JPS59113247A - Variable venturi type carburetor - Google Patents

Abstract

PURPOSE:To fit a bearing easily to a suction piston shaft of a variable venturi carburetor. CONSTITUTION:A bearing 13 is inserted into an annular space 12 formed between a suction piston shaft 9 and a support shaft 10. The bearing 13 consists of a hollow cylindrical sleeve 14 made of a synthetic resin, and a plurality of ball inserting holes 15 are formed in the outer peripheral surface of the sleeve 14 on both end parts of the same, in the manner that they are spaced equiangularly from each other. When balls 16 are inserted into respective holes 15, they are held securely in the holes 15 by the elastic force of the sleeve 14, without causing coming-out of the balls 16 from the holes 15. Therefore, the bearing 13 can be fitted easily to the suction piston shaft 9.

Description

[Detailed description of the invention] The present invention relates to a variable venturi type carburetor.

a suction piston is slidably inserted into the carburetor casing to separate the interior of the casing into an atmospheric pressure chamber and a negative pressure chamber, the suction piston having a suction piston shaft extending in a direction opposite to the needle;
A variable venturi carburetor has been proposed in which a hollow cylindrical support tube surrounding a suction piston shaft is fixed to a casing, and the suction piston shaft is supported by a linear ball bearing. This linear ball bearing consists of multiple rows of ball groups aligned in the axial direction of the SAXILON piston shaft, and each ball group circulates within a support cylinder. Therefore, this linear ball bearing has a complicated structure, and there is a problem in that the manufacturing cost increases when this linear ball bearing is used. On the other hand, bearings that have similar functions to linear ball bearings and are inexpensive are known in other industrial fields. This bearing consists of a hollow cylindrical sleeve made of metal.

A plurality of ball insertion holes are formed on the outer peripheral surface of both axial ends of the sleeve, and balls are fitted into these ball insertion holes from the outside. However, when assembling a variable venturi type carburetor, such bearings are
If an attempt is made to fit the bearing onto the Y-piston shaft, the ball will fall out of the ball insertion hole and become trapped, resulting in the problem that it becomes extremely difficult to assemble the bearing.

The object of the present invention is to provide a variable venturi type carburetor in which such an inexpensive bearing can be easily incorporated.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, 1 is a carburetor main body, 2 is an intake passage extending vertically, 3 is a suction piston that moves laterally within the intake passage 2, and 4 is a needle attached to the tip surface of the suction piston 3. .

Reference numeral 5 indicates a throttle valve provided in the intake passage 2 downstream of the suction piston 3, and reference numeral 6 indicates a chamber 70. A venturi portion 7 is formed between the tip end surface of the suction piston 3 and the inner wall surface of the intake passage 2. Ru.

A casing 8 is fixed to the carburetor body 1, and the suction piston 3 is slidably inserted into the casing 8. The suction piston 3 includes a hollow cylindrical suction piston shaft 9 extending in the opposite direction to the needle 4, and a support cylinder 10 surrounding the suction piston shaft 9 is fixed to the casing 8. As shown in FIG.
is formed from a hollow cylindrical member having an inner diameter larger than the outer diameter of the suction piston shaft 9, and the outer end of the support cylinder 10 is closed by a blind cover 11. The suction piston shaft 9 is arranged coaxially with the support cylinder 10.

A bearing 13 is inserted into an annular gap 12 formed between the suction piston shaft 9 and the support cylinder 10. As shown in FIGS. 4 and 5, this bearing 13 consists of a substantially hollow cylindrical sleeve 14 made of a synthetic resin material such as polyamide resin or polyacetal resin. A plurality of ball insertion holes 15 are bored on the surface at regular angular intervals. This ball insertion hole 15 is located in the large diameter portion 1 located on the outside.
5a and a small diameter portion 15b located inside, and a ball 16 having a diameter approximately equal to that of the large diameter portion 15g is inserted into each ball insertion hole 15. When the ball 16 is inserted into the ball insertion hole 15, it projects slightly outward from the outer peripheral surface of the sleeve 14 and slightly inward from the inner peripheral surface of the sleeve 14.

Note that these balls 16 can freely rotate within the ball insertion hole 15. Furthermore, annular ribs 17 and 18 are integrally formed on both end surfaces of the sleeve 14. On the other hand, as shown in FIG. 1, a snap ring 20 is fitted into a ring groove formed on the outer peripheral surface of the outer end of the suction piston shaft 9, and A snap ring 21 is fitted into the ring groove formed on the top. An annular spring retainer 22 having a cross section as shown in FIGS. 1 and 2 is inserted inside the snap ring 20, and an annular spring retainer 22 having a cross section as shown in FIGS. 1 and 3 is inserted inside the snap ring 21. A curved annular spring retainer 23 is inserted. Further, a compression spring 24 is inserted between one end surface of the bearing sleeve 14 and the spring retainer 22, and a compression spring 25 is inserted between the other end surface of the bearing sleeve 14 and the spring retainer 23. These compression springs 25 serve to keep the bearing 13 in the center of both snap rings 20, 21 at all times. When the suction piston 3 moves, the ball 16 moves accordingly, and at this time, the bearing 13 moves in the direction of movement of the suction piston 3 at a speed equal to the speed of movement of the suction piston 3.

The interior of the casing 8 is divided by the suction piston 3 into a negative pressure chamber 28 and an atmospheric pressure chamber 29.

