GB2288457A

GB2288457A - Condensate removal from an appliance

Info

Publication number: GB2288457A
Application number: GB9507237A
Authority: GB
Inventors: Reinhard Wiethe
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-04-11
Filing date: 1995-04-07
Publication date: 1995-10-18
Anticipated expiration: 2015-04-07
Also published as: FR2718494A1; FR2718494B1; GB9507237D0; ITMI950684A1; IT1277183B1; GB2288457B; ITMI950684A0

Abstract

A laundry drier has a condensate pump, which is drivable by a drive motor (8) of a laundry drum, and a condensate collecting container (1) arranged below a laundry drying chamber, the container being hydraulically connected with a pump chamber (2) of the pump. A drive shaft (5) of an impeller wheel (4) of the pump carries a driven wheel (6), which is movable in direction towards a drive wheel (7) of the motor (8) and mechanically connected with a float (12), which is guided in a float chamber (11) hydraulically connected with the collecting container (1). When condensate in the container (1) reaches a predetermined level (II), the wheel (6) will be brought by the float into engagement with the wheel (7). Thus the pump is active only when a greater quantity of condensate has been collected. Different forms of floats and arrangements of float and pump chambers have been disclosed. <IMAGE>

Description

CONDENSATE REMOVAL FROM AN APPLIANCE 2288457 The present invention relates

to an appliance, for example a laundry drier, and has particular reference to removal of condensate from a condensate collecting chamber of the appliance.

A condensate pump for condensate removal from a laundry drier is known from German published specification 21 35 397. Although an impeller wheel condensate pump is not directly described therein, the use of an impeller wheel pump is evident when, as stated, the pump is connected directly with the shaft of a drive motor and fan. Such a drive of the condensate pump allows the pump to co-rotate uninterruptedly for as long as the laundry drum is driven by the drive motor. However, since condensate does not arise in a correspondingly large quantity, the pump is frequently idling, consumes drive energy and is the source of unnecessary noise.

is There is thus a need for a condensate removal arrangement in which pumping is carried out only when an adequately high condensate surface level is present in a collecting chamber, so that the development of undesired noise can be largely avoided. Preferably, the use of surface level controls of doubtful safety, which would lead to an appreciable cost expenditure, shall be avoided.

According to the present invention there is provided an impeller wheel condensate pump which is drivable by the drive motor of a laundry drum, for a laundry drier with a condensatecollecting chamber which is arranged below a laundry drying chamber and, hydraulically connected with a pump chamber, characterised in that a drive input shaft of the impeller wheel has a driven gearwheel which is movable in direction towards a driven gearwheel of the drive motor and connected mechanically with a float which is guided in a flow chamber connected hydraulically with the collecting chamber.

The float can automatically raise the driven wheel into the engagement with the drive wheel when the condensate surface level in the collecting container is high enough to raise the float, including the mass of the driven gearwheel and optionally also of other pump parts loading the float. Then, an adequate quantity of condensate is also present and can be sucked away without slurping noises by the pump. Moreover, the overflow of condensate from the collecting chamber is excluded because the float always brings the driven wheel of the pump into engagement with the drive wheel of the motor at the right time. A special electrical device for monitoring surface level is not essential. is In a particularly advantageous embodiment, a pump housing, which defines the pump chamber and is provided with a bearing for the drive shaft, is fixedly connected with the float. In this case, the entire pump housing together with the float is raised for the coupling of the pump drive shaft with the drive motor of the laundry drum. 20 Advantageously, the float consists of a foamed synthetic material with closed cells, preferably polystyrol. Such a float is cheap to manufacture and of stable shape. In particularly advantageous manner, the float has a step function in its travel shortly before the engagement of the driven wheel with the drive wheel. This allows prevention of insecure engagement, by which the wear of the wheels could' become unnecessarily high, at the instant of interengagement of-the two wheel s. This feature will preferably be used in the case of wheels which transmit drive by way of friction. - The step function can be provided in particularly simple and reliable manner by a spring, which holds down the float and has a step function in its characteristic, or by an armature of an electromagnet, which armature can be switched on by an electrical surface level transmitter switch on attainment of a condensate level in the collecting chamber sufficient to give rise to a float buoyancy force able to secure the engagement of the driven wheel with the drive wheel and can be switched off again when the level reduces to a point which no longer ensures interengagement of the two wheels.

