JPH0629464Y2 - Blow-by gas treatment device for supercharged engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a blow-by gas treatment device for a supercharged engine.

(Prior Art) A pressure wave supercharger has been conventionally known as one of intake air supercharging means. However, in this pressure wave supercharger, intake air and exhaust gas are brought into contact with each other in a cell and pressure on the exhaust side is increased. Since the wave is transmitted to the intake side to pressurize the intake air, there are the following problems in processing the blow-by gas of the engine. That is, when treating blow-by gas in an engine with a pressure wave supercharger, a method is usually employed in which the blowby gas is directly returned to the intake passage upstream of the pressure wave supercharger and re-combusted in the engine.
However, since blow-by gas originally contains oil mist, when it is returned to the intake passage on the upstream side of the pressure wave supercharger, intake air and exhaust gas are discharged in the cells of the pressure wave supercharger. If the contact occurs, the oil mist contained in the blow-by gas and the carbon contained in the exhaust gas may come into contact with each other, and a large amount of carbon may adhere to the cells. Therefore, in an engine with a supercharger in which the blow-by gas is recirculated to the intake passage upstream of the pressure wave supercharger as described above, for example, the actual open sho 61-6660.
As disclosed in Japanese Patent Publication No. 8, a heating device is provided to vaporize the oil mist in the blow-by gas to prevent carbon from adhering to the cells of the pressure wave supercharger.

However, in the case of this known example, there is a problem that the structure becomes complicated such as a heating device is required and the air charging efficiency is lowered by the intake air heating and the cost is increased, which is not preferable. .
It is possible to return the blow-by gas into the intake passage downstream of the pressure wave supercharger, but in this case, the intake pressure in the intake passage is very high, which causes a backflow of blow-by gas. Is not suitable.

For this reason, it has been proposed that the blow-by gas is returned to the exhaust passage side and further to the downstream side of the pressure wave supercharger, not to the intake passage. In this case, however much the pressure wave supercharger is on the downstream side, the exhaust pressure from the place where the exhaust silencer, the exhaust gas purification device, etc. are still provided downstream from the pressure wave supercharger is relatively high, Therefore, when the blow-by gas is simply returned as it is to the exhaust passage downstream of the pressure wave supercharger, the back-flow phenomenon of the blow-by gas may still occur. Therefore, conventionally, an ejector is attached to the blow-by gas discharge passage so that the blow-by gas is forcibly recirculated into the exhaust passage by utilizing the suction effect of the ejector. Hereinafter, for convenience of description of the present invention, first, in an engine with a pressure wave supercharger, blowby gas is circulated to an exhaust passage downstream of the pressure wave supercharger, and an ejector is provided in the middle of the blowby gas discharge passage. An example of a general structure of a blow-by gas treatment device for an engine with a supercharger and problems in that case will be described with reference to FIGS. 4 to 6.

FIG. 5 shows an intake / exhaust system diagram of an automobile engine. The intake manifold 2 of the engine 1 has an intake passage 4 and the exhaust manifold 3 has an exhaust passage 5
Are connected respectively. A pressure wave supercharger 6 is provided across the intake passage 4 and the exhaust passage 5.

The pressure wave supercharger 6 includes an air casing 63 connected to the intake passage 4 side, a gas casing 62 connected to the exhaust passage 5 side, the gas casing 62 and the air casing 63.
And a rotor casing 61 arranged between them. The rotor casing 61 has a large number of cells 64, 64 ...
The rotor 66 is attached. This pressure wave supercharger 6 rotates a rotor 66 to rotate each cell 64, 64.
The inside of the exhaust gas on the side of the gas casing 62 and the intake air on the side of the air casing 63 are brought into contact with each other to transmit the pressure wave of the exhaust gas to the intake air, thereby pressurizing the intake air.

An air cleaner 7, an intercooler 8 and a starting valve 9 are provided in the intake passage 4. This starting valve 9 is for introducing natural intake air directly into the engine 1 side from the air cleaner 7 without passing through the pressure wave supercharger 6 when the engine is lightly loaded, and the intake bypass passage 24 is connected to the air cleaner 7. Connected through.

