WO2000036480A1

WO2000036480A1 - Improved control and monitoring apparatus for refrigerating appliances

Info

Publication number: WO2000036480A1
Application number: PCT/EP1999/009174
Authority: WO
Inventors: Umberto Pujatti
Original assignee: Ht Control S.R.L.
Priority date: 1998-12-14
Filing date: 1999-11-26
Publication date: 2000-06-22
Also published as: ITPN980091A0; IT1305558B1; ITPN980091A1

Abstract

Control apparatus with at least one temperature control probe (5) adjustable by the user through adjustable means (15, 16) arranged on a control unit (11), characterized in that said control unit (11) includes means (22, 23) suitable for monitoring differentiated anormalous situations in the operation of the appliance based on different values (TN + ΔTS, TN - ΔTI, TN + 2H) of the effective temperature (TEFF) in the holding compartment (3) which is sensed by said control probe (5) and/or on the duration of the same values. Use: refrigerating appliances, in particular for professional uses, with at least one thermally insulated compartment (3). Advantages: the functions of controlling and monitoring the refrigerating equipment are incorporated in a single compact apparatus.

Description

IMPROVED CONTROL AND MONITORING APPARATUS FOR REFRIGERATING

APPLIANCES

DESCRIPTION

The piesent invention i elates to an improved control and monitoring apparatus for refrigerating appliances, paiticularly for commercial uses, such as counters, display cases, cabinets, and also refrigerated motor vehicles.

Conventionally, these refrigerating appliances, having at least one thermally insulated compartment, are controlled by a user-adjustable thermostatic device, that controls the on-off modes of the refrigerating appliance

(compressor) and of any auxiliary operating devices (fans for forced air circulation mside the insulated compartment, defrosting heating elements, etc.)

Systems of this type aie also piov ded with alarm means, i.e., means capable of signalling possible operating anomalies of the appliance to then usei Often, howevei , such means aie limited to visual and/or acoustic signal generatois of a particulaily elementary alarm.

Very sophisticated systems are also known, intended to optimize the management of the adjusting phases, which are suitable for commercial establishments equipped with a large number of appliances, as, for example, supermarkets. Such systems include a plurality of simple and low-cost control devices, referred to as "slave", on each single appliance, connected by means of electrical cables to a more sophisticated centralized device referred to as "master", which, m turn, can be connected to additional remote monitoring and technical assistance systems Apart from the fact of not bemg specifically capable of independently monitoring anomalous situations in the refrigerating appliances, these systems are evidently of such exceedingly complex construction and installation as to make them, including for economic reasons, not available for the generality of commercial users

Finally, the use is well known, in the industrial sector (food processing firms), as well as in many laboratories, of particularly sophisticated monitoring means known as 'data loggeis", that howevei require a technical skill that is not always possessed by the users of commeicial refngei ating appliances used for food preservation

Moieovei it is necessary to beai m mind that all professional users of lefngeratmg appliances used for preserving perishable food pioducts are now obliged by recent legislation (Euiopean Union Dnectives 93/43 and 96/3) to identify m then activity "every phase tnat could result critical for the safety of the foodstuffs and [to] guarantee that the suitable safety procedures are identified, applied, maintained and kept up to date" Consequently, a user of this type "must also guarantee [the efficiency of] the control means implemented to obtain a product having the prescribed requirements of health and safety"

In the scope outlined as above, the objective of the present invention is to piopose a contiol appaiatus foi lefngeiatmg appliances that

a) enables the orofessional useis to meet the legal obligations, b) is capable even in the basic veision of signalling a particularly large number of events connected with the occurrence of anomalous situations, c) is capable in the moie complete version of recording at veiy close piedetermined time intervals the effective temperature in one or two thermally insulated compartments duimg a penod of time longer than one yeai

These and other objectives of the piesent invention are achieved with an appaiatus having the charactenstics set down m the accompanying claims

The appaiatus of the invention is also characterized by the following advantages

I) in all its veisions it has a compact construction and a particularly moderate cost II) it does not require any technical skill on the part of the users of the equipment on which it is installed,

III) it can be installed on both new equipment and on the many appliances already in operation with scarcely any or no modifications

In ordei to better disclose the characteristics, purposes and advantages of the present invention, the description of a preferred (but not exclusive) embodiment of the piesent invention is provided, with the assistance of the enclosed drawings m which

