Patent Description:
Laundry non-uniformly distributed inside the drum of a washing machine generates a rotating unbalance and undesired vibrations of the whole machine during centrifugation. In order to keep the vibration of the casing at a low level, the tub is suspended inside the casing by means of a system of springs and damping elements. This system reduces the vibrational forces transferred to the casing. Document <CIT> discloses a laundry washing machine comprising a casing, a rotatable drum and a tub enclosing the drum, the washing machine of <CIT> further comprises a support device separate from and within said casing, wherein said tub is mounted to said support device, and elastic damping elements provided between the support device and a foot section, wherein the casing is arranged on the support device and the foot section comprises feet.

The problem to be solved by the present invention is to provide a washing machine with reduced vibrations of the casing.

This problem is solved by the washing machine of the independent claim. Accordingly, the washing machine comprises at least the following parts:.

The damping element(s) form the sole mechanical connection between the support device and the casing.

This arrangement has the advantage of reducing the vibrations transferred from the tub to the casing since the tub is mounted on a support device separate from the casing. With this design, less vibrations are transferred to the casing.

Advantageously, the tub is suspended from the support device, i.e. a major part of its weight, in particular at least <NUM>% or its weight, in particular at least <NUM>% of its weight, is suspended from the support device. In particular, the "weight of the tub" includes the weight of a drive for rotating the drum.

The machine further comprises a "foot section", which is the part touching the floor the machine stands on and that supports the weight of the machine. In addition, there is or are one or more damping elements, which (directly or indirectly) couple the support device to the foot section. This allows to damp the vibrations of the support device. According to the invention, the damping element(s) form the sole mechanical connection between the support device and the foot section.

The stiffness of the connection between the casing and the foot section is at least ten times, in particular at least fifty times, higher than the stiffness of the connection between the support device and the foot section. Hence, the casing will tend to rest stationary on the foot section even when the support device vibrates. Advantageously, this relation of the stiffness holds true for all six degrees of freedom of relative movement.

Similarly, the stiffness of the connection between the support device and the foot section is at least ten times, in particular at least fifty times, higher than the stiffness of the connection (if there is any such connection) between the support device and the casing. This minimizes the coupling between the support device and the casing. Advantageously, this relation of the stiffness holds true for all six degrees of freedom of relative movement.

Advantageously, the damping elements receive at least <NUM>% of the weight of the drum and the tub. In particular, the receive all of the weight of the drum and the tub. This improves the decoupling of the drum and tub from the casing.

Advantageously, the damping element(s) comprise, in particular consist of, a material having a hardness between <NUM> Shore A and <NUM> Shore D, and/or the damping element(s) comprise, in particular consist of, an elastomer, and/or the damping element(s) comprise, in particular consist of, an EPDM rubber.

Advantageously, the thickness of the damping element(s) is at least <NUM>, in particular at least <NUM>, in particular at least <NUM>. In particular, this relates to the thickness of the damping element(s) in the vertical direction.

The foot section can comprise one or more foot members, in particular at least three foot members, in particular at least four foot members.

In this case, the total connection between all the foot members and the casing is at least ten times, in particular at least fifty times, stiffer than the connection between all the foot members and the support device. Advantageously, this relation of the stiffness holds true for all six degrees of freedom of relative movement.

The foot member can comprise at least one support surface, wherein the casing is arranged on said support surface. The damping element is arranged vertically above the support surface between the casing and the support device to vertically support the support device. This provides a stiff coupling between the foot member and the casing and a less stiff coupling between the foot member and the support device.

Furthermore, said support surface horizontally extends at least over <NUM>%, in particular at least over <NUM>%, in particular at least over <NUM>%, of the area of said damping element.

The larger the support surface is, the better it can prevent the vibrations of the support member from being transferred to the casing. The support surface should not be much smaller than the damping element and is advantageously larger than the damping element.

Advantageously, the foot member comprises a projection extending through an opening in the support device. The damping element also extends into this opening and is located there between the projection and the support device, thus providing a good dampening in horizontal direction.

In another advantageous embodiment, the casing and the support device are arranged at a distance from each other. This distance should be at least <NUM>, in particular at least <NUM>.

This type of support device surrounds the tub at least partially and allows to support the same from several sides.

The support frame can comprise two support members arranged laterally at opposite sides of the tub and an interconnecting member arranged above the tub. The interconnecting member interconnects the support members. The bottom ends of the support members are mounted to the support base. This provides a support frame of basically inverted U-shape, and the interconnecting member helps to increase the stiffness of the support frame.

In particular, the interconnecting member is, in vertical direction, thinner at its center than the support members in horizontal direction, thus providing more room for the tub.

