JPH04284171A - Ignition timing adjusting device for gas fueled engine - Google Patents

Abstract

PURPOSE:To prevent the generation of knocking and improve fuel consumption by properly determining the ignition timing even if the constituent ratio of gas fuel is not constant. CONSTITUTION:The pressure of the saturated vapor 42 of the gas fuel 17 in a fuel tank 20 is detected by a pressure sensor 43, and the temperature of the saturated vapor 42 is detected by a temperature sensor 44, and each detection signal and the detection signal of the number of revolution of an engine are inputted into a control means 45, and the proper ignition timing is determined.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an ignition timing adjustment device for a gas fuel engine.

0002

[Prior Art] Engines that use liquefied petroleum gas (LPG) as fuel, as well as conventional gasoline engines,
Appropriate ignition timing is required to prevent knocking and improve fuel efficiency. The above LPG has propane and butane as its main components, and the ratio of these components is usually 30:70 (%), but due to regional and seasonal differences,
The component ratio varies, for example, 10:90 (%).

0003

[Problem to be Solved by the Invention] Incidentally, it is preferable that the above-mentioned ignition timing is appropriately determined according to the above-mentioned component ratio of LPG, but in the past, this has not been pursued to determine the ignition timing. Therefore, there is still room for improvement in this respect.

0004

[Object of the Invention] This invention was made in view of the above-mentioned circumstances, and it is possible to appropriately determine the ignition timing even if the component ratio of gas fuel is not constant, and thereby,
The purpose is to prevent knocking and improve fuel efficiency.

[0005]

[Means for Solving the Problems] A feature of the present invention for achieving the above object is that once the pressure and temperature of the saturated vapor of the gas fuel in the fuel tank are known, the component ratio of the gas fuel can be determined. This method was developed with a focus on the fact that the above-mentioned pressure and temperature sensors were provided, and the ignition timing was determined via a control means based on the detection signals of these sensors and the engine speed. It is in.

[0006]

[Operation] The operation of the above configuration is as follows. The pressure of the saturated steam 42 of the gas fuel 17 and the same saturated steam 42
The relationship between the temperature and the component ratio of propane and butane in this gas fuel 17 is as shown in FIG. 3 as an experimental result. On the other hand, the appropriate ignition timing for each component ratio and a certain rotation speed of the engine 1 is as shown in FIG. 4 as an experimental result. Therefore, the results of each of the experiments described above are applied to the control means 4.
5, and the pressure of the saturated steam 42 of the gas fuel 17 in the fuel tank 20 and the temperature of the same saturated steam 42 are measured by a pressure sensor 43 and a temperature sensor 44.
If these detection signals and the detection signal of the rotational speed of the engine 1 are inputted to the control means 45, the control means 45 will determine the appropriate ignition timing.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. In FIG. 2, reference numeral 1 indicates a parallel multi-cylinder engine for an automobile. This engine 1 uses LPG as fuel and has a cylinder 2, a piston 3, and a cylinder head 4, and a space surrounded by these constitutes a combustion chamber 5. Further, 6 is a spark plug. An intake port 7 and an exhaust port 8 are formed in the cylinder head 4, and an intake valve 9 for opening and closing the intake port 7 and an exhaust valve 10 for opening and closing the exhaust port 8 are provided. These intake valves 9 and exhaust valves 10 are opened and closed as appropriate by a valve operating mechanism 11 as the engine 1 operates.

An intake pipe 13 and a surge tank 14 are connected to the intake port 7. Further, an exhaust pipe 15 is connected to the exhaust port 8, and a catalyst 16 for purifying the exhaust gas is contained in the middle of the exhaust pipe 15.

In FIGS. 1 and 2, a fuel supply device 18 is provided for supplying gas fuel 17, which is LPG, to the combustion chamber 5 of the engine 1. This fuel supply device 18 is a fuel tank 2 in which the gas fuel 17 is liquefied and stored in a sealed manner.
0, and a filter 21, a pressure regulator 22, and a mixer 23 are connected to this fuel tank 20. From this mixer 23 to the surge tank 14 and the intake pipe 1.
Gaseous fuel 17 is supplied to the combustion chamber 5 of the engine 1 through the combustion chamber 3 and the intake port 7 .

In FIG. 1, an on-off valve 25 and a pair of emergency valves 26, 2 are provided between the fuel tank 20 and the pressure regulator 22.
7 is interposed. Further, an inlet 28 for feeding the gas fuel 17 into the fuel tank 20 is provided, and this inlet 28 is provided with an on-off valve 29. The pressure regulator 22 vaporizes the liquefied gas fuel 17 from the fuel tank 20 and also regulates the pressure.
Supply to 3.

In FIG. 2, the mixer 23 has a cylindrical casing 34, one end of which is connected to the surge tank 14. The inner hole of the casing 34 serves as an intake passage 35, and outside air is drawn into the combustion chamber 5 through the intake passage 35, the surge tank 14, and the intake pipe 13. A venturi portion 36 is formed in the intake passage 35, the main fuel passage 31 is connected to the venturi portion 36, and a main needle valve for adjusting the opening degree of the main fuel passage 31 is connected to the main fuel passage 31 at this connection portion. 37 are provided.