A plate spring, the free end of which, namely the rim of a central opening, stands in engagement with an entraining member fastened to the float, can serve for the step function by a holdingdown spring.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic sectional view of a condensate discharge pump in a first appliance embodying the invention; Fig. 2 is a schematic perspective view of a condensate discharge pump in a second appliance embodying the invention; Fig. 3 is a schematic sectional view of a condensate discharge pump in a third appliance embodying the invention; and is a schematic sectional view of a condensate discharge pump in a fourth appliance embodying the invention.

Referring now to the drawings, in all illustrated embodiments a collecting container 1 for condensate is arranged underneath a laundry drier heat exchanger from which condensate emanates. A pump chamber 2 is a component of the collecting container 1 and connected hydraulically with a collecting chamber of the container by way of a central inflow opening 3. An impeller wheel 4 running in the pump chamber 2 has a drive input shaft 5, which is provided with splines 24 on which a drive output gearwheel 6 is guided to be longitudinally displaceable, but secure against rotation. The impeller wheel 4 can lo be set into rotation by this wheel 6 when it is disposed in engagement with a drive input wheel 7 of a motor 8. The motor 8 also drives, by way of a drive input belt 25, a laundry drum (not illustrated) mounted thereabove and a drying blower 26. The impeller wheel 4 when driven conveys condensate 9 out of the collecting container 1 through a central induction opening 3 and into an outflow connecting piece 10.

The engagement between the wheels 6 and 7 is produced by a float 12, which is guided in vertical direction in an own float chamber 11 connected by way of an inflow opening 13 with the collecting container 1, when the float is moved sufficiently far upwardly by the surface level of the condensate 9 (surface level II). In that case a coupling fork 14 of the float draws the wheel 6 so far upwardly, in particular into the position indicated in chain-dotted lines, on the shaft 5 of the impeller wheel that it comes into contact with the conical surface of the wheel 7 of the motor 8. The impeller wheel 4 runs at the instant of the contact of the wheels and conveys condensate out of the collecting container 1 into the outflow z connecting piece 10.

In the embodiment of Fig. 2, the collecting container 1 is connected hydraulically by way of an inflow opening 6 with a float chamber 15. A somewhat larger float 17 than in the case of Fig. 1 is guided vertically in the flow chamber 15. A condensate pump 18, the pump chamber 2 of which is hydraulically connected at its underside with the float chamber 15 communicating with the collecting container 1, is embedded in the float 17. The impeller wheel and the drive output wheel 6 are connected together to be secure against relative rotation by way of the drive input shaft 5. A pressure connecting pipe 10 leads upwardly out of the float and the pump chamber and connects to a flexible outlet duct (not shown).

In this embodiment, the engagement of the wheels 6 and 7 comes into being through the float body 17, together with the condensate pump 18 embedded thereon, being raised sufficiently far by the level of the condensate 9. Since the condensate pump 18 has a noteworthy mass, the float body 17 dips into the condensate a sufficient extent for the pump chamber 2 to be constantly filled with condensate. Consequently, slurping noises cannot arise. Before the condensate could escape downwardly out of the pump chamber, the float 17 lowers the entire condensate pump 18 down so far than the wheel 6 comes out of engagement with the wheel 7. The motor 8 is, for the sake of simplicity, represented without further driving parts for the laundry drum and the blower.

In the case of the embodiment illustrated in Fig. 3, the arrangement of the float and the pump is similar to that in Fig. 2.

The pump is additionally provided with a suction bell 19, which sits on the base of the float chamber 15 and has low inflow openings 20. During vertical movement of the pump, the bell 19 remains on the base so that the pump can move up and down within the bell. The bell 19 serves, by its low inflow openings 20 near the base, for feeding 5 residual water from the base of the float chamber 15 to the pump.

