JPH0432657A - Refrigeration cycle controller - Google Patents

Abstract

PURPOSE:To achieve a control excellent in responsiveness from an initial stage by comparing first and second elements multiplied by a quantity of first calculation among mutual intervention compensating elements used for a compensating elements used for a compensating means with those obtained by removing dynamics factors as theoretical values and setting the ratio thereof to a large value. CONSTITUTION:Deviation DELTAT between the evaporation temperature TR of a cooling medium and the target temperature TRO thereof and deviation DELTAS between the degree of superheat SH and the target degree of superheat SHO are calculated. A first quantity X of pseudo-operation is calculated by PID calculation based on the deviation DELTAT and a second quantity Y of pseudo- operation is calculated based on the deviation DELTAS. The quantity thetaa of valve travel operation and the quantity Da of compressor capacity operation are calculated from equations, that is, Da = X.alpha + Y.b12(0), thetaa = X.beta + Y.b22(0). Herein, alpha,beta, b12 (0) and b22(0) are constants (compensating elements). The change of the quantity thetaa of valve travel operation is emphasized larger and controlled, compared with the case in which theoretical values b11(0), b21(0) are used.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a control device for a refrigeration cycle, and more particularly to a control device for mitigating mutual interference within a two-man power, two-output system controlled object.

[Prior Art] Generally, a refrigeration cycle device equipped with a variable capacity compression micro-condenser, a variable opening expansion valve, and an evaporator is used in automotive air conditioners (hereinafter abbreviated as "air conditioners"). ing. This device (variable capacity compressor, condenser, variable opening expansion valve, and evaporator in this order) circulates the refrigerant and exchanges heat between indoor air and the evaporator to cool the room.

In order to maintain the indoor temperature (or humidity) at a comfortable level, such devices efficiently control the evaporation temperature and superheating degree of the refrigerant according to the indoor temperature (humidity) state. The evaporation temperature and degree of superheating of the refrigerant are controlled by adjusting the capacity of the compressor (rotational speed, compressor capacity, etc.) and the opening degree of the expansion valve.

However, the capacity of the compressor and the degree of opening of the expansion valve independently influence the evaporation temperature and degree of superheating of the refrigerant, and thus interfere with each other. Therefore, even if an attempt is made to control the refrigerant evaporation temperature and the degree of superheat to the desired states, a system in which the refrigerant evaporation temperature is independently controlled by the capacity of the compressor and the degree of superheat is independently controlled by the opening degree of the expansion valve will not reach the desired state. It was difficult to quickly converge to the refrigerant evaporation temperature and superheat degree.

To solve this problem, the opening degree of the expansion valve and the capacity of the compressor were calculated via a non-interference circuit (Japanese Patent Laid-Open No. 63
-29155).

The method of determining mutual interference compensation elements in this interference-free circuit is generally well known.

In other words, in the case of a two-man power, two-output system, the transfer function of the controlled object is
It is represented by a matrix G, (S) with rows and 2 columns, and by appropriately selecting the mutual interference compensation element Go(s) with 2 rows and 2 columns, the apparent controlled object G (s), that is, G (s) = Gp ( s) ・Go(s) ・・(
This is a method that attempts to make 1) as close to a diagonal matrix as possible.

However, the mutual interference compensation element G0 obtained from the above conditions
(s) is typically quite complex and may delay control. For this reason, if G, (0) is a regular matrix, then Go(s) is a constant matrix G0(S) :G,
It is proposed to select (0) -1...(2).

At this time, it is clear that G (0) = G, (0)・Go(0) = lF ・・
- Since (3), 5=O (state in which dynamics factors are excluded) and mutual interference does not exist. Moreover, since the mutual interference compensation element G0(s) is a constant, each operation amount to the expansion valve and compressor is calculated from two calculated values (for example, pseudo operation amount) calculated from the deviation between the target value and the actual measurement value. By multiplying by a constant, the complexity of control is eliminated.

