JPH0745802B2 - Energy recovery system for internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound engine with a turbocharger capable of recovering exhaust energy of an internal combustion engine, and particularly to a heat exchanger from exhaust gas from an exhaust turbine. The present invention relates to an energy recovery device for an internal combustion engine that recovers energy.

(Prior Art) In recent years, an adiabatic internal combustion engine has been developed in which ceramics are used for each part of the internal combustion engine, for example, the outer wall of the exhaust manifold, the cylinder liner, the heat insulating plate of the cylinder head, the piston, and the like. According to this internal combustion engine, it is not necessary to radiate the heat generated therein to cool the internal combustion engine, and the energy of the generated high-temperature exhaust gas is recovered and returned to the output shaft of the internal combustion engine. It can be used to improve the output of feedback.

A method for recovering this kind of exhaust energy is disclosed, for example, in JP-A-59-141713 and JP-A-60-233935. According to these proposals, the electric motor is driven by the output of a generator installed in an exhaust turbine driven by the energy of exhaust gas, and the torque of an internal combustion engine is energized, whereby energy is recovered. ing.

(Problems to be Solved by the Invention) In such an exhaust turbine, exhaust gas from a high-temperature and high-pressure internal combustion engine is adiabatically expanded to give energy to turbine blades. Although it still has energy that can be recovered, the flow velocity is slowing and the energy cannot be recovered again by the exhaust turbine. Therefore, the energy that is currently saved with the exhaust gas has not been recovered.

The present invention has been made in view of the above points, and in addition to recovering energy by a conventional turbocharger and an exhaust turbine, further recovers energy including a heat exchanger and a steam turbine, and has a high energy recovery rate. It is an object of the present invention to provide an energy recovery device for an internal combustion engine having the above.

(Means for Solving the Problems) According to the present invention, in an energy recovery device for an internal combustion engine having a turbocharger in which a rotating shaft is provided with an electric motor / generator, the internal combustion engine has a heat shield mechanism. , A turbine driven by exhaust gas and steam on the downstream side of the exhaust turbine of the turbocharger, a heat exchanger for recovering heat from the exhaust gas discharged from the turbine to generate steam, and a high-pressure generator for the heat exchanger. A compressor that supplies water,
A generator disposed on the rotating shaft of the turbine, an electric motor mounted on the output shaft of the internal combustion engine and capable of receiving recovered power, and generated electric power when the motor / generator of the turbocharger operates as a generator There is provided an energy recovery device for an internal combustion engine, comprising: a control device having a means for adding generated electric power of a generator disposed on the rotating shaft of the turbine.

(Operation) In the present invention, high-pressure steam is generated by the heat exchanger provided at the exhaust port of the exhaust turbine of the turbocharger and the compressor for sending high-pressure water to the heat exchanger, and the steam turbine of the high-pressure steam is used. Drive the generator by the steam turbine and generate electricity, and also operate the electric / generator of the turbocharger as a generator, add the electric power of the generator and the electric power of the electric / generator to generate energy. Effective Recovery (Embodiment) Next, an embodiment of the energy recovery apparatus for an internal combustion engine according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a structural explanatory view showing an embodiment of the energy recovery apparatus according to the present invention.

In the figure, reference numeral 1 denotes an internal combustion engine having a heat insulating structure. Although not shown, a combustion chamber such as a piston and a cylinder liner and an exhaust port form a heat insulating structure made of ceramics, and an exhaust manifold 2 is provided with an AC generator-motor 4. The turbocharger 3 that it has is attached.

The turbine blade 3a is attached to the rotary shaft of the turbocharger 3.
, And the rotor 4a of the AC generator-motor 4 and the compressor blade 3b are coaxially and directly connected to each other. The rotor 4a is composed of a permanent magnet having a strong magnetic force made of a rare earth element or the like, and although not illustrated in the stator 4b provided facing the rotor 4a, AC power of a predetermined frequency is supplied from a battery via an inverter. Is supplied, the rotor 4a
Rotates to drive the compressor blade 3b to pump the supercharged air to the internal combustion engine 1, and the exhaust gas discharged from the exhaust manifold 2 of the internal combustion engine 1 rotates the turbine blade 3a to rotate the rotor 4a. When it is driven, it becomes a generator and inputs AC power to a transformer (not shown) connected to the stator 4b. The turbine blades 3a are driven by the exhaust gas from the exhaust manifold 2, and the supercharged air generated by the rotation of the compressor blades 3b is, of course, pressure-fed to the internal combustion engine 1.

Reference numeral 5 denotes an exhaust turbine having an AC generator 6, which is connected to the exhaust port 3c of the turbocharger 3 and is connected to the turbine blade 3a to drive the turbine blade 5a driven by the exhaust gas G in which exhaust energy remains. Have A rotor 6a made of a permanent magnet having a strong residual magnetic force is provided coaxially with the turbine blade 5a, and constitutes an AC generator 6 together with a stator 6b having an AC winding facing the rotor 6a. Further, on the same axis as the AC generator 6, there is a steam turbine 7 which is recovered by superheated steam described later.
Blade 7a is provided.

Reference numeral 8 is a heat exchanger for generating superheated steam or superheated air. The heat exchanger has a steam generating means into which the exhaust gas discharged from the exhaust turbine 5 is introduced and which generates superheated steam by this heat.

