AU664804B2

AU664804B2 - Vaporised gas flow control

Info

Publication number: AU664804B2
Application number: AU64822/94A
Authority: AU
Inventors: John Dillon Upham; Dan Vrubel; Victor Vrubel
Original assignee: Upham Ronda
Current assignee: Upham Ronda
Priority date: 1993-08-06
Filing date: 1994-06-17
Publication date: 1995-11-30
Anticipated expiration: 2014-06-17
Also published as: AU6482294A

Description

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r" 664804 PATENTS ACT 1990 COMPLETE SPECIFICATION FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification Lodged: Accepted: Lapsed: Published: Priority: Related Art: 00 0 0 0 0 0 04 o4 4 ft a 4 4 4 4 4 4 4 4 TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: Victor Vrubel Dan Vrubel 11 Drake 11 Drake Avenue CARINGBAH NSW 2229 Avenue CARINGBAH NSW 2229 Actual Inventor: SAME AS Address for Service: 11 Drak Complete Specification for the invention entitled:

APPLICANTS

:e Avenue CARINGBAH NSW 2229 VAPORISED GAS FLOW CONTROL The following statement is a full description of this invention, including the best method of performing it known to me: 1 This invention relates to internal combustion engines. More particularly although not exclusively it provides an improved apparatus for enabling such engines to run on vaporised gaseous fuel such as a mixture of propane and butane gases commonly known as the Liquefied Petroleum Gas (LPG), when it is supplied to the engine under a high positive pressure in a gaseous form and not in the liquid form.

Throughout the following description the vaporised gaseous fuel shall be referred to as the "vaporised gas".

At present internal combustion engines converted for operation on vaporised gas require the back fitting of carburettor-like devices. For example it is known to control the flow of vaporised gas by means of devices that measure the vacuum in the engine intake manifold and operate a valve that allows the entry of vaporised gas into the engine according to the value of the vacuum. It is also known to control the flow of vaporised gas by means of a device that operates a valve allowing the entry of vaporised gas in :i accordance with the flow rate of the air entering the intake manifold. This is typically achieved by a diaphragm placed in the way of the entering air that oo:i «moves according to the air flow rate and thus controls the entry of vaporised gas into the engine.

I. .o In such systems the vaporised gas flow control relies 0 on monitoring of a single parameter only such as vacuum or air flow rate and takes no account of external loads on the engine that may cause it to require more or less of vaporised gas for smooth operation and constant idle speed. More importantly these prior art systems of vaporised gas flow control are inherently slow and exhibit a significant lag in 2 I I response to the engine fuel demand. This is because such systems work under negative pressure, the method relies on monitoring vacuum and is also limited by the inertia of moving parts of the vaporised gas control system and restrictions in the air flow presented by the diaphragm and other parts.

It is an object of this invention to ameliorate the aforementioned disadvantages and accordingly this invention discloses an apparatus for enabling an internal combustion engine to operate on a vaporised gas, said apparatus comprising a vaporised gas metering means for connection to a pressurised source of said vaporised gas and adapted for fitting into the air intake duct of said engine, a microcontroller which in use of the apparatus produces phase shifted control signals for the vaporised gas metering means whereby said vaporised gas metering means may be operated to selectively control the amount of vaporised gas entering said air intake stream in accordance with the signals from the microcontroller.

Preferably said vaporised gas metering means is adapted for fitting into the air intake duct above the throttle valve and for injecting said vaporised ,gas into the centre of the duct in the direction of air flow.

4 4The currently preferred embodiment of this invention 50 will now be described with reference to the attached C, drawings in which: Figure 1 shows a block diagram of an apparatus according to this concept connected to a system for fuelling internal combustion -engines with vaporised gas, 3

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-r ii t i. I PP~1Ci~Zi~i~a.~-ii~i~~~ -^i~~il Figure 2 Figure 3 Figure 4 is a cross-sectional view of the metering means looking along the direction of air flow in the duct, is a cross-sectional view of part of the metering means along direction A of Figure 2, is a view of part of the metering means along a direction opposite the direction of air flow in the duct, and 6 are cross-sectional views along the line B-B of Figure 4.

Figures 5 Referring first to Figure 1 the apparatus may basically be connected to a pressurised liquefied gaseous fuel tank 1 which supplies liquefied gaseous fuel through conduit 2 to a solenoid activated safety valve 3. The liquefied gaseous fuel then enters a vaporiser/pressure regulator 4 which changes it to vaporised gas at a o0 controlled pressure of for example 200 kPa. The 0 vaporised gas then flows through a second safety valve S and via line 5A to an apparatus comprising the metering 0 0o o25 means (formed by a metering valve 6 and a stepper motor o o7) and a microcontroller 12. A metered quantity of vaporised gas may thus be injected into the middle of the air intake duct 8 upstream of throttle valve 9 as shown. The vaporised gas exits valve 6 in the direction of air flow and mixes with it for distribution through 0,0 the intake manifold 10 to engine 11. The vaporised gas control microcontroller 12 according to this invention a produces signal for controlling the stepper motor 7 in combination with the vaporised gas metering valve 6.

