Rail vehicles

Abstract

To provide a railway car provided with a return duct in the ceiling for returning air in a passenger compartment to an air conditioner provided in a roof structure, effectively reducing low-frequency noise generated from the air conditioner and improving quietness in the passenger compartment. [Solution] A railway car 10 is provided with an air conditioner KT on a roof structure YK, and a return duct KD1 in the ceiling space that returns air RA in a passenger compartment 1 from an air intake 22 formed in a ceiling panel 2 to an RA opening KT2 of the air conditioner via a curved flow path KD11. A sound reflecting plate 4 with multiple through holes 41 is provided on the back side of the ceiling panel that forms the lower surface of the return duct, at a position below the vehicle facing the RA opening and spaced away from the ceiling panel toward the top of the vehicle, and the separation distance d1 between the ceiling panel and the sound reflecting plate is formed so as to gradually change.

Description

[Technical field]

[0001] The present invention relates to a railway vehicle, and more particularly to a railway vehicle equipped with a return duct in the ceiling for returning air inside the passenger compartment to an air conditioner provided in a roof structure. [Background technology]

[0002] Conventionally, return ducts that return air from inside the passenger compartment to air conditioners installed in the roof structure often connected the return air opening of the air conditioner (hereinafter referred to as the "RA opening") and the air intake formed in the ceiling panel in a straight line in the vertical direction of the vehicle, for reasons such as reducing pressure loss in the duct. However, in this case, the noise of the air conditioner (for example, the noise when the compressor is operating) is easily transmitted from the RA opening through the straight return duct into the passenger compartment, and noise inside the passenger compartment when the air conditioner is operating has become a problem.

[0003] In this regard, for example, Patent Document 1 discloses a railcar 100, as shown in Fig. 6, which includes a roof structure 103 having an air conditioner 101 mounted on the upper portion and a first opening 102 through which ventilation can be provided to the air conditioner 101, a ceiling member 105 stretched under the roof structure 103 to define the ceiling of a passenger compartment 104 and having a second opening 106 through which ventilation can be provided from the passenger compartment 104, and a return duct 107 that connects the first opening 102 and the second opening 106 and forms a flow path connecting the first opening 102 and the second opening 106, and the second opening 106 is not aligned with the first opening 102 in the height direction of the railcar 100, but is offset in the longitudinal direction or width direction of the railcar 100. A filter 106a and a porous plate 106b are provided in the second opening 106. In addition, a sound-absorbing straightening member 108 that smooths the flow of air 109 flowing through the flow path is provided in the plate material that constitutes the return duct 107. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-144167 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the return duct 107 of the railway vehicle 100 of Patent Document 1 has the following problems. That is, since the plate material constituting the return duct 107 is provided with a sound-absorbing straightening member 108 for smoothing the flow of air 109 flowing through the flow path, the noise of the air conditioner 101 is also smoothly propagated along the straightening member 108 inside the return duct 107, and there is a problem that the noise inside the passenger compartment 104 while the air conditioner is operating cannot be sufficiently reduced. In addition, since the sound-absorbing straightening member 108 is made of a sound-absorbing material (such as a porous material) formed in a plate or triangular shape, it can generally effectively reduce noise in the mid-to-high range, but there is a problem that it cannot sufficiently reduce low-frequency noise with a frequency of about 400 to 500 Hz or less, such as noise when the compressor of the air conditioner 101 is operating.

[0006] The present invention has been made to solve such problems, and aims to provide a railway vehicle equipped with a return duct in the ceiling that returns air inside the passenger compartment to an air conditioner installed in the roof structure, effectively reducing the low-frequency noise generated by the air conditioner and improving quietness inside the passenger compartment. [Means for solving the problem]

[0007] In order to achieve the above object, a railway vehicle according to the present invention has the following configuration. (1) A railway vehicle having an air conditioner installed in a roof structure and a return duct in the ceiling that returns air in the passenger compartment from an air intake formed in a ceiling panel through a curved flow path to the RA opening of the air conditioner, A sound reflecting plate having a plurality of through holes is provided on the back surface side of the ceiling panel constituting the lower surface of the return duct, at a position below the vehicle facing the RA opening and spaced from the ceiling panel above the vehicle, The distance between the ceiling panel and the sound reflecting plate is formed so as to gradually change.

