JPH0260818A - Car airconditioner control device - Google Patents

Abstract

PURPOSE:To measure heat load more directly to prevent supercooling by changing a present control target value in accordance with a calculated operation rate association value of a compressor and with a critical operation rate association value corresponding to the present control target value. CONSTITUTION:A clutch control amplifier 9 makes the clutch 8 of a compressor 1 ON when temperature, detected by a sensor 6, of air blown out from an evaporator 5 is higher than an upper limit valve of a fixed hysteresis width making a target air temperature from a control unit 10 as the center, and makes the clutch OFF when the temperature lower than a lower limit value. The control unit 10 is previously set up, for every control target value, with the critical value of operation rate association value (duty ratio on driving the compressor 1) drivable at a cooling degree of the control target value, and changes the control target value in relation to operation rate association value (heat load) measured actually. In this way, it is possible to measure heat load more directly and to intend to save power and to prevent supercooling without deteriorating comfortable air conditioning.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a car air conditioner 1t1j control device that saves power.

[Prior art]

Conventionally, in a car air conditioner (vehicle air conditioning system), the degree of cooling of the evaporator measured by the temperature of the air blown from the evaporator, the surface temperature of the fins of the evaporator, the refrigerant temperature or refrigerant pressure inside the evaporator, etc. is, on average, The compressor is controlled on and off so that it reaches a control target value for its degree of cooling, which is given as a set value of a manual setting device or a required value calculated from various thermal conditions. In order to prevent indoor overcooling, an economy control mode is provided, which increases the control target value for the degree of cooling of the evaporator depending on manual operation or the vehicle heat load predicted from the required temperature and outside air temperature. things are being done.

[Problem to be solved by the invention]

However, since the vehicle thermal load calculated from the detected values of each sensor as described above is only a predicted value, there is a prediction error with the actual thermal load. Therefore, in order to use the economy mode without sacrificing comfortable air conditioning, the predicted heat load had to be reduced to a value that takes into account this prediction error. Due to these circumstances, in the conventional economy mode,
The original purpose of power saving and prevention of supercooling could not be effectively achieved. The present invention was developed to solve the above problems, and its purpose is to achieve effective power saving without sacrificing comfortable air conditioning by measuring heat load more directly. The goal is to prevent overcooling and overcooling.

[Means to solve the problem]

The structure of the invention for solving the above problem is, in a car air conditioner control device that controls on/off of a compressor according to the degree of cooling of an evaporator and its control target value, an operating rate that calculates a value related to the operating rate of the compressor. a related value calculation means; a critical value storage means for storing, for each of the control target values, a critical operating rate related value that is a criterion for determining whether to change the control target value; The present invention further includes target value control means for changing the current control target value in accordance with the operating rate related value and the critical operating rate related value corresponding to the current control target value.

[Effect]

The compressor operating rate related value is, for example, a duty ratio related to driving the compressor. If the operating rate-related value increases by J(, it means that the heat load has increased, and conversely, 1. If the operating rate-related value decreases, it means that the heat load has become smaller. Therefore, it is possible to detect the heat load more directly by using the value related to the operating rate of the compressor.Also, it is possible to reduce the control target value of the cooling degree of the evaporator (for example, by reducing the Increasing the temperature) means reducing the cooling capacity, and conversely, increasing the control target value for the degree of cooling of the evaporator (for example, lowering the blowout temperature (!:) It means increasing the cooling capacity. Therefore, for each control target value, a critical value (critical operation rate related value) of the operating rate related value that can be driven with the cooling degree of the control target value is determined in advance, A more effective economy mode can be realized by changing the control target value in the relationship between the actually measured operating rate related value and its critical operating rate related value. In the case where multiple control target values are set and the economy mode is performed in multiple stages, the critical operating rate related values corresponding to each intermediate control target value are The lower limit critical operating rate related value, which is the criterion for shifting to the value, and conversely,
Furthermore, it is composed of an upper limit critical operating rate related value that serves as a criterion for shifting to a control target value with a higher degree of cooling (lower temperature).

