JPH0313498B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a control circuit for refrigeration and air conditioning equipment, particularly a pump interface for centrally controlling multiple units that share a water circuit using multiple transmission technology. It is about lock.

[Conventional technology]

FIG. 1 is a system configuration diagram including a conventional pump interlock circuit, in which 1 is a central command control unit (hereinafter referred to as the master unit), 2 to 5 are slave control units (hereinafter referred to as slave units), The base unit, the slave unit, and each other are connected by two-wire multiplex transmission technology to transmit information. Reference numeral 6 denotes a transmission circuit section, which is installed in each of the slave units 2 to 5, and is normally controlled by a microcomputer (not shown) or the like. Reference numeral 7 denotes an interface circuit for inputting the contact input signal 8 to the transmission circuit section, and is usually composed of a photocoupler (not shown) or the like for noise prevention. Reference numeral 9 denotes an excitation unit for detecting an interlock signal, which usually uses a relay and is connected to each child unit individually. Reference numeral 10 indicates a pump used in this water circuit, and as a pump driving part, 12a is a contact part of an electromagnetic switch, 12b is an excitation part of an electromagnetic switch, 10a is an electric motor for driving the pump, and 11a and 11b are overcurrent relay sensing parts. 13 shows a pump operation switch. Reference numeral 14 indicates an inlet pipe of the water circuit, and 15 indicates an outlet pipe, through which water flows in the direction of the arrow.

The conventional pump interlock circuit is configured as described above, and when the pump operation switch 13 is turned on, the excitation part 52P of the electromagnetic switch is excited, the contact part is turned on, and the pump drive motor is started. and the pump is also in operation. However, since the contact part 12a of the excitation part 52P is in the closed state, the excitation part (hereinafter referred to as relay excitation part) for detecting the interlock signal attached to each slave unit is excited.
All the contacts 8 are in the ON state, and the input is sent to the transmission circuit 6 via the interface circuit 7, so that the slave units 2 to 5 receive commands from the master unit in order.
operates the connected unit. Alternatively, the contact 8 was directly input to the interlock circuit for controlling the unit via an interface circuit to form an interlock between the unit and the pump.

However, since it is configured as above,
Although it is possible to connect between the master unit and slave units or between slave units using multiplex transmission technology, construction work is difficult because the connection wire for pump interlock is only routed around the unit. It was my fault. Furthermore, the microcomputer and the like constituting the transmission circuit 6 sometimes malfunctioned due to the noise generated by the relay for detecting the pump interlock signal.

In addition, if the control via transmission between the master unit and the slave unit does not cooperate well with the electrical pump interlock circuit, interlock contact 8 may fail even though the master unit is sequentially issuing start signals. Since the units are started at the same time, there are problems such as an excessive starting current caused by simultaneous starting of the units, which adversely affects the power supply.

[Summary of the invention]

This invention was made with the aim of improving this drawback, and proposes a system in which the pump interlock signal is multiplexed transmitted to the master unit by one slave unit, and the master unit allows the slave unit to operate. .

[Embodiments of the invention]

FIG. 2 is a system configuration diagram showing an embodiment of the present invention, and FIG. 3 is a detailed diagram of the system configuration diagram. The same reference numerals as in FIG. 1 indicate the same or the same functions as those in the conventional configuration diagram.

17 is a pump interlock signal input circuit that extracts a signal by directly applying the commercial power supply voltage, 18 is a large-capacity current limiting resistor, and 19 is a rectifier diode, which is half-wave rectified and smoothed by a smoothing capacitor 20. . 22 is a photocoupler current limiting resistor, 21 is a photocoupler, 21a is its light emitting section, and 21b is its light receiving switching section, which is input to the transmission circuit 6.

In the above configuration, the pump operation switch 13
When 17a and 17b are turned on, as in the conventional example,
A power supply voltage is applied to both ends of the photocoupler light emitting unit 21a, and the photocoupler light emitting unit 21a emits light, and in order to bring the switching unit 21b into a conductive state, the transmission circuit 6 of the slave unit 2 determines that the pump is operating, and sends a pump operation start signal to the parent unit. issue. Upon receiving this signal, the master unit sequentially issues operation commands to the slave units of each unit.

The system in the above configuration is explained in detail using the flow diagram shown in FIG. A “pump operation status investigation command” 23 is always transmitted from the master unit to the slave unit, and the slave unit transmits the “pump operation detection circuit 2”.
If a pump stop (off) signal is transmitted to the master unit in step 4, the unit prohibits operation of the unit in response to a "unit total stop command" 25. In addition, the slave unit operates the pump (on) by the "pump operation detection circuit" 24.
When the signal is transmitted to the master unit, the units are started in sequence, starting with unit No. 1, as shown in FIG.

Because of this control, the pump operation status detection circuit can be configured with just one unit, which is advantageous in terms of cost, and requires less wiring for pump interlocks.
It can be handled with only two wires, and the wiring for other control is
Since it can be handled with only two core wires for multiplex transmission, it is easy to construct and install.

Furthermore, since the pump operating state detection circuit does not use equipment having moving parts such as relays, it is advantageous in terms of noise characteristics and does not cause malfunctions of microcomputers or the like.
In addition, since it is configured with non-contact points, stable detection characteristics such as long life can be obtained.

By the way, the above explanation refers to the pump interlock, but if the circuit configuration uses multiplex transmission technology as a system, it can also process signals from peripheral devices that are not directly related to control, such as fire alarms and water leak detection. Needless to say.

〔Effect of the invention〕

As mentioned above, this invention has the effect of improving ease of construction and installation because it is configured to interlock the entire system by inputting a pump interlock signal to one slave unit and multiplexing the signal to the master unit. has.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional system configuration, FIG. 2 is a circuit diagram showing a system configuration according to an embodiment of the present invention, FIG. 3 is a detailed circuit diagram showing a part of FIG. 2, and FIG. The figure is a flow diagram showing one embodiment of the present invention. In the figure, 1 is a central command control device, 2 to 5 are slave control devices, 6 is a transmission circuit, 10 is a pump, 13 is a pump operation switch, and 17 is a pump interlock signal input circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 Connect multiple units that have a water circuit and supply cooling water using at least one pump or supply cooling water to secondary loads, and install each unit using multiplex transmission means using a central command and control device. In the case where the control is executed through the slave control device, only one slave control device is equipped with a pump interlock, and the pump interlock signal is multiplexed from this slave control device to the central command control device. 1. A control circuit for refrigeration and air conditioning equipment, characterized in that, at the same time as the central command and control device transmits, based on the multiplexed transmission signal, an operation enable signal is sent to the subordinate control circuits of each unit connected to the system.