JP2882222B2 - Vaporizer pressure regulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquefied petroleum gas (LP)
G) relates to an internal combustion engine using fuel as fuel,
The present invention relates to a pressure control device for a vaporizer that converts PG into decompressed gas and supplies the gas to a venturi in an intake passage.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine using LPG as fuel, the fuel is vaporized by heating between a fuel tank and a venturi in order to supply the fuel in a vaporized state to a venturi in an intake passage. Regulator is provided.

[0003] This regulator uses LP from a pressure vessel.
Primary pressure control chamber to introduce G and LP gasified into intake passage
And a secondary pressure regulating chamber for delivering G. When the gas pressure in the secondary pressure chamber becomes a negative pressure, a passage connecting the primary pressure chamber and the secondary pressure chamber in conjunction with the movement of the membrane separating the secondary pressure chamber and the air chamber. Is opened. Along with this, LPG is supplied from the primary pressure regulating chamber to the venturi in the intake passage via the secondary pressure regulating chamber.

In recent years, a technique has been proposed in which an air chamber and an air cleaner upstream of a venturi are communicated with each other through an air passage. With this technology, the reproducibility of the idling of the engine is improved, and the idling operation state is stabilized. However, in this technique, if the engine speed is gradually increased from the idling state, a problem may occur that the air-fuel mixture becomes extremely lean in a certain speed range regardless of the load.

Therefore, as a technique for solving the above-mentioned problem, there is a technique disclosed in Japanese Utility Model Laid-Open No. 59-100954, for example. In this technique, a pressure adjusting device including a diaphragm or a bellows is provided for the air passage. Thus, by providing the pressure regulating device, the pressure pulsation of the engine intake air is absorbed by the pressure regulating device. Therefore, a substantially constant pressure always acts on the membrane, and the movement of the membrane is less affected by the pressure pulsation of the secondary pressure regulation chamber. As a result, the problem that the air-fuel mixture becomes extremely lean in a certain rotational speed range and the air-fuel ratio is extremely reduced is solved.

[0006]

However, in the above prior art, the inside diameter and length of each air passage, that is, the air passage connecting the air chamber and the pressure control device, or the air connecting the pressure control device and the air cleaner, are reduced. No reference is made to the inside diameter and length of the passage. Therefore, if these points are inappropriately selected, the influence of pressure pulsation may still occur. In particular, in a high-load region where the pressure pulsation of the intake air is largely transmitted to the air cleaner, there is a possibility that the normal movement of the film is hindered. As a result, the supply amount of the fuel may become too large or, on the contrary, too small, and the air-fuel ratio may be largely changed due to the change in the engine speed.

[0007] A diaphragm or bellows is applied as the pressure regulating device. Each of these has a drawback that the pressure pulsation absorption characteristics are liable to change because the internal volume and the like greatly change with environmental changes such as temperature changes. Therefore, there is a possibility that the normal movement of the film is hindered as in the above.

The present invention has been made in view of the above-described circumstances, and has as its object to obtain a stable air-fuel ratio characteristic without being affected by a temperature change in any operation region including a high-load region. It is an object of the present invention to provide a vaporizer pressure control device capable of performing the above-described operations.

[0009]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and, as a result, came to the present invention. That is, in the present invention, the fuel composed of liquefied petroleum gas is vaporized in the primary pressure regulating chamber by a predetermined heat source, and the vaporized fuel is regulated in the secondary pressure regulating chamber to near the atmospheric pressure. A regulator that supplies the Venturi in the intake passage through the fuel hose and supplies it to the internal combustion engine, and an air chamber that is opposed to the secondary pressure regulating chamber of the regulator with a membrane interposed between the regulator and the air cleaner that is provided in the middle of the intake passage A pressure regulator for a vaporizer comprising an air hose connecting the side and a resonator provided in the middle of the air hose, wherein the volume of the resonator is about twice or more the displacement per cylinder of the internal combustion engine. The inside diameter of the first air hose connecting the chamber and the resonator is set to α times the average inside diameter of the intake passage, and the length is adjusted by the air cleaner in the intake passage. The length of the second air hose connecting the resonator to the clean side of the air cleaner is set to 2α times the length of the air cleaner, and the inner diameter of the second air hose is set to β times the average inner diameter of the intake passage. The gist is that the length is set to 4β times or more of the length from to the venturi (α and β are both positive values).

