JPS622259Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a blow-by gas processing device for an engine in which a supercharger is interposed in the intake passage and does not have an intake throttle valve in the intake passage downstream of the supercharger. .

Generally, in a supercharged engine that does not have an intake throttle valve, a blow-by gas recirculation passage connected to the crankcase or cam case is connected to the intake passage between the air cleaner and the supercharger.
The blow-by gas is configured to be circulated back to the combustion chamber. However, especially when the above-mentioned engine is installed in a passenger car, air cleaner resistance and intake passage resistance become large in order to prevent intake noise, and since there is no throttle valve in the intake passage, a large amount of air is taken in. Since the negative pressure in the intake passage to which the above-mentioned circulation passage communicates becomes large, the circulation amount of blow-by gas becomes excessive, especially during high-load operation, resulting in increased oil consumption, abnormal oil combustion in the combustion chamber, etc. There was a problem. In order to eliminate the above problem, a branch passage is connected to the circulation passage, and the branch passage is connected to the upstream side (dirty side) of the cleaner element of the air cleaner, thereby reducing the negative pressure in the intake passage and causing blow-by gas. It is known that the cleaner element is configured to reduce the recirculation amount, but in this case, there is a problem that the cleaner element is contaminated by oil and carbon in the blow-by gas, so it is often used in diesel engines in particular. In the case of filter paper elements, there is a problem in that the airflow resistance increases significantly due to the attached oil.

Therefore, in view of the above-mentioned problems, this invention was proposed with the aim of constantly circulating a certain amount of appropriate blow-by gas and preventing contamination of the cleaner element. In a supercharged engine in which a supercharger is installed in the middle of the intake passage and does not have an intake throttle valve in the intake passage downstream of the supercharger, to recirculate the blow-by gas of the engine. The recirculation passage is connected to the intake passage between the air cleaner and the supercharger via an orifice, and the positive pressure of supercharging pressure is constantly applied to the intake passage downstream of the supercharger during engine operation. and the intake passage side of the orifice intervening device of the recirculation passage are communicated with each other via a throttle means, and a communication passage is provided for flowing intake air from the intake passage into the recirculation passage. The gist is an engine blow-by gas treatment device. Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG. The reference numeral 10 generally indicates an engine body, which includes an intake passage 16 that communicates with a combustion chamber (not shown) and includes an air cleaner 14 having a cleaner element 12, and an exhaust passage 18 that communicates with the combustion chamber. It is being A pump fan 20 as a supercharger is interposed in the intake passage 16, and the pump fan 20 is connected to the exhaust passage 1.
It is connected via a shaft 24 to a turbine fan 22 which is installed in the engine 8 and is driven by exhaust gas, and is driven by the turbine fan 22. The circulation passage 26 for circulating the blow-by gas generated in the engine body 10 has one end communicating with the crank case or cam case of the engine body 10, and the other end communicating with the intake air between the air cleaner 14 and the pump fan 20. It communicates with the passage 16a, and orifices 28 and 30 are interposed therein. Further, a communication passage 32 is provided midway through the circulation passage 26 to provide an intake passage 16b on the downstream side of the pump fan 20.
An orifice 34 forming a restricting means is interposed in the communication path 32. In addition,
The above configuration is suitable for a diesel engine without an intake throttle valve.

According to the above configuration, when the engine is at low rotation speed, the supercharger is rotated at low speed and the amount of intake air sucked into the intake passage 16a is small.
The intake negative pressure generated in this case has a small value. Blow-by gas generated in the engine body 10 by this intake negative pressure is sucked into the intake passage 16a through the circulation passage 26 and sent to the combustion chamber of the engine body 10. At this time, the amount of blow-by gas recirculated is limited by the orifices 28 and 30.

Further, the flow rate of the positive pressure air pressurized by the supercharger is restricted by the orifice 34, and it is circulated through the communication passage 32 to the circulation passage 26, and blow-by gas is sucked into the intake passage 16a. It acts to reduce the intake negative pressure. As a result, the intake negative pressure is reduced to a desired value, and blow-by gas is recirculated in an amount corresponding to the desired value.

