JPS6019969Y2 - Rotary throttle valve type carburetor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary throttle type carburetor equipped with a rotary throttle valve suitable for installation in a two-stroke engine used as a drive source for a chain saw or a brush cutter.

Conventionally, this type of carburetor is provided with a fuel supply mechanism for supplying the fuel required by the engine to the throttle hole of the rotary throttle valve in accordance with the rotation angle of the rotary throttle valve.

This fuel supply mechanism includes a nozzle tube for guiding fuel into a throttle hole of a throttle valve, one end of which is coupled to a throttle lever and is received within the carburetor body so as to be slidable in the circumferential and axial directions. The nozzle tube includes a needle for varying the diameter of the nozzle hole provided on the circumferential surface of the nozzle tube.

The nozzle tube is arranged along the rotation center axis of the throttle valve, and has one end fixed to the carburetor body and the other end extending into the throttle hole of the throttle valve.

Further, the needle is disposed along the rotation center axis of the throttle valve, and has one end screwed to one end of the throttle valve so as to be able to move integrally with the throttle valve, and the other end connected to the other end of the nozzle tube. Extending into the nozzle tube.

In order to move the needle forward and backward according to the rotation angle of the throttle valve, a cam groove is provided on the outer peripheral surface of the throttle valve, and a pin extending from the carburetor body to the cam groove is provided. A compression coil spring is provided between the other end of the throttle valve and the wall surface of the carburetor body that the other end faces to ensure the connection.

Therefore, when the throttle lever is operated, the throttle valve is rotated integrally with the needle and moved in the axial direction in accordance with the rotational operation angle of the throttle lever, thereby opening the nozzle hole of the nozzle tube. The aperture is variable, and fuel is supplied from the nozzle hole in an amount corresponding to the increase or decrease in the actual aperture.

However, in order to obtain an appropriate increase in fuel as the opening degree of the throttle valve increases, it is necessary to form the cam groove provided on the outer peripheral surface of the throttle valve into a curved shape.
It is extremely difficult to form such a curved cam groove on the outer peripheral surface of the generally cylindrical throttle valve.
Moreover, when the cam groove is curved, the friction between the cam groove and the pin that engages with it increases, and this umbrella acts as resistance to the throttle lever, making it difficult to operate the throttle lever smoothly. becomes.

Therefore, in the conventional carburetor, the cam groove provided in the throttle valve is formed in a straight line, and in the carburetor, the actual diameter of the nozzle hole is adjusted according to the rotation angle of the throttle lever. It was not possible to increase or decrease the amount of fuel appropriately, and it was not possible to supply an appropriate amount of fuel necessary to maintain a good operating condition of the engine depending on the operating condition of the engine.

Further, in the conventional carburetor, the width of the cam groove is set larger than the width of the pin that engages with the cam groove in order to enable smooth operation of the throttle lever. It is not possible to sufficiently reduce the friction between the cam groove and the pin, and it is necessary to use a return spring with a large spring force as a return spring to hold the throttle valve at the idling opening position. Because it is necessary to overcome the spring force of the throttle lever to operate the throttle lever,
A large operating force was required to operate the throttle lever.

Further, in the conventional carburetor, the width of the cam groove is set larger than that of the pin, and the compression coil spring causes the throttle valve to be in a state where the pin is in contact with one side wall of the cam groove. is held in

Therefore, in order to correct the position of the needle relative to the throttle valve for purposes such as idling adjustment, the throttle valve is moved in the axial direction according to the amount of play in the cam groove by a pressing force from a driver on one end of the needle, and When the driver is released from the needle, the elastic force of the compression coil spring causes the throttle valve to return to its original position.

For this reason, there is a difference between the amount of fuel supplied during adjustment and the amount of fuel supplied after adjustment, making accurate idling adjustment difficult.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the conventional technology, to have a relatively simple configuration, to be able to smoothly operate a throttle lever with a relatively small operating force, to be easy to manufacture, and to improve engine performance. It is an object of the present invention to provide a rotary throttle type carburetor that can supply an appropriate amount of fuel depending on the driving situation.

