JPH03117624A - Turbosupercharge engine - Google Patents

Abstract

PURPOSE:To support shortage of low speed torque, and prevent generation of exhaust smoke at a low speed range by providing two pairs of turbochargers, and combinating them in two-stage at the low speed range, and performing supercharging by only one supercharger at a high speed range. CONSTITUTION:In a diesel engine 14, two pairs of turbochargers 17, 31 are provided. The superchargers 17, 31 are both operated from a low speed range to the maximum torque point, and boost pressure is raised and increase of air quantity is secured. At the higher speed range than the maximum torque point, only the turbocharger 17 is operated. Output torque of the engine 14 at a low speed range is improved, and generation of black smoke in exhaust gas is prevented by increasing the air quantity at the low speed range.

Description

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

The present invention relates to a turbocharged engine, and more particularly to a turbocharged engine in which an exhaust turbine is driven by exhaust gas, and intake air is compressed by a compressor directly connected to the exhaust turbine and supplied into a cylinder.

[Summary of the invention Supercharging is performed only by the charger, which improves low-speed torque and prevents the generation of black smoke due to the lack of intake teeth on the low-speed side. [Prior Art] A conventional turbocharged engine has a structure as shown in FIG. I'm trying to drive it. Since the compressor 4 is directly connected to the turbine 3, the intake air introduced through the air cleaner 5 is transferred to the compressor 4.
The air is compressed by the air intake pipe 6 and introduced into the intercooler 7, cooled by the intercooler 7 to reduce its volume, and then fed into the cylinder through the intake manifold 8. K Problems to be Solved by the Invention The disadvantages of such conventional turbocharged engines are that they lack low-speed torque and generate exhaust smoke at low speeds. That is, in the turbocharger 2, when the engine speed is low, the energy extracted by the turbine 3 is small, so the supercharging effect by the compressor 4 is also small, and low-speed torque tends to be insufficient. When a large amount of fuel is supplied with such a small amount of intake air, there is a problem that the fuel is not completely combusted and black smoke is emitted into the exhaust gas. Therefore, in the past, measures have been taken to increase the boost pressure of the compressor 4 of the turbocharger 2 to a large pressure in the low speed range. However, when such a low-speed turbocharger 2 is used, boost pressure becomes excessive on the high-speed side. Therefore, a waste gate valve 9 is provided, and the valve 9 is opened in the high speed range to directly exhaust the exhaust gas, so that the turbocharger 2 is not used. Therefore, at high speeds, the energy contained in the exhaust gas is simply wasted, and the energy contained in the exhaust gas is not effectively utilized, resulting in poor fuel efficiency. To compensate for the lack of low-speed torque of turbocharged engines,
Attempts have been made to use barrier geometry turbos. This type of turbo changes the angle of the guide vane depending on the engine speed to change the efficiency of the turbine, but even in this case, effective exhaust energy is partially wasted. Therefore, the energy contained in the exhaust gas is lost, resulting in worsening fuel efficiency. The present invention was made in view of these problems, and it compensates for the lack of low-speed torque of a turbocharged engine without wasting the energy of exhaust gas, and also eliminates the generation of exhaust smoke in the low-speed range. The object of the present invention is to provide a turbocharged engine that prevents the above. [Means for Solving the Problems] The present invention provides an engine in which intake air is compressed and supplied into cylinders by a compressor driven by an exhaust turbine, and two sets of turbochargers are provided. In addition to performing supercharging by combining the turbochargers into stages, supercharging is performed by only one turbocharger in the high-speed range.

[Effect]

