ARRANGEMENT FOR THE TRANSFER OF CONTROL COMMANDS IN AN APPARATUS OR A MACHINE OPERATED FROM THE MAINS

Abstract: An arrangement in an apparatus or a machine operated from the mains for the transfer of control commands to at least one working means (24) in the apparatus or machine, e.g. a motor or the like, via a wire (13) also used for the power supply to said working means. The arrangement comprises a control unit (10) provided for creating a control command by suppressing, in a predetermined order, at least part of one or several consecutive half-periods of a predetermined polarity of the supply voltage. Moreover, the arrangement comprises a slave unit (11) operating in response to the control command transmitted to activate the working means (24). The control unit (10) has such a design that before a control command is transmitted the control unit operates to shortly disconnect the supply voltage on the wire (13) for a period of time required for the current in the working means (24) to decline essentially to zero.

Description: Arrangement for the transfer of control commands in an apparatus or a machine operated from the mains The present invention pertains to an arrangement in a apparatus or a machine operated from the mains for the transfe of control commands to at least one working means in sai apparatus or machine, e.g. a motor or the like, via a wire als used for the power supply to said working means, the arrange ment comprising a control unit provided for creating a contro command by suppressing, in a predetermined order, at least par of one or several consecutive half-periods of a predetermine polarity of the supply voltage, and a slave unit operating i response to the control command transmitted to activate th working means. In the U.S. patent publications Nos. 4,007,458 an 4,131,882 there are disclosed arrangements of the kind descri bed. Here, the arrangements have been used in irrigatio systems including a great number of valves and the object ha been to convey out, in a simple way by means of the powe supply cable, control commands for the control of the differen valves. If an arrangement of the kind described is to be used i an apparatus or a machine having several working means wit inductive properties, such as motors, difficulties hav appeared for the slave unit to interprete the control comman if being sent while any such inductive working means i operating. The change in a number of half-cycles, obtained b suppressing of at least part of the cycle, is counteracted b the repugnance of the working means against changes and as result the slave unit will experience difficulties in unam biguously identifying a control command being sent. The object of the invention is to remedy the drawbac indicated and to provide an arrangement of a desigh such tha the control commands transmitted can be unambiguously interpre ted by the slave unit for the correct control of the workin means to be operated. The object is achieved by an arrangemen of the kind referred to above which is characterized by such design of the control unit that before a control command is transmitted the control unit operates to shortly disconnect the supply voltage on the wire for a period of time required for the current in the working means to decline essentially to zero. The invention characterized above is the subject matter of the appending claim 1. Preferred embodiments have been included in the sub-claims. The invention will now be described more in detail in connection with an embodiment with reference to the enclosed drawings, in which: Fig. 1 shows a block diagram of the arrangement; Fig. 2 schematically shows a control unit according to the invention; Fig. 3 schematically shows a slave unit having a working means connected to it; and Fig. 4 and 5 show diagrams of waveforms of signals transferred between the control unit and the slave unit. In the embodiment the invention is intended to be used in a dishwasher the main function and design of which being con- ventional. Accordingly, no detailed description of the dish¬ washer will be given and said dishwasher will only be commented on in general terms when needed. Hence, such a- machine may comprise a dishwashing compartment supplied with water via a solenoid valve and drained of cleaning and rinsing liquid via a drainage pump. Further, in such machine a circulation pump is provided for the supply of cleaning and rinsing liquid to rotating spray-arms provided with holes and spraying liquid, in a conventional way, onto dish goods supported in baskets in the dish-washing compartment. For the dosage of detergent there is provided a dosing device which via a door, which can be opened by magnetic means, supplies a dose of powder from a dosage compartment covered by said door. Accordingly, the various working means which in this case have to be controlled by a programmer are the circulation pump, the drain pump, the dosage device and the solenoid valve. Preferably, in this case the programmer is of the electronic type comprising a microproces¬ sor, a program memory and additional electronic components required. In the following description the control components concerned have been removed from the dishwasher together wit one of the working means and these details are shown schemati cally in the block diagram of fig. 1. Accordingly, the contro arrangement comprises a control unit 10 and a slave unit 1 interconnected by a line 13, referred to as a bus line. In th line a triac switch 20 is connected by which the voltage to th slave unit 11 can be broken, either permanently or temporar when a control command is to be transmitted. A working means 2 is connected to the slave unit 11 via a triac switch 27. A shown in greater detail in fig. 2, the control unit consists o a microprocessor 14 which in a known way communicates, via a address bus 15 and a data bus 16, with a program memory 17. Vi terminals 18, 19 the bus line is connected