JP7676052B2 - Drainage pump - Google Patents

Description

The present invention relates to a drainage pump.

When an air conditioner is in cooling mode, moisture in the air is cooled and condenses in the heat exchanger of the indoor unit, and the water droplets drip into the drain pan located below the heat exchanger. In the case of a wall-mounted indoor unit, the drain water that accumulates in the drain pan is discharged to the outdoors through a drain pipe by gravity. On the other hand, in the case of indoor units such as ceiling-embedded types, it is generally difficult to arrange a drain pipe so that gravity can be used to drain the water. Therefore, in these types of indoor units, a drain pump that uses a motor as a power source to drain the water is installed.

Patent Document 1 discloses a drainage pump equipped with a motor. In this drainage pump, legs are formed extending upward from an upper case, and the upper ends of the legs are fastened to the indoor unit of an air conditioner, thereby attaching the drainage pump to the structure.

JP 2012-082790 A

The drainage pump in Patent Document 1 drains water by driving a rotating blade with a motor. Here, vibrations that occur during drainage are transmitted to the indoor unit via the legs of the drainage pump, causing resonance and resulting in noise.

One idea for suppressing this type of noise is to place anti-vibration rubber between the mounting part of the indoor unit and the legs to make it harder for the vibrations of the drainage pump to be transmitted to the indoor unit. However, if anti-vibration rubber is required when installing the drainage pump, the cost of the parts will increase and the effort required to install the drainage pump will also increase.

Therefore, the present invention aims to provide a drainage pump that can suppress the transmission of vibrations without increasing the number of parts and is easy to install.

In order to achieve the above object, the drainage pump of the present invention comprises:
A drainage pump having a case that houses a rotor and a motor that drives the rotor,
The case has a plurality of legs protruding along a rotation axis direction of the rotor blades,
The leg portion includes a leg body fixed to a mounting portion and a plurality of plate-shaped portions connecting the leg body and the case,
When viewed through the plate-like portions, a first gap is formed between the case and the leg body.

According to the present invention, it is possible to provide a drainage pump that can suppress the propagation of vibrations without increasing the number of parts and is easy to install.

FIG. 1 is a perspective view of a drainage pump according to a first embodiment. FIG. 2 is a perspective view of the drainage pump according to the first embodiment. FIG. 3 is a side view of the drainage pump shown attached to a mounting portion. FIG. 4 is a top view of the drainage pump. FIG. 5 is a side view of the drive unit shown removed from the housing. FIG. 6 is a side view of the drive unit shown removed from the housing. FIG. 7 is a perspective view similar to FIG. 1 of a drainage pump according to a comparative example. FIG. 8 is an enlarged plan view of the second leg portion of the present embodiment taken along the direction of the rotation axis. FIG. 9 is an enlarged plan view of the second leg of the comparative example taken along the rotation axis direction. FIG. 10 is a graph comparing noise levels between this embodiment and the comparative example. FIG. 11 is a perspective view of a drive unit according to the second embodiment. FIG. 12 is a view of one of the legs of the drive unit in a modified example of the second embodiment, seen from the outside along the radial direction. FIG. 13 is a diagram showing the relationship between the overall noise value (OA value) during operation of the drainage pump to which the first modification is applied and the size of the first gap (H1-H2). FIG. 14 is a view similar to FIG. 12, showing another modified example.

First Embodiment
Figures 1 and 2 are perspective views of a drainage pump 1 according to a first embodiment of the present invention, but are shown from different viewing angles. Figure 3 is a side view of the drainage pump 1 shown in an installed state. Figure 4 is a top view of the drainage pump 1. The rotation axis of the rotor assembly and the rotating blades built into the drainage pump 1 is designated as X.

The drainage pump 1 has a drive unit 3 with a built-in motor, and a housing 2 made of synthetic resin that houses a rotor assembly and rotating blades (not shown). The housing 2 has a cylindrical upper housing 21 with a bottom that rotatably houses the rotor assembly, and a lower housing 22 that rotatably houses the rotating blades. The motor is connected to the rotor assembly so that it can be rotated, and the rotor assembly is connected to the rotating blades so that they can rotate together. The rotor assembly and rotating blades may be, but are not limited to, those disclosed in JP 2014-107893 A. Here, the drive unit 3 side is described as the upper side, and the lower housing 22 side is described as the lower side.

