Patent Description:
Hereinafter, a structure of a conventional laundry apparatus and disadvantages thereof will be described referring to <FIG>.

Such a conventional laundry apparatus includes a tub T provided to hold water; and a bearing housing BH coupled to a rear surface of the tub T and configured to be rotatably penetrated by a drum shaft. The bearing housing BH may be insertedly molded in the rear surface of the tub T.

The insert molding may reinforce durability and prevent a problem in that the bearing housing BH is deformed by the tension caused by the rotation of the drum shaft or separated from the tub T. Also, the insert molding may enhance space efficiency inside the cabinet.

However, the conventional laundry apparatus includes a plurality of recessions formed in the bearing housing BH to reinforce the sealing between the bearing housing BH and the tub T. The plurality of the recessions R may be configured of a concave area (B) and a convex area (C). The conventional laundry apparatus further include a plurality of uneven areas (B) formed in an inner surface of the tub T that faces the plurality of the recessions R formed in the bearing housing BH to secure the strength of the tub T against the high speed spinning.

As including the recessions R and the uneven areas B, the conventional laundry apparatus has following disadvantages.

First of all, water and vapors frequently contacts with an inner wall of the tub T and such the structure of the uneven areas B might cause the water and vapors consistent remaining on the inner wall, not discharged outside. Because of that, much mold or foreign substances might gather on the surface and a serious sanitation problem might occur (e.g., bad smell and propagation of germs, etc.).

Furthermore, air inside the tub T may flow together with water during the rotation of the drum. At this time, the uneven areas (B) might cause aerodynamic noise.

Still further, the conventional bearing housing BH) has a weak rigidity and subject to a torque generated by the rotation of the shaft disadvantageously.

Still further, the plurality of the recessions R formed in the bearing housing BH might enlarge the width of the bearing housing BH enough to deteriorate use of a space di sadvantageously.

<CIT> relates to a structure of a driving part provided to a washing machine. The washing machine comprising a tub configured to store wash water therein; a drum rotatably installed in the tub and accommodating laundry therein; a driving shaft connected to the drum; at least one bearing configured to support the driving shaft; a motor mounted to an outer surface of a rear wall of the tub and connected to the driving shaft; and a bearing housing comprising a hub configured to accommodate the at least one bearing and a flange provided around the hub and coupled to a stator of the motor, the bearing housing buried in the rear wall of the tub.

<CIT> relates to a washing machine having a tub that stores washing water. A drum is pivotally installed in the tub. A operating shaft is connected to the drum. At least on bearings supports the driving shaft. A motor is installed in an exterior of a rear wall of the tub. The motor is connected to the operating shaft. The bearing housing includes a herb and a flange. The hub accepts the bearing. The flange is combined with a stator(<NUM>) of the motor.

<CIT> relates to a bearing housing and a washing machine including the same. The bearing includes a bearing support supporting a bearing, a rib formed integrally with the bearing support and including a penetration part, and a flange part extending radially from the rib.

To overcome the disadvantages, an object of the present invention is to address the above-noted and other problems and to provide a laundry apparatus which may enhance sanitation by providing a smooth rear inner surface with a tub.

Another object of the present invention is to provide a laundry apparatus which may reduce the noise generated by a shape of a rear inner surface formed in the tub, while a drum is rotated.

A further object of the present invention is to provide a laundry apparatus which may enhance the strength of a bearing housing insertedly molded in the rear wall of the tub.

A still further object of the present invention is to provide a laundry apparatus which may improve use of a space inside the tub by improving a shape of a bearing housing.

The invention is specified by the independent claim.

To achieve these objects and other advantages and in accordance with the purpose of the embodiments, as embodied and broadly described herein, a laundry apparatus comprises a cabinet; a tub provided in the cabinet and configured to hold water; a drum rotatably mounted in the tub and configured to accommodate laundry; a drive unit comprising a stator configured to form an electromagnetic field and a rotor rotatable by the electromagnetic field of the stator; a shaft fixed to the drum and connected to the drive unit via a rear wall of the tub; a bearing rotatably supporting the shaft; and a bearing housing insert-molded in the tub <NUM> and configured to fix the bearing, wherein the bearing housing comprises a housing body formed in a cylinder shape and comprising a shaft insertion hole configured to fix the bearing; a first flange formed in a ring shape arranged in an outer area with respect to a radial direction of the housing body; a plurality of first connection ribs provided to connect an outer circumferential surface of the housing body to the first flange; and a first insertion hole provided between two of the first connection ribs.

