JPH02267470A - Capacity controller of compressor for refrigerating plant - Google Patents

Abstract

PURPOSE:To restrict an abnormal increase of a high pressure caused by a changing-over operation and further prevent a protective device for a compressor from being operated by a method wherein a time for changing-over of an unloading mechanism is delayed more than a changing-over time of an output frequency of an inverter. CONSTITUTION:In case that an unloading mechanism 2a is changed over from its unloaded state to its loaded state by a controlling means 51, a time for changing-over the unloading mechanism 2a into its loaded condition is delayed by a changing-over limiting means 52. In case that capacities of compressors 1 and 2 are changed, the unloading mechanism 2a is changed over to its loading side and at the same time an output frequency of an inverter 15 is varied slightly. In this case, at first an output frequency of the inverter 15 is varied and then a capacity of the compressor is gradually decreased and after this state the unloading mechanism 2a is changed over to the loading side, resulting in that the capacity of the compressor just after this changing-over operation is not so high as expected. Thus, a high pressure is not abnormally increased, but the protection device against the compressors 1 and 2 is not operated, so that the compressors 1 and 2 may perform their continuous operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a capacity control device for a compressor of a refrigeration system, and particularly relates to an improvement in the capacity control device using both an unloading mechanism and an inverter.

(Prior Art) Conventionally, as a capacity control device for a compressor of this type of refrigeration equipment, for example, as disclosed in Japanese Unexamined Patent Publication No. 127864/1983, an unloading mechanism is used to control the compressor between a loaded state and an unloaded state. There is a known system in which the capacity of the compressor is adjusted in multiple stages by changing the operating frequency of the compressor into multiple stages using an inverter, thereby controlling the capacity of both.

(Problems to be Solved by the Invention) However, although the switching operation of the unloading mechanism is performed immediately, the inverter can only change the output frequency gradually. Therefore, when controlling the compressor capacity to the target value, when switching the unload mechanism to the load side and changing the inverter output frequency to a lower value, the inverter output frequency is still near the original frequency. situation, the unloading mechanism will immediately switch to the loading side. As a result, the capacity of the compressor increases from its original capacity by the amount that the unloading mechanism switches to the load side, and then gradually decreases as the output frequency of the inverter decreases. In this case, when the capacity of the compressor increases, the high pressure in the refrigerant circulation system increases abnormally, and the compressor protection device operates accordingly, forcing the compressor to stop. Sometimes I put it away.

The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent the unloading mechanism from changing from the unloading side to the loading side when changing the capacity of the compressor. The purpose is to prevent the compressor's protection device from operating by suppressing abnormal increases in high pressure, and to allow the compressor to operate continuously.

(Means for Solving the Problems) In order to achieve the above object, the present invention establishes a relationship between the timing of the switching operation of the unloading mechanism and the timing of changing the output frequency of the inverter, and the timing of the switching operation of the former. The change timing is set later than the latter.

In other words, the specific solution of the present invention is, as shown in FIG. The above compressor (1,
2) a target capacity setting means (50) for setting the target capacity ff1(L+); and receiving the output of the target capacity setting means (50), the capacity of the compressor (1, 2) is set to the target capacity ff1(L+). The unloading mechanism (2a) and the control means (51) for controlling the inverter (15) are applied so that the unloading mechanism (2a) is controlled by the control means (51).
2a) is provided with a switching restriction means (52) that delays the timing of switching the unloading mechanism (2) to the loading state when switching from the unloading state to the loading state.

(Function) With the above configuration, in the present invention, when changing the capacity of the compressor (1, 2), the unloading mechanism (2a) is switched to the loading side and the output frequency of the inverter (15) is changed to a small value. First, the output frequency of the inverter (15) is changed and the capacity of the compressor is gradually reduced, and then the unloading mechanism (25a) 1 is switched to the loading side.
The capacity of the compressor immediately after this changeover is not very large. Therefore, the high pressure does not become abnormally high and the compressor (1, 2)
Since the protective device is not activated, the compressors (1, 2) can be operated continuously.

