JP4530934B2 - Auxiliary turbocharger - Google Patents

Description

  The present invention relates to an improvement of an auxiliary combustion type turbocharger.

  A conventional turbocharged engine compresses air by using exhaust energy of a reciprocating internal combustion engine (hereinafter simply referred to as “engine”) by a turbocharger (hereinafter simply referred to as “supercharger”), and further, an engine by a charge air cooler. Increases the air density sucked in. Since the engine whose air amount is increased in this way can burn more fuel, it can generate a larger output.

  However, when the engine is started or when the engine output is small, the turbocharger speed is low and sufficient air cannot be supplied to the engine, generating harmful exhaust materials due to poor combustion or a rapid increase in load. There is a problem that it is not possible to generate enough power to follow. This is basically due to a lack of engine exhaust energy supplied to the turbocharger.

  Therefore, the following patent document discloses a technique for improving fuel by combusting fuel using a combustor, and joining the generated high-temperature gas with engine exhaust to make up for insufficient energy.

  FIG. 3 shows an example of a system configuration of a conventional turbocharger equipped with the auxiliary combustion type supercharging mechanism.

  This system includes an engine 1, a supercharger 2, a charge air cooler 3, a backup combustor 4, and an automatic control device (not shown). When the engine 1 is composed of a plurality of cylinders, an air supply branch pipe 1 a that connects the intake air inlet of the engine 1 and the air inlet of each cylinder, and an exhaust gas that connects the exhaust outlet of each cylinder and the exhaust outlet of the engine 1. And a branch pipe 1e.

  The supercharger 2 includes a compressor 2c and a turbine 2t coupled to both ends of the shaft 2s. The air outlet of the compressor 2c is connected to the air inlet of the air supply cooler 3 and the air passage a1, and the air supply cooling is performed. The air outlet of the vessel 3 is connected to the air supply inlet of the engine 1 by the air supply passage a2. The air inlet of the combustor 4 is connected to an air supply passage a3 branched from the air supply passage a1, and the air supply passage a3 is provided with a control valve Va.

  The exhaust passage e1 from the engine 1 is connected to the combustor 4, and the gas outlet of the combustor 4 is connected to the gas inlet of the turbine 2t of the supercharger 2 by the exhaust passage e2.

  One side f1 of a fuel supply pipe from a fuel source (not shown) is connected to the engine 1, and the other side f2 is connected to the combustor 4.

  Next, the operation of each part of the apparatus will be described. In FIG. 3, the air sucked into the supercharger 2 is compressed by the compressor 2c and guided to the air cooler 3 through the air supply passage a1. The air cooled by the supply air cooler 3 is guided to the engine 1 through the supply air passage a <b> 2, mixed with fuel and burned, and drives the engine 1.

  Exhaust gas generated by the combustion is guided to the combustor 4 through the exhaust passage e1. Further, a part of the air compressed by the compressor 2c is led to the combustor 4 by the air supply passage a3 branched from the air supply passage a1, and this air becomes a high-temperature gas by the combustion of the fuel supplied to the combustor 4. , And merged with the exhaust of the engine 1 from the exhaust passage e1.

The flow rate of air guided to the combustor 4 side is adjusted by the opening degree of the control valve Va. The valve opening degree is large when the load is low, and the valve opening degree is automatically controlled when the load is high.
The merged exhaust gas is guided to the turbine 2t by the exhaust passage e2, where the power for driving the compressor 2c is generated and then released to the atmosphere.

  The rotational speed of the rotor of the supercharger 2 is determined by the balance between the power generated by the turbine 2t and the load of the compressor 2c, and the speed increases as the exhaust energy from the engine 1 increases. ) Since the load of the compressor 2c exceeds the power generated by the turbine 2t below, the speed cannot be maintained and the vehicle stalls.

Therefore, in the above system, the turbocharged engine not equipped with the conventional combustor 4 cannot supply a sufficient supercharger speed, and the high temperature gas is supplied from the combustor even at the time of start-up, low load, and load increase. Accordingly, the turbocharger speed is increased, and higher-temperature and high-pressure air can be supplied to the engine. Therefore, there is an advantage that the above-described problems can be suppressed.
JP 2004-11551 A

  However, according to the above technique, the flow rate of air passing through the engine 1 increases as the driving speed of the engine 1 increases, so the flow rate of air supplied to the combustor 4 decreases and the gas temperature of the combustor increases. To do.

