JPS63186916A - Control of operation of power turbine - Google Patents

Abstract

PURPOSE:To reduce the variation width of the quantity of exhaust gas supplied into a supercharger by adjusting the quantity of exhaust gas introduced into a power turbine, in the constitution in which a power piston for recovering the exhaust gas supplied from a Diesel engine as power is equipped. CONSTITUTION:A supercharger 1 consisting of a turbine T driven by exhaust gas and a compressor C driven by the power of the turbine T is connected with a Diesel engine 2. A bypass line 3 making a detour around the turbine T of the supercharger 1 is formed, and a power turbine 4 is installed midway into the bypass line 3, and the energy of the exhaust gas is recovered as the power in the power turbine 4, and transmitted to the main shaft 6 of the engine 2. With such constitution, the gas inlet to the power turbine 4 is divided into two parts, and bypass pipes 8 and 9 into which the bypass valves 5a and 5b are installed are connected with the gas inlets 7a and 7b. Each bypass valve 5a, 5b is opening/closing-controlled stepwise according to the load.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a power turbine attached to a diesel engine that is used to recover the energy of exhaust gas discharged from a diesel engine equipped with a supercharger as power. This is related to the operation control method.

[Prior Art] A diesel engine equipped with a supercharger is equipped with a power turbine to recover the energy of exhaust gas discharged from the diesel engine and sent to the supercharger as power.

As a conventional diesel engine with a power turbine, the third
As shown in the figure, a supercharger 1 is equipped with a turbine T that rotates a blade wheel by introduced gas, and a compressor C that rotates the blade wheel by the turbine T, compresses intake air, and discharges it. In a configuration in which the compressor C of the supercharger 1 is connected to the diesel engine 2 and the exhaust gas from the diesel engine 2 is sent to the turbine T of the supercharger 1, A bypass line 3 is provided to bypass a part of the exhaust gas sent to the turbine of the engine 1, and a power turbine 4 and a bypass valve 5 are installed in the middle of the bypass line, and the energy of the exhaust gas is used as motive power by the power turbine 4. The main shaft 6 of the diesel engine 2 is rotated.

The power turbine 4 is used when the load of the diesel engine 2 is about 50% or more, and the power turbine 4 is designed to bypass exhaust gas at a proportion to the total amount of exhaust gas discharged from the diesel engine 2. 4 is determined, and the performance of the power turbine 4 is maintained by the bypassed gas, and the output of the supercharger 1 is obtained by the exhaust gas sent to the supercharger 1, thereby increasing the performance of the diesel engine 2. That's how it is.

The reason why the exhaust gas bypass ratio is set to a value as described above is that if the number of bypasses is too small, sufficient power cannot be recovered by the power turbine 4, and conversely, if the amount of bypass is too large, the power Although the recovery power of the turbine 4 can be increased, the amount of exhaust gas sent to the supercharger 1 will be reduced, making it impossible to obtain sufficient supercharger output, and there is a risk that the performance of the diesel engine 2 will deteriorate. This is to prevent this.

[Problems to be solved by the invention] However, in the conventional power turbine 4,
There is only one inlet lower for the exhaust gas to be bypassed, and its size is determined so that the amount of bypass is always constant, and since the amount of bypass is set to a certain amount, the bypass valve 5 is When controlling the power turbine 4 by introducing or stopping the exhaust gas bypassed by opening and closing the power turbine 4, the amount of exhaust gas sent to the supercharger 1 changes greatly, and this changes the amount of exhaust gas sent to the diesel engine 2. There is a huge difference in the intake pressure. That is, the conventional power turbine 4 is not configured to be able to reduce the amount of change in the bypassed exhaust gas, and has many bypasses, so when the bypass valve 5 is open, the bypass exhaust gas entering the power turbine 4 is The amount of exhaust gas sent to the supercharger 1 decreases rapidly due to the amount of The amount of exhaust gas sent to the charger 1 will increase rapidly, and the amount of exhaust gas sent to the supercharger 1 will fluctuate greatly when the bypass valve 5 is opened and closed, and it will also affect the power turbine 4. There is a wide range in the amount of exhaust gas that may or may not work. Therefore, there is a large difference in the intake pressure Psc entering the diesel engine 2 from the supercharger 1, and it changes greatly as shown in FIG. 4 when the bypass valve 5 is opened and closed. The angle also changes greatly when the bypass valve 5 is opened and closed, as shown in FIG. This change becomes larger as the amount of bypass increases. The above-mentioned rapid changes in pressure and temperature can be a factor that shortens the life of the diesel engine.

Therefore, the present invention aims to reduce the range of change in the amount of exhaust gas sent to the supercharger even when the power turbine is operated by bypassing a part of the exhaust gas, or when the amount of bypass is set to zero. This is an attempt to solve the above-mentioned conventional problems.

