JPH08326520A - Blow-by gas ventilating device for internal combustion engine - Google Patents

Abstract

PURPOSE: To improve ventilating performance in a crank chamber so as to suppress the generation of oil deterioration. CONSTITUTION: A blow-by gas exhaust passage 23B between a crank chamber 12A and a locker chamber 15A is provided on the inside of an engine E body end part positioned on the opposite side to an engine E body end part where a chain case 22 is formed. A blow-by gas exhaust port 25 is provided in the upper wall position of a locker cover 15 corresponding to the position of the blow-by gas exhaust passage 23B. A fresh air lead-in port 27 is provided more on the chain case 22 side than the middle part in the cylinder row direction of the locker cover 15 so as to prevent fresh air from being exhausted to an intake manifold along with blow-by gas. The inside of the crank chamber 12A can thereby be ventilated sufficiently, and the locker chamber 15A is not filled with blow-by gas so as to obtain an excellent ventilated state filled with almost fresh air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow-by gas ventilator for an internal combustion engine, and more particularly to a technique for improving ventilation in a crank chamber to prevent deterioration of oil due to blow-by gas.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine (hereinafter referred to as an engine), as a device for ventilating blow-by gas discharged from the inside of a crankcase, for example, a closed type ventilation device as shown in FIG. 4 is known. [TOYO
TA SCEPTER New Car Manual (1992, 1
1) P2-35].

In this engine, the blow-by gas discharged in the crank chamber 1 is discharged to the intake manifold 2, and at the same time, fresh air is introduced from the intake duct 3 or the air cleaner 4 into the engine body, that is, into the rocker chamber 5 and the crank chamber 1.
By introducing the gas into the engine body, the concentration of blow-by gas inside the engine body is reduced and oil deterioration due to the blow-by gas is prevented. Specifically, it is configured as follows.

That is, blow-by gas discharge passages 6a and 6b are provided which connect the intake manifold 2 of the engine E and the crank chamber 1 via the rocker chamber 5. Blow-by gas discharge passage 6 between engine E and intake manifold 2
A blow-by gas control valve (PCV valve) 8 is interposed in the blow-by gas discharge port 7 which is a connection portion with the rocker chamber 5 of a.

On the other hand, the intake duct 3 downstream of the air cleaner 4
A fresh air introduction passage 9 that connects the locker chamber 5 and the locker chamber 5 is provided. A fresh air introduction port 10 serving as a connection portion of the fresh air introduction passage 9 with the rocker chamber 5 is provided in the vicinity of the blow-by gas discharge port 7. In such a configuration, the engine E
During low load operation of the blow-by gas, the blow-by gas released in the crank chamber 1 passes from the blow-by gas discharge passage 6a through the PCV valve 8 to the blow-by gas discharge passage 6b by the action of the negative pressure in the intake manifold 2, While being discharged to the intake manifold 2, fresh air is introduced into the rocker chamber 5 through the fresh air introduction passage 9 and is introduced into the crank chamber 1 through the rocker chamber 5.

[0006] In such a structure, there is an advantage that the amount of oil taken out at the time of discharging the blow-by gas is small compared with the structure in which the blow-by gas discharge passage and the fresh air introduction passage are installed in the crank chamber. That is, since the amount of oil mist generated in the rocker chamber 5 is smaller than that in the crank chamber 1, the negative pressure in the intake manifold 2 is reduced under normal operating conditions and high load operation, and the blow-by gas is blown from the fresh air introduction passage. Even under the condition of reverse flow of oil, the amount of oil taken out when the blow-by gas is discharged becomes small.

[0007]

However, in such a conventional blow-by gas ventilation device, the blow-by gas discharge passage 6 between the crank chamber 1 and the rocker chamber 5 is provided.
b is formed integrally with the engine E, its passage area is small, and both the fresh air introduction port 10 and the blow-by gas discharge port 7 are provided close to each other.
There are the following problems.

That is, the fresh air introduced into the rocker chamber 5 is
Although it is introduced into the crank chamber 1 through the rocker chamber 5, the fresh air introduced into the rocker chamber 5 is difficult to flow toward the crank chamber 1 and short-circuits to the blow-by gas discharge port 7,
The blow-by gas is discharged to the intake manifold 2. For this reason, there is a problem that the ventilation in the crank chamber 1 is not sufficiently performed, the amount of NOx mixed in the blow-by gas into the oil increases, and the oil easily deteriorates.

In FIG. 4 described above, the solid arrow indicates the flow of blow-by gas, and the dotted arrow indicates the flow of fresh air. In view of the above conventional problems, the present invention is
By improving the formation part of the blow-by gas discharge passage and its arrangement, it is easier for fresh air introduced into the rocker chamber to flow toward the crank chamber, which improves ventilation in the crank chamber and suppresses oil deterioration. The purpose is to

[0010]

For this reason, the invention according to claim 1 is an internal combustion engine having a chain case containing a timing chain for driving a camshaft.
An internal combustion engine equipped with a blow-by gas discharge passage for introducing blow-by gas into the intake system through the rocker chamber by the negative pressure of the intake system and a fresh air introduction passage for introducing fresh air from the intake system into the rocker chamber In the blow-by gas ventilation device, a blow-by gas discharge passage between the crank chamber and the rocker chamber is provided inside the engine body end portion opposite to the engine body end portion where the chain case is formed, and the crank chamber is provided. The blow-by gas discharge port of the blow-by gas discharge passage between the rocker chamber and the rocker chamber is provided at the rocker cover upper wall position corresponding to the blow-by gas discharge passage position, while the fresh air introduction port of the fresh air introduction passage is connected to the rocker cover. It is arranged at a position closer to the chain case than an intermediate portion in the cylinder row direction of.