In the present invention, a throttle lever coupled to a shaft of a rotary throttle valve is provided with a pin extending toward the outer surface of the carburetor body, and the tip of the pin is attached to the outer surface as the lever swings. an inclined surface on which the rotary throttle valve slides, and the elasticity of a spring presses the tip of the pin toward the inclined surface, and the inclined surface defines the position of the rotary throttle valve in the axial direction according to the rotation angle of the rotary throttle valve. At the same time, in order to cause the spring to directly apply a biasing force in the circumferential direction toward the idling opening position of the throttle valve, the spring is disposed in the carburetor main body surrounding the shaft portion and has one end. A cylindrical compression coil spring is used, with one end of the compression coil spring being in contact with the carburetor body and the other end of the compression coil spring being in contact with a shoulder defining the shaft of the throttle valve. is coupled to the carburetor main body, and the other end is coupled to the throttle valve.

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

In FIG. 1, a carburetor according to the present invention is generally designated by the reference numeral 10, and the carburetor 10 includes a carburetor body 12 and a rotary throttle valve 14 incorporated within the carburetor body.

The carburetor body 12 has an air cleaner (not shown) at one end.
and the other end is connected to the internal combustion engine's intake pipe (not shown).
An air hole 16 is formed which is connected to the throttle valve 14, and a hole 18 which intersects with the air hole 16 and is open at one end is formed to receive the throttle valve 14.

The throttle valve 14 includes a cylindrical portion 14a and a shaft portion 14b extending from one end of the cylindrical portion with an axis aligned with the cylindrical portion.

The shaft portion 14b has a shaft portion 14b extending along its central axis.
A screw hole 20 is formed in the end face of b, and the cylindrical part 14
A small-diameter through hole 22 is formed in a, extending along the central axis, and having one end open to the screw hole 20 and the other end open to the other end of the cylindrical portion 14a.

Furthermore, as shown in FIG. 2, the cylindrical portion 14a is formed with a throttle hole 24 passing through it in the radial direction.

The throttle valve 14 is accommodated in the hole 18 such that the cylindrical portion 14a is located on the closed end side of the hole 18 and the shaft portion 14b protrudes from the open end of the hole 18.

A bearing member 26 constituting a part of the side wall of the carburetor main body 12 is bolted into the open end of the hole 18 to receive the shaft part 14b so that the tip thereof can protrude, and to close the open end. 28 to the carburetor body 12, whereby the throttle valve 14 is rotatably about its central axis, that is, slidably circumferentially and axially slidably within the carburetor body 12. It has been incorporated.

A needle 30 and a nozzle tube 32 are arranged in the threaded hole 20 and through hole 22 of the throttle valve 14, respectively, along the rotation center axis of the throttle valve 14.

One end of the nozzle tube 32 is fixed to a side wall portion of the carburetor body 12 facing the bearing member 26, and the other end extends into the throttle hole 24 from the other end of the cylindrical portion 14a through the through hole 22.

The one end of the nozzle tube 32 is connected to a conventionally well-known fuel feed path, and the fuel from the fuel feed path is transferred into the throttle hole 24 through a nozzle hole 34 provided on the circumferential surface near the other end. gush.

One end of the needle 30 has a screw hole 20 in the shaft portion 14b.
A screw member 36 is fixed thereto, and the one end of the needle 30 is connected to the shaft portion 14 of the throttle valve 14 via the screw member.

The other end of the needle 30 is inserted into the nozzle tube from the other end of the nozzle tube 32, and the other end of the needle 30 is inserted into the nozzle tube 32, and
The needle 30 slides integrally with the throttle valve 14 in the axial direction with respect to the nozzle tube 32 fixed to the nozzle tube 32, so that the opening area, that is, the actual diameter, of the nozzle hole 34 of the needle 30 becomes variable.

