NZ205929A - System for operating 1.c. engine on combination of liquid and gaseous fuels - Google Patents

Description

r0flH 5- NEW ZEALAND S.9.

Re^gCf'.) 2 05 92 9 Fei>: /flO.OO Priority Date(s): . . «2&, Complete Specificotion Filed: .'fV.'.Q.&t Class: . &}&£ . F.wpA /.<&.

Publication Date: P.O. Journal, Wo: LI 2 NOV *t986 Insert number of Provisional Speci fication( s) (i f anv) and date(s) of filing; otherwise leave blank.

PATENTS ACT 195 3 Number: Date: COMPLETE SPECIFICATION Insert Title of Invention.

Insert full name, ful I street address and nationality of (each) applicant.

METHOD OF OPERATING ENGINE USIMG GASEOUS FUEL IN COMBINATION WITH LIQUID FUEL I/WE TAKESHI IKEDA, e Japanese citizen of ?-r,-P.-213 , Sfinnn Ctak.li , Tokyo, Japan hereby declare the invention for which I/we pray that a patent may be granted to me/us and the method by which it is to be performed, to be particularly described in and by the following statement:- Indicate if following page is numbered '1(a)' 1 - This invention relates to a spark ignition internal combustion engine and a method of operating the same wherein a liquid fuel such as gasoline, methanol or ethanol is burnt in combination with gaseous fuel such as propane, methane, acetylene gas or hydrogen.

Presently, gasoline engines are a main power source all over the world. Some countries confronted with a difficulty in obtaining petroleum are formulating an energy policy to promote the use of gasohol which is a blend of gasoline and alcohol. However, since gasohol contains more than 85% gasoline, a fundamental solution can not be achieved by this policy and, in addition, it is difficult in practice to operate ordinary gasoline engines using other fuels.

At present some vehicles are modified to be fuelled with LPG to permit engines to be operated with liquid fuel other than gasohol. Since alcohol, for example, has a smaller calorific value than gasoline and they have different characteristics from each other, it is also difficult to employ pure alcohol in conventional gasoline engines.

This invention has been proposed to solve problems arising out of diversification of energy sources as a result of shortage ot petroleum resources. The invention provides an engine and a method of operating the same comprising: a liquid fuel supply apparatus connected to an inlet air passage of the engine for supplying liquid fuel; a gaseous fuel supply apparatus connected to the inlet air passage for supplying gaseous fuel; at least one said fuel supply apparatus comprising an air/fuel ratio adjustment device which is adapted to adjust the overall air/fuel ratio of a mixture supplied from 205929 both fuel supply apparatuses to a desired value.

An ODject of this invention is to provide an engine and a method of operating the same in which at least one kind of liquid fuel selected from gasoline, methanol, ethanol, etc. is used in combination with gaseous fuel having a relatively high calorific value, such as natural gas, LPG, hydrogen or acetylene gas, thus resulting in good fuel consumption and excellent performance. Furthermore when a mixture forming device according to this invention used for supply of liquid fuel as constructed to make it possible to obtain the air/fuel ratio suitable for operating conventional engines fuelled with gasoline only, the engine can be operated using liquid fuel only in a similar manner to conventional gasoline engines.

Liquid fuels such as gasoline and alcohol and gaseous fuels such as natural gas, acetylene gas, hydrogen and LPG, which are used in this invention, have calorific values as shown in the following Table 1.

Therefore, using this invention, even when using a fuel of lower carolific value such as alcohol, the calorific value can be raised up to a level of gasoline by mixing gaseous fuel of a higher calorific value with inlet air in a given ratio. At the Table 1 Fuel Lower Calorific Value (cal/g) Gasoline Alcohol (ethanol) ALcohol (methanol) LBS (propane) Methane gas Acetylene gas Hydrogen gas ca. 10,500 6,400 4,800 11,080 12,000 11,500 28,700 205929 same time other characteristics such as the ignition timing are adjusted so that the engine may be operated under operating conditions similar to those prevailing when gasoline is used. It is also possible to increase the calorific value to a level higher than that of gasoline, and hence to obtain greater power, by mixing gaseous fuel of a higher calorific value with inlet air in the increased ratio.

Further, this invention can be applied to engines of the so-called fuel injection type wherein fuel is injected in accordance with inlet air weight as well as engines using carburettors.

The results of study of the relationship between calorific values of liquid fuel and gaseous fuel when applied to motor vehicles equipped with conventional gasoline engines will be described hereinafter.

By means of tests in which alcohol and various gaseous fuels are supplied in different mixture ratios, it has been ascertained that the best fuel consumption efficiency is attained when the calorific value is similar to that of gasoline, and that when a larger amount of gaseous fuel with a higher calorific value is supplied to increase the calorific value, power is correspondingly increased.

