Air conditioner

Abstract: An air conditioner having a centrifugal blower (6) in the central portion within a casing (2) configuring an air conditioner main body (1), in which a heat exchanger (7) is disposed around said centrifugal blower (6), heat insulation material (10) for forming a blow-off air course (8) is disposed between said heat exchanger (7) and an inner wall surface of said casing (2) on said inner wall surface, a panel (9) is mounted to a lower end portion of said casing (2), a suction port (3) is formed in a central portion of said panel (9), and blow-off ports (4) are formed in side edge portions, characterized in that a width of said blow-off air course (8) on the upstream side is smaller than that on the downstream side.

Description: BACKGROUND OF THE INVENTION The present invention relates to an air conditioner, and more particularly to a structure for realizing uniformalization in wind velocity distribution of air which passes through its heat exchanger. As a conventional ceiling embedded-type air conditioner, there is known an air conditioner disclosed in, for example, Japanese Patent Laid-Open No. 6-341659. Figure 6 is a sectional view showing the ceiling embedded-type air conditioner. In Figure 6, a reference numeral 1 denotes an air condition main body, which has a motor 5 in the central portion within a casing 2 configuring the main body 1, and a centrifugal blower 6 is fixed to the tip end of the shaft of the motor 5. A reference numeral 6a denotes a main plate of the centrifugal blower 6; and 6b, an air blower shroud. A heat exchanger 7 is arranged around the centrifugal blower 6, and on the inner wall surface of the casing 2, there is disposed heat insulation material 10 for forming a blow-off air course 8 between the inner wall surface and the heat exchanger 7. At the lower end portion of the casing 2, there is mounted a panel 9, in the central portion of the panel 9, there is formed a suction port 3, and in the side edge portions, there are formed blow-off ports 4. A reference numeral 2a denotes a casing corner portion. The description will be made of the operation. When the centrifugal blower 6 is driven by the motor 5, indoor air is sucked into the air conditioner main body 1 through the suction port 3. The air thus sucked in is pushed out on the heat exchanger 7 side by the centrifugal blower 6, and after heat exchanged by passing through the heat exchanger 7, passes through a blow-off air course 8 on the secondary side of the heat exchanger, and is conducted indoors through the blow-off port 9. Figure 7 is a view showing blow-off wind velocity distribution of the centrifugal blower in the conventional ceiling embedded-type air conditioner. The air sucked into the air conditioner main body 1 through the suction port 3 is bent in a direction at right angles by the centrifugal blower 6 and is pushed out on the heat exchanger 7 side, and therefore, in the wind velocity blown from the centrifugal blower 6, there takes place such inclination in distribution that the wind velocity becomes slower toward the blower shroud 6b side and faster toward the main plate 6a side as shown in Figure 7. The conventional ceiling embedded-type air conditioner has had a problem that the capacity must be made larger because there is inclination in wind velocity distribution on passing through the heat exchanger 7 because of the above described configuration, and therefore, it has inferior heat exchange efficiency, and cannot make the most of the performance of the heat exchanger 7. Also, there has been a problem that disturbance due to eddy current takes place, or great pressure loss due to sharp deflection occurs in the casing corner portion 2a, resulting in loud noise because the air which passed through the heat exchanger 7 collides with the inner wall surface made of the heat insulation material 10, is bent in a direction at right angles and flows toward the blow-off port 4. An air conditioner according to the preamble of claim 1 is known from document EP-A-0 926 451. The document discloses a ceiling mounted apparatus comprising an air channel structure which is slanted towards the inner wall of a housing so as to define a continuously increasing radial spacing from its heat exchanger elements. EP10030022 discloses an air conditioner that comprises a heat insulating material attached to the inside wall of its casing that provides an air blow off course that is smaller on the upstream side than on the downstream side. SUMMARY OF THE INVENTION The present invention has been achieved in order to solve the above described problems, and is aimed to provide an air conditioner capable of making the most of the heat exchanger' s performance to reduce the capacity in which wind velocity distribution of the air which passes through the heat exchanger becomes uniform, the pressure loss on passing through the heat exchanger is reduced and the noise is muffled. According to the present invention, there is provided an air conditioner comprising the features of claim 1. An air conditioner according to the present invention is capable of uniformalizing the wind velocity distribution of the air which passes through the heat exchanger because the width of the blow-off air course on the upstream side is set smaller than the width on the downstream side. Therefore, it becomes possible to reduce the pressure loss on passing through the heat exchanger, for muffling the noise, and to make the most of the heat exchanger's performance for reducing the capacity. In addition, since the guide is formed of acoustic material such as acoustic plastic and an air layer is provided between the guide and the casing, the noise can be further reduced. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view showing a ceiling embedded-type air conditioner according to a first embodiment which does not fall within the scope of the claims. Figure 2 is a view showing relationship between air flow and noise in an experimental result in which noises with and without any guide are compared. Figure 3 is a view showing relationship between guide width and noise. Figure 4 is a sectional view showing a ceiling embedded-type air conditioner according to a second embodiment which does not fall within the scope of the claims. Figure 5 is a sectional view showing a ceiling embedded-type air conditioner according to an embodiment of the invention. Figure 6 is a sectional view showing a conventional ceiling embedded-type air conditioner. Figure 7 is a view showing blow-off wind velocity distribution of a blower in the conventional ceiling embedded-type air conditioner. BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment Hereinafter, with reference to the drawings, the description will be made of a first embodiment which does not fall within the scope of the claims. Figure 1 is a sectional view showing a ceiling embedded-type air conditioner according to the first embodiment of the present invention. In Figure 1, reference numerals 1 to 10 denote the same or equivalent portions as in Figure 6 showing the conventional apparatus. A reference numeral 11 denotes a guide mounted to heat insulation material 10 disposed on the inner wall surface of a casing 2 in a casing corner portion 2a. With the provision of the guide 11, a minimum width W1 from the ceiling surface of the casing 2 to the upstream-side blow-off air course near the center of the impeller blade outlet of a centrifugal blower 6 is approximately one third to two thirds of the downstream-side air course width W2. In a ceiling embedded-type air conditioner configured as described above, when the centrifugal blower 6 is driven by the motor 5, indoor air is sucked into the main body 1 through the suction port 3. The air sucked is bent in a direction at right angles, is pushed out on the heat exchanger 7 side by the centrifugal blower 6, and passes through the heat exchanger 7 to flow out in the blow-off air course 8. At this time, the air having faster wind velocity on the blower main plate 6a side is converted into static pressure because the velocity component is restrained by the guide 11 provided on the inner wall surface of the casing 2. Therefore, the inclination of the wind velocity distribution of the air which passes through the heat exchanger 7 is improved to enhance the heat exchange efficiency. Since the wind velocity is weakened in the casing corner portion 2a, disturbance caused by the occurrence of eddy current is restrained to smoothly flow toward the downstream side, the air which passes below the heat exchanger 7 without the guide 11 is also dragged into it, and the entire air smoothly flows toward the blow-off port 4. Therefore, the pressure loss decreases, and the noise is reduced. Figure 2 shows the experimental result in which noises with and without any guide are compared, and it could be confirmed that the noise is reduced by the provision of the guide 11 as shown in solid line (presence of the guide 11) and in broken line (absence of the guide 11). As regards the size of the guide 11, the size of approximately one third to two thirds of the width of the blow-off port 4 is most appropriate as shown in the experimental result in Figure 3. According to the above described embodiment, it is possible to uniformalize the wind velocity distribution of the air which passes through the heat exchanger 7, and therefore, it is possible to reduce the pressure loss on passing through the heat exchanger 7, to muffle the noise, to make the most of the performance of the heat exchanger 7, and to reduce the capacity. Second Embodiment Although the heat insulation material 10 and the guide 11 are configured by separate components respectively in the first embodiment, the guide 11 may be integrally molded with heat insulation material 10 disposed on the inner wall surface of the casing 2 as shown in Figure 4 . However, this embodiment does not fall within the scope of the claims. In addition to the effect of the first embodiment, the heat insulation material 10 can be made thicker, thereby the heat insulation effect can be improved, and dewing preventing effect on the outer wall surface of the casing 2 during cooling can be improved. Embodiment of the invention Figure 5 shows an air conditioner in which the guide 11 is formed of acoustic material and an air layer 12 is provided between the inner wall surface of the casing 2 and the guide 11. The fluid noise of the air which flows through the blow-off air course 8 is absorbed by the guide 11 formed of the acoustic material and the air layer 12, and therefore, the noise can be further reduced.

