JPS5937406B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration system equipped with a temperature controller that controls capacity in multiple steps by switching a compressor between loading and unloading operations.

Conventionally, for example, a heat pump type chiller consists of two refrigerant circuits, and a heat exchanger on the user side produces cold water or hot water as a heat exchange medium, and this cold water or hot water is sent to a fan coil indoors through piping. In a refrigeration system that performs air conditioning and heating, a two-step temperature controller is used to switch one compressor between load operation and unload operation during cooling operation, and the two steps of 100% and 50% are used. By controlling the capacity or using a 4-step temperature controller, the two compressors can be switched to load operation and unload operation, respectively, to achieve 100% (both compressors operate at 100%) and 75%. (one compressor running at 100%, the other running at 50%), 50% (both compressors running at 50%), and 25% (one compressor running at 50%, the other stopped). A device in which the capacity is controlled in four steps is known.

By the way, conventionally, as mentioned above, 100%, 75%, 50%
% and 25%, especially during cooling operation, when the capacity is switched and the 10%
0% to 75%, 75% to 50%, or 50%
When the step decreases by one step from % to 25%, the temperature of the cold water produced by the user-side heat exchanger rises rapidly immediately after switching, regardless of the load.

This phenomenon is especially noticeable when the amount of water is very small.
Water temperature rises rapidly in a short period of time.

Therefore, in order to prevent a short cycle from occurring, the differential of the temperature regulator needs to be set large enough to cope with the rapid temperature rise when the amount of water is small.

For example, when controlling the capacity based on the water temperature at the pipe outlet of the cold water produced by the user-side heat exchanger, it is necessary to set the differential at 4°C.

Therefore, there was a problem in that the ability to follow the load deteriorated, and in particular, it was impossible to follow sudden changes in the load.

Therefore, the present invention has been made in view of the above points, and in a refrigeration system equipped with a temperature regulator that controls the capacity in multiple steps as described above, the present invention continuously detects the water temperature and controls the range of temperature change of the cold water. The capacity will not be increased during a certain period of time when the water temperature is rapidly rising due to switching of the capacity control width, and the capacity will be increased when the temperature change width in a steady state after a certain period of time reaches or exceeds the set temperature. In this way, it is an object of the present invention to provide a refrigeration system that has good load followability without causing short cycles.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Figure 1 shows, for example, a heat pump type chiller consisting of two refrigerant circuits, in which cold water or hot water, which is the heat exchange medium, is produced by a heat exchanger on the user side provided in common for the two refrigerant circuits, and this cold water or hot water is In a refrigeration system that has two air-cooled heat source side heat exchangers that send heat to indoor fan coils via piping to perform cooling and heating, two corresponding fans, and two compressors, the two compressors Switch the machine to load operation and unload operation, and the capacity control width is 25.
2 is a circuit diagram of a 4-step temperature regulator when applied to a refrigeration system equipped with a 4-step temperature regulator that controls capacity in the first to fourth steps of %, 50%, 75%, and 100%.

That is, in the four-step temperature regulator shown in Fig. 1, 1 is a temperature sensor composed of a thermistor that continuously detects the temperature of the cold water produced by the heat exchanger on the user side of the heat pump chiller, and 2 is the This is an A/D converter that converts the detection signal voltage of the temperature sensor 1 into a digital value detection signal.

3 receives the detection signal voltage of the temperature sensor 1 and outputs it when the detection signal voltage matches a set voltage value corresponding to the water temperature preset by the cooling water temperature regulator 4 that sets the temperature of the cold water. This is a thermostat that outputs a capacity down signal from the first single shot 5 connected to the side.

6 is cleared via the OR circuit 7 by a capacity down signal from the thermostat l-3 or a capacity up signal to be described later, and operation is started by the operation switch 8 which is closed after a set time (for example, 1 minute) and at startup. This is a timer that later outputs a storage command signal from the second single shot 9.

Further, 10 receives a storage command signal from the timer 6,
11 is a storage circuit configured with a latch that stores a detection signal from the temperature sensor 1 that is converted into a digital value by the A/D converter 2 upon receiving the storage command signal;
is the memory circuit 1 based on the detection signal from the temperature sensor 1.
12 is a calculation unit that performs calculations to subtract the detection signal stored in 0 and outputs a difference signal, and 12 is preset by the difference signal of the calculation unit 11 and a switch 13 etc. that sets when the temperature of the cold water is rising. The third single shot 14 is compared with the set temperature range signal corresponding to the temperature change range of the chilled water, and when the difference signal becomes equal to or larger than the set temperature range signal, the third single shot 14
This is a comparator that outputs a capacitance increase signal from.

