JPH09256910A - Air-fuel mixture control device - Google Patents

Abstract

(57) [Abstract] [Problem] Compact layout and excellent responsiveness
To provide an air-fuel mixture adjusting device for a carburetor suitable for a fuel supply system of an internal combustion engine at low cost. SOLUTION: A throttle valve 51 slidably disposed in a fluid supply passage bored in a carburetor body to make an effective sectional area of the passage variable, and heat for transmitting an engine temperature to the carburetor body. A heat transfer member 61, a temperature-sensitive member 54 that is in contact with the outer end portion of the throttle valve 51, and is disposed in the vicinity of the heat-receiving portion of the heat transfer means 61, the heat-receiving side of the temperature-sensitive member 54, and the heat-receiving portion. The heat conducting member 53 interposed between the heat insulating member 52 and the heat insulating member 52 disposed on the heat radiating side of the temperature sensitive member 54.
An air-fuel mixture adjusting device for a vaporizer comprising:

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for adjusting the mixing ratio of fuel and air in a carburetor.

[0002]

2. Description of the Related Art When an internal combustion engine is cold during the winter, the vaporization of fuel is poor. Therefore, in order to ensure smooth operation at low temperatures, a rich air-fuel mixture is temporarily supplied to the internal combustion engine. In order to do so, some vaporizers are equipped with a mixture control device.

For example, the one disclosed in Japanese Utility Model Laid-Open No. 58-130064 is a carburetor equipped with a low-speed fuel system, in which a pilot air passage is provided through a thermo valve provided in a heat-generating body such as an engine. It is connected to the air supply source, and until the engine reaches the specified temperature, 2
The supply of the secondary air is regulated by the thermo-valve to make a rich mixture, and when the temperature of the engine exceeds the specified temperature, the thermo-valve opens and the secondary air is supplied to the pilot air passage to dilute the fuel.

Further, in the one disclosed in Japanese Utility Model Laid-Open No. 60-120254, a temperature sensing element provided in a heat generating element such as an engine drives an on-off valve via a bellows. Air is supplied to the air vent of the main nozzle of the carburetor and the outlet of the intake passage through the on-off valve.

The former thermo-valve sensor and the latter thermo-sensitive body both use thermo-wax which expands as the temperature rises. The one disclosed in Japanese Utility Model Publication No. 62-45066 is to use thermowax to heat the engine cooling water and move the cold enrichment rod to open and close the passage to the main air bleed with respect to the atmosphere. is there.

[0006]

As described above, if the thermo-valve sensor and temperature sensor are attached to the engine body, the responsiveness of the valve is good. Since it is necessary to reroute the air passages, it is difficult to put them together compactly due to layout restrictions, and it is not suitable for small vehicles such as motorcycles, and it is also disadvantageous in terms of cost.

On the other hand, in the third example, the temperature sensing part is in the carburetor and the air passage is not required to be routed, but since it is not attached to the engine body, responsiveness becomes a problem,
Since there is no countermeasure against it, that is, temperature rise / heat retention,
There was difficulty in responsiveness.

Further, since the thermowax which is the temperature sensing portion has a very small amount of thermal expansion due to heating, and the sliding control width of the on-off valve is limited accordingly, it is difficult to finely control the mixture adjustment. Since the thermowax itself does not have the property of absorbing expansion at the time of temperature rise, there is equipment to absorb the thermal expansion of the thermowax itself in preparation for an excessive temperature rise, and the wax itself does not shrink during cooling after heating. Since the on-off valve does not return to its original state, equipment for returning the on-off valve is required, which tends to be complicated as a whole.

Since the present invention has been made in view of the above points,
The purpose is to provide an air-fuel mixture adjusting device for a carburetor at a low cost, which has a compact layout and excellent responsiveness and is suitable for a fuel supply system of an internal combustion engine.

