Scroll type fluid machine

Abstract

To provide a screw type fluid machine capable of enhancing a silencing effect.SOLUTION: The scroll type compression machine includes a fixed scroll 11 having a spiral lap 11b, a turning scroll 12 having a spiral lap 12b, a drive shaft 13 for turning the turning scroll 12 with respect to the fixed scroll 11, a centrifugal impeller 18 attached to the drive shaft 13, a casing 19 for accommodating the centrifugal impeller 18, an even number of resonance chambers 22 disposed so as not to overlap a position of the centrifugal impeller 18 in an axial direction of the drive shaft 13, and an even number of communication holes 23 for communicating the even number of resonance chambers 22 with a flow path formed on an outer peripheral side of the centrifugal impeller 18 in the casing 19. The even number of communication holes 23 are not provided at the position of the tip P of the 19a of the tongue part of the casing 19 in the circumferential direction around the rotation center O of the centrifugal impeller 18, and are arranged symmetrically around the rotation center O of the centrifugal impeller 18.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a scroll-type fluid machine. [Background technology]

[0002] A scroll compressor, which is one type of scroll-type fluid machine, includes a fixed scroll having a spiral wrap, an orbiting scroll having a spiral wrap, a drive shaft that rotates the orbiting scroll relative to the fixed scroll, and a plurality of working chambers formed between the wrap of the orbiting scroll and the wrap of the fixed scroll. Each working chamber moves along the wrap of the orbiting scroll as the orbiting scroll rotates, compressing gas and finally discharging the compressed gas.

[0003] The fixed scroll and the orbiting scroll are heated by heat generated by the compression of the gas. The scroll compressor of Patent Document 1 is configured to cool the fixed scroll and the orbiting scroll. In detail, it includes a centrifugal impeller (fan rotor) attached to a drive shaft, a casing (volute) that houses the centrifugal impeller, and a duct (outlet bend) that is connected to the casing and directs cooling air generated by the centrifugal impeller to the back of the fixed scroll and the back of the orbiting scroll. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-129152 Summary of the Invention [Problem to be solved by the invention]

[0005] Within the casing, noise is generated by the rotation of the centrifugal impeller and the flow of cooling air, and this noise is amplified by resonance caused by the structure of the flow passages within the casing. Therefore, it is conceivable to provide a resonance chamber that damps noise through resonance and a communication hole that connects the resonance chamber to the flow passages within the casing. However, depending on the arrangement of the resonance chamber and the communication hole, the noise damping effect may not be sufficient.

[0006] The present invention has been made in view of the above circumstances, and one of its objects is to improve the noise reduction effect. [Means for solving the problem]

[0007] The present invention includes a plurality of means for solving the above-mentioned problems, and one example thereof is a scroll-type fluid machine including a fixed scroll having a spiral wrap, an orbiting scroll having a spiral wrap, a plurality of working chambers formed between the wrap of the fixed scroll and the wrap of the orbiting scroll, a drive shaft for orbiting the orbiting scroll relative to the fixed scroll, a centrifugal impeller inserted into and attached to the drive shaft, and a casing that houses the centrifugal impeller, the scroll-type fluid machine further including an even number of resonance chambers that are arranged so as not to overlap with the centrifugal impeller in the axial direction of the drive shaft and that muffle noise by resonance, and an even number of communication holes that connect the even number of resonance chambers to flow paths formed on the outer periphery of the centrifugal impeller in the casing, the even number of communication holes being not provided at positions at the tips of a tongue portion of the casing in the circumferential direction centered on the center of rotation of the centrifugal impeller, and being arranged so as to be symmetrical about the center of rotation of the centrifugal impeller. [Effects of the Invention]

[0008] According to the present invention, the noise reduction effect can be improved.

