JP2002022288A - Controller for refrigeration cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for a refrigeration cycle capable of properly controlling the valve travel of an expansion valve and restricting and avoiding unnecessary variation of pressure of the refrigeration cycle. SOLUTION: The valve travel of the expansion valve calculated on the basis of a target pressure calculated from temperature of a high pressure line and an actual pressure of the high pressure line is corrected on the basis of temperature difference between a target temperature of an evaporator and an actual temperature so that correction can be made in advance before variation in the refrigerant circulation quantity of the refrigeration cycle (discharge capacity of compressor) changing in response to the temperature difference of the evaporator occurs. Thus, response of the expansion valve to the variation of pressure of the high pressure line can be raised so that fluctuation in pressure of the refrigeration cycle can be stabilized in an early stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor using carbon dioxide as a refrigerant and having a discharge capacity changed by a control signal from the outside, a radiator for cooling a high-pressure refrigerant discharged from the compressor, While reducing the pressure of the refrigerant cooled by the radiator, the valve opening degree is changed by an external control signal, an electric expansion valve, and an evaporator that evaporates the low-pressure refrigerant flowing out of the expansion valve. The present invention relates to a refrigeration cycle control device that controls a refrigeration cycle constituted at least by the above.

[0002]

2. Description of the Related Art A supercritical refrigeration cycle disclosed in Japanese Patent Application Laid-Open No. 11-304268 discloses a variable displacement compressor configured to reduce the amount of refrigerant discharged in response to a decrease in suction pressure. A radiator that cools the refrigerant discharged from the type compressor, an electric expansion valve that is disposed on the outlet side of the radiator and whose valve opening is variably controlled, and a refrigerant that flows out of the electric expansion valve An evaporator for evaporating, and in a supercritical refrigeration cycle in which the high-pressure side refrigerant is compressed to a supercritical region, when the amount of refrigerant discharged from the variable displacement compressor changes (reduces), When the opening degree of the expansion valve is fixed for a predetermined time, and when the discharged refrigerant amount does not change, the valve opening degree of the electric expansion valve is changed so that the refrigerant temperature and pressure at the outlet side of the radiator change along the optimal control line. To control It is intended.

[0003]

In general, in a refrigeration cycle using a carbon dioxide refrigerant as a refrigerant having a variable displacement compressor and an electric expansion valve, if the compressor has a small discharge capacity in order to adjust the refrigeration capacity, the outlet of the radiator is required. Side refrigerant pressure drops. On the other hand, the expansion valve attempts to increase the refrigerant pressure on the outlet side of the radiator by reducing the valve opening so as to maintain a pressure corresponding to the refrigerant temperature on the outlet side of the radiator. As described above, the compressor controls the discharge capacity in accordance with the required refrigerating capacity, while the expansion valve controls the high pressure in accordance with the refrigerant temperature at the outlet of the radiator. The simple control of the combination does not provide the appropriate control.

In order to solve the above problem, Japanese Patent Laid-Open No.
In the refrigeration cycle according to JP-A-304268, the variable displacement compressor is less affected by the expansion valve, and the refrigeration cycle is appropriately controlled. There is a problem that there is a time delay before the suction pressure changes and the time is not constant, so that an erroneous determination may be made.
For example, since the pressure change is not transmitted immediately after the compressor changes the discharge capacity, it is determined that the pressure change is small and the expansion valve is driven, and immediately after the pressure changes, the entire cycle is unnecessarily changed. The problem described above occurs. Furthermore, since the pressure sensor for detecting the suction pressure is expensive, there is a problem that the cost of the system is increased.

Accordingly, an object of the present invention is to provide a refrigeration cycle control device capable of appropriately controlling the opening degree of an expansion valve and suppressing and preventing unnecessary pressure fluctuations of the refrigeration cycle.

