JPS6243064B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a sliding throttle valve type carburetor.

In a sliding throttle valve type carburetor, the effective diameter of the intake passage can be varied by sliding a throttle valve arranged across the air supply passage formed in the carburetor body in the diametrical direction of the intake passage. The effective diameter of the fuel nozzle can be increased or decreased in accordance with the increase or decrease in the effective diameter of the intake passage by means of a tapered needle that moves together with the throttle valve.

In the conventional carburetor described above, since the needle moves together with the throttle valve, in order to obtain an appropriate rate of change in the effective diameter of the fuel nozzle with respect to the rate of change in the effective diameter of the intake passage, the needle moves in unison with the throttle valve. The tapered part of the carburetor became longer, which caused problems such as an increase in the height of the carburetor.

The inventor of the present application previously proposed in Japanese Patent Application No. 57-165104 to solve the above-mentioned problems by sliding the throttle valve and the needle with different strokes.

A further object of the present invention is to provide a sliding throttle valve type carburetor that facilitates starting of an internal combustion engine in cold weather.

The present invention includes a throttle valve that is slidably accommodated in a guide hole with both ends closed and intersecting the intake passage in order to vary the effective diameter of the intake passage provided in the carburetor body in the axial direction of the guide hole. , a fuel nozzle that opens into the intake passage from wall portions of the four closed ends of the guide hole; and a fuel nozzle that is disposed along the axis of the guide hole and passing through the throttle valve, the other side of the guide hole being closed. A needle whose movement is guided along the axis of the guide hole in order to vary the effective diameter of the fuel nozzle by a guide portion provided on the end wall surface, and a needle which is oscillated by the operation of a throttle lever. a sliding throttle valve carburetor comprising an arm member operatively connected to the valve to slide the throttle valve by dynamic motion, the arm member being provided with a cam surface; is swingably supported near the other closed end, and engages the needle and abuts the cam surface to move the needle in the direction of movement of the throttle valve in conjunction with the swinging movement of the arm member. A driven member is provided in contact with the driven member, and further,
A cam mechanism is provided for moving the driven member away from the cam surface in order to move the nozzle toward the other closed end, and by operating the cam mechanism when starting the engine, the effective aperture of the fuel nozzle can be changed. The engine is characterized by a temporary increase, thereby making it easier to start the engine.

The features of the invention will become clearer from the following description of the illustrated embodiment.

The vaporizer 10 according to the present invention is shown in FIGS.
As shown in the figure, the intake passage 12 is open at both ends.
The carburetor body 14 includes a carburetor main body 14 in which an air intake passage 12 is formed, and a throttle valve 16 for making the effective diameter of the intake passage 12 variable.
The carburetor 10 is fixed to an internal combustion engine (not shown) by a flange portion 18 of the carburetor body so that one end of the intake passage 12 is connected to an air supply port of the engine (not shown). Although not shown, the other end of the intake passage 12 is connected to a conventionally well-known air cleaner.

The carburetor body 14 has a circular cross-sectional shape,
A guide hole 20 with both ends closed and intersecting the intake passage 12
is formed. In the illustrated example, the carburetor main body 14 includes a portion including a cylindrical portion 22 that defines a part of the guide hole in a plane crossing the axis of the guide hole 20, and a portion that includes a cylindrical portion 22 that defines a part of the guide hole, and a portion that cooperates with the cylindrical portion 22 to a closed-end tubular portion 24 coupled to the tubular portion 22 to define the bore 20;
It is divided into. The cylindrical portion 24 is connected to the carburetor main body excluding the cylindrical portion via a pair of mounting screws 26 (see FIG. 2), so that the mounting posture of the cylindrical portion 24 is set in the guide hole. Can be rotated 180 degrees in the circumferential direction.

The throttle valve 16 is made of a cylindrical member with one end closed. The throttle valve 16 has its closed end 16a connected to the intake passage 1.
one closed end 20 of the guide hole 20 adjacent to 2;
It is disposed in the guide hole 20 with its central axis aligned with the axial direction of the guide hole 20, facing the guide hole 20a. The throttle valve 16 is slidable in the axial direction of the guide hole in order to vary the effective diameter of the intake passage 12.
A guide hole 20 is connected to the closed end 16a of the throttle valve 16 from the wall portion of the one closed end 20a of the guide hole.
a hole 3 for receiving a nozzle tube 28 with open ends extending into the intake passage along the axis of the hole 3;
0 is formed. The nozzle tube 28 communicates at one end with a fuel passage 32 of a conventionally well-known fuel supply mechanism, and has a fuel nozzle 34 on its side for ejecting fuel.

