JP2019146277A - Linear motor and compressor mounted with the same - Google Patents

Abstract

To provide a linear motor capable of efficiently operating with two drive frequencies and a compressor mounted with the same.SOLUTION: A linear motor comprises: a first movable part having one of a permanent magnet and a coil; a second movable part having the other of the permanent magnet and the coil; a stationary part; a first spring connected between the first movable part and the second movable part; and a second spring connected between the second movable part and the stationary part. The first movable part and the second movable part reciprocate in approximately the same direction. The linear motor performs a low range mode supplying an AC current of a frequency in the vicinity of a low range side resonance mode frequency and a high range mode supplying an AC current of a frequency in the vicinity of a high range side resonance mode frequency.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a linear motor and a compressor equipped with the linear motor.

As a technique related to the present invention, for example, Patent Document 1 is cited.
Patent Document 1 includes a reference assembly having a cylinder and a resonance assembly that is displaced with respect to the reference assembly. The reference assembly and the shell 1 are connected by a spring 9, and the reference assembly and the resonance assembly are connected by a resonance spring 3. A sexual movement system is disclosed (paragraphs 0003-0005, FIG. 1, FIG. 2, etc.). There is a disclosure that the function of the brake spring 9 is to minimize the transmission of vibrations caused by the operation of the resonant assembly.

  Further, Patent Document 1 discloses a first balancing means 30 that connects the shell 1 and the reference assembly 20, a resonance spring 3 that connects the reference assembly 20 and the resonance assembly 10, and a second that connects the shell 1 and the resonance assembly 10. The balance means 40 is disclosed, and attention is paid to the relationship between the elastic coefficient (spring constant) KS of the first balance means 30 and the elastic coefficient KB of the second balance means 40 (paragraph 0024, FIG. 8, etc.). ).

JP-T-2004-503717

Patent Document 1 does not disclose a specific technical idea regarding the relationship between the elastic coefficient of the braking spring 9 and the elastic coefficient of the resonance spring 3 or the drive control of the compressor based on the relationship between such elastic coefficients. . Patent Document 1 is for suppressing the vibration of the compressor. In this case, in order to suppress the transmission of vibration to the shell 1, the spring constant of the spring 9 is small, that is, the spring 9 is set soft. It is normal.
If it comprises like patent document 1, the room for improvement remains about ensuring the frequency area | region in which resonance control is possible.

  In view of the above circumstances, the present invention provides a first movable part having one of a permanent magnet or a coil, a second movable part having the other of the permanent magnet or the coil, a fixed part, and the first movable part. A first spring that connects the second movable part, and a second spring that connects the second movable part and the fixed part, the first movable part and the second movable part being A linear motor that reciprocates in substantially the same direction, wherein a low-frequency mode in which an alternating current having a frequency in the vicinity of a low-frequency resonance mode frequency is passed through the coil, and an alternating current having a frequency in the vicinity of a high-frequency resonance mode frequency are applied to the coil. And a high-frequency mode that flows in

ADVANTAGE OF THE INVENTION According to this invention, the linear motor which can perform resonance control effectively, and the compressor carrying this can be provided.
Problems, configurations, and effects other than those described above will become apparent from the description of the following examples.

Schematic of the linear motor of Example 1 The figure which drawn the linear motor concerning Example 1 as a spring mass damper system The figure which shows the frequency response characteristic of the transfer function from the electric current which flows through the coil of Example 1 to the displacement amount of the 1st movable part. The figure which shows the frequency response characteristic of the transfer function from the electric current which flows through the coil of Example 1 to the displacement amount of the 2nd movable part. The figure which shows the basic structure of the compressor of Example 2. Frequency response characteristic diagram regarding the relative displacement of the two movable parts of Example 2 Displacement time waveform of Example 2 (drive frequency = f _L ) Displacement time waveform of Example 2 (drive frequency = f _H ) Frequency response characteristic diagram regarding first moving part displacement amount of Comparative Example 1 Frequency response characteristic diagram regarding the second movable part displacement amount of Comparative Example 1 Frequency response characteristic diagram regarding displacement of two movable parts of Comparative Example 2 Displacement time waveform of Comparative Example 2 (drive frequency = f _H )

  Hereinafter, each embodiment of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to the configuration of each embodiment described in detail below. The various components of the present invention do not necessarily have to be independent of each other. A plurality of components are formed as a single member, and a single component is formed of a plurality of members. That a certain component is a part of another component, a part of a certain component overlaps with a part of another component, and the like.

