SANITARY DEVICE AND METHOD FOR CONTROLLING AN OPERATION POWER PROVIDED BY A POWER UNIT OF A SANITARY DEVICE

Abstract

 Sanitary device, comprising a ring- or U-shaped seat (2), an electric heating element (10) arranged at or within the seat (2), a power unit (8) adapted to provide an operation power to the heating element (10) and a control unit (13) adapted to control the operation power provided by the power unit, whereby a resistor (11) is connected or connectable in series to the heating element (10), whereby the control unit (13) is adapted to measure a voltage on a measuring point (19) between the resistor (11) and the heating element (10) in a connected state and to control the operation power depending on the measured voltage.

Description

[0001] The invention relates to sanitary device, comprising a ring- or U-shaped seat, an electric heating element arranged at or within the seat, a power unit adapted to provide an operation power to the heating element and a control unit adapted to control the operation power.

[0002] Heatable seats are an important comfort feature of modern sanitary devices, frequently called electric toilets or electric bidets. An electric heating element may be arranged at or within the seat and obtain electric operation power by a power unit. In order to achieve an appropriate and comfortable temperature for a person using the sanitary device a control unit controls the power applied to the heating element.

[0003] Conventional sanitary devices comprise a temperature sensor adapted to provide a temperature measuring signal to the control unit which controls the power unit depending on this signal. The temperature sensor is arranged inside the seat requiring respective space within the seat. Thus, those temperature sensors suffer from their large dimensions rendering a further reduction of the thickness of the seat difficult.

[0004] Therefore, it is an object of the invention to provide a sanitary device with a heatable seat of reduced thickness.

[0005] This is inventively achieved by a sanitary device at initially described, whereby a resistor is connected or connectable in series to the heating element, whereby the control unit is adapted to measure a voltage on a measuring point between the resistor and the heating element in a connected state and to control the operation power depending on the measured voltage.

[0006] The invention bases on the consideration to renounce a dedicated temperature sensor by obtaining an information relating to the seat temperature from the resistance of the heating element. Its resistivity may be assumed as linear increasing at least within a typical range of operation temperature, e.g. between +20 °C and +40 °C. Thus, connecting a resistor of known resistance in series to the heating element permits deriving the heating element's resistance by measuring the voltage on the measuring point between the heating element and the resistor in its connected state. The voltage may be measured while the power unit provides a known operating voltage and/or current to the heating element. Consequently, the operation power of the heating element provided by the power unit may be controlled depending on the measured voltage indicating the seat temperature. As the resistor used for the inventive sanitary does not need to be thermally connected to the seat or the heating element, installation space within the seat can be saved allowing a reduction of the thickness of the seat, advantageously.

[0007] The ring-shaped seat may be considered as O-shaped, as well, meaning that the seat surrounds an opening for a person to sit on completely, whereas the U-shaped seat does not surround an opening completely. A typical inventive sanitary device may also comprise a bowl, especially made of ceramics, to which the seat is attached. The bowl may additionally comprise a flushing unit connectable to a water supply and/or a drain connectable to a sewer system or tank. The seat may be adapted for a person sitting on it. The sanitary device may be adapted as toilet and/or for washing parts of the human body (bidet). A lid may be attached to the seat or the bowl. Additionally, the inventive sanitary device may comprise a spraying unit adapted to spray a liquid on the human body and/or a blowing unit adapted to blow, particularly warmed, air on the human body and/or a moving unit adapted to move the lid and/or a deodorization unit.

[0008] Advantageously, a switching unit is connected within a circuit comprising the power unit and the heating element and controlled by the control unit. The switching unit may comprise two switching elements, e.g. transistors, whereby a first switching element is adapted to allow the current to flow through the heating element and the resistor and a second switching element is adapted to allow the current to flow through the heating element without flowing through the resistor. The switching unit may be adapted to connect the resistor in series with the heating unit to perform a measurement of the voltage on the measuring point. The control unit may be adapted to connect the resistor in series with the heating unit when a measurement on the measuring point is performed. Hence, the current flows through the resistor only when it is necessary to measure the voltage avoiding a power consumption by the resistor when no measurement is performed. Thus, in a first switching state the first switching element may be open, e.g. the first transistor blocks the current, and the second switching element may be closed, e.g. the second transistor is conducting. In a second switching state the first switching element may be closed, the first transistor is conducting, and the second switching element may be open, the second transistor blocks the current.

