KR100819609B1 - Linear compressor - Google Patents

Abstract

A linear compressor is provided to compensate motion transferred to a shell from a moving part by elastic elements such as mechanical springs for reducing vibration and noise, thereby achieving stable operation of the linear compressor. A linear compressor includes a shell(11), a fixing part(13) mounted in the shell and having a mass(mb), a moving part(12) reciprocating in the fixing part to compress fluid and having a mass(ma), a first elastic element(14) connecting the moving part to the shell and having an elastic coefficient(ka), second elastic elements(15,16) connecting and supporting the fixing part to the shell and having an elastic coefficient(kb), and a third elastic element(17) connecting the fixing part to the moving part and having an elastic coefficient(kc). The first and second elastic elements satisfy a formula: kb/ka=mb/ma.

Description

Linear Compressor {LINEAR COMPRESSOR}

1 illustrates an example of a conventional vertical linear compressor.

2 illustrates a linear compressor according to an embodiment of the present invention.

3 is a diagram schematically illustrating a vibration system of a linear compressor according to an embodiment of the present invention.

4 is a graph showing the correlation between the elastic modulus of the first and second elastic bodies of the linear compressor according to the present invention and the transmission force of the shell.

The present invention relates to a linear compressor. In particular, it is related with the linear compressor provided with an elastic body in order to prevent a shell from vibrating by the operation of a movable part.

In general, a compressor is a mechanical device that increases pressure by receiving power from a power generator such as an electric motor or a turbine to compress air, refrigerant, or various other working gases. It is widely used throughout.

These compressors can be classified into reciprocating compressors for compressing refrigerant while linearly reciprocating inside the cylinders by forming a compression space in which the working gas is absorbed and discharged between the piston and the cylinder. And a rotary compressor for compressing the refrigerant while the roller is eccentrically rotated along the inner wall of the cylinder so that a compression space for absorbing and discharging the working gas is formed between the eccentrically rotating roller and the cylinder. As a scroll compressor that compresses the refrigerant while the rotating scroll rotates along the fixed scroll to form a compressed space in which the working gas is absorbed and discharged between the orbiting scroll and the fixed scroll. Divided.

Recently, among the reciprocating compressors, in particular, the piston is directly connected to the reciprocating linear motion drive motor, so that there is no mechanical loss due to the motion conversion to improve the compression efficiency as well as a simple linear compressor has been developed a lot.

Normally, a linear compressor is configured to suck and compress a refrigerant and then discharge the refrigerant while the piston moves in a closed shell to reciprocate linearly inside the cylinder by a linear motor, where the linear motor is a permanent magnet between the inner and outer stators. The permanent magnets are driven to linearly reciprocate by mutual electromagnetic force, and as the permanent magnets are driven in a state connected to the pistons, the pistons reciprocate linearly inside the cylinders to inhale, compress, and discharge the refrigerant. do.

At this time, the piston is intentionally linear reciprocating movement by the drive of the motor, while the other parts inside the shell does not intentional movement except the elastic body. Therefore, in the following, the moving part, the part connected to the piston and reciprocating together with the piston, is expressed as a stationary part. The stationary part and the movable part are connected to the shell by an elastic body inside the shell. Hereinafter, the vibration system of the linear compressor is simplified and expressed as a shell, a movable part, a fixed part, and an elastic body.

In the conventional linear compressor, the fixed part is displaced by the movement of the movable part, and a force is transmitted to the shell connected to the fixed part by the elastic body, and vibration is generated in the shell. Vibration of the shell is undesirable because it not only reduces the stability of the linear compressor, but also generates noise.

1 illustrates an example of a conventional vertical linear compressor. The movable portion and the fixed portion, the fixed portion and the shell, the movable portion and the shell are all connected to the shell by an elastic body, and when the movable portion is driven by a motor, the three elastic bodies are displaced simultaneously. At this time, the first elastic body 20 and the second elastic body 21 satisfy the following relational expression.

식(1)

Formula (1)

At this time, Ma is the mass of the movable part, and the movable part includes the piston 1, the actuator 4, and the magnet member 5. Mb is the mass of the fixed part, and the fixed part includes a cylinder 2, a cylinder block 2a, and a cylinder head 3.

In addition, the third elastic body 22 included in the linear compressor is connected to the movable part and the fixed part, and is a part for increasing the efficiency of the linear compressor by causing the movable part to resonate during operation. However, in a compressor in which the first elastic body 21 and the second elastic body 20 satisfy Equation (1), k _c must be negative for the third elastic body 22 to satisfy the resonance condition. Therefore, there is a problem that can not use the most widely used and convenient mechanical spring control.

The present invention has been made to solve the above problems, an object of the present invention is to provide a linear compressor having an elastic body for reducing the vibration transmitted to the shell by the movement of the movable portion.