[Linear motor 100]
FIG. 1 is a schematic diagram of a linear motor 100 according to the present embodiment, and FIGS. 2A and 2B are diagrams illustrating the linear motor 100 according to the present embodiment as a spring mass damper system. The linear motor 100 includes a first movable part 1, a second movable part 2, a fixed part 3, a permanent magnet 4, a yoke 6 (6a, 6b) that is a magnetic body, and a coil 5 (5a, 5) wound around the yoke 6. 5b), having a first spring 10, a second spring 11 and a damping part 12.

The first movable part 1 has a permanent magnet 4 that can face the coil 5, and is connected to the second movable part 2 via a first spring 10 and a damping part 12.
The second movable part 2 has a coil 5 and a yoke 6 and is connected to the fixed part 3 via a second spring 11. Each of the coils 5 is opposed to each other with the first movable part 1 interposed therebetween.
The first movable portion 1 and the second movable portion 2 can reciprocate in substantially the same direction with respect to the fixed portion 3.
The fixing unit 3 may be a housing of the linear motor 100, for example, or may be the ground separately from the linear motor 100, for example. One end of the second spring 11 is connected to the fixed portion 3.

  The second movable portion 2 is connected to the other end of the second spring 11. With respect to the second movable part 2, one end of the first spring 10 and the damping part are arranged on the opposite side of the second spring 11 in the extending direction (the vertical direction in the drawing in FIG. 1) across the second movable part 2. One end of 12 is connected. The other end of the first spring 10 and the other end of the damping part 12 are connected to the first movable part 1. The first movable part 1 and the second movable part 2 can reciprocate in the substantially extending direction of the first spring 10 and the second spring 11.

The linear motor 100 can give reciprocating power to the second movable part 2 by an AC magnetic field that can be generated by passing an AC current through the coil 5. The 1st movable part 1 can receive reciprocating power by reaction of this reciprocating power.
The magnetization direction of the permanent magnet 4 is the left-right direction in FIG. Further, the closed loop of the magnetic field generated when a current flows through the coil 5 is in the plane of FIG. Therefore, an attractive force or a repulsive force is generated between the first movable part 1 and the second movable part 2 by the current flowing through the coil 5. In the linear motor 100 according to the present embodiment, the distance between the two movable parts 1 and 2 can be vibrated by passing an alternating current through the coil 5. The frequency of the alternating current that can be changed by the control is defined as an operating frequency fop. 1 may be the gravitational direction, but it is not necessarily coincident with the gravitational direction, and either the left-right direction may be parallel to the gravitational direction. In this case, you may provide another elastic body which supports the 2nd movable part 2 with respect to the ground etc.

  When the centroid of the permanent magnet 4 is observed from a direction perpendicular to the paper surface in FIG. 1 while the linear motor 100 is stopped, the centroid of the permanent magnet 4 is located below or above the centroid of the yoke 6. be able to. By doing so, reciprocating power can be effectively generated when the linear motor 100 is started.

The linear motor 100 has a normal range of the frequency of the alternating current flowing through the coil 5. This range may vary depending on the application of the linear motor 100. For example, in the case of a compressor described later, if it is a small one mounted on a refrigerator, 10 Hz to 100 Hz is easily used. As will be described below, it is preferable that both of the resonance mode frequencies of the linear motor 100 of the present embodiment, which is a two-inertia system, fall within this numerical range. In this way, the linear motor 100, and the low frequency mode to drive at a low frequency side resonant mode frequency f _L vicinity of the alternating current, the high-frequency mode of driving at a high frequency side resonant mode frequency f _H vicinity of the alternating current And can be executed separately.

[Resonant mode frequency of two-inertia system]
The linear motor 100 is a two-inertia system in which the first movable part 1 and the second movable part 2 can be displaced with respect to the fixed part 3. That is, the first movable part 1 can vibrate with respect to the fixed part 3 via the vibration of the second spring 11, and can vibrate with respect to the second movable part 2 via the first spring 10. It is. Further, the second movable part 2 can vibrate with respect to the fixed part 3 via a combined spring of the first spring 10 and the second spring 11. The vibration directions of the first movable part 1 and the second movable part 2 are substantially the same direction.
Such a linear motor 100 has two resonance modes. The resonance mode frequencies f _L and f _H (f _L <f _H ) can be derived by the following formula 1.

