JPH10331719A - Rotary throttle valve type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform fine regulation of an intake air amount though rough regulation being contrary exhaust gas regulation is unpracticable. SOLUTION: In a rotary throttle valve carburetor to regulate an air amount through rotation of a throttle valve 8 and regulate a fuel amount through axial movement of a throttle valve 8, intake air amount regulation bolts 62 and 72 protruded to the interior of the intake air passage 12 and effect regulation from the outside are disposed at the portion, situated upper stream from the throttle valve 8, of the intake passage 12 and the portion, situated downstream from the throttle valve 8, of the intake passage 12. The head parts of the intake air amount regulation bolts 62 and 72 are contained the screw holes 61 and 71 of a carburetor body 18, and after regulation of the intake air amount regulation bolts 62 and 72, covers 63 and 73 are pressed in the screw holes 61 and 71.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor for an internal combustion engine used in a portable working machine, and more particularly to a rotary throttle valve type carburetor provided with a mechanism for adjusting an intake air amount (flow rate) when a throttle valve is fully opened.

[0002]

2. Description of the Related Art Conventional carburetors are generally provided with a low-speed fuel adjustment mechanism and a high-speed fuel adjustment mechanism. It is not preferable because it causes. In recent years, exhaust gas regulations have been introduced for internal combustion engines of portable working machines, and the fuel amount of the carburetor is regulated by a fixed jet, so that the driver cannot adjust the fuel amount without permission. However, it is desirable to be able to finely adjust the amount of fuel in order to obtain optimal matching between the carburetor and the engine.

That is, after the carburetor manufacturer adjusts the fuel amount with the fuel amount adjusting bolt on the test stand so that the fuel amount does not vary in the mass-produced carburetor, the carburetor is fixed so that the driver cannot adjust it. Or, generally, a cap for controlling the movement of the fuel amount adjusting bolt is inserted into the screw hole. In some cases, both the low-speed fuel adjustment bolt and the high-speed fuel adjustment bolt are fixed to prevent the driver from making arbitrary adjustments. With the configuration described above, the exhaust gas regulation value does not fall outside the regulation range due to a driver's handling error. However, in the mass production line of the engine manufacturer, the intake air amount also varies in the engine. Therefore, if the matching between the carburetor and the engine is poor, the exhaust gas regulation may not be satisfied. In case of such a case, it is preferable that the carburetor can adjust the intake air amount very slightly.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the object of the present invention is to make a large adjustment that does not deviate from exhaust gas regulations, but to make it possible to finely adjust the intake air amount (flow rate). It is to provide a type vaporizer.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a configuration of the present invention is to adjust the amount of air by rotating a throttle valve and adjust the amount of fuel by moving the throttle valve in the axial direction. That the intake volume adjustment bolts protruding into the intake path and being adjustable from the outside are disposed on the upstream side of the intake path throttle valve and on the downstream side of the intake path throttle valve. Features.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a small intake air amount adjusting bolt is projected to one or both of a portion of the intake passage upstream of the throttle valve and a portion of the intake passage downstream of the throttle valve. Although not affected, the intake negative pressure acting on the fuel injection hole of the fuel supply pipe can be adjusted. When the intake air amount adjusting bolt is projected into the intake passage, the passage area of the intake passage is reduced, and the intake negative pressure acting on the fuel injection hole of the fuel supply pipe changes.

For example, when the fuel efficiency is slightly reduced from a state where the fuel efficiency is higher than the optimum value, the intake air amount adjusting bolt at the downstream side of the fuel supply pipe of the intake passage is screwed in, and the fuel supply pipe downstream of the intake passage is supplied. By making the passage area of the side part slightly smaller than the passage area of the part on the upstream side of the fuel supply pipe in the intake passage, the intake negative pressure acting on the fuel supply pipe is weakened to the required exhaust gas regulation value. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. Will be closed. Throttle valve 8 having throttle hole 8a in cylindrical portion 2
Are fitted so as to be rotatable and slidable in the axial direction. Throttle valve 8
The shaft portion 14 extending upward from the shaft portion 1 is supported by the lid 17, and the shaft portion 1
A follower 16 is supported by a throttle valve lever 15 coupled to the upper end of the fourth. The shaft portion 14 is provided between the lid 17 and the throttle valve 8.
The follower 16 is moved by the force of the spring 13 surrounding the
When the throttle valve lever 15 is turned, the throttle valve 8 moves in the axial direction. At this time, it is screwed into the screw hole of the shaft portion 14 and the locking spring 5
The rod valve 3 regulated by the valve moves up and down together.

A fuel supply pipe 7 whose opening degree of the fuel injection hole 6 is adjusted by the rod valve 3 is fixedly supported on the bottom wall of the carburetor body 18. The fuel supply pipe 7 is passed through a check valve 47 and a fuel jet 46, and is supplied with a constant-pressure fuel chamber 38 which always holds fuel under a constant pressure.
Is communicated to.