The heat exchanger 8 is provided with a compressor 9 that mixes air and water necessary for producing superheated steam and sending the steam to the steam turbine 7 and sends it out in an atomized state. With the above configuration, the generated power from the stator 6b generated by the rotation of the turbine blade 5a is
The residual energy of the exhaust gas G2 of the steam exhaust turbine 5 is enhanced by the rotation of the blades 7a of the steam turbine 7 driven by the superheated steam S obtained via the heat exchanger 8, and the amount of energy recovery by the exhaust gas G2 is correspondingly increased. Will increase. The generated electric power obtained as described above drives the electric motor 10 attached to the rotary shaft of the internal combustion engine 1 via the electronic controller 11,
Energize the rotation of the internal combustion engine.

The electronics controller 11 adds the electric power generated by the generator-motor 4 and the alternating-current generator 6, and performs frequency conversion of electric power for controlling the rotation of the electric motor 10.

Next, the operation of recovering energy as superheated steam by the heat exchanger 8 of the energy recovery device according to the present invention and driving the steam turbine will be described with reference to the flowchart of FIG.

First, the exhaust temperature of the exhaust turbine 5 is measured to determine the first set temperature.
It is determined whether it is higher than T _E1 (step a). When the temperature is lower than the set temperature T _{E1, the} process jumps to step m, and when it is higher, the process proceeds to step b to start the compressor 9. Next, the compressor 9 mixes air and water to form an atomized mist, and sends it to the heat exchanger 8 whose temperature has already risen by the exhaust gas to generate superheated steam (step c). Looking at the steam pressure generated at this time and the rotation speed of the steam turbine,
The control is started by setting the area of the superheated steam outlet 7b of the steam turbine 7 as an initial setting value commensurate with the exhaust temperature T _E1 .
(Steps d, e, f). In this state, the temperature T _E0 of the exhaust outlet 8b of the exhaust gas of the heat exchanger 8 is measured. When the temperature is lower than 200 ° C., the temperature returns to the original value. Step g). In steps h to l, the rotation of the compressor 9 is increased, the rotation speed of the steam pressure steam turbine 7 is checked, and the area of the steam outlet 7b of the steam turbine 7 is increased to increase the amount of steam supplied to the steam turbine 7. (Steps h, i, j, k,
l). In this way, when the exhaust temperature is equal to or higher than the first set temperature, the temperature of the exhaust port 8d is controlled to be 200 ° C. Next, the exhaust temperature is lower than T _E1 at the second set temperature T _E2 and T _E1
When located between the through T _E2 is the exhaust gas temperature in step m is is lower than the second set temperature T _E2 is the energy over recovered by the heat exchanger 8 from the exhaust gas G2 is small compressor 9, and the steam Turn off generation (step u,
w), if it is higher than T _E2 and is between T _E1 , proceed to step n and below step m). In steps n to q, the compressor 9 is driven, the pressure of the steam is observed, the area of the steam outlet 7b of the steam turbine 7 is set to an initial value, and control is started.

Next, with the amount of water vapor kept constant, the rotation of the compressor 9 is increased, the steam pressure and the rotation speed of the steam turbine are observed, and the area of the steam outlet 7b of the steam turbine 7 is increased to recover energy from the exhaust gas G2. increase.

Although the present invention has been described with reference to one embodiment, various modifications are possible within the scope of the gist of the present invention, and these modifications are not excluded from the scope of the present invention.

(Effects of the Invention) As described in detail above, in addition to the conventional energy recovery system for an internal combustion engine, the present invention extracts the energy remaining in the exhaust gas discharged from the exhaust turbine as superheated steam, It is taken out as water vapor, the steam turbine is rotated by this high-pressure water vapor, and the steam turbine drives a generator to generate electricity, and at the same time the turbocharger's motor / generator is operated as a generator. Since it is added to the generated power of the machine to recover the energy and return it to the output shaft of the internal combustion engine,
Exhaust energy that could not be recovered by the conventional exhaust heat recovery device, for example, exhaust energy in the low speed operation region of the internal combustion engine, can also be recovered, and the thermal efficiency of the internal combustion engine can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing an embodiment of an energy recovery system for a turbo compound engine according to the present invention, and FIG. 2 is a flow chart showing the operation of a heat exchanger and a steam turbine. 1 ... Internal combustion engine, 2 ... Exhaust manifold, 3 ... Turbocharger, 4 ... Generator-motor, 5 ... Exhaust turbine, 6 ... Alternator, 7 ... Steam turbine, 8 ...
… Heat exchanger, 9… Compressor, 10… Electric motor, 11…
… Electronics controller.

Claims (2)

[Claims] 1. An energy recovery apparatus for an internal combustion engine having a turbocharger, in which a motor / generator is arranged on a rotating shaft, wherein the internal combustion engine has a heat shield mechanism, and the turbocharger is provided downstream of an exhaust turbine. A turbine driven by the exhaust gas and steam, a heat exchanger that recovers heat from the exhaust gas discharged from the turbine and generates steam,
A compressor that supplies high-pressure water to the heat exchanger, a generator disposed on the rotating shaft of the turbine, and an electric motor that is attached to the output shaft of the internal combustion engine and is capable of receiving recovered power.
A control device having a unit for adding the generated power when the turbocharger motor / generator operates as a generator and the generated power of the generator disposed on the rotating shaft of the turbine. Energy recovery device for internal combustion engine. 2. The energy recovery system for an internal combustion engine according to claim 1, wherein the control device has means for controlling the amount of steam in the turbine according to the temperature of the exhaust gas.