JPH02294570A - Exciting system for electromagnetically-driven type reciprocating compressor - Google Patents

Abstract

PURPOSE:To maintain performance of a compressor and to relieve generating vibration by a method wherein a driver coil is excited by means of an AC in which a high frequency having a frequency higher than that of a fundamental wave is overlapped with a fundamental wave of a frequency responding to the reciprocating motion of a compressor. CONSTITUTION:A pair of pistons 3A and 3B are positioned facing each other in a single cylinder 2 with a compression space 2a of a working medium formed therebetween. Diver coils 11A and 11B coupled to the pistons 3A and 3B, respectively, are arranged in the magnetic field of a constant magnetic field magnet device. The driver coils 11A and 11B are excited by means of an AC in which a high frequency having a frequency higher than that of a fundamental wave and amplitude lower than that of the fundamental wave is overlapped with a fundamental wave of a frequency responding to the reciprocating motion of a compressor. This method maintains performance of the compressor and relieves generating vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an excitation method for a driver coil of an electromagnetically driven reciprocating compressor that reciprocates a piston using electromagnetic force. [Prior Art] Since the piston of the reciprocating pressure I1iIIIl linearly reciprocates, pulsating vibrations occur during operation, which is a major cause of noise and shortened service life. To this end, various anti-vibration measures have been taken in the past, one of which is a method in which the piston is electromagnetically driven by a linear motor, and in terms of structure, the working medium is housed in a single cylinder with both ends open. A pair of pistons are arranged facing each other on both sides of the compression space, and a driver coil coupled to each piston is arranged in the magnetic field of a constant magnetic field magnet device, and a phase difference of 180 degrees is given to each drive element. Did you use alternating current excitation of the child coil to electromagnetically drive the piston? ! A magnetically driven reciprocating compressor was published by the same applicant in JP-A-61-210.
It has already been proposed as No. 276. According to the configuration proposed above, a pair of pistons reciprocates in opposite directions in synchronization with each other in a single cylinder, so the inertial forces of each piston cancel each other out, making it possible to suppress vibrations in the entire compressor. Can be done. [Problems to be Solved by the Invention] By the way, the above-mentioned compressors generally employ a clearance seal system in order to keep the sliding friction between the cylinder and the piston to a minimum. This clearance seal method is a method in which gas, which is a working medium, is discharged from the compression space side of the cylinder into the minute gap between the cylinder and the piston, and the gas is sealed using the viscous resistance of the gas flow. In this case, in order to increase the efficiency of the compressor, it is necessary to reduce the fitting gap between the cylinder and piston as much as possible in order to suppress the amount of gas released as seal gas. On the other hand, when machining pistons and cylinders, machining errors occur in terms of accuracy in roundness and cylindricity, and this machining error causes local contact between the piston and cylinder during compressor operation. As a result, a so-called value is generated in this part, and this jump acts as a frictional resistance force on the movement of the piston. However, since the locations where the piston and cylinder jitter occur due to such machining errors are random, in a compressor that combines a pair of pistons in a single cylinder as described above, both pistons PX between
A difference occurs in the friction resistance. Moreover, the difference in the frictional resistance that acts individually on both pistons is the acceleration when driving the pistons! It also has a great effect on the pistons, and for this reason, it is not possible to maintain a 180 degree phase difference between the pistons during operation.
