Title of Invention

HEATER FOR PREVENTING ICING OF CARBURETOR

Abstract

A heater for preventing icing of a carburetor, comprises : a carburetor main body (1) having an intake passage (2) controlled by a throttle valve (3) ; a bypass hole (11) open to an inner portion of the intake passage so as to face to an end portion of the throttle valve from a bypass chamber (10) recessed along a longitudinal axial direction of the intake passage ; and a float chamber (6) is formed in an inner portion by a lower recess portion of the carburetor main body and a float chamber main body arranged so as to oppose thereto, wherein the longitudinal axial line A-A of the electric heater (13) is arranged substantially in parallel to the longitudinal axial direction (Y-Y) of the intake passage (2) and the fuel liquid surface (X-X); and the electric heater is integral with the float chamber main body, and attached to a heater mounting boss (20) parallel to the longitudinal axial direction (Y-Y) of the intake passage (2), and a heat insulating space portion (Z) is provided between a front end portion (20A) of the heater mounting boss (20) and a side wall (5A) of the float chamber main body (5).

Full Text

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a heater for preventing icing of carburetor and to a carburetor which adjusts and controls an amount and a concentration of an air-fuel mixture supplied to an engine and more particularly to a heater for preventing an icing which prevents a bypass hole open so as to face to an end portion of a throttle valve from being frozen (mounting of the heater for preventing the icing). DESCRIPTION OF THE CONVENTIONAL ART A description will be given of a conventional heater for preventing icing of a carburetor. A carburetor main body has an intake passage pierced there-through sideward. The intake passage is controlled to be opened and closed by a butterfly type throttle valve formed in a plate shape. The throttle valve is screwed with a throttle valve shaft rotatably supported to the carburetor main body, and a driver operates to rotate the throttle valve shaft, whereby the throttle valve opens and closes the intake passage. -2- A lower recess portion of the carburetor main body is closed by a cup-shaped float chamber main body, to form a float chamber, and a fixed fuel liquid surface is formed and held within the float chamber by a fixed liquid surface control mechanism constituted by a valve seat, a float valve opening and closing the valve seat and the float applying the opening and closing motion to the float valve. Further, a bypass chamber extending along a longitudinal axial direction of the intake passage is provided below the intake passage of the carburetor main body, and a bypass hole is pierced so as to be open toward an inner portion of the intake passage from the bypass chamber. The bypass hole is open so as to face to an end portion of the throttle valve, and the bypass hole functions mainly to supply a low speed fuel at a time when the engine is driven at a low speed. A heater mounting hole is recessed toward an upper portion in the side of the bypass chamber from a lower end of the float chamber main body. A female screw is formed upward from the lower end. Further, an electric heater structured such that an internal heat generating body generates heat due to an electric current application, is screwed to the heater mounting hole. The electric heater is energized when the engine is driven, whereby the bypass chamber and the bypass hole are warmed up by the heat generation of the electric heater so as to prevent the icing of the bypass hole. -3- In a conventional carburetor, there are the following problems. First, it is impossible to effectively warm up the bypass chamber including the bypass hole by the electric heater. This is because the heat generating portion of the electric heater is formed in a cylindrical shape, the heat generating portion is constituted of a side portion provided in the outer periphery of a cylinder portion and having a large heat generating area, and an upper bottom portion provided in the front end of the cylinder portion and having a small heat generating area, and the side portion having the large heat generating area is arranged orthogonally to the longitudinal axial line of the intake passage. A great amount of heat discharged from the side portion as mentioned above warms up the side wall of the float chamber main body at first, and the heat is next transmitted upward so as to warm up the bypass chamber and the bypass hole. Further, a space portion inevitably exists between the upper end of the heater mounting hole and the upper bottom portion of the electric heater due to a reason in processing of the female screw, and in order to increase a heat transmitting effect from the space portion, a grease is sealed in this portion, whereby an assembling property of the electric heater is greatly deteriorated. Further, the side portion having the large heat generating area in the electric heater is arranged along a direction of storing the fuel within the float chamber main body, whereby the fuel within the float chamber