JPS63272955A - Slide throttle valve type carburetor - Google Patents

Abstract

PURPOSE:To enable obtaining an excellent airtight connecting by tapering a connection face between the lower recess part of a carburetor proper and a jet block for closing a throttle valve guide hole in the constitution wherein a throttle valve is so mounted within said hole formed in an intake passage as to be freely slidable. CONSTITUTION:A slide throttle valve 3 so positioned as to be freely slidable in a valve guide hole 8 punched through a carburetor proper 1 has a circular arc side 3A opposing the side of an engine. And the throttle valve guide hole 8 is so formed as to penetrate down to the lower recess part 1A of the carburetor proper 1 from the upper part thereof via an intake passage 2. A jet block with a main fuel system M and a low speed fuel system S arranged therein is so provided as to close said throttle valve guide hole 8. In this case, a tapered connection 1C is formed in said lower recess 1A and, on the other hand, a tapered connection face 9A corresponding to said face 1C is formed on the upper part of the jet block 9, thereby enabling the airtight connection of the jet block 9.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a carburetor that adjusts and controls the volume and concentration of a mixture supplied to an engine, and particularly relates to a carburetor that allows a throttle valve to be moved freely into a throttle valve guide hole that is connected to an intake duct. This relates to a sliding throttle valve type carburetor, which is often used as a carburetor for motorcycle engines. [Prior Art] Conventionally, as mentioned above, sliding throttle valve type carburetors are often used in motorcycles, and carburetors for these engines tend to be particularly small and have high output. It is desirable to improve the suction efficiency of the device. A carburetor that aims to improve this suction efficiency is preferably one in which the cross-sectional shape of the sliding throttle valve is oval or rectangular rather than circular; for example, Japanese Patent Application No. 81-1 filed by the applicant
No. 52940. This consists of a sliding throttle valve with a side surface facing the engine side and a side surface facing the air cleaner side. This uses a sliding throttle valve formed by a straight part perpendicular to the longitudinal axis of the road and a connecting part that connects the straight part. According to this, the groove of the guide part of the sliding throttle valve to the carburetor body can be made extremely small, and according to this, the suction efficiency of the engine can be maintained well.1. This made it possible to improve output. When manufacturing such a carburetor, especially when forming the throttle valve guide hole, since the throttle valve guide hole is not cylindrical, it is necessary to pass through the intake passage from the top of the carburetor body and penetrate into the lower recess of the carburetor body. It is common practice to drill a throttle valve guide hole and then close the throttle valve guide hole opening into the lower recess of the carburetor body with a jet block. Now, paying attention to the connection between the jet block and the lower four parts of the carburetor body, the joint surface between the jet block and the lower concave part of the carburetor body is joined at a flat part that is approximately parallel to the longitudinal axis of the intake duct. be done. On the other hand, the jet block is equipped with so-called fuel systems, a main fuel system and a slow fuel system. A passage is formed in a substantially perpendicular direction. Then, the air passage in the jet block that supplies air to these fuel systems and the mixture controlled by the fuel system are supplied to the fuel hole (for example, the pilot out left hole) drilled in the carburetor body. The air-fuel mixture passages, that is, the passages that connect the passages formed in the carburetor body and the fuel system formed in the jet block, are formed in an L-shaped passage configuration. This is due to the fact that the joint surface of the jet block is arranged approximately parallel to the longitudinal axis of the intake passage, and the joint surface of the jet block corresponds to each passage in the carburetor body and is arranged approximately perpendicular to the joint surface of the jet block. A hole drilled (perpendicular to the longitudinal axis of the intake passage) and a hole bored approximately parallel to the joint surface of the jet block that connects to the fuel system (perpendicular to the longitudinal axis of the intake passage) This is because it is configured by the two sides (substantially parallel). [Problems to be Solved by the Invention] This conventional sliding throttle valve type carburetor has the following problems. In other words, as mentioned above, the air passage and mixture passage formed in the jet block are bent in an L-shape, so the air or mixture flowing there collides with the bend and the flow is disturbed, so it is not smooth. fluid flow is obstructed. This makes it difficult for the fluid to follow smoothly, especially during acceleration operation in which the engine speed rapidly increases, making it difficult to improve the transient performance of the engine. In addition, since the machining is L-shaped, two machining axes are required for a single passage. Furthermore, the occurrence of cracks at the intersections caused processing problems. [Means for Solving the Problems] The sliding throttle valve type carburetor according to the present invention has been developed in view of the above-mentioned problems, and it is an object of the present invention to provide a sliding throttle valve type carburetor particularly excellent in transient response. In order to achieve this purpose, a throttle valve guide hole is drilled, which is connected to the intake passage that passes through the carburetor body, and which passes through the intake passage from the top of the carburetor body to the lower concave part of the carburetor body. In a sliding throttle valve type carburetor, a throttle valve guide hole opening into a lower concave portion of the carburetor body is closed and joined with a jet block having a fuel system inside. A part of the joint surface between the lower concave portion of the carburetor body and the jet block is joined by a tapered surface. [Operation] A part of the joint surface between the jet block and the lower four parts of the carburetor body is tapered, and this tapered joint surface is used to straighten the air passage and mixture passage formed in the jet block. passages (passages connecting each passage bored in the carburetor body and the fuel system formed in the jet block), so fluid flow can be made smooth. [Example] Hereinafter, one example of the sliding throttle valve type carburetor according to the present invention will be explained as follows. , will be explained using Figure 3. 1 is a carburetor main body through which an intake passage 2 passes;