Further, a blow-by gas outlet 11 provided in the head cover 13 of the engine 1 and a blow-by gas inlet 12 formed in the exhaust passage 5 and at a position immediately downstream of the pressure wave supercharger 6 are provided.
Is a blow-by gas discharge passage 20 including an upstream passage 21 connected to the blow-by gas outlet 11 side and a downstream passage 22 connected to the blow-by gas inlet 12 side.
Are communicated with each other via. A pressure introducing passage 23 is connected to the intake outlet 19 formed in the intake passage 4 on the downstream side of the air casing 63 of the pressure wave supercharger 6. The other end of the pressure introducing passage 23 and the three passages, that is, the upstream passage 21 and the downstream passage 22 of the blow-by gas discharge passage 20 are connected to each other via an ejector 10 described later.

As shown in FIG. 6, the ejector 10 is formed in a vacant chamber 31 having a proper volume in which the downstream end 21a of the upstream passage 21 of the blow-by gas discharge passage 20 is opened to the side wall thereof, and the upstream end 22a of the downstream passage 22. And the aperture part 3
Venturi part 3 in which 2a is opened at one end of the vacant chamber 31
2 and one end 23a of the pressure introducing passage 23 and the venturi portion 3 in the vacant chamber 31.
2 and the injection nozzle 3 which is arranged coaxially with the venturi portion 32 and is overlapped with the throttle portion 32a of the venturi portion 32 so as to form an annular gap 33 therebetween.
It is composed of 4 and.

In the engine 1 including the ejector 10 configured as above, the head cover 1
The blow-by gas accumulated in 3 is returned to the exhaust passage 5 immediately downstream of the pressure wave supercharger 6 via the blow-by gas discharge passage 20, in which case exhaust pressure exists in the exhaust passage 5. Nevertheless, the blow-by gas is smoothly recirculated by the suction effect of the ejector 10 provided in the blow-by gas discharge passage 20. That is, in FIG. 6, when the supercharged intake air is blown out from the injection port 34a of the injection nozzle 34 toward the Venturi portion 32 side at a high speed as shown by an arrow B, at the narrowed portion 32a portion of the Venturi portion 32, The intake flow is throttled, the flow velocity becomes faster, and the pressure drops. For this reason, the blow-by gas on the upstream passage 21 side and the internal pressure of the upstream passage 21 and the venturi portion 32 are
Due to the pressure difference from the internal pressure on the side, it is sucked out to the venturi portion 32 side through the annular gap 33 as shown by arrow A, and further pushed out to the downstream passage 22 side as shown by arrow C, and sequentially to the exhaust passage 5 side. It is refluxed.

The blow-by gas suction effect by the ejector 10 becomes better as the pressure difference between the internal pressure of the upstream passage 21 and the internal pressure of the venturi portion 32 increases. On the other hand, the internal pressure of the Venturi portion 32 decreases in proportion to the flow velocity of the intake flow ejected from the injection nozzle 34, that is, the internal pressure of the pressure introduction passage 23. In other words, it can be said that the blow-by gas suction effect in the ejector 10 increases in proportion to the pressure difference between the internal pressure of the pressure introducing passage 23 and the internal pressure of the venturi portion 32.

However, the conventional blow-by gas processing apparatus equipped with such an ejector 10 has the following problems.

That is, when the blow-by gas is discharged from the crank chamber of the engine, it is effective to use the suction effect of the ejector 10 as described above, but if the crank chamber pressure is too low due to the suction effect of the ejector, the combustion chamber will be reduced. The pressure difference between the pressure and the pressure in the crank chamber increases, and the generation of blow-by gas itself increases. Therefore, in the case of discharging blow-by gas by utilizing the suction effect of the ejector, it is necessary to promote the discharge action of the blow-by gas accumulated in the crank chamber to the outside and the amount of blow-by gas leaking from the combustion chamber to the crank chamber itself. In order to achieve both suppression of the above, it is desirable that the crank chamber pressure be set to a pressure slightly lower than the atmospheric pressure throughout the entire operating range of the engine.

