JP2007298219A - Stirling refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Stirling refrigerating machine having control method for compensating heat load change. <P>SOLUTION: This Stirling refrigerating machine comprises a cylinder, a surrounding member formed in a state of surrounding at least one end of the cylinder, a displacer received in the cylinder, reciprocated in the axial direction of the cylinder and forming an expansion space with the surrounding member, a piston received in the cylinder, reciprocated in the axial direction of the cylinder, and forming a compression space with the displacer, a cooling portion communicating the compression space and the expansion space and composed of a heat exchanger and a cold storage unit, a linear motor reciprocating and driving the displacer and the piston, and a control means adjusting the reciprocation of the displacer and the piston, and controlling the change of volumes of the compression space and the expansion space. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a Stirling refrigerator, and more particularly to vibration control means suitable for stabilizing the reciprocating motion of a piston and a display.

  Stirling refrigerators are widely used as important refrigeration means. A Stirling refrigerator basically includes a displacer, a piston, a cylinder that forms a compression space and an expansion space surrounding them, a cooling unit that connects the compression space and the expansion space, and a linear motor that drives the displacer and the piston. Composed.

  In the Stirling refrigerator, the volume of the expansion space and the compression space fluctuates due to the reciprocating movement of the displacer and the piston, and the refrigerating power is generated by repeating the cycle of the state of the working gas enclosed inside as a refrigerator. Function. However, since it is assumed that when the working gas state repeats a certain cycle, the working gas state changes instantaneously, such a change cannot actually occur. A state change cycle of the working gas is formed by moving in a sinusoidal waveform having a phase difference.

In a Stirling refrigerator, two linear motors can be used to move the displacer and piston. However, if the drive frequency increases, the inertial force acting on the piston and displacer becomes very high and an excessive motor is required. It becomes. For this reason, a vibration system having a spring is attached and driven near the resonance point to suppress the motor capacity. Accordingly, mechanical springs and gas springs exist as elements constituting the vibration system in the Stirling refrigerator. Mechanical springs are linear, while gas springs are non-linear. Since the displacement waveform is greatly influenced by the characteristics of the non-linear spring, there is no guarantee that even if an alternating force of the electric motor is applied, an alternating displacement having the stop position as the vibration center can be applied to the displacer and the piston. That is, the position of the vibration center is displaced, and there may be a problem that the returning piston and the displacer collide with the end of the cylinder or the dead volume of the compression chamber increases. As a method of solving these problems, there is Japanese Patent No. 2559839 (hereinafter referred to as Patent Document 1). In patent document 1, it has the displacement measurement means which measures the displacement of the piston and displacer which comprise a Stirling refrigerator, and the vibration center and amplitude of a piston and a displacer are obtained from the displacement amount of a piston and a displacer. A method for controlling the current of the motor driving the piston and the displacer to approach the amplitude has been disclosed.
Japanese Patent No. 2559839

  In the method of Patent Document 1, control is performed so that the reciprocating center of the piston and the displacer does not change even if the working gas state changes due to the temperature change of the refrigerator. Not. That is, optimal refrigeration output control that matches the heat load of the cooling unit is not performed. That is, it is impossible to set an optimum target value for performing amplitude control, vibration center control, phase angle control, and frequency control corresponding to the temperature of the cooling section.

  This invention is made | formed in view of said actual condition, and makes it a subject to provide the Stirling refrigerator which has a control form which compensates a thermal load fluctuation | variation.

  The Stirling refrigerator of the present invention forms an expansion space between a cylinder, an enclosing member that surrounds at least one end of the cylinder, and a reciprocating motion in the axial direction of the cylinder that is accommodated in the cylinder. A displacer, a piston that is accommodated in the cylinder and reciprocates in the axial direction of the cylinder to form a compression space, a heat exchanger that communicates the compression space and the expansion space, and a regenerator. A cooling unit, a linear motor that reciprocates the displacer and the piston, and a control unit that adjusts the reciprocating motion of the displacer and the piston to control the volume change of the compression space and the expansion space.

