JP2007120484A - Main fuel passageway adjusting device for carburetor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optimum combustion state by a simple operation suiting an atmospheric state (atmospheric pressure, humidity, atmospheric temperature) of the periphery without repeating exchanging of a main jet of a carburetor. <P>SOLUTION: A shaft case 10 is screwed into a float cover 5 of the carburetor. A tip end of a main needle 11a of a main needle shaft 11 goes into the main jet 6. A cross-section area of an orifice of the main jet is made to be variable. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of a carburetor for an internal combustion engine, and more particularly to an apparatus for adjusting the flow rate of fuel passing through a main fuel passage.

Conventionally, in a motorcycle, for example, as shown in Patent Document 1, the maximum flow rate of fuel passing through a main fuel passage of a carburetor is determined by the inner diameter of an orifice precisely formed in a main jet attached to the lower end of this passage. On the other hand, in a commercially available motorcycle, an appropriate main jet that can be operated comfortably throughout the year is selected and installed.
JP-A-5-272414

However, when trying to obtain the optimal combustion state according to the ambient atmospheric conditions (atmospheric pressure, humidity, atmospheric temperature) to be operated, such as altitude, weather, and temperature, the combustion state is covered with a single main jet. In some cases, it was difficult to obtain the original engine output. Especially when driving in extremely high altitude areas or when riding a motorcycle on a circuit and selecting the optimal main jet within the limited driving time frame, the engine output is effectively extracted, and as a result Although it is an important task only related to the race results, it was a heavy burden for riders with little experience to repeat driving and changing the main jet.

  In addition, the main jet is often screwed into the vaporizer body or jet holder in the float chamber, and repeated replacement work is felt complicated. Furthermore, various main jets had to be prepared as setting parts according to atmospheric conditions and engine specifications. The present invention allows a rider who suffers from these problems to perform an optimal combustion state according to the ambient atmospheric conditions (atmospheric pressure, humidity, atmospheric temperature) without repeating complicated main jet replacement, without disassembling the carburetor, or It is an object of the present invention to provide an adjusting device that can be obtained by a simple operation while traveling.

  In order to solve the above problems, the first invention is provided with a main fuel passage that opens into a float chamber of a carburetor that supplies an air-fuel mixture to an engine and communicates with a main bore, and an orifice attached to an end of the main fuel passage. Further, a needle member arranged to face the orifice and adjusting the cross-sectional area of the main fuel passage is arranged.

  According to a second aspect of the present invention, there is provided a jet needle that can be inserted into and removed from a main fuel passage integrally with a piston valve that controls the amount of air flowing through the main bore of the carburetor, and that the tip of the needle member faces the tip of the jet needle. Features.

  According to a third aspect of the present invention, there is provided a case member that holds the needle member so as to be movable back and forth with respect to the orifice, and the case member is attached to a float cover that defines the float chamber.

  The fourth invention is characterized in that the needle member has a conical shape in which the outer diameter decreases toward the orifice, and the apex angle of the cone is in the range of 2 to 15 degrees.

  The fifth invention is characterized in that the needle member can be screwed into the case member and a dial member capable of rotating the needle member from the outside is provided at the rear end portion thereof.

  The sixth invention is characterized in that a spring member is interposed between the needle member and the case member.

  According to a seventh aspect of the invention, there is provided a pointer support for holding a pointer indicating a reference position of the rotation speed of the dial facing the outer periphery of the dial member.

  The eighth invention is characterized in that an eccentric shaft case that allows eccentricity between the main jet and the case member of the float cover is supported by a sleeve and a set cover.

  The ninth invention is characterized in that the needle member can be screwed into the case member and a remote control member capable of operating the needle member from a remote location is provided at an end thereof.

  According to the first aspect of the present invention, the optimal combustion state matched to the surrounding atmospheric conditions (atmospheric pressure, humidity, atmospheric temperature) without repeating complicated main jet replacement can be performed without disassembling the carburetor or while traveling. It can be obtained by simple work.

  According to the second invention, since the tip of the needle member is opposed to the tip of the jet needle so that it can be inserted into and removed from the main fuel passage integrally with the piston valve, both of them can face each other across the main jet, and a special fuel passage for the adjusting device The structure can be simplified.

  According to the third invention, it is a simple structure in which the case member is attached to the float cover, and no significant change of the vaporizer body is required. Furthermore, if the adjusting device of the present invention is attached in place of the drain bolt attached to the float cover, the configuration of the present invention can be achieved by a very simple replacement operation.

  According to the fourth invention, since the apex angle of the conical needle member is in the range of 2 degrees to 15 degrees, the change in the passage area of the fuel passing through the main jet is moderate, the change in the position of the needle is not too rapid, Further, since the adjustment is simple because it is not too slow, the adjustment width does not require an axial length more than necessary, and the apparatus can be made compact.