[0006]

Accordingly, as shown in FIG. 1, the present invention relates to a compressor provided with a variable displacement mechanism for changing the displacement, and a radiator for cooling the high-pressure refrigerant discharged from the compressor. An expansion unit that lowers the pressure of the refrigerant cooled by the radiator and has a valve opening variable by an external control signal, and an evaporator that evaporates the low-pressure refrigerant flowing out of the expansion unit. In the refrigeration cycle configured, air temperature detecting means 1 for detecting the temperature of the air passing through the evaporator
5, an air temperature setting means 30 for setting a target temperature of the air passing through the evaporator, and a refrigerant temperature detecting means 13 for detecting a refrigerant temperature in a high pressure line from a discharge side of the compressor to an inflow side of the expansion means. A high pressure detecting means 14 for detecting the pressure of the high pressure line; a target high pressure calculating means 32 for calculating a target high pressure based on the refrigerant temperature detected by the refrigerant temperature detecting means 13; A valve opening calculating means 34 for calculating the valve opening of the expansion means 5 based on the actual high pressure detected by the pressure detecting means 14 and the target high pressure calculated by the target high pressure calculating means 32; 15 and the air temperature setting means 3
A temperature difference calculating means 36 for calculating a temperature difference between the target temperature of the air passing through the evaporator and a target temperature set by 0, and the valve opening degree calculating means 34 based on the calculation result of the temperature difference calculating means 36. Opening correction means 38 for correcting the valve opening calculated by the above, and valve opening control means for outputting a control signal to the expansion means 5 based on the valve opening corrected by the valve opening correction means 38 40.

Therefore, according to the present invention, the degree of opening of the expansion valve, which is calculated from the target pressure calculated from the high-pressure line temperature and the actual pressure in the high-pressure line, is determined by the target temperature of the evaporator and the actual Since the correction is performed based on the temperature difference between the temperatures, the correction can be made before the fluctuation of the refrigerant circulation amount (discharge capacity of the compressor) of the refrigeration cycle which changes due to the temperature difference of the evaporator. The responsiveness of the valve can be improved, and the above object can be achieved.

Further, in the present invention, the variable displacement mechanism provided in the compressor is controlled by an external control signal and detected by the air temperature setting means and the target temperature set by the air temperature setting means. Discharge capacity calculation means for calculating the discharge capacity of the compressor based on the actual temperature thus obtained; and compressor capacity control means for outputting a control signal to the compressor based on the discharge capacity calculated by the discharge capacity calculation means. Is provided.

Thus, in a configuration in which the discharge capacity of the compressor is controlled by an external signal, the valve opening is corrected based on the factor for calculating the discharge capacity of the compressor and the temperature difference between the actual temperature of the evaporator and the target temperature. Therefore, the opening degree of the expansion valve can be corrected simultaneously with the change in the displacement of the compressor, so that the responsiveness of the expansion valve can be improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

The refrigeration cycle 1 shown in FIG. 2 uses a supercritical refrigerant such as carbon dioxide as the refrigerant, and has a variable displacement mechanism 9 for varying the discharge displacement based on the pressure on the low pressure side. A variable displacement compressor 2 whose on / off is controlled by an electromagnetic clutch 8 using an engine for driving as a drive source. The refrigeration cycle 1 has a radiator 3 for cooling the refrigerant compressed to a supercritical region by the compressor 2, and an outlet side of the radiator 3 has a high-pressure side constituting an internal heat exchanger 4. The high-pressure refrigerant passing through the heat exchanger 4a is cooled by the low-pressure refrigerant. An electric expansion valve (hereinafter, expansion valve) 5 whose opening degree is adjusted by a control signal from the control unit 10 is provided on the outflow side of the high-pressure side heat exchanger 4a. The path from the discharge side of the compressor 2 to the inflow side of the electric expansion valve 5 is a high-pressure line 1.
1.

At the outflow side of the expansion valve 5, the expansion valve 5
An evaporator 6 is provided for evaporating the refrigerant which has been throttled down and reduced in pressure to the gas-liquid mixing region. The evaporator 6 absorbs heat of air passing through the air conditioning duct 22 and cools the air. On the outflow side of the evaporator 6, an accumulator 7 is provided. The accumulator 7 performs gas-liquid separation to supply only the gas phase component of the refrigerant to the compressor 2 and adjusts the amount of the refrigerant circulating in the refrigeration cycle 1. The refrigerant flowing out of the accumulator 7 is heated by the heat of the high-pressure refrigerant by passing through the low-pressure side heat exchanger 4b of the internal heat exchanger 4, and is sucked into the compressor 2. The path from the outflow side of the expansion valve 5 to the suction side of the compressor 2 forms a low-pressure line 12.