[0008] In the present invention, a sound reflecting plate with multiple through holes is provided on the rear surface of the ceiling panel that constitutes the lower surface of the return duct, at a position below the vehicle facing the RA opening and spaced above the vehicle from the ceiling panel, so that a portion of the mid-high to low frequency noise generated by the air conditioner can be reflected by the sound reflecting plate toward the RA opening on its way from the RA opening to the air intake of the ceiling panel. Therefore, not only mid-high frequency noise but also low frequency noise can be suppressed from propagating into the passenger compartment.

[0009] Furthermore, sound waves from the air conditioner that pass through the holes in the sound reflecting plate are attenuated in the gap between the ceiling panel and the sound reflecting plate by the sound absorption principle of the Helmholtz resonator, reducing the noise that propagates into the passenger compartment. The distance between the ceiling panel and the sound reflecting plate is designed to gradually change, so that sound can be absorbed over a wide range of sound, and as the distance increases, the resonant frequency between the ceiling panel and the sound reflecting plate can be expanded to a low frequency range of about 400 to 500 Hz or less, effectively reducing low frequency noise. This improves the quietness of the passenger compartment.

[0010] Therefore, according to the present invention, it is possible to provide a railway vehicle equipped with a return duct in the ceiling that returns air inside the passenger compartment to an air conditioner installed in the roof structure, and which can effectively reduce low-frequency noise generated by the air conditioner and improve quietness inside the passenger compartment.

[0011] (2) In the case of a railway vehicle as described in (1), The return duct is characterized by including a second sound reflecting plate disposed in the vicinity of the intake port.

[0012] In the present invention, the return duct is provided with a second sound reflecting plate disposed near the air intake, so that noise generated by the air conditioner that is not reflected by the sound reflecting plate to the RA opening side is reflected and attenuated by the second sound reflecting plate, and can be prevented from propagating from the air intake into the passenger compartment. This can further improve the quietness of the passenger compartment.

[0013] (3) In the case of railway vehicles described in (2), The second sound reflecting plate is characterized in that it extends obliquely upward and laterally from the vehicle width direction end portion of the main body portion of the sound reflecting plate in which the through hole is formed.

[0014] In the present invention, the second sound reflecting plate extends obliquely upward from the vehicle width direction end of the main body of the sound reflecting plate where the through hole is formed, so that the noise generated by the air conditioner that is not reflected by the sound reflecting plate to the RA opening side is reflected by the second sound reflecting plate to the RA opening side, and the low frequency noise propagating from the intake port to the passenger compartment can be further attenuated. Therefore, the quietness in the passenger compartment can be further improved effectively.

[0015] (4) In the case of railway vehicles described in (2), The second sound reflecting plate is formed so as to divide the flow path into a plurality of parts above and below the vehicle.

[0016] In the present invention, the second sound reflecting plate is formed so as to divide the flow path into a plurality of parts at the top and bottom of the vehicle, so that almost no pressure loss occurs in the flow path. In addition, noise generated by the air conditioner that is not reflected to the RA opening side by the sound reflecting plate can be further attenuated by repeatedly reflecting it up and down by the second sound reflecting plate that divides it into a plurality of parts at the top and bottom of the vehicle. Therefore, low-frequency noise propagating from the intake port into the passenger compartment can be further attenuated with almost no pressure loss in the flow path. As a result, quietness in the passenger compartment can be improved even more effectively.

[0017] (5) In the case of railway vehicles described in (4), The second sound reflecting plate is characterized in that a guide portion is formed to guide the air flowing through the flow path toward the RA opening side.