A pivot shaft 36 parallel to the intake passage 12 is rotatably supported in the cylindrical portion 24 of the carburetor body 14, and a throttle lever 38 is attached to the projecting end of the pivot shaft.
is fixed. Further, an arm member 40 is fixed to the pivot 36. In the illustrated example, the arm member 40 includes a boss portion 40a fixed to the pivot 36.
and a pair of arm portions 40b extending in parallel to each other from the boss toward the center of the guide hole 20, and the tip of each arm portion 40b is pivotally connected to the closed end 16a of the throttle valve 16. It is pivotally attached to the section 42 via a link member 44. Therefore, by operating the throttle lever 38, the arm member fixed to the pivot shaft 36 can be swung, thereby causing the arm member operatively connected to the arm member via the link member 44 to swing. Throttle valve 16
can be slid along the axis of the guide hole 20 between the illustrated idling opening position and a fully open position in which the intake passage 12 is fully opened. The throttle valve 16 is held at the above-mentioned idling opening position by the spring force of a conventionally well-known return spring 46 (see FIG. 2). In order to smoothly slide the throttle valve 16 by operating the throttle lever 38, the arm member 40 and the throttle valve 16 are connected to each other.
It is preferable that the closed end 16a of the throttle lever and the throttle valve be made of an elastic synthetic resin material, and the elasticity of the parts made of the synthetic resin material can prevent looseness or play between the throttle lever and the throttle valve caused by assembly errors. This can be prevented.

A needle 48 is provided in the guide hole 20 to increase or decrease the effective diameter of the fuel nozzle 34 in accordance with the increase or decrease in the effective diameter of the intake passage due to the aforementioned sliding of the throttle valve 16.
is arranged along the axis of. Needle 4
8 includes a main body 50 having a uniform diameter in the axial direction and a base 52 fixed to one end of the main body in the example shown in FIG. A guide hole 56 is formed in the base 52 and is slidably fitted into a guide portion 54 extending from the wall surface of the other closed end 20b of the guide hole 20 along the axis of the guide hole 20.
The needle 48 has one end thereof, that is, the main body portion 5
The sliding movement of the throttle valve 16 in the moving direction of the throttle valve 16, that is, in the axial direction of the guide hole 20, is guided by the guide portion so that the tip of the nozzle tube 28 is received in the other end of the nozzle tube 28. Further, the needle 48 receives a spring force toward the nozzle tube from a coil spring 58 disposed around the guide portion between the wall surface of the closed end 20b and the end surface of the base portion 52.

A driven member 60 for sliding the needle 48 by swinging of the arm member 40 is arranged with its pivot portion 60a located near the guide portion 54 on the wall surface of the closed end 20b. There is. In the illustrated example, the pivot portion 60a is supported by the carburetor main body via a bearing member 62 that is positioned in the cylindrical portion 24 so as to be adjustable in the diametrical direction of the guide hole 20 and in the axial direction thereof. .

That is, as clearly shown in FIG. A first adjustment screw 66 that is screwed into the screw hole 64 of the adjustment screw, and a shaft portion 66 of the adjustment screw.
One side portion 70a in which a hole 68 is formed to allow penetration of a.
and an L-shaped base member 70 having another side 70b extending at right angles to the one side and in the diametrical direction of the guide hole 20, and a hole 72 formed in the other side of the base member and the hole. A shaft portion 7 passing through a hole 74 formed at the top of the cylindrical portion 24 corresponding to the
It is supported on the carburetor body by a positioning mechanism including a second adjustment screw 76 having a diameter of 6a.

One side 70a of the base member 70 is connected to the head 66b of the first adjusting screw by the spring force of a coil spring 78 disposed around the shaft 66a of the first adjusting screw. is held between. Therefore, the first adjustment screw 66
By rotating the base member 70, the base member 70 can be moved in the diametrical direction of the guide hole 20, and the base member 70 can be positioned at that position.