However, the ejector 10 having the conventional structure as shown in FIG.
In the blow-by gas treatment apparatus having the above-described structure, the intake pressure on the downstream side of the pressure wave supercharger 6 is directly reflected as the internal pressure of the blow-by gas discharge passage on the downstream side of the venturi section 32. As shown by the curve L ₁ in FIG. 4, in the light load region of the engine in which the supercharging pressure is kept relatively low, the ejecting effect by the ejector 10 is also relatively slow, and the crank chamber pressure is maintained near atmospheric pressure. In the high load range of the engine where the boost pressure itself becomes high, an operating range occurs in which the crank chamber pressure is extremely lower than the atmospheric pressure, as shown by the curve L ₂ in FIG. Therefore, in the light load region of the engine, both the blow-by gas discharging action and the blow-by gas generation suppressing action are maintained relatively well, but the blow-by gas discharging action itself is relatively good in the high engine load region. However, there is a problem that the amount of blow-by gas generated itself increases, and as a result, the crank chamber ventilation is not smoothly performed.

(Object of the Invention) The present invention is intended to solve the problems pointed out in the above-mentioned prior art, in which blow-by gas in the crank chamber is passed through the blow-by gas discharge passage to the exhaust passage downstream of the pressure wave supercharger. In a blow-by gas treatment device for an engine with a supercharger that is recirculated, the generation of blow-by gas in the high supercharging region is suppressed as much as possible, and the discharge action of blow-by gas from the crank chamber is suppressed in the supercharging region. The purpose is to actively carry out in all areas.

(Means for Achieving the Object) As a means for achieving the above object, the present invention has a rotor having a large number of partition walls rotatably supported in a case and forming a large number of cells. In a supercharged engine equipped with a pressure wave supercharger, which connects an exhaust passage and an intake passage of an engine via a cell of the above to give supercharging by applying a pressure in the exhaust passage to the intake air, A blow-by gas discharge passage communicates with an exhaust passage downstream of the machine, and a venturi portion provided in the blow-by gas discharge passage and a pressure introduction passage for guiding pressurized air in the intake passage downstream of the supercharger to the venturi portion. An injection nozzle for injecting the supercharged intake air in the pressure introducing passage toward the venturi portion and in the exhaust flow direction, a supercharging pressure detecting means for detecting the supercharging pressure in the pressure introducing portion, and the supercharging pressure detecting means. A pressure adjusting mechanism including a pressure increasing means for increasing the pressure downstream of the venturi portion when the supercharging pressure of a predetermined pressure or higher is detected by the supply pressure detecting means.

(Operation) In the present invention, by adopting such a configuration, the pressure difference between the pressure introduction passage and the blow-by gas discharge passage downstream of the venturi portion becomes excessively large due to the increase of the supercharging pressure, and the suction action in the venturi portion may become excessive. In a high supercharging region, the pressure difference is reduced by increasing the pressure downstream of the venturi section by the pressure increasing means of the pressure adjustment mechanism, and as a result, the suction effect in the venturi section is maintained at an appropriate level. Will be done.

(Embodiment) A preferred embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

The blow-by gas processing apparatus for a supercharged engine according to the embodiment of the present invention has the same basic configuration as the blow-by gas processing apparatus described in the section of the above-mentioned prior art. Since a pressure adjusting mechanism described later is additionally provided, therefore, the description of the basic configuration will be omitted in the following, and only the pressure adjusting mechanism and a portion related thereto will be described in detail.