Further, 15 receives the output signal from the timer 6 and delays the output signal by the total operating time of the second single shot 9, the memory circuit 10, the arithmetic unit 11, and the comparator 12. Delay circuit 1 that outputs
6, a flip-flop circuit 17 which receives the delayed signal of the delay circuit 16 and outputs a hold signal, and the comparator 1.
AND circuit 1 which is interposed between 2 and the third single shot 14 and receives the hold signal of the flip-flop circuit 17.
8, and prevents the comparator 12 from outputting the capacitance up signal from the third single switch 14 for the total time of the timer 6 and the delay time of the delay circuit 16. It is.

Further, 19 has bits corresponding to 100%, 75%, 50%, 25% and stop capacity control, and receives a capacity up signal from the comparator 12 and shifts the output bit, for example, to the right. 20 is a shift register that shifts the output bit, for example, to the left in response to the capacity down signal 20, and 20 encodes the output from the output bit of the shift register 19 into a preset form, and controls the capacity corresponding to the output bit. This is a decoder that controls the refrigeration equipment.

As described above, the four-step temperature regulator is configured.

In addition, 21 is an OR circuit that operates the thermostat 3 by the capacity up signal of the comparator 12 or the output signal of the timer 6, and 22 is the cooling water temperature regulator 4 that receives the output signal from the thermostat 3 and adjusts the start-up water temperature of the thermostat 3. A preset circuit 23 presets the output bit of the shift register 19 to a bit corresponding to 100% when the water temperature is higher than the water temperature set by , and a bit corresponding to stop when the water temperature is lower than the water temperature set by . When the output bit of the shift register 19 is a bit corresponding to 100%), an inverted signal obtained by inverting the output signal of the output bit is received via the NOT circuit 24, and the shift register 19 is inverted by the capacitance up signal of the comparator 12. AN to prevent the output bits of from being shifted to the right
The D circuit 25 is a NOT circuit 26 when stopped (when the output bit of the shift register 19 is a bit corresponding to stop).
27 and 28 are thermostats each receiving an inverted signal that inverts the output of the output bit through an AND circuit and inhibiting the output bit of the shift register 19 from being shifted to the left by the capacitance down signal of the thermostat 3. 3 and the preset circuit 22, and closes at startup to close the thermostat 3 and the preset circuit 22.
This is the operation switch that activates the

Next, to explain the operation of the four-step temperature regulator, the temperature sensor 1 continuously detects the temperature of the cold water produced in the user-side heat exchanger (not shown), and the temperature sensor 1 detects When the signal voltage and the set voltage set by the cooling water temperature regulator 4 match (when the chilled water temperature and the set water temperature match), the thermostat 3 outputs a capacity down signal from the first single shot 5, and By inputting the capacitance down signal to the shift register 19 and shifting the output bit one step to the left, the capacitance control width corresponding to the bit is lowered by one step, and the output of the output bit is encoded by the decoder 20.

For example, when the output bit is a bit corresponding to a capacity control width of 50%, the first and second fans for the air-cooled heat source side heat exchanger are turned on, the first and second compressors are turned on, and The first and second unload valves are turned on and the refrigeration system is immediately operated at a capacity control width of 50%.

On the other hand, the capacitive amplifier signal output from the thermostat 3 is input to the timer 6 via the OR circuit 7, and when the timer 6 is cleared, the flip-flop circuit 1
7 resets.

By resetting this flip-flop circuit 17, the AN
The D circuit 18 prevents the comparator 12 from outputting the capacitive amplifier signal.

Thereafter, the timer 6 counts up after a set time (one minute), and the output signal of the timer 6 is combined via the delay circuit 16 for the delay time of the delay circuit 16 and input to the flip-flop circuit 17. flip-flop circuit 1
By setting 7, the flip-flop circuit 1
7 allows a capacity up signal to be output.

On the other hand, the count amplifier of the timer 6 causes the timer 6 to output the storage command signal from the second single shot 9 to the storage circuit 10, and the storage circuit 10 receives the detection signal from the temperature sensor 1 when receiving the storage command signal. remember,
The arithmetic unit 11 subtracts the detection signal stored in the storage circuit 10 from the detection signal of the temperature sensor 1 and inputs the difference signal to the comparator 12 .

Then, when the difference signal becomes equal to or larger than the preset set wetness width signal by the comparator 12, a capacity up signal is output from the third single shot 14 to the shift register 19, and the shift register The output bit of No. 19 is shifted one step to the right to increase the capacity control width corresponding to the bit by one step, and the output of the output bit is encoded by the decoder 20 to operate the refrigeration system with the capacity control width increased by one step.

Therefore, in the embodiment, when the water temperature detected by the temperature sensor 1 drops during cooling operation and reaches the water temperature value set by the cooling water temperature regulator 4 of the thermostat 3, the thermostat 3 immediately outputs a capacity down signal. As a result of the capacity down signal, cooling operation is immediately started with the capacity control width being lowered by one level.

Furthermore, after the capacitance control width is lowered by one stage, the flip-flop circuit 17 is reset by the set time (1 minute) because the timer 6 is cleared by the capacitance down signal, and the flip-flop circuit 17 is reset. Therefore, no output appears from the AND circuit 18, and the AND circuit 18
This prevents the comparator 12 from outputting the capacitance up signal from the third single shot 14.