A control unit 10 is provided to control the refrigeration cycle 1 having the above configuration. The control unit 10 is a known unit that includes at least a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), an input / output port (I / O), and the like. 11, a refrigerant temperature sensor 13 for detecting the temperature (Tref) of the high-pressure refrigerant, a pressure sensor 14 for detecting the pressure (PH) of the high-pressure refrigerant, and a blowing temperature (Teva) of the evaporator 6. ), An indoor temperature sensor 16 for detecting a vehicle interior temperature (Tinc), an outdoor air temperature sensor 17 for detecting an outdoor air temperature (Tam), a solar radiation sensor 18 for detecting an amount of solar radiation (Qsun), and , Temperature setting switch 2 on operation panel 19
At least a temperature setting signal (Tptc) from 0, an on / off signal from an A / C switch 21 for controlling on / off of the electromagnetic clutch 8, and a setting signal (Teva_set) from a volume switch 30 for setting an evaporator temperature are input. This is processed by a predetermined program as shown in the flowchart, and is output as a control signal to the electromagnetic clutch 8, the variable displacement mechanism 9, the expansion valve 5, and the like.

The control executed by the control unit 10 according to the embodiment of the present invention will be described below with reference to flowcharts.

FIG. 3 shows a basic flowchart 100 of the refrigeration cycle control. This flowchart 1
00 is, for example, periodically started from the main control routine of the air conditioning control. In step 110, initialization of various signals can be performed, and in step 120, signal processing calculation is performed. In the signal processing calculation in step 120, each of the sensors 13, 14, 15, 16,
The signals from 17, 17 and the setting signal from the operation panel 19 are read, and are processed into operation signals which can be respectively operated to calculate the target outlet temperature (Tao). This operation is performed by the following equation: Tao = (A + D) * T'pt
It is calculated by c + B * Tam-D * tinc + C * Q'sun + E. In this equation, T ′
ptc is a temperature setting signal T from the temperature setting switch 20.
This is a temperature setting signal calculated from ptc, and Q'sun
Is an insolation signal calculated from the insolation signal Qsun from the insolation sensor 18, A, B, C, and D are operation constants for weighting the respective signals, and E is a correction term.
In the above configuration, an evaporator temperature setting volume is provided on the operation panel 19 to set the evaporator temperature. However, in this step, a target value of the evaporator temperature may be calculated from the target outlet temperature Tao. Things.

Then, after step 120, step 2
At 00, control of the electromagnetic clutch 8 (Mgcl control) as shown in FIG. 4 is executed. In this electromagnetic clutch control, at step 202, the A / C
Whether the switch 21 is turned on (A / C SW
ON)), and if the A / C switch 21 is not turned on (N), the routine proceeds to step 216, where the compressor 2 is turned off (COMP OFF), and the energization to the electromagnetic clutch 8 is stopped. Then, the connection to the driving engine (not shown) is cut off, and the compressor 2 is stopped.

If it is determined in step 202 that the A / C switch 21 is turned on, then in step 204, the high pressure PH of the refrigeration cycle 1 is increased to a predetermined pressure range P3 to P4 (for example, , 11M
It is determined whether the pressure is equal to or higher than Pa to 15 MPa). If the high pressure is higher than a predetermined pressure (A), the process proceeds to step 216 to stop the compressor 2 for safety. In addition, the high pressure PH is in the predetermined pressure range P3.
If the pressure is equal to or less than P4 (B), the routine proceeds to step 206, where it is determined whether or not the high pressure PH is within a predetermined pressure range P1 to P2 (for example, 3.5 MPa to 3.9 MPa). If it is determined in step 206 that the high pressure PH is equal to or less than the predetermined pressure range P1 to P2 (D), it is determined that the refrigerant is insufficient, and step 216 is performed.
Then, the compressor 2 is stopped. If it is determined in step 206 that the high pressure PH is equal to or higher than the predetermined pressure range (C), the process proceeds to step 208 to determine the actual evaporator temperature (Teva). In this determination, the evaporator temperature (Teva)
Is equal to or lower than a predetermined temperature T1 (for example, 1.5 ° C.), it is determined that the evaporator temperature is low, and the predetermined temperature T1 is determined.
In the case of 1 or more, it is determined that the evaporator temperature is high. In this determination, hysteresis is formed, and the temperature range Th is, for example, 2.5 ° C. The result of this determination is determined in step 210, and if it is determined that the evaporator temperature (Teva) is low, the process proceeds to step 212, where the operation of the compressor 2 is continued for a time t1 (for example, 60 seconds), and the operation is continued for a time t1 Step 2 after lapse
Proceeding to 16, the compressor 2 is stopped. If the evaporator temperature (Teva) is not low in the determination in step 210, the process proceeds to step 214, where the operation of the compressor 2 is set (COMP ON), and the electromagnetic clutch 8 The compressor 2 is operated by being energized and connected to a running engine (not shown).

