JPH03159815A - Air conditioner for vehicle - Google Patents

Abstract

PURPOSE:To further improve air-conditioning performance by increasing/ decreasing the discharge capacity of a variable capacity compressor according to the deviation between the detected value and set value of the physical quantity correlated with the temperature of an evaporator, and correcting the deviation according to the engine cooling water temperature. CONSTITUTION:The discharge capacity of a variable capacity compressor for force-feeding a cooling medium is changed by a means 102 on the basis of a capacity command signal. On the other hand, the physical quantity correlated with the temperature of an evaporator is detected by a means 103. The engine cooling water temperature is also detected by a means 104, and deviation between the physical quantity and the set value is computed by a means 105. The capacity command signal is then outputted by a means 106 in such a way as to increase the discharge capacity according to the deviation at the time of the physical quantity being more than the set value, whereas to reduce the discharge capacity according to the deviation at the time of the physical quantity being less than the set value. At this time, when the detected water temperature is over the specified value, for instance, the capacity command signal is formed on the basis of the reduced deviation value.

Description

[Detailed Description of the Invention] A. INDUSTRIAL APPLICATION FIELD The present invention relates to a vehicle air conditioner equipped with a variable displacement compressor.

B. 2. Description of the Related Art In this type of vehicle air conditioner, there is a correlation that when the temperature of the air passing through the evaporator decreases, the suction pressure Ps of the compressor decreases. Therefore, the target value of the air temperature on the evaporator discharge side (hereinafter referred to as suction temperature) was determined from the target value of the air temperature blown into the vehicle interior (hereinafter referred to as blowout temperature).
The suction pressure Ps is controlled so that the compressor suction pressure Ps becomes a set pressure Pr determined in accordance with the target suction temperature. In other words, when the suction pressure Ps falls below the set pressure Pr, the discharge capacity of the compressor is reduced to reduce the cooling capacity, and when the suction pressure Ps exceeds the set pressure Pr, the discharge capacity of the compressor is increased to increase the cooling capacity. The suction temperature is controlled to a target value (for example, Japanese Patent Laid-Open No. 1-254418).

C. Problems to be Solved by the Invention Incidentally, in this type of conventional vehicle air conditioner, the discharge capacity of the variable capacity compressor is set to a minimum value in order to reduce the engine load when the engine cooling water temperature exceeds a predetermined value ( (See dashed line A in Figure 10). In this case, compared to a fixed capacity compressor where the compressor is completely turned off by disengaging the electromagnetic clutch (see dashed line C in FIG. 10), the cooling capacity is somewhat improved.

However, if the discharge volume is controlled more precisely, the cooling capacity can be further improved.

A technical object of the present invention is to reduce the engine load while maintaining the cooling capacity to a certain extent without reducing the discharge capacity of the variable capacity compressor to the minimum value even when the engine cooling water temperature exceeds a predetermined value.

D. Means for Solving the Problems Explained with reference to FIG. 1, which is a diagram corresponding to claims, the present invention comprises a variable capacity compressor 101 that pumps refrigerant, and a capacity that adjusts the discharge capacity of the variable capacity compressor 101 based on a capacity command signal. a changing means 102; a detecting means 103 for detecting a physical quantity correlated with the temperature of the evaporator;
Water temperature detection means 104 detects the temperature of engine cooling water; deviation calculation means 105 calculates the deviation between the physical quantity detected by the detection means 103 and a preset setting value; A command signal output means 106 is provided for forming a capacity command signal so that the discharge capacity of the compressor ↓01 increases in accordance with the deviation, and when the physical quantity becomes less than a set value, the discharge capacity decreases in accordance with the deviation. The command signal output means 106 forms a capacity command signal based on the calculated deviation when the detected water temperature is below a predetermined value, and forms a capacity command signal based on a value with a smaller deviation when the detected water temperature exceeds the predetermined value. 3 to form the capacity command signal.

E. When the detected water temperature exceeds a predetermined value, the discharge capacity is adjusted based on the corrected deviation. Capacity change means 02
If the detected physical quantity is larger than the set value, the discharge capacity is increased in accordance with the magnitude, so if the discharge capacity is controlled using a value corrected to reduce the deviation, the discharge capacity is controlled to be small.

