JP4629273B2 - Vaporizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly comprises a carburetor for supplying fuel to a general-purpose engine, more specifically, a butterfly-shaped throttle valve and a single fuel system for delivering fuel measured according to its opening / closing operation. The present invention relates to a vaporizer capable of supplying a high-concentration air-fuel mixture at start-up.
[0002]
[Prior art]
As a carburetor for supplying fuel to a two-cycle or four-cycle general-purpose engine, a fixed venturi type butterfly-shaped throttle valve, a main system, and a low-speed system as described in JP-A-55-69748 And a variable venturi type cylinder-shaped sliding throttle valve and a measuring needle provided on the sliding throttle valve as described in Japanese Utility Model Publication No. 49-17682. A cylinder having a single fuel system with a variable fuel delivery amount, a cylindrical rotary throttle valve and a metering needle provided on the rotary throttle valve as described in JP-A-58-101253 It is well known that there is a single fuel system with a variable fuel delivery amount.
[0003]
And the one with a sliding type or rotary type throttle valve has a single fuel system compared to the fixed venturi type, so the fuel connection from the low speed to the high speed is smooth and the fuel passage configuration Has the advantage that the required air flow rate at the time of high output is easily secured because the same passage cross-sectional area as that of the intake passage is given when fully opened.
[0004]
On the other hand, since the sliding throttle valve needs to provide at least a space equivalent to the stroke of the sliding throttle valve for the metering needle that moves together, there is a problem that the carburetor cannot be made sufficiently small. . In addition, the rotary throttle valve controls the required fuel flow rate in the entire engine operating range by a slight movement of the metering needle that moves integrally in the central axis direction, so the shape, dimensions, and installation relationship between the fuel nozzle and metering needle are highly accurate. There is a manufacturing difficulty in that it must be set to.
[0005]
On the other hand, in these carburetors, in order to improve engine startability, particularly cold startability, a choke valve or a start fuel passage may be provided, or a means for slightly moving the rotary throttle valve in the direction of the central axis may be provided. However, the choke valve and the start fuel passage increase the size of the carburetor and further complicate the fuel passage configuration. In addition, the means for moving the rotary throttle valve described in Japanese Utility Model Publication No. 6-83943 and the like with a cam moves the measuring needle with a small total stroke by a minute stroke, which makes the design and manufacture more troublesome. It will be difficult.
[0006]
[Problems to be solved by the invention]
The present invention is designed and manufactured including fixed venturi type, sliding throttle valve type, rotary throttle valve type carburetors with high output and fuel connection, overall miniaturization, and startability improvement means. The present invention has been made in order to solve the above-described problem that at least one of ease is difficult, and an object thereof is to provide a vaporizer that does not involve these problems.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention relates to an intake passage formed through the body, a butterfly-shaped throttle valve that opens and closes the intake passage, and a fuel nozzle that sends fuel to the intake passage downstream of the throttle valve. A fuel system, a metering needle inserted into the fuel nozzle, a cam member that rotates integrally with the throttle valve, and a driven member that holds the metering needle and is reciprocated by the cam member in the direction of the central axis thereof. The interlocking mechanism and the cam member are rotated so that the throttle valve is opened slightly from the idle opening so that the fast idle cam and the driven member are separated from the cam member to increase the fuel delivery amount from the idle position. And a manual starting mechanism having a lift-up cam as a starting position.
[0008]
By making the intake passage almost the same length without venturi, the required air flow rate at high output can be easily secured, and the throttle valve has a butterfly shape compared to sliding and rotating types. It is possible to reduce the size of the entire carburetor by shortening the valve axis direction. In addition, by installing a fuel nozzle downstream of the throttle valve and controlling the fuel delivery with a metering needle linked to the throttle valve, the required fuel flow in the entire engine operating range is controlled by a single fuel system. be able to. And since the stroke of the metering needle can be arbitrarily set by the cam, the function of appropriately controlling the fuel delivery amount over the entire engine operating range can be easily provided.