After the electromagnetic clutch control of the compressor 2, the control of the capacity of the compressor 2 is executed in step 300. The capacity control of the compressor 2
For example, as shown in FIG.
It is determined whether the C switch 21 is turned on. If the switch is not turned on (N), the process proceeds to step 304, where the proportional component D of the capacity control duty ratio D output to the capacity control mechanism 9 is output.
p is set to “0”, and further proceeds to step 306, where the integral component Di (t
−Δt) is set to “0”, and in step 308, the capacity control duty ratio D is set to “0”.
At 80, the capacity control duty ratio D is output. still,
In this case, the capacity control duty ratio D is not substantially output. Further, in the capacity control duty ratio D, when the duty ratio is 0 [%], the valve of the capacity control mechanism 9 is fully opened, high pressure is introduced into the back pressure chamber (not shown) of the compressor 2 and the minimum capacity is obtained. Is 100
At the time of [%], the valve is fully closed and high pressure is not introduced into the back pressure chamber, so that the maximum capacity is obtained.

If it is determined in step 302 that the A / C switch 21 is turned on (Y), the process proceeds to step 310, where the evaporator temperature setting volume switch (EVA temperature setting VR) 3
Target evaporator temperature Teva_s according to level of 0
et is set. In step 310, Te
1 is set to 2 ° C., and Te 2 is set to 15 ° C. In this step 310, the evaporator temperature is set manually by the evaporator temperature setting volume switch 30, but may be obtained based on the above-described target blowout temperature (Tao). In this case, the target evaporator temperature Teva_set is 2 ° C. when the target blowout temperature Tao is 10 ° C., and the target blowout temperature Tao is 30 ° C. in the characteristic line shown in the block of step 310.
The target evaporator temperature Teva_set is 15 ° C
It is desirable that

Then, the routine proceeds to step 320, where a capacity calculation duty ratio (0 to 100%) DT is calculated. The calculation of the capacity calculation duty ratio DT is, for example, as shown in FIG. 6. First, in step 322, the proportional component Dp of the capacity calculation duty ratio DT is calculated. The proportional component Dp is represented by the characteristic line shown in FIG. 7 and the temperature difference ΔTe between the actual evaporator temperature Teva and the target evaporator temperature Teva_set set in the step 310.
It is calculated from va. Basically, when the temperature difference is −20 ° C., the proportional component Dp is “0%” and the temperature is + 20 ° C.
In this case, the proportional component Dp is calculated from the temperature difference based on the primary characteristic line that changes so that the proportional component Dp becomes “100%”.

Further, in step 324, the temperature difference ΔTeva (ΔTev) is determined based on the characteristic line shown in FIG.
a = Teva−Teva_set), the change ΔDi of the integral component is calculated. Then, in step 326, the t-time integral component Di (t) is calculated by the equation {Di (t) = Di (t−Δt) + ΔDi} shown in step 326. Note that this Δt is 100 msec.

Then, at step 328, it is determined whether or not the t-time integral component Di (t) is 50% or more.
A determination is made whether i (t) is less than or equal to -50%. In the above determination, the t-time integral component Di
If (t) is 50% or more, step 32
8, the flow advances to step 332 to set the integral component Di to 50.
[%], And the t-time integral component Di (t) is −5.
If it is not more than 0 [%], the process proceeds from step 330 to step 334 to limit the integral component Di to -50 [%]. Further, the t time integral component Di (t) is -50 to
If it is within the range of +50 [%], step 330
Then, the process proceeds to step 336 to set the t-time integral component Di (t) as the integral component Di. Then, the integral component Di set in step 332, 334 or 336 and the proportional component Dp set in step 322 are set.
Thus, in step 338, the capacity calculation duty ratio DT is calculated (DT = Dp + Di). Then, in step 340, the integral component Di is calculated for a predetermined time Δ
t is set as a time integral component D (t−Δt) before t,
The process returns to the control routine shown in FIG. Then, at step 350, the capacity calculation duty ratio DT is set as the capacity control duty ratio D, and at step 380, the capacity control duty ratio D is output.