[0010]

According to the above construction, the fuel which is vaporized by the predetermined heat source in the primary pressure regulating chamber and whose pressure is regulated to near the atmospheric pressure in the secondary pressure regulating chamber is taken in through the main fuel hose. It is supplied to the venturi of the passage and supplied to the internal combustion engine.

A first air hose is provided having an inner diameter α times the average inner diameter of the intake passage and having a length of 2α times the length from the air cleaner to the venturi in the intake passage and connecting the air chamber and the resonator. ing. The internal diameter is β times the average internal diameter of the intake passage through a resonator having a volume of about twice or more the displacement per cylinder of the internal combustion engine,
A second air hose having a length at least 4β times the length from the air cleaner to the venturi in the intake passage and connecting the resonator to the clean side of the air cleaner is provided. For this reason, even if the current operating state is any operating area including the high load area, the pressure pulsation of the intake air of the internal combustion engine is absorbed by the resonator and the first air hose and the second air hose are mutually connected. Offset by the pressure pulsation. Therefore, a substantially constant pressure always acts on the membrane, and the movement of the membrane is not affected by the pressure pulsation.

Further, the internal volume of the resonator provided between the first air hose and the second air hose does not fluctuate significantly due to a temperature change. Therefore, the characteristic of absorbing the pressure pulsation by the resonator does not change so much depending on the temperature change.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a vaporizer pressure adjusting device according to the present invention will be described in detail with reference to FIGS.

FIG. 1 is a schematic diagram illustrating a pressure control device of a vaporizer mounted on a vehicle in this embodiment. In an LPG internal combustion engine (not shown) using liquefied petroleum gas (LPG) as a fuel, the LPG internal combustion engine includes:
An air cleaner 2 and a cool air duct 3 are connected via an intake passage 1. A venturi 4 is provided in the intake passage 1. In addition, this Venturi 4
A throttle valve 5 which is opened and closed in conjunction with the operation of an accelerator pedal (not shown) is provided in the intake passage 1 further downstream than the intake passage. When the throttle valve 5 is opened and closed, the amount of air taken into the intake passage 1 is adjusted.

The pressure regulator of the vaporizer in this embodiment includes a regulator 6 for supplying fuel to the venturi 4 in a vaporized state. This regulator 6 is LP
It is provided between the fuel tank 7 for storing the G fuel and the venturi 4 and promotes the vaporization of the fuel introduced from the fuel tank 7 through the tank-side fuel passage 8 by heating, and the fuel is depressurized and adjusted. It is for pressing.

That is, the inside of the casing 9 constituting the regulator 6 is partitioned by the partition 10 into two chambers 11 and 12 of primary and secondary. In the primary chamber 11, a first diaphragm 13 is provided.
3 makes the primary chamber 11 a primary pressure chamber 14 and a primary air chamber 15
It is divided into and. The secondary chamber 12 is provided with a second diaphragm 16 as a film.
6, the secondary chamber 12 is divided into a secondary pressure regulating chamber 17 and a secondary air chamber 18 as an air chamber.

A part of the partition wall 10 is provided with a communication passage 19 for communicating the primary pressure regulating chamber 14 with the secondary pressure regulating chamber 17. The partition 10 is provided with a water passage (not shown) through which cooling water for cooling the LPG internal combustion engine flows as a heat source. Further, an internal fuel passage 20 through which fuel flows is provided inside the partition wall 10. One end of the internal fuel passage 20 is connected to a tank-side fuel passage 8 extending from the fuel tank 7. The other end of the internal fuel passage 20 can communicate with the primary pressure regulating chamber 14. One end of a main fuel hose 21 for leading fuel to the venturi 4 based on the negative pressure generated in the venturi 4 is connected to the secondary pressure regulating chamber 17.

