EP0394654B1 - Time switch - Google Patents

Description

The invention relates to a time switch according to the preamble of claim 1.

Such a time switch is known as an electronic time switch from the Patent Abstracts of Japan, Volume 009, No. 186 (P-377) JP-A 60 056 287. The circuit, which contains a non-volatile RAM for its operating program, has a reserve voltage source for the failure of the operating supply. If this also fails, then the operating program must be set to the current time in order to be ready for operation again when it is ready for operation again; but the cited publication does not show how the time reference is obtained and how the time correction is carried out.

From EP-A 0 180 155 a consumer watch known in the art as an autonomous radio clock is known, in which the time display itself is operated from an internal time-keeping circuit (such as a quartz oscillator), but with the special feature that from time to time Receiver is switched on, which is tuned to a long-wave transmitter, via which a coded absolute time information is transmitted. The demodulated time information is compared with the currently displayed time and corrected in the event of deviations. The peculiarity of the radio clock described there lies in not letting the time display start at the start of operation, but first connecting one of the pointers in time with the received time telegram pulses in order to indicate whether there is currently undisturbed or disturbed reception.

In contrast, a radio-controlled traffic signal system according to EP-A 0 021 062 is not a radio clock in the present sense, in which successively received time information for the phase change is checked on the basis of an expected value in order to avoid incorrect controls. The light signal control there is based on constant radio contact with the timer center for retrieving the control information from a programmable read-only memory.

A time switch in the present sense, on the other hand, is used for the time-dependent switching on and off of consumers connected to its different switching channels. Such a timer is regularly equipped with a so-called power reserve for bridging temporary failures in the feed network. This ensures that the time switch continues to work at the correct time even during a network failure and thus normal network operation can be continued when the network is available again without having to readjust the time switch to the actually given, current point in time. The power reserve consists of a primary or secondary battery and a voltage-controlled switching device, via which the drive of the switching timer, which normally occurs from the mains, is switched to battery supply when the mains voltage falls below a minimum value required for operation, in particular if the mains due to mains malfunctions completely.

Such a time-buffered battery for the power reserve, but operated per se from the mains, is known, for example, from FUNKSCHAU issue 2/1982 (page 112 bottom left). The operating buffering of the built-in power reserve ensures that the actual switching mechanism is still operated in a time-keeping manner in the event of a power failure, and thus, when the power is available again, the load control is then carried out again at the specified times via the time switch.

A disadvantage of equipping a time switch with such a power reserve is, on the one hand, that two drive mechanisms are usually required to enable the time-dependent operation of the time switch either from a network and from a battery (with a regularly lower voltage), or quite right elaborate conversion circuits for the seamless transition of the drive device between different supply sources (see. DE-PS 1921520). And it is particularly problematic when using such a memory-buffered power reserve that the storage element no longer has the necessary capacity for the bridging operation due to signs of aging, if after several years of trouble-free network operation, emergency operation from the power reserve finally becomes necessary. The available storage (especially rechargeable batteries) that are considered for the power reserve have the very serious disadvantage that after a few years of aging they assume an internal short-circuit condition, ie they are no longer available as a bridging source. The short circuit can even lead to the failure of the time switch in spite of the existing or re-existing network. Particularly at high ambient temperatures, as can also occur in control cabinets, the lifespan of such storage units quickly drops to short remaining periods; on the other hand, low ambient temperatures lead to a greatly reduced capacity of the electrochemical storage.

In recognition of these circumstances, the object of the invention is to create a timer which is operationally resistant to a power failure and which does not require the relatively expensive and comparatively fault-prone memory for the conventional securing of a power reserve.

This object is essentially achieved in that the generic timer is designed according to the characterizing part of claim 1.

This solution is based on the knowledge that the load circuit (i.e. the consumer to be controlled depending on the actual time, such as a heater) cannot be operated anyway if its supply network - from which the controlling time switch is also operated - is not available . It is therefore sufficient to automatically put the consumer control system, which is based on the absolute time, back into operation at the correct time when the supply network again provides the operating power. However, according to the invention, any conventional power reserve based on the described bridging operation from a memory can be dispensed with entirely, if only it is ensured that when the network becomes available again, the time switch for its future operation will be corrected for the time actually given. This is done, for example, by means of a central time transmitter via wire (telecommunication or network lines), but preferably by means of a so-called radio clock (ie via a receiving and possibly display device synchronized by a time telegram radio transmitter), as described, for example, in EP-0S 0180155 . It decodes the instantaneous legal time from the radio telegrams transmitted via radio and uses this absolute time information to re-set the time register of an electronic time switch to be removed from the network or the gear train of a motor-driven clockwork.

