JPS633227B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention features a refrigerant circuit that connects a compressor whose compression capacity can be adjusted in multiple stages, a condenser, a pressure reduction device, and a user-side heat exchanger, and a refrigerant circuit that can change the air flow rate for cooling the condenser into multiple stages. The present invention relates to a control device for a refrigerator equipped with a blower. As shown in Fig. 1, this type of refrigerator includes a compressor 1 that is equipped with a capacity adjustment mechanism and whose compression capacity can be adjusted in multiple stages, a condenser 2 that performs a condensing action, and a pressure reducing device 3.
A refrigerant circuit 5 is constructed by connecting the heat exchanger 4 on the user side, which performs evaporation, to the condenser 2, and a plurality of blowers 6 for cooling are arranged in parallel to the heat exchanger 4 on the user side. is connected to a secondary refrigerant circuit 7 that exchanges heat with the evaporating refrigerant, and the cooled secondary refrigerant (for example, water) is circulated through the circuit 7 by a pump 8 and supplied to the fan coil 9. The fan coil 9 constitutes a chiller type air conditioner that cools the air in the conditioned room. The conventional control device detects the inflow temperature of the secondary refrigerant into the heat exchanger 7 on the user side and controls the compression capacity of the compressor 1 in multiple stages to perform capacity operation commensurate with the load and reduce the temperature around the condenser 2. By detecting the outside air temperature and selecting the number of operating blowers 6 according to the outside air temperature, an appropriate amount of cooling air can be obtained. However, when the air flow rate is increased due to a rise in outside air temperature, the pressure on the low pressure side of the refrigerant circuit 5 drops rapidly, and this state may continue transiently for 2 to 3 minutes, causing damage to the compressor 1 or damage to the secondary If the refrigerant freezes and damages the secondary refrigerant circuit 7, or if a pressure switch is provided to detect abnormally low pressure, there is a risk that the compressor 1 will stop and the cooling operation will not be able to continue. The present invention has been made in view of the above-mentioned facts, and is characterized in that the compressor is operated at a small capacity for a predetermined period of time when the condenser cooling fan is commanded to increase the amount of air blown, and the refrigerant circuit is improved by increasing the amount of air blown. It protects the refrigerant circuit including the compressor, the secondary refrigerant circuit, etc. by preventing a sudden drop in low pressure pressure, and also interrupts operation when selecting the condenser cooling air flow rate suitable for outside temperature fluctuations. It is an object of the present invention to provide a control device for a refrigerator that eliminates the risk of An embodiment in which the present invention is applied to the refrigerator shown in FIG. 1 will be described below. Figure 2 shows the control device, l is the operation switch 1
This is a bus bar to which a constant DC voltage is supplied via 0.
11 is a microcomputer, and power terminal B
is connected to bus line l, and an oscillator 12 that determines the free running time of the microcomputer is connected between clock terminals CL ₁ and CL ₂ . Reference numeral 13 denotes a secondary refrigerant measuring circuit to which a DC constant voltage is supplied from the bus line l, and which converts an analog signal of a temperature sensor 14 that detects the inflow temperature of the secondary refrigerant into the user-side heat exchanger 4 into a binary digital signal and outputs the signal. The output end is connected to the input port _I1 of the microcomputer 11. 15
is an outside temperature measuring circuit that is supplied with a DC constant voltage from the bus L and converts the analog signal of the temperature sensor 16 that detects the outside air temperature around the condenser 2 into a binary digital signal and outputs it, and the output terminal is the input terminal. Connected to port I ₂ . A reference pulse generator 17 generates a reference pulse of a predetermined frequency using a constant DC voltage supplied from the bus line I, and its output end is connected to the input port _I3 . 18 is a compressor control relay circuit consisting of a power supply control relay 19 for the drive motor (shown) of the compressor 1 and capacity adjustment mechanism control relays 20 to 22 for the compressor 1, one end of each relay being connected to the bus line l. , and the other ends thereof are connected to output ports _P1 to _P4 via drivers 23 each having an inverting function. Reference numeral 24 denotes a relay circuit for controlling the number of blowers in operation, which is composed of power supply control relays 25 to 27 for the blowers 6 for cooling the condenser, one end of each relay being connected to the bus line l, and the other end connected to a driver 28 having a reversing function. via output port P ₅ to P ₇
It is connected to the. Figure 3 shows the operation and internal system of the microcomputer 11, and shows the respective ports.
I ₁ , I ₂ , P ₁ to P ₇ correspond to the respective ports of the microcomputer shown in FIG. In this figure, 29 and 30 are storage devices, and 33 to 36 are timer devices, which are 60 seconds, 15 seconds, 30 seconds, and 3 seconds, respectively.
Count the seconds. Note that this timer device may be either a software device or a hardware device that counts reference pulses from the input port _T3 . 31, 32, and 37 are capacity setting means, air volume setting means, and control means, respectively, and their respective operations are determined by software (program). First, the storage devices 29 and 30 are the secondary refrigerant measuring circuit 1.
3 and the outside temperature measuring circuit 15 are inputted from input ports _I1 and _I2 , respectively, and stored as the latest temperature data. The capacity setting means 31 compares the temperature data in the storage device 29 with pre-stored setting data based on a program (not shown) and outputs a control signal of " ₁ " or "0" from the output ports P1 to _P4 . emits. That is, the capacity setting means 31 compares the secondary refrigerant inflow temperature of the user-side heat exchanger ₄ with the set temperature as shown in FIG. A control signal is issued from ₄ to control the compression capacity ratio of the compressor 1 in five stages from 0 to 100%. The air volume setting means 32 compares the temperature data in the storage device 30 with pre-stored setting data based on a program and sets " ₁ " from the output ports P5 to _P7 .
Alternatively, a control signal of "0" is issued. That is,
The air volume setting means 32 compares the outside air temperature with _the set value as shown in _FIG . In addition to controlling the air blow rate indicated by the number of operating units relative to the total number of units in three stages of 33%, 67%, and 100%, all the air blowers are stopped only when the first comparator 31 issues a command to stop the compressor 1. .