A fuel supply system used in a conventional gasoline engine is so constructed that gasoline is mixed with inlet air in a given ratio. It is practicable, therefore, to supply alcohol fuel using the fuel supply system for gasoline, and gaseous fuel using a separate system having a given ratio of gaseous fuel to inlet air. When the fuel supply system of a cconventional gasoline engine is employed directly for the *\' \. 205929 supply of alcohol, since gasoline and alcohol (ethanol) have different specific gravities, i.e. about 0.75 and 0.79 respectively, the fuel supply system which is capable of supplying gasoline and alcohol in equal volumes (i.e. in the same air to fuel ratio) will supply them in the weight ratio of 1.0 5 alcohol to 1.00 gasoline. As shown in Table 1, since the calorific value of gasoline is 10,500 cal/g compared to 6,4,00 cal/g for alcohol (ethanol), and since the calorific value of 1.05 g alcohol is 6,720 cal (6,400 x 1.05), the difference between the calorific value of lg of gasoline and the same volume of alcohol (1.05g) is 3,780 cal (= 10,500 - 6,720) which is to be compensated for by gaseous fuel. Table 2 shows the kind and weight of various gaseous fuels which are used in combination with alcohol (ethanol) fuel to compensate for the lack in the calorific value thereof and hence to attain a calorific value which is substantially equivalent to that of gasol ine.

Tfthl f ? (A) (B) (A)+(B) Liquid Fuel Weight (g) Gaseous Fuel Weight (g) Total Tbtal C&L. (A): (B) Weight (g) (Cal/g) Ratio Gasdine 1.00 - - 1.00 # 10,500 Ethanol *1.05 Propane gas #0.34 #1.39 # 10,487 #76:24 Ethanol #1.05 Methane gas #0.31 #1.36 # 10,440 #77:23 Ethanol #1.05 Acetylene gas #0.33 #1.38 #10,515 #76:24 Ethane! # 1.05 fydrogen gas # 0.13 # 1.18 # 10,451 # 89:11 Table 3 shows the kinds and weights of various gaseous fuels necessary to attain the equivalent air/fuel ratio. 205929 W?3 (A) (B) (A)+(B) Liquid Fuel Weicjit (g) Gaseous Fuel Weicfrt (g) Total Air Ratio* (A): (B) Weight (g) Equivalent Ratio Tb Gasoline Gasoline 1.00 Ethane! * 1.05 Ethanol * 1.05 EthandL * 1.05 Ethanol r 1.05 1.00 * 15.0 Propane gas 7*0.34 *1.39 *15.0 f 76:24 Mstfcare gas * 0.43 * 1.48 * 15.0 * 77:23 Acetylene gas * 0.42 * 1.47 * 15.0 * 76:24 fydrogen gas * 0.16 * 1.21 * 15.0 * 89:11 Inlet air weight is to be 1.5 g in each case, This invention can be applied to motor vehicles with conventional gasoline engines, without need for substantial modification, but with the following simple modifications: (1) a simple gas injection port of the kind generally used for LPG or the like is provided; (2) a small gas tank is installed in the trunk of the vehicle; and (3) a device is provided which is adapted to add a gaseous fuel in the appropriate ratio for the liquid fuel being used, and is controlled by the vehicle accelerator control to which it is connected.

This arrangement provides valuable advantages: (1) no engine design adjustments are required to change between various fuels; (2) if gasoline is on hand, it may be used; (3) if alcohol is on hand, it also may be used; (4) if both gasoline and alcohol are on hand, they may be used in any desired mixture ratio; (5) a mixture of various liquid fuels can be used without need for substantial adjustment, by selecting an appropriate I 305929 ratio of gaseous fuel to yield the overall calorific value of gasoline; (6) when using gasoline, the fuel consumption can be improved by adding gaseous fuel to yield a higher calorific value and thermal efficiency than gasoline; (7) addition of gaseous fuel facilitates starting of engines at low temperatures, such starting having been 1 considered a disadvantage attendant on the use of liquid fuels with lower calorific values; and (8) it is proven that the thermal efficiencies of alcohol and gaseous fuels are better than that of gasoline when used in an internal combustion engine.

Particular embodiments of the invention are hereunder described, by way of example only, with reference to the following drawings, wherein: Figure 1 is a schematic diagram of a first embodiment of the invention; Figure 2 is a cross-sectional view of a flow-regulating valve of the first embodiment; Figures 3 to 6 are graphs showing the results of tests carried out on vehicles incorporating the first embodiment of the invention; i Figure 7 is a schematic diagram of a second embodiment of the invention; Figure 8 is a timing chart applicable to the second ^ embodiment; Figure 9 is a schematic diagram of a third embodiment of invention; ''N *^\Figure 10 is a cross-sectional view of a strut of a 1lSEPl986yl a J -7- I 205929 - /-■' regulating valve of the third embodiment; Figure 11 is a schematic diagram of a fourth embodiment of the invention; Figure 12 is a cross-sectional view of a part of a carburettor of the fourth embodiment; Figure 13 is a schematic diagram of a fifth embodiment of the invention; Figure 14 is a cross-sectional view of a part of a carburettor of the fifth embodiment; and Figure 15 is a diagram illustrating the operation of the fifth embodiment.

A first embodiment of this invention as applied to an engine equipped with a carburettor is shown in Figures 1 and 2.

Designated at the reference numeral (1) is a liquid fuel tank, and (II) is a liquid fuel supply apparatus including a fuel supply pump (2) which has its inlet connected to the liquid fuel tank (1) through a supply passage (2') and has its outlet end connected to a carburettor (3) in an inlet air passage (4') of the engine (5).