In particular, after the output frequency of the inverter (15) has been changed to the target value and the frequency change has been completed, the unloading mechanism (
By switching 2a) to the load side, continuous operation of the compressors (1, 2) is ensured.

(Effects of the Invention) As explained above, according to the capacity control device for a compressor of a refrigeration system of the present invention, when switching the unload mechanism to the load side, the timing is the same as the time when the output frequency of the inverter is changed. Instead, it is delayed further than this, so it is possible to suppress an abnormal rise in the high pressure in the refrigerant circuit, prevent the compressor protection device from operating, and expand the range in which the compressor can be continuously operated.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

Figure 'R42 shows an embodiment in which the present invention is applied to a multi-type air conditioner, in which (A) is an outdoor unit, (B) to (P
) are five indoor units with the same internal configuration, and inside the outdoor unit (A), there are a first compressor (1) and a second compressor (2) connected in parallel to each other, and four A path switching valve (3), an outdoor heat exchanger (4) having an outdoor fan (4a), and an expansion valve (5) are provided, and each of the devices is
> to (5) are connected to each other through refrigerant pipes (6) so that refrigerant can flow therethrough. In addition, each of the above indoor units (B)
- (P) each include an indoor heat exchanger (10) having an indoor ventilation fan (log) and an expansion valve (11), and the expansion valve (11) has an opening degree that is electrically controlled. It consists of an indoor electric expansion valve for adjusting air conditioning capacity that can be increased or decreased.
The respective devices (10) and (11) are refrigerant pipes (12)...
connected to allow refrigerant flow.

The five indoor units (B) to (P) are connected in parallel to each other through refrigerant piping (I3), and connected to the outdoor unit (A) so that the refrigerant can be circulated. A system (14) is formed, and during cooling operation, the four-way switching valve (3) is switched as shown by the broken line in the figure to circulate the refrigerant as shown by the broken line arrow in the figure, thereby controlling each indoor heat exchanger (1O). The heat absorbed from the room is repeatedly radiated to the outside air by the outdoor heat exchanger (4) to cool each room, while during heating operation, the four-way selector valve (3) is turned on as shown by the solid line in the figure. By switching the refrigerant and circulating the refrigerant as shown by the solid arrow in the figure, the amount of heat exchanged is reversed to heat the room.

In addition, an inverter (15) is connected to the ml compressor <1), and 30% to 1
By outputting the frequency setting signal in 0% increments, the compressor (1)
The operating frequency of the pump is adjusted in eight steps, and the capacity is increased or decreased in multiple steps (nine steps including when stopped).

Furthermore, as shown in detail in FIG.
) is formed, and a piston (2g) driven by a motor (2e) via a drive shaft (2f) is disposed within the sealed casing (2b), and a gas pumped by the piston (2g) is arranged. (Discharged gas) Discharged gas passage (2h)
A discharge gas pipe (2b) opens from the discharge gas passageway (2b).
]) to the discharge port (2d). And, in the middle of the discharge gas passage (2h),
An unloading mechanism (2a) is arranged, and the unloading mechanism (2a) includes a valve body (2 k) that opens and closes an opening (2k) provided in a partition wall (2j) of a discharge gas passage (2h), (2
1) It has a spring (2m) that biases the valve in the valve opening direction and a pressure chamber (2n) behind the valve body (21). and,
The valve body (21) is a pilot solenoid valve (1) provided in a pilot pressure introduction passage (1B) communicating with a pressure chamber (2n).
7), the high pressure (discharge gas pressure) acts on the valve body (21) to close the opening (2k) and guide the entire amount of discharge gas to the discharge port (2d), which causes the second compressor ( While the capacity of 2) is set to full load (100%), low pressure is applied when the pilot solenoid valve (17) is opened, and the urging force of the spring (2■) pushes the valve body (21) toward the right in the figure. is energized to open the opening (2k), and a portion of the discharged gas is bypassed to the lower part of the sealed casing (2b) through the opening (2k), reducing the capacity of the second compressor (2) to 50%. It is to be unloaded.

