JP3100094B2 - Liquefied petroleum fuel supply system for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for an internal combustion engine mounted on a portable working machine such as a brush cutter, and more particularly, to a method for converting liquefied petroleum fuel (LPG) filled in a small liquefied gas container (fuel cylinder) into liquid. The present invention relates to a liquefied petroleum fuel supply device which is taken out as it is, heated and vaporized, and then supplied to an internal combustion engine via a mixer.

[0002]

2. Description of the Related Art In a liquefied petroleum fuel supply apparatus of Japanese Patent Application No. 2-220440 filed by the present applicant, heat of an exhaust muffler of an engine is used for a heater for heating and vaporizing liquid fuel. However, the vaporization efficiency of the liquid fuel is poor until the engine warms up, and it takes a considerable amount of time before the engine can operate at full load. Further, since the heat capacity of the exhaust muffler is small, even when the engine is warmed up, the heat of the exhaust muffler may not sufficiently heat the heater. In particular, butane gas as liquefied petroleum fuel (LPG) has a high vaporization temperature (−7 ° C.). Therefore, when the outside air temperature becomes about 0 ° C. or lower, the fuel does not vaporize and cannot be used as engine fuel.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a liquefied petroleum fuel for an internal combustion engine which can be used as an engine fuel by effectively vaporizing butane gas which could not be used at low temperatures. To provide a supply device.

[0004]

In order to achieve the above object, according to the present invention, the liquid fuel in the liquefied gas container is provided such that the fuel suction pipe always projects below the liquid level of the liquefied gas container during operation of the internal combustion engine. In the liquefied petroleum fuel supply device for an internal combustion engine, the liquefied gas container is sent to a primary pressure regulator, vaporized, and then supplied to the internal combustion engine through a secondary pressure regulator and a mixer integrated with the secondary pressure regulator. A metal pipe connecting the pressure regulator and the primary pressure regulator is curved in a U-shape, and a vaporizer for supplying liquid fuel from below and discharging gas fuel from above is provided in parallel with a cooling fin of a cylinder body and cooling air for cooling an internal combustion engine. Is disposed so as to bypass a portion downstream of the cylinder body.

[0005]

The cooling air for cooling the engine is heated when passing through the outer wall of the cylinder body, and the heated cooling air heats the vaporizer at the most downstream side. The fuel suction pipe of the liquefied gas container always projects below the liquid level, and the liquid fuel of the liquefied gas container flows from the fuel suction pipe to the vaporizer in almost liquid state during operation of the engine at a low temperature. The liquid fuel is heated and vaporized by the vaporizer, and is drawn into the intake passage of the mixer via the primary pressure regulator and the secondary pressure regulator.

[0006]

1 is a block diagram of a liquefied petroleum fuel supply system for an internal combustion engine according to the present invention. The two-stroke engine B mounted on the portable working machine includes a cylinder body 2 having a large number of cooling fins.
0, a crankcase 23 is connected to the top of the crankshaft, and a recoil starter 24 for starting the engine is provided at the front end of the crankshaft (not shown) via a clutch. And a blower.
The blower is housed inside a fan case 22 which is connected to the cylinder body 20 and the back of the crankcase 23, sucks outside air from the rear end side of the crankshaft, and sends it to the lower side, that is, to the outer wall of the cylinder body 20. A lower end portion of the cylinder body 20 is provided with an ignition plug 19 and is covered with a cover 18 (see FIG. 2) integrated with the fan case 22. Accordingly, the cooling air from the blower is sent from the back of the cylinder body 20 to the front through the space between the cooling fins. The intake port on the left side wall of the cylinder body 20 is connected to the mixer C through the heat insulating pipe 17.
The exhaust port on the right side wall is coupled with the exhaust muffler 21.

