JP7799708B2 - Air conditioner outdoor unit - Google Patents

Description

This disclosure relates to an outdoor unit of an air conditioner that has a housing and a heat exchanger.

A conventional air conditioner outdoor unit is known to include a box-shaped housing and a heat exchanger placed inside the housing, with the heat exchanger and housing made from different metals. The types of metal used for the heat exchanger and housing are selected based on the required characteristics. For example, aluminum is typically used for heat exchangers that require high thermal conductivity, while iron is typically used for housings that require strength.

When a heat exchanger and a housing, which are made of dissimilar metals, come into direct contact, galvanic corrosion occurs in the metal with the lower standard electrode potential when moisture adheres to the contact point. Hereinafter, galvanic corrosion will be referred to simply as corrosion. One known method of preventing corrosion is to indirectly connect the heat exchanger and housing via a non-conductive material such as resin.

However, when such measures are used, the heat exchanger and housing are electrically insulated by the non-conductive material, creating a parasitic capacitance between them. This creates the problem of electromagnetic noise generated by electronic boards, compressors, and other components inside the housing causing voltage changes in the parasitic capacitance, which in turn generates further electromagnetic noise. The rear of the housing is provided with an air intake port for allowing outside air to flow in, and the heat exchanger is positioned facing the air intake port to exchange heat with the outside air. Electromagnetic noise is radiated from between the heat exchanger and housing through the air intake port to the outside of the housing.

Technologies have therefore been developed to simultaneously solve the two challenges of preventing corrosion and reducing electromagnetic noise. For example, Patent Document 1 discloses a technology in which a conductive connecting member is interposed between a heat exchanger and a housing. The connecting member has a first connecting portion made of the same metal as that used in the heat exchanger and in direct contact with the heat exchanger, and a second connecting portion made of the same metal as that used in the housing and in direct contact with the housing. In addition, an insulating layer is provided between the first connecting portion and the second connecting portion to electrically insulate them from each other.

The technology disclosed in Patent Document 1 ensures electrical continuity and reduces electromagnetic noise by removing part of the insulating layer and bringing the first and second connection parts, which are made of dissimilar metals, into partial direct contact, while covering the contact points between the first and second connection parts with a covering material such as waterproof tape to prevent moisture from penetrating the contact points and prevent metal corrosion.

Patent No. 6583489

However, the technology disclosed in Patent Document 1 complicates the structure by using multiple types of metal for the connecting members, providing an insulating layer, and using a waterproof coating material, resulting in problems such as increased manufacturing labor and an increased number of parts.

This disclosure has been made in consideration of the above, and aims to provide an outdoor unit for an air conditioner that has a simple structure and can achieve both corrosion prevention and electromagnetic noise reduction.

To solve the above-mentioned problems and achieve the object, the outdoor unit of an air conditioner according to the present disclosure includes a box-shaped housing made of a first metal and having an air intake port for introducing outdoor air; a heat exchanger, at least a portion of which is made of a second metal having a standard electrode potential different from that of the first metal, disposed within the housing and fixed to the housing via a non-conductive member; and a grid, made of the first metal, disposed upstream of the heat exchanger in the air flow direction and spaced apart from the heat exchanger, fixed to the housing and electrically connected to the housing. A gap is formed between the heat exchanger and the housing. The grid includes a fixing frame fixed to the housing and positioned so as to overlap the gap when viewed along the air flow direction. The housing includes a housing floor panel, a housing top panel disposed above the housing floor panel and spaced apart from the housing floor panel, and housing back panel and housing side panel connecting the housing floor panel and the housing top panel. A top flange portion folded downward is formed around the periphery of the housing top panel. The top flange and the fixed frame are fixed together in a state where they are butted against each other in the direction opposite to the air flow.A bottom flange is formed on the periphery of the chassis floor panel, folded upward.The bottom flange and the fixed frame are fixed together in a state where they are butted against each other in the direction of the air flow.

The outdoor unit of the air conditioner disclosed herein has the advantage of being able to prevent corrosion and reduce electromagnetic noise at the same time with a simple structure.

FIG. 1 is an exploded perspective view schematically illustrating an outdoor unit of an air conditioner according to a first embodiment. FIG. 1 is a front view showing an outdoor unit of an air conditioner according to a first embodiment, with a front panel of the housing removed; FIG. 1 is an exploded perspective view showing an electronic circuit board box and an interface panel according to a first embodiment. FIG. 4 is a perspective view showing the electronic circuit board box and the interface panel shown in FIG. 3 assembled together; FIG. 1 is a right side view showing an outdoor unit of an air conditioner according to a first embodiment. 6 is a cross-sectional view taken along line VI-VI shown in FIG. 2; FIG. 1 is a rear view showing a grid body according to the first embodiment; FIG. 1 is a rear view of the outdoor unit of the air conditioner according to the first embodiment, showing a state in which a lattice member is attached to the housing. 9 is a cross-sectional view taken along line IX-IX shown in FIG. 8. FIG. 1 is a perspective view schematically illustrating a heat exchanger according to a first embodiment. FIG. 1 is a front view showing a heat exchanger according to a first embodiment; 12 is an enlarged view of the main part of the heat exchanger shown in FIG. 11 . FIG. 1 is a schematic diagram showing, as an electric circuit, a transmission path of electromagnetic noise generated in an outdoor unit of an air conditioner according to a first embodiment. 1 is an equivalent circuit diagram of a path through which a current that causes electromagnetic noise propagates in an outdoor unit of an air conditioner according to a first embodiment. FIG. 1 is a rear view of the outdoor unit of the air conditioner according to the first embodiment, showing a state in which a grid is removed and a location where electromagnetic noise occurs. 1 is an equivalent circuit diagram of a path through which a current that causes electromagnetic noise is transmitted when a heat exchanger and a housing are in direct contact without an insulating member in an outdoor unit of an air conditioner according to a first embodiment. FIG. 1 is a rear view of the outdoor unit of the air conditioner according to the first embodiment, showing a state in which a grid is attached and a location where electromagnetic noise occurs.

Below, the outdoor unit of the air conditioner according to the embodiment is described in detail with reference to the drawings.

Embodiment 1.
Fig. 1 is an exploded perspective view schematically showing an outdoor unit 1 of an air conditioner according to embodiment 1. As shown in Fig. 1, the outdoor unit 1 of the air conditioner includes a housing 2, a lattice member 3, a partition plate 4, a blower 5, a heat exchanger 6, two insulating members 7, a compressor 8, and an electronic circuit board box 9. Hereinafter, the outdoor unit 1 of the air conditioner may also be simply referred to as the outdoor unit 1.