An electromagnet 21, the armature 22 of which - when the electromagnet 21 is not actuated - assumes the position illustrated in dashed lines and projects downwardly, is arranged in the upper region of the float chamber 15. The armature 22 with the support of a spring 23 thereof in that case presses on the float 17 from above and prevents it from rising. In that situation, the wheels 6 and 7 remain out of engagement one with the other.

A surface level transmitter with an electrical switch, which can control the electromagnet 21, is arranged in the collecting container 1. Whenever a predetermined surface level of the condensate in the collecting container 1 is attained, in particular a level sufficient for an adequate buoyancy of the float together with the pump in order to secure engagement of the wheels with each other, the electromagnet 21 is actuated and pulls the armature 22 into the position illustrated in solid lines. Thereby, it releases the float 17, which then rises suddenly into the position of engagement for the two wheels. The condensate surface level transmitter has, according to presumption, a hysteresis so that its switch releases the electromagnet 21 only when the buoyancy force produced by the surface level is such that a secure engagement of the wheels is no longer ensured. The armature 22 with the support of its spring 23 then presses the float 17 down so far that the wheels are securely m 1 disengaged.

It can be made certain by this embodiment that the engagement of the wheels with each other provides a slip-free force transmission or that no contact of the wheels with each other takes place. An insecure engagement and wear, which is caused by slip, of the wheels can thereby be excluded.

In the preceding embodiments,the wheels are provided on their frustoconical surfaces with friction material for a friction couple. Alternatively, these surfaces can have a tooth-like profiling or a conventional toothing.

In place of the armature 22 of the electromagnet 21 illustrated in Fig. 3 and its control components, the float 17 can be loaded by a spring, the characteristic of which has a step in such manner that a hard portion of the spring characteristc must be overcome initially until suddenly a soft portion of the spring characteristic is present at the point of the step. Then, buoyancy would urge the float 17 upwardly through a short travel against the soft spring characteristic until the wheels get into engagement with each other. During the lowering of the condensate level, the buoyancy of the float 17 reduces until the step to the hard characteristic causes the float to be urged downwardly until the wheels are securely out of engagement.

This variant of the step function for the float has advantages even over the illustrated embodiment: the constructional cost is lower and the uncertainties attaching to a surface level switch for the control of the electromagnet 21 are avoided.

An embodiment with a spring step characteristic, provided by a bistable plate spring 27, is illustrated in Fig 4. For adaptation to the components differing from Fig. 3, the float 17 and the connecting piece 10 are differently shaped. The connecting piece 10 can either issue out the float 17 laterally or, in the case of vertical guidance, pass through one of several openings (not illustrated) distributed in radial symmetry at the spring 27. The remaining components are comparable with those of Fig. 3 and bear the same reference symbols.

The float 17 is firmly connected with an entraining member 28, which is penetrated in freely rotatable manner by the shaft 5. The shaft 5 is borne at the side of the wheel 6 by a bush 29 in a bearing sleeve. An annular groove at the circumference of the entraining member 28 stands in engagement with the rim of a central opening of the plate spring 27, which is firmly clamped at its outer rim to the wall of the float chamber 15. The drive output wheel 6 is mounted on the shaft 5 to be secure against rotation relative thereto, but to be axially displaceable therealong. In the illustrated raised position of the float 17, the entraining member 28 presses against the wheel 6 from below by way of the compression spring 30 and brings it into engagement with the wheel 7. The pump 4 is therefore able to convey condensate.

