Noise silencer for a vehicle air conditioning system

Abstract

Silencer for a vehicle air conditioning system designed to reduce noise and vibration transmitted along coolant lines (30) in a vehicle compartment, the silencer comprising: a silencer body tube (10) installed between the coolant lines (30) such that a coolant gas flowing along the coolant lines (30) passes through the silencer body tube (10), the silencer body tube (10) having several resonance holes (12), an outer resonance tube (20) which is installed on the outer circumferential surface of the silencer body tube (10) such that a resonance chamber (22) for absorbing vibrations and noise of the coolant gas flowing through the silencer body tube (10) is defined between the outer circumferential surface of the silencer body tube (10) and the outer resonance tube (20), wherein the noise damper body tube (10) is configured such that it limits the amount of compressor-lubricating oil that accumulates in the resonance chamber (22), characterized by the fact that at least one of the resonance holes (12) is arranged in a region of the resonance chamber (22) that is lowest in the direction of gravity, so that the oil lubricating the compressor, which enters the resonance chamber (22) and flows downwards in the direction of gravity, flows through at least one of the resonance holes (12) into the silencer body tube (10).

Description

Field of the invention

[0001] The present invention relates to a noise damper for a vehicle air conditioning system, and more particularly, to a noise damper for a vehicle air conditioning system capable of efficiently reducing vibration and noise of a compressor without impairing the fluidity of a refrigerant and thereby suppressing stagnation of a lubricant for the compressor. Background of the invention

[0002] Noise is a major cause of reduced vehicle ride comfort. There are many different types of noise generated in a motor vehicle, including air conditioning noise. Air conditioning noise is generated by the compression of refrigerant in a compressor. When this noise is introduced into the vehicle cabin, the vehicle's ride comfort is significantly reduced.

[0003] In particular, vibrations and noise generated in a compressor are transmitted into a vehicle compartment along the refrigerant and refrigerant line. Due to these transmitted vibrations and noises, vehicle occupants experience significant stress and fatigue. Thus, vibrations and noise reduce vehicle driving comfort and significantly impede safe driving. Accordingly, it is necessary to reduce the noise generated by the compressor of the vehicle air conditioning system to improve vehicle driving comfort and ensure safe driving.

[0004] As a method for reducing noise generated in a compressor, a technology is available in which a noise damper is installed in a refrigerant line connected to the compressor.

[0005] As in Fig. As shown in Figure 1, this technology utilizes the Helmholtz resonance principle and has a structure in which a resonance tube 3 is installed within a coolant passage 1. The resonance tube 3 includes a coolant introduction part 5, a neck part 7 whose diameter gradually decreases from the coolant introduction part 5, and a coolant discharge part 9 whose diameter gradually increases from the neck part 7. A resonance chamber 7a is defined between the outer peripheral surface of the neck part 7 and the inner peripheral surface of the coolant passage 1.

[0006] During a process of introducing and discharging a high-temperature and high-pressure refrigerant gas in this resonance tube 3, vibrations and noise in the resonance chamber 7a are absorbed through a resonance hole 7b formed in the neck portion 7. As a result, the vibrations and noise generated in the compressor are prevented from being transmitted to the interior of a vehicle via the refrigerant and the refrigerant line. This makes it possible to prevent deterioration of vehicle driving comfort, which may be caused by the vibrations and noise generated in the compressor.

[0007] In the above-mentioned conventional air conditioning system, the high-temperature and high-pressure refrigerant gas should pass through the small-diameter resonance pipe 3. This leads to a sharp drop in the fluidity of the refrigerant, which in turn leads to a decrease in the cooling performance of the vehicle compartment.

[0008] Oil for lubricating the compressor is contained in the refrigerant gas. As in Fig. As shown in Figure 2, the oil passing through the throat portion 7 of the resonance tube 3 is introduced through the resonance hole 7b and stagnates in the resonance chamber 7a, as indicated by "A." This reduces the power of the compressor and significantly reduces the noise absorption performance of the resonance chamber 7a.

[0009] In particular, oil shortage occurs in the compressor due to oil stagnation in the resonance chamber 7a. This can drastically reduce compressor performance and cause compressor malfunctions.