A retainer 2 for a liquefied gas container (fuel cylinder) 3 is disposed above the engine B. The retainer 2 has a fuel cock 5 and an outlet 6 on the lower end wall. The liquefied gas container 3 used for a household stove or the like is inverted and elastically mounted between the upper end wall and the lower end wall of the retainer 2 so that the fuel suction pipe 3a projects below the liquid level. When the cock 5 is opened, the liquid fuel in the liquefied gas container 3 is supplied to the fuel suction pipe 3a, the fuel cock 5,
It is supplied to the mixer C of the engine via the outlet 6. However, when the outside air temperature is low (about 10 ° C. or less), most of the fuel at the outlet 6 is in a liquid state.

According to the present invention, the vaporizer 7 for vaporizing the fuel from the liquefied gas container 3 is provided on the front wall of the cylinder body 20 of the engine B (on the side opposite to the blower mounting portion). The vaporizer 7 is formed of a metal tube curved in a U-shape, and is disposed substantially horizontally at the front of the cylinder body 20.

An inlet 7a at the lower end of the vaporizer 7
Is connected to the outlet 6 of the liquefied gas container 3 via the pipe 6a. The outlet 7b at the upper end of the vaporizer 7 is connected to the inlet 12 of the primary pressure regulator A. Primary pressure regulator A is box 1
The diaphragm 10 is sandwiched between the fuel cell 11 and the bottom plate 13a, the fuel chamber 11 is partitioned on the upper side, and the atmosphere chamber is partitioned on the lower side. One end of a lever supported on the wall of the fuel chamber 11 by the support shaft 14 is a valve body 8. The other end is engaged with a rod connected to the diaphragm 10, and the valve body 8 is urged to open the inlet 12 under the force of the spring 9.

The fuel chamber 11 can communicate with the constant pressure fuel chamber 38 via the outlet 12a, the pipe 15, the inlet passage 44a of the secondary pressure regulator E integrated with the mixer C, and the valve body 44. In the mixer C, the left end of the intake passage 36 passing through the main body 35 is connected to an air purifier (not shown), and the right end is connected to the heat insulating pipe 17. The main body 35 has a well-known piston-type throttle valve 37 that protrudes into the intake passage 36 on the upper wall and controls the amount of fuel and air to the engine. The throttle valve 37 is provided with a needle valve protruding into a fuel passage 37a described later. When the throttle valve 37 is slid up and down by an acceleration lever (not shown), the amount of air in the intake passage 36 is adjusted, and at the same time, the needle valve slides. And the amount of fuel drawn from the constant pressure fuel chamber 38 into the intake passage 36 via the fuel passage 37a is adjusted.

The secondary pressure regulator E includes a lower wall and a bottom plate 39 of the main body 35.
The diaphragm 40 is sandwiched between the constant pressure fuel chamber 3 and the upper side.
8, and an atmosphere chamber is defined on the lower side. The lever 41 supported by the support shaft 42 in the fuel constant pressure chamber 38 has a left end engaged with the diaphragm 40 and a right end engaged with the valve body 44, respectively. The valve body 44 receives the force of the spring 43 and closes the inlet passage 44a. However, when the fuel in the constant pressure fuel chamber 38 decreases and the fuel pressure decreases, the lever 41 is rotated clockwise by the diaphragm 40 that receives atmospheric pressure. The valve body 44 opens the inlet passage 44a to supply fuel to the constant pressure fuel chamber 38. The constant pressure fuel chamber 38 opens the fuel passage 37 a to the intake passage 36.

The intake passage 36 is opened with an oil passage 34 for lubricating the engine. The oil passage 34 communicates with a transparent tube 33 connected to the upper wall of the main body 35. The transparent pipe 33 supports the valve box 32 of the oil amount adjustment valve D. The needle valve 31 screwed and supported by the valve chamber 32a of the valve box 32 adjusts the oil flow from the lower end outlet of the valve chamber 32a to the transparent pipe 33. The valve chamber 32a is supplied with oil from an oil tank 61 through an outlet pipe 63 and a pipe 45 under pressure. Therefore, pressurized air is supplied to the oil tank 61 from the air pump F.