When describing the directions of each component of the outdoor unit 1 below, the depth direction of the outdoor unit 1 is referred to as the X-axis direction, the height direction of the outdoor unit 1 as the Y-axis direction, and the width direction of the outdoor unit 1 as the Z-axis direction. Furthermore, the + direction in the X-axis direction is referred to as the forward direction, and the - direction in the X-axis direction is referred to as the rearward direction. The + direction in the X-axis direction is the direction from the - side to the + side of the X-axis, and the - direction in the X-axis direction is the direction from the + side to the - side of the X-axis. Furthermore, the + direction in the Y-axis direction is referred to as the upward direction, and the - direction in the Y-axis direction is referred to as the downward direction. The + direction in the Y-axis direction is the direction from the - side to the + side of the Y-axis, and the - direction in the Y-axis direction is the direction from the + side to the - side of the Y-axis. Furthermore, the + direction in the Z-axis direction is referred to as the right, and the - direction in the Z-axis direction is referred to as the left. The + direction in the Z-axis direction is the direction from the - side to the + side of the Z-axis, and the - direction in the Z-axis direction is the direction from the + side to the - side of the Z-axis. In this embodiment, the side of the outdoor unit 1 from which the airflow generated by the blower 5 is discharged to the outside is referred to as the front, and the side opposite the front is referred to as the back. Arrow Y shown in Fig. 1 indicates the blowing direction of the airflow generated by the blower 5.

Figure 2 is a front view showing the outdoor unit 1 of the air conditioner according to embodiment 1, with the front panel 2c of the housing 2 removed. In Figure 2, the heat exchanger 6 is indicated by dot hatching for ease of understanding. As shown in Figures 1 and 2, the housing 2 is a box-shaped member that forms the outer shell of the outdoor unit 1. The housing 2 is formed from a first metal. The first metal is preferably a metal with high strength. The first metal is, for example, iron or an iron alloy.

As shown in FIG. 1, the housing 2 has a housing floor panel 2a, a housing top panel 2b, a housing front panel 2c, and a housing side panel 2d. The housing floor panel 2a forms the bottom surface of the outer shell of the outdoor unit 1. The planar shape of the housing floor panel 2a is a rectangle with rounded corners. The housing top panel 2b is positioned above and spaced apart from the housing floor panel 2a. The housing top panel 2b forms the ceiling surface of the outer shell of the outdoor unit 1. The planar shape of the housing top panel 2b is the same as the planar shape of the housing floor panel 2a.

The housing front panel 2c and housing side panels 2d connect the housing floor panel 2a and the housing top panel 2b. The housing front panel 2c has an L-shaped shape in a plan view. The housing front panel 2c has a front panel main body 2e extending along the Z-axis direction and a front panel extension 2f extending rearward from the left edge, which is one edge of the front panel main body 2e along the Z-axis direction. The front panel main body 2e connects the front edge of the housing floor panel 2a to the front edge of the housing top panel 2b. The front panel main body 2e forms the front surface of the outer shell of the outdoor unit 1. The front panel extension 2f connects the left edge of the housing floor panel 2a to the left edge of the housing top panel 2b. The front panel extension 2f forms the left side of the outer shell of the outdoor unit 1. Hereinafter, the front panel extension 2f may also be referred to as the "housing side panel 2g." In this embodiment, the front panel main body 2e and the housing side panel 2g are formed integrally, but may be formed separately.

The planar shape of the housing side panel 2d is L-shaped. The housing side panel 2d has a side panel main body 2h extending along the X-axis direction and a side panel extension 2i extending leftward from the rear edge, which is one edge of the side panel main body 2h along the X-axis direction. The side panel main body 2h connects the right edge of the housing floor panel 2a to the right edge of the housing top panel 2b. The side panel main body 2h forms the right side of the outer shell of the outdoor unit 1. The side panel extension 2i connects part of the rear edge of the housing floor panel 2a to part of the rear edge of the housing top panel 2b. The side panel extension 2i forms part of the back surface of the outer shell of the outdoor unit 1. Hereinafter, the side panel extension 2i may also be referred to as the "housing rear panel 2j." In this embodiment, the side panel main body 2h and the housing rear panel 2j are formed integrally, but they may also be formed separately. When the panels are assembled as shown in FIG. 1, the left edge of the rear panel 2j and the rear edge of the side panel 2g are spaced apart from each other.

The grid 3 is a metal member that is located upstream of the heat exchanger 6 in the air flow direction and spaced apart from the heat exchanger 6, and is fixed to the housing 2 and electrically connected to the housing 2. In this specification, "electrically connected" between metal members includes a state in which the metal members are in direct contact with each other and are electrically connected, as well as a state in which the metal members are electrically connected through a gap. The grid 3 is located between the left edge of the housing rear panel 2j and the rear edge of the housing side panel 2g. The grid 3 is located behind the heat exchanger 6 and spaced apart from the heat exchanger 6. The grid 3 is made of the same first metal as the housing 2.

As shown in Figure 2, the partition plate 4 is a metal member that divides the interior of the housing 2 into a fan chamber 10 and an electrical chamber 11. The fan chamber 10 and the electrical chamber 11 are formed side by side in the Z-axis direction. The partition plate 4 extends in the Y-axis direction from the housing floor panel 2a to the electronic circuit board box 9. The partition plate 4 extends in the X-axis direction from the housing front panel 2c to the housing rear panel 2j shown in Figure 1.

The housing 2, grid 3, and partition plate 4 shown in Figure 1 are made of the same type of first metal. The housing 2, grid 3, and partition plate 4 are joined at their contact points by welding, screws, etc. If the surfaces of each panel of the housing 2 are painted or otherwise coated, resulting in high electrical resistance on the surface of each panel, the electrical resistance on the surface of each panel can be reduced, for example, by masking some or all of the joints in advance or by using serrated screws to remove the paint when tightening the screws.

As shown in FIG. 2, the blower 5 is disposed in the fan chamber 10 and is a device that generates an airflow. The blower 5 has a support 5a that rises from the housing floor panel 2a, a fan motor 5b attached to the support 5a, and a propeller fan 5c that is attached to the rotating shaft of the fan motor 5b and rotates as the fan motor 5b rotates. The upper end of the support 5a is fixed to the housing top panel 2b. The lower end of the support 5a is fixed to the housing floor panel 2a. The fan motor 5b is electrically connected to the electronic board 9c (described below) via a fan drive wire 12. The fan motor 5b rotates when it receives a drive signal output from the electronic board 9c via the fan drive wire 12.