[0009] Problems, configurations, and effects other than those described above will become clear from the following description. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an axial cross-sectional view illustrating the structure of a scroll compressor according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view taken along the line II-II in FIG. 1, showing the arrangement of centrifugal impellers. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1, illustrating the arrangement of the resonance chambers, communication holes, and the like. [Figure 4] 4 is a cross-sectional view taken along the line IV-IV in FIG. 3, illustrating the structure of the resonance chamber and the communication hole. [Figure 5] FIG. 2 is an exploded view showing the structure of a resonance chamber and a communication hole in an embodiment to which the present invention is applied. [Figure 6] FIG. 10 is a diagram showing a first-order standing wave occurring in the circumferential direction of a casing in an embodiment to which the present invention is applied. [Figure 7] FIG. 10 is a diagram showing a secondary standing wave occurring in the circumferential direction of a casing in an embodiment to which the present invention is applied. [Figure 8] FIG. 10 is an exploded view showing the structure of a resonance chamber and a communication hole in a modified example to which the present invention is applied. [Figure 9] FIG. 10 is a cross-sectional view showing the structure of a resonance chamber and a communication hole in another modified example to which the present invention is applied. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment to which the present invention is applied will be described with reference to the drawings.

[0012] FIG. 1 is an axial cross-sectional view showing the structure of a scroll compressor according to this embodiment. FIG. 2 is a cross-sectional view taken along arrows II-II in FIG. 1, showing the arrangement of a centrifugal impeller (however, the centrifugal impeller blades, drive shaft, etc. are omitted). FIG. 3 is a cross-sectional view taken along arrows III-III in FIG. 1, showing the arrangement of a resonance chamber, communication holes, etc. (however, the drive shaft, housing, etc. are omitted). FIG. 4 is a cross-sectional view taken along arrows IV-IV in FIG. 3, showing the structure of the resonance chamber and communication holes. The outline arrows in FIGS. 1 and 2 indicate the flow of cooling air.

[0013] The scroll compressor of this embodiment includes a housing 10, a fixed scroll 11, an orbiting scroll 12, and a drive shaft 13. The fixed scroll 11 is connected to the open end side (upper side in FIG. 1 ) of the housing 10. The orbiting scroll 12 is accommodated within the housing 10 and faces the fixed scroll 11. The drive shaft 13 is rotatably supported by a bearing 14 within the housing 10.

[0014] The fixed scroll 11 has a substantially circular flat plate 11a, a spiral wrap 11b standing on one side of the flat plate 11a (the lower side in FIG. 1), and a plurality of fins 11c standing on the opposite side of the flat plate 11a (the upper side in FIG. 1). The plurality of fins 11c extend in the left-right direction in FIG. 1 and are spaced apart from one another in a direction perpendicular to the plane of the paper in FIG. 1. An intake passage (not shown) is formed in a radially outer portion of the fixed scroll 11, and a discharge passage 11d is formed in a radially central portion of the fixed scroll 11.

[0015] The orbiting scroll 12 has a substantially circular flat plate 12a, a spiral wrap 12b standing on one side of the flat plate 12a (upper side in FIG. 1), a plurality of fins 12c standing on the opposite side of the flat plate 12a (lower side in FIG. 1), and a plate 12d provided on the tip side of the plurality of fins 12c (lower side in FIG. 1). The plurality of fins 12c extend in the left-right direction in FIG. 1 and are spaced apart from one another in a direction perpendicular to the plane of the paper in FIG. 1.

[0016] A crank portion 15 is provided on one end side (upper side in FIG. 1) of the drive shaft 13. The center of the crank portion 15 is eccentric from the center of the drive shaft 13, and is connected to a boss portion of the plate 12d of the orbiting scroll 12 via an orbiting bearing 16.

[0017] The other end of drive shaft 13 (the lower side in FIG. 1) protrudes outside housing 10 and is provided with pulley 17. A belt (not shown) is stretched between pulley 17 and a pulley (not shown) provided on a rotating shaft (not shown) of the electric motor. As a result, the rotational force of the electric motor is transmitted to pulley 17, causing drive shaft 13 to rotate and orbiting scroll 12 to orbit relative to fixed scroll 11. A rotation prevention mechanism for preventing orbiting scroll 12 from rotating on its own axis is provided within housing 10.

[0018] A plurality of working chambers are formed between the wrap 11b of the fixed scroll 11 and the wrap 12b of the orbiting scroll 12. As the orbiting scroll 12 orbits, each working chamber moves from the outside to the inside in the wrap extension direction (in other words, from the radially outer portion of the fixed scroll 11 toward the center) and sequentially performs a suction process, a compression process, and a discharge process. The working chamber during the suction process draws in air (gas) through an intake filter (not shown) and the suction flow path of the fixed scroll 11. The working chamber during the compression process compresses the air. The working chamber during the discharge process discharges compressed air (compressed gas) through the discharge flow path 11d of the fixed scroll 11.

