WO2018037906A1

WO2018037906A1 - Compressor

Info

Publication number: WO2018037906A1
Application number: PCT/JP2017/028710
Authority: WO
Inventors: 高橋　慎一; 郁男江崎
Original assignee: 三菱重工サーマルシステムズ株式会社
Priority date: 2016-08-25
Filing date: 2017-08-08
Publication date: 2018-03-01
Also published as: JP2018031303A; EP3447296A1; EP3447296A4

Abstract

Provided is a compressor in which an appropriate pulsation frequency component of a fluid can be sufficiently reduced by a muffler while the performance of the compressor is ensured. A compressor 1 is provided with a compression mechanism 4 that compresses a refrigerant, and a muffler 10 that reduces pulsation of the refrigerant compressed by the compression mechanism 4. The muffler 10 is provided with: a muffler body 11 that takes refrigerant into the interior thereof from the compression mechanism; and a cover 12 that forms a cavity 120 with an outer periphery 11S of the muffler body 11, the cover 12 discharging the refrigerant taken in from the interior of the muffler body 11. A plurality of openings 11H passing through in the plate thickness direction are formed in the muffler body 11, separately from a discharge port 11P through which refrigerant passes into the cavity 120 from the interior of the muffler body 11. Due to the relationship between the speed of sound C, the cross-sectional area S of each of the openings 11H, the plate thickness L, and the volume V of the cavity 120, Helmholtz resonance arises in air masses 15 located inside the openings 11H leading into the cavity 120, whereby sound is absorbed.

Description

Compressor

The present invention relates to a compressor provided with a muffler for reducing pressure fluctuation (pulsation) of a compressed fluid.

A rotary compressor that constitutes an air conditioner or the like includes a compression mechanism that compresses refrigerant in a cylinder by rotation of a piston rotor, and a muffler that suppresses noise caused by pressure fluctuations of the compressed refrigerant.
As a muffler for a rotary compressor, a two-stage muffler composed of a first muffler and a second muffler is also employed (for example, Patent Document 1). The compressed refrigerant is discharged to the inside of the first muffler from the discharge port of the bearing to which the cylinder is fixed, and is further discharged from the first muffler into the second muffler through the discharge port of the first muffler. . Since the space in the first muffler and the space in the second muffler act as resistance corresponding to the space volume for the compressed refrigerant, the pulsation of the refrigerant is reduced by sequentially passing through the first muffler and the second muffler. The

JP 2014-173554 A

Even if a normal muffler or a two-stage muffler is installed in the compression mechanism, a sufficient pulsation reduction effect may not always be obtained for the frequency component of the pulsation of the compressed refrigerant.
In particular, in the case of a two-stage muffler, it is difficult to improve the rigidity by sufficiently taking the thickness of the muffler due to restrictions on weight and cost, so that the pressure wave of the pulsation of the refrigerant is likely to be radiated to the outside of the muffler.
If the opening area of the outlet of the muffler is reduced, pressure loss can be given to the refrigerant discharged from the muffler and pulsation can be reduced, but this leads to a reduction in the performance of the compressor. In particular, in the case of a two-stage muffler, since the pressure loss is large, there is a limit to reducing the opening area of the discharge port.

In view of the above, an object of the present invention is to provide a compressor capable of sufficiently reducing an appropriate pulsation frequency component of a fluid with a muffler while ensuring the performance of the compressor.

A compressor according to the present invention includes a compression mechanism that compresses a fluid, and a muffler that reduces pulsation of the fluid compressed by the compression mechanism. The muffler includes a muffler body that receives fluid from the compression mechanism inside, and the muffler body. A cover that discharges fluid received from the inside of the muffler body, and a discharge port through which the fluid passes from the inside of the muffler body into the cavity. Separately, a plurality of openings penetrating in the plate thickness direction are formed, and exist in the openings leading to the cavities based on the relationship between the sound velocity C, the sectional area S of each of the openings, the plate thickness L, and the volume V of the cavities. Sound absorption is performed when Helmholtz resonance is established with respect to the air mass.

In the compressor according to the present invention, it is preferable that the compression mechanism has a piston rotor provided on the rotating shaft and a cylinder in which the piston rotor is arranged, and the muffler body and the cover are arranged around the axis of the rotating shaft.