Next, when the engine is running at a high speed, the negative intake pressure generated in the intake passage 16a and the positive pressure generated in the intake passage 16b become large values, and the effect of the decrease in the intake negative pressure due to the positive pressure becomes large, so that the intake negative pressure does not reach the desired level. The blow-by gas is refluxed in an amount corresponding to the value.

As described above, by appropriately selecting the diameters of the orifices 28, 30, and 34, the desired intake negative pressure to suck blow-by gas into the intake passage 16a can be kept almost constant over the entire operating range of the engine. A certain amount of blow-by gas is always refluxed at a certain value. In addition, the intake passage 16
Negative pressure in a tends to increase especially in high negative pressure and high speed operating conditions, but in such cases the boost pressure also increases, so in the above operating conditions the blow-by gas annulus It is possible to prevent the flow rate from becoming excessive and to make the recirculation flow rate appropriate. Furthermore, since the recirculated blow-by gas does not pass through the cleaner element 12, the element 12 is not contaminated with oil, carbon, etc., and there is no problem in using a filter paper element.

Furthermore, under low-load, low-speed operating conditions, the amount of blow-by gas recirculated is appropriate, and since there is no throttle valve installed in the intake passage, the intake air is drawn in without being throttled, resulting in blow-by gas. Over-concentration due to gas reflux is prevented, resulting in stable combustion.

FIG. 2 shows another embodiment of the present invention, in which the diameter of the communication passage 32 in the above embodiment is increased to reduce passage resistance, and the communication passage 32' is An orifice 34 and a constant pressure check valve 36 which opens when the supercharging pressure in the intake passage 16b exceeds a predetermined value are arranged in parallel, and the orifice 34 and the constant pressure check valve 36 form a throttling means. According to the above configuration, the check valve 36 can be opened to prevent the supercharging pressure from becoming excessive especially in high-load, high-speed operating conditions, and the blow-by gas recirculation amount can be controlled as shown in FIG. This can be carried out in substantially the same way as the embodiment shown. In the embodiment shown in FIG. 2, the constant pressure check valve 36 is replaced by a diaphragm valve that opens and closes by detecting the supercharging pressure in the intake passage 16b, and in addition to the supercharging pressure, exhaust pressure, cooling water temperature, and oil temperature. It goes without saying that even if a solenoid valve or the like which is opened and closed by an electric signal from a detection device for detecting the above-mentioned conditions is used, the same effects as those of the above embodiment can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an aspect of one embodiment of the present invention, and FIG. 2 is a schematic explanatory diagram showing an aspect of another embodiment. 10...engine body, 14...air cleaner, 16...intake passage, 20...pump fan,
22...Turbine fan, 26...Recirculation passage, 2
8, 30, 34... Orifice, 32, 32'...
...Communication path, 36...Constant pressure check valve.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A supercharger is interposed in the middle of the intake passage communicating from the air cleaner to the combustion chamber, and an intake throttle valve is provided in the intake passage downstream of the supercharger. In an engine with a turbocharger, a recirculation passage for recirculating the blow-by gas of the engine is connected to the intake passage between the air cleaner and the supercharger via an orifice, and the intake passage downstream of the supercharger is connected to the intake passage between the air cleaner and the supercharger. In the passage, during engine operation, a position where positive pressure of supercharging pressure is always applied is communicated with the intake passage side from the orifice interposed position of the circulation passage through a restricting means, and from the intake passage to the circulation passage. A blow-by gas treatment device for a supercharged engine, characterized by having a communication path through which intake air flows. (2) The blow-by gas treatment device for a supercharged engine according to claim 1, wherein the throttle means is an orifice. (3) The scope of the utility model registration claim, characterized in that the throttle means opens and closes the communication passage depending on the operating state of the engine, and is equipped with a control valve that opens at least when the boost pressure exceeds a predetermined value. A blow-by gas treatment device for a supercharged engine according to item 1. (4) A utility model characterized in that the throttle means opens and closes the communication passage depending on the operating state of the engine, and a control valve and an orifice are interposed in parallel, which open at least when boost pressure exceeds a predetermined value. A blow-by gas treatment device for a supercharged engine according to claim 1.