# US 2019/0170054 A1 · Two-stroke internal combustion engine

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- Number: US 2019/0170054 A1
- Document ID: US20190170054A1
- Status: Published application
- Kind: A1
- Application number: 16/324,345
- Filed: 2017-07-25
- Published: 2019-06-06
- Earliest claimed: 2016-09-08
- Assignees: Emak S.P.A.
- Applicants: Emak S.P.A.
- Inventors: Marco FERRARI; Vincenzo GAGLIARDI
- Web page: https://patentgrep.com/patent/US20190170054A1

## CPC

- F02B 25/14: using reverse-flow scavenging, e.g. with both outlet and inlet ports arranged near bottom of piston stroke
- 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
- F02B 33/28: Component parts, details or accessories of crankcase pumps, not provided for in, or of interest apart from, subgroups F02B33/02 - F02B33/26
- F02B 63/02: for hand-held tools
- F02F 1/002: {Integrally formed cylinders and cylinder heads}
- F02F 1/22: characterised by having ports in cylinder wall for scavenging or charging
- F02B 2075/025: {two}
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- F02F: CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES

## Abstract

Herein described is a two-stroke internal combustion engine (100), comprising: a cylinder (135) having a pre-set central axis (B); a piston (145) slidably coupled to the cylinder (135) and suitable to divide the interior volume thereof into two distinct chambers, including a combustion chamber (150) and a pumping chamber (155); an intake duct (160) communicating with the pumping chamber (155); an exhaust duct (170) communicating with the combustion chamber (150); and at least one scavenging duct (180) suitable to place the pumping chamber (155) in communication with the combustion chamber (150); wherein said scavenging duct (180) comprises a terminal portion (190) leading to the combustion chamber (150) which extends with configuration diverging from an inlet section (200) up to an outlet section (205) obtained on a lateral surface of the cylinder (135).

## Claims

### Claim 1

A two-stroke internal combustion engine (100), comprising:
a cylinder (135) having a pre-set central axis (B),
a piston (145) slidably coupled to the cylinder (135) and adapted to divide the interior volume of the cylinder (135) into two distinct chambers; a combustion chamber (150) and a pumping chamber (155),
an intake duct (160) communicating with the pumping chamber (155),
an exhaust duct (170) communicating with the combustion chamber (150), and
at least one scavenging duct (180) adapted to place the pumping chamber (155) in communication with the combustion chamber (150),
wherein said scavenging duct (180) comprises a terminal portion (190) leading to the combustion chamber (150) which extends with configuration diverging from an inlet section (200) up to an outlet section (205) obtained on a lateral surface of the cylinder (135), and
wherein the projection of the terminal portion (190) of the scavenging duct (180) on a median plane (M) containing the axis (B) of the cylinder (135) is fully contained in the projection of the outlet section (205) on the same median plane (M), said median plane (M) being a symmetry plane of the exhaust duct (170),
wherein the cross-section of the terminal portion (190) of the scavenging duct (180), carried out according to a section plane orthogonal to the central axis (B) of the cylinder (135), is substantially trapezoidal-shaped wherein said cross-section has a side substantially orthogonal to the median plane (M).

### Claim 2 (depends on 1)

The engine (100) according to claim 1, wherein the inlet section (200) of the terminal portion (190) defines a choke in the scavenging duct (180).

### Claim 3 (depends on 2)

The engine (100) according to claim 2, wherein the inlet section (200) of the terminal portion (190) is the narrowest passage section of the entire scavenging duct (180).

### Claim 4 (depends on 1)

The engine (100) according to claim 1, wherein said median plane (M) is a symmetry plane of the intake duct (160).

### Claim 5 (depends on 1)

The engine (100) according to claim 1, wherein the outlet section (205) of the terminal portion (190) of the scavenging duct (180) is substantially rectangular-shaped.

### Claim 6 (depends on 1)

The engine (100) according to claim 1, further comprising at least one pair of said scavenging ducts (180), which are shaped and arranged in a mutually symmetrical manner with respect to said median plane (M).