One end of a slow fuel hose 22 for drawing out idle slow fuel is communicated with the primary pressure regulating chamber 14, and the other end is communicated with a main fuel hose 21. In the middle of the slow fuel hose 22, in order to allow / cut off the flow of the slow fuel of the hose 22,
A slow lock valve 23 that is opened and closed by using a solenoid 23a as a drive source is provided. When the slow lock valve 23 is controlled to close, the supply of the slow fuel from the slow fuel hose 22 to the main fuel hose 21 is cut off, so that the slow fuel cut at the time of deceleration or the like is performed.

The first diaphragm 13 is provided with a first valve member 24 for opening and closing the other end of the internal fuel passage 20. Further, a compression spring 25 is provided in the primary air chamber 15, and the inside of the air chamber 15 is set to substantially the atmospheric pressure. Here, the first diaphragm 13 is constantly urged toward the primary pressure regulating chamber 14 by the urging force of the compression spring 25 and the atmospheric pressure in the primary air chamber 15, whereby the pressure inside the primary pressure regulating chamber 14 becomes a predetermined pressure. The pressure is adjusted.

Then, at normal temperature, the first diaphragm 13 is displaced toward the primary pressure regulating chamber 14 by the urging force of the compression spring 25 as the pressure in the primary pressure regulating chamber 14 decreases. Due to this displacement, the first valve member 24 operates to open the internal fuel passage 20, and the primary pressure regulating chamber 14 is opened from the passage 20.
The fuel from the fuel tank 7 is introduced into the tank. Further, the fuel introduced into the primary pressure regulating chamber 14 is vaporized by a heat source in the same pressure regulating chamber 14, and the vaporization increases the pressure in the primary pressure regulating chamber 14, causing the first diaphragm 13 to perform primary pressure regulation. Room 1
The internal fuel passage 20 is closed by being displaced to the fourth side. Thus, the pressure in the primary pressure regulating chamber 14 is regulated to a predetermined pressure.

On the other hand, the second diaphragm 16 is provided with a second valve member 26 for opening and closing one end of the communication path 19. Further, a compression spring 27 is interposed between the second valve member 26 and the partition 10, and the compression spring 27
Accordingly, the second valve member 26 is urged in a direction to close the communication passage 19. Further, the inside of the secondary air chamber 18 is set to substantially the atmospheric pressure.

When the pressure in the secondary pressure regulating chamber 17 decreases, the second diaphragm 16 is displaced toward the secondary pressure regulating chamber 17 against the urging force of the compression spring 27. Due to this displacement, the second valve member 26 operates to open the communication passage 19, and fuel is introduced from the primary pressure regulating chamber 14 to the secondary pressure regulating chamber 17. The fuel introduced into the secondary pressure adjusting chamber 17 is adjusted to almost the atmospheric pressure in the tuning pressure chamber 17, and is then led out to the venturi 4 through the main fuel hose 21.

As described above, the regulator 6 vaporizes the fuel introduced from the fuel tank 7 in the primary pressure regulating chamber 14 using cooling water as a heat source, and further reduces the pressure in the secondary pressure regulating chamber 17 to near atmospheric pressure. After the pressure is adjusted, the pressure is led out to the venturi 4 mainly through the main fuel hose 21. Further, the fuel mixed with the air in the venturi 4 is supplied to the LPG internal combustion engine through the intake passage 1 and used for combustion. When the LPG internal combustion engine is operating, opening the throttle valve 5 increases the amount of intake air passing through the venturi 4, thereby increasing the venturi negative pressure. Therefore, in the regulator 6, the negative pressure acting on the secondary pressure regulating chamber 17 through the main fuel hose 21 increases, and accordingly, the second valve member 26 is opened and the fuel supply amount to the venturi 4 increases. .

In this embodiment, the secondary air chamber 1
An air hose 31 that connects the air cleaner 8 to the clean side of the air cleaner 2 provided in the middle of the intake passage 1 is provided. A rectangular tubular (rectangular) resonator 32 having a predetermined volume is interposed in the air hose 31. That is, the air hose 31 is a first air hose 33 connecting the secondary air chamber 18 and the resonator 32.
And a second air hose 34 connecting the resonator 32 and the clean side of the air cleaner 2.

