JPS62153518A - Intake air cooling device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the operation rate of a refrigerant compressor, by arranging a water cooled intercooler and another intercooler utilizing a compartment cooling refrigerant in series to each other, and using the water cooled intercooler when an engine load is greater than a predetermined value, while when an intake air temperature rises, operating the intercooler utilizing the refrigerant as changing the capacity of the refrigerant compressor according to the intake air temperature. CONSTITUTION:A first water cooled intercooler 42 is arranged downstream of a supercharger 20, in which intercooler is circulated a cooling water of an engine cooling system. A second intercooler 44 is arranged downstream of the first intercooler 42 in series thereto, which intercooler 44 uses a part of a refrigerant of a compartment cooling device 54 having a variable displacement compressor 56. The first intercooler 42 is operated when an engine load is greater than a predetermined value, while the second intercooler 44 is operated when an outlet temperature 86 of the first intercooler 42 is greater than a predetermined value. When the outlet temperature is less than the predetermined value, the capacity of the variable displacement compressor is decreased, while when the outlet temperature is greater than the predetermined value, the capacity is increased, thus preventing undue driving of the compressor.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an intake air cooling device for a supercharged internal combustion engine.

[Prior art and problems]

It is well known that a supercharger such as an exhaust turbo supercharger or an engine-driven supercharger is provided in the intake system of an internal combustion engine to supercharge the engine and increase its output.

When an engine is supercharged, the cylinder compression pressure increases and the intake air temperature rises, making non-king more likely to occur. Therefore, it is common practice to cool intake air using a water-cooled or air-cooled intercooler. However, this type of intercooler does not have sufficient cooling capacity, especially in high-speed, high-load operating ranges where the amount of intake air is large. It is necessary to prevent the occurrence of knocking by this method, which sacrifices engine output and fuel efficiency.

It is also known to cool intake air using refrigerant in an automobile's cabin cooling system (near conditioner) (Japanese Patent Publication No. 60-35530 and Utility Model Publication No. 59-914).
No. 21). The refrigerant is compressed by a compressor, and this compressor is driven by an engine crank pulley or the like via an electromagnetic clutch. This intake air cooling system requires a large-capacity compressor in order to simultaneously cool the passenger compartment and the intake air, which poses a problem in that the fuel consumption rate of the engine increases.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an intake air cooling device for a supercharged internal combustion engine that has sufficient intake air cooling capacity and can be operated at a minimum fuel consumption rate. be.

[Summary of Means and Effects for Solving Problems] The intake air cooling device of the present invention includes a water-cooled first intercooler and a second intercooler cooled by a refrigerant. These two intercoolers are arranged in series with each other downstream of the supercharger, so that the intake air cooled by the first intercooler is further cooled by the second intercooler. Coolant cooled by the radiator is circulated through the first intercooler. Refrigerant is circulated through the second intercooler from the refrigeration circuit of the vehicle room cooling device via a branch circuit. A variable capacity type refrigerant compressor is used in the refrigeration circuit of an air conditioner.

The first water-cooled intercooler is activated when the engine load exceeds a set value. The second intercooler cooled by the refrigerant is activated when the temperature of the intake air cooled by the first intercooler is, for example, 30° C. or higher. In this case, when the intake air temperature reaches, for example, 50° C. or higher, the variable displacement compressor is operated at maximum capacity, and the intake air is cooled to the maximum extent. If the intake air temperature is, for example, 3
If the temperature is above 0°C and below 50°C, the compressor is operated at 50% capacity, for example. Therefore, the compressor drive load is reduced by reducing the compressor capacity, and fuel efficiency is improved.

〔Example〕

FIG. 1 shows an embodiment of the intake air cooling device of the present invention.

A combustion chamber 12 of the engine 10 communicates with an intake passage 14 . The intake passage 14 includes a conventional air flow make 16, a throttle valve 18, and a loop follower type supercharger 2.
0 is provided, and the intake air passes through the intake valve 22 and enters the combustion chamber 1.
Sent to 2. The air flow meter 16 measures the amount of intake air and outputs an analog signal to the control circuit 24. A potentiometer-type throttle opening sensor 26 is linked to the throttle valve 18 , and its analog output is input to the control circuit 24 .

The supercharger 20 is driven by a crank pulley 28 of the engine 10 via a belt 30 and an electromagnetic clutch 32. Bypass 34 of supercharger 20 is controlled in a known manner by a bypass control valve 36.

Distributor 3 to detect engine speed
8 is provided with a conventional crank angle sensor 40,
The output pulses are sent to control circuit 24.

Next, to explain the intake air cooling system, a first intercooler 42 is provided in the intake passage 14 on the downstream side of the supercharger 20, and is designed to cool the intake air pressure-fed from the supercharger. There is. Further, a second intercooler 44 is provided downstream of the first intercooler 42 so that the intake air cooled by the first intercooler 42 can be further cooled.

