Clothes dryer

A clothes dryer which comprises a housing, a rotatable drum for receiving the clothes and a bearing for rotatably receiving the drum in the housing. In order to protect the bearing from overheating, a cooling air device for cooling the bearing is provided.

BACKGROUND OF THE INVENTION

This invention relates to a dryer with a rotary drum for receiving laundry and a bearing for rotary mounting of the drum.

Dryers are known in which a drum is arranged horizontally for receiving laundry, and is pivoted by pivot bearings. The pivot bearings are subject to high thermal loads which negatively influence the reliability and life of the bearings, particularly when they are arranged adjacent to ducts conveying hot process air.

SUMMARY OF THE INVENTION

The object of the invention is to make available a dryer that operates reliably, with a drum that is swivelled by means of a bearing.

This object is achieved by the characteristics in claim1. Advantageous embodiments and further developments of the invention are described in the dependent claims.

A dryer has a housing in which a drum for receiving laundry is swivelled by means of a bearing. To ensure that the bearing operates reliably at all times, a cooling device is provided for cooling the bearing. This enables the maximum thermal expansion of the drum bearing components to be reduced and hence also the mechanical load. Furthermore, the lubricant provided for the bearing is subjected to lower loads because of the cooling of the bearing if the bearing is operated at lower temperatures. Moreover, there is reduced risk of the lubricant in the bearing becoming fluid at low temperatures and escaping. This increases the life and reliability of the bearing, and hence of the dryer.

In an advantageous embodiment the cooling device comprises means for improving the radiation and/or convection of heat from the bearing or adjacent to the bearing. In particular, cooling faces may be provided which are connected thermally and conductively to the bearing. Such cooling faces may be formed by a suitably large surface design of the bearing bracket or by providing cooling ribs.

In an advantageous embodiment the cooling device has a device for conveying cooling air, preferably ambient air, to the bearing. This makes available active cooling with which defined thermal conditions can be created on the bearing.

In an advantageous embodiment a fan is provided for conveying process air through the drum and/or for conveying cooling air for a condenser, wherein the fan serves as a device for conveying cooling air to the bearing. This also makes it possible to make use of fans that are already installed in the dryer, either a fan for conveying process air or a fan for conveying cooling air to a condenser, as a cooling device for cooling the bearing.

In an advantageous embodiment a process air conduit is provided, wherein a section of the process air conduit and/or the drum is loaded with a vacuum due to the conveying action of the fan, and forms a vacuum space. Furthermore, a cooling conduit is provided between the vacuum space and the bearing so that air is sucked in adjacent to the bearing in the form of ambient air and conveyed by the cooling conduit as spent air to the process air.

In an advantageous embodiment the bearing has a bearing bracket which is secured to the housing, and a process air duct has an air distribution hood adjacent to the bearing which covers the process air inlet holes into the drum, wherein a cooling air conduit is formed between the air distribution hood and the bearing bracket, in the form of an annular gap, so that a cooling air flow is able to flow through the annular gap into the process air duct in the form of ambient air. The bearing is flushed on all sides with cooling air through the annular gap and is therefore effectively cooled.

In an advantageous embodiment a process air conduit is provided, wherein a section of the process air conduit and/or the drum is loaded with excess pressure by the conveying action of the fan, and forms an excess pressure space. Furthermore, a cooling conduit is provided between the excess pressure space and the bearing, so that some of the conveyed air is fed to the bearing in order to cool the bearing.

In an advantageous embodiment the process air conduit is provided as a circuit with a condenser which is cooled by a cooling air flow. Some of the cooling air flow is branched and fed via a cooling air conduit to the bearing in order to cool the bearing.