A longitudinal axis of each first connection rib is provided on a perpendicular line of the housing body.

The laundry apparatus may further comprise a stator securing portion provided between the first connection ribs, wherein the first insertion hole and the stator securing portion may be alternately provided along a circumference of the housing body.

The bearing housing comprises a second flange formed in a ring shape and arranged in an outer area with respect to a radial direction of the first flange; a plurality of second connection ribs provided to connect an outer circumferential surface of the first flange to the second flange; and a plurality of second insertion holes provided between the second connection ribs, and a longitudinal axis of each second connection rib is provided on a perpendicular line of the housing body.

The first connection ribs and the second connection ribs are provided on the same line out of perpendicular lines of the housing body.

The back-and-forth width of the first connection rib becomes narrower as extended from the housing body towards the first flange, and the back-and-forth width of the second connection rib becomes narrower as extended from the first flange towards the second flange, and the back-and-forth width of the first connection rib is larger than that of the second connection rib.

A line from some area of the first flange forming one of the second insertion holes and a radial-direction center of the housing body may form a sector.

A diameter of the bearing housing may be <NUM>-<NUM>% of a diameter of the tub rear wall.

The first flange and the second flange may be located behind a front end of the housing body.

The second connection rib may be longer than the first connection rib.

The second connection rib may be equal to or shorter than the first connection rib.

The bearing housing may comprise a third flange formed in ring shape and arranged in an outer area with respect to a radial direction of the second flange; a plurality of third connection ribs provided to connect an outer circumferential surface of the second flange to the third flange; and a plurality of third insertion holes provided between the second connection ribs, and a longitudinal axis of each third connection rib may be provided on a perpendicular line of the housing body.

A stator coupling portion may be provided in the tub rear wall and configured to couple the stator thereto, and the rotor may comprise a rotor housing fixed to the shaft; and a permanent magnet fixed to the rotor housing and provided in an outer area with respect to a radial direction of the stator.

According to embodiments of the present invention, the laundry treating apparatus has following effects.

First, the laundry apparatus is capable of enhancing sanitation by forming a smooth and flat rear wall of a tub.

Furthermore, the laundry apparatus has less noise during the rotation of the drum.

Still further, the laundry apparatus is capable of guaranteeing the durability of the bearing housing.

Still further, the laundry apparatus has a better use of a space.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by illustration only, since various changes and modifications within the scope of the claims will become apparent to those skilled in the art from this detailed description.

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings, which are given by illustration only, and thus are not limitative of the present invention, and wherein:.

Referring to the accompanying drawings, exemplary embodiments of the present disclosure will be described in detail. Regardless of numeral references, the same or equivalent components may be provided with the same reference numbers and description thereof will not be repeated.

For the sake of brief description with reference to the drawings, the sizes and profiles of the elements illustrated in the accompanying drawings may be exaggerated or reduced and it should be understood that the embodiments presented herein are not limited by the accompanying drawings.

The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings.

First of all, referring to <FIG> illustrating a side view of a laundry apparatus according to the present invention, an entire configuration of the laundry apparatus will be described.

The laundry apparatus includes a cabinet <NUM> defining an exterior design; a tub provided in the cabinet and a drum <NUM> rotatably mounted in the tub <NUM> and configured to accommodate laundry.

The cabinet <NUM> may have an opening formed in a front side of the cabinet to introduce the laundry and a door <NUM> may be rotatably coupled to the cabinet to open and close the opening.

The door <NUM> may be configured of a circular door frame <NUM>; and a transparent window <NUM> provided in a center of the door frame.

Here, as defining directions to make the specific structure of the laundry apparatus, which will be described as follows, easily understood, a direction towards the door <NUM> with respect to the center of the cabinet <NUM> may be defined as a front side.

A reversed direction of the direction towards the door <NUM> may be defined as a rear side. A right side and a left side may be naturally defined by the front and rear sides.

The tub <NUM> may include a tub body <NUM> provided as a cylinder shape with a longitudinal axis disposed in parallel or keeping <NUM>~<NUM> degrees with a bottom surface of the cabinet; a tub front wall <NUM> provided in a front side of the tub body <NUM> and configured to communicate with the opening; and a tub rear wall <NUM> provided in a back side of the tub body <NUM>.

