JP3952229B2 - Membrane vaporizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention suppresses a rapid increase in the amount of fuel supplied to the engine when the fuel accumulates inside the intake passage of the carburetor during the idling operation of the internal combustion engine and the attitude of the engine changes. The present invention relates to a membrane type vaporizer that is highly effective.
[0002]
[Prior art]
Engines for portable working machines such as power saws and brush cutters are required to be compact, lightweight, high output and capable of operating in all positions. Therefore, in general is air-cooled two-stroke engine including a film type vaporizer is employed, in recent years has Tsu name as well be employed 4-stroke engine for exhaust gas countermeasures. Since the ambient temperature becomes very high during engine operation, a synthetic resin with better heat insulation than metal is provided between the carburetor and the engine inlet to suppress evaporation of fuel inside the carburetor. Insulator pipes are connected.
[0003]
By the way, in the conventional membrane type carburetor, when the engine is cold started or idling, the fuel is not sufficiently atomized or vaporized. Therefore, the fuel sucked into the intake passage of the carburetor remains in a liquid state inside the heat insulation pipe. it may become Tsu reservoir to. A large amount of fuel Tsu reservoir in the interior of the heat-insulated pipe is, and is rapidly supplied Tsu accompanied to the institutions to change in the attitude of the portable working machine, the air-fuel mixture becomes suddenly rich, engine is to be stopped.
[0004]
As shown in FIG. 6, in the conventional rotary throttle valve type carburetor, since the opening of the throttle valve 47 is small when the engine is idling, the flow of the air-fuel mixture is small. In addition, the flow of the air-fuel mixture in the intake passage 16 of the carburetor or the intake passage 63a of the heat insulating pipe 63 is fast, but a large amount of the air-fuel mixture particularly exists in the closed portion 16b opposite to the open portion 16a of the throttle valve 47 at the outlet of the intake passage 16. As shown by the point, the stagnation of the air-fuel mixture tends to occur. When the air-fuel mixture in the closed part 16b of the throttle valve 47 at the outlet of the intake passage 16 from staying, it is the fuel from adhering to Tsu Na in the liquid.
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has a membrane-type vaporization that prevents fuel from accumulating inside the intake passage of an engine carburetor and prevents the engine from being stopped when the engine is tilted during idling of the engine. Is to provide a vessel.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the configuration of the present invention is provided with a suction inlet to the intake passage of the carburetor body adjacent to the open portion of the outlet side of the idle position of the rotary throttle valve, the outlet in the idle position of the rotary throttle valve adjacent the side closed part provided an intake outlet to an intake passage of the carburetor body, characterized in that the said intake outlet and the intake inlet communicating with the tube.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the open portion and the closed portion of the rotary throttle valve at the outlet of the intake passage are communicated by a passage. The intake air introduced into the passage from the open portion of the rotary throttle valve is blown out to the closed portion of the rotary throttle valve through the passage, and the air-fuel mixture stagnating in the closed portion is blown to the downstream side of the intake passage, resulting in stagnation of the air-fuel mixture. To prevent.
[0008]
In the present invention, a flexible tube with a closed end is connected to the closed portion of the rotary throttle valve at the outlet of the intake passage. In the intake stroke of the engine, the intake pressure at the closed portion of the outlet of the intake passage becomes lower than the atmospheric pressure inside the tube, and the tube is crushed. At this time, the fuel stagnating in the closed portion is pushed away to the downstream side of the intake passage by the air from the tube. On the other hand, in the other strokes of the engine, the intake air at the closed portion of the outlet of the intake passage is sucked into the tube, and the intake pressure gradually decreases as the tube expands. Thus, the intake pressure in the closed portion of the outlet of the intake passage is close to the intake pressure in the open portion by the next intake stroke.