The first intercooler 42 is a water-cooled intercooler, and a coolant circulation means 46 circulates the coolant therein. This coolant circulation means 46 consists of a closed loop pipe 48, an electric water pump 50, and a radiator 52.
The coolant cooled by the radiator 52 is circulated to the first intercooler 42 by the water pump 50. The water pump 50 is controlled by a control circuit 24 as described below.

The second intercooler 44 is composed of an evaporator cooled by the refrigerant in the refrigeration circuit 54 of the vehicle room cooling system (near conditioner). The refrigeration circuit 54 of this vehicle room cooling system is
A refrigerant compressor 56, a closed loop pipe 58,
It is composed of a capacitor 60, an accumulator 62, a first electromagnetic cutoff valve 64, an expansion valve 66, an evaporator 68 for cooling the vehicle compartment, and a pressure regulating valve 70. The compressor 56 is driven by the engine crank pulley 28 via a heald 72 and an electromagnetic clutch 74.

The first electromagnetic valve, electromagnetic club, and chia 4 are controlled on and off by a control circuit as described later. Refrigerant compressor 56
is a variable capacity type, and when the solenoid 76 is excited, the capacity can be reduced to 50%. As this type of variable capacity compressor, the one described in "Toyota Crown New Model Car Manual" (published by Toyota Motor Service Department on August 31, 1980, pp. 6-56 et seq.) can be used. To operate the cabin cooling system, press the air conditioner switch 7.
8 allows the passenger to make a selection, and its output signal is input to the control circuit 24.

In order to circulate the refrigerant in the refrigeration circuit 54 to the second intercooler 44, a branch circuit 80 is connected to the pipe 58, and a second electromagnetic shutoff valve 82, an expansion valve 84, and a second intercooler are connected to the pipe 58. 44 is the piping. When the second electromagnetic valve 82 is opened when the compressor type (n clutch 74 is connected and the compressor 56 is operated), the refrigerant circulates through the second intercooler 44 and cools the intake air.

In order to measure the temperature of the intake air cooled by the first intercooler 42, the first intercooler 4 is connected to the intake passage 14.
An intake temperature sensor 86 is provided between the second intercooler 2 and the second intercooler 44, and its output is controlled. The signal is sent to the ff1 circuit 24. Furthermore, in order to detect the cooling load of the refrigeration circuit 54, a refrigerant temperature sensor 88 is provided in the piping 58 between the pressure regulating valve 70 and the compressor 56, and by measuring the temperature of the refrigerant downstream of the pressure regulating valve 70. It is designed to detect the cooling load.

This intake air cooling system is controlled by a control circuit 24 based on engine load and intake air temperature.

Next, a configuration example of the control circuit 24 will be explained with reference to FIG. Is the control circuit 24 engine-controlled? Consists of a microcomputer for Ill, central processing unit (CPU) 90, read only memory (ROM) 92, random access memory (RAM) 94, A/D converter with multiplexer 96, human interface circuit 98, output interface circuit 1OO1. Lotus 10 connecting
It consists of 2, etc. Analog signals from the throttle sensor 26, air flow meter 16, intake temperature sensor 86, and refrigerant temperature sensor 88 are each converted into binary signals by an A/D converter 96, stored in RAM 94, and used for calculations described later. . Crank angle sensor 4
For example, the CPU 90 outputs a pulse to the input interface 98 every 30 degrees of crank angle, and each time the CPU 90 receives this pulse, it calculates the time of the preceding and following pulses to calculate the engine rotation speed. The on/off signal from the air conditioner switch 78 is sent to the input interface 98 and the CPU 90
reads this information as needed. The water pump 50 of the first intercooler cooling pipe 48 , the first solenoid valve 64 of the refrigerant circuit 58 for cooling the passenger compartment, the second solenoid valve 82 of the branch circuit 80 for cooling the intake air, the compressor river electromagnetic clutch 74 , and the The solenoid 76 for reducing the
Controlled by an off signal.

Next, the control routine program for the intake air cooling system will be explained with reference to the flowcharts of FIGS. 3 and 4.

The flowchart in FIG. 3 shows a control routine for the coolant circulation means 46. In step 201, this control routine is started every 10 milliseconds, for example, as an interrupt routine of the main routine. In step 202, it is determined whether the engine load is greater than the set load. To do this, calculate the intake air amount Q/N per engine revolution based on the intake air amount Q measured by the air flow meter 16 and the engine rotation speed Ne calculated from the signal from the crank angle sensor 40. It can be compared with the set value A. In this case, the set value A can be set to 0.6 (12/rev), for example. Alternatively, the load may be determined based on the throttle opening detected by the throttle opening sensor 26.

