TWO-STROKE CYCLE COMBUSTION ENGINE OF AIR SCAVENGING TYPE

• US 20100192928A1
• Filed: 01/14/2010
• Published: 08/05/2010
• Est. Priority Date: 01/30/2009
• Status: Active Grant

• Current Assignee: Kawasaki Motors
• Original Assignee: Kawasaki Jukogyo Kabushiki Kaisha
• Inventors: Yuasa, Tsuneyoshi
• Granted Patent: US 8,122,861 B2
• Time in Patent Office: Days
• US Class Current: 123/65.00V
• CPC Class Codes: F02B 25/14 using reverse-flow scavenging, e.g. with both outlet and inlet ports arranged near bottom of piston stroke
• CPC Class Codes: F02B 25/22 by forming air cushion between charge and combustion residues
• CPC Class Codes: F02B 33/04 with simple crankcase pumps, i.e. with the rear face of a non-stepped working piston acting as sole pumping member in co-operation with the crankcase
• CPC Class Codes: F02M 35/1019 Two-stroke engines; Reverse-flow scavenged or cross scavenged engines

Abstract

To provide a two-stroke cycle combustion engine of an air scavenging type, in which not only can transit from the idling condition to the rapid accelerating condition take place smoothly, but the combustion engine can be smoothly started, there are provided scavenging passages (30, 31) for introducing an air/fuel mixture (M) and an air (A) into a combustion chamber (1a), a valve unit (51, 50) for adjusting the opening of each of an air passage (23) for supplying the air (A) to the scavenging passage (30) and an air/fuel mixture passage (24) for supplying the air/fuel mixture (M) to the scavenging passage (31), and an auxiliary air introducing passage (70) for introducing an auxiliary air to the air/fuel mixture passage (24) at a location downstream of the valve unit (51, 50) in the air/fuel mixture passage (24).

Claims

1. A two-stroke cycle combustion engine of an air scavenging type in which an air/fuel mixture and an air are introduced into a combustion chamber through a scavenging passage, which engine comprises:

a valve unit for adjusting the opening of each of an air passage for supplying the air to the scavenging passage and a air/fuel mixture passage for supplying the air/fuel mixture to the scavenging passage; and

an auxiliary air introducing passage for introducing an auxiliary air to the air/fuel mixture passage at a location downstream of the valve unit.

2. The two-stroke cycle combustion engine of the air scavenging type as claimed in claim 1, in which the air is so set as to be introduced into the combustion chamber prior to the air/fuel mixture.

3. The two-stroke cycle combustion engine of the air scavenging type as claimed in claim 1, in which the auxiliary air introducing passage has a downstream portion defined in a spacer which is disposed between a carburetor, having the valve unit, and an engine body.

4. The two-stroke cycle combustion engine of the air scavenging type as claimed in claim 3, in which the auxiliary air introducing passage has a throughhole defined in the carburetor for introducing a clean air, which has passed through an air cleaner, into the air/fuel mixture passage.

5. The two-stroke cycle combustion engine of the air scavenging type as claimed in claim 1, in which the auxiliary air introducing passage includes a tube for introducing a clean air, which has passed through an air cleaner, into the air/fuel mixture passage.

6. The two-stroke cycle combustion engine of the air scavenging type as claimed in claim 1, further comprising an auxiliary air cleaner for substantially purifying an external air and in which the auxiliary air introducing passage fluidly connects the auxiliary air cleaner and the air/fuel mixture passage together.

7. The two-stroke cycle combustion engine of the air scavenging type as claimed in claim 1, in which the valve unit comprises a single rotary valve unit for adjusting the opening of both of the air passage and the air/fuel mixture passage and further comprising a needle valve movable across the valve unit in a direction axially of the valve unit for adjusting the opening of a main nozzle for fuel and a lift up lever movable in a direction required to open the needle valve to thereby increase the concentration of fuel at the time of start of the combustion engine.

8. The two-stroke cycle combustion engine of the air scavenging type as claimed in claim 1, further comprising a choke valve disposed at a location upstream of the valve unit for throttling down the opening of the air passage and the air/fuel mixture passage at the time of start of the combustion engine and a passage shutter provided in the choke valve for closing the auxiliary air introducing passage at the time of start of the combustion engine.