Pulley and washing machine with a pulley

Abstract

 The pulley comprises at least one vane. The washing machine comprises a pivoted drum for holding clothes wherein the drum is positioned within a tub, the drum being functionally connected to a shaft that passes through a bearing of the tub. A pulley is fixed to the shaft outside the tub, wherein the pulley comprises at least one vane to create a flow of air at least to or from the bearing.

Description

BACKGROUND OF THE INVENTION

Field of the invention

[0001] The invention relates to a pulley, in particular for use with a household appliance, a washing machine comprising a pivoted drum for holding clothes wherein the drum is positioned within a tub, the drum being functionally connected to a shaft that passes through a bearing of the tub, wherein a pulley is fixed to the shaft outside the tub, and to a method for cooling a region in the vicinity of a shaft fitted with a pulley.

Prior art

[0002] Modern washing machines comprise a pivoted drum for holding clothes wherein the drum is positioned within a tub ('drum housing'). The drum is typically connected to a shaft that leads through the tub. For this, the tub is equipped with a respective ball bearing to support the shaft. While the bearing is made of metal, most often steel, the remainder of the tub is made of plastic. At the outside of the tub, the shaft is typically provided with a pulley to connect the shaft to a motor via a belt. Upon operation of the motor, the pulley, via the belt, exerts a torque onto the shaft to rotate the drum. A typical revolution speed is within a range from 600 rpm to 1400 rpm.

[0003] For example, WO 2007/115894 A1 discloses a tub for a clothes washing-machine, in particular of the domestic type, which houses a rotating drum within which the washing load is placed, said washing tub consisting of a peripheral cylindrical housing formed by a tub front section and a tub rear section which are joined at their respective plastic material edges, enclosing the drum in their interior. The tub rear section holds a respective ball bearing to support a shaft.

[0004] A critical zone is the joint between the plastic material of the tub and the bearing, in particular a bearing housing. The plastic cover may have been formed around the bearing by injection moulding. In particular during a spin cycle, the bearing heats up so that thermal expansion and contraction of the bearing and the surrounding plastic occurs in different magnitude. This may lead to damage of the plastic and / or of the interface between metal and plastic, mainly because of the induced stress and subsequent delamination along the interface. This in turn may render the washing machine unusable.

[0005] To prevent such overheating problems, there exist two methods, namely overdimensioning the bearings or using a high-temperature-resistant plastic material, in particular when employing high-performance washing machines (1200 and 1400 rpm). Overdimensioning the bearing leads the maximum temperature they attain to being restricted within a moderate range, e. g., approximately between 60 and 70°C. Utilization of a specific plastic material (e. g., PP, PEEK, etc. with reinforcement and / or temperature resistant filler materials like talc, fibres, etc.) achieves a reduction in the differential contraction effect together with the retention of an improved mechanical fixing also for a high temperature. However, both techniques lead to high costs.

SHORT DESCRIPTION OF THE INVENTION

[0006] It is the object of the present invention to provide an inexpensive possibility to reduce heating of a bearing that supports a pulley-driven shaft, and in particular to provide an inexpensive possibility to prevent thermally induced damage at a bearing zone of a tub of a washing machine, in particular caused by a spinning cycle.

[0007] This object is achieved by a pulley, a washing machine (single washing machine or washer-dryer) a method according to the respective independent claims.

[0008] The pulley comprises at least one vane. Thus, the pulley, upon rotation, creates an air flow that may be directed to a heated zone, in particular to a bearing. The design of such a pulley is inexpensive compared to using an oversized bearing or reinforced plastic or the use of a separate fan fixed to the shaft. This object is further achieved without a need to re-design, in particular a need for an enlarged design dimension.

[0009] In other words, the pulley (which transmits torque to the shaft and which is a passive transmission element), by means of a vane / vanes, generates an air-cooling effect upon rotation.

[0010] Advantageously, the pulley comprises a plurality of vanes to increase air flow.

[0011] Advantageously, the plurality of vanes is provided around the pulley's rotational axis to create an even air flow.

[0012] The vanes may be located as it is most useful for the intended purpose. Advantageously, the plurality of vanes is arranged in a rotational symmetry around the pulley's rotational axis.

[0013] The vane may be of any useful shape. Advantageously, a vane has a substantially triangular shape for easy manufacturing while creating a relatively strong air flow with low or no propeller noise.

[0014] Advantageously, a number of vanes is between 8 and 24.

[0015] Advantageously, the pulley may be made from a plastic material.

[0016] Then, advantageously, the pulley is made by injection moulding.

[0017] Advantageously, the pulley's plastic material comprises a plastic base and reinforcement filler, e. g. talc and / or fibre (glass fibre, ceramic fibre etc.).

[0018] Advantageously, the pulley may be made from metal sheet.

[0019] Then, advantageously, at least one vane is formed by sheet metal forming of the pulley, in particular by partial cutting and subsequent bending the cut area out of its original position.

[0020] Advantageously, the at least one vane is designed to create a flow of air along a rotational axis of the pulley upon operation / rotation of the pulley. This airflow is particularly useful for cooling down a bearing supporting a shaft that is fixed to the pulley.

