JPH0515914B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a carburetor that adjusts and controls the amount and concentration of air-fuel mixture supplied to an engine, and particularly relates to a carburetor that has a throttle valve connected to an intake passage. This invention relates to a sliding throttle valve type carburetor that is movably disposed within a guide cylinder and is used as a carburetor for motorcycle engines.

[Conventional technology]

Conventionally, as mentioned above, since sliding throttle valve type carburetors are often used in motorcycles, it is particularly important that the intake air supplied to the engine be efficiently produced. It is desirable that the groove remaining on the side of the intake passage of the throttle valve guide tube that guides and holds the valve is as small as possible. For this purpose, intake air is drawn from the side facing the engine, which has a circular arc shape with a radius R starting from the longitudinal axis of the intake passage, and from the end of the side facing the engine, which is sandwiched between the longitudinal axis of the intake passage. A planar air cleaner that connects an outer surface extending along the longitudinal axis of the air intake channel and an end of each outer surface on the air cleaner side along an orthogonal line perpendicular to the longitudinal axis of the intake channel. A sliding throttle valve is used that includes a side surface facing the air cleaner side, and a ventilee-forming surface that projects further toward the air cleaner side than the side surface facing the air cleaner side. According to the sliding throttle valve having such a shape, the groove of the throttle valve guide cylinder formed on the side of the intake passage is a cylindrical throttle valve,
The groove area could be significantly reduced compared to the one using a square throttle valve.

In order to facilitate machining, the throttle valve guide tube that slides and guides the sliding throttle valve having such an unusual shape is connected to the lower concave portion of the carburetor body from the lower intake passage of the carburetor body that faces the throttle valve guide tube. It is common practice to drill a through hole toward the lower recess of the carburetor body, and then close the through hole opening into the lower recess of the carburetor body with a jet block. A needle jet is disposed in this jet block and opens by inserting a jet needle disposed in the sliding throttle valve to control the fuel.

[Problem to be solved by the invention]

According to such a conventional sliding throttle valve carburetor, the through hole facing the throttle valve guide tube that slides and guides the sliding throttle valve equipped with the jet needle has the following drawbacks: The through-hole that needs to be formed and opens into the lower recess of the carburetor body must be closed by accurately positioning the through-hole by a jet block with a needle jet.

The closing position of the jet block with respect to the through hole of the carburetor body varies, the jet needle attached to the sliding throttle valve slidably disposed in the throttle valve guide tube, and the needle jet disposed in the jet block. The relative positional relationship between the jet needle and needle jet becomes inaccurate, and the annular gap formed by the jet needle and needle jet becomes uneven, which impedes accurate and uniform air-fuel mixture control. This is not desirable in terms of harmful exhaust gas regulations.

Here, the irregularly shaped through hole can be formed extremely easily, inexpensively, and accurately by broaching. However, the outer circumferential surface of the jet block that closes the through hole is machined using an NC milling cutter, etc., and although it is possible to form an accurate outer circumferential surface, the machining setup and processing time increase, making it difficult to manufacture. The cost increases significantly, which is not desirable for mass production.

The sliding throttle valve type carburetor of the present invention was developed in view of the above problems, and the lower opening of the through hole facing the throttle valve guide cylinder bored in the carburetor body is made extremely simple by using a jet block. It is an object of the present invention to provide accurate closing, enable accurate and uniform air-fuel mixture control, and perform the closing at extremely low cost.

[Means to solve problems]