【Example】

The present invention will be described below based on specific examples. In the car air conditioner control device shown in FIG. 4, the refrigerant compressed by the compressor 1 flows into the evaporator 5,
There, the air is evaporated, the evaporator 5 is cooled, and cooled air is obtained by exchanging heat with the fins of the evaporator 5. The refrigerant evaporated by the evaporator 5 passes through the expansion valve 4, is collected in the receiver 3, is condensed in the condenser 2, and heat is released to the surrounding air. Further, the compressor 1 is operatively connected to the engine 7 via a clutch mechanism 8. The clutch mechanism 8 is controlled on and off by a clutch control amplifier 9. Further, an air temperature sensor 6 is provided at the outlet of the evaporator 5 to detect the air temperature Te of the evaporator 5 as a means for detecting the degree of cooling of the evaporator 5, and its output is input to the clutch control amplifier 9. ing. The clutch control amplifier 9 has a function of outputting an on/off control signal to the clutch mechanism 8 according to the detected outlet air temperature Te and the target air temperature Ts. Specifically, it is configured with a differential amplifier and generates a control signal that is turned from off to on when the outlet air temperature Te becomes higher than the upper limit of a certain hysteresis width centered on the target air temperature Ts input from the control device 10. When the outlet air temperature Te falls below the lower limit of a certain hysteresis width centered on the target air temperature Ts input from the control device 10, a control signal is output that changes from on to off. The control device 10 is a device that performs air conditioning control according to the present invention, inputs the on/off signal from the clutch control amplifier 9, calculates the operating rate from the duty ratio, and determines the target air temperature from the operating rate if necessary. This is a device that changes Ts. The control device 10 includes a CPU II that executes arithmetic processing to realize the functions of the operation rate related value calculation means and the target value control means, a ROM 12 that stores a control program, and a ROM 12 that changes the target air temperature for each target air temperature. The RO is formed with a critical value storage means for storing a critical operating rate that serves as a criterion for determining whether
It is composed of an M13 and an input/output interface 14. Next, the operation of the control device 10 will be explained according to the flowchart of FIG. 3 showing the processing procedure of the CPU II. In step 100, an on/off signal is input from the clutch control amplifier 9, and its on period Ton and one cycle T of on/off are measured. Then, in step 102, the operating rate Xon is calculated from the ratio of the on period Ton to one cycle T. In this embodiment, the target air temperature Ts is the first target temperature T of 0 to 4°C, which is the target value in the normal cooling mode.
The second g:temperature T1 is composed of two target values: O and the second g:temperature T1 of about 10° C., which is the target value in the economy mode. Next, the process moves to step 104, and the operating rate Xo at that time is
It is determined whether n is smaller than the first critical operating rate XOI corresponding to the first target temperature TO. If the operating rate Xon is smaller than the first critical operating rate XOI corresponding to the first target temperature TO, this means that the operating rate has decreased in the basic control mode at the first target temperature TO. , which means that the cooling capacity has tended to be excessive, and the process moves to step 106, where the target air temperature Ts is set to the second target air temperature T1 of the economy mode, and that value is output to the clutch control amplifier 9. be done. As a result, the control mode becomes economy control in which the outlet air temperature Te becomes the second target air temperature T1. Next, the process moves to step 108, where the economy mode state is maintained for a certain period of time in order to prevent hunting, and then the process returns to step 100, where the above-described process is repeated. If it is determined in step 104 that the operating rate Xon at that time is not smaller than the first critical operating rate x01 corresponding to the first target temperature To, the process moves to step 110. Then, in step 110, the operating rate X at that time
on is the second critical operating rate XO2 corresponding to the second target temperature T]
It is determined whether the value is greater than or not. In addition, here, the second critical operating rate XO2 is the first critical operating rate X
It is set to a value greater than 01. If it is determined that the operating rate Xon at that time is not larger than the second critical operating rate XO2 corresponding to the second target temperature T1, it is determined that the cooling load has not increased to such an extent that it cannot be controlled in the economy mode, Continue economy mode and step 10
The value returns to 0 and the above process is repeated. Further, if it is determined in step 110 that the operating rate Xon at that time is larger than the second critical operating rate XO2 corresponding to the second target temperature Tl, the economy mode which is the 1liU control mode at the second target temperature T1 is selected. This means that the operating rate has increased, which means that the cooling capacity tends to be insufficient and the cooling load has increased to the extent that it cannot be controlled in the economy mode.In this case, step 112 Move to. Then, in step 112, the target air temperature Ts is set to '1rJ1 target air temperature TO in the basic mode, and that value is output to the clutch control amplifier 9. As a result, in the control mode, the outlet air temperature Te is the first target air temperature T. Return to basic mode. Next, the process moves to step 108, where the basic mode state is maintained for a certain period of time in order to prevent hunting, and then the process returns to step 100, where the above-described process is repeated. Next, the control principle will be further explained in detail. FIG. 1 shows the change in air temperature blown from the evaporator after the air conditioner is operated. Figure 1 shows the characteristics when the enthalpy of the evaporator inlet air is constant, and there are two types of control target values: the first target air temperature TO in the basic mode and the second target air temperature T1 in the economy mode. and