Claims: An air conditioner having a centrifugal blower ( 6) in the central portion within a casing (2) configuring an air conditioner main body (1), in which a heat exchanger (7) is disposed around said centrifugal blower (6), heat insulation material (10) for forming a blow-off air course (8) is disposed between said heat exchanger (7) and an inner wall surface of said casing (2) on said inner wall surface, a panel (9) is mounted to a lower end portion of said ca sing (2), a suction port (3) is formed in a central portion of said panel (9), and blow-off ports (4) are formed in side edge portions, on the inner wall surface of said casing (2), there being provided a guide (11) for making the width of said blow-off air course (8) on the upstream side smaller than that on the downstream side, characterized in that said guide (11) comprises an acoustic material, and an air layer (12) is provided between said casing (2) and said guide (11), the accoustic material and the air layer being for absorbing fluid noise of air flowing through the blow-off air course (8). An air conditioner according to Claim 1, wherein said acoustic material comprises an acoustic plastic. An air conditioner according to Claim 1 or 2, characterized in that said air conditioner is configured so that the width of said blow-off air course (8) on the upstream side becomes one third to two thirds of that on the downstream side.

Inventors: ASAHINA MANABU, EDAYOSHI ATSUSHI, IKEDA TAKASHI, NAKASHIMA HIROSHI, OYA RYO, SEKIGUCHI KAZUNOBU, SONE TATSUO, ASAHINA, MANABU, EDAYOSHI, ATSUSHI, IKEDA, TAKASHI, NAKASHIMA, HIROSHI, OYA, RYO, SEKIGUCHI, KAZUNOBU, SONE, TATSUO, Asahina, Manabu, Mitsubishi Denki K. K., Edayoshi, Atsushi, Mitsubishi Denki K. K., Ikeda, Takashi Mitsubishi Denki K. K., Nakashima, Hiroshi, Mitsubishi Denki K. K., Oya, Ryo, Mitsubishi Denki K. K., Sekiguchi, Kazunobu, Mitsubishi Denki K. K., Sone, Tatsuo, Mitsubishi Denki K. K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 2000
Main classification: F24F1
IPC codes: F24F1