[0021] The washing machine (including one out of a single washing machine and a washer-dryer) comprises a pivoted drum for holding clothes wherein the drum is positioned within a tub, the drum being functionally connected (i. e., directly connected or via intermediate elements) to a shaft that passes through a bearing, preferably ball bearing, of the tub. A pulley is directly or indirectly (e. g., via a bushing) fixed to the shaft outside the tub. The pulley comprises at least one vane to create, upon rotation, a flow of air to or from the bearing.

[0022] The advantages stem from the utilization of a passive element (the pulley) as a cooling element to cool the bearings and the joint plastic / metal (cast shell) zone while retaining its function of torque transmission. In this manner, by reducing the temperature, bearings may be employed without concern for heat generation. In addition, plastic materials may be employed without a requirement for fibre or mineral fillers for temperature resistance; this is particularly attractive since the drum is mostly made from one mould.

[0023] It may be advantageously if the pulley, upon rotation, creates a flow of air to the bearing. The pulley thus acts as an air-compression element that draws air from the exterior and forces it towards the tub/bearings zone.

[0024] Alternatively, it may be advantageously if the pulley, upon rotation, creates a flow of air from the bearing. The pulley thus acts as a low pressure-generating element that draws air from the tub / bearings zone such that cool air flows in through the sides towards the bearings zone.

[0025] Advantageously, the pulley is a pulley as described above.

[0026] The washing machine thus comprises a pulley which transmits torque to the drum (currently a passive transmission element) such that by means of a vanes / vanes an air-cooling effect is generated particularly in the spinning phases.

[0027] The pulleys are not restricted for use in a washing machine or any other household appliance but may also be utilized in any other type of apparatus comprising a shaft. They are particularly useful for cooling a bearing of the shaft and especially for cooling a joint bearing / surrounding material zone wherein the surrounding material may or may not be plastic.

[0028] The method for cooling a region in the vicinity of a shaft fitted with a pulley, wherein the pulley comprises at least one vane, comprises the step of rotating the shaft pulley to create a flow of air by the at least one vane.

[0029] Advantageously, the flow of air is created substantially along a rotational axis of the pulley.

[0030] Advantageously, the region to be cooled comprises a bearing supporting the shaft.

[0031] Advantageously, the shaft drives a drum of a clothes washing machine.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To complement the description which is to be made below, and in order to better understand the invention, a set of schematic drawings is attached to this specification. Same numerals may be used for same or like elements throughout the figures.

FIG 1

shows a side view of the profile of a washing tub with a drum inserted into its interior, and elements of a drive train to spin the drum;

FIG 2

shows a slanted view of a pulley according to a first embodiment of the invention for use with a washing machine of FIG 1;

FIG 3

shows a slanted view of a pulley according to a second embodiment of the invention for use with a washing machine of FIG 1;

FIG 4

shows an enlarged cut-out view of FIG 1 in the vicinity of the drive train with an indication of a cooling air flow according to a first embodiment of the drive train;

FIG 5

shows an enlarged cut-out view of FIG 1 in the vicinity of the drive train with an indication of another cooling air flow according to a second embodiment of the drive train.

DESCRIPTION OF THE PREFERED EMBODIMENT

[0033] In the following, preferred embodiments of the invention are described at greater detail. It should be understood that the description of the preferred embodiments is not intended to limit the invention.

[0034] FIG 1 shows a schematic section of a tub 1 for a clothes washing-machine, in particular of a domestic type, which houses a rotating drum 2 within which the washing load is placed. The washing-machine is of the front-loading type, with an opening 10 in the tub front section 3 for the insertion of the washing load. The tub 1 is manufactured from plastic by injection moulding and comprises a peripheral cylindrical housing made from two parts, a tub front section 3 and a tub rear section 4 which are joined along their respective open edges 31, 41, enclosing the drum 2 in their interior, by means of fusion welding of the plastic materials of the edges 31, 41, producing a weld bead 5a between the tub front section 3 and the tub rear section 4. The system for closing the same by welding is the system of closure by vibration. The edges 31, 41 are joined along at least two joining lines 51, 52, forming a chamber 5 between the edges 31, 41 along the perimeter of the weld bead 5a.

[0035] At the centre of the tub rear section 4 is arranged a metallic ball bearing 6. The remainder of the tub rear section 4 is formed by a plastic region 8 surrounding the bearing 6. The ball bearing supports a shaft 7 that drives the drum 2. Outside of the tub 1, a pulley 9 is fixed to the shaft 7. The washing machine further comprises a motor 10. A rotation of a driveshaft 11 of the motor 10 is transmitted to the pulley 9 by a belt 12. The driving mechanism 6,7,9-12 is also referred to as a drive train to rotate the drum 2.