[0009]
Furthermore, when the engine is started, the throttle valve and the metering needle are operated by the manual starting mechanism without using the interlocking mechanism, so that the air flow rate necessary for maintaining the engine rotation and the high-concentration mixture required for starting Can be easily obtained, and the cold start can be surely performed. Since the movement amount of the measuring needle by the lift-up cam is set within the entire stroke by the interlocking mechanism, the design and manufacture are easy.
[0010]
In addition, a venturi can be provided in the part in which the fuel nozzle and the metering needle are installed, without making the intake passage have a substantially uniform diameter. In this case, the negative pressure required to suck out the fuel can be obtained mainly by the upstream throttle valve, so it is possible to increase the fuel flow without worrying about reducing the air flow by installing a venturi that slightly narrows the passage. It is.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. An intake passage 2 having a uniform overall length is formed in the fuselage 1 so as to penetrate in the lateral direction, and is rotatably held by the fuselage 1 across the intake passage 2. A well-known butterfly-shaped throttle valve 4 having a disc-like valve plate 6 mounted on the valve shaft 5 is provided with both end portions of the valve shaft 5 protruding from the body 1. Air that has entered the intake passage 2 from an air cleaner (not shown) flows through the throttle valve 4 in the direction of arrow E and is sent to a combustion chamber of an engine (not shown).
[0012]
A throttle valve lever 7 is fixed to one shaft end of the valve shaft 5, and the torsion coil spring provided on the shaft end portion is pulled or rotated by the driver's accelerator operation. That the throttle valve 4 is opened and closed by the spring force of the valve closing spring 8 is the same as that conventionally known.
[0013]
On the downstream side of the throttle valve 4 in the intake passage 2, a pipe-shaped fuel nozzle 10 is disposed so as to be parallel to the valve shaft 5 and protrudes at the tip of the tube wall of the fuel nozzle 10 in a slit shape that is long in the direction of the central axis. Nozzle port 11 is provided. A main jet 12 that defines the maximum flow rate of fuel is disposed at the base end of the fuel nozzle 10, and fuel in a membrane type constant fuel chamber (not shown) passes through the main jet 12 in the fuel passage to the fuel nozzle 10. Sent. The fuel passage, the main jet 12 and the fuel nozzle 10 constitute a single fuel system 9.
[0014]
On the other hand, a metering needle 13 protrudes from the intake passage 2 so as to face the fuel nozzle 10. The tip of the metering needle 13 is inserted into the fuel nozzle 10 and reciprocates linearly so that the nozzle opening 11 has a minimum opening when idling the engine and a maximum opening when maximum output.
[0015]
The base end of the metering needle 13 is inserted into a cylindrical holding member 15, and an adjusting screw 14 attached to the base end is screwed onto the female screw 16 of the holding member 15, and is particularly metered during idling. The insertion depth of the needle 13 into the fuel nozzle 10, that is, the effective opening area of the nozzle port 11 is adjusted so that stable idling is performed. The holding member 15 is slidably and airtightly fitted into a holding hole 17 provided in the body 2, and can be moved only in the central axis direction by a non-illustrated detent.
[0016]
In some cases, a venturi 3 as shown by a two-dot chain line may be provided in a portion of the intake passage 2 where the fuel nozzle 10 and the metering needle 13 are disposed. This venturi 3 works to increase the air flow rate and increase the amount of fuel delivered from the nozzle port 11, but the negative pressure necessary for sucking out the fuel is obtained mainly by the throttle valve 4 on the upstream side, so this negative pressure is reduced. Therefore, the fuel flow rate can be increased by slightly narrowing the passage so that the required air flow rate at the maximum output can be secured.
