JPS6161917A - Air intake device of engine with supercharger - Google Patents

Abstract

PURPOSE:To maintain supercharged air temperature constant by detecting the temperature of a supercharger on the lower stream of an evaporator of a freezing device provided on an air intake passage on the lower stream of the supercharger and controlling the degree of opening of a control valve on the inlet side of the evaporator in accordance with the detected result. CONSTITUTION:An engine 1 is provided with a turbo supercharger 4 mounted over an air intake passage 2 and an exhaust passage 3. And a surge tank 14 is provided on the air intake passage 2 on the lower stream of a blower 9 of the supercharger 4, and an evaporator 15 of a freezing device is mounted therein. A control valve 23 controlling coolant flowing amount in the evaporator 15 is mounted on a coolant circulating path 22 of the coolant flow-in side in the evaporator 15. The control valve 23 controls the coolant flowing amount by a control circuit 25 based on the output signal of a supercharged air temperature sensor 24 adjacently provided to the air intake passage 2 of the lower stream of the evaporator 15, and the amount flowing in the evaporator 15 is controlled according to the degree of opening of the control circuit 25.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake system for an engine equipped with a supercharger for performing so-called intake supercharging.

[Prior art 1] Supercharged engines equipped with a supercharger such as a turbo supercharger and designed to improve output performance by improving charging efficiency through intake supercharging are widely used.

One of the major problems faced by such supercharged engines is
The intake air is adiabatically compressed by the supercharger and raised to a wide range above the supercharging temperature, so even if the boost pressure is increased, the charging efficiency will actually increase when the boost pressure increases by 1r. This is an obvious problem.

In order to solve this problem, in the intake passage downstream of the turbocharger,
It is known that a water-cooled or air-cooled intercooler is installed to lower the supercharging temperature, but this type of intercooler has insufficient cooling capacity and may cause the supercharging temperature to drop below the outside temperature. They have the essential drawbacks of not being able to do this, and that their cooling capacity is dependent on the outside temperature.

In addition, instead of a water-cooled or air-cooled intercooler as described in item 1, an evaporator of the refrigeration cycle is installed in a surge tank for buffering intake pulsation, which is installed in the intake passage downstream of the supercharger, and the evaporator uses the evaporator to air the supercharged air. An intake system for a supercharged engine that actively cools the engine has been proposed (
(See Japanese Patent Application Laid-open No. 142932/1983).

As mentioned above, the method of cooling supercharged air using the 9ft evaporator of the refrigeration cycle is superior to supercharged air cooling methods using air cooling or water cooling in that it can cool the supercharged air to a temperature lower than the outside temperature. It's excellent.

By the way, the cooling capacity of the above-mentioned refrigeration cycle is set equal to the amount of heat released by the supercharged air when cooling the supercharged air temperature at that time to a predetermined temperature in the engine's maximum load state, The capacity of the compressor and the capacity (capacity) of the evaporator and condenser that constitute the refrigeration system together with the compressor are determined.

However, during actual operation, the following problems occur.

In other words, the cooling capacity of the refrigeration system is proportional to the compressor rotation speed or the engine rotation speed, so it increases linearly in proportion to the engine rotation speed. On the other hand, the amount of heat released by the supercharged air when lowering the supercharged air to a predetermined temperature is due to the fact that at the start of supercharging, the supercharging pressure is not proportional to the engine rotation speed, which reduces the cooling capacity of the evaporator. I end up using it. Further, even when the engine speed is high, the amount of intake air is small at partial load, so the cooling capacity of the evaporator is used less as described above. If this situation can be expressed in concrete numbers, for example,
If the cooling capacity of the refrigeration system is set to cool the supercharged air of 9 (1'C) to 3 (1'C) at full load, the l , ('l ('l f'l rpm
In the vicinity, the supercharging temperature of 6 T')'C is cooled to below 10'C, resulting in supercooling.

In this way, if supercharged air is supplied to the engine in a supercooled state, the charging efficiency will be excessive, and the vaporization and atomization state of the heating charge will deteriorate, leading to knocking and a decline in emission performance. However, the output performance also deteriorates.

