JPH0442529B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a supercharged engine, particularly a pressure wave supercharging system in which intake air is compressed by exhaust pressure generated in an engine exhaust passage and introduced into a combustion chamber. Regarding an engine equipped with a machine.

(Prior Art) Pressure wave superchargers have been proposed for a long time, in which intake air is compressed using the exhaust pressure generated in the engine exhaust passage, and this compressed intake air is introduced into the combustion chamber. Recently, it has been attracting attention again because it has a higher supercharging effect during low-speed operation than a turbocharger using an exhaust turbine. This type of supercharger consists of a rotor having a large number of gas passages separated from each other passing through it in the direction of the rotation axis, and a case that supports the rotor so as to be rotatable around the rotation axis. An exhaust inlet, an exhaust outlet, and an intake inlet and an intake outlet are formed at opposing positions at the end, and the intake air introduced into the gas passage in the rotor from the intake inlet is introduced from the exhaust inlet. It is configured to be pushed toward the intake/discharge port by the pressure of exhaust gas. For this reason,
The exhaust gas inlet and the air intake and discharge ports are formed at positions opposite to each other in the axial direction of the rotor, sandwiching the rotor therebetween. An example of this type of pressure wave supercharger is the
It is disclosed in Publication No. 127839. In the turbocharger disclosed in this publication, an exhaust inlet and an exhaust outlet are provided on the same rotor end side, an intake inlet and an intake outlet are provided on the other rotor end side, and an exhaust This is a so-called counter-flow type, in which the air flow and the intake air flow each change direction within the rotor, but these gases flow axially through the rotor.
A flow-through type is also known, and its structure and operation are as follows:
It is detailed in the magazine "Internal Combustion Engine" Vol. 15, No. 179, June 1976.

This pressure wave supercharger is considered to be particularly suitable for diesel engines and is effective even at low speeds, but the intake air is brought into contact with the exhaust air in the rotor, resulting in partial mixing of the intake air and exhaust air. become. This mixture is called exhaust gas recirculation (hereinafter referred to as EGR).
The mixing ratio can be controlled by changing the rotation speed of the rotor.

(Object of the Invention) An object of the present invention is to focus on the phenomenon of the above-mentioned mixture of exhaust gas into the intake air that occurs in the pressure wave supercharger in an engine equipped with a pressure wave supercharger of the type described above, and to improve the rotation of the rotor. It is an object of the present invention to provide a diesel engine with a pressure wave supercharger that can effectively prevent misfires by increasing the amount of EGR during low-temperature, low-load operation by controlling the number of EGRs.

(Configuration of the present invention) In order to achieve the above object, the present invention has the following configuration. That is, the supercharged engine according to the present invention includes a pressure wave supercharger, and the pressure wave supercharger includes a rotor having a plurality of gas passages separated from each other and passing through in the direction of the rotation axis; A case that supports the rotor rotatably around its rotation axis, and the case includes an exhaust inlet connected to an engine exhaust port and an exhaust inlet connected to an engine exhaust port at a position facing the end of the rotor, and an exhaust port for discharging the exhaust gas to the atmosphere. The exhaust discharge port is formed offset in the rotor rotational direction, and an intake discharge port connected to the engine intake port is located on the opposite side of the rotation axis direction from the exhaust introduction port, and is also rotated relative to the exhaust discharge port. Air intake ports for sucking in atmospheric air are formed at positions on opposite sides in the axial direction. In the present invention, an electric motor is provided to rotationally drive the rotor of the supercharger, and the rotational speed of the electric motor is set such that the engine temperature is low and the engine is under a light load, or when the EGR amount is increased. Control the ratio to the rotation speed to a small value.

In a pressure wave supercharger, when the gas passage in the rotor opens to the exhaust inlet as the rotor rotates, exhaust pressure is transmitted to this gas passage, and a pressure wave is generated on the exhaust passage side of the gas passage. This pressure wave propagates within the passage at the speed of sound and reaches the other end while compressing the intake air within the passage. Therefore, by appropriately determining the positional relationship between the exhaust inlet and intake outlet, the length of the gas passage in the rotor, the rotor and rotation speed, etc., it is possible to transmit the pressure waves propagating in the gas passage to the intake inlet. This allows a supercharging effect to be obtained. On the other hand, the flow of exhaust gas in the gas passage advances within the passage behind the pressure waves, so if the gas passage is blocked from the intake/discharge port before the exhaust flow reaches the other end of the gas passage, the engine intake Almost no exhaust gas is mixed in.