[0019] The fixed scroll 11 and the orbiting scroll 12 are heated by heat generated by the compression of air. The scroll compressor of this embodiment includes a centrifugal impeller 18, a casing 19, and a duct 20 to cool the fixed scroll 11 and the orbiting scroll 12. The housing 10 has a plurality of (e.g., three or four) fixed portions 10a arranged spaced apart from one another in the circumferential direction centered on the drive shaft 13. The casing 19 is fixed to the plurality of fixed portions 10a by a plurality of bolts 21 (fixing devices). The duct 20 is connected to the casing 19.

[0020] The casing 19 houses the centrifugal impeller 18 and forms a flow path on the outer periphery of the centrifugal impeller 18. As shown in Fig. 2, the width W of the flow path inside the casing 19 (more specifically, the distance between the outer edge of the centrifugal impeller 18 and the inner wall of the casing 19 in the radial direction of the centrifugal impeller 18) is shortest at the position where the tip P of the tongue portion 19a of the casing 19 is located, and increases in the clockwise direction in Fig. 2.

[0021] The centrifugal impeller 18 is attached to the drive shaft 13 by being inserted therethrough and rotates together with the drive shaft 13. As a result, air is sucked in through an inlet 19b (see FIG. 3) of the casing 19, generating cooling air. The cooling air generated by the centrifugal impeller 18 flows through a flow path within the casing 19 in the clockwise direction in FIG. 2 and is led through a duct 20 to the back of the fixed scroll 11 (specifically, the flow path between the multiple fins 11c) and the back of the orbiting scroll 12 (specifically, the flow path between the multiple fins 12c). As a result, the fixed scroll 11 and the orbiting scroll 12 are cooled.

[0022] Incidentally, noise is generated within the casing 19 by the rotation of the centrifugal impeller 18 and the flow of cooling air, and this noise is amplified by resonance caused by the structure of the flow passages within the casing 19. That is, standing waves with frequencies of 1 kHz or less are generated in the circumferential direction of the casing 19 (in other words, in the circumferential direction around the rotation center O of the centrifugal impeller 18), amplifying the noise. An n-th order standing wave has n wavelengths around the entire circumference of the casing 19, and its frequency fn can be calculated by the following equation (1). In the equation, L is the length of the flow passage in the circumferential direction of the casing 19, and c is the speed of sound. fn=n×c / L (1)

[0023] According to the conditions of this embodiment (i.e., the length L of the flow path in the circumferential direction of the casing 19), a primary standing wave (see FIG. 6) and a secondary standing wave (see FIG. 7) are generated as standing waves with a frequency of 1 kHz or less. The horizontal axes in FIGS. 6 and 7 represent the circumferential position of the casing 19, shown as an angle around the center of rotation O of the centrifugal impeller 18, with the angle at which the tip P of the tongue portion 19a of the casing 19 is located being set to 0 degrees. The vertical axes in FIGS. 6 and 7 represent sound pressure.

[0024] The flow path within the casing 19 has the fastest flow velocity at the position of the tip P of the tongue 19a. Therefore, when a standing wave occurs in the circumferential direction of the casing 19, the position of the tip P of the tongue 19a becomes an antinode of the particle velocity (in other words, a point of large change). Because the particle velocity and the sound pressure are out of phase with each other by 90 degrees, the position of the tip P of the tongue 19a becomes a node of the sound pressure (in other words, a point of no change). Therefore, as shown in FIG. 6, the sound pressure nodes of the first-order standing wave are 0 degrees and 180 degrees, and the sound pressure antinodes are 90 degrees and 270 degrees. Also, as shown in FIG. 7, the sound pressure nodes of the second-order standing wave are 0 degrees, 90 degrees, 180 degrees, and 270 degrees, and the sound pressure antinodes are 45 degrees, 135 degrees, 225 degrees, and 315 degrees.

