Patent Description:
Generally, laundry treatment apparatuses include an apparatus that washes laundry (an object to be washed or an object to be dried), an apparatus that dries laundry, and an apparatus that is capable of performing both washing and drying of laundry.

Conventional laundry treatment apparatuses are classified into a front-loading-type laundry treatment apparatus, in which laundry is introduced into the laundry treatment apparatus through an introduction hole provided in the front surface thereof, and a top-loading-type laundry treatment apparatus, in which laundry is introduced into the laundry treatment apparatus through an introduction hole provided in the upper surface thereof.

The top-loading-type laundry treatment apparatus includes a cabinet, a tub provided in the cabinet, the tub being provided in the upper surface thereof with an introduction hole, a drum rotatably provided in the tub, and a door configured to open and close the introduction hole.

In the conventional laundry treatment apparatus having the above structure, a heater is provided in the lower surface of the tub. In the case in which the size of the tub is small, however, the heater may interfere with a stator and a rotor.

In addition, in the conventional laundry treatment apparatus, the tub includes a tub body having an open upper surface and a tub cover configured to cover the upper surface of the tub body. However, the rigidity of the conventional tub cover is low, whereby the central part of the tub cover droops.

<CIT> discloses a washing machine with a cavity formed in a periphery of a bottom surface to avoid interference with a driving part and is extended perpendicular to radial direction of an outer tub.

<CIT> (A1) relates to a washer dryer comprising a housing, a water tank placed within the housing, a washing and dewatering tank which is rotatably placed within the water tank and which accommodates laundry; and a drying system for drying the laundry within the washing and dewatering tank, wherein at least part of the drying system is provided between the water tank and the drum.

<CIT>) relates to a washing machine that comprises a detergent dissolving foaming device, said device includes a dissolving foaming cavity and a heater that can heat the detergent solution in the dissolving foaming cavity device.

<CIT>) discloses a washing machine which comprises an outer barrel and a heating device, the heating device is arranged on the outer barrel and comprises a first heating pipe and a second heating pipe, and the first heating pipe and the second heating pipe are connected and located in the outer barrel.

<CIT>) discloses a laundry apparatus including a cabinet; a first space provided in the cabinet, in which a first treating part provided to treat laundry is installed; a second space provided in the cabinet, in which a second treating part provided to treat laundry is installed; a drawer movably provided in the second space, in which the second treating part is installed; and a rail unit configured to limit vertical and horizontal movement of the drawer with respect to the second space and to guide the outward movement of the drawer.

<CIT>) discloses a washing machine which may include a cabinet that defines an accommodation space, a washing device configured to be withdrawn from the accommodation space of the cabinet, and a front panel provided in front of the washing device that defines a front external appearance of the auxiliary washing machine.

One object of the present invention devised to solve the problem lies in a laundry treatment apparatus capable of including a large-capacity heater while minimizing interference between the heater and a driving unit even in the case in which the size of a tub is small.

Another object of the present invention devised to solve the problem lies in a laundry treatment apparatus capable of minimizing a change in the outside size of a tub even in the case in which a large-capacity heater is used with a small-sized tub.

A further object of the present invention devised to solve the problem lies in a laundry treatment apparatus capable of minimizing the disturbance of flow of water stored in a tub even in the case in which a large-capacity heater is used with a small-sized tub.

The present invention is specified by the independent claim. The present invention provides a laundry treatment apparatus including a housing, a tub provided in the housing to store water, a drum provided in the tub to store an object to be washed, a driving unit provided at the outer bottom surface of the tub to rotate the drum, a heater configured to heat the water stored in the tub, and an accommodation unit provided in the bottom surface of the tub so as to be recessed downwards, the heater being provided in the accommodation unit, a portion of the accommodation unit protruding from the outer circumference of the bottom surface of the tub in the radial direction.

A first side surface of the accommodation unit may be located so as to be parallel to a tangent to the outer circumference of the bottom surface of the tub.

In addition, one vertex of the accommodation unit may be located at a contact point at which a first tangent and a second tangent to the outer circumference of the tub intersect each other.

Meanwhile, the laundry treatment apparatus may further include a protruding part protruding inwards from a second flat surface of the tub.

One surface of the protruding part may form a second side surface of the accommodation unit.

The tangent to the outer circumference of the bottom surface of the tub may be a first tangent provided at the rear of the tub.

