JP2001280142A - Turbo supercharging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo supercharging system of a series two-stage supercharging capable of avoiding failure caused by raising the temperature of a compressor of a high pressure stage by effectively cooling air supplied from a compressor of a low pressure stage without using surplus power by carrying out wasteful cooling. SOLUTION: In the turbo supercharging system of a series two-stage supercharging wherein a first turbine 31 of a first supercharger 30 and a second turbine 41 of a second supercharger 40 are disposed in an exhaust passage 22 of an internal combustion engine 10 and a second compressor 42 of the second supercharger 40 and the first supercharger 30 of an intermediate air supply cooler 50 are disposed in order from an upstream side of an intake passage 12, cooling performance of the intermediate air supply cooler 50 is changeably constituted, and a control device 60 is disposed so as to cool a cooling performance of the intermediate air supply cooler 50 according to a value detected by a temperature sensor 61 disposed on a downstream side of the first compressor 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line two-stage turbocharging system in an internal combustion engine such as a diesel engine or a gasoline engine, in which compressors are arranged in two stages in series.

[0002]

2. Description of the Related Art In a supercharged engine, an intercooler or a charger is provided downstream of a compressor in an intake passage for cooling supply air heated by a compressor in order to sufficiently supply and charge intake air to a cylinder. An air-supply cooler called a cooler is provided to cool the air-supply air whose temperature has been increased by compression.

In order to cool the air supply cooler which exchanges heat with the air supply, running air is blown or air is blown by a fan directly driven by an engine or an electric fan. In the above-described means other than the cooling by the traveling wind, a driving loss occurs, and fuel efficiency is deteriorated.

In a large engine, a large-capacity turbine is driven when the load or the number of revolutions is large, and the turbine is switched to a small-capacity turbine when the load or the number of revolutions is small, and the turbine is driven and supercharged. There is a switching type two-stage supercharging system.

On the other hand, since the exhaust gas discharged from the first-stage exhaust gas turbine still has sufficient exhaust energy available, the second-stage exhaust gas turbine is provided to provide the second-stage exhaust gas turbine.
There has been proposed an in-line two-stage supercharging system in which a stage compressor is driven, the air supply is further compressed, and the air is supplied to the engine at high supercharging to improve the charging efficiency.

As described above, when the compressors are arranged in two stages in series, the supply air is compressed by the compressor at the low pressure stage on the upstream side and the temperature is increased, and further the temperature is increased by the compressor at the high pressure stage on the downstream side. In particular, when a cooling device is not provided during this period, the temperature at the outlet of the high-pressure stage compressor becomes 200 ° C. or more at maximum, and the heat resistance and durability of the high-pressure stage compressor are problematic. Also, when the supply air temperature increases,
Since the compression capacity of the high-pressure stage compressor is also reduced, it is necessary to cool the supply air with an intermediate air supply cooling device before entering the high-pressure stage compressor.

[0007]

However, the intermediate air supply cooling device provided between the two compressors is replaced by a normal air supply cooling device (intercooler) provided between the high-pressure stage compressor and the air supply manifold. ), The same structure at the front or rear of the engine will cause problems in the front-rear space of the engine, complicated pipes and increased flow resistance of the pipes. Thus, there is a problem that the arrangement is actually difficult.

On the other hand, in the case of a series two-stage supercharging system,
Depending on the operating region of the engine, the supply air temperature at the outlet of the compressor in the low-pressure stage does not increase, so this intermediate supply cooling device does not need to always have high cooling performance,
Only in the case of high load and high rotation, etc., it is sufficient that the supply air can be cooled such that the compressor in the high pressure stage is at or below the allowable temperature limit.

In addition, in the case of the in-line two-stage supercharging system, the power used for cooling the air supply is larger than that of the one-stage supercharging system, so that the driving loss is increased. Since fuel efficiency tends to deteriorate, it is necessary to reduce the drive loss and minimize the power used for cooling the supply air.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide an in-line two-stage supercharger capable of efficiently converting exhaust energy into turbocharger energy to enable high supercharging. In a turbocharged turbocharger system, the air supply from the low-pressure stage compressor can be efficiently cooled to avoid a failure due to the temperature rise of the high-pressure stage compressor. An object of the present invention is to provide a two-stage turbocharger system that can improve fuel efficiency without using a turbocharger.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, a turbocharger system includes a first turbine and a first turbine of a first supercharger driven by exhaust gas in an exhaust passage of an internal combustion engine. A turbocharger having a second turbocharger and a second compressor driven by the second turbine and a first compressor driven by the first turbine arranged in two stages in series from the upstream side of an intake passage. In the supercharging system, an intermediate air supply cooler is provided between the first compressor and the second compressor for cooling the air supply compressed and heated by the second compressor, and a cooling capacity of the intermediate air cooler is provided. Is configured to be changeable, and the first
A control device is provided for controlling the cooling capacity of the intermediate air supply cooler in accordance with a detection value of a temperature sensor provided downstream of the compressor.