” - As is clear from the above, the flow rate of refrigerant circulating within the refrigeration cycle is basically determined by the rotation speed of the compressor (engine rotation speed) driven by the engine, but in reality is adjusted by an expansion valve installed in the refrigerant passage on the inlet side of the evaporator. The opening degree of this expansion valve is controlled by a temperature-sensitive cylinder attached to a pipe wall forming an outlet-side refrigerant passage of the evaporator.

This temperature-sensing tube uses the thermal expansion of ether to detect the refrigerant temperature at the outlet side of the evaporator, and when the refrigerant temperature rises by one or two degrees, it detects the refrigerant by increasing the opening of the expansion valve. This is to control the expansion valve to increase the flow rate and cooling capacity.

Although the purpose of controlling the refrigerant flow rate using such a temperature-sensitive tube-expansion valve is to control the cooling capacity, the responsiveness of the control is extremely slow.

In addition, there is a drawback that the control range is not too large.

Furthermore, an essential drawback of such a control method is that there is no clear one-to-one correspondence between the refrigerant temperature detected by the thermosensor and the temperature of the supercharged air passing through the evaporator. The key is to maintain a constant temperature.

[Objective of the Invention 1 The object of the present invention is to detect the temperature of the supercharged air cooled by the evaporator of the refrigeration system and to maintain the supercharged air temperature downstream of the evaporator constant. The purpose of the present invention is to provide an intake device for the following.

[Structure 1 of the Invention] In order to achieve the above object, the present invention provides a control valve for controlling the flow rate of the refrigerant in the refrigerant circulation path on the inlet side of the evaporator, and also detects the temperature of the supercharged air downstream of the evaporator. The system is characterized in that the opening degree of the control valve installed on the inlet side of the evaporator is directly controlled according to the detected supercharging temperature.

That is, in the present invention, by controlling the flow rate of refrigerant flowing through the evaporator according to the supercharging temperature downstream of the evaporator, the cooling capacity of the evaporator can be adjusted to the required cooling capacity of the supercharging air, that is, the desired supercharging air. In order to cool down to a low temperature, the evaporator is controlled to match the amount of external heat taken from the supercharged air.

[Advantageous Effects of the Invention 1] According to the present invention, the temperature of the supercharging air supplied to the engine can be kept constant regardless of the operating state of the engine.

In addition, since the refrigerant flow rate of the evaporator is directly controlled according to the superintake air temperature downstream of the evaporator, the responsiveness of the control can be improved by controlling the cooling capacity of the evaporator with good responsiveness. be able to.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the ennon 1 includes a turbo supercharger 4 installed across an intake passage 2 and an exhaust passage 3. As is well known, this turbo supercharger 4 has an exhaust port 6 which is opened and closed by an exhaust valve 5, and an exhaust passage 3.
When the turbine 7 is driven at high speed by the exhaust gas discharged from the engine, the blower 9 connected to the turbine output shaft 8 is driven at high speed, and the blower 9 boosts the pressure of the intake air taken in through the air cleaner 10. When the port 12 is opened, pressurized intake air or supercharged air is supplied to the combustion chamber 13.

The intake passage 2 downstream of the blower g is provided with surge tanks 1, 1 for absorbing and mitigating intake pulsation, and in the surge tanks 1, 4, an evaporator 15 of a refrigeration system, which will be described in detail later, is installed. Further downstream of the surge tank 14, a fuel injection nozzle 16 that is controlled to inject fuel corresponding to the engine operating state and a throttle valve 17 whose opening degree is set according to the engine load are installed.

'' - Similar to those used in automatic coolers, the refrigeration system includes a compressor 19 for compressing refrigerant, which is connected to an output shaft (not shown) by an electromagnetic clutch 18, and a compressor 19 that liquefies the compressed refrigerant. It has a basic configuration in which a condenser 20 is connected in series with a liquid tank 21 that stores the refrigerant liquefied by the condenser 20, and an evaporator 15 installed in the surge tank 14 and a refrigerant circulation path 22. A control valve 23 that controls the flow rate of refrigerant within the evaporator 15 is installed in the refrigerant circulation path 22 on the refrigerant inflow side.

This control valve 23 is connected to the electricity absorption passage 2 downstream of the evaporator 1S.
The control circuit 2.1 receives the output signal of the supercharging temperature sensor 25 installed in the evaporator 15, that is, the supercharging temperature downstream of the evaporator 15.
The opening degree is variably controlled by the opening degree, and the amount of refrigerant flowing through the evaporator 15 is controlled according to the opening degree, thereby changing the cooling capacity of the evaporator 15.