[0017]
A plate-like cam member 21 is fixed to the other shaft end of the valve shaft 5. The cam member 21 has an abutting protrusion 22 projecting outward and an arc-shaped cam 23 centering on the valve shaft 5, and the cam 23 has a cam surface 24 on a surface opposite to the body 1. have. In addition, a plate-like driven member 25 is fixed to an end portion of the holding member 15 protruding from the holding hole 17, and a contact piece 26 made of a ball that is rotatably held by the driven member 25 is formed on the cam surface 24. In contact. The cam member 21 and the driven member 25 are built in a cover body 28 attached to the body 1, and a pressing spring 27 made of a compression coil spring inserted between the top wall 28 a and the driven member 25 is a contact piece 26. Is brought into contact with the cam surface 24, and a force for moving the metering needle 13 toward the idle position where the metering needle 13 is inserted most deeply into the fuel nozzle 10 is applied. The pressing spring 27 is effective for bringing the cam member 21 and the driven member 25 into contact with each other and maintaining their interlocking relationship with certainty.
[0018]
When idling, the contact piece 26 contacts the lowest part of the cam surface 24 to minimize the effective opening area of the nozzle port 11 by the metering needle 13. When the throttle valve 4 starts to open from the idle opening by the accelerator operation, the contact piece 26 comes into contact with the gradually increasing portion of the cam surface 24, so that the measuring needle 13 attached to the holding member 15 is effective from the idle position to the nozzle port 11. The nozzle port 11 opens to the maximum when moving in the direction of increasing the opening area and the throttle valve 4 is fully opened. When the throttle valve 4 is closed by the valve closing spring 8, the driven member 25 is maintained in contact with the cam member 21 by the push spring 27 and moves the metering needle 13 toward the idle position.
[0019]
The cam member 21 having the cam 23, the driven member 25 having the contact piece 26, and the push spring 27 operate the throttle valve 4 and the metering needle 13 in relation to control the air-fuel mixture to a predetermined air-fuel ratio from idling to maximum output. The interlocking mechanism 20 is configured.
[0020]
According to the present embodiment, the flow rate characteristic of the fuel can be arbitrarily set according to the shape of the cam 23, the shape of the tip portion of the metering needle 13, and the size and shape of the nozzle port 11. Further, since the entire stroke of the metering needle 13 can be arbitrarily set depending on the height of the cam 23 regardless of the opening / closing operation of the throttle valve 4, design and manufacturing can be facilitated without impeding miniaturization of the entire vaporizer.
[0021]
Next, in the space formed by the inside of the cover body 28 incorporating the interlocking mechanism 20 and the recess of the body 1 communicating with the fast idle cam 31 that is pressed against the contact protrusion 22 of the cam member 21 and rotated, A lift-up cam 32 that moves in a direction away from the cam member 21 in contact with the surface on which the contact piece 26 of the driven member 25 is provided is incorporated. These two cams 31 and 32 are provided adjacent to each other at the distal end of a shaft piece 34 having a starting lever 33 at the base end, facing the mating surface between the body 1 and the peripheral side wall 28 b of the cover body 28. A shaft piece 34 is fitted into a shaft support hole 37 formed of the formed half shaft hole. The start lever 33 is sandwiched between the body 1 and the receiving wall 38 projecting from the body 1 and can be manually rotated without shaking in the axial direction.
[0022]
The fast idle cam 31, the lift-up cam 32, the start lever 33, and the shaft piece 34 are hollow bodies having a through hole 35 penetrating from the proximal end to the distal end, and a return spring 36 comprising a torsion coil spring receives one end. The other end of the wall 38 is engaged with the fast idle cam 31 and is received in the through hole 35. The return spring 36 serves to hold the two cams 31 and 32 in the inoperative position slightly separated from the cam member 21 and the driven member 25, but may be omitted. However, according to the present embodiment, even if the shaft piece 34 that supports the force that opens the throttle valve 4 from the idle opening and the force that moves the metering needle 13 from the idle position is made with a large diameter and high strength, Since the return spring 36 is arranged, there is an advantage that the compactness is not lost.
