JPH0211722B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust energy recovery device for an engine.

(Prior Art) A gasoline engine or a diesel engine, which is an internal combustion engine, generates power by pushing down a piston using energy generated by burning fuel in a cylinder. Then, the exhaust gas generated by combustion within the cylinder is directly discharged from the exhaust manifold toward the outside air. This exhaust gas is at high temperature and pressure and still retains considerable energy.

(Problem to be Solved by the Invention) Recently, a system has been announced that attempts to recover high energy remaining in the exhaust gas emitted from an internal combustion engine and return it to the crankshaft to improve operating efficiency. , is described in Japanese Utility Model Application Publication No. 57-89828.

In the system described in this publication, a turbine rotated by exhaust gas is placed near the exhaust port, and the surplus rotational power obtained from this turbine is reduced by speed conversion using multi-stage gears, and the crank This is to return it to the axis.

Such devices have the drawback that the overall structure of the energy recovery device is complex and the transmission light rate is poor, which not only makes the overall price of the internal combustion engine expensive, but also does not have very good operating efficiency, and cannot be used under partial load. However, it is not very effective.

Another method described in the publication is that a turbine rotated by exhaust gas is disposed near the exhaust port, and the rotational force obtained from this turbine is used to rotate a generator. The electric power obtained from the machine rotates an electric motor connected to the crankshaft, and the recovered energy is returned to the crankshaft.

In such a device, not only is the overall structure of the energy recovery device complex, but also the electric power obtained from the generator is applied to the electric motor without a control device, making it impossible to control the generator and electric motor, making it impossible to implement. It is something.

Further, a field-controlled generator including a turbine rotationally driven by an exhaust gas flow discharged from the engine, a field-controlled motor rotated by electric power generated by the generator, and a controller that is connected to the engine and controls the rotation of the motor according to the engine speed detected by the engine speed detector; and a controller that is interposed between the motor and the engine and controls the rotational force of the motor to the engine. and an electromagnetic clutch whose intermittent transmission is controlled by the controller.The exhaust gas energy is converted into electrical energy by a turbine and a generator, and the electrical energy is transferred back into (mechanical rotation) motion by a motor. An exhaust energy recovery device that converts energy into energy and uses the kinetic energy to drive an engine has been developed.
It is described in Publication No. 58-30727 (filed in Utility Model Application No. 124309/1983).

However, as is clear from the description in the publication, the generator of the exhaust energy recovery device described in the publication is a generator of a type that controls the amount of power generated by controlling the field current, and the rotor Winding wire is used in Therefore, when the rotor is rotated at high speed by the turbine, parts such as the windings that make up the rotor are crushed into fine particles by the large centrifugal force generated by the high speed rotation of the turbine, making them unusable.

In addition, the system described in this publication detects the engine rotation speed and uses this rotation speed to control the motor armature voltage and field current, and at the same time controls the generator field current. The engine rotation speed detector is not only essential for this device, but also has the disadvantage that the control circuit becomes complicated.

Furthermore, in the system described in the publication, a clutch is interposed between the motor and the rotating shaft of the engine, and the on/off control of this clutch is also performed by a control circuit, so the configuration of the control circuit is It also has the disadvantage of becoming more complex.

The present invention aims to improve these conventional drawbacks, and its purpose is to efficiently recover the energy held in the exhaust gas of an internal combustion engine and efficiently return it to the crankshaft. In addition, even if the generator is directly connected to the turbine, it will not be destroyed even if it is rotated at high speed, and the generator and motor field control, engine rotation speed detection,
It is an object of the present invention to provide an exhaust energy recovery device that can efficiently control the entire device without taking any means such as clutch control or providing a clutch.

(Means for Solving the Problems) An alternator has a rotating shaft directly connected to the turbine shaft of an exhaust turbine, and the rotating shaft is provided with a rotor made of permanent magnets, and an alternator is connected to the rotating shaft of an engine. a rectifier for inputting AC power obtained from the alternator, converting it into DC power and outputting it, and allowing the power to pass only from the input side to the output side; An engine exhaust energy recovery device comprising: a control device that prevents power from being supplied to an electric motor in excess of a rated value.