The lower housing 22 has a hollow inlet cylindrical portion 22b connected to the central lower end and a hollow outlet cylindrical portion 22c connected to the side wall, and has a pump chamber inside in which rotor blades are arranged. The pump chamber and the outside of the lower housing 22 are connected via the inlet cylindrical portion 22b and the outlet cylindrical portion 22c.

The upper housing 21 and the lower housing 22 are separable, and when connected, the gap between them is sealed with an O-ring or the like. The upper housing 21 can be attached to the lower housing 22 by a snap-fit function using a pair of elastically deformable locking claws 22a formed to protrude from the outer periphery of the upper end of the lower housing 22.

Figures 5 and 6 are side views of the drive unit 3 removed from the housing 2, with Figure 5 showing the state as seen from the direction of arrow A in Figure 4, and Figure 6 showing the state as seen from the direction of arrow B in Figure 4. In Figures 4 to 6, the drive unit 3 has a cylindrical housing lid 31 made of synthetic resin with a top, and a motor (not shown) housed within the housing lid 31. A connector 32 (see Figures 2 and 3) equipped with terminals 32a to which wiring (not shown) is connected is attached to the upper side surface of the upper housing 21, and power is supplied to the motor within the housing lid 31 from an external power source (not shown) via the connector 32. The housing lid 31 has a notch 31c to avoid interference with the connector 32.

The outer periphery of the lower end of the housing lid 31 fits into the inner periphery of the upper end of the upper housing 21. The housing lid 31 is removably attached to the upper housing 21 by a snap-fit function using elastically deformable locking claws 31a that protrude from and are connected to the outer periphery of the lower end of the housing lid 31. The housing 2 and the housing lid 31 together form the case of the drainage pump.

(Leg configuration)
The housing lid 31 is formed by connecting a plurality of (three in this example) legs 33, 34, 35 that protrude upward along the direction of the rotation axis X. In Fig. 4, the first leg 33 includes a disk-shaped leg body 33a and a plurality of (three in this example) plate-like portions 33b, 33c, 33d that extend in parallel at equal intervals from the leg body 33a toward the housing lid 31. The plate-like portions 33b, 33c, 33d have a generally trapezoidal shape that widens toward the lower end, with the plate-like portion 33b being the longest and the plate-like portion 33d being the shortest. A hole 33e is formed in the center of the leg body 33a for inserting a fastening bolt (not shown).

The side edges near the upper ends of the plate-shaped parts 33b, 33c, and 33d are connected to the outer periphery of the leg body 33a, and the lower ends of the plate-shaped parts 33b, 33c, and 33d are connected across the upper surface of the housing lid part 31 and the upper part of the side surface adjacent to the upper surface (the tapered part 31b having an arc-shaped cross section). By integrating the plate-shaped parts 33b, 33c, and 33d with the housing lid part 31 by wrapping the lower ends of the plate-shaped parts 33b, 33c, and 33d around the side surface from the upper surface of the housing lid part 31, it becomes easier to remove the molded product when forming the housing lid part 31 by injection molding, etc., and manufacturing costs can be reduced. However, the lower ends of the plate-shaped parts 33b, 33c, and 33d may be connected only to the upper surface of the housing lid part 31.

In this embodiment, the plate-shaped parts 33b, 33c, and 33d are connected to the leg body 33a and the housing lid 31, and are not connected to anything else. In other words, when viewed from the side in the direction along the plate-shaped parts 33b, 33c, and 33d, first gaps CH1 and CH2 (see FIG. 6) are formed between the leg body 33a and the upper surface of the housing lid 31, and the length H1 of the first gaps CH1 and CH2 in the direction of the rotation axis X is equal to the distance between the leg body 33a and the housing lid 31. In addition, the leg body 33a is disposed radially outward from the outer peripheral surface of the housing lid 31, and second gaps CV1 and CV2 (see FIG. 4) are formed between the leg body 33a and the outer peripheral surface of the housing lid 31, which are held by the plate-shaped parts. This configuration can further reduce the rigidity of the first leg 33.

The second leg 34 also has a disk-shaped leg body 34a and three plate-shaped parts 34b, 34c, and 34d that extend in parallel from the leg body 34a toward the housing lid 31. The plate-shaped parts 34b, 34c, and 34d have a generally trapezoidal shape that widens toward the lower end, but the length of the plate-shaped part 34d is the longest and the length of the plate-shaped part 34b is the shortest. A hole 34e is formed in the center of the leg body 34a for inserting a fastening bolt (not shown).

