JP2508043B2 - Compressor capacity control device for refrigeration equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor capacity control device for a refrigeration system, and more particularly to measures for preventing deterioration of durability due to frequent capacity changes of the compressor.

(Prior Art) Conventionally, as a compressor capacity control device for a refrigeration apparatus of this type, as disclosed in, for example, Japanese Patent Laid-Open No. 59-56649, a compressor whose capacity is adjusted by an inverter in an air conditioner. It is known to provide comfortable air conditioning in the room by controlling the capacity of the compressor with an inverter in accordance with changes in the air conditioning load in the room to appropriately adjust the air conditioning capacity to the air conditioning load. .

(Problems to be solved by the invention) By the way, when controlling the capacity of the compressor to increase or decrease, if the number of stages of change in the capacity is set in multiple stages, the refrigerating capacity can be better responded to the refrigerating load and the refrigerating performance is improved. Can be achieved, which is preferable.

Therefore, for example, two compressors are provided, the capacity of one compressor is controlled by an inverter, and the capacity of the other compressor is controlled by an unload mechanism, so that the total capacity of both compressor mechanisms becomes almost the target capacity value. By controlling the total capacity of the compressor at a relatively low price, the total capacity can be adjusted in multiple stages to improve the refrigeration performance.

Therefore, when the total capacity of the compressors is adjusted in multiple stages in this way, one of the compressors is relatively finely adjusted by the inverter, for example, the capacity is adjusted in steps of 10%, and the other compressor is, for example, 50% by the unload mechanism. The capacity is relatively adjusted to 100% and 100%. Therefore, for the adjustment control of the total capacity of the compressor, for example, the basic capacity value is set by the compressor on the unload mechanism side, and the capacity on the inverter side is set to a capacity approximately equal to the capacity difference between the basic capacity value and the target capacity value. The total capacity of the compressor is adjusted to a target capacity value by adjusting and controlling the machine.

However, in that case, if the target capacity value changes according to changes in the refrigeration load, for example, the target capacity value is 40% and 50%.
, The compressor on the side of the unloading mechanism repeatedly starts and stops at a capacity between 0% and 50%, which lowers the durability of the compressor. Then, there arises a drawback that the reliability is lowered.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the capacity of a compressor on the unload mechanism side when the capacity of two compressors is controlled by an inverter and an unload mechanism as described above. By keeping the state as long as possible and increasing / decreasing the total capacity of the two compressors to make it converge to the target capacity value, the start / stop frequency of the compressor on the unload mechanism side can be adjusted as much as possible. The refrigerating capacity can be adjusted in multiple stages while improving the durability while improving the refrigerating performance.

(Means for Solving the Problem) In order to achieve the above-mentioned object, a concrete solving means of the present invention is, as shown in FIG. The first compressor (1) to be adjusted and the unload mechanism (2a) make it larger than the step width of the first compressor (1) and the capacity adjustment range of the first compressor (1). Second, the capacity is adjusted to multiple steps with a smaller step width
The compressor capacity control device for a refrigerating machine is premised on which the total capacity of both compressors (1) and (2) is controlled in multiple stages. Then, the target capacity calculating means (50) for calculating the total target capacity (L1) of the compressors (1) and (2) and the output of the target capacity calculating means (50) are received, and the total target capacity (L1) is received. And a control means (51) for controlling the inverter (15) and the unload mechanism (2a) so as to adjust the total capacity of the compressors (1), (2) to a capacity at a stage close to. Further, when the total target capacity (L1) calculated by the target capacity calculating means (50) is increased and the capacity of the first compressor (1) is less than the vicinity of the maximum value, the first compressor (1 ) Is sequentially increased to adjust the total capacity of both compressors (1) and (2) to the total target capacity (L1), and the capacity of the second compressor (2) is less than the maximum value. When the total target capacity (L1) further increases after the capacity of the first compressor (1) has increased to near the maximum value, the capacity of the second compressor (2) is increased by one step, and The capacity of the first compressor (1) is calculated from the capacity of the second compressor (2) for one step.
The total capacity of both compressors (1) and (2) is reduced by the capacity of one step of
While adjusting to 1), when the total target capacity (L1) decreases, if the capacity of the first compressor (1) exceeds the vicinity of the minimum value, only the capacity of the first compressor (1) is sequentially Decrease and adjust the total capacity of both compressors (1), (2) to the total target capacity (L1), and when both compressors (1), (2) are operating, the first compressor ( When the total target capacity (L1) further decreases after the capacity of 1) is reduced to near the minimum value, the capacity of the second compressor (2) is decreased by one step, and the first compressor (1) By increasing the capacity of the first compressor (1) by subtracting the capacity of one step of the second compressor (2) from the capacity of one step of the second compressor (2). Total capacity of 2) total target capacity (L1)
The configuration is adjusted to.