[0010]

In order to achieve the above object, the present invention is slidably disposed in a fluid supply passage bored in a carburetor body, and effectively cuts off the passage. A throttle valve that makes the area variable, heat transfer means that transfers the engine temperature to the carburetor body, and a temperature-sensing element that is in contact with the outer end portion of the throttle valve and that is disposed in the vicinity of the heated portion of the heat transfer means. A carburetor including a member, a heat conducting member interposed between the heat receiving side of the temperature sensitive member and the heated portion, and a heat insulating member disposed on the heat radiating side of the temperature sensitive member. The air-fuel mixture adjusting device was used.

Since the throttle valve is arranged in the fluid supply passage bored in the carburetor body, it is not necessary to arrange the air passage around, and a compact layout is possible and the outer end portion of the throttle valve is also possible. The temperature-sensitive member that is in contact with the heat-transfer member is near the heat-receiving member, the heat-conducting member is interposed between the heat-receiving side of the temperature-sensitive member and the heat-receiving member, and the heat-insulating member is disposed on the heat-radiating side. Since the structure is provided, the responsiveness to the engine temperature can be maintained high.

The heat transfer member is a hot air duct, and the mixture adjusting device for a carburetor according to claim 1, wherein when the internal combustion engine is an air-cooled type, the shroud portion surrounding the outer circumference of the internal combustion engine extends from the hot air duct. Can guide the exhausted air and efficiently transfer the heat to the temperature-sensitive member near the heated portion.

The heat transfer member is a carburetor mixture adjusting device according to claim 1, wherein the heat transfer member is a hot water riser, whereby a part of the internal combustion engine cooling water passage is vaporized when the internal combustion engine is of a water cooling type. A hot water riser provided as a measure against icing of a vaporizer diverted to the body guides hot water and can efficiently transfer heat to the temperature sensitive member near the heated portion.

By using the air-fuel mixture adjusting device of the carburetor according to claim 1, wherein the temperature sensitive member is a spiral bimetal, the control range by the throttle valve can be increased, and more accurate air-fuel mixture adjustment can be performed. In addition, the spiral bimetal itself can absorb the expansion of the throttle valve as long as the throttle valve itself is provided with a means for restricting the stroke.Therefore, additional equipment such as thermo wax is required. In addition, since the throttle valve is also interlocked with the throttle valve when contracted, the throttle valve return equipment is not necessary.

A throttle valve slidably disposed in a fluid supply passage bored in the carburetor body to make the effective cross-sectional area of the passage variable, and a throttle valve arranged in contact with the outer end of the throttle valve. By using a mixture adjustment device for a carburetor equipped with an installed spiral bimetal, it is possible to increase the control range by the throttle valve while maintaining a compact structure, enabling finer mixture adjustment control, The number of parts can also be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described with reference to FIGS. This embodiment is applied to a scooter type motorcycle 1, and as shown in FIG. 1, the scooter type motorcycle 1 includes a unit swing type internal combustion engine.

A vehicle body front part 2 and a vehicle body rear part 3 are connected via a low floor part 4, and a vehicle body frame 5 forming the skeleton of the vehicle body descends from the vehicle body front part and then branches into two to form a floor part. The lower part of the vehicle body 4 extends rearward and the rear part 3 of the vehicle body extends upward and rearward. A seat 6 is provided on the upper part of the rear part 3 of the vehicle body, and a handle 7 is provided on the upper part of the front part 2 of the vehicle body in front of it.
There is provided a steering head 8 provided with.

A front wheel 10 is suspended on the front part 2 of the vehicle body via a front fork 9 and is steered by a handle 7.
Then, a pair of left and right hanger brackets 17 projecting above the front part of the unit swing case 16 are pivotally supported on a pivot 12 that is installed between left and right inclined parts that rise diagonally above the rear part of the body frame 5, and the swing unit 15 is swingable up and down, and a rear cushion 18 is interposed behind the pivot 12 and the vehicle body frame 5.