Shaft portion 14 of throttle valve 14 in carburetor main body 12
A compression coil spring 38 is arranged on the outer periphery of b, surrounding the shaft portion.

One end of this coil spring 38 is in contact with a bearing member 26 that constitutes a part of the side wall of the carburetor main body 12, and its terminal end 38a is locked to the bearing member 26.

The other end of the coil spring 38 is connected to the throttle valve 14.
It abuts on the one end of the cylindrical portion 14a, which is a shoulder portion, and its end 38b is locked to the shoulder portion.

Therefore, the throttle valve 14 receives a biasing force along the axial direction toward the closed end of the hole 18 due to the elastic force of the spring 38, and also receives a biasing force along the circumferential direction toward the idling opening position. receive.

The coil spring 38, whose terminals 38a and 38b are respectively connected to the carburetor main body 12 and the throttle valve 1-4, directly applies a circumferential biasing force to the throttle valve toward its idle link opening position. As a result, there is no need for another return spring dedicated to the conventional throttle valve to apply biasing force in the circumferential direction toward its idling opening position, simplifying the configuration of the carburetor. And it becomes possible to make it more compact.

A throttle lever 40 is fixed to one end of the throttle valve 14 protruding from the side wall of the carburetor body 12, that is, to the protruding end of the shaft portion 14b.

The throttle lever 40 has an L-shape as a whole as shown in FIG. 3, and is fixed to the shaft portion 14b at the center of the lever.

A connecting portion 42 to a throttle wire (not shown) is provided at one end of the throttle lever 40, and a pin 44 extending from the outer surface of the carburetor body 12 is fixed to the other end of the throttle lever 40.

Further, an arcuate groove 46 is formed on the outer circumferential surface of the carburetor main body 12 along an arcuate locus drawn by the tip of the pin 44 as the throttle lever 40 swings about the shaft portion 36. has been done.

One end 46a of this groove 46 defines the idling opening position of the throttle valve 12, and the other end 46b defines the fully open position of the throttle valve 12.

The bottom surface 48 of the groove 46 is inclined at a specific angle of elevation from the one end to the other end, and the bottom surface 48 of the groove 46
The tip of the pin 44 is always held in contact with the above-mentioned inclined surface 48 by the biasing force of 8.

Therefore, when the throttle lever 40 is at the idling operation angle, the tip of the pin 44 is held in contact with the deepest position of the inclined surface 48, so that the throttle valve 14 is
The other end is held close to the closed end of the hole 16 as shown.

In this idling state, the needle 30 is moved in the axial direction with respect to the throttle valve 14 by adjusting the threaded member 36 so that the fuel injected from the nozzle hole 34 is optimal in the idling state. 34 actual diameter is adjusted.

During this idling adjustment, the pressing force of a screwdriver or the like engaged with the screw member 36 does not act as the pressing force of the spring 38, and the throttle valve 14 does not move in the axial direction before and after adjustment, as in the conventional case. There isn't.

Therefore, quick and easy idling adjustment is possible.

When the throttle lever is rotated to direct the throttle valve 14 to its fully open position, the throttle valve 14 is rotated and the tip of the pin 44 is guided toward the shallowest position of the inclined surface 48. valve 14
is moved to the left in FIG. 1 along the axial direction depending on the rotation angle.

This movement of the throttle valve moves the needle 30 to the left together with the valve, thereby increasing the actual diameter of the nozzle hole 30.

Therefore, by giving a desired degree of inclination to the inclined surface 48 that defines the axial position of the throttle valve 14 in accordance with the rotation angle of the throttle valve 14, the throttle valve 14 can be
The actual diameter of the nozzle hole 30 can be appropriately increased or decreased according to the rotation angle, that is, the opening area of the throttle hole 24 to the air hole 16.