In this way, the consumer is again controlled correctly when the network is available again and the current time can be decoded, to which the previous failure of the switch position control caused by the power failure is corrected; without the expensive and fault-prone memory for bridging the operation during the power failure.

Additional alternatives and further developments as well as further features and advantages of the invention result from the further claims and, also taking into account the explanations in the summary, from the following description of a preferred implementation example for the solution according to the invention, which is sketched in a highly abstracted manner while restricting it to the essentials.

The only figure in the drawing shows in the egg-pole block diagram a time switch with a radio clock operated by the same network for time control of a consumer fed from this network.

A consumer 11, for example a heating or lighting device, is to be switched on or off from the network 12 at predetermined times. For this purpose, the consumer 11 is connected to the network via the switching path 13 of a time switch 14. Their electromechanical or electronic time control device 15 can be adjusted via a manually operable non-volatile mechanical or electronic memory 16 (e.g. shift lever according to DE-0S 32 41 533 or EEPROMs) so that the switching path 13 is preferably at predetermined times with respect to the operation of the Timer 14 (that is, primarily not over predetermined time periods regardless of the actual times) is switched on or off.

The time switch 14 is not equipped with a power reserve for bridging temporary or system-related failures of the network 12. If the network 12 fails, the time switch 14 stops. The time-dependent control of the switching path 13 is thus interrupted; but this has no effect because, due to the lack of available energy in the network 12, the network-dependent consumer 11 cannot be operated anyway. The content of the non-volatile memory 16 for the predetermined switching times is retained. In the event of a power failure, or in any case before the switching control is resumed at the right time, a defined switching state is assumed in the output channels for the load control in order to avoid uncontrolled switching operations or undesired high-load conditions when the network is available again. Only when the current time has been decoded a few minutes after the mains voltage has returned and the time switch has been adjusted accordingly, the time-dependent, preset switching states are resumed in the channels. It can be provided to continue working with the interrupted program at the correct time; or the work cycles that failed during the interruption are rescheduled accordingly, for example in order not to miss any cooling phases in refrigeration technology.

If, in fact, the network 12 goes back into operation and the timer 14 starts up again, due to the previous functional standstill, the current activation of the switching path 13 may no longer match that which was actually stored for this point in time. In order to synchronize the time control with the actual time sequence again as quickly as possible, a radio clock 17 is provided as an adjusting device, from whose reception decoder 18 the time control device 15 is corrected to the current time received by radio. The radio clock 17 does not work autonomously either, so it can also be fed from the central network 12. Because as long as the network 12 has failed (and the radio clock is not operated as well), the consumer 11 cannot be operated anyway, so no switching operations need to be carried out.

When the network 12 is then available again, the radio clock 17 has immediately obtained the absolute time information for correcting the time switch position from the received time telegrams under normal operating conditions.

There are consumers 11 which evaluate time-dependent network control functions, in particular via their time switch control, the periodicity of the voltage on the network 12 (including time information). Then malfunctions cannot be completely ruled out, which can result from the fact that, due to the supply, the time information that can be derived for the time switch 14 from a fluctuating network 12 does not at least temporarily correspond exactly to the official time that can be determined via the radio clock 17. In order to avoid disturbances due to time differences, it is expedient, via a switch-on control circuit 19, which responds to the restarting of a network 12 that has been switched off, the radio clock 17 temporarily only for this reason (for setting the clock 14 to the actual current one Time) to be put into operation, and then to operate the time switch 14 again solely from the network 12. However, it can be provided that the switch-on control circuit 19 is also designed to check the current time position of the time switch 14 at greater intervals and, if necessary, to correct it if time deviations with regard to the actuation of the switching path 13 should have occurred due to operational faults (without an actual power failure).

Claims (3)

1. A time switch (14) having a time control mechanism (15) for a non-volatile store (16), in which different switching instants are presettable for different load switching sections (13), characterised in that the switching sections (13) with subsequent consuming devices (11) are fed from the same mains (12) as the time control mechanism (15) and as a radio-controlled clock (17), which at the start of the readiness for use of the mains and thereafter at fairly great intervals checks, and in the appropriate circumstances corrects, the current time position of the time switch (14), in which respect after a failure of the mains (12) the switching sections (13) have preset switching states or switching state sequences.
2. A time switch according to claim 1, characterised in that it is equipped with an adjusting mechanism which is operable by way of a switch-on control circuit (19) which is temporarily active upon re-availability of the mains (12).
3. A time switch according to claim 1 or 2, characterised in that upon re-availability of the mains (12) the switching programme that has been interrupted at least with respect to its switch-on phases of the switching sections (13) is recoverable in a time-shifted manner, before the preset switching sequence programme is further pursued at the correct time.

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