JPH074763A - Refrigerating device - Google Patents

Abstract

PURPOSE:To eliminate the restriction of two pistons in their reciprocating movement and in the central position of the reciprocating movement at the compressing parts by a method wherein oppositely arranged first and second pistons are magnetically levitated by magnetic bearings and driven by linear reciprocating motors. CONSTITUTION:Oppositely arranged first and second pistons 1a and 1b are driven by the linear motors which, together with magnetic bearing 4a and 4b, magnetically levitate and move their respective piston shafts 2a and 2b. To accomplish this, a means is provided which controls the displacement detecting means 5a and 5b for both the pistons and the electricity input components for the linear reciprocating motors in order to completely keep the pistons and the body of the refrigerating machine out of contact and to permit adjustment of the central position of the reciprocating movement and this reciprocal movement of both the pistons at the oppositely positioned compressing parts. This can eliminate the restriction of the two pistons in their reciprocating movement and in the central position of the reciprocating movement at the compressing parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator, and more particularly to a refrigerator.
The present invention relates to a refrigerator whose refrigerating capacity needs to be adjusted like a general-purpose Stirling refrigerator used in experiments at a space station.

[0002]

2. Description of the Related Art A conventional technique will be described below by taking a Stirling refrigerator as an example. FIG. 3 shows a schematic diagram of the Stirling refrigerator, and FIG. 4 shows its thermodynamic cycle. First,
The operation principle will be described based on these figures. The Stirling refrigerator is basically composed of a displacer, a piston, and a regenerator. In FIG. 4, the regenerator is structured to be housed inside the displacer, but may be installed outside the cylinder at any position where the compression space and the expansion space are electrically connected. The stroke of → is the compression stroke, and the piston moves upward in the figure to compress the gas. The compression heat generated at this time is discharged to the outside of the cylinder using a medium such as water or air. Therefore, the compression will be performed isothermally. The stroke of → is an equal volume stroke, only the displacer moves downward, and the gas moves from the compression space to the expansion space through the regenerator. The process of → is an expansion process and both the displacer and the piston move downward, so the gas in the expansion space expands and the temperature drops. On the thermodynamic cycle, this change is an isothermal change and can be realized by externally applying a constant heat load, which corresponds to the refrigerating capacity. →
The stroke of is the same volume stroke, the displacer moves upward, and contrary to the stroke of →, the gas passes through the regenerator and moves from the expansion space to the compression space. At this time, the gas that still has the refrigerating capacity is cooled in the regenerator by heat exchange with the regenerator and moves to the compression space. Therefore, in the process of →, when the gas moves from the compression space to the expansion space, the gas is cooled by heat exchange in the regenerator section. By repeating such a cycle, a refrigerator having a certain refrigerating capacity can be realized. Although this change is theoretically constructed on the assumption that it occurs instantaneously, such a change cannot occur in reality, but in practice, by moving the piston and displacer with a finite time sine waveform with a phase difference. Forming this cycle.

A conventional Stirling refrigerating machine using the refrigerating cycle described above and provided with an opposed compression section is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-200158. This is
As schematically shown in Fig. 1, a first piston 1a that horizontally reciprocates: a second piston 1b that is arranged horizontally opposite to the first piston and that reciprocates in an opposite phase to the first piston: acts on the first piston. First crank portion 13a that is electrically connected
It is provided with a crankshaft 14 having a second crank portion 13b having a phase opposite to that of the above, and has a crank mechanism for driving both pistons, and is intended to reduce vibration of the compression portion.

[0004]

A general-purpose Stirling refrigerator used in a space station is required to have a mechanism capable of controlling the refrigerating capacity according to the object of the experiment. There is a problem in that the pressure of the compression space and the exhaust volume for changing the refrigerating capacity of the Stirling refrigerator, which is fixed to the crankshaft, cannot be adjusted.

It is an object of the present invention to eliminate the restriction of the amplitude of both pistons of the compression section and the restriction of the center position of the amplitude so that the exhaust volume can be changed and the refrigerator having an opposed compression section which can be applied to a wide range of refrigerating capacity. To provide. That is, it is an object of the present invention to provide a refrigerator provided with an opposed compression unit that controls the refrigerating capacity by adjusting the pressure and exhaust volume of the compression space.

[0006]

In order to achieve the above object, the present invention magnetically levitates and drives the piston shafts of a first piston and a second piston, which are opposed to each other, by a magnetic bearing and a linear motor. , By driving the piston with a linear motor, the piston and the main body are made completely non-contact, and the displacement center of both pistons in the opposed compression unit and the amplitude of the linear reciprocating motor can be adjusted so that the amplitude can be adjusted. It is provided with means for controlling the input component.