In addition, an object of the present invention is to provide a linear compressor in which all of the elastic body for reducing vibration can be implemented by a mechanical elastic body.

The present invention provides a shell, a fixed portion having a mass M _b installed inside the shell, _a movable portion having a mass M _a for reciprocating the inside of the fixed portion at a frequency ω and compressing a fluid, and an elastic modulus connecting the movable portion and the shell is k _a . A first elastic body, a second elastic body having an elastic modulus of k _b connected to and supported by the fixing part to the shell, and a third elastic body having an elastic modulus of k _c connecting the fixed part and the movable part; :

It provides a linear compressor characterized in that to satisfy. Through this structure, the force transmitted to the shell by the movement of the movable part can be canceled, and the vibration of the shell can be reduced.

In addition, the elastic modulus of the third elastic body is

It is an object of the present invention to provide a linear compressor characterized by satisfying the following. Through this configuration, the linear compressor can be operated under resonance conditions.

In addition, the present invention has a frequency ω, where:

It provides a linear compressor characterized in that to satisfy. Through this configuration, it is possible to implement a linear compressor in which k _c is always positive. Therefore, a 3rd elastic body can be made into the mechanical elastic body which is easier to control than a gas elastic body.

Moreover, this invention provides the linear compressor characterized by the frequency ω being the resonant frequency ω _cr of a movable part.

The present invention also provides a linear compressor, wherein the third elastic body is a mechanical elastic body.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2 is a diagram schematically showing a vibration system of a linear compressor according to an embodiment of the present invention.

,

이다. 여기서 제3 탄성체의 탄성 계수는 가동부의 운동에 의한 유체의 압축시에 발생하는 유체의 탄성까지 고려한 값이다. 즉, 제3 탄성체의 탄성 계수와 유체의 압축에 의한 탄성 계수의 합을 편의상 탄성 계수 k_c로 나타낸다. The vibration system of the linear compressor consists of a shell 11, a movable part 12, a fixing part 13, a first elastic body 14, a second elastic body 15 and 16 and a third elastic body 17. A variable, the displacement of the movable portion x _a, and the displacement of the state x _b, the elastic modulus of the mass of the mass of the movable portion M _a, fixing M _b, a first elastic member (14) k _a, the second elastic member used in the vibration system analysis The force applied to the movable portion by the elastic modulus 0.5 · kb of the (15, 16), the elastic modulus kc of the third elastic body 17, the motor parameters L, R, α, V, the motor output Fm, and the first elastic body 14 Fa, the force applied to the fixed portion by each of the second elastic bodies 15 and 16, 0.5 · Fb, and the absolute coordinate system N And unit vector of each

,

to be. Herein, the elastic modulus of the third elastic body is a value considering the elasticity of the fluid generated when the fluid is compressed by the motion of the movable portion. That is, the sum of the elastic modulus of the third elastic body and the elastic modulus due to the compression of the fluid is represented by the elastic modulus k _c for convenience.

The shell 11 has a considerably higher resonance frequency than the operating frequency. Therefore, the shell 11 is assumed to be a rigid body and the vibration system is analyzed. In addition, generalized coordinates of x _a (t), x _b (t), and q (t) are required to analyze the system by the movable part, the fixed part, and the current.

First, using the preceding variables to find the kinetic energy T of the vibration system,

to be.

Also the elastic energy V,

to be.

In addition, the attenuation energy R,

to be.

Also, if we find the virtual δW,

to be.

Also the Lagrange equation for the vibration system,

to be.

Substituting each of the energy equations T, V, R, and δW derived above into the Lagrange equation,

Formula (2)

Formula (3)

식(4)

Formula (4)

It can be represented as.

When the above expressions (2) and (3) are expressed as determinants,

Formula (5)

It is expressed as

Since the excitation source F _m is a harmonic function with F _m = F ₀ e ^jwt , the displacements of the movable part 12 and the fixed part 13 are x _a = X _a0 e ^iwt and x _b = X _b0 e ^{iwt, respectively.} Is expressed as the harmonic function of. Substituting the displacement represented by the harmonic function into equations (2) and (3) again,

Formula (6)

It can be represented as

Here, when X _a0 and X _b0 are calculated, it can be expressed as follows.

식(7)

Formula (7)

Where D = (k _a + k _{c ^{- m a · ω 2) ·}} (k b + k _c - _b · m ω ²⁾ -k ² _c to be.

The total transmission force F _s acting on the shell 11 is

식(8)

Formula (8)

to be.

