JPH062553A - Exhaust energy recovery device - Google Patents

Abstract

PURPOSE:To improve efficiency of recovering exhaust energy by mounting a plurality of turbochargers with dynamo-electric machine, and switching a connected flow path. CONSTITUTION:Turbine side flow paths of turbochargers with dynamo-electric machine (TCG) 10, 20 are connected in parallel, to join exhaust gas, after driving, guided to a turbine generator 30 to generate power. Supercharge side flow paths of both the TCG10, 20 are switched to be connected to series connection in a low speed region and to parallel connection in a high speed region, of an engine 2, and both actuated in a region of high pressure efficiency, and also power generation-actuating the dynamo-electric machine to collect exhaust energy as power in the case of an overboost in a high speed region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mounts a rotary electric machine on a turbocharger connected to an engine, recovers exhaust energy to raise intake pressure, and causes the rotary electric machine to generate power to recover energy from a low engine speed to a high speed. The present invention relates to an exhaust energy recovery device that improves efficiency over a wide range.

[0002]

2. Description of the Related Art In recent years, a turbocharger connected to an engine is equipped with a rotating electric machine which serves as an electric motor / generator to perform a supercharging operation which is the original purpose of the turbocharger. An energy recovery system has been developed that is driven to assist the supercharging operation and charge the battery.

On the other hand, in order to improve the efficiency of supercharging operation in a wide range of the engine from a low load region to a high load region, Japanese Patent Laid-Open Publication No.
Japanese Patent Laid-Open No. 1-291727 discloses a two-stage type supercharger for controlling two turbochargers of a small capacity and a large capacity, and as a so-called sequential turbo,
With a turbo having a small capacity and a large capacity, a small capacity is used in a low speed range and a large capacity turbo is used in a high speed range.

[0004]

As described above, in a system in which two turbochargers are used for switching in response to a wide range of engine operations, in order to prevent the boost pressure from temporarily lowering when switching turbines, It is necessary to control the switching of the side flow passage and the compressor side flow passage at the same time.

Further, when the supercharging pressure is appropriately restricted in the high speed range of the engine, the waste gate must be opened to prevent a part of the exhaust energy during the high speed range in order to prevent the over boost pressure. It has the drawback of not becoming.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide an exhaust energy recovery system that efficiently recovers the exhaust energy in a wide operating region of the engine. To provide.

[0007]

In order to achieve the above-mentioned object, according to the present invention, a plurality of turbochargers with a rotating electric machine are attached to an exhaust passage of an engine to improve the efficiency of exhaust energy recovery. In the recovery device, the exhaust flow paths from the engine to the plurality of turbochargers with rotating electrical machines are related to the parallel connection, and the supercharging flow paths are the flow paths that are switched to the series / parallel connection according to the operating state of the engine. An exhaust energy recovery device provided with a switching means is provided.

[0008]

[Operation] The exhaust passage to the turbocharger is connected in parallel, and the supercharging passage is switched to series connection in the low speed range of the engine and parallel connection in the high speed range, so the compressor operates efficiently over a wide operating range. Moreover, in order to prevent overboost, the exhaust energy can be recovered as electric power by driving the rotating electric machine to generate electricity.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a configuration block diagram showing an embodiment of an exhaust energy recovery system according to the present invention, and FIG. 2 is an explanatory view showing a turbocharger with a rotating electric machine used in this embodiment.

First, referring to FIG. 2, the relationship between the turbocharger and the rotary electric machine will be described. 1 is a turbocharger, 2 is an engine, and 3 is a rotary electric machine that serves as a motor generator, and exhaust gas from the engine 2 is exhaust pipe 21. The gas is sent to the turbocharger 1 via the air and is discharged by driving the turbine 11.

A rotary electric machine 3 and a compressor 13 are coaxially attached to the turbine shaft 12, and the compressor 13 driven by turbine torque compresses air to intake pipe 2.
The supercharged air is pressure-fed to the engine 2 via 2. When the exhaust energy from the engine 2 is large, the rotary electric machine 3 generates electricity and charges the battery 5 via the power converter 4. When the engine 2 rotates at a low speed and requires a high load, electric power supplied from the battery 5 is supplied to the rotary electric machine 3 by the power converter 4 to operate the electric motor, and assists the pneumatic operation of the compressor 13 to prevent excessive operation. It will increase the supply pressure. It should be noted that such operation control is performed by a command from the controller 6 that inputs signals from the engine rotation sensor 23, the boost pressure sensor 14, the accelerator pedal sensor 61 serving as a load detection unit, and the like.

