JPS5985467A - Air-fuel ratio control device for carburetor - Google Patents

Abstract

PURPOSE:To prevent after burning by enriching an air-fuel mixture, which is necessary when using an engine brake, through the opening and closing of an air vent. CONSTITUTION:An air-fuel ratio control device 8, which enriches an air-fuel mixture by increasing the amount of fuel drawn out from a main jet 7k, when applying an engine brake, using the air vent 7l of the float chamber 7f of a carburetor 7, has a closing valve 11 to open and close the air vent 7l of a carburetor 7, and a control means 12 to open and close the closing valve 11. During deceleration, a valve body 19 is drawn upward together with a diaphragm 23 due to suction pressure, closing the closing valve 11, i.e., the air vent 7l. Thereby the layer of air a in the float chamber 7f becomes in a sealed condition, and the pressure applied to the surface of a fuel liquid in the float chamber 7f is increased, increasing the quantity of fuel drawn out in a connecting passage 7a.

Description

[Detailed Description of the Invention] This invention provides a method for reducing engine speed during engine deceleration (engine braking).
This relates to afterburn prevention.

Afterburn that occurs during engine deceleration (engine braking) can be prevented by reducing the air-fuel ratio of the air-fuel mixture supplied to the engine to a certain value or less (by enriching the air-fuel mixture).

Conventionally, two slow air passages were installed in the carburetor as an air-fuel ratio control device to enrich the mixture during deceleration.
Some air-fuel ratio control devices form two air passages in the carburetor and close one of the passages during engine braking, thereby enriching the air-fuel mixture. This had the disadvantage that jets had to be manufactured for each air passage, making the structure of the carburetor complicated.

This invention was proposed against the above background, and it is possible to enrich the air-fuel mixture during engine deceleration without using the slow air passage of the carburetor. The present invention aims to provide an air-fuel ratio control device for a carburetor that does not require the formation of a system and is suitable for simplifying the structure of the carburetor and reducing manufacturing costs.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 is a side view of a first embodiment of a motorcycle to which the present invention is applied, in which 1 is a body frame, 2 is a V-type engine, 3 is a radiator, and 4 is a fuel tank. A space 5 surrounded by the V-shaped buff 9 formed by the V-shaped cylinder l~ parts 2a and 2b and the bottom of the fuel tank 4 is filled with fresh air from above from the air cleaner 6 or the base 6a of the air cleaner 6. A carburetor turf etc. for supplying the engine are arranged, and an air-fuel ratio control device 8 is provided above the key knob 7 to enrich the air-fuel mixture supplied to the engine during engine braking.

The carburetor 7 and the air-fuel ratio control device 8 will be explained below with reference to FIG.

First, the carburetor 7 will be described. 7a is a communication passage that serves as an air flow path from the base portion 6a of the air cleaner 6 to the intake boat 2C of the ■-type engine 2, and 7b is the communication passage 7a.
Throttle valve that opens and closes 7C is diaphragm 7d
7e is a needle, 7f is a float chamber, 7g is a fuel inlet hole communicating with the fuel tank 4, 7h is a float rotatably supported around the shaft 71, and 7j is the float 7h. 7 is a flow rate adjustment valve whose lower end is connected to and opens and closes the fuel inlet hole 7o by the swinging of the float 7h, 7 is a main jet that sucks out fuel (gasoline) F stored in the float chamber 7f, and 7J is a float chamber. 7 [Air layer A above the liquid level outside the carburetor (
The outside side (the throttle valve 7b side) of the communication passage 7a is connected to the intake boat 2C of the cylinder portion 2a via the communication pipe 9, and the inside side of the communication passage 7a is connected to the air vent. Air cleaner 6 through 10
The air cleaner 6 is connected to the base portion 6a of the air cleaner 6 according to the opening degree of the screw 1hen 7ce and the throttle valve 7b.
Air is supplied from the main jet 7k to the engine 2, and fuel is supplied from the main jet 7k through a gap around the needle 7e.