According to the present invention, in order to achieve the above-mentioned object, the float chamber body is arranged in the lower recessed part of the carburetor body to form a float chamber, and the intake passage passing through the carburetor body has an opening facing upward from the intake passage. A throttle valve guide cylinder is arranged in series, and inside the throttle valve guide cylinder, an arcuate engine-side facing side surface having a radius R starting from the longitudinal axis XX of the intake passage; Intake air is connected to the outer surfaces extending along the longitudinal axis X-X of the intake passage from the ends of the opposite side surfaces facing the engine across the axis X-X, and to the ends of the outer surfaces on the air cleaner side. A planar air cleaner side facing side surface connected along an orthogonal line Y-Y perpendicular to the longitudinal direction axis X-X of the airway, and a ventilee forming surface that protrudes further toward the air cleaner side from the air cleaner side facing side surface. A sliding throttle valve is slidably arranged, and the bottom of the sliding throttle valve has one end connected to a float chamber formed below the carburetor main body and the other end opened toward the intake passage. In a sliding throttle valve type carburetor in which a jet needle is arranged to be inserted into the needle jet, at least the side surface of the sliding throttle valve facing the engine side is provided on the lower intake passage surface of the carburetor body facing the throttle valve guide cylinder. A positioning hole formed by a positioning surface on the side facing the engine side having the same shape, a positioning surface on the outside side having the same shape as the outside surface, and a positioning surface on the side facing the air cleaner side having the same shape as the side facing the air cleaner side. At the same time, an insertion hole is opened at the lower end of the positioning hole on the float chamber side through a locking step facing outward, and an insertion hole is opened at the lower recessed part of the carburetor body facing the float chamber, and the positioning hole is opened at the lower end on the float chamber side. , a locking step, and an insertion hole to form a through hole that penetrates the lower intake passage surface of the carburetor body and the lower recess of the carburetor body; a positioning hole insertion protrusion having an opening around the entire circumference; an abutment part at the lower end of the positioning hole insertion protrusion that abuts the locking step; and a positioning hole insertion protrusion extending downward from the abutment part for insertion. It is formed by an insertion protrusion that is inserted into the hole, and a fuel control protrusion that extends further downward from the insertion protrusion and reaches into the float chamber, and further, on the outer peripheral surface of the positioning hole insertion protrusion, A positioning protrusion is provided protrudingly in contact with the positioning surface on the side opposite to the engine side, the positioning surface on the outer side, and the positioning surface on the opposite side to the air cleaner side. Open the needle jet to be communicated, bring the abutting part of the jet block into contact with the locking step of the through hole, and place the positioning protrusion on the positioning surface on the engine side opposite side of the positioning hole, the positioning surface on the outer side, and the air positioning surface. The jet block closes the through hole of the carburetor body by bringing it into contact with the positioning surface on the opposite side of the cleaner side and inserting the insertion protrusion into the insertion hole.

[Effect]

When the through hole opening in the lower concave portion of the carburetor body is closed by the jet block, the abutting portion of the jet block abuts and locks against the locking step of the through hole, thereby blocking the jet block in the vertical direction. The position is accurately determined, and the positioning protrusion provided on the outer peripheral surface of the positioning hole insertion protrusion of the jet block abuts each positioning surface of the positioning hole facing the positioning protrusion, thereby positioning in the front circumferential direction. In such a state, the jet block closes the through hole opening into the lower concave portion of the carburetor body, and the through hole for the sliding throttle valve guide cylinder can be accurately and inexpensively positioned and closed by the jet block. can.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a sliding throttle valve type carburetor according to the present invention will be described below with reference to the drawings.

FIG. 1 is a top plan view showing one embodiment of a sliding throttle valve T. The sliding throttle valve T has an arcuate engine-side facing side surface 1 with a radius R starting from a longitudinal axis XX of an intake passage passing through the carburetor body, which will be described later, and a longitudinal axis of the intake passage. An outer surface extending along the longitudinal axis X-X of the intake passage from the ends 2 and 3 of the engine-side opposing side surface 1 (the engine side refers to the left side in FIG. 1) across the line X-X. 4, 5, outer surfaces 4, 5 extending along the axis X-X, and air cleaner side ends 6 and 7 of each outer surface 4, 5 (the air cleaner side is the right side in FIG. ) is the longitudinal axis of the intake passage
It consists of a planar air cleaner side facing side surface 8 connected along an orthogonal line YY perpendicular to , and a ventilee forming surface 9 protruding further toward the air cleaner side from the air cleaner side facing side surface 8.

A jet needle insertion hole 11 through which a jet needle (to be described later) is inserted is bored in the inner bottom 10 of the sliding throttle valve T toward the lower surface. Next, the carburetor main body C will be explained with reference to FIGS. 2 and 3.
FIG. 2 is a longitudinal sectional view of the carburetor main body, and FIG. 3 is a top plan view of FIG. 2.

