JPH10317938A - Positive crankcase ventilation system for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the pulsation of intake air caused by pressure fluctuation of blowby gas, suppress the deposition of sludge and the condensation or freezing of moisture in a blowby gas passage, and suppress fouling of the detecting element of an airflow meter by sludge contained in blowby gas. SOLUTION: An engine control system comprises a positive crankcase ventilation system for evacuating the crankcase of an engine of blowby gas and returning it to an intake system, and a device arranged in the intake system to detect an airflow rate. In that control system, the ratio of the minimum cross-sectional area of a blowby gas passage 19b that communicates together the engine crankcase and the upstream part of an intake passage 18 with an intake air control valve 14 is set not more than 0.008 to the cross-sectional area of the intake passage 18 at the position where the blowby gas passage 19 opens thereinto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an engine control system including a blow-by gas reducing device and an air flow detecting device.

[0002]

2. Description of the Related Art A blow-by gas reducing device is a blow-by gas leaking into a crankcase through a gap between a piston and a cylinder wall of an engine of an internal combustion engine in order to purify exhaust gas discharged from an internal combustion engine of an automobile or the like. The gas is discharged from the engine crankcase and returned to the intake system to recirculate and burn the blow-by gas.

FIG. 9 is a schematic diagram showing an internal combustion engine provided with a conventional blow-by gas reducing device. The blow-by gas leaking into the crankcase 13 is discharged from the engine crankcase 13 and returned to the intake system to reduce the blow-by gas. Is recirculated and burned.

In the blow-by gas reducing device shown in FIG.
The first passage 17 and the second passage 17 serve as blow-by gas recirculation passages.
Path 19a. The first passage 17 is provided in the intake passage 1 downstream of the crankcase 13 and the intake air control valve 14.
5. Metering valve (PCV valve) that adjusts the amount of blow-by gas suction according to the operating conditions of the engine
The second passage 19 a communicates with the intake passage 18 upstream of the crankcase 13 and the intake air valve 14.

The second passage 19a communicating with the crankcase 13 and the intake passage 18 upstream of the intake air valve 14 is usually constituted by a combination of pipes made of metal, rubber or the like having a constant cross-sectional area. The cross-sectional area of the intake passage 18 is constituted by a desired cross-sectional area due to the total displacement of the engine of the internal combustion engine and restrictions for obtaining a predetermined engine output, and the second cross-sectional area with respect to the minimum cross-sectional area of the second passage 19a. The ratio of the cross-sectional area of the intake air passage 18 at a position 20a where the passage 19a is open upstream of the intake air valve 14 is as follows:
It was configured to be 0.01 or more.

In an engine control system in which the intake air control valve 14 and the air flow detecting device 21 are integrally formed or both are connected, generally, the second passage 19a is located upstream of the intake air control valve 14. Passage 2 having a detection element 23 of an air flow detection device 21
2 was configured to be located further upstream of the opening 20a of the second passage 19a.

[0007]

FIG. 10 (a) and FIG. 10 (b)
FIG. 10 is a plan view and a side sectional view showing the vicinity of a connection portion between a second blow-by gas recirculation passage and a suction air passage in the conventional apparatus of FIG. 9. Conventionally, as described above, the ratio of the sectional area of the intake air passage 18 at the upstream opening 20a of the intake air valve 14 of the second passage 19a to the minimum sectional area of the second blow-by gas passage 19a is 0.01 or more. When the engine load is relatively small, such as during idling, the pulsation generated in synchronization with the cycle in which the piston of the engine operates is transmitted to the second passage 19a, and the second passage 19a is opened. This has a great effect on the intake air flowing through the intake air passage 18 that is in the air.

For example, FIG. 3 shows that in the engine test of the inventor himself, the second cross section of the second passage 19a with respect to the minimum
The result of investigating the detection error of the intake air amount when the ratio of the sectional area of the intake air passage 18 at the upstream opening 20a of the intake air valve 14 of the passage 19a is changed. This figure 3
According to this, when the ratio of the cross-sectional area ratio was 0.01 or more, the air flow rate detection error was significantly deteriorated.