In the above turbocharger system, the cooling capacity of the intermediate supply cooler is changed by an electric fan that cools the intermediate supply cooler.

That is, the high pressure stage (first) and the low pressure stage (second)
An air supply cooler cooled by an electric fan is provided between the two compressors, and the drive of the electric fan is controlled in accordance with a detection value of a temperature sensor provided downstream of the first compressor in the high-pressure stage, Change the cooling capacity of the intermediate supply cooler.
This “change” includes not only continuous changes but also ON / O
It also includes two-stage switching of the FF and switching of a plurality of stages and multi-stages.

The cooling capacity may be switched between ON / OFF when the electric fan is driven and when it is not driven, or may be changed by controlling the number of revolutions of the electric fan.

In the turbocharger system having the above configuration, the supply air temperature is detected at the outlet of the first compressor of the high pressure stage to be protected, and the cooling capacity of the intermediate air supply cooler is changed or changed according to the detected value. Since the switching is performed, the supply air is efficiently cooled without performing unnecessary cooling. Further, since the supply air temperature at the inlet side is reduced so that the supply air temperature at the outlet of the first compressor of the high-pressure stage becomes equal to or lower than a predetermined value, it is possible to prevent the first compressor from becoming hot.

Further, the intake passage between the two compressors of the high pressure stage and the low pressure stage has a very simple structure in which only the intermediate air supply cooler is arranged. Increase.

Since the electric fan is not driven for useless cooling, the loss of cooling driving energy is reduced and fuel efficiency is improved.

The change and control of the cooling capacity of the intermediate air supply cooler are optimally driven and controlled by an electric fan, and the system is simplified, but the following configuration is also conceivable.

For example, an exhaust turbine is provided on the downstream side of the second turbine, and a cooling fan for cooling the intermediate air supply cooler is rotationally driven by the exhaust turbine, and this rotation is performed, for example, on the downstream side of the second compressor. The control may be performed by turning on / off the clutch according to the detection value of the sensor.

The rotation of the cooling fan mechanically driven by a belt drive or the like from the crankshaft of the engine is controlled by turning on the clutch in accordance with a detection value of a temperature sensor provided downstream of the second compressor, as described above. The control may be performed by turning on / off.

Alternatively, it is conceivable to provide a bypass passage in a part of the intermediate air supply cooler and control the opening and closing of the valve at the entrance of the bypass passage to change the cooling capacity. However, in this case, even if the cooling performance is reduced by bypassing the air supply, energy for cooling is not saved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a turbocharging system according to the present invention will be described with reference to the drawings.

The turbocharger system 1 includes an engine 1
Exhaust passage 22 connected to exhaust manifold 21
In the order from the upstream side, the first supercharger 30 of the high pressure stage
A turbine 31, a second turbine 41 of a second supercharger 40 at a low pressure stage, and a muffler (silencer) 23 are provided.

An air cleaner 13 and an air cleaner 13 are arranged in the intake passage 12 connected to the intake manifold 11 in order from the upstream side.
First of the second supercharger (turbocharger) 40 of the low pressure stage
Compressor 42, intermediate charge cooler 50, first high pressure stage
The first compressor 32 and the supply air cooler (intercooler: charge cooler) 15 of the supercharger 30 are provided.

An electric fan 51 is provided immediately adjacent to the intermediate supply air cooler 50 to cool the supply air A which has been heated by being compressed by the second compressor 42 of the second supercharger 40 at the low pressure stage. The electric fan 51 is connected to the first compressor 3
A control device 60 is provided on the downstream side of the apparatus 2 for controlling according to the detection value of the temperature sensor 61 provided on the upstream side of the air supply cooler 15.

The control device 60 controls the temperature sensor 61
When the temperature of the air supply A, which is the detected value of the air supply A, becomes equal to or higher than a predetermined value, the control to turn on the electric fan 51 is performed, and the cooling performance for the air supply A is improved by cooling the intermediate air supply cooler 50,
The temperature of the air supply A entering the first compressor 32 is reduced to protect the first compressor 32.

When the detected value of the temperature sensor 61 is less than a predetermined value, the temperature of the air supply A is not high even if the cooling performance of the intermediate air supply cooler 50 is lowered. 32 can be protected. Therefore, the electric fan 51 is
Perform FF control to avoid wasting energy.

The cooling of the air supply cooler 15 downstream of the first compressor 32 of the first supercharger 30 is performed by a cooling fan (not shown) driven directly by the engine, running air, etc., similarly to the known technique. It is arranged in front of or behind the engine 10 so that it can be cooled.

Further, the first supercharger 30 of the high pressure stage
An exhaust bypass passage 24 bypassing the first turbine 31 and an adjusting valve 25 provided at the inlet of the exhaust bypass passage 24, and the opening and closing of the adjusting valve 25 is controlled based on the engine speed and the like. Thereby, the first turbine 31 of the first supercharger 30 and the second supercharger 40
Of the second turbine 41 is adjusted. By this adjustment, the ratio of the compression ratio of the supply air by the first compressor 32 in the high-pressure stage and the second compressor 42 in the low-pressure stage is adjusted.

