GB2091914A - Central heating system control - Google Patents

Abstract

A control unit of an H.W. and C.H system Fig. 1 comprises switches 8 to select any of six operating periods. Light-emitting elements 4 give analogue indication of time of day and also the selected time periods in a manner distinguished therefrom eg by colour or by flashing. Sliders 82 are continuously variable to select room temperature from heating OFF to max. during a respective period. Switches 18a enable setting of desired HW temp. A microprocessor 42 Fig. 3 includes means for comparing the set temperatures with actual room temperature. <IMAGE>

Description

SPECIFICATION Improvements in or relating to programming means This invention relates to programming means for electrical output functions, in particular for time control of heating apparatus.

Typically, such means comprise a device incorporating a clock or the like establishing an overall time period or programme base, e.g. a 24-hour time base, with means to set four switching times adjustably in that period, although some programming devices are known that have means providing a larger number of switching times but with some restriction on their positions.The selection of output function control has normally been limited, for example, there being function selector switches that allow the on/off operation of space heating means in dependence upon a thermostatic control device operating in the space being heated, and possibly also drawoff hot water heating means, from time-operated switches responding in different ways at the set switching times, and associated selector switches to allow the selection of a single on/off cycle or double on/off cycles for each function (space heating and hot water) during the 24-hour period, and it may be possible also to select a continuous "on" or continuous "off" setting for one or both functions.

There have also been electronic programming devices produced more recently that offer many of the features described above, but in adapting to electronic techniques the devices have also been less easy to understand and to use than conventional electromechanical devices.

Programming means, especialiy for programming domestic heating, will often be used by people with no particular knowledge or training and any added complexity will limit the usefulness of more flexible control arrangements. By virtue of being more difficult to understand they may discourage the consumer from making use of the facilities that are provided, and they are more likely to be operated incorrectly. Moreover, the electronic devices so far adopted may not even provide greater control than the known electro-mechanical devices.

According to the present invention, there is provided a programming means for controlling heating and/or cooling means and comprising a programming device having an electronic circuit for producing output signals for programming the operation of said means, said circuit being arranged to operate in conjunction with adjustable timing means adapted to delineate adjustable time periods within a larger overall time period and with programming means for the delineated time periods, said programming means comprising at least one adjustable programming element assigned to each individual time period for setting a desired temperature level in that period, a thermosensitive element responsive to the temperature of a region to be controlled by the programming device being arranged to provide an input signal to the electronic circuit dependent upon the temperature sensed by said element and the electronic circuit producing an output signal in dependence upon the differences between said sensed temperature and the temperature setting of the or each said adjustable element of the programming means in its assigned operative time period.

Advantageously, such a device is provided with analogue display means for displaying said overall time period and for indicting thereon the elapsed time in a programme cycle and the time periods delineated by said timing means, there conveniently being a common electronic analogue display for all this information, and the adjustable programming elements of the individual time periods are preferably arranged as a group forming a configuration parallel to and adjacent said time display.

The invention will be more particularly described by way of example with reference to the accompanying diagrammatic drawings, in which: Figure 1 illustrates the front panel of a programming device according to the invention, Figures 2a and 2b illustrate features of a remote temperature control for use with the device of Fig. 1, and Figure 3 is a block diagram of the circuitry of the device in Fig. 1.

Fig. 1 illustrates the front panel 2 of a device according to the invention in which a time display 4 of the programme base is provided by means of an array of light-emitting elements, and the time of day is indicated by illumination of each element in turn in accordance with the inscribed time scale. In this example there is a rectilinear array of 48 similar elements 6, the individual elements corresponding to half-hour periods of a 24hour clock, but the overall time period can be subdivided into greater or lesser periods if required.

The device illustrated is arranged to have six adjustable switching times within an overall period represented by the array of elements 6. These times are set by respective timing push switches 8 labelled "Set A", "Set B," "Set F", arranged in a rectilinear array 10 like time display 4. The associated circuits are so arranged that when an individual push switch 8 is held down the switching time A, B ... F associated with that switch sweeps progressively to and fro between the limits set by the adjacent preceding and succeeding switching times (and in the case of the switches "Set A" and "Set F" the beginning and end, respectively, of the array), until stopped by releasing the push switch. In this way, all six switching times are individually adjustable, although as will be explained later a switching operation does not necessarily occur at the set times.

The light-emitting elements 6 also serve to show the programmed switching times set by the push switches, but in a manner that is differentiated from the time-of-day indication, e.g. as by being of a different colour or by using a flashing signal for the time-of-day indication. In the latter case, when the timeof-day indication is coincident with a programmed switching time it can be arranged that the light-emitting element concerned will then flash with a different duty cycle than if it indicated only time-of-day: e.g. for time-of-day only it might have light-dark cycle of 1:9 whereas with the two indications coincident this changes to 9:1. In order to avoid confusion when adjusting the switching times, it can be arranged that the time-of-day indication is extinguished while any of the push switches 8 are being held down.