  Moreover, it is preferable that the control means of the Stirling refrigerator of the present invention includes position detection means for detecting position fluctuations of the piston and the displacer, and temperature detection means provided in the cooling part for detecting the temperature of the cooling part. Further, the control means of the Stirling refrigerator of the present invention comprises: an amplitude calculating means for calculating the center position, amplitude or phase angle of the displacer and piston from the output signal of the position detecting means; and a detected temperature detected by the temperature detecting means. Temperature deviation calculating means for calculating the temperature deviation between the target temperature and the target temperature of the optimum amplitude, optimum amplitude center, optimum phase angle and optimum frequency to eliminate the temperature deviation based on the calculation results of the amplitude calculating means and the temperature deviation calculating means. Linear so as to eliminate motion deviations from the target value calculation means for calculating the value and the target values of the optimum amplitude, optimum amplitude center, optimum phase angle, and optimum frequency of the piston and the displacer based on the calculation result from the target value calculation means It is preferable to have power supply control means for controlling the power supply of the motor.

  As described above, by providing the temperature detection means in the cooling unit, the temperature change due to the fluctuation of the thermal load is detected in the cooling unit, and the optimum amplitude, optimum vibration center, optimum phase angle, or optimum corresponding to the temperature of the cooling unit is detected. The frequency can be set. That is, the Stirling refrigerator of the present invention can have a control form in which optimum refrigeration output control corresponding to the heat load is performed and the heat load fluctuation is compensated.

  According to the Stirling refrigerator of the present invention, it is possible to prevent the deviation of the vibration center due to the characteristics of the vibration system, and the optimum amplitude, optimum vibration center, optimum phase angle corresponding to the temperature change due to the load of the cooling unit, or An optimum frequency can be set, and a control configuration that compensates for thermal load fluctuations can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A cross-sectional view of the schematic configuration of the Stirling refrigerator of the present embodiment is shown in FIG. FIG. 2 is a conceptual diagram of the Stirling refrigerator of this embodiment. As shown in FIG. 2, the Stirling refrigerator of this embodiment mainly includes a displacer 1, a piston 2, a cylinder 3, a cooling unit 4, a linear motor 51 (for a displacer), 52 (for a piston), and control means. C (shown in FIG. 1). Further, in the cylinder 3, an expansion space 11 and a compression space 21 are respectively formed by the surrounding member 31, the displacer 1, or the piston 2, and communicated via the cooling unit 4. The cooling unit 4 includes a heat absorber 41, a regenerator 42, a radiator 43, and a connecting passage 44. The surrounding member 31 is integrally formed by surrounding the cylinder 3 at the upper end of the cylinder 3. In addition, the heat absorber 41 and the heat radiator 43 comprise the heat exchanger of this invention.

  The displacer 1 is driven by a linear motor 51, and the piston 2 is driven by a linear motor 52. The linear motors 51 and 52 are coil movable linear motors, permanent magnet movable linear motors, or iron core movable linear motors, and use the force generated by flowing current in a constant magnetic field formed by permanent magnets. Is. For this reason, the linear motors 51 and 52 can control the force generated by adjusting the current or voltage. As a result, the vibration system of the Stirling refrigerator can be controlled.

  Further, the Stirling refrigerator of the present embodiment is provided with a displacer amplitude detecting means 61 or a piston amplitude detecting means 62 for detecting a position variation due to vibration of the displacer 1 or the piston 2 at a predetermined position. In addition, the amplitude detection means 61 and 62 can be installed in the site | part which is easy to detect the position change of the displacer 1 and the piston 2. FIG. For example, a configuration in which the amplitude detecting means 61 and 62 are provided in the linear motors 51 and 52, respectively, and the position fluctuations of the piston 2 and the displacer 1 are detected without a sensor by the current and voltage input to the linear motors 51 and 52 can be exemplified. . (As shown in FIG. 1) In addition, a displacement sensor can be placed in the wall of the cylinder 3 to detect the positional fluctuation of the displacer 1 and the piston 2 accommodated directly in the cylinder 3 (shown in FIG. 2). like). The configuration of the amplitude detection means 61 and 62 is not limited to these. The amplitude detection means 61 and 62 constitute the position detection means of the present invention.

  The displacer 1 constitutes an independent vibration system via a spring 510 and a linear motor 51, and the piston 2 constitutes an independent vibration system via a spring 520 and a linear motor 52, respectively. Further, the cooling unit 4 is provided with temperature detecting means 7 for detecting the temperature of the cooling unit 4. The temperature detecting means 7 can be constituted by a temperature sensor that directly detects the temperature, but can also be constituted by a pressure sensor that indirectly detects the temperature by the pressure of the working gas. Moreover, the structure of the temperature detection means 7 is not limited to these.