The air pump F has a pair of upper and lower boxes 53, 60.
The diaphragm 58 is sandwiched between the pulsating pressure introduction chambers 5 on the upper side.
5, and a pump chamber 59 is defined on the lower side. The pulsation pressure introduction chamber 55 supplies the pulsation pressure of the crank chamber to the pipe 47 and the passage 54.
Supplied via The pump chamber 59 can communicate with the atmosphere inlet 57 through the check valve 56, and can communicate with the oil tank 61 through the check valve 51, the outlet 51 a, the pipe 46, and the inlet 62. The outlet 51a is opened to the atmosphere via a jet 52, and the upper limit pressure of the oil tank 61 is set.

Next, the operation of the liquefied petroleum fuel supply device for an internal combustion engine according to the present invention will be described. During the operation of the engine B, the cooling air sent from the blower inside the fan case 22 to the cylinder body 20 hits the cover 18 and cools the cylinder body 20 when flowing substantially horizontally from the back to the front of the engine. The vaporizer 7 heats as it becomes hot and is released outside the cover 18, ie, to the front of the engine. Therefore, the liquid fuel is heated by the vaporizer 7 and vaporized,
The fuel enters the fuel chamber 11 of the primary pressure regulator A from the inlet 12. When the fuel pressure in the fuel chamber 11 becomes higher than a predetermined value, the valve body 8 closes the inlet 12 and keeps the fuel pressure in the fuel chamber 11 substantially constant.

The fuel in the fuel chamber 11 is supplied to the outlet 12a, the pipe 15,
The fuel enters the constant pressure fuel chamber 38 of the secondary pressure regulator E via the inlet passage 44a and the valve body 44. When the fuel pressure in the constant-pressure fuel chamber 38 increases, the diaphragm 40 is pushed down, the lever 41 receiving the force of the spring 43 rotates following the diaphragm 40, the valve body 44 closes, and the fuel pressure in the constant-pressure fuel chamber 38 decreases. Keep almost constant. The fuel in the constant pressure fuel chamber 38 is mixed with the air in the intake passage 36 through the passage 37a, and is further mixed with the oil from the oil passage 34 and is sucked into the combustion chamber of the engine.

During the operation of the engine B, the pulsating pressure in the crank chamber causes the diaphragm 58 in the pulsating pressure introducing chamber 55 to vibrate up and down through the pipe 47 and the passage 54. Therefore, the atmosphere is at the entrance 5
7. The liquid is sucked into the pump chamber 59 through the check valve 56, and is sent to the oil tank 61 through the check valve 51, the outlet 51a, the pipe 46, and the inlet 62 to pressurize the oil. The oil in the oil tank 61 is supplied to the outlet pipe 63,
The oil enters the valve chamber 32 a of the oil amount adjusting valve D via the pipe 45, and is further supplied to the intake passage 36 via the transparent pipe 33 and the oil passage 34.

In the embodiment shown in FIG. 2, the case where the engine B is mounted upright on the portable work machine is shown, and each member is denoted by the same reference numeral as in FIG. The liquefied gas container 3 is disposed higher than the vaporizer 7, and the liquid fuel in the liquefied gas container 3 flows into the vaporizer 7 from the lower end of the vaporizer 7 by its own weight, is heated and vaporized, and becomes primary from the upper end. After being mixed with air and oil through the pressure regulator A, the secondary pressure regulator E, and the mixer C, it is sucked into the combustion chamber of the engine B.

In the embodiment shown in FIGS. 1 and 2, the liquefied gas container 3 is disposed vertically above the engine B, but the present invention is not limited to this. As shown, the liquefied gas container 3 may be disposed horizontally, and if the liquefied gas container 3 is disposed above the vaporizer 7, the liquid fuel in the liquefied gas container 3 flows to the vaporizer 7 by its own weight.

