Packaged compressor housing

The packaged compressor includes: an exhaust duct having an exhaust port; a gas cooler arranged to be inclined with respect to the exhaust port in the exhaust duct; and at least one sound insulating plate arranged in a direction perpendicular to the exhaust port in the exhaust duct, the sound insulating plate configured to partition the exhaust port. In the packaged compressor, the exhaust port is partitioned into divided openings by the sound insulating plate. Of the divided openings, an area of a first divided opening provided on a side where a distance between the gas cooler and the exhaust port is shortest is larger than an area of a second divided opening.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a national phase application in the United States of International Patent Application No. PCT/JP2017/019529 with an international filing date of May 25, 2017, which claims priority of Japanese Patent Application No. 2016-120034 filed on Jun. 16, 2016 the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a packaged compressor.

BACKGROUND ART

The packaged compressor includes one package in which a compressor main body and a heat exchanger (gas cooler) for cooling the compressed air discharged from the compressor main body are arranged. JP 2010-127234 A discloses a structure in which a gas cooler is disposed in an inclined manner for effective usage of a space in a package. In addition, an intake port of this packaged compressor has a louver structure in which sound insulating plates of the same length are arranged at equal intervals in parallel.

Packaged compressors are often limited in the package size from the viewpoint of the degree of freedom of installation. Therefore, it is required to arrange components in a package such as a gas cooler in a space-saving manner. As with the packaged compressor of JP 2010-127234 A, arranging sound insulating plates of the same length in parallel at equal intervals improves sound insulation performance (silent performance), but there is room for improvement from the viewpoint of space saving.

Embodiments of the present invention are made under such circumstances, and an object of the present invention is to provide a packaged compressor can achieve both of a space saving arrangement of components in a package and silence.

Means for Solving the Problems

The packaged compressor according to an embodiment of the present invention includes: a duct having an opening; a heat exchanger arranged to be inclined with respect to the opening in the duct; and at least one sound insulating plate arranged in a direction perpendicular to the opening in the duct, the sound insulating plate configured to partition the opening. The opening is partitioned into a plurality of divided openings including a first divided opening by the sound insulating plate. The divided opening provided on a side where a distance between the gas cooler and the opening is shortest is larger than areas of the others of the divided openings.

In this case, the “packaged compressor” of the present invention means a compressor in which various components including a compressor main body are arranged in a package. In addition, “perpendicular to the opening” means that the sound insulating plate is arranged in a direction perpendicular to the opening surface in plan view, that is, when the opening is viewed in face-to-face. In addition, “a side where a distance between the gas cooler and the opening is shortest” means, in side view that is as viewed from a direction in which the gas cooler and the sound insulating plate extend, when the length of a distance between the gas cooler and the opening is determined, a side on which the distance is shortest.

According to this configuration, since the heat exchanger is arranged so as to be inclined, the cross-sectional area of the duct can be reduced as compared with the case where the duct is arranged horizontally, the duct can be reduced in size, and the components in the package can be arranged in a space-saving manner. In addition, the noise reduction effect of the duct is generally proportional to the length of the sound insulating plate installed inside the duct and inversely proportional to the size of the opening of the duct. As in the above configuration, when the first divided opening is formed larger, the sound insulating plate is disposed close to the side on which the distance between the heat exchanger and the opening is longer. Therefore, the length of the sound insulating plate that can be installed can be increased, and the noise reduction effect can be improved. In addition, forming the first divided opening large causes the area of the divided opening other than the first divided opening to decrease. In comprehensive consideration of the increase and decrease of the noise reduction effect due to the increase and decrease of the area of the divided openings and the improvement in the noise reduction effect due to the length of the sound insulating plate, when the area of the first divided opening is made largest as compared with the areas of the other divided openings, the amount of noise reduction effect becomes maximum, that is, the silent performance can be maximized.

The inner surface of the duct may be covered with a sound absorbing material.

Since the inner surface of the duct is covered with a sound absorbing material, the noise reduction effect is further improved, and the silent performance can be further improved. Preferably, the entire surface of the inner surface of the duct is covered with a sound absorbing material, and more preferably the sound insulating plate is also covered with a sound absorbing material.

At least two of the sound insulating plates are arranged, and a length of the sound insulating plate may be longer than a length of another of the sound insulating plates arranged adjacent to a side on which a distance between the heat exchanger and the opening is shorter.

Since the length of each of the sound insulating plates is longer than that of the adjacent other sound insulating plates on a side on which a distance between the heat exchanger and the opening is shorter, the length of each of the sound insulating plates is specified to increase toward a side on which a distance between the heat exchanger and the opening is longer. Therefore, the space widened by the inclined arrangement of the heat exchanger can be effectively utilized, and the noise reduction effect can be improved.

The sound insulating plates may be disposed at a predetermined equal space from the heat exchanger.