In front of the swing unit 15, an internal combustion engine is installed.
20 is integrally provided, a rear wheel 21 is rotatably supported at the rear portion, and the power of the internal combustion engine 20 is transmitted to the rear wheel 21 by a belt transmission mechanism 22 having an automatic speed change function. The fuel tank 23 is on the floor 4
It is fixedly mounted on the vehicle body frame 5 at the lower part of.

The internal combustion engine 20 is a forced-air-cooled two-cycle internal combustion engine. A cylinder block 20b and a cylinder head 20c (see FIG. 2) projecting forward from the crankcase 20a are located between the left and right rising portions of the vehicle body frame 5. Intake pipe that is located in the cylinder and extends upward from the cylinder block 20b.
24 extends to the left toward the rear and is connected to the carburetor 30, and the carburetor 30 is connected to the air cleaner 25 behind the carburetor 30. The carburetor 30 and the air cleaner 25 are the unit swing case 16 above the belt transmission mechanism 22. To be installed on.

A cooling fan 27 is provided on the crankshaft 20a on the right side of the crankshaft via a generator 26, and a side of the cooling fan 27 is covered with a fan cover 28 having an intake port. , The cylinder block 20b and the cylinder head 20c are connected to a shroud 29. An air exhaust port 29a is opened on the left side of the shroud 29, and a hot air duct 61 is connected to the air exhaust port 29a via a rubber connecting pipe 60.

The hot air duct 61 is a pair of duct halves.
61a and 61b are joined to each other, fit into a recess 62 on the right side surface of the unit swing case 16, extend obliquely upward and rearward, and the outer duct half 61a reaches the carburetor 30.

Therefore, the air sucked from the suction port by the rotation of the cooling fan 27 is guided by the shroud 29 to the cylinder block 20b and the cylinder head 20c to be cooled, and the warmed air is discharged to the connection pipe 60 from the exhaust port 29a. , Guided to the hot air duct 61 to the side of the carburetor 30,
Blow warm air on 30.

As shown in FIG. 3, in the carburetor 30, a vertically movable throttle valve 34 projects from a venturi portion between an air intake port 32 and an air-fuel mixture outlet 33 of an intake passage of a carburetor body 31, and is integrated with the throttle valve 34. The jet needle 35 is inserted into the main nozzle 36.

A slow jet 37 is disposed downstream of the main nozzle 36, while an air screw 50 is obliquely fitted to the side wall of the carburetor body 31, and the air screw 50 slides as a throttle valve. There is an air passage 38 extending in the sliding direction of the rod 51, and the air passage 38 is the slow jet.
It intersects the air bleed part of 37 at an angle (see Fig. 5).

As shown in FIGS. 6 and 7, the tubular portion 40 of the carburetor body 31, into which the sliding rod 51 of the air screw 50 is slidably inserted, has a large inner diameter portion 40a opened to the outside.
And a small inner diameter portion 40b which is slightly larger than the diameter of the sliding rod 51 extending inwardly, and the small inner diameter portion 40b is further reduced in diameter and continues to the air passage 38. The inner end of the sliding rod 51 forms a tapered valve portion 51a and is openably and closably fitted into the end opening of the air passage 38.

An air passage 39 extending from the air intake port 32 intersects with the small inner diameter portion 40b of the tubular portion 40. Therefore, the movement of the inner end valve portion 51a of the sliding rod 51 changes the effective cross-sectional area in the communication between the air passage 39 and the air passage 38, and the slow jet 37 flows from the air suction port 32 through the air passage 39 and the air passage 38. Air is supplied to and the amount is adjusted.

The air screw 50 has a cylindrical rod 52 slidably supporting a sliding rod 51. The cylindrical rod 52 is made of heat insulating resin and has a male screw on its outer peripheral surface. It is formed so as to be screwed into and supported by the large inner diameter portion 40a of the tubular portion 40 with a spring 55 interposed. Spring 55
Is a step between the large inner diameter portion 40a and the small inner diameter portion 40b, and the cylindrical support 52.
It is interposed as a compression spring between the end surface of and.