As a result, the load of the variable capacity compressor on the engine can be reduced while maintaining the cooling capacity to some extent, and a rise in cooling water temperature can be suppressed.

F. Example An embodiment of the present invention will be described with reference to FIGS. 2 to 7.

(1) Structure of the embodiment <1-1: Overall structure> The vehicle air conditioner according to the present invention has the following features as shown in FIG.
Variable displacement compressor 2 driven by engine 1
, capacitor 3, evaporator 4, noquid tank 5,
A cooler unit I-100 of a certain compression refrigeration cycle is provided from the expansion valve 6.

The variable displacement compressor 2 is of a so-called swash plate type, and the suction pressure Ps or the discharge pressure Pd is guided through a control valve 2a into a casing in which the swash plate is disposed.
This changes the inclination angle of the swash plate to change the discharge capacity, as disclosed in, for example, Japanese Patent Laid-Open No. 158382/1982. When the suction pressure Ps exceeds the set pressure Pr, the inclination angle is increased to increase the discharge capacity, and when the suction pressure Ps becomes lower than the set pressure Pr, the inclination angle is decreased to decrease the discharge capacity. The set pressure Pr is determined by the solenoid current I SQ supplied from the control circuit 40 shown in FIG.
The set pressure Pr is controlled by the solenoid current I
It increases in proportion to 80L.

Therefore, when the solenoid current ISQL is increased, the discharge capacity of the variable capacity compressor 2 is decreased, and the cooling capacity is decreased.

Further, the evaporator 4 is disposed within an air conditioning duct 7 having an outside air inlet 7a and an inside air inlet 7b. An inside/outside air switching door 8 that controls the flow rate of air introduced into the air conditioning duct 7 is provided at each of the introduction ports 7a, 7b. Furthermore, a well-known rib blower fan 9, a heater unit 10, and an air mix door 11 are provided in the air conditioning duct 5, as well as a vent outlet 7c provided in the air conditioning duct 7.
A vent door 12 and a foot door 13 are provided to respectively adjust the amount of air emitted from the foot air outlet 7d. Further, a defroster door l4 is provided at a defroster outlet 7e provided in the air conditioning duct 7.

<I-2: Control Circuit 40> FIG. 3 shows an example of the control circuit 40 of the vehicle air conditioner according to the present invention. The CPU 41 is connected via an input circuit 42 to an outside temperature sensor 43 that detects the outside temperature TAI4B, an indoor temperature sensor 44 that detects the vehicle interior temperature TING, and an amount of solar radiation Q.
A solar radiation sensor 45 that detects SUN, a suction temperature sensor 46 that detects the air temperature (hereinafter referred to as suction temperature) TINT downstream of the evaporator 4, and a water temperature sensor 47 that detects the engine cooling water temperature Tw are connected to each other, and these sensors 43 to 47 are connected to each other. 47, various temperature information and heat amount information are sent to CPU41
is input. The input circuit 42 also includes an air conditioner switch 48, a pro fan switch 49, and an air mix door opening sensor 5 that detects the opening of the air mix door 11.
0 is also connected.

Furthermore, the CPU 41 is connected to various door actuator groups 5 such as an intake actuator via an output circuit 51.
2 and a proa fan control circuit 53 are connected to the proa fan control circuit 53, and a proa fan motor 9 is connected to the proa fan control circuit 53. The output circuit 51 is further connected via a relay 52 to a solenoid portion of an electromagnetic actuator 2a-1 attached to the control valve 2a.

The CPU 41 controls each sensor 43 to 47 and each switch 48 .
Based on various information inputted from the controller 49, the door actuator group 52 is driven and controlled to appropriately control the air inlet, outlet, and outlet temperatures or the set pressure Pr of the control valve 2a.

(II) Operation of the embodiment =7 Next, the operation of the embodiment will be explained.

<II-1: Basic flowchart> Figure 4 is CP'
It is a flowchart which shows the basic control of an air conditioning control apparatus performed by U41.

In step SIO, initial settings are made, and in normal automatic air conditioner mode, for example, the set temperature T
Initial setting is 5℃. In step S20, various information from each sensor is input.

