JPS62142853A - Regulator for gas fired engine - Google Patents

Abstract

PURPOSE:To prevent respective members from being cooled because of adiabatic expansion caused when fuel gas is reduced in pressure by providing a PTC (Positive Temperature Coefficient) heater composed of an element having a positive temperature coefficient of resistance value, around the periphery of an open end of a high temperature gas passage released to a pressure reducing chamber. CONSTITUTION:A regulator 1 is composed of a high pressure side body 11 equipped with a fuel cut-off valve 9, a low pressure side body 13 equipped with respective members for reducing pressure, and of a PTC heater 15 arranged between both of the bodies 11 and 13. And the PTC heater 15 is composed of a heating element 57 consisting of a PTC thermistor, a wire 59 connected with both ends of the heating element 57 to apply specified voltage, and of a water-proof cover 61. When fuel gas is injected into a pressure reducing chamber 21, as adiabatic expansion is accompanied therewith, both an open end 38 of No.2 high pressure gas passage 23 and the vicinity of a valve chamber 35 are extremely cooled. Accordingly, the PTC heater 15 is heated up for preventing respective members 38 and 35 from being cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a regulator for a gas-fueled engine that reduces the pressure of high-pressure gas such as compressed natural gas (CNG) to a predetermined pressure.

BACKGROUND OF THE INVENTION In recent years, natural gas has been reconsidered as an alternative energy source to oil, and the movement to utilize it as a fuel for automobiles has become active, especially in natural gas producing countries. Natural gas has methane as its main component, which has a low boiling point, and this is the main difference from petroleum gas, which has relatively high boiling points, such as propane and butane, as its main components. Therefore, when using natural gas as a fuel for automobiles, it is difficult to store LPG (liquefied petroleum gas), which has traditionally been used in some automobile fuels, as a liquid at room temperature, and it is difficult to compress it. Natural gas (Coa+pressed Natural Gas:
Generally, it is stored and used as GNG (hereinafter abbreviated as GNG).

In vehicles that use CNG as fuel, CNG is normally sealed in a cylinder at high pressure, is depressurized by a regulator or governor, mixed with air by a mixer using a venturi, etc., and then supplied to the engine. I have to. A practical regulator or governor is one that controls the release of gas from the high-pressure side gas passage connected to the cylinder to the decompression chamber by opening a valve 1r1 that is linked to a diaphragm that detects the atmospheric pressure in the decompression chamber. This can be done in two or more stages by combining these multiple stages or by integrally constructing the parts of the number of stages, and when the CNG is sealed in the cylinder, for example, 200 kg/cm2 is heated to atmospheric pressure, for example. I'm trying to reduce the pressure. (Example: JP-A-59-165852) Problems to be Solved by the Invention However, during this pressure reduction, due to adiabatic expansion when fuel gas is released from the high-pressure side gas passage to the decompression chamber, the high-pressure side gas passage The area near the open end of the fuel gas is cooled, and in this area, especially in the high-pressure side gas passage, components with relatively high melting points such as propane, butane, or water mixed in the fuel gas are transferred directly from the gas or via the liquid state. This causes the fuel to solidify, resulting in a substantial reduction in the passage diameter, which impedes the flow of the gas fuel and reduces engine performance.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a regulator for a gas fuel engine that can prevent narrowing of the gas passage due to coagulation of mixed fuel gas components in the high-pressure side gas passage, etc., regardless of the operating state of the engine. shall be.

Means for Solving the Problems The problem with the prior art described above is that the open end of the high-pressure side gas passage opened to the reduced-pressure chamber is opened or closed depending on the atmospheric pressure in the reduced-pressure chamber, and the fuel in the high-pressure side gas passage is removed. In a gas fuel engine regulator configured to reduce the pressure of gas to a constant pressure, a fuel cutoff valve is provided in the high-pressure side gas passage to cut off the fuel gas when the engine is stopped or in an emergency, and a fuel cutoff valve is provided on the downstream side of the fuel cutoff valve. This problem can be solved by providing a PTC heater made of an element having a positive temperature coefficient of resistance around the open end of the high-pressure side gas passage.

A PTC heater is one of the functional ceramics that has been put into practical use in recent years.
It consists of a thermistor.

Function As mentioned above, the electrical resistance of a PTC heater increases significantly as its temperature rises, so if you apply a constant voltage while the engine is running, the current will change depending on the temperature of the heat generating part. It exhibits a self-temperature control effect that maintains the temperature at a constant level. Therefore, it is possible to supply necessary and sufficient heat to a desired location with an extremely simple electric circuit.

