SPRING DEVICE FOR SPRING-MOUNTING A FUNCTIONAL UNIT OF AN ELECTRICAL APPLIANCE, AND METHOD FOR INFLUENCING A SPRING DEVICE OF THIS KIND

Abstract

A spring device for spring-mounting a laundry drum of a washing machine has at least one spring means and coupling means for coupling the spring means to the spring device. The spring means has a spring constant or spring properties which are temperature-dependent and can be varied by a temperature effect on the spring means. As an alternative or in addition, the coupling means are designed in a temperature-dependent manner in such a way that they vary their coupling effect between the spring means and the spring device by a temperature effect. Heating means are provided for the spring means and/or for the coupling means in order to warm up the said spring means and/or coupling means and to change their spring properties or their coupling effect. Therefore, the spring-mounting arrangement of the laundry drum can be thermally, and therefore quickly and simply, varied.

Claims

1. Spring device for suspending or for spring-mounting a functional unit of an electrical appliance, wherein said spring device has: at least one spring means, and coupling means for coupling said spring means to said spring device, wherein: said spring means has a spring constant or spring properties which are temperature-dependent and are variable by a temperature effect on said spring means, and/or said coupling means are designed in a temperature-dependent manner in such a way that said coupling means vary their coupling effect between said spring means and said spring device by a temperature effect, wherein heating means are provided for said spring means and/or for said coupling means for the purpose of warming up said spring means and/or said coupling means and changing said spring properties and/or said coupling effect thereof.

2. Spring device according to claim 1, wherein said spring device has at least one main spring means and at least one additional spring means, wherein said coupling means are designed for coupling said additional spring means to said spring device, wherein said coupling means are designed in a temperature-dependent manner in such a way that they vary their coupling effect between said additional spring means and said spring device by a temperature effect, and wherein said heating means are provided for said coupling means for the purpose of warming up said coupling means and changing said coupling effect thereof

3. Spring device according to claim 2, wherein said main spring means and said additional spring means are designed without heating means.

4. Spring device according to claim 2, wherein said coupling means are at least partially composed of a metal alloy with a memory effect, wherein: in a first state as a basic state, said coupling means connect said additional spring means in a non-functionally effective and coupling manner to said spring device or said additional spring means is functionally disconnected from said spring device, and in a second state as a state of change, said coupling means connect said additional spring means in a functionally effective and coupling manner to said spring device or said additional spring means is connected to said spring device.

5. Spring device according to claim 2, wherein said heating means are designed for heating said portion composed of said metal alloy with said memory effect with a subsequent change in said coupling effect due to a warming up.

6. Spring device according to claim 1, wherein said spring means is a metal spring, which is in a portion at least partially composed of a metal alloy with a temperature-dependent memory effect.

7. Spring device according to claim 6, wherein said heating means are designed for heating said portion composed of said metal alloy with said memory effect with a subsequent change in said spring constant or said spring properties due to said heating and warming up.

8. Spring device according to claim 6, wherein said spring means is a helical spring.

9. Spring device according to claim 6, wherein said spring device has at least one main spring means and at least one additional spring means, wherein said additional spring means is at least partially composed of said metal alloy with said temperature-dependent memory effect.

10. Spring device according to claim 1, wherein said additional spring means or said main spring means are a pneumatic spring with an air volume for said spring properties, wherein said air volume is located in an air chamber.

11. Spring device according to claim 10, wherein said heating means are associated with said air chamber for heating said air volume.

12. Spring device according to claim 10, wherein said heating means are arranged on said outside on said air chamber or are mounted onto an outer side of said air chamber.

13. Spring device according to claim 10, wherein a piston is arranged in the air chamber, said piston being able to be moved along said air chamber, and said piston separating off said air volume.

14. Spring device according to claim 10, wherein a piston is arranged in said air chamber, said piston being able to be moved along said air chamber, and said piston separating said air chamber into a first air volume and into a second air volume, said piston is arranged between said first air volume and said second air volume, said first air volume and said second air volume are closed off, at least one of said first air volume or said second air volume are heatable by means of said heating means.

15. Spring device according to claim 14, wherein separate heating means are provided for said two air volumes in each case, wherein said separate heating means can be activated independently of one another.

16. Spring device according to claim 1, wherein said heating means have a resistance heating element.

17. Spring device according to claim 16, wherein said heating means have a resistance heating element in the form of a flat heating element.

18. Spring device according to claim 1, wherein said flat heating element is a thick-layer heating element.

19. Spring device according to claim 16, wherein said heating means are directly connected to a portion composed of said metal alloy with said temperature-dependent memory effect according to claim 3.