According to a second aspect of the present invention, fresh air introduced into the rocker chamber when the camshaft is rotated is introduced into the crank chamber of the cam sprocket connected to the camshaft and wound around the timing chain. A fin is provided to generate an air flow that is sent to the.

[0012]

In the invention described in claim 1, the fresh air from the intake system introduced into the rocker chamber through the fresh air inlet diffuses into the rocker chamber, but the fresh air inlet is in the cylinder row direction of the rocker cover. Since it is located closer to the chain case than the middle part, the fresh air flows toward the chain case.

The blow-by gas discharged into the crank chamber is sucked by the negative pressure of the intake system and is discharged from the crank chamber into the intake system via the blow-by gas discharge port. In this case, the blow-by gas discharge passage between the crank chamber and the rocker chamber is provided inside the engine body end opposite to the engine body end where the chain case is formed, and the blow-by gas discharge port is Since the blow-by gas is provided at the rocker cover upper wall position corresponding to the blow-by gas discharge passage position, the blow-by gas sucked is mainly the blow-by gas from the crank chamber.

The flow of fresh air and blow-by gas as described above, when viewed as a whole in the engine main body, is a flow from the rocker chamber to the crank chamber on the chain case side, and blow-by at the end of the engine main body on the side opposite to the chain case. In the gas discharge passage, the flow is from the crank chamber to the rocker chamber, and the fresh air introduced into the rocker chamber smoothly flows toward the crank chamber and does not flow in a short circuit to the blow-by gas discharge port. Along with the gas, it can be prevented from being discharged into the intake system, and the crank chamber is well ventilated, and the rocker chamber is not filled with blow-by gas, and is in good ventilation with almost fresh air. Becomes

In the invention according to claim 2, since the cam sprocket rotates and the fins provided on the cam sprocket rotate, the fresh air on the rear side of the sprocket is sent to the chain case and introduced into the rocker chamber. Most of the fresh air that has been released is sent from the inside of the chain case into the crank chamber.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. 1 and 2, which will be described below, the black arrow indicates the flow of blow-by gas, and the white arrow indicates the flow of fresh air. In these figures, in the crankcase 12 below the cylinder block 11 of the engine E,
Bulk part 11 supporting the main bearing 14 of the crankshaft 13
A plurality of A are provided corresponding to each cylinder # 1 to # 4.
In this case, each bulk portion 11A is integrally molded with the cylinder block 11.

On the other hand, in the cylinder head 16 provided with the rocker cover 15, a pair of overhead cam shafts 17 is provided.
A pair of cam sprockets 18 fixed to
A crank sprocket 19 fixed to the crank shaft 13 is provided in the cylinder block 11. A timing chain 20 is wound around the pair of cam sprocket 18 and crank sprocket 19.

The engine E main body has a cylinder block 1
A chain case 22 composed of a wall 11 a of No. 1 and a front cover 21 is provided adjacent to the crank case 12, and the timing chain 2 is provided in the chain case 22.
0 is allocated. Here, the blow-by gas discharge passage 23 for guiding the blow-by gas in the crank chamber 12A of the crank case 12 to the intake system (intake manifold) via the rocker chamber 15A of the rocker cover 15 by the negative pressure of the intake system.
A and 23B and a fresh air introduction passage 24 for introducing fresh air from the intake system (intake duct) into the rocker chamber 15A are provided.

The crank chamber 12A and the rocker chamber 15
The blow-by gas discharge passage 23B between the crankcase 12A and the rocker chamber 15A is provided inside the engine E main body end opposite to the engine E main body end where the chain case 22 is formed. Blow-by gas discharge port 2 of blow-by gas discharge passage 23B between
5 is provided at the upper wall position of the rocker cover 15 corresponding to the position of the blow-by gas discharge passage 23B. A PCV valve 26 is provided at the blow-by gas outlet 25.

The fresh air introduction port 27 of the fresh air introduction passage 24
Is provided at a position closer to the chain case 22 than an intermediate portion of the rocker cover 15 in the cylinder row direction. The timing chain 2 is connected to the camshaft 13
On the cam sprocket 18 around which 0 is wound, an air flow is generated so that fresh air introduced into the rocker chamber 15A when the camshaft 13 rotates is sent to the crank chamber 12A through the inside of the chain case 22. A fin is provided.

