JPH0674940B2 - Defrost control device for open showcase - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a defrosting control device for removing frost adhering to a cooler in an open showcase for refrigerating and displaying products, and more specifically, a defrosting operation using a plurality of open showcases as one system. The present invention relates to a defrosting control device for an open showcase that synchronizes the operations.

[Prior art]

A conventional defrost control circuit is shown in FIG. The figure shows an example in which eight open showcases are used as one system and these open showcases are commonly connected to one refrigerator. FIG. 4 (A) shows one control circuit installed in each open showcase (the one in the first open showcase is shown), and FIG. 4 (B) shows eight open shows. The control circuit contained in the control panel common to the cases is shown. That is, each control circuit in FIG. 4 (A) is connected in parallel to the control circuit in FIG. 4 (B). First, in FIG. 4 (A), 1 is a defrost heater that melts frost adhering to a cooler (not shown), and 2 is a temperature control that performs ON-OFF operation by detecting the temperature of cold air circulating in the open showcase Thermostat (hereinafter referred to as "temperature control thermostat"), 3 is an electromagnetic valve inserted in a refrigerant pipe connecting the refrigerator and the cooler of the open showcase, and 4 is a defrost heater 1
A defrost thermostat that turns on by detecting the end of defrost from the temperature of the cooler heated by
X _D is a heater relay for energizing the defrost heater 1, x _D
Is its a contact, X is an auxiliary relay, xa and xb are the a contact and b contact of auxiliary relay X, respectively, and x _T1 is a timer relay X _T1
These are the C contacts, and they are connected to an AC200V power source as shown. Next, in FIG. 4 (B), 5 is a 24-hour timer that outputs a defrosting start signal to each open showcase. For example, as shown in FIG. 3, one day at 0:00, 4:00 and 8:00 To 3
Turn on contact _T for 30 minutes each time. When the contact _T turns ON,
Timer relays X _T1 ... X _T8 provided for each open showcase are energized all at once, and their respective c contacts (first
For the open showcase of x _T1 ) will switch at the same time. The operation of such a conventional configuration will be briefly described as follows. FIG. 4 (A) shows a normal cooling operation state, in which the temperature control thermostat 2 is turned on and off within predetermined upper and lower limit temperatures. When the temperature control thermo 2 is turned on, the solenoid valve 3 is opened and the refrigerant is supplied to the cooler to cool the inside of the open showcase. When the temperature control thermostat is turned off, the refrigerant is cut off and the cooling is interrupted. Therefore, when the timer 5 is turned on according to the time schedule shown in FIG. 3, the timer relay contact x _T1 shown in FIG. 4 (A) is switched and the relay X _D is energized. As a result, the a contact x _D turns on and the defrost heater 1
Is energized. When defrosting progresses and the temperature of the cooler rises, the differential thermostat 4 is turned on and the auxiliary relay X is energized. As a result, the b contact xb is turned off and the relay X _D is de-energized, and the contact x
_D is turned off and the power supply to the defrost heater 1 is cut off. At the same time, the a-contact xa is turned on, the relay X is held by itself, and the solenoid valve 3 is opened to restart the cooling operation.

[Problems to be Solved by the Invention]

As described above, in the conventional apparatus, the defrosting start time is synchronized, and defrosting starts at the same time for all the open showcases of the same system. However, the time when defrosting ends is left to each open showcase because it is left to the Def Thermo 4 of each open showcase. On the other hand, open showcases of the same system are connected to each other and arranged, and in that case, there is usually no partition between adjacent open showcases. Therefore, if the defrosting end time, that is, the cooling operation restart time is different as in the conventional case, and one of the adjacent open showcases is in the defrosting operation and the other is in the cooling operation, the open during the defrosting operation is performed. There is a problem that cold air enters the showcase to prevent defrosting, and warm air enters the open showcase during the cooling operation to raise the temperature of the inside of the warehouse and deteriorate the product. Therefore, an object of the present invention is to provide an open showcase defrosting control device in which not only the defrosting start but also the restart of the cooling operation is synchronized to eliminate the above-mentioned problems.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a defrosting control device for an open showcase including a timer that simultaneously outputs a defrosting start signal to a plurality of open showcases. Each open showcase is provided with a means for outputting a signal of, and a signal for suspending the start of the cooling operation is provided to all the open showcases when one of the signals indicating defrosting is input. Means for outputting the output.