Generally, the rotation speed of the rotor is generally increased or decreased in proportion to the engine rotation speed due to the engine intake amount. However, if the rotor speed is controlled so that the ratio of the rotor speed to the engine speed is small, for example in an engine operation region where exhaust gas recirculation is required, the exhaust flows through the gas passage and mixes with the intake air, producing the effect of increasing the amount of EGR.

(Effects of the Invention) In the present invention, the rotor of the pressure wave supercharger is driven by an electric motor, and when the engine has poor ignition performance at low temperature and under light load, the electric motor
The ratio between the rotation speed of the rotor and the engine rotation speed is controlled to be small so that the amount of EGR increases. This suppresses a decrease in intake air temperature and prevents misfires in the above-mentioned operating range. According to the present invention, in order to obtain the above-mentioned EGR characteristics, special measures are taken such as providing an EGR passage.
There is no need to install an EGR device. Also, compared to the case where the rotor is driven by the engine crankshaft,
There are no restrictions on the mounting position of the supercharger, allowing greater flexibility in component placement.

(Description of an embodiment) Basic configuration Referring to FIG. 1, an engine 1 has cylinders 2
and a cylinder head 3 attached to the upper end of the cylinder 2. A piston 4 is disposed within the cylinder 2 so as to be able to freely reciprocate, thereby forming a combustion chamber 12 within the cylinder 2. An intake port 5 and an exhaust port 6 are formed in the cylinder head 3, and an intake valve 7 and an exhaust valve 8 are arranged in the intake port 5 and the exhaust port 6, respectively. Furthermore, the intake port 5 is connected to a supercharging passage 9, and the exhaust port 6 is connected to an exhaust passage 10, respectively. A pressure wave supercharger 11 is provided between the supercharging passage 9 and the exhaust passage 10.

The supercharger 11 includes a case 14 shown in FIG. 2a,
Consisting of the rotor 15 shown in FIG. 2b, the rotor 15
is rotatably arranged inside the case 14. As shown in FIG. 2b, the rotor 15 has a number of separated gas passages 16 passing through it in the axial direction. The case 14 has end walls 14a and 14b facing both ends of the rotor 15, and one end wall 14a has an exhaust inlet 17 and an exhaust outlet 18 formed therein.
An intake inlet 19 and an intake outlet 20 are formed in the other end wall 14b. As shown in Figure 1,
An exhaust passage 10 is connected to the exhaust introduction port 17 of the case 14, and a supercharging passage 9 is connected to the intake/discharge port 20. Furthermore, the exhaust outlet 1 of the case 14
8 is connected to the exhaust passage 21, and the intake inlet 19
The intake passage 22 is connected to the intake passage 22.

