JPH0521607Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a blow-by gas recirculation device for an internal combustion engine, and in particular to a blow-by gas recirculation device for an internal combustion engine that aims to recirculate blow-by gas through the inside of a cylinder head cover. Related to equipment.

[Prior Art] Blowby gas recirculation devices are known that recirculate unburned gas (hereinafter referred to as blowby gas) leaked from the gap between the piston and the cylinder during the compression stroke of the engine to the intake system of the engine (for example, , Utsukai Showa 59-
No. 71929). As explained in the publication, the blow-by gas is stored in the crank chamber, which is formed by the crank case of the cylinder block and the oil pan, in which the crankshaft is rotatably supported. Here, the crank chamber communicates with the internal chamber of the cylinder head cover, which accommodates valve train components that open and close the intake and exhaust valves and communicates with the inside of the intake passage, through a communication hole that passes through the cylinder block and the cylinder head. The blow-by gas is returned to the intake system from the communication hole via the cylinder head cover internal chamber. In particular, in the device disclosed in the above publication, an attempt was made to open the discharge port of the pump, which is one of the auxiliary parts installed in the internal combustion engine, into the internal chamber of the cylinder head cover so as not to increase the internal pressure in the crank chamber. The oil used to lubricate the valve train parts is quickly passed through the communication hole and returned to the oil pan.

[The problem that the idea aims to solve]

By the way, as the engine starts operating at high speed, the amount of blow-by gas increases and the pressure in the crank chamber increases. For this reason, even if the internal chamber of the cylinder head cover is pressurized by a pump like the device in the above publication, the increase in pressure in the crank chamber prevents the lubricating oil from passing through the communication hole and There still remains the problem that oil tends to accumulate inside the head cover and the oil accumulated there is carried away by the blow-by gas flow.

Therefore, the technical problem of the present invention is to suppress the pressure rise in the crank chamber when forcibly returning the oil that tends to accumulate in the internal chamber of the cylinder head cover to the oil pan, and to reduce the amount of oil carried away by the blow-by gas reflux. The goal is to reduce the amount.

[Means to solve the problem]

In order to solve the above technical problem, the present invention provides a communication passage that communicates between the crank chamber, in which the crankshaft is pivotally supported, and the internal chamber of the cylinder head cover, in which the valve train parts that open and close the intake and exhaust valves are housed. The lubricating oil accumulated in the internal chamber of the cylinder head cover is returned to the crank chamber through the communication passage, and the blow-by gas accumulated in the crank chamber is guided to the internal chamber of the cylinder head cover and returned to the intake passage. In the blow-by gas recirculation device for an internal combustion engine, the communication path is such that a suction port of a pump driven using a part of the engine output is opened in the crank chamber, and a discharge port is opened in the internal chamber of the cylinder head cover. The engine is characterized in that it includes a first communication passage consisting of a first communication passage, and a second communication passage that communicates the crank chamber and the cylinder head cover internal chamber in parallel with the first communication passage.

[Effect]

According to this means, the blow-by gas in the crank chamber is sucked into the first communication passage by the action of the pump, and is discharged from the first communication passage into the cylinder head cover internal chamber. This blow-by gas flow reduces the pressure in the crank chamber and increases the pressure in the cylinder head cover internal chamber, so the lubricating oil accumulated inside the cylinder head cover is The oil is forcibly returned to the oil pan through the second communication path.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

As shown in Fig. 1, a cylinder block 4 and a cylinder head cover 5 are attached to the cylinder head 1 with gaskets 2 and 3 in between, and an oil pan 6 is attached to the cylinder block 4 to form the main body of the diesel engine. It is configured. Here, the cylinder block 4 includes a cylinder portion 12 on which the piston 7 slides, and a skirt portion 13 whose width gradually increases from the cylinder portion 12 toward the oil pan 6.
It is divided into A crank chamber 9 in which a crankshaft 8 is housed is formed by the skirt portion 13 and the oil pan 6. Incidentally, the crankshaft 8 is connected to the piston 7 via a connecting rod 10.

Next, the cylinder head 1 is formed with an intake port 11 forming part of an intake passage and an exhaust port (not shown) forming part of an exhaust passage. An intake valve 14 capable of blocking the flow of air passing through the intake port 11 is provided at the passage opening of the intake port 11 into the bore 12a of the cylinder portion 12.
1 so that its shaft 14a penetrates through the wall of the exhaust port 1 (an exhaust valve is similarly installed for the exhaust port). The intake valve 14 is opened and closed by valve train components housed in a cylinder head cover internal chamber 15 formed by the cylinder head cover 5 and the cylinder head 1. Valve train parts are
A camshaft 16 rotates at half the rotational speed of the crankshaft 8, and a shaft 1 of the camshaft 16 and the intake valve 14 is pivotably supported with the center as a fulcrum.
It consists of a locking arm 17 whose both ends are in contact with the end of the locking arm 4a. In this manner, when the camshaft 16 rotates, the rocker arm 17 swings, the intake valve 14 slides against the force of the spring 18, and the passage opening of the intake port 11 is opened. Here, lubricating oil pumped up by an oil pump (not shown) is supplied to the sliding parts of the valve train parts.
This oil passes through the cylinder head 1 and the cylinder block 4 and enters the cylinder head cover inner chamber 1.
5 and the crank chamber 9, and is returned to the oil pan 6.