In the gas fuel engine regulator of the present invention,
When gas fuel starts to flow after the engine starts, it is cooled by adiabatic expansion during depressurization and the temperature of surrounding parts decreases, but at this low temperature, the resistance value of the PTC heater is small, so a relatively large current flows, and a relatively large current flows around the open end. The parts warm up rapidly. As the temperature of the relevant part and the PTC heater itself gradually increases, the resistance value gradually increases accordingly.
Eventually, a steady temperature is reached where the amount of heat dissipated by the PTC heater and the power consumption are balanced, and self-control is performed to maintain this temperature.

In this way, the temperature decrease during the process of adiabatic expansion of the fuel gas is prevented, and coagulation of mixed components in the fuel gas is prevented, so that narrowing of the high-pressure side gas passage is prevented.

Embodiments Hereinafter, preferred embodiments of the present invention will be explained based on the drawings.

Referring to FIG. 3, there is shown a fuel supply system for a gas fuel vehicle constructed using the regulator of the present invention, and this is nothing but a system separately proposed by the inventors of the present invention. In this case, in order to shorten the high pressure piping route, the regulator is divided into at least two parts, and if the number of divisions is 2, for example, the primary regulator 1 and the fuel cutoff valve 9 are integrally configured. A cylinder 2 filled with CNG, etc. is placed in a luggage storage area 3 of a vehicle (the trunk of a passenger car, a truck bed), a secondary regulator 4 and a mixer 5 are placed in an engine storage area 6 of the vehicle, and a The regulator 1 and the secondary regulator 4 are connected by a pipe 8 laid in a passenger compartment area 7 of the vehicle.

Gaseous fuel such as CNG filled into the cylinder 2 at a pressure of, for example, 150 to 250 K9/32 immediately after filling is supplied to the primary regulator 1 via the fuel cutoff valve 9, where it is supplied to the primary regulator 1 at a pressure of, for example, 3 to 5 Kg/J. After being depressurized to , it is sent to the secondary regulator 4 through the pipe 8 . The primary pressure-reduced fuel gas is further reduced in pressure by the secondary regulator 4 to approximately atmospheric pressure, for example 0 to 200+s+AQ, and then the engine 10
The air is mixed with air at a predetermined ratio by a mixer 5, which is formed integrally with the engine or provided separately, and is supplied to the engine 10.

Of these divided regulators, the present invention is effectively applied to the primary regulator 1 which is located on the most upstream side and has the widest reduced pressure difference, and its configuration is, for example, as shown in FIG. It has become.

The primary regulator 1 includes a high-pressure side body 11 to which a fuel cutoff valve 9 is attached, a low-pressure side body 13 to which various members for pressure reduction are attached, and a PTC heater 15 interposed between the two bodies. A fuel cutoff chamber 1 is provided in the high pressure side body 11.
7 is formed, and this fuel cutoff chamber 17 is connected to a first high pressure gas passage 19 connected to a high pressure pipe (not shown) from the cylinder 2.
and a second high pressure gas passage 23 communicating with a reduced pressure chamber 21 formed in the low pressure side body 13.

The fuel cutoff valve 9 includes a fuel cut needle valve 25 that can move up and down within the fuel cutoff chamber 17 and an electromagnetic coil (not shown) for driving the fuel cut auxiliary valve 25.
7 to the high pressure side body 11. The electromagnetic coil is connected to a battery power source 31 via a switch 29 that is linked to an ignition switch (not shown), and drives the fuel cut needle valve 25 downward to close the lower conical wall of the fuel cutoff chamber 17, for example, when the engine is stopped. 33,
It is designed to block the flow of fuel gas downstream. The switch 29 does not necessarily have to be a mechanical switch, and may be constructed from an electronic circuit or the like having a switch function so as to be turned on or off by a signal from a means for detecting an abnormal situation, for example.