【table】

[Table] When the operation switch 10 is closed, the microcomputer 11 starts operating, and the measurement circuit 13,
The secondary refrigerant temperature and outside air temperature measured in step 15 are converted into binary data and stored in storage devices 29 and 30, respectively. Each data is then compared with the setting data in the first and second comparison devices 31 and 32 at the next stage. When the secondary refrigerant temperature is, for example, 14°C, as is clear from FIG.
is from output port P ₁ to P ₄ as shown in Table 1 [1,
1, 1, 1] is required to cause the compressor 1 to operate at 100% capacity. However, if the compressor 1 is operated at 100% immediately upon startup, the starting current will become extremely large and a load will be placed on the compressor, and there is also the risk of liquid returning to the compressor. According to the program at start-up, first output ports P ₁ to P ₄
A signal [1, 0, 0, 0] is emitted from the compressor, and only the control relay 19 is energized to start the compressor 1 at a small capacity operation of 25%, and a set command is issued to the timer device 33. When the timer device 33 finishes counting for 60 seconds and receives a time-up signal, the first
The comparator 31 has output ports P ₁ to P ₄ [1,
1,0,0] signal and control relay 19,20
The compressor 1 is operated at 50% capacity by energizing, and the timer device 34 is set. and
When 15 seconds have elapsed, the compressor 1 is operating at 75% capacity, and the timer device 35 is set, and when another 30 seconds have elapsed, the compressor 1 is operating at 100% capacity, completing startup. The state at this time is illustrated in FIG. 6. On the other hand, when the outside air temperature is 25°C, as _is clear from _FIG . It is required to control the blower 6 so that the air volume is 67%. In this case, the second comparator 32 first issues a set command to the timer device 36, and based on the time-up signal after 3 seconds, outputs signals [1, 0, ₀ ] from output ports P5 to _P7 to activate the relay 25. When energized, the number of operating blowers 6 is selected so that the air volume is 33%, and a set command is issued again to the timer device 36. After 3 seconds, a control signal of [1, 1, 0] is issued and the relay 2 is activated.
5 and 26 are energized, and the number of blowers 6... is increased so that the blowing volume is 67%. In this way, the starting currents of the compressor 1 and the blower 6 do not overlap, and the blowers themselves are started sequentially in groups, which alleviates the overlap of the starting currents. During this operation, the outside temperature rose and the time shown in Figure 6
When the Tx temperature exceeds 28°C, the second comparison circuit 32 is switched to the output port, as is clear from the characteristics shown in Figure 5.
A control signal [1, 1, 1] is issued from P ₅ to P ₇ so that all the relays 25 to 27 are energized, and the air blow rate of the condenser 2 is set to 100%, which causes all the blowers 6 to operate. Ensure sufficient cooling. At this time, the first comparator 31 is connected to the second comparator 32.
Check that the control signal has changed from [1, 1, 0] to [1, 1, 1], that is, that it has issued a control signal that increases the air flow, and then
Control signals from P ₁ to P ₄ [1, 1, 1, 1]
to [1, 0, 0, 0] and issues a set command to the timer device 33. Therefore compressor 1
As the air flow rate of the blower increases from 67% to 100%, the refrigerant circuit 5 operates at a small capacity of 25%, and the refrigerant circuit 5 is operated at a low capacity of 25% due to the sudden drop in high pressure. The refrigerant circuit 5 including the compressor 1 and the secondary refrigerant circuit 7