[0018] In the present invention, the second sound reflecting plate is formed with a guide portion that guides the air flowing through the flow path toward the RA opening side, so that the guide portion can reduce pressure loss in the flow path. Also, noise generated by the air conditioner that is not reflected by the sound reflecting plate toward the RA opening side can be reflected by the guide portion toward the sound reflecting plate side, thereby further attenuating the noise. Therefore, the quietness in the passenger compartment can be improved more effectively while reducing pressure loss in the flow path.

[0019] (6) In a railway vehicle according to any one of (1) to (5), The sound reflecting plate includes a plurality of partition walls extending to the rear surface side of the ceiling panel, The present invention is characterized in that a plurality of resonance chambers are provided between the sound reflecting plate and the ceiling panel, the resonance chambers being partitioned by the partition wall and having different resonance frequencies in the low frequency range.

[0020] In the present invention, the sound reflecting plate is provided with a plurality of partitions extending to the rear side of the ceiling panel, and a plurality of resonance chambers having different low-frequency resonance frequencies are provided between the sound reflecting plate and the ceiling panel, which are partitioned by the partitions, so that the low-frequency noise of the air conditioner can be reduced over a wider frequency range, thereby more effectively improving the quietness inside the passenger compartment. Effect of the Invention

[0021] According to the present invention, it is possible to provide a railway vehicle equipped with a return duct in the ceiling that returns air inside the passenger compartment to an air conditioner installed in the roof structure, effectively reducing low-frequency noise generated by the air conditioner and improving quietness inside the passenger compartment. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic side view of a railway vehicle according to one embodiment of the present invention. FIG. [Diagram 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Diagram 3] FIG. 3 is a cross-sectional view taken along line BB in FIG. 2, showing a first example of the present embodiment. [Figure 4] FIG. 3 is a cross-sectional view taken along line BB in FIG. 2, showing a second example of the present embodiment. [Diagram 5] 5 is a cross-sectional view taken along line BB in FIG. 2, showing a modified example of the second example of the present embodiment. FIG. [Figure 6] FIG. 1 is a schematic cross-sectional view of a return duct of a railway vehicle described in Patent Document 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] <Configuration of this railway vehicle> Next, a first and a second examples of a railway vehicle according to one aspect of an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 shows a schematic side view of a railway vehicle according to one aspect of an embodiment of the present invention. Fig. 2 shows an AA cross-sectional view shown in Fig. 1. Fig. 3 shows a BB cross-sectional view shown in Fig. 2 of the first example of this embodiment. Fig. 4 shows a BB cross-sectional view shown in Fig. 2 of the second example of this embodiment. Fig. 5 shows a modified example of the second example of this embodiment, the BB cross-sectional view shown in Fig. 2.

[0024] (First Example) As shown in Fig. 1, the railway vehicle 10 of the first embodiment includes an underframe DW supported by a pair of front and rear bogies DS running on a rail RL, an end structure TK standing at the front and rear ends of the underframe DW, a side structure GK standing at both ends of the underframe DW, and a roof structure YK connected to the upper ends of the end structure TK and the side structure GK. The side structure GK is formed with side windows GM of various sizes, a passenger side door GT1 through which passengers get on and off, and a crew side door GT2 through which the driver and others get on and off. Underfloor equipment KZ is attached to the underframe DW. An air conditioner KT is attached to the roof structure YK. Here, one air conditioner KT is attached to the roof structure YK near the center of the vehicle longitudinal direction, but multiple air conditioners may be attached.

[0025] As shown in Figs. 1 to 3, the railway vehicle 10 is provided with an air conditioner KT on the roof structure YK, and a return duct KD1 is provided in the ceiling space for returning the air RA in the passenger compartment 1 from an air intake 22 formed in the ceiling panel 2 to an RA opening KT2 of the air conditioner KT via a bent flow path KD11. A roll filter device 6 having a rollable filter section 61 is disposed at the upper end of the return duct KD1. The air RA in the passenger compartment 1 that has passed through the air intake 22 returns to the RA opening KT2 of the air conditioner KT after foreign matter and the like have been removed by the filter section 61 of the roll filter device 6. The air intake 22 may be divided into a plurality of sections in the vehicle longitudinal direction (rail direction).