The tub <NUM> may be fixed to the bottom surface of the cabinet <NUM> by a lower supporter <NUM> having a support bar 91a and a damper 91b connected to the support bar 91a. Accordingly, the lower supporter <NUM> may damp the vibration generated in the tub <NUM> by the rotation of the drum <NUM>.

In addition, an elastic supporter <NUM> provided in a top surface of the cabinet <NUM> may be connected to a top surface of the tub <NUM>. Accordingly, the elastic supporter <NUM> may damp the vibration generated in the tub <NUM> and transferred to the cabinet <NUM>.

The drum <NUM> may be provided in a cylinder shape having a longitudinal axis arranged in parallel or keeping <NUM>~<NUM> degrees with the bottom surface of the cabinet so as to accommodate the laundry. The drum may include a drum opening <NUM> formed in a front side to communicate with the tub opening <NUM>.

Accordingly, a user may load laundry into the drum <NUM> through the opening, the tub opening <NUM> and the drum opening 31or unload the laundry from the inside of the drum <NUM>.

Also, the drum <NUM> may further include a lifter <NUM> provided in an inner circumferential surface of the drum <NUM> to agitate the laundry when the drum is rotated; and a plurality of through-holes <NUM> penetrating an outer circumferential surface of the drum <NUM>.

The laundry apparatus according to one embodiment may further include a water supply hose <NUM> configured to be supplied water from an external water supply source; a detergent box <NUM> fixed to the cabinet <NUM>, in communication with the water supply hose <NUM> and configured to supply a washing detergent to the tub <NUM>; and a detergent box drawer <NUM> detachable from the detergent box <NUM> to be retractable from the front side of the cabinet <NUM>.

The laundry apparatus may further include a water supply hose <NUM> that is extendible while facilitating communication between the detergent box <NUM> and the tub <NUM>. The washing detergent supplied to the detergent box <NUM> may be mixed with the water supplied along the water supply hose <NUM> and then discharged into the tub <NUM> along the water supply pipe <NUM>.

A gasket <NUM> may be provided between the opening of the cabinet 1and the tub opening <NUM>. The gasket <NUM> may be configured to prevent leakage of water into the cabinet <NUM> from the tub <NUM> and the vibration of the tub <NUM> from being transferred to the cabinet <NUM>.

Specifically, the gasket <NUM> may include a cabinet fixing portion <NUM> connected to an area where the opening of the cabinet <NUM> is formed; a tub fixing portion <NUM> connected to an area where the tub opening <NUM> is formed; and a circular gasket body <NUM> provided to connect the cabinet fixing portion <NUM> and the tub fixing portion <NUM> with each other.

The gasket <NUM> may be made of a flexible material (e.g., rubber) so as to damp the vibration transferred to the cabinet <NUM> from the tub <NUM>. The vibration may be more effectively damped by a vibration isolating member <NUM> that is curved from a circumferential surface of the gasket body <NUM> along a perpendicular direction with respect to the circumferential surface.

A weight balancer <NUM> may be provided in a front surface of the tub <NUM> outside the gasket <NUM> and configured to damp the vibration generated in the drum.

For the water discharge, the laundry apparatus according to one embodiment may include a water discharge pipe <NUM> provided to form a water discharge path for the water held in the tub <NUM>; and a water discharge pump <NUM> having a water discharge motor and a water discharge impeller so as to generate a pressure different in the water discharge pipe <NUM> and discharge the water via the water discharge pipe <NUM>.

More specifically, the water discharge pipe <NUM> may include a first water discharge pipe <NUM> provided to connect the bottom surface of the tub <NUM> with the water discharge pump <NUM>; and a second water discharge pipe <NUM> having one end connected with the water discharge pump <NUM> and configured to form a path of the water flowing outside the cabinet <NUM>.

Meanwhile, the drum <NUM> is rotatable by a drive unit <NUM> provided behind the tub <NUM>. The drive unit <NUM> may include a stator <NUM> fixed to a rear surface of the tub <NUM>; and a rotor <NUM> rotatable by the electromagnetic action with the stator.

Examples of a method for the drive unit <NUM>'rotating the drum <NUM> may include a method using a belt in transferring a power to a shaft and another method using a rotor <NUM> directly connected to the shaft <NUM>. Hereinafter, the latter method will be adopted as one example.

