JPS60159337A - Engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent a misfire from occurring without fail, by installing a throttle valve, which is throttled in times of engine cooling and light load, in a suction passage, in case of an engine provided with a supercharger inclusive of a rotor having a lot of gas passages piercing through in a turning axial direction. CONSTITUTION:When an engine 1 is started, a motor 28 is rotated by output of a control circuit 29, turning a rotor 15 of a supercharger 11. If so, suction air flows in a gas passage 22, and discharged to a supercharging passage 9 when the said passage 6 is opened to a suction discharge port 20, thus led into a combustion chamber 12. On the other hand, exhaust out of an exhaust port 6 is discharged to an exhaust passage 21 by way of each routes 10-17-16-18. At this juncture, when a fact that the engine is in a state of low termperature and light load operation is detected by a control circuit 38 from each output of a water temperature sensor 39 and an accelerator step-on operation sensor 32, a selector valve 37 is changed over, and a throttle valve 22a installed in the suction passage 22 is controlled so as to be throttled by a diaphragm device 35.

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 rotor axial direction with the rotor sandwiched therebetween. An example of this type of pressure wave supercharger is the Utility Model 55-727g.
, No. 39. 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 The exhaust and intake air flows each change their flow direction within the rotor, so-called counter-flow type, but these gases are made to flow through the rotor in the axial direction.

- A once-through type is also known, and its structure and operation are described in the magazine "Internal Combustion Engine J Vol, /j, Ha/79. /97
&, l, are detailed.

This pressure wave supercharger is considered to be particularly suitable for diesel engines and is effective even at low speeds, but because the intake air is brought into contact with the exhaust air in the rotor, partial mixing of the intake air and exhaust air occurs. become.

This mixing can be seen as an exhaust gas recirculation (hereinafter referred to as EGR) effect, and the mixing ratio can also be controlled by changing the pressure balance between the intake and exhaust air that sandwich the supercharger.

(Object of the Invention) The object of the present invention is to focus on the phenomenon of exhaust gas being mixed into the intake air that occurs inside the supercharger in an engine equipped with a pressure wave supercharger of the type described above, and to By changing the pressure balance between intake and exhaust air, the EGR effect is exerted and the amount of EGR is controlled to improve ignition performance when the engine is operating at low temperatures and under light load, thereby effectively preventing misfires in such operating ranges. An object of the present invention is to provide a diesel engine with a pressure wave supercharger that can prevent pressure waves from occurring.

(Structure of the 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, a throttle valve is provided in the intake passage on the E flow side of the supercharger or in the exhaust passage downstream of the supercharger, and the throttle valve is controlled to be throttled when the engine is operated at low temperature and under light load. .

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, creating a pressure wave on the exhaust passage side of the gas passage. This pressure wave is generated and propagates within the passage at the speed of sound, compressing the intake air in the passage before reaching the other end. Therefore, by appropriately determining the positional relationship between the exhaust inlet and intake outlet, the length of the gas passage in the rotor, the rotation speed of the rotor, etc., it is possible to transmit the pressure waves propagating in the gas passage to the intake inlet. and supercharging effect can 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 Exhaust air hardly gets mixed in. In this way, in order to prevent exhaust air from mixing with the intake air, it is necessary to maintain a constant pressure between the intake and exhaust air (under a lance, the rotor length, rotor rotation speed, intake and exhaust outlet ports, and the position of the inlet port). This can be achieved by appropriately determining the relationships, etc., but conversely, when trying to utilize the above-mentioned contamination phenomenon, that is, the EGR effect, contamination can be caused by appropriately changing the conditions mentioned above. In the present invention, by changing the pressure balance between the intake air and the exhaust air, effective use of the phenomenon of the above-mentioned exhaust air being mixed into the intake air is achieved.That is, In the present invention, when the engine is operating at a low temperature and under a light load, the pressure of the intake air introduced into the supercharger is lowered relative to the pressure of the exhaust air discharged from the supercharger by appropriately throttling the above-mentioned throttle valve. Control as follows.