In addition to not being able to achieve exact synchronization, there will also be differences in the stroke amplitude of the reciprocating motion of each piston. As a result, in addition to a decrease in the effective displacement of the compressor, problems such as large vibrations and noise occur due to the difference in inertia of the pistons. The present invention has been made in consideration of the above points, and improves the excitation method of the driver coil connected to the piston to reduce the frictional force between the piston and the cylinder, thereby maintaining the performance of the compressor. The purpose of this paper is to provide an excitation method for an electromagnetically driven reciprocating compressor that reduces the vibration generated. [Means for Solving the Problems] In order to solve the above problems, the present invention targets the above-mentioned electromagnetically driven reciprocating compressor. It has a higher frequency than waves. The driver coil is excited by an alternating current with a small amplitude superimposed wave. [Function] As a result of the above, in addition to the large alternating electromagnetic force that causes the piston to reciprocate in response to the frequency of the fundamental wave, there is also a superimposed electromagnetic force that has a higher frequency than the fundamental wave between the driver coil and the constant magnetic field magnet device. A minute alternating electromagnetic force is generated by the waves (the electromagnetic force due to the superimposed waves is set to a low value so as not to affect the reciprocating movement of the compressor piston). As a result, the piston is reciprocated within the cylinder at a period corresponding to the fundamental wave, and at the same time, the piston moves to the vertical dead center position at the end of the stroke during the reciprocating stroke (at this position, the direction of movement of the piston is reversed, so the movement is temporarily stopped). Even when the piston stops, a small excitation force due to the excitation of the superimposed wave is constantly applied to the piston. Therefore, even if the piston and cylinder locally contact each other due to machining errors during manufacturing as described above, the above-mentioned superimposed wave will be generated at the stroke top and bottom dead center positions during the reciprocating stroke of the piston. Since a small excitation force is applied by the piston and the cylinder, no static friction acts between the piston and the cylinder, and the piston and cylinder are always in a state of dynamic friction.
On the other hand, as is well known, the coefficient of dynamic friction is only 1 smaller than the coefficient of static friction. Therefore, by applying a slight excitation force to the piston using the excitation current of the superimposed wave applied to the driver coil as described above, and operating the piston so that dynamic friction always acts on the contact surface between the piston and the cylinder. , the frictional resistance between the piston and the cylinder becomes extremely small, and the difference in the frictional resistance that occurs between the pair of pistons installed in the cylinder is also small. This allows the compressor to operate stably. (Example) Fig. 1 shows a configuration diagram of an embodiment of the present invention, and Fig. 2 shows a waveform diagram of a fundamental wave and a superimposed wave applied as excitation current. The configuration of the machine will be explained. In the figure, a single cylinder 2 with a compression space 2a for a working medium formed in the body is installed in a case 1. A pair of pistons 3A and 3B with the same dimensions and weight specifications are arranged facing each other on the left and right sides of the cylinder.In addition, a working medium suction pipe 5.
A discharge pipe 6 is open, and a suction valve 7 and a discharge valve 8 are provided here. Furthermore, the pistons 3^, 3B are attached with tM1 drives 81!114^, 4B. This electromagnetic drive machine horizontal 4A. 4B is a driver coil 11^, 111 that is S-mounted in a sleeve 10 made of a non-magnetic material coupled to the piston shaft 9.
1, and cylindrical magnetic yokes 12 and 13 arranged oppositely on the inner and outer peripheries of the driver coil (however, in the illustrated embodiment, the cylinder 2
(also serves as the inner cork 12), and a constant magnetic field magnet device consisting of a permanent magnet 14 interposed between the yokes 12 and 13. Further, the above-described driver coils 11A and 118 have opposite coil rotation directions, and the lead wires drawn out from each driver coil are connected to an external t-source 16 via a power supply terminal 15 provided in the case I. It is connected. Note that 17 is a spring member for holding the pistons 3A and 3B in their respective neutral positions in a stopped state. On the other hand, T! l source 16 is the fundamental wave generating circuit 1B. Superimposed wave generation circuit 19. Equipped with 20jr addition and expansion circuits. here,
The fundamental wave generating circuit I8 outputs a fundamental wave signal with a frequency corresponding to the reciprocating period of the compressor, and the superimposed wave generating circuit 19 outputs a superimposed wave signal having a higher frequency and an extremely small amplitude than the fundamental wave. , these fundamental wave and superimposed wave signals are amplified by the summing amplifier circuit 20 and sent to the driver coil IIA, 1 of the compressor.
