# US 5,347,960 A · Double-acting piston engine

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- Number: US 5,347,960 A
- Document ID: US5347960A
- Status: Granted
- Kind: A
- Application number: 08/100,089
- Filed: 1993-07-30
- Granted: 1994-09-20
- Earliest claimed: 1993-07-30
- Inventors: Jyoji Tokumi
- Web page: https://patentgrep.com/patent/US5347960A

## CPC

- F02B 75/246: {with only one crankshaft of the "pancake" type, e.g. pairs of connecting rods attached to common crankshaft bearing}
- F01B 9/026: {Rigid connections between piston and rod; Oscillating pistons}
- F02B 75/002: {Double acting engines}
- F02B 1/04: with fuel-air mixture admission into cylinder
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)
- F01B: MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES (of rotary-piston or oscillating-piston type F01C; of non-positive-displacement type F01D; internal-combustion engines F02B; combustion-product engine plants F02G; machines or engines, other than of positive-displacement type, for liquids F03B; positive-displacement engines driven by liquids F03C; wind motors F03D; positive-displacement machines for liquids F04B; rotary-piston, or oscillating-piston, positive-displacement machines for liquids F04C)

## Abstract

A double-acting piston engine has a crankshaft rotatable about a first central axis and having a crankpin having a second central axis which is spaced a distance from the first central axis, a cylinder assembly having a pair of cylinder chambers confronting each other along an axial line perpendicular to the first central axis, with the crankpin being disposed substantially between the cylinder chambers, and a piston assembly slidably disposed in the cylinder chambers and coupled to the crankpin. The piston assembly comprises a pair of pistons slidably fitted in the cylinder chambers, respectively, a joint disposed in the cylinder chambers and having opposite ends coupled to the pistons, respectively, the joint having a cylindrical opening defined therein, and a rotor rotatably fitted in the cylindrical opening for rotation about a third central axis, the rotor having an eccentric hole defined therein and spaced from the third central axis by a distance which is the same as the distance by which the second central axis is spaced from the first central axis, the crankpin being fitted in the eccentric hole thereby connecting the piston assembly to the crankpin.

## Claims

### Claim 1

A double-acting piston engine comprising:
a crankshaft rotatable about a first central axis and having a crankpin having a second central axis which is spaced a distance from said first central axis;
a cylinder assembly having a pair of cylinder chambers confronting each other along an axial line perpendicular to said first central axis, with said crankpin being disposed substantially between said cylinder chambers; and
a piston assembly slidably disposed in said cylinder chambers and coupled to said crankpin;
said piston assembly comprising:
a pair of pistons slidably fitted in said cylinder chambers, respectively;
a joint disposed in said cylinder chambers and having opposite ends coupled to said pistons, respectively, said joint having a cylindrical opening defined therein; and
a rotor rotatably fitted in said cylindrical opening for rotation about a third central axis, said rotor having an eccentric hole defined therein and spaced from said third central axis by a distance which is the same as said distance by which said second central axis is spaced from said first central axis, said crankpin being fitted in said eccentric hole thereby connecting said piston assembly to said crankpin.

### Claim 2 (depends on 1)

A double-acting piston engine according to claim 1, wherein said joint has a pair of partial internal gears which are positioned diametrically opposite to each other across said third central axis, said crankpin having on one side thereof a partial external gear positioned for mesh with said partial internal gears, the arrangement being such that when said crankshaft rotates about said first central axis to position said second central axis near a plane which is perpendicular to said axial line and passes through said first central axis, said partial external gear meshes with one of said partial internal gears.

### Claim 3 (depends on 1)

A double-acting piston engine according to claim 1, wherein said joint has a guide positioned between said pistons and held in sliding contact with an inner circumferential surface of said cylinder chambers, said inner circumferential surface having a lubricating oil groove extending axially with respect to said cylinder chambers, said joint having a first lubricating hole communicating between a surface of said guide which faces said lubricating oil groove and an inner circumferential surface of said cylindrical opening, the arrangement being such that lubricating oil supplied from outside of said cylinder assembly to said lubricating oil groove is supplied through said lubricating hole to an outer circumferential surface of said rotor which is held in sliding contact with said inner circumferential surface of said cylindrical opening.

### Claim 4 (depends on 3)

A double-acting piston engine according to claim 3, wherein said rotor has a second lubricating hole communicating between said outer circumferential surface of said rotor and an inner circumferential surface of said eccentric hole, the arrangement being such that the lubricating oil supplied to the outer circumferential surface of said rotor is supplied through said second lubricating hole to an outer circumferential surface of said crankpin which is held in sliding contact with the inner circumferential surface of said eccentric hole.