(Operation) According to the present invention, according to the present invention, when the total target capacity (L1) of the compressors (1) and (2) is calculated by the target capacity calculating means (50) during the refrigerating operation, the first compression is performed. Since the capacity of the machine (1) is controlled by the inverter (15) by the control means (51) and the capacity of the second compressor (2) is controlled by the unload mechanism (2a) by the control means (51), Even when the above total target capacity (L1) is finely set in multiple stages, the total capacity of both compressors (1) and (2) is approximately the above target capacity (L1).
The refrigeration performance is improved by adjusting the temperature in accordance with.

In that case, the capacity of the second compressor (2) on the side of the unloading mechanism (2a) does not become, for example, 100% near the maximum value of the capacity of the first compressor (1) on the side of the inverter (15). Since there is no increase or change, for example, the total target capacity (L1) is 50
% Fluctuates between 60% and 60%, only the capacity of the first compressor (1) changes between 50% and 60% and the second
The capacity of the compressor (2) is 0% (stopped state). Then, for example, the total target capacity (L1) is 100% to 110
%, That is, the capacity of the first compressor (1) is 10
After reaching 0%, the capacity of the second compressor (2) is adjusted to 50% by the unload mechanism (2a), and
The capacity of the compressor (1) is adjusted to 60% by the inverter (15), and its total capacity matches the total target capacity (L1) of 110%.

Then, even if the total target capacity (L1) drops below 100%, the capacity of the second compressor (2) is maintained at 50%, and by the decrease control of the capacity of the first compressor (1). The total capacity is adjusted down to the target capacity (L1). After that, when the capacity of the first compressor (1) drops to around 30% near the minimum value, that is, when the total target capacity (L1) drops from 80% to 70%, the second compression The capacity of the machine (2) is 0%
The first compressor (1) is adjusted to (stop state)
The capacity of will be adjusted to 70% by the inverter (15) and will match the total target capacity (L1). The case where the capacity of the second compressor (2) changes between 0% and 50% has been described above, but the same applies to the case where the capacity of the second compressor (2) changes between 50% and 100%.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings starting from FIG.

FIG. 2 shows an embodiment in which the present invention is applied to a multi-type air conditioner, (A) is an outdoor unit, and (B) to (F).
Are five indoor units having the same internal configuration, and inside the outdoor unit (A), a first compressor (1) and a second compressor (2) connected in parallel to each other, and a four-way A switching valve (3), an outdoor heat exchanger (4) having an outdoor blower fan (4a), and an expansion valve (5) are provided, and the respective devices (1)
To (5) are connected by refrigerant pipes (6) ... so that the refrigerant can flow therethrough. In addition, each indoor unit (B) to
Each of (F) includes an indoor heat exchanger (10) having an indoor blower fan (10a) and an expansion valve (11), and the expansion valve (11) has its valve opening degree increased or decreased electrically. Each of the devices (10) and (11) is connected through a refrigerant pipe (12) so that the refrigerant can flow therethrough.