According to the present invention, as will be described in detail later, it is possible to obtain a pulsation reduction effect based on Helmholtz resonance while maintaining a pulsation reduction effect by a two-stage muffler that repeatedly discharges pulsation into the space. The motion of the air mass inside the small opening of the muffler body that causes Helmholtz resonance does not affect the main flow in the muffler, so the pulsation of the fluid is sufficiently reduced to absorb sound while ensuring the performance of the compressor. In other words, noise caused by fluid pressure fluctuations can be suppressed.
According to the present invention, it is possible to suppress the sound pressure from being emitted by the muffler as a sound source by reducing the pulsation, so that it is possible to suppress the noise even if the thickness of the muffler main body and the cover is thin. .

It is a longitudinal section of a rotary compressor concerning an embodiment of the present invention. It is a figure which shows typically the upper muffler shown in FIG. FIG. 3 is a partially enlarged view of FIG. 2. (A) And (b) is a figure for demonstrating Helmholtz resonance.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
A rotary compressor 1 shown in FIG. 1 sucks gas refrigerant in an accumulator (gas-liquid separator) (not shown) through

pipes

8 and 9 and compresses it by a compression mechanism 4.
The compressor 1 and the accumulator constitute a refrigeration cycle apparatus such as an air conditioner or a refrigerator, and are connected to a refrigerant circuit (not shown) through which the refrigerant circulates.

The compressor 1 is driven by a motor 2 as a power source, a rotating shaft 3 (crankshaft) rotated by a rotating driving force output from the motor 2, and a rotating driving force transmitted through the rotating shaft 3. A rotary compression mechanism 4,

mufflers

10 and 20 arranged around the rotation shaft 3, and a housing 5.
The

mufflers

10 and 20 suppress noise caused by the pulsation of the refrigerant compressed by the compression mechanism 4.

The housing 5 houses the motor 2, the rotating shaft 3, the compression mechanism 4, and the

mufflers

10 and 20, and is formed in a cylindrical shape.
The motor 2 includes a stator 2A that is fixed to the inner peripheral portion of the housing 5, and a rotor 2B that is disposed inside the stator 2A. The rotor 2B rotates relative to the stator 2A by energizing a coil 2C provided on the stator 2A.

The rotating shaft 3 is coupled to the rotor 2B and protrudes downward from the rotor 2B. The upper crankpin 3B is eccentric with respect to the axis of the main shaft 3A. And an eccentric lower crankpin 3C. The lower crankpin 3C is eccentric with respect to the axis of the rotary shaft 3 in a direction opposite to the upper crankpin 3B (180 °).
The upper crank pin 3 B is disposed in the upper cylinder 412 of the compression mechanism 4, and the lower crank pin 3 C is disposed in the lower cylinder 422 of the compression mechanism 4.

The compression mechanism 4 (FIG. 1) will be described.
The so-called twin rotary type compression mechanism 4 includes an upper compression mechanism 41, a lower compression mechanism 42, a partition plate 4A, and an upper bearing 6 and a lower bearing 7 that rotatably support the rotary shaft 3.
The partition plate 4 A partitions the inside of the cylinder 412 of the upper compression mechanism 41 and the inside of the cylinder 422 of the lower compression mechanism 42.

The upper compression mechanism 41 includes an upper piston rotor 411 provided on the upper crankpin 3B, an upper cylinder 412 in which the upper piston rotor 411 is disposed, and an upper muffler 10 disposed around the axis of the main shaft portion 3A. Has been.
The upper piston rotor 411 is fitted to the outer peripheral portion of the upper crankpin 3 B, and is turned in the upper cylinder 412 as the rotary shaft 3 rotates.
The refrigerant is sucked into the upper cylinder 412 through the pipe 8.

The upper bearing 6 has an abutting portion 6A that abuts against the upper end surface of the upper cylinder 412 and a cylindrical bearing portion that protrudes upward from the abutting portion 6A and is positioned around the axis of the rotary shaft 3 (main shaft portion 3A). 6B. The abutting portion 6 A is fixed to the inner peripheral portion of the housing 5.
An upper cylinder 412, an upper muffler 10, a lower cylinder 422, and a lower muffler 20 are integrally assembled to the upper bearing 6 with bolts 113.