The side edges near the upper ends of the plate-shaped parts 34b, 34c, and 34d are connected to the outer periphery of the leg body 34a, and the lower ends of the plate-shaped parts 34b, 34c, and 34d are connected across the upper surface of the housing lid part 31 and the upper part of the side surface adjacent to the upper surface (the tapered part 31b having an arc-shaped cross section). As described above, by integrating the plate-shaped parts 34b, 34c, and 34d with the housing lid part 31 by wrapping the lower ends of the plate-shaped parts 34b, 34c, and 34d around the side surface from the upper surface of the housing lid part 31, it becomes easier to remove the molded product when forming the housing lid part 31 by injection molding or the like, and manufacturing costs can be reduced. However, the lower ends of the plate-shaped parts 34b, 34c, and 34d may be connected only to the upper surface of the housing lid part 31.

In this embodiment, the plate-shaped parts 34b, 34c, and 34d are also connected to the leg body 34a and the housing lid 31, and are not connected to anything else. In other words, when viewed from the side through the plate-shaped parts 34b, 34c, and 34d, first gaps CH1 and CH2 (see FIG. 6) are formed between the leg body 34a and the upper surface of the housing lid 31, and the length of the first gaps CH1 and CH2 in the direction of the rotation axis X is equal to the distance between the leg body 34a and the housing lid 31. In addition, the leg body 34a is disposed radially outward from the outer peripheral surface of the housing lid 31, and second gaps CV1 and CV2 (see FIG. 4) are formed between the leg body 34a and the outer peripheral surface of the housing lid 31, which are held by the plate-shaped parts. With this configuration, the rigidity of the second leg 34 can be further reduced. The thickness of the plate-like portions 34b, 34c, and 34d is preferably equal to the thickness of the plate-like portions 33b, 33c, and 33d. In addition, the height from the housing lid 31 to the upper surface of the leg body 34a is equal to the height from the housing lid 31 to the leg body 33a.

In Fig. 4, the plate-shaped portion 33b of the first leg 33 faces the plate-shaped portion 34d of the second leg 34, i.e., both surfaces of the plate-shaped portion 33b and the plate-shaped portion 34d are in approximately the same plane (preferably parallel to the rotation axis X). The plate-shaped portion 33c of the first leg 33 faces the plate-shaped portion 34c of the second leg 34, i.e., both surfaces of the plate-shaped portion 33c and the plate-shaped portion 34c are in approximately the same plane (preferably parallel to the rotation axis X). The plate-shaped portion 33d of the first leg 33 faces the plate-shaped portion 34b of the second leg 34, i.e., both surfaces of the plate-shaped portion 33d and the plate-shaped portion 34b are in approximately the same plane (preferably parallel to the rotation axis X).

4, when viewed in the direction of the rotation axis X, the center lines L0 of the plate-shaped portions 33c and 34c overlap each other, do not intersect with the rotation axis X, and pass through the center O1 of the hole 33e and the center O2 of the hole 34e. If the angle between the line segment L1 connecting the center O1 of the hole 33e and the rotation axis X and the center line L0 is θ1, and the angle between the line segment L2 connecting the center O2 of the hole 34e and the rotation axis X and the center line L0 is θ2, it is preferable that the angles θ1 and θ2 are 0 degrees or greater than 0 degrees and less than or equal to 40 degrees. By changing the angles θ1 and θ2, the rigidity of the legs 33 and 34 along the circumferential direction can be adjusted.

The third leg 35 also has a disk-shaped leg body 35a and three plate-shaped parts 35b, 35c, and 35d extending in parallel from the leg body 35a toward the housing lid 31. The plate-shaped parts 35b, 35c, and 35d have a common approximately trapezoidal shape that becomes wider toward the lower end, and each has approximately the same length.

A hole 35e is formed in the center of the leg body 35a for inserting a fastening bolt (not shown). When viewed in the direction of the rotation axis X, the center line L3 of the plate-shaped portion 35c passes through the center O3 of the hole 35e and the rotation axis X.

