JPH076502B2 - Capacity control method for variable capacity compressor in air conditioner - Google Patents

Description

The present invention relates to a method for controlling the capacity of a variable capacity compressor in a vehicle cooling system, and more specifically, the temperature of air blown from an evaporator repeatedly and largely fluctuates (hunting). In this case, the present invention relates to a capacity control method for appropriately controlling the capacity of the compressor in order to reduce the hunting width.

(Prior Art) Conventionally, a vehicle cooling device includes, for example, as shown in FIG. 7, a variable displacement compressor 2 of an oscillating inclined plate (wobble) type that is rotationally driven by an engine 1, and a discharge chamber of the compressor 2. 3, a condenser 6, an expansion valve 7 and an evaporator 8 which are sequentially connected in the middle of an external pipe 5 connecting the discharge port 3 and the sucker chamber 4 via a discharge port and a sucker port (not shown); The blower 9 for supplying air to the evaporator 8 and the outer surface of the outlet side conduit 5a of the evaporator 8 are attached to detect the refrigerant gas temperature and pressure at the outlet of the evaporator 8 to open the expansion valve 7. And a temperature-sensitive tube 10 for controlling the.

In the rear housing portion of the variable amount compressor 2, as shown in FIG. 6, a solenoid valve 11 which constitutes a variable capacity mechanism is built in. The solenoid valve 11 controls the pressure Pc in the crank chamber 12, and the stroke amount of the piston 14 is changed by the control to change the tilt angle of the swinging tilt plate 13 to control the compression capacity. I am trying to do it. Then, the duty ratio of the solenoid valve 11 is controlled to control the opening / closing of the passage 15 that communicates between the discharge chamber 3 and the crank chamber 12, and the amount of refrigerant gas, which is the discharge pressure Pd, introduced into the crank chamber 12. Is controlled to control the compression capacity of the variable capacity compressor 2. The crank chamber 12 communicates with the suction chamber 4 through a leak passage 16 so that the refrigerant gas blown by from the compression chamber to the crank chamber 12 leaks to the suction chamber 4.

Further, as shown in FIG. 7, the solenoid valve 11 is connected to an arithmetic and control unit 17 for controlling the opening and closing of the solenoid valve 11. The arithmetic and control unit 17 includes a rotation sensor 18 for detecting the number of revolutions of the compressor 2, a temperature sensor 19 for detecting the temperature of the air blown from the evaporator 8, and a voltage of the blower 9 for the evaporator 8. Voltage sensor 2 for detecting the amount of blown air
0, and a temperature sensor 21 for detecting the outside air temperature is connected to each.

Then, the vehicle cooling device is started, and the arithmetic and control unit
The target temperature Tc of the blown air temperature Tf of the evaporator 8 is set by 17, and then the blown air temperature Tf and the outside air temperature are detected by both temperature sensors 19 and 21, and the rotation sensor 18
The voltage sensor 20 detects the rotation speed of the compressor 2 and the amount of air blown out of the evaporator 8, and the arithmetic control unit 17 calculates a capacity control amount based on these detection signals, and a control signal proportional to this. Was input to the solenoid valve 11 to control the duty ratio of the solenoid valve 11 to control the capacity of the compressor 2.

(Problems to be Solved by the Invention) However, in the conventional displacement control method for the variable displacement compressor, the control operation of the solenoid valve 11 is performed independently of the control operation of the expansion valve 7. That is, the expansion valve 7 controls the superheat by the temperature sensing tube 10 at the outlet of the evaporator 8, while the variable displacement compressor controls the above so that the blown air temperature Tf at the outlet of the evaporator 8 is maintained at the target temperature. Since it was controlled by the device 17, it was not always possible to perform the best control as the entire cooling device. That is, if the control amount of the expansion valve 7 and the control amount of the variable displacement compressor 2 do not match well within a certain range of the outlet refrigerant gas temperature of the evaporator 8, the outside air temperature, and the rotation speed, as shown in FIG. As the blown air temperature Tf of the evaporator 8 elapses with time t, it hunts largely up and down with a relatively long cycle across the target temperature Tc,
There has been a problem that the cooling feeling is significantly impaired and the passengers feel uncomfortable.

The object of the present invention is to eliminate the problems existing in the above-mentioned conventional operation control method, and to improve the cooling feeling by suppressing a significant hunting of the air temperature blown out of the evaporator outlet, and to a wide range of cooling devices. An object of the present invention is to provide a capacity control method for a variable capacity compressor in an applicable cooling device.