is easily warmed up by the side wall. and it is not preferable in view of restricting an evaporation of the fuel within the float chamber. Further, when attaching a harness for an electric current application to the electric heater, a total height of the carburetor becomes substantially large, so that freedom for mounting on the engine is deteriorated. SUMMARY OF THE INVENTION A carburetor in accordance with the present invention is made by taking the problems mentioned above into consideration, and an object of the present invention is to provide a heater for preventing icing of a carburetor which can effectively warm up a bypass hole including a bypass chamber, and further to restrict an evaporation of fuel within a float chamber due to an electric heater. In order to achieve the object mentioned above, the present invention provides a heater for preventing icing of a carburetor, comprising : a carburetor main body in which an intake passage is pierced sideward ; a throttle valve for controlling so as to open and close the intake passage ; a bypass hole open to an inner portion of the intake passage so as to face to an end portion of the throttle valve from a bypass chamber recessed along a longitudinal axial direction of the intake passage ; and -5- a float chamber in which a fixed fuel liquid surface is formed in an inner portion by a lower recess portion of the carburetor main body and a float chamber main body arranged so as to oppose thereto, wherein a longitudinal axial line of an electric heater is arranged substantially in parallel to the longitudinal axial direction of the intake passage and the fuel liquid surface ; and the electric heater is integrally formed with the float chamber main body, and attached to a heater mounting boss formed substantially in parallel to the longitudinal axial direction of the intake passage, and a heat insulating space portion is provided between a front end portion of the heater mounting boss and a side wall of the float chamber main body. In accordance with the present invention, since the side portion having the large heat generating area in the electric heater is arranged in parallel to the intake passage and the fuel liquid surface, it is possible to effectively warm up the bypass chamber and the bypass hole so as to prevent formation of icing. In particular, since the side portion is arranged in parallel to the fuel liquid surface, the fuel within the float chamber is hard to be warmed up, whereby it is possible to prevent the fuel within the float chamber from being evaporated. Further, since the space portion is formed between the front end portion of the electric heater and the side wall of the float chamber main body, and the side wall of -6- the float chamber main body is not heated by the front end portion of the electric heater, it is possible to further prevent the fuel within the float chamber from being evaporated. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS In the accompany drawings, - Fig. 1 is a vertical cross sectional view showing an embodiment of a heater for preventing icing of a carburetor in accordance with the present invention ; and Fig. 2 is a vertical cross sectional view showing a heater for preventing icing of a carburetor in accordance with conventional art. DESCRIPTION OF PRIOR ART A description will be given of a conventional heater for preventing icing of a carburetor with reference to Fig. 2. Reference numeral 1 denotes a carburetor main body has an intake passage 2 pierced there-through sideward. The intake passage 2 is controlled to be opened and closed by a butterfly type throttle valve 3 formed in a plate shape -7- The throttle valve 3 is screwed with a throttle valve shaft 4 rotatably supported to the carburetor main body 1, and a driver operates to rotate the throttle valve shaft 4, whereby the throttle valve 3 opens and closes the intake passage 2. A lower recess portion 1A of the carburetor main body 1 is closed by a cup-shaped float chamber main body 5, to form a float chamber 6, and a fixed fuel liquid surface X-X is formed and held within the float chamber 6 by a fixed liquid surface control mechanism constituted by a valve seat 7, a float valve 8 opening and closing the valve seat 7 and a float 9 applying the opening and closing motion to the float valve 8. Further, a bypass chamber 10 extending along a longitudinal axial direction Y-Y of the intake passage 2 is provided below the intake passage 2 of the carburetor main body 1, and a bypass hole 11 is pierced so as to be open toward an inner portion of the intake passage 2 from the bypass chamber 10. The bypass hole 11 is open so as to face to an end portion of the throttle valve 3, and the bypass hole 11 functions mainly to supply a low speed fuel at a time when the engine is driven at a low speed. Reference numeral 12 denotes a heater mounting hole is recessed toward an upper portion in the side of the bypass chamber 10 from a lower end 5B of the float chamber main body 5. A female screw is formed upward from the lower end 5B. -8- Further, an electric heater 13 structured such that an internal heat generating body generates heat