Title of Invention

"FLUID ADJUSTING SCREW IN CARBURETOR"

Abstract

An annular gap formed by a taper needle valve portion and a metering hole are uniformly and accurately formed by increasing concentricity accuracy between a fluid adjusting screw and a screw guiding hole to improve accuracy and uniformity in controlling a fluid. Large and small diameter guide cylinder portions 5 and 6 are concentrically formed from male screw portion 3 of fluid adjusting screw P toward taper needle valve portion 4. Female screw portion 10, large and small diameter guide holes 11 and 12 and metering hole 13 are concentrically pierced in fluid controller 1 inward from an outer end. Male screw portion 3 is engaged with female screw portionlO, large and small diameter guide cylinder portions 5 and 6, supported by large and small diameter guide holes 11 and 12 respectively, and taper needle valve portion 4, inserted into and arranged within metering hole 13.

Full Text

SPECIFICATION BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a fluid adjusting screw arranged in a fluid controller and adjusting a fluid controlled within the fluid controller, and more particularly to a fluid adjusting screw used in a carburetor. DESCRIPTION OF THE CONVENTIONAL ART A description will be given of a fluid adjusting screw used in a conventional carburetor with reference to Fig. 2. Hereinafter, the adjusting screw will be referred as a pilot screw. Reference numeral 1 denotes a carburetor main body through which an intake passage 2 passes, and the other elements constituting a carburetor are omitted. Reference symbol P denotes a pilot screw serving as a fluid adjusting screw for adjusting an amount of low speed air-fuel mixture. The pilot screw P is constituted of the following elements. Reference numeral 30 denotes a male screw portion provided at the rear end. An adjusting groove 30A for rotating the pilot screw P is cut on a rear end surface 1A of the male screw 30. Reference numeral 31 denotes a taper needle valve portion provided at a front end of the male screw portion 30. The male screwportion 30 and the taper needle valve portion 31 are connected in the following manner. That is, a small diameter guide cylinder portion 32 is continuously provided from the front end of the male screw portion 30 toward the taper needle valve portion 31, and a front end of the small diameter guide cylinder portion 32 and a rear end of the taper needle valve portion 31 are connected by a connecting portion 33 having a diameter smaller than that of the small diameter guide cylinder portion 32. That is, the pilot screw P is structured such that the male screw portion 30, the small diameter guide cylinder portion 32, the connecting portion 33 and the taper needle valve portion 31 are continuously provided from the rear end toward the front end, and the respective portions mentioned above are concentrically and integrally formed. The pilot screw is generally manufactured by turning a brass material on a lathe. Meanwhile, the following holes are continuously pieced in the carburetor main body 1. A female screw portion 4 0 (including an unthreaded- 2 hole portion) to be engaged with the male screw portion 30, a small diameter guide hole 41 guiding and supporting the small diameter guide cylinder portion 32, and a metering hole 4 2 which the taper needle valve portion 31 is inserted into and arranged in are continuously provided, from the outer end {an upper side in Fig. 2) of the carburetor main body 1 toward an inner side and the female screw hole 40, the small diameter guide hole 41 and the metering hole 42 are concentrically formed. Further, a low speed air-fuel mixture inflow passage 43 is connected to an upstream side 42A of the metering hole 42, and a low speed air-fuel mixture outflow passage 4 4 is connected to a downstream side 42B of the metering hole 42. A downstream of the low speed air-fuel mixture outflow passage 44 is connected to an inner portion of the intake passage 2, and a low speed air-fuel mixture made by mixing a low speed fuel controlled by a low speed fuel jet (not shown) with a low speed air controlled by a low speed air jet is supplied within the low speed air-fuel mixture inflow passage 4 3 . Then, the pilot screw P is arranged in the carburetor main body 1 in the manner mentioned below. The pilot screw P is structured such as to be inserted into and arranged within the carburetor main body 1 via 3 the female screw portion 40 open so as to face to the outer end of the carburetor main body 1, whereby the male screw portion 30 is engaged with the female screw portion 40, the small diameter guide cylinder portion 32 is supported by the small diameter guide hole 41 so as to be movable in the axial direction, and the taper needle valve portion 31 is inserted into and arranged within the metering hole 42. In this case, reference symbol S denotes a coil spring pressing the pilot screw P to one side (for example, upward in Fig. 2) so as to deprive a backlash between the male screw portion 30 and the female screw portion 4 0. In the pilot screw P structured in the manner mentioned above, when inserting a driver into the adjusting groove 30A and rotating it, for example, in a clockwise direction, the pilot screw P moves inward so as to reduce a metering gap formed by the taper ireedle valve portion 31 and the metering hole 42, whereby it is possible to adjust an