In order to simplify the explanation, the resonance mode frequency in the non-attenuating system ignoring the attenuation coefficient c ₁ of the attenuation unit 12 is clearly shown, but the attenuation coefficient c ₁ may be zero or non-zero. The main points are maintained. Here, the spring constant of the first spring 10 is k ₁ , the spring constant of the second spring 20 is k ₂ , the first movable part mass is m ₁ , and the second movable part mass is m ₂ . The angular velocity ω ₁ obtained from the first spring constant and the first movable part mass, the angular velocity ω ₂ obtained from the second spring constant and the second movable part mass, and the mass ratio μ of the movable part are as shown in Equation 2 below. It is. Here, when calculating by adding a part or all of the mass of the spring connected to the mover to m1 and m2, the accuracy becomes higher. For example, 1/3 of the mass of the first spring 10 can be included in m1. Further, m2 can include all of the mass of the first spring 10 and 1/3 of the mass of the second spring 11.

In this example, when k ₁ = 50 N / mm, k ₂ = 300 N / mm, m ₁ = 0.5 kg, and m ₂ = 4 kg, the resonance mode frequencies are 38.3 Hz and 57.3 Hz.
In this embodiment, for example, f _L and f _R can be brought close to each other by making ω ₁ and ω ₂ relatively close to each other, preferably matched. When (f _R / f _L ) is made close to 1 in this way, the resonance mode frequencies can be made closer to each other. Specifically, it is preferable to set each parameter so that the relationship of the following formula 3 is established.

Here, A is 0.6 or more and 1.4 or less, preferably 0.8 or more and 1.2 or less, more preferably 0.9 or more and 1.1 or less. By housing the value A in such upper and lower limit range, as described later, while the close to each other resonant mode frequency of the two-inertia, to be a low band side resonance frequency f _L to a certain extent higher value it can.

Here, in general, it is preferable that the linear motor 100 has a movable part (first movable part 1 in the present embodiment) that reciprocates greatly with respect to the ground so as to have a smaller mass than the other movable part. For this reason, when m _k <m _l , it is preferable that k _k <k _l (subscripts k and l are one and the other is 2).

In addition, as a usage of the linear motor 100, when it is desired to use a very low output mode and a very high output mode separately, the value of (f _R / f _L ) may be set to a high value. Can be designed according to various applications, is considered to be large devices to a super 20 or less _(f R _/ f _L).

[Displacement of moving parts]
The positive direction of force and displacement is assumed to be upward in the drawing in FIG. The electromagnetic force F generated by passing a current through the coil 5 acts on the first movable portion 1, and the second movable portion 2 has the same magnitude and opposite reaction force as the electromagnetic force F. . Hereinafter, it is assumed that the displacement amount of the first movable portion 1 is x ₁ , the displacement amount of the second movable portion 2 is x ₂ , and the attenuation constant c ₁ is 0.1.

FIG. 3 is a diagram showing the frequency response characteristics of the transfer function from the current flowing through the coil 5 to the displacement x _{1 of} the first movable part 1, and FIG. 4 is the displacement amount of the second movable part 2 from the current flowing through the coil 5. is a diagram showing the frequency response characteristic of the transfer function up to x _2.
The amount of displacement of the movable part 1 and 2 respectively, with a large peak at a resonant mode frequency _{f L} and _{f H.} The first movable part 1 has an anti-resonance point of the gain is greatly reduced during the resonant mode frequencies f _L and f _H. Looking at the phase relationship between the first movable part 1 and the second movable part 2, it is in the same phase in the vicinity of the resonance mode frequency f _L on the low frequency side or lower, and exceeds the antiresonance point of the movable part 1. After that, the phase is reversed.

Linear motor 100 according to this embodiment, the frequency of the current flowing through the coil 5, to a mode in a range including a resonant mode frequency f _L of the low-frequency side, the range including a resonant mode frequency f _H of the high-frequency side Has a mode. In the former, the first movable part 1 and the second movable part 2 have the same phase relationship, and the latter has the opposite phase relationship. That is, the linear motor 100 according to the present embodiment has two operation modes in which the two movable parts 1 and 2 operate in the same direction and in the opposite direction. That is, in the low frequency mode, the two movable parts 1 and 2 operate in the same direction, and in the high frequency mode, the two movable parts 1 and 2 operate in the opposite directions. Thus, since the operation directions of the movable parts 1 and 2 in the high-frequency mode in which vibration is likely to increase are in opposite phases, generation of vibration can be suppressed.