- Figuie 1 shows schematically a refrigerated display case for a commercial establishment, piovided with the control apparatus of the present invention m its basic veision (essential configuration),

- Figure 2 shows an embodiment of the control unit belonging to the lefπgerated display case of Figuie 1 ,

- Figure 3 shows a block diagram of the same contiol unit,

- Figure 4 shows a tempeiatuie-time diagiam lelative to the food holding compartment of the lefngeiated display case of Figure 1 m the condition of an anomalous situation (e g , electπcal power failure)

As is shown m Figuie 1 , a refngeiated display case (taken as a typical example of a lefπgeiating appliance used in a commercial establishment) includes substantially a cabinet 1 wΛh a fiont dooi 2 and a theimally insulated compartment 3 foi the pieservation of foodstuffs The refrigeration of the compartment 3 is piovided oy a functional unit 3 (that typically, includes an evaporatoi , a compiessoi , an expansion device and a condenser of the refngerant) which is conti oiled by a control probe 5 according to operating tempeiatmes selected by the user through a contiol unit 11 The control unit 11 which is the heart of the appaiatus of the present invention, is essentially an electronic module connected to the probe 5 through a cable 6 and to the functional unit 4 thiough a cable 7 The feeder inside the control unit 11 normally leceives, thiough anothei cable 8, energy fiom the terminal board 9 of the functional unit 4 (which is connected in turn to the power supply) or through a power supply transformer

As is shown m Figure 2, the control unit 11 is enclosed m an insulated case 12 having one side 13 that remains accessible to the user as it is located, for example, adjacent to the door 2 of the refrigerated display case, and that mcludes a display 14 of the type with shiftmg characters and two selection keys 15 and 16, incremental and decremental, respectively On the side 13 and/or on another wall of the case 1 are located the other outputs, which are suitable for transmitting diffeient signals lelative both to anomalous situations confirmed by the same control unit 11 and to the type of configuration of the same appliance

Figuie 2, which is a schematic lepresentation, shows specifically a radio antenna 17, an lnfiaied transmittei 18 and an RS485 serial output, indicated by numeral 19 but there could also be only one of such outputs For reasons of simplicity, Figuie 2 does not show the teimmals to which the cables 6, 7 and 8 aie connected, which aie lllustiated schematically m Figuie 1

Specifically, according to an important characteristic of the invention, the case 12 of the contiol unit 11 has the same dimensions as the electronic theimostats that aie conventionally installed on professional refrigerating appliances, I e a plastic holder measuπng 32 mm in height and 74 mm m width

Since the use of the contiol unit 11 does not impose significant modifications to the wiring of the appaiatus, the present invention can also be used to advantage to letiofit most of the lefngeratmg appliances already in opei tion, m addition to new appliances

The block diagiam of Figuie 3 lllustiates how the control unit 11 includes the following pans all contained in the same case

- a mam feeder 20 of the same contiol unit 11 , which includes a double half-wave lectifier and a DC/DC converter, connected to the power supply through a cable 8 connected to the terminal board of the functional unit 4, - an opeiational amplifier 21 to which are connected the cables 6 and 60 coming fiom the contiol probe 5 and from the probe of the evapoiator 50,

- a microprocessor 22, compiehensive of ROM, RAM and EEPROM memories which receives its input fiom the operational amplifier 21 , - a real time clock (RTC) circuit 23, comprehensive of a RAM memory, connected to the microprocessor 22;

- an auxiliary feeder 26, which m practice is a buffer battery, connected through the contacts 24 and 25 to only the RTC circuit 23;

- the above-mentioned outputs for communicating to the user the monitoring data consisting, in addition to the display 14, of the radio antenna 17, the infrared data transmitter 18 and the serial output 19.

The control unit 11 also includes the following means, not shown:

- the interfaces with the already mentioned cable connection 7 for controlling the functional unit 4 (and any other auxiliary components like the fans for forced air circulation inside the insulated compartment 3, the fans for the forced air circulation for cooling the compressor and the condenser, etc.) of the appliance,

- manual reset means foi the data memorized by the above-mentioned memoiy-equipped components of the control unit 11

The microprocessoi 22 has as its input the value (processed by the operational amplifier 21) of the effective temperature T_EFT (m the thermally insulated compartment 3 of the lefiigerated display case, which is continually sensed by the control probe 5

This value T_tFF is compared with the value T of the nominal operating tempeiatuie of the equipment, which can be assigned by the manufacturer as default value or selected by the user through the keys 15, 16 on the control unit 11. Said comparison also takes into account, in addition to the predetermined tolerances (ΔT_S upward and ΔT, downward, respectively) of the T_N temperature, the delay times set by the user based on the specifications of the manufacturei of the apparatus since they consider the lefngeratmg capacity of the functional unit 4, expressed in °C/hour

From the results of the comparison, the microprocessor 22 actuates a series of actions, m particulai a senes of alarms, as will be explained below.