The larger the length of the sound insulating plate in the duct is, the more the noise reduction effect is improved. However, if the lengths of the sound insulating plates are increased to be too close to the heat exchanger, since the heat exchanger is at a high temperature, the sound insulating plates are thermally affected. In particular, when the sound absorbing material is stuck to the sound insulating plates, the sound absorbing material is thermally deteriorated, and further, the adhesive sticking the sound absorbing material to the sound insulating plates changes in properties due to the high temperature, so that the sound absorbing material is easily peeled off. Therefore, arranging the sound insulating plates with a predetermined equal space, at which the sound insulating plates are not easily thermally affected from the heat exchanger, apart from the heat exchanger, that is, maximally securing the lengths of the sound insulating plates to the extent that the thermal effect is minimal allows the noise reduction effect to be maximally improved while the sound insulating plates are protected from heat deterioration.

The first divided opening may be provided with a blocking portion for partially blocking a region on a side opposite to the sound insulating plate.

Since the first divided opening is the largest of the divided openings, the noise reduction effect tends to be minimized. Furthermore, since the first divided opening is provided on a side on which the distance between the heat exchanger and the opening is the shortest, the maximum value of the length of the sound insulating plate that can be installed is also shorter than that of the other sound insulating plates, and the noise reduction effect tends to be minimized as compared with the other divided openings. Therefore, as in the above configuration, blocking a part of the first divided opening and preventing noise from leaking out allow the noise reduction effect to be improved. In particular, in the first divided opening, since the noise reduction effect is large in the vicinity of the sound insulating plate, it is effective to partially block the region on the side opposite to the sound insulating plate. Furthermore, when the size of the opening is sufficiently secured in consideration of the cooling capacity of the packaged compressor, the present configuration is particularly useful.

Two of the sound insulating plates may be arranged. The divided openings may include the first divided opening, the second divided opening, and the third divided opening positioned in order from a side on which a distance between the heat exchanger and the opening is shorter toward a side on which a distance between the heat exchanger and the opening is longer. The first divided opening may have a width determined by a following mathematical expression (1):
[Mathematical Expression 1]
b/3<b1<2b/3  (1)
b=b1+b2+b3
b: width of opening
b1: width of first divided opening
b2: width of second divided opening
b3: width of third divided opening

Defining the range of the width of the first divided opening as in the above mathematical expression (1) allows the noise reduction effect to be maximized. When the width of the first divided opening is less than the range of the mathematical expression (1), the length of the sound insulating plate forming the first divided opening becomes shorter, and the noise reduction effect decreases. When the width of the first divided opening is larger than the range of the mathematical expression (1), the first divided opening becomes larger, the noise leaking out from the first divided opening becomes larger, and the noise reduction effect decreases. In addition, when the range of the mathematical expression (1) is set as the optimum range of the width of the first divided opening, the noise reduction effect is confirmed to be maximized from the viewpoint of numerical analysis.

Each of the second divided opening and the third divided opening may have a width determined by a following mathematical expression (2):
[Mathematical Expression 2]
b2<b/3,b3<b/3  (2)
b=b1+b2+b3
b: width of opening
b1: width of first divided opening
b2: width of second divided opening
b3: width of third divided opening

According to this configuration, similarly to the above-described first divided opening, the range of each width of the second divided opening and the third divided opening can be set in an optimum range so that the noise reduction effect when two sound insulating plates are used can be maximized. In addition, when the range of the mathematical expression (2) is set as the optimum range of each width of the first to third divided openings, the noise reduction effect is confirmed to be maximized from the viewpoint of numerical analysis.

One of the sound insulating plates may be arranged. Of the first divided opening and the second divided opening arranged in order from a side on which a distance between the gas cooler and the opening is shorter toward a side on which a distance between the gas cooler and the opening is longer, a width of the first divided opening may be determined by a following mathematical expression (3):
[Mathematical Expression 3]
0.6≤b1/b≤0.8  (3)
b=b1+b2
b1: width of first divided opening
b2: width of second divided opening

According to this configuration, similarly to the case of the above-described two sound insulating plates, even in the case of one sound insulating plate, the range of the width of the first divided opening can be set to the optimum range as shown in mathematical expression (3) so that the noise reduction effect when one sound insulating plate is used can be maximized. In addition, when the range of the mathematical expression (3) is set as the optimum range of the width of the first divided opening, the noise reduction effect is confirmed to be maximized from the viewpoint of numerical analysis.

The first divided opening may have a width determined by a following mathematical expression (4):
[Mathematical Expression 4]
−0.0013θ+0.67≤b1/b≤−0.0041θ+0.94  (4)
b=b1+b2
b: width of opening
b1: width of first divided opening
b2: width of second divided opening
θ: inclination angle with respect to opening of gas cooler

According to this configuration, in consideration of a case where the inclination angle θ changes, the noise reduction effect can be maximized when one sound insulating plate is used. In addition, when the range of the mathematical expression (4) is set as the optimum range of the width of the first divided opening, the noise reduction effect is confirmed to be maximized from the viewpoint of numerical analysis.