Designated at the reference numeral (6) is a gaseous fuel tank, and (IV) is a gaseous fuel supply apparatus including a pressure regulating valve (8) which has its inlet connected to a gaseous fuel tank (6) and has its outlet connected to a nozzle (10) provided in the inlet air passage (41). The pressure regulating valve (8) is provided with a pressure adjuster (81) which is able to adjust the pressure manually or automatically.

The reference numeral (7) denotes an electro-magnetic valve O^dapted to open and close a supply passage (21') under the ^S£P1986% // -8- 205929 control of an ignition switch (III), and the valve (7) includes a stop switch (7') which allows it to be switched off as required, so that supply of fuel may be interrupted independently of actuation of the ignition switch (III).

An air/fuel ratio adjustment device (V) comprises a flow regulating valve (9) which has its outlet connected to the nozzle (10) and has its inlet connected to the pressure regulating valve (8) through a supply passage (21') and which is also connected to an inlet manifold (4) of the engine (5). The flow regulating valve (9) is provided with a pressure adjuster (9') operated manually or automatically. The numeral (411) denotes an exhaust pipe, and M'11) denotes an air cleaner.

As shown in Figure 2, the flow regulating valve (9) comprises a diaphragm (12) which is urged by a spring (11) to open a valve (13). A space (17) to the opposite side of the diaphragm (12) communicates with the inlet manifold (4) through a pipe (14). An inlet (15) of the valve (13) communicates with the pressure regulating valve (8), while its output (16) communicates with the nozzle (10).

When the engine is stopped, the electro-magnetic valve (7) . is closed. But when the ignition switch is switched on, the electro-magnetic valve (7) is opened so that the gaseous fuel is supplied to the flow regulating valve (9) after being adjusted to a preselected pressure by the pressure regulating valve (8) .

When the engine is under a light load with the throttle — valve closed, inlet air weight is small and the vacuum in the ^" inlet manifold (4) is high, whereby the diaphragm (12) is urged / _9_ y,''N against the spring (11) to close the valve (13) so as to decrease the amount of gaseous fuel supplied to the inlet manifold.

When the engine is under a heavy load with the throttle valve opened, inlet air weight is increased and vacuum in the inlet manifold (4) is reduced, whereby the diaphragm (12) is urged by the spring (11) to open the valve (13) so as to increase the amount of gaseous fuel supplied to the inlet manifold.

In the construction as described above, when the ignition switch (III) is turned ON, the electro-magnetic valve (7) is opened so that gaseous fuel flows into the supply passage (2 1 *) from the tank (6) at a pressure regulated by the pressure regulating valve (8). Thus gaseous fuel at the proper pressure is supplied to the flow regulating valve (9), where the supply of fuel is controlled by the vacuum pressure within the inlet manifold (4) to maintain the flow rate substantially in the desired proportion to inlet air. Thus controlled gaseous fuel is supplied to the inlet air passage (4') from the nozzle (10).

Liquid fuel such as methanol or ethanol is supplied to the carburettor (3) from the tank (1) through the supply passage (21) and the pump (2), thus mixing with the gaseous fuel which is also supplied to the inlet air passage (4'). The resulting fuel has both an air/fuel ratio and a calorific value substantially equal to those of a conventional gasoline and air mixture. As a result, efficiency is improved and the engine operates smoothly.

In the first embodiment, since the flow rate of gaseous fuel is controlled by vacuum pressure within the inlet manifold r 205929 (4), gaseous fuel is supplied substantially in constant proportion to inlet air and hence it is possible to maintain the mixture ratios among air, gaseous fuel and liquid fuel at an almost constant value.

The mixture ratio of gaseous fuel to air can be easily changed by adjusting the pressure regulating valve (8).

The following experiments have been carried out with a. 4-cylindered gasoline engine of 1600cc displacement using various combinations of fuels.

Experiment 1 Ethanol and domestic LPG gas were used as liquid fuel and gaseous fuel, respectively, and the ratio of ethanol to LPG by weight was varied from 88:12 to 63:37 . At the same time, the engine speed was varied between 1,000 rpm and 3,500 rpm.

Under these conditions fuel consumption measured in Km/1 was measured using a low gear only. As a result, there were obtained the data shown in Table 4. Figure 3 shows the same result in graph form. The best fuel consumption was obtained when che mixture ratio of ethanol to domestic LPG gas was 68:32 and there was no appreciable difference in driveability as compared to the use of gasoline only. 205929 Fuel Mixture Ratio Ehgine Speed (r.p.m.) Liquid : Gas 1,000 1,500 2,000 2,500 3,000 3,500 88 : 12 4.5 .6 .4 .1 .0 4.7 63 : 17 .7 .6 6.0 .9 .7 .4 7 b : 22 6.6 .9 7.0 6.7 6.6 6.3 73 : 27 6.7 6.4 7.4 7.2 7.5 7.1 68 : 32 .6 6.5 7.8 8.2 7.9 7.5 55 : 37 7.0 6.0 7.5 8.0 7.7 6.4 The result of a road running test where the engine was operated at the engine speeds 2,000 rpm and 2,500 rpm using top gear only is shown in Table 5.