Next, the air-fuel ratio controller 1 to the roll device 8 will be explained.

The air-fuel ratio control device 8 includes the key 17 breaker 7.
The air vent 7J of the float chamber 7r is used to increase the amount of fuel sucked out from the main jet 7k during engine braking, thereby enriching the air-fuel mixture. It includes an on-off valve 11 and a control means 12 for opening and closing the on-off valve 11.

The opening/closing valve 11 has recesses 13 and 14 at the upper and lower sides in FIG. 16, and a lower case 17 screwed to the lower part of the upper case 16 so as to cover the recess 14.
, a gasket 18 interposed between the two cases 16 and 17, and a valve body 19 held within the recess 14.

The recess 14 of the upper case 17 has a communication hole 14a opening to the left in FIG.
Further, the lower case 17 has a communication hole 17a in its lower part that allows the recess 14 to communicate with the outside. Further, the valve body 19 includes a packing part 19a that contacts the valve seat part 14b and closes the recess 14, and a shaft part 190 fixed to the packing part 19a via a nut 19b.
The shaft portion 19c has an upper end portion 19d protruding into the recess 13 and is movably supported by the partition wall 15. The communication hole 14a communicates with the air vent 7J of the key 17 breaker 7 via a hose 20, and the communication hole 17a communicates with the base portion 6a of the air cleaner 6 via a hose.

The control means 12 detects the engine braking state based on the pressure change in the communication passage 7a on the downstream side (intake port 2C side) from the thrower 1 to the valve 7e of the carburetor 7, and also detects the engine braking state based on the intake pressure in the communication passage 7a. It operates the opening/closing valve 11, and includes a cover 22 that has a recess 21 at the bottom and is attached to the upper part of the upper case 16 so as to cover the recess 13, and a cover 22 and the upper part that cover the recess 21. A diaphragm 23 that is held between the case 16 and supports the upper end 19d of the valve body 19, a spring 24 that urges the diaphragm 23 downward (towards the recess 13), and a cover 22 together with the diaphragm 23. and the upper case 16.
It is composed of five parts.

A detection hole 21a is formed in the upper part of the recess 21 and opens laterally in FIG.
6 to the communication passage 7a on the side of the intake port t-2c of the carburetor 7, so that the diaphragm 23 is sucked upward in FIG. 2 by the intake pressure during engine braking. The spring 24 sets the operating pressure at which the diaphragm 23 pulls up the valve body 10. In this embodiment, when the intake pressure in the communication passage 7a decreases to 450±40 ynmH (), the diaphragm 23 is pulled up. The elastic force is set so that the on-off valve 11 is closed, that is, the air vent 7.1 is closed.This operating pressure setting is based on the intake pressure during engine braking (deceleration) and when the engine is empty. This was done by taking into account the intake pressure when driving, that is, when there is no load, and the intake pressure (P
B-I), intake pressure at engine no load (PB-o)
, and the range (parea) of the set operating pressure is shown in FIG. Note that 1jI is present in the detection hole 21a.
, an orifice 21b is formed to improve the responsiveness and operability of the diaphragm 23 due to fluctuations in intake pressure.

In addition, to provide a supplementary explanation of the cylinder portion 2a shown from I-J in FIG. 2, 2d is the cylinder head, 2e is the cylinder,
2r is a head cover, 2o is an exhaust boat, 2h is an intake valve, 21 is an exhaust valve, 2j is a piston, and 2 is a connecting rod.

The operation of the air-fuel ratio control device 8 will be explained below.

During constant running, where the slot valve 7b of the carburetor 7 maintains a constant opening, or during acceleration (acceleration), where the slot valve 7b of the carburetor 7 maintains a constant opening, the intake pressure in the communication passage 7a of the Kitoburetuff is high, and the intake pressure increases. Since the urging force of the spring 24 is stronger than the suction force acting on the diaphragm 23, the diaphragm 23 is kept in a downwardly bent state, and therefore the on-off valve 11 is kept in an open state.