[0009] To solve the above problem, for example,
The blow-by gas reducing device described in Japanese Patent Application Laid-Open Nos. 1-95916, 61-99617, and 59-203814 discloses a method in which the second blow-by gas recirculation passage is forked or narrowed in the blow-by gas recirculation passage. By providing a valve and an expansion chamber, the influence on the intake air due to the fluctuation of the pressure of the blow-by gas is reduced.
When such measures are taken in the blow-by gas passage, the cross-section of the blow-by gas passage changes partly abruptly, and the inner wall surface of the blow-by gas passage becomes discontinuous, causing a step. Contaminants such as carbon contained in the blow-by gas and sludge contained in the engine oil tend to accumulate in places where such steps occur, and condensation and freezing of water are promoted in cold weather, and a predetermined blow-by gas flow rate is recirculated. It becomes impossible.

Further, as shown in FIG. 11, if there is a step 30 at the joint of the second blow-by gas passage 19a, especially the passage communicating with the upstream of the intake air control valve 14, the blow-by gas is supplied as in the above case. Contaminants such as carbon contained therein and sludge contained in engine oil tend to accumulate.
In particular, since the opening of the blow-by gas passage to the intake air passage is away from the engine, the temperature tends to be low in cold weather, and the exhaust gas contained in the blow-by gas condenses and freezes, and the cross-sectional area of the passage is reduced. It has been found by the inventors' actual engine verification that the passage becomes small and the passage is easily clogged.

When the air flow detecting device 21 and the intake air control valve 14 are relatively close to each other, the opening of the second passage 19a is conventionally located upstream of the intake air control valve 14 and downstream of the air flow detecting device 21. The blow-by gas is directly returned to the intake air and enters the detection passage 22 so that carbon contained in the blow-by gas, sludge contained in the engine oil, and the like are removed from the air flow detecting device 21. When the amount of intake air is measured by the air flow detecting device 21, it may be inaccurate or may cause problems such as long-term reliability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and when the engine load is relatively small, such as during idling, the pressure fluctuation of the blow-by gas is synchronized with the cycle in which the engine operates. It is an object of the present invention to reduce pulsation of intake air and to suppress accumulation of contaminants and the like in a blow-by gas passage, condensation of water, and freezing. In addition, by configuring the detection element of the air flow rate detection device so as not to be easily polluted by pollutants contained in the blow-by gas, an engine control having an accurate and highly reliable blow-by gas reduction device and an intake air amount detection device is provided. The purpose is to provide a system.

[0013]

According to a first aspect of the present invention, there is provided an engine control system including a blow-by gas reducing device and an air flow detecting device, the blow-by device communicating a crankcase of an engine with an upstream side of an intake air control valve. The ratio of the minimum sectional area of the gas passage to the sectional area of the intake passage at the position where the blow-by gas passage opens to the intake passage is 0.00
8 or less.

According to a second aspect of the present invention, the minimum cross-sectional area of the blow-by gas passage that connects the crankcase of the engine and the upstream side of the intake air control valve, and the cut-off of the intake passage at the position where the blow-by gas passage opens to the intake passage. It was configured such that the ratio to the area was 0.0065 or less.

According to a third aspect of the present invention, the cross-sectional area of the blow-by gas passage communicating the crankcase of the engine and the upstream side of the intake air control valve is gradually reduced from the upstream side of the intake air control valve toward the crankcase. Reduced to

According to a fourth aspect of the present invention, the cross-sectional area of the blow-by gas passage communicating the crankcase of the engine and the upstream side of the intake air control valve is gradually reduced from the upstream side of the intake air control valve toward the crankcase. And gradually expanded from the middle.

According to a fifth aspect of the present invention, the opening surface of the blow-by gas passage that connects the crankcase of the engine and the upstream side of the intake air control valve to the intake passage is formed by the intake air in the detection passage of the air flow detecting device. It is located on the intake passage wall facing the side surface between the inlet and the outlet.

According to a sixth aspect of the present invention, a blow-by gas passage communicating the crankcase of the engine with the upstream side of the intake air control valve is disposed at a predetermined angle toward the downstream side of the flow of the intake air. The surface is located on the intake passage wall facing the side surface between the intake air inlet and the outlet of the detection passage of the air flow detecting device.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, a blow-by gas returning device of an engine control system according to Embodiment 1 of the present invention will be described.