amount of the low speed air-fuel mixture supplied within the intake passage 2 from the low speed air-fuel mixture inflow passage 43 via the metering gap and the low speed air-fuel mixture outflow passage 44 in a reducing direction. On the contrary, when the pilot screw P is rotated in a counterclockwise 4 direction, the pilot screw P moves outward so as to increase the metering gap formed by the taper needle valve portion 31 and the metering hole 42, whereby it is possible to adjust the amount of the low speed air-fuel mixture supplied within the intake passage 2 from the low speed air-fuel mixture outflow passage 4 4' in an increasing direction. In accordance with the conventional fluid adjusting screw, it is hard to strictly attain an accuracy of concentricity between the female screw portion 40, the small diameter guide hole 41 and the metering hole 42 (totally called as a screw adjusting hole) pierced in the carburetor main body 1, and the pilot screw P. Even if the concentricity of the screw hole (the female screw portion 40, the small diameter guide hole 41 and the metering hole 42) and the concentricity of the pilot screw P are respectively formed and maintained in an accurate manner, it is impossible to accurately maintain the mutual concentricity in a state of arranging the pilot screw P within the screw hole, and this is caused by a reason that the fluid adjusting screw is supported to the small diameter guide hole 41 only by the small diameter guide cylinder portion 32. Further, :when the concentricity can not be 5 accurately maintained, particularly, it is impossible to uniformly maintain the shape of the annular gap particularly formed by the taper needle valve portion 31 and the metering hole 42, and this matter generates a problem in making the amount of the low speed air-fuel mixture more accurate and supplying the low speed air-fuel mixture uniformly. In order to improve the accuracy of concentricity, it can be considered to increase the guide length of the first guide cylinder portion 32 and the first guide hole 41, however, in this case, a total length of the pilot screw P "is increased and it is impossible to assemble the carburetor in a compact manner,. SUMMARY OF THE INVENTION A fluid adjusting screw in' accordance with the present invention is made by taking the above mentioned problem into consideration, and an object of the present invention is to improve an accuracy of concentricity between a fluid adjusting screw and a screw hole guiding the fluid adjusting screw on the basis of a little change given to a conventional adjusting screw without increasing a total length of the adjusting screw, thereby attaining significantly uniform and accurate control of the fluid. In order to achieve the object mentioned above. 6 in accordance with the present invention, there is provided a fluid adjusting screw provided in a carburetor and adjusting a low speed air-fuel mixture supplied to the carburetor, wherein the fluid adjusting screw is provided with a taper needle valve portion at a front end thereof and a male screw portion at a' rear end, and continuously provided with a large diameter guide cylinder portion and a small diameter guide cylinder portion from the male screw portion toward the taper needle valve portion, and the male screw portion, the large diameter guide cylinder portion, the small diameter guide cylinder portion and the taper needle valve portion are concentrically formed, wherein a carburetor main body is provided with a female screw portion, a large diameter guide hole, a small diameter guide hole and a metering hole concentrically pieced inward from the outer end, wherein the male screw portion of the fluid adjusting screw is engaged with the female screw portion, and wherein the large diameter guide cylinder portion is supported by the large diameter guide hole, the small diameter guide cylinder portion is supported by the small diameter guide hole, and the taper needle valve 7 portion is inserted into and provided within the metering hole. In accordance with the fluid adjusting screw of the present invention, the fluid adjusting screw is structured such that the large diameter guide cylinder portion is supported by the large diameter guide hole and the small diameter guide cylinder portion is supported by the small diameter guide hole, whereby it is possible to accurately and concentrically arrange the fluid adjusting screw within the screw hole constituted of the female screw portion, the large diameter guide hole, the small diameter guide hole and the metering hole, and particularly it is possible to accurately and uniformly insert and arrange the taper needle valve portion within the metering hole. Accordingly, it is possible to accurately and uniformly adjust and control the fluid such as the low speed air-fuel mixture or the like. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig. 1 is a vertical cross sectional view of a main portion of a fluid adjusting screw in accordance with the present invention; and Fig. 2 is a vertical cross sectional view of a main portion of a conventional fluid adjusting screw. 