The five indoor units (B) to (F) are
Refrigerant circulation systems (14) are formed by being connected in parallel to each other by refrigerant pipes (13) and being circulated to the outdoor unit (A) so that a refrigerant circulation system (14) is formed. 3) is switched as indicated by the broken line in the figure and the refrigerant is circulated as indicated by the dashed arrow in the figure, so that each indoor heat exchanger (1
The heat quantity absorbed from the room in 0) is repeatedly radiated to the outside air in the outdoor heat exchanger (4) to cool each room, while
During the heating operation, the four-way switching valve (3) is switched as shown by the solid line in the figure to circulate the refrigerant as shown by the solid line arrow in the figure, so that the exchange of heat is reversed and the room is heated. There is.

Further, an inverter (15) is connected to the first compressor (1), and the operating frequency of the compressor (1) is output by outputting a frequency setting signal in steps of 30% to 10% of the inverter (15). Is adjusted to 8 steps, and the capacity is increased / decreased to a plurality of steps (9 steps including stop).

Further, the second compressor (2), as shown in detail in FIG.
A suction port (2c) and a discharge port (2d) are formed in the closed casing (2b), and in the closed casing (2b), a piston (driven by a motor (2e) via a drive shaft (2f) ( 2g) is disposed and discharges gas (discharge gas) pumped by the piston (2g) from the discharge gas passage (2h) to the discharge gas passage (2b) through the discharge gas pipe (2i). It leads to the exit (2d). An unload mechanism (2a) is arranged in the middle of the discharge gas passage (2h), and the unload mechanism (2a) is provided with an opening (2k) provided in a partition (2i) of the discharge gas passage (2h). ) Is opened and closed, a spring (2m) for urging the valve body (21) in the valve opening direction, and a pressure chamber (2n) behind the valve body (21). The valve body (21) is acted upon by high pressure (discharging gas pressure) when the pilot solenoid valve (17) provided in the pilot pressure introducing passage (16) communicating with the pressure chamber (2n) is closed. The opening (2k) is closed by the valve body (21) and the entire amount of discharge gas is guided to the discharge port (2d) to make the capacity of the second compressor (2) full load (100%), while the pilot solenoid valve When the low pressure is applied when (17) is opened, the valve (21) is urged to the right in the figure by the urging force of the spring (2m) to open the opening (2k), and a part of the discharge gas is discharged. Bypass to the lower part inside the closed casing (2b) through the opening (2k)
It unloads the capacity of the compressor (2) to 50%. That is, the second compressor (2) adjusts the capacity in a plurality of steps with a step width larger than the step width of the first compressor (1) and smaller than the capacity adjustment range of the first compressor (1). It is what is done.

Further, in FIG. 2, (20) is a pressure equalizing hot gas bypass circuit that connects the refrigerant pipes (6), (6) (the discharge pipe and the suction pipe) before and after the four-way switching valve (3), The bypass circuit (20) is provided with a hot gas solenoid valve (21) which is opened during a low load in a cooling operation state, a defrosting operation of the outdoor heat exchanger (4), and the like.

Further, (22) is a heating overload bypass circuit connected to the refrigerant pipe (6) serving as a discharge pipe during the heating operation, and the bypass circuit (22) includes an auxiliary capacitor (23).
Further, a high pressure control valve (24) which is opened when the pressure of the refrigerant is high is interposed, and the refrigerant from the compressors (1) and (2) is exchanged with the heat of each room through the bypass circuit (22) at the time of heating overload. Bowl (1
0) are bypassed, and each indoor heat exchanger (10) is bypassed to the refrigerant pipe (6) on the downstream side.

In addition, (25) is the bypass circuit (2
A liquid injection bypass circuit for connecting the downstream side of the auxiliary condenser (23) of 2) to the refrigerant pipe (6) (intake pipe) on the downstream side of the four-way switching valve (3), the liquid injection bypass circuit (25). An electromagnetic valve (26) for injection, which opens and closes in conjunction with the operation of the compressors (1) and (2), and an expansion valve (27) are interposed in the engine.

Also, (30) is the receiver, (31) is the accumulator,
(32) is a supercooling coil, (33) is an oil separator, and the lubricating oil separated by the oil separator (33) passes through an oil passage (34) to both compressors (1), (2 ).