1 is a sliding throttle valve that is slidably disposed in a throttle valve guide hole bored in a carburetor main body 1, which will be described later, and has, for example, the following structure. That is, it is formed by an engine side facing side surface 3A (left side in the figure) facing the engine side and an air cleaner side facing side surface 3B facing the air cleaner side, and this engine side facing side surface 3A has an arc shape (single shape). It is formed in a semicircular shape with a radius R of 1. And the engine side opposite side 3A
A guide side surface 3C13C is provided from each of the arcuate ends A and B of the guide side surface 3C13C substantially along the longitudinal axis x-x of the intake passage 2,
The other end gBc of this guide side surface 3C13C, D (4
The air cleaner side opposite side surface 3B is formed from the opposite side of the air cleaner side opposite side surface 3A. (In addition, the guide side 3C
(The width of 13G is preferably a small width of about 3 mm.) Furthermore, the air cleaner side opposing side surface 3B will be described in detail. From the other ends C, D of the guide side surface 3C13C, the straight portions 3D, 3D substantially perpendicular to the longitudinal axis aX-X of the intake passage 2 and the longitudinal axis x-x of the intake passage 2, and The straight portions 3D and 3D are connected to each other by a connecting portion 3E that protrudes toward the air cleaner side (to the right in FIG. 3). Furthermore, a cutaway 3F is provided at the bottom of the sliding throttle valve 3 that opens into the intake passage 2 to control the intake passage negative pressure that acts on the needle jet, which will be described later. An inclined surface is formed from the opposing side surface 3B toward the engine side opposing side surface 3A. Further, a jet needle 4 is arranged in the sliding throttle valve 3 to be inserted into a needle jet described later to control the amount of fuel. Reference numeral 5 denotes a float window main body disposed at the lower part of the carburetor main body, a float chamber 6 is formed by the vaporizer main body 1 and the float window main body 5, and the float chamber 6 includes a float 7 and a float valve (not shown). A constant liquid level is created by the valve seat. In order to achieve the above-mentioned purpose, the system is constructed as follows. That is, reference numeral 8 denotes a throttle valve guide hole formed in the carburetor body l, which passes from the upper part of the carburetor body 1 connected to the intake passage 2 through the intake passage 2 to the lower recess IA of the carburetor body l. The cross-sectional shape of the throttle valve guide hole 8 is as shown in FIG.
Straight section 30.3 between A and the air cleaner side opposite side surface 3B
1) has a shape similar to the connected shape. (In addition, the shape of the air cleaner side facing side surface 3B is not a continuous connection shape of straight part 3D-connection part 3E-straight part 3D, but is made into a straight line shape by simply connecting straight part 3D-30.It is a sliding throttle valve. This is because the connection part 3E of the air cleaner side facing side surface 3B is not recessed into the carburetor main body side below the intake passage 2 when the sliding throttle valve 3 is at a low opening. In the case where the connecting portion 3E is recessed into the carburetor main body side below the intake passage 2, the shape is the same as that of the air cleaner side facing side surface 3B of the sliding throttle valve 3.) The lower recess IA has a tapered joint surface I for joining the jet block described later.
This joint surface 1c may be the entire circumference or a part thereof, and this can be selected depending on the arrangement of various passages. Further, a main air passage 10 and a pilot mixture passage IE are opened in a tapered joint surface IC formed in a lower recess IA of the carburetor main body l. (Note that the passages that open to this joint surface IC can be added or removed depending on the function.) Reference numeral 9 denotes a throttle valve guide hole 8 that opens in the lower recess of the carburetor main body 1.
This jet block is formed as follows. Inside the jet block 9, a main fuel system M and a low-speed fuel system S are arranged as fuel systems. The low-speed fuel jet 12 as the low-speed fuel system S is arranged substantially orthogonal to the longitudinal axis xx of the intake passage 2 . A tapered joint surface 8A is formed on the upper part of the jet block 9 in correspondence with the tapered joint surface IC formed on the carburetor body.
A has a main air introduction passage 8B whose one end corresponds to the main air passage ID opening to the joint surface 1C of the carburetor main body 1, and whose other end corresponds to the gap on the outer periphery of the needle jet 11; Corresponding to the pilot mixture passage IE that opens to the joint surface IC, a pilot mixture outlet passage 9C whose other end is connected to the low-speed fuel system S opens. The main air introduction passage 8B and the pilot air mixture flow passage 3C are located in the jet block 9 and are formed substantially parallel to the longitudinal axis x-x of the intake passage 2. Reference numeral 13 denotes a sealing member for maintaining airtightness arranged between the joint surfaces IC and 9A of the jet block 9 and the carburetor body 1, and 14 denotes a seal member for attaching the jet block 9 to the carburetor body l. This is a screw for According to the sliding throttle valve type carburetor of the present invention having such a configuration, first, the throttle valve guide hole 8 is bored in the carburetor body 1 from the upper part of the carburetor body 1 to the downward concave portion IA, and then the jet block 9 is opened. After making the tapered joint surface 8A correspond to the tapered joint surface IC provided in the lower recess IA of the carburetor main body 1, the jet block 9 is attached to the carburetor main body l with screws. Therefore, the main air flowing into the main air passage ID is transferred from the main air introduction passage 9B of the jet block 9 to the needle jet 1.
1, mixed with the fuel sucked out from the needle jet 11, and sucked out into the intake passage 2. On the other hand, the low-speed air-fuel mixture sucked out from the low-speed fuel system S is drawn from the pilot air-fuel mixture flow path 9C. Pilot mixture passage IE
The air is sucked out into the air intake passage 2 through the air.

