JPS6040811Y2 - Blow-by gas recirculation device for internal combustion engine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a blowby gas recirculation device for an internal combustion engine that recirculates blowby gas generated in the engine to an intake passage, supplies it to the engine, and burns and purifies it.

Blowby gas recirculation devices for internal combustion engines have traditionally recirculated blowby gas in a blowby gas accumulation area such as an engine crankcase or a locker room to an intake passage downstream of an intake throttle valve via a control valve. The air in the intake passage is sucked into the blow-by gas reservoir of the engine through an air introduction passage to maintain the pressure within the reservoir and provide ventilation.

However, since the control valve is configured to be opened by the engine suction negative pressure downstream of the intake throttle valve, the control valve does not open in the engine high load range where the suction negative pressure is small, and blow-by gas is Since the suction force was also small, it was difficult to reflux the blow-by gas sufficiently and smoothly (see JP-A-55-37529).

Therefore, in a high-speed rotation, high-load region of the engine where a large amount of blow-by gas is generated, the pressure in the blow-by gas retention section increases and the blow-by gas flows back into the intake passage upstream of the intake throttle valve through the air introduction passage, causing the throttle valve to Contaminated the nearby intake passage.

As a result, negative pressure outlets for various control devices near the throttle valve are blocked, or smooth rotation of the throttle valve is prevented, which has an adverse effect on the engine.

This inconvenience is caused by the fact that in the supercharging region of an engine equipped with an exhaust turbocharger, the pressure downstream of the turbocharger is positive, and the control valve of the blowby gas recirculation device is closed, so blowby gas flows from the atmosphere introduction passage to the upstream side of the throttle valve. .

In view of the above-mentioned disadvantages of the conventional device, the present invention has been developed by opening the downstream outlet of the blow-by gas recirculation passage into a venturi section provided in the intake passage downstream of the intake throttle valve, thereby reducing the suction of blow-by gas into the intake passage of the engine. This is achieved by suction negative pressure and venturi negative pressure based on the air flow velocity, thereby making it possible to recirculate blowby gas sufficiently and smoothly over the entire range from low engine loads to high engine loads.

Embodiments of the present invention will be described below based on the drawings.

In FIGS. 1 and 2, intake air of an engine 1 is introduced via an air cleaner 2 and an air flow meter 3, and is introduced through an intake passage 5 upstream of a throttle valve that is connected to a compressor of an exhaust turbocharger 4, an intake throttle valve 6, and a throttle. It is supplied into the combustion chamber 8 through the intake passage 7 downstream of the valve.

On the other hand, fuel is injected and supplied into the intake port 9 from a fuel injection valve (not shown) according to the amount of intake air measured by the air flow meter 3.

Here, the fuel supply system is not limited to the electronically controlled fuel injection type, but may also be a carburetor type, and it goes without saying that it can also be applied to a diesel engine.

After the combustion gas in the combustion chamber 8 rotates the exhaust turbine of the exhaust turbocharger 4, it is discharged through the exhaust passage 10.

A part of the unburned gas in the combustion chamber 8 passes through the outer periphery of the piston 11 and enters the crankcase 12 or the locker room 13.
It leaks into the interior as blow-by gas.

Also, the oil in the crankcase evaporates due to the heat and becomes blow-by gas.

The locker room 13 and the inside of the crankcase 12 are communicated through a communication passage 14 formed in the main body of the engine 1.

A blow-by gas recirculation passage 21 whose inlet end opens into the crankcase 12 has a known control valve (crankcase ventilation control valve) 22 interposed in the middle thereof, and its outlet 20 is shown in detail in FIG. It opens into a venturi section 23 formed on the downstream side of the intake throttle valve 6.

The venturi portion 23 is formed on the downstream side of the cylindrical barrel 24 on the intake side.

The cylindrical barrel 24 has a collar 25 formed on the opposite upstream side.
is mounted between the throttle chamber 27, which forms a part of the intake passage on the downstream side of the throttle valve, and the intake manifold 28, so that it is attached in a shape that projects into the gathering part of the intake manifold 28.

A downstream portion of the blow-by gas recirculation passage 21 is formed within the wall thickness of the throttle chamber 27 and the cylindrical barrel 24.

The control valve 22 opens when the differential pressure across the valve body 22a installed in the blow-by gas recirculation passage 21 becomes greater than the set load of the valve spring 22b, and the blow-by gas flows from the crankcase 12 to the upstream side of the throttle valve. This valve structure allows the air to flow into the intake passage 5.

Further, the crankcase 12 and the intake passage 5 on the upstream side of the intake throttle valve 6 are communicated through an atmosphere introduction passage 29.

The effects of the above configuration are as follows.

A part of the high-pressure gas in the combustion chamber 8 leaks through the outer periphery of the piston 11 and other parts to the crankcase 12 and locker room 13.
Trying to stay inside.

Further, the oil in the crankcase evaporates and accumulates in the crankcase 12.

On the other hand, when the intake air flow of the engine flows through the venturi section 23 downstream of the intake throttle valve 6, it forms a venturi negative pressure at the outlet 20 section of the blow-by gas recirculation passage 21. Control valve 2 cooperates with engine suction negative pressure.
Open 2.

As a result, the blowby gas that tends to accumulate in the crankcase 12 and the locker room 13 through the communication passage 14 is drawn into the intake passage 7 via the blowby gas recirculation passage 21 .

The blow-by gas sucked in this way is transferred to the intake passage 7.
The intake air flow is mixed within the combustion chamber 8 and sucked into the combustion chamber 8 where it is combusted and purified.