(Function) The device of the present invention rectifies AC power generated by an AC generator connected to the turbine shaft of a turbine driven by engine exhaust gas and supplies it to a DC motor. The rectified electric power is adjusted to control the DC motor to operate under optimal load conditions that always provide the rated output.

When idling, etc., when exhaust gas emissions are low and there is no power supplied from the AC generator to the DC motor, the engine rotates the DC motor, and the DC motor temporarily becomes a DC generator to generate electricity. Since the rectifying means that generates the electric power prevents the electric power from flowing back toward the alternator, the DC motor simply idles and does not become a load on the engine.

(Example) Next, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a block diagram of the present invention.

In the figure, 1 is an adiabatic type engine. As mentioned above, this engine is of a heat-insulating type using ceramics for the cylinder liner, cylinder head heat insulating plate, exhaust valve, piston, etc.

2 is an exhaust manifold, the outer wall of which is made of ceramics and has a heat insulating structure. An exhaust turbine 3 is connected to the tip of the exhaust manifold 2. Reference numeral 3a denotes a turbine vortex chamber, in which a turbine blade 3b is rotatably disposed.

Reference numeral 4 denotes a high-pressure alternating current generator, the rotating shaft of which is directly connected to the turbine shaft 3c of the exhaust turbine 3.
The alternator 4 has a rotor made of permanent magnets,
This is a two-pole alternator with an armature winding on the fixed side. This alternator 4 is driven by the exhaust turbine 3 at a maximum rotation speed of about 100,000 times per minute, so the rotor is thin and long in the direction of the rotation axis, and the centrifugal The force is minimized to prevent rotor damage. In addition, since this alternator 4 rotates at high speed, it is suitable for use in automobiles at a high voltage of approximately 200 V and a frequency of approximately
Generates an AC voltage of about 3.5KHz.

5 is a converter composed of a thyristor bridge. The converter 5 is turned on by a pulse signal applied to the gate terminal, rectifies the alternating current generated by the alternator 4, converts it into direct current (pulsating current), and converts the alternating current generated by the alternating current generator 4 into direct current (pulsating current).
It allows passage only in that direction. The power supplied to the DC motor 7 can be changed by changing the application timing of the pulse signal. By the way, the thyristor constituting this converter 5 is a high frequency thyristor that operates satisfactorily even at a frequency of about 3.5 KHz.

A gate control circuit 6 controls a pulse signal applied to the thyristor gate terminal of the converter 5.

Reference numeral 7 denotes a DC motor, the rotating shaft of which is connected to the rotating shaft 1a of the engine 1 via two gears 7a and 7b. The DC motor 7 is preferably a DC direct-wound motor that operates at approximately the same rotation speed as the engine 1.

8 is a current detector that detects the drive current of the DC motor 7.

Next, the operation of the present invention will be explained.

When the engine 1 starts rotating and high-temperature exhaust gas is discharged from the exhaust turbine 3, the turbine blades 3b of the exhaust turbine 3 start rotating, the alternator 4 is driven, and power generation starts. Initially, the gate control circuit 6 widens the gate of the thyristor constituting the converter 5 and attempts to supply the electric power generated by the alternating current generator 4 to the DC motor 7 to drive it, but the rotation speed of the exhaust turbine 3 increases. Since the output voltage of the AC generator 4 is small, the output voltage of the AC generator 4 is also small and cannot drive the DC motor 7.

On the other hand, the DC motor 7 is rotated by the engine 1 and acts as a generator to generate DC voltage. The electric power generated by the DC motor 7 flows backward through the converter 5 and tends to flow toward the AC generator 4. However, the gate control circuit 6
Since the gate is controlled so that the DC motor 7 is in a "powering" state, that is, power is supplied in the direction of the DC motor 7, the power generated by the DC motor 7 does not flow backwards. Further, since no load that should consume the generated power is connected to the DC motor 7, there is no need to apply a braking force to the rotating shaft 1a of the engine 1.