[0010] The stagnation of oil in the resonance chamber 7a leads to a decrease in the effective volume of the resonance chamber 7a and a sharp reduction in the noise absorption performance of the resonance chamber 7a. As a result, the efficiency of reducing noise and vibration of the compressor is significantly reduced. US 8 434 586 B2 discloses a silencer device for a refrigerant circuit with refrigerant containing refrigerant oil, comprising a housing in which an upper silencer chamber and a lower silencer chamber are arranged, wherein the upper silencer chamber has an upper inlet opening connectable to the refrigerant circuit and the lower silencer chamber has a lower outlet opening connectable to the refrigerant circuit, and wherein a silencer partition wall is arranged between the upper and lower silencer chambers, said partition wall having at least one silencer pipe connecting the upper silencer chamber to the lower silencer chamber, the upper section of which projects into the upper silencer chamber with an upper opening, wherein, at a fill level which exceeds the height of the upper opening, refrigerant oil accumulated on the upper side of the silencer partition wall can be fed with refrigerant vapor to the lower silencer chamber.

[0011] JP H11-62 827 A discloses a muffler for a hermetic compressor which effectively suppresses a noise caused by a pulsating sound generated by a compression part of the hermetic compressor. Summary of the invention

[0012] In view of the above-mentioned problems, it is an object of the present invention to provide a noise damper for a vehicle air conditioning system capable of efficiently absorbing vibrations and noises of a compressor transmitted through a refrigerant and a refrigerant line without impairing refrigerant flowability.

[0013] Another object of the present invention is to provide a noise damper for a vehicle air conditioning system capable of efficiently reducing vibration and noise of a compressor without impairing the performance of cooling a vehicle compartment.

[0014] Another object of the present invention is to provide a noise damper for a vehicle air conditioning system capable of efficiently absorbing vibrations and noises of a compressor transmitted through a refrigerant and a refrigerant line while preventing oil clogging.

[0015] Yet another object of the present invention is to provide a noise damper for a vehicle air conditioning system capable of suppressing a reduction in compressor performance and a reduction in vibration / noise absorption rate that may be caused by oil stagnation.

[0016] To achieve the above objects, the present invention provides a noise damper for a vehicle air conditioning system according to claim 1, which is designed to reduce noise and vibration transmitted into a vehicle compartment along refrigerant lines (30). The subclaims relate to preferred embodiments of the invention.

[0017] The disclosed silencer has the following features: a silencer body tube installed between the coolant lines so that a coolant gas flowing along the coolant lines passes through the silencer body tube, the silencer body tube including one or more resonance holes formed on an outer peripheral surface of the silencer body tube; and an outer resonance tube installed on the outer peripheral surface of the silencer body tube such that a resonance chamber for absorbing vibrations and noises of a coolant gas flowing through the silencer body tube is defined between the outer peripheral surface of the silencer body tube and the outer resonance tube; wherein the muffler body tube is configured to restrict compressor lubricating oil introduced into the resonance chamber through the resonance holes from stagnating in the resonance chamber. In the silencer for a vehicle air conditioning system according to the present invention, the resonance chamber is formed outside the silencer body tube. This makes it possible to efficiently absorb vibrations and noise of a refrigerant gas without reducing the inner diameter of the silencer body tube.

[0018] Since the vibration and noise of the coolant gas can be efficiently absorbed without reducing the inner diameter of the silencer body pipe, it is possible to efficiently absorb the vibration and noise of the coolant gas without affecting the fluidity of the coolant gas flowing through the coolant line.

[0019] As far as the vibration and noise of the refrigerant gas can be efficiently absorbed without affecting the fluidity of the refrigerant gas, it is possible to effectively reduce the vibration and noise of the compressor without affecting the performance of cooling the space of a vehicle.

[0020] According to the present invention, the oil introduced into the resonance chamber is allowed to flow down by gravity and be discharged to the silencer body tube and the coolant line. Therefore, it is possible to prevent oil stagnation in the resonance chamber.