The configuration block diagram of FIG. 1 shows a system including two turbochargers (TCG) 10 and 20 with a rotating electric machine and a turbine generator 30. The exhaust passage of the engine 2 is shown in the drawing. As described above, the TCGs 10 and 20 are always connected in parallel, and the exhaust gases after driving the respective two turbines t are connected to drive the turbine generator 30 to be recovered as electric power.

Next, the intake passage will be explained. S is an intake passage, and A, B, C and D are branch passages or joint passages each having an openable / closable valve in a predetermined direction, and the engine 2 is low. At the time of rotation, the compressors c of TCG 10 and 20 are connected in series, and at the time of high rotation, two compressors are connected in parallel. A valve that temporarily releases the compressed air in the W direction is provided in the D branch passage.

FIG. 3 is a process flow chart showing an example of the operation of this embodiment, and the operation will be described based on the figure.

First, in step 1, the engine speed and engine load are input, and based on these signals, it is determined in step 2 whether or not the intake passage is switched between direct and parallel.

When the preparation for switching is made in step 2, the process proceeds to step 3, in which the valve of the flow passage in the W direction in the D branch is temporarily opened. This is TCG10,
When the passages of 20 compressors t are switched from serial to parallel, the pressure changes as shown in FIG. 4, so it is necessary to shorten the time from the start of switching until C = D. The TCG 10 is designed to transiently open the flow path from D to W to maintain the pressure constant.
Is electrically driven, and when the engine speed to be switched is reached, the opened flow path is closed and the electrically driven is stopped.

Therefore, the process proceeds from step 3 to step 4 and the g of the TCG 10 is electrically driven so that the pressure of D becomes constant. Then, in the case of serial / parallel switching, the process proceeds to steps 5, 6 and 7, where W The side flow path is closed and the TCG 10 is stopped from being electrically operated, and the parallel flow path is changed in step 8.

If the preparation for switching the flow path is not made in step 2, the boost pressure is checked in step 9, and the flow ends if the pressure is a predetermined appropriate pressure, but to step 10 if the boost is excessive. Go ahead and let the TCG generate electricity,
Excessive amount of exhaust energy will be converted to electric power and recovered.

FIGS. 5 and 6 show the compressor efficiency η in a curve diagram showing the relationship between the compressor air flow rate and the pressure ratio. In the low speed region of FIG. In the high-speed range of FIG. 6, there is no waste due to opening of the waste gate as in the conventional case, and the electric power is recovered by the power generation of the rotating electric machine.

[0021]

According to the present invention as in the above embodiments,
The two turbine flow paths of the turbocharger with rotating electric machine are always connected in parallel to the exhaust flow path of the engine, and the supercharged air flow path from the compressor is connected in series at low speed range and parallel at high speed range according to the operating condition of the engine. Because it switches to connection,
The compressor performs highly efficient compression operation in a wide range of operating areas, the exhaust gas after driving the turbine is collected and collected as electric energy by the turbine generator, and in the high speed range, it is generated by the rotating electric machine to prevent overboost. Then, the effect that the exhaust energy that has been conventionally discharged by the waste gate can be recovered as electric power is obtained.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of an exhaust energy recovery system according to the present invention.

FIG. 2 is an explanatory diagram showing a turbocharger with a rotating electric machine used in this embodiment.

FIG. 3 is a process flow chart showing an example of the operation of the present embodiment.

FIG. 4 is an explanatory diagram at the time of serial / parallel switching in the present embodiment.

FIG. 5 is a curve diagram showing an example of compressor efficiency according to the present embodiment.

FIG. 6 is a curve diagram showing an example of compressor efficiency according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Turbocharger 2 ... Engine 3 ... Rotating electric machine 10, 20 ... Turbocharger with rotating electric machine 30 ... Turbine generator

Claims (4)

[Claims] 1. An exhaust energy recovery apparatus for mounting a plurality of turbochargers with a rotating electric machine in an exhaust passage of an engine to improve the efficiency of exhaust energy recovery, wherein the turbocharger with a rotating electric machine is connected to a plurality of turbochargers from the engine. An exhaust energy recovery system characterized in that the exhaust passages are connected in parallel, and the supercharging passages are provided with passage switching means for switching between series / parallel connection according to the operating state of the engine. 2. The exhaust energy recovery system according to claim 1, wherein the flow passage switching means switches the supercharging flow passages in series in a low speed region of the engine and in parallel in a high speed region. 3. The exhaust energy recovery system according to claim 1, wherein the control of the excessive supercharging pressure in the high speed range of the engine causes the rotary electric machine to generate electric power. 4. The exhaust energy recovery system according to claim 1, wherein exhaust gas passages of the plurality of turbochargers with rotating electric machines are collected and a turbine generator is connected to the passages.