In addition, in FIG. 2, (20) is a pressure equalizing hot gas bypass circuit that connects the refrigerant pipes (6) and (8) (discharge pipe and suction pipe) before and after the four-way switching valve (3). The bypass circuit (20) is provided with a hot gas solenoid valve (21) that is opened during low load during cooling operation and during defrosting operation of the outdoor heat exchanger (4).

Furthermore, (22) is a heating overload bypass circuit connected to the refrigerant pipe (8) which becomes a discharge pipe during heating operation, and the bypass circuit (22) includes an auxiliary capacitor (23).
) and a high-pressure control valve (24) that opens when the refrigerant pressure is high.

(2) through the bypass circuit (22) and bypasses each indoor heat exchanger (10)...downstream refrigerant piping (6). ).

In addition, (25) is the heating overload bypass circuit (2
The downstream side of the auxiliary condenser (23) of 2) is connected to the four-way selector valve (
3) A liquid injection bypass circuit connected to the refrigerant pipe (6) (suction pipe) on the downstream side, and the liquid injection bypass circuit (25) is equipped with a compressor (
An injection solenoid valve (2B) that opens and closes in conjunction with the operations of 1) and (2) and an expansion valve (27) are interposed.

Further, (30) is a receiver, (31) is an accumulator, (32) is a supercooling coil, and (33) is an oil separator, and the lubricating oil separated by the oil separator S (33) is passed through the oil passage ( 34) and is returned to the inner compressors (1) and (2).

Furthermore, in each indoor unit (B) to (P), (T
ll1) is a room temperature sensor that detects the temperature of the corresponding indoor air (intake air temperature), (Tll2) and (Tll
3) is an indoor heat exchanger (10) that acts as an evaporator during cooling operation, and a temperature sensor that detects the temperature of the front and rear cooling vi. In addition, in the outdoor unit (A), (
T114) is a temperature sensor that detects the refrigerant discharge temperature of the first and second compressors (1) and (2), and (TI15) is a temperature sensor that detects the evaporation temperature of the refrigerant in the outdoor heat exchanger (4) during heating operation. The evaporation temperature sensor (Ti[i) is an intake gas temperature sensor that detects the intake gas temperature to the first and second compressors (1) and (2). Further, (PI) is a pressure sensor that detects the discharge gas pressure during heating operation and the intake gas pressure during cooling operation, and (IIPS) is a high pressure switch for protecting the compressor.

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

In FIG. 4, the refrigerant temperature T2, that is, the evaporation temperature (
During heating operation, after detecting the condensation temperature of the refrigerant, PI sub-control proportional-integral control is performed as feedback control of the total capacity of the compressors (1) and '(2), and in step S2, the compressor (1) ), the target total capacity L1 of (2) is
Based on the current and previous values e (1) and e (t-Δ1) of the deviation between the evaporation temperature T2 and its target value T2o,
Calculate using the following formula (% formula %)) Lo: Current total capacity Kc: Gain (constant) TI: Integral constant Δt: Sampling time so that the evaporation temperature T2 becomes the target value T20.

After that, in step S3, the compressor (1
), (2), and calculate the capacity of the first compressor (1) based on the actual capacity map of each compressor (1), (2) in Table 2 corresponding to this total capacity. The capacity is controlled by an inverter (15), and the capacity of the second compressor (2) is adjusted by an unloading mechanism (2a). Then, in step S4, wait for the sampling time Δt to elapse, and then proceed to step S! Go back and repeat the above steps.

Table 1 Here, the total capacity map in Table 1 above is for compressor (1)
, (2) when the total capacity to be controlled is zero, and when 30%
The total target capacity L
The range of 1 is distinguished between when the capacity increases and when it decreases.

