JPH0756421B2 - High-voltage controller for dual refrigerator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high pressure control device for preventing overload operation in a binary refrigerator.

(Prior Art) There is a known device disclosed in Japanese Patent Application Laid-Open No. 62-293051 for performing start control of a dual refrigerating machine, which starts while controlling the capacity of a high temperature side refrigerating circuit, and thereafter, When the low temperature side refrigeration circuit is started after a lapse of a predetermined time and the pressure of the low temperature side high pressure refrigerant reaches the set value, the capacity control on the high temperature side is released. There is a device disclosed in Japanese Patent No. 62-195053, which controls the capacity of the compressor on the high temperature side when the high pressure on the low temperature side becomes a predetermined value or less.

(Problems to be Solved by the Invention) Of the above two examples, the former can prevent the pressure increase at the time of start-up, but after starting the normal operation, the capacity control on the low temperature side is performed only by the pressure on the low temperature side. Since the high temperature side is operated at full capacity, the pressure fluctuation on the high temperature side is large in many cases and the operation is not performed in the optimum range, and the operation with low efficiency and energy saving cannot be expected.

On the other hand, the latter controls the pressure on the low temperature side by the capacity control on the high temperature side, but in this case as well, it is insufficient to maintain highly efficient operation on both the high temperature side and the low temperature side. This control is far from energy saving.

As described above, the conventional capacity control method is performed on the basis of one of the high temperature side and the low temperature side pressure, and the present invention has been made in view of the fact that it is not sufficient in terms of energy saving. In either case of steady operation after start-up, the high pressure of each refrigeration circuit will be in the optimum range by controlling the capacity of the compressor based on the high pressure of both the high temperature side and the low temperature side. Thus, it is an object of the present invention to maintain operation in an optimum state as a whole and to achieve high efficiency and energy saving.

(Means for Solving the Problem) The invention according to claim 1 has a first compressor (3) whose rotation is controlled by a first inverter (13), as shown in the embodiments of the accompanying drawings. A lower limit value (in the dual refrigerating machine which is cascade-connected to the high temperature side refrigeration circuit (1) and the low temperature side refrigeration circuit (2) having the second compressor (9) whose rotation is controlled by the second inverter (14) P _H1 ), the upper limit value (P _H2 ), and the intermediate value thereof, and the detected high pressure (P _H ) when pulling down the high temperature side refrigeration circuit (1) is compared with the detected pressure ( PH) generates a first speed-up signal, a first deceleration signal, and a first neutral signal depending on whether P _H ) is below, above, or within the set pressure band (15). If the lower limit value (P _L1) and the upper limit value (P _L2) and A set pressure band of the intermediate value, by comparing the pull-down time of the high pressure of the detected low temperature side refrigerating circuit ₍₂₎ (P L), or the detected pressure (P _L) is below the set pressure band , A low temperature side pressure detecting means (16) for respectively generating a second speed increasing signal, a second decelerating signal and a second neutral signal depending on whether the temperature is higher or within a band, the first neutral signal and the second neutral signal. The output for maintaining the current speed by the AND of the first deceleration signal and the second neutral signal, and the output for decelerating the predetermined width by the logical product of the first deceleration signal and the second speedup signal are An output for decelerating a width smaller than the predetermined width by the logical product of the signal and the second speed increasing signal is obtained by the logical product of the first speed increasing signal and the second neutral signal, and the first speed increasing signal and the second speed decreasing signal. An output for increasing the speed by a predetermined width is used as the first neutral signal and the second neutral signal.
The first inverter control means for providing an output to the speed increasing small width than said predetermined width in the logical product of the deceleration signal respectively generated by the first inverter (13) and (17 _A), the first neutral signal and a second neutral The output for maintaining the current speed by the logical product of the signals, the output for decelerating the predetermined width by the logical product of the first neutral signal and the second deceleration signal, and the first deceleration signal and the second deceleration signal is the first deceleration An output for decelerating by a logical product of the signal and the second neutral signal, which is smaller than the predetermined width, is used as a first neutral signal for the second speed increasing signal, and a logical product of the first speed increasing signal and the second speed increasing signal. The output for increasing the speed within a predetermined range is output by the first speed increasing signal and the second speed increasing signal.
_A second inverter control means (18A) for generating an output for increasing the speed smaller than the predetermined width by the logical product of the neutral signals and giving it to the second inverter (14). .