20. Spring device according to claim 1, wherein said spring device has a damping device on said functional unit.

21. Method for influencing a spring device according to claim 1 in an electrical appliance comprising a movable functional unit being spring-mounted by means of said spring device, wherein said functional unit of said electrical appliance comprising said spring-mounting arrangement has a resonant frequency, wherein said spring means of said spring device is heated for changing its spring properties and/or said coupling means are heated for changing a coupling effect between said spring means and said spring device.

22. Method according to claim 21, wherein varying said spring properties and/or said coupling effect is not performed continuously but rather in steps.

23. Method according to claim 22, wherein varying said spring properties and/or said coupling effect is performed in steps with a total of only two steps of 0% and 100%.

24. Method according to claim 21, wherein varying said spring properties and/or said coupling effect is performed in accordance with prespecifications when certain frequencies or rotation speeds of said functional unit are crossed.

25. Method according to claim 21, wherein said functional unit of said electrical appliance has a resonant frequency, and wherein detection in respect of whether it is approaching said resonant frequency is performed by means of a vibration sensor or a force sensor on said functional unit.

26. Method according to claim 25, wherein said spring properties or said coupling effect is changed when said resonant frequency is reached or shortly before said point.

27. Method according to claim 21, wherein, when said resonant frequency is reached, said spring properties are changed in such a way that said spring constant of said spring means is increased by at least 5%.

28. Method according to claim 21, wherein, when said frequency has reached at least 80% of said resonant frequency, said spring properties are changed in such a way that said spring constant of said spring means is increased by at least 5%.

29. Method according to claim 21, wherein, when a frequency has reached at least 80% of said resonant frequency, said coupling effect is greatly increased in such a way that said spring means is fully effectively coupled to said spring device or connected to said spring device.

30. Method according to claim 29, wherein said coupling effect is greatly increased in such a way that said spring means is rigidly coupled and connected to said spring device.

31. Method according to claim 21, wherein a drive motor for said functional unit is provided, wherein a motor current of said drive motor is detected and said resonant frequency of said functional unit or said situation of said resonant frequency being reached is identified on a basis of a profile of said motor current with a characteristic range.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Exemplary embodiments of the invention are schematically illustrated in the drawings and will be explained in more detail below. In the drawings:

[0034] FIG. 1 shows a schematic illustration of a washing machine as an electrical appliance according to the invention comprising a spring device for a laundry drum,

[0035] FIGS. 2 to 4 show various functional states of additional means for a spring device of the washing machine from FIG. 1,

[0036] FIG. 5 shows an alternative refinement of a spring, which can be varied by heating, in the form of a pneumatic spring with two air chambers,

[0037] FIG. 6 shows a modification to FIG. 5 comprising a pneumatic spring which has only one air chamber, and

[0038] FIG. 7 shows a yet further modification to a spring device similar to FIG. 2 with an additional spring composed of a memory alloy.

DETAILED DESCRIPTION

[0039] FIG. 1 illustrates a simplified view of a washing machine 11 comprising a housing 12. A laundry drum 14 is held, specifically such that it can rotate, in a manner which is known per se in a laundry drum holder 15 in the said housing. A drive motor, not illustrated here, is usually fitted to the laundry drum holder 15 in order to be able to rotate the laundry drum 14.

[0040] On account of the possible occurrence of an abovementioned unbalance during rotation of the laundry drum 14, in particular at high rotation speeds such as during spin-drying for example, conventional vibrations may occur in the washing machine 11, so that the said washing machine wobbles to a considerable extent. In order to be able to absorb the said vibrations to a certain extent, a spring device 17 is provided at the top of the laundry drum holder 15. The said spring device has two springs 18a and 18b, advantageously helical springs composed of metal. The said springs allow a certain degree of movement of the laundry drum holder 15. In order to prevent the movement or vibrations from becoming too large, two dampers 16 are arranged at the bottom of the laundry drum holder 15. The said dampers do not have the task of providing suspension, but rather are intended merely to damp movements or strong vibrations. This is also known from the abovementioned prior art.

[0041] The invention provides that the washing machine 11 has a spring device 17 according to the invention, that is to say yet a further spring or an additional spring which can be provided in addition to the springs 18a and 18b or can at least partially replace the said springs. The additional means 20, illustrated using dashed lines, can comprise coupling means 25 and an additional spring 22 according to FIGS. 2 to 4. As an alternative, according to FIGS. 5 and 6, the said additional means is only one additional spring 122 and, respectively, 222 which can be influenced. According to a yet further alternative, the said additional means is a series circuit comprising a further additional spring 332, which can be influenced, and an additional spring 322 according to FIG. 7.

