US 7,624,574 B2 · Piston apparatus, stirling engine, external combustion engine, and fluid device

Abstract

A piston apparatus which configures an air bearing by introducing a compressed working media into an inside of a piston, and ejecting the working media from plural holes arranged on a circumferential portion of the piston into a clearance between the piston and the cylinder, which prevents a back-flow of the working media in the piston to a working space, and which readily secures reliability and longevity is provided. The piston apparatus is applied to an external combustion engine 10, and includes a piston main body 211, a pressure-accumulating chamber 212 that is formed inside the piston main body, an introduction portion 214 that serves to introduce the compressed working media into the pressure-accumulating chamber, holes 216 that are arranged on a circumferential portion 211b of the piston main body and runs from the pressure-accumulating chamber to the clearance between the piston main body and the cylinder 22 of the external combustion engine, wherein the introduction portion is arranged to be communicable in an introduction direction to the pressure-accumulating chamber of the working fluid and an opposite direction of the introduction direction, and a channel resistance in the opposite direction in the introduction portion is larger than in the introduction direction.

Claims15

Dependent claims

An external combustion engine comprising:

a piston apparatus;
and
a cylinder, wherein
the piston apparatus includes
a piston main body,
a pressure-accumulating chamber formed inside the piston main body,
an introduction portion that is arranged in a first portion corresponding to a predetermined height position in a circumferential portion of the piston main body, and that serves to introduce a working medium compressed in a working space of the external combustion engine into the pressure-accumulating chamber, and
a hole that is arranged in a second portion corresponding to a position lower than the predetermined height position in the circumferential portion of the piston main body, and that runs from the pressure-accumulating chamber to a clearance between the piston main body and the cylinder, and
a size of the clearance between the first portion in the circumferential portion of the piston main body and the cylinder is configured to be larger when the piston apparatus is at a top dead center than when the piston apparatus is at a bottom dead center.

6 more elements

A fluid device arranged in a piston apparatus which is applied to an external combustion engine and which includes a piston main body and a pressure-accumulating chamber that is formed inside the piston main body, the fluid device serves to introduce a working medium compressed in a working space of the external combustion engine into the pressure-accumulating chamber, wherein

the fluid device is arranged so that the working medium can flow in an introduction direction toward the pressure-accumulating chamber and an opposite direction of the introduction direction, and the fluid device has a channel resistance which is larger for the opposite direction than for the introduction direction,
a difference between the channel resistance for the introduction direction and the channel resistance for the opposite direction in the fluid device is not based on an channel opening/closing operation of a channel of the fluid device which is caused by an operation of a movable part such as a valving element, but based on a shape of the fluid device,
an inlet portion of the fluid device facing against the introduction direction is formed to have a relatively large curvature, and is formed to have an opening whose dimension is gradually decreasing toward inside so that the working medium is drawn into the channel of the fluid device along a smooth streamline, and
an inlet portion of the fluid device facing against the opposite direction is formed so that a curvature thereof is zero or nearly zero, and an edge is formed at the inlet portion facing against the opposite direction so as to separate the working medium when the working medium in the pressure-accumulating chamber moves in a direction to flow in the opposite direction.

1 more element

Dependencies are inferred from the claim text.

Piston apparatus, stirling engine, external combustion engine, and fluid device

Life of this patent

Piston apparatus, stirling engine, external combustion engine, and fluid device

Life of this patent

Abstract

Claims15