In this embodiment, the resonator 32
Is 2 times the displacement per cylinder of the LPG internal combustion engine.
(For example, when the displacement per cylinder is “500 cc”, the volume of the resonator 32 is “10 cc”.
00cc "or more).

The inside diameter of the first air hose 33 is α times the average inside diameter of the intake passage 1 (where α is a positive value), and the length of the first air hose 33 is 2 of the length from the air cleaner 2 to the venturi 4 in the passage 1
α times.

Further, the inner diameter of the second air hose 34 is
Β times the average inner diameter of the intake passage 1 (where β is a positive value)
The length of the second air hose 34 is at least 4β times the length from the air cleaner 2 to the venturi 4 in the intake passage 1.

Next, the operation of this embodiment will be described. In this embodiment, as described above, the resonator 32 having a volume that is at least twice the displacement per cylinder of the LPG internal combustion engine is provided. The secondary air chamber 18 is formed by a first air hose 33 having an inner diameter α times the average inner diameter of the intake passage 1 and having a length 2α times the length from the air cleaner 2 to the venturi 4 of the intake passage 1. The communication with the resonator 32 is established. The resonator 32 and the air cleaner 2 are formed by a second air hose 34 having an inner diameter β times the average inner diameter of the intake passage 1 and having a length equal to or more than 4β times the length from the air cleaner 2 to the venturi 4 of the intake passage 1. There is communication with the clean side. For this reason, even if the current operating state is any operating area including the high load area, the pressure pulsation accompanying the intake of the internal combustion engine is reliably absorbed by the resonator 32 and the first air hose 33 and the The pressure pulsation between the two air hoses 34 reliably cancels each other. Therefore, a substantially constant pressure always acts on the second diaphragm 16, and the movement of the second diaphragm 16 is not affected by the pressure pulsation. Therefore, a stable air-fuel ratio characteristic can be obtained in any operation range including the high load range.

Further, a resonator 32 provided between the first air hose 33 and the second air hose 34 is provided.
Does not significantly change the internal volume due to a temperature change. Therefore, unlike the prior art in which a diaphragm or a bellows is used, the absorption characteristic of the pressure pulsation by the resonator 32 does not fluctuate much due to a temperature change, and a more stable air-fuel ratio characteristic can be obtained.

Next, in order to confirm the excellent air-fuel ratio performance, the volume of the resonator 32 and the first air hose 33
The following experiment was performed by variously changing the inner diameter and length of the second air hose 34 and the inner diameter and length of the second air hose 34. In performing the following experiment, the displacement per cylinder of the LPG internal combustion engine (hereinafter simply referred to as unit displacement QE) is set to “5”.
The load was fixed to the maximum load (WOT) condition. Also, the inner diameter of the main fuel hose 21 is set to “13”.
mm "and the length was fixed at" 550 mm ". Furthermore, the average inner diameter of the intake passage 1 (hereinafter simply referred to as the intake diameter D) is set to “5
5 mm ”, the length from the air cleaner 2 to the venturi 4 in the intake passage 1 (hereinafter simply referred to as the intake length L) is set to“ 101 ”.
0 mm ".

First, the air-fuel ratio A / F with respect to the engine speed NE when the volume of the resonator 32 is variously changed.
2 is shown in FIG. However, at this time, the inner diameter of the first air hose 33 is fixed at “13 mm”, the length is fixed at “500 mm”, and the inner diameter of the second air hose 34 is “13 mm”.
The length was fixed at “700 mm”. As is clear from FIG. 2, it is understood that the relationship between the engine speed NE and the air-fuel ratio A / F becomes more stable as the volume of the resonator 32 increases. Particularly, when the volume of the resonator 32 is equal to or more than twice the unit displacement QE, that is, equal to or more than "1000 cc", the air-fuel ratio A / F varies little with the engine speed NE, and the air-fuel ratio characteristics are most stable in such a case Was obtained.