Advantageously, the support base has a central opening located vertically below the tub. This reduces the weight of the support base and/or provides more room for the tub.

Advantageously, the washing machine comprises exactly one support frame. Alternatively, for increased stability but at the cost of a higher weight and higher complexity, it may comprise two or more support frames.

Furthermore, at least one, in particular a majority of, in particular all, of the following elements of the washing machine, if present in the washing machine, are mounted to the support device: the water pump, a heat pump, a fan, a valve.

Such elements are vibrating or at least moving during operation. If they are mounted to the support device, the noise and/or vibration of their operation is not (or to a lesser degree) transferred to the casing.

The machine can comprise at least one, in particular two, spring members suspending the tub from the support device and/or it can comprise at least one damping member arranged between the tub and the support device.

The spring members advantageously transfer the forces in a direction which is at an angle between <NUM>° and <NUM>° in respect to the vertical direction.

Advantageously, the support device is of steel for high rigidity.

The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. This description makes reference to the annexed drawings, wherein:.

<FIG> shows a washing machine without its casing. The washing machine comprises a tub <NUM>. Tub <NUM> encloses a rotatable drum <NUM> for receiving the laundry for washing and, optionally, centrifugation.

Drum <NUM> can be rotated e.g. about a substantially horizontal axis of rotation. In particular, the axis of rotation of the drum <NUM> deviates by less than <NUM>°, in particular by less than <NUM>°, from the horizontal direction.

The washing machine further comprises a support device <NUM> for supporting the tub <NUM>. Support device <NUM> includes, in the shown embodiment, a support base <NUM> and a support frame <NUM>, <NUM>, <NUM>.

Support device <NUM> is supported by several, e.g. four, foot members 4a, 4b, 4c. forming a foot section <NUM> of the device. In operating position, the whole weight of the machine rests on foot section <NUM> and foot section <NUM> is in direct contact with e.g. the ground or shelf the machine is placed on.

Support base <NUM> forms a frame surrounding a central opening <NUM> located vertically below tub <NUM>.

Support base <NUM> supports support frame <NUM>, <NUM>, <NUM>.

Support frame <NUM>, <NUM>, <NUM> comprises two support members <NUM> and <NUM>, which are arranged laterally at opposite sides of tub <NUM> and e.g. consist of two vertical pillars. The two support members <NUM> and <NUM> are interconnected, at their upper ends, by an interconnecting member <NUM>, which is arranged vertically above tub <NUM>.

In vertical direction, the thickness of interconnecting member <NUM> at its center 63a is smaller than the thickness of the support members <NUM>, <NUM> in horizontal direction.

Support device <NUM> is advantageously made of steel.

The support members <NUM> and <NUM> are mounted on support base <NUM> by means of stiff couplings <NUM>. Each stiff coupling <NUM> is e.g. a sleeve that holds the respective support member <NUM>, <NUM> in a fixed position relative to support base <NUM>. Alternatively or in addition thereto, the couplings can e.g. be formed or reinforced by welding.

In an alternative embodiment, the washing machine may comprise two support frames <NUM>, <NUM>, <NUM>, both of which are mounted on support base <NUM>. For example, the two support frames can be located at a distance from each other along the axis of rotation of drum <NUM>.

<FIG> shows the washing machine from its front side, again without the casing.

As can be seen, one or more baffles <NUM> to <NUM> are arranged inside drum <NUM> in a design basically known to the skilled person.

Tub <NUM> is suspended from support device <NUM>, in particular from support frame <NUM>, <NUM>, <NUM>, by e.g. two spring members <NUM> and <NUM>.

Furthermore, e.g. two or three damping members <NUM> to <NUM> support tub <NUM> from below. Advantageously, the damping members <NUM> to <NUM> are connected to support base <NUM>.

All vibrations caused by tub <NUM> during the centrifugation of the wet laundry are transferred to support base <NUM>, either via the spring members <NUM> and <NUM> and support frame <NUM>, <NUM>, <NUM> or via the damping members <NUM> to <NUM>.

Other vibrating or noise-generating machine elements <NUM> and <NUM>, such as a water pump, a heat pump, fans, etc. are advantageously mounted to support device <NUM>, in particular to support base <NUM>
As already mentioned, support device <NUM> is supported by the foot members 4a, 4b, 4c, which are arranged on the ground when the machine is in its operating position.

Due to the described arrangement, both the vibrations of the tub <NUM> and the vibrations of the machine elements <NUM> and <NUM> are directly transferred to the support device <NUM> and from there to the ground via the foot members 4a, 4b, 4c.

The vibrations are not, or only to a small degree, transferred to the casing (shown in <FIG>) of the washing machine.