A drive shaft 23 is fixed to the rotor 15, and the drive shaft 23 extends axially outward from one end of the rotor 15. The drive shaft 23 is rotatably supported by the intake housing 26 by bearings 24 and 25, and cantilever-supports the rotor 15 at one end thereof. The other end of the drive shaft 23 is connected to an electric motor 28 via an electromagnetic clutch 27.
is connected to the output shaft of the A control circuit 29 is provided to control the rotation of motor 28. This control circuit 29 receives the output of the engine rotation speed sensor 30 as an input, and generates an output proportional to the engine rotation speed. For example, if the electric motor 28 is a pulse motor, the control circuit 29 generates a pulse output whose number of pulses increases in proportion to an increase in engine speed. The output of the control circuit 29 is sent to the correction circuit 3
1, and the output of the correction circuit 31 is input to the motor 2.
Used to drive 8. The correction circuit 31 receives the operating amount of the engine control member, for example, the output of the accelerator pedal depression amount sensor 32, and compares the voltage conversion value of the engine load with the set voltage input value 35.
A signal from a light load determination circuit 36 that determines whether the engine is in a light load state is input. The correction circuit 31 corrects the output of the control circuit 29 according to the signal from the light load determination circuit 36, and controls the rotation speed of the motor 28. In this example, a water temperature sensor 38 detects the engine coolant temperature in order to detect the temperature state of the engine.
A signal from the water temperature sensor 38 is also input to the light load determination circuit 36. With such a configuration, the correction circuit 31
corrects the signal from the control circuit 29 so that the rotation speed ratio CR/ER between the supercharger rotation speed CR and the engine rotation speed ER becomes small when the engine cooling water temperature is below a predetermined temperature and the engine is under light load. . FIGS. 3A and 3B show the relationship between the engine fuel injection amount Q, the rotational speed ratio CR/ER, and the EGR amount. Figure 3A shows the case where the engine cooling water temperature is above a predetermined value, that is, after the engine has warmed up. of time
As shown by the broken line, the EGR amount changes depending on the fuel injection amount Q, that is, the engine load, and when the load is low, a small amount of EGR is performed.

In addition, Figure 3B shows the case where the engine coolant temperature is below a predetermined value, that is, during warm-up, and the above rotation speed ratio CR/ER is, as shown by the solid line in the figure, when the engine load is low. Sometimes it is smaller than when the load is high, and the EGR amount at this time is larger than in the case of FIG. 3A, as shown by the broken line in the same figure. The output of the accelerator depression amount sensor 32 is also applied to the electromagnetic clutch 27, so that the clutch 27 is disconnected in a load range smaller than a certain load.

Operation In the load range where the engine 1 is started and the clutch 27 is engaged, the motor 28 is
The rotor 15 is rotated by the output from the rotor 15. Engine intake air enters the gas passage 16 in the rotor 15 from the intake passage 22 through the intake inlet 19, and when the passage 16 opens to the intake discharge port 20, it is discharged into the supercharging passage 9 and is combusted from the intake port 5. is introduced into chamber 12. On the other hand, the exhaust gas discharged from the exhaust port 6 passes through the exhaust passage 10 to the exhaust introduction port 1.
The gas enters the gas passage 16 in the rotor 15 from 7, and is discharged into the exhaust passage 21 when the passage 16 opens to the exhaust discharge port 18. In the case 14, the exhaust inlet 17 and the intake outlet 20 are arranged at positions facing each other in the axial direction, so when one end of the gas passage 16 opens to the exhaust inlet 17, the pressure generated in the passage 16 is reduced. The waves propagate in the passage 16 and reach the intake air outlet 20 while compressing the intake air in the passage 16, and discharge the intake air into the passage 9 in a supercharged state.

FIG. 4 schematically shows the flow of intake and exhaust air in the passage 16 of the rotor 15. As shown in FIG. In the figure, the rotor 15 is shown unfolded for convenience of explanation, and the passage 16 moves from top to bottom in the direction indicated by arrow A as the rotor 15 rotates. Fourth
The passage 16a near the upper end of the figure has moved in a state filled with intake air, and since both ends of the passage are closed at the position of this passage 16a, the intake air inside is in a stationary state. One end of the continuing passage 16b opens to the exhaust gas introduction port 17, and pressure waves due to exhaust gas are generated as shown at 33 in the figure. At this time, the exhaust gas is flowing into one end of the passage 16b as shown at 34. In the passages 16c and 16d whose phase is advanced in the rotation direction of the rotor 15, pressure waves propagate as shown by 38a and 33b, and the exhaust flow also advances along the passages as shown by 34a and 34b, but at this point In this case, the other end of the passage is closed and the intake air near that end is stationary. Furthermore, the end of the passage 16e opens to the intake/discharge port 20, and at this point the pressure wave has reached the intake/discharge port 20, and the intake air is discharged into the passage 9 in a supercharged state. In the following passages 16f, 16g, and 16h, the intake air is continuously discharged, and the exhaust gas flows in the passages in the outflow direction of the intake air. The passage 16i is blocked from the exhaust gas introduction port 17, and an exhaust stationary portion 34c is created at the end on the side of the gas introduction port 17. The passage 16j is the intake outlet 2
It is also cut off from zero, and the intake and exhaust are in a stationary state. One end of the passage 16k opens to the exhaust discharge port 18, and an exhaust expansion part 35 is provided at the end.
occurs, and this expanded portion expands within the passage as the phase advances, as shown in the figure. aisle 16
1, the other end side opens to the intake inlet 19, atmospheric pressure air flows into the passage, and the expanded exhaust gas is pushed out to the exhaust passage 21.