In this case, as shown in FIG. 3, concave portions 18A and convex portions 18B are formed on both end surfaces of the cam sprocket 18 at predetermined intervals along the circumferential direction, respectively. A fin is composed of the concave portion 18A and the convex portion 18B. Next, the operation of this configuration will be described. The fresh air from the intake duct introduced into the rocker chamber 15A from the fresh air inlet 27 diffuses into the rocker chamber 15A, but the fresh air inlet 27 is located at an intermediate portion of the rocker cover 15 in the cylinder row direction. Since it is provided near the chain case 22, fresh air
Flows toward. In addition, since the cam sprocket 18 rotates and the fins provided on the cam sprocket 18 rotate, the fresh air on the rear side of the cam sprocket 18 is sent to the chain case 22 and introduced into the rocker chamber 15A. Most of them are sent from the chain case 22 into the crank chamber 12A.

The crank chamber 12 is generated in the cylinder portion.
The flow rate of the blow-by gas released into A is controlled by the PCV valve 26 due to the negative pressure of the intake manifold, sucked, and led out from the inside of the crank chamber 12A to the intake manifold via the blow-by gas discharge port 25. . In this case, crank chamber 12A and rocker chamber 15A
The blow-by gas discharge passage 23B between the blow-by gas discharge passage 25 and the blow-by gas discharge passage 23B is provided inside the end of the engine E main body located on the opposite side of the end of the engine E main body where the chain case 22 is formed. Since it is provided at the upper wall position of the rocker cover 15 corresponding to the position of the passage 23B, the blow-by gas sucked is mainly the blow-by gas from the crank chamber 12A.

The flow of fresh air and blow-by gas as described above, when viewed as a whole inside the engine E main body, from the rocker chamber 15A to the crank chamber 12 on the chain case 22 side.
In the blow-by gas discharge passage 23B at the end of the engine E main body on the side opposite to the chain case 22, the flow is in the direction from the crank chamber 12A to the rocker chamber 15A, and the fresh air introduced into the rocker chamber 15A is in the crank chamber 12A. Since it flows smoothly toward the blow-by gas discharge port 25 and does not short-circuit to the blow-by gas discharge port 25, it is possible to prevent fresh air from being discharged to the intake manifold together with the blow-by gas, and the ventilation in the crank chamber 12A is sufficient. At the same time, the rocker chamber 15A is not filled with blow-by gas and is in a good ventilation state substantially filled with fresh air.

As a result, the amount of NOx mixed in the blow-by gas into the oil can be reduced, and the deterioration of the oil can be prevented as much as possible.

[0025]

As described above, according to the first aspect of the invention, the fresh air introduced into the rocker chamber can smoothly flow toward the crank chamber and short-circuit to the blow-by gas discharge port. Because there is no fresh air with blow-by gas,
You can prevent it from being discharged to the intake manifold,
The crank chamber is well ventilated, and the rocker chamber is not filled with blow-by gas and is in a good ventilation state filled with almost fresh air, and NOx in the blow-by gas is hardly mixed into the oil. It is possible to prevent deterioration of oil as much as possible.

According to the second aspect of the present invention, the cam sprocket generates an air flow in which fresh air introduced into the rocker chamber when the camshaft rotates is sent to the crank chamber through the chain case. Since the fins are provided, most of the fresh air introduced into the rocker chamber can be sent from the inside of the chain case into the crank chamber, and the ventilation in the crank chamber can be further improved.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the invention described in claims 1 and 2.

FIG. 2 is a front sectional view of the same embodiment as above.

3A and 3B are views showing a configuration of a cam sprocket in the above-mentioned embodiment, wherein FIG. 3A is a plan view and FIG. 3B is AA in FIG.
Sectional view

FIG. 4 is a schematic diagram showing a conventional blow-by gas ventilation device for an internal combustion engine.

[Explanation of symbols]

 E Engine 12 Crankcase 12A Crank chamber 15 Rocker cover 15A Rocker chamber 18 Cam sprocket 18A Recessed portion 18B Convex portion 22 Chain case 23B Blow-by gas discharge passage 24 Fresh air introduction passage 25 Blow-by gas discharge outlet 27 Fresh air introduction inlet

Claims (2)

[Claims] 1. An internal combustion engine having a chain case containing a timing chain for driving a camshaft, wherein a blow-by gas exhaust passage for discharging blow-by gas in a crank chamber to an intake system via a rocker chamber by negative pressure in the intake system. In a blow-by gas ventilator for an internal combustion engine, which has a fresh air intake passage for introducing fresh air from the intake system into the rocker chamber, a chain case forms a blow-by gas discharge passage between the crank chamber and the rocker chamber. The blow-by gas exhaust port of the blow-by gas exhaust passage between the crank chamber and the rocker chamber is provided inside the end of the engine main body located on the side opposite to the end of the engine main body. While installing at the corresponding rocker cover upper wall position, the fresh air introduction port of the fresh air introduction passage should be Blowby gas ventilation system for an internal combustion engine than the intermediate portion of the column, characterized in that provided at the position of the chain case closer. 2. Fresh air introduced into the rocker chamber when the camshaft is rotated is fed to a crank chamber connected to the camshaft and around which the timing chain is wound. The blow-by gas ventilation device for an internal combustion engine according to claim 1, wherein fins for generating such an air flow are provided.