JPH0375746B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in free-piston internal combustion engines.

Conventional structure and its problems Conventionally, the Stirling engine, which is an external combustion engine, has characteristics such as high efficiency, fuel efficiency, and quietness.
Many companies are engaged in research, and among Stirling engines, the free-piston Stirling engine is one that has low mechanical loss and is expected to be highly efficient.

Some free piston heat engines of this type use gas springs with a large spring constant in their spring parts. However, when configured with only gas springs, movable components such as pistons may not always be in the designed position at the time of startup, such as by falling in the direction of gravity due to their own weight, making it difficult to start, especially during startup, etc. A moving component such as a piston may collide with a cylinder wall or the like. For this reason,
This increases the number of design constraints and requires a large space, which is one of the causes of a decline in the performance of heat engines.

OBJECTS OF THE INVENTION The present invention solves the above problems by using both a gas spring and a coil spring without causing any deterioration in engine performance.

Structure of the Invention The present invention arranges a piston and a displacer in a cylinder, and for example, either a gas spring formed between the piston and the displacer or a gas spring formed on the bottom surface of the piston and the cylinder body, or Both have coil springs which maintain the movable components near the center of motion;
It is also easy to start, and movable components such as pistons do not collide with cylinder walls etc. during startup.
This enables stable and smooth operation.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below. In the figure, 1 is the load, 2 is the cylinder body, 3 is the communication pipe between the low temperature side heat exchanger and the compression space, 4 is the low temperature side heat exchanger, 5 is the regenerator, 6 is the high temperature side heat exchanger, 7
8 is an expansion space, 9 is a displacer, 10 is a compression space, 11 is a piston, 12 is a coil spring,
13 is a gas spring space between the displacer and the piston, 14 is a coil spring, and 15 is a gas spring space between the piston and the cylinder.

Next, the operation of the free piston type heat engine will be explained. Gas such as helium air is sealed inside the engine. When the displacer 9 moves downward, the gas present in the compression space 10 passes through the communication pipe 3, the low temperature side heat exchanger 4, the regenerator 5, the high temperature side heat exchanger 6, and the communication pipe 7, and enters the expansion space. Sent to 8th. In this process, the gas expands endothermically and the piston 1
Push down on 1. Next, displacer 9
When moves upward, the gas in the expansion space 8 becomes
Reversely passing through the passage and the heat exchanger, the compression space 10
sent to. During this process, the gas is cooled, the pressure of the gas decreases, and the piston 11 is pulled upward. By repeating this operation, the piston 11 performs work against the load 1.

Here, since a coil spring is used in addition to a gas spring for the spring part, the displacer 9 and piston 11 can be placed near the center position of the movement, making it easy to start, and also providing Collisions between the sprayer 9 and the wall of the cylinder 2, the piston 11 and the wall of the cylinder 2, etc. can also be prevented.

In addition, in the above embodiment, the coil spring was arranged to match the gas spring formed in the space formed by the piston and the displacer and the space formed by the piston and the cylinder body.
The same applies to an engine in which a gas spring is formed in a space formed by a displacer and a cylinder body, and a space formed by a piston and a cylinder body, or a case in which a gas spring is formed in only one of the spaces.

Effects of the Invention As described above, in the Stirling engine of the present invention, by using both a gas spring and a coil spring in the spring portion, the piston and displacer can be placed at any designed position, for example, at the motion center position. The pressure of the gas spring can be made the average pressure of the fluctuating pressure at the center position, making it easy to start and preventing collisions between the piston and the displacer.

Furthermore, in the present invention, since a gas spring and a coil spring are provided together, design latitude is greatly expanded.

For example, a gas spring can be used as a vibration system spring that mainly determines the operating frequency, and a coil spring can be used as a spring for positioning a displacer or piston when it is stopped, so the position of the displacer or piston can be controlled. It becomes possible to easily do things that would be nearly impossible with a conventional configuration using only coil springs, such as matching the design frequency during operation and holding the system at a nearly central position when stopped.

[Brief explanation of drawings]

The drawing is a configuration diagram of a free piston type heat engine according to an embodiment of the present invention. 1... Load, 2... Cylinder body, 8... Expansion space, 9... Displacer, 10... Compression space, 11... Piston, 12, 14... Coil spring, 13, 15... Gas spring .

Claims (1)

[Claims] 1 It has a container that holds working gas in the working space, a heater, a regenerator, a cooler, and a power piston and a displacer that reciprocate inside the working space, and both the piston and the displacer or A Stirling engine is provided with a gas spring and a coil spring having a spring constant that holds the piston or displacer near the center of motion when stopped, respectively, on the one hand in the axial direction.