[Problems to be Solved by the Invention] When the mutual interference compensation element G0(s), which is a constant matrix obtained by the above method, is applied to an actual refrigeration cycle, the refrigerant evaporation temperature is independently controlled by the compressor capacity, Both the evaporation temperature and the degree of superheat converge to the target values more quickly than in a system that controls the degree of superheating independently by the opening degree of the expansion valve, and as a result, the room temperature and the air outlet temperature of the air conditioner quickly reach the desired state.

However, it has been found that even if the compensation element Go(s) is used, sufficient control is not performed at the initial stage of control. This is because the response of the degree of superheat is slower when operating the expansion valve opening than when operating the compression function force, but the compensation element Go(s
) does not include dynamics factors, so the degree of superheat is quickly influenced by the compression function force operation in the initial stage of changing the target refrigerant evaporation temperature, resulting in deviations in control. Therefore, for example, when switching the room temperature setting from a high temperature side to a low temperature side, the degree of superheating increases in the initial stage of control, causing a phenomenon in which the decrease in the temperature of air blowing from the air conditioner temporarily stops. .

Structure of the Invention [Means for Solving the Problems] The present invention has been made for the purpose of solving the above-mentioned problems. A cycle control device is provided.

The refrigeration cycle control device of the present invention, which has been made to solve the above problems, has at least a variable capacity compressor, a condenser, a variable opening expansion valve, and an evaporator arranged along the flow of refrigerant, as illustrated in FIG. A control device for a refrigeration cycle arranged in sequence, comprising: evaporation temperature related physical quantity detection means for detecting an evaporation temperature related physical quantity related to the evaporation temperature of the refrigerant in the evaporator; superheat degree-related physical quantity detection means for detecting a related superheat degree-related physical quantity; capacity switching instruction means for instructing switching of the capacity of the refrigeration cycle; and a target value of at least the evaporation temperature-related physical quantity in response to the capacity switching instruction. a first calculation means that calculates a first calculated amount based on the deviation between the physical quantity related to the evaporation temperature and its target value; By using a second calculating means that calculates a second calculated amount using and a compensating means for outputting an opening related manipulated variable of the variable opening expansion valve, and the mutual interference compensation element includes at least a first calculated variable that is multiplied by the first calculated amount in order to calculate the capacity related manipulated variable. 1 element, a second element multiplied by the first calculated quantity, and a third element multiplied by the second calculated quantity in order to calculate the opening-related manipulated variable, the second element and the first The absolute value of the ratio of the corresponding element among the mutual interference compensation elements calculated by the method of removing mutual interference based on the input-output transfer function set excluding the dynamics factors of the refrigeration cycle. It is characterized by being large compared to its absolute value.

[Operation] In the present invention, the mutual interference compensation element includes a first element multiplied by at least the [first] calculation amount in order to calculate the capacity-related operation amount, and a first element by which the opening-related operation amount is calculated. 1st
A constant matrix G, (0)-
1 is not used as is. This constant matrix G,
A constant matrix is used in which the absolute value of the ratio of the second element to the first element (second element/first element) is set to be large compared to (0)-1. In other words, the opening-related manipulated variable calculated based on "first calculated amount x second element" is larger than [first calculated amount x second element].
Compared to the ability-related manipulated variable calculated based on "calculated amount x first element," the change is emphasized more than when the constant matrix G, (0) is used as is. It goes without saying that the emphasis should be placed within a range that does not cause liquid back-up over a long period of time.

In this way, by quickly setting the manipulated variable that shows a relatively large change in the opening-related manipulated variable, it compensates for the delay in superheat response due to expansion valve opening manipulation as described above, and improves control from the initial stage. Improves responsiveness.

[Example] Next, a preferred example of the present invention will be described in detail based on the drawings. FIG. 2 shows an automotive air conditioner and its control device as an embodiment.

