the present invention the perimeters of the cavities 5, 11 in the cylinder head and piston crown of the converted engine are illustrated.

Better combustion has been achieved when cavity 5 of width D overlaps cavity 11 by a distance Dl, which is less than half the width D, preferably Dl, being approximately * one third of D. r- c ir! v' v. D 1 fi 29 9 2 67 With respect to figures 4 and 5 of the drawings one possible form of governing and ignition system of the present invention is illustrated. The system comprises an engine speed and flywheel position sensor 20, a speed to voltage converter 21, a speed governor output device 22, a vacuum advance adjustment means 24, a speed advance adjustment means 25.

The speed governor output means 22 controls gas valve 23, and the means 24, 25 are communicable with ignition output means 26, the engine ignition coil of spark plug(s) 27.

Speed governor output device 22 records a speed voltage and a comp irator 28 communicates with a relay device to control a gas valve 22 via a solenoid, and thus gas input is controlled by the governor device.

International emission regulations call for the mandatory use of catalytic converters with combustion engines.

Carbon monoxide within gases reaching converters must be kept within certain levels over a range of conditions. Conventionally these levels are achieved using electronic control systems interposed between the fuel supply and the engine combustion chambers. The fuel burning efficiency of a converted engine described is such that no such electronic control means is required to control carbonmonixide levels.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof, as defined in the appended claim. *

Claims (14)

WHAT WE CLAIM IS: 2®926y

1. A method of converting a diesel engine to run on gas comprising replacing or modifying the cylinder head to increase the size of the combustion chamber and to provide for spark ignition, the conversion including creating a combustion chamber defined by a cavity within the crown of the engine piston and an adjacent offset cavity in the cylinder head, and characterised in that the off-setting of the cavity in the cylinder head provides a partial overlap between the cavity in the cylinder head and the cavity within the crown of the engine piston.

2. A method as claimed in claim 1 wherein the overlap between the cavity in the cylinder head and the cavity in the crown of the piston is less than the width of the cavity in the cylinder head.

3. A method as claimed in claim 2 wherein the overlap between the cavity in the cylinder head and the cavity in the crown of the piston is approximately equivalent to one third of the width of the cavity in the cylinder head.

4. A method as claimed in any one of claims 1 to 3 applied to a single or multicylinder engine.

5. A method as claimed in any one of claims 1 to 4 including providing ignition and governing means which in combination controls the gas valve for fuelling the engine to limit engine speed.

6. A gas fuelled internal combustion engine having a combustion chamber defined by a cavity within the crown of any engine piston and an adjacent off-set cavity in an engine cylinder head, wherein the off-setting of the cavity in the cylinder head provides a partial overlap between the cavity in the cylinder head and the cavity within the crown of the engine piston. r C F. I V 5 Q,r. Property u.va 1 o FW 1 9

7. A converted piston engine as claimed in claim 6 wherein the overlap between the cavity in the cylinder head and the cavity in the piston is less than the width of the cavity in the cylinder head.

8. A converted piston engine as claimed in claim 7 wherein the overlap between the cavity in the cylinder head and the cavity in the crown of the piston is approximately equivalent to one third of the width of the cavity in the cylinder head.

9. A converted piston engine as claimed in any one of claims 6 to 8 wherein the engine has one or more cylinders.

10. A converted piston engine as claimed in any one of claims 6 to 9 including ignition and governing means which in combination control a gas valve for fuelling the engine and limiting engine speed.

11. A converted piston engine as claimed in anyone of claims 6 to 10 wherein the cavity in the crown of the piston is of the so called omega configuration.

12. A converted piston engine as claimed in any one of claims 6 to 11 wherein the cavity in the cylinder head is substantially semi-spherical.

13. A method of converting a diesel engine to run on gas substantially as herein described with reference to the accompanying drawings.

14. A converted piston engine substantially as herein described with reference to the accompanying drawings. TRANSPORT FUEL SYSTEMS LIMITED by its Attorneys END OF CLAIMS ' • r 0 E 1 V n 0 ProiHsviy o.Ii ?« 8