JPH0765494B2 - Blow-by gas recirculation system for internal combustion engine - Google Patents

Description

The present invention relates to a blow-by gas recirculation system for an internal combustion engine.

<Prior Art> Second example as a conventional example of a blow-by gas recirculation device for an internal combustion engine
There is one as shown in the figure (see Japanese Utility Model Laid-Open No. 56-35545).

That is, during low load operation, the blow-by gas accumulated in the oil pan 1 flows through the passage 2a in the front cover 2 and the rocker cover 3 as indicated by the thick arrow in FIG.
It flows through the blow-by gas recirculation passage 4 in which the pressure control valve 4 a is interposed and flows into the collector portion of the intake manifold 5. Then, the blow-by gas is mixed with fresh air in the collector portion, passes through the branch portion of the intake manifold 5, is introduced into the combustion chamber, and is then burned. At this time, the fresh air introduced into the oil pan 1 is transferred from the fresh air passage 6 to the rocker cover 3
And the oil separator 7 to be introduced into the oil pan 1.

Here, in the pressure control valve 4a, the valve body is urged to open by the spring toward the rocker cover 3, and the valve opening amount is controlled by the differential pressure between the valve body and the blow-by gas flow rate. It has become.

Further, during high load operation, the blow-by gas in the oil pan 1 passes through the fresh air passage 6 and is introduced into the intake passage upstream of the intake throttle valve 8 as indicated by the thin arrow in FIG.

In addition, 9 is an air cleaner and 10 is an air flow meter.

<Problems to be Solved by the Invention> However, in such a conventional blow-by gas recirculation system, if the engine is stopped with the intake throttle valve 8 closed, even if the engine is completely stopped, the intake negative air flows into the collector part. Pressure remains around 1-2 seconds. Therefore, after the engine is completely stopped after the engine key is turned off, if the intake negative pressure in the collector portion becomes the chattering generation negative pressure of the pressure control valve 4a, it is sucked by the intake negative pressure and chattering occurs in the pressure control valve 4a. At this time, since the engine is completely stopped and the surroundings are quiet, there is a problem that the chattering sound of the pressure control valve 4a is perceived as an abnormal sound and gives a driver uncomfortable feeling.

The present invention has been made in view of such circumstances, and an object thereof is to provide a blow-by gas recirculation device capable of preventing abnormal noise due to chattering of a pressure control valve when the engine is stopped.

<Means for Solving the Problems> Therefore, according to the present invention, the blow-by gas recirculation passage is provided with a pressure control valve, and the blow-by gas generated in the engine is introduced through the blow-by gas recirculation passage into the intake air downstream of the intake throttle valve. In the system in which the air is recirculated to the passage, an atmosphere introducing device is provided for introducing the atmosphere into the intake passage downstream of the intake throttle valve for a few seconds at the same time as engine key-off when the engine is stopped.

<Operation> In this way, the atmosphere is introduced into the intake passage downstream of the intake throttle valve at the time of engine key-off, and the intake negative pressure in the intake passage is reduced to atmospheric pressure.

<Example> An example of the present invention will be described below with reference to FIG.

In the figure, a bypass passage 11 that bypasses the intake throttle valve 8
And the bypass passage 12 has an electromagnetic auxiliary air control valve.
13 are installed. The auxiliary air control valve 13 controls the intake flow rate of the bypass passage 12 at the time of cold start or idle operation.

Further, one end of the engine key switch 14 is connected to a power source, and the other end is grounded via a relay coil of a relay 15. The engine key switch 14 is turned off when the engine is stopped to energize the relay coil. Relay 15
The relay contacts are closed when the relay coil is energized.

Further, one end of the relay contact of the relay 15 is connected to the power source, and the other end is connected to the coil portion of the auxiliary air control valve 12 via the timer circuit 16. When the timer circuit 16 is energized by the relay 15, the auxiliary air control valve 12 is energized for a predetermined time (for example, 1 to 2 seconds) from the start of the energization. The auxiliary air control valve 12 introduces the atmosphere into the collector portion of the intake manifold 5 via the bypass passage 11 when energized.

Therefore, the bypass passage 11, the auxiliary air control valve 12, the relay 15, and the timer circuit 16 form an atmosphere introducing device.

With this configuration, when the engine key switch 14 is turned off, the timer circuit 16 energizes the coil portion of the auxiliary air control valve 12 for a predetermined time after the engine key switch 14 is turned off to open the bypass passage 11. As a result, the atmosphere is introduced into the collector section of the intake manifold 5 downstream of the intake throttle valve 8 through the bypass passage 11, so that the internal pressure of the collector section rapidly rises to atmospheric pressure. Therefore, the occurrence of charring of the pressure control valve 4a can be prevented or the timing of occurrence of the charring can be advanced until just before the engine is completely stopped, so that it can be prevented from being caught as an abnormal noise, and thus the driver etc. Eliminates the discomfort of.

It should be noted that a hole communicating with the outside air is provided in the intake passage downstream of the intake throttle valve, and a solenoid valve is attached to this hole to open the hole for a few seconds to introduce the atmosphere when the engine key is turned off. Good.

<Effects of the Invention> As described above, in the present invention, the atmosphere is introduced into the intake passage downstream of the intake throttle valve for several seconds when the engine is stopped, so that the intake negative pressure in the intake passage rapidly becomes atmospheric pressure. . For this reason, the negative pressure for sucking the pressure control valve in the blow-by gas recirculation passage is eliminated, so that chattering of the pressure control valve can be eliminated or the timing of chattering can be accelerated until just before the engine completely stops. Eliminates driver discomfort by eliminating noise.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example of a blow-by gas recirculation device. 4 ... Blow-by gas recirculation passage, 4a ... Pressure control valve, 5
…… Intake manifold, 8 …… Intake throttle valve, 11 ……
Bypass passage, 12 ... Auxiliary air control valve, 14 ... Engine key switch

Claims (1)

[Claims] 1. A blow-by of an internal combustion engine, wherein a blow-by gas recirculation passage is provided with a pressure control valve, and blow-by gas generated in the engine is recirculated to the intake passage downstream of the intake throttle valve via the blow-by gas recirculation passage. A blow-by gas recirculation system for an internal combustion engine, comprising a gas recirculation system, which is provided with an atmosphere introduction device for introducing the atmosphere into the intake passage downstream of the intake throttle valve for a few seconds at the same time as engine key-off when the engine is stopped.