The sliding rod 51 is slidably supported by the cylindrical support body 52 and penetrates the spring 55 so that the inner end valve portion 51a faces the air passage 38, and the other outer end portion 51b is a flange.
It projects outward from the cylindrical support body 52 via 51c. The cylindrical support body 52 has a flange 52a formed on the outer end edge thereof, and an inner diameter of the outer end opening having an enlarged diameter portion 52d whose diameter is slightly enlarged in accordance with the flange 51c of the sliding rod 51.

Therefore, the sliding rod 51 has a cylindrical support 52.
Slidably supported by the flange 51c is a cylindrical support.
When it is fitted in the expanded diameter portion 52d of 52 and comes into contact with the stepped portion, inward sliding is restricted.

A spiral bimetal 54 is provided around the outer end portion 51b of the sliding rod 51. One end of the spiral bimetal 54 is fixed to the end surface of the flange 52a of the cylindrical support 52, and the other end is slid. It is fixed to the outer end of the outer end portion 51b of the rod 51.

The spiral bimetal 54 is formed by spirally winding a bimetal in which different kinds of metals are bonded together, and has a property of extending in the axial direction as the temperature rises and a property of turning in a direction of unwinding the winding. Therefore, the spiral bimetal 54 has a property of extending in the axial direction.

When the spiral bimetal 54 is in a contracted state at a low temperature, the sliding rod 51 is in a state in which the flange 51c is restricted by the enlarged diameter portion 52d of the cylindrical support 52 and is moved inward (FIG. 6). reference). A spiral bimetal 54 provided around the outer end portion 51b of the sliding rod 51 projecting outward from the cylindrical support body 52 is covered with a bottomed cylindrical lid member 53,
Cover the spiral bimetal 54.

The lid member 53 is made of a metal having a good thermal conductivity, and the opening end edge portion is caulked to the outer peripheral edge of the flange 51c of the cylindrical support body 52 and integrally fitted. Grooves 53a are formed along the diameter on the outer end surface of the bottom wall of the lid member 53. This groove 53
By rotating the tip of the driver in line with a, the cylindrical support body 52 integrated with the lid member 53 can be rotated, and the screwing state of the cylindrical support body 52 into the cylindrical body portion 40 can be adjusted.

That is, by adjusting the screwing state of the cylindrical support body 52 into the cylindrical body portion 40, the relative positional relationship between the inner end valve portion 51a of the sliding rod 51 and the opening of the air passage 38 (effectiveness of the air passageway). The cross-sectional area) can be adjusted. This is when it is necessary to absorb variations in the initial setting of the assembly or to further change the stroke of the throttle valve (use site environment, passenger preference, etc.).
It is also possible to adjust.

As shown in FIG. 2, FIG. 4 and FIG. 5, the lid member 53 made of a good heat conductor is located so as to project toward the opening of the hot air duct 61, and the hot air introduced by the hot air duct 61 is not exposed to the hot air. The lid member 53 is directly contacted to heat the lid member 53. The lid member 53 is heated by warm air with a good heat conductor to raise the overall temperature, and since the cylindrical support body 52 connected to the lid member 53 is made of a resin of a heat insulator, heat dissipation by heat conduction is prevented, The temperature of the lid member 53 is maintained.

The internal spiral bimetal 54 covered with the lid member 53 in which heat is accumulated in this way is heated as the temperature of the internal space rises, deforms and expands, and the sliding rod
Sliding 51 outwardly and gradually opening the inner end valve portion 51a to increase the effective sectional area through which air passes (see FIG. 7). Then, the sliding rod 51 becomes slidable until the outer end surface 51d of the sliding rod 51 contacts the inner end surface of the lid member 53.