After a significant degree of lowering of the condensate level in the collecting container 1, the buoyancy force acting on the float 17 also reduces until the weight of the float inclusive of the pump exceeds the retaining force of the plate spring 27 to such an extent that this reduces its curvature. In that case, the engagement of the wheels 6 and 7 remains maintained, due to the compression spring 30, P r it 9 - even though the shaft 5 has been drawn down somewhat from the float 17. However, as soon as an abutment 31 at the top of the shaft is brought into contact with the wheel 6 from above, the wheel is drawn downwardly and comes out of engagement with the wheel 7. The stresses of the two springs 27 and 30 and their switching or reswitching travels 32 and 33 are so matched to be buoyancy and weight forces of the float 17 that the spring 27 snaps downwardly into the chain-dotted position at the instant at which the abutment 31 contacts the wheel 6 from above. The two wheels 6 and 7 therefore come out of engagement suddenly and almost free of slip. The drive output wheel 6 in that case drops into the chain-dotted position.

Correspondingly, the buoyancy force must increase greatly against the weight force of the float 17 and the now downwardly acting retaining force of the plate spring 27 until the float 17, on finally overcoming the spring-retaining force, snaps through the switching-back travel 33 into the illustrated position and brings the two wheels 6 and 7 suddenly into engagement with each other again.

This embodiment, too, can be modified in many ways. In place of a plate spring, which might possibly be too hard, there can be used a leaf spring inserted in like sense. In addition, a spring of that kind can engage elsewhere at the float provided a tilting moment is not transmitted to it. The step function can, in place of that within the spring, lie in a lever joint which is held in the respective stable position by a simple compression, tension or spiral spring.

Claims

1. An appliance provided with a condensate collecting chamber arranged below a drying chamber, a pump chamber and a float chamber each hydraulically connected to the collecting chamber, an impeller arranged in the pump chamber, a drive shaft connected to the impeller and carrying a driven wheel which is movable into and out of drive transmitting engagement with a drive wheel of a motor of the drier, and a float to influence engagement and disengagement of the gearwheels, the float being movably arranged in the float chamber and mechanically coupled with the driven gearwheel.

2. An appliance as claimed in claim 1, wherein the pump chamber is defined by a housing which is fixedly connected to the float and which is provided with a bearing for the shaft.

3. An appliance as claimed in claim 1 or claim 2, wherein the f I oat comprises foamed synthetic material.

4. An appliance as claimed in claim 3, wherein the material is polystyrol.

5. An appliance as claimed in any one of the preceding claims, comprising means to cause movement of the float in the float chamber to be subject to a step function before engagement of the driven wheel with the drive wheel.

_r or 9

6. An appliance as claimed in claim 5, wherein the means for causing the step function comprises a detector for detecting condensate level in the collecting chamber and an electromagnet having an armature controlling movement of the float, the detector being arranged to so control actuation of the electromagnet that the armature prevents the float from rising until detection by the detector of a condensate level predetermined to be sufficient for the buoyancy of the float to ensure engagement of the driven wheel with the drive wheel and depresses the float when the condensate has reduced or is assumed to have reduced to a level predetermined to be insufficient for the buoyancy of the float to ensure continuing engagement of the driven wheel with the drive wheel.

7. An appliance as claimed in claim 5, wherein the means for causing the step function comprises bistable spring means acting axially on the shaft andmovable from a first stable state in which the driven wheel is disengaged from the drive wheel to a second stable state in which the driven wheel is engaged with the drive wheel by a force at most equal to the force produced by the buoyancy of the float when the condensate has reached a level sufficient for conveying by the impeller and from the second stable state back to the first stable state by a force at most equal to the gravitational force of the float and all components connected therewith when the condensate has reduced to a level insufficient for conveying by the impeller.

8. An appliance as claimed in claim 7, wherein the spring means comprises a plate spring.

9. An appliance as claimed in claim 7 or claim 8, wherein the float is connected to the spring means by way of an entraining member.

10. An appliance as claimed in any one of claims 7 to 9, wherein the driven wheel is mounted on the shaft to be movable axially thereof but secure against rotation relative thereto, axial movement of the wheel on the shaft being limited in one direction by a compression spring between the wheel and the float and in the other direction by an abutment at an upper end of the shaft.

11. An appliance as claimed in any one of the preceding claims, the appliance being a laundry drier.

12. An appliance substantially as hereinbefore described with reference to any one of Figs. 1 to 4 of the accompanying drawings.

A W