A surface of the sound insulating plate facing the heat exchanger may be covered with a sound absorbing material. A tip portion of the sound absorbing material of the sound insulating plate facing the heat exchanger may be chamfered.

Thus, the sound absorbing material can be separated from the heat exchanger by the amount by which a corner of the sound absorbing material of the sound insulating plate is removed, and the sound insulating plate can be lengthened by that amount.

The tip portion of the sound insulating plate may be bent toward the heat exchanger.

Since the tip portions of the sound insulating plates are bent, it is difficult for the sound waves traveling between the sound insulating plates to travel straight, that is, noise hardly leaks directly to the outside. Therefore, the noise reduction effect can be improved and the silent performance can be improved.

The tip portion of the sound insulating plate may have a shape defined by a following mathematical expression (5):
[Mathematical Expression 5]
m×sin ζ>bx(5)
m: length of tip portion of sound insulating plate
ζ: bending angle of tip portion of sound insulating plate
bx: width of divided opening partitioned by sound insulating plate

According to this configuration, when the inside of the duct is viewed from the opening, since the heat exchanger is positioned behind the bent tip portions of the sound insulating plates, that is, the heat exchanger cannot be directly viewed, it is possible to prevent noise from the heat exchanger from directly leaking out to the outside and to improve the noise reduction effect.

The sound insulating plate may include a protruding portion on a surface facing the heat exchanger.

According to this configuration, similarly to the above, it is possible to prevent noise from directly leaking to the outside and to improve the noise reduction effect. In addition, since only the protruding portions are provided, the flow passage area between the sound insulating plates is not reduced.

The duct may be an exhaust duct.

Since the exhaust duct guides the air flowing out of the package, providing the sound insulating structure as described above to the exhaust duct can effectively prevent leakage of noise to the outside of the package.

According to the present invention, arranging the heat exchanger to be inclined and defining the size of the first divided opening allow a packaged compressor in which space-saving arrangement of components in the package and silence are compatible with each other to be provided.

MODE FOR CARRYING OUT THE INVENTION

First Embodiment

Referring toFIG. 1, a packaged compressor2of the present embodiment includes a box-type package4. The inside of the package4is provided with a compressor main body6, a turbofan8functioning as a cooling fan, an exhaust duct (duct)10, and a gas cooler (heat exchanger)12.

The package4is formed of a metal plate such as a steel plate and includes intake ports14and15and an exhaust port (opening)16. A filter (not shown) is attached to the intake ports14and15, and air from which foreign matters such as dust are removed by the filter is introduced into the package4. The space in the package4is divided into a compression chamber18and an air cooling chamber20. The compression chamber18and the air cooling chamber20are partitioned by the exhaust duct10and the fan cover22of the turbofan8so that air does not directly come in and out from each other.

First, the configuration in the compression chamber18will be described.

In the compression chamber18, the compressor main body6is disposed. The compressor main body6of the present embodiment is of a two-stage screw type. The compressor main body6includes a first-stage compressor main body24, a second-stage compressor main body26, a gear box28, and a compressor motor30.

The gear box28is fixed to a base32constituting the floor of the compression chamber18. The compressor motor30is fixed to the base32by a supporting column34. Each of the first-stage compressor main body24and the second-stage compressor main body26includes an intake port, a discharge port, and a pair of male and female screw rotors inside. The first-stage compressor main body24and the second-stage compressor main body26suck air from the intake ports. Each of the screw rotors is mechanically connected to the compressor motor30via the gear box28, and is rotationally driven by the compressor motor30, and the sucked air is compressed. The intake port of the first-stage compressor main body24is opened in the package4. The discharge port of the first-stage compressor main body24is fluidly connected to the intake port of the second-stage compressor main body26through a pipe (not shown). The discharge port of the second-stage compressor main body26is fluidly connected to the inlet port38of the gas cooler12through a pipe36.

Next, the configuration in the air cooling chamber20will be described.

In the air cooling chamber20, a turbofan8and an exhaust duct10are arranged.

A fan cover22is attached to the turbofan8and is disposed in a lower part of the air cooling chamber20. In addition, the turbofan8includes a fan motor40. The fan motor40is disposed on the base32. The turbofan8is driven by the fan motor40and causes the air in the air cooling chamber20to flow from the intake port15to the exhaust port16. Although the configuration in the air cooling chamber20is described here, the fan motor40is disposed inside the compression chamber18.

The exhaust duct10guides the air delivered by the turbofan8to the exhaust port16. The lower end of the exhaust duct10is connected to the fan cover22of the turbofan8, and the upper end thereof is connected to the upper surface and the exhaust port16of the package4. A sound absorbing material42is stuck to the inner surface of the exhaust duct10. The sound absorbing material42is a spongy soft member. The sound absorbing material42absorbs noise energy and attenuates noise.