A valve chamber 35 is formed in the lower part of the high pressure side body 11,
A valve 37 is loosely fitted inside this. valve 37
As shown in FIG. 2, it has a non-circular cross-sectional shape with a convex or concave portion around the periphery, and when it is in close contact with the open end 38 of the second high-pressure gas passage 23, it prevents the fuel gas from flowing downstream. When the valve 37 is shut off and is shifted downward and separated from the open end 38, the fuel gas is discharged into the decompression chamber 21 through the gap formed between the uneven portion of the valve 37 and the inner wall of the valve chamber 35. The lower end of the valve 37 comes into contact with an L-shaped lever 41 that is pivotally supported by a pin 39 fixed to the low-pressure side body 13,
The eight-shaped lever 41 is connected to a shaft 45 that transmits the displacement of a diaphragm 43 that forms the reduced pressure chamber 21 together with the low-pressure side body 13. Seat 17 feet 45
are shells 47a and 47b that sandwich the diaphragm 43;
It is fixed with a nut 49. 51 is an outer shell 47a and a diaphragm 43 on the low pressure side body 13.
A cover 53 having a hole that is fixed through the hole and opens to the atmosphere.
The spring constant is determined by the desired gas fuel pressure to be reduced.

Now, when the pressure in the decompression chamber 21 is low and the diaphragm 43 is displaced to the right in the figure, the valve 37 is lowered and the fuel gas flows out from the second high pressure gas passage 23 into the decompression chamber 21. When the pressure inside the decompression chamber 21 gradually rises and the diaphragm 43 is displaced to the left, the second valve 37 opens.
The open end 38 of the high pressure gas passage 23 is closed to no longer allow fuel gas to pass therethrough. In this way, inside the decompression chamber 21, the spring member 5 is always in the normal position of the diaphragm 43.
An air pressure corresponding to the repulsive force of 1 is maintained, and the fuel gas is discharged to the low pressure gas passage 55 at this air pressure.

- On the other hand, when the fuel gas is released into the decompression chamber 21, it undergoes adiabatic expansion, so the open end 38 of the second high pressure gas passage and the vicinity of the valve chamber 35 are extremely cooled. Therefore, in this embodiment, a PTC heater is provided around the second high pressure gas passage 23 and the valve chamber 35. The PTC heater 15 is a heating element 5 made of a BaTiO3-based PTC thermistor.
7, a wire 59 connected to both ends of this heating element to apply a predetermined voltage, and a waterproof cover 61.
3. The voltage can be applied to the heating element 57 at any time during engine operation without special control, for example in conjunction with an ignition switch. Immediately after the engine is started, the temperature near the open end 38 drops the most, but since the resistance value of the heating element 57 is small, a large current flows and the temperature rises almost immediately. Once the temperature rises, the resistance value of the heating element 57 becomes extremely large, so the area around the second high-pressure gas passage 23 and the valve chamber 35 is maintained at a predetermined steady temperature without consuming much power. Ru.

In this embodiment, the PTC heater 15 is arranged only around the second high pressure gas passage 23 and the valve chamber 35, but it is also possible to extend it to other places, for example, around the decompression chamber 21. This does not deviate from the spirit of the invention.

Effects of the Invention With the configuration described above, the technical problem of the present invention is solved and the object of the present invention is achieved, and cooling of each member due to adiabatic expansion during fuel gas pressure reduction is prevented by using a PTC heater. Compared to technology that uses heated engine coolant to heat the regulator, this technology allows the engine to heat up quickly even immediately after starting, and then maintains the temperature at the desired stable temperature. Can be continued. Furthermore, since this heat is also transmitted to the fuel cutoff valve, it is possible to prevent the fuel cutoff valve from freezing.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional configuration diagram of a regulator for a gas fuel engine showing a preferred embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, and FIG. There is a block configuration diagram C of a gas fuel vehicle constructed by applying this method. 9...Fuel cutoff valve, 11...High pressure side body, 13
...Low pressure side body, 15...PTC heater, 21.
...Decompression chamber, 25...Fuel cut needle valve, 37...
Valve, 43...diaphragm.

Claims (2)

[Claims] (1) A gas fuel engine that opens and closes the open end of a high-pressure side gas passage that is opened to the decompression chamber according to the atmospheric pressure in the decompression chamber, thereby reducing the pressure of the fuel gas in the high-pressure side gas passage to a constant pressure. 1. A regulator for a gas fuel engine, characterized in that a PTC heater made of an element having a positive temperature coefficient of resistance is provided around the open end. (2) A gas fuel engine configured to reduce the pressure of the fuel gas in the high-pressure side gas passage to a constant pressure by opening and closing the open end of the high-pressure side gas passage opened to the decompression chamber according to the atmospheric pressure in the decompression chamber. In the regulator, a fuel cutoff valve for shutting off the high pressure side gas passage is integrally provided upstream of the open end of the high pressure side gas passage, and the fuel cutoff valve is formed of an element having a positive temperature coefficient of resistance around the open end. A regulator for a gas fuel engine characterized by being equipped with a PTC heater.