In addition, the capacity map of each compressor (1) and (2) in Table 2 above shows that the capacity of the first compressor (O increases in 10% increments) when the total capacity ranges from 30% to 100%. At the same time, the first map holds the capacity of the second compressor (2) at 0% (stopped), and the total capacity changes from 80% to 150%.
In the range of is 13
In the range from 0% to 200%, the first compressor (
The capacity of 1) increases in 10% increments, and the second compressor (2)
and a third map whose capacity is 100%. Then, the total capacity increases or decreases in the first map, and when the total capacity increases to 110% while the capacity of the first compressor (1) is at its maximum value (100%), the map shifts to the second map. , the capacity of the second compressor (2) is 0 at the unloading mechanism (2a).
% to 50%, and the first compressor (
1) Capacity is increased from 100% to 60% by inverter (15)
After that, each capacity value of this second map is taken according to the increase/decrease change in the total capacity, and the first compressor (1
) when the capacity value is 30% of the minimum value, the total capacity is 80%.
When the capacity decreases from 1 to 70%, the process shifts to the first map, and the capacity of the second compressor (2) is adjusted to 0%, and the capacity of the first compressor (1) is adjusted to 0%. (15)
is adjusted to 70%.

Similarly, if the total capacity increases or decreases in the second map, and the capacity of the first compressor (1) is at its maximum value (100%), and the total capacity increases from 150% to 160%, the third map changes. The capacity of the second compressor (2) is increased by the unloading mechanism (
In 2a), the increase is adjusted from 50% to 100%, and
The capacity of the first compressor (1) is 10 with the inverter (15)
Adjusted to decrease from 0% to 60%. After that, each capacity value of this third map is taken according to the increase/decrease change in the total capacity,
When the capacity value of the first compressor (1) is 30% of the minimum value and the total capacity decreases from 130% to 120%,
Moving to the second map above, the capacity of the second compressor (2) decreases from 100% to 50% I! The capacity of the first compressor (1) is increased to 70% by the inverter (15).
is adjusted to

Therefore, in step S2 of the control flow in FIG. 4 above, the evaporation temperature T2 is set to the set value (target values T, Q).
A target capacity setting means (50) is configured to calculate and set a total target capacity L1 of the compressors (1) and (2). Further, in step S3, the inverter (15) receives the output of the target capacity setting means (50) and sets the total capacity of the compressors (1) and (2) to a level close to the total target capacity RL1. ) and unloading mechanism (2a
) constitutes a control means (51) configured to control. The control means (51) is equipped with a capacity map of each compressor (1) and (2) in Table 2, and the total capacity of the compressors (1) and (2) is between 150% and 100%. When the load increases, the unloading machine +fW (2a) is switched from the unloading state to the loading state to make the capacity of the second compressor (2) 100%, and the output frequency of the inverter (15) is lowered. The capacity of the first compressor (1) is 100
% to 60%.

Next, we will explain the operation of the above control flow, especially the total capacity ff1150.
The explanation will be based on FIG. 5 and FIG. 6, focusing on the increase from % to 160%.

In Fig. 5, the pilot solenoid valve (17) of the unloading mechanism (2K) is turned on (opened) in the second compressor (2).
When unloading (at "1" position), if the thermostat turns OFF and an increase in capacity is requested, the pilot solenoid valve (
17) to the OFF (closed) side and turn on the second compressor (2).
is in a fully loaded state (“0” position).

Also, if the thermostat is turned on in this state and a reduction in capacity is requested, the first compressor (1) will be activated! Only when the capacity is 00%, it transits to the "1" position and the second compressor (2) is in an unloaded state.

In addition, at the "1" position, the first compressor (1) is at 100%
When the capacity is reached, in order to wait for the capacity to increase from 150% to 180%, the frequency matching counter (described later) is reset to the "2" position, and the O of the pilot solenoid valve (17) is turned off.
The unloaded state of the second compressor (2) is maintained by the N (open) operation.

Then, when the thermostat turns off at the "2" position and an increase in capacity to 160% is requested, the first compressor (1)
wait for the time when the capacity reaches 80%, that is, the inverter (1
In order to wait for the time when the output frequency of 5) reaches the target value, the 6th
Perform the counter control flow shown in the figure. This control flow starts, and in step S1, it is determined whether or not a frequency matching signal is received from the inverter (15), which means that the output frequency matches the target value.If it is not received, step S2 is performed. Reset the frequency match counter and return. In addition, in the case of YES when the frequency match signal is received, the frequency match counter counts the time, and in step S3 it is determined whether this count has increased, and in the case of NO, the count is continued in step S4 and the process returns. When the count is completed, the process immediately returns to switch the unload mechanism (2a) to the full load state.