Configuration of the Invention (Means for Solving Problems) In order to solve the above problems, the present invention sequentially connects a condenser, an expansion valve, and an evaporator to a discharge side port and a suction side port of a variable displacement compressor. In addition, a temperature-sensitive tube for controlling the expansion valve is provided in the outlet side pipe of the evaporator, and the capacity control amount is calculated based on a detection signal from a sensor that detects the temperature of air blown out of the evaporator. In a cooling device including an arithmetic and control unit that outputs a control signal to a variable capacity mechanism of a variable capacity compressor, a current suction temperature or discharge temperature of the refrigerant gas of the variable quantity compressor and a suction temperature before a predetermined time or When the temperature difference from the discharge temperature is within the set temperature range, the capacity control constant in the arithmetic and control unit remains at the initial set value to calculate the capacity control amount, and the temperature difference rises beyond the set temperature range. When The means for calculating the capacity control amount by increasing the capacity control constant and decreasing the capacity control constant and calculating the capacity control amount when the temperature difference falls below the set temperature range. I am collecting.

(Operation) The present invention operates as follows by adopting the above means.

When the air conditioner is activated, the arithmetic and control unit holds the capacity control constant at the initial setting value to calculate the capacity control amount, and the capacity control signal proportional to this controls the capacity variable mechanism of the variable capacity compressor, The discharge air temperature at the outlet of the evaporator is controlled within the allowable temperature range across the target temperature. Then, the control amount of the expansion valve and the capacity control amount of the compressor by the arithmetic and control unit do not match, the temperature of the blown air at the evaporator outlet fluctuates greatly, and the current sucker temperature or discharge temperature of the refrigerant gas and the predetermined time The temperature difference from the previous intake temperature or discharge temperature is
When the temperature rises (falls) beyond the set temperature range, the capacity control constant increases (decreases), the capacity control amount is calculated based on this capacity control constant, and the capacity control signal proportional to this is used to calculate the capacity of the variable capacity compressor. The variable mechanism is controlled. As a result, compared with the control of the discharge air temperature of the evaporator when the control constant is the initial setting value, the control of the blown air temperature is performed to a narrower extent, and the passenger's discomfort is eliminated.

Further, since the present invention is not related to the time constant of the temperature sensing tube of the expansion valve, it can be widely applied to the cooling device.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. In this embodiment, reference numerals 1 to 21 are members having the same functions as those of the conventional cooling device described above, and therefore, the same reference numerals are given and the description of the configuration is omitted.

In the embodiment of the present invention, the discharge temperature sensor 22 for detecting the discharge temperature Td of the refrigerant gas of the compressor is provided in the pipe line 5 from the discharge chamber 3 of the compressor 2 to the condenser 6. This variation of the discharge temperature Td has a correlation with the variation of the blown air temperature Tf at the evaporator outlet together with the intake temperature Ts as shown in FIG. 5, and in the present invention, paying attention to these correlations, the blown air temperature Tf Of the discharge temperature Td or the sucker temperature Ts is sensed, the capacity control constant in the arithmetic and control unit 17 is changed according to this fluctuation, the capacity of the compressor 2 is properly controlled, and the blowout of the evaporator is performed. The air temperature Tf is surely controlled.

Therefore, the arithmetic and control unit 17, the target temperature setting means 23 for setting the target temperature Tc of the blown air at the evaporator outlet,
A discharge temperature for calculating the discharge temperature difference ΔTd (Td1-Td2) between the current discharge temperature Td1 and the discharge temperature Td2 before a predetermined time (for example, 10 seconds) based on the discharge temperature Td from the discharge temperature sensor 22. The capacity control constant is changed according to the discharge temperature difference ΔTd from the difference production means 24 and the discharge temperature difference calculation means 24, and the control amount is calculated based on the changed capacity control constant to change the capacity of the compressor 2. And a capacity control constant changing means 25 for outputting a control signal to the mechanism.

Further, in this embodiment, the discharge temperature difference ΔTd from the discharge temperature difference calculation means 24 is compared with the first to fifth set temperature regions T1 to T5 stored in advance, and the discharge temperature difference ΔTd is set to the first setting. Temperature range
When it is between T1 (for example, −1 to + 1 ° C.), the capacity control constant C of the capacity control constant changing means 25 is set to the initial setting value a.
In the second set temperature range T2 (for example, 1 to 5 ° C.), the capacity control constant of (a + r) obtained by adding the positive variable constant r to the initial set value a, and the third set temperature Area
At T3 (for example, 5 ° C. or higher), after the capacity control amount A is calculated based on the capacity control constant (a + r ′) obtained by adding the variable constant r ′ larger than the variable constant r to the initial setting value a, A capacity control signal proportional to this is output to the variable capacity compressor 2 to control its capacity.

On the contrary, when the discharge temperature difference ΔTd is in the fourth set temperature range T4 (for example, −1 to −5 ° C.) or the fifth set temperature range T5 (for example, 5 ° C. or less), it is a negative variable with respect to the initial set value a. To the (a-r) capacity control constant to which the constant r is added, or to the (a-r ') capacity control constant to which a negative variable constant r'which is smaller than the negative variable constant r is added to the initial setting value After the capacity control amount A is calculated based on this, a capacity control signal proportional to this is output to the variable capacity compressor 2 to control its capacity.