Next, claim 2 is the first inverter control means (17 _A )
However, when the second compressor (9) is operating at the lowest speed, both the first deceleration signal and the second deceleration signal are generated, and at the highest speed, the second compressor (9) A function for giving an output for decelerating a predetermined width to the second inverter (13) is added according to the condition that both the first speed increasing signal and the second speed increasing signal are generated during operation. According to a third aspect of the present invention, the second inverter control means (18
_A ) is a condition that both the first speed increasing signal and the second speed reducing signal are generated when the first compressor (3) is operating at the maximum speed, and the first compressor ( When 3) is in operation, the second decelerating output is output according to the condition that both the first deceleration signal and the second speedup signal are generated.
The feature is that the function given to the inverter (14) is added.

A fourth aspect of the present invention is a high temperature side refrigeration circuit (1) having a first compressor (3) whose rotation is controlled by a first inverter (13) and a second compressor whose rotation is controlled by a second inverter (14). A binary refrigerator having a low temperature side refrigeration circuit (2) having (9) in a cascade connection, wherein a set pressure band including a lower limit value (P _H1 ) and an upper limit value (P _H2 ) and an intermediate value thereof, and detection compared were the hot side high pressure after pulldown completion of the refrigeration circuit ₍₁₎ (P H), or the detected pressure (P _H) is below the set pressure band, or around the top, the upper around or band The high temperature side pressure detecting means (15) for respectively generating the first speed increasing signal, the first decelerating signal and the first neutral signal, the lower limit value (P _L1 ) and the upper limit value (P _L2 ) and Set pressure band consisting of intermediate values and detected low temperature side refrigeration circuit The high pressure (P _L ) after completion of pull-down in (2) is compared, and the second increase is made depending on whether the detected pressure (P _L ) is below, above, or within the set pressure band. The low temperature side pressure detecting means (16) for respectively generating the speed signal, the second deceleration signal and the second neutral signal, and the output for maintaining the current speed by the logical product of the first neutral signal and the second neutral signal Deceleration signal and second deceleration signal, first deceleration signal and second neutral signal, first deceleration signal and second speedup signal,
An output for decelerating a predetermined width by each logical product of the first speed-up signal and the second speed-up signal is decelerated by a logical product of the first neutral signal and the second speed-up signal by a width smaller than the predetermined width. Output the first
An output for increasing the speed of a predetermined width by each logical product of the speed-up signal and the second deceleration signal and the first speed-up signal and the second neutral signal is obtained by the logical product of the first neutral signal and the second deceleration signal by the predetermined width. the first inverter control means for supplying the first inverter and respectively generate an output to the speed increasing of narrow than (13) and (17 _B), the first neutral signal and a second neutral signal transmitted immediately after the pull-down completed Second inverter control means (18 _B ) for generating an output for maintaining the current speed by a logical product and giving the output to the second inverter (14).

The invention of claim 5 is the first inverter control means (1
_7B ) increases the speed of the first compressor (3) to the maximum speed with the output of the speed increase resulting from the logical product of the first speed increase signal and the second speed reduction signal, and then outputs the speed increase of the current speed. After decelerating to the minimum speed of the first compressor (3) with the output of deceleration based on the logical product of the first deceleration signal and the second speedup signal, the deceleration output is maintained. According to a fourth aspect of the present invention, the configuration is formed so that the output turns to stop.