Therefore, in the low speed range, two sets of turbochargers are combined in two stages to perform supercharging, and the boost pressure in the low speed range increases. In addition, since supercharging is performed by only one turbocharger in the high speed range, an abnormal increase in boost pressure is suppressed, and the energy of the exhaust gas can be used effectively even in the high speed range. Embodiment K FIG. 1 shows a turbocharged engine according to an embodiment of the present invention, and this turbocharged engine is composed of a diesel engine 14. In FIG. An intake manifold 15 and an exhaust manifold 16 are attached to both sides of the cylinder block of the diesel engine 14, respectively. A turbine 18 of a first turbocharger 17 is connected to the exhaust manifold 16, and a compressor 19 directly connected to the turbine 18 is connected to an air cleaner 21 via an intake pipe 20. Further, the outlet side of the compressor 19 is connected to a first intercooler 22 via an intake pipe 20. The outlet side of the intercooler 22 is connected to the intake manifold 15 via a switching valve 23 and an intake pipe 24. The outlet side of the turbine 18 of the first stage turbocharger 17 is connected to a switching valve 27, and this switching valve 27 is connected to a muffler 29 via an exhaust pipe 28. The other outlet of the switching valve 27 is connected to a turbine 32 of a second stage turbocharger 31 via an exhaust pipe 30. An intake pipe 34 is connected to the inlet side of the compressor 33 which is directly connected to the turbine 32 . The tip of this intake pipe 34 is connected to the switching valve 23. Further, the outlet side of the compressor 33 is connected to a second intercooler 36 via an intake pipe 35. The outlet side of this intercooler 36 is connected to the intake pipe 24. In the above configuration, the compressor 19 of the first-stage turbocharger 17 and the compressor 33 of the second-stage turbocharger 31 each exhibit characteristics as shown in FIG. The boost pressure of the compressor 19 reaches its peak in a region where the air flow rate is relatively low. On the other hand, the compressor 3 of the second stage turbocharger 31
No. 3 has the characteristic that its boost pressure is maximized in a region where the air flow rate is somewhat large. As shown in FIG. 3, in a region where the rotational speed of the engine 14 is lower than the rotational speed corresponding to the maximum torque, both the first stage turbocharger 17 and the second stage turbocharger 31 are used. It is now possible to On the other hand, in the region higher than the rotation speed corresponding to the maximum torque, the first
Only one stage turbocharger 17 is used, which causes the engine 14 to produce the torque characteristics shown in FIG. The rotation speed of the engine 14 is detected by the rotation detection sensor 38, and in the low speed range, the controller 37 detects the rotation speed of the engine 14.
switches the switching valve 27 to the turbine 32 side of the second stage turbocharger 31. At the same time, the switching valve 23 is switched to the combination buzzer 33 side of the second stage turbocharger 31. Therefore, the exhaust gas generated by combustion in the cylinders of the engine 14 drives the turbine 18 of the first stage turbocharger 17, then further drives the turbine 32 of the second stage turbocharger 31, and is then discharged through the muffler 29. will be done. Therefore, the intake air introduced through the air cleaner 21 is first compressed by the compressor 19 of the first stage turbocharger 17, and then guided to the first intercooler 22 through the intake pipe 2o, and cooled by this intercooler 22. Thereafter, the intake air is guided to the compressor 33 of the second stage turbocharger 31 by the switching valve 23 and the intake pipe 34, where second stage compression is performed, and the intake air is guided to the second intercooler 36 by the intake pipe 35. After being cooled again here, it is supplied into the cylinders of the engine 14 through the intake pipe 24 and the intake manifold 15. When the rotation speed of the engine 14 exceeds the rotation speed corresponding to the maximum torque, the rotation detection sensor 38 detects this, and the controller 37 switches the switching valve 27 to the muffler 29.
At the same time, the switching valve 23 is switched to the intake pipe 24 side. Therefore, in such a rotation range, the second stage turbocharger 31 does not operate, and supercharging is performed only by the first stage turbocharger 17. That is, exhaust gas generated by combustion within the engine 14 is discharged through the muffler 29 after driving the turbine 18 of the first stage turbocharger 17 . Therefore, air cleaner 2
The intake air introduced by 1 is connected to the first turbocharger 1
After being compressed by the turbine 19 of No. 7 and cooled by the first intercooler 22, the air is supplied to the intake manifold 15 through the switching valve 23 and the intake pipe 24, and is sequentially introduced into the cylinders of the engine 14. As described above, the turbocharged engine according to this embodiment is equipped with two sets of turbo chargers 17.31, and in the range from low speed to the maximum torque point, both sets of turbo chargers 17.31 are The engine is activated to increase boost pressure and increase air volume. On the other hand, at higher speeds than the maximum torque point, only the first stage turbocharger 17 is operated. Therefore, it is possible to improve the output torque of the engine 14 in the low speed range as shown by the solid line in Fig. 3, and the increase in the amount of air in the low speed range prevents the generation of black smoke in the exhaust gas. becomes possible. Further, since turbocharging is performed even in the high speed range, it becomes possible to effectively utilize the energy contained in the exhaust gas, leading to a reduction in fuel consumption. [Effects of the Invention] As described above, the present invention provides two sets of turbochargers and performs supercharging by combining them into two stages in the low speed range.
In the high-speed range, only one turbocharger performs supercharging. Therefore, it is possible to improve the torque in the low speed range and to suppress the generation of black smoke in the exhaust gas by increasing the amount of air. Moreover, since supercharging can be performed by effectively utilizing the energy of exhaust gas even in high-speed ranges, it is possible to reduce fuel consumption.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a turbocharged engine according to an embodiment of the present invention, Fig. 2 is a graph showing the characteristics of the turbocharger, Fig. 3 is a graph showing the characteristics of the engine, and Fig. 4 is a graph showing the characteristics of the turbocharger. FIG. 2 is a plan view of a turbocharged engine. The names of the main parts in the drawings are as follows. 17...First stage turbocharger 18...Turbine 19...Compressor 22...First intercooler 23...Switching valve 27...Switching valve 31...Second turbocharger 32 ... Turbine 33 ... Compressor 36 ... Second intercooler

Claims (1)

[Claims] 1. In an engine that uses a compressor driven by an exhaust turbine to compress intake air and supply it into the cylinder, two sets of turbochargers are installed, and the turbochargers are combined in two stages to perform supercharging at low speeds, and at high speeds. A turbocharged engine that is characterized by being supercharged by only one turbocharger.