Supply power to 1B and excite it. The waveforms of the fundamental wave and superimposed wave mentioned above are shown in Figure 2. In such Yokonai, electric R1G
The driver coil 11A. When AC current is supplied to 11B and WJJ magnetization is performed, an alternating electromagnetic force is generated between the constant magnetic field and the Lareming law, and the piston 3 receives this electromagnetic force.
A and 3B reciprocate in opposite directions inside cylinder 2 with a phase difference of 180 degrees. The reciprocating motion of the piston is described in the aforementioned Japanese Patent Application Laid-Open No. 61-210276, and its explanation will be omitted here. By the way, the driver coil 11 is powered by electric power *t6.
^, 1 generated by excitation of IIB! The magnetic force consists of a large electromagnetic force corresponding to the frequency of the fundamental wave mentioned above, and a slight excitation of high frequency waves by superimposed waves. and,
Piston 3A. 3B is driven to reciprocate inside the cylinder 2 at a period corresponding to the frequency of the fundamental wave, and at the same time, during the entire stroke of the piston including the top and bottom dead center of the reciprocating movement, a small wave with a high frequency due to superimposed waves is generated. Excitation force will be applied. The amplitude of the superimposed wave is selected to be sufficiently small compared to the fundamental wave so that this excitation force does not affect the basic piston reciprocation of the compressor. As a result, even at the vertical dead center position at the end of the stroke during the reciprocating stroke of the piston, the pistons 3A and 3B do not come to a completely stationary state. Therefore, even if there is a mechanical contact between the cylinder 2 and the pistons 3A and 3B, there is still 3% static between them! 11 force is not applied, and only the dynamic frictional force with extremely small resistance acts, and as a result, the frictional resistance force that acts between the pistons 3^, 3B and the cylinder 2 due to the reciprocating motion of the compressor is minimized. It can be suppressed. Moreover, this causes almost no difference in frictional force between the pair of pistons 3^ and 38,
Both pistons have a predetermined phase difference (180 degrees). It reciprocates stably while maintaining the stroke amplitude. Although the illustrated example shows a general gas compressor, the present invention can also be applied to a reverse Stirling cycle refrigerator configured by combining this compressor with a displacer that serves as a separate expansion cylinder. [Effects of the Invention] As described above, the excitation method of the electromagnetically driven reciprocating compressor according to the present invention provides the following effects. (1) The friction acting between the piston and cylinder, including the vertical dead center position at the end of the stroke during the reciprocating stroke of the piston, is always I! ! It is possible to maintain a state of dynamic friction with low frictional resistance. (2) As a result, the difference in frictional force between a pair of pistons installed in a single cylinder is minimized, making it possible to stabilize compressor operation, maintain performance, and reduce generated vibrations.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an embodiment of the present invention, and Fig. 2 shows the fundamental wave of the excitation t current. This is a waveform diagram of superimposed waves. In the figure, 2: cylinder, 2a = compression space, 3A, ae: piston, 4A, 48: it magnetic drive a mechanism, IIA, IIB: driver coil, 14: permanent magnet, 16: t source, ts: i book Wave generation circuit, 19: Superimposed wave generation circuit. −． i')

Claims (1)

[Claims] 1) A pair of pistons are arranged facing each other on both sides of a single cylinder with both ends open, with a compression space for the working medium in between, and a driver coil coupled to each piston is arranged within the magnetic field of a constant magnetic field magnet device. , and for an electromagnetically driven reciprocating compressor in which the piston is driven by alternating current excitation of each driver coil with a phase difference of 180 degrees, the basic frequency corresponding to the reciprocating operation of the compressor is An excitation method for an electromagnetically driven reciprocating compressor, characterized in that the driver coil is excited by an alternating current in which a high frequency wave having a higher frequency and smaller amplitude than the fundamental wave is superimposed on the wave.