The heat exchanger 6 is disposed in the fan chamber 10 and is a component for exchanging heat between the refrigerant and outdoor air. Outdoor air to be taken in by the blower 5 passes through the heat exchanger 6. The heat exchanger 6 is, for example, a parallel flow type heat exchanger. The heat exchanger 6 is disposed within the housing 2 and fixed to the housing 2 via an insulating member 7, which is a non-conductive member. At least a portion of the heat exchanger 6 is formed from a second metal having a standard electrode potential different from that of the first metal. The second metal is preferably a metal with high thermal conductivity. The second metal is, for example, aluminum or an aluminum alloy. The standard electrode potential of the first metal is higher than the standard electrode potential of the second metal.

As shown in FIG. 1, the heat exchanger 6 has an L-shaped planar shape. The heat exchanger 6 extends along the Z-axis direction and then extends forward along the X-axis direction. The portion of the heat exchanger 6 along the Z-axis direction is located behind the blower 5. The portion of the heat exchanger 6 along the X-axis direction is located to the left of the blower 5. The heat exchanger 6 and the blower 5 are either spaced apart and electrically insulated, or are electrically insulated by being placed via an insulating member (not shown).

The heat exchanger 6 and the housing front panel 2c and housing side panel 2d are either spaced apart and electrically insulated, or are arranged via insulating members (not shown) and are electrically insulated. As shown in FIG. 2, the upper end of the heat exchanger 6 is fixed to the housing top panel 2b via insulating member 7. The lower end of the heat exchanger 6 is fixed to the housing floor panel 2a via insulating member 7. The heat exchanger 6 is electrically insulated from the housing top panel 2b and housing floor panel 2a. The heat exchanger 6 is arranged without being electrically connected to the metal members such as the housing 2, grid 3, and blower 5 that are arranged around the heat exchanger 6.

The two insulating members 7 shown in FIG. 1 are made of an electrically insulating material such as resin. Hereinafter, when distinguishing between the two insulating members 7, the insulating member 7 provided at the lower end of the heat exchanger 6 will be referred to as the first insulating member 7a, and the insulating member 7 provided at the upper end of the heat exchanger 6 will be referred to as the second insulating member 7b. In this embodiment, the first insulating member 7a and the second insulating member 7b, which have the same planar shape and size as the heat exchanger 6, are used to cover the entire bottom and top surfaces of the heat exchanger 6, thereby electrically insulating the heat exchanger 6 from the housing 2. However, this is not intended to limit the electrical insulation means between the two members. For example, a configuration may be adopted in which pedestals made of an electrically insulating material are provided at several locations on the bottom surface of the heat exchanger 6, interposing the pedestals between the heat exchanger 6 and the housing floor panel 2a. With this configuration, the heat exchanger 6 and the housing floor panel 2a are spaced apart in the Y-axis direction, so that the heat exchanger 6 and the housing floor panel 2a can be electrically insulated from each other.

As shown in Figure 2, the compressor 8 is disposed in the electrical compartment 11 and is a device that compresses the refrigerant flowing through the heat exchanger 6. The compressor 8 is disposed on the housing floor panel 2a in the lower space of the electrical compartment 11. The compressor 8 is fixed to the housing floor panel 2a with screws or the like.

The electronic board box 9 is a component that houses electronic boards 9c, such as control boards, required to operate the outdoor unit 1. The electronic board box 9 is formed in the shape of a hollow rectangular parallelepiped. The electronic board box 9 is fixed to the upper end of the partition plate 4 and is arranged to straddle the fan chamber 10 and the electrical chamber 11. A heat sink 9d extending downward is attached to the portion of the electronic board box 9 that is arranged in the fan chamber 10. The heat sink 9d is exposed to the fan chamber 10. The heat sink 9d is cooled by the airflow generated by the blower 5.

The portion of the electronic circuit board box 9 located in the electrical chamber 11 is located above the compressor 8. A compressor drive wire 13 is connected to the portion of the electronic circuit board 9c located in the electrical chamber 11. The compressor 8 is electrically connected to the electronic circuit board 9c via the compressor drive wire 13. The compressor 8 is driven when it receives a drive signal output from the electronic circuit board 9c via the compressor drive wire 13.

The electrical compartment 11 is surrounded by the housing floor panel 2a, the partition plate 4, the housing side panel 2d, the electronic circuit board box 9, and the housing front panel 2c and housing rear panel 2j shown in Figure 1, providing a waterproof structure that prevents the infiltration of rainwater and other moisture from outside the housing 2. A stop valve 17 is provided at the bottom of the outer surface of the housing side panel 2d. The stop valve 17 serves as a terminal for connecting the refrigerant piping that connects to the indoor unit (not shown).

The compressor 8 and stop valve 17 are connected to each other via multiple refrigerant pipes 18. The compressor 8 and heat exchanger 6 are connected to each other via multiple refrigerant pipes 18. The connection 19 between the heat exchanger 6 and the refrigerant pipes 18 is located in the electrical chamber 11, which has a waterproof structure. By locating the connection 19 in the electrical chamber 11 in this manner, contact between the connection 19 and moisture can be prevented, thereby preventing corrosion of the connection 19. Note that to further enhance the waterproof effect of the connection 19, the connection 19 may be waterproofed by wrapping it with waterproof tape or the like. Although specific illustrations are omitted, the refrigerant pipes 18 are connected to valve devices such as a four-way valve that switches the direction of refrigerant flow and an expansion valve that expands the refrigerant to a predetermined pressure. The connection configuration of the refrigerant pipes 18 is not limited to the example shown.

An interface panel 20 is installed in the upper space of the electrical room 11. The interface panel 20 is fixed to the inner surface of the housing side panel 2d and the underside of the electronic board box 9. A terminal block 21 is installed on the interface panel 20. The external AC power line 14 and the internal power line 15 are connected to the terminal block 21. The external AC power line 14 is electrically connected to the internal power line 15 via the terminal block 21. The internal power line 15 is electrically connected to the electronic board 9c. Power is supplied to the electronic board 9c via the external AC power line 14, the terminal block 21, and the internal power line 15. The voltage of the power supplied to the electronic board 9c is, for example, single-phase 200V, but is not limited to this voltage.

The interface panel 20 is formed from the same first metal as the housing side panel 2d. Therefore, the interface panel 20 is joined to the housing side panel 2d with low electrical resistance. The interface panel 20 is connected to the signal ground of the electronic board 9c. The interface panel 20 has an earth connection point 20e to which the earth wire 16 is connected. The interface panel 20 is grounded via the earth connection point 20e and the earth wire 16. The housing 2 joined to the interface panel 20 and the partition plate 4 joined to the housing 2 are grounded via the earth connection point 20e and the earth wire 16. The heat exchanger 6 is electrically connected to the housing 2 via the connection portion 19 with the refrigerant piping 18, the compressor 8, etc., but is not directly short-circuited to the housing 2 and the partition plate 4. In other words, the heat exchanger 6 is indirectly short-circuited to the housing 2 and the partition plate 4 via the compressor 8, etc., and is not short-circuited by direct contact with the housing 2 and the partition plate 4.