[0009] Alternatively or additionally, the switching unit is adapted to open or close the circuit to control the operation power. Thus, in another switching state both switching elements may be open, e.g. both transistors block the current, to prohibit the current to flow through the heating element. Nevertheless, the second switching element may be opened or closed temporarily, e.g. for defining a pulse-width-modulation (PWM) with a duty cycle to heat the seat. The switching unit may allow a current to flow through the heating element if the measured voltage indicates, that the seat temperature is below a lower threshold. Accordingly, the switching unit may prohibit the current to flow through the heating element if the measured voltage exceeds an upper threshold.

[0010] The control unit may be adapted to control the operation power by switching a power line between the power unit and the heating element and/or by activating and deactivating the power unit. For example, the power unit is activated or the switch, e.g. a relay, is closed if the measured voltage indicating, the seat temperature is below the lower threshold. Accordingly, the power unit may be deactivated or the switch may be opened if the measured voltage exceeds the upper threshold. Alternatively or additionally, the control unit is adapted to control the power unit by setting a voltage and/or a current provided by the power unit. In this case the control unit may choose the set voltage and/or the set current such that the measured voltage remains near a predetermined value.

[0011] Advantageously, the control unit is adapted to control the operation power depending on a difference value between the measured voltage or a parameter derived from the measured voltage and a predetermined reference value. Hence, the difference value may be considered as error signal of a negative feedback control systems, having the power provided by the power unit as system input. This way, the power unit may be controlled very precisely to provide a comfortable seat temperature by the heating element.

[0012] More preferably, an ambient temperature sensor is adapted to provide an ambient temperature signal, whereby the control unit is adapted to control the operation power depending on the ambient temperature signal, additionally. Thus, the seat temperature may be set higher or lower with regard to the ambient temperature. E.g., the ambient temperature sensor comprises an NTC (negative temperature coefficient) element. Particularly, the lower threshold and/or the upper threshold and/or the reference value may be set depending on the ambient temperature signal.

[0013] Advantageously, the control unit is adapted to detect a malfunction of at least one component connected or connectable to the power unit and to switch a power line connected to the power unit if a malfunction is detected. The at least one component may be the heating element and/or the switching unit, particularly one of its switching elements. The malfunction may be a short circuit. The malfunction may be detected by measuring the voltage on the measuring point. E.g. in a normal operation state the voltage is within a predetermined range. It exceeds the range when a short circuit of the heating element or the switching unit occurs.

[0014] Particularly, the power unit and/or the control unit and/or the resistor are disposed outside the seat. Each of the aforementioned components may be arranged at the seat or, more preferably, separately from the seat allowing the realization of a very thin seat which has merely the heating element arranged inside. Preferably, a service device is arranged separately from the seat and incorporating the power unit and/or the control unit and/or resistor in a housing. Providing the service device allows the seat to be of reduced thickness over its entire dimensions. The service device and the seat may each comprise a connector to provide a connection between them.

[0015] Advantageously, the seat has a thickness of at most 10 mm, preferably at most 7 mm, more preferably at most 5 mm, with a minimum thickness of 3 mm.

[0016] Aside, the invention relates to a method for controlling an operation power provided by a power unit of a sanitary device, whereby the power unit provides the operation power to a heating element arranged at or within a ring- or U-shaped seat of the sanitary device. The inventive method is characterized in measuring a voltage on a measuring point between the heating element and a resistor connected in series to the heating element and controlling the operation power depending on the measured value.

[0017] Advantageously, a switching unit connected within a circuit comprising the power unit and the heating element and controlled by the control unit connects the resistor in series with the heating unit to perform a measurement of the voltage on the measuring point and/or opens or closes the circuit to control the operation power.

[0018] Preferably, the operation power is controlled by switching a power line between the power unit and the heating element and/or by activating and deactivating the power unit and/or setting a voltage and/or a current provided by the power unit.

[0019] Advantageously, the operation power unit is controlled depending on a difference value between the measured voltage or a parameter derived from the measured voltage and a predetermined reference value.