The side edges near the upper ends of the plate-shaped parts 35b, 35c, and 35d are connected to the outer periphery of the leg body 35a, and the lower ends of the plate-shaped parts 35b, 35c, and 35d are connected across the upper surface of the housing lid part 31 and the upper part of the side surface adjacent to the upper surface (the tapered part 31b having an arc-shaped cross section). As described above, by integrating the plate-shaped parts 35b, 35c, and 35d with the housing lid part 31 by wrapping the lower ends of the plate-shaped parts 35b, 35c, and 35d around the side surface from the upper surface of the housing lid part 31, it becomes easier to remove the molded product when forming the housing lid part 31 by injection molding or the like, and manufacturing costs can be reduced. However, the lower ends of the plate-shaped parts 35b, 35c, and 35d may be connected only to the upper surface of the housing lid part 31.

In this embodiment, the plate-shaped parts 35b, 35c, and 35d are connected to the leg body 35a and the housing lid 31, and are not connected to anything else. In other words, when viewed from the side through the plate-shaped parts 35b, 35c, and 35d, a first gap (not shown) is formed between the leg body 35a and the upper surface of the housing lid 31, and the length of the gap in the direction of the rotation axis X is equal to the distance between the leg body 35a and the housing lid 31. In addition, the leg body 35a is disposed radially outward from the outer peripheral surface of the housing lid 31, and second gaps CV1 and CV2 (see FIG. 4) are formed between the leg body 35a and the outer peripheral surface of the housing lid 31, which are held by the plate-shaped parts. With this configuration, the rigidity of the leg 35 can be further reduced. The thicknesses of the plate-shaped portions 35b, 35c, and 35d are preferably equal to the thicknesses of the plate-shaped portions 34b, 34c, and 34d. The thicknesses of the leg bodies 33a, 34a, and 35a are also preferably equal to each other. In addition, the height from the housing lid 31 to the upper surface of the leg body 35a is equal to the height from the housing lid 31 to the leg body 34a.

As shown in FIG. 4, when viewed in the direction of the rotation axis X, the center line L3 of the plate-shaped portion 35c intersects with the rotation axis X, but the plate-shaped portions 35b, 35c, and 35d may be angled so that the center line L3 does not intersect with the rotation axis X.

The drainage pump 1 is attached, for example, to the top plate (mounting part) CP of the cooling unit, as shown in Figure 3, by bolts (not shown) inserted through holes 33e, 34e, and 35e in the legs 33, 34, and 35.

(Drainage pump operation)
When power is supplied to the motor of the drive unit 3 from an external power source via the connector 32, the rotating blades in the housing 2 are rotated, and drain water is sucked up from the inlet cylindrical portion 22b into the pump chamber by centrifugal force and discharged from the outlet cylindrical portion 22c, and then drained outside the room via piping not shown.

Comparative Example
Next, a comparative example to be compared with the drainage pump 1 of this embodiment will be described. Fig. 7 is a perspective view similar to Fig. 1 of a drainage pump 1' according to the comparative example. The drainage pump 1' shown in Fig. 7 differs from the drainage pump 1 of this embodiment in the configuration of a drive unit 3'. Configurations common to the drainage pump 1 are given the same reference numerals and duplicated explanations will be omitted.

Specifically, the housing lid 31' of the drive unit 3' also has three legs 33', 34', and 35' connected together so as to protrude upward. The first leg 33' is connected to a leg body 33a' with a hole 33e', two plate-shaped parts 33b' and 33d' extending in parallel from the leg body 33a' toward the housing lid 31', and a side wall 33f' connecting the side edges of the plate-shaped parts 33b' and 33d' farther from the rotation axis X over the entire direction of the rotation axis X. The leg body 33a' is connected to the entire upper ends of the plate-shaped parts 33b' and 33d' and the entire upper end of the side wall 33f'.

The second leg 34' also comprises a leg body 34a' with a hole 34e', two plate-shaped parts 34b', 34d' extending in parallel from the leg body 34a' toward the housing lid 31', and a side wall 34f' connecting the side edges of the plate-shaped parts 34b', 34d' farther from the rotation axis X over the entire direction of the rotation axis X. The leg body 34a' is connected over the entire upper ends of the plate-shaped parts 34b', 34d' and the entire upper end of the side wall 34f'.

Furthermore, the third leg 35' also comprises a leg body 35a' with a hole 35e', two plate-shaped parts 35b', 35d' extending in parallel from the leg body 35a' toward the housing lid 31', and a side wall 35f' connecting the side edges of the plate-shaped parts 35b', 35d' farther from the rotation axis X over the entire direction of the rotation axis X. The leg body 35a' is connected over the entire upper ends of the plate-shaped parts 35b', 35d' and the entire upper end of the side wall 35f'.