Next, the configuration of the outdoor unit 1 will be described in more detail. First, the configuration of the electronic board box 9 and interface panel 20 will be described with reference to Figures 3 and 4. Figure 3 is an exploded perspective view showing the electronic board box 9 and interface panel 20 in embodiment 1. Figure 4 is a perspective view showing the electronic board box 9 and interface panel 20 shown in Figure 3 assembled together.

As shown in Figure 3, the electronic board box 9 has a box-shaped lower box 9a that opens upward, a top cover 9b that covers the top opening of the lower box 9a, an electronic board 9c, and a heat sink 9d. The electronic board 9c is fixed inside the lower box 9a. The electronic board 9c has an internal power line 15 that connects to the terminal block 21 and a compressor drive wire 13 that connects to the compressor 8. Although not shown, the electronic board 9c also has various power lines for operating the heat generating elements, fan motor 5b, and other driving equipment.

The heat sink 9d is fixed to the electronic board 9c in close contact with the electronic board 9c. The heat sink 9d serves to cool the heat-generating elements on the electronic board 9c. The heat-generating elements are, for example, power semiconductors such as IGBTs (Insulated Gate Bipolar Transistors). The electronic board 9c with the heat sink 9d fixed thereto is inserted into the lower box 9a through an opening in the top of the lower box 9a. As shown in Figure 4, part or all of the heat sink 9d is exposed to the outside of the lower box 9a through a hole 9e formed in the bottom wall of the lower box 9a.

The lower box 9a and top cover 9b shown in FIG. 3 are formed from, for example, rubber, resin, or metal such as iron, or a combination of these. For example, if the lower box 9a and top cover 9b are formed from metal, the electronic board 9c is covered with metal, which can suppress the radiation of electromagnetic noise generated by the electronic board 9c to the outside of the electronic board box 9. There is a risk that moisture such as rainwater scattered in the fan chamber 10 may enter the electronic board box 9 and the electrical chamber 11 through the hole 9e formed in the bottom wall of the lower box 9a. Therefore, in practice, measures are taken to ensure the waterproofing of the electronic board box 9 and the electrical chamber 11 by modifying the shape of the hole 9e and the shape of the lower box 9a to make it difficult for moisture to enter, or by adding new waterproofing structures.

The interface panel 20 has an interface vertical wall 20a, an upper joint flange portion 20b, an interface horizontal wall 20c, and a lower joint flange portion 20d. The interface vertical wall 20a is a vertical wall extending along the Y-axis direction. The upper joint flange portion 20b extends horizontally in the Z-axis direction from the upper end of the interface vertical wall 20a. The upper joint flange portion 20b is joined to the underside of the bottom wall of the lower box 9a. The interface horizontal wall 20c extends horizontally in the Z-axis direction from the lower end of the interface vertical wall 20a. The lower joint flange portion 20d extends downward in the Y-axis direction from the tip of the interface horizontal wall 20c. The lower joint flange portion 20d is joined to the inner surface of the housing side panel 2d shown in FIG. 2. The interface panel 20 is fixed to and electrically connected to the housing side panel 2d at the lower joint flange portion 20d. The interface panel 20 is fixed to the housing side panel 2d and the lower box 9a.

Next, the configuration of the right side of the outdoor unit 1 will be described with reference to Figure 5. Figure 5 is a right side view showing the outdoor unit 1 of the air conditioner in embodiment 1.

An opening 2k that connects the inside and outside of the housing 2 is formed in the housing side panel 2d. An interface cover 22 is removably attached to the housing side panel 2d. The interface cover 22 can be opened and closed by being attached and detached. When closed, the interface cover 22 covers the opening 2k. When open, the interface cover 22 opens the opening 2k. The interface panel 20 and terminal block 21 installed in the electrical room 11 are visible and accessible through the opening 2k. Wiring of various power lines can be performed by opening the interface cover 22 and through the opening 2k.

The interface cover 22 ensures ventilation between the electrical chamber 11 and the outside of the housing 2 while preventing the intrusion of moisture such as rainwater into the electrical chamber 11. The interface cover 22 is made of resin, a metal such as iron, or a combination of these. When the interface cover 22 is made of a metal such as iron and is joined to the housing side panel 2d with low electrical resistance, closing the opening 2k with the interface cover 22 can suppress the radiation of electromagnetic noise from the opening 2k to the outside of the housing 2.

Although not shown in the figures, the interface cover 22 has a through hole formed therein to ensure ventilation between the electrical chamber 11 and the outside of the housing 2 and to allow power lines to pass between the electrical chamber 11 and the outside of the housing 2. Waterproofing measures are taken in the through hole to prevent rainwater and other moisture from entering the electrical chamber 11. Examples of waterproofing measures include filling the gaps in the through hole with sponge or making the through hole a shutter structure.

Next, the configuration of the partition plate 4 will be described with reference to Figure 6. Figure 6 is a cross-sectional view taken along line VI-VI shown in Figure 2. In Figure 6, for ease of understanding, only the housing 2 is hatched with diagonal lines.

The partition plate 4 has a first partition portion 4a and a second partition portion 4b connected to the rear end of the first partition portion 4a. An inlet hole 4c is formed in the second partition portion 4b for introducing the Z-axis end of the heat exchanger 6 into the electrical chamber 11. The heat exchanger 6 and the second partition portion 4b are made of dissimilar metals. To avoid contact between the dissimilar metals, it is preferable to interpose a resin material between the heat exchanger 6 and the second partition portion 4b, for example.

Next, the configuration of the grid 3 will be explained with reference to Figure 7. Figure 7 is a rear view showing the grid 3 in embodiment 1.

The grid 3 has a fixed frame 31, multiple metal wires 32, multiple intersections 33, and multiple grid connection sections 34. The grid 3 is a grid-shaped member formed by crossing multiple metal wires 32 in the Y-axis direction and the Z-axis direction. There are no particular restrictions on the material of the grid 3, as long as it is the same first metal as the housing 2.

The fixed frame 31 has a rectangular frame shape when viewed from behind. The fixed frame 31 has a first vertical frame portion 31a, a second vertical frame portion 31b, a first horizontal frame portion 31c, and a second horizontal frame portion 31d. The first vertical frame portion 31a and the second vertical frame portion 31b extend along the Y-axis direction. The first vertical frame portion 31a and the second vertical frame portion 31b are arranged parallel to each other with a gap in the Z-axis direction. The first horizontal frame portion 31c and the second horizontal frame portion 31d extend along the Z-axis direction. The first horizontal frame portion 31c and the second horizontal frame portion 31d are arranged parallel to each other with a gap in the Y-axis direction. The first horizontal frame portion 31c connects the upper end of the first vertical frame portion 31a to the upper end of the second vertical frame portion 31b. The second horizontal frame portion 31d connects the lower end of the first vertical frame portion 31a and the lower end of the second vertical frame portion 31b.