[0009]
【Example】
As shown in FIG. 1, the main body 15 of the membrane type carburetor is connected to an intake port (not shown) of the engine via a heat insulating pipe 63 and a gasket 62. The illustrated carburetor is of a known rotary throttle valve type, and a cylindrical portion 57 orthogonal to the intake passage 16 is formed in the main body 15, and a throttle valve 47 having a throttle hole 47 b is rotatable in the cylindrical portion 57. And it is inserted so that raising and lowering is possible. The throttle valve lever 51 is coupled to the valve shaft 47 a that protrudes upward from the throttle valve 47 through the lid plate 53 that closes the cylindrical portion 57, and the lower cam surface 51 a of the throttle valve lever 51 and the follower 52 of the lid plate 53. The cam mechanism is composed of the above. When the throttle valve 47 is rotated in the acceleration direction against the force of the spring 54 by the throttle valve lever 51, the opening degree at which the throttle hole 47b communicates with the intake passage 16 increases, and from the shaft portion 47a of the throttle valve 47. The needle valve 55 protruding into the throttle hole 47b and inserted into the fuel nozzle 56 rises from the injection hole 56a of the fuel nozzle 56, and the opening degree of the injection hole 56a increases. The stationary fuel nozzle 56 is fitted and supported in a hole 58 at the bottom of the main body 15 and communicates with the constant pressure fuel chamber 25 of the fuel metering mechanism A through a jet 59 and a check valve 66.
[0010]
A fuel pump 11 and a fuel metering mechanism A are configured in the lower part of the carburetor body 15. That is, in the fuel pump 11, the intermediate body 49 is coupled to the lower end surface of the main body 15 with the membrane 10 interposed therebetween, the pulsation pressure chamber 8 accommodating the spring 8 a is disposed above the membrane 10, and the pump chamber 9 is disposed below the membrane 10. Each is partitioned. In the four-stroke engine, the fuel pump 11 introduces the pulsating intake negative pressure of the intake passage 63a of the heat insulating pipe 63 into the pulsating pressure chamber 8 through the inlet 61a and the passage 61. In the two-stroke engine, the pulsating pressure of the crank chamber is introduced into the pulsating pressure. By introducing the fuel into the chamber 8, the fuel in the fuel tank 37 is sucked into the pump chamber 9 through the passage 38, the inlet 13, the check valve 12 and the passage 12 a, and discharged to the passage 7 a through the passage 12 a and the check valve 7.
[0011]
The fuel quantification mechanism A joins the cover 30 a with the membrane 29 sandwiched between the lower end surface of the intermediate body 49 and partitions the constant pressure fuel chamber 25 and the atmospheric chamber 30. A lever 28 is rotatably supported by a shaft 27 inside the constant pressure fuel chamber 25. One end of the lever 28 is engaged with the inflow valve 2, and the inflow valve 2 is configured to contact the valve seat at the end of the passage 7 a under the force of the spring 24. The other end of the lever 28 can be brought into contact with the membrane 29, and when the force of atmospheric pressure acting on the lower surface of the membrane 29 becomes larger than the force of the spring 24, the lever 28 rotates clockwise and the inflow valve 2 is rotated. Is opened, and fuel is supplied from the passage 7a to the constant pressure fuel chamber 25. Thus, the constant pressure fuel chamber 25 holds a predetermined amount of fuel at a predetermined pressure. The fuel in the constant pressure fuel chamber 25 is supplied to the intake passage 16 through the check valve 66, the jet 59, the injection hole 56a of the fuel nozzle 56, and the throttle hole 47b.
[0012]
Such a membrane type carburetor is known from, for example, Japanese Patent Application Laid-Open No. 59-20551, and the fuel sent to the constant pressure fuel chamber 25 by the fuel pump 11 can be used in any position of the engine (for example, in a rollover state). The engine is supplied to the intake passage 16 from the nozzle hole 56a of the fuel nozzle 56 by the intake negative pressure of the engine.
[0013]
As shown in FIGS. 1 and 2, from a metal having a large thermal conductivity, such as aluminum, having an inner diameter smaller than that of the heat insulating pipe 63 having an intake passage 63 a connected between the intake port of the engine and the carburetor body 15. A ring member 26 is disposed at the outlet of the intake passage 16 of the carburetor. Therefore, a large-diameter cylindrical portion 26 a is formed at the outlet end of the intake passage 16 of the carburetor body 15, the ring member 26 is fitted into the large-diameter cylindrical portion 26 a, and connected to the heat insulating pipe 63 via the gasket 62. To do. In the illustrated embodiment, the end flange of the carburetor body 15, the gasket 62, and the heat insulating pipe 63 are fastened to the engine wall by a plurality of through bolts (see the through bolt 60 in FIG. 6). The inner diameter of the heat insulating pipe 63 is the same as the inner diameter of the intake passage 16 of the carburetor body 15. Preferably, the ring member 26 is provided with an intake passage having a smaller diameter than the intake passage 16.