to a mains A network and via the triac switch 20 the bus line is connecte to the slave unit 11. Said triac switch is controlled, via driver circuit 21, from the microprocessor 14. An opto couple 22 is used to supply phase information from the supplied A voltage to the microprocessor. In the usual way the micropro cessor is also connected to a clock pulse generator 23. The microprocessor 14 and the program memory 17 constitut an electronic programmer determining the function of th connected machine, here the dishwasher, said programmer als controlling the activation of the different working means, her represented by the load 24, see Fig. 3. The last-mentione figure shows the slave unit 11 which comprises an electroni circuit 25 referred to as EP310 PAL Altera. The circuit has tw inputs INI and IN2 of which INI is connected to a monostabl flip-flop 26. The flip-flop is triggered by each positive half period of the supply voltage generating pulses of a constan width. The second input IN2 of the circuit 25 is directl connected to the supply AC voltage and in a manner not dis closed in detail the circuit uses the positive half- periods o the input IN2 to be compared with the pulses on the input IN in order to determine the nature of the data informatio transferred, "1" or "0". The circuit 25 has a number of output Q0-Q4 to which the different loads are connected. In th example the only load 24 is connected to the output Q0 via triac switch 27. More or less sophisticated methods can be used in creatin a control command for activation or inactivation of one or several of a number of working means or loads. In a domestic appliance of the type dishwasher or laundry washing machine it is of great value, however, if codes are used which are as simple as possible. As a result the command for disconnection is equal to breaking of the voltage while the command for switching-on of a load is equal to a binary code activating the respective output of the circuit 25 in the slave unit. For activation of the outputs Q0-Q4 binary codes 10001, 10010, 10011, 10100 and 10101 are used where in each code the first "1" is a start bit. In the diagram of Fig. 4 there is shown the waveform of the supply voltage transmitted on the bus line with a control command for the output Q0 included. According to the invention, first the voltage is broken for a time period sufficient for all working means to be disconnected and all motors to be standstill. Then the voltage is switched-on for a shorter period to have the condition of the slave unit 11 stabilize. In the diagram this phase has been marked by the digit 1. Then follows the control command itself which starts with a start bit represented by a "1". The "1" is represented by a half-period of the supply voltage suppressed during 50% of its duration whereas a "0" is represented by a full half- period. In addition to the start bit, the control command comprises four additional bits and with respect to the output Q0 said command consists of three "0" followed by a "1". The real control command is shown in phase 2 of the diagram. In the following phase, marked 3, the supply voltage is completely unaffected representing the condition in which the working means is activated. Then, when the working means is to be disconncted, the supply of current is disrupted by opening of the triac switch 20. This phase has been designated by 4 in the diagram. In the diagram of Fig. 5 those pulses are shown which have been discussed above and are present in the circuit 25 as the result of the signals on inputs INI and IN2. The circuit 25 is provided with a shift register, not shown, which is being filled with the ones and zeros which represent the transmitted control command. When the start bit is present in a predetermi¬ ned position in the shift register the control command is retrieved and gated to the corresponding output, in this cas QO, via a logic network or the like, activating said output an the working means connected thereto. The connection takes plac by closing of a triac switch 27. The working means remain connected for a period determined by the electronic programme and when said period has lapsed disconnection takes place b the triac switch 20 being operated to take its open position It might be considered as a drawback that the curren supply has to be disrupted every time a new working cycle is t be initiated. However, practice has shown that the function o the machine has got no negative influence while at the sam time a control system has been achieved which is very simpl and which, as a result, can be manufactured at a low cost. I a dishwasher, and even more in a laundry washing machine, ther is a problem in that a great number of wires are needed for th connection of the different working means to one another and t the programmer. By using the arangement according to th invention most of the wiring otherwise needed will disappea and the number of signal wires is reduced to a minimum. The invention is not limited to the embodiment describe above and shown in the drawings and modifications can be mad within the scope of the inventive idea expressed in the claims Accordingly, both the control unit and the slave unit can b otherwise designed and with other components. The latter ha been shown as provided with a number of outputs correspondin to the number of working means to be connected. Instead, number of slave units can be provided where each slave unit i associated with one working means only. Further, the cod chosen can of course be modified in the desired way in accor dance with known code patterns and the control unit can b modified accordingly. Even though the invention has been mad to be used primarily in dish-washing and laundry washin machines it can of course be applied in all those apparatuse and machines where there is a need for control commands to b sent for the connection and disconnection of working mean having inductive properties.