Therefore, when the temperature of the internal combustion engine 20 is low, the air screw 50 is initially in the state shown in FIG.
The valve portion 51a of 51 reduces or closes the effective cross-sectional area of the air passage 38 and does not supply a small amount of air to the slow jet 37. Therefore, the fuel of the air-fuel mixture is rich and the operation in cold air is good. Can be maintained at.

The heat generated in the internal combustion engine 20 is efficiently transmitted as hot air to the lid member 54 of a good conductor of heat of the air screw 50 by the hot air duct 61, and the heat radiation side is radiated by the cylindrical support body 52 of the heat insulator. Since the structure is designed to prevent the spiral bimetal 54 from heating as much as possible, the spiral bimetal 54 reacts quickly to the engine temperature and the valve opening response of the air screw 50 responds even though the spiral bimetal 54 is far from the internal combustion engine 20. It has excellent properties.

When the sliding rod 51 of the air screw 50 slides outward in response to the engine temperature in this way, the valve portion 51a increases the effective cross-sectional area of the air passage 38, causing air to flow into the slow jet 37. It is possible to supply the air-fuel mixture suitable for the engine temperature by gradually reducing the air-fuel mixture having a darker fuel at low temperature.

As described above, the present embodiment has a simple structure in which the air screw 50 is attached to the carburetor body 31 without the need for arranging the slow air passages around the carburetor body 31, and has a compact layout. Can be reduced.

Since the spiral bimetal 54, which is the temperature-sensing portion of the air screw 50, has a large control width and can increase the amount of movement of the sliding rod 51, it is possible to finely adjust the air supply amount and at the same time, to move the sliding rod. Since the 51 is provided with the flange 51c for controlling the stroke and the outer end surface 51d, and the spiral bimetal 54 can absorb the expansion of itself,
Does not require additional equipment such as thermo wax,
In addition, since the sliding rod 51 is also interlocked with the contracting member, a special returning mechanism is not required and the structure is simple. Further, the adjustment of the initial setting of the effective sectional area of the air passage 38 of the air screw 50 and the change of the control width can be easily performed by rotating the lid member 53.

Next, another embodiment will be described with reference to FIGS.
It will be explained based on 11. The present embodiment is directed to a carburetor 70 provided in a water-cooled internal combustion engine, and an air screw 80 is used as a mixture adjustment device.

The carburetor 70 is provided with the slow jet 72 as in the above-mentioned embodiment, the air screw 80 is obliquely fitted to the side wall of the carburetor body 71, and the axial direction of the sliding rod 81 of the air screw 80. Has an air passage 73, and the air passage 73 obliquely intersects the slow jet 72 (see FIG. 9).

As shown in FIGS. 10 and 11, the tubular body portion 75 of the carburetor body 71 into which the sliding rod 81 of the air screw 80 is slidably inserted has a large inner diameter portion as in the above embodiment. The small inner diameter portion 75b is continuous with the air passage 73. Inner end valve portion 81a of the sliding rod 81
Is openably and closably fitted into the end opening of the air passage 73. An air passage 74 extending from the air intake port intersects with the small inner diameter portion 75b of the tubular portion 75.

In the air screw 80, a male screw 81d is formed on a part of a sliding rod 81, and a female screw portion 82b of a cylindrical support 82 is formed.
It is screwed to and is supported so as to be freely slidable. The cylindrical support body 82 is made of a metal having good heat conductivity, and has a male screw formed on the outer peripheral surface thereof so that the large inner diameter portion 75 a of the cylindrical body portion 75 has a spring 76.
It is adapted to be screwed in and supported by interposing.

A spiral bimetal 84 is provided around the outer end 81b of the sliding rod 81, which projects outward from the cylindrical support 82 through the flange 81c of the sliding rod 81.
Has one end fixed to the end surface of the flange 82a of the cylindrical support 82, and the other end fixed to the outer end of the outer end portion 81b of the sliding rod 81. The spiral bimetal 84 has a property of turning in a direction of unwinding the winding as the temperature rises.