(Operation) A claim 1, 2 or 3 is a high pressure control device at the time of pull-down which is performed in a state where the air temperature of the cooling target is out of the temperature band of the set temperature. By operating the refrigeration circuits (1) and (2) at a high pressure within the set pressure band by operating the compressor and conversely accelerating the compressor for the low one, operation under the capacity adapted to the load. Is done.

On the other hand, claim 4 or 5 is a normal operation in which the temperature of the air to be cooled is controlled so as to be maintained within the temperature band of the set temperature, and both refrigeration circuits (1) and (2) are set. The capacity of the first compressor (3) was controlled so that the high pressure was maintained in the pressure band, and the second compressor (9) was operated at the current capacity to adapt to the load. Driving under ability is completed.

(Example) Hereinafter, an example of the present invention is described based on an accompanying drawing.

In FIG. 1, (1) is a high temperature side refrigerating circuit, (2) is a low temperature side refrigerating circuit, and both circuits (1) and (2) are cascade-connected by a cascade capacitor (6) to provide a binary It constitutes a refrigerator.

The high temperature side refrigeration circuit (1) forms a refrigeration cycle by the first compressor (3), the condenser (4), the first expansion valve (5), and the low pressure side passage (7) of the condenser (6). The low temperature side refrigeration circuit (2) forms a refrigeration cycle by the second compressor (9), the high pressure side passage (8) of the condenser (6), the second expansion valve (10) and the evaporator (11). ing.

In addition, (12) shows an expansion tank branched and connected to the low pressure gas pipe of the low temperature side refrigeration circuit (2).

In the above dual refrigerator, the motor of the first compressor (3) is supplied with the variable frequency power from the first inverter (13), and the motor of the second compressor (9) is also the second inverter (14). ), A variable frequency power source is supplied, and both compressors (3) and (9) are subjected to capacity control by stepless speed control.

A control system for frequency conversion is provided for both inverters (13) and (14), but the one shown in FIG. 1 is a control system common to pull-down operation control and normal operation control. The pull-down operation control system among them is a high temperature side pressure detecting means (15), a low temperature side pressure detecting means (16),
It is provided with four means, a first inverter control means (17 _A ) and a second inverter control means (18 _A ).

The high temperature side pressure detection means (15) has a pressure detection part branched and connected to the high pressure gas pipe of the high temperature side refrigeration circuit (1) and detects the high pressure (P _H ) during pulling down to establish a set pressure band. By comparison, a first speed increasing signal is generated when the lower limit value (P _H1 ) is exceeded, a first neutral signal is generated when the upper limit value (P _H2 ) is exceeded, and a first deceleration signal is generated when the upper limit value (P _H2 ) is exceeded. To occur.

The low temperature side pressure detection means (16) has a pressure detection part branched and connected to the high pressure gas pipe of the low temperature side refrigeration circuit (2), detects the high pressure (P _L ) during pull-down and compares it with the set pressure band. However, a second speed increasing signal is generated when the lower limit value (P _L1 ) is exceeded, a second neutral signal is generated when the upper limit value (P _L2 ) is exceeded, and a second deceleration signal is generated when the upper limit value (P _L2 ) is exceeded. Occur.

The first inverter control means (17 _A ) and the second inverter control means (18 _A ) respectively include a logic gate circuit and an output circuit, and their functions are as shown in FIG.

That is, in FIG. 2, step (a), (b) is represents the operation of the high-temperature side pressure detection means (15), when the detected high pressure (P _H) rises above an upper limit value (P _H2) When the first deceleration signal and the lower limit value (P _H1 ) are exceeded, the first speed increasing signal and the first neutral signal within the set pressure band are generated, respectively.

On the other hand, steps (c) and (d) represent the operation of the low temperature side pressure detecting means (16), and when the detected high pressure (P _L ) exceeds the upper limit value (P _L2 ) the first deceleration signal,
If the lower limit value (P _L1 ) is exceeded, a second speed increasing signal and a second neutral signal are generated within the set pressure band.