Furthermore, in each indoor unit (B)-(F),
(TH1) is the temperature of the corresponding indoor air (suction air temperature)
Room temperature sensors (TH2) and (TH3) for detecting the temperature of the indoor heat exchanger (10), which function as an evaporator during the cooling operation, are temperature sensors for detecting the temperature of the refrigerant. In the outdoor unit (A), (TH4) is a temperature sensor that detects the refrigerant discharge temperature of the first and second compressors (1) and (2), and (TH5) is the outdoor heat exchanger (4) during heating operation. ) Is an evaporation temperature sensor for detecting the evaporation temperature of the refrigerant, and (TH6) is an intake gas temperature sensor for detecting the intake gas temperature to the first and second compressors (1), (2). Further, (P1) is a pressure sensor that detects the discharge gas pressure during heating operation, and the suction gas pressure during cooling operation, and (HPS) is a high-pressure pressure switch for protecting the compressor.

Next, the capacity control of the first and second compressors (1) and (2) will be described based on the control flow of FIG. 4 by taking the cooling operation as an example. Note that this capacity control is performed by an outdoor control unit (not shown) provided in the outdoor unit (A).

In FIG. 4, after starting, the refrigerant temperature T2 obtained by converting the intake air amount gas pressure detected by the pressure sensor (P1) in step S1 into the equivalent saturation temperature, that is, the evaporation temperature (condensing temperature of the refrigerant during heating operation) ) Is detected, P1 control (proportional-integral control) is performed as feedback control of the total capacity of the compressors (1) and (2).
At S2, the target total capacity L1 of the compressors (1) and (2) is based on the current and previous values e (t), e (t-Δt) of the deviation between the evaporation temperature T2 and its target value T2o. Then, the following equation L1 = Lo + Kc {e (t) -e (t- [Delta] t) + ([Delta] t / 2Ti) (e (t) + e (t- [Delta] t)} Lo; so that the evaporation temperature T2 becomes the target value T2o. The current total capacity Kc; gain (constant) Ti; integration constant Δt; sampling time.

Then, in step S3, the compressor (1) corresponding to the above total target capacity L1 based on the total capacity map in Table 1,
Grasping the total capacity of (2), based on the actual capacity map of each compressor (1), (2) in Table 2 corresponding to this total capacity, determine the capacity of the first compressor (1). The capacity of the second compressor (2) is adjusted by the unload mechanism (2a) while being controlled by the inverter (15). Then, in step S4, after the elapse of the sampling time Δt, the process returns to step S1 and the above operation is repeated.

Here, the total capacity map in Table 1 above shows that the total capacity of the compressors (1) and (2) to be controlled is zero.
It is divided into multiple stages (19 stages) from the 30% value to the 200% value by gradually increasing by 10%, and the range of the total target capacity L1 is distinguished when the capacity is increasing and when it is decreasing.

In addition, the capacity maps of the compressors (1) and (2) in Table 2 above show that when the total capacity is in the range of 30% to 100%, the capacity of the first compressor (1) is in steps of 10%. In the first map where the capacity of the second compressor (2) increases and the capacity of the second compressor (0) keeps 0% (stop), and the total capacity of the first compressor (1) is 80% to 150%. Capacity is the same as above
In the second map where the capacity of the second compressor (2) keeps 50% and increases in 10% increments, and the total capacity ranges from 130% to 200%, the first compressor (1) The capacity of the second compressor (2) increases by 10%, and the capacity of the second compressor (2) holds 100%. Then, when the total capacity increases or decreases in the first map and the total capacity increases to 110% in the state where the capacity of the first compressor (1) is the maximum value (100%), the process moves to the second map. , The capacity of the second compressor (2) is adjusted to be increased from 0% to 50% by the unload mechanism (2a), and the capacity of the first compressor (1) is adjusted by the inverter (15) to 10%.
It is adjusted to decrease from 0% to 60%, and then each capacity value of this second map is taken according to the increase and decrease of the total capacity,
When the total capacity decreases from 80% to 70% when the capacity value of the compressor (1) is 30% of the minimum value, the second compressor (2) is moved to the first map. Is adjusted to 0% and the capacity of the first compressor (1) is adjusted to 70% by the inverter (15).

