JPS5820388B2 - vaporizer - Google Patents

Description

[Detailed Description of the Invention] In general, in a sliding throttle valve type carburetor, when the throttle valve is opened at a high opening, the speed of air passing through the venturi decreases when the throttle valve is opened at a low speed, or when accelerating suddenly. It is difficult to demonstrate performance.

On the other hand, in capacity pressure type carburetors, the performance is unstable due to vertical movement of the suction piston due to the effect of suction negative pressure in the low speed operation range, and in order to secure the required air amount in the low speed operation range, In a capacity pressure type carburetor of the type in which a small fixed venturi is formed in advance, the air velocity in the low opening and low speed operating range is slow, and the fuel discharge delay cannot be reduced.

Particularly when modern air-fuel mixtures are set to be lean due to exhaust gas countermeasures, the lack of acceleration and output during transient periods is a major problem.

In view of these problems, the present invention uses a butterfly valve as the main throttle valve, engages the throttle valve with a suction piston that moves by suction negative pressure up to a medium opening range, and operates as a sliding throttle valve type carburetor. By operating the carburetor as a capacity pressure type carburetor in the high opening range, the carburetor is constructed as a carburetor that incorporates the advantages of each.

A vaporizer constructed for this purpose has already been proposed in Japanese Utility Model Publication No. 18812/1983, but the present invention is more improved and practical than these.

Examples of the present invention will be described below.

In Figure 1, 1 is the intake path of the carburetor, 2 is the throttle valve, 3 is the choke valve, 4 is the suction piston, 5 is the needle valve, 6 is the needle valve mounting screw, 7 is the main nozzle, and 8 is the suction at the diaphragm. It is fixed to the piston by a presser plate 9.

10 is a negative pressure chamber, 11 is an atmospheric chamber, 12 is a fixed shaft, and 13 is a spacer cylinder which is slidably inserted into the fixed shaft 12 and has a spring 14.
is pressed against the shaft end of the fixed shaft.

Reference numeral 15 denotes a lever which is supported on a fulcrum 16, one end of which contacts the presser plate 9, and a link 17 attached to the other end.

18 is a lever, 19 is a fulcrum, and 20 is a cam that moves together with the throttle valve.

21 is a throttle valve lever, 22 is a slow speed fuel system, 23 is a negative pressure outlet, and 24 is a tension spring for returning the lever 18.

The operation will be explained based on the above configuration.

FIG. 1 shows an idle link state, in which fuel is supplied from the slow fuel system 22.

The suction piston 4, together with the diaphragm 8 and the presser plate 9, descends under its own weight to achieve a predetermined alignment.

It is stationary in the operating position.

Although weak intake negative pressure is applied to the negative pressure chamber 10 through the negative pressure outlet hole 23, it does not rise because the lever 15 is in contact with the presser plate 9.

When the throttle valve 2 is opened from this state, the cam 20 rotates counterclockwise, using the lever 18 in contact as a fulcrum.

19 and rotate the lever 15 clockwise around the fulcrum 16 via the link 17 to release the lever 15 from contact with the presser plate 9.

Therefore, the piston 4 rises due to the intake negative pressure.

That is, the opening of the throttle valve 2 and the rise of the piston coincide.

Aperture. When the valve opens further and the piston 4 rises following it and comes into contact with the lower end of the spacer cylinder 13, from then on the spring 14
Even when the force is applied and the throttle valve is fully opened, the piston 4 moves up and down due to the balance between spring force and negative pressure, and functions as a conventional capacity pressure type carburetor.

. When closing the throttle valve, the lever 18 rotates counterclockwise around the fulcrum 190 by the spring 24 along the cam surface of the cam 20, presses the retaining plate 9 of the piston 4 via the link 17 and the lever 15, and descends. Apply force in the direction and the piston will move down.

Furthermore, since the cam 20 only follows the closing direction of the throttle valve by the spring 24, even if the piston 4 gets caught in dust or ice during its descent and remains open, only the throttle valve 2 will close completely. Since it is closed, it is effective in preventing the car from running out of control.

The present invention is further characterized in that the return spring 14 of the piston is locked in the middle by the spacer cylinder 13, which completely interlocks with the throttle valve 2 during the rising process of the piston 4 to the intermediate opening range. This eliminates the pressing force of the spring 14 and allows the piston to rise smoothly even with weak intake negative pressure.

FIG. 2 shows another embodiment of the present invention, in which the same parts as in FIG. 1 are designated by the same reference numerals. Unlike FIG. 25 is engaged, and one end contacts the pin 29 of the negative pressure actuator 26.

The device consists of a negative pressure chamber 27 partitioned by a diaphragm, a built-in spring 28, and a pin 29 fixed to the diaphragm.

A pin 30 is fixed to one end of the throttle valve lever 21A fixed to the throttle valve shaft, and this pin and the end surface of the cam 20A are pressed together by the spring 25.

Reference numeral 31 denotes a negative pressure operated valve, which is composed of a negative pressure chamber 32 separated by a diaphragm, a built-in spring 33, and a valve 34 fixed to the diaphragm.The negative pressure chamber 32 is communicated with the intake passage downstream of the throttle valve through a passage 35. However, the passage 36 communicates the downstream side of the throttle valve with the negative pressure chamber 27 of the negative pressure actuator 26.

There is a passage 37 branching from this passage, and this passage communicates with a negative pressure operated valve 310 and an atmospheric chamber 38 via a valve 34.

