EP0881443A1 - Power saving circuit for mains operated refrigeration apparatus and control method thereof - Google Patents

Abstract

An energy saving control comprises a self contained unit connected between a refrigerator and the main supply. The unit has a proximity/movement sensor to detect if users are in the vicinity of the refrigerator eg. hotel minibar. If no persons are detected the control unit switches to an energy saving mode after a preset time delay, where the unit operates in a switching mode. The detector can be a simple PIR detector or a movement sensor. If a person is detected when the unit is in the energy saving mode the unit initiates a starting mode or enhanced cooling. The various time factors of the control unit are programmable.

Description

The invention relates to a power saving circuit for a mains operated Refrigerator, especially for a mini bar in one Hotel room, according to claim 1, and a method to control the same according to claim 8.

Many hotel rooms today have a small fridge, also called minibar, equipped. In it, the hotel guest chilled drinks etc. provided. To noise pollution due to the intermittent operation of the minibar small refrigerators of the absorber type are usually to be avoided used. However, these usually have a higher one electrical connected load as a regarding cooling capacity comparable device of the compressor type. In hotel businesses with many rooms is therefore because of the large Number of continuously operating minibars with a relative high energy consumption due to the constant supply Cooling capacity to be expected. The content of the minibar will generally around the clock at an average temperature kept at around 5 ° C and thus available to the guest posed. This is usually the case even if the Demand for chilled drinks etc. only for a few Hours per day is really available. A disadvantage This common solution is the relatively high energy consumption.

However, there are known solutions for cooling devices by a controlled increase in the average cooling temperature energy consumption during certain operating times reduce. The mean temperature is raised to a degree, of course, to ensure that the chilled content, i.e. drinks, food, etc., not spoil and become unusable prematurely. So is from the WO-82 01812 discloses a device in which refrigerated display cases in sales outlets during non-business hours are controlled using a predetermined switching cycle, to save energy. The disadvantage of this solution is in that he is not easy on the circumstances is transferable in a hotel. In contrast to sales outlets can when operating a minibar in a hotel room fixed times are not expected in which there is no demand and therefore in energy saving mode could be switched.

The object of the invention is therefore a power saving circuit and a method for controlling the same specify that for a refrigerator, especially for a minibar in a hotel room, are applicable, and those mentioned Do not have disadvantages. An additional task is that the invention for refrigerators and minibars different origins should be applicable no replacement or modification of the existing devices required should do.

This task is carried out by the independent Claim 1 and those mentioned in claim 8 Features resolved.

The solution is essentially based on the fact that the power saving circuit as a separate device in the refrigerator Mains supply can be connected upstream and that the power saving circuit has a sensor element which is used in the detection a sensor output signal to a person in the vicinity of the cooling device emits that in a control logic for generation a switching sequence is used with which the mains power supply is controlled for the refrigerator.

So one of the main advantages of the present invention lies in that with the introduction of the present power-saving circuit no new and expensive refrigerators are bought and that neither on the cooling units nor on the electrical installations of the power supply - apart from from the interposition of the power-saving circuit according to the invention - any changes are necessary. The Design provided with a sensor for detecting the Presence of a person in the vicinity of the cooling device also ensures that even with different user behavior always a satisfactory cooling performance is provided and that the existing energy saving potential nonetheless can be largely used.

In an advantageous embodiment of the invention switching sequence generated by the control logic from three parts, which are used depending on the situation.

A first part of the switching sequence in which the mains power supply for the cooling unit periodically switched on and off is used if during longer Time no one is detected in the vicinity of the cooling device becomes, if the sensor output signal during longer There is no time.

A second part of the switching sequence, hereinafter referred to as Transitional portion is referred to and during its duration the mains supply for the cooling unit is switched on continuously remains applied when a person is in the environment of the cooling device is detected. The Transition portion in each case when the sensor output signal is present restarted.

A third part of the switching sequence, hereinafter referred to as Initial share is designated and during which the Mains power supply for the cooling unit also switched on continuously remains, then applies if that Refrigerator is turned on and the filled goods, so Drinks etc. first from room temperature to the above Operating temperature of about 5 ° C must be cooled.

It is also advantageous to set the on / off ratio of the first part of the switching sequence and the duration of the switch-on period the remaining two parts of the switching sequence adjustable to provide the individual encountered Relationships, for example in different Needs-oriented hotel businesses to take into account. By suitable adjustment of the parameters mentioned can the existing energy saving potential in the desired Be exhausted.

Fig. 1

die Zusammenschaltung der Stromsparschaltung und des Kühlgerätes,

Fig. 2

ein Blockschaltbild der Stromsparschaltung,

Fig. 3

ein Zeitdiagramm der Schaltsequenz im vorgesehenen Betrieb, und

Fig. 4

ein Zeitdiagramm der Schaltsequenz während der Einschaltphase.

An embodiment of the solution according to the invention is explained in more detail below with reference to drawings. Show it

Fig. 1

the interconnection of the power-saving circuit and the cooling device,

Fig. 2

a block diagram of the power saving circuit,

Fig. 3

a timing diagram of the switching sequence in the intended operation, and

Fig. 4

a timing diagram of the switching sequence during the switch-on phase.

