The present invention relates to a washer, and in particular, to parts of a washing machine or a dishwasher, and further relates to a washer having such parts.

In order to control water consumption of a washer, for example, washing machines or dishwashers, or perform other corresponding control according to the amount of water in the washer, a detection device may often be disposed at an appropriated position in the washer. A detection device used more commonly at present is a water-level detection device. Document CN 102 560 976 A discloses in detail a structure and principle of such a water-level detection device, which may serve as a reference for the present invention.

However, the thus known water-level detection device has the following defects: as a washer often has various metal parts, especially metal housing, an output frequency of the water-level detection device is easily interfered by the metal parts of the washer, so that the detection result is biased, and finally errors occur in the control of the washer based on the water-level detection result, thereby affecting the washing effect. It can be seen from the first curve 100 in FIG. 3 of the attached drawing that the output frequency of the existing water-level detection device varies to a larger extent as a distance to a metal plate changes.

An objective of the present invention is to reduce or eliminate the influences generated by environmental factors on an output frequency of a water-level detection device.

With respect to the above objective, the present invention adopts a technical solution as defined in the independent claims to a water-level detection device and a washer, respectively. Preferred embodiments of the invention are defined independent claims, with preferred embodiments of the water-level detection device corresponding to preferred embodiments of he washer and vice versa even if not mentioned Preferred embodiments are also apparent from the subsequent description and the attached drawing. With respect to the above objective, the present invention adopts a technical solution as follows:

A water-level detection device including: a housing; an air passage connected to the housing; an air chamber within the housing and connected to the air passage; a partition board within the housing and capable of reciprocating based on a pressure change of the air chamber; an inductor constituting a part of a resonant circuit; and a magnetic core supported on the partition board and capable of moving with movement of the partition board to cause a frequency change of the resonant circuit to which the inductor is connected; a magnetic shield being disposed around the inductor.

Preferably, the magnetic shield is in a sleeve-like structure with peripheral walls closed.

Preferably, the magnetic shield is disposed around an outer surface of the housing. Such a structure makes assembly of the magnetic shield simple, so that small changes may be made based on the existing water-level detection device without re-designing an internal structure of the device, which saves cost.

Preferably, the magnetic shield forms at least a part of the housing.

Preferably, the partition board is mounted on a diaphragm constituting a part of walls of the air chamber and is elastically retractable.

Preferably, an edge of the diaphragm is connected to the housing.

Preferably, the inductor is disposed around a movement path of the magnetic core.

The other objective of the present invention is to improve detection precision of the washer for the water level. Based on the objective, the washer of the present invention includes a controller and a liquid container, and the water-level detection device stated above is connected to the liquid container through the air passage. In addition, the controller of the washer and the resonant circuit are such connected that the controller may determine a water level or a water level change of the liquid container according to a frequency of the resonant circuit. The washer may be selected from a variety of machines using water to treat dirty objects, including a washing machine, a washer-dryer, a dishwasher and the like.

Compared with the prior art, as the magnetic shield is disposed outside the inductor, interference of metal parts for the water-level detection device is reduced, thereby improving the detection precision. In terms of the washer using the water-level detection device in the present invention, due to improvement of the water-level detection precision, the washer may control more accurately, thereby obtaining an ideal washing effect, and appropriately lowering energy consumption of the washer at the same time. Preferred embodiments of the invention are now explained in detail with reference to the attached drawing. In the drawing:

FIG. 1 is a schematic diagram of a washer provided with a water-level detection device (for the purpose of easy observation and understanding, only the water-level detection device and a liquid container are displayed, and other components are omitted);

FIG. 2 is a circuit diagram of a connection between a resonant circuit in a water-level detection device and a controller of a washer; and