N.2. PATENT OFFICE ft SEP 1984 iQ- r^in RSC'Z.'vT) 2,000 rpn 2,5(tl Fuel mixture ratio Fuel Consumption Fuel Mixture Ratio Eliel Consumption liquid s cps Kn/1 liquid : gas Kn/1 ttl : 19 17.0 85.5 : 14.5 12.5 Experiment 2 Ethanol and acetylene gas were used as liquid fuel and gaseous fuel, respectively, and the ratio by weight of ethanol to acetylene was varied from 88:12 to 67:33. At the same time, the engine speed was varied between 1,000 rpm and 3,500 rpm. Under these conditions fuel consumption (measured in Km/1) was measured using a low gear only. As a result, there were obtained the data shown in Table 6. Figure 4 shows the same result in graph form. The best fuel consumption was achieved 205929 when the ratio of ethanol to acetylene gas was 67:33, and there was no appreciable difference in driveability as compared to the use of gasoline only.

Tahlff 6.

Fuel Mixture Ratio Engine Speed (r. p.m.) Liquid : Gas 1,000 1,500 2,000 2,500 3,000 3,500 88 : 12 6.5 6.0 .5 .6 .6 .8 82 : 18 6.9 6.8 6.7 6.7 6.5 6.3 75 : 7.5 7.8 7.8 7.9 7.2 6.8 67 : 33 8.3 8.5 8.4 8.3 7.8 7.5 The result of the road running test where the engine was operated at the speeds 2,000 rpm and 2,500 rpm using top gear only, is shown in Table 7.

N.Z. PATENT OFFICE 11 SEP 1984 —-*• ICE > A RECEIVED 2,000 rpm 2,500 rpn Fuel mixture ratio Fuel Consumption Fuel Mixture Ratio Fuel Ctonsunption liquid : gas Kn/1 liquid : cps Kn/1 84 : 16 16.5 86 : 14 12.6 Experiment 3 Ethanol and gasoline in the ratio of 1 : 1 were used as the liquid fuel and domestic LPG gas was used as the gaseous fuel, and the ratio by weight of liquid fuel to gaseous fuel was varied from 88:12 to 67:33. At the same time, the engine speed was varied between 1,000 rpm and 3,500 rpm. Under these circumstances fuel consumption (measured in Km/1) was measured 205929 using a low gear only. As a result, there were obtained the data shown in Table 8. Figure 5 shows the same result in graph form. The best fuel consumption was achieved when the ratio of the mixtue of ethanol and gasoline to domestic LPG gas was 80:20, and there was no appreciable difference in driveability as compared to the use of gasoline only.

Table 8 Fuel Mixture Ratio Engine Speed (r.p.m.) Liquid : Gas 1,000 1,500 2,000 2,500 3r000 3,500 88 : 12 7.0 6.3 6.8 6.7 .5 .6 84 : 16 6.0 6.3 7.1 6.7 .9 .9 80 : .5 .7 7.3 7.0 7.1 6.3 77 : 23 6.0 6.0 6.4 6.1 .8 .2 69 : 31 .5 6.2 6.0 6.1 6.6 6.3 The result of the road running test where the engine was operated at the speeds 2,000 rpm and 2,500 rpm using top gear only, is shown in Table 9.

ISfoJLe 9 2,000 rpn 2,500 rpn Fuel mixture ratio Fuel Gonsunption Fuel Mixture Ratio Fuel Consumption liquid : gas Kn/1 liquid : gas Kir/l 76 : 24 18.5 80 : 20 15.5 - Experiment 4 } S -J ^ - Ho' Ethnanol and gasoline in the ratio of 1:1 were used as the SEr* - 1 // -14- 205929 liquid tuel and acetylene gas was used as the gaseous fuel, ana the ratio by weight of the liquid fuel to the gaseous fuel was varied from 88:12 to 69:31. At the same time, the engine speed was varied between 1,000 rpm and 3,500 rpm. Under these conditions fuel consumption (measured in Knv/1) was measured using a low gear only,. As a result, there were obtained the data shown in Table 10. Figure 6 shows the same result in graph form. The best fuel consumption was achieved ratio of the mixture of ethanol and gasoline to the acetylene gas was 69:31, and there was no appreciable difference in driveability as compared to the use of gasoline only.

Table 1Q Fuel Mixture Ratio fihgine Speed (r.p.m.) Liquid : Gas 1,000 1,500 2,000 2,500 3,000 3,500 88 : 12 8.1 7.8 6.7 6.4 .8 .6 82 : 18 6.9 8.0 7.0 6.7 6.5 6.0 75 : 7.3 7.5 7.5 7.8 7.0 6.6 69 : 31 7.8 8.2 8.1 8.0 7.5 7.1 The result of the road running test where the engine was operated at the speeds 2,000 rpm and 2,500 rpm using top gear only, is shown in Table 11.

N.Z. PATENT OF; 11 SEP 1984 205929 2,000 rpn 2,500 rpn Fuel mixture ratio Fuel CDnsunption fuel Mixture Patio Fuel Cbnsunption liquia : cps Kn/1 liquid : gas Kn/1 79 : 21 17.3 81 : 19 16.6 Control Experiment Where gasoline alone was used without the addition of a gaseous fuel, fuel consumptions as shown in Table 12 were observed for the stated engine speeds, using a low gear only.

Table 12 Engine Speed (r.p.m.) 1,000 1,500 2,000 2,500 3,000 3,500 Fuel Gonsunption (Kn/1) 5.2 5.8 6.5 6.2 6.1 5.5 The result of the road running test where the engine was operated at the speeds 2,000 rpm and 2,500 rpm using top gear only, is shown in Table 13.