Upon receiving each of these signals, the first inverter control means (17
_A ) is step (e), (f), (to), (h),
As shown in (i), (n), and (l), the first inverter (13) generates an output for acceleration and deceleration of a predetermined width, an acceleration and deceleration of a width smaller than that, and maintaining the current state.

In addition, the second inverter control means (18 _A ) has steps (f), (h), (h), (h), (h), (h), (h),
As shown in (W), the acceleration and deceleration of a predetermined width, the acceleration and deceleration of a narrower width than that, and the output for maintaining the current state are generated.

Thus, in both refrigeration circuits (1) and (2), the pull-down operation in which the high pressure is maintained within the set pressure band is stably performed under the capacity suitable for the load.

Then, when the second compressor (9) is reduced to the minimum speed due to the deceleration control (step (f)), when the first deceleration signal and the second deceleration signal are generated, the second compressor (9) is turned off. Since it is not possible to decelerate any more, the first compressor (3) is decelerated in step (Yo), and similarly the second compressor (9) is rising to the maximum speed in accordance with the speed-up control (Step (T)). If the first speed-up signal and the second speed-up signal are generated, the speed of the second compressor (9) cannot be increased any further, so the step (r) is used to decelerate the first compressor (3) to increase the high pressure. The pressure is balanced, which is the structure according to claim 2.

On the other hand, assuming that the first compressor (3) is operating at the maximum speed (step (so)) and the first speed increasing signal and the second speed reducing signal are generated, the first compressor (3) is operated. Since the speed cannot be increased any more, the second compressor (9) is stepped
Similarly, if the first compressor (3) is operating at the lowest speed (step (n)) and the first deceleration signal and the second speed increase signal are generated, the step (na ), The second compressor (9) is decelerated to balance the high pressure, which is the configuration according to claim 3.

By adding the configurations of claims 2 and 3 in this manner, the control range is further expanded.

Thus, during normal operation after the high pressure control of the pull-down operation has been performed and the air temperature of the cooling target has fallen to the set temperature band, the high pressure is adjusted by the capacity control of the first compressor (3) as shown in FIG. It's blaming.

The control system the hot-side pressure detecting means in this case (15), said cold-side pressure detection means (16), a first inverter control means (17 _B), comprising a fourth means of the second inverter control means (18 _B) ing.

Both the control means (17 _B ) and (18 _B ) are composed of a logic gate circuit and an output circuit, respectively, and their functions are as shown in FIG.

That is, when receiving one of the first deceleration signal, the first speed increasing signal and the first neutral signal and one of the second deceleration signal, the second speed increasing signal and the third neutral signal, the first inverter control means ( 17 _B) is as shown in step (e) - (Wa), a speed increasing with a predetermined width with respect to the first inverter (13), deceleration, slight speed increase than it generates an output of the reduction and maintaining the status quo.

On the other hand, the second inverter control means (18 _B ) uses the logical product (step (wa)) of the first neutral signal and the second neutral signal transmitted immediately after the completion of pull-down to output the output fixed at the speed at that time. 2 Give to the inverter (14).

In this way, both refrigeration circuits (1) and (2) can stably perform the normal operation in which the high pressure is maintained within the set pressure band under the capacity control suitable for the load.

However, when the first compressor (3) is reduced to the minimum speed due to the deceleration control (step (f)), if the first deceleration signal and the second speed-up signal are generated, then further Since it is not possible to decelerate, the first compressor (3) is stopped by step (Yo) to suppress the decrease of the low temperature side high pressure (P _L ), while the first compressor (3) is controlled by the speed-up control to the maximum. If the first speed-up signal and the second deceleration signal are generated when the speed is increased (step (ta)),
Since the speed cannot be increased any further, the maximum speed is maintained by step (re) so as to suppress the high pressure fluctuations further. This is the structure according to claim 5, and the control range is Expanded.