Particularly in the vicinity of the no-load state, the gas temperature of the combustor 4 often exceeds the allowable value before the engine speed reaches the original upper limit speed, or the combustion cannot be continued due to defective combustion.
If the fuel flow rate to the combustor 4 is decreased, the turbocharger 2 is likely to stall, and if it is increased, the gas temperature further increases. Therefore, the gas temperature cannot be effectively reduced by adjusting the fuel flow rate to the combustor 4. .

  If compressed air is added from the outside, the gas temperature can be lowered, but the equipment for that purpose is expensive, and the operating cost also increases.

  From such a background, a means that can easily and inexpensively lower the gas temperature of the combustor has been desired. Therefore, an object of the present invention is to provide an auxiliary combustion turbocharger in which the temperature of combustion gas is reduced without adding external air.

In order to achieve the above object, the auxiliary combustion turbocharger described in claim 1 is:
A turbocharger driven by exhaust gas; a charge air cooler that cools air supplied by the supercharger; and a turbocharger that combines exhaust gas from the engine and fuel and air that is burned from the turbocharger. In the auxiliary combustion turbocharger that has a combustor to be supplied to the turbocharger and operates the supercharger at high speed with the high-temperature gas from the combustor,
A first flow rate adjusting means disposed between the engine and the supercharger as a separate body from the engine, and provided in an inlet side air supply passage of the charge air cooler; A bypass passage connected to the front stage of the first flow rate adjusting means, bypassing the charge air cooler and communicating between the supercharger and the charge air inlet side of the engine, and a second flow rate disposed in the bypass passage and a adjusting means comprises a flow rate adjusting means for adjusting the flow rate of the supply air passing through the supply air cooler,
By adjusting the first and second flow rate adjusting means, air is circulated only in the bypass passage in the no-load state, and the amount of air supply bypassing the cooler is reduced as the load applied to the engine increases. By increasing the amount of air supply passing through the cooler, the heat adjustment by the air supply cooler is suppressed by the flow rate adjusting means to reduce the gas temperature of the combustor ,
The combustor has an air supply passage for taking in part of the compressed air supplied from the compressor of the supercharger, and third flow rate adjusting means provided in the air supply passage. The third flow rate adjusting means controls the fuel flow so that only the air compressed by the supercharger burns fuel and generates exhaust to reduce the flow rate as the load increases with the no-load state as the maximum flow rate. And
Further, in the no-load operation state of the engine, the air flow distribution to the engine side and the combustor side is adjusted by adjusting the opening degree of the third flow rate adjusting means and the second flow rate adjusting means. It is characterized by.

The auxiliary combustion turbocharger described in claim 2 is the auxiliary combustion turbocharger according to claim 2 ,
The flow rate of the fuel supplied to the combustor is controlled so that the speed or gas temperature of the supercharger is maintained within a predetermined range.

  Therefore, according to the present invention, when the load on the engine is small, the combustor can be operated with less fuel and lower gas temperature than when the supply air cooler is not bypassed, so that the apparatus can be operated economically and stably. At the same time, it is possible to maintain the combustor operating state more appropriately by adjusting the amount of air bypass according to the load state, and to maintain the high speed operation of the turbocharger safely against a wide range of operating state changes. it can.

Furthermore , according to the present invention, in addition to the conventional basic structure, only a bypass flow path and first and second flow rate adjusting means are added, and therefore, this can be realized with a simple mechanism.

Furthermore , according to the present invention, the gas temperature of the combustor is kept low in the no-load state, and the bypass amount is adjusted according to the load, so that the operation state of the combustor can be more appropriately maintained.

Furthermore , according to the present invention, the air amount distribution to the engine and the combustor at the time of no load is determined, and each optimum operation can be performed.

According to the invention of claim 2 , the combustor can be driven at the optimum air-fuel ratio corresponding to the increase or decrease of the air amount.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best mode for carrying out the invention will be described with reference to the accompanying drawings in which a turbocharger for a diesel engine is embodied.

  FIG. 1 shows the overall configuration of a system comprising an engine and a supercharging device according to this embodiment. In addition, the same code | symbol is attached | subjected to the same location as the past shown in the said FIG. 3, and it demonstrates using a new code | symbol only for the newly added location.