A compression spring 30 that constantly presses the suction piston 3 toward the venturi portion 7 is inserted into the negative pressure chamber 28 . The negative pressure chamber 28 is connected to the venturi section 7 through a suction hole 31 formed in the suction piston 3, and the atmospheric pressure chamber 29 is connected to the intake passage 2 upstream of the suction piston 3 through an air vent 32.

On the other hand, a fuel passage 33 extending in the axial direction of the needle 4 is formed in the carburetor main body 1 so that the needle 4 can enter therein, and a metering jet 34 is provided in the fuel passage 33. The fuel passage 33 upstream of the metering jet 34 is connected to the float chamber 6 via a downwardly extending fuel pipe 35.
The fuel in the float chamber 6 is sent into the fuel passage 33 via this fuel pipe 35. Furthermore, a hollow cylindrical nozzle 36 is fixed on the inner wall surface of the intake passage 2 and is arranged coaxially with the fuel passage 33 . The needle 4 extends through the nozzle 36 and the metering jet 34, and the fuel is metered by the annular gap formed between the needle 4 and the metering jet 34 before being delivered from the nozzle 36 into the intake passage 2. As shown in FIG. 1, a raised wall 37 is formed above the nozzle 36 and projects horizontally into the intake passage 2. As shown in FIG.

Flow rate control is performed between this raised wall 37 and the tip of the suction piston 3. When engine operation is started, air flows downward in the intake passage 2. At this time, since the air flow is restricted between the suction piston 3 and the raised wall 37, negative pressure is generated in the venturi portion 7, and this negative pressure is guided into the negative pressure chamber 28 through the succilon hole 31. The suction piston 3 moves so that the pressure difference between the negative pressure chamber 28 and the atmospheric pressure chamber 29 becomes a substantially constant pressure determined by the spring force of the compression spring 3o, that is, so that the negative pressure in the venturi portion 7 becomes substantially constant.

As mentioned above, the sleeve 14 of the bearing 13 is made of a synthetic resin material and has elasticity. Therefore, when the ball 16 is inserted into the ball insertion hole 15, the ball 16 is moved by the elastic force of the sleeve 14. Ball insertion hole 15
The ball is held in the ball insertion hole 15 without falling off. Therefore, when the bearing 13 with the ball 16 inserted into the ball insertion hole 15 is fitted onto the suction piston shaft 9, the ball 16 does not fall out of the ball insertion hole 15, and the bearing 13 is thus inserted into the suction piston shaft. It can be easily assembled on top of 9.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of a variable venturi type carburetor according to the present invention, Fig. 2 is a perspective view of the spring retainer, Fig. 3 is a perspective view of the spring retainer, Fig. 4 is a side view of the bearing, and Fig. 5 is a perspective view of the spring retainer. FIG. 4 is a sectional view of FIG. 4; 3...Suction piston, 4...Needle. 7...Venturi part, 8...Casing. 9... Suction piston shaft, 10... Support tube. 13...Bearing, 14...Sleeve. 15...Ball insertion hole, 16...Ball. Patent Applicant: Toyota Motor Corporation Aisan Industries, Ltd. Patent Application Agent: Akira Aoki, Patent Attorney, Kazuyuki Nishidate, Patent Attorney, Kyo Nakayama, Patent Attorney, Akira Yamaguchi (9),,9. . Figure 4 14 298- Figure 5 Procedural amendment (voluntary) February 78, 1980 Director of the Patent Office Kazuo Wakasugi 1, Indication of the case 1988 Patent application No. 222081 2, Invention name Variable pliers -Relationship with the person making the amendment (3) Name of patent applicant (320) Name of Toyota Motor Corporation Aisan Kogyo Co., Ltd. (4) Agent (external) 5. Subject of amendment (1) Details "Detailed Description of the Invention" column (2) Drawings (
[Figure 5] 6. Contents of the amendment (1) (a) Page 5 of the specification, lines 2 to 5, "This ball insertion hole...... can be inserted δ."? ``This ball insertion hole 15 has a large diameter part 15a located in the middle, a small diameter part 15b located on the inside, and a small diameter part 15C located on the outside.
Each ball insertion hole 150 has a small diameter portion 15C in the large diameter portion 15a. A ball 16 is inserted through it. The large diameter portion 15a has a slightly larger diameter than the diameter of the ball 16, is slightly smaller than the diameter of the small diameter portion 15Ci ball 16, and has a slightly larger diameter than the small diameter portion 15b. ” will be corrected. (b) Page 8, lines 11 to 13 of the specification, "Ball 16i...by force"? The ball 16 can be inserted into the large diameter tA15a through the small diameter portion 1501. At this time, the ball 16 is corrected by the small diameter portions 15b and 15C. (2) Correct Figure 5 as shown in the attached sheet. l Catalog drawing of attached documents (Fig. 5) 1 copy Fig. 5

Claims (1)

[Claims] a suction piston slidably inserted into a carburetor casing, the suction piston separating the interior of the casing into an atmospheric pressure chamber and a negative chamber, the suction piston having a suction piston shaft extending in a direction opposite to the needle; In a variable venturi type carburetor, a hollow cylindrical support cylinder surrounding the suction piston shaft is fixed to the casing, and the suction piston shaft is movable in the axial direction inside the support cylinder. A hollow cylindrical bearing sleeve made of a synthetic resin material is inserted into the annular space formed between the support cylinders, and a plurality of ball insertion holes are formed on the outer peripheral surface of both axial ends of the bearing sleeve. A variable venturi type carburetor in which a ball that contacts both the suction piston shaft and the support cylinder is inserted into the insertion hole.