[Action]

With the defrosting signal from the open showcase side, the restart of cooling operation of all open showcases is suspended,
When the defrosting signal disappears, the signal is first released to synchronize the restart of the cooling operation.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. In the case of the embodiment as well, it is assumed that one refrigerator is connected to eight open showcases to form one system. In a first diagram showing a control circuit mounted on each open showcase (A), during the defrosting operation as a means for outputting a signal to that effect, the signal a-contact x _D of the relay X _D heater is inserted circuit 6 is provided, the relay circuit 7 is provided further with a relay X _B. Relay x _B b contact x
_B is the auxiliary relay X a connected to the circuit connecting the solenoid valve 3 and the power supply.
It is inserted in series with the contact xa. On the other hand, the terminal 8 and the relay circuit 7 to which the signal circuit 6 is connected between the power supplies of the control circuit of FIG.
A direct circuit 11 including a terminal 9 to which is connected and a manual switch 10 is connected. The signal circuit 6 and the relay circuit 7 of each open showcase are connected in parallel to the terminals 8 and 9, respectively. Here, the relay circuit 7 including the b-contact x _B and the series circuit 11 send a signal for holding the start of the cooling operation to all open showcases even if one of the signals shown during defrosting is input from the open showcases. It constitutes means for outputting to. In such a configuration, the switch 10 is turned on in order to perform the control of the present invention. Now, for example, when the timer 5 is turned ON according to the time schedule of FIG. 3,
A defrosting start signal is sent to all the open showcases simultaneously via the timer relays X _T1 ... X _T8, and as described above, the defrosting operation is started in each open showcase. During the defrosting operation relay X _D is energized, so that a contact point x _D is turned ON, the signal shorts the terminal 8 is sent from the signal circuit 6 to the control panel. The terminal 8 is short-circuited, the relay X _B of the relay circuit 7 is energized, its contact b x _B opens the electromagnetic valve to OFF, the cooling operation is not performed. The signal circuit 6 of each open showcase is connected to the terminal 8 in parallel. Therefore, if any one of them is in the defrosting operation, the short-circuited state of the terminal 8 is maintained. And
As a voltage is applied to all of the relay circuit 7 through the terminal 9 in the case, the cooling operation is prevented relay X _B is energized. That is, even in the open showcase that has been defrosted, the restart of the cooling operation is suspended until the defrosting of all other open showcases is completed. When the last one completes the defrosting, the series circuit 11 is opened by the terminal 8 and all the open showcases restart the cooling operation all at once. FIG. 2 is a time chart showing this situation. That is, in FIG. 2, the defrost heater 1 is turned off at different timings for each open showcase, but when the eighth open showcase completes defrosting, all open showcases are simultaneously cooled. Have moved to. In addition, if any of the Def Thermo 4
Even if it does not turn on, the timer will turn off after 30 minutes, so restarting the cooling operation is not hindered. Also, if the switch 10 is turned off, the differential thermo 4 is turned on as in the conventional case.
If so, the operation of immediately shifting to the cooling operation can be performed.

【The invention's effect】

According to the present invention, not only the start of defrosting but also the start of cooling operation can be synchronized, so that cold air and warm air are disturbed between adjacent open showcases to prevent defrosting or the product deteriorates. Can be prevented.

[Brief description of drawings]

1 (A) is a circuit diagram of a control circuit on the open showcase side in the embodiment of the present invention, FIG. 1 (B) is a circuit diagram of the control circuit on the control panel side, and FIG. 2 is an embodiment of the present invention. 3 is a time chart showing an operating condition in an example, FIG. 3 is a time chart showing a defrosting schedule of a timer, FIG. 4 (A) is a circuit diagram of a control circuit on the open showcase side in a conventional example, and FIG. 4 (B). Is a circuit diagram of a control circuit on the side of the control panel. 1 ... Defrost heater, 2 ... Temperature control thermostat, 3 ... Solenoid valve,
4 ... Def Thermo, 5 ... Timer.

Claims (1)

[Claims] 1. A defrost control device for an open showcase, comprising a timer for simultaneously outputting defrosting start signals to a plurality of open showcases, comprising means for outputting a signal to that effect during a defrosting operation. Each open showcase is provided with a common means for outputting a signal for holding the start of the cooling operation to all the open showcases when any one of the signals indicating defrosting is input. A defrost control device for an open showcase, which is provided.