8 DESCRIPTION OF THE PREFERRED EMBODIMENT A description will be given of an embodiment of a fluid adjusting screw in accordance with the present invention with reference to Fig. 1. A fluid controller in accordance with the present embodiment is a carburetor similarly to that of the conventional embodiment, and the same reference numerals are attached to the same elements. Reference numeral 1 denotes a carburetor main body where an intake passage 2 passing through an inner portion thereof is pierced. Reference symbol Pdenotes a fluidadjusting screw. In the present embodiment, the fluid-adjusting screw is a pilot screw for adjusting an amount of low speed air-fuel mixture. The fluid adjustin-g screw P is constituted of the following elements. Reference numeral 3 denotes a male screw portion provided at a rear end. An adjusting groove 3A such as a minus groove, a plus groove or the like is cut on a rear end surface of the male screw 3. Reference numeral 4 denotes a taper needle valve portion provided at a front end of the male screw 3. The male screw portion 3 and the taper needle valve portion 4 are connected in the following manner. 9 A large diameter guide cylinder portion 5 and a small diameter guide cylinder portion 6 are continuous ly provided from the front end of the male screw portion 3 toward the taper needle valve portion 4, and a front end of the small diameter guide cylinder portion 6 is connected to a rear end of the taper needle valve portion 4 via a conical portion. That is, the fluid adjusting screw P is structured such that the male screw portion 3, the large diameter guide cylinder portion 5, the small diameter guide cylinder portion 6 and the taper needle valve portion 4 are continuously provided from the rear end toward the front end, and the respective portions mentioned above are concentrically formed. The fluid controller 1 is a carburetor main body in the present embodiment, and the following holes are continuously provided inward from the outer end of the carburetor main body 1. Reference numeral 10 denotes a female screw portion open so as to face to the outer end of the carburetor main body 1. A large diameter guide hole 11, a small diameter guide hole 12 having a diameter smaller than that of the large diameter guide hole 11, and a metering hole 13 are pierced inward from the lower end of the female screw portion 10. 10 The female screw portion 10, the large diameter guide hole 11, the small diameter guide hole 12 and the metering hole 13 are concentrically formed. Further, the fluid adjusting screw P is inserted into and arranged within the carburetor main body 1 via the female screw portion 10 open so as to face to the outer end of the carburetor main body 1, whereby the male screw portion 3 is engaged with the female screw portion 10, the large diameter guide cylinder portion 5 is supported by the large diameter guide hole 11 so as to be movable in the axial direction, the small diameter guide cylinder portion 6 is supported by the small diameter guide hole 12 so as to be movable in the axial direction, and the taper needle valve portion 4 is inserted into and arranged within the metering hole 13 . In the fluid adjusting screw P structured in the manner mentioned above, when inserting a driver into the adjusting groove 3A and rotating it, for example, in a clockwise direction, the fluid adjusting screw ? moves inward so as t.o reduce a metering.gap formed by the taper needle valve portion 4 and the metering hole 13, whereby it is possible to adjust an amount of the low speed air-fuel mixture supplied within the intake passage 2 via the low speed air-fuel mixture inflow 11 passage 43 and the low speed air-fuel mixture outflow passage 4 4 in a reducing direction. On the contrary, when the fluid adjusting screw P is rotated in a counterclockwise direction, the fluid adjusting screw P moves outward so as to increase the metering gap formed by the taper needle valve portion 4 and the metering hole 13, whereby it is possible to adjust the amount of the low speed air-fuel mixture supplied within the intake passage 2 from the low speed air-fuel mixture outflow passage 4 4 in an increasing direction. Then, in accordance with the fluid adjusting screw P of the present invention, the adjusting screw is structured such that the large diameter guide cylinder portion 5 existing at an upperQpart position in the axial direction is supported by the large diameter guide hole 11 movably in the axial direction, and is guided along a guide length (A), and the small diameter guide portion 6 positioned below in the axial direction is supported by the small diameter guide hole 12 movably in the axial direction, and is guided along a guide length (B) , so that particularly the taper needle valve portion 4 in the fluid adjusting screw P is accurately centered and arranged within the metering hole 13. In accordance with the structure mentioned above, 12 portion 4 and the metering hole 13 so as to always have ^ A^ v*-' an accurate annular gap, whereby it is possible to stably *S- ' even when a biasing force is applied to the fluid adjusting screw P by an adjusting tool such as a driver or the like inserted within the adjusting groove 3A in the case that the fluid adjusting screw P is rotated, or even when a biasing force is applied to the fluid adjusting screw P by a spring S, it is possible to uniformly form an annular gap by thle taper needle valve Q supply an accurate and uniform low speed air-fuel mixture toward the intake passage 2 of the carburetor main bo.dy 1 from the low speed air-fuel mixture outflow passage 4 4.. In this case, although the present embodiment is described with respect to