JPH0571775B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention utilizes the energy of engine exhaust gas to generate pressure waves, and causes this pressure wave to act on the intake air to increase the pressure of the intake air. The present invention relates to an engine equipped with a pressure wave supercharger that supplies intake air to the engine.

[Prior Art] Conventionally, a rotor is rotatably supported within a case and has a large number of partition walls radially arranged to form a large number of small chambers, an air intake inlet formed in the case at one end of the rotor, and a rotor. The rotor includes an intake discharge port, an exhaust inlet port and an exhaust discharge port formed in the case on the other end side of the rotor, and supercharges the intake air by transmitting the pressure wave energy of the exhaust gas to the intake air as the rotor rotates. A pressure wave supercharger has been proposed (for example, see Japanese Patent Application Laid-open No. 157914/1983).

This type of pressure wave supercharger is different from conventionally used turbo superchargers in that it can directly exchange energy between exhaust and intake air, so it has high energy utilization efficiency. It is said that once a certain amount of displacement is secured, intake supercharging can be performed immediately, improving supercharging performance in the low speed range and responding to engine load fluctuations with good responsiveness. There are advantages.

In particular, since diesel engines have a large displacement in principle and are advantageous for this type of pressure wave supercharger, their commercialization is being pursued.

On the other hand, in this type of diesel engine,
When idling or operating at extremely low load in the vicinity,
If intake is performed without limit, the amount of work in the compression stroke will increase and the required output may not be obtained. Therefore, an on-off valve (intake shutter valve) is installed in the intake passage to open and close this passage. When operating as above, the on-off valve downstream should be
It becomes necessary to maintain a negative pressure of about 100 to 150 mmHg, thereby limiting the substantial intake air amount.

In addition, in a normal spark ignition engine, a throttle valve is installed in the intake passage, and the amount of intake air is controlled by controlling the opening degree of this throttle valve according to the engine load. There is.

[Object of the Invention] An object of the present invention is to provide an engine structure that does not obstruct the necessity of limiting or controlling the intake air amount as described above when putting the pressure wave supercharger as described above into practical use. .

[Structure of the Invention] Therefore, in the present invention, the intake passage downstream of the intake discharge port is provided with a first on-off valve that closes at least during startup, and the intake passage downstream of the first on-off valve and the intake passage upstream of the intake inlet are connected. A bypass passage is provided which communicates with the first on-off valve to bypass the pressure wave supercharger when the first on-off valve is closed and allows intake air to flow to the intake passage downstream of the first on-off valve. The basic feature is that a second on-off valve is provided to substantially control the intake air amount when the load is extremely low in the vicinity.

The second on-off valve that substantially controls the intake air amount is
For diesel engines, this is an intake shutter valve that generates a negative intake pressure of about 100 to 150 mmHg in the intake passage during idling or extremely low load operation; spark ignition engines (gasoline engines)
In this case, it is a throttle valve that opens and closes in response to negative pressure.

[Effects of the Invention] According to the present invention, a second on-off valve is provided in the intake passage downstream of the bypass passage, and by generating a negative pressure of about 100 to 150 mmHg during idle or extremely low load operation, work during the compression stroke is reduced. without reducing the amount
In addition to ensuring the necessary output, the intake passage upstream of the second on-off valve can be maintained at positive pressure, so exhaust gas from the pressure wave supercharger is not carried out to the intake side, and when the engine is started, Since the first on-off valve is closed and intake air is supplied through the bypass passage, exhaust gas is not brought into the intake side via the pressure wave supercharger, and startability can be effectively ensured.

Also, if we consider the case where an on-off valve is installed in the intake passage upstream of the pressure wave supercharger, in that case, the exhaust inlet side of the pressure wave supercharger becomes negative pressure, and due to the influence of this negative pressure, A large amount of exhaust gas mixes into the intake air, making it impossible to control the amount of intake air and impairing combustibility. However, according to the present invention, there is no such fear.

[Example] Hereinafter, an example of the present invention will be specifically described based on the attached drawings.

The diesel engine 1 shown in FIG. 1 sucks air supplied from an intake passage 5 into a combustion chamber 4 when an intake valve 2 opens an intake port 3, compresses the intake air as a piston 6 rises, and fuels the combustion chamber 4. It has a basic structure in which fuel supplied from an injection valve 7 is ignited and burned, and when an exhaust valve 8 is opened, exhaust gas is discharged from an exhaust port 9 to an exhaust passage 10.

A pressure wave supercharger 11 is provided across the intake passage 5 and exhaust passage 10 of the diesel engine 1, and the pressure wave supercharger 11 boosts the pressure of air taken in through the air cleaner 12. Perform intake supercharging.