The laundry apparatus according to one embodiment includes a shaft <NUM> penetrating the tub rear wall <NUM> and connecting the drum to the rotor <NUM>; and an arm <NUM> provided in a rear surface of the drum <NUM> and configured to transfer a rotational force of the shaft <NUM> to the drum <NUM>.

The arm <NUM> may be fixed to the drum <NUM> and extended in a radial direction with respect to a rotation center of the drum rear wall.

The stator <NUM> may be secured to a stator coupling portion <NUM> provided in the tub rear wall <NUM>. The rotor <NUM> may be configured of a permanent magnet <NUM> spaced a predetermined distance apart from stator in a perpendicular direction with respect to the shaft; and a rotor housing <NUM> provided to connect the permanent magnet <NUM> and the shaft <NUM> with each other.

The laundry apparatus further includes a bearing <NUM> provided to support the shaft <NUM>; and a bearing housing <NUM> insert-molded in the tub <NUM> and configured to secure the bearing <NUM> to the tub.

The bearing housing <NUM> may be provided between the shaft <NUM> and the bearing housing <NUM>. The bearing housing <NUM> may include a first bearing <NUM> fixed to a front area of the bearing housing <NUM>; and a second bearing <NUM> fixed to a rear area of the bearing housing <NUM>.

Hereinafter, referring to <FIG> and <FIG>, the bearing housing <NUM> according to one embodiment will be described in detail.

The bearing housing <NUM> includes a housing body <NUM> formed in a cylinder shape and having a shaft insertion hole 721a; a first flange <NUM> formed in a ring shape and provided in an outer area with respect to a radial direction of the housing body <NUM>, while being spaced a preset distance apart from the housing body <NUM>; and a first connection rib <NUM> provided to connect the housing body <NUM> to the first flange <NUM>.

A first bearing coupling portion 821b may be provided in a front area of the shaft insertion hole <NUM> to couple the first bearing <NUM> thereto and a second bearing coupling portion 821c provided in a rear area to couple the second bearing <NUM> thereto.

A plurality of first connection ribs <NUM> are provided and a longitudinal axis of each first connection rib <NUM> are provided along a perpendicular line with respect to a circumferential surface of the housing body <NUM>.

In other words, the first connection rib <NUM> is extended from a circumferential surface of the housing body <NUM> in a radial direction and connected to the first flange <NUM>.

Also, a plurality of first insertion holes <NUM> are formed between the first connection ribs <NUM> and a material forming the tub <NUM> (e.g., synthetic resin) may be filled in the first insertion holes <NUM> as the bearing housing <NUM> is inserted in the tub. Accordingly, the sealing between the bearing housing <NUM> and the tub rear wall <NUM> may be enhanced.

A stator securing portion <NUM> may be provided between the first connection ribs <NUM> so as to secure the stator <NUM> to the tub rear wall <NUM>.

The stator securing portion 825may be backwardly projected with respect to the first connection ribs <NUM>. For that, an inner surface of the stator securing portion <NUM> may be backwardly recessed.

The material forming the tub <NUM> (e.g., synthetic resin) may be filled in a space formed after the inner surface of the stator securing portion <NUM> is backwardly recessed.

A securing hole 825a may be formed in the stator securing portion <NUM> and a bolt may be secured to the stator securing portion <NUM> to fix the stator <NUM>. A securing portion inner insertion hole 825b may be provided in an inner area of the securing hole 825a and a securing portion outer insertion hole 825c may be provided in an outer area with respect to a radial direction of the housing body <NUM>.

The securing portion inner and outer insertion holes 825b and 825c may be also filled with the material forming the tub <NUM>. Accordingly, the sealing between the bearing housing <NUM> and the tub rear wall <NUM> may be improved and the consumption of the material forming the bearing housing <NUM> may be reduced.

The plurality of first insertion holes <NUM> and the stator securing portion <NUM> may be arranged along a circumference of the housing body <NUM>. At this time, both of them may be alternately provided. Any arrangements may be applicable only if the first insertion hole <NUM> and the stator securing portions <NUM> are arranged in opposite areas with respect to an axis perpendicular to the ground while passing the center of the bearing housing <NUM>, by the same number.

Moreover, the bearing housing <NUM> further includes a second flange <NUM> formed in a ring shape and arranged in an outer area with respect to a radial direction of the first flange <NUM>, while being spaced a preset distance apart from the first flange <NUM>; and a plurality of second connection ribs <NUM> provided to connect an outer circumferential surface of the first flange <NUM> to the second flange <NUM>.

