JPH0740680Y2 - Downdraft diaphragm carburetor - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a carburetor that controls the amount and concentration of air-fuel mixture supplied to an engine, and is divided by a diaphragm into a fuel regulator chamber and an atmospheric chamber, and a fuel regulator chamber is provided. A diaphragm type carburetor that operates a diaphragm according to the negative pressure in the intake passage to operate, controls the opening and closing of a valve seat provided at the end of the fuel passage by using a fuel control valve, and thereby supplies an air-fuel mixture to the engine In particular, the present invention relates to a down-draft diaphragm carburetor in which an air intake passage penetrating the carburetor main body penetrates in a vertical direction and air flowing in the air intake passage flows downward from above.

[Conventional technology]

A conventionally used down-draft diaphragm type vaporizer is shown, for example, in Japanese Utility Model Publication No. 62-103452. This will be described with reference to FIGS. 3 and 4.

Reference numeral 1 denotes a carburetor main body in which an intake passage 2 penetrates in the vertical direction XX, and a throttle valve 3 for controlling the opening area of the intake passage 2 is located below the intake passage 2 in the vertical direction XX. It is attached to a shaft 4 rotatably supported by the carburetor body 1.

One end of the main fuel passage 5 is open to a venturi portion V formed in a substantially middle portion of the intake passage 2 of the carburetor main body 1. The other end of the main fuel passage 5 is one side surface 1A of the carburetor main body 1 ( Third
It opens on the left side in the figure).

Further, 6 is a bypass hole as a low-speed injection hole B opened in the intake passage 2 corresponding to the throttle valve 3, and 7 is a bypass hole 6
It is a pilot outlet hole as a low speed injection hole B opened further downstream, and the low speed injection hole B composed of the bypass hole 6 and the pilot outlet hole 7 is connected to the low speed fuel passage 8. , Vaporizer body 1
It opens on one side surface 1A (left side surface in FIG. 3).

Reference numeral 9 denotes a carburetor main body member arranged on one side surface 1A of the carburetor main body 1, and at least an opening portion of the main fuel passage 5 and an opening portion of the low speed fuel passage 8 which are open to the one side surface 1A of the carburetor main body 1 are formed. The carburetor main body member 9 is closed at one side surface 9A (right side surface in FIG. 3).

Further, a concave portion 9C is formed on the other side surface 9B of the vaporizer main body member 9 (the left side surface of the vaporizer main body member 9 in FIG. 3), and a concave portion 10A is formed on the concave portion 9C of the vaporizer main body member 9. The cover 10 is disposed, and the diaphragm 11 is disposed between the cover 10 and the other side surface 9B of the carburetor main body member 9.

Thus, one side face 11A of the diaphragm 11 and the vaporizer main body member 9
The fuel regulator chamber 12 is formed by the recess 9C of
The other side surface 11B of the diaphragm 11 and the recess 10A of the cover 10 form an atmosphere chamber 13. The main fuel passage 5 is provided in the upper portion of the fuel regulator chamber 12 in the vertical direction XX.
The main fuel jet 13 connected to the low speed fuel passage 8 below the fuel regulator chamber 12 in the vertical direction XX.
The low-speed fuel jet 14 connected to is opened.

That is, the main fuel supply passage M as the main fuel system of the carburetor is formed by the main fuel jet 13 and the main fuel passage 5. One end of the main fuel supply passage M is open to the venturi portion V and the other end is formed. Will be opened above the fuel regulator chamber 12.

Further, the low speed fuel supply passage S as the low speed fuel system of the carburetor
Is a low speed injection hole B, a low speed fuel passage 8, a low speed fuel jet 14
The low speed fuel supply passage S has one end opened to the intake passage 2 near the throttle valve 3 and the other end opened to a position below the fuel regulator chamber 12.