[0020] More preferably, the operation power is controlled depending on an ambient temperature signal provided by an ambient temperature sensor, additionally. Particularly, a power line connected to the power unit is switched if a malfunction of at least one component connected or connectable to the power unit is detected.

[0021] All statements according to the inventive sanitary device may apply analogously to the inventive method, so that advantages achieved by the inventive sanitary device may be achieved by the inventive method, too.

[0022] In the following, the invention is described in detail, whereby references are made to the principle drawings, which show:

Fig. 1

a perspective view of an inventive sanitary device;

Fig. 2

a top view on a seat of the sanitary device depicted in fig. 1;

Fig. 3

a block diagram of the sanitary device depicted in fig. 1; and

Fig. 4

a diagram of the resistance of a heating element of the sanitary device depicted in fig. 1 against a temperature.

[0023] Fig. 1 shows a perspective view on a sanitary device 1, comprising a ring-shaped, heatable seat 2 which is arranged on a bowl 3. According to further embodiments the seat may be U-shaped. A lid 4 is attached pivotly to the seat 2 to cover it in a closed position and to allow a person to sit on the seat 2 in an opened position. The bowl 3 is connected to a sewer system and has a cistern 5 with an operating element 6 to initiate flushing the bowl 3. A service device 7 is arranged separately from the seat 2 and comprises a housing in which a power unit 8 adapted to provide an operation power via a connector 9 to a heating element 10 arranged within the seat 2, a resistor 11 connectable in series with the heating element 10 via a switching unit 12 and a control unit 13 adapted to control the power unit 8 and the switching unit 12 are incorporated.

[0024] Besides, the sanitary device 1 comprises a spraying unit adapted to spray a liquid on the human body, a blowing unit adapted to blow warmed air on the human body, a moving unit adapted to move the lid 4 and a deodorization unit. Note, that this enumeration is not exhaustive. Those units, which are not shown in fig. 1 in detail, may be controlled by the control unit 13, as well.

[0025] Fig. 2 shows a top view on the seat 2, comprising a connector 14 adapted to fit to the connector 9 of the service device 7 and to connect the power unit 8 to the coil-like heating element 10. The heating element 10 may be molded in seat, arranged sandwich-like between two parts of the seat 2 or arranged on a bowl-side surface of the seat 2. The seat 2 is made of a plastic material, e.g. polypropylene, acrylnitril-butadien-styrol, urea-formaldehyde resin, a composite material, wood or combinations thereof. Note, that this enumeration is not exhaustive. Since no further components have to be integrated into the seat 2 besides the heating element 10 and the connector 14, the seat 2 has a very low thickness of 10 mm or even only 5 mm. This is achieved by avoiding an additional temperature sensor arranged within conventional seats and by determining an information relating to the seat temperature out of the resistance of the heating element 10.

[0026] Fig. 3 shows a block diagram of the sanitary device 1. The power unit 8 is adapted to provide an operation power via a power line 15 and the connectors 9, 14 to the heating element 10. A relay 16 is placed within the power line 15, whereby the control unit 13 is adapted to switch the relay 16 to an open state when the control unit 13 detects a malfunction, e.g. a short circuit, of the heating element 10 or the switching unit 12. In a normal operation state of the sanitary device 1 the relay 16 is closed.

[0027] The switching unit 12 is also controlled by the control unit 13 and comprises two switching elements, e.g. a first transistor 17 and a second transistor 18. If the first transistor 17 blocks and the second transistor 18 is conducts, current provided by the power unit 8 will flow through the heating element 10 to ground in the closed state of the relay 16, thus heating the seat 2. In this state of the switching unit 12 a measuring point 19 being connected with an A/D-converter input 20 of the control unit 13 is connected to ground. By contrast, if the transistor 17 conducts and the second transistor 18 blocks, the current will flow through the resistor 11 to ground, whereby a voltage to be measured on the measuring point 19 drops over the resistor 11. This voltage can be described by the term

whereby U_S denotes the voltage supplied by the power unit 8, R₁ denotes the resistance of the heating element 10 and R₂ denotes the resistance of the resistor 11. It has been found out that the resistance R₁ of the heating element 10 increases approximately linear with the temperature of the heating element 10. Thus, R₁ is a proper indicator for the temperature of the seat 2 within a typical range of operating temperature between +20°C and + 40°C.