If an abnormally low pressure detection switch (not shown) is provided, it will not be activated and the cooling operation will not be interrupted. When the timer device 33 times up after 60 seconds,
The first comparator 31 returns the compressor 1 to 50% capacity operation. Also, a timer device 34 is set, and
After 15 seconds, the timer device 35 is set, and the compressor 1 eventually returns to its original value in the order of 25% → 50% → 75% → 100% at intervals of 60 seconds, 15 seconds, and 30 seconds, as shown in FIG. We will return to capacity operation. The timer device 33 used at startup in this way
35, the first comparator 31 operates the compressor 1 at a small capacity for a predetermined period of time (in this example, 60
seconds) to absorb low-pressure pressure fluctuations, and then gradually return to a control signal that matches the secondary refrigerant temperature data and set value in the storage device 29, so as to lighten the load on the compressor 1. There is. In addition, in the above embodiment, compressor 1 is 100%
The air flow rate is between 67 and 100.
I explained the case where it is switched to %, but it is 100%.
When switching the air flow rate from 33% to 67% when operating at a compression capacity of The same control will be performed for the timers 33 to 35, and the required number of timer devices 33 to 35 will be set. Further, the above-mentioned numerical values are not limited to these, and can be appropriately selected depending on the model used, the installation location, etc. Furthermore, the present invention has many modified embodiments in terms of compression capacity and means for adjusting the amount of air blown. As described above, the present invention allows the compressor to operate at a small capacity for a predetermined period of time when the condenser cooling blower is commanded to increase the amount of air blown, so that it is possible to prevent a sudden drop in the low pressure of the refrigerant circuit due to an increase in the amount of air blown. This protects the refrigerant circuit including the compressor, as well as the secondary refrigerant circuit, and prevents operation interruptions due to the activation of abnormally low pressure detection switches when selecting the condenser cooling air flow rate appropriate for the outside temperature. It can be avoided.

[Brief explanation of the drawing]

The drawings all relate to one embodiment of the present invention, and FIG. 1 is a refrigerant circuit diagram showing an example of a refrigerator to which the present invention can be applied, FIG. 2 is an electric circuit diagram of a control device, and FIG. 2 is a block diagram showing the internal system of the microcomputer used in FIG. 2, FIGS. 4 and 5 are diagrams explaining the characteristics of this device, and FIG. 6 is a diagram explaining the operation of this device. 1... Compressor, 2... Condenser, 3... Pressure reduction device, 4... User-side heat exchanger, 5... Refrigerant circuit, 1
1...Microcomputer, 15...Outside temperature measuring circuit, 31, 32...Comparison device, 33 to 3
5... Timer device.

Claims (1)

[Claims] 1 A compressor whose compression capacity can be changed, a condenser,
In a refrigerator control device that includes a refrigerant circuit that connects a pressure reducing device and a user-side heat exchanger, and a blower that can switch the air flow rate for cooling the condenser into multiple stages, capacity setting means for setting the compression capacity of the compressor based on the outside temperature; air volume setting means for setting the air flow rate of the blower based on outside temperature; and capacity setting means when the air flow setting value of the air flow setting means increases A control device for a refrigerating machine, comprising: control means for setting a set value of 1 to a low capacity set value for a predetermined period of time.