The second adjusting screw 76 has its head 76b locked to the other side 70b of the base member, and its shaft portion 76a extends into the guide hole 20 in parallel with the axis of the guide hole 20. The hole 72 formed in the other side 70b of the base member receives the shaft portion 76a of the adjustment screw 76 so as to move the adjustment screw 76 in parallel with the movement of the base member 70, and the adjustment screw 76 is attached to the base member 70. It is rotatable relative to member 70. Further, the hole 74 formed at the top of the cylindrical portion 24 receives the shaft portion 76a of the second adjusting screw 76 so as to allow the parallel movement of the screw. The bearing member 64 is screwed onto the shaft portion 76a near the closed end 20b. Therefore, while the bearing member 64 is prevented from rotating relative to the adjustment screw 76, the second adjustment screw 76 is
By rotating the bearing member 64, the bearing member 64 can be moved in the axial direction of the guide hole, and the bearing member 64 can be positioned at that position.

Therefore, the bearing member 62 can be adjusted in position by operating the two adjustment screws 66, 76, but the bearing member can be fixed to the carburetor body.

In the example shown in FIG. 2, the driven member 60 includes a swing shaft portion 60a supported by the bearing member 62, and a swing shaft portion 60a that extends from both ends of the swing shaft portion toward the boss portion 40a of the arm member. The link member is generally U-shaped and includes a pair of arm portions 60b extending in parallel. The tip of each arm portion 60b returns to a bent portion 60c, and the bent portion slidably abuts on the upper surface 80 of each arm portion 40b of the arm member 40. Since the pair of arm portions 62b extend on both sides of the base portion 52 of the needle, the bearing member 62 supporting the driven member 62 is prevented from rotating relative to the second adjustment screw 76 by the needle 48. There is. In addition, each arm portion 62b
is bent into a valley shape and engages with the lower surface of a pair of protrusions 82 provided on the base 52 of the needle 48.

When the throttle lever 38 is rotated, for example, in the counterclockwise direction as viewed in FIG. 1, in order to increase the effective diameter of the intake passage 20 beyond the idling opening degree shown in FIG. Due to the movement, the upper surface 80 of each arm portion 40b of the arm member 40 that receives each bent portion 60c of the driven member 60 acts as a cam surface of the bent portion 60c. This cam surface 80 causes the driven member 60 to swing about its swing shaft 60a as the arm member swings. This rocking of the driven member 62 causes the needle 48 to slide in its axial direction, that is, in the axial direction of the guide hole 20, so that the needle 48 is moved in accordance with an increase or decrease in the effective diameter of the intake passage 20.
slides within the nozzle tube 28, thereby increasing or decreasing the effective diameter of the fuel nozzle 34.

The effective aperture of the fuel nozzle 34, that is, the change in fuel supply amount with respect to the change in the effective aperture of the intake passage 20, that is, the opening degree of the throttle valve 16, is controlled by the bearing member 6 by operating the adjusting screws 66, 76.
It can be adjusted by adjusting the position of 2. When the first adjustment screw 66 is rotated, the driven member 60 and the needle 48 are held in substantially a predetermined position without causing the needle 48 to slide significantly in the axial direction of the needle, and the needle is rotated along with the bearing member 66. It moves in the longitudinal direction of the arm portion 62b along the diameter direction of the guide hole 20. Therefore, when adjusting the first adjustment screw 66, the distance from the swing shaft 60a of the driven member 60 to the protrusion 82 of the needle 48 changes.
The rate of movement of the nozzle 48, that is, the increase/decrease rate of the supplied fuel can be changed in the medium speed range exceeding the idling opening, and the fuel supply in the medium speed range, that is, the partial load range, can be changed by adjusting the first adjustment screw 66. Characteristics can be adjusted. Furthermore, when the second adjustment screw 76 is rotated, the driven member 60 swings around the bent portion 60c in accordance with the elevation and descent of the bearing member 62. Accordingly, the needle 48 moves in its axial direction.
Therefore, by adjusting the second adjustment screw 76, the idling opening degree and the fuel supply characteristics in the vicinity thereof can be changed.