(First Embodiment) FIG. 1 shows an ejector 10 portion of a blow-by gas processing apparatus according to a first embodiment of the present invention. The basic structure itself of the ejector 10 portion is the same as that of the conventional example (see FIG. 6), and the blow-by gas discharge passage 20
The upstream passage 21 and the downstream passage 22 are communicated with each other in an orthogonal state via a vacant chamber 31 and a venturi portion 32. An injection nozzle 34 is attached to the pressure introduction passage 23 arranged on the opposite side of the venturi portion 32 with the empty chamber 31 interposed therebetween and coaxially with the venturi portion 32. Then, the supercharged intake air introduced from the intake passage 4 on the downstream side of the pressure wave supercharger 6 via the pressure introduction passage 23 is injected into the injection nozzle 34.
Blow-by gas on the upstream passage 21 side is forcibly sucked and led out on the downstream passage 22 side by being blown out from the injection port 34a to the venturi portion 32 side. Therefore, the discharge of blow-by gas from the crank chamber to the exhaust passage side is promoted through the blow-by gas discharge passage 20.

In this case, the pressure difference between the internal pressure of the pressure introducing passage 23 and the internal pressure of the downstream passage 22 is large in the supercharging region where the suction effect can be expected in the ejector 10, especially in the high supercharging region where the supercharging pressure rises. As described above, there is a possibility that the pressure becomes extremely large, the negative suction pressure of the crank chamber excessively increases due to the excessive suction effect, and the generation of blow-by gas itself increases.

Therefore, in this embodiment, a pressure adjusting mechanism X to be described later is additionally provided, and the pressure adjusting mechanism X controls the pressure difference between the internal pressure of the pressure introducing passage 23 and the internal pressure of the downstream passage 22 downstream of the venturi portion 32. I try to maintain it at an appropriate level.

That is, the pressure adjusting mechanism X includes an opening / closing valve 40 provided in the pressure introducing passage 23 and immediately upstream of the injection nozzle 34, and an actuator 42 for opening / closing the opening / closing valve 40 via a lever 45. It has a pressure passage 41 that guides intake pressure to a pressure chamber 43 of the actuator. The actuator 42 is composed of a diaphragm-type pressure responsive valve, and it is in accordance with the balance between the intake pressure (supercharging pressure) introduced into the pressure chamber 43 through the pressure passage 41 and the spring force of the spring 44. The diaphragm 46 is displaced, and this is transmitted to the lever 45 via the actuator 47.

The operating characteristic of the pressure adjusting mechanism X is set as follows. That is, when the intake pressure in the pressure introducing passage 23 is low (low supercharging region), the on-off valve 40 is held at the fully open position, which is substantially parallel to the flow direction of the intake air. In the high supercharging range in which the intake pressure is high and the intake pressure is high, the operating characteristic of the opening / closing valve 40 is set so that the pressure introducing passage 23 can be appropriately throttled.

In the device provided with such a pressure adjusting mechanism X, the opening / closing valve 40 is kept open in the low supercharging region, and the pressure difference between the internal pressure of the pressure introducing passage 23 and the internal pressure of the downstream passage 22 is originally compared. Since it is relatively small, the suction effect in the venturi portion is not so strong, and the negative pressure in the crank chamber of the engine is maintained at a value close to atmospheric pressure. Therefore, the generation of blow-by gas itself is suppressed, and the blow-by gas in the crank chamber is positively discharged to the exhaust passage 5 side by the suction effect of the ejector 10.

On the other hand, in the high supercharging region, when the supercharged intake air is blown from the injection nozzle 34 to the venturi portion 32 as it is, the pressure difference between the internal pressure of the pressure introduction passage 23 and the internal pressure of the downstream passage 22 becomes excessive. In this embodiment, the on-off valve 40 operates in the closing direction and the passage area of the pressure introducing passage 23 is reduced by the on-off valve 40 so that the intake flow injected from the nozzle 34 toward the downstream passage 22. And the pressure in the downstream passage 22 rises. Therefore, the internal pressure (that is, supercharging pressure) of the pressure introducing passage 23 and the downstream passage 22
The pressure difference with the internal pressure of is maintained at about the same level as in the low supercharging range. Therefore, in spite of the high supercharging range, the negative pressure increase in the crank chamber pressure is suppressed, the generation of blow-by gas is reduced as much as possible, and the appropriate suction effect of the ejector 10 causes the exhaust passage from the crank chamber to be exhausted. The blow-by gas is smoothly discharged to the 5 side.