Fuel Consumption (Km/1) Table 11 2,000 rpm 16.5 N.Z. PATL" r 11 SEP 1984 F.CiCuiVOi.' 2,5*00 rpm 14.5 Although domestic LPG gas was adopted as the gaseous fuel in some of the experiments the main components of domestic LPG gas ano CNG are propane and methane, respectively, and both gases have similar characteristics as seen from Table 14 which shows their inflammability ranges and calorific values. It 205929 will be understood, therefore, that similar results can be achieved using either propane gas or methane gas.

Table 14 Inflammability Range Lower Calorific (vol %) Value (cal/g) Propane 2.39 9.50 ca. 11,080 Methane 5.00 15.00 ca. 12,000 Although acetylene gas was also adopted in some of the experiements, acetylene gas and hydrogen have similar characteristics as seen from Table 15, in that they both have a wide inflammability range and are dangerous in use. It will be understood, therefore, that hydrogen can be used in place of acetylene ano offers better efficiency because it has a higher calorific value.

Table 15 Inflammability Range Lower Calorific (vol %) Value (cal/g) Acetylene 2.3 82.0 ca. 11,500 Hydrogen 4.1 75.0 ca. 28,700 As will be apparent from the experiments described above, even when using liquid fuels other than gasoline, ordinary motor vehicles can be driven normally when the liquid fuels are combined with gaseous fuels.

Although a flow rate of gaseous fuel was controlled in the foregoing embodiments, the same effect as in those embodiments can be attained also be providing an adjustable main jet of the carburettor thereby to control the flow rate of the liquid N.2. PATENT OPT ;■ If SEP 1984 205929 A second embodiment of this invention is shown in Figures 7 and 8. In the further embodiments to be described, the parts which are similar to those in the first embodiment are denoted by the same reference symbols.

In the second embodiment, in place of the flow regulating valve (9) serving as an air/fuel ratio adjustment device in the first embodiment, there is provided another air/fuel ratio adjustment device (V') which comprises a second electro-magnetic valve (91 1) on and off intermittently, a controller (61) for the electro-magnetic valve (9''), a potentiometer (63) connected to a throttle valve (31), and a device for measuring the engine speed. More specifically, the air/fuel ratio adjustment device (V) includes the nozzle (10) through which gaseous fuel having passed the second electro-magnetic valve (9'1) is discharged into the inlet air passage, and the electro-magnetic valve controller (61) which controls an opening time of the second electro-magnetic valve (911) in accordance with an opening angle of the throttle valve (31) and the engine spee3.

One input terminal of the electro-magnetic valve controller (61) is connected to the potentiometer (63) in series with the throttle valve (31), while the other input terminal of the controller is connected to an ignition coil (64) thereby to detect the engine speeo.

The electro-magnetic controller (61) comprises a monostable multivibrator, which is triggered by the pulse voltage (A) from the ignition coil (64) as shown in Figure 8, and which generates pulse voltage output ? pn1 gp N. 2. PATENT OFf'. i -18- [ 11 SEP 1984 R!-r.£!VED tuel.

I 0^ 205*929 as shown in Figure 8(B) in accoraance with a time constant determined by a resistance value of the potentiometer (63). The opening time of the second electro-magnetic valve (91') is controlled by the pulse voltage output.

When the engine is stopped, the first electro-magnetic valve (7) is closed. When the ignition switch (III) is turned ON, the first electro-magnetic valve (7) is opened so that the gaseous fuel is supplied at a preselect pressure to the second electro-magnetic valve (9 • *).

When the engine is under a light load, with the throttle valve (31) closed, the resistance value of the potentiometer (63) is small and the pulse width (t) of the pulse voltage output from the electro-magnetic valve controller (61) is narrow, whereby the opening time of the second electro-magnetic valve (91') is short. When the engine is under a heavy load with the throttle valve (31) opened, the resistance value of the potentiometer (63) becomes large and the pulse width (t) of the pulse voltage output from the electro-magnetic valve controller (61) becomes wide, whereby the opening time of the second electro-magnetic valve (9 ' 1) is increased.

Since the electro-magnetic valve controller (61) is triggered by the pulse voltage (A) from the ignition coil (64), the frequency of the pulse voltage output time becomes proportional to the speed of the engine.

Accordingly, the frequency of the opening of the second electro-magnetic valve is in proportion to the engine speed, and the opening time (t) of the second electro-magnetic valve for each opening is substantially in proportion to the opening angle of the throttle valve (31), so that over all, the gaseous N.Z. PATENT OFFICE 1f SEP 1984 205929 fuel is discharged from the nozzle proportionally by weight to the product of the speed and the load of the engine, i.e., inlet air weight.

According to the second embodiment, as explained hereinabove, gaseous fuel can be supplied substantially in proportion to inlet air weight, whereby the ratios among air, gaseous fuel and liquid fuel can be maintained at an almost constant value.

A third embodiment of this invention is shown in Figures 9 and 10.