In other words, the air vent 7J is in communication with the air cleaner 6 via the on-off valve 11, and the float chamber 7
Since the pressure in the inner air layer A is maintained at approximately atmospheric pressure, the amount of fuel corresponding to the opening degree of the throttle valve 7b is sucked out from the main jet 7k, and the air-fuel mixture is mixed to a predetermined air-fuel ratio. is formed.

During the aforementioned constant running or during deceleration (engine braking) in which the opening degree of the throttle valve 7b is reduced from the acceleration, the intake pressure on the downstream side of the throttle valve 7b of the carburetor 7 decreases, and the intake pressure decreases. 450±40
ynyn) -1a, the suction force acting on the diaphragm 3 due to the intake pressure is reduced to the spring 24.
The biasing force is larger than that of the diaphragm 23, and the valve body 19 is pulled upward together with the diaphragm 23, and the opening/closing valve 11, that is, the air vent 1-74 is opened. At that time, since the liquid level cannot move upward, the float 7h is also held at that position, and the flow control valve 7j is held open. In this way, the air vents 7,,f are closed and the float chamber 7f is closed.
When the air layer A inside the float chamber 7f is in a sealed state, the air mA is compressed by the fuel flowing into the float chamber 7f and covers the float chamber 7f, and the pressure of the air mA is 1 no more than when the air vent j-74 is open. becomes higher. Zunarichi, just by this pressure increase, FuD
-1. The pressure applied to the fuel liquid level in the chamber 7f increases, and as a result, the amount of fuel sucked out from the main jet 7k into the communication passage 7a becomes larger than the amount corresponding to the throttle valve 7b. In response to such an increase in the amount of fuel supplied, the amount of air flowing through the communication passage 7a depends on the opening degree of the throttle valve 7b, so a relatively lipped air-fuel mixture is formed. This prevents afterburn during deceleration.

In addition, when air vents 7 and f are closed, the float to 7r
The pressure pushing the fuel level in the float chamber 7t is inversely proportional to the change in the volume of the air layer A, which is reduced by the fuel r1 flowing into the float chamber 7t.For example, if the volume of the air layer A changes to 1/2, If it pushes on the liquid level, the pressure will double. Therefore, by setting the stage of the carburetor 7 in advance so that the volume of the air layer A becomes smaller and increasing the rate of volume reduction by the fuel flowing into the float chamber 7f when the air vent 7 is closed, the fuel liquid level can be lowered. Apply pressure to fuel tank 4
Depending on the height difference between the carburetor 7 and the carburetor 7, the pressure can be increased to the level that acts on the fuel inlet hole 7g.

4 and 5 show a second embodiment of a motorcycle to which the present invention is applied, and parts that function in the same way as in the first embodiment are given the same numbers to simplify the explanation. do.

In this motorcycle, the angle between the cylinders is a narrow V.
It is equipped with a V-type engine 27, and the V-type engine 27
Behind the air-fuel ratio control device 8 and an opening/closing valve 11 of the air-fuel ratio control device 8, which is called a gearnister.
A suction device 28 is provided for adsorbing the vaporized fuel released from the communication hole 17a.

As shown in FIG. 5, the adsorption device 28 is arranged in a case 29 having a discharge port 29a at the bottom, and has spaces 29b at the top and bottom.
, 29c is filled with adsorbent 30,
Tube 31 connected to communication hole 17a of on-off valve 11
is inserted into the adsorbent 30 from the upper side of the case 29, and the tube 32 connected to the discharge port 29a at the bottom of the case is guided to the lower part of the vehicle body, thereby adsorbing the fuel components in the gas released from the on-off valve 11. The material absorbs and purifies the air, which is then released to the underside of the vehicle. In this embodiment, a return pipe 34 that communicates with the overflow duplex 33 of the fuel tank 4 and the adsorption port 2C of the engine is connected to the L side of the case 29. The fuel remaining in the engine is moved to the intake bowl by the engine's intake pressure.
It has been devised to return to

FIG. 6 shows a third embodiment of the present invention.