The refrigerant sucked into the upper cylinder 412 is compressed in a space ahead in the rotational direction with respect to a blade (not shown) pressed against the outer peripheral portion of the rotating upper piston rotor 411. The compressed refrigerant is discharged into the upper muffler 10 through the discharge port 6P (FIG. 2) formed in the abutting portion 6A of the upper bearing 6, and further from the upper muffler 10 to the motor 2 in the housing 5. Is also discharged into the space below.

Similar to the upper compression mechanism 41, the lower compression mechanism 42 (FIG. 1) includes a lower piston rotor 421 provided in the lower crankpin 3C, a lower cylinder 422 in which the lower piston rotor 421 is disposed, and the axis of the main shaft portion 3A. And a lower muffler 20 disposed in the middle.
A gas refrigerant is sucked into the lower cylinder 422 through the pipe 9.

The lower bearing 7 has an abutting portion 7A that is abutted against the lower end surface of the lower cylinder 422, and a cylindrical bearing portion that projects downward from the abutting portion 7A and is located around the axis of the rotary shaft 3 (main shaft portion 3A). 7B.

The refrigerant sucked into the lower cylinder 422 is compressed as the lower piston rotor 421 turns. The compressed refrigerant is discharged into the lower muffler 20 through the discharge port (not shown) formed in the abutting portion 7A of the lower bearing 7 and into the inner space of the housing 5, and further, the abutting portion of the upper bearing 6 It passes through a notch 61A formed in 6A and an opening (not shown), and is discharged into a space below the motor 2 in the housing 5.

As described above, the refrigerant compressed by the upper compression mechanism 41 and the lower compression mechanism 42 is discharged into a space below the motor 2 in the housing 5. The refrigerant flows into a space above the motor 2 through a notch provided in the stator 2A and the rotor 2B, and is discharged to a refrigerant circuit through a discharge pipe 5A provided in the upper part of the housing 5.

The upper compression mechanism 41 and the lower compression mechanism 42 each discharge refrigerant with pressure fluctuation (pulsation) from the discharge port according to the turning cycle of the

piston rotors

411 and 421. The pulsations of the compressed refrigerant ejected to the

mufflers

10 and 20 through the discharge ports by the upper compression mechanism 41 and the lower compression mechanism 42 are reduced in the

mufflers

10 and 20, respectively.

The compressor 1 of this embodiment is characterized by the structure of the upper muffler 10.
First, the configuration of the upper muffler 10 (hereinafter referred to as the muffler 10) will be described with reference to FIGS.
The muffler 10 includes a muffler body 11 that forms a space 110 between the upper bearing 6 and the abutting portion 6A, and a cover 12 that forms a cavity 120 between the outer periphery 11S of the muffler body 11.
The muffler body 11 and the cover 12 are each formed from a metal material such as an aluminum alloy, for example, by deep drawing.

The muffler body 11 receives the compressed refrigerant compressed in the upper cylinder 412 (FIG. 1) and ejected from the discharge port 6P in the inner space 110, and reduces the pulsation of the compressed refrigerant. Since the space inside the muffler main body 11 acts as a resistance corresponding to the space volume for the refrigerant jetted into the muffler main body 11, the pulsation of the refrigerant is attenuated by the muffler main body 11.

The muffler main body 11 is arranged around the axis of the rotary shaft 3. A bearing 6B that supports the rotary shaft 3 is passed through an opening formed in the center of the flat surface of the muffler body 11. The peripheral portion of the opening corresponds to the inner peripheral end 111 of the muffler main body 11.
The muffler body 11 extends from the inner peripheral end 111 to the outside in the radial direction of the rotating shaft 3 with a predetermined diameter, and is formed in a substantially circular shape in plan view. The radially outer ends of the muffler body 11 are fastened to the upper bearing 6 by bolts 113 at a plurality of locations in the circumferential direction.

The dimensions and volume of the muffler body 11 can be determined as appropriate so as to match the audible frequency component of the pulsation of the compressed refrigerant. The same applies to the cover 12.