[0042] In the exemplary embodiment of FIGS. 2 to 4, the additional means 20, outlined by dashed lines, which are similar to those in FIG. 1, have an additional spring 22 at one end for coupling to the outside. According to the prior art, this additional spring 22 is advantageously constructed as a metal helical spring. In principle, it can be similar to the springs 18a or 18b. FIGS. 2 and 3 show a basic state since, specifically, the additional spring 22 is not effectively coupled to the spring device. FIG. 4 shows the state of change since, here, the additional spring 22 is actively coupled.

[0043] The coupling means 25 are designed such that the additional spring 22 is actually not actively involved in the suspension operation. Therefore, it can be provided here that, in a basic state, the coupling means 25 are not active and, respectively, the piston 29 is moved up and down largely without friction in the cylinder 27 given a corresponding movement of the laundry drum holder 15. This is shown in FIG. 3.

[0044] Heating elements 28 are arranged on the outside of the cylinder 27, advantageously mounted directly onto an outer side of the cylinder 27. The said heating elements are preferably thick-layer heating elements of the kind mentioned in the introductory part which can also be fitted directly onto metal if an insulating layer has first been applied to the surface. These heating elements 28 can heat the cylinder 27 itself in such a way that it changes such that the piston 29 is firmly clamped therein, for example because it exhibits an even greater thermal expansion upon warming up than the cylinder 27 itself. As an alternative, the cylinder 27 can be composed of a temperature-invariant material, for example Invar. The heat which is then generated by the heating elements 28 expands only the piston 29 which is then firmly clamped inside the cylinder 27, either at an arbitrary point or at a possible latching-in point. This is illustrated in FIG. 4, where the piston 29 is firmly clamped in the cylinder 27 at the same point as in FIG. 2 and is therefore fixed by warming up by the heating element 28. The additional spring 22 is now fixedly and permanently an active part of the spring device 17 at the bottom of the coupling means 25. Therefore, the spring constant of the spring device 17 has increased in accordance with expectations, and therefore the resonant frequency has also increased.

[0045] During operation of the washing machine 11, the process can proceed such that, when in the prevailing configuration, that is to say when loading the laundry drum 14 with laundry, the situation of the resonant frequency being approached is identified. This can be performed in the case of a known resonant frequency on the basis of monitoring the rotation speed of the drive motor, not illustrated, wherein it is possible to store in a table the rotation speed of the drive motor at which a resonant frequency will be reliably or very probably reached. As an alternative, a vibration sensor or force sensor, not illustrated, can be provided, which vibration sensor or force sensor identifies, on the basis of the vibrations or movements of the laundry drum holder 15 in the housing 12, when the resonant frequency will soon be reached or when approximately 90% or 95% of the resonant frequency is reached. The vibrations then increase, specifically usually sharply or in a non-linear manner. The additional spring 22 can then be coupled by corresponding influencing of the coupling means 25. If the resonant frequency is reliably overcome, advantageously at a frequency of at least 10% above the assumed resonant frequency or better even somewhat higher, the additional spring 22 can be actually removed or deactivated again, that is to say decoupled. The heating elements 28 can then be switched off, so that the coupling effect is cancelled and, by cooling down the coupling means 25, the cylinder 27 again releases the piston 29 so that it can move freely. Therefore, the heating elements 28 have to be expected to be in operation for only 10 seconds or at most 20 seconds, so that firstly excessive warming up does not take place and secondly excessive energy is not consumed either.

[0046] As an alternative to the above-described way of determining a situation of the resonant frequency being approached, the motor current can likewise also be detected or monitored in a simple manner. It is possible to identify from a characteristic profile when the resonant frequency of the rotating laundry drum 14 including the laundry drum holder 15 is being approached. The spring device 17 can then be correspondingly influenced.

[0047] If the washing machine 11 runs through the frequency response from top to bottom, that is to say if the resonant frequency could be passed from top to bottom during crossing, the same method can be repeated.

[0048] As an alternative to the embodiment shown here in FIGS. 2 to 4, the piston 29 could be arranged in a fixed manner at the top and the cylinder 27 could be arranged on it by way of the spring 22 such that the said cylinder can move along the said piston. The heating elements 28 could then be arranged on the piston and expand the said piston when they are warmed up, so that the said piston can be firmly clamped in the cylinder 27 more easily and more directly. It would then be possible to supply electrical power to the non-moving heating elements 28 on the non-moving piston 29 more easily too.

[0049] FIG. 5 illustrates an alternative refinement of the invention with additional means 120, outlined by dashed lines, which consist only of a temperature-dependent spring means. Here, the additional spring 122 is designed as a pneumatic spring with two air chambers 123a and 123b. These air chambers 123a and 123b are arranged in a cylinder 127, with heating elements 128 respectively being provided in an upper region and a lower region on the outer side of the said cylinder. There are no heating elements in the central region.