[0007]

According to the present invention, since the first piston and the second piston are magnetically levitated by the magnetic bearings and driven by the linear reciprocating motor, the amplitude limitation and the amplitude center position of both pistons in the compression section are suppressed. You can remove the restrictions. Furthermore, the refrigerating capacity of the refrigerator is controlled by detecting the amplitude center position and amplitude of both pistons by means of displacement detection means of both pistons and linking to the detected value to adjust the electric input component of the linear reciprocating motor. It is possible to achieve the above object.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, in the present embodiment, a first piston 1a in which a first compression part constituting a refrigerator is installed in the center of the inside of a cylinder 7a, a shaft 2a of the first piston for supporting the piston, and a shaft of the piston. Magnetic bearing 4 combining stator and coil to magnetically levitate 2a
a, an axial displacement detecting means 5a installed coaxially with the shaft 2a of the piston at the end of the cylinder 7a, a permanent magnet 6a mounted at the center of the shaft 2a of the piston, and a cylinder 7a for reciprocating the permanent magnet. The linear motor coil 3a. Then, the second compression section having the same structure as the first compression section is installed opposite to the first compression section via the joint flange 12, and the working medium of the first and second compression sections is provided in the flow path of the joint flange 12. It is available for distribution.
In addition, the displacer portion 8 equipped with the regenerator via a connecting pipe that is mounted in communication with the flow path of the joint flange 12
Are connected. And both linear motor coils 3
There is a linear motor power supply 9 that supplies current to a and 3b.
Further, it has a control unit 10 for controlling the linear motor power supply 9 based on the signals of both displacement measuring means 5a, 5b. There is a magnetic bearing power supply 11 that supplies current to both magnetic bearings 4a, 4b. The present embodiment is a Stirling refrigerator configured as described above.

The operation of the configuration of this embodiment will be described below. When the magnetic bearing power supply 11 is turned on, both piston shafts 1a and 1b are magnetically levitated and are in a completely non-contact state. Therefore, the linear motor coil 3
By supplying an alternating current from a linear motor power source to a and 3b, both pistons 1a and 1b are reciprocated, and a necessary pressure and exhaust volume are provided to a displacer portion 8 having an expansion space for adiabatic expansion of the working medium. .

Next, the case of adjusting the refrigerating capacity of the refrigerating cycle using this apparatus will be described with reference to the control flow chart shown in FIG. First, the operator gives the control unit a refrigerating capacity corresponding to the load 15, and the control unit calculates the pressure and the exhaust volume for obtaining the necessary refrigerating capacity by the calculator 16, and based on the calculation result, the target amplitude is calculated. And the target amplitude center position is calculated by the calculator 17, the deviation d1 between the current amplitude output from the displacement measuring means and the target amplitude is calculated by the calculator 18, and the linear motor is operated until d1 of the comparator 20 becomes zero. Control is performed to adjust the DC component of the power supply (step 22).
Further, in the control unit, the deviation d2 between the amplitude center position and the target value is
Is also calculated by the calculator 19, and control is performed to adjust the AC component of the linear motor power supply until d2 of the comparator 21 becomes 0 (step 23). Further, the displacement detection means always detects the displacement of both pistons and outputs a signal to the control unit (step 24).

According to the present embodiment, both pistons are magnetically levitated, thereby eliminating the amplitude limitation and the amplitude center position limitation. Further, in the present apparatus, the amplitude and the center position of the amplitude can be freely controlled by adjusting the input components to the linear motor coils mounted to reciprocate the respective pistons in the same phase. This is to adjust the pressure of the compressor and the exhaust volume, and it was possible to control the refrigerating capacity in the refrigerating cycle.

[0012]

According to the present invention, since the first piston and the second piston, which are arranged opposite to each other, are magnetically levitated by the magnetic bearing and are driven by the linear reciprocating electric motor, the amplitude of both pistons in the compression section is increased. The limit of and the limit of the amplitude center position can be deleted. Furthermore, the refrigerating capacity of the refrigerator is controlled by detecting the amplitude center position and amplitude of both pistons by means of displacement detection means of both pistons and linking to the detected value to adjust the electric input component of the linear reciprocating motor. It becomes possible.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a refrigerator of the present invention.

FIG. 2 is a control flowchart of the embodiment.

FIG. 3 is an explanatory diagram of a Stirling refrigeration cycle.

FIG. 4 is an explanatory view of the thermodynamic cycle.

FIG. 5 is a block diagram of a conventional opposed compression unit.

[Explanation of symbols]

1a ... 1st piston, 1b ... 2nd piston, 2a ... 1st piston shaft, 2b ... 2nd piston shaft, 3
a, 3b ... Linear motor coil, 4a, 4b ... Magnetic bearing, 5a, 5b ... Displacement measuring means, 6a, 6b ... Movable permanent magnet, 7a, 7b ... Cylinder, 8 ... Displacer, 9
... linear motor power supply, 10 ... control unit, 11 ... magnetic bearing power supply, 12 ... joint flange.

Claims (1)

[Claims] 1. A compression unit for synchronously driving a first piston and a second piston, which are arranged opposite to each other, by a linear reciprocating electric motor, a displacer reciprocating with a phase difference between both pistons, and a cold storage for precooling a working medium. In a refrigerator composed of a reactor, the first piston and the second piston are driven by a linear reciprocating electric motor, and the electric input components of the linear reciprocating electric motor are linked by linking the detected values detected by the displacement detecting means of both pistons. A refrigerator characterized in that the center of amplitude and the amplitude of both pistons can be adjusted by adjusting.