At the rotational speed of the rotor 15 shown in FIG.
The passage 16 is blocked off from the intake outlet 20 before the exhaust gas flowing into the intake outlet 6 reaches the intake outlet 20.
Therefore, the exhaust gas does not reach the supercharging passage 9 except for a small amount that remains after coming into contact with the intake air. FIG. 5 shows a case where the rotational speed of the rotor 15 is relatively lowered and the ratio between the rotor rotational speed and the engine rotational speed is reduced. In this state, the flow of the exhaust gas 34 is faster than the progress of the gas passage 16 due to the rotation of the rotor 15.
The exhaust gas 34 reaches the discharge port 20 before the passage 16 is blocked from the intake discharge port 20 and is discharged into the supercharging passage 9.

The amount of exhaust gas discharged into the supercharging passage 9 in this way changes depending on the ratio between the rotation speed of the rotor 15 and the engine rotation speed, and this rotation speed ratio is changed as shown by the solid line in FIG. 3B. As a result, the amount of exhaust gas mixed into the intake air changes as shown by the broken line in the figure. That is, by controlling the rotation speed of the pressure wave supercharger, it is possible to substantially control the EGR amount to a desired state. In this example, when the engine cooling water temperature is lower than a certain value in a region where the fuel injection amount is relatively small, that is, in a light load region, the rotation speed ratio CR/ER between the supercharger rotation speed and the engine rotation speed is small. It is controlled so that a large amount of EGR can be obtained.
This suppresses a decrease in intake air temperature, improves ignition performance, and prevents misfires. Also,
In a high-load operation region, a high supercharging effect can be obtained by increasing the rotational speed ratio CR/ER to prevent exhaust gas from being mixed into the intake air as shown in FIG.

Note that in a low-load operating range, the clutch 27 may be disengaged in response to a signal from the sensor 32, and the rotor 15 may be driven only by exhaust energy. Further, although the above-mentioned embodiments are of the reverse flow type, the present invention can also be applied to a once-through type without any problems.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a supercharged engine showing an embodiment of the present invention, Fig. 2 a and b are perspective views showing the case and rotor of the supercharger, respectively, and Fig. 3 A
and B is a diagram showing an example of rotor rotation speed control,
4 and 5 are exploded views of the rotor showing the action of the supercharger. 1...Engine, 9...Supercharging passage, 10...Exhaust passage, 11...Supercharger, 14...Case, 15
...Rotor, 16...Gas passage, 17...Exhaust inlet, 18...Exhaust discharge port, 19...Intake inlet, 20...Intake discharge port, 28...Electric motor, 29...Control circuit.

Claims (1)

[Claims] 1 Consisting of a rotor having a large number of gas passages separated from each other passing through in the direction of the rotation axis, and a case that supports the rotor rotatably around the rotation axis, and the case includes a rotor at the end of the rotor. An exhaust inlet port connected to the engine exhaust port and an exhaust discharge port for discharging exhaust gas into the atmosphere are formed at opposite positions, offset in the rotor rotation direction, and further on the opposite side in the rotational axis direction with respect to the exhaust inlet port. Pressure wave supercharging of a type in which an intake discharge port connected to the engine intake port is formed at a position, and an intake inlet port for sucking atmospheric air is formed at a position opposite to the exhaust discharge port in the rotation axis direction. In a supercharged diesel engine equipped with an electric motor for rotationally driving the rotor, the ratio between the rotation speed of the rotor and the engine rotation speed is reduced when the engine temperature is low and the engine is under a light load. A supercharged engine characterized by being provided with a control device.