JP2835585B2 - Constant vacuum vaporizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor for adjusting and controlling the amount and concentration of an air-fuel mixture supplied to an engine. A constant-vacuum carburetor in which a negative pressure-operated valve movably disposed in the guide cylinder of the negative-pressure operated valve for variably controlling the area of the venturi portion in accordance with the negative pressure generated in the intake passage is provided. About.

[0002]

2. Description of the Related Art In such a conventional constant vacuum vaporizer,
A partition is disposed at the upper end of the negative pressure actuated valve, and a pressure receiving chamber is formed on the upper surface of the partition, which communicates with the inside of the intake passage via a negative pressure introducing passage. An atmosphere chamber is formed which is communicated via a passage. And a labyrinth type is used as this partition. In this labyrinth-type partition, an annular portion is formed at the upper end of the negative pressure operating valve, and a plurality of labyrinth grooves are formed on the outer periphery of the annular portion. This annular portion is movable with a very small gap in the negative pressure cylinder. Placed in That is, the pressure in the annular portion is reduced by the throttle action of the labyrinth groove to suppress the leakage in the vertical direction of the labyrinth groove, and a pressure receiving chamber connected to the intake path is formed on the upper surface of the annular portion,
An air chamber connected to the atmosphere is formed separately on the lower surface of the annular portion.

[0003]

The conventional labyrinth-type constant vacuum vaporizer has the following problems to be solved. The outer diameter of the annular portion of the negative pressure actuated valve and the inner diameter of the negative pressure cylinder are formed with an extremely small gap in order to effectively obtain the pressure drop effect by the labyrinth groove, and the annular shape formed on the outer periphery thereof is formed. The gap must be formed uniformly. According to the above, the outer diameter of the annular portion of the negative pressure operated valve and the inner diameter of the negative pressure cylinder need to be formed with extremely high precision. Further, as described above, the negative pressure cylinder is provided with another cup-shaped member in order to increase the processing accuracy, and is assembled to the carburetor main body after the inner diameter portion is precisely processed. When assembled to the carburetor body, the negative pressure cylinder must be accurately and concentrically mounted to the annular portion of the negative pressure operated valve. Also, the precision machined annular portion of the negative pressure actuated valve and the inner diameter portion of the negative pressure cylinder must be very carefully stored and transported in the parts stage. Furthermore, machining is required to obtain the dimensional accuracy of the outer diameter of the annular portion of the negative pressure actuated valve and the inner diameter of the negative pressure cylinder. A low-cost synthetic resin material cannot be used. This is because the synthetic resin material is inferior in workability as compared with the metal material. According to the above, the processing and assembling are required to have high accuracy, storage and transportation efficiency are reduced, and furthermore, the freedom of choice of synthetic resin materials with low material costs is hindered, It has been difficult to reduce the manufacturing cost.

[0004] The present invention has been made in view of the above problems,
It is an object of the present invention to obtain an inexpensive constant-vacuum vaporizer without using a diaphragm as a partition of a negative pressure operated valve.

[0005]

According to the present invention, an object of the present invention is to provide a negative pressure operated valve guide cylinder connected to an intake passage penetrating a carburetor body. In a constant-vacuum carburetor in which a negative-pressure operating valve for variably controlling the area of a venturi section in accordance with a negative pressure generated in a passage is movably disposed, the carburetor body has an upper end from one side of an intake passage. A negative pressure cylinder that opens toward the cylinder and a negative pressure operated valve guide cylinder that opens from the intake path into the negative pressure cylinder are formed, while the negative pressure operated valve moves to the negative pressure operated valve guide cylinder. A negative pressure actuated valve portion which is freely supported and forms a venturi portion by its bottom and an intake passage, an annular portion formed at an upper end of the negative pressure actuated valve portion, and is formed on an outer periphery of the annular portion. A negative pressure operated valve portion of the negative pressure operated valve formed by the annular ring groove. The annular portion is slidably disposed on the negative pressure cylinder via an annular elastic ring fitted in the ring groove, and is disposed movably on the negative pressure actuated valve guide cylinder. This is achieved by forming a pressure receiving chamber with a cover that closes the opening of the cylinder, and forming an air chamber communicating with the atmosphere on the lower surface of the annular portion.

