EP1673501A2

EP1673501A2 - Plastic container for washing machines or tumble dryers

Info

Publication number: EP1673501A2
Application number: EP04787052A
Authority: EP
Inventors: Otto Kaulbersch; Ute Kreuziger; Ulf Sauerwald
Original assignee: Wirthwein AG
Current assignee: Wirthwein AG
Priority date: 2003-09-30
Filing date: 2004-09-29
Publication date: 2006-06-28
Also published as: WO2005033400A3; WO2005033400A2; DE10345848A1

Abstract

The invention relates to a plastic container for a washing machine or a tumble drier, in which a drivable drum comprising an essentially horizontal shaft can be mounted. Said container comprises a wall with at least one front wall provided with a plurality of radial and concentric reinforcing ribs, the bearings having a seat in a housing that is positively arranged in the front wall. The invention also relates to the specific use of a glass-fibre reinforced polyamide for bearings of a drum in washing machines or tumble dryers, and to the specific use of a high tensile strength, glass-fibre reinforced polyamide for the bearing housing of a drum in washing machines or tumble dryers. The front wall in the region of the housing, that is embodied as a bush with a shoulder, is provided with a plurality of reinforcing ribs extending concentrically to the axis of the shaft of the drum and a plurality of reinforcing ribs extending radially away from the axis, said reinforcing ribs being used to support the separately produced bearing-receiving housing that can be screwed to the front wall. The housing together with a complementary reinforcing rib of the front wall forms a press fit at least in the region of the seat of the rolling bearing or the bush part.

Description

Plastic tub for washing machines or dryers

description

The invention relates to a plastic tub for a washing machine or dryer, in which a drivable drum with a substantially horizontal shaft can be stored, comprising a wall with at least one end wall, which is integrally provided with a plurality of radially and concentrically extending reinforcing ribs, the bearings have a seat in a housing that is arranged in a form-fitting manner in the end wall and the special use of a GRP polyamide for storing a drum in washing machines or dryers.

A tub of this type, which encloses a rotating drum for the laundry to be treated, usually consists of a cylinder with a substantially horizontal axis, which has a jacket and two end walls. In the case of the front loaders, the opening for filling and removing the laundry is provided on the front wall of the tub, while the seats for the bearings of the drum shaft are installed in the rear wall; in the top loaders, the opening for the laundry is provided on the jacket and the bearings are preferably arranged on the front and rear walls.

The lifespan of a washing machine is usually 10 to 20 years. Therefore, a tub has to be designed in such a way that it fulfills functional requirements such as durability against the mechanical loads transmitted by the drum, water resistance and corrosion resistance for such a long period of time. Furthermore, the suds container must be suitable for production and recycling, both from a strictly technical and economic point of view, when the washing machine has reached the end of its service life. DE 298 21 140 U1 discloses the use of a tub made of plastic by injection molding. It is manufactured in highly automated manufacturing processes and also allows recycling. A tub of this type is made using a single plastic, apart from that

Connecting screws between its various parts and some.

Insert parts such as the waterproofing rings and the seats for the bearings of the

Drum shaft.

To ensure that the tub is adequately stable, the wall with the seat for the bearings is not flat, but instead has one-piece reinforcement elements with the wall, which are produced during injection molding. Polypropylene reinforced with glass fibers is used as the material, the reinforcing elements being designed both as radially arranged ribs with crossing points and concentrically extending around a bearing hub.

This known construction of the tub alone is not enough, strong and complicated bending-torsional loads like those that occur in the most modern machines, in which the spin speed of the rotating drum can even be over 1500 revolutions per minute with a payload of laundry of more than 5 kg ; imbalances occur. These are met with an integrally injected metal bearing hub, while on the other hand, recesses are made in the wall around the bearing hub to save weight.

EP 0 219 115 B1 proposes integrating the necessary ball bearings and their spacer rings in a multi-step, repeated injection molding process into the washing container in a glass fiber reinforced polyester hub of a plastic washing container. This manufacturing process is naturally complex and costly.

The document DE 100 40 319 C1 provides an intermediate route in which a tub with a hub, a first ball bearing integrally injected therein and a further ball bearing has been inserted into a partial bearing housing which is connected to the hub by gluing or welding. For top loaders, it is known from DE utility model G 80 24 841.5 that a bearing housing with bushing and contact collar made of glass fiber reinforced polypropylene, polyacetal or polyamide can be positively arranged in a container wall made of glass fiber reinforced polypropylene for ball bearings by means of a bayonet lock. The design according to the document DE 31 42 295 A1 is similar, the ball bearing here being pressed into the housing.

Since in both cases the eccentrically designed bearing housing can be rotated to adjust the belt tension of the rotary drive, the bearing housing has corresponding play and is also only partially durable due to the large number of fastening parts for the rotating shaft and the drum.