In the system of the present invention shown in FIG. 1, a supply air cooler 3 includes a control valve Vc as a first flow rate adjusting means in an air supply passage a1 at its air inlet, and further in a stage preceding the first control valve Vc. The only difference from the conventional system shown in FIG. 3 is that a bypass passage a4 that bypasses the supply air cooler 3 and connects to the supply air passage a2 and a control valve Vb as the second flow rate adjusting means are provided. Other mechanical configurations are the same.
The control valve Va connected to the air supply passage a3 communicating with the combustor 4 has the same configuration as the conventional one as described above, but the control valves Vc and Vb of the present embodiment are not described in the claims. These are the first and second flow rate adjusting means, and this control valve Va is the third flow rate adjusting means.

  Next, the function of each part in the above system will be described. In FIG. 1, the air sucked into the supercharger 2 is compressed by the compressor 2c and guided to the supply air cooler 3 by the supply air passage a1.

  By controlling the first control valve Vc at the inlet of the charge air cooler and the second control valve Vb at the bypass passage a4, the ratio of the air flow rate passing through the charge air cooler 3 is adjusted, and the amount of air supplied to the engine 1 is adjusted. The temperature is adjusted.

  The air whose temperature has been adjusted is guided to the engine 1 through the air passage a2, mixed with fuel and burned, and the engine 1 is driven. The generated exhaust gas is guided to the combustor 4 through the exhaust passage e1.

  Further, a part of the air compressed by the compressor 2c of the supercharger 2 is guided to the combustor 4 through an air supply passage a3 branched from the air supply passage a1. This air becomes high-pressure gas by the combustion of the fuel supplied to the combustor 4 and merges with the exhaust from the engine 1 from the exhaust passage e1.

  The merged exhaust gas is guided to the turbocharger turbine 2t through the exhaust passage e2, and is driven into the atmosphere after being driven by the compressor 2c.

  The opening degree of the first and second control valves Vb and Vc and the control valve Va is adjusted according to the magnitude of the load on the engine 1 by a control device (not shown).

  That is, in the no-load state, the control valve vc is fully closed and the control valve Vb is fully opened. In this state, the air from the compressor 2c of the supercharger 2 remains at a high temperature without being cooled by the charge air cooler. Supplied to the engine 1. Since hot air has a low density, the flow rate of air supplied to the engine 1 is reduced.

  As the load increases, the first control valve Vb is closed and the second control valve Vc is opened. Further, the control valve Va is fully opened in the no-load state, and closes as the load increases.

  In the no-load state, the air flow distribution to the engine 1 and the combustor 4 can be adjusted by appropriately adjusting the opening degree of the second control valve Vb and the control valve Va. The maximum opening is set.

  The fuel flow rate to the combustor 4 is controlled by a control device (not shown) so that the supercharger speed or gas temperature is maintained within a predetermined range.

  If necessary, the air-fuel ratio in the combustor may be adjusted by air bypass similar to that of the charge air cooler 3.

  When the operation of the combustor 4 is stopped during the operation of the engine 1, the fuel to the combustor 4 is shut off, the control valve Va and the second control valve Vb are fully closed, and the first control valve Vc is fully opened. To. In this state, the system is substantially the same as a turbocharger without a combustor.

  2 (a) shows the energy of the conventional system of FIG. 3 when the engine is operated without load, and FIG. 2 (b) shows the energy of the engine when the engine of FIG. 1 is operated with no load. The schematic diagram which shows a flow is shown and supercharger speed is the same in both.

  In these figures, circled A indicates the energy of the fuel supplied to the engine, B indicates the energy of the fuel supplied to the combustor, and C indicates the ratio of the energy circulating in the system.

  First, in the conventional system shown in FIG. 2A, almost all of the energy absorbed by the turbine 2t and transferred to the air by the compressor 2c is released from the air cooler 3 to the outside.

  On the other hand, in the present invention shown in FIG. 2 (b), the energy transmitted to the air by the compressor 2c is not lost by the charge air cooler 3, and the energy circulating in the system increases.