Inside the exhaust duct10, the gas cooler12is disposed inclined with respect to the exhaust port16. In the present embodiment, the inclination angle θ of the gas cooler12is 45 degrees (seeFIG. 2). The inclination angle θ is preferably set in the range of 30 degrees to 65 degrees from the viewpoint of the cooling capacity, the space-saving arrangement of the gas cooler12, and the like. In order that this inclination angle θ is maintained, the gas cooler12is bolted to the exhaust duct10by a stopper44.

The gas cooler12includes an inlet port38, a plurality of tubes46communicating with the inlet port38, and an outlet port (not shown) communicating with the plurality of tubes46. The air compressed by the compressor main body6is introduced into the gas cooler12from the inlet port38and is led out from an outlet port (not shown) through the tube46. The air delivered by the turbofan8passes between the tubes46of the gas cooler12from the bottom to the top in the drawing. Therefore, in the gas cooler12, heat exchange is performed between the air inside and outside the tube46. Specifically, the air inside the tube46compressed by the compressor main body6is cooled, and the air outside the tube46delivered by the turbofan8is heated.

In the exhaust duct10, a sound insulating plate48is disposed. The sound insulating plate48of the present embodiment is a quadrangular steel plate. The sound insulating plate48is disposed to be fixed perpendicularly to the exhaust port16so as to partition the exhaust port16. The term “perpendicularly to the exhaust port16” specifically means that the sound insulating plate48is arranged in the direction perpendicular to the opening surface (vertical direction) as the exhaust port16is viewed in face-to-face in a plan view (see an arrow N inFIG. 3). In addition, sound absorbing materials42are stuck to both surfaces of the sound insulating plate48similarly to the inner surface of the exhaust duct10. That is, the sound insulating plate48is sandwiched between two sound absorbing materials42.

The exhaust port16is partitioned by the sound insulating plate48and divided into a first divided opening50and a second divided opening52. The first divided opening50is provided on the side on which the distance between the gas cooler12and the exhaust port16is shorter (on the left side in the drawing). The second divided opening52is provided on the side on which the distance between the gas cooler12and the exhaust port16is longer (on the right side in the drawing). Here, the side on which the distance between the gas cooler12and the exhaust port16is shorter or longer is determined from the side view shown inFIG. 2, that is, as seen from the direction in which the sound insulating plate48and the gas cooler12extend. This also applies to the following embodiments.

As shown inFIG. 2, the area of the first divided opening50is formed larger than the area of the second divided opening52. The areas of the first and second divided openings50and52herein indicate the opening areas when the first and second divided openings50and52are viewed in face-to-face in a plan view (see the arrow N inFIG. 3). Specifically, as shown in the following mathematical expression (6), the sound insulating plate48is arranged so that the width b1 of the first divided opening50is within the range of 0.6 to 0.8 with respect to the total b of the width b1 of the first divided opening50and the width b2 of the second divided opening52. In addition, the width b1 or b2 herein denotes the distance between the sound insulating plate48(or the sound absorbing material42stuck to the sound insulating plate48) and the inner surface of the exhaust duct10(or the sound absorbing material42stuck to the inner surface of the exhaust duct10).
[Mathematical Expression 6]
0.6≤b1/b≤0.8  (6)
b=b1+b2
b: width of opening
b1: width of first divided opening
b2: width of second divided opening

In addition, the sound insulating plate48is disposed with a predetermined space d apart from the gas cooler12. The predetermined space d is set so that the sound insulating plate48is hardly affected by heat from the gas cooler12. Details of the space d will be described below.

With reference toFIG. 1, first, the flow of air in the compression chamber18will be described (see the alternate long and short dash line arrow in the drawing).

The normal-temperature air outside the package4flows into the package4through the intake port14. The inflowing air is sucked into the first-stage compressor main body24to be compressed, and then is pressurized and fed to the second-stage compressor main body26, and further compressed. Here, due to the compression heat generated during compression, the temperature of compressed air becomes high. The high-temperature and high-pressure air compressed by the compressor main body6is pressurized and fed through the pipe36to the inlet port38of the gas cooler12. The high-temperature and high-pressure air introduced into the gas cooler12from the inlet port38of the gas cooler12is cooled by the air outside the tube46while passing through the tube46of the gas cooler12, that is, is heat-exchanged to be supplied from an outlet port (not shown) to a supply destination outside the package4.

Next, the flow of air in the air cooling chamber20will be described (see the broken line arrow in the drawing).