Substituting the relation in equation (7) into equation (8),

Formula (9)

Becomes

At this time, when the force transmitted to the shell 11 is canceled out so that the net force becomes 0, the occurrence of vibration in the shell 11 can be reduced. Required to be zero the sum of the transfer force, to zero the molecule in formula (9), and because F ₀ and ω is always greater than or equal to zero during the operation of the linear compressor value, (-k · _a M _b k + _b M _a ) must be zero. Therefore, in order to cancel the transmission force of the shell 11 and reduce vibration, the mass of the movable part 12, the mass of the fixing | fixed part 13, the elastic modulus of the 1st elastic body 14, and the 2nd elastic bodies 15 and 16 are carried out. Modulus of elasticity of

식(10)

Formula (10)

Must satisfy

In addition, the linear compressor according to the embodiment of the present invention should have an elastic modulus in which the third elastic body 17 can resonate the movable part 12. The elastic modulus k _c of the third elastic body 17 can be expressed by the following determinant when the excitation circle F _m is 0 in the formulas (2) and (3).

의 형태로,

관계식을 이용하면, In other words,

In the form of,

Using relational expressions,

Becomes

Here, in order for the equation of [A] {X} = {0} to have a feasible solution, the determinant of the matrix [A] must be zero.

Therefore, the determinant of [K] is

Therefore, k _c is

식(11)

Formula (11)

At this time, when _{c c} is positive, the third elastic body 17 may be implemented as a general mechanical elastic body such as a helical spring. So if we substitute the condition k _c > 0,

Must be satisfied. In addition, considering the resonance condition of the movable part 12, the frequency ω should be ω _cr which is the resonance frequency of the movable part.

Based on the above conditions, we simulated the vibration system of the linear compressor. The vibration system of the linear compressor, the mass M of _a moving part (12), 0.6kg, and mass M _b of the decision section 13 that was to 5.0kg. At this time, when the elastic modulus k _a of the first elastic body 14 is 1440 N / m, the sum kb of the elastic modulus of the second elastic bodies 15 and 16 satisfying the formula (10) is 1440 * (5.0 / 0.6) Therefore, it becomes 12000 N / m.

If k _c satisfying Equation (11) is obtained under the above condition, k _c is a positive number, and thus the third elastic body 17 may be a mechanical spring that is easy to control and implement. Therefore, since the elastic modulus of the third elastic body 17 that satisfies the resonance condition in the conventional vertical linear compressor is negative, it was overcome by the mechanical spring.

4 is a graph showing the results of simulating k _a and k _b , which satisfy equation (7). Obtaining ka and kb, where the transmission force F _s delivered to the shell 11 becomes 0, is as follows.

case ka [N / m] kb [N / m] One 960 8,000 2 1,2000 10,000 3 1,440 12,000 4 1,560 14,000

At this time, the operating conditions were MK resonance conditions, and the operating frequency of the movable portion 12 was 50 Hz. This allows k _c to be calculated. k _c can be calculated by considering the elasticity of the fluid when the fluid is compressed by the movement of the movable part 12. The peak is also constrained by the motor parameter α.

The linear compressor provided by the present invention cancels the transmission force transmitted to the shell, thereby reducing noise and vibration.

In addition, the linear compressor provided by the present invention has an advantage that the elastic modulus of the elastic body provided to operate in the resonant operation condition is a positive number, and thus may be implemented by a mechanical spring.

In addition, the linear compressor provided by the present invention has an advantage that the transmission force transmitted to the shell is canceled, so that the linear compressor can be stably operated.

Claims (5)

Shell; A fixing part having a mass M _b installed inside the shell; _A movable part having a mass M _a for reciprocating the inside of the fixed part at a frequency ω and compressing the fluid; A first elastic body having an elastic modulus k _a that connects the movable part to the shell; A second elastic body having an elastic modulus of k _b connecting the fixing part to the shell; And And a third elastic body having an elastic modulus of k _c connecting the fixed part and the movable part. The frequency ω is

Linear compressor, characterized in that to satisfy. Shell; A fixing part having a mass M _b installed inside the shell; _A movable part having a mass M _a for reciprocating the inside of the fixed part at a frequency ω and compressing the fluid; A first elastic body having an elastic modulus k _a that connects the movable part to the shell; A second elastic body having an elastic modulus of k _b connecting the fixing part to the shell; And And a third elastic body having an elastic modulus of k _c connecting the fixed part and the movable part. The elastic modulus of the third elastic body is

Satisfies the, and the linear compressor to resonate the movable portion. The method according to any one of claims 1 and 2, The first and second elastic bodies are

Linear compressor, characterized in that to satisfy. The method according to any one of claims 1 and 2, The frequency ω is a linear compressor, characterized in that ω _cr which is the resonance frequency of the movable part. The method according to any one of claims 1 and 2, The third elastic body is a mechanical elastic body.

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