That is, when the legs 33', 34', 35' are viewed from the side through the plate-shaped portions, there is no gap between the leg body 33a', 34a', 35a' and the housing lid 31', and the gap is shielded by the side walls 33f', 34f', 35f'. Also, when viewed in a plane in the direction of the rotation axis X, the leg body 33a', 34a', 35a' and the housing lid 31' overlap, and there is no gap between the plate-shaped portions. Therefore, the legs 33', 34', 35' are roughly speaking hollow box structures with an opening. In other words, when the legs 33', 34', 35' are cut at any point along the rotation axis X, the cross section is H-shaped or C-shaped. Due to this structure, the legs 33', 34', 35' have high rigidity in the rotation direction (circumferential direction) of the motor.

The rest of the configuration of the drainage pump 1' is the same as in the embodiment described above. The position of the engagement claw 31a' of the drive unit 3' is different from that of the embodiment described above, but there is almost no difference in the position of the engagement claw with respect to vibration transmission.

Figure 8 is an enlarged view of the second leg 34 of this embodiment viewed in a plane along the direction of the rotation axis X, and Figure 9 is an enlarged view of the second leg 34A of the comparative example viewed in a plane along the direction of the rotation axis X.

When the motor is driven to rotate the impeller, vibrations occur in the drainage pump. These vibrations are mainly circumferential vibrations caused by pressure fluctuations in the pump chamber before and after the tip of the impeller passes near the outlet cylindrical portion 22c.

In the comparative example shown in Figure 9, when circumferential vibration is applied, the plate-shaped parts 34b', 34d' are reinforced by the presence of the side wall 34f' extending in the circumferential direction, and the leg part 34' has high rigidity in the circumferential direction and is not easily deformed, so the vibration from the housing lid part 31' is transmitted to the top plate CP (Figure 2) through the leg part 34' with almost no attenuation. The same is true for the legs 33', 35'. Therefore, if the transmitted vibration coincides with the natural frequency of the top plate CP, resonance occurs and may be recognized as noise.

In contrast, according to the present embodiment, first gaps CH1 and CH2 are formed between the leg body 33a and the housing lid 31, and are sandwiched by the plate-like portions. In other words, the leg body 34a and the housing lid 31 are connected to both ends of the three plate-like portions 34b, 34c, and 34d. Therefore, when circumferential vibration is applied, the central portions of the plate-like portions 34b, 34c, and 34d are deformed so as to bend in the plate thickness direction, consuming energy at that time and suppressing the transmission of vibration from the housing lid 31 to the top plate CP. The same is true for the legs 33 and 35. Therefore, it is possible to provide a drainage pump 1 that can suppress the transmission of vibration without increasing the number of parts and is easy to install.

Figure 10 is a graph comparing noise levels between this embodiment and the comparative example, with the noise level on the vertical axis and the voltage applied to the motor on the horizontal axis. The graph in Figure 10 shows that at a normal operating voltage of around 13 V, the drainage pump 1 of this embodiment has a noise reduction effect of approximately 7 dB (A) compared to the drainage pump 1' of the comparative example.

According to the results of the research conducted by the inventors of the present application, it was found that even when the plate-shaped portions 33c, 34c of the legs 33, 34 are arranged so that their center lines L1, L2 intersect with the rotation axis X, a reduction effect similar to that of the above embodiment can be achieved.

Second Embodiment
11 is a perspective view of a drive unit 3A according to the second embodiment. The drive unit 3A can be assembled to the housing 2 in the same manner as in the above-described embodiment, and redundant explanations will be omitted for components other than the drive unit 3A.

In this embodiment, the second leg 34A connected to the housing lid 31A includes a disk-shaped leg body 34Aa with a hole 34Ae, three plate-shaped parts 34Ab, 34Ac, and 34Ad extending in parallel at equal intervals from the leg body 34Aa toward the housing lid 31A, a lower wall part (also simply called a wall part or a connecting part) 34Ag extending from one side of the plate-shaped parts 34Ab and 34Ac to the other and connecting the vicinity of their lower ends, and a lower wall part (also simply called a wall part or a connecting part) 34Ah extending from one side of the plate-shaped parts 34Ac and 34Ad to the other and connecting the vicinity of their lower ends. The lower wall parts 34Ag and 34Ah are formed to extend from the housing lid 31A toward the leg body 34Aa side, but terminate before reaching the leg body 34Aa. Therefore, first gaps CH1, CH2 are formed between the upper ends of the lower wall portions 34Ag, 34Ah and the leg body 34Aa.

