JPS58155270A - Device for increasing amount of fuel upon engine acceleration - Google Patents

Abstract

PURPOSE:To prevent the air/fuel ratio of a mixture from being excessively lean and fluctuating in an engine having a carburettor provided with a throttle valve of butterfly type disposed in an intake-air passage, by providing a resistance valve in the intake/ air passage and as well by laying an atmospheric air communicating passage in the intake air passage between the resistance valve and a fuel jet port. CONSTITUTION:An intake air passage 4 is communicated with a combustion chamber 3 in each cylinder C1, C2 of an engine, and a small venturi 8 provided with a throttle valve 6 and a fuel nozzle 7 is formed in a carburettor 5 which forms a part of the intake air passage 4. Further, there is provided an intake air expansion chamber 10 including a box member 10a and a lid member 10b above the carburettor 5. Further, a resistance valve 16 is disposed in an opening in the upper surface of the above-mentioned box member 10b, and is composed of a support cylinder 17 and a valve member 19 which covers an opening surface 18. A bypass passage is formed by the opening surface 18, a gap 23 and a circular hole formed in the valve member 19. With this arrangement, an increase in the flow of intake air is temporarily hindered by the resistance valve 16 when the throttle valve 6 is abruptly opened upon enging abrupt acceleration, thereby the air/fuel ratio of a mixture is prevented from being excessively lean.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an engine having a carburetor with a linear throttle valve in the intake passage.

Conventionally, in this type of engine, a resistance valve was installed upstream of the fuel nozzle to prevent the air-fuel ratio of the mixture from becoming too hot during sudden acceleration operations, and a technology was used to momentarily delay the inflow of intake air when the throttle valve suddenly opened. is known (for example, Jikko 4)
4-21126).

In general, the resistance valve needs to open easily with a small amount of opening force in order to allow a large amount of air to flow without resistance at maximum output. opening is required.

However, if the operation of the resistance valve is made light, the opening changes due to the pulsation of the intake negative pressure during low-output operation, and the intake negative pressure acting on the fuel nozzle becomes unstable, causing the air-fuel ratio of the mixture to fluctuate. There is a problem.

The purpose of this invention is to eliminate such problems, and the purpose of this invention is to close the resistance valve when the intake air amount of the engine is below a predetermined value, and to supply air to the air intake passage between the resistance valve and the fuel nozzle. It is characterized by having a side road leading to it.

This will be explained below with reference to illustrated embodiments. In the figure, reference numeral 1 denotes a motorcycle, which is equipped with a V-shaped two-cylinder engine 2 having two cylinders Cs and Cx of a V-shaped device inclined in the front and rear. In FIG. 2, each cylinder CI,
The combustion chamber 3 of C2 has an intake passage 4 extending substantially vertically upward. A carburetor 5 forms a part of the intake passage 4 and has a small bench lily 8 provided with a linear throttle valve 6 and a fuel nozzle T. 9 is an operation link connected to the throttle valve 6; 10 is an intake expansion chamber consisting of a synthetic resin box 10a and a removable lid 10b; The inside thereof has an intake distribution chamber 12 partitioned by a cylindrical partition wall 10c protruding from the bottom. This partition wall 10c
A relatively large-diameter hole 13 is opened at the upper end, and an offshore filter 14 is attached to the hole 13. 14a is a frame board made of P paper, and 1x is a frame board made of a tin plate. Reference numeral 15 denotes an air funnel that is fitted into the hole in the bridge body 10 and the bottom and opens into the distribution chamber 12. The intake expansion chamber 10 thus constitutes an air cleaner chamber. Reference numeral 16 denotes a resistance valve, which is screwed into an opening provided on the top surface of the lid 10b.