FIG. 1 is a schematic structural view showing an internal combustion engine provided with a blow-by gas reducing device according to the first embodiment. The internal combustion engine passes through a gap 12 between a piston 10 and a cylinder wall 11 of an engine of the internal combustion engine, and is provided in a crankcase 13. Blow-by gas leaking from the engine crankcase and returned to the intake system to recirculate and burn the blow-by gas.

In FIG. 1, a first passage 17 and a second passage 19b are provided as blow-by gas recirculation passages. The first passage 17 communicates with a crankcase 13 and an intake passage 15 downstream of the intake air control valve 14 via a metering valve (PCV valve) 16 that adjusts a suction amount of blow-by gas according to an engine operating condition. The second passage 19b is provided between the crankcase 13 and the intake air valve 1.
4 is configured to communicate with the intake passage 18 upstream.

FIGS. 2 (a) and 2 (b) are a plan view and a side sectional view showing the vicinity of a connection portion between the blow-by gas recirculation passage and the intake air passage of the engine according to the first embodiment, particularly the second blow-by gas recirculation passage. is there.

In FIG. 2, the minimum cross-sectional area of a second blow-by gas passage 19b communicating the crankcase 13 and the upstream of the intake air control valve 14 and the opening 20b of the second blow-by gas passage 19b to the intake passage 18 are shown. Is 0.008 or less, preferably 0.008
It is configured to be 65 or less.

In the figure, the second blow-by gas passage 1
As the ratio of the cross-sectional area of the intake passage at the opening 20b to the intake passage of the blow-by gas passage 19b having the minimum cross-sectional area of 9b decreases, the pulsation effect of the blow-by gas flow on the intake air amount gradually decreases. As shown in FIG. 3, the air flow detecting device 21 in the engine control system
The detection error of the air flow rate measured in step (b) is reduced, and the minimum cross-sectional area of the blow-by gas passage 19b and the blow-by gas passage 19b are reduced.
The detection error can be minimized when the ratio of the sectional area of the intake passage at the opening 20b to the intake passage b is 0.008 or less, particularly around 0.0065.

Embodiment 2 FIG. 4 is a cross-sectional view showing a blow-by gas returning device for an engine according to the second embodiment, particularly a blow-by gas recirculation passage. In the figure, a blow-by gas recirculation passage is constituted by a blow-by hose 19c made of a material such as rubber, for example, and is cut off from the upstream side of the intake air control valve 14 on the suction passage side toward the crankcase 13 on the engine head side. It is configured to continuously and slowly reduce the area. In addition, the blow-by gas passage 19c is configured such that no step is formed particularly on the joint side communicating with the upstream of the intake air control valve.

In FIG. 4, the pulsating pressure of the blow-by gas is transmitted from the crankcase 13 to the intake air passage side. At this time, the cross-sectional area of the blow-by gas passage is reduced, so that the amplitude of the pulsating pressure of the blow-by gas is reduced. Becomes smaller. Further, in the blow-by gas passage, particularly, there is no step at the joint of the passage communicating with the upstream of the intake air control valve 14, and there is no place where the cross-sectional area changes suddenly. Condensation and freezing of water in the exhaust gas contained in the gas hardly occur.

Embodiment 3 5 and 6 are cross-sectional views showing a blow-by gas returning device for an engine according to the third embodiment, in particular, a blow-by gas recirculation passage. In the figure, a blow-by gas recirculation passage is constituted by blow-by hoses 19d and 19e made of a material such as rubber, for example, from the upstream side of the intake air control valve 14 on the suction passage side toward the crankcase 13 on the engine head side. The cross-sectional area is formed so as to be continuously and gradually reduced, and the cross-sectional area is configured to be continuously and slowly expanded from the middle. Also, in the blow-by gas passages 19d and 19e, a step is not formed between the joint side of the passage communicating with the engine head communicating with the crankcase 13 and the joint side communicating with the upstream of the intake air control valve. Configure.

According to the third embodiment, the amplitude of the pulsating pressure of the blow-by gas is reduced by reducing the sectional area of the blow-by gas passage. In addition, since there is no step at the joint between the blow-by gas passage on both the engine head side and the intake air passage side, deposition of contaminants contained in the blow-by gas and condensation and freezing of moisture in the exhaust gas are unlikely to occur. .