  For this reason, in order to maintain the same supercharger speed, the flow rate of the fuel consumed in the combustor 4 becomes smaller than that in the case of FIG. At the same time, since the supply air to the engine is high temperature, the density is low, and the flow rate of air passing through the engine decreases, so the flow rate of air to the combustor 4 increases.

  As a result, the gas temperature of the combustor 4 is lower than the conventional one, and the gas temperature of the combustor 4 can be effectively increased only by adjusting the air valve opening degree even in the no-load high-speed operation state of the engine where the gas temperature is likely to be the highest. Since the temperature can be lowered, the auxiliary combustion turbocharged engine can be operated economically and safely.

  Further, as shown in the embodiment, when the present invention is applied to a diesel engine, it is possible to simultaneously suppress the speed follow-up delay of the turbocharger and incomplete combustion of the fuel by the high-speed operation of the turbocharger. Engine start-up performance and load response performance can be improved, and generation of black smoke and bad odor in exhaust gas can be reduced. Since the supercharger outlet temperature becomes high even at a low load, when a denitration device or a waste heat recovery device is provided at the exhaust outlet, they can be operated more effectively.

  In the above embodiment, the control valves Va, Vb, and Vc are used as the flow rate adjusting means. However, any other type of variable throttle mechanism such as a damper may be used as long as it has the same function.

  Further, as the outlet temperature adjusting means of the supply air cooler 3, instead of the combination of the bypass flow path a4 and the control valve Vb. It can replace with the flow volume adjustment means of a cooling medium. For example, in the case of an air-cooled cooler, this can also be realized by reducing or stopping the rotation speed of the cooling fan.

1 is a schematic diagram showing an example of a diesel engine equipped with an auxiliary combustion turbocharger according to the present invention. (A) is a schematic diagram which shows the flow of energy in the case of driving | operating by the conventional system, (b) is the case of driving | operating by the system of this invention. It is the structure schematic which shows an example of the engine provided with the conventional auxiliary combustion type turbocharger.

Explanation of symbols

1 engine 2 turbocharger (2t turbine, 2c air compressor)
3 Supply air cooler 4 Combustor a1, a2, a3 Supply air passage a4 Bypass passage f1, f2 Fuel supply piping e1, e2 Exhaust passage Va Third flow rate adjusting means (flow control valve)
Vc first flow rate adjusting means (flow rate control valve)
Vb Second flow rate adjusting means (flow rate adjusting valve)

Claims (2)

A turbocharger driven by exhaust gas; a charge air cooler that cools air supplied by the supercharger; and a turbocharger that combines exhaust gas from the engine and fuel and air that is burned from the turbocharger. In the auxiliary combustion turbocharger that has a combustor to be supplied to the turbocharger and operates the supercharger at high speed with the high-temperature gas from the combustor,
A first flow rate adjusting means disposed between the engine and the supercharger as a separate body from the engine, and provided in an inlet side air supply passage of the charge air cooler; A bypass passage connected to the front stage of the first flow rate adjusting means, bypassing the charge air cooler and communicating between the supercharger and the charge air inlet side of the engine, and a second flow rate disposed in the bypass passage and a adjusting means comprises a flow rate adjusting means for adjusting the flow rate of the supply air passing through the supply air cooler,
By adjusting the first and second flow rate adjusting means, air is circulated only in the bypass passage in the no-load state, and the amount of air supply bypassing the cooler is reduced as the load applied to the engine increases. By increasing the amount of air supply passing through the cooler, the heat adjustment by the air supply cooler is suppressed by the flow rate adjusting means to reduce the gas temperature of the combustor ,
The combustor has an air supply passage for taking in part of the compressed air supplied from the compressor of the supercharger, and third flow rate adjusting means provided in the air supply passage. The third flow rate adjusting means controls the fuel flow so that only the air compressed by the supercharger burns fuel and generates exhaust to reduce the flow rate as the load increases with the no-load state as the maximum flow rate. And
Further, in the no-load operation state of the engine, the air flow distribution to the engine side and the combustor side is adjusted by adjusting the opening degree of the third flow rate adjusting means and the second flow rate adjusting means. An auxiliary combustion turbocharger characterized by The flow rate of the fuel supplied to the combustor, the turbocharger speed or gas temperature co燃式turbocharger according to claim 1, characterized in that it is controlled to be maintained within a predetermined range apparatus.

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