JP4136262B2 - Turbocharger system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an in-line two-stage turbocharging system in which compressors are arranged in two-stage series in an internal combustion engine such as a diesel engine or a gasoline engine.
[0002]
[Prior art]
In an engine with a supercharger, in order to sufficiently supply and fill the intake air to the cylinder, an intake air called an intercooler or a charger cooler is provided downstream of the compressor in the intake passage for cooling the intake air heated by the compressor. A cooler is provided to cool the supply air whose temperature has been increased by compression.
[0003]
Further, in order to cool the air supply cooler that exchanges heat with the air supply, traveling air is applied or air is blown by a fan or an electric fan directly driven by the engine. In the means other than the cooling by the traveling wind, a driving loss occurs and the fuel consumption deteriorates.
[0004]
In a large engine, a large-capacity turbine is driven when the load and the rotational speed are large, and a small-capacity turbine is switched when the load and the rotational speed are small. There is a two-stage supercharging system.
[0005]
On the other hand, since the exhaust gas discharged from the first stage exhaust gas turbine still has sufficient exhaust energy available, a second stage exhaust gas turbine is provided to drive the second stage compressor, A series two-stage supercharging system has been proposed in which charge air is compressed and supplied to an engine with high supercharging to improve charging efficiency.
[0006]
In this way, when the compressors are arranged in two stages in series, the supply air is compressed by the upstream low-pressure stage compressor to increase the temperature, and further, the temperature is increased by the downstream high-pressure stage compressor. If a cooling device is not provided during this period, the maximum temperature is 200 ° C. or more at the outlet of the high-pressure stage compressor, and the heat resistance and durability of the high-pressure stage compressor becomes a problem. Further, when the supply air temperature becomes high, the compression capacity of the high-pressure stage compressor also decreases, so that it becomes necessary to cool the supply air with an intermediate supply air cooling device before entering the high-pressure stage compressor.
[0007]
[Problems to be solved by the invention]
However, the intermediate charge air cooling device provided between the two compressors has the same structure as a normal charge air cooling device (intercooler) provided between the high pressure stage compressor and the air supply manifold, and the front of the engine. Or, if you try to place it in the same position on the back, there will be problems with the space in the front-rear direction of the engine, complicated piping and increased distribution resistance of the piping, and it is actually difficult to arrange from the viewpoint of engine layout There is a problem.
[0008]
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 low-pressure stage compressor does not increase, so this intermediate supply air cooling device always has a high cooling performance. It is not necessary to be able to cool the supply air so that the high-pressure stage compressor is below the heat-resistant temperature only in the case of high load and high rotation.
[0009]
In addition, in the case of this series two-stage supercharging system, the power used for cooling the supply air becomes larger than that of the one-stage supercharging system, and therefore the driving loss increases and the fuel consumption deteriorates. Therefore, it is necessary to reduce this driving loss and minimize the power used for cooling the supply air.
[0010]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a series two-stage turbocharger that can efficiently convert exhaust energy into supercharger energy to enable high supercharging. In the supercharging system, it is possible to efficiently cool the supply air from the low-pressure stage compressor to avoid a failure due to the temperature rise of the high-pressure stage compressor, and use unnecessary power by performing unnecessary cooling. An object of the present invention is to provide a two-stage turbocharging system in series that can improve fuel efficiency.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a turbocharging system includes a first turbine of a first supercharger and a second turbine of a second supercharger that are driven by exhaust gas in an exhaust passage of an internal combustion engine. In the turbocharger system in which the second compressor driven by the second turbine and the first compressor driven by the first turbine are arranged in two stages in series from the upstream side of the intake passage, the first compressor An intermediate air supply cooler that cools the supply air that has been compressed by the second compressor and heated, and is configured to change the cooling capacity of the intermediate air supply cooler. When it is determined that the engine is in a high-load high-rotation state from the detection values of the load sensor that detects the load state of the internal combustion engine and the rotation speed sensor that detects the rotation speed, the cooling capacity of the intermediate charge air cooler is determined. Configured to provide a control device that performs control to increase.
[0012]
In the turbocharging system, the cooling capacity of the intermediate charge air cooler is changed by an electric fan that cools the intermediate charge air cooler.
[0013]
Further, in the turbocharger system described above, when the control device determines that the state has shifted from the high load high rotation state to the other state, the cooling of the intermediate charge air cooler is performed after a predetermined time lag has elapsed. It is configured to perform control to reduce the capacity.