The on/off operation status in each case is shown. When the target value is low at the first target air temperature TO, the hysteresis width given around the first target air temperature TO allows the outlet air temperature Te of the evaporator 5 to always be set at the first target air temperature as an average value. On/off control is performed so that the temperature becomes TO. Incidentally, the on-time is determined by the state (capacity) of the refrigeration cycle, the amount of heat load determined by the enthalpy of the evaporator inlet air, and the amount of air passing through the evaporator. Further, the off time is determined by the evaporator cooling power remaining at the time of shutdown and the heat load. At this time, the first target air temperature TO is at a low temperature, so when considering the capacity limit of the refrigeration cycle, the operating state is close to the limit, so the on time is relatively long. On the other hand, since the temperature difference between the evaporator inlet air temperature (which can be regarded as room temperature in the inside air mode) and the first target air temperature TO is large, the off time is relatively short. On the other hand, when the target value is high, the on-time tends to be relatively short and the off-time tends to be relatively long. Therefore, if the evaporator inlet air enthalpy is kept constant and the target value is changed from the first target air temperature TO to the second target air temperature T1, the operating rate of the compressor 1
n has a decreasing characteristic. By the way, if we look at the actual changes in car room temperature, etc.
Immediately after the target value is changed from the first target air temperature TO to the second target air temperature T1, it will be as shown in Figure 1, but as time passes, the temperature and humidity inside the vehicle will rise and the evaporator inlet air load will increase. In such a case, the second target air temperature TI
The utilization rate of will increase, and after enough time,
The operating rate becomes stable at a higher operating rate than the operating rate shown in FIG. Furthermore, when the evaporator inlet air enthalpy changes, the on-period and off-period change linearly, and the operating rate also changes linearly. The air conditioner heat load mentioned above in steady state is balanced with the vehicle heat load QL, and when the vehicle heat load QL is large, the air conditioner operation rate increases, and when the vehicle heat load OL is small, the operation rate decreases, and the required cooling depends on the operation rate. ability can be assessed. Further, the cooling capacity Q4 of the air conditioner is expressed by the following formula. Q, -rVa It -12) However, r: Inlet air specific weight Wrinkle: Air volume Il: Evaporator inlet air enthalpy 12: Evaporator outlet air enthalpy And, the cooling capacity Q2 is balanced with the vehicle heat load QL in a steady state. Changing the target value from the first target air temperature TO to the second target air temperature T1 means increasing the evaporator outlet air enthalpy 12 and decreasing the cooling capacity Q. As described above, by predicting the heat load based on the operating rate and changing the target air temperature, it is possible to change the cooling capacity and set the system to economy mode. Here, the purpose of the economy mode is to lower the cooling capacity Q by increasing the evaporator outlet temperature, to avoid unnecessary cooling, and to lower the average power of the compressor 1. In the above embodiment, two-stage control of the basic mode and economy mode is shown, but a multi-stage control mode can also be configured as follows. In a similar way, in addition to the first target air temperature TO7, the second target air temperature T1, the third target air temperature T2. Fourth target air temperature T3
- It can be made into multiple stages. This will be explained in FIG. Now, when the cooling capacity and heat load are balanced at point A, the critical operating rate near point A is the lower critical value χ01 and the upper critical value XO2.
, compare the actual operating rate Xon with the lower critical value XOI and the upper critical value XO2, and when Xon < XOI, change the target air temperature to the second target air temperature T1, and when Xon > XO2, change the target air temperature. The first target air temperature TO
Add an operation to change it to . In FIG. 2, since Xon<XOI, the target air temperature is changed from the first target air temperature To to the second target air temperature TI,
Move from point A to point B. In other words, when the operating rate at the first target air temperature TO is smaller than the predetermined value, the target air temperature is T
By increasing from O to T1, the operating rate is further lowered and power-saving operation is performed. Next, further at the second target air temperature TI, X on<
When Xon>X12, the target air temperature is changed to the third target air temperature T2, and when Xon>X12, the target air temperature is changed to the first target air temperature TO.
Add a masterpiece of changing to . In Figure 2, since X on < X 11 at point B, the target air temperature is changed from the second target air temperature T1 to the third target air temperature T2.
, and move from point B to point C. Similarly, when Xon<X21, the target air temperature is set to the fourth target air temperature T3.
When Xon>X22, set the target air temperature to the second target air temperature TI.
Add an operation to change it to . In Figure 2, Xo at point C
Since n>X22, the target air temperature is changed from T2 to T1, and the process returns from point C to point B again. In Figure 2 below, points B and C
controlled by repeatedly transitioning between points. When transitioning from point A to point B, and then from point B to point C, the vehicle room temperature must be in equilibrium to some extent, and if there is a sudden transition to the set value, the temperature will change from A to B → C → (D) → → (D). →C-B-A
It becomes a big hunting like →B→C. In order to prevent hunting, for example, a timer or the like is required to hold the value for a certain period of time after the setting is changed. In addition, in FIG. 2, compared to point A, at points B and C, the cooling capacity is reduced and balanced with the vehicle heat load. When the influence of humidity is ignored, the vehicle heat load QL is approximated as follows: QL=Kl (T, , -T, ) Since the amount of solar radiation can be expressed as a constant, K, , K, is a constant, the car room temperature at point B rises from point A, and at point C it rises further, so as shown in Figure 2, the enthalpy of the air at the evaporator inlet becomes It deviates above the fixed line. In the above embodiment, the operating rate related value was calculated using the duty ratio, but as other operating rate related values, the target air temperature TO→T1
→ In the case of transition to T 2-, select the on-time Ton of the compressor, change the magnitude of that Ton, and also select T2→
In the case of transition from T1 to TO, the compressor of time T
It is also possible to select off and compare the magnitude of Toff with a predetermined value. Although the present invention is intended for a manual air conditioner, the air mix damper opening is set to a predetermined opening on the 110T side or Ma
If it is activated in the xtlOT state, it can also be combined with an automatic air conditioner.