Meanwhile, the tub may include a tub body configured to store the water and a tub cover forming the upper surface of the tub body, and the tub cover may include an insertion part configured to be inserted into the inner circumference of the tub body, a protruding part protruding from the end of the insertion part in the radial direction so as to be supported at the upper side of the tub body, and an extension part extending upwards from the end of the insertion part, the extension part being longer than the insertion part.

The height of the tub body may be lower than the height of the drum.

In addition, the laundry treatment apparatus may further include a bent part bent downwards from the end of the protruding part and a support part protruding from the tub body in the radial direction to support the bent part.

In other words, the first side surface of the accommodation unit may extend from a contact point provided at the outer circumference of the bottom surface of the tub so as to be parallel to the first tangent, which is a tangent to the contact point.

In other words, the first side surface may be provided under a first contact point.

In other words, one vertex of the accommodation unit may be located at a point at which the first tangent and a second tangent to a portion of the outer circumference of the bottom surface of the tub that is rotated from the contact point by a predetermined angle intersect each other.

In other words, the tub may include a protruding part protruding from the outer circumferential surface of the tub to the contact point.

In other words, one surface of the protruding part may form the first side surface of the accommodation unit, and the other surface of the protruding part may form the second side surface of the accommodation unit.

In other words, the second side surface may be perpendicular to the first side surface.

In other words, the first tangent may be provided at the rear of the tub.

The present invention has the effect of providing a laundry treatment apparatus capable of including a large-capacity heater while minimizing interference between the heater and a driving unit even in the case in which the size of a tub is small.

In addition, the present invention has the effect of providing a laundry treatment apparatus capable of minimizing a change in the outside size of a tub even in the case in which a large-capacity heater is used with a small-sized tub.

In addition, the present invention has the effect of providing a laundry treatment apparatus capable of minimizing the disturbance of flow of water stored in a tub even in the case in which a large-capacity heater is used with a small-sized tub.

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are shown in the accompanying drawings. Meanwhile, the configuration of an apparatus or a control method thereof, which will be given below, is merely intended to explain exemplary embodiments of the present invention, rather than limiting the technical scope of the present invention. Throughout the specification, the same reference numerals denote the same constituent elements.

A laundry treatment apparatus according to the present invention includes a housing <NUM>, a tub <NUM> provided in the housing <NUM> to store water, and a drum <NUM> rotatably provided in the tub <NUM> to store laundry.

The housing <NUM> may be constituted by a cabinet having formed therein a space, in which the tub may be accommodated. Alternatively, as shown in <FIG>, the housing <NUM> may be constituted by a drawer, which may be removed from the cabinet <NUM>. In the following description, the housing <NUM> is constituted by a drawer that is removable from the cabinet <NUM>.

The cabinet <NUM> may define the external appearance of the laundry treatment apparatus <NUM>, or may simply be a space in which the housing <NUM> is accommodated. In any case, the cabinet <NUM> may be provided in the front thereof with an open surface <NUM>, through which the housing <NUM> is inserted.

The cabinet <NUM> has a longer length in the width direction (Y-axis direction) than in the height direction (Z-axis direction). In addition, the housing <NUM> has a longer length in the width direction than in the height direction.

The housing <NUM> includes a housing body <NUM> configured to be inserted into the cabinet <NUM> through the open surface <NUM>, a housing panel <NUM> fixed to the front surface of the housing body <NUM> to open and close the open surface <NUM>, and a housing cover <NUM>, which defines the upper surface of the housing body <NUM>.

Since the housing panel <NUM> is fixed to the front surface of the housing body <NUM>, the housing panel <NUM> may also serve as a handle used to remove the housing body <NUM> from the cabinet <NUM>.

The housing panel <NUM> may be provided with a control panel <NUM>, which allows a user to input a control command related to the operation of the laundry treatment apparatus <NUM> and displays a message related to the operation of the laundry treatment apparatus.

The housing body <NUM> may be inserted into the cabinet <NUM> through the open surface <NUM>. The shape of the housing body <NUM> is not particularly restricted, as long as the housing body <NUM> provides a space to accommodate the tub <NUM>. <FIG> shows a housing body <NUM> having a hollow hexahedral shape by way of example.

The housing cover <NUM> is provided with a first through-hole <NUM> and a second through-hole <NUM>, through which the inside of the housing body <NUM> communicates with the outside. The first through-hole <NUM> is provided for the introduction and removal of laundry while the second through-hole <NUM> is provided for the supply of water necessary to wash the laundry, which will be described below in detail.