[0021] Since the clogging of oil in the resonance chamber can be prevented, it is possible to suppress a reduction in compressor performance and a reduction in vibration / noise absorption rate that may be caused by the clogging of oil in the resonance chamber.

[0022] The precise mounting position of the outer tuning pipe is marked in advance on the muffler body pipe. The outer tuning pipe is installed based on the marking. This allows the outer tuning pipe to be installed quickly and precisely in the correct position.

[0023] As far as the outer resonance tube can be quickly and accurately mounted in the correct position, it is possible to perform the step of mounting the outer resonance tube in a simple and quick manner and to position the outer resonance tube precisely with respect to the resonance hole.

[0024] Since the work of attaching the outer resonance tube can be performed in an easy and fast manner and since the outer resonance tube can be accurately arranged in a correct position, it is possible to increase productivity and significantly improve the noise absorption performance of the silencer. Short description of the drawings

[0025] The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings. Fig. 1 is a sectional view showing a conventional noise damper for a vehicle air conditioning system. Fig. 2 is a sectional view taken along the line II - II in Fig. 1. Fig. 3 is a sectional view showing a noise damper for a vehicle air conditioning system according to a first embodiment of the present invention. Fig. 4 is a sectional view showing a noise damper for a vehicle air conditioning system according to a second embodiment of the present invention. Fig. 5 is a sectional view showing a noise damper for a vehicle air conditioning system according to a third embodiment of the present invention. Fig. 6 is a sectional view showing a noise damper for a vehicle air conditioning system according to a fourth embodiment of the present invention. Fig. 7 is a sectional view taken along a line VII - VII in Fig. 6. Fig. 8 to 10 are views showing various modified examples of the resonance hole in a noise damper according to the fourth embodiment. Fig. 11 is a sectional view showing a noise damper for a vehicle air conditioning system according to a fifth embodiment of the present invention. Fig. 12 is a sectional view showing a noise damper for a vehicle air conditioning system according to a sixth embodiment of the present invention. Detailed description of the preferred embodiments

[0026] Certain preferred embodiments of a noise damper for a vehicle air conditioning system according to the present invention will now be described in detail with reference to the accompanying drawings. [First embodiment]

[0027] Referring to Fig. 3, a noise attenuator for a vehicle air conditioning system according to the present invention includes a noise attenuator body tube 10 and an outer resonance tube 20 installed on the outer peripheral surface of the noise attenuator body tube 10.

[0028] The silencer body tube 10 is arranged between the coolant lines 30 and has the same inner diameter B as the coolant lines 30. A high-temperature and high-pressure coolant gas flowing through the coolant lines 30 is introduced into the silencer body tube 10. Since the silencer body tube 10 has an inner diameter B equal to the inner diameter of the coolant lines 30, the coolant gas flowing through the coolant lines 30 passes through the silencer body tube 10 with little flow resistance. This means that the silencer body tube 10 does not impair the flowability of the coolant gas flowing through it.

[0029] The silencer body tube 10 is installed at an inclination of a specific angle Θ with respect to a floor surface. For example, the silencer body tube 10 is installed at an angle of approximately 90 degrees with respect to the floor surface. In the present invention, the silencer body tube 10 is formed independently of the coolant lines 30 and is installed between the coolant lines 30. However, if necessary, the coolant lines 30 can be used as the silencer body tube 10. In this case, it is possible to reduce the manufacturing costs and the number of manufacturing steps. This helps to save the costs involved in manufacturing the silencer.

[0030] The outer resonance tube 20 is fixedly attached to the outer peripheral surface of the silencer body tube 10, which has a specific inclination angle Θ with respect to the bottom surface. The intermediate portion of the outer resonance tube 20 is spatially spaced from the outer peripheral surface of the silencer body tube 10. The opposite end portions of the outer resonance tube 20 are hermetically fixed to the outer peripheral surface of the silencer body tube 10. Thus, a resonance chamber 22 is defined between the silencer body tube 10 and the outer resonance tube 20.

[0031] The outer resonance tube 20 includes end fixing parts 20a having a diameter smaller than the diameter of the intermediate part thereof. The end fixing parts 20a are welded to the outer peripheral surface of the muffler body tube 10 such that the intermediate part of the outer resonance tube 20 is spatially spaced from the outer peripheral surface of the muffler body tube 10.