【Effect of the invention】

The present invention provides an operation rate-related value calculation means, a critical value storage means, an operation rate-related value calculated by the operation rate-related value calculation means, and a critical drive rate-related value corresponding to a current control target value. Since it has a target value control means for changing the current control target value, the critical value (critical operation rate related value) of the operating rate related value that can be driven by the cooling degree of the control target value for each control target value is provided. By changing the control target value in relation to the actually measured operating rate-related values, the heat load can be controlled more directly, making it more effective without sacrificing comfortable air conditioning. It is possible to achieve significant power savings and prevention of overcooling.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the operation of a control device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining the operation of a control device according to another embodiment. Figure 3 shows C of the embodiment device.
The flowchart which showed the processing procedure of PU. FIG. 4 is a block diagram showing the configuration of the embodiment device. I Compressor 2 Capacitor 5 Evaporator 6'' Air temperature sensor 10 - Control device Patent applicant Nippondenso Co., Ltd. Representative Patent attorney Shul11 Fujitani @ Figure 1 Figure 2 Target air temperature diagram

Claims (1)

[Claims] Depending on the degree of cooling of the evaporator and its control target value,
In a car air conditioner control device that controls on/off of a compressor, an operating rate related value calculating means for calculating a value related to the operating rate of the compressor, and a criterion for determining a change in the control target value for each of the control target values. a critical value storage means for storing a critical operation rate related value, according to the operation rate related value calculated by the operation rate related value calculation means and a critical operation rate related value corresponding to the current control target value, A car air conditioner control device comprising: target value control means for changing a current control target value.