In the third embodiment, there is included an air/fuel ratio adjustment device (V,f) which is provided with a second flow regulating valve (19) in addition to the flow regulating valve (9) used in the air/fuel ratio adjustment device of the first embodiment. More specifically, a flow regulating valve (29) used in the third embodiment constitutes a gaseous fuel supply system, which comprises the first flow regulating valve (9) adapted to adjust a flow rate of gaseous fuel according to the vacuum within the inlet manifold (4) , the second flow regulating valve (19) connected to the throttle valve (31) through a strut (26) and a rod (12'), and the nozzle (10) adapted to discharge gaseous fuel which has passed through both flow regulating valves (9) and (19) into the inlet air passage (14 ') .

The strut (26) used for actuating the second flow regulating valve (19) functions to transmit a controlled part of the movement of the throttle valve (31). As illustrated in Figure 10, the strut (26) comprises a cylinder (27) and a piston (28), the latter having a leak opening (30) and a valve I 205929 (29'). When the engine is stopped, the electro-magnetic valve (7) is closed. But when the ignition switch (III) is turned ON, the electro-magnetic valve (7) is opened so that gaseous tuel is supplied at a preselected pressure to both tlow regulating valves (9) ano (19) through the pressure regulating valve (8). When the engine is under a light load, as explained cy referring to Figure 2 with the throttle valve (31) closed, the amount of inlet air drawn into the engine is small and vacuum within the inlet manifold (4) is high whereby the diaphragm (12) is urged against the spring (11) to close the valve (13) and decrease the amount of gaseous tuel which is supplied to the engine.

When the engine is under a heavy load with the throttle valve (31) opened, a large amount of inlet air is drawn into the inlet manifold (4) and the vacuum within the inlet manifold (4) is reduced, whereby the diaphragm (12) is pushed by the spring (11), to open the valve (13) so as to increase the amount of gaseous tuel supplied to the engine.

When a high output is required, for example, when starting or accelerating rapidly, the throttle valve (31) is opened abruptly, whereupon the piston (28) of the strut (26) is also pushed abruptly. Therefore, the valve (29') of the piston (28) is closed and oil pressure within the cylinder (27) is increased. As a result the cylinder (27) is also pushed thereby to open the second flow regulating valve (19).

However, since the piston is provided with the leak opening (30), oil pressure within the cylinder (27) is reduced gradually and hence the position of the piston (28) is changed with respect to the cylinder (27). Finally, the second. fcXow.

N.y. rATEMT OFFICE It SEP 1984 RFnpivpn I r 205929 regulating valve (19) is closed by the spring (32).

When the throttle valve (31) is closed abruptly, the piston (28) can return to its original position, because the valve (29') provided on the piston (28) of the strut (26) is opened.

According to the third embodiment, as explained hereinabove, gaseous fuel can be supplied substantially in proportion to inlet air weight through the first flow regulating valve (9), so that the engine can be operated normally while maintaining the ratios among air, gaseous fuel and liquid fuel at an almost constant value. When higher output is required, increased amounts of gaseous fuel with higher calorific value are supplied through the second flow regulating valve (19).

The ratio of gaseous fuel supplied to the engine can be easily changed by adjusting the discharge pressure of the pressure regulating valve (8) .

Hereinafter, there is described a fourth embodiment of this invention which adopts a carburettor for LPG in an air/fuel ratio adjustment device.

In the fourth embodiment, as shown in Figure 11, in addition to the conventional liquid fuel supply system which comprises the liquid fuel tank (1), a float chamber (3') and the carburettor (3) for gasoline including the throttle valve (31) etc. there is further provided a gaseous fuel supply valve (7) which is opened by closing of the ignition switch system which comprises an LPG fuel container (6), a solenoid a vaporizer (VIII) adapted to regulate LPG pressure, and carburettor (100). In this connection, when using 205929 gaseous tuel other than LPG, tor example hydrogen, the vaporizer (VIII) is not required ano gaseous fuel may be supplied through a pressure regulator alone.

As illustrated in detail in Figure 12, the LPG carburettor (100) includes a first bypass passage (43), a second bypass passage (44) as well as a main nozzle (42) between a gaseous fuel passage (21) and a gaseous fuel jet (41). The first bypass passage (43) is provided with adjusting screw (45) arranged to open ana close the passage (43) incrementally in accordance with the kind of gaseous tuel to be used, while the second bypass passage (44) is provided with a choke valve (47) opened and closed by means of an actuator (46) which is operated when the throttle valve (31) assumes a large opening angle.

When the engine is stoppea, the solenoid valve (7) is closed. But when the ignition switch (III) is turned ON, the solenoid valve (7) is opened so that gaseous fuel is supplied at a preselected pressure to the LPG carburettor (100) .

When the engine being unoer a light load with the throttle valve (31) closed, the amount of inlet air drawn into the engine is small, so only small amounts of both liquid fuel and gaseous tuel are supplied.

When the engine is unoer a heavy load with the throttle valve (31) opened, a larger amount of inlet air is drawn into the engine, so larger amounts of both liquid fuel and gaseous fuel are supplied.

When the engine is under the maximum load, the actuator (46) is operated so as to open the choke valve (47), whereby an increased amount of gaseous fuel is supplied.

N.Z. PATENT 23 11 SEP 1984 In this way, since the LPG carburettor (100) and the liquid fuel carburettor (3) are disposed in series in the inlet air passage of the engine, it becomes possible to maintain a constant overall ratio of total fuel weight to the weight of air passing through both carburettors (3) and (100), and it also becomes possible to increase the overall ratio of total fuel weight to inlet air weight, in order to increase the output of the engine.