The normal-temperature air outside the package4flows into the package4through the intake port15. The inflowing air is sucked into the turbofan8and delivered upward in the drawing, that is, with noise into the exhaust duct10. The air delivered into the exhaust duct10is heat-exchanged with the compressed air in the tube46while passing between the tubes46of the gas cooler12as described above to be heated. After the noise energy is absorbed by the sound insulating plate48to which the sound absorbing material42is stuck and the inner surface of the exhaust duct10to which the sound absorbing material42is stuck, the air passing through the gas cooler12is exhausted from the exhaust port16to the outside of the package4.

According to the configuration of the present embodiment, covering the inner surface of the exhaust duct10with the sound absorbing material42improves the noise reduction effect as compared with the case where nothing is done and improves the silent performance. As in the present embodiment, it is preferable that the sound absorbing material42is covered on the entire inner surface of the exhaust duct10, and the sound insulating plate48is also covered with the sound absorbing material42, but the present invention is not limited to this, and the sound absorbing material42may be stuck to a part of the inside of the exhaust duct10.

In addition, since the gas cooler12is disposed to be inclined, the cross-sectional area of the exhaust duct10can be reduced as compared with the case where the gas cooler12is disposed horizontally, that is, the exhaust duct10can be reduced in size, and the components in the package4can be arranged in a space-saving manner. In addition, the noise reduction effect of the exhaust duct10is generally not only proportional to the length of the sound insulating plate48installed inside the exhaust duct10but also inversely proportional to the size of the exhaust port16. As described above, when the first divided opening50is formed larger, the sound insulating plate48is disposed close to the side on which the distance between the gas cooler12and the exhaust port16is longer. Therefore, the length of the sound insulating plate48that can be installed can be increased, and the noise reduction effect can be improved. In addition, forming the first divided opening50large causes the area of the second divided opening52to decrease. In comprehensive consideration of the increase and decrease of the noise reduction effect due to the increase and decrease of the area of the divided openings50and52and the improvement in the noise reduction effect due to the length of the sound insulating plate48, when the area of the first divided opening50is made largest as compared with the areas of the other divided openings52, the amount of noise reduction effect becomes maximum, that is, the silent performance can be maximized.

In order for maximization of the amount of noise reduction effect to be quantitatively examined, numerical analysis is performed as shown inFIGS. 3 to 6. As shown inFIG. 3, the analysis model is a rectangular parallelepiped exhaust duct10having dimensions of height l, width b, and depth a (where a=2b). The gas cooler12is disposed to be inclined at an inclination angle θ with respect to the exhaust port16. For the width b1 of the first divided opening50and the width b2 of the second divided opening52, let K be the sound absorption constant, then the noise reduction amounts TL1and TL2of the respective divided openings50and52are represented by the following mathematical expression (7): where l1 is the length of the sound insulating plate48. It should be noted that in the analysis model, the thickness of the wall of the exhaust duct10, the thickness of the sound insulating plate48, and the thickness of the sound absorbing material42stuck thereto are sufficiently smaller than the widths b1 and b2 of the respective divided openings50and52, that is, calculation is made assuming that b=b1+b2 is satisfied.
[Mathematical Expression 7]
TL1=K×2(a+b1)/a/b1×l1+K×2(a+b)/a/b×(l−l1)
TL2=K×2(a+b2)/a/b2×l1+K×2(a+b)/a/b×(l−l1)  (7)

Maximizing TL1and TL2in mathematical expression (7) allows the amount of noise reduction effect to be maximized. However, since the size of the exhaust duct10is defined, b1+b2 takes a constant value b. In addition, the length l1 of the sound insulating plate48is required to be a length such that the sound insulating plate48does not interfere with the gas cooler12. That is, the length l1 of the sound insulating plate48depends on the inclination angle θ of the gas cooler12and the width b1 of the first divided opening.

Under the above conditions,FIG. 4shows the result of analysis of the noise reduction amount TL for the analysis model inFIG. 3at θ=30°. The horizontal axis shows the ratio (b1/b) of the width b1 of the first divided opening to the width b (=b1+b2) of the exhaust duct10. The vertical axis shows the minus noise reduction amount TL (dB). InFIG. 4, graphs of noise reduction amounts TL1and TL2, and their average value TL0are shown. In the case where evaluating the silent performance from the graph, when the average value TL0of the noise reduction amount is the largest, it can be evaluated that the best silent performance is exhibited. Therefore, in the graph inFIG. 4, when b1/b=0.74, the best silent performance is exhibited. In addition, in consideration of the range of error 0.05 (db) from the optimum value, b1/b is preferably in the range of 0.63≤b1/b≤0.82.