  According to the fifth aspect, since the dial member is provided at the rear end portion of the needle member, the opening cross-sectional area of the main fuel passage can be easily adjusted from the outside during operation of the engine.

  According to the sixth aspect, the set position of the needle can be reliably maintained by the friction generated by the spring member inserted between the needle member and the case member.

  According to the seventh aspect of the invention, the pointer support holds the pointer indicating the reference position of the rotation speed of the dial, thereby facilitating data collection when recording and changing the setting position unique to the engine.

  According to the eighth aspect of the invention, the needle member can be supported toward the center of the main jet even when the adjustment member mounting portion formed at the lower portion of the float cover and the main jet are eccentric due to the structure of the vaporizer.

  According to the ninth aspect of the present invention, since there is a carburetor at the back of the vehicle body, it can be operated from the outside of the vehicle body via the remote control member even when the adjustment member cannot be reached. Furthermore, this makes it easy to make fine adjustments even during traveling, for example.

  Hereinafter, the present invention will be described with reference to examples. FIG. 1 shows a cross section of a vaporizer 1 to which the present invention is applied. A throttle valve 3 is slidably accommodated in the vaporizer body 2. A jet needle 4 is provided below the throttle valve.

  A float cover 5 is liquid-tightly fixed to the lower part of the carburetor body via an O-ring 17a. A main fuel passage 6b is formed in the carburetor body 2 inside, and the main jet 6 is twisted directly or appropriately through a holder. It is included. The main jet 6 measures the fuel corresponding to the maximum air flow rate of the carburetor 1 and supplies the fuel to the engine E from the main fuel passage 6b through a carburetor main bore (not shown).

  In the figure, the slow jet 7 measures a minute amount of fuel in the low speed rotation region mainly from the idling of the engine E. The float 8 and the float valve 9 cooperate to keep the oil level of the fuel constant.

  In the existing vaporizer, a female thread portion for discharging the fuel originally in the float chamber or screwing a relatively large diameter drain bolt for exchanging the main jet is formed below the float cover 5. There is something. In this embodiment, the female screw portion is used for facilitating processing and mounting. However, the present invention can be applied to other types of vaporizers if such a female screw portion is separately formed. It is. For this reason, it is not necessary to change the main body of the vaporizer, and the replacement work can be performed very easily.

  The shaft case 10 is screwed into the female screw portion. The shaft case has a male screw portion corresponding to the female screw portion at the upper end and a female screw portion in a small-diameter central hole. A large-diameter portion that accommodates the O-ring 17b is formed following the male screw portion.

  A main needle shaft 11 having an external thread formed on the outer shape is screwed into the small-diameter center hole. The main needle shaft 11 is integrally formed with a main needle 11a on the tip side. For this reason, since the tip of the main needle 11a faces the tip of the jet needle that can be inserted into and removed from the main fuel passage integrally with the piston valve, both can face each other across the main jet, and it is necessary to provide a new fuel passage for the adjusting device. The structure can be simplified.

  Since the apex angle of the main needle 11a is in a conical shape range of 2 to 15 degrees, the change in the passage area of the fuel passing through the main jet is easy to understand as the change in the combustion of the engine, and the position change of the main needle 11a is not too steep. Moreover, since the adjustment is simple because it is not too slow, the adjustment width does not require an axial length longer than necessary, and the apparatus can be formed compactly. In this case, a plurality of main needles having different apex angles can be prepared and appropriately selected.

  A dial 12 is integrally fixed to the rear end of the main needle shaft 11 with a fixing screw 13. By rotating this dial, the main needle shaft 11 can be moved in the axial direction corresponding to the screw pitch. For this reason, the opening cross-sectional area of the main fuel passage can be easily adjusted from the outside by turning the dial during operation of the engine. The shaft case 10 and the main needle shaft 11 are kept oil-tight by an O-ring 17c.

In the first embodiment, a spring 14 is interposed between the shaft case 10 and the dial 12 to reliably maintain the setting position of the needle by friction and prevent rotation due to vibration or the like. Since the allowance is given, the spring 14 can be omitted.

  A gauge 16 is fixed to the outer periphery of the shaft case 10 via a gauge holder 15. The tip of the gauge 16 extends near the outer periphery of the dial 12 and can indicate a reference position for the rotational speed of the dial 12. This facilitates data collection when recording and changing the setting position unique to the engine.

  The inner diameter of the orifice portion of the main jet 6 is called a count, but the main jet attached to the adjusting device may be about 10 to 100% larger than that normally used by the engine. Alternatively, an existing main jet inner diameter appropriately enlarged may be used. It is preferable to select a main jet having a large count considering the cross-sectional integral of the main needle 11a so that an appropriate mixing ratio can be obtained in a state where the main needle 11a enters the main jet 6 from about one third to half.