[0050] A piston 129 is arranged in the cylinder 127 such that it can move in a vertical and longitudinal manner. Whereas the cylinder 127, by way of its top side, is fixedly connected to the housing 12 of the washing machine 11 or to another bearing, the piston 129 is fixedly connected to, for example, the laundry drum holder 15. A fastening rod of the piston passes through a seal 130, so that the lower air chamber 123 is likewise also sealed off in an air-tight manner.

[0051] A pneumatic spring of this kind is not necessarily customary for washing machines per se, but rather in other fields, such as the suspension of chassis, in particular in bicycles or motorcycles. A spring constant of the additional spring 122 or its spring properties depend on the air pressure in the air chambers 123a and 123b. If the heating elements 128 now warm up the air in the air chambers 123a and 123b during heating operation, the air pressure there increases. Therefore, overall, the spring constant of the additional spring 122 becomes larger and harder or the spring constant increases. As a result, the spring properties of the entire spring device of the entire washing machine also change, and this entire spring constant then also increases.

[0052] Activation of varying the spring properties of the additional spring 122 according to FIG. 5 advantageously takes place once again in a regulated manner when the resonant frequency is approached in the washing machine 11 during operation or during spin-drying. A frequency limit and also identification thereof can be as described above.

[0053] FIG. 6 illustrates a yet further option for an additional means 220, outlined by dashed lines, for a spring device 17 illustrated in FIG. 1. In FIG. 6, an additional spring 222 is once again in the form of a pneumatic spring, but only one single air chamber 223 is provided in a cylinder 227. A piston 229 which can be moved in a longitudinal manner in the cylinder 227 presses against the compressed air in the air chamber 223 as it is moved into the cylinder, so that a pneumatic spring is produced once again. Here, the spring properties are expected to be poorer than in the additional spring 122 according to FIG. 5, but instead the structural design is considerably simpler. It is only necessary for a single air chamber 223 to be provided, and a seal beneath the piston 229 can also be dispensed with.

[0054] Heating elements 228 are provided around the air chamber 223 on the outside of the cylinder 227. The effect of the said heating elements is as described above in relation to FIG. 5; they can warm up the air volume in the air chamber 223, as a result the air pressure further additionally rises and the additional spring 222 becomes as it were harder, at least under pressure loading. This can also help to vary a resonant frequency of the entire system of the washing machine 11 briefly and in a controlled manner, so that a resonance point can be readily overcome.

[0055] A yet further refinement of the invention is illustrated in FIG. 7. In addition to a spring 318, a spring device further has the additional means 320, outlined by dashed lines in the said figure. The additional means 320 consist of an additional spring 322 which, however, is advantageously a normal helical spring composed of metal. The said additional means is connected in series to a further additional spring 332 which is composed of a metal alloy with a memory effect, that is to say has a memory effect. The said memory effect is temperature-dependent. The variant illustrated here is designed in such a way that the further additional spring 332 can even be directly heated itself by current throughflow, as is illustrated. As an alternative, heating elements can of course also be provided, as in FIGS. 2 to 6, or else further heating elements can be provided, such as, for example, an inductive heating arrangement around the outside of the further additional spring 332. This reduces problems in respect of electrical connection and insulation.

[0056] It can also be provided in the case of the additional means 320 of FIG. 7 to change the spring constant by heating, specifically by changing the shape of the further additional spring 332 composed of memory metal by heating and the said further additional spring becoming harder or softer, alternatively longer or shorter. This also influences the spring constant of the additional means 320 in a predictable manner and therefore influences the spring properties of the entire spring device of the washing machine. Depending on the configuration of the further additional spring 332, the additional spring 322 could also be dispensed with in the case of the additional means 320 here. A further additional spring composed of memory metal which is then provided can then also be made softer or harder and/or longer or shorter by heating. A resonance point can, as described above, also be readily overcome in this way.

[0057] In principle, there is even the option, already described above, of not activating heating elements at all for overcoming the resonance point. A basic state is then even no coupling of additional springs or the like. The heating elements are also required only when the said coupling is required. If the said heating elements are designed in a corresponding manner, activation of this kind can be performed in a few seconds since the heating elements can be designed such that they respond very quickly and therefore their heating effect develops very quickly. The coupling means and/or springs heated by the said heating element can also react very quickly. As an alternative, heating can start as early as when the rotation speed of the laundry drum 14 of the washing machine 11 is ramped up, so that, when it can be predicted that the resonance point will be reached and exceeded, this additional coupling effect and/or spring effect is already present. When the resonance point is then overcome and the prevailing frequency is at least 5% or better at least 10% above the resonant frequency at the current rotation speed of the laundry drum 14 without activated coupling means and/or spring means, the said coupling means and/or spring means can be deactivated. The provision of complex force or vibration sensors can then be dispensed with under certain circumstances.