When the spiral bimetal 84 is in a contracted state at a low temperature, the sliding rod 81 is in a state in which the flange 81c is regulated by the enlarged diameter portion 82d of the cylindrical support member 82 and is moved inward (FIG. 10). reference). When the spiral bimetal 84 is heated, it swivels in the direction of unwinding to rotate the sliding rod 81, so that the sliding rod 81 rotates while rotating with respect to the cylindrical support body 82 screwed with the screw portion 81d. Moving outward, the effective cross-sectional area of the air passage 73 is expanded as shown in FIG.

A spiral bimetal 84, which is provided around the outer end 81b of the sliding rod 81 projecting outward from the cylindrical support 82, is covered with a bottomed cylindrical lid member 83 to cover the spiral bimetal 84. ing.

The lid member 83 is made of a heat insulating resin, and the opening edge portion is caulked to the outer peripheral edge of the flange 51c of the cylindrical support body 52 and integrally fitted. Grooves 83a are formed along the diameter on the outer end surface of the bottom wall of the lid member 83.

A warm water riser 85 is fitted toward the tubular portion 75 of the carburetor body 71 to which the air screw 80 is attached. Hot water riser as shown in FIG. 8 and FIG.
Reference numeral 85 designates two connecting pipes 85a and 85b at their base end portions 85c.
Are connected in a mutually intersecting manner, and a part of the base end portion 85c extends and abuts on the tubular body portion 75 of the carburetor body 71.

A cooling water hose 86 is connected to one of the connecting pipes 85a to guide the cooling water which has taken up heat and is heated around the internal combustion engine, and the other connecting pipe 85b is used to return the cooling water to the radiator. The hose 87 is connected to form a bypass for cooling water.

The air-fuel mixture adjusting device of the present embodiment has the structure as described above, and when the internal combustion engine 20 is at a low temperature, the air screw 80 is initially in the state shown in FIG.
The valve portion 81a of 81 reduces or closes the effective sectional area of the air passage 73 to reduce or not supply the air to the slow jet 72. Therefore, the fuel of the air-fuel mixture is rich and the operation in the cold air is improved. Can be maintained.

The heat generated in the internal combustion engine 20 is supplied to the cooling water hose.
The hot water is led by the 86 to the hot water riser 85, and the base portion 85c of the hot water riser 85 extends from the tubular portion 75 and the air screw
The heat is efficiently transferred to the spiral bimetal 84 via the cylindrical support body 82 of 80 good heat conductor. Since the lid member 83 covering the spiral bimetal 84 is made of a heat insulating resin, heat radiation is prevented as much as possible.

Therefore, even though the spiral bimetal 84 is separated from the internal combustion engine, the reaction of the spiral bimetal 84 with respect to the engine temperature is fast and the air screw
Excellent in 80 valve opening responsiveness.

When the sliding rod 81 of the air screw 80 swivels and slides in the pull-out direction in response to the engine temperature in this manner, the valve portion 81a increases the effective cross-sectional area of the air passage 73 and the throwing speed increases. Supplying air to the jet 72,
When the temperature is low, the air-fuel mixture with rich fuel can be gradually thinned to supply the air-fuel mixture suitable for the engine temperature.

Also in this embodiment, it is not necessary to arrange the slow air passages around and the layout is compact. The spiral bimetal 84 swivels, but has a large control width and a large amount of axial movement of the sliding rod 81, and it is possible to finely adjust the air supply amount.
The initial setting of the effective sectional area of the air passage 73 of the air screw 80 can be easily adjusted by rotating the lid member 83.

Next, a modified example of the air screw will be described with reference to FIGS. 12 and 13. An air passage 93 is bored toward a slow jet (not shown) of the carburetor body 91, and the air passage 93 is formed.
A tubular portion 95 is formed in the extension direction of 93, and the air screw 100 is attached to the tubular portion 95. The cylindrical body portion 95 is composed of a large inner diameter portion 95a and a small inner diameter portion 95b, and an air passage 94 on the upstream side communicates with the small inner diameter portion 95b.

