Carburetor for internal combustion engine

Patent metadata

Field	Value
Publication number	US-10113509-B2
Application number	US-201615197911-A
Country	US
Kind code	B2
Filing date	Jun 30, 2016
Priority date	Jul 1, 2015
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

In an automotive carburetor, the time delay in the response of the engine to the change in the cross sectional area of the air passage is minimized, and a high level of freedom in selecting the communication cross section area of the air passage and the air fuel ratio for the given load of the engine. The carburetor ( 1 ) comprises a fuel passage ( 13 ) including a fuel nozzle ( 16 ) for supplying fuel to the intake passage, a first air passage ( 14 ) communicating with the fuel passage to supply air to the fuel passage, a variable communication unit ( 21, 41 ) provided in a part of the first air passage and moveable between an open position for communicating the first air passage and a closed position for shutting off the first air passage and a switch mechanism ( 22, 43 ) for moving the variable communication unit between the open position and the closed position in dependence on a load of the engine.

First claim

The invention claimed is:

1. A carburetor for an internal combustion engine, comprising,
a throttle body internally defining an intake passage;
a throttle valve provided in the intake passage for controlling a flow rate of air conducted by the intake passage, the throttle valve including a throttle shaft rotatably supported by the throttle body;
a fuel passage including a fuel nozzle for supplying fuel to the intake passage;
a first air passage communicating with the fuel passage to supply air to the fuel passage;
a variable communication unit provided in a part of the first air passage and moveable between an open position for communicating the first air passage and a closed position for shutting off the first air passage, the variable communication unit including an air passage shaft received in a retaining hole provided in an intermediate part of the first air passage in a rotatable manner around an axial line extending in parallel with the throttle shaft, the air passage shaft having a communication passage defined therein and being rotatable between the open position where the communication passage forms a part of the first air passage and the closed position where the communication passage forms no part of the first air passage; and
a switch mechanism for rotating the air passage shaft between the open position and the closed position in dependence on a load of the engine,
wherein the switch mechanism comprises a link mechanism coupled between the throttle shaft and the air passage shaft to rotate the air passage shaft such that the first air passage is communicated when an opening angle of the throttle valve is a first angle, and is shut off when the opening angle of the throttle valve is a second angle greater than the first angle,
wherein the first air passage includes an upstream portion extending in parallel with the intake passage to the retaining hole of the air passage shaft, and a downstream portion extending from a bottom end of the retaining hole along an axis of the retaining hole and then is bent to extend to the fuel passage, and
wherein the communication passage is bent in the air passage shaft and has an upstream end opening out in an outer circumference of the air passage shaft and a downstream end opening out in an inner end face of the air passage shaft.

2. The carburetor according to claim 1 , further comprising a first tubular member fitted in a part of the downstream portion of the first air passage extending along the axis of the retaining hole such that the first tubular member defines a first air jet constituting a narrowest section of the first air passage.

3. The carburetor according to claim 2 , further comprising a second air passage communicating with a part of the first air passage downstream of the first air jet to supply air to the fuel passage via the first air passage.

4. The carburetor according to claim 3 , wherein the second air passage extends in parallel with the intake passage and is bent to be connected to the part of the first air passage downstream of the first air jet, and
a part of the second air passage extending in parallel with the intake passage is provided with a stepped configuration including an upstream section having a first diameter and a downstream section having a second diameter smaller than the first diameter such that a shoulder surface is defined at a boundary between the upstream section and the downstream section, a second tubular member being fitted into the upstream section of the second air passage and positioned by abutting against the shoulder surface to define a second air jet constituting a narrowest section of the second air passage.

5. The carburetor according to claim 1 , wherein the link mechanism includes an eccentric pin provided on one of the throttle shaft and the air passage shaft, and an arm provided on the other of the throttle shaft and the air passage shaft and having a slot receiving the eccentric pin.

6. The carburetor according to claim 1 , wherein the link mechanism includes a rod connected eccentrically and pivotally to one of the throttle shaft and the air passage shaft at one end thereof, and an arm plate provided on the other of the throttle shaft and the air passage shaft and having a slot receiving an eccentric pin provided on another end of the rod.

7. The carburetor according to claim 1 , wherein the link mechanism includes an eccentric pin provided on an outer end of the throttle shaft to be in parallel with the throttle shaft, and an arm provided on an outer end of the air passage shaft to extend radially with respect to the air passage shaft, the arm having a slot receiving the eccentric pin, such that when the throttle shaft rotates, the eccentric pin undergoes a swinging movement, and the swinging movement of the eccentric pin causes the air passage shaft to rotate via the arm in such a manner that when the throttle valve is fully closed, the first air passage is communicated by the air passage shaft.

8. The carburetor according to claim 7 , wherein when the throttle valve is fully opened, the first air passage is shut off by the air passage shaft.

Assignees

• Honda Motor Co Ltd

Inventors

• Sakurai Koichi
• Ando Masaki
• Utsugi Eiichi
• Abe Hitoshi
• Suzuki Takashi
• Tajima Katsuya
• Fukuhara Masayuki

Classifications

• F02M7/26 Primary

  dependent on position of optionally operable throttle means · CPC title