That is, by attaching the pressure adjusting mechanism X to the ejector 10, the blow-by gas can be smoothly discharged from the crank chamber to the exhaust passage 5 side through the entire supercharging region of the engine, and the blow-by gas itself is generated. It can be effectively suppressed.

In this embodiment, the actuator 42 corresponds to the boost pressure detecting means in the scope of utility model registration claim, and the on-off valve 40 corresponds to the boosting means in the scope of utility model registration claim.

(Second Embodiment) FIG. 2 shows a main part of a blow-by gas processing apparatus according to a second embodiment of the present invention. In this example,
In the first embodiment, the opening / closing valve 40 is provided on the pressure introducing passage 23 side to throttle the intake air flowing in the pressure introducing passage 23 to increase the pressure on the downstream side of the venturi portion to increase the pressure of the pressure introducing portion 23. While the pressure difference from the internal pressure is made small, the opening / closing valve 40 is provided on the venturi portion 32 side, and the opening / closing valve 40 suppresses the flow of the intake air flow ejected from the injection nozzle 34. The speed is reduced to increase the internal pressure on the downstream passage 22 side, thereby reducing the pressure difference between the internal pressure of the pressure introduction passage 23 and the internal pressure of the downstream passage 22. Therefore, naturally, in this case as well, the opening / closing valve 40 is set to have its operating characteristics such that it is fully opened in the low supercharging region and operates in the valve closing direction in the high supercharging region. The on-off valve 40 has the same structure as the on-off valve 40 of the first embodiment.

It goes without saying that the blow-by gas treatment apparatus of the second embodiment can also obtain the same operational effects as the blow-by gas treatment apparatus of the first embodiment.

Also in this embodiment, as in the case of the first embodiment, the actuator 42 corresponds to the supercharging pressure detecting means in the utility model registration claim, and the on-off valve 40 is in the utility model registration claim. Corresponds to the boosting means.

(Third Embodiment) FIG. 3 shows a main part of a blow-by gas processing apparatus according to an embodiment of the present invention. In this embodiment, the above 2
In contrast to the first embodiment, the throttling action of the on-off valve 40 is used to reduce the pressure difference between the internal pressure of the pressure introducing passage 23 and the internal pressure of the downstream passage 22 at the time of high supercharging. As shown in FIG. 3, in the pressure adjusting mechanism X, a pressure passage 41 (corresponding to a pressure increasing means in the scope of utility model registration claims) for connecting the pressure introducing passage 23 and the venturi portion 32 to each other is provided. Valve port 39 formed at the upstream end
And a switching valve having the function of a pressure valve (corresponding to the supercharging pressure detecting means in the scope of utility model registration claims) provided in the above. A part of the intake air on the introduction passage 23 side is directly introduced to the venturi portion 32 side to increase its pressure, and thus the pressure introduction passage 23
This is to reduce the pressure difference between the internal pressure of the above and the internal pressure of the downstream passage 22. Therefore, it goes without saying that the blow-by gas processing apparatus of this embodiment can obtain the same actions and effects as those of the above-mentioned embodiments.

Further, in the above embodiment, the blow-by gas discharge passage 2
When the downstream passage 22 of 0 is connected to the exhaust passage downstream of the supercharger such that the oil mist in the blowby gas reaches a temperature at which the oil mist ignites at high speed and high load of the engine, the pressure becomes high at high speed and high load of the blowby gas. This has an advantage that the blow-by gas is burned and made harmless by an appropriate amount of air from the introduction passage 23.