FIG. 3 is a curve of a change of frequencies output by different water-level detection devices relative to different distances from a metal plate obtained according to experiments. As shown in FIG. 1 , a washer 1 includes a liquid container 2, such as, an outer tub 2 of a washing machine. A bottom of the liquid container 2 is connected to a water-level detection device 4 through an air passage 3. The water-level detection device 4 includes a housing 5. The housing is internally provided with an air chamber 6. The air chamber 6 is connected to fluids in the air passage 3 connected to the housing 5. The housing 5 is further provided with a diaphragm 7 with an edge connected to the housing. The diaphragm 7 constitutes a part of walls of the air chamber 6, and may be elastically retractable under a pressure action in the air chamber 6, away from or close to a bottom face 61 of the air chamber 6 opposite thereto. The diaphragm 7 is provided with a partition board 8. Then, the partition board 8 may reciprocate with a pressure change in the air chamber 6. It can be seen in combination with FIG. 1 and FIG. 2 that, an upper part of the air chamber 6 is provided with an inductor 9, the inductor 9 and a capacitor as well as other ancillary electrical components constitute a resonant circuit 10. Output ends 10a and 10b of the resonant circuit 10 are connected to a controller 1 1 of the washer 1. A magnetic core 12 is supported on the partition board 8, capable of moving with movement of the partition board 8. A reset spring 13 is disposed between a top of the magnetic core 12 and an inner wall of the housing 5. The magnetic core 12 passes through the inductor 9 along an axial movement path. The movement of the magnetic core 12 relative to the inductor 9 may change an output frequency of the resonant circuit 10 to which the inductor 9 is connected. The output frequency may be received by the controller 1 1 , which thus determines a current water level or a water level change in the liquid container 2, and then performs corresponding control on the washer 1. Such control includes, but is not limited to, controlling a water inflow of the washer; deciding the amount of added detergent according to the water level; and determining the amount of water inflow in unit time according to the change of the water level.

A working principle of the water-level detection device 4 may be substantially described as follows: as the liquid container 2 is connected to the air passage 3, when a liquid is filled in the liquid container 2, a part of the liquid also enters the air passage 3, so as to seal the air chamber 6. As the water level in the liquid container 2 rises, pressure in the air chamber 6 gradually increases. Change of the pressure makes the diaphragm 7 stretch and expand, so as to make the partition board 8 move upward. The magnetic core 12 then moves upward in the inductor 9, which changes inductance of the inductor 9, and finally changes the output frequency of the resonant circuit 10. On the contrary, when the water level in the liquid container 2 drops, the pressure in the air chamber 6 becomes small. Under the action of the reset spring 13, the magnetic core 12, the diaphragm 7 and the partition board 8 jointly move downward, to compress the air chamber 6. Due to the movement of the magnetic core 12, the output frequency of the resonant circuit 10 changes.

To reduce magnetic interference caused by environmental factors, in a first embodiment of the present invention, a magnetic shield 14 is disposed around an inductor 6 in the housing 5 of the water-level detection device 4.

To reduce the production and design costs, as a preferred alternative solution, in a second embodiment of the present invention, a magnetic shield 14' is disposed on an outer surface of the housing 5 of the water-level detection device 4. As other alternative solutions, a magnetic shield may also be disposed in the housing

5 and on an outer surface thereof at the same time.

The magnetic shields 14 and 14' are in a sleeve-like structure with peripheral walls closed, to facilitate assembly and manufacturing. Certainly, based on the objective of the present invention, the magnetic shields 14 and 14' may also be in any other shapes and structures adapted for assembly.

In a third preferred embodiment, the magnetic shield forms at least a part of the housing 5. That is, at least a part of the housing 5 is directly made of a magnetic shielding material.

A first curve 100 in FIG. 3 shows a change of the frequency output by a previously known water-level detection device relative to different distances to the metal plate; a second curve 200 shows a change of the frequency output by the water-level detection device relative to different distances to the metal plate after sleeve-like magnetic shield with peripheral walls not closed is disposed outside the inductor of the water-level detection device; and a third curve 300 shows a change of the frequency output by the water- level detection device relative to different distances to the metal plate after sleeve-like magnetic shield with peripheral walls closed is disposed outside the inductor of the water- level detection device. It can be seen by contrast between the three curves that, the output frequency of the previously known water-level detection device not provided with magnetic shields is easily interfered by surrounding metal parts; after non-closed sleevelike magnetic shields are installed, interference is suppressed to a certain extent; and after closed sleeve-like magnetic shields are installed, the output of the water-level detection device is almost free from the interference of external metals.

The above embodiments are merely preferred embodiments of the present invention, and the present invention may have many other embodiments. Equivalent variations made by persons of ordinary skill in the art with respect to the present invention under teachings of the present invention shall still fall within the scope of the claims of the present invention.