This refrigeration cycle includes a variable capacity compressor 1, a condenser 3, a receiver 5, a variable opening expansion valve 7, and an evaporator 9. Since these functions are common and their configurations are well known, their explanations will be omitted. In particular, the above-mentioned variable capacity compressor] is also disclosed in Japanese Patent Laid-Open No. 85219/1983, and controls the amount of refrigerant to be compressed by adjusting the compressor capacity in response to an operation signal from an electronic control circuit 25. Further, the variable opening degree expansion valve 7 is composed of a solenoid valve, and controls the refrigerant flow rate by adjusting the valve opening degree based on an operation signal from the electronic control circuit 25.

The evaporator 9 is provided with a proa fan for exchanging heat between indoor air and the refrigerant in the evaporator 9. The amount of air blowing can be adjusted by the driver or the like operating the temperature setting and air volume setting switches on the operation panel 13 provided on the dash board in the driver's cabin.
This is realized by changing the rotation speed of 1a.

The input shaft of the variable capacity compressor 1] a has an electromagnetic clutch] 5
The driving output from the automobile engine 17 is transmitted through the electromagnetic clutch 5. Further, the condenser 3 is cooled by an engine cooling fan 19.

The setting signal SW of the operation panel [3], the refrigerant temperature TS signal from the temperature sensor 2 near the outlet of the evaporator 9, and the refrigerant pressure PR signal from the pressure sensor 23 are sent to an electronic control circuit 25 configured as a microcomputer. is input. The electronic control circuit 25 converts each signal into a digital signal using a provided input circuit 25a and inputs the digital signal to the CPLJ,
ROM.

A logic operation circuit 25b equipped with a RAM and a clock performs a predetermined process, and outputs a necessary command corresponding to the result as a predetermined signal from the provided output circuits 2 and 5c.
Solenoid valve 27 for turning on/off the electromagnetic clutch 15 and adjusting the capacity
and controls the opening degree of the variable opening degree expansion valve 7.

Next, the processing executed by the electronic control circuit 25 will be explained based on the flowchart of FIG. This process is stored as a program in the logic operation circuit 25bOROM.

When processing is started by turning on a key switch (not shown), first, various flags, variables, and constants are initialized, or the initial states of the electromagnetic clutch 15, the capacity adjustment electromagnetic valve 27, and the variable opening expansion valve 7 are set. to be done (step)
00).

Next, it is determined whether the control cycle has been reached (step 1
]0). If the predetermined cycle has not been reached, a negative determination is made and a standby state is entered. When the predetermined cycle has been reached, an affirmative determination is made, and then it is determined whether or not the target value has been changed based on the setting signal SW of the operation panel 13 (step 120). For example, when the air volume setting or the room temperature setting is switched on the operation panel 3, it is determined that the target value has been switched. A change in the target value means an instruction to switch the capacity in the refrigeration cycle. If there is a change in the target value, the already set target value of the evaporation temperature is newly set to a target value according to the setting signal SW (step) 30. For example, when the room temperature is newly set, the target refrigerant evaporation temperature TPO is determined and set from the new room temperature setting based on the relationship map between the set room temperature and the target refrigerant evaporation temperature TPO shown in FIG. Ru. This map is stored in ROM. Of course, instead of the map, the target refrigerant evaporation temperature TRO may be determined by storing and setting in the ROM an arithmetic expression indicating the relationship.

The target superheat degree SHO is usually a desired superheat degree (for example) 0
Since 0°C exists, it does not change even if you change the room temperature setting or the air volume setting.

Of course, if necessary, the target superheat degree S can be set according to the setting signal SW.
You may change the HO.

In addition to changing the target value as described above, various gains may be changed depending on the situation. For example, the gain of PID control, which will be described later, and the compensation elements α, β, b12 ( , b22(0), etc. However, regarding α and β, the relationship described later (Equation (9)
) must satisfy 6th temperature sensor 21
The refrigerant temperature TS is determined from the pressure sensor 23, and the refrigerant pressure PR is determined from the pressure sensor 23.
is read (step 140). Next, since the saturation temperature of a pure substance is determined once the pressure is determined, the evaporation temperature TR of the refrigerant is determined from the value of the refrigerant pressure PR (step) 45. Next, the degree of superheating of the refrigerant vapor at the outlet of the evaporator 9 is 5H (
=TS-TR) (Step] 50).