According to the present invention, since the inclined surface 48 is formed on the flat outer surface of the carburetor main body 12, a desired inclined surface can be easily formed by relatively simple cutting or molding. As a result, the actual diameter of the nozzle hole 30 can be accurately increased or decreased as the rotation angle of the throttle valve 14 is increased or decreased, making it possible to accurately control the operation of the internal combustion engine.

Further, unlike the conventional case, large friction does not occur between the inclined surface 48 and the pin 44, and as a result, the spring force for maintaining the throttle valve 14 at the idling opening can be set to a small value. A cylindrical tube that allows the throttle lever 40 to be operated smoothly with a relatively small operating force, and also provides a biasing force to the throttle valve in its axial direction so as to press the tip of the pin toward the inclined surface. Both ends of the compression coil spring are coupled to the carburetor main body and the throttle valve, respectively, so that the coil spring applies a circumferential biasing force to the throttle valve toward its idling opening position. Since this directly acts on the throttle valve, a dedicated return spring for applying biasing force in the circumferential direction to the throttle valve is not required, and the configuration can be simplified.

In the above description, an example was shown in which an arcuate groove was formed directly on the outer surface of the carburetor body to form an inclined surface on the outer surface. can be removably attached to the outer surface of the carburetor main body, and by selecting the guide plate, it is possible to supply fuel appropriately according to the characteristics of various internal combustion engines to which the carburetor is assembled.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the vaporizer according to the present invention, FIG. 2 is a vertical cross-sectional view taken along the line ■-■ shown in FIG. 1, and FIG. It is a front view which shows the throttle lever of the carburetor shown in the figure. 12: carburetor main body, 14: throttle valve, 14a: cylindrical part of throttle valve, 14b: shaft part of throttle valve, 24
: Throttle hole, 26: Bearing member, 30: Needle, 3
2: nozzle tube, 34: nozzle hole, 38: compression coil spring, 38a, 38b: terminals of coil spring, 40: throttle lever, 44: pin, 46: arcuate groove, 48: inclined surface.

Claims (3)

[Scope of utility model registration request] (1) A rotary throttle that is disposed on the carburetor body so as to be slidable in the circumferential and axial directions, and has a shaft portion at one end that protrudes from the carburetor body and is coupled to a throttle lever that is disposed outside the carburetor body. a valve, which is disposed along the rotation center axis of the throttle valve, has one end fixed to the carburetor body, and is inserted from the carburetor body through the other end of the throttle valve into a throttle hole provided in the throttle valve. an extending nozzle tube for injecting fuel into the throttle hole from a nozzle hole provided on the circumferential surface of the nozzle tube; a needle which is coupled and whose other end is received into the nozzle tube from the other end of the nozzle tube, and which allows the actual diameter of the nozzle hole to be varied by sliding in the axial direction of the throttle valve; and the throttle lever. a pin provided on the outer surface that extends from the throttle lever to the outer circumferential surface of the carburetor body; and a pin provided on the outer surface that contacts the tip of the pin and rotates the throttle valve in the axial direction according to the rotational operation angle of the throttle lever. a sloped surface for defining the position; and a pin disposed in the carburetor body surrounding the shaft portion so as to press the tip of the pin toward the sloped surface, and having one end abutted against the carburetor body; The compression coil spring includes a cylindrical compression coil spring disposed with its other end in contact with a shoulder defining the shaft portion of the throttle valve, and the compression coil spring directs the throttle valve toward its idling opening position. A rotary throttle type carburetor, characterized in that one end is connected to the carburetor body and the other end is connected to the throttle valve to apply a biasing force in the circumferential direction. (2) The low-rise throttle valve hole carburetor according to claim (1), wherein the inclined surface is a bottom surface of an arcuate groove provided on the outer surface. (3) The rotary throttle type carburetor according to claim (1), wherein the both ends of the spring are respectively latched to the side wall of the carburetor body and the shoulder of the throttle valve. vessel.