[0032] In the present invention, the silencer body tube 10 has one or more resonance holes 12 formed in its thickness direction. The resonance holes 12 are formed to extend from the interior of the silencer body tube 10 toward the resonance chamber 22, so that vibrations and noises of a coolant gas flowing through the silencer body tube 10 are transmitted into the resonance chamber 22 and absorbed by it.

[0033] Accordingly, it is possible to prevent vibrations and noises of the refrigerant gas from being transmitted into a space of a vehicle along the refrigerant pipes 30. This makes it possible to suppress deterioration of comfort when driving a vehicle, which may be caused by the vibrations and noises of the refrigerant gas.

[0034] It is preferable that the number of resonance holes 12 be two or more. The resonance holes 12 are formed in the silencer body tube 10 so as to communicate with the resonance chamber 22. It is preferable that the resonance holes 12 are formed in a part of the silencer body tube 10 corresponding to a lower portion of the resonance chamber 22 in the direction of gravity, which has a length ℓ of one-half or less of the total length L of the resonance chamber 22.

[0035] Even more preferably, the resonance holes 12 are formed in a part of the silencer body tube 10 which corresponds to a lowest region of the resonance chamber 22 with the total length L in the direction of gravity.

[0036] The reason for adopting this configuration is to ensure that even when compressor lubricating oil mixed with the refrigerant gas is introduced into the resonance chamber 22, the oil is allowed to flow downward in the direction of gravity and be discharged into the muffler body tube 10 through the resonance holes 12.

[0037] This makes it possible to prevent the compressor lubricating oil from clogging in the resonance chamber 22. As a result, it is possible to suppress a reduction in compressor performance and a reduction in the vibration / noise absorption rate that may be caused by clogging of the oil in the resonance chamber 22. [Second embodiment]

[0038] Next, a noise damper for a vehicle air conditioning system according to a second embodiment of the present invention will be described with reference to Fig. 4 described.

[0039] In the silencer according to the second embodiment, the silencer body tube 10 is installed at an angle of approximately 60 degrees with respect to the floor surface. Since the silencer body tube 10 is installed at an angle of approximately 60 degrees in this manner, the outer resonance tube 20 existing around the silencer body tube 10 is also installed at an angle of approximately 60 degrees with respect to the floor surface. Therefore, the silencer as a whole is installed at an angle of approximately 60 degrees with respect to the floor surface.

[0040] According to the silencer, which as described above is the same as the one in Fig. 3, it is possible to prevent the compressor lubricating oil from clogging in the resonance chamber 22. As a result, it is possible to suppress a reduction in compressor performance and a reduction in the vibration / noise absorption rate that may be caused by clogging of the oil in the resonance chamber 22. [Third Embodiment]

[0041] Next, a noise damper for a vehicle air conditioning system according to a third embodiment of the present invention will be described with reference to Fig. 5 described.

[0042] In the silencer according to the third embodiment, the silencer body tube 10 has a plurality of resonance holes 12. The resonance holes 12 include a resonance hole 12a formed in a lower part of the silencer body tube 10 in the direction of gravity and a resonance hole 12b formed in a upper part of the silencer body tube 10 in the direction of gravity.

[0043] Specifically, the resonance hole 12a is formed in a lowermost part of the silencer body tube 10 in the direction of gravity. The resonance hole 12b is formed in a higher part of the silencer body tube 10 in the direction of gravity.

[0044] The reason for adopting this configuration is to ensure that, even when the silencer body tube 10 is upside down during the assembly process of the silencer body tube 10 with the coolant pipe 30, at least one of the resonance holes 12 is always located on the lower side of the resonance chamber 22 in the direction of gravity. This ensures that the oil introduced into the resonance chamber 22 is easily discharged from the resonance chamber 22.