After the capacity control in step 300, the control of the expansion valve 5 is executed in step 400. The control of the expansion valve 5 is, for example, as shown in FIG.
First, in step 402, it is determined whether or not the compressor 2 is operating (COMP ON?).
In this determination, if the compressor 2 is not operating (N), the routine proceeds to step 404, where the proportional component Eph_p of the duty ratio of the valve opening control duty ratio EXP output to the electromagnetic coil (not shown) of the expansion valve is provided. Is set to “0”, and in step 406, the integral component Eph_i (t−Δt) before the time Δt is set to “0”, and in step 408, the valve opening control duty ratio E
XP is set to “0”, and from step 500, the valve opening control duty ratio EXP is output to the electromagnetic coil of the expansion valve. In this case, in step 500, the valve opening control duty ratio EXP is not substantially output. Also,
In the valve opening control duty ratio EXP, when the duty ratio is 0 [%], the expansion valve 5 is fully opened and the duty ratio is 10%.
It is fully closed when it is 0 [%].

If it is determined in step 402 that the compressor 2 is operating, then in step 410 the target high pressure PHset is
Equation (PHset = A * T) shown in block 10
ref + B) is calculated from the refrigerant temperature Tref. Then, in step 412, step 410
It is determined whether or not the target high pressure PHset calculated in is lower than a predetermined pressure P1 (for example, 14 MPa). If the target high pressure PHset is equal to or higher than the predetermined pressure P1 (N),
Proceeding to step 414, the target high pressure PHset is set so that the target high pressure PHset does not exceed the predetermined pressure P1.
A predetermined pressure P1 is set to set as an upper limit pressure. When the target high pressure PHset is equal to or lower than the predetermined pressure P1, the target high pressure PHset calculated by the above formula is used, bypassing the step 414.

In step 420, a valve opening calculation duty ratio Eph is calculated. The calculation of the valve opening calculation duty ratio Eph is, for example, as shown in FIG.
In this calculation flowchart, first, step 422 is executed.
Sets constants used in the calculations in steps 424 and 426. This constant is, for example, a1 is 0.
5, b1 is 0.5 and c1 is 0.05. In step 424, the proportional component Eph_p of the valve opening duty ratio is calculated from the temperature difference ΔTeva between the evaporator temperature Teva and the evaporator target temperature Teva_set based on the characteristic line shown in FIG.
Note that this characteristic line is 0 when the temperature difference is -0.5 ° C.
[%] (Fully open), +0. It changes linearly to 100% (fully closed) at 5 ° C.

Further, in step 426, the variation ΔEph_i of the integral component is calculated from the above-mentioned temperature difference ΔTeva based on the characteristic line shown in FIG. Then, in step 428, the t time integral component Eph_i (t) is expressed by the equation {Eph_i (t) = Eph_i (t-
Δt) + ΔEph_i｝. this is,
It is obtained by adding ΔEph_i calculated in step 426 to the integral component Eph_i (t−Δt) before Δt time.

Then, it is determined in step 430 whether or not the t-time integral component Eph_i (t) calculated in step 428 is 50% or more.
At 30, the integral component Eph_i (t) is -50 [%].
It is determined whether or not: In these determinations, if the t-time integral component Eph_i (t) is equal to or more than +50 [%], the process proceeds from step 430 to step 434, where the integral component Eph_i is set to the upper limit 50 [%], If the integral component Eph_i (t) is equal to or smaller than -50 [%], the process proceeds from step 432 to step 436, where the lower limit value -50 [%] is set for the integral integral Eph_i.
And the t time integral component Eph_i (t) is -50.
If it is between +50 [%], the process proceeds from step 432 to step 438 to set the t-time integral component Eph_i (t) as the integral component Eph_i. Then, at step 440, the valve opening calculation duty ratio Eph
To the equation (Eph) shown in the block of step 440.
= Eph_p + Eph_i). Further, in step 442, the integral component Eph_i set in the above step 434, 436 or 438 is Δt
This is set as the integral component Eph_i (t−Δt) before the time, exits from the Eph calculation routine, and returns to the control routine shown in FIG.