A fifth embodiment of this invention is shown in Figures 13 to 15. In this embodiment, an air/fuel ratio adjustment device (VI1) is so constructed that the amount of gaseous fuel supplied to the engine is regulated in accordance with the amounts of 0^ and CO contained in exhaust gas from the engine, thereby to ahieve the proper air/fuel ratio. More specifically, in this embodiment, as shown in Figure 13, there is provided a gaseous fuel supply system which comprises an LPG fuel container (6) , a solenoid valve (7) which is opened by the closing of the ignition switch (III), a vaporizer (VIII) adapted to regulate pressure and an LPG carburettor (100) the same as that used in the fourth embodiment; in addition to a liquid fuel supply system which comprises a liquid fuel tank (1), a float chamber (31) and a gasoline carburettor (3) including the throttle valve (31). The air/fuel ratio adjustment device (VI,,I,) controls the gaseous fuel supply system in such a manner that a desired percentage of CO and 02 contained in exhaust gas is maintained.

As illustrated in Figure 14 in detail, the LPG carburettor (100) includes a choke valve 47), opened and closed by means of the actuator (46), between the gaseous fuel passage (2 ' *) and the gaseous fuel jet (41).

An exhaust manifold (4 * 1 > of the engine is provided with a CO sensor (49) and an O^ sensor (48) . Respective outputs from both the sensors (48) and (49) are introduced to an analogue to digital convertor (51) through an analogue switch (50) and then are supplied to a micro-computer (52) after being converted into digital values.

There is further provided a switch (31') which is actuated when the throttle valve (31) has a large opening angle and the opened or closed state of this switch (31') is also an input into the microcomputer (52) .

With regard to a relationship between the concentrations of CO and 0? contained in exhaust gas from the engine, as shown in Figure 15, it is known that the concentration of CO is increased with the fuel mixture becoming richer below the theoretical ideal air/fuel ratio (A) as indicated by a curve (C), while the concentration of 02 is increased with the fuel mixtures becoming leaner above the theoretical ideal air/fuel ratio (A) as indicated by a curve (0). And it is also known that if the engine is operated in the somewhat rich state (D) a higher output will be achieved, while if it is operated in the somewhat lean state (B) fuel consumption will be improved.

In the engine of the fifth embodiment, therefore, liquid fuel such as gasoline or alcohol is supplied through the gasoline carburettor (3) in a constant fuel to air ratio.

When gasoline is supplied from the liquid fuel tank (1)., the engine is operated in a state near the theoretical ideal ^.^air/fuel ratio (A) and hence the concentrations of CO and 02 c>\ j0<antained in exhaust gas are small, because the carburettor (3) i 205929 has been adjusted originally for gasoline.

On the other hand, when only alcohol is supplied as liquid fuel, fuel is in short supply and the mixture becomes lean, so that the concentration of 02 contained in exhaust gas is increased. As a result, the microcomputer [52] controls the actuator [46] of the gas carburettor [100] to open the choke valve [47] and to supply the optimum amount of gaseous fuel in order that the concentration of 02 detected by the 02 sensor comes into the economical fuel consumption range [B].

When the engine is under higher output operation with the throttle valve [31] assuming a large opening angle and the switch [31] turned ON, the microcomputer [52] controls the carburettor [100] to further open the choke valve [47] and to supply the amount of gaseous fuel suitable for producing higher output, in order that the concentration of CO detected by the CO sensor should be increased and the engine is operated in the somewhat rich state [D].

In this way, it is possible to regulate the amount of gaseous fuel supplied to the engine and to maintain the optimum operation state, by detecting CO and 02 contained in exhaust gas from the engine and then maintaining the ratio of liquid fuel with respect to inlet air at a constant value. Therefore, even if the quality of liquid fuel is changed, i.e., even when using liquid fuels having calorific values different from each other, the amount of gaseous fuel supplied can be automatically adjusted in accordance with deficiency of the calorific value.

Although a carburettor was used for supply of liquid fuel in the fifth embodiment mentioned above, this invention is also directly applicable to engines including a liquid fuel supply N.Z. PATENT OFFICE 11 SEP 1984 205929 system wherein tuel is injected electronically, by supplying liquid tuel at the constant ratio with respect to inlet air.

Furthermore, the foregoing emboaiments have been described with rererence to motor vehicle engines, but it will reaaily be appreciatea that the results similar to those in the foregoing emboaiments can be attainea also when this invention is applieO to inaustrial engines for power generation, civil engineering ana other fields.

The throttle valve (47) shown in Figures 12 and 14 may be a flow-regulating valve capable of controlling a supply amount of gaseous tuel. Moveover the actuator (46) may include a diaphragm which is operated by, for example, vacuum pressure within the inlet manifold, thereby to control the flow-regulating valve. Alternatively, the actuator (46) may be so constructed that it operates electo-magnetically, electrically or mechanically in response to the opening angle of the throttle valve. Stated differently, it is sufficient tor the actuator to serve as an opening and closing control means (46) tor the flow-regulating valve, adapted to open ana close the flow-regulating valve (47) in accordance with an opening angle of the throttle valve.