Next, the deviation/T between the refrigerant evaporation temperature TR and the target refrigerant evaporation temperature TRO, and the deviation/S between the degree of superheat SH and the target degree of superheat SH○ are calculated (step) 60. Next, PID
Through calculation, a first pseudo operation amount x is calculated based on the deviation 7, and a second pseudo operation amount Y is calculated based on the card deviation/S (step) 70. Since PID calculation is a well-known method, a detailed explanation will be omitted, but for example, as an example of a velocity form of PID control, each pseudo operation amount is calculated using the following equation. Of course, position form P
ID control may also be used. Also, P control, P1 control, or P control
The D sub-control may also be a modern control such as an optimum regulator.

Vn=Vn-++Kp ((E,-En-1)±(/l
/TI)E.

Ten (T, /at) (E, 2E, -1+Eo-2)
)Vn Secondary pseudo-operated variable Vn-,: Pseudo-operated variable Ko before 1 sampling: Proportional gain (However, in the following description, the proportional gain for evaporation temperature control is Kl, and the proportional gain for superheat degree control is 2. shall be.

) /l: Sampling time Ti: Integration time T, : Differential time En: Current deviation En-, : i Deviation before sampling 1=n-2: 2 Deviation before sampling Next, valve opening manipulated variable θa and The compressor capacity operation amount Da is calculated using the following equations (4) and (5) (step)
80).

Da=×・α+Y−b12(0)...(4)θa=X
・β0Y −b22co)−<5>Here, α, β,
b12(of, b22(0) is a constant (compensation element). This α, β, b12(of, b22(0)
was determined as follows.

The above equation (2) [G, (s) =G, (0)
-'], Go(S) [where S=0] and G, (0) are specifically expressed as determinants by the following equation (6):
It is expressed as (7). In addition, the following equation (6), (
A block diagram corresponding to 7) is shown in FIG.

In addition, in equation (6), rbll is used instead of "α" in the figure.
(0)J, rb21(0)J instead of “β”
is used.

Therefore, the relationship in equation (2) is expressed as in equation (8) below. On the right side, all(, a12(, a21()
of.

a　22(0) are all constants.

...(8) From this equation, it follows that the compensation elements b11('s, b12('s, b21('s, b22(0)[;&all('s,a12('s,a21('s).

It can be determined as a constant by the combination of a 22(0).

Here, b12 (of,
b22(0)IL Corresponds to the same symbol in formula (8).

In addition, α and β in equations (4) and (5) are theoretical values of bll(, and b21(0) is given by the following equation (9
) is set to have the relationship shown in

β/αl > l b21(0)/bll(0)I
...(9) Therefore, in the above equations (4) and (5), the change in the valve opening manipulated variable θa is emphasized more than when the theoretical values b11 (0) and b21 (0) are used. It will be controlled by

In addition, in this example, α, β(y) are each theoretical value b11(0
) and b21(0), but since the product of the proportional gain of PID control and 1 is ultimately calculated and reflected in the manipulated variable, the sign of the proportional gain Kl should be considered. For example, α, β and the theoretical value b 11(0), b
21(0) may be a different code.

Therefore, the signs of α and β can be set freely.

In addition, the total proportional (constant) gain of the control system is the proportional gain Kl of PID control, 2, and compensation elements α and β.
, b12(, b22(0)), so if we change the weight of 2 to the proportional gain Kl, we get
Any one of compensation elements α and β, and compensation element b
12(0), b22(0), ``]
”, and in the case of “]”,
Multiplication with Y can be omitted. For example, the expression (
4) and (5) can also be simplified as in the following equations (4)' and (5)'.