  The configuration of the present embodiment can be the same as that of the first embodiment except for the following points. The present embodiment relates to a compressor 200 having a linear motor 100. FIG. 5 is a longitudinal sectional view of the compressor 200. The compressor 200 includes a linear motor 100, a piston 21, a cylinder case 22, a cylinder chamber 23, a suction port 24, and a discharge port 25.

  The linear motor 100 may have the same configuration as that of the first embodiment, and may further include coils 5c and 5d and yokes 6c and 6d. In the present embodiment, the first movable portion 1 has a permanent magnet 4, a piston 21, and a mover constituting material 27. The second movable part 2 includes a coil 5, a yoke 6, and a cylinder case 22.

  The suction port 24 and the discharge port 25 are each provided with a known suction valve (not shown) and a discharge valve (not shown), and are connected to a suction pipe (not shown) and a discharge pipe (not shown), respectively. Is done. Each of the suction valve and the discharge valve opens and closes when the pressure difference generated before and after the valve exceeds (is below) a set value. First, when a one-way current flows through the coil 5 with the intake valve closed, and the piston 21 moves downward in FIG. 7, the volume of the cylinder chamber 23 increases and the pressure in the cylinder chamber 23 decreases, and the intake The valve opens and working fluid (not shown) flows into the cylinder chamber 23. Next, when a reverse current is passed through the coil 5 with the discharge valve closed, the piston 21 moves upward, the volume of the cylinder chamber 23 decreases, the pressure in the cylinder chamber 23 increases, and the discharge valve The working fluid having a high pressure is discharged from the open discharge port 25.

FIG. 6 shows the relative displacement between the first movable part 1 and the second movable part 2 when k ₁ , k ₂ , m ₁ and m ₂ are set to the same values as in the first embodiment. Δx is a frequency response characteristic from the current flowing through the coil 5 to Δx. At this time, the resonance mode frequency _{f L} of the lower frequency 38.3Hz, high frequency side _{f H} is 57.3Hz. Here, m ₂ includes all of the masses of the suction valve and the discharge valve provided in the cylinder case 22 and part or all of the mass of the pipes attached to these valves. How much of the mass of the pipe is included in m ₂ depends on the installation mode of the pipe. It will be apparent to those skilled in the art that the weight should be determined in consideration of how much weight is applied to the cylinder case 22.

According to FIG. 6, there are two low compression mode frequencies f _L and high resonance mode frequencies f _H that generate a large compressive force in the cylinder chamber 23. FIG. 7 shows the displacement of the first movable part 1 (displacement of the piston 21) x ₁ , the displacement of the second movable part 2 (displacement of the cylinder case 22) x ₂ when the driving frequency is f _L , and relative It is a figure which shows the time development of displacement amount (DELTA) x. The first movable part 1 and the second movable part 2 vibrate in the same phase, and the vibration amplitude of the first movable part 1 is larger than that of the second movable part 2. Δx corresponds to an amount of change from the initial value of the height of the space of the cylinder chamber 23, and means that a higher compressive force can be obtained with a smaller current as the peak height is higher. Therefore, the relative displacement amount Δx vibrates and the working fluid in the cylinder case 22 can be compressed.

FIG. 8 shows the displacement of the first movable part 1 (displacement of the piston 21) x ₁ and the displacement of the second movable part 2 (displacement of the cylinder case 22) x when the drive frequency is f _H in this embodiment. ₂ and the time evolution of the relative displacement amount Δx. The first movable part 1 and the second movable part 2 vibrate in opposite phases, and the vibration amplitude of the first movable part 1 is larger than that of the second movable part 2. Therefore, the relative displacement amount Δx vibrates and the working fluid in the cylinder chamber can be compressed.

  That is, by making the relationship between the two spring constants and the masses of the two movable parts as described above in the first embodiment, the two resonance mode frequencies are close to each other. By setting the operation mode in which each resonance mode frequency is a drive frequency, it is possible to provide an efficient compressor 200 that can obtain a large pressure with a small electric power.

  By the way, the anti-resonance point exists between two resonance mode frequencies. Further, since the compressor 200 compresses the fluid, a spring constant due to the fluid is added to the system, so that the two resonance mode frequencies transition to the high frequency side. Therefore, when switching from the high frequency mode to the low frequency mode, switching from the driving frequency to below the low frequency resonance mode frequency when the spring constant by the fluid is 0, and then increasing the frequency, It is easy to avoid driving at the resonance point, which is preferable.