The structure of this pressure wave supercharger 11 is shown in FIG.

The pressure wave supercharger 11 has a rotor 14 disposed within a case 13, and the rotor 14 is rotatably supported within the case 13 via a bearing 15A at its rotor shaft 15. The shaft end thereof is drivingly connected to an output shaft (not shown) of the diesel engine 1 via a belt transmission device 16, and is configured to rotate in synchronization with the diesel engine 1. Further, a large number of partition walls 17, 17... are arranged radially around the outer circumference of the rotor 14, and a large number of small chambers 18, 18 that penetrate in the axial direction and are open at both end surfaces.
...is being formed. Furthermore, the case 13 on one end side (the rotor shaft 15 side) of the rotor 14 is formed with an intake inlet 19 and an intake outlet 20 that communicate with the small chamber 18, respectively.
9 is connected to the intake passage 5A upstream of the pressure wave supercharger 11, and the intake discharge port 20 is connected to the intake passage 5B downstream of the pressure wave supercharger 11. Also, rotor 1
The case 13 on the other end side of 4 is formed with an exhaust inlet 21 and an exhaust outlet 22 that communicate with the small chamber 18, respectively, and the exhaust inlet 21 is connected to the exhaust passage 10A upstream of the pressure wave supercharger 11. Exhaust outlet 22
are connected to the exhaust passage 10B downstream of the pressure wave supercharger 11, respectively. With the above structure, as the rotor 14 rotates, intake air flows into one side of the small chamber 18, exhaust air flows in from the other side, and the two come into direct contact to exchange energy, thereby transmitting the pressure wave energy of the exhaust air to the intake air. By doing so, the intake air is pressurized and the diesel engine 1 is supercharged with the intake air.

Returning again to FIG. 1, the pressure wave supercharger 11
An intake shutter valve 24 (corresponding to the second on-off valve according to the present invention), which is a rosefly valve whose opening and closing is controlled by the first diaphragm device 23, is provided downstream of the downstream intake passage 5B. ,
Also, an upstream exhaust passage 1 communicating with the exhaust port 9
A second diaphragm device 25 is located relatively upstream of 0A.
An exhaust shutter valve 26, which is a butterfly valve whose opening and closing are controlled by the exhaust shutter valve 26, is interposed.

A first three-way solenoid valve 27 is provided for the first diaphragm device 23 that controls opening and closing of the intake shutter valve 24.
is excited when the engine is idling or operating at an extremely low negative pressure close to idling, and switches the negative pressure chamber 23a of the first diaphragm device 23 from the atmospheric side to the negative pressure side provided by the vacuum pump 28. When the negative pressure generated by the vacuum pump 28 is introduced into the negative pressure chamber 23a, the diaphragm 23b of the first diaphragm device 23 is displaced, and the intake shutter valve 24 is opened to a predetermined opening degree via the actuation rod 23c. The valve is closed until the end, and a negative intake pressure of about 100 to 150 mmHg is generated downstream.

As mentioned above, if the intake shutter valve 24 is closed during idling and extremely low load operation, the compression resistance used in the piston 6 can be reduced, and possible torque fluctuations can be reliably prevented. be able to.

On the other hand, the exhaust shear valve 26 is basically controlled by the second diaphragm device 25 so as to be closed when the engine is decelerating and when the engine is cold. That is, during the above operation, the second three-way solenoid valve 29 provided for the second diaphragm device 25 is switched and controlled so as to directly introduce the negative pressure from the vacuum pump 28 into the negative pressure chamber 25a, and the operating rod Diaphragm 25 connected to exhaust shutter valve 26 via 25c
The exhaust shutter valve 26 is closed by the displacement b.

During deceleration when the exhaust shutter valve 26 is closed, the exhaust gas is trapped in the combustion chamber 4 side, increasing the compression resistance acting on the piston 6 and providing a so-called exhaust braking effect. Further, during a cold start, warm-up of the diesel engine 1 itself is promoted by trapping high-temperature exhaust gas in the combustion chamber 4 and supplying a large amount of fuel.

Note that for the second diaphragm device 25,
A third three-way solenoid valve 30 is provided, and when the second three-way solenoid valve 29 is energized when it is not energized, the negative pressure of the vacuum pump 28 is transferred to the negative pressure chamber 25a of the second diaphragm device 25 through the orifice 31. It is now possible to introduce it to This third three-way solenoid valve 30
The negative pressure introduced by the exhaust shutter valve 26 is appropriately diluted midway through by the pressure regulating valve 32, and the exhaust shutter valve 26 is maintained at an intermediate opening (half-closed state) by the diluted negative pressure. be done. The reason why the exhaust shutter valve 26 is kept partially closed in this manner is to secure the exhaust gas that is consumed for heating during running heating, which heats the interior of the vehicle while the vehicle is running.