The metal wires 32 include a plurality of first metal wires 32a extending vertically and a plurality of second metal wires 32b extending horizontally. The first metal wires 32a extend along the Y-axis direction and span the first horizontal frame portion 31c and the second horizontal frame portion 31d. The plurality of first metal wires 32a are arranged in parallel with each other at equal intervals A in the Z-axis direction. The second metal wires 32b extend along the Z-axis direction and span the first vertical frame portion 31a and the second vertical frame portion 31b. The plurality of second metal wires 32b are arranged in parallel with each other at equal intervals B in the Y-axis direction. Hereinafter, the interval A may be referred to as the lattice interval A, and the interval B may be referred to as the lattice interval B.

The intersection 33 is the portion where the first metal wire 32a and the second metal wire 32b intersect with each other. The intersection 33 is the portion where the first metal wire 32a and the second metal wire 32b are fixed to each other and electrically connected to each other. The first metal wire 32a and the second metal wire 32b are fixed to each other by, for example, welding or screws.

The grid connection portion 34 is the portion where both ends of the metal wire 32 along its extension direction are fixed onto the fixed frame 31. The grid connection portion 34 is the portion where the metal wire 32 and the fixed frame 31 are fixed to each other and electrically connected to each other. The metal wire 32 and the fixed frame 31 are fixed to each other by welding or screws, for example.

The lattice spacing A and lattice spacing B of the lattice element 3 are equal to or less than half the wavelength of the electromagnetic noise generated from inside the housing 2. The lattice element 3 is disposed in the path of air flowing toward the fan chamber 10 shown in FIG. 2 and passing through the heat exchanger 6, and is disposed upstream of the heat exchanger 6 in the air flow direction. Therefore, it is desirable to make the thickness of the metal wire 32 thin enough that the adverse effects of ventilation on the heat exchanger 6 are negligible, and thick enough that impedance components such as electrical resistance are sufficiently small. It is also desirable to make the thickness of the fixing frame 31 thin enough that the adverse effects of ventilation on the heat exchanger 6 are negligible.

Figure 8 is a rear view showing the outdoor unit 1 of the air conditioner according to embodiment 1, showing the state in which the lattice member 3 is attached to the housing 2. The housing 2 is formed with an air intake port 2m for allowing outdoor air to flow in. The air intake port 2m is an opening for allowing air outside the housing 2 to flow into the fan chamber 10. The air intake port 2m is formed by being surrounded by the housing floor panel 2a, the housing back panel 2j, the housing top panel 2b, and the housing side panel 2g.

The grid element 3 is arranged alongside the housing rear panel 2j in the Z-axis direction. The grid element 3 is fixed to the housing floor panel 2a, the housing top panel 2b, the housing rear panel 2j, and the housing side panel 2g at the position of the air intake vent 2m. The grid element 3 and the housing 2 are electrically connected. The second horizontal frame portion 31d of the fixing frame 31 is fixed to and electrically connected to the housing floor panel 2a. The first horizontal frame portion 31c of the fixing frame 31 is fixed to and electrically connected to the housing top panel 2b. The first vertical frame portion 31a of the fixing frame 31 is fixed to and electrically connected to the housing rear panel 2j. The second vertical frame portion 31b of the fixing frame 31 is fixed to and electrically connected to the housing side panel 2g. The grid element 3 and the housing 2 are fixed together by, for example, welding or screws.

Next, the configuration of the housing 2, blower 5, heat exchanger 6, and grid 3 will be further described with reference to Figure 9. Figure 9 is a cross-sectional view taken along line IX-IX shown in Figure 8.

An exhaust port 2n is formed in the front panel main body 2e of the housing front panel 2c. The exhaust port 2n is an opening for discharging the airflow generated by the blower 5 to the outside of the fan chamber 10. A bell mouth 23 is provided on the inner surface of the exhaust port 2n to improve ventilation between the inside and outside of the fan chamber 10. A front cover 24 with ventilation holes 25 is attached to the front panel main body 2e in front of the exhaust port 2n. The front cover 24 ensures ventilation between the inside and outside of the fan chamber 10 while preventing foreign matter from entering the inside of the fan chamber 10. Foreign matter includes, for example, dust and dirt. When the fan motor 5b rotates and the propeller fan 5c is driven, negative pressure is created in the fan chamber 10, and air from outside the outdoor unit 1 flows into the fan chamber 10 through the air intake 2m. The air that has flowed into the fan chamber 10 passes through the heat exchanger 6, is formed into an air flow by the blower 5, and is discharged to the outside of the fan chamber 10 through the exhaust port 2n.

The upper end of the support pillar 5a extends rearward along the top panel 2b of the housing. The upper end of the support pillar 5a is fixed to the heat exchanger 6 via a second insulating member 7b on the rear side of the housing 2. The first horizontal frame portion 31c, which forms the upper end of the lattice element 3, may be fixed to and electrically connected to the upper end of the support pillar 5a, or it may not be fixed to and electrically connected to the upper end of the support pillar 5a. The heat exchanger 6 and the lattice element 3 are arranged at a distance from each other in the X-axis direction. The heat exchanger 6 and the lattice element 3 are also connected via multiple members, including the insulating member 7. The heat exchanger 6 and the lattice element 3 are arranged so as not to be electrically connected.

A top flange portion 2o is formed on the periphery of the housing top panel 2b, folding it downward. The top flange portion 2o is arranged to cover the housing front panel 2c and the grid 3 from the outside of the housing 2. The top flange portion 2o is fixed to the housing front panel 2c and the grid 3. Although not shown in Figure 9, the top flange portion 2o is also arranged to cover the housing side panel 2d from the outside of the housing 2, and is also fixed to the housing side panel 2d. It is desirable to electrically connect the grid 3 and the top flange portion 2o to minimize the gap between them.

A bottom flange portion 2p is formed on the periphery of the housing floor panel 2a, folding upward. The bottom flange portion 2p is positioned on the inside of the housing 2 between the housing front panel 2c and the grid 3. The bottom flange portion 2p is fixed to the housing front panel 2c and the grid 3. Although not shown in Figure 9, the bottom flange portion 2p is also positioned on the inside of the housing 2 between the housing side panel 2d. The bottom flange portion 2p is also fixed to the housing side panel 2d. It is desirable to electrically connect the grid 3 and the bottom flange portion 2p to minimize the gap between them.

Next, the configuration of the heat exchanger 6 will be further described with reference to Figures 10 to 12. Figure 10 is a schematic perspective view of the heat exchanger 6 in embodiment 1. Figure 11 is a front view of the heat exchanger 6 in embodiment 1. Figure 12 is an enlarged view of a main portion of the heat exchanger 6 shown in Figure 11.