In the air screw 100, a cylindrical support member 101 made of a resin has a small diameter portion 101b screwed into a large inner diameter portion 95a of a cylindrical body portion 95 to project the large diameter portion 101a outward. Sliding cylindrical body on the support body 101 and the small inner diameter portion 95b of the cylindrical body portion 95
102 is slidably inserted. This sliding cylinder 102 is made of a metal having good thermal conductivity, has a valve opening 102a with a small inner diameter formed at the inner end, and has an opening 102b on the side wall near the valve opening 102a. Have. A groove is formed on the outer peripheral surface of the valve opening portion 102a and a seal member 106 is fitted therein.

The outer end of the sliding cylinder 102 forms a flange 102c inside the large inner diameter portion 95a of the cylindrical support member 101. A fixed rod 103 is inserted into the sliding cylindrical body 102, and the fixed rod 103 has a large inner diameter portion 95a at the outer end.
It is screwed and supported to the opening edge of the through a fixing member 104.

The inner portion of the fixed rod 103 passes through a small diameter portion 103b and forms a valve portion 103a having a tapered end portion to form the valve opening portion 102a.
The outer end of the male screw 103c is screwed onto the fixed rod 103. A groove 103d is formed along the diameter on the outer end surface of the fixed rod 103.

Inside the large diameter portion 101 a of the cylindrical support member 101, the spiral bimetal 105 is provided around the fixed rod 103.
The spiral bimetal 105 has one end fixed to the fixing member 104 and the other end the flange of the sliding cylinder 102.
It is fixed to 102c. Spiral Bimetal 105 is
It has the property of elongating when heated. Although not shown,
A warm water riser is in contact with the cylindrical portion 95 as in the above-described embodiment (see FIG. 9).

The air screw 100 has the above-described structure. At low temperature, the spiral bimetal 105 initially moves the sliding cylinder 102 outward in a contracted state to move the valve opening 102a. Is fitted into the valve portion 103a of the fixed rod 103 so that the effective cross-sectional area of the air passage 93 is small or closed, the supply of air to the slow jet is small or cut off, and the fuel of the air-fuel mixture is rich. It is possible to make the operation in cold air smooth.

When the engine temperature rises and heat is transferred to the spiral bimetal 105 via the tubular body 95 and the sliding cylinder 102 by the hot water riser, the spiral bimetal 105
105 expands and pushes the sliding cylinder 102 inward, as shown in FIG.
The valve opening 102a to the valve portion 103a of the fixed rod 103 as shown in FIG.
Away from the air passage 93 to increase the effective cross-sectional area
And the air passage 93 through the opening 102b to supply air to the slow air bleed, and gradually reduce the fuel-rich mixture at low temperature to supply a mixture suitable for the engine temperature. can do.

The periphery of the spiral bimetal 105 is covered with a cylindrical support 101 made of resin and a fixing member 104 to prevent heat dissipation, and the spiral bimetal with respect to the engine temperature.
The responsiveness of 105 is improved.

In the case of this air screw 100, the air passage 93
The initial setting of the effective sectional area can be adjusted by turning the tip of the screwdriver in alignment with the groove 103c on the outer end surface of the fixed rod 103.

In the air-fuel mixture adjusting apparatus in the above embodiment, the air screw is used as an air screw to adjust the ratio of the fuel in the air-fuel mixture at low temperature.
The structure of the air screw may be substantially the same as that of the air screw, and the pilot screw may be used to adjust the supply amount of the air-fuel mixture. It goes without saying that the above-described embodiments can be combined freely and have the same effect.

[Brief description of drawings]

FIG. 1 is an overall side view of a scooter type motorcycle according to an embodiment of the present invention.

FIG. 2 is a top view of a swing unit of the scooter type motorcycle as a cross section of a main part.