(Comparative Example 1)
Comparative Example 1 relates to a linear motor. As parameters, k ₁ = 50 N / mm, k ₂ = 0.3 N / mm, m ₁ = 0.5 kg, m ₂ = 4 kg, that is, a linear motor in the case of A = 33.3. At this time, the resonance mode frequencies are f ₁ = 1.3 Hz and f ₂ = 53.4 Hz.
In Comparative Example 1, the second spring constant is small, and f _L is sufficiently smaller than the lower limit of the operating frequency.

9 and 10 show the frequency response characteristics of the transfer function from the current to the displacement amounts x ₁ and x ₂ of the movable parts ₁ and ₂ . It can be seen that the displacement amounts of the movable parts 1 and 2 both have large peaks at the resonance mode frequencies f _L and f _H. Resonant mode frequency f _L of the low-frequency side is very low, usually out of the operation mode.

In addition, the movable part 1 has an anti-resonance point at which the gain greatly decreases in the vicinity of the resonance mode frequency f _L on the low frequency side. Looking at the phase relationship between the movable parts 1 and 2, the phase is reversed after the antiresonance point of the movable part 1 is exceeded. In Comparative Example 1, the linear motor is in the frequency range of normal driving, among the resonant mode frequencies, only f _H of the high-frequency side belongs, the two movable parts 1 operates in the opposite direction.

(Comparative Example 2)
Comparative Example 2 relates to a compressor. FIG. 11 is a diagram showing frequency response characteristics from the current flowing through the coil 5 to Δx, using the parameters of Comparative Example 1. In FIG. At this time, the resonance mode frequency f _L on the low frequency side is 1.3 Hz, and the resonance mode frequency f _H on the high frequency side is 53.4 Hz.
The frequency range compressor is normally driven, of the resonant mode frequencies, only high-frequency side resonant mode frequency f _H belongs.

FIG. 12 is a diagram showing the piston displacement x ₁ , the cylinder displacement x ₂ , and the relative displacement amount Δx when the drive frequency is f _H. The second movable part 2 hardly vibrates, and the vibration amplitude of the first movable part 1 is approximately equal to the distance between the two movable parts. When the compressor of Comparative Example 2 is to be resonantly driven at a frequency substantially lower than f _H , the compressor must be lowered to a frequency at which operation of the compressor is difficult, so that low output can be effectively performed. Have difficulty.

  The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... 1st movable part 2 ... 2nd movable part 3 ... Fixed part 4 ... Permanent magnet 5,5a * 5b * 5c * 5d ... Coil 6,6a * 6b * 6c * 6d ... Yoke 10 ... First spring DESCRIPTION OF SYMBOLS 11 ... 2nd spring 12 ... Damping part 21 ... Piston 22 ... Cylinder case 23 ... Cylinder chamber 24 ... Suction port 25 ... Discharge port 27 ... Moving part component

Claims (5)

A first movable part having one of a permanent magnet or a coil;
A second movable part having the other of a permanent magnet or a coil;
A fixed part;
A first spring connecting the first movable part and the second movable part;
A second spring connecting the second movable part and the fixed part,
A linear motor in which the first movable part and the second movable part reciprocate in substantially the same direction,
A low-frequency mode in which an alternating current having a frequency near the low-frequency resonance mode frequency is passed through the coil;
And a high frequency mode in which an alternating current having a frequency in the vicinity of the high frequency side resonance mode frequency is passed through the coil. The mass of the first movable part is m ₁ , the mass of the second movable part is m ₂ , the spring constant of the _first spring is k ₁ , and the spring constant of the _second spring is k ₂ . The linear motor according to claim 1, wherein the following relational expression 1 is satisfied.

However, A is 0.6 or more and 1.4 or less. The mass of the first movable part is m ₁ , the mass of the second movable part is m ₂ , the spring constant of the _first spring is k ₁ , and the spring constant of the _second spring is k ₂ . _2. The linear motor according to claim 1, wherein relational expression m ₁ <m ₂ and relational expression k ₁ <k ₂ hold.   The linear motor according to any one of claims 1 to 3, wherein reciprocating directions of the first movable part and the second movable part in the high frequency mode are opposite to each other. A compressor comprising the linear motor according to any one of claims 1 to 4 and compressing a fluid,
When switching from the high frequency mode to the low frequency mode, the frequency of the current flowing through the coil is switched below the low frequency resonance mode frequency when the spring constant by the fluid is 0, and then the frequency is increased. Compressor characterized by.

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