Second, FIGS. 3 and 4 show the results when the inner diameter and length of the first air hose 33 are variously changed. In FIG. 3, the volume of the resonator 32 is set to “750 cc”, the inner diameter of the second air hose 34 is fixed to “13 mm”, the length is fixed to “700 mm”, and the inner diameter of the first air hose 33 is set to “13 mm”. The engine speed NE when fixed and the length of the first air hose 33 is changed
Shows the relationship of the air-fuel ratio A / F to the air-fuel ratio. In this case, the inside diameter of the first air hose 33 is “13 mm”, and the intake diameter D
Is about "0.236 times". And, as is clear from the figure, the length of the first air hose 33 is “4”.
The most stable air-fuel ratio characteristics can be obtained in the range of "70 to 480 mm". That is, it can be said that the value of “470 to 480 mm” is substantially equal to a value obtained by multiplying the intake length L by a value twice the ratio of the inner diameter of the first air hose 33 to the intake diameter D.

In FIG. 4, the volume of the resonator 32 is set to “1000 cc”, the inner diameter of the second air hose 34 is fixed to “7 mm”, the length is fixed to “600 mm”, and the inner diameter of the first air hose 33 is fixed to “600 mm”. Shows the relationship between the engine speed NE and the air-fuel ratio A / F when the length of the first air hose 33 is changed while fixing at 11 mm. In this case, the inner diameter of the first air hose 33 is “11”.
mm ", which is about" 0.200 times "the intake diameter D. As is clear from the figure, the most stable air-fuel ratio characteristic is obtained when the length of the first air hose 33 is about 400 mm. That is, it can be said that the value of “400 mm” is substantially equal to the value obtained by multiplying the intake length L by twice the value of the ratio of the inner diameter of the first air hose 33 to the intake diameter D, as described above. From the above,
When the inner diameter of the first air hose 33 is α times the intake diameter D, the most stable air-fuel ratio characteristics can be obtained when the length is 2α times the intake length L.

Third, FIGS. 5 and 6 show the results obtained when the inner diameter and length of the second air hose 34 are variously changed. That is, in FIG. 5, the length of the second air hose 34 is changed, and in FIG. 6, the air-fuel ratio A / A with respect to the engine speed NE when the inner diameter of the second air hose 34 is changed.
The relation of F is shown. However, in FIG. 5, the resonator 3
2 is "1000 cc" and the first air hose 3
3 is fixed at "13 mm" and the length is set at "450 mm", and the inner diameter of the second air hose 34 is set at "13 m".
m ”. As is clear from FIG. 5, the longer the length of the second air hose 34, the more the relationship between the engine speed NE and the air-fuel ratio A / F becomes more stable. Particularly, when the length of the second air hose 34 is "1000 m
m "or more, the air-fuel ratio characteristics are stable, and when it is less than m, the engine speed NE is" 1000 rpm ".
The air-fuel ratio A / F in the following became extremely lean. That is, if the length of the second air hose 34 is equal to or more than a value obtained by multiplying the intake length L by a value four times the ratio of the inner diameter of the second air hose 34 to the intake diameter D, a stable air-fuel ratio characteristic is obtained. I can say.

In FIG. 6, the volume of the resonator 32 is set to "1000 cc", the inner diameter of the first air hose 33 is fixed to "13 mm", the length is fixed to "450 mm", and the length of the second air hose 34 is fixed. Sa "1400m
m ”. As is clear from FIG. 6, the smaller the inner diameter of the second air hose 34, the more the relationship between the engine speed NE and the air-fuel ratio A / F becomes more stable.
That is, by setting the inner diameter of the second air hose 34 small, it is possible to set the length of the second air hose 34 small to obtain stable air-fuel ratio characteristics. Also, from the above, the second air hose 34 is
When the inner diameter is β times the intake diameter D, it can be said that stable air-fuel ratio characteristics can be obtained when the length is 4β times or more the intake length L.

As is clear from the above experimental results, according to this embodiment, the volume of the resonator 32 is set to at least twice the displacement per cylinder of the LPG internal combustion engine. Also,
The first air hose 33 has an inner diameter that is α times the average inner diameter of the intake passage 1 and a length that is 2α times the length from the air cleaner 2 to the venturi 4 of the intake passage 1. further,
The second air hose 34 has an inner diameter that is β times the average inner diameter of the intake passage 1 and a length that is at least 4β times the length from the air cleaner 2 to the venturi 4 of the intake passage 1. Therefore, stable air-fuel ratio characteristics can be reliably obtained in any operation region including a high load region.