As shown in <FIG>, the tub includes a tub body <NUM>, which is located in the housing body <NUM> to store water, and a tub cover <NUM>, which defines the upper surface of the tub body <NUM>.

The tub body <NUM> may have a cylindrical shape having an open upper surface. An accommodation unit <NUM> to accommodate a heater <NUM> is provided in the bottom surface of the tub body <NUM>.

The accommodation unit <NUM> communicates with the outside via a tub through-part <NUM>. The heater <NUM> is inserted into the space defined between the bottom surface of the drum and the bottom surface of the tub through the tub through-part <NUM>.

The tub cover <NUM> may include an introduction hole <NUM>, through which the inside of the tub body <NUM> communicates with the outside of the tub body, and a supply hole <NUM>, through which water is supplied into the tub body <NUM>.

The introduction hole <NUM> may communicate with the first through-hole <NUM> in the housing cover <NUM>, and the supply hole <NUM> may communicate with the second through-hole <NUM> in the housing cover. That is, the introduction hole <NUM> may be located under the first through-hole <NUM>, and the supply hole <NUM> may be located under the second through-hole <NUM>.

The introduction hole <NUM> is means that supplies laundry into the tub body <NUM> or removes the laundry from the tub body. The introduction hole <NUM> is opened and closed by a door <NUM>.

As shown in <FIG>, the door <NUM> may include a frame <NUM> rotatably coupled to the tub cover <NUM> via a hinge <NUM>, a window <NUM> provided at the frame, and a door handle <NUM> to detachably couple the frame <NUM> to the tub cover <NUM>. The window <NUM> may be made of a transparent material such that a user can check the inside of the tub body <NUM>.

The window <NUM> may be made of a transparent material such that the user can check the inside of the tub body <NUM> when the housing <NUM> is removed from the cabinet <NUM>.

Meanwhile, in order to prevent the water in the tub body <NUM> from being discharged to the outside of the tub body <NUM> through the introduction hole <NUM>, one of the frame <NUM> and the tub cover <NUM> may be further provided with a sealing portion <NUM> to seal the space between the frame <NUM> and the introduction hole <NUM> when the door <NUM> closes the introduction hole <NUM>.

As shown in <FIG>, the drum <NUM>, provided in the tub <NUM>, may include a cylindrical drum body <NUM> having an open upper surface <NUM>. Since the open surface <NUM> is located under the introduction hole <NUM>, laundry supplied through the introduction hole <NUM> is supplied into the drum body <NUM> through the open surface <NUM>.

A plurality of drum through-holes <NUM>, through which the inside of the drum body <NUM> communicates with the tub body <NUM>, may be provided in the bottom surface <NUM> and the circumferential surface <NUM> of the drum body <NUM>.

The drum body <NUM> is rotated in the tub body <NUM> by a driving unit. The driving unit may include a stator M1, which is located outside the tub body <NUM> and is fixed to the bottom surface of the tub body, a rotor M2, which is rotated by a rotating field generated by the stator, and a rotary shaft M3, which extends through the bottom surface of the tub body to interconnect the bottom surface <NUM> of the drum and the rotor M3. In this case, the rotary shaft M3 may be perpendicular to the bottom surface of the tub body <NUM>.

The tub <NUM> having the above structure is coupled to the housing body <NUM> via a tub support unit <NUM>. The tub support unit <NUM> may include a first support part <NUM> provided at the housing body <NUM>, a second support part <NUM> provided at the tub body <NUM>, and a connection part <NUM> that interconnects the first support part and the second support part.

As shown in <FIG>, the connection part <NUM> may include a first connection part <NUM> located at the first support part <NUM>, a second connection part <NUM> that supports the second support part <NUM>, and a bar <NUM> that interconnects the first connection part and the second connection part.

The first connection part <NUM> may be located in the first support part <NUM>, and may have a shape that is movable in the first support part <NUM>. The second connection part <NUM> may support the second support part <NUM>, and may have a shape movable in the second support part <NUM>. In an example, the surfaces of the first connection part <NUM> and the second connection part <NUM> that contact the respective support parts <NUM> and <NUM> may be hemispherical. In another example, the first connection part <NUM> and the second connection part <NUM> may be spherical.