the control of the low speed air-fuel mixture of the carburetor, it can be applied to a control of a low speed air and can be further applied to an air adjust screw for adjusting an amount of idling air in a throttle body. Further, if an unthreaded portion of the hole prepared for the female screw portion 10 is used as the large diameter guide hole 11, it is easy to manufacture the large diameter guide hole. Furthermore', since the fluid adjusting screw P is supported at two points in the axial direction of the 13 first guide guiding the large diameter guide cylinder portion 5 along the guide length (A) and the second guide guiding the small guide cylinder portion 6 along the guide length (B), the respective guide lengths can be set to be short, so that it is not necessary to make the length of the fluid adjusting screw P longer than that of the conventional one. As mentioned above, in accordance with the present invention, since the fluid adjusting screw P is continuously provided with the male screw portion 3, the large diameter guide cylinder portion 5, the small diameter guide cylinder portion 6 and the taper needle valve portion 4 concentrically from the rear end toward the front end, the male screw portion 3 is engaged with the female screw portion 10 provided in the carburetor main body 1, the large diameter guide cylinder portion 5 is supported by the large diameter guide hole 11, the small diameter guide cylinder portion 6 is supported by the small diameter guide hole 12 and the taper needle valve portion 4 is inserted into and arranged within the metering hole 13, it is possible to completely prevent the fluid adjusting screw P from inclininq, and it is possible to accurately and uniformly form the annular qap by the taper needle valve portion 4 and the metering hole 13, whereby it is possible to uniformly 14 and accurately control the fluid. Further, since the fluid adjusting screw P is supported by the large diameter guide cylinder portion. 5 and the small diameter guide cylinder portion 6 at two positions, it is not necessary to increase the length of the fluid adjusting screw P, and the size of the carburetor main body 1 is not increased, so that it is possible to easily apply the structure to the conventional carburetor. 15 WE CLAIM : 1. A fluid adjusting screw provided in a carburetor and adjusting a low speed air-fuel mixture supplied to the carburetor, wherein s'aid fluid adjusting screw P is provided with a taper needle valve portion 4 at a front end thereof and a male screw portion 3 at a rear end, and continuously provided with a large diameter guide cylinder portion 5 and a small diameter guide cylinder portion 6 from the male screw portion 3 toward the taper needle valve portion 4, and the male screw port ion, the large diameter guide cylinder portion 5, the small diameter guide cylinder portion 6 and the taper needle valve portion 4 are concentrically formed, wherein a carburetor main body 1 is provided with a female screw portion 10, a large diameter guide hole 11, a small diameter guide hole 12 and a metering hole 13 concentrically pieced inward from an outer end, wherein the male screw portion 3 of the fluid adjusting screw is engaged with the female screw portion 10, and wherein the large diameter guide cylinder portion 5 is supported by the large diameter guide hole 11, the small diameter guide cylinder portion 6 is supported by the small diameter guide hole 12, and the taper needle 16 valve portion 4 is inserted into and provided within the metering hole 13. 2. A fluid adjusting screw, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 3. A carburetor incorporating a fluid adjusting screw, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. An annular gap formed by a taper needle valve portion and a metering hole are uniformly and accurately formed by increasing concentricity accuracy between a fluid adjusting screw and a screw guiding hole to improve accuracy and uniformity in controlling a fluid. Large and small diameter guide cylinder portions 5 and 6 are concentrically formed from male screw portion 3 of fluid adjusting screw P toward taper needle valve portion 4. Female screw portion 10, large and small diameter guide holes 11 and 12 and metering hole 13 are concentrically pierced in fluid controller 1 inward from an outer end. Male screw portion 3 is engaged with female screw portionlO, large and small diameter guide cylinder portions 5 and 6, supported by large and small diameter guide holes 11 and 12 respectively, and taper needle valve portion 4, inserted into and arranged within metering hole 13.

Documents:

00043-cal-2002-abstract.pdf

00043-cal-2002-claims.pdf

00043-cal-2002-correspondence.pdf

00043-cal-2002-description(complete).pdf

00043-cal-2002-drawings.pdf

00043-cal-2002-form-1.pdf

00043-cal-2002-form-18.pdf

00043-cal-2002-form-2.pdf

00043-cal-2002-form-3.pdf

00043-cal-2002-form-5.pdf

00043-cal-2002-g.p.a.pdf

00043-cal-2002-letters patent.pdf

00043-cal-2002-priority document others.pdf

00043-cal-2002-priority document.pdf

43-CAL-2002-FORM-27.pdf

43-cal-2002-granted-abstract.pdf

43-cal-2002-granted-claims.pdf

43-cal-2002-granted-description (complete).pdf

43-cal-2002-granted-drawings.pdf

43-cal-2002-granted-form 2.pdf

43-cal-2002-granted-priority document.pdf

43-cal-2002-granted-specification.pdf

43-cal-2002-granted-translated copy of priority document.pdf