Figure 1 shows the basic interconnection of a Power-saving circuit 1 according to the invention with a cooling device 2, for example a minibar. The power saving circuit 1 is a power cord and a power plug 3 on one Mains socket 4 connected. The cooling unit is over the device's own power cord at socket 5 on the power-saving circuit 1 connected. The power saving circuit 1 has via a sensor element 6 for detecting the presence a person in the vicinity of the refrigerator 1.

FIG. 2 shows the block diagram of the power saving circuit 1. The mains voltage is fed from the mains plug 3 via the switch contacts of a mains relay 7 to the socket 5 for connecting the cooling device 2. A network fuse (not shown) and / or an overvoltage protection 8 can optionally be present in this path. A control logic 9 is fed by a power supply 10. The sensor element 6 is connected to an evaluation circuit 11, which feeds the processed sensor output signal 12 to the control logic 9. The control logic 9 controls the network relay 7 via a switching stage (not shown) with a switching sequence. Furthermore, adjustable potentiometers 13, 14, 15 are connected to corresponding inputs of the control logic 9. These potentiometers are used to set the on / off ratio V _{p of} a periodic component of the switching sequence, the duration T _{u of} a transition component of the switching sequence and the duration T _{a of} an initial component of the switching sequence.

The sensor element 6 is preferably a pyroelectric Infrared detector of a passive infrared detector (PIR). PIR detector known design couple two (detection) criteria together. On the one hand, this is the detection of infrared radiation living body in the spectral range between 7µm and 14µm, on the other hand the detection of a movement by the Space of the body emitting IR radiation perpendicular to one segmentation of the surveyed space. In Combination with the evaluation circuit 11 provides such Sensor element is a sensor output signal that is essentially then exists when there is a person in the area of the sensor element moves. Of course, can be used for detection the presence of a person also sensor elements are used, which are based on other principles, so for example motion sensors based on the ultrasound principle. The sensor element can also be an outside of the Power-saving circuit arranged element, for example a ground contact via a control input (not shown) is connected to the control logic. Such a Control input can also be potential-free. in the present embodiment with the aforementioned PIR detector one assumes that it is sufficient to move the mentioned Type to detect and that this is normally the Presence of a person can be equated.

On the functional principle of the power saving circuit:

Figure 3 shows schematically the intended normal operation a cooling device 2 with a power saving circuit 1, essentially that is, a timing diagram of the control logic 9 generated switching sequence for controlling the mains power supply to the cooling unit and (approximately) the expected Temperature curve in the cooling device.

The top line of the time diagram shows schematically (Yes / no representation) the presence of a person in the Environment of the cooling device. It is also believed that used sensor element 6 during the entire duration of the presence gives the person a sensor output signal. Farther it is also assumed in the course of the illustration that before the first detection of a person in the environment of the cooling device at time t = 0 for a long time nobody was detected, and that is why up to this When the cooling unit was operated in economy mode, which is why in this diagram from an initial cooling temperature of approx. 10 ° C is assumed.

A cooling device or a minibar operated directly from the mains would reach an average cooling temperature of approx. 5 ° C in normal operation with the on / off rhythm given by the cooling device or minibar internal temperature setting. A minibar with an upstream power-saving circuit, on the other hand, only achieves an average cooling temperature of approx. 10 ° C due to the additional switching rhythm for the mains power supply, which is superimposed or imposed on the mains input. The cooling temperature effectively achieved when using a power-saving circuit according to the invention essentially depends on the selected on / off switching ratio of the superimposed switching rhythm. This is achieved by the periodic on / off portion of the switching sequence mentioned. For the sake of simplicity, an on / off switching period of 1 hour and an on / off ratio of 1: 1 are assumed in the time diagram shown (V _p = 1). The actual values to be set are advantageously determined in the specific application situation by further tests.

If a person enters the room at time t = 0 and, as shown in the diagram, remains in the vicinity of the minibar for about 4.5 hours, until a transition time T _u of 3 hours has elapsed after the last detection of the person, the Mains power supply released. This means that the mini bar lowers the cooling temperature to the ideally desired 5 ° C without any external influence in the order of about 4 hours (an approximate value determined by tests). The course of the cooling temperature is only shown schematically and in reality will have significantly fewer abrupt transitions. As mentioned earlier, the transition time T _u in the power-saving circuit can be set using a potentiometer. The periodic part of the switching sequence is only started when the transition time T _u has elapsed. According to the illustration, however, this always happens in such a way that the on component becomes effective, which is equivalent to an effective extension of the transition time T _u . When the periodic part of the switching sequence is started, the temperature in the minibar begins to rise again until it finally reaches the value of approx. 10 ° C, which is influenced by the 'external' switching rhythm, unless another person enters the room in the meantime. It can also be seen from the figure that every short-term detection of the presence of a person in the vicinity of the cooling device always triggers the transition portion of the switching sequence again. In the example shown, the selected transition time T _u is just under the time (approx. 4 hours) that the cooling device itself requires to reach the lower cooling temperature. This ensures that the minibar reaches the desired cooling temperature as quickly as possible at least approximately again.