It is preferable that the surface of the lower wall portions 34Ag, 34Ah farther from the rotation axis X is included in a cylindrical surface common to the side surface of the housing lid portion 31A. The upper end positions of the lower wall portions 34Ag, 34Ah are approximately equal, and the gap between the height H2 from the housing lid portion 31A to the upper end of the lower wall portions 34Ag, 34Ah and the height H1 from the upper surface of the housing lid portion 31A to the lower surface of the leg body 34Aa should be greater than 0, and generally, the larger the gap, the more the noise reduction effect can be expected.

Therefore, in the second embodiment as well, when viewed from the side through the plate-like portions 34Ab, 34Ac , and 34Ad, gaps CH1 and CH2 are formed between the leg body 34Aa and the lower wall portions 34Ag and 34Ah, which are sandwiched by the plate-like portions. The rest of the configuration of the leg 34A is the same as in the above-mentioned embodiment, and the first leg 33A and the third leg 35A are also similar, so repeated explanations will be omitted.

According to this embodiment, by changing the height of the lower wall portions 34Ag and 34Ah, the rigidity of the legs 33A, 34A, and 35A can be changed, and the vibration transmission characteristics can be changed. Therefore, by adjusting the height of the lower wall portions 34Ag and 34Ah according to the specifications of the top plate CP of the cooling unit, a drainage pump in which resonance of the top plate CP is less likely to occur can be realized.

For example, if resonance occurs during use of the drainage pump, an effective countermeasure against the resonance can be implemented by replacing the drive unit 3A with one that has lower wall portions 34Ag and 34Ah of different heights. In such a case, only the drive unit 3A needs to be replaced, and the housing 2 that has been used up until now can be used, significantly reducing the cost of replacement.

(Various modified examples)
12 is a view showing one of the legs of the drive unit in the modified example of the second embodiment as viewed from the outside along the radial direction. Since the configuration other than the legs is the same as the above-mentioned embodiment, a duplicated description will be omitted.

(Variation 1)
12(a), the second leg 34B connected to the housing lid 31B (only a portion of which is shown) includes a disk-shaped leg main body 34Ba, three plate-like portions 34Bb, 34Bc, and 34Bd extending in parallel at equal intervals from the leg main body 34Ba toward the housing lid 31B, a lower wall portion (also simply referred to as a wall portion or a connecting portion) 34Bg extending from one of the plate-like portions 34Bb and 34Bc toward the other and connecting portions thereof, and a lower wall portion (also simply referred to as a wall portion or a connecting portion) 34Bh extending from one of the plate-like portions 34Bc and 34Bd toward the other and connecting portions thereof. It is preferable that the other legs have a common configuration.

The lower wall portions 34Bg, 34Bh extend further from the housing lid portion 31B toward the leg body 34Ba than in the second embodiment, but terminate before reaching the leg body 34Ba. Therefore, first gaps CH1, CH2 are formed between the upper ends of the lower wall portions 34Bg, 34Bh and the leg body 34Ba. Here, if the distance from the housing lid portion 31B to the underside of the leg body 34Ba is H1 and the distance from the housing lid portion 31B to the upper ends of the lower wall portions 34Bg, 34Bh is H2, then H1-H2>0 holds.

In variant example 1 (and the second embodiment), the lower wall portions 34Bg and 34Bh have a common rectangular plate shape, and the distance H2 from the housing lid portion 31B to the upper ends of the lower wall portions 34Bg and 34Bh are also equal to each other.

(Variation 2)
12B, the second leg 34C connected to the housing lid 31C (only a portion of which is shown) includes a disk-shaped leg main body 34Ca, three plate-like portions 34Cb, 34Cc, and 34Cd extending in parallel at equal intervals from the leg main body 34Ca toward the housing lid 31C, a lower wall portion (also simply referred to as a wall portion or a connecting portion) 34Cg extending from one of the plate-like portions 34Cb and 34Cc to the other and connecting portions thereof, and a lower wall portion (also simply referred to as a wall portion or a connecting portion) 34Ch extending from one of the plate-like portions 34Cc and 34Cd to the other and connecting portions thereof. It is preferable that the other legs have a common configuration.