As it has been explained (Effect of the Invention) The present invention is high or low temperature side both refrigeration circuit of a binary refrigerating machine (1), each of the high pressure _(P H) of (2), _(P L)
Is detected and the capacities of the first compressor (3) and the second compressor (9) are controlled simultaneously so that both pressures do not fall out of the set pressure band. ), (9)
You can prevent overexertion and overexercise.

Claims 1 to 3 relate to high pressure control during pull-down, and since the capacities of both compressors (3) and (9) are controlled so that fluctuations in the overall capacity do not occur, load It is possible to increase the durability of the compressor by operating at an appropriate pressure with suitable capacity, and at the same time, the energy saving effect is significant.

Claims 4 and 5 relate to high-pressure control during normal operation after completion of pull-down, and both high-pressure pressures (P _H ),
Since the pressure control of (P _L ) is performed by the capacity control of the first compressor (3) on the high temperature side, the control system becomes extremely simple. Furthermore, since the refrigeration operation on the low temperature side is fixed, the cooling target The effect of stabilizing the cooling performance with a small temperature change range is further added.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are flow charts for explaining control aspects of the present invention. (1) …… High temperature side refrigeration circuit, (2) …… Low temperature side refrigeration circuit, (3) …… First compressor, (9) …… Second compressor, (13) …… First inverter, ( 14) ... second inverter, (15) ... high temperature side pressure detection means, (16) ... low temperature side pressure detection means, (17 _A), (17 _B) ...... first inverter control means (18 _A ), (18 _B ) ... second inverter control means,

Claims (5)

