JP2008202515A - Sliding throttle valve type carburetor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding throttle valve type carburetor exerting purge performance equal to or more than that of a butterfly type carburetor, by efficiently sucking diffused gas of fuel. <P>SOLUTION: In the sliding throttle valve type carburetor 1, a sliding throttle valve 4 is slidably fitted and inserted into a cylinder part 2a vertically disposed to a mixing chamber 2, and the sliding throttle valve 4 is slid in the mixing chamber 2 to measure the fuel. A groove 6 opened to the mixing chamber 2 is formed to a part of an outer peripheral surface of the sliding throttle valve 4, and a purge hole 7 communicating with the canister 10 and selectively communicating with the groove 6 is opened to an inner peripheral surface of the cylinder part 2a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sliding throttle type carburetor having a purge hole for purging a fuel vapor gas adsorbed by a canister into a mixing chamber.

  The fuel evaporates in the fuel tank of a vehicle such as a motorcycle, but if the vaporized gas generated by the evaporation of this fuel is released into the atmosphere as it is, it causes air pollution. The transpiration gas is adsorbed on activated carbon.

Thus, the vaporized gas adsorbed by the canister is sucked by the negative pressure generated in the carburetor and the throttle body by the operation of the engine, returned to the intake system, and recovered by being used for combustion in the engine. (For example, see Patent Documents 1 and 2). Specifically, a purge hole is opened in the vicinity of a butterfly-type throttle valve provided in the carburetor or the throttle body, and a purge pipe connected to the canister is connected to the purge hole so that the carburetor and the throttle are operated during engine operation. The vapor generated from the canister is sucked through the purge pipe by the negative pressure generated in the vicinity of the throttle valve on the body, and this vapor is purged from the purge hole near the throttle valve on the carburetor or throttle body and returned to the engine intake system. Has been done.
Japanese Patent Publication No. 6-005059 Japanese Patent Laid-Open No. 2006-070785

  However, when the method of purging fuel vaporized gas to the vaporizer is employed, application to the butterfly type vaporizer having a butterfly type throttle valve has been limited. In addition, it has been difficult for a sliding throttle type vaporizer equipped with a sliding throttle valve to exhibit the same purge performance as a butterfly type vaporizer.

  The present invention has been made in view of the above circumstances, and the object of the present invention is a sliding throttle valve capable of efficiently sucking a fuel vapor gas and exhibiting a purge performance equivalent to or better than that of a butterfly type vaporizer. The object is to provide a type vaporizer.

  In order to achieve the above object, according to the first aspect of the present invention, a sliding throttle valve is slidably fitted into a cylinder portion standing in the mixing chamber, and the sliding throttle valve is slid in the mixing chamber. In the sliding throttle type carburetor that measures fuel by moving, a groove that opens in the mixing chamber is formed in a part of the outer peripheral surface of the sliding throttle valve, and the inner peripheral surface of the cylinder portion In addition, a purge hole communicating with the canister and selectively communicating with the groove is opened.

  According to a second aspect of the present invention, in the first aspect of the invention, the length of the groove or the position of the purge hole is at least closed when the sliding throttle valve is fully closed by the sliding throttle valve. The length or position is set.

  According to the first aspect of the present invention, when the purge hole opened in the inner peripheral surface of the cylinder communicates with the groove formed in a part of the outer peripheral surface of the sliding throttle valve, the fuel vaporized gas adsorbed in the canister Is effectively sucked into the mixing chamber and purged from the purge hole through the groove of the sliding throttle valve due to the negative pressure generated in the mixing chamber, so the sliding valve type vaporizer is equivalent to the butterfly type vaporizer. The above purge performance can be obtained.

  According to the second aspect of the present invention, the purge hole is closed by the sliding throttle valve at least when the sliding throttle valve is fully closed, that is, when the engine is in an idling operation state and at a low rotation and a low load. Therefore, it is possible to prevent the deterioration of the engine operation stability and the deterioration of the exhaust gas characteristics due to the enrichment of the air-fuel mixture due to the purge of the vaporized gas.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 and 2 are longitudinal sectional views of a main part of a sliding throttle type carburetor according to the present invention, FIG. 3 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is a slide of the sliding throttle type carburetor. FIG. 5 is a side view of the dynamic throttle valve, and FIG. 5 is a diagram showing the purge characteristics of the sliding throttle valve type vaporizer.