At this time, the inside of the crankcase 12 becomes negative pressure due to the above-mentioned suction effect of the blow-by gas, and in an attempt to compensate for this, fresh air in the intake passage 5 on the upstream side of the intake throttle valve 6 is forced into the atmosphere introduction passage 2.
It is introduced into the crankcase 12 via the locker room 13 and the communication passage 14 through the pipe 9, thereby preventing pressure reduction and at the same time providing ventilation.

By the way, when the engine is in a low-load operating range, a negative pressure is maintained in the intake passage 7 downstream of the intake throttle valve 6 due to the influence of the suction negative pressure, and an atmosphere in which blow-by gas is easily sucked through the recirculation passage 21 is maintained.

However, when the engine enters a high-load, high-speed rotation range, the compressor of the exhaust turbocharger 4 operates, creating positive pressure in the intake passage 7 downstream of the intake throttle valve 6 (in engines without an exhaust turbocharger, the intake negative pressure decreases). ), the control valve 22 based on suction negative pressure to maintain the open state of the control valve 22
The positive difference before and after is reduced.

However, the amount of intake air is increased and the venturi section 2
3, the intake flow rate increases and the venturi negative pressure increases,
This venturi negative pressure acts in the direction of increasing the differential pressure across the control valve 22 to maintain the valve open state of 22, so that the blow-by gas continues to be recirculated sufficiently and smoothly.

Therefore, the pressure in the crankcase 12 and the locker room 13 becomes negative, allowing smooth introduction of fresh air through the atmosphere introduction passage 29, and reducing the chances of blow-by gas flowing back into the atmosphere introduction passage 29. Become.

Therefore, the blow-by gas is returned to the intake passage 7 downstream of the throttle valve, and there is little chance of contaminating the vicinity of the throttle valve 6, especially the intake passage upstream thereof, and smooth rotational operation of the throttle valve 6 and various control devices around the throttle valve 6 are avoided. The signal negative pressure outlet hole is less likely to be clogged.

In particular, in this embodiment, the venturi portion 23 is provided not on the wall of the intake passage 7 itself, but on the cylindrical barrel 24 that is formed separately and protrudes into the gathering part of the intake manifold 28, so that the outlet of the exhaust gas recirculation passage (not shown) is connected to the intake manifold. Even if the valve 25 is opened to the collecting portion 25, the recirculated exhaust gas does not flow back into the cylindrical barrel 24, and therefore, it is possible to simultaneously prevent the intake throttle valve 6 from being contaminated by the recirculated exhaust gas.

Furthermore, although the above embodiment shows a case where the throttle chamber 27 is a single barrel, as shown in FIGS. 24, or may be similarly attached to the secondary side.

Furthermore, if necessary, a check valve can be provided in the atmosphere introduction passage 29 to thoroughly prevent the backflow of blow-by gas.Also, even if the control valve 22 is installed on the atmosphere introduction passage 29 side, blow-by gas reflux is substantially the same. It is something that is done.

As described above, according to the present invention, the blowby gas in the blowby gas accumulation part of the internal combustion engine is recirculated to the downstream side of the intake throttle valve through the recirculation passage, and the atmosphere in the intake passage on the upstream side of the throttle valve is introduced into the atmosphere. When ventilation is performed by introducing the blowby gas into the reservoir through the passage, the outlet of the recirculation passage is opened to the venturi section provided downstream of the intake throttle valve, so that the intake of blowby gas is controlled by the engine suction negative pressure. Alternatively, venturi negative pressure based on the intake flow rate can also be used.

Therefore, even if the engine is in a high-speed, high-load region with low suction negative pressure, or if the engine is equipped with an exhaust turbocharger, blow-by gas can be recirculated sufficiently and smoothly, and there is little chance of blow-by gas recirculating to the atmosphere introduction passage. .

As a result, the vicinity of the intake throttle valve is less likely to be contaminated by blow-by gas, the signal negative pressure outlet holes for various control devices in the vicinity of the throttle valve are not blocked, and the rotational operation of the throttle valve can be made smooth.

Furthermore, since it has a simple configuration, it can be supplied at a low price, and the layout is not complicated, so productivity, ease of assembly, and maintenance and inspection are easy.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway system diagram showing an embodiment of the blow-by gas recirculation device for an internal combustion engine with an exhaust turbocharger according to the present invention;
Fig. 2 is a vertical sectional view of the main part of the same as above, Fig. 3 is a longitudinal sectional view of the part corresponding to Fig. 2 showing another embodiment of the present invention, and Fig. 4 is a longitudinal sectional view of the same part as above.
-A cross-sectional view. 1... Engine, 4... Exhaust turbocharger, 5... Intake passage upstream of intake throttle valve, 6
...Intake throttle valve, 7...Intake passage downstream of the intake throttle valve, 12...Crankcase, 1
3... Locker room, 20... Exit, 21... Blow-by gas recirculation passage, 22...
... Control valve, 23 ... Venturi section, 24
・・・・・・Cylindrical barrel.

Claims (1)

[Scope of utility model registration request] The blow-by gas return passage of the control valve material returns the blow-by gas generated in the engine from the crankcase to the intake passage downstream of the intake throttle valve, the intake passage upstream of the intake throttle valve, and the locker room where the blow-by gas of the engine is stored. A blow-by gas recirculation system for an internal combustion engine, characterized in that a venturi section is formed in the intake passage downstream of an intake throttle valve, and an outlet of the blow-by gas recirculation passage is opened in the venturi section. Device.