[0036] FIG 2 shows a wheel-like pulley 9 having a through hole 13 for inserting a shaft directly or, e. g., via a bushing. At its circumference 14, the pulley 9 guides the belt and may comprise a groove between two flanges, as it is well known in the art. The pulley further comprises twelve air guiding means each in turn comprising an opening 15 that is at least partly overlapped (if seen from the front or rear) by a vane 16. In the present case, the vane 16 and the opening 15 have the same form of an isosceles triangular with perpendicular bisector of the smaller side roughly aligned in the radial direction. One of the longer sides connects the vane 12 to the rest of the pulley 9. If the pulley 9 is driven by the belt, it rotates with the shaft around the rotation axis R. The pulley 9 is made from plastic material, in particular comprising PP.

[0037] FIG 3 shows a pulley 17 that in comparison to the embodiment of FIG 2 has larger openings 15 and vanes 17.

[0038] In the present case, a rotation of the pulley 9 or 17 (in the clockwise direction in the case of FIG 2 and FIG 3) causes cooling air 18 to be drawn through the openings 15 such that an air flow is created that is substantially directed along the rotation axis R (from front to rear in the view of FIG 2 and FIG 3).

[0039] FIG 4 shows an embodiment of the drive train wherein the pulley 9 or 17 is adapted and arranged such that the bearing 6 is located in the direction of the blown out air 18 (the air flow along the rotation axis R). Subsequently, the air flow 18 cools the bearing and its surrounding by being frontally directed onto the zone to be cooled.

[0040] FIG 5 shows another embodiment of the drive train wherein the pulley 9 or 17 is adapted and arranged such that the bearing 6 is located at the side of the pulley 9,17 where air 18 is drawn in. The drawn-in air flow 18 cools the bearing 6 and its surrounding by being moved substantially along the surface of the zone to be cooled. For both embodiments, a short distance from the pulley 9,17 to the area to be cooled is advantageous.

[0041] The invention is not restricted to the shown embodiments. For example, the number and form of the vanes (and openings) may vary. The pulley may be used within other types of machines. The pulley may be made from another plastic base material than PP, e. g., PEEK. The pulley may contain an appropriate amount of reinforcement fillers, e. g. glass fibers of 15 vol % to 30 vol %. The pulley may also be made from metal, e. g., steel. The vane may have different form and positions, e. g., different opening angles. The connection to the shaft (or the bushing) may be of any type, e. g., welding, gluing, screwing, clamping etc. The air flow does not have to be parallel to the shaft supporting the pulley but may - depending on, e. g., the form and position of the vane - be blown in or drawn from a direction that comprises a finite angle with the rotation axis.

LIST OF REFERENCE NUMERALS

[0042] 

1

tub

2

drum

3

tub front section

4

tub rear section

5

chamber

5a

weld bead

6

bearing housing ('hub')

6A

side surface

6B

front surface

6C

rear surface

6D

inner surface

7

shaft

8

plastic tub region

9

pulley

10

motor

11

driveshaft

12

belt

13

throughhole

14

circumference

15

opening

16

vane

17

pulley

18

cooling air

Claims

1. A pulley (9;17), characterized in that it comprises at least one vane (16).

2. The pulley (9;17) according to claim 1, characterized in that said at least one vane (16) has a substantially triangular shape.

3. The pulley (9; 17) according to claim 1 or 2, characterized in said at least one vane (16) is a plurality of vanes (16) provided around a rotational axis (R).

4. The pulley (9;17) according to claim 3, characterized in that a number of vanes (16) is between 8 and 24.

5. The pulley (9;17) according to any of the preceding claims, characterized in that said pulley (9; 17) is made from a plastic material.

6. The pulley (9;17) according to any of claims 1 to 4, characterized in that said pulley (9;17) is made from metal sheet and in that at least one vane (16) is formed by sheet metal forming.

7. The pulley (9;17) according to claim 6, characterized in that said at least one vane (16) is formed by partial cutting and subsequent bending the cut area out of its original position.

8. The pulley (9;17) according to any of the preceding claims, characterized in that said at least one vane (16) is designed to create a flow of air (18) along a rotational axis (R) of said pulley (9; 17) upon rotation of said pulley (9; 17).

9. A washing machine, comprising a pivoted drum (2) for holding clothes wherein the drum (2) is positioned within a tub (4), said drum (2) being functionally connected to a shaft (7) that passes through a bearing (6) of said tub (4), wherein a pulley (9;17) is fixed to said shaft (7) outside said tub (4), characterized in that said pulley (9;17) comprises at least one vane (16) to create a flow of air at least to or from said bearing (6).

10. The washing machine according to claim 9, characterized in that said pulley (9; 17) is a pulley (9; 17) according to any of claims 1 to 8.

11. A method for cooling a region in the vicinity of a shaft (7) fitted with a pulley (9; 17), characterized in that the pulley (9;17) comprises at least one vane (16) and in that the method at least comprises the step of rotating the shaft pulley (9;17) to create a flow of air (18) by the at least one vane (16).

12. The method according to claim 11, characterized in that the flow of air (18) is created substantially along a rotational axis (R) of the pulley (9;17).

13. The method according to claim 11 or 12, characterized in that the region to be cooled comprises a bearing (6) supporting the shaft (7).

14. The method according to any of claims 11 to 13, characterized in that the shaft (7) drives a drum (2) of a clothes washing machine.

Drawing