Figure 4 shows schematically the intended initial operation a refrigerator 2 or a minibar with one Power saving circuit, essentially a time diagram the switching sequence for control generated by the control logic 9 the mains supply to the cooling unit, and (approximately) the expected temperature profile in the Refrigerator or in the minibar when starting up the same.

The top line of the time diagram also shows schematically here (Yes / no representation) the presence of a person in the environment of the cooling device. It is again assumed that the sensor element 6 used for the entire duration emits a sensor output signal when the person is present. Furthermore, the course shown also assumes that before switching on the minibar, the temperature inside the minibar was about 20 ° C, which is why in this diagram this initial temperature is assumed.

A cooling device or minibar operated directly from the mains would reach the average cooling temperature of approx. 5 ° C in about 9.5 to 10 hours with the on / off rhythm given by the cooling device or minibar internal temperature setting. This is also approximately the case with a minibar which is connected via a power-saving circuit according to the invention. When the minibar is put into operation, a 6-hour start time T _a is started in the switching sequence, within which any detections of a person in the vicinity of the minibar remain ineffective (see also event A shown in dashed lines). After the start time T _a has elapsed (even without being triggered by the presence of a person), the 3-hour transition time T _u is started, within which any detections of a person in the vicinity of the minibar no longer remain ineffective, but the effect described earlier (see also event B shown in dashed lines; the mains power supply would be released until the transition time T _{u has} elapsed after the person was last detected). If, however, no person is detected in the vicinity of the minibar within 9 hours, the periodic portion of the switching sequence is finally also started here with the passage of the transition time T _u . According to the illustration, this always takes place in such a way that the on component becomes effective, which is equivalent to an effective extension of the transition time T _u . As a result of the combined times T _u and T _a it is achieved that the minibar also reaches the desired cooling temperature as quickly as possible at least approximately in this operating case.

Is, as in the example shown, for at least 9.5 hours after commissioning nobody in the area the minibar, will automatically switch back to energy saving mode switched. If this happens, it is (how in the case without a power saving device) relatively much at the beginning Energy converted into cooling capacity because the lower one first Cooling temperature is controlled. The advantage of this Control type is that in the minibar filled goods in this case only for relatively short Stored at a cooling temperature above about 10 ° C are.

The initial part of the switching sequence is always one higher switch-on or event priority assigned than that Transition share, and this in turn a higher switch-on or Event priority as the periodic on / off portion. This manifests itself in the fact that during a running start time the transitional portion and the periodic on / off Proportion can be suppressed during an ongoing transition period but only the periodic on / off portion of the Switching sequence.

Claims (10)

Power-saving circuit (1) for a mains-operated cooling device (2), in particular for a minibar in a hotel room, characterized in that the power-saving circuit (1) can be connected upstream of the cooling device (2) as a separate device and a sensor element (6) for detection of a person in the vicinity of the cooling device or a control input for such a sensor element, the sensor element (6) emitting a sensor output signal (12) when a person is detected in the area of the cooling device and a control logic (essentially) controlled by the sensor output signal (12) 9) is available to generate a switching sequence that controls the power supply for the cooling device. Power-saving circuit according to claim 1, characterized in that the switching sequence has a periodic on / off component, the on / off ratio of which is adjustable and which is initiated after the sensor output signal (12) has not been present for a prolonged period. Power-saving circuit according to Claim 1, characterized in that the switching sequence has a transition component which can be set in terms of time and which switches on the mains power supply for the cooling device for a transition period and which is initiated when the sensor output signal (12) is present. Power-saving circuit according to Claim 1, characterized in that the switching sequence has an initial portion which can be set in terms of time and which switches on the mains power supply for the cooling device for an initial time and which is initiated when the cooling device is started up. Power-saving circuit according to claim 2, 3 and 4, characterized in that a higher switch-on priority is assigned to the initial part of the switching sequence than the transition part of the switching sequence, and this in turn has a higher switch-on priority than the periodic on / off part of the switching sequence. Power-saving circuit according to one of claims 1 to 5, characterized in that the sensor element (6) is a passive infrared sensor. Power-saving circuit according to one of claims 1 to 5, characterized in that the sensor element (6) is a motion sensor. Method for controlling a power saving circuit (1) according to claim 1 for a mains operated cooling device (2), especially for a minibar in a hotel room, with a sensor element (6) for detecting the Presence of a person in the vicinity of the cooling device (2) and a control logic (6) for generating a Switching sequence for controlling the power supply to Cooling device, if there is a long absence of detection a person in the vicinity of the refrigerator Mains power supply for the refrigerator from a periodic Part of the switching sequence switched on and off periodically and is the ratio of the duty cycle for the duration of the periodic portion of the Switching sequence is adjustable. A method according to claim 8, wherein upon detection of the presence of a person in the vicinity of the cooling device, the mains power supply for the cooling device is switched on continuously for a transition time T _u and the duration of the transition time T _{u is} adjustable. A method according to claim 8, wherein when the cooling device is started up, the mains supply for the cooling device is switched on continuously for an initial time T _a and the duration of the initial time T _{a is} adjustable.

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