[0045] Accordingly, even when the silencer body tube 10 is upside down during an assembly process, it is possible to prevent the compressor lubricating oil from clogging within the resonance chamber 22. As a result, it is possible to suppress a reduction in compressor performance and a reduction in the vibration / noise absorption rate that may be caused by clogging of the oil in the resonance chamber 22. [Fourth Embodiment]

[0046] Next, a noise damper for a vehicle air conditioning system according to a fourth embodiment of the present invention will be described with reference to Fig. 6 to 9 described.

[0047] Referring to Fig. 6, the silencer according to the fourth embodiment includes a silencer body pipe 10 installed horizontally in a parallel relationship with the floor surface.

[0048] Since the muffler body tube is installed horizontally in this manner, the outer resonance tube 20 surrounding the muffler body tube 10 is also installed horizontally. Thus, the muffler as a whole is installed horizontally in a parallel relationship with the floor surface.

[0049] In the silencer according to the fourth embodiment, the silencer body tube 10 has a plurality of resonance holes 12 formed therethrough. The resonance holes 12 include a resonance hole 12c formed in a bottom surface portion of the silencer body tube 10 corresponding to a lowermost region of the resonance chamber 22 in the direction of gravity.

[0050] When compressor lubricating oil mixed in the refrigerant gas is introduced into the resonance chamber 22 through the resonance holes 12, the oil stagnates within the resonance chamber 22 and accumulates to a level of the resonance hole 12c as shown in Fig. 7. By forming the resonance hole 12c at the lowest position in the direction of gravity, it is possible to lower the level of oil stagnating within the resonance chamber 22. This makes it possible to minimize the amount of oil stagnating within the resonance chamber 22. As a result, it is possible to suppress a reduction in compressor performance and a reduction in the vibration / noise absorption rate that may be caused by oil stagnation in the resonance chamber 22.

[0051] The resonance holes 12 further include a resonance hole 12d, which is preferably formed higher than the resonance hole 12c formed in the bottom surface portion of the silencer body tube 10. Even more preferably, the resonance hole 12d is formed in an uppermost surface portion of the silencer body tube 10, which corresponds to a gravity-uppermost portion of the resonance chamber 22.

[0052] There is a fear that the resonance hole 12c formed in the bottom surface part of the silencer body tube 10 will be clogged by the oil stagnating in the resonance chamber 22. In this case, vibrations and noises generated in the silencer body tube 10 can be transmitted into the resonance chamber 22 through the resonance hole 12d formed in the top surface part of the silencer body tube 10, rather than through the clogged resonance hole 12c formed in the bottom surface part of the silencer body tube 10.

[0053] It is most preferable that the resonance hole 12d is formed in the uppermost surface part of the silencer body tube 10. In some cases, as in the Fig. 8 and Fig. 9, the resonance hole 12d may be formed in the side surface part of the silencer body tube 10.

[0054] In Fig. 10 shows a modified example of the resonance holes 12 formed in the muffler body tube 10. The resonance holes 12 according to the modified example include a resonance hole 12c formed in a lower right part of the muffler body tube 10 and a resonance hole 12d formed in an upper left part of the muffler body tube 10.

[0055] Specifically, the resonance hole 12c is formed in a lowermost right part of the silencer body tube 10 in the direction of gravity. The resonance hole 12d is formed in a topmost left part of the silencer body tube 10 in the direction of gravity.

[0056] The reason for adopting this configuration is to ensure that even if the muffler body pipe 10 is rotated by 180 degrees in the left-right direction in a process of assembling the muffler body pipe 10 with the coolant pipes 30, a worker can appropriately deal with the situation. [Fifth performance form]

[0057] Next, a noise damper for a vehicle air conditioning system according to a fifth embodiment of the present invention will be described with reference to Fig. 11 described.

[0058] In the silencer according to the fifth embodiment, the silencer body tube 10 includes a mounting position indicating part 40 formed on an outer peripheral surface thereof. The mounting position indicating part 40 is configured to indicate a right position of the outer resonance tube 20 with respect to the resonance holes 12. The mounting position indicating part 40 is formed, for example, by a projection bead 42 projecting radially outward from the outer peripheral surface of the silencer body tube 10.