To specifically explain the data information of each of these sensors,
The set temperature TPTC is determined from a control panel (not shown), the vehicle interior temperature TING is determined from the interior temperature sensor 44, the outside temperature TAMB is determined from the outside temperature sensor 43, and the amount of solar radiation Qs is determined.
uN is obtained from the solar radiation sensor 45, suction temperature T INT is obtained from the suction temperature sensor 46, and engine water temperature Tw is obtained from the water temperature sensor 4.
Each is given from 7.

Next, in step S30, the outside air temperature TAMB obtained from the outside air temperature sensor 43 is processed to a value TAM corresponding to the actual outside air temperature by removing the influence from other heat sources. Next, in step S40, the solar radiation amount information as the amount of light from the solar radiation sensor 81 is processed into a value Q' 80H as the amount of heat suitable for subsequent conversion.

In step 850, a value T''p is obtained by correcting the set temperature TPC set on the control panel according to the outside temperature.
'Process to rc. In step S60, T'PTCI
TINCI TAM* Q'8UN to target blowout temperature T
o, and also calculates the opening degree of the air mix door 11 according to the deviation between the target blowout temperature TO and the actual blowout temperature. In step S70, the compressor 2 is controlled as described below.

In step S80, each outlet is controlled. Step S9
0 controls selection switching of the suction ports, that is, the outside air introduction port 7a and the inside air introduction port 7b. In step S100, the flow rate from the air outlet is controlled by controlling the proa fan 9.

<II-2: Compressor control> FIG. 5 shows the compressor control (step S70) in FIG.
) is a flowchart explaining in detail.

In FIG. 5, in step S701, it is determined whether the profan 9 is operating (turned on) or not based on the signal from the profan switch 49, and if it is not operating, the compressor 2 is stopped (turned off) in step S702. do.

If it is in operation, in step S703, the target blowing temperature To obtained in step S60 is read.

This date mark air temperature To is determined, for example, by the following equation.

To= (A+D)T'PTC+BTAM+CQ'SU
N-DTING 10E Here, A-E is a constant. Next, the process proceeds to step S704, and the target suction temperature T is determined based on the target blowout temperature To from the table shown in FIG. 6, for example.
Find INT'. Thereafter, in step S705, the engine coolant temperature TV is read and it is determined whether or not it exceeds a predetermined value. If it exceeds the predetermined value, the process proceeds to step 8706, subtracts the constant α from the read suction temperature TINT, and sets the result as the new suction temperature TINT. That is, the suction temperature T INT used in a later procedure is corrected to a lower value. If the engine cooling water temperature Tw is less than or equal to the predetermined value, the process directly advances to step S707 without performing the subtraction in step S706.

In step S707, it is determined whether the suction temperature TINT is lower than the temperature at which the evaporator starts freezing, for example, 3°C. If it is lower than 3°C, the solenoid current ISQL is set to the maximum value in step 8708.

As a result, the set pressure Pr of the control valve 2a is set to the maximum value, the discharge capacity of the variable capacity compressor 2 is controlled to the minimum value, and freezing of the evaporator 4 is suppressed. If the suction temperature TINT is 3°C or higher, step S709
Then, the suction temperature TINT becomes the target suction temperature TINT'
The discharge capacity of the compressor 2 is controlled so that

<■-3 Discharge capacity control flowchart> Fig. 7 is a detailed flowchart of the discharge capacity control in step S709, and the discharge capacity is controlled by calculating the solenoid current Isob, which is the capacity command signal, as follows. .

First, the difference (T INT - T' INT) between the suction temperature TINT and the target suction temperature T'rNT is calculated (step S7091), and from this difference, the proportional term current IP and the integral term current IT are calculated as -I+ in Figs. 8 and 8, respectively. Step S709 according to FIG.
Find it in 2. Here, the proportional term current IP is determined in step S70.
The integral term current II is obtained from FIG. 9 based on the difference calculated in step 91, and the integral term current II is obtained from FIG.
is calculated, and the value Ir (
=I1+ΔIr). and step S
At step 7093, a current corresponding to the difference between the proportional term current rp and the integral term current II is determined as the solenoid current I80L. In other words, solenoid energization/current I SQL
Is ■ so = IP- ■ !・ ・
・It is obtained by (1).

However, IP is ampere, ■summer is milliampere.