A fuel pump A couples the membrane 53 and the intermediate body 43 to the lower surface of the carburetor body 18 and connects the pulsating pressure introducing chamber 5 to the upper side.
4, and a pump chamber 55 is formed on the lower side. The pulsating pressure introduction chamber 54 is connected to, for example, a crank chamber of a two-stroke engine, and reciprocates the membrane 53 up and down. The pump chamber 55 is connected to a fuel tank (not shown) via the passage 51, the check valve 10, and the connection pipe 45. The pump chamber 55 is provided with the check valve 4,
Through the passage 52 and the inflow valve 9, it is communicated with the constant pressure fuel chamber 38.

The film 34 and the cover 4
2 and a constant-pressure fuel chamber 38 is provided above the membrane 34.
The atmosphere chambers 36 having the atmosphere holes 58 are defined on the lower side of the chamber 4. A lever 41 is supported by a support shaft 40 inside the constant pressure fuel chamber 38. The left end of the lever 41 is abutted against the membrane 34 by a spring, while the right end supports the tapered inflow valve 9. When the fuel pump A is driven, the fuel in the fuel tank is supplied from the connection pipe 45 to the strainer 19, the check valve 10, and the passage 5.
1. Pump chamber 55, check valve 4, inflow valve 9 through passage 52
It is sent to the entrance side of.

According to the present invention, in order to be able to finely adjust the intake air amount (flow rate) in the high-speed operation range of the engine, a portion of the intake passage 12 upstream of the throttle valve 8 and the intake passage 12 At the downstream side of the throttle valve 8, intake air amount adjusting bolts 62, 7 projecting into the intake passage 12 and being externally adjustable.
2 are provided. That is, the intake air amount adjusting bolts 62 and 72 are respectively inserted into the screw holes 61 and 71 provided in the wall of the vaporizer main body 18.
Is screwed. At this time, the heads of the intake air amount adjusting bolts 62 and 72 are accommodated in the screw holes 61 and 71, and after adjusting the air intake amount at the factory, the lids 63 and 7 are respectively inserted into the screw holes 61 and 71.
3 to prevent the engine driver from making adjustments without permission. It is preferable that the outer diameter of the tip of each of the intake air amount adjusting bolts 62 and 72 is smaller than that of the threaded portion.

As shown in FIGS. 2 and 3, the intake air amount adjusting bolts 62 and 72 are provided on one side of the intake passage 12, that is, in the throttle, so as not to change the intake air amount (flow rate) in the low speed operation range of the engine. At the idle position of the valve 8, the intake passage 12 is disposed at a portion opposite to a portion communicating with the throttle hole 8 a, and the tips of the intake air amount adjusting bolts 62 and 72 project toward the center of the intake passage 12.

Next, the operation of the rotary throttle valve type carburetor according to the present invention will be described. As shown in FIG. 1, when the fuel efficiency (air-fuel ratio) when the throttle valve 8 is fully opened is low, the intake path 1
The intake air amount adjusting bolt 62 in the portion upstream of the throttle valve 8
And the passage area of the intake passage 12 on the upstream side of the throttle valve 8 is made slightly smaller than the passage area of the intake passage 12 on the downstream side of the throttle valve 8.
The intake negative pressure acting on the fuel injection hole 6 is slightly increased to increase the amount of fuel, and set so as to satisfy the required exhaust gas regulation value.

Conversely, fuel efficiency (air-fuel ratio) when the throttle valve 8 is fully opened
4, the intake air amount adjusting bolt 72 on the downstream side of the throttle valve 8 of the intake passage 12 is screwed in to reduce the passage area of the intake passage 12 on the downstream side of the throttle valve 8 as shown in FIG. By making the passage area slightly smaller than the passage area of the intake passage 12 on the upstream side of the throttle valve 8, the intake negative pressure acting on the fuel injection holes 6 of the fuel supply pipe 7 is slightly weakened, and the fuel amount is reduced.
Set to meet required exhaust gas regulation values.

In the embodiment shown in FIG. 5, the fuel consumption can be adjusted slightly richer or thinner by one intake air amount adjusting bolt 62 provided on the upstream side of the throttle valve 8 of the intake passage 12. Things. It is designed in advance so that the intake air amount reaches a set value with the intake air amount adjusting bolt 62 slightly protruding into the intake passage 12 on the test stand of the carburetor manufacturer. That is, the intake air amount adjusting bolt 62 slightly protrudes into the intake passage 12 from the beginning, and when the fuel consumption is low due to the matching with the engine, the fuel consumption is increased by screwing the intake air amount adjusting bolt 62 slightly. Conversely, when the fuel consumption is high, the fuel consumption is reduced by slightly retracting the intake air amount adjusting bolt 62. Of course, the amount of intake air adjusted by the intake air amount adjustment bolt 62 is very small, and therefore, the output of the engine does not decrease by adjusting the intake air amount adjustment bolt 62.