[0026] The return duct KD1 is composed of an upper duct section 3 located above the ceiling and a ceiling panel 2, and the upper duct section 3 and the ceiling panel 2 are fixed to the inner frame YK1 of the roof structure YK separately at the top and bottom. Here, the inner frame YK1 is formed with a brim hat cross section with a horizontal brim YK11 at the lower end. The upper duct section 3 is formed with a vertical wall section 31 and a horizontal wall section 32 in a V-shape and has the function of bending the flow path KD11 from the vehicle vertical direction to the vehicle width direction. The vertical wall section 31 of the upper duct section 3 and the locking fitting 23 of the ceiling panel 2 are fixed to the brim YK11 of the inner frame YK1 separately at the top and bottom. A seal material 25 is attached between the locking fitting 23 and the brim YK11 of the inner frame YK1. The horizontal wall section 32 of the upper duct section 3 is in close proximity to or in contact with the frame body 62 of the roll filter device 6.

[0027] The ceiling panel 2 is made of a resin material or the like, and is shaped into a predetermined shape in the center of the ceiling. The ceiling panel 2 has an upward curved portion 2H that protrudes in an arc shape toward the top of the vehicle and a downward curved portion 2T that protrudes in an arc shape toward the bottom of the vehicle, formed at different positions in the longitudinal direction of the vehicle from both ends in the vehicle width direction where the air intake portion 22 is formed, thereby increasing the rigidity of the ceiling panel 2 in the middle portion in the vehicle width direction. In this way, by increasing the rigidity of the ceiling panel 2 itself, vibration of the ceiling panel 2 is suppressed, and noise SO from the air conditioner KT is less likely to propagate into the passenger compartment 1.

[0028] In addition, on the front side and rear side of the return duct KD1, there are air conditioning ducts KD that blow conditioned air supplied from the supply port KT1 of the air conditioner KT into the passenger compartment 1 in the ceiling. The return duct KD1 and the air conditioning duct KD are formed to have the same or similar size in the vehicle width direction. Therefore, the lower surface of the return duct KD1 and the lower surface of the air conditioning duct KD can be formed by a common ceiling panel 2. In addition, a heat insulating material 24 is attached to the back side of the ceiling panel 2. The heat insulating material 24 can also serve as a sound absorbing material. In addition, a lighting interior panel 7 with a lighting fixture (not shown) attached thereto is attached to the end side of the lighting interior panel 7 in the vehicle width direction near the outside of the vehicle, and a side ceiling panel 5 that is joined to the interior panel of the side structure GK is attached to the end side of the lighting interior panel 7 in the vehicle width direction near the outside of the vehicle.

[0029] In addition, the back side of the ceiling panel 2 constituting the lower surface of the return duct KD1 is provided with a sound reflecting plate 4 having a plurality of through holes 41 formed therein, at a position below the vehicle facing the RA opening KT2 and spaced apart from the ceiling panel 2 toward the upper side of the vehicle. Therefore, a portion of the noise SO from the mid-high to low ranges generated by the air conditioner KT can be reflected by the sound reflecting plate 4 toward the RA opening KT2 side on its way from the RA opening KT2 to the air intake portion 22 of the ceiling panel 2. Therefore, not only the noise SO in the mid-high range but also the noise SO in the low range can be suppressed from propagating into the passenger compartment 1.

[0030] Here, the sound reflecting plate 4 is formed with a gentle mountain-shaped cross section, with the center CL in the vehicle width direction as the apex, gradually inclining downward toward the vehicle side (to the vehicle right and left). By forming the sound reflecting plate 4 with a gentle mountain-shaped cross section, it is possible to reflect more of the noise SO generated by the air conditioner KT toward the RA opening KT2 side, while smoothly returning the air RA in the passenger compartment 1 sucked from the air intake port 22 to the RA opening KT2 side. The inclination angle of the sound reflecting plate 4 with respect to the horizontal plane is preferably about 5 to 10 degrees. In this case, it is possible to reflect more of the noise SO toward the RA opening KT2 side while securing the necessary flow passage space in the return duct KD1.