It should be noted that the present invention is not limited to the above-described embodiment, and may be carried out as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In the above-described embodiment, the configuration in which the cool air duct 3 is provided at the upstream end of the air cleaner 2 is adopted. However, the configuration in which the cool air duct 3 is not provided may be adopted.

(2) In the above embodiment, the resonator 32 has a rectangular cylindrical shape (a rectangular parallelepiped shape). However, the resonator 32 may have any shape. That is, as a result of conducting experiments by changing the shape of the resonator 32 variously, the air-fuel ratio
It has been found that even if there is a difference in the shape of, there is almost no effect. Therefore, the shape may be, for example, a cylindrical shape (cylindrical shape) or the like.

(3) A silencing intake resonator may be provided between the air cleaner 2 and the venturi 4 in the intake passage 1 in the above embodiment.

[0040]

As described above in detail, according to the pressure control device of the vaporizer of the present invention, the pressure control device is provided in the middle of the intake passage with the air chamber opposed to the secondary pressure control chamber of the regulator with the membrane interposed therebetween. An air hose connecting the clean side of the air cleaner was provided, and a resonator was provided on the way. The volume of the resonator is set to be about twice or more of the displacement per cylinder of the internal combustion engine. Further, the inside diameter of the first air hose connecting the air chamber and the resonator was set to α times the average inside diameter of the intake passage, and the length was set to 2α times the length from the air cleaner to the venturi in the intake passage. Further, the inner diameter of the second air hose connecting the resonator and the clean side of the air cleaner is set to β times the average inner diameter of the intake passage, and the length is set to at least 4β times the length from the air cleaner to the venturi in the intake passage. And Therefore, an excellent effect that a stable air-fuel ratio characteristic can be obtained without being affected by a temperature change in any operation region including a high load region is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a vaporizer pressure adjusting device according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the engine speed and the air-fuel ratio when the volume of the resonator is changed in one embodiment.

FIG. 3 is a graph showing the relationship between the engine speed and the air-fuel ratio when the length is changed while the inner diameter of the first air hose is kept constant in one embodiment.

FIG. 4 is a graph showing the relationship between the engine speed and the air-fuel ratio when the length is changed while the inner diameter of the first air hose is constant in one embodiment.

FIG. 5 is a graph showing the relationship between the engine speed and the air-fuel ratio when the length is changed while keeping the inner diameter of the second air hose constant in one embodiment.

FIG. 6 is a graph showing the relationship between the engine speed and the air-fuel ratio when the inner diameter is changed while keeping the length of the second air hose constant in one embodiment.

[Explanation of symbols]

1 ... intake passage, 2 ... air cleaner, 4 ... venturi, 6
... regulator, 14 ... primary pressure regulating chamber, 16 ... second diaphragm as membrane, 17 ... secondary pressure regulating chamber, 18 ... secondary air chamber as air chamber, 21 ... main fuel hose, 31 ...
Air hose, 32 ... Resonator, 33 ... First air hose, 34 ... Second air hose.

Claims (1)

(57) [Claims] Claims: 1. A fuel made of liquefied petroleum gas is vaporized by a predetermined heat source in a primary pressure regulating chamber, and the vaporized fuel is regulated in a secondary pressure regulating chamber to near atmospheric pressure.
A regulator for supplying to a venturi in an intake passage via a main fuel hose and supplying to an internal combustion engine; and an air chamber opposed to a secondary pressure regulating chamber of the regulator with a membrane interposed therebetween and provided in the middle of the intake passage. An air hose connecting a clean side of an air cleaner, and a pressure regulator for a vaporizer including a resonator provided in the middle of the air hose. The inner diameter of the first air hose connecting the air chamber and the resonator is set to α times the average inner diameter of the intake passage, and the length is from the air cleaner to the venturi in the intake passage. And the inner diameter of a second air hose connecting the resonator and the clean side of the air cleaner is set to 2α times. With a beta times the average internal diameter of the intake passage, the length, and said intake passage said to venturi length of 4β times from an air cleaner (but, alpha, beta are both positive values)
A pressure adjusting device for a vaporizer.