Meanwhile, the respective support parts <NUM> and <NUM> may be provided at the position at which the bar <NUM> is perpendicular to the bottom surface of the cabinet <NUM> (the position at which the bar is perpendicular to the bottom surface of the housing).

The laundry treatment apparatus according to the present invention is configured such that at least three tub support units <NUM> are provided to couple the tub body <NUM> to the housing body <NUM> and such that the bar <NUM> is perpendicular to the bottom surface of the housing body <NUM>. Consequently, it is possible to increase the distance between the tub cover <NUM> and the housing cover <NUM> compared to the case in which the bar <NUM> is inclined at a predetermined angle relative to the Z-axis. Even when the tub body <NUM> vibrates in the housing body <NUM>, therefore, the tub support units <NUM> may reduce the possibility of the tub cover <NUM> colliding with the housing cover <NUM>.

As shown in <FIG>, the second support part <NUM>, provided at the tub body <NUM>, may include an accommodation recess <NUM>, in which the second connection part <NUM> is located, a through-hole <NUM>, into which the bar <NUM> of the connection part is inserted, and a slit <NUM>, through which the bar <NUM> is inserted into the center of the through-hole from the edge of the through-hole.

The first support part <NUM> and the second support part <NUM> may serve as support points of the connection part <NUM> when the tub body <NUM> is vibrated. For this reason, it is advantageous for the frictional force between the first support part <NUM> and the first connection part <NUM> and the frictional force between the second support part <NUM> and the second connection part <NUM> to be small. Consequently, the first support part <NUM> and the second support part <NUM> may be made of a self-lubricative material.

When considering that it is natural for the first support part <NUM> to be made of the same material as the housing body <NUM> by injection molding and for the second support part <NUM> to be made of the same material as the tub body <NUM> by injection molding, however, only the first connection part <NUM> and the second connection part <NUM> may be made of a self-lubricative material, or only a first bracket <NUM>, the first connection part <NUM>, and the second connection part <NUM> may be made of a self-lubricative material.

In order to most stably support the tub body <NUM>, a plurality of second support parts <NUM> may be radially disposed at the circumferential surface of the tub body <NUM> so as to be spaced apart from each other by the same angle. That the second support parts <NUM> are radially disposed at the circumferential surface of the tub body means that the second support parts <NUM> are provided so as to be symmetrical with respect to the rotary shaft M3, which is located at the center of the bottom surface of the tub body.

In the laundry treatment apparatus <NUM> having the above structure, water is supplied to the tub <NUM> through the water supply unit <NUM>, and the water stored in the tub <NUM> is discharged to the outside of the cabinet <NUM> through the drainage unit <NUM>.

As shown in <FIG>, the water supply unit <NUM> may include a first water supply pipe <NUM> connected to the supply hole <NUM> provided in the tub cover, a second water supply pipe <NUM> connected to a water source located outside the cabinet, and a connection pipe <NUM> fixed to the tub cover <NUM> to interconnect the first water supply pipe and the second water supply pipe.

The first water supply pipe <NUM> may interconnect the supply hole <NUM> and the connection pipe <NUM> through the second through-hole <NUM> provided in the housing cover <NUM>, and may be constituted by a bellows pipe in order to prevent the first water supply pipe <NUM> from being separated from the connection pipe <NUM> when the tub <NUM> is vibrated (see <FIG>).

In addition, the second water supply pipe <NUM> may also be constituted by a bellows pipe in order to prevent the second water supply pipe <NUM> from being separated from the connection pipe <NUM> when the housing is removed from the cabinet <NUM>. The second water supply pipe <NUM> is opened and closed by a water supply valve <NUM>, which is controlled by a controller (not shown).

Unlike what is shown in <FIG>, however, the water supply unit <NUM> may include a single water supply pipe that interconnects a water source (not shown) located outside the cabinet and the supply hole <NUM> provided in the tub cover. In this case, the water supply pipe may be constituted by a bellows pipe.

The drainage unit <NUM> may include a drainage pump <NUM> fixed to the housing body <NUM>, a first drainage pipe <NUM> configured to guide the water in the tub body <NUM> to the drainage pump <NUM>, and a second drainage pipe <NUM> configured to guide the water discharged from the drainage pump <NUM> to the outside of the cabinet <NUM>. In this case, the second drainage pipe <NUM> may be constituted by a bellows pipe.