[0014]
According to the present invention, in order to prevent fuel from accumulating inside the intake passage 16 during idling of the engine, one of the intake air at the outlet 16a of the outlet of the intake passage 16, that is, the outlet of the throttle hole 47b of the throttle valve 47, is reduced. Is guided to the closed portion 16b at the outlet of the intake passage 16 to eliminate the stagnation of the air-fuel mixture in the closed portion 16b. Therefore, the ring member 26 is provided with a radial intake port 31a adjacent to the open portion 16a, and a radial intake port 33a adjacent to the closed portion 16b. As shown in FIG. 2, the intake inlet 31 a and the intake outlet 33 a are communicated by a groove passage 32 a provided on the upper outer peripheral surface of the ring member 26.
[0015]
In the embodiment shown in FIGS. 3 and 4, the pipe 42 is used in place of the ring member 26, and the intake inlet 41a and the intake outlet 43a are communicated with each other. An intake inlet 41a is provided adjacent to the open portion 16a, and an intake outlet 43a is provided adjacent to the closed portion 16b on the peripheral wall of the intake passage 16 of the carburetor body 15, and the end of the pipe 42 is connected to the intake inlet 41a and the intake outlet 43a. The portions 41 and 43 are respectively fitted, and the intake air at the outlet portion 16a of the intake passage 16, that is, the intake air at the outlet of the throttle hole 47b of the throttle valve 47 is passed through the pipe 42 to the closed portion 16b at the outlet of the intake passage 16. It was made to blow out.
[0016]
Next, the operation of the membrane type vaporizer according to the present invention will be described. When the engine is idling, the throttle valve 47 is in the state shown in FIG. 3, and when the intake air sucked into the intake passage 16 passes through the throttle hole 47 b of the throttle valve 47, fuel is injected from the nozzle hole 56 a of the fuel nozzle 56. The air is sucked, flows from the throttle hole 47b to the open portion 16a at the outlet of the intake passage 16, and further flows to the engine through the heat insulating pipe 63.
[0017]
When the engine is idling, the flow of the air-fuel mixture is slow. Therefore, the air-fuel mixture stays in the closed portion 16b of the outlet of the intake passage 16, which is a so-called dead space, and only fuel having a higher specific gravity than intake air tends to accumulate. However, in the embodiment shown in FIGS. 1 and 2, the ring member 26 having the groove passage 32a is disposed at the open portion 16a of the intake passage 16, that is, the outlet of the throttle hole 47b, so that the open portion of the intake passage 16 from the throttle hole 47b. Part of the intake air flowing into the ring member 26 enters the intake inlet 31a of the ring member 26 and flows through the groove passage 32a from the intake outlet 33a to the closed portion 16b of the intake passage 16, so that the closed portion is caused by the flow of intake air from the intake outlet 33a. The air-fuel mixture of 16b is blown to the downstream side of the intake passage 16, and the accumulation of fuel is suppressed.
[0018]
3 and 4, the intake inlet 31a provided in the open portion 16a of the outlet of the intake passage 16 and the intake outlet 33a provided in the closed portion 16b are communicated by the pipe 42. Part of the intake air flowing from the throttle hole 47b to the open portion 16a of the intake passage 16 enters the pipe 42 through the intake inlet 31a and flows from the intake outlet 33a to the closed portion 16b of the intake passage 16, so that the intake air from the intake outlet 33a As a result of this flow, the air-fuel mixture in the closed portion 16b is blown to the downstream side of the intake passage 16, and fuel accumulation is suppressed. Were it to Tsu, the idle operation of the engine, sump fuel closed part 16b of the conventional outlet of the intake passage 16 as, Tsu names in rich mixture in Tsu accompanied fuel Tsu sump to vibration and posture change of the engine The problem that the engine stops at once and then stops is solved.
[0019]
In the embodiment shown in FIG. 5, the tube 44 is fitted into a through hole 43b provided in the closed portion 16b of the outlet of the intake passage 16, and the proximal end portion of the flexible tube 46 having the distal end portion 46a closed is connected to the tube. 44 and is fastened by a band 45.