<FIG> shows one foot member <NUM> in a detailed, sectional view. It comprises a sole <NUM>, a projection <NUM> extending upwards from sole <NUM>, and a support element <NUM>.

The projection <NUM> extends upwards through an opening <NUM> of support base <NUM>.

Support element <NUM> is screwed to an outer threading on projection <NUM> and is thus adjustable in height. It has a vertical sleeve <NUM> engaging the threading of support element <NUM> as well as a horizontally projecting tray section <NUM>.

A nut <NUM> is used to secure foot member 4a.

In the present embodiment, the upper surface of tray section <NUM> forms a support surface <NUM>.

The casing <NUM> of the washing machine is arranged on the support surface <NUM>, in particular it rests thereon. This provides a stiff support of casing <NUM> on foot member 4a and therefore on the ground.

A damping element <NUM> is arranged between casing <NUM> and support base <NUM>. Its purpose is to damp the vibrations of support device <NUM> during the operation of the machine, in particular during centrifugation.

Advantageously, damping element <NUM> is an EPDM rubber.

Damping element <NUM> comprises a sleeve-shaped, vertical section <NUM> and a horizontal section <NUM> extending horizontally outwards from vertical section <NUM>.

Horizontal section <NUM> is located between casing <NUM>, in particular a horizontally extending bottom section <NUM> of casing <NUM>, and support base <NUM>. It supports the weight of support device <NUM> as well as of tub <NUM>, drum <NUM>, and the laundry and water arranged therein.

In horizontal direction, vertical section <NUM> of damping element <NUM> is arranged between support base <NUM> and sleeve <NUM> of support element <NUM>.

As can be seen, casing <NUM> and support device <NUM> are arranged at a distance from each other such that vibrations cannot be transferred directly from support device <NUM> to casing <NUM>.

In the present embodiment, support device <NUM> and casing <NUM> are only connected via damping element <NUM>. And since the coupling of casing <NUM> to the ground through support element <NUM> is much stiffer than any coupling of casing <NUM> to support device <NUM>, vibrations are not transmitted to casing <NUM>.

As can be seen in <FIG>, support surface <NUM> is located vertically below damping element <NUM>. Advantageously, support surface <NUM> extends, in horizontal direction, over at least <NUM>% of the area of horizontal section <NUM> of damping element <NUM>. This is to be understood such that the area of bottom side <NUM> of damping element <NUM> is smaller than or at most equal to the area of support surface <NUM> of foot member <NUM>. Thus, no bending forces are exerted to base section <NUM> of housing <NUM>, which further reduces the transmission of vibrations.

Casing <NUM> of the machine can e.g. be of sheet metal or of plastics.

Advantageously, casing <NUM> encloses the machine from the front side, where it has a door giving access to the interior of drum <NUM>, its back side (i.e. the side opposite to the door), from its two lateral sides as well as from above.

In the above embodiments, support frame <NUM>, <NUM>, <NUM> and support base <NUM> are different elements joined to each other by means of a rigid connection. Alternatively, all of support device <NUM> can be of a single piece or it can be constructed from differently assembled subparts.

A weak coupling between support device <NUM> and casing <NUM> is, even though not preferred, well within the scope of the present invention. For example, soft, foamed elements may be provided between these parts in order to reduce the risk of violent impacts under extremely strong vibrations. Advantageously, though, the stiffness of the various couplings should be within the parameters indicated above.

Even though the above embodiment shows tub <NUM> to be suspended from support device <NUM>, it may also rest on support base <NUM> only by means of elastic, dampening support elements.

Instead of placing casing <NUM> on support surface <NUM>, casing <NUM> may be connected to the foot section in different manner, e.g. by using a part separate from support element <NUM> in order to obtain improved decoupling between support device <NUM> and casing <NUM>. Casing <NUM> may even rest on the ground directly.

Even though the embodiment shown is a machine for washing laundry only, the invention can also be applied to washer-driers, where the laundry can be dried after washing, e.g. by means of hot, dehydrated air.

Claim 1:
A washing machine for laundry comprising
- a casing (<NUM>),
- a rotatable drum (<NUM>),
- a tub (<NUM>) enclosing said drum (<NUM>) for receiving laundry,
- a support device (<NUM>),
- a foot section (<NUM>) and
- one or more damping elements (<NUM>) coupling said support device (<NUM>) and said foot section (<NUM>),
characterized by
the support device (<NUM>) being separate from and within said casing (<NUM>), wherein said tub (<NUM>) is mounted to said support device (<NUM>), and wherein said one or more damping elements (<NUM>)
form the sole mechanical connection between the support device (<NUM>) and the casing (<NUM>).