D a = X 10Y-b 12(0)' -
(4) 'θa=X・β' 10Y...(
5)' Once the manipulated variables θa and Da are set in this way, the manipulated variables are then converted into operational signals and output to the capacity adjustment solenoid valve 27 and the variable opening expansion valve 7. step] 90).

In this way, control returns to step 770, and thereafter the above-described process is repeated every control cycle. As a result, control is performed so that the actual evaporation temperature and degree of superheating reach the target values.

In this embodiment, the capacity of the variable capacity compressor (with this configuration, the variable capacity compressor is responsive to changes in settings such as room temperature and air volume) and the opening of the variable opening expansion valve 7 can be made to follow. This allows the desired air conditioning state to be quickly reached from the beginning of the setting change.

FIG. 6 shows a timing chart of the blowout temperature when the room temperature setting is changed in this embodiment.

In FIG. 6, the thick solid line represents this embodiment, which is the case where α and β obtained by the following equation (10) are used.

β/α=l, 4X (b21(0)/bll(0)
)...(10) Also, the thin solid line is the theoretical value (bti
If (, b2], (0)) is used as is, the broken line indicates the superheat degree deviation AS, which is calculated by calculating the compressor capacity operation amount Da from the evaporation temperature deviation 7 using only PID control without using the compensation element.
This is a case where the valve opening degree manipulation amount θa is calculated from .

It took 170 seconds for the blowout temperature to drop to the desired temperature using only PID control (broken line).

When using compensation elements (thick solid line and thin solid line)
In this case, the desired temperature is reached at 70 seconds, but in the case of using the theoretical value (thin solid line), the blowing temperature remains almost unchanged for nearly 40 seconds after the setting change operation. There is. For this reason, sufficient cooling is not performed during this time, causing a sense of discomfort to the operator, and cooling of the entire room is delayed.

On the other hand, when α and β are used as compensation elements, there is a rapid drop in the blowout temperature from the beginning of the switching operation, and the operator does not feel any discomfort, and the entire room is cooled quickly. This is because the increase in the degree of superheating immediately after the switching operation is suppressed due to the relationship in equation (9).

In the above embodiment, α, β, b12(0
), b22(0) were used, among which b12(
Even without 0), there is almost no problem in controllability. Therefore, the above equations (4) and (5) can be simplified as follows.

Da=X・α...(11)
θa=X・β0Y −b22(0) −(12) If we introduce the simplification process of equations (4)' and (5)' into this, equations (13) and (14) become even simpler, Control calculation load can be reduced.

D a = X...(
13) θa=X・β' +Y...
(14) In this embodiment, the compressor 1 is of a variable capacity type that can change the discharge volume M, but it may also be of a type that has a constant capacity and changes the rotational speed, or it may be of a type that changes the rotation speed without changing the discharge volume. , that is, the inhalation volume may be changed. In short, the discharge mass per unit time of compressed refrigerant as a variable capacity compressor (or the suction mass per unit time of refrigerant before compression)
It is fine as long as it can change.

Further, without providing the pressure sensor 23, the refrigerant evaporation temperature TR may be directly detected by a temperature sensor in the evaporator 9 and used as a physical quantity related to the evaporation temperature of the refrigerant. This (a) may be the temperature of the air immediately after passing through the evaporator 9, the temperature of the blown air, or room temperature.

In the above example, the degree of superheating SH was determined from the difference between the superheated steam temperature TS at the outlet of the evaporator 9 and the refrigerant evaporation temperature TR.
A refrigerant temperature sensor may be provided at each entrance and exit of the evaporator 9, and the degree of superheat may be determined from the refrigerant temperature difference.

The variable opening expansion valve 7 has an adjustable opening, but it is an expansion valve with a fixed opening, and a separate control valve for adjusting the refrigerant flow rate is provided upstream of the expansion valve, so that the combination of the two can be varied. It may also be driven by an opening expansion valve.