[Means for Solving the L Problem] In order to achieve the above object, the present invention makes it possible to adjust in stages the amount of exhaust gas that enters the power turbine and is bypassed, so as to avoid excess gas when opening and closing the bypass valve. The method is to adjust the amount of bypass gas to the power turbine so as to reduce the difference in the amount of exhaust gas sent to the feeder.

[Effect] When opening and closing the bypass valve, reducing the amount of bypass gas that enters the power turbine reduces the difference in the amount of exhaust gas that enters the turbocharger when bypassing and when there is no turbulence, which reduces the amount of exhaust gas that enters the diesel engine. Intake pressure no longer changes suddenly. Furthermore, since the amount of bypass is reduced, changes in the turbine inlet temperature and outlet temperature can also be suppressed to a small level.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the method of the present invention, in which a diesel engine 2 equipped with a supercharger 1 is
In a configuration in which a power turbine 4 is attached to recover the energy of the exhaust gas from the exhaust gas as motive power, and a part of the exhaust gas is bypassed, the gas inlet to the power turbine 4 is divided into two parts 7a and 7b. , a bypass pipe 8.9 is connected to each of the gas-filled lowers a and 7b, and each bypass pipe 8.9 is provided with a bypass valve 5a and 5b, respectively. In the figure, the same parts as in FIG. 3 are given the same reference numerals.

When the load of the diesel engine 2 is about 50% or more, a part of the exhaust gas is bypassed to operate the power turbine 4,
The energy of the exhaust gas is recovered as power by the power turbine 4 and used to return it as the rotation of the main Itl 16, but the exhaust gas is bypassed by opening and closing the bypass valve, or the exhaust gas is not bypassed and all of it is supercharged. When sending to machine 1, do the following.

First, when part of the exhaust gas is not to be bypassed, both the bypass valves 5a and 5b of each bypass pipe 8.9 are closed (process).

Next, after a certain period of time, for example, one of the bypass valves 5a
Open only (Step ■). At this time, the other bypass valve 5b
Since the bypass valves 5a and 5b are closed, the amount of exhaust gas bypassed is half of the total amount of bypass, and since the amount of exhaust gas bypassed is small, when both bypass valves 5a and 5b are closed, Compared to the amount of exhaust gas sent, the amount of exhaust gas sent to the supercharger 1 when only the bypass valve 5a is opened is not so small. Therefore, as shown in FIG. 2, the range of change in the intake pressure Psc of the diesel engine 2 is significantly smaller than in the conventional system shown in FIG. 4, and there is no sudden change. Also, the turbine inlet temperature TV
Since the amount of bypass is small under T and the turbine outlet temperature TN, the range of change becomes small as shown in FIG.

Next, when the bypass valve 5b is opened after a certain period of time (step III), both the bypass valves 5a and 5b are all opened, and a large amount of gas is bypassed and enters the power turbine 4. At this time as well, the change in the bypass amount is the increase due to the opening of the bypass valve 5b, and between the process 2, the intake pressure and temperature no longer change rapidly.

Note that the present invention is not limited to the above-described embodiment, and for example, the power turbine 4 may have two or more gas inlets and two or more bypass valves may be provided. By increasing the number of gas inlets and sequentially opening and closing the bypass valves, it is advantageous that the range of change in intake pressure, temperature, etc. can be made smaller than 7.
Instead of the configuration in which the power turbine 4 has a plurality of gas inlets and a plurality of bypass valves, a variable capacity nozzle is used in which the power turbine 4 has one gas inlet and one bypass valve, and the amount of bypassed gas can be adjusted. May be adopted. Using such a nozzle has the advantage that smooth changes can be obtained.

[Effects of the Invention] As described above, according to the method of the present invention, the flow of gas entering the power turbine is adjusted so as to change the amount of exhaust gas entering the power turbine and being bypassed in a small range. The amount of bypassed gas can be changed stepwise or smoothly when the valve is fully open or vice versa, eliminating sudden changes in the intake pressure of the diesel engine and the temperatures at the turbine inlet and outlet, thereby increasing the power output. The excellent effect of further extending the life of the turbine-equipped diesel engine can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the degree of change in intake pressure and temperature according to the present invention, and FIG. 3 is a schematic diagram showing a conventional system. FIG. 4 is a diagram showing the degree of change in intake pressure and temperature in the conventional case. 1...Supercharger, 2...Diesel engine, 3...Bypass line, 4...Power turbine, 5.5a,
5b...Bypass valve, 7.7a, 7b...Gas inlet.

Claims (1)

[Claims] 1) In order to recover energy from the exhaust gas from the diesel engine as power, the amount of exhaust gas that is bypassed by entering the power turbine attached to the diesel engine is adjusted when entering the power turbine, and supercharging is performed from the diesel engine. A power turbine operation control method characterized by reducing the range of change in the amount of exhaust gas sent to a turbine.