[0031] In addition, sound waves from the air conditioner KT that pass through the through holes 41 of the sound reflecting plate 4 are attenuated in the gap between the ceiling panel 2 and the sound reflecting plate 4 by the sound absorption principle of the Helmholtz resonator, and the noise SO propagating into the passenger compartment 1 can be reduced. The separation distance d1 between the ceiling panel 2 and the sound reflecting plate 4 is formed to gradually change. Specifically, the separation distance d1 between the sound reflecting plate 4 formed in a gentle mountain-shaped cross section and the upwardly curved portion 2H that protrudes in an arc shape toward the upper side of the vehicle or the downwardly curved portion 2T that protrudes in an arc shape toward the lower side of the vehicle is formed to gradually change in the vehicle width direction. Therefore, sound can be absorbed in a wide range, and as the separation distance d1 increases, the resonant frequency that resonates between the ceiling panel 2 and the sound reflecting plate 4 can be expanded to a low-frequency range of about 400 to 500 Hz or less, and low-frequency noise can be effectively reduced. As a result, the quietness in the passenger compartment 1 can be improved.

[0032] Therefore, according to the present railway vehicle 10, a railway vehicle 10 can be provided that is equipped with a return duct KD1 in the ceiling that returns the air RA in the passenger compartment 1 to the air conditioner KT provided in the roof structure YK, and that effectively reduces the low-frequency noise SO generated by the air conditioner KT, thereby improving quietness in the passenger compartment 1.

[0033] In addition, in the present railway vehicle 10, the return duct KD1 is preferably provided with a second sound reflecting plate 42 arranged near the intake port 22. In this case, noise SO1 generated by the air conditioner KT that is not reflected by the sound reflecting plate 4 to the RA opening KT2 side is reflected by the second sound reflecting plate 42 to the RA opening KT2 side, and can be suppressed from propagating from the intake port 22 into the passenger compartment 1. Therefore, the quietness in the passenger compartment 1 can be further improved.

[0034] In addition, in the present railway vehicle 10, the second sound reflecting plate 42 is preferably extended obliquely upward and laterally (in a direction inclined so as to rise toward the outside in the vehicle width direction) from the vehicle width direction end of the main body 4H of the sound reflecting plate 4 where the through hole 41 is formed. In this case, the noise SO1 generated by the air conditioner KT that is not reflected by the sound reflecting plate 4 to the RA opening KT2 side is reflected by the second sound reflecting plate 42 to the RA opening KT2 side, and the low-frequency noise SO1 propagated from the intake port 22 into the passenger compartment 1 can be further attenuated. Therefore, the quietness in the passenger compartment 1 can be further effectively improved. The crossing angle of the second sound reflecting plate 42 with respect to the sound reflecting plate 4 is preferably formed at an obtuse angle of about 120 to 150 degrees. In this case, the bending amount of the flow path KD11 does not increase so much, and the increase in pressure loss can be minimized. In addition, the tip of the second sound reflecting plate 42 is preferably bent obliquely downward toward the intake port 22 of the ceiling panel 2. In this case, the tip of the second sound reflecting plate 42 allows the air RA that has flowed in from the intake port 22 to return more smoothly to the RA opening KT2 side.

[0035] (Second Example) As shown in Figs. 1, 2, 4, and 5, the railway vehicle 10B of the second embodiment is provided with an air conditioner KT on the roof structure YK, and a return duct KD1 in the ceiling space for returning the air RA in the passenger compartment 1 from the air intake 22 formed in the ceiling panel 2 to the RA opening KT2 of the air conditioner KT through a bent flow path KD11. The back side of the ceiling panel 2 forming the lower surface of the return duct KD1 is provided with a sound reflecting plate 4 having a plurality of through holes 41 formed therein at a position spaced apart from the ceiling panel 2 toward the upper side of the vehicle, at a position facing the RA opening KT2 below the vehicle, and the distance d1 between the ceiling panel 2 and the sound reflecting plate 4 is formed so as to gradually change. The return duct KD1 is also provided with a second sound reflecting plate 43 (431, 432) disposed near the air intake 22. The above content is common to the railway vehicle 10 of the first embodiment described above. Here, the same reference numerals are used to denote features common to the railway vehicle 10 of the first embodiment, and explanations thereof will be omitted in principle, and differences will be mainly described.