  After recording the state where the main needle shaft 11 is fully closed, the engine E is started with a slight return. Idling is possible with the slow system, but there is not enough fuel to move in this state, so the rotation does not increase and stalls. If the throttle valve 3 is opened and closed with no load operation while turning the dial in the reverse direction to find a position where the engine E is not caught by the increase in rotation of the engine E, a position that reacts well to the movement of the throttle is found, and this position is recorded.

  Next, the adjustment is completed by making a fine adjustment after grasping the state in which the engine E is loaded and actually applying the full load near the maximum speed by riding or the like. In this state, the main needle position can obtain a passage cross-sectional area substantially equivalent to the proper main jet count. After that, you can almost decide the main system settings just by making fine adjustments according to the temperature, weather and course. Even if the jet needle 4 is replaced or changed, the optimum state can be adjusted immediately.

  Although the first embodiment has been described on the assumption that the center of the drain bolt hole of the vaporizer coincides with the center of the main jet, FIG. 2 shows an embodiment in which both centers are slightly offset. . In addition, the same number is given to common parts.

  A sleeve 18 with a hook is screwed into the drain bolt hole from the inside of the float cover 5 and fixed. Then, the set cover 19 is screwed and fixed to the male screw portion protruding to the outside of the sleeve 18 so as to sandwich the flange portion of the shaft case 20. The shaft case is formed such that the flange portion and the main body portion are decentered from each other, and this decentering amount matches the offset amount between the drain bolt hole center and the main jet center.

  The shaft case 20 and the set cover 19 are kept oiltight by an O-ring 17d. The main needle shaft 11 is supported on the shaft case 20 by the same thread as in the first embodiment, and the tip of the main needle 11a faces the center of the main jet. Therefore, even if the drain bolt hole center and the center of the main jet 6 are eccentric in structure, the centers of the main needle 11a and the main jet 6 can be made to coincide.

  For example, even when the adjustment member cannot be reached because of the carburetor at the back of the vehicle body, the main needle shaft 11 and the dial 12 are connected by a flexible cable 21 as shown in FIG. More remote control operation can be made possible. In addition, for example, it is possible to make fine adjustments during traveling as required.

  The adjusting device of the present invention is suitable for a vehicle such as a motorcycle equipped with an internal combustion engine that needs to frequently set a carburetor. This is particularly convenient when the engine output is greatly affected by the atmosphere such as racing.

It is explanatory drawing which showed the cross section of the vaporizer | carburetor to which this invention was applied. Example 1 It is explanatory drawing which showed the other structure of this invention. (Example 2) It is explanatory drawing which showed other structure of this invention. (Example 3)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vaporizer 3 ... Piston valve 4 ... Jet needle 5 ... Float cover 6 ... Main jet (orifice)
6b ... main fuel passage 10 ... holder 11a ... needle 12 ... dial

Claims (9)

  A main fuel passage that opens into a float chamber of a carburetor that supplies an air-fuel mixture to the engine and communicates with the main bore, and an orifice that is attached to an end of the main fuel passage are provided. A main fuel passage adjusting device for a carburetor, wherein a needle member for adjusting an area is arranged.   A jet needle that can be inserted into and removed from a main fuel passage integrally with a piston valve that controls the amount of air flowing through the main bore of the carburetor is provided, and the tip of the needle member faces the tip of the jet needle. The main fuel passage adjusting device for a carburetor according to claim 1, wherein   The vaporizer according to claim 1, wherein a case member is provided to hold the needle member so as to be movable back and forth with respect to the orifice, and the case member is attached to a float cover that defines the float chamber. Main fuel passage adjustment device.   The main body of the carburetor according to claim 1, wherein the needle member has a conical shape with an outer diameter decreasing toward the orifice, and the apex angle of the cone is in the range of 2 to 15 degrees. Fuel passage adjustment device.   4. The main fuel for a carburetor according to claim 3, wherein the needle member can be screwed into the case member, and a dial member capable of rotating the needle member from the outside is provided at a rear end portion thereof. Passage adjustment device.   The main fuel passage adjusting device for a carburetor according to claim 3, wherein a spring member is interposed between the needle member and the case member.   The carburetor main fuel passage adjusting device according to claim 4, further comprising a pointer support for holding a pointer indicating a reference position of a rotational speed of the dial facing the outer periphery of the dial member.   The carburetor main fuel passage adjusting device according to claim 3, wherein an eccentric shaft case that allows eccentricity between the main jet and a case member of the float cover is supported by a sleeve and a set cover.   The carburetor according to claim 3, wherein the needle member can be screwed into the case member, and a remote control member capable of remotely operating the needle member is provided at a rear end portion thereof. Main fuel passage adjustment device.

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