<FIG> is a perspective view showing the tub of the laundry treatment apparatus according to the embodiment of the present invention. <FIG> is a plan view showing the tub body of the laundry treatment apparatus according to the embodiment of the present invention. <FIG> is a bottom view showing the tub body of the laundry treatment apparatus according to the embodiment of the present invention.

The accommodation unit for accommodating the tub body <NUM> and the heater <NUM> will be described below in detail.

As shown in <FIG>, the tub <NUM> includes a tub body <NUM>, which is located in the housing body <NUM> to store water, and a tub cover <NUM>, which defines the upper surface of the tub body <NUM>.

The upper surface of the tub body <NUM> is open. The tub body <NUM> includes a bottom surface 41a of the tub body <NUM> and a side surface 41b of the tub body <NUM>.

An accommodation unit <NUM> to accommodate a heater <NUM> is provided in the bottom surface 41a of the tub body <NUM>.

The heater <NUM> heats the water stored in the tub <NUM> to provide hot water necessary for washing, or changes the water into steam, which is supplied to laundry. A sheath heater is generally used as the heater <NUM>. The sheath heater, which is a basic electric heater, is a pipe-shaped heater configured such that an electric wire is mounted in a metal protection pipe in the form of a coil and the metal protection pipe is filled with magnesium oxide, which is insulative powder, in order to insulate the electric wire and the protection pipe.

The accommodation unit <NUM> is provided in the bottom surface 41a of the tub body <NUM> so as to be recessed downwards. The heater, which is accommodated in the accommodation unit <NUM>, does not protrude above the bottom surface 41a of the tub body <NUM>. That is, the heater <NUM> is located between the bottom surface <NUM> of the drum and the bottom surface 41a of the tub. The heater <NUM> is accommodated in the accommodation unit <NUM> so as not to protrude from the bottom surface 41a such that the heater <NUM> does not collide with the drum <NUM> when the drum is rotated by the driving unit.

At the outside of the tub <NUM>, the accommodation unit <NUM> is provided so as to protrude downwards from the bottom surface 41a of the tub. In this case, one side of the accommodation unit communicates with the outside through a tub through-part <NUM>. The heater <NUM> may be inserted into or removed from the accommodation unit <NUM> through the tub through-part <NUM>. The heater <NUM> is inserted into the accommodation unit <NUM>, and is then installed in the accommodation unit <NUM>.

In consideration of the fact that the accommodation unit <NUM> is means that initially supplies water into the tub body <NUM> to the heater <NUM> in order to prevent overheating of the heater and prevents the heater from being damaged by the bottom surface <NUM> of the drum during the rotation of the drum <NUM>, it is inevitable for the accommodation unit <NUM> to protrude from the bottom surface of the tub body <NUM>.

As previously described, in order to rotate the drum <NUM>, the driving unit includes the stator M1, which is installed outside the tub body <NUM> and fixed to the bottom surface 41a of the tub body <NUM>, and the rotor M2, which is rotated by the stator.

Consequently, it is necessary to prevent the rotating rotor M2 from being interfered with by the accommodation unit <NUM>. However, the size of the driving unit, which rotates a drum <NUM> having a predetermined size or more, is fixed, irrespective of the size of the drum <NUM>.

In the case in which the size of the tub <NUM> is large and thus the diameter of the tub <NUM> is large, the accommodation unit <NUM>, which protrudes from the bottom surface 41a of the tub <NUM>, is provided inside the outer circumference of the bottom surface 41a of the tub <NUM> with a spatial margin. Even though the stator M1 and the rotor M2 are installed, therefore, the rotor M2 and the accommodation unit <NUM> do not interfere with each other.

In the case in which the size of the tub <NUM> is reduced, the diameter of the tub <NUM> is reduced, but the size of the stator M1 and the rotor M2 is not reduced. As a result, it is not possible to provide the accommodation unit <NUM> in the outer circumference of the bottom surface 41a of the tub <NUM>.

In addition, the height of the accommodation unit <NUM>, by which the accommodation unit <NUM> can protrude from the bottom surface of the tub body, is limited (the thickness of the heater is limited). In the case in which the length or the width of the accommodation unit <NUM> is reduced, it is necessary to reduce the size of the heater <NUM>. In this case, it is difficult to mount a heater capable of generating a large amount of heat per unit time.

In order to solve the above problem, the laundry treatment apparatus according to the present invention is configured to have a structure in which the accommodation unit <NUM> is provided in the outer circumference of the bottom surface 41a of the tub <NUM> such that a portion of the accommodation unit <NUM> protrudes in the radial direction.