[0036] In the present railway vehicle 10B of the second embodiment, the second sound reflecting plate 43 (431, 432) is formed so as to divide the flow path KD11 into a plurality of parts at the top and bottom of the vehicle. For example, as shown in FIG. 4, the second sound reflecting plate 43 includes a lower reflecting plate 431 extending horizontally above the vehicle width direction end of the sound reflecting plate 4, and an upper reflecting plate 432 extending horizontally above the lower reflecting plate 431 and to the vertical wall portion 31 of the upper duct portion 3. In this case, the air RA in the passenger compartment 1 sucked in from the air intake portion 22 of the ceiling panel 2 comes into contact with the upper reflecting plate 432 and bends inward in the vehicle width direction, and flows along the gap between the upper reflecting plate 432 and the lower reflecting plate 431 and the gap between the lower reflecting plate 431 and the sound reflecting plate 4, so that the pressure loss is hardly increased. It is preferable that the upper reflecting plate 432 is curved downward in an arc shape near the vertical wall portion 31. In this case, the pressure loss in the vicinity of the vertical wall portion 31 can be further reduced.

[0037] On the other hand, the noise SO1 generated by the air conditioner KT that is not reflected by the sound reflecting plate 4 to the RA opening KT2 side is repeatedly reflected up and down by the gap between the upper reflecting plate 432 and the lower reflecting plate 431, and the gap between the lower reflecting plate 431 and the sound reflecting plate 4, and is attenuated. In this way, the noise SO1 that is not reflected by the sound reflecting plate 4 to the RA opening KT2 side can be further attenuated by repeatedly reflecting up and down by the second sound reflecting plate 43 (431, 432) that divides the flow path KD11 into a plurality of parts at the top and bottom of the vehicle. Therefore, the low-frequency noise SO1 propagated from the intake port 22 to the passenger compartment 1 can be further attenuated without almost increasing the pressure loss of the flow path KD11. As a result, the quietness in the passenger compartment 1 can be improved more effectively. Here, the second sound reflecting plates 43 (431, 432) are formed so as to divide the flow path KD11 into two parts at the top and bottom of the vehicle, but this is not limiting and the flow path KD11 may be divided into three or more parts.

[0038] In addition, in the present railway vehicle 10C of the modified example of the second embodiment, it is preferable that the second sound reflecting plate 43 is formed with a guide portion 433 for guiding the air RA flowing through the flow path KD11 to the RA opening KT2 side, as shown in FIG. 5. The guide portion 433 is extended obliquely upward and inward from the inner end of the lower reflecting plate 431 in the vehicle width direction. In this case, the guide portion 433 makes the flow of the air RA smooth, and the pressure loss of the flow path KD11 can be reduced. In addition, the noise SO1 generated by the air conditioner KT that is not reflected by the sound reflecting plate 4 to the RA opening KT2 side can be reflected by the guide portion 433 to the sound reflecting plate 4 side, and can be further attenuated. Therefore, the quietness in the passenger compartment 1 can be further effectively improved while reducing the pressure loss of the flow path KD11.

[0039] In addition, in the present railway vehicle 10C of the modified example of the second embodiment, as shown in FIG. 5, the sound reflecting plate 4 is provided with a plurality of partitions 44 extending to the rear side of the ceiling panel 2, and it is preferable to provide resonance chambers 4K (4Ka, 4Kb) between the sound reflecting plate 4 and the ceiling panel, which are partitioned by the partitions 44 and have different low-frequency resonance frequencies (for example, a resonance frequency of 400 Hz and a resonance frequency of 500 Hz). In this case, the low-frequency noise SO of the air conditioner KT can be reduced over a wider frequency range. As a result, the quietness inside the passenger compartment 1 can be improved even more effectively. This can also be applied to the present railway vehicle 10 of the first embodiment.