More specifically, when the temperature of the air blown from the evaporator 8 is Tf, the target temperature Tc of the air blown from the evaporator 8 is 6 ° C., and the control amount of the compressor 2 is A, proportional compensation control, A = C1 ( tf-6) differential compensation control, a = C2 · dTf / dt integral compensation ^{control, a = C3 · ▲ ∫ K} 0 ▼ (Tf-6) each capacity control constant C1 in dt three or more types of control, C2, C3 of Of these, the capacity of the variable capacity compressor 2 can be increased or decreased by changing the control constant C1 of the proportional compensation control based on the above-mentioned initial setting value a and the variable constants r and r'as needed. .

Next, the capacity control method of the variable capacity compressor 2 will be described with a focus on the flowchart of FIG.

Now, when the vehicle interior temperature is high and cooling is required, the electromagnetic clutch (not shown) of the compressor 2 is turned on, and the rotation of the engine 1 is transmitted to the rotary shaft of the compressor 2. In, the piston 14 is reciprocated by the swinging inclined plate 13, and the suction refrigerant gas is compressed in the compression chamber and discharged from the discharge chamber 3. The compressed refrigerant gas reaches the evaporator 8 through the condenser 6 and the expansion valve 7, where heat is exchanged and the refrigerant flows into the suction chamber 4.

When the operation of the cooling device is started by the operation of the electromagnetic clutch (not shown), the target temperature setting means 23 sets the target temperature Tc of the air blown from the evaporator outlet, and the rotation speed of the compressor 2 is set by the rotation sensor 18. Air temperature Tf blown out of the evaporator 8
Are constantly detected by the temperature sensor 19. Further, the discharge temperature sensor 22 detects the discharge temperature Td of the refrigerant gas. Further, the capacity control constant C1 of the proportional compensation control is set to the initial setting value a by the arithmetic and control unit 17. The control constants C2 and C3 of the differential compensation control and the integral compensation control are unchanged in this embodiment.

On the other hand, the discharge temperature detected by the discharge temperature difference calculation means 24
The discharge temperature difference ΔTd between the current discharge temperature Td1 and the discharge temperature Td2 a predetermined time before is calculated based on Td, and the temperature difference ΔTd must be within the first set temperature range T1 (-1 to + 1 ° C). If
Since the variable constant r is held at zero, the control constant C1 remains at the initial setting value a, and the arithmetic and control unit 17 controls the control constant C1.
The control amount A of the compressor is calculated based on each compensation control of C3 to C3, and a control signal proportional to this is input to the solenoid valve 11 of the variable displacement compressor 2 to control the displacement. As a result, the outlet air temperature Tf at the evaporator outlet is set to the target temperature Tc as shown in FIG.
It is controlled within the allowable temperature range by sandwiching it.

Then, when the matching between the control amount of the expansion valve 7 and the compressor capacity control amount by the arithmetic control device 17 decreases, and the blown air temperature Tf largely fluctuates upward as shown in FIG. 3, Since the discharge temperature difference ΔTd becomes large and becomes the second or third set temperature range T2, T3, a positive variable constant r or r '(> r) is added to the initial set value a by the capacity control constant changing means 25. Large control constant (a + r) or (a + r ')
Based on the above, the displacement control amount A is calculated by the arithmetic control unit 17, and a control signal proportional to this is output to the solenoid valve 11 of the variable displacement compressor 2. As a result, as shown in FIG. 3, a large upward change in the blown air temperature Tf of the evaporator from the target temperature Tc is suppressed.

On the contrary, when the discharge temperature difference ΔTd coincides with the negative fourth or fifth set temperature range T4, T5, the capacity control constant changing means 25 makes the initial set value a a negative variable constant -r or -r '. (<-
The capacity control amount A is calculated by the arithmetic and control unit 17 based on the control constant (ar) or (ar ′) smaller than the initial setting value a to which r) is added, and a control signal proportional to this is calculated. Output to the solenoid valve 11 of the variable displacement compressor 2. As a result, as shown in FIG. 3, a large downward change of the blown air temperature Tf of the evaporator from the target temperature Tc is suppressed.

In the embodiment of the present invention, it is determined which of the first to fifth set temperature ranges T1 to T5 the discharge temperature difference ΔTd is in, and the positive set value a or the positive set value a is set. Or, a control constant C1 which is obtained by adding negative variable constants r, r ', -r, -r'.
Since the capacity control amount is calculated by the proportional compensation control based on, the capacity control of the compressor 2 can be appropriately performed, and as a result, the fluctuation of the blown air temperature Tf of the evaporator 8 can be suppressed to a small extent. By performing proper cooling, it is possible to eliminate discomfort to passengers.