The lower wall portions 34Cg and 34Ch also extend from the housing lid portion 31C toward the leg body 34Ca and terminate before reaching the leg body 34Ca, but each has a V-shaped notch extending downward in the center of the upper end. Therefore, the first gaps CH1 and CH2 have a tapered shape toward the bottom. Here, if the distance from the housing lid portion 31C to the bottom surface of the leg body 34Ca is H1 and the distance from the housing lid portion 31C to the upper end of the lower wall portions 34Cg and 34Ch (which has the maximum height among the lower wall portions 34Cg and 34Ch that are in contact with the plate-shaped portions 34Cb, 34Cc, and 34Cd) is H2, then H1-H2>0 holds.

(Variation 3)
12(c), a second leg 34D connected to a housing lid 31D (only a portion of which is shown) includes a disk-shaped leg main body 34Da, three plate-like portions 34Db, 34Dc, and 34Dd extending in parallel at equal intervals from the leg main body 34Da toward the housing lid 31D, a lower wall portion (also simply referred to as a wall portion or a connecting portion) 34Dg extending from one of the plate-like portions 34Db and 34Dc toward the other and connecting portions thereof, and a lower wall portion (also simply referred to as a wall portion or a connecting portion) 34Dh extending from one of the plate-like portions 34Dc and 34Dd toward the other and connecting portions thereof. It is preferable that the other legs have a common configuration.

The lower wall portions 34Dg, 34Dh extend from the housing lid portion 31D toward the leg body 34Da and terminate before reaching the leg body 34Da. First gaps CH1, CH2 are formed between the upper ends of the lower wall portions 34Dg, 34Dh and the leg body 34Da, but because the upper ends of the lower wall portions 34Dg, 34Dh are inclined relative to the upper surface of the housing lid portion 31D, the lower edges of the first gaps CH1, CH2 are correspondingly inclined. In addition, because the heights of the upper ends of the lower wall portions 34Dg, 34Dh are different, the sizes of the first gaps CH1, CH2 are also different. Here, if the distance from the housing lid portion 31D to the underside of the leg main body 34Da is H1, and the distance from the housing lid portion 31D to the upper end of the lower wall portion 34Dh (here, the upper end of the lower wall portion 34Dh that is farthest from the housing lid portion 31D among the parts of the lower wall portion that contact the plate-shaped portion) is H2, then H1-H2>0 holds.

In this way, by changing the size of the first gaps CH1 and CH2, it is possible to change the length (the length of the part that becomes the vibrating body) of the three plate-shaped portions 34Db, 34Dc, and 34Dd that is not constrained by the lower wall portions 34Dg and 34Dh, and it is also possible to give the plate-shaped portions different natural frequencies.

As shown in the above modified examples, the lower wall portion formed between the three plate-shaped portions may have various shapes (which may be common to all of the plate-shaped portions or may be different shapes), but it is important that H1-H2>0 is satisfied in any shape.

(Variation 4)
In the modified example 1-3 shown in Fig. 12(a) to (c), the lower wall portion has been described as an example of a connecting portion that connects adjacent plate-shaped portions to each other. However, in addition to the above, as in the modified example shown in Fig. 14, for example, a beam (also called a connecting portion) 34Eg may be provided in the leg 34E, which extends from one of the adjacent plate-shaped portions 34Eb, 34Ec to the other and connects parts of them, and a beam (also called a connecting portion) 34Eh may be provided, which extends from one of the adjacent plate-shaped portions 34Ec, 34Ed to the other and connects parts of them. In such a case, gaps CH3, CH4 of a distance H3 in the direction of the rotation axis X are also generated between the beams 34Eg, 34Eh and the housing lid 31E. The widths of the beams 34Eg, 34Eh in the direction of the rotation axis X are H2 and are equal to each other, but the widths of the two may be different. In this case, it is preferable that H1-(H2+H3)>0. Furthermore, it is preferable that the thickness of the lower wall or beam is uniform. It is also preferable that the two legs (not shown in FIG. 14) other than the leg 34E have the same structure.