[0025] The scroll compressor of this embodiment includes an even number of resonance chambers 22 and communication holes 23 in order to reduce noise inside the casing 19. To explain in more detail, as shown in Fig. 5, for example, a cylindrical member 24 with a bottom is welded to the outside of the casing 19 (the upper side of Fig. 5), and the resonance chambers 22 are formed inside the member 24, and the communication holes 23 are formed in the casing 19. As a result, the even number of resonance chambers 22 are arranged so as not to overlap with the positions of the centrifugal impellers 18 in the axial direction of the drive shaft 13.

[0026] From the viewpoint of reducing noise inside the casing 19, it is preferable that an even number of communication holes 23 be arranged at positions close to antinodes of sound pressure, avoiding positions of nodes of sound pressure in standing waves of frequencies of 1 kHz or less that occur in the circumferential direction of the casing 19. Therefore, the even number of communication holes 23 are not provided at the position of the tip P of the tongue portion 19a in the circumferential direction of the casing 19, and are arranged symmetrically (e.g., at equal intervals) around the rotation center O of the centrifugal impeller 18. In particular, in this embodiment, in order to take into account both primary and secondary standing waves, the number of combinations of resonance chambers 22 and communication holes 23 is four, and the four communication holes 23 are arranged within ranges of 40 to 50 degrees, 130 to 140 degrees, 220 to 230 degrees, and 310 to 320 degrees around the rotation center O of the centrifugal impeller 18 (in other words, positions close to antinodes of sound pressure in the secondary standing wave), respectively.

[0027] As described above, in this embodiment, by providing the resonance chambers 22 and the communication holes 23 instead of using a sound-absorbing material, it is possible to effectively muffle standing waves with frequencies of 1 kHz or less that occur in the circumferential direction of the casing 19. Furthermore, by arranging the resonance chambers 22 and the communication holes 23 as described above, it is possible to enhance the sound-muffling effect. Furthermore, because the resonance chambers 22 and the communication holes 23 are not provided in positions where the sound-muffling effect is low (more specifically, positions of nodes of sound pressure in standing waves, including the position of the tip P of the tongue portion 19a), it is possible to reduce the number and size of the resonance chambers 22, and it is possible to reduce the size of the entire compressor.

[0028] Furthermore, in this embodiment, the resonance chamber 22 is arranged so as not to overlap with the centrifugal impeller 18 in the axial direction of the drive shaft 13. Therefore, unlike when the resonance chamber 22 is arranged so as to overlap with the centrifugal impeller 18 in the axial direction of the drive shaft 13, the influence on the flow of cooling air inside the casing 19 can be reduced.

[0029] In the above embodiment, the four communication holes 23 are respectively arranged within the ranges of 40 to 50 degrees, 130 to 140 degrees, 220 to 230 degrees, and 310 to 320 degrees around the rotation center O of the centrifugal impeller 18 (in other words, positions close to the antinodes of the sound pressure in the second-order standing wave), but this is not limiting. The four communication holes 23 may also be respectively arranged at 45 degrees, 135 degrees, 225 degrees, and 315 degrees around the rotation center O of the centrifugal impeller 18 (in other words, positions of the antinodes of the sound pressure in the second-order standing wave).

[0030] Furthermore, in the above embodiment, a case has been described in which a primary standing wave and a secondary standing wave are generated as standing waves with a frequency of 1 kHz or less, but this is not limiting. It may also be assumed that only a primary standing wave is generated as a standing wave with a frequency of 1 kHz or less. In this case, the number of combinations of resonance chambers 22 and communication holes 23 may be two, and the two communication holes 23 may be disposed within a range of 85 to 95 degrees and a range of 175 to 185 degrees around the rotation center O of the centrifugal impeller 18 (in other words, positions close to the antinodes of the sound pressure in the primary standing wave), respectively. Alternatively, the two communication holes 23 may be disposed at 90 degrees and 180 degrees around the rotation center O of the centrifugal impeller 18 (in other words, positions at the antinodes of the sound pressure in the primary standing wave), respectively.

[0031] In the above embodiment, the communication holes 23 are positioned a predetermined distance away from the outer edge of the centrifugal impeller 18 in the radial direction of the centrifugal impeller 18, as shown in Fig. 3 above, but this is not limiting. The communication holes 23 may be positioned midway between the outer edge of the centrifugal impeller 18 and the inner wall of the casing 19 in the radial direction of the centrifugal impeller 18.