The carburetor main body C has an intake passage 1 horizontally inside.
In FIG. 2, the left intake passage 12 is connected to an engine (not shown), and the right side is connected to an air cleaner (not shown).

A throttle valve guide cylinder 13 is connected and opened upward from the middle part of the longitudinal axis X-X of the intake passage 12, and a float chamber is provided below the carburetor main body C along with a float chamber main body to be described later. A lower recess 14 is formed.

The upper end of the throttle valve guide cylinder 13 opens at the upper part of the carburetor main body C, and the lower end opens at the lower intake passage surface 1 of the intake passage 12.
Reach 2A.

The throttle valve guide cylinder 13 has a shape capable of slidingly guiding the sliding throttle valve T described above.
has the same shape.

Lower intake path surface 12 facing the throttle valve guide tube 13
A through hole 15 is formed in the carburetor body C between the lower recess 14 of the carburetor body C and the lower recess 14 of the carburetor body C. Through hole 15
is formed by a positioning hole 16, a locking step 17, and an insertion hole 18 from the top toward the bottom.

The positioning hole 16 opens into the lower intake passage 12A of the carburetor main body C, and has a positioning surface 19 on the side facing the engine and having the same shape as the side surface 1 facing the engine of the sliding throttle valve T.
, outer surface positioning surfaces 20 and 21 having the same shape as the outer surfaces 4 and 5, and a side surface 8 facing the air cleaner side.
and an air cleaner side opposing side surface positioning surface 22 having the same shape as the air cleaner side.

A locking step 17 is formed outward from the lower end 23 of the positioning hole 16 on the float chamber side and parallel to the longitudinal axis XX of the intake air 12. An insertion hole 18 opening toward the lower recess 14 is opened below the outer end.

The through hole 15 is closed by a jet block J.

Jet block J is shown in FIGS. 4 and 5. FIG. 4 is a longitudinal sectional view, and FIG. 5 is a top plan view. The jet block J has a positioning insertion protrusion 24, an abutment part 25, and an insertion protrusion 26 from above.
and a fuel control protrusion 28. The positioning hole insertion protrusion 24 is inserted into the positioning hole 16 and has a shape with a gap S over the entire circumference with respect to the positioning hole 16. That is, the outer circumferential surface 24A of the positioning hole insertion protrusion 24 is connected to the positioning hole 1.
It forms a similar shape that is smaller by S relative to 6.

In FIG. 5, the positioning hole 16 is indicated by a two-dot chain line. On the outer peripheral surface 24A of the positioning hole insertion protrusion 24, a positioning protrusion 27 that comes into contact with the positioning surface 19 of the positioning hole 16 on the side opposite to the engine side, the positioning surfaces 20, 21 on the outer side, and the positioning surface 22 on the side opposite to the air cleaner side. is provided with a protrusion.

The positioning protrusion 27 protruding from the outer peripheral surface 24A is orthogonal to the pair of positioning protrusions 27 along the longitudinal axis XX of the intake passage 12 and the longitudinal axis XX of the intake passage 12. It is along the orthogonal line Y-Y. Then, a contact portion 25 is formed which extends laterally from the lower end of the positioning hole insertion protrusion 24 horizontally to the longitudinal axis XX of the intake passage 12 and abuts against the locking step portion 17 of the through hole 15. Further, an insertion protrusion 26 inserted into the insertion hole 18 from the outer peripheral end of the contact portion 25
extends downward, and this insertion protrusion 26
The fuel control protrusion 28 protrudes further downward.

Further, a needle jet 29 is disposed on the upper end surface 24B of the positioning hole insertion projection 24, passing through the fuel control projection 28 and extending into the float chamber to be described later.

As mentioned above, the positioning hole 16 of the through hole 15 of the carburetor main body C has the same shape as the engine side facing side surface 1, the outer side surfaces 4 and 5, and the air cleaner side facing side surface 8 of the throttle valve guide cylinder 13, Throttle valve guide tube 1
It is now possible to broach the inside of the through hole 15 from the upper opening of No.
6 could be formed in exactly the same shape as the throttle valve guide cylinder 13.