This allows the mixing ratio, that is, the EGR3l, to be increased in the above operating range. The throttle valve as a means for changing the pressure balance of intake and exhaust may be provided in either the intake passage or the exhaust passage, or may be provided in both. If both throttle valves are provided, at least one throttle valve may be throttle-controlled. In addition, a communication passage is installed to connect the intake passage downstream of the turbocharger, that is, the supercharging passage, and the intake passage of the turbocharger E flow and the intake passage of the flow. Effective EGRi
can be increased. Although the rotary power of the engine crankshaft can be used as a means for rotationally driving the rotor, preferably, an electric motor is used to drive the rotor.

(Effects of the Invention) According to the present invention, when an engine with poor ignitability is at low temperature and under light load, the L throttle valve is throttled, and the intake pressure is lowered relative to the exhaust pressure. This increases the proportion of exhaust gas mixed into intake air, suppresses a drop in intake air temperature, and prevents misfires in the above-mentioned operating range. Furthermore, in the EGR control according to the configuration of the present invention, the supercharger itself
It has a function as an EGR passage for the GR control device, so there is no need to provide a special EGR passage.

(Description of an Embodiment) Basic Configuration Referring to FIG. 1, a diesel engine 1 has a cylinder 2 and a cylinder head 3 attached to the L end of the cylinder 2, and a piston 4 moves reciprocatingly within the cylinder 2. They are arranged freely to form 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 T 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 1 roller 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. 2(a) and a second
It consists of a rotor 15 shown in Figure (b), and the rotor 15 is rotatably arranged within the case 14. Figure 2(b)
As shown in K, the rotor 15 has a number of gas passages 16 that are separated from each other and extend through the rotor 15 in the axial direction. Case 14 is
The rotor 15 has end walls 14a and 14b facing each other at both ends, and one end wall 14a has an exhaust inlet 1T and an exhaust outlet 1.
8 is formed, and an intake inlet 19 is formed in the other end wall 14t).
An intake/discharge port 20 is formed. As shown in FIG. 1, an exhaust passage 10 is connected to the exhaust introduction port 11 of the case 14, and a supercharging passage 9 is connected to the intake and discharge port 20. Further, an exhaust passage 21 is connected to the exhaust outlet 18 of the case 14, an intake passage 22 is connected to the intake inlet 19, and an intake throttle valve 22a is disposed within the intake passage 22.

A drive shaft 23 is fixed to the rotor 15, and this drive shaft 23
extends axially outward from one end of the rotor 15. The drive shaft 23 is rotatably supported in the intake housing 26 by bearings 24, 25, and cantilevers the rotor 15 at one end thereof.

The other end of the drive shaft 23 is coupled to the output shaft of the electric motor 2B via an electromagnetic clutch 27. A drive circuit 29 is provided to control the rotation of motor 2B. This drive circuit 29 receives the output of the engine rotation speed sensor 30 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.

A diaphragm device 35 is provided to control the opening degree of the throttle valve 22a, and the diaphragm 35 of the device 35
a partitions the casing 35b into a negative pressure chamber 35c and an atmospheric chamber 35d communicating with the atmosphere, and is fixed to an operating member 35e of the throttle valve 22a, forming a trap so as to be interlocked with the member 35e.

A spring 35f is disposed in the negative pressure chamber 35c of the diaphragm device 35 to apply a pressing force to the diaphragm 35aK, and a switch is installed in the negative pressure chamber 35c to switch communication between the chamber 35c and the atmosphere or the vacuum pump 36. Connected to valve 3T.

The switching valve 37 is a solenoid valve, and a control circuit 38 is provided to control the operation of the switching valve 3T. Actuation amount of sensor 39 and engine control member 35e, for example accelerator depression amount sensor 3
2 and outputs a switching signal to the switching valve 3T.

When the engine is cold and the load is light, selector valve 3T
The solenoid is excited by a signal from the control circuit 38, and at this time the switching valve 37 communicates the negative pressure chamber 35c of the diaphragm device 35 with the vacuum pump 3T.