A pieferred embodiment of the invention calls for assuming - the values of T_N + ΔT_S and T_N - ΔT, as the lower threshold and, respectively, as the upper threshold of a first anomalous operating condition of the apparatus refened to as "prealarm" which, if it lasts for a time shorter than the above-mentioned delay time, is simply signalled to the user (smce it would be due, for example, to the introduction of a certain quantity of relatively warm products into the appliance) However, if the prealarm condition lasts for a time longer than a predefined time t_A, greater than or equal to the above-mentioned delay time (as m the case m which the door 2 of the appliance is left inadvertently open) , the ontrol unit 11 ascertains an "alarm" condition which, in addition to being communicated in leal time to the user, is also memorized,

- the value of T_N + 2ΔT_H, wheie ΔT, > ΔT_S, is the positive temperature differential between the on and off modes (hysteiesis) of the compressor m the functional unit 4, as a sensing threshold of a furthei anomalous operating condition (blackout alarm)

Fiom this descnption it is evident that, according to the fundamental chaiacteπstic of this invention, the control unit 11 incorporates the conventional control means (that control the on and off modes of the functional unit 4 to achieve and maintain a predetei mined operating temperatuie T„) with the means foi monitonng the appliance The monitoimg means, that are suitable to determine, memoπze and signal anomalous situations on the equipment, opeiate on the basis of the effective tempeiature T^ sensed by the same control means, 1 e with the contiol probe 5

An example of opeiation of the invention will now be described, with leference to the Cartesian time (t) - tempeiature (T) diagram of Figure 4

It is assumed that the lefngeratmg appliance is legulated so as to have m the thermally insulated compartment 3 a nominal operating temperature of T_N =

-18°C with toleiances of ΔT_S = ΔT, = 3°C and so that the momtoied time period is the time between 1 00 and 19 30 of a given day

Until 18 00 the appliance woiks legulaily, as is shown by the fact that the tempeiature T∞, sensed by the contiol probe 5, varies cyclically based on the on and off modes of the compiessoi within the predetermined interval of T_M + ΔT_S/ -ΔT,, that is between -21°C and -15°C At 18 01 , the user charges a certain quantity of relatively warm food products into the compartment 3, which causes a brief rise m temperature The control probe 5 in fact measures at 18 10 an instant value of TEΠ- = -14°C, that the microprocessor 22 finds to be >T_N + ΔT_b, so that it activates in real time a signal of prealarm state This signal consists of the appearance on the display 14 of the flashing Ht code alternating with the value TEFF Smce the compressor operates normally, at 18 20 a temperature of T^ = -16°C <T_N + _T_S is measured in the compartment 3, which causes said signal to stop, and a temperature of TEFT = -17°C is measured at 18 30 In other words, in this case the prealarm condition is not followed by an alai m condition

Just aftei 18 40 and until 19 27, theie is the occurrence of a second, much moie serious, anomalous condition which consists of a blackout cutting off electric powei to the appliance The blackout causes the complete stoppage of the lefngeratmg appliance, except for the RTC circuit 23, thanks to the auxiliary feeder 25, which makes it possible to memorize the time that elapses, that is, with the passing of every minute of blackout the RTC circuit 23 memorizes the actual time of the day

During the blackout, the temperatuie m the compartment 3 increases with a piogression which leaves no lecorded trace, however, at 19 27, the time at which the powei supply is lestored (so that the lefngeratmg appliance lesumes its regular opeiation), the contiol piobe 5 senses a maximum temperature peak THT = -10°C which is assumed as the lesettmg temperature of the functional unit 4 Since the miciopiocessoi 22 peiceives that at this moment T_E[T > T. + 2H, the control unit 11 activates an immediate communication to the user of the alarm state lelative to this anomalous situation (blackout) and memorizes it