It will also be necessary to adjust the position of the time-of-day indication, both for initial setting purposes and for clock adjustments such as the changeover to and from Summer Time. The front panel of the device has two push switches 12, 14 for this purpose, giving forward and backward adjustments respectively. By pressing the forward switch 1 2 the time-of-day indication will for example move forwards progressively through the elements to the right-hand end of the time display 4 and then reappear at the left-hand end and continue to step forwards until the switch is released. The backward adjustment switch 14 of course will operate in the opposite manner. Again, to avoid confusion with the programme switching time indications set by the switches 8, these indications can be arranged to be extinguished during a time-ofday setting process.

Because the time is indicated by the elements 4 in discrete steps, when the timesetting operation is carried out in the manner described it is preferably arranged that the programme base timing begins from the exact half-hour point selected, to avoid ambiguity in the setting procedure, i.e. so that it will take the complete half hour before the time-of-day indication moves to the next element. If it is desired to be able to set the internal time of the device closer to real time an intermediate step facility can be provided to allow adjustments in smaller steps of, e.g. five minutes.

This can be so arranged that by pressing the time advance or retard switches 12, 14 briefly, e.g. holding one or other down for less than 2 second, a five minute step will be added to or subtracted from the internal timekeeping register. This can be repeated as desired in either direction, allowing adjustments to be made in any multiple of five minutes. It will be understood that this is an optional adjustment and although the facility may not be self-evident to an uninformed user, such a user will not be unduly concerned about precise setting of the "time of day".

Associated with the programme switching times are two series of selector switches 1 8a, 82. The first series 1 8a consists of independently operable paddle switches 1 6a for control of the heating of a draw-off or domestic hot water supply, and the second series 82 consists of independently operable slider switches 84 for control of a space heating output. The paddle switches are simply on-off switches, but the slider switches are continuous adjustable between an off position and a maximum setting.

The selector switches serve to control the state of a programmed output function in the respective periods delineated by the programme timing switches 8. Thus, with the push switches 8 and time display 4 indicating a series of particular switching times A to F, the six selector switches of each series 1 8a, 82 determine whether the output function controlled is on or off during individual periods A to B, B to C ... F to A. It is to be noted that the selector switches define the programme control values within individual delineated time periods independently of the time period setting means. Of course, if it is desired to subdivide the overall programme time period into a greater or lesser number of sectors, the number of selector switches then being changed correspondingly so that each time sector can be individually controlled.

Equally, however, it is not necessary to have a change of state at the end of each set period. The output function defined by any selector switch is independent of the function set by any other selector switch so that the user has complete choice.

The selector switches 1 6a have distinctively different appearances in their alternative positions so that the overall programme set by the switches is immediately apparent: i.e. as they appear in Fig. 1, they show "on" periods from A to B, C to D and E to F alternating with "off" periods from B to C, D to E and F to A. The six slider switches 84 assigned to the individual delineated time periods similarly signal their states and each gives a continuously variable adjustment for its respective period, from a "heating off' position to a maximum room temperature setting of approximately 80"F (280on).

This form of space heating control is used in conjunction with a temperature sensor 86 fitted in an optimum position in the space being heated, a preferred form of sensor being shematically illustrated in Figs. 2a and 2b and comprising a thermistor 88 and a variable resistance 90 connected in series. A microprocessor 42 (Fig. 3) provides a voltage source of known internal impedance across the terminals 92 of the sensor and so generates a voltage that is a function of the temperature sensed. This can be compared in the microprocessor with the adjustable reference voltage set by the operative slider 84 for the time period in question, and an output function control signal is generated accordingly.

The variable resistor 90 in the sensor is adjusted by a rotary knob 94 on the front cover of the sensor and allows a small local adjustment of temperature to be made by the user thereby modifying the combined resistance of the thermistor and resistor. The adjustment may allow a variation of temperature of plus or minus 10% relative to the setting of the programme selector slider -- e.g. for a 60"F (1 5 C) nominal setting there will be a possible adjustment between 66 and 54"F (1 3.5 C and 1 6.5 C). This form of adjustment may be particularly useful to make temporary adjustments to the heating level without having to change the previously set optimum programme on the heating selector sliders.

Both series of switches 1 8a, 82 are arranged as rectilinear arrays parallel to the time display 4 and the timing switches 8, in order that they can be easily related to the indicated switching times A to F, so that even an unsophisticated user is able to comprehend easily the programme that has been set and to make adjustments without difficulty.

Respective indicator lights 20, 20a are provided adjacent the arrays of programme selector switches 1 8a, 82 to show whether the output is on or off at any instant. The lights are operated from the control signals generated by the programming device so as to indicate the instantaneous state of the programme regardless of possible back-feedis from load circuits or the like.

The panel 2 also carries override or boost switches 22, 22a for the water heating and space heating controls respectively, and by means of which it is possible to modify temporarily a preset programme. There may be an illuminated indicator incorporated in each switch to show when it has been operated. In particular, the function of the switch 22, 22a may be to increase the length of time during which the relevant output function is on for some period, and the device thereafter resuming its preset programme.This may be arranged so that, if the output function is off when the override or boost switch is operated, an immediate one-hour "on" period is initiated. if the output is already on, due to the preset programme, it may be arranged that the override switch will have no immediate effect but will add a further one-hour period to the "on" state from the moment at which the control would have been switched to "off" by the preset programme.