According to this configuration, the exhaust gas G discharged from the exhaust manifold 21 of the engine 10 is sent to the first supercharger 30 at the high pressure stage to drive the first turbine 31,
The first compressor 32 on the same axis is rotated to supercharge the intake air, and the gas that has passed through the first turbine 31 is
Further, the air is sent to the second supercharger 40 at the low pressure stage, drives the second turbine 41, and is discharged to the atmosphere via the muffler 23.

On the other hand, after passing through the air cleaner 13, the supply air A is supplied to the second compressor 42 of the second supercharger 40 at the low pressure stage.
And then cooled by an intermediate fan cooler 50 cooled by an electric fan 51 controlled by a control device 60, and then cooled by a first supercharger 30 of a high pressure stage. The temperature is further compressed by the first compressor 32 to increase the temperature, and is cooled by the air supply cooler 15 and then supplied to the intake manifold 11.

According to the turbocharger system having the above configuration, the controller 60 controls the first compressor 3 in the high-pressure stage.
The intermediate fan cooler 50 is cooled by the electric fan 51 controlled according to the detection value of the temperature sensor 61 provided downstream of the first compressor 31, so that the temperature of the supply air A entering the first compressor 31 is surely lowered. Thus, the first compressor 31 can be protected.

The temperature of the supply air A at the outlet of the first compressor 31 is low, and the temperature of the first compressor 3
If there is no fear of damage to the motor, turn off the electric fan 51
F, energy loss can be avoided, so that fuel efficiency can be improved and engine output can be increased.

Further, since the electric fan 51 is not driven directly from the crankshaft of the engine 10, the range of installation locations can be widened and the degree of freedom in layout can be increased.

The cooling capacity of the intermediate air supply cooler 50 is switched between ON and OFF when the electric fan 51 is driven and when it is not driven. The first compressor is controlled by controlling the rotation speed of the electric fan 51. Controlling the temperature of the supply air A downstream of 32 to not exceed a predetermined value can further reduce energy loss.

Incidentally, for example, when the superchargers 30 and 40 operate most at medium speed, the supply air temperature is about 100 ° C. at the outlet of the second compressor 42 in the low pressure stage, and the supply pressure is Is about 170 kPa. When the electric fan 51 is not driven, at the outlet of the first compressor 32, the supply air temperature is about 200 ° C. and the supply air pressure is about 29 ° C.
Although it is about 0 kPa, when the electric fan 51 is driven, the supply air temperature at the outlet of the first compressor 32 is about 170 ° C. and the supply air pressure is about 300 kPa.

[0037]

As described above, according to the turbocharger system according to the present invention, the supply air temperature is detected at the outlet of the first compressor of the high pressure stage to be protected, and the intermediate temperature is determined in accordance with the detected value. Since the cooling capacity of the supply air cooler is changed or switched, the supply air temperature at the outlet of the first compressor at the high pressure stage can be lowered so as to be equal to or lower than a predetermined value. Can be protected from

Further, since the rise in the supply air temperature at the inlet can be suppressed, the compression performance of the first compressor in the high-pressure stage can be favorably maintained.

Then, only when necessary, the cooling capacity of the intermediate air supply cooler is increased, so that unnecessary cooling is not performed.
The loss of driving energy for cooling can be reduced, and fuel efficiency and engine output can be improved. Further, since the cooling and recompression of the air supply can be performed efficiently, the charging efficiency of the air supply can be maintained in a good state.

In addition, since only the intermediate air supply cooler is arranged in the intake passage between the two compressors of the high pressure stage and the low pressure stage, the structure becomes extremely simple. The degree of freedom in the layout can be increased, and the piping can be simplified, so that the design becomes easy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a turbocharging system according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbocharger system 12 Intake passage 22 Exhaust passage 30 First supercharger 31 First turbine 32 Second compressor 40 Second supercharger 41 Second turbine 42 Second compressor 50 Intermediate supply cooler 51 Electric fan 60 control device 61 temperature sensor

Claims (2)

[Claims] An exhaust passage of an internal combustion engine includes a first turbine of a first supercharger driven by exhaust gas and a second turbine of a second supercharger, and is driven by the second turbine. In a turbocharger system in which a second compressor and a first compressor driven by the first turbine are arranged in two stages in series from the upstream side of an intake passage, a turbocharger is provided between the first compressor and the second compressor.
An intermediate air supply cooler that cools the air supply that has been compressed and heated by the second compressor is provided, and the cooling capacity of the intermediate air supply cooler is configured to be changeable, and is provided downstream of the first compressor. A turbocharger system, comprising: a control device that controls a cooling capacity of the intermediate air supply cooler according to a value detected by a temperature sensor. 2. The turbocharger system according to claim 1, wherein the cooling capacity of the intermediate charge air cooler is changed by an electric fan that cools the intermediate charge air cooler.