In addition, the ventilary forming surface 9 of the throttle valve guide cylinder 13
The guiding part, the locking step part 17 and the insertion hole 18
is formed by casting when the carburetor main body C is molded.

On the other hand, each positioning protrusion 2 of the jet block J
7, its position and LMNP are determined with the center of the needle jet 29 as a reference. Since this formation only needs to be performed on the tip end portion of each positioning protrusion 27, it can be formed accurately and easily by, for example, press working. The jet block J is attached to the carburetor body C in the following manner. This is shown in FIGS. 6 and 7. The positioning hole insertion protrusion 24 of the jet block J is inserted through the lower opening of the through hole 15 of the carburetor body C. According to this, the positioning insertion protrusion 24 of the jet block J is inserted into the positioning hole 16, and at this time, the positioning protrusion 27 provided protruding from the outer peripheral surface 24A of the positioning insertion protrusion 24 is inserted into the engine side opposite Side positioning surface 19, outer side positioning surface 20, 2
1 and the positioning surface 22 on the side opposite to the air cleaner side, the jet block J could be accurately positioned in the circumferential direction of the positioning hole 16.

On the other hand, since the contact portion 25 of the jet block J comes into contact with the locking step 17 of the through hole 15, the jet block J is positioned in the vertical direction, and the insertion protrusion 26 of the jet block J contacts the insertion hole 17 of the through hole 15. inserted within. Then, in this state, the jet block J is fixed to the carburetor main body C. For this fixation, appropriate fixing means such as screws, press-fitting, caulking, adhesive, etc. are used. By arranging the float chamber main body 30 below the carburetor main body C to which the jet block J is attached in this way to form a float chamber 31, and arranging the sliding throttle valve T within the throttle valve guide tube 13. The jet needle 32, which is then arranged on the sliding throttle valve T, can be inserted into the needle jet 29.

〔Effect of the invention〕

The sliding throttle valve type carburetor of the present invention as described above provides the following effects. The through hole drilled in the carburetor body, particularly the positioning hole, can have exactly the same shape as the throttle valve guide tube.

This is because the throttle valve guide tube and the positioning hole of the through hole are made to have the same shape, and the throttle valve guide tube and the positioning hole can be broached.

Also, it is inserted through the positioning protrusion formed on the outer circumferential surface of the positioning insertion protrusion of the jet block placed in the positioning hole, and the dimension from the center of the jet needle to the tip of each positioning protrusion is The dimensions could be accurately determined by machining only the tip.

By arranging the jet block in the positioning hole of the carburetor body through the positioning protrusion of the positioning insertion protrusion of the jet block, it becomes possible to accurately arrange the jet block with respect to the throttle valve guide cylinder. This makes it possible to accurately position the jet needle attached to the sliding throttle valve, which is slidably disposed within the throttle valve guide cylinder, and the needle jet, which is disposed on the jet block. It was made.

Therefore, the relative positions of the needle jet and jet needle can be accurately arranged, and accurate and uniform fuel control is possible, which has great effects in terms of engine operability and harmful exhaust gas regulations. play.

In addition, the positioning insertion protrusion does not require machining the entire outer circumferential surface of the protrusion, but only the tip of the positioning protrusion needs to be machined, so the machining can be done in a very short time and at low cost, making it easy to manufacture the vaporizer. This enabled cost reduction.

Especially when manufacturing jet blocks by molding,
If this positioning protrusion is made of a pin-replaceable type during mold manufacturing, it will be easy to maintain its accuracy, and even if the pin wears out during manufacturing, the pin can be replaced, making maintenance easier.