(Effects of the Invention) The present invention has a rotor having a large number of partition walls rotatably supported in a case and forming a large number of cells, and connects an exhaust passage and an intake passage of an engine through the cells of the rotor. In a supercharged engine equipped with a pressure wave supercharger that is connected to give pressure in the exhaust passage to intake air, the blowby gas discharge passage is connected to the exhaust passage downstream of the supercharger. , A venturi portion provided in the blow-by gas discharge passage, a pressure introduction passage that guides the supercharged intake air downstream of the supercharger to the venturi portion, and the supercharged intake air in the pressure introduction passage is exhausted to the venturi portion. An injection nozzle for injecting in the flow direction, a supercharging pressure detecting means for detecting supercharging pressure in the pressure introducing portion, and a supercharging pressure detecting means for detecting a supercharging pressure of a predetermined pressure or more. A pressure adjusting mechanism including a pressure increasing means for increasing the pressure at the downstream of the turie portion is provided.

Therefore, according to the blow-by gas treatment apparatus for a supercharged engine of the present invention, the pressure difference between the pressure introduction passage and the blow-by gas discharge passage downstream of the venturi portion becomes excessively large due to the increase of the supercharging pressure, and the suction in the venturi portion is increased. In the high supercharging range where the effect may be excessive, the pressure adjustment mechanism increases the pressure on the downstream side of the venturi section to reduce the pressure difference, and the suction effect in the venturi section is maintained at an appropriate level. In particular, in the high supercharging region, excessive negative pressure in the crank chamber is suppressed to reduce the generation of blow-by gas itself, and the blow-by gas is positively discharged from the crank chamber by an appropriate suction effect throughout the supercharging region. A practical effect that the gas can be returned to the exhaust passage side can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a blow-by gas processing apparatus for a supercharged engine according to a first embodiment of the present invention, and FIG. 2 is a supercharged engine according to a second embodiment of the present invention. FIG. 3 is a longitudinal sectional view of a blowby gas treatment apparatus according to a third embodiment of the present invention. FIG. 4 is a longitudinal sectional view of the blowby gas treatment apparatus according to a third embodiment of the present invention. FIG. 5 is a general characteristic view of a blow-by gas treatment apparatus for a conventional engine with a supercharger, and FIG. 6 is an enlarged vertical sectional view of a VI portion in FIG. 1 …… Engine 2 …… Intake manifold 3 …… Exhaust manifold 4 …… Intake passage 5 …… Exhaust passage 6 …… Pressure wave supercharger 7 …… Air cleaner 8 …… Intercooler 9 …… Starting valve 10 …… Ejector 11 ...... Blow-by gas outlet 12 ...... Blow-by gas inlet 13 ...... Head cover 19 ...... Intake outlet 20 ...... Blow-by gas discharge passage 21 ...... Upstream passage 22 ...... Downstream passage 23 ...... Pressure introduction passage 24 ... Intake bypass passage 31 Vacancy 32 Venturi part 33 Annular gap 34 Injection nozzle 40 Opening valve 41 Pressure passage 42 Actuator X Pressure adjusting mechanism

Claims (1)

[Scope of utility model registration request] 1. An exhaust system comprising a rotor having a large number of partition walls rotatably supported in a case and forming a large number of cells, and connecting an exhaust passage and an intake passage of an engine through the cells of the rotor. In a supercharged engine equipped with a pressure wave supercharger for performing supercharging by applying pressure in the passage to intake air, a blowby gas exhaust passage is connected to an exhaust passage downstream of the supercharger, and the blowby gas is connected to the exhaust passage. A venturi portion provided in the discharge passage, a pressure introduction passage that guides the supercharged intake air downstream of the supercharger to the venturi portion, and the supercharged intake air in the pressure introduction passage toward the venturi portion and in the exhaust flow direction. And a venturi when a supercharging pressure of a predetermined pressure or more is detected by the supercharging pressure detecting means for detecting the supercharging pressure in the pressure introducing portion and the supercharging pressure detecting means. Blow-by gas processing apparatus supercharged engine, characterized in that a pressure adjusting mechanism comprising a booster means for raising the pressure downstream.