Similarly, if the total capacity increases or decreases on the second map and the total capacity increases from 150% to 160% with the capacity of the first compressor (1) at the maximum value (100%), the third map will appear. After the transition, the capacity of the second compressor (2) becomes the unload mechanism (2a).
The capacity of the first compressor (1) is adjusted to be reduced from 100% to 60% by the inverter (15) while being adjusted to be increased from 50% to 100%. After that, each capacity value of this third map is taken according to the increase or decrease in the total capacity, and the total capacity is 130% when the capacity value of the first compressor (1) is 30% of the minimum value.
When the first compressor (1) is reduced from 120% to 120%, the second map is moved to adjust the capacity of the second compressor (2) from 100% to 50%. ) Capacity is adjusted to 70% by the inverter (15).

Therefore, in step S2 of the control flow of FIG. 4, the target for calculating the total target capacity L1 of the compressors (1) and (2) so that the evaporation temperature T2 becomes the set value (target value T2o) It constitutes a capacity calculation means (50). Further, in step S3, the control means (5) which receives the output of the target capacity calculation means (50) and controls the capacity of the compressors (1) and (2) to a total capacity at a stage close to the total target capacity L1.
1) is composed. Then, the control means (51) is
The capacity maps of the compressors (1) and (2) shown in Table 2 are provided so that the capacity of the first compressor (1) can be increased when the total capacity of the compressors (1) and (2) increases. After reaching 100% of the maximum value, the capacity of the second compressor (2) is further increased, and conversely,
When the total capacity is decreased, the capacity of the first compressor (1) becomes 30% of the minimum value, and then the capacity of the second compressor (2) is further reduced by one step. (2a) is controlled by associating it with each other.

Therefore, in the above embodiment, during the cooling operation of each indoor unit (B) to (F), the total target capacity L1 of the compressors (1) and (2) is determined by the target capacity calculation means (50) based on the evaporation temperature T2. ) Is calculated. Then, the capacity of the first compressor (1) is controlled by the control means (51) by the inverter (15) so that the capacity stage corresponds to the target total capacity L1. The capacity of 2) is the control means (51)
Is controlled by the unload mechanism (2a), and the total capacity of the compressors (1) and (2) is accurately adjusted to the total target capacity L1. As a result, the evaporation temperature T2 of the refrigerant converges favorably to the target value T2o, and each room is cooled and air-conditioned well.

In that case, after the capacity of the second compressor (2) is adjusted to increase or decrease between 0%, 50% and 100% by the unloading mechanism (2a), the capacity of the first compressor (1). Even if the inverter (15) is adjusted to increase or decrease to an intermediate value of 40 to 90% due to the change of the total target capacity L1, the value is maintained as it is and 100% of the maximum value.
The steps do not increase unless
As the step is not reduced unless it reaches 30%, the capacity of the second compressor (2) adjusted by the unloading mechanism (2a) can be kept at the same value for as long as possible, and the number of times the capacity changes. Can be effectively reduced, and the durability and reliability of the second compressor (2) can be improved.

In the above embodiment, the capacity of the first compressor (1) is controlled by the inverter (15) in 8 steps, and the capacity of the second compressor (2) is controlled by 2 steps by the unload mechanism (2a). The total capacity is controlled in 19 steps, but the number of capacity control steps may be multiple steps. In addition, in the state of the maximum value (100%) of the first compressor (1), the second compressor (2)
Capacity was increased by one step, and it was controlled to decrease by one step at the minimum value (30%) of the first compressor (1), but increased by one step near the maximum value of the first compressor (1). Of course, the control may be reduced by one step near the minimum value.