  Next, the operation principle of the Stirling refrigerator of this embodiment will be briefly described. The Stirling refrigerator of this embodiment has the same freezing principle as a general Stirling refrigerator. This will be described with reference to FIG. The piston 2 moves upward and compresses the working gas. Since the compression heat generated at this time is discharged to the outside through the medium, the working gas is compressed isothermally. Next, only the displacer 1 moves downward, and the working gas moves from the compression space 21 to the expansion space 11 through the cooling unit 4 constituted by the regenerator 42 and the like. Next, since both the displacer 1 and the piston 2 move downward, the working gas in the expansion space 11 expands and the temperature decreases. At this time, the heat load can be cooled by heat absorption. That is, since heat is conducted from the heat load to the cooling unit 4, the working gas is expanded isothermally. As a result, the generated low temperature can be output to the heat load as refrigeration power.

  Next, the control system of the Stirling refrigerator of this embodiment is shown in FIG. FIG. 1 schematically shows the configuration of a Stirling refrigerator. In FIG. 1, the same components as those in FIG. 2 are denoted by the same reference numerals. As shown in FIG. 1, the linear motor 51 that drives the displacer 1 (shown in FIG. 2) is provided with amplitude detector 61 for the displacer, and the linear motor 52 that drives the piston 2 (shown in FIG. 2) The piston amplitude detecting means 62 is installed. Further, a temperature detection means 7 is installed in the cooling unit 4 (shown in FIG. 2). Further, the Stirling refrigerator of the present embodiment includes a temperature deviation calculating unit 70, an amplitude calculating unit 60, a target value calculating unit 80, or a power source control unit 90.

  The temperature deviation calculating means 70 compares the detected temperature detected from the temperature detecting means 7 with the target refrigeration temperature and calculates a temperature difference.

  The displacer amplitude detecting means 61 and the piston amplitude detecting means 62 can detect the amplitudes of the displacer 51 and the piston 52 and output them to the amplitude calculating means 60 as signals. Further, the amplitude calculation means 60 calculates the vibration center, amplitude, phase angle, or frequency of the displacer 51 and the piston 52.

  The target value calculation means 80 calculates target values such as optimum amplitude, vibration center, phase angle, and frequency to eliminate the temperature deviation based on the results calculated from the temperature deviation calculation means 70 and the amplitude calculation means 60. is there.

  The power supply control means 90 adjusts the power supplies 51P and 52P (voltage or current) of the linear motors 51 and 52 that drive the displacer 1 and the piston 2 based on the result calculated by the target value calculation means 80 to obtain the target value. Control to achieve.

  As described above, the control means C of the Stirling refrigerator of the present embodiment includes the temperature detection means 7, the amplitude detection means 61 and 62, the amplitude calculation means 60, the temperature deviation calculation means 70, the target value calculation means 80, or the power supply control means. 90.

  In the Stirling refrigerator of this embodiment, a specific operation method can be exemplified as follows.

  (1.) In the target value calculation means 80, the values of the target value amplitude, amplitude center or target phase angle of the piston 2 and the displacer 1 corresponding to the temperature deviation between the detected temperature of the cooling unit 4 and the target value temperature are determined. The power source control means 90 adjusts the reciprocating motion of the piston 2 and the displacer 1 so as to eliminate the deviation from the target value. The voltage, current, or voltage and current offset amount of the power sources 51P and 52P of the linear motors 51 and 52 are eliminated. The target value is achieved by controlling the phase angle and frequency of the current.

  FIG. 3 shows an operation flow of the refrigerator of this embodiment. As shown in FIG. 3, the actual temperature when the refrigeration load is actually applied to the cooling unit 4 is detected using the temperature detecting means 7, and the detected temperature is compared with the target temperature by the temperature deviation calculating means 70. To calculate the temperature deviation. On the other hand, the amplitude detection means 61 and 62 constituting the position detection means detect the actual vibration state of the displacer 1 and the piston 2, respectively, and the amplitude calculation means 60 calculates the vibration center, amplitude, and phase angle under this state. . Further, the target value calculation means 80 calculates a deviation value such as a vibration center, amplitude, or phase angle according to the temperature deviation, and determines an optimum amplitude center, amplitude, vibration phase angle, or frequency.

  The power supplies 51P and 52P of the linear motors 51 and 52 for driving the piston 2 and the displacer 1 according to the command of the optimum values such as the amplitude center, amplitude, phase angle and frequency output from the target value calculation means 80 are supplied to the power supply control means 90. Controlled. 4 and 5 show characteristics based on the principle of electromagnetics that can adjust the amplitude center and amplitude by power supply control. As shown in FIG. 4, the vibration (amplitude) center position has a linear relationship with the voltage (current) offset amount, and can be adjusted by the voltage (current) offset amount. Further, as shown in FIG. 5, the vibration amplitude value has a linear relationship with the voltage value or the current value, and can be adjusted by the voltage value and the current value.