FIGS. 5 and 6show the analysis results of the noise reduction amount TL as inFIG. 4in the case of θ=45° and 60°. As shown inFIG. 5, in the case where θ=45°, when b1/b=0.69, the best silent performance is exhibited. In consideration of the range of error 0.05 (db) from the optimum value, b1/b is preferably in the range of 0.62≤b1/b≤0.76. As shown inFIG. 6, in the case where θ=60°, when b1/b=0.65, the best silent performance is exhibited. In consideration of the range of error 0.05 (db) from the optimum value, b1/b is preferably in the range of 0.60≤b1/b≤0.70. The inclination angle θ of the gas cooler12is often used in the range of 30° 5 0 5 65° as described above. Therefore, in the range of the inclination angle θ, the width b1 of the first divided opening50is preferably set to be approximately within the range of 0.6≤b1/b≤0.8 in order that the range of error 0.05 (db) from the above-described optimum value inFIG. 4(θ=30°) toFIG. 6(θ=60°) is included. Furthermore, the width b1 of the first divided opening50is more preferably set to be within the range of 0.63≤b1/b≤0.70.

Furthermore,FIG. 7plots the optimum range including the error 0.05 (db) of the ratio (b1/b) of the width b1 of the first divided opening50with respect to the inclination angle θ of the gas cooler12based on the results inFIGS. 4 to 6. It is preferable to design the packaged compressor2in the range satisfying the following mathematical expression (8) as in the range indicated by the hatched portion within the range of the two straight lines inFIG. 7. Designing in this manner allows the noise reduction effect with one sound insulating plate48to be maximized in consideration of even the inclination angle θ changing.
[Mathematical Expression 8]
−0.0013θ+0.67≤b1/b≤−0.0041θ+0.94  (8)
b=b1+b2
b: width of opening
b1: width of first divided opening
b2: width of second divided opening
θ: inclination angle with respect to opening of heat exchanger

In the present embodiment, a noise prevention structure as described above is provided in the exhaust duct10, and since the exhaust duct10guides the air flowing out of the package4, providing the exhaust duct10with the sound insulating structure as described above is effective for preventing noise from leaking outside the package4. However, when there is an intake duct, a similar noise prevention structure may be provided in the intake duct. This also applies to the second embodiment and subsequent modifications.

Second Embodiment

In the exhaust duct10of the packaged compressor2of the present embodiment shown inFIG. 8, two sound insulating plates48and49are arranged. The packaged compressor2of the present embodiment has the same configuration as that of the packaged compressor2of the first embodiment inFIGS. 1 and 2, except for this configuration. Therefore, the same reference numerals are given to the same parts as those shown inFIGS. 1 and 2, and description thereof will be omitted.

In the packaged compressor2of the present embodiment, two sound insulating plates48and49are arranged perpendicularly to the exhaust port16, that is, arranged vertically. Therefore, the exhaust port16is partitioned by the two sound insulating plates48and49, and divided into a first divided opening50, a second divided opening52, and a third divided opening54in order from the side on which the distance between the gas cooler12and the exhaust port16is shorter (the left side in the drawing) to the side on which the distance is longer (the right side in the drawing).

In the present embodiment, the sound insulating plates48and49are arranged so that the width b1 of the first divided opening50is larger than the widths b2 and b3 of the other divided openings52and54. Furthermore, the sound insulating plates48and49are arranged so that the widths b1, b2, and b3 of the first, second, and third divided openings50,52, and54are within predetermined ranges satisfying the following mathematical expression (9): In addition, the widths b1, b2 herein respectively denote the distances between the sound insulating plate48(or the sound absorbing material42stuck to the sound insulating plate48), the sound insulating plate49(or the sound absorbing material42stuck to the sound insulating plate49), and the inner surface of the exhaust duct10(or the sound absorbing material42stuck to the inner surface of the exhaust duct10).
[Mathematical Expression 9]
b/3<b1<2b/3,b2<b/3,b3<b/3  (9)
b=b1+b2+b3
b: width of opening
b1: width of first divided opening
b2: width of second divided opening
b3: width of third divided opening

In addition, of the sound insulating plates48and49, the sound insulating plate49disposed on the side on which the distance between the gas cooler12and the exhaust port16is longer is longer. Specifically, the lengths l1 and l2 of the sound insulating plates48and49are respectively provided with the same predetermined distances d apart from the gas cooler12. As the lengths of the sound insulating plates48and49are longer, the noise reduction effect is generally improved. However, if the lengths of the sound insulating plates48and49are increased to be too close to the gas cooler12, since the gas cooler12is at a high temperature, the sound insulating plates48and49are thermally affected. In particular, when the sound absorbing material42is stuck to the sound insulating plates48and49as in the present embodiment, the sound absorbing material42is thermally deteriorated, and further, the adhesive sticking the sound absorbing material42to the sound insulating plates48and49changes in properties due to the high temperature, so that the sound absorbing material42is easily peeled off. Therefore, arranging the sound insulating plates48and49with a predetermined space d (seeFIG. 8), at which the sound insulating plates48and49are not easily thermally affected from the gas cooler12, apart from the gas cooler12, that is, maximally securing the lengths of the sound insulating plates48and49to the extent that the thermal effect is minimal allows the noise reduction effect to be maximally improved while the sound insulating plates48and49are protected from heat deterioration.

