JPS6039451Y2 - Blow-by gas reflux device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a blow-by gas recirculation device that recirculates blow-by gas generated in an engine from an intake passage to a combustion chamber for combustion treatment.

As a countermeasure device for internal combustion engine blowby gas, a blowby gas recirculation device has been proposed that returns blowby gas from the crankcase to the combustion chamber and burns it again, such as the ventilation blowby system shown in Figure 1 (References: 1 Automotive Engineering Handbook 1st Volume 7-15~7-
16 pages, Automotive Technology Complete Showa 4g#-Published).

In FIG. 1, depending on the opening degree of the throttle valve 11, the intake passage 19
After the air taken into the intake valve 2 is purified by the air cleaner 17, the flow rate is measured by the air flow meter 18.
When the valve 1 is opened, the fuel is supplied to the combustion chamber 20.

A portion of the fresh air supplied to the engine at idle is passed through the throttle valve 11.
It is supplied through an idle passage 7 provided to bypass the.

An idle adjustment screw 10 is provided in the middle of the idle passage 7 to adjust the bypass flow rate.
It is designed to finely adjust the engine idle rotation.

On the other hand, in order to process blow-by gas, some intake air is sent to the crankcase 16 in the air box 8 upstream of the throttle valve.
The flow is divided into an atmospheric passage 4 leading to the atmosphere.

This air comes out from the fresh air outlet 1a and flows through the rocker cover 1.
The fresh air enters the inside and reaches the crankcase 16 via the oil down passage 5, where it mixes with unburned gas (gas at the blowout) that leaked out through the sliding gap between the cylinder 14 and the piston 13. .

These become blow-by gases, which pass through the blow-by recirculation passage 6 and are controlled in flow rate by the control valve 12, and are sent to the intake passage downstream of the throttle valve 11 (intake manifold 21 hold).
Attracted to 9.

The control valve 12 has a valve body 1 as shown in FIG.
2a and a spring 12b that biases the valve body 12a in a direction away from the valve seat 12c, and blow-by gas is transferred to the intake manifold according to the valve opening degree that is controlled based on the balance between the spring 12b and the intake manifold negative pressure. Reflux into hold 9.

This blow-by gas is sucked into the combustion chamber 20 together with the air-fuel mixture through the intake valve 21 and combusted again.

By repeating this operation, blow-by gas accumulated in the crankcase 16 is re-combusted, fuel is effectively consumed, and the pressure inside the crankcase 16 can be prevented from becoming high.

Incidentally, the amount of intake air required during idle to obtain a predetermined idle rotational speed is adjusted by an adjustment screw 10 in the idle passage 7.

However, since the passage that bypasses the throttle valve 11 is divided into the idle passage 7 and the atmospheric passage 4, in order to smoothly perform this adjustment, the blow-by recirculation passage 6 that connects to the atmospheric passage 4 must also have the same opening area. There will be restrictions.

As a result, the opening area of the control valve 12 cannot be made too large, and when the amount of blow-by gas generated increases, such as during high-load rotation, the blow-by recirculation passage 6
This results in blow-by gas that cannot be absorbed completely flowing back through the atmospheric passage 4, and is discharged upstream of the throttle valve 11, contaminating the intake system and interfering with its operation.

Furthermore, the fact that the idle passage 7, which has the same function of bypassing the throttle valve 11, and the atmosphere passage 4 and the blow-pipe recirculation passage 6 are provided independently complicates the mechanism of the intake system and increases costs. Moreover, it also has the disadvantage of poor workability during maintenance and inspection.

Therefore, the present invention consists of a throttle valve installed in the intake passage, an atmospheric passageway that sends fresh air from the intake passage upstream of the throttle valve to the crankcase, and a blow-by recirculation system that recirculates blow-by gas from the crankcase to the intake passage downstream of the throttle valve. The present invention attempts to solve the problems of the conventional device described above by providing a mechanism consisting of a passage and an idle air flow rate adjusting screw provided in the blow pie return passage.

FIG. 3 shows an embodiment of the present invention, and in the figure, members similar to those in the conventional example are designated by the same reference numerals and explanations thereof will be omitted.

The fresh air that has reached the air box 8 is divided into those that are sucked into the atmospheric passage 4a and those that directly pass through the throttle valve 11.

The atmospheric passage 4a has a cross-sectional area that is the sum of the effective cross-sectional areas of the conventional atmospheric passage 4 and the idle passage 7, respectively.

The blow pie recirculation passage 6a for discharging blow-by gas from the crankcase 16 also has a large effective cross-sectional area.

An oil separator 15 that prevents oil from being sucked up is provided in the middle of this recirculation passage 6a, and an idle adjustment screw 10a is provided further downstream.
The idle air flow rate and the amount of blow-by gas controlled by the throttle valve 11 are sucked into the downstream intake passage 9 of the throttle valve 11.

With the above configuration, the fresh air supplied to the engine during idling can either directly pass through the throttle valve 11 or bypass the throttle valve 11 through the atmospheric passage 4a, the crankcase 16, and the recirculation passage 6a. It becomes.

This bypass air is then fed to the idle adjustment screw 10a.
The engine speed can be increased by 100 kHz and adjusted to obtain a predetermined idle speed.

In this case, blow-by gas is also included in the bypass air, but oil in this blow-by gas is removed by the oil separator 15, so oil consumption does not increase.

Next, when comparing the amount of bypass air with the conventional one, it becomes as shown in FIG. 4.

A is the bypass air flow rate according to the conventional configuration, the amount of air passing through the idle passage 7 is a1, and the amount of air passing through the blow-by recirculation passage 6 is as follows.

B is the amount of bypass air according to the present invention, and d is the characteristic of the blow-by gas recirculation passage, which is much larger than the conventional b, so that the back flow of blow-by gas during high engine loads is reduced accordingly.

Also, in terms of exhaust performance, the amount of blowby generated itself does not change in the present invention, so there is no effect on the air-fuel mixture due to blowby gas.

In this way, according to the present invention, the idle passage that bypasses the throttle valve from upstream to downstream is combined with the blow-pie return passage to form one bypass passage with a large effective diameter, so that idle rotation adjustment and blow-by gas return can be controlled simultaneously. In addition, the mechanism of the intake system becomes simpler, and maintenance and inspection become easier.

In addition, the blowby gas has sufficient reflux characteristics, which prevents blowby gas from flowing backwards, reduces dirt in the intake passage, eliminates time-consuming measures to prevent dirt, and eliminates the need for a control valve, reducing costs. .

Note that the present invention can be similarly applied to a closed blow-by system that does not have the atmospheric passage 4.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the conventional example, Figure 2 is an enlarged sectional view of the same control valve, Figure 3 is a sectional view of the embodiment of the present invention, and Figure 4 is a comparison of the bypass flow characteristics of the conventional example and the present invention. This is a graph shown as follows. 4a... Atmospheric passage, 5... Oil downward passage, 6a... Blow pie return passage, 10a... Idle adjustment screw, 11... Throttle valve, 13... Piston, 4... Turinda, 15... Oil separator.

Claims (1)

[Scope of utility model registration request] A throttle valve provided in the intake passage, an atmospheric passage that sends fresh air from the intake passage upstream of the throttle valve to the crankcase, a blow-by recirculation passage that recirculates blow-by gas from the crankcase to the intake passage downstream of the throttle valve, and the blow-by recirculation passage. A blow-by gas recirculation device comprising an idle air flow rate adjusting screw provided in a passage.