In this embodiment, the operation panel] 3 corresponds to the capacity switching instruction means for instructing the switching of the capacity of the refrigeration cycle, and the target value of the evaporation temperature was switched according to the operation of the operation panel 13 by the passenger. As a capability switching instruction means other than the operation panel 13, it is preferable to use a temperature sensor installed inside and outside the companion vehicle or a solar radiation sensor that measures the amount of solar radiation.

Using such sensors, for example, the appropriate cooling capacity can be demonstrated according to the air conditioning environment such as the air volume that is automatically set according to the temperature inside the car, each temperature inside and outside the car, and the amount of solar radiation. The target value of the evaporation temperature may be changed.

In this embodiment, deviation calculation processing (step] 60)
and the PID calculation process (step 170) correspond to the process as the first calculation means and the second calculation means, and the calculation process of the valve opening/rotation speed operation amount (step 180) corresponds to the process as the compensation means. . In addition, the first pseudo operation factor x in the embodiment is the first calculated amount, the second pseudo operation amount Y is the second calculated amount, α
corresponds to the first element (2 β corresponds to the second element, and b22 (0) corresponds to the third element. Therefore, in this example, the proportional gain Kl of PID control, and 2 correspond to the first calculated amount and the second calculated amount. However, the gain Kl of PID control is calculated by the compensation means without being included in the first calculated amount and the second calculated amount.
, may have a value of 2. In this case, PID control will be included in the compensation means.

Effects of the Invention In the refrigeration cycle control device of the present invention, the second element and the first element multiplied by the first calculated amount of the mutual interference compensation element used in the compensation means are theoretical values excluding dynamics factors. The ratio is set large compared to what was calculated.

Therefore, mutual interference can be eliminated as much as possible, heat conductivity control with low responsiveness can be speeded up, and refrigeration cycle control with high responsiveness can be realized from the initial stage.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram conceptually illustrating the content of the present invention, Fig. 2 is a schematic system configuration diagram showing an embodiment of the present invention, and Fig. 3 is an electronic control circuit for implementing the invention. FIG. 4 is a flowchart of the control process, FIG. 4 is a map showing the relationship between the set room temperature and the target refrigerant evaporation temperature, FIG. 5 is a control block diagram, and FIG. 6 is a timing chart showing the operation of this embodiment. [Figure 1]...Variable capacity compressor 7...Variable opening expansion valve]]a...Promoter motor 21...Temperature sensor 25...Electronic control circuit 3...Condenser 9... Evaporator 13...operation panel 23...pressure sensor 7...capacity adjustment solenoid valve

Claims (1)

[Scope of Claims] 1. A control device for a refrigeration cycle in which at least a variable capacity compressor, a condenser, a variable opening expansion valve, and an evaporator are arranged in order along the flow of refrigerant, the control device comprising: evaporation temperature related physical quantity detection means for detecting an evaporation temperature related physical quantity related to temperature; superheat degree related physical quantity detection means for detecting a superheat degree related physical quantity related to the superheat degree of the refrigerant vapor generated by the evaporator; capacity switching instructing means for instructing switching of the capacity of the cycle; target setting means for setting at least a target value of the evaporation temperature related physical quantity in response to the capacity switching instruction; a first calculation means for calculating a first calculation amount based on the deviation; a second calculation means for calculating a second calculation amount based on the deviation between the superheat degree-related physical quantity and its target value; and a mutual interference compensation element. Compensating means that outputs a capacity-related manipulated variable of the variable capacity compressor and an opening-related manipulated variable of the variable-opening expansion valve from an input consisting of the first calculated amount and the second calculated amount; and the mutual interference compensation element includes at least a first element that is multiplied by the first calculated amount to calculate the capacity-related manipulated variable, and a first calculated amount that is multiplied by the first calculated amount to calculate the opening-related manipulated variable. and a third element that is multiplied by the second calculated amount, and the absolute value of the ratio of the second element and the first element excludes the dynamics factor of the refrigeration cycle. A refrigeration cycle control device characterized in that the ratio is larger than the absolute value of a corresponding element among mutual interference compensation elements calculated by a method of removing mutual interference based on a set input/output transfer function.