[0040] Here, the sound reflecting plate 4 is formed with different plate thicknesses t1, t2 for each resonance chamber 4K (4Ka, 4Kb), and through holes 41 (41a, 41b) with different hole diameters b1, b2 are formed. In this case, even if the volume of the resonance chambers 4K (4Ka, 4Kb) is the same, the volume of the through holes 41 (41a, 41b) is different, so that the resonance frequency of the resonance chambers 4K can be made different. By making the volume of the resonance chambers 4K (4Ka, 4Kb) common, many compact resonance chambers 4K can be formed. As a result, the air conditioning ducts KD are provided on the front side and rear side of the vehicle of the return duct KD1, and the low-frequency noise SO can be reduced over a wider frequency range in the return duct KD1 formed in a narrow range. It goes without saying that the railway cars 10, 10B, and 10C can be further modified into various forms without changing the gist of the present invention.

[0041] <Action and effect> According to the railway cars 10, 10B, and 10C according to the present embodiment described above in detail, the back side of the ceiling panel 2 constituting the lower surface of the return duct KD1 is provided with a sound reflecting plate 4 having a plurality of through holes 41 formed therein at a position facing the RA opening KT2 below the vehicle and spaced apart from the ceiling panel 2 above the vehicle, so that a portion of the noise SO from the mid-high to low ranges generated by the air conditioner KT can be reflected by the sound reflecting plate 4 to the RA opening KT2 side on its way from the RA opening KT2 to the air intake 22 of the ceiling panel 2. Therefore, not only the noise SO of the mid-high range but also the noise SO of the low range can be suppressed from propagating into the passenger compartment 1.

[0042] Furthermore, sound waves from the air conditioner KT that pass through the through holes 41 of the sound reflecting plate 4 are attenuated in the gap between the ceiling panel 2 and the sound reflecting plate 4 due to the sound absorption principle of the Helmholtz resonator, reducing the noise SO propagating into the passenger compartment 1. Since the separation distance d1 between the ceiling panel 2 and the sound reflecting plate 4 is formed to gradually change, sound can be absorbed over a wide range of sounds, and as the separation distance d1 increases, the resonant frequency between the ceiling panel 2 and the sound reflecting plate 4 can be expanded to a low-frequency range of about 400 to 500 Hz or less, effectively reducing low-frequency noise. This allows the passenger compartment 1 to be quieter.

[0043] Therefore, according to this embodiment, it is possible to provide railway cars 10, 10B, and 10C that are equipped with a return duct KD1 in the ceiling that returns the air RA in the passenger compartment 1 to an air conditioner KT provided on the roof structure YK, and that can effectively reduce the low-frequency noise SO generated from the air conditioner KT and improve quietness in the passenger compartment 1.

[0044] Furthermore, according to this embodiment, the return duct KD1 is provided with the second sound reflecting plates 42, 43 (431, 432) arranged near the intake port 22, so that noise SO1 generated by the air conditioner KT that is not reflected by the sound reflecting plate 4 to the RA opening KT2 side is reflected and attenuated by the second sound reflecting plates 42, 43 (431, 432) and can be prevented from propagating from the intake port 22 into the passenger compartment 1. This makes it possible to further improve the quietness inside the passenger compartment 1.

[0045] Furthermore, according to this embodiment, the second sound reflecting plate 42 extends obliquely upward from the vehicle width direction end of the main body 4H of the sound reflecting plate 4 where the through hole 41 is formed, so that the noise SO1 generated by the air conditioner KT that is not reflected by the sound reflecting plate 4 to the RA opening KT2 side is reflected by the second sound reflecting plate 42 to the RA opening KT2 side, thereby further attenuating the low-frequency noise SO1 propagating from the intake port 22 into the passenger compartment 1. Therefore, the quietness in the passenger compartment 1 can be improved even more effectively.