Furthermore, when the exhaust shutter valve 26 is substantially fully closed or partially closed, the intake shutter valve 24 is partially closed to prevent intake air from blowing back due to an increase in exhaust pressure. It is preferable to do so.

In addition, the intake and exhaust shutter valve 2 as described above
In order to prevent sudden pressure fluctuations caused by the opening and closing of the intake shutter valves 33 and 26, surge tank sections 33 and 3 are provided in the intake passage 5B downstream of the intake shutter valve 24 and in the exhaust passage 10A upstream of the exhaust shutter valve 26.
It is preferable to provide 4 respectively.

On the other hand, as a countermeasure when the pressure wave supercharger 11 is adopted, one is to install another shutter that opens and closes the downstream side intake passage 5B in the vicinity of the intake/discharge port 20 of the pressure wave supercharger 11. A valve (corresponding to the first on-off valve according to the present invention) 35 is provided, and the shutter valve 35 is fully closed by an actuator 36 when the engine 1 is started. When the shutter valve 35 is fully closed, the upstream intake passage 5
Intake air is supplied through a one-way valve (having a function as a bypass passage according to the present invention) 37 provided between the shutter valve A and the intake passage 5B downstream of the shutter valve 35.

This is to prevent starting performance from being extremely deteriorated if a large amount of exhaust gas is brought into the intake side via the pressure wave supercharger 11 when starting the engine, and the shutter valve 35 is Wait for the engine to fully explode and then open to full throttle.

In addition, in order to prevent the boost pressure from increasing excessively due to the increase in exhaust energy during high-speed and high-load operation of the engine, there is a gap between the upstream exhaust passage 10A and the downstream exhaust passage 10B. teeth,
Bypass passage 3 that bypasses the pressure wave supercharger 11
It is preferable to provide a waste gate valve 39 in the bypass passage 38, which opens when the exhaust pressure rises above a set value.

In this way, the exhaust pressure acting on the pressure wave supercharger 11 will not rise above the set value, so the supercharging pressure generated by the pressure wave supercharger 11 will not increase excessively, Engine reliability is ensured.

As explained above, in the configuration in which the intake shutter valve 24 is interposed in the intake passage 5B downstream of the pressure wave supercharger 11, even during operation in which the intake shutter valve 24 is closed, the pressure wave supercharger 1
There is no possibility that negative pressure will be generated in the intake passage 5A upstream, and therefore a large amount of exhaust gas will not be brought into the intake side via the pressure wave supercharger 11.

Furthermore, even if the intake shutter valve 24 is closed to some extent, the smooth operation of the pressure wave supercharger 11 is not hindered, so the respective functions of the intake shutter valve 24 and the pressure wave supercharger 11 are maintained. The pressure wave supercharger 11 can be maintained in a good condition, and the excellent performance of the pressure wave supercharger 11 can be effectively utilized to perform supercharging particularly well in a low speed range.

In addition, although the embodiment of a diesel engine has been described above, it goes without saying that the present invention can also be applied to a spark ignition engine (gasoline engine).

[Brief explanation of drawings]

FIG. 1 is an overall schematic explanatory diagram of an engine showing an embodiment of the present invention, and FIG. 2 is a vertical sectional view showing the structure of a pressure wave supercharger. 5...Intake passage, 10...Exhaust passage, 11...
Pressure wave supercharger, 19...Intake inlet, 20...Intake discharge port, 24...Intake shutter valve (second
on-off valve), 35... shutter valve (first on-off valve), 37... one-way valve (bypass passage).

Claims (1)

[Scope of Claims] 1. A rotor that is rotatably supported within a case and has a number of partition walls arranged radially to form a number of small chambers, an air intake inlet formed in the case at one end of the rotor, and It has an intake discharge port, and an exhaust inlet port and an exhaust discharge port formed in the case on the other end side of the rotor, and supercharges the intake air by transmitting the pressure wave energy of the exhaust gas to the intake air as the rotor rotates. In an engine equipped with a pressure wave supercharger that performs A bypass passage is provided that communicates with the first on-off valve to bypass the pressure wave supercharger when the first on-off valve opens and closes, and allows intake air to flow into the intake passage downstream of the first on-off valve. A supercharged engine characterized in that it is provided with a second on-off valve that substantially controls the amount of intake air at extremely low loads.