When the switching valve 3T communicates the atmosphere with the negative pressure chamber 35c, the diaphragm 35a is moved to the right in the figure, the throttle valve 22a is fully open, and the switching valve 3T is connected to the vacuum pump. 36 and the negative pressure chamber 35c, the diaphragm 35a moves to the left in the figure against the pressing force of the spring 35f, and the operating member 35e
By moving the throttle valve 22a to the left, the throttle valve 22a becomes half-open and a throttle state is achieved, thereby reducing the intake pressure introduced into the supercharger 11. Note that the output of the accelerator depression amount sensor 32 is also given to the electromagnetic clutch 2T, so that the clutch 2T is disconnected in a load range smaller than a certain load.

Operation In a load range where the engine 1 is started and the clutch 21 is connected, the motor 2B is rotated by the output from the drive circuit 29 at a rotational speed approximately proportional to the engine rotational speed, thereby driving the rotor 15. Engine intake air enters the gas passage 1eK in the rotor 15 from the intake passage 22 through the intake inlet 19, and when the passage 1B opens to the intake discharge port 20, it is discharged into the supercharging passage 9 and from the intake port 5 into the combustion chamber. 1
2 will be introduced. On the other hand, the exhaust gas discharged from the exhaust port 6 passes through the exhaust passage 10 and exits from the exhaust introduction port 1T to the rotor 15.
The gas passage 16 enters the inside, and the passage 16 connects to the exhaust outlet 18
When it opens, it is discharged into the discharge passage 21. case 14
In this case, since the exhaust inlet 17 and the intake outlet 20 are disposed in positions facing each other in the axial direction, when one end of the gas passage 1B opens to the exhaust inlet 1T, a pressure wave is generated in the passage 16. propagates in the passage 16, reaches the intake air outlet 20 while compressing the intake air in the passage 16, and discharges the intake air into the passage B in a supercharged state.

FIG. 3 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 is assumed to move downward in the direction indicated by arrow A as the rotor 15 rotates. The passage 16a near the end in FIG. 3 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 1T, 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 passage 16C, fed, whose phase is advanced in the rotational direction of the rotor 15, the pressure wave is 3
It propagates as shown at 3a and 33b, and the exhaust flow also flows at 34a.
, 34b, the other end of the passage is closed at this point, and the intake air near the 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 8 in a supercharged state. Continuing passages 16f, 16g, 16h
In this case, the intake air continues to be discharged, and the exhaust gas flows in the passage in the outflow direction of the intake air. The passage 16i is blocked from the exhaust gas introduction port 1T, and an exhaust stationary portion 34c is created at the end on the side of the gas introduction port 17. The passage 161 is also blocked off from the intake and discharge ports 20, so that intake and exhaust are in a stationary state. In the passage 16, one end of the passage opens to the exhaust discharge port 1B, and an expansion part 35 of exhaust gas is generated at the end, and this expansion part expands within the passage as the phase advances as shown in the figure. . The other end of the passage 16o opens into the intake port 19, and atmospheric pressure air flows into the passage, pushing out the expanded exhaust gas into the exhaust passage 21.

In the intake/exhaust pressure balance state shown in FIG. 3, the passage 16 is blocked from the intake/discharge port 20 before the exhaust gas flowing into the passage 16 reaches the intake/discharge port 20. Therefore, the exhaust gas does not reach the supercharging passage 9 except for a small amount that remains after being mixed into the intake air due to contact with the intake air. FIG. 7 shows a diagram in which the throttle valve 22a of the intake passage 22 is set in a half-open state to throttle the passage, thereby changing the pressure balance between intake and exhaust air in the case explained in FIG. Indicates a case where it is forced. In this case, since the pressure difference between the intake and exhaust air is larger than in the case of FIG. The fuel reaches the supercharging passage 9 and is discharged into the supercharging passage 9. In this way, the amount of exhaust gas discharged into the supercharging passage 9 changes depending on the pressure balance between the intake air introduced into the supercharging 4 (A11) and the exhaust gas discharged from the supercharger 11. Controlling K than EGR
The amount can be controlled. In this example, in the region where the fuel injection amount is relatively small, that is, in the light load region, the engine cooling water temperature is reduced below a certain value, so the supercharging mode 1
The intake pressure introduced into the engine 1 decreases and the EGR amount increases.