A portion of the area of the accommodation unit <NUM> protrudes from the outer circumference of the bottom surface 41a of the tub <NUM>. That is, a portion of the area of the accommodation unit <NUM> deviates from the radius R of the bottom surface 41a of the tub <NUM>.

Consequently, the rotor M is rotated without being interfered with by the accommodation unit <NUM>.

If the accommodation unit <NUM> deviates from the bottom surface 41a of the tub <NUM>, however, the size of the tub <NUM> is increased, whereby interference with the housing <NUM> occurs. In order to solve the above problem, it is necessary to minimize the size of the accommodation unit <NUM> that deviates and protrudes from the bottom surface 41a of the tub <NUM>.

As shown in <FIG> and <FIG>, the accommodation unit <NUM> is provided at the rear side of the bottom surface 41a of the tub <NUM> (in the negative x-axis direction). Consequently, the front side of the tub <NUM>, which is exposed to the user, may remain curved. In addition, the accommodation unit <NUM> includes a drainage hole <NUM> formed in a bottom surface <NUM> thereof. The drainage hole <NUM> is connected to the first drainage pipe <NUM>, and the first drainage pipe <NUM> is connected to the drainage pump <NUM>, which is provided at the rear surface of the housing body <NUM>. Consequently, it is possible to minimize the length of the first drainage pipe <NUM>.

The accommodation unit <NUM> may be quadrangular, and is provided in the bottom surface 41a of the tub <NUM> so as to be recessed. The accommodation unit <NUM> may have a bottom surface <NUM>, a first side surface <NUM>, a second side surface <NUM>, a third side surface <NUM>, and a fourth side surface <NUM>.

The first side surface <NUM> of the accommodation unit <NUM> may be parallel to a tangent to the outer circumference of the bottom surface 41a of the tub.

Specifically, the first side surface <NUM> may be provided so as to be parallel to a first tangent TL1 to the outer circumference of the bottom surface 41a of the tub <NUM>. Alternatively, the first side surface <NUM> may be provided so as to be the same as the first tangent TL1 to the outer circumference of the bottom surface 41a of the tub <NUM>.

The first tangent TL1 is a tangent of a point T1 located at the rear side of the bottom surface 41a of the tub <NUM> from the center O thereof (in the negative x-axis direction). That is, the first side surface <NUM> is provided so as to be parallel to the rear surface of the housing body <NUM>.

In other words, the first side surface <NUM> may have a contact point T1, which contacts the outer circumference of the bottom surface 41a of the tub <NUM>, and may extend parallel to the first tangent TL1, which is formed at the contact point T1.

Specifically, the first side surface <NUM> may be provided under the contact point T1, since the accommodation unit <NUM> is provided in the bottom surface of the tub <NUM>.

The first side surface <NUM> may extend from the contact point T1 so as to be parallel to the first tangent TL1 only in one direction, or may extend from the contact point T1 so as to be parallel to the first tangent TL1 in both directions (opposite directions).

That is, the first side surface <NUM> may include a contact point that forms the outer circumference of the bottom surface 41a of the tub <NUM> and an extension surface that extends from the contact point.

The second side surface <NUM> of the accommodation unit <NUM> is connected to the first side surface <NUM> in order to form the accommodation unit <NUM>. The second side surface <NUM> may be perpendicular to the first side surface <NUM>. The tub through-part <NUM> is formed in the second side surface <NUM>. The heater is inserted into the accommodation unit <NUM> through the tub through-part <NUM>, and is then installed in the accommodation unit <NUM>.

The second side surface <NUM> of the accommodation unit <NUM> protrudes from the outer circumference of the bottom surface 41a of the tub <NUM>. That is, one end of the second side surface <NUM> of the accommodation unit <NUM> deviates from the radius R of the outer circumference of the bottom surface 41a of the tub <NUM>.

Meanwhile, the third side surface <NUM> of the accommodation unit <NUM> is connected to the second side surface <NUM> so as to be parallel to the first side surface <NUM>, and the fourth side surface <NUM> of the accommodation unit <NUM> is connected to the first side surface <NUM> and the third side surface <NUM> so as to be parallel to the second side surface <NUM>.