FIG. 3 is a sectional view of a carburetor mounted on the scooter-type motorcycle.

FIG. 4 is a side view of a vaporizer and its vicinity.

FIG. 5 is a rear view showing the same section.

FIG. 6 is a cross-sectional view of an air screw.

FIG. 7 is a cross-sectional view of the air screw in another state.

FIG. 8 is a side view of a carburetor and its vicinity according to another embodiment.

FIG. 9 is a rear view showing the same section.

FIG. 10 is a cross-sectional view of an air screw attached to the vaporizer.

FIG. 11 is a cross-sectional view of the air screw in another state.

FIG. 12 is a sectional view of an air screw according to another embodiment.

FIG. 13 is a cross-sectional view of the air screw in another state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Scooter type motorcycle, 2 ... Front part of vehicle body, 3 ... Rear part of vehicle body, 4 ... Floor part, 5 ... Body frame, 6 ... Seat,
7 ... Steering wheel, 8 ... Steering head, 9 ... Front fork, 10 ... Front wheel, 12 ... Axis, 15 ... Swing unit, 16 ... Unit swing, 17 ... Hanger bracket,
18 ... Rear cushion, 20 ... Internal combustion engine, 21 ... Rear wheel, 22 ... Belt position mechanism, 23 ... Fuel tank, 24 ... Intake pipe, 25 ... Air cleaner, 26 ... Generator, 27 ... Cooling fan, 28 ... Fan cover, 29 ... Shroud, 30 ... Vaporizer, 31 ... Vaporizer body, 32 ... Air inlet, 33 ... Mixture outlet, 34 ... Throttle valve, 35 ... Jet needle, 36 ... Main nozzle, 37
... Slow air greed, 38, 39 ... Air passage, 40 ... Cylindrical part, 50 ... Air screw, 51 ... Sliding rod, 52 ... Cylindrical support, 53 ... Lid member, 54 ... Spiral bimetal, 55 ... Spring, 60 … Connection pipe, 61… Hot air duct 70… Vaporizer, 71… Vaporizer body, 72… Slow jet,
73, 74 ... Air passage, 75 ... Cylindrical part, 76 ... Spring, 80 ...
Air screw, 81 ... Sliding rod, 82 ... Cylindrical support, 83
… Lid member, 84… Spiral bimetal, 85… Hot water riser, 86, 87… Cooling water hose, 91… Vaporizer body, 93, 94
… Air passage, 95… Cylindrical part, 100… Air screw, 101
... Cylindrical support, 102 ... Sliding cylinder, 103 ... Fixed rod,
104… Fixing member, 105… Spiral bimetal, 106…
Seal member.

Claims (5)

[Claims] 1. A throttle valve slidably disposed in a fluid supply passage bored in a carburetor body for varying an effective sectional area of the passage, and heat for transmitting an engine temperature to the carburetor body. A transfer means, a temperature-sensitive member that is in contact with an outer end portion of the throttle valve and is disposed in the vicinity of the heat-receiving portion of the heat-transfer means, and between a heat-receiving side of the temperature-sensitive member and the heat-receiving portion. An air-fuel mixture adjusting device for a carburetor, comprising: an intervening heat conducting member; and a heat insulating member arranged on the heat radiating side of the temperature sensitive member. 2. The air-fuel mixture adjusting device for a carburetor according to claim 1, wherein the heat transfer member is a hot air duct. 3. The air-fuel mixture adjusting device for a vaporizer according to claim 1, wherein the heat transfer member is a hot water riser. 4. The air-fuel mixture adjusting device for a vaporizer according to claim 1, wherein the temperature sensitive member is a spiral bimetal. 5. A throttle valve slidably disposed in a fluid supply passage bored in a carburetor body, for varying the effective cross-sectional area of the passage, and abutting against an outer end portion of the throttle valve. And a spiral bimetal arranged as follows.