In this embodiment, when the float chamber 7 of the carburetor 7 is provided with an overflow pipe 7Ill for preventing too much fuel from entering, the fuel flowing out from the overflow pipe 7m is adsorbed via the air-fuel ratio control device d8. The overflow pipe 7m is led downward through a tube 35, and is further connected to the T-type joint through a pipe 36 to the air vent l-7.
, , f and the communication hole 14a of the on-off valve 11 are connected to a hose 20.

In addition, in the above embodiment, as a carburetor,
Flow 1 - Although the fuel supply into the room is performed by the difference in height between the fuel tank and the carburetor, fuel may be supplied to these carburetors by a twerp pump.

As explained above, the air-fuel ratio control device of the present invention includes an on-off valve for opening and closing the air vent 1- in the float chamber of the carburetor, and a valve control means for closing the on-off valve during engine braking, and Since the mixture is enriched during braking by opening and closing the air vent, the conventional method opens and closes the slow system air passage to adjust the amount of air mixed with the fuel, thereby enriching the mixture. Compared to the previous model, there is no need to create two slow air passages in the carburetor or to create jets for the air passages, simplifying the structure of the carburetor and significantly reducing manufacturing costs. It's now possible.

[Brief explanation of the drawing]

FIG. 1 is a side view of a first embodiment of a motorcycle to which the present invention is applied, FIG. 2 is an enlarged sectional view of the main part of FIG. 1, and FIG.
4 is a side view showing a second embodiment of a motorcycle to which the present invention is applied; FIG. 5 is an explanatory diagram of the operating pressure of the device of the present invention; FIG.
The figure is an enlarged sectional view of the main part of Fig. 4, and Fig. 6 is the third embodiment of the present invention.
It is an explanatory view showing an example. 2C...Intake port, 6...Air cleaner, 6a...Base part, 7...Carburetor, 7a...Communication path, 7b...・・・・・・
Throttle valve, 7t...Float chamber, 7g
...Fuel inlet hole, 7h...Float,
7j...Flow 11 section valve, 7k...Main jet 1., 7J...Air vent, A...
... Air layer, 8 ... Air-fuel ratio control device, 11 ... Opening/closing valve, 12 ... Control means, 16 ... Upper case, 17・・・・・・
・Lower case, 18...Paragin, 19...
... Valve body, 21 ... Recess, 21a ...
・Detection hole, 22...Cover, 23...
Diaphragm, 24...Spring, 25...
... Pa-nking. Applicant: Honda Motor Co., Ltd. Figure 5: Mr. Commissioner of the Patent Office 1. Indication of the case Patent Application No. 195550 of 1982 2 Title of the invention Carburetor Air-Fuel Ratio Control Device 3 Amendment Person Patent Applicant (33, 2) Honda Motor Co., Ltd. 4 Agent (2) Drawings. (1) Correct [Pulp 7eJ in the negative 11th line of the specification to [Pulp 7bJ]. (2) Specification @ page 77 No. 1I! Eye 1 - Inspiratory pressure -1
is corrected as "g & air negative pressure is greater than atmospheric pressure". (8) Specification page 9, No. 1I! The first inspiratory pressure in the line is ""
The intake negative pressure is corrected to be "more than atmospheric pressure." (4) Details * “Diaphragm 8” on page q, line tM15
is corrected as [diaphragm 28-1]. (5) Inspiratory pressure (PBJ mmHg)j in Fig. 3 is changed to [inspiratory negative pressure (Pn>rczHa
) Correct as J. that's all

Claims (1)

[Claims] An air-fuel ratio control device for a carburetor, comprising an opening/closing valve that opens and closes the only air vent that communicates air between the upper part of the oil level in a float chamber of the carburetor and the outside, and a valve control means that closes the opening/closing valve during engine braking.