JPH01138351A - Free piston type stirling engine - Google Patents

Abstract

PURPOSE:To obtain a small-sized starter by installing a small piston which moves in the gas spring space in which a displaler acts and a driving device which drives the small piston and possesses the control function to stop the small piston at an arbitrary position. CONSTITUTION:When the stator coil 5 of a motor in a starter which is installed on the side part of a Stirling engine body through a passage 4 is brought into electric conduction, and a rotor 6 is revolved, a crankshaft 7 formed integrally with the rotor 6 revolves, and a small piston 9 moves in reciprocation through a connecting rod 8. When the piston 9 moves leftward, the pressure in a gas spring space 10 increases, and a displacer 11 is raised, while when the small piston 9 moves rightward, the displacer 11 is lowered. Through the vertical movement of the displacer 11, working gas flows in reciprocation between a high temperature space 15 and a low temperature space 16, passing through a heater 12, regenerator 13, and a cooler 14, and a power piston 17 is moved in reciprocation by the increase and reduction of the working gas pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the starting and control of free-piston Stirling engines.

The Stirling engine, which is a conventional external combustion engine, has many characteristics such as high efficiency, quietness, and fuel versatility. Stirling engines can be roughly divided into two types based on their configuration: free-piston Stirling engines in which the displacer and/or power piston are not tied together by a crank mechanism, and Stirling engines in which the displacer and power piston are connected to a crank mechanism (hereinafter referred to as mechanical type Stirling engines). There is a Stirling institution. Free-piston Stirling engines generally have the advantage of low mechanical losses because the power piston is not restrained by the crankshaft or connecting rod. but,
The displacer and piston move freely, making startup and control difficult.

In order to solve the above-mentioned problems, a typical example of a conventional starting device is a method in which the displacer body shown in FIG. 3 is started using a linear motor (Japanese Patent Publication No. 59-501470). This comprises an armature 2 fixed to the displacer I for starting the displacer 1, and a stator 3 next to the armature 2 supported by the housing of the Stirling engine. The displacer is started by supplying power to the coil wound around the stator 3.

Problems to be Solved by the Invention In the conventional system described above, since the displacer 1 is large, the armature 2 attached to the displacer 1 is also inevitably large, making the entire displacer 1 considerably heavy. In order to drive such a heavy displacer and control its amplitude, etc., the higher the frequency, the greater the inertial force of the displacer 1, so a powerful thrust is required. Inevitably, linear motors become larger. Furthermore, when such a large starter device is placed coaxially with the displacer 1, the design of the engine cooler and working gas passage is restricted. Roughly speaking, if the displacer 1 is even slightly eccentric from the axis, the linear motor is large, so the displacer 1 receives a large lateral force, and the bearing must also become large.

Means for Solving the Problems The present invention provides a freewheel drive system that is equipped with a small piston that communicates with the gas spring space in which the displacer acts, and a drive device that has a control function that can drive the small piston and stop the small piston at any position. It is a piston type Stirling engine.

Since the activation device does not need to be placed coaxially with the displacer, the design of the engine body is easy, and the small piston built into the activation device is smaller and lighter than the displacer, so the inertia force due to the small piston is small. , the motor used as the electrical means can also be small. Furthermore, by providing a control function that can stop the small piston at any position, the volume of the gas spring space of the displacer can be changed, and by changing the spring constant of the gas spring space, the resonant frequency of the displacer changes, and the amplitude of the displacer can be controlled.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIG. 1, when the rotor 6 is rotated by supplying electric power to the stator winding 5 of the motor in the starter device attached to the side of the Stirling engine main body through the passage 4,
A crankshaft 7 integrated with a rotor 6 rotates, and a small piston 9 connected by a connecting rod 8 reciprocates. For example, when the small piston 9 moves to the left, the pressure in the gas spring space IO becomes hg, pushing the displacer 11 upward. Conversely, when moving to the right, the pressure within the gas spring space 10 decreases and the displacer 11
moves downward. In this way, the displacer 11
When shooting under hfh, the working gas such as helium sealed inside the Stirling engine flows into the heater 12. Regenerator 13. It passes through the cooler 14 and reciprocates between the high temperature space 15 and the low temperature space 16. For example, when the displacer 11 moves upward, the working gas in the high-temperature space 15 passes through the heater 12, stores the heat of the gas itself in the regenerator 13, is cooled in the cooler 14, and returns to the low-temperature space 15. Move to the side. At this time, a proportion of the working gas in the space above the power piston 17 is in the low-temperature space, and the pressure decreases and the piston 17 is pulled up. Conversely, when the displacer 11 moves downward, the working gas in the low temperature space 16 passes through the cooler 14, is stored in the regenerator 13, absorbs heat, is heated by the heater 12, and is transferred to the high temperature space 15 side. Moving. At this time, a proportion of the working gas above the power piston 17 is on the high temperature space 15 side, and the working gas pressure increases, pushing the power piston 17 downward. - When starting the displacer 1 due to pressure fluctuations caused by heating and cooling, even if the starting device is stopped, the displacer 1
1 and the power piston 17 continue to move.

In this way, only a small starting device is required, and there is no need to place it on the same axis as the engine body, so installation is free and the cooler 1/l
- The design of the engine body is easy because it does not interfere with the arrangement of the regenerator 13, etc. Furthermore, by setting the position of the small piston 9 in accordance with the signal from the load sensor 20 using the control device 18 and changing the volume of the gas spring space of the displacer 11, the resonant frequency of the displacer changes, and the engine output is adjusted according to the load. It can be changed. Also, although not shown, for example, the rotor 6 and the small piston 9 may be provided with a groove, such as by forming a groove on the rotor 6 and engaging the stopper with the groove.
By providing either one of the crankshafts 7 with a braking function, the small piston 9 hardly moves and stable operation is possible.

Effects of the Invention The Stirling engine of the present invention has a small piston that communicates with the gas spring space where the displacer acts, and a drive device that has a control function that can drive the small piston and stop the small piston at any position. It can be started with a small drive device, and by changing the position of the small piston in response to the load signal, the volume of the gas spring space of the displacer changes, which changes the resonant frequency of the displacer, making it possible to control the amplitude of the displacer in accordance with the load.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a main part of a free piston type Stirling machine and starting device according to an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of a main part of a typical conventional starting part. 9...Small piston, 10...Gas spring space,
11...Displacer, 18...Control device, 2
0...Load sensor. Name of agent: Patent attorney Toshio Nakao Person No. 1 Group No. 1 Yoshio No. 2 Figure 2

Claims (5)

[Claims] (1) The space inside the cylinder is divided into a high-temperature space and a low-temperature space by a reciprocating displacer, and a side passage with a heater, a regenerator, and a cooler is provided between the high-temperature space and the low-temperature space. A free piston type Stirling that is equipped with a small piston that communicates with the gas spring space where the displacer acts, a sensor that detects the load, and a drive device that has a control function that drives the small piston and stops the small piston at any position. engine. (2) The free-piston Stirling engine according to claim 1, which is provided with a stepping motor and a crank mechanism as a drive device for the small piston. (3) The free piston type Stirling engine according to claim 1, wherein a position controllable linear motor is provided as a drive device for the small piston. (4) The free piston Stirling engine according to claim 1, wherein the drive device including the small piston has a brake function. (5) The free-piston Stirling engine according to claim 1, wherein the load signal is temperature, temperature difference, pressure, amplitude or position of the piston or displacer, or a combination of some of these.