  The sliding throttle valve carburetor 1 according to the present embodiment has a Venturi-shaped mixing chamber 2, and a main bore 3 penetrating in the horizontal direction is formed in the mixing chamber 2. The air is drawn by the intake negative pressure of the engine and flows in the direction of the arrow a in the figure. Although not shown, the sliding throttle carburetor 1 has an upstream end (the left end in FIGS. 1 and 2) connected to an air cleaner and a downstream end connected to an engine intake system. Has been.

  In addition, a cylindrical cylinder portion 2a is erected integrally with an upper portion of the mixing chamber 2, and a piston valve type sliding throttle valve 4 is vertically moved in the cylinder portion 2a (air flow in the main bore 3). In a direction orthogonal to the direction). Although not shown, a tapered jet needle is attached to the lower end of the sliding throttle valve 4 so that its diameter gradually decreases downward. The sliding throttle valve 4 is always urged downward (throttle side) by a spring, and is connected to the accelerator portion via a throttle wire.

  Further, a float chamber (not shown) is attached to the lower part of the mixing chamber 2, and fuel is accommodated in the float chamber. A main nozzle 5 is provided in the float chamber on the same axis as the jet needle, and the upper end of the main nozzle 5 opens into the main bore 3 in the mixing chamber 2. And the front-end | tip part of the jet needle bound to the lower end of the sliding throttle valve 4 is inserted in the inside of the main nozzle 5 from upper direction.

  Thus, in the present embodiment, as shown in FIGS. 1 to 3, a long groove 6 is formed in a part of the outer peripheral surface of the sliding throttle valve 4 in the vertical direction, and this groove 6 is mixed. The main bore 3 in the chamber 2 is always open. Further, as shown in FIGS. 1, 2, and 4, a purge hole 7 that selectively communicates with the groove 6 formed in the outer peripheral surface of the sliding throttle valve 4 is formed in the inner peripheral surface of the cylinder portion 2 a. Is open. In the present embodiment, the groove 6 formed on the outer peripheral surface of the sliding throttle valve 4 is formed to have a length that always opens to the main bore 3 regardless of the stroke of the sliding throttle valve 4. The length of the groove 6 may be set to a length at which communication with the main bore 3 is cut off when the throttle opening is from a high opening to a full opening.

  Here, FIG. 1 shows a state in which the sliding throttle valve 4 is in a fully closed state and the engine is in an idle operation state. At least when the sliding throttle valve 4 is fully closed, the groove 6 of the sliding throttle valve 4 is shown. This length is set so that the purge hole 7 is closed by the sliding throttle valve 4. Alternatively, the purge hole 7 is formed at a position where the purge hole is closed by the sliding throttle valve 4 at least when the sliding throttle valve 4 is fully closed.

  By the way, as shown in FIG. 1, the upper portion of the fuel tank 8 is connected to the canister 10 by the vapor pipe 9, and the purge pipe 11 extending from the canister 10 is formed in the cylinder portion 2 a of the sliding throttle carburetor 1. Connected to the purge hole 7. Note that the vaporized gas generated by the evaporation of fuel in the fuel tank 8 is introduced into the canister 10 through the vapor pipe 9 and is adsorbed by the activated carbon in the canister 10.

  Next, the operation of the sliding throttle valve carburetor 1 according to the present invention will be described.

  When an engine (not shown) is started, air in the atmosphere is sucked into an air intake duct (not shown) by the intake negative pressure of the engine, and this air is purified by passing through an air cleaner. It flows in the direction of arrow a in FIG. A negative pressure is generated in the main bore 3 by the air flow in the main bore 3, and the fuel in the float chamber is sucked out from the main nozzle 5 to the main bore 3 by this negative pressure and mixed with the air flowing therethrough. As a result, an air-fuel mixture having a predetermined air-fuel ratio (A / F) is formed. The air-fuel mixture thus formed in the sliding throttle carburetor 1 is introduced into the engine and used for combustion.

  Incidentally, the vaporized fuel vapor evaporated in the fuel tank 8 is adsorbed by the activated carbon in the canister 10 as described above. As shown in FIG. 1, the sliding throttle valve of the sliding throttle type carburetor 1 is used. Since the purge hole 7 is closed by the sliding throttle valve 4 when the engine 4 is in a fully closed state and the engine is in an idling operation state at a low rotation / low load, the fuel vaporized gas is not purged from the purge hole 7. Not. For this reason, the richness of the air-fuel mixture due to the purge of the vaporized gas is prevented, and the deterioration of the engine operation stability and the deterioration of the exhaust gas characteristics due to the richness of the air-fuel mixture are prevented.