In addition, as shown inFIGS. 8 and 9and the following mathematical expression (10), the length l of the sound insulating plate49can also be expressed based on the length l1 of the adjacent sound insulating plate48, the width b2 of the second divided opening52, and the thickness t of the sound absorbing material42. This also applies to the case where three or more sound insulating plates are provided, that is, the length of the sound insulating plate can be expressed based on the length of the adjacent sound insulating plate and the like. Therefore, specifying the length of one sound insulating plate allows the length of the remaining sound insulating plate to be specified.
[Mathematical Expression 10]
l2=l1+(b2+2t)×tan θ  (10)

Thus, increasing the length of the sound insulating plate49on the side on which the distance between the gas cooler12and the exhaust port16is longer, and more specifically, maximally increasing the length of the two sound insulating plates48and49allows the space widened due to the inclined arrangement of the gas cooler12to be effectively utilized, and the noise reduction effect to be improved.

Similarly to the first embodiment, also in the present embodiment, numerical analysis is performed as shown inFIGS. 10 to 12by the analysis model shown inFIG. 9. For the width b1 of the first divided opening50, the width b2 of the second divided opening52, and the width b3 of the third divided opening52, let K be the sound absorption constant, then the noise reduction amounts TL1, TL2, and TL3of the respective divided openings50,52, and54are represented by the following mathematical expression (11): where l1 is the length of the sound insulating plate48forming the first and second divided openings50and52, and l2 is the length of the sound insulating plate49forming the second and third divided openings52and54. It should be noted that in the analysis model, the thickness of the wall of the exhaust duct10, the thickness of the sound insulating plate48and49, and the thickness of the sound absorbing material42stuck thereto are sufficiently smaller than the widths of the respective divided openings50,52, and54, that is, calculation is made assuming that b=b1+b2+b3 is satisfied.
[Mathematical Expression 11]
TL1=K×2(a+b1)/a/b1×l1+K×2(a+b1+b2)/a/(b1+b2)×(l2−l1)+K×2(a+b)/a/b×(l−l2)
TL2=K×2(a+b2)/a/b2×l1+K×2(a+b1+b2)/a/(b1+b2)×(l2−l1)+K×2(a+b)/a/b×(l−l2)
TL3=K×2(a+b3)/a/b3×l2+K×2(a+b)/a/b×(l−l2)  (11)

Maximizing TL1, TL2, and TL3in mathematical expression (11) allows the noise reduction effect to be maximized, but each variable (b1, b2, b3, l1, l2) in mathematical expression (11) is not independent of each other. Since the size of the exhaust duct10is specified, b1+b2+b3 takes a constant value b. As described above, the lengths l1 and l2 of the sound insulating plates48and49are determined so that the space between the sound insulating plates48and49and the gas cooler12is a predetermined space d (seeFIG. 8).

FIG. 10shows the result of analyzing the noise reduction amount TL of the analysis model inFIG. 3at θ=30°. The horizontal axis shows the ratio of the width b1 of the first divided opening50to the width b of the exhaust duct10. The vertical axis shows the ratio of the width b2 of the second divided opening52to the width b of the exhaust duct10. InFIG. 10, a graph of the noise reduction amount TL (average value of TL1, TL2, and TL3) with respect to these ratios is shown. In the graphs inFIGS. 10 to 12, a graph connecting equal noise reduction amount TL is plotted every 0.2 dB, and the closer to the center of the equal noise reduction amount line diagram, the larger the noise reduction volume is. Therefore, in the case where silent performance is evaluated from graphs, when the noise reduction amount TL is the largest, that is, at the center of the equal noise reduction amount line diagram, it can be evaluated that the best silent performance is exhibited. Accordingly, in the graph inFIG. 10, the best silent performance is exhibited when b1/b=0.59 and b2/b=0.21.

FIGS. 11 and 12show the analysis results of the noise reduction amount TL by using the same analysis model when θ=45° and 60°. As shown inFIG. 11, in the case where θ=45°, when b1/b=0.53 and b2/b=0.23, the best silent performance is exhibited. As shown inFIG. 12, in the case where θ=60°, when b1/b=0.47 and b2/b=0.26, the best silent performance is exhibited.

Similarly to the first embodiment, when the inclination angle θ of the gas cooler12is set in the range of 30°≤θ≤65°, the inside of the range of mathematical expression (9) (the inside of the range indicated by the hatched portion inFIGS. 10 to 12) includes a region in which the best silent performance is exhibited in each graph inFIGS. 10 to 12. Therefore, setting the widths b1, b2, and b3 of the first to third divided openings50,52, and54so as to be approximately within the range of the above mathematical expression (9) (within the range indicated by the hatched portion inFIGS. 10 to 12) allows good silent performance to be exhibited.

FIGS. 13 to 16show modifications that can be applied in common to the packaged compressor2of the first embodiment or the second embodiment.