The communication consists, at least, m the appearance of the shifting message "B-out Ptl = -10°C on the display 14 In turn, the data memorized in the control unit 11 aie the resetting temperature T_^ = -10°C and the duration of the blackout (47 minutes) By pressing one of the keys 15 and 16, the user can read these data on the display, and only aftei this it is possible for the user to reset the conti ol unit 11 , aftei having voluntarily activated the means provided foi this purpose In addition, m a preferred embodiment, the memory is capable of lecoiding up to tniee blackout alaims In othei words, the apparatus of the invention shows and memorizes the fact that, after 18 30 (when a regular temperature Tor = -17°C was measured), the tempeiatuie in the compartment 3 rose for 57 minutes, up to a value of about -10°C, which was reached at 19 27, when normal operation resumed This enables the user to decide if, and up to what pomt, the preserved food products may have lost their "requirements of healthfulness and safety"

If a remote monitoring of the refrigerating appliance is provided, the data memorized can be transfeiied (m real time or by the action of the user) from the control unit 11 thiough the serial output 19 to a PC and/or a printer (not shown), or tiansmitted through high-fiequency signals by the antenna 17

Alternatively, or even additionally, the tiansfer of the same data to the remote monitoring point in the form of IR signals emitted by the transmitter 18, can come about through a specific portable transfer unit (not shown) known in the art

Since the embodiment described thus far is only one possible embodiment it is evident that the piesent invention can be implemented m more sophisticated veisions using moie than one probe as inputs of the control unit, for example an evapoiator temperature sensoi , and equipped so as to also monitor a second lefngerated compartment of the same refrigerating appliance, and lecoid with a furthei (fourth) temperature sensor at piedeteimmed time intervals m the span of time of over one year of operation of the lefngeratmg appliance

In all cases there lemain the advantages already mentioned, that is, the compact standaid dimensions of the contiol unit case 12, the differentiated anomalous conditions of opeiation of the appliance that can be monitored, the different modes of communication with the usei

Claims

1 Control apparatus foi a lefiigeiatmg appliance, particularly for commeicial uses, having at least one thermally insulated compartment (3) with at least one contiol piobe (5) foi controlling the functional unit (4) of the lefiigeiatmg appliance according to the selection effected by the user through adjustable means (15, 16) of a contiol unit (11) ananged on an accessible part of the appliance, characteiized in that in said contiol unit are present means suitable foi deteimimng (22), memonzmg (23) and communicating (22, 23, 17, 18, 19) to the usei diffeientiated anomalous situations on the basis of different values (T_N + ΔT_S, T_N - ΔT„ TV + 2H) of the effective temperature (T_w) in said compartment (3) that is sensed by the same control piobe (5) and/or of the dm ation of said values

2 Control apparatus accoidmg to claim 1 , characterized in that said contiol unit also includes means (15, 16), actuatable by the user, for selecting at least one part of the values of the monitoied temperatuie (T_N + ΔT», T_N - ΔT,, T_N + 2H) that coi I espond to anomalous situations

3 Contiol appai tus accoidmg to claim 1 or 2, characterized m that at least one part (23) of said memoiization means, prefeiably the one lelative to the time elapsed, aie fed by an independent feeder (26) even during periods of powei failuie in the powei supply connected to the apparatus

4 Contiol apparatus according to any one of the previous claims, characteiized m that said detei mining (22), memonzmg (23) and communicating (22, 23, 17, 18, 19) means can be disabled only manually by the user through means (15, 16) provided on the control unit

5 Control apparatus according to any one of the previous claims, charactenzed m that said anomalous situation signalling means mclude a display of the type with shiftmg characters

6 Control apparatus according to any one of the previous claims, characterized in that it includes, m a manner known m the art, means (17, 18, 19) for the remote ti ansmission of signals relative to said anomalous situations

7 Control appaiatus according to claim 6, characterized m that said means for remote ti ansmission include a radio antenna (17), integrated m said control unit, associated to a receivei aπanged at a I emote monitoring position

8 Contiol appaiatus according to claim 6, charactenzed m that said means foi remote transmission include an infrared transmittei (18), mteifaceable with a mobile data tiansfer unit which is associated m turn with a remote receiving unit

9 Control appaiatus accoidmg to any one of the previous claims, characterized m that the entire contiol unit (11) is enclosed m a case (12) having the standard foim and dimensions of tne electronic thermostats for lefngeratmg appliances