[0019]

According to the present invention, the fuel taken out in the liquid phase is converted into a gaseous phase inside the ventrizer composed of a metal pipe and sent to the regulator, so that the fuel amount required by the engine can be changed to the gaseous phase. It is very safe because there is no need to heat the fuel cylinder and the regulator. Since only the gas phase fuel always enters the regulator, the controllability of the fuel is stabilized.

Since fuel is taken out of the fuel cylinder in the liquid phase, more fuel can be taken out than in the gas phase, and an engine with a higher output can be operated than an engine that can be operated in the gas phase.

Since the liquid fuel in the liquefied gas container is supplied to the vaporizer and heated by the cooling air of the engine, the fuel vaporization efficiency is high, and the full load operation can be performed for a long time without running out of fuel.

Since the high-temperature cooling air after the cooling of the engine is positively used, the liquid fuel can be quickly vaporized by a small vaporizer, and a fuel amount suitable for the operating conditions of the engine can be supplied.

The amount of cooling air of the engine is proportional to the load of the engine, and the amount of cooling air heated to the vaporizer increases at full load operation of the engine. In light load operation, the amount of heated cooling air to the vaporizer is reduced, so that there is no risk of fuel being overheated and the fuel is safe.

By arranging the discharge port of the liquefied gas container above the primary pressure regulator, the liquid fuel flows to the vaporizer by its own weight even when the outside air temperature is low, so that the liquid fuel can be smoothly vaporized.

When the engine is inverted, both the cylinder body and the vaporizer are on the lower side. By arranging the liquefied gas container horizontally or vertically near the crankcase,
As the whole outer shape becomes more compact and the fuel in the liquefied gas container flows to the vaporizer by its own weight even in cold weather,
Regardless of the outside air temperature, for example, the evaporation temperature of butane gas (-
The liquefied butane gas can be used even at an outside air temperature of 7 ° C. or lower.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a liquefied petroleum fuel supply device for an internal combustion engine according to the present invention.

FIG. 2 is a front sectional view of a liquefied petroleum fuel supply device according to a modified embodiment of the present invention.

FIG. 3 is a front sectional view of a liquefied petroleum fuel supply device according to a modified embodiment of the present invention.

FIG. 4 is a front sectional view of a liquefied petroleum fuel supply device according to a modified embodiment of the present invention.

[Explanation of symbols]

A: Primary pressure regulator B: Internal combustion engine C: Mixer E: Secondary pressure regulator 3: Liquefied gas container 3a: Fuel suction pipe 7: Vaporizer 20: Cylinder body 36: Intake passage

Continuing on the front page (72) Inventor Nobuyuki Kuroki 2- 925 Shin Maruko Higashi, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Walbrofer East Co., Ltd. (72) Inventor Noboru Saito 2-925 Shin-Maruko Higashi, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Within the Walblofer East (56) References Real Opening Sho 63-21753 (JP, U) Real Opening Sho 62-116157 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 21/06 F02B 67/00 F02M 21/02 F02M 31/16

Claims (2)

(57) [Claims] The liquid fuel in a liquefied gas container, in which a fuel suction pipe always projects below the liquid level of a liquefied gas container during operation of an internal combustion engine, is sent to a primary pressure regulator, and is vaporized before being connected to a secondary pressure regulator. , 2
In a liquefied petroleum fuel supply device for an internal combustion engine supplied to an internal combustion engine via a secondary pressure regulator and an integrated mixer, a metal pipe connecting the liquefied gas container and the primary pressure regulator is bent into a U-shape, and A vaporizer that supplies fuel from below and discharges gaseous fuel from above is arranged in parallel with the cooling fins of the cylinder body and so as to bypass a portion downstream of the cylinder body of cooling air for cooling the internal combustion engine. A liquefied petroleum fuel supply device for an internal combustion engine, characterized by: 2. The liquefied gas container having a cylindrical shape is disposed vertically in an internal combustion engine and above the vaporizer, and liquid fuel is supplied to the vaporizer from a fuel outlet provided at a lower end of the liquefied gas container. The liquefied petroleum fuel supply device for an internal combustion engine according to claim 1.