Therefore, as can be seen from FIGS. 8 and 9 and equation 1, during discharge capacity control, ISQL indicates that the suction temperature T INT of the evaporator 4 is equal to the target suction temperature T IN
It is increased or decreased so that it becomes T'. Solenoid current IS
When QL becomes smaller, the pressure Pr set in the control valve 2a becomes lower, and even if the compressor suction pressure Ps is a small value, the suction pressure Ps is introduced into the casing chamber of the compressor 2, and the inclination angle becomes large, that is, the compressor The discharge capacity is increased (cooling capacity is increased). Conversely, when the solenoid current ISQL increases, the pressure Pr set in the control valve 2a increases, and even if the compressor suction pressure Ps becomes relatively large, the suction pressure Ps remains in the two casing chambers of the compressor.
is not guided, an increase in the inclination angle, that is, an increase in the compressor discharge capacity is suppressed, and the cooling capacity is controlled to be relatively small.

In this way, when the engine coolant temperature is above a predetermined value,
If the suction temperature T INT used for discharge capacity control is reduced by a predetermined temperature α, the discharge capacity will be controlled to be smaller than when the same scale discharge temperature To is required, the compressor absorption horsepower will be reduced, and the load on the engine will be reduced. decreases, working to lower the engine cooling water temperature. Therefore, the cooling capacity for the engine cooling water temperature rv is:
As shown in FIG. 10, when the engine cooling water temperature T, exceeds a predetermined value, the discharge capacity is set to the minimum value.In the conventional method, the discharge capacity drops suddenly as shown by the broken line A, but by controlling as described above, the solid line B As shown in FIG. 2, the cooling capacity gradually decreases as the engine cooling temperature TV becomes higher than the predetermined value. Therefore, the load on the engine can be reduced while maintaining cooling capacity to some extent.

In the structure of the above embodiment, the control valve 2a
is the capacity changing means 102, the suction temperature sensor 46 is the physical quantity detecting means 103, and the water temperature sensor 47 is the water temperature detecting means 10.
4, the control circuit 40 controls the deviation calculating means 105 and the signal forming means 106, respectively.

Although the discharge capacity of the variable capacity compressor 2 was adjusted according to the deviation between the suction temperature downstream of the evaporator and its target value, the control method may take various forms. Further, the capacity changing mechanism is not limited to the method of the embodiment.

G. Effects of the Invention Since the present invention is constructed as described above, when the engine cooling water temperature reaches a predetermined value or higher, a predetermined cooling capacity can be maintained while reducing the load on the compressor, and air conditioning performance is improved.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram. Figures 2 to 9 illustrate one embodiment of the present invention.
Figure 2 is the overall configuration of the air conditioner, Figure 3 is a block diagram of the control system, Figure 4 is the main flowchart, Figure 5 is the flowchart for compressor control, and Figure 6 is the target outlet temperature To and target suction temperature. A diagram showing a table of temperature TINT',
FIG. 7 is a flowchart for controlling the discharge volume, and FIGS. 8 and 9 are graphs used for calculating the solenoid current I80L. FIG. 10 is a graph showing cooling capacity versus engine cooling water temperature. 1: Engine 2: Variable displacement compressor 2a: Control valve 4: Evaporator 40:
Control circuit 46: Suction temperature sensor 47: Water temperature sensor 101 Variable capacity compressor l5 102: Capacity changing means 104: Water temperature detecting means 106 Two command signal form means 103: Physical quantity detecting means 105: Deviation calculating means

Claims (1)

[Scope of Claims] 1) A variable capacity compressor that pumps refrigerant, capacity changing means that adjusts the discharge capacity of the variable capacity compressor based on a capacity command signal, and detection means that detects a physical quantity correlated to the temperature of the evaporator. , water temperature detection means for detecting the temperature of engine cooling water; deviation calculation means for calculating the deviation between the physical quantity detected by the detection means and a preset set value; and when the physical quantity exceeds the set value, the variable command signal output means for forming the capacity command signal so that the discharge capacity of the capacity compressor increases in accordance with the deviation, and when the physical quantity becomes less than a set value, the discharge capacity decreases in accordance with the deviation; The command signal output means generates a capacity command signal based on the calculated deviation when the detected water temperature is below a predetermined value, and generates a capacity command signal based on the calculated deviation when the detected water temperature exceeds the predetermined value. A vehicle air conditioner, characterized in that the capacity command signal is formed based on the capacity command signal.