The front panel of the display device also has an auto/off switch 24. In the auto position the output functions are determined by the preset programmes. The output functions are in the "off" state continuously when the switch is in the off position, although the device may still have its indicating elements 6 functioning, at least to give a time-of-day display. As shown, the state of the switch 24 is indicated by its position, but it can additionally or alternatively have illuminated indicating means.

Fig. 3 is a block diagram of the electronic modules associated with the display panel already described. A power board 30 receives the mains input 32 and one or more load circuits 34, which may be at mains voltage or low voltage, are connected to the power board. The power board 30, also provides low volatage power through connections 36 to a main control board 38, from which a line 40 returns to it output function signals to control the load circuit outputs.

The low voltage power supply 36 is connected to a microprocessor 42 on the main board, from which the output function signals are produced. There are inputs to the microprocessor from the various time setting and control switches 8, 12, 14, 22 on the front panel, as well as from the programme selector switches 16a, and the microprocessor outputs to the various front panel indicating elements 6, 20, 22, and time display 4, this last being mounted on a display board 44. An emergency battery supply 46 is provided to allow the internal timing mechanism of the device to continue functioning in the event of a power failure, so that the time-of-day computation is contained, although there is no timeof-day display if this requires excessive power, and the storage means of the microprocessor continues to hold the manually adjusted time periods of the set programme.

Further details of the circuitry in this example of the invention are described in our copending application No 82. 01646 in which the preceding embodiment is also described and illustrated.

It will be understood that a programming device according to the present invention may be provided solely for the purpose of controlling an output heating function in response to sensed temperature, i.e. in the case of the embodiment described above the array 18a of hot water selector swtiches might be omitted.

Although described with reference to space heating, it can also be applied to the control of the temperature of solid or liquid masses.

Reference can be made to our copending application already mentioned above for other features and possible modifications that can be incorporated in a device according to the present invention, as for example the manner in which means can be provided for adjusting the time-of-day indication to a fractional part of the time period represented by each element of said display means, or for arranging a stand-by battery-powered means which, upon failure of said external input, is adapted to maintain the operation of computation means for the time-of-day display and of storage means for the adjustable time period values.

Claims (11)

1. Programming means for controlling heating and/or cooling means and comprising a programming device having an electronic circuit for producing output signals for programming the operation of said means, said circuit being arranged to operate in conjunction with adjustable timing means adapted to delineate adjustable time periods within a larger overall time period and with programming means for the delineated time periods, said programming means comprising at least one adjustable programming element assigned to each individual time period for setting a desired temperature level in that period, a thermosensitive element responsive to the temperature of a region or mass to be controlled by the programming device being arranged to provide an input signal to the electronic circuit dependent upon the temperature sensed by said element and the electronic circuit producing an output signal in dependence upon the differences between said sensed temperature and the temperature setting of the or each said adjustable element of the programming means in its assigned operative time period.

2. Programming means according to claim 1 having an analogue display means for displaying said overall time period and for indicating theron the elapsed time in a programme cycle and the time periods delineated by said timing means, and the adjustable programming element of the individual time periods being arranged as a group forming a configuration extending parallel to and adjacent said time display.

3. Programming means according to claim 2 wherein, for said temperature level adjustment, said programming elements are displaceable transversely to the direction of extent of at least the adjacent region of said configuration.

4. Programming means according to claim 2 or claim 3 wherein a common display means is provided for time-of-day and said adjusted time periods.

5. Programming means according to claim 4 wherein time-of-day and the adjusted time periods are arranged to be displayed simultaneously, and means are provided for distinguishing between the indications of time-of-day and said time periods.

6. Programming means according to any one of claims 2 to 5 having linear array of light-emitting elements for said analogue time display means, each representing a discrete time period.

7. Programming means according to claim 6 comprising means for adjusting the time-ofday indication to a fractional part of the time period represented by each element of said display means.

8. Programming means according to any one of the preceding claims wherein said thermosensitive device is provided with ad- justment means to alter its signal at a given sensed temperature in order to modify the electronic circuit output signal at a given setting of said at least one adjustable programming switch.

9. Programming means according to any one of the preceding claims comprising manual control means for override of a pre-pro rammed element setting to bring into operation a setting for a subsequent time period.

10. Programming means according to claim 9 comprising light-emitting means for indicating the actuation of said manual control means.

11. Programming means according to any one of the preceding claims arranged to be operated by an external power input and comprising a stand-by battery-powered means which, upon failure of said external input, is adapted to maintain the operation of computation means for the time-of-day display and of storage means for the adjustable time period values.

1 2. A programming device arranged for use in programming means according to any one of the preceding claims.

1 3. A combination of a programming device and at least one thermosensitive device, constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.