  Thereafter, when the throttle part is operated and the sliding throttle valve 4 of the sliding throttle type carburetor 1 is moved up by the throttle wire as shown in FIG. 2, the flow area of the main bore 3 increases, so that the air flow Since the flow rate and flow velocity also increase and the jet needle bound to the lower end of the sliding throttle valve 4 moves up in the main nozzle 5, the opening area of the main nozzle 5 is enlarged and sucked out from the float chamber to the main bore 3. The amount of fuel to be increased. As a result, the amount of air-fuel mixture formed by the sliding throttle carburetor 1 also increases, the air-fuel ratio of the air-fuel mixture is kept substantially constant, and the engine speed and load increase.

  By the way, when the sliding throttle valve 4 is moved upward from the fully closed position, as shown in FIGS. 2 and 3, the groove 6 formed on the outer periphery of the sliding throttle valve 4 and the inner periphery of the cylinder portion 2a. Since the purge hole 7 opened to the surface communicates, the negative pressure in the main bore 3 acts on the canister 10 through the purge pipe 11, and the vaporized gas of fuel adsorbed on the activated carbon of the canister 10 is discharged from the purge pipe 11. The purged hole 7 and the groove 6 of the sliding throttle valve 4 are sucked into the main bore 3 and purged. The purged vaporized gas is sucked into the engine together with the air-fuel mixture and used for combustion.

  In the sliding throttle valve carburetor 1 according to the present embodiment, the length of the groove 6 of the sliding throttle valve 4 or the position of the purge hole 7 is arbitrarily set, so that the purge hole 7 is grooved. 6, that is, the timing at which the purge of the vaporized gas is started can be arbitrarily set.

  As described above, when the purge hole 7 opened to the inner peripheral surface of the cylinder portion 2a communicates with the groove 6 formed on the outer peripheral surface of the sliding throttle valve 4, the vaporized fuel vapor adsorbed on the canister 10 is purged. Since it is efficiently sucked into the main bore 3 from the hole 7 through the groove 6 of the sliding throttle valve 4 and purged, the sliding valve type carburetor 1 can obtain a purge performance equivalent to or better than that of the butterfly type carburetor. Can do.

  Here, FIG. 5 shows the results of actual measurement of the purge characteristics of the sliding throttle type vaporizer 1 according to the present embodiment. The measurement was performed when the purge hole diameter was set to φ1 mm and φ2 mm in a sliding throttle type vaporizer having a main bore diameter of φ16 mm.

  The horizontal axis in FIG. 5 is the throttle opening, and the vertical axis is the purge amount of the transpiration gas. As shown in the figure, when the throttle opening increases beyond a predetermined value, the purge amount of the transpiration gas increases rapidly. After showing the maximum value, as the throttle opening increases, the negative pressure decreases and the purge amount gradually decreases. As the throttle opening approaches full open, the purge amount of the transpiration gas approaches zero. Of course, it can be seen that the purge amount is larger when the purge hole diameter is larger (φ2 mm).

It is a longitudinal cross-sectional view of the principal part of the sliding throttle valve carburetor according to the first invention. It is a longitudinal cross-sectional view of the principal part of the sliding throttle valve carburetor according to the first invention. It is the sectional view on the AA line of FIG. It is a side view of the sliding throttle valve of the sliding throttle type vaporizer which concerns on 1st invention. It is a figure which shows the purge characteristic of the sliding throttle valve vaporizer which concerns on 1st invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sliding throttle type vaporizer 2 Mixing chamber 2a Cylinder part of mixing chamber 3 Main bore 4 Sliding throttle valve 5 Main nozzle 6 Sliding throttle valve groove 7 Purge hole 8 Fuel tank 9 Vapor piping 10 Canister 11 Purge piping

Claims (2)

A sliding throttle type carburetor for measuring fuel by inserting a sliding throttle valve slidably into a cylinder portion standing in the mixing chamber and sliding the sliding throttle valve in the mixing chamber. In
A purge hole that is formed in a part of the outer peripheral surface of the sliding throttle valve and that opens into the mixing chamber, and that communicates with the canister and selectively communicates with the groove on the inner peripheral surface of the cylinder portion. A sliding throttle type carburetor characterized by having an opening.   The length of the groove or the position of the purge hole is set to a length or position at which the purge hole is closed by the sliding throttle valve when the sliding throttle valve is fully closed. Sliding throttle valve type vaporizer.

Images