After calculating the valve opening degree duty ratio Eph, at step 450, the temperature difference ΔTev
It is determined whether or not the absolute value of a is equal to or smaller than a predetermined value β. Then, in step 450, the temperature difference ΔTe
If it is determined that va is equal to or smaller than the predetermined value β (Y), it is not necessary to greatly change the refrigerant circulation amount of the refrigeration cycle 1, so that the change in the discharge capacity of the compressor 2 is suppressed. The pressure fluctuation in the line 11 is reduced. As a result, it is assumed that no problem occurs even if the opening degree of the expansion valve 5 is controlled based on the calculated value.
At step 60, the duty ratio of the valve opening control duty ratio EXP supplied to the electromagnetic coil of the expansion valve 5 is set to Eph, and output to the expansion valve 5 at step 500. In step 450, the temperature difference ΔTe
When it is determined that va is larger than a predetermined value β (N)
Since it is necessary to greatly change the refrigerant circulation amount of the refrigeration cycle 1, the change in the discharge capacity of the compressor 2 is increased, and the latest calculation is performed based on the high pressure that changes following the change in the capacity. Calculation duty ratio E of
In ph, since there is a possibility that the entire cycle fluctuates unnecessarily, step 460 is avoided, and
This is to maintain the previous valve opening control signal. As a result, the opening degree of the expansion valve 5 is fixed, so that the temperature difference Δ between the actual temperature of the evaporator 6 and the target temperature.
It is possible to suppress the pressure fluctuation of the refrigeration cycle 1 due to Teva at an early stage. Also, at the calculation stage,
Since the valve opening of the expansion valve 5 can be adjusted according to the fluctuation of the temperature difference ΔTeva, the responsiveness of the expansion valve 5 can be improved.

Hereinafter, other embodiments of the present invention will be described. The same portions and portions having the same effects are denoted by the same reference numerals and description thereof is omitted.

FIG. 13 shows a second embodiment of the present invention. In the second embodiment, after the determination in the step 450, the temperature difference Δ
If Teva is within the predetermined range, step 45
1, the numerical values a, b, and c of the characteristic lines shown in FIGS.
= 0.5, b1 = 0.5, c1 = 0.05)
If the temperature difference ΔTeva is out of the predetermined range, in step 453, the numerical values a, b, and
c is a2, b2, c larger than a1, b1, c1
2 (for example, a2 = 5, b2 = 2, c2 = 0.5). Accordingly, when the temperature difference ΔTeva is large, the proportional component Eph_ of the valve opening calculation duty ratio Eph calculated from the temperature difference is used.
p and the rate of change of the integral component Eph_i can be reduced, so that the expansion valve 5
Operation can be suppressed.

Accordingly, when the change in the calculation result of the discharge capacity of the compressor 2 is large, the valve opening calculation duty ratio Eph of the expansion valve 5 is set in a direction to suppress the change in the valve opening caused by the change in the compressor discharge capacity. Since the correction is made, the pressure fluctuation of the refrigeration cycle 1 can be stabilized at an early stage.

In the third embodiment shown in FIG. 14, the temperature difference Δ
When the absolute value of Teva is equal to or smaller than the predetermined range β, or in step 408, the valve opening control duty ratio EXP
Is set to "0" in step 464, the flag A (Flag A) is set to "0".

If it is determined in step 450 that the absolute value of the temperature difference ΔTeva is out of the predetermined range β, the flag A is determined in step 452, and if the flag A is “0” (Y). Contains step 45
Proceeding to 4, it is determined whether the temperature difference ΔTeva is positive or negative.
If the temperature difference ΔTeva is positive (N) in the determination of step 454, it can be determined that the temperature difference ΔTeva greatly changes (the high pressure increases) in the direction of increasing the refrigerant circulation amount. A value obtained by adding a predetermined value R (for example, 20%) to the valve opening calculation duty ratio Eph is set to the opening control duty ratio EXP. As a result, a predetermined value R is added to the valve opening calculation duty Eph, which is estimated to be calculated so that the expansion valve 5 is controlled to open. .