Similarly, a plurality of second insertion holes <NUM> may be provided between the second connection ribs <NUM> and the material forming the tub <NUM> may be filled in the second insertion hole <NUM> as the bearing housing <NUM> is inserted in the tub <NUM>.

The second insertion hole <NUM> may be provided between each two of the second connection ribs <NUM>, different from the first insertion hole <NUM>.

A longitudinal axis of each second connection rib <NUM> is provided on a perpendicular line of the housing body. In other words, the second connection ribs <NUM> are extended from the first flange <NUM> in a radial direction and then connected to the second flange <NUM>.

At this time, the first connection ribs and the second connection ribs <NUM> are provided on the same line along the perpendicular line of the housing body.

Accordingly, a line connecting some point of an arc of the first flange forming one of the second insertion holes and a radial center of the housing body may form a fan shape.

In other words, the housing body <NUM> and the first connection ribs <NUM> and the first connection ribs <NUM> and the second flange <NUM> may be coupled to each other, respectively, to form a spoke shape.

As the bearing housing <NUM> including the plurality of the flanges and connection ribs is inserted in the tub rear wall <NUM>, the strength of the tub rear wall may be secured even without auxiliary uneven structure formed in the tub rear wall <NUM>.

The first flange <NUM> and the second flange <NUM> may be located behind a front end of the housing body <NUM>. The first connection ribs <NUM> may be located in a line connecting the front end of the housing body <NUM> and the first flange <NUM> at the shortest distance.

As stress distribution will be described hereinafter, the stress per unit volume, that is applied to the bearing housing <NUM> along the rotation of the shaft <NUM> is the largest near the housing body <NUM> and becomes smaller towards the outer area in a radial direction of the shaft <NUM>.

Accordingly, the back-and-forth width of the first connection rib becomes narrower as the first connection rib is extended from the housing body <NUM> towards the first flange <NUM>. The back-and-forth width of the second connection rib <NUM> becomes narrower as the second connection rib <NUM> is extended from the housing body <NUM> towards the second flange <NUM>. The width of the first connection rib <NUM> may be wider than that of the second connection rib <NUM>.

The area of the connection rib having a high stress per unit volume may be formed thick and the area having a low stress per unit volume may be formed thin, such that the material forming the bearing housing <NUM> can be reduced while the use of the space inside the tub and the space inside the tub <NUM> can be enhanced effectively.

Meanwhile, the length L of the second connection rib <NUM> may be larger than the length K of the first connection rib <NUM>. The sealing force between the bearing housing <NUM> and the tub <NUM> may be enhanced by enlarging a radius of the tub rear wall <NUM> occupied by the bearing housing <NUM>.

Hereinafter, referring to <FIG> and <FIG>, the structure of the bearing housing <NUM> inserted in the tub rear wall <NUM> will be described.

First of all, referring to <FIG> illustrating the inner surface of the tub rear wall <NUM>, some inner area of the tub rear wall <NUM> may have a smooth surface, except an area S corresponding to the stator securing portion.

In other words, compared with the related art mentioned above, it is shown that the projected area of the tub rear wall <NUM> is noticeably reduced.

Accordingly, the sanitation of the tub <NUM> may be improved and the aerodynamic noise caused by the rotation of the drum <NUM> may be reduced.

Meanwhile, referring to <FIG> illustrating the structure of the tub rear wall <NUM>, a diameter BD of the bearing housing <NUM> may be <NUM>-<NUM>% of a diameter TD of the tub rear wall <NUM>.

Compared with the conventional laundry apparatus, a rate of the diameter of the bearing housing to the diameter of the tub rear wall <NUM> may be relatively larger. While the material of the bearing housing <NUM> is saved, the durability against the rotation stress may be enhanced effectively.

The stator coupling portion <NUM> provided in the rear surface of the stator securing portion <NUM> may be projected from the tub rear wall <NUM> and a projection <NUM> may be formed to increase the strength of the tub <NUM>.

The projection <NUM> may include a first projection 242a projected from a rear surface of the second flange <NUM> in a circular shape; and a second projection radially projected from rear surfaces of the first and second connection ribs <NUM> and <NUM>.

Next, referring to <FIG>, another embodiment of the bearing housing <NUM> provided in the laundry apparatus according to the present invention will be described, focused on a different feature from the above-noted embodiment.