As shown in Figure 10, the heat exchanger 6 is a parallel flow type heat exchanger in this embodiment. As shown in Figure 11, the heat exchanger 6 has two headers 6a and 6b, multiple refrigerant conduits 6c, and multiple fins 6d.

The two headers 6a, 6b are both hollow metal members. Each header 6a, 6b extends along the Y-axis direction. As shown in Figure 10, the two headers 6a, 6b are spaced apart from each other in the Z-axis direction and offset from each other in the X-axis direction. A refrigerant pipe 18 is connected to header 6b.

Each refrigerant conduit 6c shown in Figure 11 is a hollow metal member. Each refrigerant conduit 6c is, for example, a flat pipe. The multiple refrigerant conduits 6c are arranged at intervals from one another in the Y-axis direction. Each refrigerant conduit 6c extends from one header 6a to the other header 6b. The extension direction of each refrigerant conduit 6c is perpendicular to the Y-axis direction. One end of each refrigerant conduit 6c in the extension direction is connected to one header 6a, and the other end of each refrigerant conduit 6c in the extension direction is connected to the other header 6b. Each refrigerant conduit 6c connects one header 6a to the other header 6b.

The fins 6d are metal plate-shaped members. The fins 6d are arranged between adjacent refrigerant conduits 6c. There are no particular limitations on the shape of the fins 6d, but in this embodiment, they have a wave-like shape that protrudes alternately upward and downward. That is, in this embodiment, corrugated fins are used for the fins 6d. As shown in Figure 12, the fins 6d contact each of the adjacent refrigerant conduits 6c and are joined by welding or the like.

Refrigerant flows inside the headers 6a, 6b and inside the refrigerant conduit 6c shown in Figure 11. One of the two headers 6a, 6b serves to distribute the refrigerant to each of the multiple refrigerant conduits 6c. The other of the two headers 6a, 6b serves to merge the refrigerant flowing out from each of the multiple refrigerant conduits 6c. The refrigerant conduit 6c serves to exchange heat between the refrigerant and the outdoor air. That is, heat exchange occurs between the refrigerant flowing inside the refrigerant conduit 6c and the outdoor air flowing around the refrigerant conduit 6c. The fins 6d serve to promote heat exchange between the refrigerant and the outdoor air.

Next, we will explain the operation and effects of the outdoor unit 1 in embodiment 1.

As shown in FIG. 2, when power is supplied to the electronic board 9c from the external AC power line 14 via the internal power line 15, the electronic board 9c enters a standby state. When the electronic board 9c receives a command signal to start operation from the indoor unit via a communication signal line between the indoor unit and the outdoor unit 1 (not shown), it starts operating the outdoor unit 1. Specifically, the electronic board 9c outputs a drive signal to the fan motor 5b via the fan drive wire 12, driving the fan motor 5b. The electronic board 9c also outputs another drive signal to the compressor 8 via the compressor drive wire 13, driving the compressor 8. The drive signal output by the electronic board 9c typically uses a square-wave pulse generated by the switching of a power semiconductor. Therefore, the drive signal contains high-frequency components that are not actually required to drive the AC motors of the compressor 8 and fan motor 5b, such as switching noise from the power semiconductor and harmonic components of the square-wave pulse. These high-frequency components act as a source of electromagnetic noise and contribute to the radiation of electromagnetic noise outside the housing 2 via the transmission path described below.

Figure 13 is a schematic diagram showing, as an electrical circuit, the transmission path of electromagnetic noise generated in the outdoor unit 1 of the air conditioner according to embodiment 1. In Figure 13, the heat exchanger 6 is indicated by dotted hatching for ease of understanding. For example, if a three-phase AC motor is used for the compressor 8, electromagnetic noise generated on the electronic board 9c is transmitted to the compressor 8's housing via the three-phase motor winding neutral point 8d and the parasitic capacitance 8b existing between the motor winding 8a and the compressor 8's housing. A portion of the electromagnetic noise transmitted to the compressor 8's housing is transmitted to the housing floor panel 2a and then returned to the electronic board 9c. However, due to impedance components such as the contact resistance 8c between the compressor 8's housing and the housing floor panel 2a, a portion of the electromagnetic noise transmitted to the compressor 8's housing is transmitted to the heat exchanger 6 through the refrigerant piping 18.

The characteristics of the parasitic impedance components of the heat exchanger 6 vary depending on the structure of the heat exchanger 6. As an example, assume that the heat exchanger 6 is a parallel-flow heat exchanger equipped with fins 6d and flat refrigerant conduits 6c, as shown in Figure 11. An equivalent circuit is shown in which the parasitic inductance 27 of the heat exchanger 6 is combined as shown in Figure 13. The parasitic impedance components, such as the parasitic inductance 27 of the heat exchanger 6, exist in a complex distributed constant circuit as shown in Figure 13. Because the heat exchanger 6 and the housing 2 are electrically insulated by the first insulating member 7a and the second insulating member 7b, parasitic capacitances 26a and 26b are generated between the heat exchanger 6 and the housing 2. Specifically, parasitic capacitance 26a is generated between the heat exchanger 6 and the housing bottom panel 2a, and parasitic capacitance 26b is generated between the heat exchanger 6 and the housing top panel 2b. The parasitic capacitances 26a and 26b are generated on the electromagnetic noise transmission path.

Figure 14 is an equivalent circuit diagram of the path of current transmission that causes electromagnetic noise in the outdoor unit 1 of the air conditioner according to embodiment 1. Electromagnetic noise transmitted from the electronic board 9c through the compressor 8 to the heat exchanger 6 and the housing 2 shown in Figure 13 generates resonance with the parasitic inductance 27 of the heat exchanger 6, generates resonance with the parasitic capacitances 26a and 26b, and generates resonance with the parasitic impedance components such as the parasitic inductance 28 of each panel of the housing 2. Because the heat exchanger 6 and the housing floor panel 2a are electrically insulated by the first insulating member 7a shown in Figure 13 and the heat exchanger 6 and the housing top panel 2b are electrically insulated by the second insulating member 7b, a voltage change due to resonance occurs in the parasitic capacitances 26a and 26b.