If the temperature difference ΔTeva is negative (Y) in the determination in step 454, it can be determined that the refrigerant circulation amount largely changes in the direction of decreasing the refrigerant circulation amount. The duty ratio EXP and the valve opening calculation duty ratio Eph have a predetermined value R.
(Eg, 20%) is subtracted. This corrects the valve opening in the opening direction by subtracting a predetermined value R from the valve opening calculation duty ratio Eph estimated to be operated so that the expansion valve 5 is controlled in the closing direction. It is. Then, in step 462, the flag A is set to "1", and the valve opening control duty ratio EXP to which the corrected value has been set is output from step 500. If “1” is set in the flag A, in step 450, the temperature difference ΔTe
If it is determined that the change of va is large, the process proceeds to step 500 in the determination of step 452, so that the corrected valve opening is maintained.

In the fourth embodiment shown in FIG. 15, when the absolute value of the temperature difference ΔTeva is equal to or more than a predetermined value β, it is determined in step 452 whether or not the flag A is “0”. If “Y” (Y), step 453 is executed.
In the case where the latest valve opening calculation duty ratio Eph is set as the reference duty ratio Eph0 and the flag A is set to "1" (N), the Eph0 has already been set.
Is set, step 453 is bypassed.
Then, in step 455, it is determined whether or not the valve opening calculation duty ratio Eph is equal to or more than the reference duty ratio Eph0 + 20 [%]. Further, in step 457, the valve opening calculation duty ratio Eph is changed to the reference duty ratio Eph.
It is determined whether it is ph0-20 [%] or less. Accordingly, when the valve opening calculation duty ratio Eph is larger than the reference duty ratio Eph0 by 20% or more, the process proceeds from step 455 to step 459, where the valve opening degree duty ratio Eph is limited to Eph0 + 20%. The opening calculation duty ratio Eph is equal to the reference duty ratio Eph
If it is smaller than 0 by 20% or more, step 45
7 to step 461, where the valve opening duty ratio E
Limit ph to 0-20% Eph. As a result, the valve opening calculation duty ratio Eph set to be restricted in step 459 or step 461 is changed to step 4
At 63, the valve opening control duty ratio EXP is set. Only when the valve opening calculation duty ratio Eph is within the range of the reference duty ratio Eph0 ± 20 [%], in step 463, the valve opening calculation duty ratio Eph is directly set to the valve opening control duty ratio EXP. Is done. Then, at step 465, "1" is set to the flag A.

With the above configuration, when the change in the temperature difference ΔTeva is large, the valve opening calculation duty ratio Eph for determining the valve opening of the expansion valve 5 is changed to the reference duty ratio Eph0.
Since the restriction is made within the range of ± 20 [%], the opening degree of the expansion valve 5 with respect to the fluctuation of the high pressure caused by the fluctuation of the circulating refrigerant amount of the refrigeration cycle 1 (the fluctuation of the discharge capacity of the compressor 2). Fluctuations can be suppressed.

[0037]

As described above, according to the present invention, the opening degree of the electric expansion valve is determined based on the temperature difference between the target temperature of the evaporator and the actual temperature, which is one of the causes of the fluctuation of the refrigerant circulation amount. Since the calculation result of the calculation is corrected, the response delay of the expansion valve can be avoided, and the pressure fluctuation of the refrigeration cycle can be stabilized early. Also,
Since the expansion valve control corresponding to the pressure fluctuation can be performed before the high-pressure pressure changes, more appropriate control can be performed, and the stable performance of the refrigeration cycle can be maintained. Further, according to the present invention, it is not necessary to provide a pressure sensor for detecting the suction pressure, so that an increase in the cost of the system can be avoided.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing a configuration of a refrigeration cycle according to the present invention.

FIG. 3 is a flowchart illustrating a main control routine of refrigeration cycle control according to the embodiment of the present invention.

FIG. 4 is a flowchart showing an electromagnetic clutch control routine according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating a compressor capacity control routine according to the embodiment of the present invention.

FIG. 6 is a flowchart showing a calculation routine of a capacity calculation duty ratio DT in a compressor capacity control routine according to the embodiment of the present invention.