After fine adjustment by the intake air amount adjusting bolt 62,
By pressing the ball 64 into the screw hole 61 of the intake air amount adjusting bolt 62, the driver can freely adjust the intake air amount adjusting bolt 62.
Can no longer be moved, and the intake volume adjustment bolt 6
It is possible to prevent dust and the like from entering the intake path 12 from the screw portion 2.

FIG. 6 shows the adjustment characteristics of the intake air amount adjusting bolt 62 in the embodiment of the carburetor shown in FIG. Matching between the carburetor and the engine is performed with the state in which the intake amount adjusting bolt 62 is projected at the position of the scale 3 as a normal position. In the case of a mass-produced carburetor, when the setting of the fuel amount varies to a high level, the fuel consumption (air-fuel ratio) is adjusted to be thin by loosening the intake amount adjusting bolt 62 from the position of the scale 3 to the position of the scale 2. I do. On the other hand, when the setting of the fuel amount is scattered to a small amount, the intake amount adjusting bolt 62 is screwed from the position of the scale 3 to the position of the scale 4 to be adjusted to a darker position. After the adjustment of the intake air amount adjusting bolt 62, the ball 64 is driven into the screw hole 61 so that the driver cannot intentionally adjust the intake air amount adjusting bolt 62.

[0019]

As described above, according to the present invention, even if the intake air amount varies during high-speed operation of the engine, the matching between the carburetor and the engine can be adjusted, so that defects during mass production can be reduced. However, it is possible to prevent deterioration of the exhaust gas component due to the adjustment of the intake air amount adjusting bolt.

The configuration is simple, only providing an intake amount adjusting bolt in the intake path, and can be easily implemented without changing the configuration of the existing carburetor.

After adjusting the matching between the carburetor and the engine, the ball is press-fitted into the screw hole of the intake air amount adjusting bolt to prevent foreign matter from entering the intake passage of the carburetor together with the atmosphere.

Since the intake air amount adjustment bolt finely adjusts the intake negative pressure acting on the fuel supply pipe, the adjustment width of the intake air amount adjustment bolt may be set to be insensitive, and the adjustment operation can be facilitated.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a rotary throttle valve carburetor provided with an intake air amount adjusting mechanism when a throttle valve is fully opened according to the present invention.

FIG. 2 is a plan sectional view of the rotary throttle valve type carburetor.

FIG. 3 is a front sectional view showing a main part of the rotary throttle valve type carburetor.

FIG. 4 is a side sectional view illustrating an adjusting operation of the rotary throttle valve type carburetor.

FIG. 5 is a side sectional view of a rotary throttle valve type carburetor according to a modified embodiment of the present invention.

FIG. 6 is a diagram illustrating an adjustment operation of the rotary throttle valve type carburetor.

[Explanation of symbols]

A: Fuel pump B: Constant pressure fuel supply mechanism 2: Cylindrical part
3: Bar valve 4: Check valve 6: Fuel injection hole 7: Fuel supply pipe 8: Throttle valve 9: Inflow valve 10: Check valve 12: Intake path 15: Throttle valve lever 16: Follower 17: Lid 17a: Cam Surface 18: vaporizer main body 34: membrane 36: atmosphere chamber 38: constant pressure fuel chamber 40: support shaft 41: lever 42: cover 43: intermediate body 46: fuel jet 47: check valve 53: membrane 54: pulsating pressure introduction chamber 55: pump chamber 61: screw hole 62: adjusting bolt 63: lid 64: ball 71: screw hole 72: adjusting bolt 73: lid

Claims (4)

[Claims] 1. A rotary throttle valve carburetor which adjusts the amount of air by rotation of a throttle valve and adjusts the amount of fuel by axial movement of the throttle valve, a portion of the intake passage upstream of the throttle valve, and an intake passage. A rotary throttle valve type carburetor characterized in that an intake air amount adjusting bolt protruding into the intake passage and being adjustable from the outside is disposed at a portion downstream of the throttle valve. 2. A head of the intake air amount adjusting bolt is housed in a screw hole of a carburetor body, and after adjusting the intake air amount adjusting bolt, a lid is pressed into the screw hole. Item 2. A rotary throttle valve type carburetor according to Item 1. 3. The method according to claim 1, wherein a head of the intake air amount adjusting bolt is housed in a screw hole of the carburetor body, and after adjusting the intake air amount adjusting bolt, a ball is pressed into the screw hole. Item 2. A rotary throttle valve type carburetor according to Item 1. 4. An intake passage adjusting bolt for projecting into the intake passage and adjusting the intake amount to a predetermined value is provided at a portion of the intake passage upstream of the throttle valve, and the intake amount adjusting bolt is provided in accordance with the amount of protrusion of the intake amount adjusting bolt. The rotary throttle valve type carburetor according to claim 1, wherein the amount of fuel is adjusted.