Incidentally, in the cylinder head cover internal chamber 15, a separation chamber 21 is divided from a space in which valve train components are housed by a shielding plate 20 having a small hole 23 for ventilation. This separation chamber 21 is connected to an intake manifold 3 which is connected to the intake port 11 via a hose 22.
It communicates with the interior of 1. In addition, a discharge port 24a of a vacuum pump 24, which is normally installed in a diesel engine, is connected to a conduit 25 in the cylinder head cover internal chamber 15, excluding the separation chamber 21.
It opens through. On the other hand, the suction port 24b of the vacuum pump 24 is connected to the crank chamber 9 via a conduit 26 in addition to the devices to which negative pressure is supplied.
It is also open to the public. In addition, vacuum pump 24
pipe 3 carries part of the lubricating oil flowing inside the engine.
It is supplied from 2. Here, a trapper 27 having a certain capacity is provided in the middle of the conduit 25, and the trapper 27 and the crank chamber 9 communicate with each other via a conduit 28. The vacuum pump 24 is driven by a belt 30 being wound around its pulley 24c and a pulley 29 attached to the shaft end of the crankshaft 8.

As described above, the blow-by gas accumulated in the crank chamber 9 is sucked by the vacuum pump 24 through the conduit 26 and is discharged through the conduit 25 into the cylinder head cover internal chamber 15.
At this time, the oil contained in the blow-by gas is separated by the trapper 27, and the separated oil is
It is returned to the crank chamber 9 via a conduit 28. The blow-by gas that has flowed into the cylinder head cover internal chamber 15 is further separated from the oil remaining in the gas without being separated by the trapper 27 in the separation chamber 21 and sent to the intake manifold 31.

In the above configuration, the vacuum pump 24,
Its discharge port 24a, suction port 24b, conduit 25, 2
6 etc. correspond to the configuration of the first communication path of the present invention, and the communication hole 19 corresponds to the second communication path.

In this embodiment, the blow-by gas in the crank chamber is guided to the cylinder head cover internal chamber 15 via the conduit 26, the vacuum pump 24, and the conduit 25, so the internal pressure of the crank chamber 9, which is on the suction side of the vacuum pump 24, is Cylinder head cover internal chamber 15 corresponding to the discharge side of the vacuum pump 24
The oil supplied to lubricate the valve train parts is forcibly returned to the crank chamber 9 through the communication hole 19, making it difficult for oil to accumulate in the cylinder head cover internal chamber 15. It's summery.
Therefore, the amount of oil carried away to the intake manifold 24 and consumed by the flow of blow-by gas passing through the cylinder head cover internal chamber 15 can be suppressed to a small amount.

Another embodiment is shown in FIG. 2, in which a conduit 41 is provided on the suction side of the vacuum pump 24 leading to a vacuum tank 40 for storing negative pressure to be supplied to each device operated by air pressure. A valve device 4 is installed at the confluence with the conduit 26 that opens into the crank chamber 9.
2 is installed. The rotation speed of this valve device 42 is controlled by a control unit 43. In this case, the internal pressure of the crank chamber 9 increases and the cylinder head cover internal chamber 15 rotates at high speed.
When oil tends to accumulate in the engine, the conduit 26 is opened by the valve device 42, and the oil is forcibly sucked into the crank chamber 9 through the communication hole 19. By limiting the opportunity to use the negative pressure from the vacuum pump 24 in this way, the vacuum pump 24
Care has been taken to ensure that there is no adverse effect on the operation of each device that is receiving negative pressure from 4.

Here, the valve device 42 is controlled by detecting the engine speed, but it may also be controlled by detecting the engine load or the internal pressure of the crank chamber 9, which causes oil to easily accumulate in the cylinder head cover internal chamber 15.

[Effect of idea]

As is clear from the above embodiments, according to the measures taken by the present invention, the crank chamber is forcibly ventilated by the first communication path, and the internal pressure of the crank chamber is kept lower than the internal pressure of the cylinder head cover. As a result, the oil lubricating the valve train components can be forcibly returned to the crank chamber through the second communication path, and the amount of lubricating oil remaining in the internal chamber of the cylinder head cover can be reduced. Therefore, oil carried away due to blow-by gas reflux can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing a blow-by gas recirculation device for an internal combustion engine according to an embodiment of the present invention;
FIG. 1 is a cross-sectional view schematically showing a blow-by gas recirculation device for an internal combustion engine according to another embodiment of the present invention. 8...Crankshaft, 9...Crank chamber,
14... Intake valve, 15... Cylinder head cover internal chamber, 19... Communication hole, 24... Vacuum pump, 24a... Discharge port, 24b... Suction port.

Claims (1)

[Scope of Claim for Utility Model Registration] A communication passage is provided that communicates between the crank chamber in which the crankshaft is pivotally supported and the internal chamber of the cylinder head cover in which the valve train parts that open and close the intake and exhaust valves are housed. A blow-by gas of an internal combustion engine in which the lubricating oil accumulated in the cylinder head cover internal chamber is returned to the crank chamber, and the blow-by gas accumulated in the crank chamber is guided to the cylinder head cover internal chamber and returned to the intake passage. In the recirculation device, the communication passage is a first communication passage formed by opening a suction port of a pump driven using part of the engine output into the crank chamber and opening a discharge port into the internal chamber of the cylinder head cover. A blow-by gas recirculation device for an internal combustion engine, comprising a passage, and a second communication passage that communicates the crank chamber and the cylinder head cover internal chamber in parallel with the first communication passage.