A throttle valve 38 is provided for opening and closing the intake passage 35 on the downstream side of the venturi section 36. Further, a fuel injection valve 39 is provided which receives gas fuel 17 through the auxiliary fuel passage 32 and injects the fuel into the intake passage 35 downstream of the throttle valve 38. When the engine 1 is in operation, gas fuel 17 from the fuel tank 20 is sent to the pressure regulator 22 and vaporized there, and this vaporized gas fuel 17 passes through the main fuel passage 31 and is sucked into the intake passage 35. The gaseous fuel 17 and air sucked in this way are sufficiently mixed in the intake passage 35, and the mixture flows into the surge tank 14 and the intake pipe 13.
, and into the combustion chamber 5 through the intake port 7, where it is combusted.

Further, a part of the gaseous fuel 17 vaporized by the pressure regulator 22 is injected into the intake passage 35 by appropriate operation of the fuel injection valve 39, and is sufficiently mixed with air in the intake passage 35. The air-fuel mixture is drawn into the combustion chamber 5 and combusted in the same manner as described above. In addition, in the event of an emergency such as a car collision, the emergency valves 26 and 27 are designed to close immediately.

In FIG. 1, an igniter 40 operates with the engine 1 to ignite the spark plug 6.
and a distributor 41 are provided. On the other hand, a pressure sensor 43 for detecting the pressure of the saturated vapor 42 of the gas fuel 17 in the fuel tank 20 is provided, and a temperature sensor 44 for detecting the temperature of the same saturated vapor 42 is provided. These pressure sensor 43 and temperature sensor 4
4 is electrically connected to the igniter 40 via a control means 45. And the pressure sensor 43
and each output signal of the temperature sensor 44, and the igniter 40.
The control means 45 inputs the rotation speed of the engine 1 detected by the igniter 40 and the distributor 4 according to the output signal of the control means 45.
1, the timing of the ignition operation of the spark plug 6 is determined.

[0015] This will be explained more specifically. FIG. 3 shows experimental results showing the relationship between the pressure (gauge pressure) of the saturated steam 42, the temperature of the same saturated steam 42, and the component ratio of propane and butane in the gas fuel 17. Symbols A to E in this figure indicate gas fuels 17 having mutually different component ratios, as shown in the table below.

[0016]

On the other hand, FIG. 4 shows the relationship between the ratio of each component of the gas fuel 17 and the appropriate ignition timing at a certain rotation speed of the engine 1. The symbols A, C, and E in this figure correspond to those in the table above.

The results of each of the above experiments are programmed into the control means 45 as a map. For this reason,
When the detection signals of the pressure and temperature of the saturated steam 42 are input to the control means 45 as described above, first, the component ratio corresponding to these detection signals is detected by the map of the control means 45 corresponding to FIG. Next, based on this component ratio and the detection signal of the rotational speed of the engine 1, an appropriate ignition timing is determined by a map of the control means 45 corresponding to FIG. In this case, for example, when the gas fuel 17 has a high proportion of propane as shown in symbol A, the crank angle is advanced to a point just before knocking occurs to improve fuel efficiency. In addition, when the gas fuel 17 has a low proportion of propane as shown in symbol E, the crank angle is retarded to delay the ignition timing until the fuel efficiency deteriorates.
Prevent knocking from occurring.

[0019]

According to the present invention, a pressure sensor for detecting the pressure of saturated vapor of gaseous fuel in a fuel tank and a temperature sensor for detecting the temperature of the saturated vapor are provided, and each detection signal of these sensors is Since the ignition timing is determined via the control means based on the engine speed and the engine speed, the following effects can be obtained.

That is, the pressure of the saturated steam, the temperature of the saturated steam, and the component ratio of propane and butane in the gas fuel have a certain relationship. On the other hand, there is also a certain relationship between each component ratio and the appropriate ignition timing at a certain engine speed. Therefore, each of the above relationships is programmed into the control means, and then the pressure of the saturated vapor of the gas fuel in the fuel tank and the temperature of the same saturated vapor are detected by a pressure sensor and a temperature sensor. By inputting the signal and the engine rotational speed detection signal to the control means, the control means determines the appropriate ignition timing. Therefore, even if the component ratio of gas fuel is not constant, the ignition timing can be determined appropriately.
According to this invention, the occurrence of knocking is prevented and fuel efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 is an overall simplified diagram of a fuel supply device.

FIG. 2 is a side cross-sectional view of a portion of the engine and fuel supply system.

FIG. 3 is a graph diagram showing the relationship between saturated vapor of gas fuel, pressure, and temperature.

FIG. 4 is a graph diagram showing the relationship between the component ratio of gas fuel, engine speed, and appropriate ignition timing.

[Explanation of symbols]

1 Engine 17 Gas fuel 18 Fuel supply device 20 Fuel tank 42 Saturated steam 43 Pressure sensor 44 Temperature sensor 45 Control means

Claims (1)

[Claims] Claim 1: A pressure sensor for detecting the pressure of saturated vapor of gaseous fuel in a fuel tank and a temperature sensor for detecting the temperature of the same saturated vapor are provided, and each detection signal of these sensors and the engine rotation speed are provided. An ignition timing adjustment device for a gas fuel engine, which determines the ignition timing through a control means based on the ignition timing.