[0014]
That is, an air supply cooler cooled by an electric fan is provided between the two compressors of the high pressure stage (first) and the low pressure stage (second), and this electric fan is driven by a load sensor (accelerator sensor) of the internal combustion engine. ) And the detection value of the rotation speed sensor to change the cooling capacity of the intermediate charge air cooler. This “change” includes not only continuous change but also ON / OFF two-stage switching and multi-stage and multi-stage switching.
[0015]
The relationship between the detected values of the load sensor and the rotation speed sensor and the high load and high rotation state is determined by collating with map data created in advance by the control device (control unit).
[0016]
This cooling capacity may be switched between ON / OFF when the electric fan is driven and not driven, or may be changed by controlling the rotation speed of the electric fan.
[0017]
Note that the cooling of the air supply cooler (intercooler) between the high-pressure stage compressor and the intake manifold is arranged in front of or behind the engine in the same manner as in the well-known technology, and the engine direct acting cooling fan, running wind, etc. Configure to cool by.
[0018]
In the turbocharging system configured as described above, it is determined whether or not the engine is in a high load and high speed region from the load and the rotational speed of the internal combustion engine. By changing or switching the cooling capacity of the compressor, the supply air temperature at the inlet side of the first compressor of the high pressure stage is lowered to protect the compressor from becoming hot, and at the same time, the compression performance against the supply air Well maintained. Further, when there is no operation state in the high load high rotation region, the cooling capacity of the intermediate air supply cooler is changed or changed to be small, and the air supply is efficiently cooled without performing unnecessary cooling.
[0019]
In addition, since the load sensor and the rotational speed sensor are already installed for controlling the internal combustion engine, it is not necessary to provide a new sensor or wiring for the sensor, and the responsiveness is good. Since the control unit can also use the engine control unit, the system itself is simple and the cost is low.
[0020]
The intake passage between the two compressors of the high-pressure stage and the low-pressure stage has a very simple configuration in which only the intermediate charge air cooler is arranged, and the use of an electric fan increases the degree of freedom in arrangement.
[0021]
In addition, since the electric fan is not driven for useless cooling, loss of driving energy for cooling is reduced and fuel efficiency is improved.
[0022]
In addition, when shifting from the high cooling capacity in the high load high rotation operation area to the low cooling capacity in the other areas, the transition is made not to immediately shift but with a time lag. (2) After all the supply air heated by the compression by the compressor is cooled by the intermediate charge cooler maintaining high cooling performance and passed through the first compressor of the high pressure stage, the cooling performance of the intermediate charge cooler is improved. Therefore, the first compressor of the high pressure stage does not become high temperature.
[0023]
In other words, when switching from high cooling capacity to low cooling capacity is completed without the time lag when the operation in the high load and high rotation range is completed, the energy of the exhaust gas is still high, and the second compressor in the low pressure stage is turned on. Since the pressure and temperature of the supplied air are still high, there is a possibility that the temperature of the first compressor in the high-pressure stage becomes higher than the allowable temperature, but this can be avoided.
[0024]
It should be noted that the change and control of the cooling capacity of the intermediate charge air cooler is optimally driven and controlled by an electric fan because the system is simple and optimal, but the following configurations are also conceivable.
[0025]
For example, an exhaust turbine is provided on the downstream side of the second turbine, and a cooling fan that cools the intermediate air supply cooler is driven to rotate by the exhaust turbine, and this rotation is controlled by turning on and off the clutch by the control device. You may comprise.
[0026]
Moreover, you may comprise so that rotation of the cooling fan mechanically driven by a belt drive etc. from an engine crankshaft may be controlled by turning ON / OFF a clutch by a control device similarly to the above.
[0027]
Alternatively, it is also conceivable that a bypass passage is provided in a part of the intermediate charge air cooler, and the valve at the inlet of the bypass passage is controlled to open and close to change the cooling capacity. However, in this case, even if the supply air is bypassed to reduce the cooling performance, the energy for cooling is not saved.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a turbocharging system according to the present invention will be described with reference to the drawings.
[0029]
The turbocharger system 1 includes, in order from an upstream side, an exhaust passage 22 connected to an exhaust manifold 21 of an engine 10, a first turbine 31 of a first supercharger 30 in a high pressure stage, and a second turbine in a low pressure stage. A second turbine 41 and a muffler (silencer) 23 of the supercharger 40 are provided.