Note that 39 is an air opening, and 40 is a diaphragm.

To explain the action shown in FIG. 2, as the throttle valve is opened, the pin 30 fixed to the throttle valve lever 21A comes into contact with the cam 20A, so the cam 20A is rotated and the lever 1
8 to rotate the lever 15 clockwise around the fulcrum 16 via the link 17.

This movement is exactly the same as the configuration shown in Fig. 1, but the stage at which the throttle valve is closed is different, enriching the air-fuel mixture during deceleration, and contributing to afterburn measures, HC reduction measures, etc.

That is, the throttle valve is closed (and the cam 20A is closed by the spring 25).
However, if the intake negative pressure downstream of the throttle valve is strong, it passes through the passage 35 and rotates following the throttle valve lever 21A.
Since the valve 34 of the valve 34 is opened and the passage 36 is opened to the atmosphere, the pin 29 of the negative pressure actuating device 26 is projected by the spring 28.
Its tip abuts against the end of the cam 20A and prevents the cam 20A from rotating.

Therefore, the lever 15 does not rotate downward, and the piston 4 rises until it hits the lever 15 due to the negative intake pressure at that time, and fuel is discharged from the main nozzle 7, and together with the slow-speed fuel, the mixture ratio is enriched.

When the engine speed decreases and the intake negative pressure also weakens, the valve 34
is closed, the intake negative pressure is transferred to the negative pressure chamber 27 via the passage 36 and the throttle 40, and the pin 29 is pulled to allow the cam 20A to rotate.

Therefore, the lever 18, link 17, and lever 15 move to lower the piston 4.

In this way, if a strong intake negative pressure above a certain level is generated during deceleration, a rich air-fuel mixture is supplied to prevent afterburn from occurring.

Next, at the time of starting, since there is no intake negative pressure, the valve 34 of the negative pressure operating valve 31 closes the passage 37, and the negative pressure operating device 26 closes the passage 37.
The pin 29 is projected by a spring 28.

Before starting, the choke valve 3 is fully closed and the throttle valve 2 is in the first idle opening state, so the cam 20A rotates together with the throttle valve lever 21A, and the lever 15 is slightly separated from the presser plate 9 of the piston 4.

When the engine is cranked, the piston 4 rises slightly due to the intake negative pressure, and fuel is discharged from the main nozzle 7, forming a rich air-fuel mixture together with fuel discharge from the slow speed system.

The operation of this start-up is the same as that of the configuration of FIG.

As described above, in the present invention, the piston 4 opens and closes together with the throttle valve up to the middle opening range of the throttle valve, similar to a sliding valve type carburetor. A small venturi is formed.

Compared to a capacity pressure type carburetor, the piston 4 is fully closed, so the negative pressure in the main nozzle is higher, and since the movement is similar to that of a sliding valve type carburetor until the gap is opened, it is difficult to open the slow-speed fuel passage. By using a separate system, the well of the main nozzle can be utilized, and even without an acceleration pump, good acceleration performance can be obtained similar to that of a sliding valve type carburetor. Furthermore, in the high opening range, the low rotation range, which is the characteristic of a capacity pressure carburetor, can be achieved. 1. A stable driving performance can be obtained, and even if a low mixture ratio is set as a measure against exhaust emissions, the ride feeling will not be impaired, and countermeasures against deceleration can be taken at the same time.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is an external view of main parts showing another embodiment. 2... Throttle valve, 4... Suction piston, 12... Fixed shaft, 13... Interval cylinder, 16, 19... Fulcrum , 20, 20A...
...Cam, 21, 21A...-throttle valve''ゞ-26°
°°°゛°Negative pressure actuator, 30...pin, 13
1.--Negative pressure operated valve.

Claims (1)

[Scope of Claims] 1. In a carburetor having a suction piston 4 which has a throttle valve 2 and controls the venturi area depending on the amount of air passing through the intake passage 1, the suction piston 4 contacts the piston on its way up. A spacer cylinder 13 disposed in the spacer, a fixed shaft 12 that slidably holds the spacer cylinder 13, a spring 14 that is tensioned to prevent the spacer cylinder 13 from rising, and the throttle valve 2 integrally A moving cam 20 and the cam 2
0, a lever 18°15 that contacts the suction piston 5, and a link mechanism that engages between the two levers, and links the throttle valve 2 and the piston 4 until the throttle valve 2 is operated under partial load. A vaporizer characterized by: 2. In a carburetor having a suction piston 4 which has a throttle valve 2 and controls the venturi area by the amount of air passing through the intake passage 1, an interval cylinder is arranged so as to contact the suction piston 4 on its way up. 13, a spring 14 tensioned to prevent the rise of the spacer cylinder 13, a cam 20A that rotates freely with the throttle valve shaft, levers 1B and 15 that contact the cam 20A and the suction piston 5, and both of the levers. a link mechanism that engages between;
A throttle valve lever 2 that engages with the cam 20A in the opening direction of the throttle valve.
1A, a negative pressure operating valve 31 that controls intake negative pressure, and a negative pressure operating device 26 that increases the negative pressure from the operating valve 31, and links the piston 4 and throttle valve 2 until partial load operation. and when decelerating, the negative pressure actuating device 26 activates the cam 20A.
A carburetor, characterized in that the movement of a lever that contacts the piston 4 is controlled by a link mechanism that rotates the piston 4 and engages with the link mechanism.