Starting from the first-mentioned prior art, the invention is based on the problem of proposing an improved suds container for washing machines or dryers with bearings for roller bearings, which is simpler and cheaper to produce, but nevertheless guarantees the highest functional performance mentioned and both for front loading machines and for Top loading machines are suitable.

The problem is solved according to the invention by the features of claims 1 and 8. Further developments of the invention are described in the dependent claims.

In the case of a generic tub, the features according to the invention include, in a first solution, an end wall in the area of the housing which is provided in one piece with a plurality of reinforcing ribs which extend concentrically to the axis of the drum shaft and which extend radially away from the axis and which serve to support a e.g. Can be attached to the end wall by means of screws and manufactured separately

Serve housing for receiving at least one rolling bearing. Parts of the housing should preferably press / under friction / shrink fit on at least parts of the ribs, on a concentric rib under ring tension. The outside of the housing and the complementary reinforcement rib of the end wall in the opening for the seat of the drum shaft should form a press fit at least in the area of the seat of the roller bearing or the bushing part, so that excellent power transmission from the drum shaft via the bearings and the housing to the end wall is possible is.

The concentric and the radial reinforcing ribs have crossing points in the area of the housing, in which there are at least three or more through holes for screws on at least one of the concentric reinforcing ribs, if the load or the deformation resistance of the housing so requires, which pass through the housing in the end wall be screwed in and thus fix the housing axially next to the frictional connection by means of a press fit, while it is held in a radially positive manner by the concentric rib.

The plastic tub should be made of softer and cheaper material than the housing, preferably made of glass fiber reinforced polypropylene, while the housing is made of polyamide reinforced with about 40 - 70% filling of glass fibers, preferably nylon with at least 50% glass fiber filling.

The second solution of the invention relates to the use of polyamide reinforced with at least 50% glass fiber filling and having a tensile strength of greater than 150 N / mm ² for bearing housings made separately by injection molding and which can be pressed into a front wall of a tub made of softer plastic for roller bearings which can be used therein a shaft of a drivable drum in a washing machine or dryer. The bearing is preferably pre-assembled before the housing is pressed into the tub. For a more detailed explanation of these features and their advantages over the closest prior art, an embodiment of the invention is described with reference to the accompanying drawings.

Show it:

Figure 1 is a perspective view of the rear wall of a plastic tub for a top loading washing machine.

Figure 2 shows a view of the same part of the tub of Figure 1, but with the bearing housing inserted;

Fig. 3 is a view similar to Fig. 1, 2, but with a partial section through the prepositioned parts for assembly.

In the following, identical reference symbols are used for identical or functionally identical functional parts.

1 shows an embodiment of the invention, a section of a tub, an end wall 1 with the storage area for the shaft of a washing drum or dryer drum. In front loaders one has such an end wall in which the drum shaft is mounted twice, while in top loaders two end walls of the washing container or lye container arranged on both sides of the drum, each with a bearing, preferably a roller bearing, usually ball bearings, are provided for the shaft.

The shaft, not shown, with axis 7 is arranged in the opening 71. The breakthrough is provided according to the invention with concentrically arranged reinforcing ribs or inner rings 2, 3, 4, 5 and, if necessary and with a corresponding load, also with further ribs such as rib 6 (FIG. 3).

Starting from the rib 5, radially reinforcing ribs 8, 10, 12, 14, 16 extend over the end wall. Each of these ribs 8, 10, 12, 14, 16 forms with the middle concentric reinforcing rib 3 a crossing point. A bore 31-36 with a thread is made in at least three of these crossing points for receiving a fastening screw (not shown) for a bearing housing 100 (FIG. 2). These bores are designed in the manner of a screw dome and preferably extend over most of the rib depth (FIG. 3). Further wall-reinforcing ribs 11 extend radially outward from the outermost concentric reinforcing rib 4. One or more parts of a concentric rib, here reinforcing rib 3, have a mounting nipple 30 for precise positioning of the bearing housing.

2, 3 show the housing 100, designed as a bushing 102 with collar 101, for a roller bearing 23 in the preassembled state in the desired position. In the case of front loaders, two bearings would be arranged at a distance from one another, in which the shaft that holds the drum flying is mounted. The housing is exactly positioned by mounting nipple 30, which projects into an opening 130 of the housing. Recesses 111 - 116 serve to save weight and increase the flexibility of the collar 101, which is fixed by screws, inserted into the holes 132 -136, of which at least three are arranged on the circumference of the collar of the housing 100. The holes are aligned with corresponding threaded bores 32-36 in the end wall 1. When the screws are fixed, the collar is supported on the rib parts 161, 162 of the rib 16 and the other ribs next to the bores 32-36. A further indirect support is provided by the housing 100 at the end of the socket part 102 on the rib 2, a sealing washer 21 and an O-ring or another seal 22 being arranged between the end 106 of the socket and the rib 2.