Therefore, the capacity control width will not increase only during the set time of 1 minute (during the time when the water temperature is rapidly increasing due to lowering the capacity control width by one level), and the water temperature will not increase rapidly. No short cycle will occur as a result.

Furthermore, in the steady state after the set time after the rapid rise of the song, the flip-flop circuit 17 is set due to the timer 6 counting up, and the comparator 12 is connected to the third single signal via the AND circuit 18. This allows the yacht 14 to output a capacity up signal.

As a result, when the water temperature detected by the temperature sensor 1 gradually rises and reaches the temperature set by the switch 13 of the comparator 12, the third single shot is sent from the comparator 12 via the AND circuit 18. A capacity up signal is output from 14.

Therefore, the capacity can be controlled even during a small temperature rise, and the load followability can be improved, and the water temperature can be kept almost constant.

Furthermore, the annual energy efficiency ratio (ratio of annual capacity to annual power consumption; 5EER) can be improved by reduction during temperature rise and prevention of short cycles.

Further, in the above embodiment, the case of a 4-step temperature controller during cooling operation was described, but the present invention provides a 4-step temperature controller during heating operation.
It can also be applied to a step temperature controller, in which case it is necessary to switch the operation of the thermostat 3, computing unit 11, and preset circuit 22 for heating.

In addition, in the above embodiment, a case has been described in which a four-step temperature controller is used for two compressors to control the capacity in the first to fourth steps, but a two-step temperature controller is used for one compressor. The present invention can be similarly applied to the case where the capacity is controlled in two steps of 50% and 100%.

As explained above, according to the refrigeration apparatus of the present invention, the temperature sensor detects the temperature of the heat exchange medium of the heat exchanger;
A thermostat that outputs a capacity down signal when the detection signal voltage of the temperature sensor matches a set voltage value corresponding to the set medium temperature, and a timer that is cleared by the capacity down signal of the thermostat and outputs a storage command signal after a set time. a storage circuit that receives the storage command signal of the timer and stores the detection signal from the temperature sensor at the time of receiving the storage command signal; and a storage circuit that stores the detection signal stored by the storage circuit and the detection signal from the temperature sensor. a comparator that outputs a capacitance up signal when the difference signal is at or above a set temperature corresponding to a preset temperature change range; and a comparator that prevents the comparator from outputting the capacitance up signal for a time approximately equal to the set time of the timer. As soon as the temperature of the medium reaches the set temperature, the capacity control step is lowered by one step by a capacity down signal, and after the capacity control step is lowered by one step, the current state is stopped for a set time. By maintaining the capacity control step and increasing the capacity control step by one step by a capacity up signal when the medium temperature changes beyond the set temperature after the set time has elapsed, short cycles are reliably prevented. Since the range of temperature change of the cold water can be set small, it is possible to improve the ability to follow the load.

In addition, it is possible to stabilize water temperature and improve annual energy efficiency.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of the present invention, Figure 1 is a block diagram of a 4-step temperature controller, Figure 2 is a diagram showing the temperature change characteristics of cold water, and Figure 3 is a conventional example. This is a diagram equivalent to Figure 2. 1...Temperature sensor, 3...Thermostat, 4...Cooling water temperature regulator, 6...
...Timer, 10...Memory circuit, 11...
...Arithmetic unit, 12...Comparator, 13.
... Switch, 15 ... Blocking circuit, 16
...Delay circuit, 17...Flip-flop circuit, 18...AND circuit, 19...
...Shift register, 20...Decoder.

Claims (1)

[Claims] 1 A temperature sensor 1 that detects the temperature of the heat exchange medium of the heat exchanger, and a thermostat 3 that outputs a capacity down signal when the detection signal voltage of the temperature sensor 1 matches a set voltage value corresponding to the set medium temperature. , the thermostat 3
a timer 6 which is cleared by a capacity down signal of and outputs a storage command signal after a set time; and a memory which receives the storage command signal of the timer 6 and stores the detection signal from the temperature sensor 1 at the time of receiving the storage command signal. circuit 10;
a comparator 12 that outputs a capacitance increase signal when a difference signal between the detection signal stored in the storage circuit 10 and the detection signal from the temperature sensor 1 is equal to or higher than a set temperature corresponding to a preset temperature change; A temperature regulator is provided with a blocking circuit 15 that prevents the comparator 12 from outputting a capacity up signal for a time approximately equal to the set time of the timer 6, and the temperature regulator increases the capacity as soon as the temperature of the heat exchange medium reaches the set temperature. While the capacity control step is lowered by one step by the down signal, the current capacity control step is maintained for a set time after lowering the capacity control step by one step, and after the set time has elapsed, if the medium temperature changes by more than the set temperature, the capacity is lowered. A refrigeration system characterized in that a capacity control step is raised by one step by an up signal.