In addition, the fuel regulator chamber 12 has a fuel inflow passage communicating with the fuel source and the fuel regulator chamber of the fuel inflow passage.
A valve seat is arranged at the opening end to 12 and a control valve for opening and closing the valve seat is arranged corresponding to the valve seat, and the control valve operates the engine to operate the intake passage 2 The negative pressure generated at the main fuel supply path M,
By introducing the fuel into the fuel regulator chamber 12 through the low speed fuel supply passage S and operating the diaphragm 11 and the control rod, the valve seat is opened to supply the fuel in the fuel source into the fuel regulator chamber 12 through the fuel inflow passage. To do. (The fuel source, the fuel inflow passage, the valve seat, the control valve, and the control rod are not shown.) Further, 15 is a check valve seat provided in the main fuel passage 5, and the check valve seat 15 corresponds to the main fuel jet 15. A normally closed check valve 16 that allows only the flow from 13 to the Venturi section V is arranged. That is,
The check valve 16 is located inside the main fuel passage 5 and
From the fuel regulator chamber 12 side.

[Problems to be solved by the device]

According to such a conventional down-draft diaphragm carburetor, the negative pressure generated in the intake passage 2 during low speed operation of the engine enters the fuel regulator chamber 12 from the low speed injection hole B through the low speed fuel supply passage S. It is introduced, and by this, the diaphragm 11 operates toward the carburetor main body 1 side,
The control valve opens the valve seat to allow the fuel in the fuel source to flow into the fuel regulator chamber 12 through the fuel inflow passage, and the fuel flows through the low speed fuel supply passage S from the low speed injection hole B to the intake passage 2
It is sucked into the inside of the engine to operate at low speed.

In addition, during such a low speed operation, since a large negative pressure does not act on the main fuel passage 5, the check valve 16 has the check valve seat 15
Is closed and there is no air leak from the main fuel supply passage M into the fuel regulator chamber 12, and the fuel regulator chamber 12 responds to the negative pressure in the intake passage 2 introduced from the low speed fuel supply passage S. Fuel can be controlled.

On the other hand, during high speed operation of the engine, a large negative pressure generated in the intake passage 2 including the Venturi portion V is generated from the low speed fuel supply passage S and the main fuel supply passage M in the fuel regulator chamber.
(The check valve 16 opens the check valve seat 15 by the negative pressure in the main fuel passage 5 on the Venturi portion V side.) And, in such operation, the check valve 16 enters the fuel regulator chamber 12. Since the negative pressure introduced is higher than the negative pressure in the intake passage 2 during the low speed operation, the diaphragm 11 can be moved toward the carburetor main body 1 side more than in the low speed operation state. The fuel suitable for high-speed operation can be supplied into the fuel regulator chamber 12, and this fuel is sucked into the intake passage 2 from the main fuel supply passage M and the low-speed fuel supply passage S. I was able to satisfy the driving.

Then, when the engine is stopped from the above-mentioned operating state of the engine, the fuel is held in the fuel regulator chamber 12 in a state of being stored. Here, the check valve seat 15 provided in the main fuel supply passage M is closed and held by the check valve 16. This is because the negative pressure in the intake passage 2 disappears as the engine stops, and the negative pressure for opening the check valve 16 does not act.

On the other hand, in the low-speed fuel supply path S, the check valve seat 15 is closed by the check valve 16 and the fuel regulator chamber 12 is in a closed state.
Even if the low-speed fuel supply passage S is opened to the lower position of the above, the fuel in the fuel regulator chamber 12 does not overflow from the low-speed fuel supply passage S into the intake passage 2. However, it is not preferable when a large external force is applied to the engine including the carburetor while the engine is stopped, for example, when the engine is transported.

That is, in the state shown in FIG. 3, when a large leftward external force is applied, the check valve seat 15 may be temporarily opened by the inertial force of the check valve 16. According to this, from the main fuel supply passage M, the fuel regulator chamber 12
Atmospheric pressure is temporarily introduced into the fuel regulator chamber 12 by introducing air into the fuel regulator chamber 12. According to this, the fuel is stored in the fuel regulator chamber 12 through the low-speed fuel supply passage S opening below the fuel regulator chamber 12. The fuel (shown by the hatched portion in FIG. 4) overflows from the low-speed injection hole B into the intake passage 2. As described above, if the fuel in the fuel regulator chamber 12 temporarily leaks into the intake passage 2 when the engine is stopped, the fuel that should originally be used for operating the engine is wasted. However, it is not preferable in terms of fuel economy.