As shown in FIGS. 3 and 4, the resistance valve 16 mainly consists of a substantially rectangular support tube 17 and a valve body 19 that covers an inclined opening surface 18 on the upper surface of the support tube 17, both of which are connected by a hinge 21. The valve body 19 is made of synthetic resin and is made to be slightly larger than the opening surface and relatively lightweight, forming a normally closed valve that is always biased in the closing direction by gravity. Valve body 19
The minimum opening degree of the valve is regulated by a rubber damper 22 fitted to the end thereof, and consists of an elongated triangular space 23 between the opening surface 1B and the valve body 19, and a circular hole 24 provided in the valve body 19. A side road has been formed. The minimum opening degree is the throttle valve 6.
When the resistance valve 16 is at the idling opening, the opening is set as small as possible within a range that does not cause an unnecessary rise in negative pressure (pressure drop) on the downstream side of the resistance valve 16.

Next, these operations will be described. When the engine is operated in an idling state, an intake air flow occurs in the direction of the arrow in the figure.

At this time, the intake air flow rate is low and the resistance valve 16 is kept at the minimum opening degree. When the throttle valve 6 is suddenly opened, the high intake negative pressure within the combustion rate 3 spreads to the upstream side of the throttle valve 6, fuel is ejected from the fuel nozzle I, and at the same time, intake air flows in from the atmosphere. At this time, the resistance valve 16 is at the minimum opening degree, so it temporarily prevents a sudden increase in intake air, and then receives the action of the suction sound on the upper surface and the atmospheric pressure on the lower surface, and rotates upward against gravity. Increase the opening. Therefore, the timing of increasing the amount of fuel, which has a relatively large inertia and tends to increase slowly, coincides with the timing of increasing the amount of air, which increases quickly, and the air-fuel ratio of the air-fuel mixture generated by the carburetor 5 is set in advance. 1'- kept in proportion! The air-fuel mixture flow rate can rapidly increase, and there will be no obstruction to the intake air flow. Immediately after the resistance valve 16, the airflow direction changes depending on the opening degree of the resistance valve 16, but the intake airflow expands sufficiently in the relatively large capacity intake air distribution chamber 12 and the airflow direction becomes stable. Local pressure fluctuations due to changes in the fuel nozzle 7 do not occur. Note that the resistance valve 16 is connected to the lid body 10b.
It is removable and easy to assemble, maintain and inspect.

As described above, the present invention provides an engine in which a carburetor consisting of a linear throttle valve and a fuel injection port, which are manually opened and closed, is provided in an intake passage that communicates a combustion chamber with the atmosphere. Since the resistance valve is installed near the opening end, when the engine suddenly accelerates, that is, when the throttle valve is suddenly opened, the increase in intake airflow is temporarily blocked, and the air-fuel mixture that tends to occur when the throttle valve is suddenly opened is blocked. can prevent overheating of the air-fuel ratio. In addition, since a side passage leading to the atmosphere was provided in the intake passage between the resistance valve and the fuel nozzle, when the engine is operated in the idle link and the low load region around it, the intake air flow is directed to this side passage. Since it is inhaled through the air, there is less intake resistance, which has the effect of preventing engine stability from being harmed. In addition, since the resistance valve faces the edge of the inclined opening surface of the support cylinder surface - E surface, it does not interfere with the cylinder body at the initial stage of opening the valve, which has the effect of stabilizing the pressure difference between the front and back sides required for opening the valve. be.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of a motorcycle to which the present invention is applied, and FIG. 2 is an enlarged partially cutaway view of the main parts of the engine. FIG. 3 is a plan view of the resistance valve which is the main part of the present invention, and FIG. 4 is a side view. 21.Fist engine, 3..M-burning w, 4..Intake passage, 5..Enjoyment, carburetor, 6..No.-throttle valve, '41i
,...Fuel nozzle, 12...Intake distribution chamber, 1
4...Filter, 16...Resistance valve. Patent applicant: Yamaha Motor Co., Ltd. agent Masaki Yamakawa (and one other person) 7-

Claims (1)

[Claims] In an engine equipped with a carburetor consisting of a linear throttle valve and a fuel nozzle that are artificially opened and closed in an intake passage that communicates the combustion chamber with the atmosphere, a resistance valve is installed near the opening end of the intake passage on the atmosphere side. A device for increasing fuel during acceleration of an engine, further comprising: a bypass passage leading to the atmosphere in an intake passage between the resistance valve and the fuel nozzle.