【Effect of the invention】

According to the sliding throttle valve type carburetor of the present invention, the following effects can be achieved. (1) At least a part of the joint surface between the carburetor main body 1 and the jet block 9 is made into a tapered joint surface IC19A,
Since air or air mixture passages are arranged on the tapered joint surfaces IC and 9A, it is possible to achieve a joint with better airtightness compared to flat joints, and the above-mentioned passages are reliably connected. It was possible to do so. (2) Taper the main air introduction passage 8B and pilot mixture flow passage 9C, which are bored in the jet block 9, to correspond to the main air passage 10 or the pilot mixture passage 1E, which are bored in the carburetor body l. joint surface 8
By opening at A, it becomes possible to drill and arrange the passages for the main fuel system M and the low-speed fuel system S substantially parallel to the longitudinal axis x-x of the intake passage 2.
Since the flow of air or air-fuel mixture is straight instead of curved in the conventional L-shape, the flow of each fluid in the passage can be made smooth, and in particular, the transient performance of the engine can be improved. This is what was created. Note that the shape of the sliding throttle valve is not limited to that of this embodiment, and the tapered joint surface may be the entire circumference of the pilot jet or a part of it, so at least It is sufficient that the connecting portion of the passage between the carburetor main body and the jet block is a tapered joint surface.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the sliding throttle valve type carburetor according to the present invention, FIG. 2 is a top plan view of FIG. 1 with the top cover removed, and FIG. FIG. 3 is a top plan view of the carburetor body with the sliding throttle valve used in the figure removed; 1... Carburetor body, IA... Lower recess of carburetor body, IC... Tapered joint surface, 10... Main air passage, IE... Pilot mixture passage. , 8... Throttle valve guide hole, 9... Jet block, 9A... Tapered joint surface, 8B... Main air introduction path, 90... Pilot mixture flow path. , Nu 2g x 3ri

Claims (2)

[Claims] (1) A throttle valve guide hole is drilled from the upper part of the carburetor body through the intake passage to the lower concave part of the carburetor body, which is connected to the intake passage passing through the carburetor body. In a sliding throttle valve type carburetor in which a throttle valve guide hole opening in a lower recess is closed and joined with a jet block having a fuel system inside, a part of the joint surface between the lower recess of the carburetor body and the jet block. A sliding throttle valve type carburetor made by joining the two on a tapered surface. (2) A throttle valve guide hole is drilled in connection with the intake passage passing through the carburetor body, passing from the upper part of the carburetor body through the intake passage and penetrating into the lower recessed part of the carburetor body. In a sliding throttle valve type carburetor in which a throttle valve guide hole opening in a lower recess is closed and joined with a jet block having a fuel system inside, a part of the joint surface between the lower recess of the carburetor body and the jet block. are joined with a tapered surface, and an air passage is connected to the tapered joint surface of the lower concave part of the carburetor body.
A mixture passage is opened, and an air passage opening to the tapered joint surface of the carburetor body, an air passage corresponding to the mixture passage, and a mixture passage are bored in the tapered joint surface of the jet block. A sliding throttle valve type carburetor.