In addition, as shown in FIG. 1, -1- of the evaporator 15
It is preferable that an air-cooled or water-cooled intercooler 26 be installed in the air intake passage 2 to cool the supercharged air, which has been adiabatically compressed and heated to a high temperature by the blower 9, to a certain degree.

The installation of the intercooler 26 is particularly advantageous for reducing the load on the evaporator 15 at high speeds and high loads when the amount of supercharged air increases, and the capacity of the evaporator 15 can be made relatively small.

In addition, in FIG. 1, 27 is a waste gate passage provided by bypassing the turbine 7 of the turbocharger 4, 28 is a waste gate valve that opens and closes the waste gate passage 27,
Reference numeral 29 is a diaphragm type date valve actuator which uses the supercharging pressure in the surge tank 14 as its operating source, and when the supercharging pressure supplied to the engine 1 attempts to rise beyond the preset maximum supercharging pressure, , date valve
actuator 21] opens the wastegate valve 28, bypasses part of the exhaust gas through the wastegate passage 27, suppresses the output of the turbine 7, and controls the boost pressure to the maximum boost pressure.

Next, the control structure of the control valve 23 will be explained.

As shown in FIG. 2, the control valve 23 has a high-pressure refrigerant port 30 connected to the condenser 2 () side via the liquid tank 21, and a low-pressure refrigerant port 30 connected to the inlet side of the evaporator 15. Refrigerant port 31 and valve housing 3
2, the two ports 30 and 31 are connected through a small-diameter communication path 33, and a valve 34 is provided to open and close the high-pressure refrigerant port 30 side of the communication path 33. There is.

The valve 34 is connected to a worm shaft 36 via an operating rod 35, and the worm shaft 36 engages a worm shaft 38 driven by a servo motor 37. The servo motor 37 is driven and controlled by a drive signal applied from the control circuit 25, and when the servo motor 37 is driven, the worm shaft 36 is moved back and forth in the axial direction via the ohm 38. , the opening degree of the valve 34 is set. In the figure, 39 is a return spring that biases the valve 34 in the closing direction.

According to the above configuration, when the supercharging temperature downstream of the evaporator 15 detected by the supercharging temperature sensor 24 deviates from the target temperature, control is performed by applying a drive signal corresponding to the deviation to the servo motor 37. Valve 3 of valve 23
4, the amount of refrigerant flowing into the evaporator 15 can be increased or decreased, and the supercharging temperature can be controlled to the target temperature.

Note that as the valve for controlling the flow rate of refrigerant according to the present invention, an expansion valve used in a conventional refrigeration system can be used as is.

Further, as a means for controlling the flow rate of refrigerant in the evaporator 15, in addition to using the flow rate control valve as described above, for example,
A dedicated motor (not shown) may be provided to drive the compressor 19, and the drive of this dedicated motor may be controlled in accordance with the output of the supercharging air temperature sensor 24.

Furthermore, except for the low engine speed range, turbo supercharging
Since the required cooling capacity of the supercharged air is proportional to the engine speed, the control valve 2 provided for the evaporator 15
3 in accordance with the engine speed, the supercharging air temperature downstream of the evaporator 15 may be controlled to the target temperature.

In this case, the supercharging temperature downstream of the evaporator 15 and the engine speed detected by the supercharging temperature sensor 24 are input to the control circuit 25, and the control valve 23 is controlled by combining these two pieces of input information. do it.

In addition to the turbocharger described above, a vane-type positive displacement pump can be used as the supercharger.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of an engine showing an embodiment of the present invention, and FIG. 2 is a sectional view showing the control structure of the control valve shown in FIG. 1... Engine, 2... Intake passage, 4
...turbocharger, 15...evaporator,
22... Refrigerant circulation path, 23... Control valve, 24
...Supercharging temperature sensor, 25...Control circuit.

Claims (1)

[Claims] (1) In an engine equipped with an evaporator of the refrigeration system in the intake passage downstream of the supercharger, a temperature sensor is provided to detect the temperature of the supercharged air that has passed through the evaporator, and the refrigerant of the evaporator is An intake device for a supercharged engine, characterized in that it is provided with a control means for controlling a flow rate.