Figure 15 is a rear view of the outdoor unit 1 of the air conditioner according to embodiment 1, showing the state with the grid 3 removed and the locations where electromagnetic noise occurs. In Figure 15, the heat exchanger 6 is indicated by dot hatching for ease of understanding. Gaps G1, G2, G3, and G4 are formed between the heat exchanger 6 and each panel of the housing 2 to ensure electrical insulation. In Figure 15, the locations of the gaps G1, G2, G3, and G4 are surrounded by dashed lines. While Figure 15 shows that there are no gaps G1, G2, G3, or G4 between the heat exchanger 6 and the housing 2 in some areas, in reality, there are elongated gaps G1, G2, G3, and G4 that extend around the four sides of the heat exchanger 6. Gaps G1, G2, G3, and G4 are locations where electromagnetic noise occurs. Voltage changes occur between the heat exchanger 6 and the housing bottom panel 2a and between the heat exchanger 6 and the housing top panel 2b through the parasitic capacitances 26a and 26b shown in Figure 13. As a result, the gaps G1, G2, G3, and G4 function as slot antennas, generating additional electromagnetic noise in response to changes in voltage applied across the gaps G1, G2, G3, and G4. The electromagnetic noise generated in the gaps G1, G2, G3, and G4 is radiated to the outside of the housing 2 through the air intake vent 2m.

Figure 16 is an equivalent circuit diagram of the path of current transmission that causes electromagnetic noise when the heat exchanger 6 and the housing 2 are in direct contact without the insulating member 7 in the outdoor unit 1 of the air conditioner according to embodiment 1. By removing the first insulating member 7a and the second insulating member 7b shown in Figure 15, the heat exchanger 6 and each panel of the housing 2 are electrically connected. In other words, the heat exchanger 6 and each panel of the housing 2 are electrically short-circuited. Therefore, as shown in Figure 16, the parasitic capacitances 26a and 26b generated between the heat exchanger 6 and each panel of the housing 2 are short-circuited. As a result, no voltage change occurs between the heat exchanger 6 and the housing floor panel 2a shown in Figure 15 and between the heat exchanger 6 and the housing top panel 2b through the parasitic capacitances 26a and 26b shown in Figure 16, and electromagnetic noise does not occur in the gaps G1, G2, G3, and G4.

When the heat exchanger 6 and housing 2 shown in Figure 15 are made of dissimilar metals, if an insulating member 7 is not provided between the heat exchanger 6 and housing 2, electromagnetic noise generation in gaps G1, G2, G3, and G4 can be prevented and electromagnetic noise radiation outside the housing 2 can be reduced, but corrosion will occur in the heat exchanger 6, which has a low standard electrode potential, at the contact points between the heat exchanger 6 and housing 2. On the other hand, if an insulating member 7 is provided between the heat exchanger 6 and housing 2, corrosion will be prevented in the heat exchanger 6, which has a low standard electrode potential, at the contact points between the heat exchanger 6 and housing 2, but electromagnetic noise will be generated in gaps G1, G2, G3, and G4, increasing the amount of electromagnetic noise radiation outside the housing 2.

Figure 17 is a rear view of the outdoor unit 1 of the air conditioner according to the first embodiment, showing the state in which the grid 3 is attached and the locations where electromagnetic noise occurs. In Figure 17, the heat exchanger 6 is indicated by dotted hatching for ease of understanding. In this embodiment, the outdoor unit 1 includes a metal grid 3 that is positioned upstream of the heat exchanger 6 in the air flow direction and spaced apart from the heat exchanger 6, and is fixed to and electrically connected to the housing 2. This divides the gaps G1, G2, G3, and G4 at grid intervals A and B by the grid 3. This suppresses electromagnetic noise radiation from the gaps G1, G2, G3, and G4 to the outside of the housing 2 via the air intake vent 2m, thereby reducing the amount of electromagnetic noise radiation from the housing 2. The frequency of the electromagnetic noise that is suppressed from radiating to the outside of the housing 2 is determined by the grid intervals A and B between adjacent metal wires 32.

In contrast, in this embodiment, as shown in Figures 15 and 17, the outdoor unit 1 includes a box-shaped housing 2 made of a first metal, a heat exchanger 6 formed at least in part from a second metal having a standard electrode potential different from that of the first metal, disposed within the housing 2, and fixed to the housing 2 via an insulating member 7, and a grid 3 disposed away from the heat exchanger 6. This prevents electrical connection between the heat exchanger 6 and the housing 2, and also prevents electrical connection between the heat exchanger 6 and the grid 3. This prevents corrosion due to contact between dissimilar metals. Furthermore, in this embodiment, the grid 3 is formed from the same first metal as the housing 2, thereby preventing corrosion due to contact between the grid 3 and the housing 2. Therefore, in this embodiment, simply by providing the metal grid 3 and the non-conductive insulating member 7, corrosion prevention and electromagnetic noise reduction can be simultaneously achieved. In other words, corrosion prevention and electromagnetic noise reduction can be achieved with a structure that is less expensive and simpler than conventional structures.

In this embodiment, because the standard electrode potential of the first metal is higher than the standard electrode potential of the second metal, if the heat exchanger 6 is electrically connected to the housing 2 and the grid 3, corrosion will occur in the heat exchanger 6, which is made of the second metal. In this embodiment, however, the heat exchanger 6 is not electrically connected to the housing 2 and the grid 3, as described above, so corrosion of the heat exchanger 6 can be prevented.

In this embodiment, the first metal is iron, which increases the strength of the housing 2 made of the first metal. Furthermore, in this embodiment, the second metal is aluminum, which increases the thermal conductivity of the heat exchanger 6 made of the second metal.

In this embodiment, the lattice spacings A and B of the lattice element 3 are less than half the wavelength of the electromagnetic noise generated from inside the housing 2, thereby further reducing electromagnetic noise.

In this embodiment, the grid 3 is fixed to the housing floor panel 2a, the housing top panel 2b, the housing back panel 2j, and the housing side panel 2g, thereby improving the electrical connection between each panel and reducing the contact resistance and parasitic inductance 28 of the housing 2. This reduces the electromagnetic noise, i.e., noise terminal voltage and interference power intensity, transmitted between the electronic board 9c, the compressor 8, and each panel of the housing 2. Note that the grid 3 only needs to be fixed to at least one of the housing floor panel 2a, the housing top panel 2b, the housing back panel 2j, and the housing side panel 2g.

Conventional heat exchangers include serpentine heat exchangers and aluminum parallel-flow heat exchangers. Both serpentine and parallel-flow heat exchangers have fins and refrigerant conduits. In serpentine heat exchangers, aluminum is typically used for the fins and copper for the refrigerant conduits. When iron is used for the housing 2, the magnitude relationship of the standard electrode potentials of the respective metals is aluminum < iron < copper. In other words, the magnitude relationship of the standard electrode potentials of the respective metal components is fins < housing 2 < refrigerant conduits. If the fins and refrigerant conduits of a serpentine heat exchanger are in direct contact with the housing 2 and moisture adheres to the contact points, corrosion may occur in the fins, which have a lower standard electrode potential than the housing 2, but corrosion will not occur in the refrigerant conduits, which have a higher standard electrode potential than the housing 2.