N.Z. PATENT OFF! 1 f SEP 1984

Claims (18)

f^ 205929 WHAT I CLAIM IS:

1. An internal combustion engine fuel supply system comprising: an inlet passage supplying air to the engine, first fuel supply apparatus for introducing a liquid fuel into the said air, second fuel supply apparatus for introducing a gaseous fuel into the said air, and adjustment means to adjust the combined calorific value of the liquid and gaseous fuels mixture to substantially that of gasoline before being mixed with air.

2. A fuel supply system according to claim 1 wherein the said liquid fuel is a mixture of gasoline and at least one liquid fuel having a lower calorific value than gasoline, and the said gaseous fuel has higher calorific value than gasoline.

3. A fuel supply system according to claim 1 wherein: the said adjustment means includes a fuel flow regulator valve responsive to vacuum in the inlet passage.

4. A fuel supply system according to claim 1 wherein the said adjustment means includes: an electromagnetically actuated valve to control the input of the said gaseous fuel, a nozzle connected to the output of said valve to direct said gaseous fuel into the said air, and a regulator to actuate said valve, the regulator SEPJ9 2 8- 205929 functioning to generate a valve-operating pulse voltage at a frequency dependent on the speed of the engine.

5. A fuel supply system according to claim 1 wherein the second fuel supply apparatus comprises: a tank for housing gaseous fuel, an electromagnetic valve controlling the discharge from said tank, a pressure regulating valve connected to the discharge side of the electromagnetic valve, a pressure-sensitive flow-regulating valve connected to the output side of the pressure regulating valve, means for connecting the flow-regulating valve in fluid communication with the inlet passage, and a nozzle connected to the discharge of the flow regulating valve and arranged to discharge fuel from the flow regulating valve into the said air.

6. A system according to claim 5 wherein: the flow regulating valve includes a spring-operated diaphragm.

7. A fuel supply system according to claim 1 wherein the inlet passage includes a throttle valve and the second fuel supply apparatus comprises: a tank for housing gaseous fuel, a first electromagnetic valve controlling the discharge V~':I-.:-, from the tank, - w <? ■. <L> \ a pressure regulating valve connected to the discharge r ■. r:njs6'-- -29- 205929 side or the first electromagnetic valve, a second electromagnetic valve connected, to the discharge side of the pressure regulating valve, an electromagnetic valve controller arranged to control the opening of the second electromagnetic valve, first sensing means indicating the engine speed connected to the valve controller and supplying a pulse signal thereto, second sensing means connected to the valve controller and to the throttle valve to supply a signal to the valve controller indicating the relative opening of the throttle valve, and a nozzle at the discharge side of the second valve positioned to inject gaseous fuel into the inlet passage in response to signals generated in the valve controller by the first and second sensing means.

8. A fuel supply system according to claim 1 wherein the inlet passage includes a throttle valve and the second fuel supply apparatus comprises: a tank for housing gaseous fuel, an electromagnetic valve controlling the discharge from the tank, a pressure regulating valve connected to the discharge side of the electromagnetic valve, first and second flow regulating valves connected to the discharge side of the pressure regulating valve, means for connecting the first flow regulating valve in fluid communication with the inlet passage, a piston and cylinder connecting the second flow regulating valve to the throttle valve, and i-.-Vi*'. n 205929 means for connecting the second flow regulating valve in fluid communication with the inlet passage.

9. A fuel supply system according to claim 1 wherein the second fuel supply apparatus comprises: a carburettor, means for introducing a gaseous fuel into the carburettor, and a valve in the carburettor controlling the amount of gaseous fuel passing therethrough, the carburettor discharging into the inlet passage, -n a sensor for sensing the concentration of carbon monoxide in an exhaust conduit of the engine, a sensor for sensing the concentration of oxygen in the exhaust conduit, and a computer coupled to the sensors and adapted to operate said valve in response to changes in carbon monoxide or oxygen concentrations in the exhaust conduit. . 6'.! r 'ill 11 S£

10. A method of supplying fuel to an internal combustion engine which comprises: mixing gasoline, a liquid fuel having a calorific value below that of the gasoline, and air to form a liquid-air mixture, combining the liquid-air mixture with a gas fuel having a higher calorific value than the gasoline in an amount such that the resultant gasoline, liquid fuel and gas fuel mixture has substantially the same calorific value as the gasoline alone, and operating the engine with the resultant mixture. -31- 205929

11. A method according to claim 10 which includes the step of: increasing the relative amount of gas fuel in the mixture when operating under high load conditions.

12. A method according to claim 10 in which: the liquid fuel is an alcohol.

13. A method according to claim 10 wherein the gas fuel is selected from the group consisting of propane, methane, acetylene, and hydrogen.

14. An internal combustion engine fuel supply system having its parts constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 1 to 6 of the accompanying drawings.

15. An internal combustion engine fuel supply system having its parts constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 7 and 8 of the accompanying drawings.

16. An internal combustion engine fuel supply system having its parts constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 9 and 10 of the accompanying drawings.

17. An internal combustion engine fuel supply system 205929 having its parts constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 11 and 12 of the accompanying drawings.

18. An internal combustion engine fuel supply system having its parts constructed, arranged and adapted to operate substantially as hereinbefore described with reference to Figures 13 to 15 of the accompanying drawings. -"JTBTHARDIE & CO. Patent Attorneys for the Appllcant(s).