This suppresses a decrease in intake air temperature, improves ignition performance, and prevents misfires. Finally, in the high-load operating range, the throttle valve 22a is fully opened, so that the mixture of exhaust gas into the intake air is suppressed and a high supercharging effect is obtained.

FIG. 5 shows another embodiment of the present invention, in which an exhaust throttle valve 21a is provided in the exhaust passage 21 on the downstream side of the supercharger 11 instead of the intake throttle valve 22a. There is.

The exhaust throttle valve 21a is controlled by the same control mechanism as in the previous example to be opened half-open to throttle the exhaust passage when the engine is at low temperature and under light load. Accordingly, the exhaust pressure is increased relative to the intake pressure, and the same effect as in the previous example can be obtained. In addition, in this example, past opportunity 1
The drive shaft 23 of the rotor 15 of No. 1 has a pulley 42ν! The boot 1J42 is fixedly connected to a pulley (not shown) on the engine crankshaft via a belt. Therefore, the rotor 15 is driven by the rotational power of the engine crankshaft, and its rotational speed is proportional to the engine rotational speed.

FIG. 6 shows yet another embodiment of the present invention, in which an intake throttle valve 22a is provided, and
A supercharging intake return passage 40 is provided that connects the upstream intake passage 22 of the supercharger 11 and the supercharging passage 9, and the passage 40 includes:
A throttle valve 4θa that changes the flow area of the core passage 40 is provided.

Although the throttle valves 22a and 40a are controlled by one diaphragm device 35, the throttle valves 22a and 40a are
When the throttle valve 2a is fully open, the throttle valve 40aa is fully closed, and when the throttle valve 22a is half open, the throttle valve 408 is fully open.

In the structure of this example, when the engine is operated at a low temperature and under a light load, the intake passage 22 is narrowed and a portion of the supercharged intake air mixed with exhaust gas from the supercharger is transferred to the intake air before being introduced into the supercharger. Therefore, the amount of EGR can be increased more effectively.

Further, in the embodiments described below, the throttle valve is provided in either the intake passage or the exhaust passage, but it may be provided in both.

In addition, in the low-load operation region, the rotor 15 may be driven only by exhaust energy for 5K. Further, although the embodiment described in E is a reverse flow type, the present invention can also be applied to a once-through type without any problem.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a supercharged engine showing an embodiment of the present invention, FIGS. 2(a) and (b) are perspective views showing the case and rotor of the supercharger, and FIGS. 1 is a developed view of the rotor showing the action of the supercharger, FIG. S is a diagram similar to FIG. 1 according to another embodiment of the present invention, and FIG. FIG. 2 is a diagram similar to FIG. 1; DESCRIPTION OF SYMBOLS 1... Engine, 9... Supercharging passage, 10... Exhaust passage, 11... Supercharger, 14... Case, 15...
- Rotor, 16... Gas passage, 17... Exhaust inlet, 1B... Exhaust discharge port, 19... Intake inlet. 20... Intake/discharge port, 2nd... Electric motor, 29
...Control circuit. Figure 3 - Figure 4

Claims (1)

[Claims] It 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 rotatably around the rotation axis, and the case includes a rotor that is opposite to 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 a position offset in the rotor rotation direction, and an A pressure wave supercharger of a type in which an intake discharge port connected to an 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 the turbocharged diesel engine, a throttle valve is provided in the intake passage for the supercharger flow or in the exhaust passage downstream of the supercharger, and the throttle valve is throttled when the engine is at low temperature and when the engine is under light load. A supercharged engine characterized by being equipped with a control device.