The present invention can also be embodied as follows.

(1) As shown in FIG. 4, the suction temperature difference ΔTs between the current suction temperature Ts1 and the suction temperature Ts2 before a predetermined time is detected, and the suction temperature difference ΔTs and the first to fifth set temperature ranges T1 are detected. By comparing with ~ T5 and changing the control constant, change the capacity control constant C2 of the differential compensation control and calculate the capacity control amount of the compressor. The operation and effect of this other example are similar to those of the above-described embodiment.

(2) In the above embodiment, the first to fifth set temperature ranges T1 to T5 were compared with the discharge temperature difference ΔTd. When the discharge temperature difference ΔTd is increased or decreased beyond the first set temperature range, Use a switching method with an arbitrary number of steps, such as a three-step switching method that changes the variable constant r.

(3) The discharge temperature Td or the suction temperature Ts is detected, and the variable constant r of the control constant C3 of the integral compensation control is changed based on the temperature difference ΔTd or ΔT. further,
The control constants C1 to C3 of each compensation control of ~ should be changeable as described above.

Effect of the Invention As described in detail above, according to the present invention, when the temperature difference obtained by subtracting the measured value of the intake temperature or the discharge temperature from the current measured value a predetermined time ago exceeds the set temperature range upward or downward. By increasing or decreasing the capacity control constant of the compressor, the capacity control of the compressor can be optimized regardless of the expansion valve control, and the fluctuation range of the air temperature at the outlet of the evaporator can be reduced to make passengers uncomfortable. There is an effect that can be eliminated.

Further, since the present invention is not related to the time constant of the temperature sensing cylinder for controlling the expansion valve, it has an effect that it can be widely applied to the cooling device.

[Brief description of drawings]

1 to 3 show an embodiment embodying the present invention,
FIG. 1 is a flow chart showing a capacity control method of a variable capacity compressor, FIG. 2 is a schematic circuit diagram of a vehicle cooling device, and FIG. 3 shows a relationship between an outlet air temperature of an evaporator and a refrigerant gas discharge temperature. A graph, FIG. 4 is a flowchart showing another example of the present invention, FIG. 5 is a graph showing the correlation between the blown-out air temperature at the evaporator outlet and the sucker temperature and the discharge temperature, and FIG. 6 is a variable capacity compressor. FIG. 7 is a schematic circuit diagram of a conventional cooling device, showing a longitudinal cross-sectional view of a central portion showing an example. Variable capacity compressor 2, discharge chamber 3, suction chamber 4, pipe line 5, condenser 6, expansion valve 7, evaporator 8, temperature sensitive cylinder 10, solenoid valve 11 constituting variable capacity mechanism, arithmetic and control unit 17, Evaporator outlet blown air temperature sensor 19, voltage sensor 20, outside air temperature sensor 21,
Discharge temperature sensor 22, target temperature setting means 23, discharge temperature difference calculation means 24, capacity control constant changing means 25, evaporator blown air temperature Tf, blown air target temperature Tc, current discharge temperature Td1,
The discharge temperature Td2 before a predetermined time, the discharge temperature difference ΔTd, the capacity control constants C, C1, C2, C3, the first to fifth set temperature ranges T1 to T5, the initial set value a, and the variable constant r.

Claims (2)

[Claims] 1. A condenser, an expansion valve and an evaporator are sequentially connected to a discharge side port and a sucker side port of a variable capacity compressor, and the expansion valve is controlled in an outlet side line of the evaporator. An arithmetic and control unit is provided which is provided with a temperature sensitive cylinder and which calculates a volume control amount based on a detection signal from a sensor for detecting the temperature of air blown out of the evaporator and outputs a control signal to a volume variable mechanism of a variable displacement compressor. In the cooling device provided, when the temperature difference between the current suction temperature or discharge temperature of the refrigerant gas of the variable capacity compressor and the suction temperature or discharge temperature before a predetermined time is within the set temperature range, the When the capacity control constant is maintained at the initial setting value to calculate the capacity control amount, and when the temperature difference rises beyond the set temperature range, the capacity control constant is increased to calculate the capacity control amount, The temperature difference is A capacity control method for a variable capacity compressor in a cooling device, wherein a capacity control constant is reduced to calculate a capacity control amount when the temperature falls below the set temperature range. 2. The set temperature range includes a first set temperature range of −1.0 to + 1.0 ° C., a second set temperature range of 1 to 5 ° C., a third set temperature range of 5 ° C. or higher, and −1. A fourth set temperature range of ~ -5 ℃,
The variable capacity compressor in a cooling device according to claim 1, wherein the variable capacity compressor is set in a fifth set temperature range of −5 ° C. or lower, and the capacity control constant is stepwise increased or decreased according to each of the set temperature ranges. Capacity control method.