Furthermore, in the above-described embodiment, the cooling operation is described as an example, but it is needless to say that the same can be applied to the heating operation, and the invention is not limited to the multi-type air conditioner, and other one outdoor unit. However, it goes without saying that the present invention can be similarly applied to a normal air conditioner to which one indoor unit corresponds, and other refrigerating apparatuses such as those in which indoor and outdoor units are integrated.

(Effects of the Invention) As described above, according to the present invention, the first and second
When the capacity of each compressor is controlled by the inverter and the unload mechanism, the basic capacity value is set by the second compressor on the unload side, and the total capacity is set to the target capacity value by the first compressor on the inverter side. In contrast to what is adjusted, the capacity of the second compressor is controlled to increase or decrease only when the capacity of the first compressor is near the maximum value and when it is near the minimum value.
By holding the capacity of the compressor at the same value as it is for as long as possible, it is possible to suppress the situation in which the second compressor on the unload mechanism side is repeatedly started and stopped, which is a particular problem in such a configuration. The number of changes in the capacity of the second compressor can be effectively reduced, and the durability of the second compressor can be reduced.
Reliability can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 4 show an embodiment of the present invention, FIG. 2 is a refrigerant piping system diagram applied to a multi-type air conditioner, and FIG. 3 is a specific internal configuration of the second compressor. FIG. 4 is a flow chart showing the capacity control of the compressor. (1) ... First compressor, (2) ... Second compressor, (2a)
… Unload mechanism, (21)… Valve element, (2n)… Pressure chamber,
(14) ... Refrigerant piping system, (15) ... Inverter, (17) ...
Pilot solenoid valve, (50) ... Target capacity calculation means, (51)
… Control means.

 ─────────────────────────────────────────────────── --Continued from the front page Examiner Shin Iwasaki (56) References JP 61-195231 (JP, A) JP 60-29553 (JP, A) JP 60-122868 (JP, A) Actual Kai 60-92059 (JP, U) Actual Kai 61-18236 (JP, U)

Claims (1)

(57) [Claims] 1. A first compressor (1) whose capacity is adjusted in a plurality of steps within a predetermined capacity adjustment range by an inverter (15), and said first compressor (1) by an unload mechanism (2a). A second compressor (2) whose capacity is adjusted in a plurality of steps with a step width larger than the step width of the first compressor (1) and smaller than the capacity adjustment range of the first compressor (1). A compressor capacity control device for a refrigerating apparatus, wherein the total capacity of (1) and (2) is controlled in multiple stages, wherein a total target capacity (L1) of the compressors (1) and (2) is calculated. The target capacity calculating means (50) for adjusting the total capacity of the compressors (1) and (2) is adjusted to a capacity close to the total target capacity (L1) by receiving the output of the target capacity calculating means (50). To control the above inverter (15) and unload mechanism (2a). Means (51) for controlling the capacity of the first compressor (1) when the total target capacity (L1) calculated by the target capacity calculating means (50) increases. When it is less than the maximum value, both the compressors (1) are
Adjust the total capacity of (2) to the total target capacity (L1)
When the total target capacity (L1) further increases after the capacity of the first compressor (1) rises to near the maximum value while the capacity of the compressor (2) is less than the maximum value, the second compressor The capacity of (2) is increased by one step, and the capacity of the first compressor (1) is increased from the capacity of one step of the second compressor (2) to one step of the first compressor (1). Both compressors (1), (2)
While adjusting the total capacity of the first target compressor (L1) to the total target capacity (L1), and when the capacity of the first compressor (1) exceeds near the minimum value, the first compressor Only the capacity of (1) is gradually decreased to adjust the total capacity of both compressors (1) and (2) to the total target capacity (L1), and both compressors (1) and (2) are driven. First in the state
When the total target capacity (L1) further decreases after the capacity of the compressor (1) has been reduced to near the minimum value, the capacity of the second compressor (2) is decreased by one step, and the first compression The capacity of the compressor (1) is increased by the capacity of one step of the second compressor (2) minus the capacity of one step of the first compressor (1) to increase the capacity of both compressors ( 1),
A compressor capacity control device for a refrigeration system, wherein the total capacity of (2) is adjusted to a total target capacity (L1).