4 i, pr i p i As best shou in figures 2 to 6 the metering valve 6 may comprise a barrel 16 which connects to vaporised gas supply line 5A and extends radially into the centre of j the air intake duct 8 from a housing 17. The end 18 of the barrel is closed off but a transverse slot 19 is cut Spartly though the circular wall of the barrel a short distance back from the end. Within the end section of barrel there is a rotatable head 20 also with a slot 21.

This slot 21 in accordance with the angular position of the head aligns with slot 19 in varying degrees to al].ow an infinitely graduated vaporised gas flow control from the interior of the barrel to the air duct (see arrow A) between the fully open position of Figure 5 to the fully closed position of Figure 6. The angular position of the head is controlled by any suitable type of commercially i available stepper motor 7 through shaft 22. Any suitable type of bearings may be used to support the head 20 and opposite end of the shaft 22 where it couples to the motor 7.

The above described arrangement has been found to provide a high speed and extremely accurate mixture control response.

f 4 0 The stepper motor controlling the metering valve has to be equipped with a provision for setting its initial 4position in relation to the fully closed position of the metering valve. The programmed microcontroller (PMC) is then capable of calculating the accurate position of the stepper motor (and thus the metering valve) at any time from the information about its initial position and the number of step signals sent to the stepper motor.

The stepper motor currently proposed for controlling the metering valve according to this invention has 200 full

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pr steps per revolution. The maximum usable working angle of the metering valve is 180 degrees however quick changes of valve position require the use of a 90 degree angle of operation only. This results in only 50 steps being availalle for control of the metering valve throughout its full range from closed to fully open position. Such limitation in precise control has been overcome by the design of PMC which allows the control of the stepper motor in microstep mode. For higher accuracy the stepper motor/metering valve assembly can be adjusted in say one of 20 positions between each two full steps. Microstep mode can be achieved for example by vibrating between two nearest steps with different time ratio, in this example between 1:19 to 19:1.

To reach high speed and accuracy the stepper motor operates in full step mode for quick changes of valve position and in microstep mode for fine adjustments only. Because each metering valve is manufactured with slightly differing tolerances it is necessary to have the means of adjusting the limits of its opening range. The PMC preferably directly controls all safety (shut off) valves. Rotational speed of the engine is calculated at all times and when the engine stops the power is cut to close the safety valves.

It will thus be appreciated that this invention at least in the form of the embodiment described provides a novel and useful improvement to existing vaporised gas installations on internal combustion engines. Clearly however the example disclosed is only the currently preferred form of this invention and a wide variety of modifications may be made which would be apparent to a person skilled in the art. For example the configuration of the metering means and functions of the PMC may all be changed according to design preference.

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Claims

1. An apparatus for enabling an internal combustion engine to operate on a vaporised gaseous fuel supplied to the engine under high positive pressure, said apparatus comprising firstly a vaporised gas metering means for connection to a pressurised source of said vaporised gaseous fuel and adapted for fitting into the air intake duct of said engine, the metering means comprising a barrel which is connectable to a vaporised gaseous fuel supply line from said source of vaporised gaseous fuel and which extends from a housing into the air supply duct, the operative end of the barrel including a slot through the wall thereof, and a slotted head rotatable within said barrel by a stepper motor so that the slot in said head aligns with the slot in said barrel in varying degrees to allow a graduated flow of the vaporised gaseous fuel from the barrel into the air intake duct, and secondly a microcontroller which in use of the apparatus produces phase shifted control signals for the vaporised gas metering means whereby said vaporised gas metering means may be I: operated to selectively control the amount of vaporised gaseous fuel entering said air intake duct in accordance with the signals from the ;microcontroller.

2. The apparatus as claimed in claim 1 wherein said vaporised gas metering means is adapted for fitting into the air intake duct upstream of the throttle valve and for injecting said vaporised gaseous fuel into the centre of the duct in the direction of air flow. Y- 7 c~ r

3. The apparatus as claimed in any one of claims 1 and 2 wherein the stepper motor is activated to rotate said head in accordance with said control signals from the microcontroller.

4. The apparatus as claimed in claim 3 wherein the stepper motor is linked to the slotted head by means of a shaft extending the interior length of the barrel.

The apparatus as claimed in any one of claims 3 and 4 wherein the microcontroller controls the stepper motor in a full step mode for quick changes of the valve position and in a microstep mode for fine adjustments only.

6. The apparatus as claimed in any one of claims wherein said vaporised gaseous fuel is LPG, when it is supplied to the engine in a gaseous form.

7. A motor vehicle fitted with apparatus as claimed in Victor Vrubel and Dan Vrubel i r a ABSTRACT This is an apparatus for high speed and accurate flow control of vaporised gaseous fuel supplied to an internal combustion engine under a high positive pressure. The apparatus comprises a vaporised gas metering means for connection to a pressurised source 1 of said vapourised gaseous fuel and adapted for fitting into the air intake duct 8 of the engine. The vaporised gas metering means consists of a rotatable proportional metering valve 6 and a stepper motor 7. The valve 6 is rotated directly by the stepper motor 7, controlled by a programmable microcontroller 12 which produces phase shifted control signals to operate the stepper motor in either a full-step or micro-step mode. The vaporised gas metering means may thus be operated to selectively control the amount of vaporised gaseous fuel entering the air intake stream in accordance with engine fuel demand. ii' I"1 9 O