The muffler main body 11 is disposed on the abutting portion 6A, with a portion 11A extending radially outward from the inner peripheral end 111 positioned above the abutting portion 6A, and descending from the portion 11A toward the abutting portion 6A. 11B. The refrigerant ejected from the discharge port 6P is mainly sprayed onto the portion 11A.

In the place where the muffler main body 11 is fastened by the bolt 113, the shapes of the

portions

11A and 11B are slightly different from other places. The muffler body 11 is not limited to the one shown in FIG. 2 and can be formed in an appropriate shape. For example, the muffler body 11 may be formed in a dome shape. The same applies to the cover 12.

In the muffler body 11, a plurality of openings 11H are formed separately from the discharge port 11P and the discharge port 11P.
The discharge port 11P allows the refrigerant to pass from the inside of the muffler main body 11 into the cavity 120.
The discharge port 11P penetrates the portion 11A of the muffler main body 11 in the plate thickness direction. Further, a plurality of discharge ports are formed at intervals in the circumferential direction of the muffler body 11.
There is no particular restriction on the position of the discharge port 11P, but the phase angle of the discharge port 6P is different from that of the discharge port 6P so that the compressed refrigerant discharged from the discharge port 6P is not discharged from the muffler body 11 as it is. It is preferable that the discharge port 11P is formed at a position away from the discharge port 6P. As described later, this leads to a sufficient sound absorption effect utilizing Helmholtz resonance by introducing a refrigerant into each of the large number of openings 11H.
The number of discharge ports 11P, the opening area of each discharge port 11P, and the total opening area of the plurality of discharge ports 11P are determined in consideration of the balance between the pressure loss for reducing pulsation and the performance of the compressor 1 and the like. It has been. The same applies to the discharge port 12P of the cover 12.
In addition, the discharge port 11P can also be formed in an annular shape around the axis of the rotary shaft 3 (around the axis of the bearing portion 6B of the upper bearing 6).

Each of the plurality of openings 11H penetrates the muffler main body 11 in the plate thickness direction. In the example shown in FIG. 2, the opening 11H is formed in the portion 11A. However, the opening 11H can be formed in the portion 11B or in both the

portions

11A and 11B.
The cross-sectional area (opening area) of the opening 11H is very small compared to the cross-sectional area of the discharge port 11P. The sectional area of the opening 11H is, for example, about 1/500 to 1/100 of the sectional area of the discharge port 11P. As will be described later, it is preferable that a large number of minute openings 11H are formed in the muffler main body 11 in order to enhance the pulsation reduction effect by the openings 11H and the cavities 120.
The opening 11H can be formed as a circular round hole as shown in FIG. 4A. However, the opening 11H is not limited to this, and the opening 11H is appropriately configured as long as the inside and outside of the muffler main body 11 communicate with each other. Can do.
In order to enhance the pulsation reducing effect, it is preferable that a large number of openings 11H are formed over the entire surface of the muffler body 11.

The cover 12 (FIGS. 2 and 3) receives the refrigerant from the space 110 in the muffler body 11 into the cavity 120 between the cover 12 and discharges it from the discharge port 12P.
Similar to the above-described muffler body 11, the cover 12 is arranged around the axis of the rotary shaft 3, and the bearing portion 6 B is passed through an opening formed in the center of the plane of the cover 12.
An inner peripheral edge 121 (periphery edge of the opening) of the cover 12 is slightly raised along the axial direction. An annular gap between the inner peripheral end 121 and the bearing portion 6B is a discharge port 12P.
The discharge port 12P may be formed at a position away from the discharge port 11P so that the refrigerant discharged from the discharge port 11P of the muffler main body 11 into the cover 12 does not go out of the cover 12 as it is. preferable. The discharge port 12P may be formed so as to penetrate the cover 12 in the plate thickness direction instead of around the axis of the bearing portion 6B.