due to an electric current application, is screwed to the heater mounting hole 12. The electric heater is energized when the engine is driven, whereby the bypass chamber 10 and the bypass hole 11 are warmed up by the heat generation of the electric heater 13 so as to prevent the icing of the bypass hole 11. The disadvantages of such a conventional carburetor has already been enumerated. They are briefly: Firstly, it is impossible to effectively warm up the bypass chamber 10 including the bypass hole 11 by the electric heater 13. Secondly, a space portion S inevitably exists between the upper end of the heater mounting hole 12 and the upper bottom portion 13B of the electric heater 13 due to a reason in processing of the female screw, and in order to increase a heat transmitting effect from the space portion S, a grease is sealed in this portion, whereby an assembling property of the electric heater 13 is greatly deteriorated. Thirdly, the side portion 13A having the large heat generating area in the electric heater 13 is arranged along a direction of storing the fuel within the float -9- chamber main body 5 (a vertical direction in the drawing), whereby the fuel within the float chamber 6 is easily warmed up by the side wall 5A, and it is not preferable in view of restricting an evaporation of the fuel within the float chamber 6. Fourthly, when attaching a harness for an electric current application (not shown) to the electric heater 13, a total height of the carburetor becomes substantially large, so that a freedom for mounting on the engine is deteriorated. DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given below of an embodiment of a heater for preventing icing of a carburetor in accordance with the present invention with reference to Fig.1. In this case, the same reference numerals are attached to the same constituting parts as those in Fig.2, and description thereof will be omitted. Reference numeral 20 denotes a heater mounting boss integrally formed with a float chamber main body 5. The heater mounting boss 20 is formed substantially in parallel to a longitudinal axial line Y-Y of an intake passage 2 and a fuel liquid surface X-X within a float chamber. -10- Further, a space portion Z is formed between a front end portion 20A of a heater mounting boss 20 and a side wall 5A of a float chamber main body 5. Further, a heater mounting hole 21 is pierced in the heater mounting boss 20 from a rear end portion 20C toward the front end portion 20A, and a female screw is formed therein. In this case, it is preferable that the heater mounting hole 21 is formed as close as possible to a bypass chamber 10. Further, an electric heater 13 is screwed from the rear end portion 20C of the heater mounting hole 21 toward the front end portion 20A, whereby a side portion 13A of the electric heater 13 is arranged substantially in parallel to the longitudinal axial line Y-Y of the intake passage 2 and the fuel liquid surface X-X within the float chamber 6, and a front end portion 13B of the electric heater 13 is arranged so as to face to the space portion Z. That is, the longitudinal axial line A-A of the electric heater 13 is arranged substantially in parallel to the longitudinal axial line Y-Y of the intake passage 2 and the fuel liquid surface X-X. In accordance with the structure mentioned above, when an electric current is applied to the electric heater 13 and an interior heat generating portion 11 generates heat, the heat is radiated from the side portion 13A having a large heat generating area to the float chamber main body 5. In this case, since the side portion 13A is arranged along the longitudinal axial line Y-Y of the intake passage 2, it is possible to effectively warm up the bypass chamber 10 including a bypass hole 11 so as to prevent an icing from being generated. Further, since the side portion 13A having the large heat generating area is arranged, in other words, orthogonally to a storing direction (a vertical direction) of the fuel liquid surface stored within the float chamber 6, it is possible to restrict warming-up of the fuel within the float chamber 6, so that it is possible to prevent the fuel within the float chamber 6 from being evaporated. Further, since the electric heater 13 is arranged sideward in a horizontal direction, a harness connected thereto for applying an electric current is also extended rightward. However, since an intake pipe directed toward the engine is connected to the right side of the intake passage 2 in Fig. 2 and a space exists below it, no problem is generated due to the rightward extension of the harness for applying the electric cur rent. Further, as the result that the space portion Z 12 is provided between the front end portion 13B of the heater mounting boss 20 and the side wall 5A of the float chamber main body 5, it is possible to prevent the heat of the heater mounting boss 20 from being transmitted to the float chamber main body 5, so that it is possible to further effectively prevent the fuel within the float chamber 6 from being evaporated. Further, since the space portion Z exists, it is possible to easily apply a working of