[Claims] 1. A high temperature side refrigeration circuit (1) having a first compressor (3) whose rotation is controlled by a first inverter (13) and a second compressor (9 which is rotation controlled by a second inverter (14). ), A low temperature side refrigeration circuit (2) having a cascade connection with a low temperature side refrigeration circuit (2), a set pressure band consisting of a lower limit value (P _H1 ) and an upper limit value (P _H2 ) and an intermediate value thereof, and a detected high temperature by comparing the pull-down time of the high pressure side refrigeration circuit ₍₁₎ (P H), or the detected pressure (P _H) is below the set pressure band, depending on whether it is within or band around the upper, first 1. High temperature side pressure detecting means (15) for respectively generating a speed increasing signal, a first decelerating signal and a first neutral signal, and a set pressure band consisting of a lower limit value ( _PL1 ), an upper limit value ( _PL2 ) and an intermediate value thereof. And when the detected low temperature side refrigeration circuit (2) is pulled down A second acceleration signal, a second deceleration signal, a second deceleration signal, depending on whether the detected pressure (P _L ) is below, above, or within the set pressure band by comparing with the high pressure (P _L ). The low temperature side pressure detecting means (16) for respectively generating the second neutral signal, and the output for maintaining the current speed by the logical product of the first neutral signal and the second neutral signal, the first deceleration signal and the second neutral signal, An output for decelerating a predetermined width by each logical product of the first deceleration signal and the second speed increasing signal, and an output for decelerating a width less than the predetermined width by a logical product of the first neutral signal and the second speed increasing signal. , A first neutral signal and a second neutral signal, and an output for increasing a predetermined width by the logical product of the first acceleration signal and the second deceleration signal, the first neutral signal and the second neutral signal.
The first inverter control means for providing an output to the speed increasing small width than said predetermined width in the logical product of the deceleration signal respectively generated by the first inverter (13) and (17 _A), the first neutral signal and a second neutral The output for maintaining the current speed by the logical product of the signals, the output for decelerating the predetermined width by the logical product of the first neutral signal and the second deceleration signal, and the first deceleration signal and the second deceleration signal is the first deceleration An output for decelerating by a logical product of the signal and the second neutral signal, which is smaller than the predetermined width, is used as a first neutral signal for the second speed increasing signal, and a logical product of the first speed increasing signal and the second speed increasing signal. The output for increasing the speed within a predetermined range is output by the first speed increasing signal and the second speed increasing signal.
_A second inverter control means (18A) for generating an output for increasing the speed smaller than the predetermined width by the logical product of the neutral signals and giving it to the second inverter (14). High-voltage controller for dual refrigerator. 2. The first deceleration signal and the first deceleration signal are both generated when the first inverter control means (17 _A ) is operating the second compressor (9) at the lowest speed. Conditions and when the second compressor (9) is operating at maximum speed, the first
The function for providing a second inverter (13) with an output for decelerating a predetermined width according to both conditions that both the speed-up signal and the first speed-up signal are generated. High-voltage controller for dual refrigerator. 3. _A second inverter control means (18 _A ) generates both a first speed increasing signal and a second speed reducing signal when the first compressor (3) is operating at the maximum speed. Condition, and when the first compressor (3) is operating at the lowest speed,
The binary according to claim 1 or 2, wherein a function for giving an output for decelerating a predetermined width to the second inverter (14) is added depending on the condition that both the deceleration signal and the second acceleration signal are generated. High-voltage control device for refrigerator. 4. A high temperature side refrigeration circuit (1) having a first compressor (3) whose rotation is controlled by a first inverter (13) and a second compressor (9 which is rotation controlled by a second inverter (14). ), A low temperature side refrigeration circuit (2) having a cascade connection with a low temperature side refrigeration circuit (2), a set pressure band consisting of a lower limit value (P _H1 ) and an upper limit value (P _H2 ) and an intermediate value thereof, and a detected high temperature by comparing the high pressure after pulldown completion of the side refrigeration circuit ₍₁₎ (P H), or the detected pressure (P _H) is below the set pressure band, depending on whether it is within or band around the top, High temperature side pressure detecting means (15) for respectively generating a first acceleration signal, a first deceleration signal and a first neutral signal, and a set pressure consisting of a lower limit value ( _PL1 ), an upper limit value ( _PL2 ) and an intermediate value thereof. Band and pull-down of detected low temperature side refrigeration circuit (2) The high speed pressure (P _L ) after completion is compared, and the second speed increasing signal, the second speed increasing signal, or the second speed increasing signal, depending on whether the detected pressure (P _L ) is below, above, or within the set pressure band. The low temperature side pressure detecting means (16) for generating the deceleration signal and the second neutral signal, respectively, and the output for maintaining the current speed by the logical product of the first neutral signal and the second neutral signal, the first deceleration signal and the second deceleration signal. Deceleration signal, first deceleration signal and second neutral signal, first deceleration signal and second speedup signal,
An output for decelerating a predetermined width by each logical product of the first speed-up signal and the second speed-up signal is decelerated by a logical product of the first neutral signal and the second speed-up signal by a width smaller than the predetermined width. Output the first
An output for increasing the speed of a predetermined width by each logical product of the speed-up signal and the second deceleration signal and the first speed-up signal and the second neutral signal is obtained by the logical product of the first neutral signal and the second deceleration signal by the predetermined width. the first inverter control means for supplying the first inverter and respectively generate an output to the speed increasing of narrow than (13) and (17 _B), the first neutral signal and a second neutral signal transmitted immediately after the pull-down completed pressure control apparatus for a two-stage cascade refrigerating machine characterized by comprising a second inverter control means for providing the second inverter to generate an output to be maintained at the speed of the current in the logical product ₍₁₄₎ (18 _B) . 5. The first inverter control means (17 _B ) comprises a first
After increasing the speed of the first compressor (3) to the maximum speed by the output of the speed increase by the logical product of the speed increase signal and the second speed reduction signal, the output of the speed increase is changed to the output for maintaining the current speed. On the other hand, after decelerating the first compressor (3) to the minimum speed by the output of deceleration by the logical product of the first deceleration signal and the second speedup signal,
The high pressure control device for a binary refrigerator according to claim 4, wherein the deceleration output is changed to an output for stopping.