If the load is greater than or equal to the set value, proceed to step 203;
Activate the water pump 50. As a result, the coolant is circulated through the radiator 52 to the first intercooler 42, and the intake air is cooled by the first intercooler 42. In addition, when operating the water pump 50 in step 203, a flag using the memory area of the RAM 94 is set to "1" to record that the water pump 50 is in the "ON" state. This information is used in the determination at step 204.

If the load is smaller than the set value in the determination at step 202, the process proceeds to step 204, where it is determined whether or not the water pump 50 was turned on in the previous execution of the routine.This determination is made using the flag described above. If it is "ON", the process proceeds to step 205, where it is determined whether or not the engine is in an idling operating state.This determination can be made based on the throttle opening detected by the throttle opening sensor 26. If the throttle valve 18 is fully closed, it is determined that the engine is in an idle state.If it is in an idle state, the process proceeds to step 206, where the water pump 50 is stopped and the flag is set to "0".
The circulation of the coolant to the intercooler 42 is stopped, and the first intercooler 420 function is stopped. If it is not in the idle state, proceed to the steering knob 203 and continue operating the water pump 50. In this way, even if the load falls below the set value, the water pump 50 will not be stopped immediately, and the water pump 50 will not be stopped immediately unless the idle state passes.
0 operation continues. The water pump 50 is stopped in step 206 only after the load has fallen below the set value and the engine is in an idle state. This is because the water pump 50
This is to prevent the switch from being turned on and off repeatedly.
This is to provide hysteresis to water pump control. If the water pump 50 is "OFF" in step 204, the process proceeds to step 206, where the water pump is stopped. As can be seen from the above,
In the intake air cooling system of the present invention, the water-cooled first intercooler 42 is operated when the engine load is equal to or higher than a set value.

Upon completion of the above routine, the process advances to step 207 in the flowchart of FIG. In step 207, it is determined whether the air conditioner switch 78 is in the "ON" state.
ON'', the compressor electromagnetic clutch 74 is connected in step 208.

As a result, the compressor 74 compresses the refrigerant and circulates it to the refrigeration circuit 54, a refrigeration cycle is started, and the refrigerant becomes ready to be circulated to the evaporator 68 for cooling the passenger compartment and/or the second intercooler 44 for cooling the intake air.

Next, the process proceeds to step 208, where it is determined whether the refrigerant temperature t detected by the refrigerant temperature sensor 88 is smaller than a set value (for example, 5° C.). This determination is made to reduce the capacity of the compressor 56 in accordance with the reduction in the cooling load, thereby reducing the driving load and improving fuel efficiency. Therefore, when the cooling load is small (5° C.), the compressor solenoid 76 is turned on in step 210 to reduce the compressor capacity to 50%, and when the cooling load is large, the solenoid 76 is turned on in step 211. 100 in Kanobi
% capacity.

Next, the process proceeds to step 212, where the temperature T of the intake air cooled by the water-cooled first intercooler 42 is measured by the intake air temperature sensor 86, and whether the intake air temperature T is smaller than the first set value A (for example, 30° C.) or not. Determine whether or not.

If T<30°C, it is considered that intake air cooling by only the first intercooler 42 is sufficient, and the second solenoid valve 82 is closed in step 213, the first solenoid valve 64 is opened in step 214, and the first solenoid valve 64 is opened in step 215. to return to the main routine. As a result, the refrigerant circulation to the second intercooler 44 is stopped, and the intake air cooling by the second intercooler 44 is stopped. However, the refrigerant is circulated to the vehicle interior cooling evaporator 68, so that the vehicle interior is cooled.

In the determination of the state 212, if the intake temperature T is, for example, 30
If the temperature is higher than .degree. C., it is determined in step 216 whether the intake temperature T is lower than a second set value B (for example, 50.degree. C.). This is because the compressor is always operated at 100% capacity when the temperature of the intake air pre-cooled by the first intercooler 42 is high. Therefore, T>50
℃, the solenoid 76 is turned off in step 217 to maintain the capacity at 100%, and the steering knob 2 is turned off.
Proceed to step 18.

If 30℃≦T≦50℃, continue to step 218
Proceed to. In step 218, the second solenoid valve 82 is opened to circulate the refrigerant to the second intercooler 44. Therefore, the intake air cooled by the first intercooler 42 is further cooled by the second intercooler 44, but when the intake air temperature measured by the intake air temperature sensor 86 is high, the compressor 56 operates at 100% capacity to maximize the capacity. The second intercooler 44 is cooled, and operates at 50% capacity when the intake air temperature is higher than the first set value but lower than the second set value.