[0030]
In addition, in order from the upstream side to the intake passage 12 connected to the intake manifold 11, the air cleaner 13, the first compressor 42 of the second supercharger (turbocharger) 40 in the low pressure stage, the intermediate charge air cooler 50, the high pressure A first compressor 32 and a charge air cooler (intercooler: charge cooler) 15 of the first supercharger 30 in the stage are provided.
[0031]
Then, an electric fan 51 is provided in the immediate vicinity of the intermediate air supply cooler 50 to cool the air supply A that has been compressed by the second compressor 42 of the second supercharger 40 in the low-pressure stage and raised in temperature. A control device 60 for controlling the fan 51 is provided. The control device 60 usually serves as an engine control unit.
[0032]
The control device 60 has input values detected by a load sensor 61 that detects the load state of the engine 10 and a rotation speed sensor 62 that detects the rotation speed, and the load and rotation speed that are the detection values are created in advance. When the map data illustrated in FIG. 2 is collated and it is determined that the load is in the high load / high rotation region, that is, the ON region, the electric fan 51 is controlled to be turned on to cool the intermediate air supply cooler 50. Increase ability.
[0033]
Further, when it is determined that it is in an area other than high load and high rotation, that is, in an OFF area, a control is performed to turn off the electric fan 51 after a predetermined time lag, for example, about 30 sec to 3 min has elapsed. The cooling capacity of the supply air cooler 50 is lowered.
[0034]
By the ON / OFF control of the electric fan 51, the supply air is cooled by the intermediate supply cooler 50 in the high cooling performance state when the temperature of the supply air rises during high load high rotation operation, and the high pressure The temperature of the supply air A entering the first compressor 32 of the stage is lowered to protect the first compressor 32, and the cooling performance is low when the temperature of the supply air is little increased in an operation region different from the high load high rotation operation. Since the first compressor 32 can be protected even if it is lowered, the electric fan 51 can be turned off to avoid wasting energy.
[0035]
Further, the cooling of the intake air cooler 15 on the downstream side of the first compressor 32 of the first supercharger 30 is arranged in front of or behind the engine 10 to directly cool the cooling fan ( It is configured to be cooled by running wind or the like (not shown).
[0036]
Further, an exhaust bypass passage 24 that bypasses the first turbine 31 of the first supercharger 30 in the high-pressure stage is provided, and an adjustment valve 25 is provided at the inlet of the exhaust bypass passage 24. The driving amount of the first turbine 31 of the first supercharger 30 and the second turbine 41 of the second supercharger 40 is adjusted by controlling the opening and closing of 25 based on the engine speed and the like. 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.
[0037]
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 in the high pressure stage to drive the first turbine 31, and the first compressor 32 on the same axis is driven. The gas that has been rotated and supercharged of the intake air and has passed through the first turbine 31 is further sent to the second supercharger 40 in the low pressure stage to drive the second turbine 41 and to the atmosphere through the muffler 23. To be released.
[0038]
On the other hand, the supply air A is compressed by the second compressor 42 of the second supercharger 40 in the low pressure stage after passing through the air cleaner 13, and then the intermediate supply air cooler 50 is cooled by the electric fan 51. Then, the air is further compressed and heated by the first compressor 32 of the first supercharger 30 in the high pressure stage, and is cooled by the air supply cooler 15 and then supplied to the intake manifold 11. The
[0039]
According to the turbocharging system having the above configuration, when the control device 60 is in the high load and high rotation range by the electric fan 51 controlled according to the engine operating state determined by the load and the rotation speed of the engine 10. Since the intermediate charge air cooler 50 is strongly cooled, the temperature of the supply air A entering the first compressor 31 can be reliably lowered to protect the first compressor 31.
[0040]
In addition, since the temperature of the supply air A at the outlet of the first compressor 31 is low when there is no high load and high rotation region, and there is no concern about damage to the first compressor 31 due to high temperature, the electric fan 51 is turned off to reduce energy loss. Since this can be avoided, it is possible to improve fuel efficiency and increase engine output.
[0041]
Further, since the cooling fan 53 is not directly driven from the crankshaft of the engine 10, the range of selection of the installation location is widened, and the degree of freedom in layout is increased.
[0042]
The cooling capacity of the intermediate air supply cooler 50 is switched between ON / OFF when the electric fan 51 is driven and when it is not driven. However, the map data function using the load and rotation speed as variables is turned ON / OFF. Energy loss can be further reduced by controlling the rotational speed of the electric fan 51 according to the load and the rotational speed instead of turning OFF.