[0046] In addition, according to this embodiment, the second sound reflecting plate 43 is formed to divide the flow path KD11 into a plurality of parts at the top and bottom of the vehicle, so that the pressure loss in the flow path KD11 is hardly generated, and the noise SO1 generated by the air conditioner KT that is not reflected to the RA opening KT2 side by the sound reflecting plate 4 is repeatedly reflected up and down by the second sound reflecting plate 43 (431, 432) that divides the noise SO into a plurality of parts at the top and bottom of the vehicle, and can be further attenuated. Therefore, the low-frequency noise SO1 propagated from the intake port 22 into the passenger compartment 1 can be further attenuated without increasing the pressure loss in the flow path KD11. As a result, the quietness in the passenger compartment 1 can be improved more effectively.

[0047] Furthermore, according to this embodiment, the second sound reflecting plate 43 is formed with a guide portion 433 that guides the air RA flowing through the flow path KD11 toward the RA opening KT2 side, so that the guide portion 433 can reduce the pressure loss in the flow path KD11. Furthermore, noise SO1 generated by the air conditioner KT that has not been reflected toward the RA opening KT2 side by the sound reflecting plate 4 can be reflected toward the sound reflecting plate 4 by the guide portion 433, and can be further attenuated. Therefore, the quietness in the passenger compartment 1 can be further effectively improved while reducing the pressure loss in the flow path KD11.

[0048] Furthermore, according to this embodiment, the sound reflecting plate 4 is provided with a plurality of partition walls 44 extending to the rear surface side of the ceiling panel 2, and a plurality of resonance chambers 4K having different low-frequency resonance frequencies are provided between the sound reflecting plate 4 and the ceiling panel, which are partitioned by the partition walls 44. As a result, the low-frequency noise SO of the air conditioner KT can be reduced over a wider frequency range. As a result, the quietness inside the passenger compartment 1 can be improved even more effectively. [Industrial Applicability]

[0049] INDUSTRIAL APPLICABILITY The present invention can be used as a railway vehicle having a return duct in the ceiling for returning air inside the passenger compartment to an air conditioner provided in the roof structure. [Explanation of symbols]

[0050] 1 Room 2 Ceiling Panel 3 Upper duct section 4 Sound reflector 4K resonance chamber 4H Main body 10, 10B, 10C Railway Cars 22 Air intake section 41 Through hole 42, 43 Second sound reflector 44 Bulkhead 433 Information Department KD1 Return Duct KD11 Flow path KT air conditioner KT2 RA opening RA Air YK roof structure d1 Separation distance

Claims

1. A railway vehicle having an air conditioner installed in a roof structure and a return duct in the ceiling that returns air from the passenger compartment from an air intake formed in a ceiling panel to the RA opening of the air conditioner through a curved flow path, A sound reflecting plate having a plurality of through holes is provided on the rear surface side of the ceiling panel constituting the lower surface of the return duct, at a position below the vehicle facing the RA opening and spaced from the ceiling panel toward the upper side of the vehicle, The distance between the ceiling panel and the sound reflecting plate is gradually changed. A railway vehicle, characterized in that the return duct is provided with a second sound reflecting plate arranged in the vicinity of the intake port.

2. 2. The railway vehicle according to claim 1, The railway vehicle, wherein the second sound reflecting plate extends obliquely upward and laterally from the vehicle width direction end of the main body of the sound reflecting plate in which the through hole is formed.

3. 2. The railway vehicle according to claim 1, The railway vehicle, wherein the second sound reflecting plate is formed so as to divide the flow path into a plurality of parts above and below the vehicle.

4. 4. The railway vehicle according to claim 3, The railway vehicle, wherein the second sound reflecting plate is formed with a guide portion that guides the air flowing through the flow path toward the RA opening side.

5. 2. The railway vehicle according to claim 1, The sound reflecting plate includes a plurality of partition walls extending to the rear surface side of the ceiling panel, a plurality of resonance chambers, each having a different low-frequency resonance frequency, partitioned by the partition wall between the sound reflecting plate and the ceiling panel;

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