Embodiment 4 7 (a) and 7 (b) are a plan view and a side sectional view showing the vicinity of a connection portion between a blow-by gas recirculation passage and a suction air passage of a blow-by gas returning device for an engine according to a fourth embodiment. In the figure, an air flow detection device 21 has a detection passage 22 in which a detection element 23 is disposed. 14 is an intake air control valve, 2
Reference numeral 0b denotes an opening of a blow-by gas passage 19f communicating the crankcase and the upstream of the intake air control valve 14, and the intake air is opposed to a side surface 42 between the intake air inlet 40 and the outlet 41 of the air flow detecting device 21. It is configured to open to the passage wall surface.

As described above, according to the fourth embodiment, since the opening to the intake air passage is blocked by the outer peripheral surface of the detection passage of the air flow detecting device, the blow-by gas is discharged from the outer peripheral surface of the passage for flow detection. , And contaminants such as dust contained in the blow-by gas will adhere to the surface,
As a result, the contaminants hardly adhere to the flow rate detecting element 23 formed inside the detection passage 22.

Embodiment 5 8 (a) and 8 (b) are a plan view and a side sectional view showing the vicinity of a connection portion between a blow-by gas recirculation passage and a suction air passage of a blow-by gas reducing device for an engine according to a fifth embodiment. In the figure, an air flow detection device 21 has a detection passage 22 in which a detection element 23 is disposed. 14 is an intake air control valve, and 20b is a crankcase 13 and an intake air control valve 14.
The opening of the blow-by gas passage 19g communicating with the upstream of the blow-by gas is arranged at a predetermined angle (downstream direction) with respect to the direction perpendicular to the flow of the intake air. The opening is a side surface 4 between the intake air inlet 40 and the outlet 41 of the air flow detecting device 21.
2 and open to the intake passage wall surface.

According to the fifth embodiment, the same effects as those of the fourth embodiment can be obtained, and the blow-by gas flows into the intake passage in the downstream direction. The amount can be suppressed,
Contaminants are less likely to adhere to the flow rate detection element formed inside the detection passage 22.

[0033]

According to the first or second aspect of the present invention,
In the engine control system, the ratio of the cross-sectional area of the blow-by gas passage that connects the crankcase and the upstream side of the intake air control valve to the cross-sectional area of the intake passage that opens the blow-by gas passage is 0.008 or less, preferably 0.1 mm or less. 0065
With the configuration described below, the pressure fluctuation of the blow-by gas is suppressed, and the pulsation of the intake air caused by the pressure fluctuation is reduced, and the detection error of the intake air amount is reduced.

The pulsating pressure of the blow-by gas is transmitted from the crankcase to the intake air. According to the third and fourth aspects of the present invention, the cross-sectional area of the blow-by gas passage is reduced, so that the blow-by gas is blown. The amplitude of the pulsating pressure decreases. In addition, since there is no place in the blow-by gas passage where the cross-sectional area changes suddenly, it is possible to suppress accumulation of contaminants contained in the blow-by gas and freezing of moisture.

According to the fifth aspect of the present invention, in the opening to the intake air passage of the blow-by gas passage communicating the crankcase with the upstream side of the intake air control valve, the opening is a detection passage of the air flow detecting device. The blow-by gas collides with the outer peripheral surface of the detection passage, and contaminants contained in the blow-by gas adhere to the outer peripheral surface of the detection passage, and the flow rate detecting element formed inside the detection passage. Has the effect of preventing fouling from adhering.

According to the sixth aspect of the present invention, since the opening of the blow-by gas passage is further opened in the downstream direction of the intake air, the flow direction of the blow-by gas into the intake passage becomes the downstream direction. When the blow-by gas collides with the outer peripheral surface of the detection passage, contaminants adhere to the outer peripheral surface of the detection passage, and the amount of the blow-by gas flowing to the upstream of the detection passage can be suppressed. Thus, an effect is obtained that the contaminants hardly adhere to the flow rate detecting element configured as described above.

As described above, according to the present invention, the pulsation of the intake air caused by the fluctuation in the pressure of the blow-by gas is reduced, and it is possible to measure the intake air amount more accurately. In addition, the contaminants contained in the blow-by gas hardly accumulate in the blow-by gas passage, and further, the contaminants hardly adhere to the flow rate detecting element formed inside the air flow rate detection passage, which is accurate and excellent in reliability. It is possible to obtain an engine control system including a blow-by gas reduction device and an air flow rate detection device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an internal combustion engine including a blow-by gas returning device according to Embodiment 1 of the present invention.