When defining a tangent at a point T2 located at the outer circumference of the bottom surface 41a of the tub <NUM>, which is rotated by a predetermined angle θ from the point T1 located at the outer circumference of the bottom surface 41a of the tub <NUM> on the basis of the center of the bottom surface of the tub <NUM>, as a second tangent TL2, one vertex of the accommodation unit <NUM> may be located at a contact point C at which the first tangent TL1 and the second tangent TL2 intersect each other.

The contact point C may be defined as a point C in order to avoid confusion of terms.

Meanwhile, the accommodation unit <NUM> may protrude from the bottom surface 41a of the tub in the circumferential direction of the tub, and the side surface 41b of the tub <NUM> may have a cylindrical shape. In the present invention, however, the outer circumferential surface of the side surface 41b of the tub body <NUM> may have a first flat surface S1 between the point T1 and the point C, a second flat surface S2 between the point C and the point T2, and a curved surface between the point T1 and the point T2 in order to make it easy to form the tub body <NUM>. In this case, the first flat surface S1 may be parallel to the first side surface <NUM>. Consequently, the side surface 41b of the tub is perpendicular to the bottom surface 41a of the tub including the accommodation unit <NUM>, whereby it is possible to easily form the tub body <NUM>.

Therefore, it is possible to minimize the range of the accommodation unit <NUM> within which the accommodation unit <NUM> deviates from the outer circumference of the tub <NUM>. The reason for this is that, on the assumption that an imaginary quadrangular area of the tub body <NUM> in the housing <NUM> is Sq, it is necessary to increase the size of the housing <NUM> in order to maintain the distance between the tub <NUM> and the housing <NUM> when the area of the quadrangle Sq is increased. However, the accommodation unit <NUM>, provided in the bottom surface 41a of the tub <NUM>, is provided so as not to substantially increase the area of the quadrangle Sq. The reason for this is that the accommodation unit <NUM> is provided in the space of the quadrangle Sq that is not occupied by the tub <NUM>, whereby the external volume of the tub <NUM> is increased.

That is, it is not necessary to reduce the size of the tub body <NUM> due to interference with the housing <NUM>, even though the volume of the tub body <NUM> is increased.

Meanwhile, it is necessary to minimize interference with the accommodation unit <NUM> when the water stored in the tub body <NUM> is rotated along with the rotation of the drum <NUM>.

To this end, the laundry treatment apparatus according to the present invention includes a protruding part <NUM> protruding from the inner circumferential surface of the tub body <NUM>.

The protruding part <NUM> is provided so as to protrude inwards from the second flat surface S2, which constitutes the tub body <NUM>. Alternatively, the protruding part <NUM> may be provided so as to protrude inwards from the second tangent TL2.

The protruding part <NUM> includes a first protruding surface <NUM> provided so as to be parallel to the second side surface <NUM> of the accommodation unit and a second protruding surface <NUM> configured such that the distance between the second protruding surface <NUM> and the center O of the tub <NUM> is the radius R of the bottom surface 41a of the tub body <NUM>.

Since the first protruding surface <NUM> is vertically provided so as to be parallel to the second side surface <NUM>, it is possible to easily form the tub body <NUM> including the accommodation unit <NUM>.

The inner circumferential surface of the side surface 41b of the tub body <NUM>, excluding the portion thereof in which the accommodation unit <NUM> is provided, remains circular due to the second protruding surface <NUM>. When the water stored in the tub <NUM> is rotated as the result of rotating the drum <NUM>, therefore, the water may smoothly move in the tub <NUM> along the second protruding surface <NUM>, whereby it is possible to minimize eddy current generated in the accommodation unit <NUM>.

<FIG> is a view showing the tub cover of the laundry treatment apparatus according to the embodiment of the present invention. <FIG> is a partial sectional view showing the laundry treatment apparatus according to the embodiment of the present invention.

The tub body and the tub cover of the present invention will be described with reference to <FIG> and <FIG>.

The height of the tub body <NUM> is configured to be smaller than the height of the drum <NUM>, but the height of the tub cover <NUM> is increased such that the tub body <NUM> and the tub cover <NUM> are coupled in order to provide the drum <NUM> in the tub <NUM>. It is not easy to install the drum <NUM> in the tub <NUM>, since the space between the tub and the drum is not wide. Since the tub body is not high, however, it is possible for a worker to install the drum in the tub body while holding the upper side of the drum, whereby it is possible for the worker to easily perform the assembly process.