[0028] Fig. 4 shows a diagram of the resistance R₁ of the heating element 10 against its temperature T in detail. As can be seen the resistance R₁ rises nearly constantly with rising temperature T, so that the measured voltage U_m on the measuring point 19 can be assumed to be proportional to the temperature T. The resistance R₁ can be modelled as

whereby ρ₀ denotes the electric resistivity the material of the heating element 10 referring to a reference temperature of e.g. 20°C, α denotes the temperature coefficient of first order, ϑ denotes the difference between the temperature T and the reference temperature, l denotes the length of the heating element 10 and A denotes its cross-sectional area.

[0029] Basing on the nearly linear relation depicted in fig. 4, temperature coefficients of higher order may be omitted. The temperature coefficient of the resistivity of an exemplary material may be α = 3930 ppm · K^-1 resulting in a change of the resistance R₁ of about 15 mΩ · K^-1 within the temperature range between +20°C and +40°C. It has to be noted, that the resistor 11 is disposed outside the seat 2 inside the service device 7. Hence, heating of the seat 2 has only very few or practically no influence on the resistance R₂ of the resistor 11, what might distort the measured voltage U_m otherwise.

[0030] Referring again to fig. 3, the control unit 13 controls the switching unit 12 to set the first transistor 17 to its conducting state, allowing a current to flow through the heating element 10 and the resistor 11, and the second transistor 18 to its blocking state in order to provide a measurement of the voltage U_m dropping over the resistor 11. Then, the control unit 13 controls the operation power provided by the power unit 8 depending on the voltage U_m measured on the measuring point 19. If the voltage U_m is below a lower threshold, indicating the need for heating the seat 2 the control unit 13 blocks the first transistor 17, prohibiting a current to flow through the resistor 11, and controls the second transistor 18 to be conductive, allowing a current to flow from the heating element 10 to ground directly. In order to heat heating element 10, the second transistor 18 may be switched on or off according to a predetermined on/off-time, e.g. a duty cycle of a pulse-width-modulation. Otherwise, if the voltage U_m exceeds an upper threshold indicating, that the seat to has been heated to a predetermined temperature, both transistors 17, 18 are controlled to block a current flowing through the heating element 10. The steps may be repeated regularly allowing to control the seat temperature continuously.

[0031] Furthermore, the control unit 13 detects if a malfunction, e.g. a short circuit of the heating element 10 or of the first transistor 17 and the second transistor 18, occurs. Such a malfunction may be detected if the voltage U_m exceeds a predetermined range, defined by further upper and lower thresholds. If the voltage U_m drops below the further lower threshold a short circuit of the transistors 17, 18 may be detected. If the U_m exceeds the further upper threshold, a short circuit of the heating element 10 may be detected while current flows through the resistor 11. If a malfunction is detected, the control unit 13 switches the power line 15 by opening relay 16 in order to prevent a damage of the sanitary device 1. According to another embodiment, to control the operation power the control unit 13 switches the power line 15 by opening and closing relay 16 instead of or additionally to controlling second transistor 18.

[0032] According to another embodiment the relay 16 is closed all the time. Instead of switching the relay 16 to its closed are open state, the control unit 13 activates or deactivates the power unit 8 directly.

[0033] According to yet another embodiment the relay 16 is closed continuously, whereby the control unit 13 controls the power unit depending on a difference value between the measured voltage or a value derived from the measured voltage and a predetermined reference value. Therefore, the voltage and the current supplied by the power unit 8 are changed continuously by the control unit 13, which realizes a negative feedback control system having the operation power as system input. The control strategies realized by the aforementioned embodiments may also be combinated.

[0034] The upper and the lower thresholds and/or the reference value are fixed, saved within a memory of the control unit 13. According to another embodiment, the upper and the lower threshold and/or the reference value are derived from a temperature value or a temperature level basing on a user input, e.g. obtained by an input device of the sanitary device 1.