[0020]
Since the intake air flow at the outlet of the intake passage 16 is fast in the intake stroke of the engine, the intake pressure in the closed portion 16b is lower than the atmospheric pressure inside the tube 46, and the tube 46 is crushed. At this time, the fuel stagnating in the closed portion 16 b is pushed to the downstream side of the intake passage 16 by the air from the tube 46. On the other hand, in the other strokes of the engine, the flow of the intake air at the outlet of the intake passage 16 becomes slow, and the closed portion 16b is almost close to the atmospheric pressure. At this time, the intake air of the closed portion 16b at the outlet of the intake passage 16 is sucked into the tube 46, and the tube 46 expands (returns to a normal shape). At the same time, the intake pressure of the closed portion 16b gradually decreases. Thus, the intake pressure of the closed portion 16b at the outlet of the intake passage 16 is close to the intake pressure of the open portion 16a by the next intake stroke. The length or volume of the tube 46 is experimentally determined in advance. If the tube 46 is short, the fuel stagnating in the closed portion 16b due to the pulsation of the intake negative pressure of the engine is sucked into the inside of the tube 46. However, if the tube 46 is lengthened, the fuel stagnating in the closed portion 16b due to the pulsation of the intake negative pressure of the engine. Is blown to the downstream side of the intake passage 16 to eliminate fuel accumulation .
[0021]
【The invention's effect】
As described above, the present invention provides an intake inlet in the intake passage of the carburetor body adjacent to the open portion on the outlet side in the idle position of the rotary throttle valve, and is adjacent to the closed portion on the outlet side in the idle position of the rotary throttle valve. As a result, an intake outlet is provided in the intake passage of the carburetor main body, and the intake inlet and the intake outlet are communicated by a pipe, so that fuel accumulates in the closed portion of the rotary throttle valve at the intake passage outlet during idle operation of the engine. It becomes difficult.
[0022]
In the present invention, the open portion intake outlet on the outlet side at the idle position of the rotary throttle valve of the carburetor and the closed portion outlet are communicated by a pipe, so that the rotary throttle valve is fully opened. There is not much influence on the flow of the air-fuel mixture, and the engine output does not decrease.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a membrane type vaporizer according to a first embodiment of the present invention.
FIG. 2 is a front sectional view of a ring member disposed in the same membrane type vaporizer.
FIG. 3 is a plan sectional view showing the main part of a membrane type vaporizer according to a second embodiment of the present invention.
FIG. 4 is a front sectional view of the same membrane type vaporizer.
FIG. 5 is a plan sectional view showing the main part of a membrane type vaporizer according to a third embodiment of the present invention.
FIG. 6 is a plan sectional view showing a main part of a conventional membrane type vaporizer.
[Explanation of symbols]
A: Fuel metering mechanism 2: Inflow valve 7: Check valve 7a: Passage 8: Pulsation pressure chamber 9: Pump chamber 10: Membrane 11: Fuel pump 12: Check valve 12a: Passage 15: Vaporizer body 16: Intake passage 16a: Open portion 16b: Open portion 25: Constant pressure fuel chamber 26: Ring member 26a: Large diameter cylindrical portion 27: Shaft 28: Lever 29: Membrane 30: Atmospheric chamber 30a: Cover 31a: Inlet inlet 32a: Groove passage 33a: Inlet air Outlet 37: Fuel tank 41a: Inlet inlet 42: Pipe 43a: Inlet outlet 43b: Through hole 45: Band 46: Pipe 47: Throttle valve 47b: Throttle hole 49: Intermediate 51: Throttle valve lever 51a: Cam surface 52: Follower 53: Cover plate 54: Spring 55: Needle valve 56: Fuel nozzle 56a: Injection hole 57: Cylindrical part 59: Jet 62: Gasket 63: Heat insulation pipe 63a: Intake passage 66: Check

Claims (2)

The inlet passage to the intake passage on the outlet side of the carburetor body adjacent the open portion provided at the idle position of the rotary throttle valve, the carburetor body adjacent the closed part of the outlet side in the idle position of the rotary throttle valve A membrane type vaporizer characterized in that an intake outlet is provided in an intake passage, and the intake inlet and the intake outlet are communicated with each other by a pipe. A ring member having an inner diameter smaller than that of the heat insulating pipe for connecting the carburetor to the intake port of the engine is fitted to the downstream side of the rotary throttle valve of the intake passage of the carburetor body, and the idle position of the rotary throttle valve The ring member is provided with an intake inlet adjacent to the outlet side open portion of the rotary throttle valve, and the ring member is provided with an intake outlet adjacent to the outlet side closed portion of the rotary throttle valve at the idle position. A membrane type vaporizer characterized in that an intake outlet communicates with a groove passage provided on an outer peripheral surface of the ring member.

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