The tub cover <NUM> may include an insertion part <NUM>, which is inserted into the inner circumference of the tub body <NUM>, a protruding part <NUM>, which protrudes from the end of the insertion part <NUM> in the radial direction so as to be supported at the upper side of the tub body <NUM>, and an extension part <NUM>, which extends upwards from the end of the insertion part <NUM>.

The outer circumferential diameter of the insertion part <NUM> is configured to be smaller than the inner circumferential diameter of the side surface 41b of the tub body <NUM> such that the insertion part <NUM> can be inserted into the tub body <NUM>.

The protruding part <NUM> extends from the side surface of the tub cover <NUM> in the radial direction. The protruding part <NUM> is provided around the tub cover <NUM> to support the tub cover at the upper side of the tub body.

The extension part <NUM> extends upwards from the end of the insertion part <NUM> or the protruding part <NUM>, and an upper surface <NUM> of the tub is provided at the end of the extension part. Compared to the case in which the horizontal upper surface of the tub is provided at the protruding part <NUM> without the extension part <NUM>, therefore, it is possible to increase the rigidity of the tub cover, whereby it is possible to prevent twisting or drooping of the tub cover.

In this case, the height h2 of the extension part <NUM> is configured to be larger than the length h1 of the insertion part <NUM>. Consequently, it is possible to substantially increase the inner volume of the tub <NUM>. In addition, it is possible to increase the rigidity of the tub cover, whereby it is possible to prevent drooping of the central part of the tub cover.

Meanwhile, the tub cover <NUM> may include a curved part <NUM> provided between the end of the extension part <NUM> and the upper surface <NUM> of the tub <NUM> so as to be bent toward the inside of the tub. Consequently, the area of the upper surface <NUM> of the tub may be reduced, by which the load applied to the center of the upper surface may be reduced, whereby it is possible to prevent drooping of the upper surface of the tub and to prevent twisting of the tub cover.

In other words, the extension part <NUM>, provided at the upper side of the protruding part <NUM> of the tub cover <NUM>, the curved part <NUM>, and the upper surface <NUM> of the tub form the shape of a cup, whereby the rigidity of the tub cover is increased.

Meanwhile, the tub cover <NUM> includes a bent part <NUM> bent downwards from the end of the protruding part <NUM>. The bent part <NUM> is provided around the tub cover <NUM>. Consequently, the rigidity of the tub cover <NUM> is increased, whereby it is possible to prevent twisting or drooping of the tub cover.

In addition, a support part <NUM> protruding from the tub body <NUM> in the radial direction may be provided in order to support the bent part <NUM>. Consequently, the end of the bent part <NUM> is supported at the upper surface of the support part <NUM>.

The tub cover <NUM> includes a reinforcement rib <NUM> protruding in the radial direction of the protruding part <NUM>. The reinforcement rib <NUM> is provided with a first fastening hole <NUM> provided to fasten the tub cover <NUM> to the tub body <NUM>. A second fastening hole (not shown) may be provided in the support part <NUM> of the tub body <NUM>. When the upper side of the tub body <NUM> is covered by the tub cover <NUM>, the second fastening hole may communicate with the first fastening hole <NUM>. Consequently, it is possible to fix the tub body and the tub cover using a fixing member extending through the first fastening hole <NUM> and the second fastening hole (not shown).

Claim 1:
A laundry treatment apparatus (<NUM>) comprising:
a housing (<NUM>);
a tub (<NUM>) provided in the housing (<NUM>) and including a tub body (<NUM>) configured to store water;
a drum (<NUM>) provided in the tub (<NUM>) to store an object to be washed;
a driving unit located at an outside of a bottom surface of the tub (<NUM>) to rotate the drum (<NUM>);
a heater (<NUM>) configured to heat the water stored in the tub (<NUM>);
an accommodation unit (<NUM>) located at the bottom surface of the tub (<NUM>) that defines a recess at the bottom surface of the tub, and that is configured to accommodate the heater (<NUM>) in the recess, and
a drainage unit (<NUM>) connected to a bottom surface (<NUM>) of the accommodation unit (<NUM>) to discharge water in the tub (<NUM>) to the outside of the laundry treatment apparatus (<NUM>);
wherein a width of the housing (<NUM>) is longer than a height of the housing (<NUM>); and
wherein the accommodation unit (<NUM>) comprises a protruded portion that protrudes in a radial direction from the bottom surface (41a) of the tub (<NUM>) to deviate from a radius (R) defined by a curved circumferential part of a side surface (41b) of the tub body (<NUM>).