The cover 12 covers the outer peripheral portion 11 S of the muffler main body 11 and is fastened to the upper bearing 6 together with the muffler main body 11 by bolts 113.
The inner peripheral end 121 of the cover 12 is located farther in the axial direction from the abutting portion 6 A of the upper bearing 6 than the inner peripheral end 111 of the muffler body 11. The cover 12 includes a portion 12A facing the portion 11A of the muffler main body 11, and a portion 12B descending from the portion 12A.
The cover 12 of this embodiment covers the entire muffler main body 11, but the cover 12 may cover at least a part of the muffler main body 11 as long as a cavity 120 is formed between the cover 12 and the muffler main body 11. That's fine.
Depending on the height of the cover 12, the inner peripheral end 121 may face the outer peripheral portion of the rotating shaft 3 instead of the bearing portion 6B. In that case, the discharge port 12 P is formed between the inner peripheral end 121 and the outer peripheral portion of the rotating shaft 3.

The lower muffler 20 (FIG. 1) is configured in substantially the same shape as the upper muffler 10, and is arranged around the axis of the lower bearing 7 so as to be reversed in the vertical direction with respect to the upper muffler 10.
Unlike the upper muffler 10, the lower muffler 20 does not include a cover and is formed of a single member. However, like the upper muffler 10, the lower muffler 20 may be configured to include a muffler body and a cover. it can.

Hereinafter, the pulsation reduction effect by the upper muffler 10 will be described.
As described above, since the muffler main body 11 forms the space 110 and the cover 12 forms the cavity 120, the refrigerant compressed by the compression mechanism 41 is ejected into the space 110 and discharged from the discharge port 11P to the cavity 120. The ink is discharged into the inside, and further, discharged from the cavity 120 to the outside of the cover 12 through the discharge port 12P. As described above, the refrigerant sequentially passes through the inside of the muffler main body 11 and the inside of the cover 12, thereby reducing the pulsation of the refrigerant. That is, the muffler 10 including the muffler body 11 and the cover 12 functions as a two-stage muffler that reduces pulsation over two stages.

The muffler 10 of the present embodiment achieves further pulsation reduction by establishing Helmholtz resonance by the opening 11H of the muffler main body 11 and the cavity 120 while maintaining the performance of reducing pulsation as a two-stage muffler. . The opening 11H and the cavity 120 constitute a Helmholtz resonator.
As shown in FIG. 4B, the Helmholtz resonance is caused by a certain frequency accompanying the surrounding air when the air mass 15 (air column) existing inside the opening 11H leading to the cavity 120 moves in the direction of the hole axis. Resonates at. At this time, the cavity 120 can be regarded as a spring provided in the air mass 15. When the air mass 15 vibrates in a resonance state, friction between air and the inner peripheral portion of the opening 11H and friction between air molecules are remarkably generated, so that vibration energy is attenuated and sound pressure is reduced (sound absorption).

In order to establish Helmholtz resonance, the cross-sectional area S (transverse area) of the opening 11H, the plate thickness L of the muffler main body 11, and the volume V of the cavity 120 are determined to be in an appropriate relationship with each other.
The basic formula of Helmholtz resonance is shown below. f is the natural frequency (natural frequency) of the air mass 15, and C is the speed of sound.

Sound absorption by Helmholtz resonance is premised on LS << V. That is, LS, which is the volume inside the opening 11H, is extremely small so as to be negligible compared to the volume V of the cavity 120. Depending on the frequency f for reducing the pulsation, the hole diameter of the opening 11H is, for example, about 0.15 mm, and the plate thickness L is, for example, about 1.5 mm. Since each opening 11H is very small, the total LS of the plurality of openings 11H is also very small compared to the volume V of the cavity 120.
As described above, since the cross-sectional area of the opening 11H is smaller than that of the discharge port 11P and the discharge port 12P, the refrigerant received in the wide space 110 is discharged from the narrow discharge port 11P and also received in the cavity 120. Thus, it does not affect the main (mainstream) refrigerant flow involved in the basic pulsation reduction mechanism of the muffler 10 that discharges from the discharge port 12P.

The cross-sectional area S and the plate thickness L can be determined in consideration of an appropriate frequency f to be reduced.
For example, when the natural frequency (resonance frequency) of the air mass 15 is 250 Hz, the hole diameter of the opening 11H is set to 0.15 mm, the plate thickness of the muffler body 11 is set to 1.5 mm, and the volume V of the cavity 120 is set to 200 mm ³ . be able to.
Here, in order to obtain a pulsation reduction effect (sound absorption effect), the hole diameter of the opening 11H needs to be sufficiently small, and the total of the cross-sectional areas S of the plurality of openings 11H is 1% of the surface area of the muffler body 11. The upper limit.