On the other hand, in aluminum parallel-flow heat exchangers, aluminum is used for the fins and refrigerant conduits. Therefore, if iron is used for the housing 2, corrosion may occur in both the fins and the refrigerant conduits. If corrosion occurs in the refrigerant conduits and holes form, the refrigerant inside the refrigerant conduits will leak into the atmosphere. This leakage of refrigerant into the atmosphere impairs the air conditioner's heating and cooling functions. Because corrosion is so detrimental to aluminum parallel-flow heat exchangers, it is important to take measures to prevent corrosion. Measures to reduce the electromagnetic noise generated by taking corrosion prevention measures must also be taken. Therefore, achieving both corrosion prevention and electromagnetic noise reduction using the grid 3 and insulating member 7, as in this embodiment, is particularly useful when using heat exchangers, such as aluminum parallel-flow heat exchangers, where corrosion is a significant detriment. In other words, using the grid 3 and insulating member 7 as in this embodiment to prevent corrosion and reduce electromagnetic noise is particularly useful when using a heat exchanger in which the standard electrode potential of the refrigerant conduit is lower than the standard electrode potential of surrounding components such as the housing 2.

The configuration of the grid 3 is not limited to the example shown in Figure 8. For example, the grid 3 may not have a fixed frame 31, and the metal wire 32 may be fixed directly to the housing 2. Furthermore, it is not necessary for all four frame portions of the fixed frame 31 to be electrically connected to the housing 2; it is sufficient that at least one of the four frame portions of the fixed frame 31 is electrically connected to the housing 2. Even in this case, the same effects as those of the first embodiment described above can be achieved.

In this embodiment, a square-shaped fixed frame 31 is exemplified, but it is not necessary for the fixed frame 31 to have four frame portions. For example, the fixed frame 31 may not have the second horizontal frame portion 31d, and one end of the first metal wire 32a in the Y-axis direction may be a free end without being fixed to the fixed frame 31. In this case, there is a possibility that electromagnetic noise may be radiated to some extent from the lower end of the lattice body 3, but because the lower end of the lattice body 3 is close to the installation surface, such as the ground, the adverse effect on electromagnetic noise is limited, and the same effect as in embodiment 1 described above can be achieved.

The method for manufacturing the grid 3 is not particularly limited. For example, the grid 3 may be manufactured by fixing metal wires 32 formed separately from the fixed frame 31 to the fixed frame 31, or by integrally molding the fixed frame 31 and metal wires 32 using a sheet metal punching process. Integrating the fixed frame 31 and metal wires 32 in this way allows the outdoor unit 1 to be manufactured in an even cheaper and simpler manner.

The entire heat exchanger 6 does not need to be made of the second metal; it is sufficient that at least a portion of the heat exchanger 6 is made of the second metal. For example, it is sufficient that at least one of the fins and refrigerant conduits of the heat exchanger 6 is made of the second metal.

The configurations shown in the above embodiments are merely examples and may be combined with other known technologies, and parts of the configurations may be omitted or modified without departing from the spirit of the invention.

1. Outdoor unit of air conditioner, 2. Housing, 2a. Floor panel of housing, 2b. Top panel of housing, 2c. Front panel of housing, 2d. Side panel of housing, 2e. Main body of front panel, 2f. Extended front panel, 2g. Side panel of housing, 2h. Main body of side panel, 2i. Extended side panel, 2j. Rear panel of housing, 2k. Opening, 2m. Air intake port, 2n. Exhaust port, 2o. Top flange, 2p. Bottom flange, 3. Lattice, 4. Partition plate, 4a. First partition, 4b. Second partition, 4c. Inlet hole, 5. Blower, 5a. Support, 5b. Fan motor, 5c. Propeller fan, 6. Heat exchanger, 6a, 6b. Header, 6c. Refrigerant conduit, 6d. Fin, 7. Insulating member, 7a. First insulating member, 7b. Second insulating member, 8. Compressor, 8a. Motor winding, 8b, 26a, 26b parasitic capacitance, 8c contact resistance, 8d three-phase motor winding neutral point, 9 electronic circuit board box, 9a lower box, 9b upper cover, 9c electronic circuit board, 9d heat sink, 9e hole, 10 fan chamber, 11 electrical chamber, 12 fan drive wire, 13 compressor drive wire, 14 external AC power line, 15 internal power line, 16 earth wire, 17 stop valve, 18 refrigerant piping, 19 connection part, 20 interface panel, 20a interface vertical wall, 20b upper connecting flange part, 20c interface horizontal wall, 20d lower connecting flange part, 20e earth connection point, 21 terminal block, 22 interface cover, 23 bell mouth, 24 front cover, 25 ventilation holes, 27, 28 parasitic inductance, 31 fixing frame, 31a First vertical frame portion, 31b: second vertical frame portion, 31c: first horizontal frame portion, 31d: second horizontal frame portion, 32: metal wire, 32a: first metal wire, 32b: second metal wire, 33: intersection portion, 34: grid connection portion.

Claims (5)

a box-shaped housing made of a first metal and having an air intake port for letting in outside air;
a heat exchanger at least a portion of which is formed from a second metal having a standard electrode potential different from that of the first metal, the heat exchanger being disposed within the housing and fixed to the housing via a non-conductive member;
a grid member that is disposed upstream of the heat exchanger in the air flow direction and spaced apart from the heat exchanger, that is fixed to the housing and electrically connected to the housing, and that is made of the first metal;
Equipped with
A gap is formed between the heat exchanger and the housing,
the grid element includes a fixed frame that is disposed at a position overlapping with the gap when viewed along the air flow direction and is fixed to the housing,
the housing has a housing floor panel, a housing top panel disposed above the housing floor panel and spaced apart from the housing floor panel, and a housing back panel and housing side panels connecting the housing floor panel and the housing top panel,
a top flange portion folded downward is formed on the periphery of the top panel of the housing;
the top flange portion and the fixing frame are fixed in a state where they are butted against each other in a direction opposite to the air flow direction,
The bottom flange portion is formed on the periphery of the floor panel of the housing, and is folded upward.
The bottom flange portion and the fixing frame are fixed in a state where they are abutted against each other in the air flow direction. An outdoor unit for an air conditioner according to claim 1, wherein the standard electrode potential of the first metal is higher than the standard electrode potential of the second metal. the first metal is iron;
3. The outdoor unit of an air conditioner according to claim 1, wherein the second metal is aluminum. An outdoor unit for an air conditioner according to any one of claims 1 to 3, wherein the heat exchanger is a parallel flow type heat exchanger. An outdoor unit for an air conditioner according to any one of claims 1 to 4, wherein the lattice spacing of the lattice element is equal to or less than half the wavelength of electromagnetic noise generated from inside the housing.