As shown inFIG. 13, in the present modification, the first divided opening50is provided with a blocking portion56for partially blocking a region on a side opposite to the sound insulating plate48. The blocking portion56of the present embodiment is made of a steel plate and is formed by bending a part of the exhaust duct10.

Since the size of the first divided opening50is the largest among those of the respective divided openings50,52, and54, the noise reduction effect in the first divided opening50tends to be the minimum as compared with the noise reduction effect in the other divided openings52and54. Furthermore, since the first divided opening50is provided on the side on which the distance between the gas cooler12and the exhaust port16is the shortest, the maximum value of the length of the sound insulating plate48that can be installed is also shorter than that of the other sound insulating plate49, and the noise reduction effect tends to be minimized as compared with the other divided openings52and54. Therefore, as in the above configuration, blocking a part of the first divided opening50and preventing noise from leaking out allow the noise reduction effect to be improved. In particular, in the present modification, in the first divided opening50, since the noise reduction effect is large in the vicinity of the sound insulating plate48, it is effective to partially block the region on the side opposite to the sound insulating plate48. Furthermore, when the size of the exhaust port16is sufficiently secured in consideration of the cooling capacity of the packaged compressor2, no adverse effect due to the provision of the blocking portion56occurs, so that the configuration of the present modification is useful.

However, the position of the blocking portion56is not limited to the first divided opening50. For example, as indicated by a broken line inFIG. 13, the position of the blocking portion56may be in a region on the side opposite to the sound insulating plate49in the third divided opening52.

As shown inFIG. 14, in the present modification, a tip portion58of the sound absorbing material42of the sound insulating plate48, which faces the gas cooler12, is chamfered. That is, a part of the sound absorbing material42of the tip portion58on the gas cooler12side of the sound insulating plate48is cut off.

The sound absorbing material42can be separated from the gas cooler12by the amount by which the sound absorbing material42of the sound insulating plate48is chamfered, and the sound insulating plate48can be lengthened by that amount. In the present modification, the sound insulating plate48is formed longer than those of the first and second embodiments by the distance h while the distance d between the gas cooler12and the sound insulating plate48(sound absorbing material42) is maintained, where the distances h and d correspond to amounts by which a part of the sound absorbing material42is cut off.

As shown inFIG. 15, in the present modification, the tip portions58and59of the sound insulating plates48and49are bent toward the gas cooler12. Specifically, the tip portions58and59of the sound insulating plates48and49are bent into a shape defined by the following mathematical expression (12):
[Mathematical Expression 12]
m×sin ζ>bx(12)
m: length of tip portions58and59of sound insulating plates48and49
ζ: bending angle of tip portions58and59of sound insulating plates48and49
bx: width of divided opening partitioned by sound insulating plates48and49

According to the configuration of the present modification, since the tip portions58of the sound insulating plates48and49are bent, it is difficult for the sound waves traveling between the sound insulating plates48and49to travel straight, that is, noise hardly leaks directly to the outside. Therefore, the noise reduction effect can be improved and the silent performance can be improved. Furthermore, when the inside of the exhaust duct10is viewed from the exhaust port16, since the gas cooler12is positioned behind the bent tip portions58and59of the sound insulating plates48and49, that is, the gas cooler12cannot be directly viewed, it is possible to prevent noise from the gas cooler12from directly leaking out to the outside and to improve the noise reduction effect.

As shown inFIG. 16, in the present modification, the sound insulating plates48and49are provided with protruding portions60and61on the surfaces facing the gas cooler12. The protruding portions60and61are formed by welding steel plates at right angles to the sound insulating plates48and49. The mode of the protruding portions60and61is not particularly limited, and the position, size, and installation angle thereof may be freely changed. Preferably, from the viewpoint of pressure loss and the like, the protruding portion61is arranged so that the distance w1between the protruding portion61and the sound insulating plate48is larger than the distance w2between the two sound insulating plates48and49including the sound absorbing material42. In addition, the protruding portions60and61may also be covered with a sound absorbing material.

According to the configuration of the present modification, as in the third modification, it is possible to prevent noise from directly leaking to the outside and to improve the noise reduction effect. In addition, since only the protruding portions60and61are provided, the flow passage area between the sound insulating plates48and49is not reduced.

As described above, although the specific embodiments of the present invention and its modifications are described, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. For example, an appropriate combination of contents of the individual embodiments may be one embodiment of the present invention. Furthermore, the number of sound insulating plates is not particularly limited, and as shown inFIG. 17, three sound insulating plates48,49, and51may be arranged. Also in this case, the relationship between the widths b1, b2, b3, and b4 of the respective divided openings50,52,54, and62, the space d between the sound insulating plates48,49, and51and the gas cooler12, and the like are similar to those of the first and second embodiments. Furthermore, although not shown, four or more sound insulating plates may be arranged.