FIGS. 2A and 2B are a plan view and a side sectional view showing a vicinity of a connection portion between a second blow-by gas recirculation passage and an intake air passage according to the first embodiment;

FIG. 3 is a diagram showing the relationship between the ratio of the cross-sectional area of the intake air passage at the upstream opening of the intake air control valve of the blow-by gas recirculation passage to the minimum cross-sectional area of the blow-by gas recirculation passage, and an intake air amount detection error. .

FIG. 4 is a cross-sectional view showing a blow-by gas recirculation passage of a blow-by gas returning device for an engine according to a second embodiment.

FIG. 5 is a cross-sectional view showing a blow-by gas recirculation passage of a blow-by gas reducing device for an engine according to a third embodiment.

FIG. 6 is a cross-sectional view showing a blow-by gas recirculation passage of a blow-by gas returning device for an engine according to a third embodiment.

FIG. 7 is a plan view and a side cross-sectional view showing the vicinity of a connection portion between a second blow-by gas recirculation passage and an intake air passage of a blow-by gas reduction device for an engine according to a fourth embodiment.

FIG. 8 is a plan view and a side cross-sectional view showing the vicinity of a connection portion between a second blow-by gas recirculation passage and an intake air passage of a blow-by gas reduction device for an engine according to a fifth embodiment.

FIG. 9 is a schematic configuration diagram showing an internal combustion engine provided with a conventional blow-by gas returning device.

FIG. 10 is a plan view and a side sectional view showing the vicinity of a connection portion between a conventional second blow-by gas recirculation passage and a suction air passage.

FIG. 11 is an enlarged sectional view of a joint portion of a second conventional blow-by gas recirculation passage.

[Explanation of symbols]

13 crankcase, 14 intake air control valve, 18
Intake passage, 19b, 19c, 19d Blow-by gas passage, 20b Opening.

Claims (6)

[Claims] 1. An engine control system comprising: a blow-by gas reducing device that discharges blow-by gas from an engine crankcase and returns the blow-by gas to an intake system; and an engine control system that is provided in the intake system and detects an air flow rate. The ratio of the minimum sectional area of the blow-by gas passage communicating with the upstream side of the air control valve to the sectional area of the intake passage at the opening position of the blow-by gas passage to the intake passage is 0.008 or less. Engine blow-by gas reduction device. 2. A ratio of a minimum cross-sectional area of a blow-by gas passage that connects a crankcase of an engine and an upstream side of an intake air control valve to a cross-sectional area of an intake passage at an opening position of the blow-by gas passage to the intake passage. 2. The blow-by gas reducing device for an engine according to claim 1, wherein the value is 0.0065 or less. 3. An engine control system comprising: a blow-by gas reducing device that discharges blow-by gas from an engine crankcase and returns the blow-by gas to an intake system; and an engine control system that is provided in the intake system and detects an air flow rate. A blow-by gas reducing device for an engine, wherein a cross-sectional area of a blow-by gas passage communicating with an upstream side of an air control valve is gradually reduced continuously from an upstream side of an intake air control valve toward a crankcase. 4. An engine control system comprising: a blow-by gas reducing device that discharges blow-by gas from an engine crankcase and returns the blow-by gas to an intake system; and an engine control system that is provided in the intake system and detects an air flow rate. The fact that the cross-sectional area of the blow-by gas passage communicating with the upstream side of the air control valve has been slowly and continuously reduced from the upstream side of the intake air control valve in the direction of the crankcase, and has been gradually expanded continuously from the middle. Characteristic engine blow-by gas reduction device. 5. An engine control system comprising: a blow-by gas reducing device that discharges blow-by gas from an engine crankcase and returns the blow-by gas to an intake system; and an engine control system that is provided in the intake system and detects a flow rate of air. The opening surface of the blow-by gas passage that communicates with the upstream side of the air control valve to the intake passage is formed on the intake passage wall facing the side surface between the intake air inlet and the outlet of the detection passage of the air flow detection device. A blow-by gas reduction device for an engine, comprising: 6. The blow-by gas passage communicating the crankcase of the engine with the upstream side of the intake air control valve is disposed at a predetermined angle toward the downstream side of the intake air flow. The blow-by gas reduction device for an engine according to the above.