[Brief explanation of the drawing]

FIG. 1 is a top plan view of a sliding throttle valve used in the sliding throttle valve type carburetor of the present invention, FIG. 2 is a vertical sectional view of the carburetor main body, and FIG. 3 is a top plan view of FIG. 2. , FIG. 4 is a longitudinal sectional view of the jet block, FIG. 5 is a top plan view of FIG. The figure is a top plan view of figure 6,
The figure is a longitudinal sectional view showing the assembled state of the sliding throttle valve. 1... Engine side opposite side, 2, 3... End, 4, 5...
Outer surface, 6, 7... End, 8... Air cleaner side opposing side, 12... Intake path, 13... Throttle valve guide cylinder,
14... Lower recess, 15... Through hole, 16... Positioning hole, 17... Locking step, 18... Insertion hole, 19... Engine side opposite side positioning surface, 20, 21... Outer surface positioning surface, 22... Air cleaner side Opposing side positioning surface, 24... Positioning hole insertion protrusion, 25... Contact part, 26... Insertion protrusion, 27... Positioning protrusion, J...
Jet block, T...sliding throttle valve, C...carburizer body.

Claims (1)

[Claims] 1. The float chamber body 3 is located in the lower recess 14 of the carburetor body C.
0 to form a float chamber 31 and passing through the carburetor main body C, a throttle valve guide cylinder 13 that opens upwardly from the intake passage 12 is connected to the intake passage 12. , an engine-side facing side surface 1 having a circular arc shape with a radius R starting from the longitudinal axis XX of the intake passage 12; and an engine-side facing side surface 1 sandwiching the longitudinal axis XX of the intake passage 12. The outer surfaces 4 and 5 extend from the ends 2 and 3 of the air intake passage 12 along the longitudinal axis XX, respectively, and the air cleaner side ends 6 and 7 of the outer surfaces 4 and 5 are used for intake air. Longitudinal axis X- of path 12
A sliding surface consisting of a planar air cleaner side facing side surface 8 connected along the orthogonal line Y-Y perpendicular to The throttle valve T is slidably arranged, and the bottom part 10 of the sliding throttle valve T has a float chamber 31 whose one end is formed below the carburetor main body C.
In a sliding throttle valve type carburetor in which a jet needle 32 is arranged to be inserted into a needle jet 29 which is continuous with the needle jet 29 and whose other end opens toward the intake passage 12, the carburetor main body C faces the throttle valve guide cylinder 13. On the lower intake passage surface 12A of the sliding throttle valve T, there is provided an engine-side facing side surface positioning surface 19 having the same shape as the engine-side facing side surface 1 of the sliding throttle valve T, and an outer surface positioning surface 20, 21 having the same shape as the outer surfaces 4, 5. and an air cleaner side opposing side surface positioning surface 22 having the same shape as the air cleaner side opposing side surface 8.
An insertion hole 18 is opened in the lower end 23 on the side of the float chamber 31 of No. 6 through a locking step 17 directed outward to the lower recess 14 of the carburetor main body C facing the float chamber 31. The lower air intake passage 12 of the carburetor main body C has a positioning hole 16, a locking step 17, and an insertion hole 18.
A through hole 15 passing through the lower recess 14 of the carburetor main body C is formed, and a jet block J that closes the through hole 15 has an opening S over the entire circumference with respect to the positioning hole 16. a positioning hole insertion projection 24; a contact portion 25 at the lower end of the positioning hole insertion projection 24 that abuts the locking step 17; and an insertion hole 1 extending downward from the contact portion 25.
8; and a fuel control protrusion 28 that extends further downward from the insertion protrusion 26 and reaches into the float chamber 31; The outer circumferential surface 24A includes a positioning protrusion 2 that comes into contact with the engine side opposing side surface positioning surface 19, the outer surface positioning surfaces 20, 21, and the air cleaner side opposing side surface positioning surface 22.
A needle jet 2 is provided on the upper end surface 24B of the positioning hole insertion projection 24 to be connected to the float chamber 31 through the inside of the fuel control projection 28.
9 is opened, and the contact portion 25 of the jet block J is inserted into the through hole 15.
The positioning protrusion 27 is brought into contact with the positioning surface 19 on the side facing the engine, the positioning surfaces 20 and 21 on the outer side, and the positioning surface 22 on the side facing the air cleaner side of the positioning hole 16 facing thereto. A sliding throttle valve type carburetor is formed by inserting the insertion protrusion 26 into the insertion hole 18 to close the through hole 15 of the carburetor body C with a jet block J.