The determination result in step 207 is "ON" when the occupant has not selected cabin cooling. In this case, the second intercooler 44 and compressor capacity are controlled according to the intake air temperature. That is, the air conditioner switch 78 is “
OFF”, in step 219 it is determined whether the intake temperature T measured by the intake temperature sensor 86 is smaller than the set value A (30°C). If T<30°C, the second
Since there is no need for intake air cooling by the intercooler 44,
In step 220, the compressor electromagnetic clutch 74 is disengaged, in step 221, the second electromagnetic valve 82 is closed, and in step 2
At 22, the first solenoid valve 64 is closed. As a result, cooling of the intake air by the second intercooler 44 is stopped, and cooling of the passenger compartment is also stopped.

If T≧set value A (30°C), it is necessary to cool the intake air by the second intercooler 44, so step 223
Then, the compressor electromagnetic clutch 74 is connected and the compressor is operated. Next, in step 224, T
≦Determine whether or not the second set value (50℃), 30℃≦T≦
When the temperature is 50°C, the compressor capacity is reduced to 50% by energizing the solenoid 76 in steps, and T>
50"C, in step 226 the solenoid 76 is set to "F" to set the capacity to 100%.Next, in step 2
At step 27, the second electromagnetic valve 82 is opened to circulate the refrigerant to the second intercooler 44, and the process proceeds to step 222.

The following table shows the execution results of the program shown in the flowchart of FIG. 4 explained above in an easy-to-understand manner.

As can be seen from the above, the water-cooled first intercooler 42 is activated when the engine load is equal to or higher than the set value.

On the other hand, the second intercooler 44 is the first intercooler 4
2 and the second intercooler 44 becomes equal to or higher than the first set value A (for example, 30''C).

In that case, when the intake temperature is equal to or higher than the first set value and lower than the second set value B (for example, 50'C), the strip refrigerant compressor
Operated at 0% capacity, 100% when the second set value or higher
Operated at capacity.

〔Effect of the invention〕

In the intake air cooling device of the present invention, when the engine load is high, the intake air is first cooled by the water-cooled first intercooler.

When the intake air temperature exceeds the first set value A, the second intercooler is activated and the intake air is further cooled by the second intercooler, so the intake air is cooled in two stages by both the first and second intercoolers. cooling capacity increases. As a result, the occurrence of knocking can be prevented without delaying the ignition timing and without making the air-fuel ratio too rich, resulting in improved engine output and reduced fuel consumption.

Moreover, since the capacity of the refrigerant compressor is reduced when the intake air temperature is less than the second set value B, the compressor drive load is reduced, further improving fuel efficiency.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a control circuit, and FIGS. 3 and 4 are flowcharts of a control routine for an intake air cooling device. 14... Intake passage, 20... Supercharger, 24
...control circuit, 28...crank pulley,
42...Water-cooled first intercooler, 44...Refrigerant-cooled second intercooler, 46...Cooling liquid circulation means, 50...Water pump, 52...Radiator, 54...Freezing circuit, 5
6... Refrigerant compressor, 64... First solenoid valve, 74... Electromagnetic clutch for compressor, 76... Capacity variable solenoid, 78... Air conditioner switch, 80... Branch circuit, 82... ...Second solenoid valve, 8
6...Intake temperature sensor.

Claims (1)

[Claims] 1. The variable capacity refrigerant compressor (56) disposed in the refrigeration circuit (54) of the vehicle cooling system is connected to the electromagnetic clutch (74).
), the internal combustion engine is equipped with an output section (28) driven through a supercharger (20) and a supercharger (20) in the intake system. a water-cooled first intercooler (42); (b) a coolant circulation means (46) for circulating the cooled coolant to the first intercooler; and (c) a first intercooler downstream of the first intercooler. a second intercooler (44) that is installed in the intake system in series with the intercooler and cools the intake air with a refrigerant; a branch circuit (80) that circulates to the second intercooler; (e) an electromagnetic shutoff valve (82) that opens and closes the branch circuit; (f) the coolant circulation means (46); and an electromagnetic clutch (7).
4), a control circuit (24) for controlling the variable capacity refrigerant compressor (56) and the electromagnetic shutoff valve (82), which controls the cooling liquid circulation means (24) when the engine load is above a set value;
46), the first intercooler (42) and the second
When the intake air temperature between the intercooler (44) and the intake air temperature is equal to or higher than the first set value, the electromagnetic clutch (74) and the electromagnetic shutoff valve (82) are operated to circulate the refrigerant to the second intercooler. a second set value greater than the first set value;
a control circuit (24) that reduces the capacity of the variable capacity compressor (56) when the intake air temperature is less than a set value and maximizes the capacity of the compressor when the intake air temperature is equal to or higher than the second set value;
, and an intake air cooling device.