In addition, in the modified example shown in Figs. 12(a)-(c) and 14, an example in which the first gap is formed between the leg body and the connecting part has been described, but the present invention is not limited thereto. For example, the leg body and the connecting part may be integrally formed, and the first gap may be formed between the connecting part and the housing lid (case). In other words, the connecting part may be formed as an upper wall part extending from the leg body toward the housing lid. In such a case, referring to Fig. 14, (H1-(H2+H3)=0 and H3>0), the upper wall part is formed to extend from the leg body 34Ea toward the housing lid 31E side, but terminates before reaching the housing lid 31E. In this case, the gap formed between the lower end of the upper wall part and the housing lid 31E is defined as the first gap CH3, CH4.

Figure 13 is a diagram showing the relationship between the overall noise value (OA value) and the size of the first gap (H1-H2) when a drainage pump to which variant 1 is applied is in operation, and shows a graph when H1 = 12 mm. The graph in Figure 13 shows that, compared to when value (H1-H2) = 0 mm (comparison example in Figure 7), noise is reduced when value (H1-H2) > 0 mm.

There is also a tendency for noise to decrease as the value (H1-H2) increases, but this is not necessarily a linear relationship. In other words, in the graph of Figure 13, as the value (H1-H2) is increased from 0 mm, the noise decreases sharply, but when the value (H1-H2) reaches 2 mm, this is the boundary (inflection point) at which the noise increases again, and when the value (H1-H2) reaches 4 mm, the noise peaks and then decreases again.

From the viewpoint of reducing noise, it is desirable to make the value (H1-H2) as large as possible, but from the viewpoint of suppressing internal stress in the legs, it is desirable to make the value (H1-H2) as small as possible. In such a case, it can be seen from the graph in Figure 13 that by setting the value (H1-H2) to, for example, 1 mm or more and 3 mm or less, it is possible to achieve both noise reduction and suppression of internal stress.

Although the present invention has been described above with reference to an embodiment of a drainage pump, the present invention is not limited to the above-mentioned embodiment. For example, the housing lid having three plate-shaped parts has been described, but the plate-shaped parts may be two or four or more. In addition, the multiple legs may extend from the housing toward the mounting part. Furthermore, the number, shape, and orientation of the plate-shaped parts of each leg relative to the rotation axis X may be set to be different, so that the legs have different characteristics such as natural frequency and rigidity.

REFERENCE SIGNS LIST 1 Drainage pump 2 Housing 3, 3A Drive unit 31, 31A Housing cover 33 , 34, 35, 34A, 35A, 34B, 34C, 34D, 34E Legs

Claims (10)

A drainage pump having a case that houses a rotor and a motor that drives the rotor,
The case has a plurality of legs protruding along a rotation axis direction of the rotor blades,
The leg portion includes a leg body fixed to a mounting portion and a plurality of plate-shaped portions connecting the leg body and the case,
When viewed through the plate-shaped portions, a first gap is formed between the case and the leg body.
A drainage pump characterized by: The leg body is disposed radially outward from the outer circumferential surface of the case, and a second gap sandwiched by the plate-shaped portion is formed between the outer circumferential surface of the case and the leg body.
2. The drainage pump according to claim 1. When the legs are viewed from the direction of the rotation axis, the center lines of the plate-shaped portions of the two legs do not intersect with the rotation axis.
2. The drainage pump according to claim 1. When the legs are viewed from the rotation axis direction, center lines of the plate-shaped portions of the two legs are substantially aligned.
4. The drainage pump according to claim 3. When the leg portion is viewed from the direction of the rotation axis, a center line of the plate-shaped portion of the leg portion intersects with the rotation axis.
2. The drainage pump according to claim 1. The leg portion has a connecting portion between the plurality of plate-shaped portions, the connecting portion connecting adjacent plate-shaped portions to each other.
2. The drainage pump according to claim 1. The connecting portion is a wall portion extending from the case side toward the leg main body.
7. The drainage pump according to claim 6. The case has a housing lid portion that houses the motor, and a housing that accommodates the rotor blades and is detachable from the housing lid portion, and the leg portion is connected to the housing lid portion.
The drainage pump according to any one of claims 1 to 7. In each of the plurality of legs, the plurality of plate-shaped portions are aligned in a rotation direction of the motor, and two plate-shaped portions aligned in the rotation direction of the motor have main surfaces facing each other.
2. The drainage pump according to claim 1. In each of the plurality of legs, the plurality of plate-shaped portions are parallel to each other.
The drainage pump according to claim 9 .

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