[0023]
When starting the engine, if the start lever 33 is moved from the non-operation position shown in FIGS. 1 and 4 to the operation position rotated 90 degrees counterclockwise in FIG. The contact protrusion 22 is pushed and rotated, and the throttle valve 4 having an idle opening is set to a starting opening that is slightly opened. At the same time, the lift-up cam 32 pushes the driven member 25 to move the contact piece 26 away from the cam surface 24, and the metering needle 13 at the idle position is set to the starting position where the nozzle opening 11 is opened slightly larger. As a result, the high-concentration air-fuel mixture required for starting is supplied to the engine.
[0024]
The fast idle cam 31, the lift-up cam 32, the start lever 33, the shaft piece 34, and the return spring 36 are a start mechanism for bringing the throttle valve 4 and the metering needle 13 into a state in which a high-concentration mixture necessary for starting is obtained. 30 except for the return spring 26, which is an integrally molded product of synthetic resin.
[0025]
According to the present embodiment, since the entire stroke of the metering needle 13 can be set to an arbitrary size regardless of the opening / closing operation of the throttle valve 4, the lift-up for determining the stroke for moving the metering needle 13 from the idle position to the starting position. The cam 32 can be easily designed and manufactured. Further, the shaft piece 34 is fitted in the shaft support hole 37 having a halved structure, and the shaft piece 34 is arranged in a direction perpendicular to the valve shaft 5 and the metering needle 13. Assembling is extremely simple.
[0026]
The start mechanism 30 can be held by hand in the operating position until the start of the engine is completed, or can be held in two positions, the non-operating position and the operating position. However, in the present embodiment, the lock mechanism 40 is provided to hold the three positions of the non-actuated position, the actuated position, and the half-actuated position therebetween.
[0027]
That is, the lock mechanism 40 is provided with stop portions 41a and 41b having two projecting edges arranged at a phase of 180 degrees on both sides across the central axis of the shaft piece 34 on the receiving wall 38, and an intermediate point between them. The locking projection 42 provided on the arm piece 28c protruding from the cover body 28 is provided at the phase portion of 90 degrees, while the engaging portion 43 formed of a long hole is provided in the central portion of the start lever 33. Contact portions 44a and 44b made of flat surfaces in directions orthogonal to each other are provided on both side edges.
[0028]
In the inoperative position, the start lever 33 is held by the two contact portions 44a and 44b being pinched between the one stop portion 41a and the locking projection 42. When the starting lever 33 is rotated toward the operating position, the locking projection 42 is detached from the contact portion 44b due to the bending of the arm piece 28c, and the two contact portions 44a and 44b are rotated at the operation position rotated 90 degrees. Is held by being caught between the locking projection 42 and the other stop 41b.
[0029]
When the engine is started, the start lever 33 can be returned to the inoperative position, but in this embodiment, the throttle valve 4 is set in the half-actuated position by engaging and engaging the engaging projection 43 with the engaging portion 43. Is set to a position slightly larger than the idle opening, and the metering needle 13 is set to a position where the nozzle opening 11 is opened slightly larger than in the idle position, and the warm-up operation following the cold start is performed at a high speed / high concentration mixture. It can be performed stably by idling. In addition, when performing an acceleration operation in which the throttle valve 4 is opened by an accelerator operation from the half-actuated position, there is an advantage that a high-concentration air-fuel mixture flows in advance so that no acceleration failure occurs.
[0030]
【The invention's effect】
As described above, according to the present invention, the opening / closing operation of the butterfly-shaped throttle valve is converted into the linear reciprocating movement of the metering needle to control the amount of fuel delivered from the fuel nozzle of a single fuel system, and on the downstream side of the throttle valve Since the fuel is supplied from the engine to the entire engine operating range, a high-performance carburetor is realized by realizing high output, optimizing the fuel flow rate, downsizing the entire carburetor, and facilitating design and manufacturing. Obtainable.