[0043]
For example, if the turbocharger works most at medium speed, the supply air temperature is about 100 ° C. and the supply air pressure is about 170 kPa at the outlet of the second compressor 42 in the low pressure stage. When the electric fan 51 is not driven, the supply air temperature is about 200 ° C. and the supply air pressure is about 290 kPa at the outlet of the first compressor 32. However, when the electric fan 51 is driven, At the outlet of one compressor 32, the supply air temperature is about 170 ° C., and the supply air pressure is about 300 kPa.
[0044]
【The invention's effect】
As described above, according to the turbocharging system of the present invention, it is determined whether or not the operating state of the engine is in the high-load high-rotation region from the load and the rotational speed of the internal combustion engine, and the high-load high-rotation system When there is an operating condition in the region, the supply air compressed and heated by the second compressor in the low pressure stage is increased by changing or switching the cooling capacity of the intermediate supply air cooler, and the supply air at the inlet side of the first compressor in the high pressure stage is increased. The air temperature can be lowered to protect the compressor from becoming hot. At the same time, the high pressure stage first compressor can be compressed well with respect to the supply air.
[0045]
In addition, when the engine operating state is not in the high-load high-rotation region, the cooling capacity of the intermediate charge air cooler can be changed or switched to reduce the air supply efficiency, and the supply air can be efficiently cooled without performing unnecessary cooling. it can.
[0046]
In addition, since the load sensor and the rotation speed sensor are already installed for controlling the internal combustion engine, it is not necessary to provide a new sensor, wiring for the sensor, etc. Since the engine control unit can be used, the system itself is simple and there is little cost increase.
[0047]
In addition, the intake passage between the two compressors of the high-pressure stage and the low-pressure stage has a very simple configuration in which only the intermediate intake air cooler is arranged. Moreover, the use of an electric fan increases the degree of freedom in arrangement and is wasteful. Since the electric fan is not driven for efficient cooling, loss of driving energy for cooling is reduced and fuel efficiency is improved.
Further, if the map data function with the load and rotation speed of the internal combustion engine as variables is set to the rotation speed of the electric fan instead of ON / OFF, and the control is performed with the rotation speed of the electric fan according to the load and the rotation speed, further energy is obtained. Loss can be reduced.
Further, if a cooling fan is provided in place of the electric fan that cools the intermediate intake air cooler, and an exhaust turbine that rotationally drives the cooling fan is provided downstream of the second turbine in the exhaust passage so that it can be turned ON / OFF by a clutch, More effective use of gas.
[0048]
In addition, when shifting from the high cooling capacity in the high load high rotation operation area to the low cooling capacity in the other areas, the transition is made not to immediately shift but with a time lag. (2) After all the supply air heated by the compression by the compressor is cooled by the intermediate charge cooler maintaining high cooling performance and passed through the first compressor of the high pressure stage, the cooling performance of the intermediate charge cooler is improved. Therefore, it is possible to avoid the first compressor in the high pressure stage from becoming high temperature.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a turbocharger system according to an embodiment of the present invention.
FIG. 2 is a map showing a relationship among a load, a rotation speed, and ON / OFF of an electric fan.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Turbocharger system 12 Intake passage 22 Exhaust passage 30 1st supercharger 31 1st turbine 32 1st compressor 40 2nd supercharger 41 2nd turbine 42 2nd compressor 50 Intermediate | middle intake air cooler 51 Electric fan 60 Control device 61 Load sensor 62 Rotational speed sensor

Claims (1)

A first compressor of a first supercharger driven by exhaust gas and a second turbine of a second supercharger are provided in an exhaust passage of the internal combustion engine, and a second compressor driven by the second turbine; In the turbocharging system in which the first compressor driven by the first turbine is arranged in two stages in series from the upstream side of the intake passage,
Provided between the first compressor and the second compressor is an intermediate supply air cooler that cools the intake air that has been compressed and heated by the second compressor, and a cooling fan that cools the intermediate intake air cooler,
An exhaust turbine that rotationally drives the cooling fan is provided downstream of the second turbine in the exhaust passage so that the exhaust fan can be turned on and off with a clutch, and the cooling capacity of the intermediate charge cooler can be changed. With
When it is determined that the engine is in a high-load high-rotation state based on detection values of a load sensor that detects the load state of the internal combustion engine and a rotation speed sensor that detects the rotation speed , the cooling capacity of the intermediate charge air cooler A turbocharger system characterized in that a control device is provided for performing control to increase by switching to ON .

Images