[0059] Before mounting the outer resonance tube 20 to the muffler body tube 10, the protrusion bead 42 is formed in accordance with a right position of the outer resonance tube 20 relative to the resonance holes 12. Specifically, the protrusion bead 42 is previously formed in one of two axially spaced portions of the muffler body tube 10, corresponding to the right position of the outer resonance tube 20.

[0060] When the outer resonance tube 20 is fitted to the outer peripheral surface of the muffler body tube 10, an end portion of the outer resonance tube 20 is stopped by the protrusion bead 42 of the mounting position indicating portion 40. This allows a worker to accurately detect the mounting position of the outer resonance tube 20 relative to the resonance holes 12. Accordingly, the worker can mount the outer resonance tube 20 in a precise position relative to the resonance holes 12. As a result, the resonance holes 12 and the resonance chamber 22 are precisely arranged in a predetermined positional relationship with each other. This makes it possible to improve the noise absorption performance of the resonance chamber 22, thereby significantly increasing the noise absorption performance of the muffler.

[0061] The protrusion bead 42 of the mounting position indicating part 40 is formed to protrude radially outward by subjecting the muffler body tube 10 to a molding process. An end fixing part 20a of the outer resonance tube 20 is welded to the thus formed protrusion bead 42. Thus, the outer resonance tube 20, positioned in the mounting position, is fixedly attached to the outer peripheral surface of the muffler body tube 10.

[0062] A circumferentially extending welding groove 14 is formed on the outer peripheral surface of the silencer body tube 10 at a position corresponding to the end fixing portion 20a of the outer resonance tube 20. The welding groove 14 is formed to protrude radially inward by subjecting the silencer body tube 10 to a molding process. The welding groove 14 is formed on the outer peripheral surface of the silencer body tube 10 between the end fixing portion 20a of the outer resonance tube 20 and the projection bead 42.

[0063] When the end fixing portion 20a of the outer resonance tube 20 is welded to the protrusion bead 42, molten weld metal is accommodated in the welding groove 14. Specifically, the welding groove 14 allows the molten weld metal to flow into the area between the end fixing portion 20a of the outer resonance tube 20 and the muffler body tube 10. Thus, the end fixing portion 20a of the outer resonance tube 20 and the muffler body tube 10 are reliably welded together. This increases the welding reliability of the outer resonance tube 20 and the muffler body tube 10.

[0064] According to the silencer of the fifth embodiment, the precise mounting position of the outer resonance tube 20 is pre-marked on the silencer body tube 10, and the outer resonance tube 20 is mounted based on the marking. This makes it possible to easily and quickly mount the outer resonance tube 20 in a mounting position.

[0065] Since the outer resonance tube 20 can be easily and quickly mounted in an assembly position, it is possible to easily and quickly perform the assembly work of the outer resonance tube 20 and accurately position the outer resonance tube 20 with respect to the resonance holes 12. This makes it possible to increase productivity and significantly improve the noise absorption performance of the silencer. [Sixth Embodiment]

[0066] Next, a noise damper for a vehicle air conditioning system according to a sixth embodiment of the present invention will be described with reference to Fig. 12 described.

[0067] In the muffler according to the sixth embodiment, the muffler body tube 10 includes two mounting position indicating parts 40 formed at two points on an outer peripheral surface thereof. Specifically, the mounting position indicating parts 40 are formed at two points corresponding to the mounting position of the outer resonance tube 20.

[0068] The two mounting position indicating parts 40 are formed to protrude radially outward at two positions on the muffler body tube 10 in accordance with the mounting position of the outer resonance tube 20. When the outer resonance tube 20 is fitted onto the outer peripheral surface of the muffler body tube 10, the opposite end parts of the outer resonance tube 20 are aligned with the two mounting position indicating parts 40.

[0069] This allows a worker to clearly identify a mounting position of the outer resonance tube 20 relative to the resonance holes 12. Accordingly, the worker can mount the outer resonance tube 20 in an accurate position relative to the resonance holes 12. As a result, the resonance holes 12 and the resonance chamber 22 are precisely arranged in a predetermined positional relationship with each other.