[0032] In the above embodiment, the resonance chamber 22 is formed in a member 24 welded to the outside of the casing 19 and communicates with a flow path within the casing 19 via a communication hole 23 in the casing 19. However, this is not limiting. For example, as shown in FIG. 8, the resonance chamber 22 may be formed in a protruding portion 19c of the casing 19 and communicate with a flow path within the casing 19 via a communication hole 23 in a plate member 25 welded to the inside of the protruding portion 19c. Alternatively, as shown in FIG. 9, the resonance chamber 22 may be formed in a fixed portion 10a of the housing 10 (more specifically, around a bolt hole into which a bolt 21 is threaded) and communicate with a flow path within the casing 19 via a communication hole 23 in the casing 19. In this modification, the member 24 or the plate member 25 is not necessary, thereby reducing the number of parts.

[0033] Although the above description has been given taking a scroll compressor as an example of an application of the present invention, the present invention is not limited to this and may be applied to other scroll fluid machines (for example, a scroll vacuum pump). [Explanation of symbols]

[0034] 10...housing, 10a...fixed portion, 11...fixed scroll, 11b...wrap, 12...orbiting scroll, 12b...wrap, 13...drive shaft, 18...centrifugal impeller, 19...casing, 19a...tongue portion, 22...resonance chamber, 23...communicating hole

Claims

1. a fixed scroll having a spiral wrap; an orbiting scroll having a spiral wrap; a plurality of working chambers formed between the wrap of the fixed scroll and the wrap of the orbiting scroll; a drive shaft that rotates the orbiting scroll relative to the fixed scroll; a centrifugal impeller inserted and attached to the drive shaft; A scroll-type fluid machine comprising: a casing that houses the centrifugal impeller; an even number of resonance chambers that are arranged so as not to overlap with the centrifugal impeller in the axial direction of the drive shaft and that muffle noise by resonance; an even number of communication holes that communicate the even number of resonance chambers with a flow path formed on an outer periphery of the centrifugal impeller in the casing, A scroll-type fluid machine characterized in that the even number of communication holes are not provided at the tip of the tongue portion of the casing in the circumferential direction centered on the center of rotation of the centrifugal impeller, and are arranged symmetrically around the center of rotation of the centrifugal impeller.

2. The scroll type fluid machine according to claim 1, a housing that accommodates the orbiting scroll and has a plurality of fixing portions that fix the casing; A scroll-type fluid machine, wherein the even number of resonance chambers are formed in the plurality of fixed portions.

3. The scroll type fluid machine according to claim 1, A scroll-type fluid machine, characterized in that each of the even number of communication holes is located midway between the outer edge of the centrifugal impeller and the inner wall of the casing in the radial direction of the centrifugal impeller.

4. The scroll type fluid machine according to claim 1, The scroll-type fluid machine is characterized in that, when the angle at which the tip of the tongue portion of the casing is located around the center of rotation of the centrifugal impeller is set to 0 degrees, the even number of communication holes are arranged within ranges of 40 to 50 degrees, 130 to 140 degrees, 220 to 230 degrees, and 310 to 320 degrees, respectively.

5. The scroll type fluid machine according to claim 1, A scroll-type fluid machine, wherein the plurality of working chambers compress a gas.

6. a fixed scroll having a spiral wrap; an orbiting scroll having a spiral wrap; a plurality of working chambers formed between the wrap of the orbiting scroll and the wrap of the fixed scroll; a drive shaft that rotates the orbiting scroll relative to the fixed scroll; a centrifugal impeller inserted and attached to the drive shaft; A scroll-type fluid machine comprising: a casing that houses the centrifugal impeller; a resonance chamber that is arranged so as not to overlap with the centrifugal impeller in the axial direction of the drive shaft and that silences noise by resonance; a communication hole that communicates the resonance chamber with a flow path formed on an outer periphery of the centrifugal impeller in the casing, A scroll-type fluid machine characterized in that the communication holes are arranged at antinode positions of sound pressure in standing waves with frequencies of 1 kHz or less that occur in the circumferential direction around the center of rotation of the centrifugal impeller.

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