[0006]

The resilient ring fitted in the ring groove of the negative pressure operated valve is resiliently arranged in the ring groove in the radial direction. It often moves while sliding on the inner diameter of the negative pressure cylinder. Therefore,
A pressure receiving chamber is formed on the upper surface of the annular portion of the negative pressure operated valve, and an atmosphere chamber is separately formed on the lower surface of the annular portion, so that a constant vacuum vaporizer can be provided. Since the outer diameter of the annular part of the negative pressure operated valve is arranged with a large gap without directly contacting the inner diameter of the negative pressure cylinder, accurate accuracy is required for the outer diameter of the annular part and the inner diameter of the negative pressure cylinder. Never be.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a constant vacuum vaporizer according to the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a carburetor body formed with an intake passage 2 penetrating the side thereof, and a float chamber 4 is formed by the float chamber body 3 disposed below the carburetor body 1. In the float chamber 4, a constant fuel level is formed by the cooperative action of the valve seat 5, the float valve 6 and the float 7. Reference numeral 8 denotes a negative pressure cylinder formed integrally with the carburetor body 1 and opens from one side of the intake path 2 toward the upper end 8A. The negative pressure cylinder 8 is integrally cast-molded toward the upper end 8A when the carburetor body 1 is formed. According to this, the inner diameter 8B of the negative pressure cylinder 8 is cast twice, for example. Draft is applied. The inner diameter 8B of the negative pressure cylinder 8 has a slightly larger diameter at the upper end 8A by 2 degrees than the lower inner diameter. In the negative pressure cylinder 8, a negative pressure operating valve guide cylinder 9 which opens at an intermediate portion of the intake path 2 opens. Incidentally, the negative pressure cylinder 8 itself does not directly open to the intake path 2. A cover 10 is disposed on the upper end 8A of the negative pressure cylinder 8,
The upper opening of the negative pressure cylinder 8 is closed by the cover 10.

[0008] The negative pressure operating valve 11 comprises the following. 11A
Is a negative pressure operating valve portion movably supported by the negative pressure operating valve guide cylinder 9, and an annular portion 11B having an annular shape is integrally formed above the negative pressure operating valve portion 11A. The annular portion 11B has a ring groove 11C opening toward the outer periphery.
In this example, two ring grooves 11C are formed.
Was formed. The outer diameter 11D of the annular portion 11B is
It has a diameter smaller than the inner diameter 8B of the negative pressure cylinder 8, and is set so that the outer diameter 11D does not come into contact with the inner diameter 8B when the negative pressure operating valve 11 moves from the low opening to the high opening. . Reference numeral 12 denotes an elastic ring fitted and arranged in the ring groove 11C. The elastic ring 12 expands and contracts in the direction of its diameter A, and is formed of, for example, a synthetic resin material and has a gap B in the circumferential direction. The elastic ring 12 is better shown in FIG.

The negative pressure operated valve 11 will be described mainly with respect to a part related to the negative pressure operated valve 11 assembled to the carburetor body 1 as follows. First, the ring groove 11 of the negative pressure actuated valve 11
The elastic ring 12 is fitted and arranged in C. At this time, the outer diameter of the elastic ring 12 is larger than the inner diameter 8B of the negative pressure cylinder 8, while the inner diameter of the elastic ring 12 has a gap C with respect to the groove bottom 11D of the ring groove 11C. The negative pressure operated valve 11 fitted with the elastic ring 12 is inserted into the carburetor body 1 through the opening of the upper end 8A of the negative pressure cylinder 8, and at this time, the negative pressure of the negative pressure operated valve 11 is reduced. The operating valve section 11A is movably disposed in the negative pressure operating valve guide cylinder 9 of the carburetor body 1 while the elastic ring 12
The outer diameter 11D is slightly reduced, and is arranged in contact with the inner diameter of the negative pressure cylinder 8 with a slight elastic force.
The reason why the outer diameter of the elastic ring 12 is reduced is that the elastic ring 1
2, a gap B is formed in the circumferential direction, and the inner diameter of the elastic ring 12 is smaller than the groove bottom 11D of the ring groove 11C.
Has a gap C. According to the above description, the negative pressure operating valve 11 is movably disposed on the negative pressure operating valve guide cylinder 9 via the negative pressure operating valve 11A, while the elastic ring 12 has a slight elasticity on the inner diameter 8B of the negative pressure cylinder 8. It is arranged in sliding contact with force. Next, the upper end 8A of the negative pressure cylinder 8
The cover 10 is disposed and fixed thereon, whereby the opening of the negative pressure cylinder 8 is closed. At this time, a spring 13 is contracted between the cover 10 and the negative pressure operating valve 11.

According to the above, since the elastic ring 12 is disposed in sliding contact with the inner diameter 8B of the negative pressure cylinder 8 with elastic force, the leakage between the upper surface 11E and the lower surface 11F of the annular portion 11B can be suppressed. The pressure receiving chamber P is formed by the upper surface 11E of the portion 11B and the negative pressure cylinder 8 closed by the cover 10, while the atmosphere chamber K is formed separately by the lower surface 11F of the annular portion 11B. Then, the negative pressure in the intake passage 2 is introduced into the pressure receiving chamber P through a negative pressure introduction passage 11H penetrating through the bottom 11G of the negative pressure operating valve 11, and is introduced into the atmosphere chamber K. The atmosphere is introduced through the atmosphere introduction path 14. The bottom 11G of the negative pressure actuated valve 11 and the intake passage 2
To form a venturi section V, and the negative pressure actuated valve 1
The jet needle 15 attached to 1 is inserted and arranged in a needle jet 16 opening to the venturi portion V.