Since the air mass 15 in the opening 11H moves while dragging the surrounding air, it is necessary to correct the length (plate thickness L) of the air mass 15 according to the shape around the opening 11H (opening portion). correction). For example, when the radius of the opening 11H is a, L ′ obtained by L + 1.7a = L ′ can be applied to the above equation (1).

According to the compressor 1 of the present embodiment, the pulsation of the refrigerant compressed by the upper compression mechanism 41 and the lower compression mechanism 42 can be sufficiently reduced by the

mufflers

10 and 20. As described above, according to the muffler 10, it is possible to obtain the pulsation reduction effect based on Helmholtz resonance while maintaining the pulsation reduction effect of the two-stage muffler that repeatedly discharges the pulsation into the space. The movement of the air mass 15 inside the minute opening 11H does not affect the main flow in the muffler.
Therefore, according to the present embodiment, it is possible to sufficiently reduce the pulsation of the refrigerant while suppressing the performance of the compressor 1 and to suppress noise due to the pressure fluctuation of the refrigerant.
Since the muffler 10 can suppress the sound pressure from being emitted by the muffler 10 itself as a sound source by reducing the pulsation, the noise can be suppressed even if the thickness of the muffler body 11 and the cover 12 is thin. It becomes possible.

In addition to the above, the configurations described in the above embodiments can be selected or changed to other configurations as appropriate without departing from the gist of the present invention.

The compression mechanism mounted on the compressor of the present invention is not limited to the twin rotary type compression mechanism 4, but may be a single rotary type compression mechanism having a pair of cylinders and piston rotors, and a muffler.

The compressor of the present invention is not limited to a rotary compressor, and may be a scroll compressor. In that case, the configuration of the present invention may be applied to a muffler (also referred to as a discharge cover) that receives the compressed refrigerant discharged from the scroll compression mechanism. That is, the discharge cover (muffler) may include a muffler main body and a cover, and the minute opening 11H may be formed in the muffler main body.

As a power source of the compressor of the present invention, for example, an engine or the like other than the motor is allowed.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Motor 2A Stator 2B Rotor 2C Coil 3 Rotating shaft 3A Main shaft part

3B Upper crankpin

3C Lower crankpin 4 Compression mechanism 4A Partition plate 5 Housing 5A Discharge pipe 6 Upper bearing 6A Butting part

6B Bearing part

6P Discharge port 7 Lower bearing 7A Abutting portion

7B Bearing portion

8, 9 Piping 10 Upper muffler 11 Muffler body 11A Part 11B Part 11P Discharge port 11H Opening 11S Outer peripheral part 12 Cover 12A Part 12B Part 12P Discharge port 15 Air mass 20 Lower muffler 41 Upper compression mechanism 42 Lower compression mechanism 61A Notch 110 Space 111 Inner peripheral end 113 Bolt 120 Cavity 121 Inner peripheral end 411 Upper piston rotor 412 Upper cylinder 421 Lower piston rotor 422 Lower cylinder L Plate thickness S Cut Product V volume

Claims

A compression mechanism for compressing the fluid;
A muffler that reduces pulsation of the fluid compressed by the compression mechanism,
The muffler is
A muffler body that receives the fluid from the compression mechanism inside,
Forming a cavity between the outer periphery of the muffler body, and a cover for discharging the fluid received from the inside of the muffler body,
In the muffler body, a plurality of openings penetrating in the plate thickness direction are formed separately from the discharge port through which the fluid passes from the inside of the muffler body into the cavity,
From the relationship between the speed of sound C, the cross-sectional area S of each of the openings, the plate thickness L, and the volume V of the cavity,
The Helmholtz resonance is established for the air mass existing inside the opening leading to the cavity, and sound is absorbed.
A compressor characterized by that.
The compression mechanism is
A piston rotor provided on the rotating shaft and a cylinder in which the piston rotor is disposed;
The muffler body and the cover are
Arranged around the axis of the rotation axis,
The compressor according to claim 1.