In an advantageous embodiment the cooling conduit is dimensioned so that the quantity of cooling air can be predetermined.

as a modified first or second exemplary embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According toFIGS. 1 and 2a first exemplary embodiment of a dryer is represented in the form of an exhaust dryer. The dryer has a housing1, a drum2mounted in housing1, a front end plate3, a feed door4arranged in the front end plate3and a lint screen5fitted in the lower section of front end plate3. Drum2is mounted in the front section above rollers6arranged on the front end plate3and in the rear section above a central bearing9arranged on rear wall8of drum2, which bearing is in turn secured by a bracket10to rear wall11of housing1. Drum2is rotated about horizontal axis14by a motor12and a belt13. The dryer has a process air conduit15which, in this exemplary embodiment, comprises an inlet opening16, an inlet duct17, an air distribution hood18connected to it, which covers process air inlet holes19arranged on rear wall8of drum2, a process air outlet grid20, lint screen5and an outlet duct21, with a fan22. A heater23is also arranged in inlet duct17. The process air flows in arrow direction24from the ambient atmosphere into inlet opening16via inlet duct17, heater23, air distribution hood18, drum2, process air outlet grid20, lint screen5, outlet duct21and fan22back into the ambient atmosphere. Air distribution hood18is sealed against rear wall8of drum2by means of a rear seal25. Upstream from fan22, a vacuum space is formed, in particular in drum2and air distribution hood18.

Bearing9is shown in more detail inFIG. 2. Bearing9has a shaft26which is secured to rear wall8of drum2, and a spherical bearing member27, which is preferably manufactured from oil saturated sinter material. Bearing member27has a hole28in which shaft26is able to rotate. Furthermore, bearing9has two seals29. Bracket10has an outer half-shell30and an inner half-shell31, between which the spherical bearing member27is retained. Between outer half-shell30and inner half-shell31is arranged a conical spring element32, which restricts the bearing member27from also rotating. Spherical bearing member27is able to perform swivel movements transversely to the horizontal center line14, to compensate for an angular displacement of drum2. The central section of air distribution hood18is secured on the inside of bracket10, parallel with bracket10, forming an annular gap33. Annular gap33is formed by spacer members34, which are formed on air distribution hood18.

Outer half-shell30and inner half-shell31are each manufactured from a steel sheet which is capable of transferring heat away from the bearing and discharging heat by thermal radiation and convection. However, since there is hot process air between rear wall8of the drum and air distribution hood18, bearing9is subjected to considerable heating. Due to the provision of annular gap33between bracket10and air distribution hood18, a cooling conduit is formed between the vacuum space in the drum2and bearing9, wherein cool ambient air is sucked into the process air as so-called spent air passing through annular gap33on bearing9. In particular, fan22, which is responsible for building up the vacuum in drum2, therefore serves as a conveying device. Because of the formation of the relatively long, parallel annular gap33, a large surface is made available for heat transfer from the hot bearing to the cooling ambient air flowing through annular gap33. A very simple device is therefore made available for cooling bearing9using the other devices, such as fan22of the dryer.

FIGS. 3 and 4show a second exemplary embodiment of the dryer in the form of a condensation dryer. Only the differences relative to the dryer designed as an exhaust dryer are shown below inFIGS. 1 and 2. Process air conduit15is designed as a closed circuit in which a condenser35is also inserted, which condenser is normally designed as a cross flow or counterflow condenser, and is cooled by means of a condenser cooling air flow36. Condenser cooling air flow36is produced in a condenser cooling air conduit38by an additional fan37, which can be mounted on the same drive shaft as fan22. A cooling air conduit41, which opens into a space39between rear wall11of housing1and bracket10, is branched off from the section of condenser cooling air conduit38on the pressure side. As shown in more detail inFIG. 4, the cooling air flows into space39, and through openings40formed in the bracket into annular gap33between bracket10and air distribution hood18.

FIG. 5shows a modification both for the exemplary embodiment according toFIGS. 1 and 2and for the exemplary embodiment inFIGS. 3 and 4. In this modification the direction of the cooling air flow according toFIG. 4is reversed, and cooling air is sucked off through cooling air conduit41from space39through annular gap33. Here the suction may take place on cooling air conduit41either via the suction side of condenser cooling air conduit38(FIG. 3) or via the suction side of process air conduit15, upstream from heater23shown inFIG. 1.

Alternatively to the embodiment shown inFIG. 1, fan22may be arranged upstream from drum2, so that an excess pressure prevails in the process air conduit before drum2, and also in drum2. Some of this air upstream from drum2, and also upstream from heater23, may be fed through a branch conduit to bearing9in order to cool bearing9.