When a negative pressure is generated in the venturi section V during operation of the engine, the negative pressure is applied to the negative pressure operating valve 1.
1 is introduced into the pressure receiving chamber P through the negative pressure introducing passage 11H. The negative pressure in the pressure receiving chamber P causes the upward pressure on the negative pressure actuating valve 11 by the negative pressure, and the negative pressure actuation by the spring 13. The position of the negative pressure actuated valve 11 is determined by the balance between the downward pressing force on the valve 11 and the venturi V formed by the bottom portion 11G of the negative pressure actuated valve 11 and the intake passage 2. In addition, the negative pressure actuated valve 11
In the above operation, the diameter of the elastic ring 12 changes according to the inner diameter 8B of the negative pressure cylinder 8.

[0012]

According to the constant vacuum vaporizer according to the present invention,
The following effects are obtained. Leakage between the upper surface and the lower surface of the annular portion of the negative pressure actuated valve was suppressed by sliding an elastic ring fitted in the ring groove with a slight elastic force on the inner diameter of the negative pressure cylinder. Therefore, since the outer diameter of the annular portion and the inner diameter of the negative pressure cylinder could be brought into a non-contact state with a relatively large gap, the outer diameter of the annular portion of the negative pressure operated valve and the inner diameter of the negative pressure cylinder were measured. It is not necessary to form the precision with high precision as in the prior art. According to the above,
The processing of the outer diameter of the annular portion and the processing of the inner diameter of the negative pressure cylinder can be eliminated. Even if the processing is performed, high precision is not required, and the manufacturing cost can be reduced. Further, as described above, since the processing is no longer necessary, it is possible to use an inexpensive synthetic resin material, which could not be conventionally employed due to the difficulty of the processing, for the negative pressure operating valve and the negative pressure cylinder. This also contributes to a reduction in the manufacturing cost. Also, it is not necessary to form the inner diameter of the negative pressure cylinder with high precision, and even if there is a draft angle, the elastic ring slides on the inner diameter of the negative pressure cylinder by the elastic force of the elastic ring. Since the negative pressure cylinder can be formed in a specific manner, the manufacturing cost of the negative pressure cylinder can be reduced, and the assembling of the negative pressure cylinder to the carburetor body is not required. This can also reduce the manufacturing cost. Although the cover is attached to the carburetor body, it is easy to assemble it because it only closes the opening of the negative pressure cylinder.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a constant vacuum vaporizer according to the present invention.

FIG. 2 is a perspective view of an elastic ring used in FIG.

[Description of Signs] 1 Vaporizer main body 2 Intake path 8 Negative pressure cylinder 9 Negative pressure operated valve guide cylinder 10 Cover 11 Negative pressure operated valve 11A Negative pressure operated valve portion 11B Annular portion 11C Ring groove 11E Upper surface 11F Lower surface 11G Bottom portion 12 Elasticity Ring P Pressure receiving chamber K Atmosphere chamber

Claims (1)

(57) [Claims] A negative pressure actuated valve guide cylinder is connected to an intake passage penetrating the carburetor body, and a venturi section is provided in the negative pressure actuated valve guide cylinder in response to a negative pressure generated in the intake passage. In a constant vacuum carburetor in which a negative pressure operating valve for variably controlling the area is movably arranged, a carburetor body 1 includes a negative pressure cylinder 8 opening from one side of an intake passage 2 toward an upper end 8A. ,
A negative-pressure operating valve guide cylinder 9 is formed to open from the intake passage 2 toward the negative-pressure cylinder 8.
Are movably supported by the negative pressure operating valve guide cylinder 9, and have a bottom 11 G and a suction path 2 to form a venturi portion V, a negative pressure operating valve portion 11 A, and a negative pressure operating valve portion 1.
An annular portion 11B formed at the upper end of 1A, and an annular portion 11B
And a ring groove 11C formed in the outer periphery of the negative pressure operated valve. The negative pressure operated valve portion 11A of the negative pressure operated valve is movably arranged in the negative pressure operated valve guide cylinder 9 and the annular portion 1 is formed.
1B is disposed in sliding contact with the negative pressure cylinder 8 via an annular elastic ring 12 fitted into the ring groove 11C, and a cover 10 for closing the upper surface 11E of the annular portion 11B and the opening of the negative pressure cylinder 8 is provided. To form a pressure receiving chamber P, and an atmosphere chamber K facing the lower surface 11F of the annular portion 11B and communicating with the atmosphere.
A constant-vacuum type vaporizer characterized by forming a segment.