When the frequency matching counter is confirmed to have increased at the "2" position in Figure 6, it is determined that the capacity can be increased to 1130%, and the frequency matching counter is changed from the "2" position to the "0" position. The pilot solenoid valve (17) is set to OPI' (
(closed) side to bring the second compressor (2) into a full load state.

Therefore, according to the control flow shown in FIGS. 5 and 6, when an increase in capacity from 150% to 180% is requested, the control means (51) changes the unloading mechanism (2a) from the unloading state to the loading state. When switching, delay the timing of switching this unloading mechanism (2) to the loading state,
Wait until it is confirmed that the output frequency of the inverter (15) has reached the target frequency, and only when this is confirmed,
It constitutes a switching restriction means (52) that allows the unloading mechanism (2) to be switched to the loading state.

Therefore, in the above embodiment, as shown in FIG. 7, when the capacity is increased from 150% to 180%, the first compressor (1) on the inverter (15) side
The capacity is reduced from 100% to 60% due to the decrease in the output frequency of the unloading machine? ! (2a) side second compressor (
In 2), the capacity is increased from 50% to 100% by switching the unloading mechanism (2a) to the full load side.

At this time, conventionally, the inverter (
15) When the capacity of the first compressor (1) on the side is close to the original 100% capacity, the unload mechanism (2a) switches to the full load side and the second compressor (2) % capacity, the total capacity becomes abnormally large, and the capacity value (indicated by the dotted chain line in the figure) corresponds to the high pressure limit value for compressor protection (operating value of the high pressure switch (IPS)). beyond,
As a result, the compressor protection device is activated and the compressor (1)
, the operation in (2) will be forcibly stopped.

However, in the present invention, as shown by the solid line in the figure, the output frequency of the inverter (15) reaches the target value and the first compressor (
When the capacity of 1) reaches the target capacity of 60%, the unloading mechanism (2a) switches to the full load side, so - in the figure
The compressor (
Continuous operation of 1) and (2) can be performed.

In the above embodiment, the first compressor (1) was controlled by the inverter (15), and the second compressor (2) was controlled by the unloading mechanism (2a). On the other hand, it goes without saying that the present invention can be similarly applied even if the capacity is controlled by both the inverter and the unloading mechanism.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. Figures 2 to 7 show embodiments of the present invention, Figure 2 is a refrigerant piping system diagram applied to a multi-type air conditioner, and Figure 3 shows the specific internal configuration of the second compressor. Figure shown, 4th
The figure is a flowchart showing the capacity control of the compressor, FIGS. 5 and 6 are flowcharts for imposing restrictions when changing the capacity, and FIG. 7 is an operation explanatory diagram. <1) First compressor, (2) ... second compressor, (
2a)...Unloading mechanism, (21)...Valve body, (
2n)...Pressure chamber, (14)...Refrigerant piping system, (
15)...Inverter, (17)...Pilot solenoid valve, (50)...Target capacity setting means, (51)...
- Control means, (52)...Switching restriction means. Figure Figure Figure

Claims (2)

[Claims] (1) A compressor capacity control device for a refrigeration system comprising an unloading mechanism (2a) and an inverter (15) for adjusting the capacity of the compressor (1, 2), the compressor (1, 2)
target capacity setting means (5) for setting a target capacity (L_1) of
0) and the output of the target capacity setting means (50), the unloading mechanism (2a) and the inverter (15) are operated so that the capacity of the compressor (1, 2) becomes the target capacity (L_1).
and a control means (51) for controlling the timing of switching the unloading mechanism (2) to the loading state when the control means (51) switches the unloading mechanism (2a) from the unloading state to the loading state. 1. A capacity control device for a compressor of a refrigeration system, characterized in that the device includes switching limiting means (52) for delaying switching. (2) The switching restriction means (52) allows the unloading mechanism (2) to be switched to the loading state only when it is confirmed that the output frequency of the inverter (15) has reached the target frequency. Capacity control device for compressor of refrigeration equipment.