The bushing 102 is inserted by shrinking into the end wall 1, which has been heated to, for example, 70 ° C., so that it contacts the rib 2 in many cases under ring tension before the screws (not shown) fix the housing, which is now immobile in the radial direction, in a positive manner in the axial direction. Instead of shrinking there is also a mechanical one Pressing in the housing or a combined heating / shrinking and pressing in possible. The decisive factor here is the combination of materials chosen by the specialist, their strength and elasticity. Ultimately, the bearing 23 is press-fitted with its outer ring, manufactured as described for the bushing, to the bushing 102 in the passage 71 for the shaft of the drum. For this purpose, the wall thickness of the socket is designed to be correspondingly thick, while the collar 101 is designed to be thinner and more flexible for effectively bracing the housing. For manufacturing reasons, slight radii are applied between the collar and bushing of the housing 100 and the angle between the collar surface and the bushing inner surface 105 can be slightly greater than 90 °. The flank angle of the surface 105 and the surface of the rib 5 should be identical. The slightly inclined surface arrangement facilitates the molding of the parts from injection molds in which both the housing 100 and the end wall 1 are injection molded and the pressing of the parts into one another or the bearing 23 into the bushing 102.

A material that is harder and stiffer than the end wall is used as the material for the housing. Tests have shown that a polyamide is most suitable for the housing 100, with about 50%, generally 40-70% glass fibers being added to the plastic for reinforcement. The material can be easily processed by injection molding. The polyamide used, a nylon or the like, is available as a raw product from ASAHI KASAI, Hampshire, UK under product names such as Thermofil, types 90G50 or AMC 50 or AMG 50. Contrary to usual

Tensile strengths for PA building materials from 15 - 75 N / mm ² , this PA 66 has a tensile strength of about 200 N / mm ² .

The design according to the invention was far superior to previous designs in long-term tests under practical conditions in a washing machine. The advantages of the construction described can be summarized as follows:

The grid-like structure in the bearing area, which is formed by the concentric ribs that cross with the radial ribs, is robust enough to withstand all mechanical loads that are transferred from the rotating drum to the tub while the washing machine is in operation. The decisive factor is probably the direct application of force from the drum shaft via the pressed-in ball bearing, via the pressed-in and screwed, i.e. frictionally and positively fastened, housing into the end wall of the tub.

Claims

claims:

1. Plastic tub for a washing machine or dryer, in which a drivable drum with a substantially horizontal shaft can be stored, comprising a wall with at least one end wall, which is provided in one piece with a plurality of radial and concentric reinforcing ribs, the bearings a seat have in a housing which is arranged in a form-fitting manner in the end wall, characterized in that the end wall (1) in the region of the housing (100-102), which as a bushing (102) with collar (101)

Plastic material is formed integrally (14, 8, 10, 12 ^', 16) provided with a plurality of concentric (2, 5) to the axis (7) of the shaft of the drum and a plurality of radially away from the axis extending reinforcing ribs for supporting of the separately manufactured housing (100) which can be fastened on or in the end wall are suitable for accommodating at least one rolling bearing (23), the housing (100) on its socket part (102) having a complementary reinforcement rib (5) in the end wall (1 ) forms a press fit at least in the area of the seat of the rolling bearing or the bushing part.

2. Plastic tub according to claim 1, characterized in that the concentric (3) and the radial (8, 10, 12, 14, 16) reinforcing ribs have crossing points in which there are at least three holes on at least one concentric reinforcing rib (3) (33) for the screws for fastening the housing (100) to the end wall (1).

3. Plastic tub according to claim 1 or 2, characterized in that the outside of the housing (100) on the ribs (161, 162, 2, 5) of the end wall (1) abuts in many cases.

4. Plastic tub according to one of the preceding claims, characterized in that the housing (100) made of reinforced polyamide and the tub (1) is made of a softer material than the housing (100), preferably of polypropylene reinforced with glass fibers.

5. Plastic tub according to one of the preceding claims, characterized in that the housing (100) consists of polyamide reinforced with glass fibers, preferably of nylon with at least 50% glass fiber filling.

6. Plastic tub according to one of the preceding claims, characterized in that the roller bearing (23) with press fit

Surface (105) is inserted into the socket (102).

7. Plastic tub according to one of the preceding claims, characterized in that the collar (101) of the housing (100) has a smaller wall thickness than the socket part (102).

8.Use of polyamide reinforced with at least 50% glass fiber filling with a tensile strength greater than 150 N / mm ² for bearing housings (100-102) for roller bearings (23) which are manufactured separately by injection molding and can be pressed into an end wall (1) of a tub ) a shaft of a drivable drum in a washing machine or dryer.

9. Use according to claim 8, characterized in that one or two spaced roller bearings (23) in the bearing housing

(100) are pressed in and / or shrunk in before the bearing housing (100) is pressed into the end wall (1) and / or shrunk in.