Claims: C l a i m s 1. An arrangement in an apparatus or a machine operated from the mains for the transfer of control commands to at least one working means (24) in the apparatus or machine, e.g. a motor or the like, via a wire (13) also used for the power supply to said working means, the arrangement comprising a control unit (10) provided for creating a control command by suppressing, in a predetermined order, at least part of one or several consecu¬ tive half-periods of the supply voltage, and a slave unit (11) operating in response to the control command transmitted to activate the working means (24), characterized in that the control unit (10) has such a design that before a control command is transmitted the control unit operates to shortly disconnect the supply voltage on the wire (13) for a period of time required for the current in the working means (24) to decline essentially to zero. 2. An arrangement according to claim 1, characterized in that the consecutive half-periods of the AC supply voltage are of a predermined polarity. 3. An arrangement according to claim 1 or 2, characterized in that one end of the wire (13) is connected to' a mains AC network and that between said end and the slave unit (11) an electronic switch (20) is provided which disconnects the voltage to the slave unit (11) in response to a control signal from the control unit (10) both prior to the transmission of a control command and for generating of the suppression of predetermined half-periods forming the control command. 4. An arrangement according to any of the preceding claims, characterized in that the electronic switch (20) is a triac switch. 5. An arrangement according to any of the preceding claims, characterized in that essentially 50% of the positive half- period of the AC supply voltage is being suppressed to form one of the two binary states of a binary code forming the control command. 6. An arrangement according to claim 5, characterized in that the slave unit (11) comprises an electronic circuit (25) having two inputs (INI, IN2) and a number of outputs (Q0-Q4) corre- sponding to the number of working means (24), one (INI) of sai inputs being connected to a monostable flip-flop (26) t receive from said flip-flop a positive pulse of constant widt generated each time a positve half-period appears on the wir (13), while the other input (IN2) is directly connected to th wire, the electronic circuit (25) being designed so that comparison between the pulses from the flip-flop (26) an pulses generated by the circuit, in correspondance with th positive half-periods on the second input (IN2), decodes th transmitted control command. 7. An arrangement according to claim 6, characterized in tha the electronic circuit (25) comprises a shift register in whic the transferred command is introduced, wherein when a start bi of said command has taken a predetermined position in the shif register the code introduced in said shift register is cause to activate, via e logic network or the like, the output (Q0 that corresponds to said command. 8. An arrangement according to claim 7, characterized in tha the working means (24) is connected in series with an elec tronic switch (27) having a control input connected to th output (Q0) of the electronic circuit (25).

Inventors: AHLSE MARC ROLF, CASTWALL LENNART WILHELM, MOREN LARS GUNNAR, AHLSE, MARC, ROLF, CASTWALL, LENNART, WILHELM, MOREN, LARS, GUNNAR
Applicants: ELECTROLUX AB, AKTIEBOLAGET ELECTROLUX
Application year: 1993
Main classification: H02J13
IPC codes: H02J13, H02P29, H04Q9