In the carburetor 10 according to the present invention, a cam mechanism 84 is provided in association with the driven member 60 in order to improve the starting performance of the engine in cold weather. an operating shaft 86 disposed parallel to the pivot axis in the vicinity and rotatably supported by the carburetor body; an operating lever 88 fixed to one end of the operating shaft protruding from the carburetor body; and a cam member 90 fixed to the other end. The cam member 90 can come into contact with the lower surface of the driven member 60 by swinging the operating lever 88 when the throttle lever 38 is in the idling operating position. the cam member 90 to the first position.
By swinging counterclockwise as seen in the figure, the driven member 60 is moved through the bent portion 6 of the driven member 60 via the cam member.
0c can be rotated around the swing shaft portion 60a in a direction away from the cam surface 80 of the arm member 40. This rotation of the driven member 60 causes the needle 48 to move toward the other closed end 20b via the protrusion 82 of the needle 48 that engages with the driven member. As a result, the effective diameter of the fuel nozzle 34 becomes larger than that in the normal idling state shown in FIG. 1, so that the amount of fuel supplied increases in accordance with the increase in the effective diameter. When the operating force applied to the operating lever 88 is released, the spring force of the coil spring 58 causes the needle 48 to return to the normal idling position shown in FIG. An appropriate amount of fuel, just enough to maintain proper idling, is supplied to the engine from the nozzle 34.

Therefore, by operating the operating lever 88 when starting the engine, a rich air-fuel mixture can be temporarily supplied to the engine, thereby improving the starting performance of the engine.

Furthermore, in the carburetor 10, the needle 48 slides due to the swinging of the driven member 62 that comes into contact with the cam surface 80 of the arm member. is smoothly transmitted to the needle. Therefore, when the effective diameter of the intake passage is increased or decreased by operating the throttle lever 38, the needle can be smoothly slid in accordance with the sliding movement of the throttle valve, and the opening degree of the throttle valve can be adjusted. The fuel nozzle 34
Since the effective diameter of the engine, that is, the amount of fuel supplied can be quickly and appropriately increased or decreased, the responsiveness of the engine to the operation of the throttle lever 38 can be improved.

In the above, an example was explained in which a needle without a tapered tip was used and a nozzle tube was provided with a fuel nozzle on the side. The open end of the nozzle tube that opens to the intake passage can be used as the fuel nozzle without providing a fuel nozzle on the side of the nozzle tube. Further, although an example has been described in which the swing shaft portion of the driven member is adjustable in the axial direction and the diametrical direction of the guide hole, the swing shaft portion may be positioned in either the axial direction or the diametric direction of the guide hole. It will be clear that the fuel delivery characteristics can also be made variable by adjustable positioning in the direction.

According to the present invention, as described above, with a relatively simple configuration, it is possible to temporarily supply a rich air-fuel mixture to the internal combustion engine when the engine is started, thereby improving the starting performance of the engine. Therefore, the engine can be easily started even in cold weather.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a vaporizer according to the present invention, and FIG. 2 is a sectional view taken along the - line shown in FIG. 1. 12: Air supply path, 14 (22, 24): Carburetor body, 16: Throttle valve, 20: Guide hole, 20a, 20
b: closed end, 34: fuel nozzle, 38: throttle lever, 40: arm member, 48: needle,
60: Driven member, 62: Bearing member, 62a: Swing shaft portion, 80: Cam surface, 84: Cam mechanism.

Claims (1)

[Claims] 1. A throttle valve that is slidably accommodated in a guide hole with both ends closed that intersects the intake passage in order to vary the effective diameter of the intake passage provided in the carburetor main body, and the guide a fuel nozzle that opens into the intake passage from a wall surface at one closed end of the hole; and a wall surface at the other closed end of the guide hole, the fuel nozzle being disposed along the axis of the guide hole and passing through the throttle valve. A needle whose movement is guided along the axis of the guide hole in order to vary the effective diameter of the fuel nozzle by a guide section provided in the section, and a needle which is oscillated by the operation of a throttle lever and whose oscillating motion an arm member operatively connected to the throttle valve for sliding the throttle valve; a cam surface provided on the arm member; a driven member that engages the needle and abuts the cam surface to move the needle in the direction of movement of the throttle valve in conjunction with the rocking motion of the member; and a driven member that temporarily changes the effective diameter of the fuel nozzle during startup. a cam mechanism for moving the driven member away from the cam surface in order to move the nozzle toward the other closed end in order to increase the temperature.