[0070] The two mounting position indicating parts 40 of the present embodiment have the same structure as the mounting position indicating part 40 of the fifth embodiment. The welding structure of the muffler body tube 10 and the outer resonance tube 20 is also identical to the welding structure described above with respect to the fifth embodiment. Therefore, a detailed description thereof will be omitted.

[0071] In the silencer according to the sixth embodiment, the two mounting position indicating parts 40 protrude radially outward from the two axially spaced-apart portions of the silencer body tube 10. For this reason, when the outer resonance tube 20 is mounted, the mounting position indicating parts 40 may hinder the mounting of the outer resonance tube 20, but the mounting position indicating parts 40 are in Fig.12 is shown at an exaggerated scale for clarity. In reality, the mounting position indicating parts 40 are sized such that during the assembly process, the outer resonance tube 20 is fitted into the area between the mounting position indicating parts 40 along the outer peripheral surface of the muffler body tube 10 as a result of the fact that the outer resonance tube 20 is elastically deformed radially outward.

Claims

[1] A noise damper for a vehicle air conditioning system, designed to reduce noise and vibration transmitted along refrigerant lines (30) in a vehicle compartment, the noise damper comprising: a silencer body tube (10) installed between the coolant lines (30) so that a coolant gas flowing along the coolant lines (30) passes through the silencer body tube (10), the silencer body tube (10) having a plurality of resonance holes (12), an outer resonance tube (20) installed on the outer peripheral surface of the silencer body tube (10) such that a resonance chamber (22) for absorbing vibrations and noises of the coolant gas flowing through the silencer body tube (10) is defined between the outer peripheral surface of the silencer body tube (10) and the outer resonance tube (20), wherein the silencer body tube (10) is configured to restrict compressor lubricating oil from clogging in the resonance chamber (22), characterized by , that at least one of the resonance holes (12) is arranged in a lowest region of the resonance chamber (22) in the direction of gravity, so that the oil lubricating the compressor, which penetrates into the resonance chamber (22) and flows downwards in the direction of gravity, flows out through at least one of the resonance holes (12) into the silencer body tube (10). [2] Noise damper according to claim 1, characterized by that the silencer body tube (10) is installed obliquely at a predetermined angle with respect to the direction of gravity so that at least one of the resonance holes (12) is arranged lower in the direction of gravity than the remaining resonance holes (12). [3] Noise damper according to claim 2, characterized bythat at least one of the remaining resonance holes (12) is formed in a part of the silencer body tube (10) which corresponds to a lower region of the resonance chamber (22) in the direction of gravity, which has a length of one half or less of the total length (L) of the resonance chamber (22). [4] Noise damper according to claim 3, characterized by that the resonance holes (12) are formed in a part of the silencer body tube (10) which corresponds to a lowest region of the resonance chamber (22) in the direction of gravity. [5] Noise damper according to claim 2, characterized by that at least one of the remaining resonance holes (12) is formed in an uppermost region of the resonance chamber (22) in the direction of gravity. [6] Noise damper according to claim 1, characterized bythat the silencer body tube (10) has a mounting position indicating part (40) formed to indicate a mounting position of the outer resonance tube (20) relative to the resonance holes (12); and characterized by in that the mounting position indicating part (40) has a projection bead (42) formed to protrude from a part of the outer peripheral surface of the silencer body tube (10) and corresponding to the mounting position of the outer resonance tube (20). [7] Noise damper according to claim 6, characterized by in that the mounting position indicating part (40) has two projection beads (42) formed to project from two axially spaced apart portions of the silencer body tube (10) corresponding to the mounting positions of both ends of the outer resonance tube (20). [8] Noise damper according to claim 6, characterized bythat the projection bead (42) is formed to project radially outward by subjecting the silencer body tube (10) to a molding process, wherein the outer resonance tube (20) is welded onto the projection bead (42). [9] Noise damper according to claim 6, characterized by that the silencer body tube (10) further comprises a welding groove (14) formed on the outer peripheral surface of the silencer body tube (10) so as to accommodate a molten welding metal when the outer resonance tube (20) is welded onto the projection bead (42). [10] Noise damper according to claim 1, characterized by that the silencer body tube (10) is equal to the coolant lines (30) in terms of its inner diameter (B).

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