[Means for solving the problem]

The downdraft diaphragm carburetor according to the present invention has been made in view of the above problems, and is to provide the carburetor with excellent fuel economy. -X is penetrated by an intake passage, and at a lower position of the intake passage in a vertical direction XX, a carburetor main body provided with a throttle valve for controlling an opening area of the intake passage, and one side of the carburetor main body are provided. A fuel regulator chamber is formed by the concave portion of the carburetor main body and one side surface of the diaphragm by the diaphragm arranged between the concave portion provided and the cover covering the concave portion, and the atmospheric chamber is formed by the concave portion of the cover and the other side surface of the diaphragm. The fuel regulator chamber has a main fuel supply passage that opens to the venturi of the intake passage and a low-speed fuel supply passage that corresponds to the throttle valve and that connects to the low-speed injection hole that opens to the intake passage. In the mouth the downdraft type diaphragm type carburetor, in which is opened at the upper position than the substantial center of the opening position of the fuel regulator chamber of the low-speed fuel supply passage in the vertical direction of the fuel regulator chamber.

[Action]

Even when the engine is stopped and a large external force is applied to the draft, the check valve temporarily opens the check valve seat and the fuel regulator chamber temporarily becomes atmospheric pressure, the fuel in the fuel regulator chamber remains fuel. Since only the fuel from the top of the regulator chamber to the opening position of the low-speed fuel supply passage that opens above the center of the fuel regulator chamber to the fuel regulator chamber overflows into the intake passage, compared to the conventional overflow rate. It can be greatly reduced.

〔Example〕

An embodiment of the down-draft diaphragm type carburetor according to the present invention will be described below with reference to FIGS.

The same reference numerals are used for the same structures as those in FIGS. 3 and 4, and description thereof will be omitted.

20 has a bypass hole 6 at one end and a pilot outlet hole 7
Is a low-speed fuel passage which is connected to the low-speed injection hole B and whose other end is open to one side surface 1A of the carburetor body 1 (left side surface of the carburetor body 1 in FIG. 1). The opening to the one side surface 1A of 1 reaches the upper position including substantially the center of the fuel regulator chamber 12.

Reference numeral 21 denotes a low-speed fuel jet having the other end opening to the fuel regulator chamber 12 and one end opening to the low-speed fuel passage 20, and the opening position of the low-speed fuel jet 21 to the fuel regulator chamber 12 is vertical to the fuel regulator chamber 12. The upper position includes the substantially center in the direction. More specifically, as shown in FIG. 2, when the fuel regulator chamber 12 is circular, the center CC of the fuel regulator chamber 12 is the center of the circle, and when it is rectangular or irregular, it is vertical. It refers to the center in the direction.

Therefore, in FIG. 2, the hatched portion corresponds to the upper position including the substantially center C-C in the vertical direction of the fuel regulator chamber 12.

Thus, the low speed fuel supply passage N comprises the low speed fuel jet 21, the low speed fuel passage 20, and the low speed injection hole B. The opening position of the low speed fuel supply passage N to the fuel regulator chamber 12 is the fuel regulator of the low speed fuel jet 21. It is an opening position to the chamber 12.

Next, the operation will be described. When the engine is stopped while the engine is operating, the fuel is stored and held in the fuel regulator chamber 12. In this state, when a large external force is applied to the engine including the carburetor, the check valve 16 in the closed state may temporarily open the check valve 15. According to this, the pressure in the fuel regulator chamber 12 temporarily becomes atmospheric pressure, and the fuel in the fuel regulator chamber 12 is slower than the low-speed fuel jet 21 in the low-speed fuel jet 21 and the low-speed fuel passage 2.
Overflow from the low speed injection hole B (bypass hole 6, pilot outlet hole 7) into the intake passage 2 through 0.