  The displacement of the vibration center, amplitude, or phase angle varies depending on the difference in the type and state of the working gas due to the temperature deviation, and the displacement of the vibration center, amplitude, or phase angle due to the temperature deviation corresponding to the working gas. A quantity map is required, but experiments can be performed according to the actual working gas used to create the map and store it in the database. Thereby, the displacement amount of the amplitude center, the amplitude, or the phase angle is obtained from the database according to the temperature deviation.

  The temperature control means 7 is provided in the cooling unit 4 in the control system (control means) C of the refrigerator, the temperature deviation is calculated by comparing the set temperature (target temperature) of the refrigerator and the detected temperature, and the temperature deviation is linear. Since the control values of the motors 51 and 52 are calculated and controlled, the refrigerator can always be operated at a stable temperature even if the load fluctuates at the output end of the cooling unit 4.

  (2.) When the heat load of the refrigerator suddenly increases, the target value calculation means 80 sets a target frequency higher than the operating frequency so far, and linear motor is used to temporarily improve the refrigeration output capacity. The frequency of the power supplies 51P and 52P of 51 and 52 can be adjusted to achieve the target value. That is, when the heat load is suddenly increased or the set temperature (target temperature) is suddenly lowered, the operation frequency of the refrigerator can be increased and the operation can be performed with the refrigeration output exceeding the rating. As a result, an increase in temperature due to an increase in heat load on the cooling unit 4 can be suppressed, and the time for achieving the target temperature can be shortened. That is, the refrigerator can always be operated at a stable temperature.

  The Stirling refrigerator of the present invention can be used in fields such as refrigeration equipment and air conditioning.

1 shows a control system of a Stirling refrigerator according to an embodiment of the present invention. The structure of the Stirling refrigerator of embodiment of this invention is shown. It is a control flow figure of the Stirling refrigerator of the embodiment of the present invention. The vibration center position characteristic with respect to the voltage (current) offset amount is shown. The amplitude characteristic with respect to the voltage (current) value is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Displacer 11: Expansion space 2: Piston 21: Compression space 3: Cylinder 31: Enclosing member 4: Cooling part 41: Heat absorber 42: Regenerator 43: Radiator 44: Connection passage 51: Linear motor for displacer
52: Piston linear motor 510, 520: Spring 51P: Displacer linear motor power supply 52P: Piston linear motor power supply C: Control unit 61: Displacer amplitude detection means 62: Piston amplitude detection means 7: Temperature detection means 70: Temperature deviation calculation means 60: Amplitude calculation means 80: Target value calculation means 90: Power supply control means

Claims (3)

A cylinder,
An encircling member formed to enclose at least one end of the cylinder;
A displacer that is accommodated in the cylinder and reciprocates in the axial direction of the cylinder to form an expansion space with the surrounding member;
A piston housed in the cylinder and reciprocating in the axial direction of the cylinder to form a compression space with the displacer;
A cooling unit comprising a heat exchanger and a regenerator that communicate the compression space and the expansion space;
A linear motor that reciprocally drives the displacer and the piston;
A Stirling refrigerator comprising: control means for controlling reciprocation of the displacer and the piston to control volume changes of the compression space and the expansion space.   2. The Stirling according to claim 1, wherein the control unit includes a position detection unit that detects a position variation of the piston and the displacer, and a temperature detection unit that is provided in the cooling unit and detects a temperature of the cooling unit. refrigerator.   The control means includes an amplitude calculation means for calculating an amplitude center position, amplitude or phase angle of the displacer and the piston from an output signal of the position detection means, and a detected temperature and a target temperature detected by the temperature detection means. Temperature deviation calculating means for calculating the temperature deviation of the target, and the target values of the optimum amplitude, optimum amplitude center, optimum phase angle, and optimum frequency for eliminating the temperature deviation based on the calculation results of the amplitude calculating means and the temperature deviation calculating means Between the target value calculation means for calculating the optimum amplitude of the piston and the displacer, the optimum amplitude center, the optimum phase angle, and the target value of the optimum frequency based on the calculation result from the target value calculation means The Stirling refrigerator according to claim 1, further comprising power control means for controlling the power of the linear motor so as to eliminate the deviation.

Images