Note that the voltage generated at the cathode of the thyristor by the electric power generated by the DC motor 7 at this time is set to be equal to or lower than the breakover voltage of the thyristor.

When the rotational speed of the engine 1 gradually increases, the amount of exhaust gas increases, and its temperature also increases, the output voltage of the alternator 4 also increases, and finally the DC motor 7 is driven. Since the DC motor 7 drives the rotating shaft 1a of the engine 1 in a direction that increases its output, the energy contained in the exhaust gas is recovered and fed back to the rotating shaft of the engine 1.

The current detector 8 always detects the current supplied to the DC generator 7, and based on this signal, the gate control circuit 6 controls the gate of the thyristor to constantly control the current supplied to the DC motor 7, which generates the rated output. Since electric power is supplied so that the engine speed changes, the DC motor 7 is driven and controlled under the optimum load condition, that is, the rated output condition.

Furthermore, if an excessive load is applied to the DC motor 7 for some reason and a current exceeding the rated value attempts to flow, the current detector 8 detects this and the gate control circuit 6 throttles the gate of the thyristor of the converter 5. The current is suppressed and controlled so that the DC motor 7 can always be driven under the above-mentioned optimum load conditions.

With this type of circuit configuration, the entire circuit can be configured with a high-voltage circuit system, resulting in less loss compared to the 12V or 24V circuit configurations normally used in automobiles.

FIG. 2 is a block diagram showing a second embodiment of the present invention, and the same parts as in FIG.

In FIG. 2, 15 is a rectifier circuit in which silicon rectifier elements are bridge-coupled. A switching regulator 18 controls the duty of the DC output current supplied from the rectifier circuit 15 to the DC motor 7, stabilizes the DC output current, and drives the DC motor 7 efficiently and stably. It works like this.

In the operation of this embodiment, the alternating current generated by the alternator 4 is directly rectified by the rectifier circuit 15. Since the voltage of the output of the rectifier circuit 15 fluctuates rapidly, it is first input to the switching regulator 18, stabilized, and then applied to the DC motor 7.

As a modification of this embodiment, a voltage booster is provided at the output end of the AC generator 4, and a rectifier circuit 15 and a regulator 18 are arranged near the DC motor 7 to boost the output voltage of the AC generator 4. After the voltage is further boosted by the device, the voltage may be rectified by the rectifier circuit 15, and then converted by the regulator 18 to an optimal voltage for the DC motor, and the DC motor 7 may be driven.

(Effects of the Invention) As described in detail above, in the engine exhaust energy recovery device according to the present invention, the rotating shaft is directly connected to the turbine shaft of the exhaust turbine, and the rotating shaft includes a rotor made of permanent magnets. The AC generator provided, the DC motor coupled to the rotating shaft of the engine, and the AC power obtained from the AC generator are input, and this is converted to DC power and output, from the input side to the output side. The rectifying means that allows power to pass only to Engine exhaust energy can be smoothly and easily recovered without controlling magnetism, without needing a means to measure engine speed, and without installing a clutch between the DC generator and the engine. It is possible.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a configuration diagram showing another embodiment. 1...Engine, 2...Exhaust manifold, 3
...exhaust turbine, 4...alternator, 5...converter, 6...gate control circuit, 7...DC motor, 8...current detector.

Claims (1)

[Claims] 1. An alternating current generator whose rotating shaft is directly connected to the turbine shaft of an exhaust turbine, and the rotating shaft is provided with a rotor made of permanent magnets, a direct current motor coupled to the rotating shaft of the engine, and the alternating current generator. A rectifier that inputs AC power obtained from the machine, converts it to DC power, and outputs it, allowing the power to pass only from the input side to the output side, and the rating of the power supplied from the rectifier to the DC motor. An engine exhaust energy recovery device comprising: a control device that prevents the above supply.