FIG. 7 is a characteristic line showing a characteristic line for calculating a proportional component Dp of a duty ratio from a temperature difference between an actual temperature of an evaporator and a target temperature in an operation routine of a capacitance operation duty ratio DT according to the embodiment of the present invention. FIG.

FIG. 8 is a characteristic line for calculating a variation ΔDi of an integral component of a duty ratio from a temperature difference ΔTeva between an actual temperature of an evaporator and a target temperature in a calculation routine of a capacitance calculation duty ratio DT according to the embodiment of the present invention. FIG. 7 is a characteristic diagram shown.

FIG. 9 is a flowchart illustrating an electric expansion valve control routine according to the first embodiment of the present invention.

FIG. 10 is a valve opening calculation duty ratio Ep in an electric expansion valve control routine according to the first embodiment of the present invention;
FIG. 9 is a flowchart illustrating an h calculation routine.

FIG. 11 is a diagram illustrating a characteristic of calculating a proportional component Eph_p of a duty ratio from a temperature difference ΔTeva between an actual temperature of an evaporator and a target temperature in a calculation routine of a valve opening calculation duty ratio Eph according to the first embodiment of the present invention. FIG. 4 is a characteristic diagram showing a line.

FIG. 12 is a flowchart showing a routine for calculating a duty ratio Eph for calculating a valve opening degree according to the first embodiment of the present invention. FIG. 4 is a characteristic diagram illustrating a characteristic line to be calculated.

FIG. 13 is a flowchart showing only a characteristic part of the second embodiment in a calculation routine of the valve opening calculation duty ratio Eph according to the second embodiment of the present invention.

FIG. 14 is a flowchart showing only a characteristic portion of the third embodiment in a calculation routine of the valve opening calculation duty ratio Eph according to the third embodiment of the present invention.

FIG. 15 is a flowchart showing only a characteristic portion of the fourth embodiment in a calculation routine of the valve opening calculation duty ratio Eph according to the fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 2 Compressor 3 Radiator 4 Internal heat exchanger 5 Electric expansion valve 6 Evaporator 8 Electromagnetic clutch 9 Variable capacity mechanism 10 Control unit 11 High pressure line 12 Low pressure line

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenji Iijima 39, Higashihara, Chiyo, Odai-gun, Osato-gun, Saitama

Claims (2)

[Claims] 1. A compressor having a variable displacement mechanism for changing a discharge capacity, a radiator for cooling high-pressure refrigerant discharged from the compressor, a valve for reducing the pressure of the refrigerant cooled by the radiator, and a valve. In a refrigeration cycle at least comprising an expansion means whose opening degree is varied by a control signal from the outside and an evaporator for evaporating the low-pressure refrigerant flowing out of the expansion means, the temperature of air passing through the evaporator Air temperature detecting means for detecting, air temperature setting means for setting a target temperature of air passing through the evaporator, and refrigerant for detecting a refrigerant temperature in a high pressure line from a discharge side of the compressor to an inflow side of the expansion means. Temperature detection means, high-pressure pressure detection means for detecting the pressure of the high-pressure line, refrigerant temperature detected by the refrigerant temperature detection means A target high pressure calculating means for calculating a target high pressure based on the actual high pressure detected by the high pressure detecting means and a target high pressure calculated by the target high pressure calculating means. And a temperature difference between the actual temperature of the air detected by the air temperature detecting means and the target temperature of the air passing through the evaporator set by the air temperature setting means. Temperature difference calculating means for calculating; valve opening degree correcting means for correcting the valve opening calculated by the valve opening degree calculating means based on the calculation result of the temperature difference calculating means; and valve opening degree correcting means. A refrigeration cycle control device comprising: valve opening control means for outputting a control signal to the expansion means based on the corrected valve opening. 2. A variable displacement mechanism provided in the compressor is controlled by an external control signal, and a target temperature set by the air temperature setting means and an actual temperature detected by the air temperature detecting means. Discharge capacity calculating means for calculating the discharge capacity of the compressor based on temperature; and compressor capacity control means for outputting a control signal to the compressor based on the discharge capacity calculated by the discharge capacity calculating means. Claim 1 characterized by the following:
A refrigeration cycle control device according to the above.