[0031]
In addition, by providing a starting mechanism that creates a high-concentration mixture by operating the throttle valve and the metering needle separately, and providing the choke function to the throttle valve, it has excellent startability without impairing the above features. Can be.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.
2 is a cross-sectional view taken along line AA in FIG.
3 is a cross-sectional view taken along line BB in FIG.
4 is a cross-sectional view taken along the line CC in FIG.
FIG. 5 is a front view of a starting mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Body, 2 Air intake path, 3 Venturi, 4 Throttle valve, 5 Valve shaft, 9 Fuel system, 10 Fuel nozzle, 13 Metering needle, 20 Interlock mechanism, 21 cam member, 24 Cam surface, 25 Drive member, 27 Push spring, 28 cover body, 30 start mechanism, 31 fast idle cam, 32 lift up cam, 33 start lever, 34 shaft piece, 35 through hole, 36 return spring, 37 shaft support hole, 40 lock mechanism, 41a, 41b stop, 42 engaging projections, 43 engaging portions, 44a, 44b per contact portion,

Claims (10)

An intake passage formed through the fuselage, a butterfly throttle valve for opening and closing the intake passage, and a single fuel system having a fuel nozzle for sending fuel to the intake passage downstream of the throttle valve; An interlocking mechanism having a metering needle inserted into the fuel nozzle, a cam member that rotates integrally with the throttle valve, and a driven member that holds the metering needle and is reciprocated by the cam member in a central axis direction thereof; Rotating the cam member to set the throttle valve to a starting opening slightly opened from the idle opening, the fast idler cam and the driven member are separated from the cam member, and the metering needle is moved from the idle position to the amount of fuel delivered. And a manual starter mechanism having a lift-up cam for increasing the starting position. The carburetor according to claim 1, wherein the intake path has a substantially uniform overall length. The carburetor according to claim 1, wherein the intake passage has a venturi at a portion where the fuel nozzle and the metering needle are disposed. The carburetor according to claim 1, wherein the cam member has a cam surface on a surface opposite to the body, and the driven member is brought into contact with the cam surface by a spring force. The starting mechanism is provided with the fast idle cam and the lift-up cam at the tip of a shaft piece having a start lever at the base end, and the shaft piece is connected to the valve shaft of the throttle valve and the metering needle. 2. A vaporizer as claimed in claim 1 arranged in a perpendicular direction. The starting mechanism is a hollow body having a through-hole penetrating from the proximal end to the distal end, and a return spring for rotating the throttle valve / metering needle from a position to be an opening degree / starting position in a direction to release them. The vaporizer according to claim 1 or 5, wherein the vaporizer is provided in a hole. The cam member and the driven member, and the fast idle cam and the lift-up cam are built in a cover body attached to the body, and a start lever for rotating the fast idle cam and the lift-up cam is provided outside the cover body. The vaporizer according to claim 1, 5 or 6, which is arranged in the above. The starting mechanism is in three positions: a non-operating position in which the throttle valve / metering needle is at an idle opening / idle position, an operating position at an opening opening / starting position, and a half operating position at an intermediate opening / position between them. The vaporizer according to claim 1, 5, 6, or 7, further comprising a lock mechanism that holds the gas. The lock mechanism includes an engagement portion provided on the start lever and a contact portion on both side edges, a locking projection provided on the body and / or the cover body, and two stop portions, and the start mechanism is started. A lever is held in an inoperative position or an operating position when the abutting portion hits one of the stop portions and the locking projection, and is half-actuated when the locking projection is engaged with the engaging portion. The vaporizer according to claim 8, wherein the vaporizer is held in position. The half shaft hole formed in these faces the mating surface of the body and the cover body, and the shaft piece is fitted in a shaft support hole formed of the two half shaft holes. Vaporizer.

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