In such a state, a point to be particularly noted is that the opening position of the low-speed fuel supply passage N to the fuel regulator chamber 12, that is, the opening position of the low-speed fuel jet 21 to the fuel regulator chamber 12 in the vertical direction of the fuel regulator chamber 12. Since the fuel is stored in the fuel regulator chamber 12 at the upper position including the center of the fuel regulator chamber 12, the fuel stored in the fuel regulator chamber 12 is only the fuel in the fuel regulator chamber 12 located above the low speed fuel jet 21 in the low speed fuel supply path N. More intake passage 2
It does not overflow inside. Ie low speed fuel jet
The fuel in the fuel regulator chamber 12 below 21 does not overflow from the low-speed fuel supply passage N into the intake passage 2, and is still stored and retained in the fuel regulator chamber 12.

Therefore, when the engine is stopped, the amount of fuel overflowing from the fuel regulator chamber 12 into the intake passage 2 can be reduced, so that the fuel economy can be prevented from being impaired.

In this embodiment, the low speed fuel supply passage N is opened to the fuel regulator chamber 12 through the low speed fuel jet 21,
In short, the fuel regulator chamber for low-speed fuel to the low-speed injection hole B
The fuel intake from 12 may be set to the upper position including the substantially center in the vertical direction of the fuel regulator chamber 12,
There is no limitation on the low-speed fuel jet 21 etc. due to the intake.

Further, in this embodiment, the carburetor main body member is used to form the low speed fuel passage and the fuel regulator chamber,
The carburetor main body member may be omitted without using the carburetor main body member and the carburetor main body member may be omitted.

Further, the opening position of the low speed fuel supply passage to the fuel regulator chamber is not limited to that position as long as it is an upper portion including substantially the center in the vertical direction of the fuel regulator chamber, and may be appropriately set.

[Effect of device]

As described above, according to the downdraft diaphragm carburetor of the present invention, the opening position of the low-speed fuel supply passage to the fuel regulator chamber is opened to the upper position including substantially the center in the vertical direction of the fuel regulator chamber. Since the amount of fuel overflowing from the fuel regulator chamber to the intake passage via the low-speed fuel supply passage at the time of stoppage can be reduced, a remarkable effect can be achieved in terms of fuel economy.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a down-draft diaphragm carburetor according to the present invention, FIG. 2 is a left side view of an essential part of FIG. 1, and then FIG. 3 is a conventional down-draft diaphragm. FIG. 4 is a side view of the left main part of FIG. 1 ... Vaporizer body, 2 ... Intake passage 3 ... Throttle valve, 10 ... Cover 11 ... Diaphragm 12 ... Fuel regulator chamber N ... Low-speed fuel supply passage B ... Low-speed injection hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Tetsuo Kamiya 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki Heavy Industries Ltd. Akashi Plant (56) References JP-A-61-185662 (JP, A) JP-A-SHO 53-147133 (JP, A) Actual public Sho 51-29364 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. An intake passage 2 penetrates the inside in a vertical direction XX, and a lower position of the intake passage in the vertical direction XX is
It is arranged between the carburetor body 1 provided with the throttle valve 3 for controlling the opening area of the intake passage 2, the recess 9C provided on one side of the carburetor body 1, and the cover 10 covering the recess 9C. The diaphragm 11 allows the recess 9C of the carburetor body 1 and one side surface 11 of the diaphragm 11.
At A, the fuel regulator chamber 12 is formed and the cover 1
Atmosphere chamber 13 at recess 10A of 0 and other side surface 11B of diaphragm 11
In the fuel regulator chamber 12, a main fuel supply passage M that opens to the Venturi portion V of the intake passage 2 is opened, and a low speed connecting to the low speed injection hole B that opens to the intake passage 2 corresponding to the throttle valve 3 is formed. In the down-draft type diaphragm carburetor with the fuel supply passage N opened, the down position of the low speed fuel supply passage N to the fuel regulator chamber 12 is opened above the approximate center of the fuel regulator chamber 12 in the vertical direction. Draft diaphragm carburetor.