[0035] Furthermore, the control unit 13 is connected to an ambient temperature sensor 21, e.g. comprising an NTC (negative temperature coefficient) element, sensing an ambient temperature of the sanitary device 1. The control unit 13 is adapted to control the operation power provided by the power unit 8 depending on the ambient temperature signal of the temperature sensor 21, additionally. Therefore, the control unit 13 may choose the upper and/or the lower threshold and/or the reference value depending on the ambient temperature signal.

[0036] According to another embodiment, the sanitary device 1 is a bidet, allowing a person sitting on the seat 2 to wash his body.

Claims

1. Sanitary device, comprising a ring- or U-shaped seat (2), an electric heating element (10) arranged at or within the seat (2), a power unit (8) adapted to provide an operation power to the heating element (10) and a control unit (13) adapted to control the operation power provided by the power unit, characterized in that a resistor (11) is connected or connectable in series to the heating element (10), whereby the control unit (13) is adapted to measure a voltage on a measuring point (19) between the resistor (11) and the heating element (10) in a connected state and to control the operation power depending on the measured voltage.

2. Sanitary device according to claim 1, characterized in that a switching unit (12) is connected within a circuit comprising the power unit (8) and the heating element (10) and controlled by the control unit (13), whereby the switching unit is adapted to connect the resistor (11) in series with the heating unit (10) to perform a measurement of the voltage on the measuring point (19) and/or to open or close the circuit to control the operation power.

3. Sanitary device according to claim 1 or 2, characterized in that the control unit (13) is adapted to control the operation power by switching a power line (15) between the power unit (8) and the heating element (10) and/or activating and deactivating the power unit (8) and/or by setting a voltage and/or a current provided by the power unit (8).

4. Sanitary device according to one of the preceding claims, characterized in that the control unit (13) is adapted to control the operation power depending on a difference value between the measured voltage or a parameter derived from the measured voltage and a predetermined reference value.

5. Sanitary device according to one of the preceding claims, characterized in that an ambient temperature sensor (21) is adapted to provide an ambient temperature signal, whereby the control unit (13) is adapted to control the operation power depending on the temperature signal, additionally.

6. Sanitary device according to one of the preceding claims, characterized in that the control unit (13) is adapted to detect a malfunction of at least one component connected or connectable to the power unit (8) and to switch a power line (15) connected to the power unit (8) if a malfunction is detected.

7. Sanitary device according to one of the preceding claims, characterized in that the power unit (8) and/or the control unit (13) and/or the resistor (11) are disposed outside the seat.

8. Sanitary device according to claim 7, characterized in that a service device (7) is arranged separately from the seat (2) and incorporating the power unit (8) and/or the control unit (13) and/or resistor (11) in a housing.

9. Sanitary device according to one of the preceding claims, characterized in that the seat (2) has a thickness of at most 10 mm.

10. Method for controlling an operation power provided by a power unit (8) of a sanitary device (1), whereby the power unit (8) provides the operation power to a heating element arranged at or within a ring- or U-shaped seat (2) of the sanitary device (1), characterized in measuring a voltage on a measuring point (19) between the heating element (10) and a resistor (11) connected in series to the heating element (10) and controlling the operation power depending on the measured value.

11. Method according to claim 10, characterized in that a switching unit (12) connected within a circuit comprising the power unit (8) and the heating element (10) and controlled by the control unit (13) connects the resistor (11) in series with the heating unit (10) to perform a measurement of the voltage on the measuring point (19) and/or opens or closes the circuit to control the operation power.

12. Method according to claim 10 or 11, characterized in that the operation power is controlled by switching a power line (15) between the power unit (8) and the heating element (10) and/or activating and deactivating the power unit (8) and/or setting a voltage and/or a current provided by the power unit (8).

13. Method according to one of the claims 10 to 12, characterized in that the operation power is controlled depending on a difference value between the measured voltage or a parameter derived from the measured voltage and a predetermined reference value.

14. Method according to one of the claims 10 to 13, characterized in that the operation power is controlled depending on an ambient temperature signal provided by an ambient temperature sensor (21), additionally.

15. Method according to one of the claims 10 to 14, characterized in that a power line (15) connected to the power unit (8) is switched if a malfunction of at least one component connected or connectable to the power unit (8) is detected.

Drawing