This embodiment of the bearing housing <NUM> may further include a third flange formed in an outer area with respect to a radial direction of the second flange in a ring shape, spaced apart a preset distance apart from the second flange <NUM>; and a plurality of third connection ribs provided to connect the second flange <NUM> with the third flange <NUM>.

A third insertion hole <NUM> may be provided between the third connection ribs <NUM> and a material forming the tub <NUM> may filled in the third insertion hole <NUM> as the bearing housing <NUM> is inserted in the tub <NUM>. A plurality of third insertion holes may be provided between two of the third connection ribs, respectively.

A longitudinal axis of each third connection rib <NUM> may be provided on a perpendicular line of the housing body. In other words, the third connection ribs <NUM> may be radially extended from the second flange <NUM> to be connected to the third flange <NUM>.

At this time, the first connection rib <NUM>, the second connection rib <NUM> and the third connection rib <NUM> may be provided on the same line along the perpendicular line of the housing body.

Accordingly, a line from some area of an arc of the third flange <NUM> forming one of the third insertion holes <NUM> to a center of a radial direction of the housing body <NUM> may form a sector.

In this instance, the length K of the first connection rib <NUM>, the length K of the second connection ribs <NUM> and the length Q of the third connection rib <NUM> may be the same.

This embodiment may be applied when the tub rear wall <NUM> of the embodiment shown in <FIG> is expanded.

<FIG> illustrates a still further embodiment of the bearing housing <NUM> provided in the laundry apparatus. This embodiment may be applied when the tub rear wall <NUM> of the embodiment shown in <FIG> is contracted.

Different from the above-noted embodiments, the length L of the second connection rib <NUM> may be shorter than the length K of the first connection rib <NUM> in this embodiment.

Accordingly, only the length of the second connection rib <NUM> is reduced in the bearing housing <NUM> such that the conventional manufacturing equipment may be used in manufacturing a different-sized laundry apparatus.

Claim 1:
A laundry apparatus comprising:
a cabinet (<NUM>);
a tub (<NUM>) provided in the cabinet (<NUM>) and configured to hold water;
a drum (<NUM>) rotatably mounted in the tub (<NUM>) and configured to accommodate laundry;
a drive unit (<NUM>) comprising a stator (<NUM>) configured to form an electromagnetic field and a rotor (<NUM>) rotatable by the electromagnetic field of the stator (<NUM>);
a shaft (<NUM>) fixed to the drum (<NUM>) and connected to the drive unit (<NUM>) via a rear wall of the tub (<NUM>);
a bearing (<NUM>) rotatably supporting the shaft (<NUM>); and
a bearing housing (<NUM>) insert-molded in the tub (<NUM>) and configured to fix the bearing (<NUM>) to the tub (<NUM>),
wherein the bearing housing (<NUM>) comprises,
a housing body (<NUM>) formed in a cylinder shape and comprising a shaft insertion hole (721a) configured to fix the bearing (<NUM>);
a first flange (<NUM>) formed in a ring shape arranged in an outer area with respect to a radial direction of the housing body (<NUM>);
a second flange (<NUM>) formed in a ring shape and arranged in an outer area with respect to a radial direction of the first flange (<NUM>);
a plurality of first connection ribs (<NUM>) provided to connect an outer circumferential surface of the housing body (<NUM>) to the first flange (<NUM>);
a plurality of second connection ribs (<NUM>) extending from the first flange (<NUM>) in a radial direction and connecting to the second flange (<NUM>) and a longitudinal axis of each second connection rib (<NUM>) is provided along a perpendicular line with respect to a circumferential surface of the housing body (<NUM>);
a plurality of first insertion holes (<NUM>) provided between two of the first connection ribs (<NUM>); and
a plurality of second insertion holes (<NUM>) provided between the second connection ribs (<NUM>),
characterized in that
the back-and-forth direction width of the first connection rib (<NUM>) becomes narrower as extended from the housing body (<NUM>) towards the first flange (<NUM>), and
the back-and-forth direction width of the second connection rib (<NUM>) becomes narrower as extended from the first flange (<NUM>) towards the second flange (<NUM>),
wherein the back-and-forth direction width of the first connection rib (<NUM>) is larger than that of the second connection rib (<NUM>), and
wherein the width of the second flange (<NUM>) is narrower than that of the first flange (<NUM>) according to a change in width of the second connection ribs (<NUM>).