a female screw to the heater mounting hole 21, and since no bag-like shape is provided, it is possible to securely remove chips. As mentioned above, in accordance with the heater for preventing the icing of the carburetor of the present invention, since the longitudinal axial line of the electric heater is arranged substantially in parallel to the longitudinal axial direction of the intake passage, and the fuel liquid surface, it is possible to effectively warm up the bypass chamber including the bypass hole by the side portion having the large heat generating area in the electric heater, so that it is possible to achieve the prevention of icing. Further, since only the front end portion of the electric heater is arranged so as to face to the fuel stored within the float chamber, and the side portion of the electric heater having the large heat generating 13 area is not arranged along the fuel, it is possible to effectively prevent the fuel evaporation within the float chamber from being generated. Further, as the result that the space portion for shielding the heat is provided between the front end portion of the heater mounting boss and the float chamber main, body, it is possible to prevent the heat in the front end portion of the electric heater and the heater mounting boss from applying to the fuel within the float chamber, and it is possible to further prevent the fuel evaporation within the float chamber from being generated. 14 WE CLAIM : 1. A heater for preventing icing of a carburetor, comprising : a carburetor main body in which an intake passage, is pierced sideward; a throttle valve for controlling so as to open and close the intake passage ; a bypass hole open to an inner portion of the intake passage so as to face to an end portion of the throttle valve from a bypass chamber recessed along a longitudinal axial direction of the intake passage ; and a float chamber in which a fixed fuel liquid surface is formed in an inner portion by a lower recess portion of the carburetor main body and a float chamber main body arranged so as to oppose thereto, wherein a longitudinal axial line A-A of an electric heater (13) is arranged substantially in parallel to the longitudinal axial direction (Y-Y) of the intake passage (2) and the fuel liquid surface (X-X) ; and the electric heater is integrally formed with the float chamber main body, and attached to a heater mounting boss (20) formed substantially in parallel to the longitudinal axial direction (Y-Y) of the intake passage (2), and a heat insulating space portion (Z) is provided between a front end portion (20A) of the heater mounting boss (20) and a side wall (5A) of the float chamber main body (5). -15- 2. A heater for preventing icing of a carburetor, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. -16- 3. A carburetor incorporating a heater for preventing icing as claimed in claim 1. A heater for preventing icing of a carburetor, comprises : a carburetor main body (1) having an intake passage (2) controlled by a throttle valve (3) ; a bypass hole (11) open to an inner portion of the intake passage so as to face to an end portion of the throttle valve from a bypass chamber (10) recessed along a longitudinal axial direction of the intake passage ; and a float chamber (6) is formed in an inner portion by a lower recess portion of the carburetor main body and a float chamber main body arranged so as to oppose thereto, wherein the longitudinal axial line A-A of the electric heater (13) is arranged substantially in parallel to the longitudinal axial direction (Y-Y) of the intake passage (2) and the fuel liquid surface (X-X); and the electric heater is integral with the float chamber main body, and attached to a heater mounting boss (20) parallel to the longitudinal axial direction (Y-Y) of the intake passage (2), and a heat insulating space portion (Z) is provided between a front end portion (20A) of the heater mounting boss (20) and a side wall (5A) of the float chamber main body (5).

Documents:

00103-cal-2002 abstract.pdf

00103-cal-2002 claims.pdf

00103-cal-2002 correspondence.pdf

00103-cal-2002 description(complete).pdf

00103-cal-2002 drawings.pdf

00103-cal-2002 form-1.pdf

00103-cal-2002 form-18.pdf

00103-cal-2002 form-2.pdf

00103-cal-2002 form-3.pdf

00103-cal-2002 form-5.pdf

00103-cal-2002 letters patent.pdf

00103-cal-2002 pa.pdf

00103-cal-2002 priority document.pdf

103-cal-2002-granted-abstract.pdf

103-cal-2002-granted-acceptance publication.pdf

103-cal-2002-granted-claims.pdf

103-cal-2002-granted-correspondence.pdf

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

103-cal-2002-granted-drawings.pdf

103-cal-2002-granted-examination report.pdf

103-cal-2002-granted-form 1.pdf

103-cal-2002-granted-form 18.pdf

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

103-cal-2002-granted-form 3.pdf

103-cal-2002-granted-form 5.pdf

103-cal-2002-granted-gpa.pdf

103-cal-2002-granted-letter patent.pdf

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

103-cal-2002-granted-reply to examination report.pdf

103-cal-2002-granted-specification.pdf

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