JP2001317324A - Blowby gas disposal device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contamination of an intake system due to oil mist in blowby gas and increase of oil consumption by properly circulating blowby gas in consideration of a pressure difference of a valve chest of each bank of an engine having a plural number of the banks. SOLUTION: A chain chamber 84 is communicated to a crankcase 82 through a blowby gas discharge port 97 provided on a connecting part between an LH cylinder block 2a and an RH cylinder block 2b at an upper part of the crankcase 82. Thereafter, only the valve chest 80 of the LH cylinder heat 3a on which pressure of the valve chest becomes relatively high in accordance with the rotating direction of timing chains 90, 95 when driving the engine in the case of using the chain chamber 84 as a return passage of oil from the valve chest. Additionally, a fresh air introduction passage 47 is connected only to the side of the valve chest 80 of the LH cylinder heat 3a, and a blowby gas passage 46 in which a PCV valve 45 is interposed through a breather device 99 is connected to it.

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 processing device for an engine having a plurality of banks, and more particularly, to a blow-by gas for an engine for preventing contamination of an intake system and an increase in oil consumption due to oil mist in the blow-by gas. It relates to a processing device.

[0002]

2. Description of the Related Art Generally, blow-by gas generated in a crankcase of an engine is recirculated to an intake system by a blow-by gas processing device and is subjected to a reburn process. In this blow-by gas processing apparatus, fresh air is introduced into the crank chamber from the intake passage upstream of the throttle valve via the valve operating chamber, and blow-by gas is recirculated from the valve operating chamber to the intake passage downstream of the throttle valve. .

For example, Japanese Patent Application Laid-Open No. 8-158854 discloses that a fresh air introduction passage for introducing fresh air from an intake system is provided in one cylinder head cover of a V-type engine.
There is disclosed a technique in which a gas supply passage for supplying gas (blow-by gas) in the other cylinder head cover to an intake system is provided, and a plurality of breather chambers communicating with a crank chamber are formed between cylinder banks.

[0004]

However, in an engine having a plurality of banks, such as a horizontally opposed engine and a V-type engine, the camshaft of a valve operating chamber formed in the cylinder head of each bank is rotated in synchronization with the crankshaft. Using a transmission mechanism such as a driven timing chain, a chain chamber accommodating the timing chain is used as an oil return passage communicating the valve train chamber and the oil reservoir chamber, and simultaneously lubricating necessary lubrication parts in the chain chamber. As a result, a pressure difference may occur between the valve train of one bank and the valve train of another bank depending on the rotation direction of the timing chain during engine operation.

For this reason, if it is attempted to recirculate blow-by gas from the valve operating chamber on the lower side of the internal pressure to the intake passage downstream of the throttle valve, the intake pipe downstream of the throttle valve during high load operation or the like in which a large amount of blow-by gas is generated. In an operation region where the pressure is close to the atmospheric pressure, the amount of fresh air introduced into the crankcase increases, and the amount of recirculated blow-by gas scavenged by the fresh air increases beyond an appropriate amount. For this reason, a large amount of blow-by gas in which the oil mist is not sufficiently separated may flow back to the intake system, which may cause problems such as contamination of the intake system and an increase in oil consumption.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and appropriately recirculates blow-by gas in consideration of a pressure difference between valve operating chambers of each bank of an engine having a plurality of banks, and uses an oil mist in the blow-by gas. It is an object of the present invention to provide an engine blow-by gas processing device capable of preventing intake system contamination and increase in oil consumption.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a plurality of banks are provided, and a cam shaft provided in a valve chamber of each bank is synchronized with a crankshaft. It has a storage chamber that houses a transmission mechanism that rotates and drives the transmission mechanism so that it can be lubricated with oil, and blow-by gas of the engine that uses this storage chamber as a return passage for oil from the valve train chamber is introduced into the intake system by introducing fresh air. A blow-by gas processing device for an engine that recirculates and recombustes an engine, wherein an upper portion of the storage chamber is communicated with a crank chamber, and an internal portion of the valve operating chamber of each bank depends on a rotation direction of the transmission mechanism during engine operation. A blow-by gas passage through which only the valve operating chamber whose pressure is relatively high communicates with the housing chamber and the blow-by gas is returned to the intake system through the valve operating chamber whose internal pressure is relatively high. Characterized in that it connects.

According to a second aspect of the present invention, in the first aspect of the present invention, a fresh air introduction passage for introducing fresh air is connected to the valve operating chamber to which the blow-by passage is connected.

That is, according to the first aspect of the present invention, when the blow-by gas of an engine having a plurality of banks is recirculated to the intake system, the transmission chamber for storing the transmission mechanism for rotating the cam shaft in synchronization with the crank shaft is stored. By recirculating the blow-by gas from the valve chamber, the internal pressure of which is relatively high due to the flow of oil due to the rotation direction of the transmission mechanism of the transmission mechanism, the amount of blow-by gas recirculation is appropriately maintained, and the intake system is contaminated by oil mist. Prevent an increase in oil consumption.

According to the second aspect of the present invention, the fresh air introduction passage and the blow-by gas passage are simultaneously connected to the valve operating chamber for recirculating the blow-by gas, so that the piping system can be made compact.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to an embodiment of the present invention, FIG. 1 is an overall configuration diagram of an engine system, and FIG.
FIG. 3 is a front view of a valve element viewed from the tip end side of a shaft part, FIG. 4 is an explanatory view schematically showing a blow-by gas passage system inside an engine, and FIG. It is explanatory drawing of a rotation transmission drive system.

In FIG. 1, reference numeral 1 denotes an engine having a plurality of banks, and in this embodiment, a horizontally opposed six-cylinder engine. The cylinder block 2 of the engine 1 is divided into two banks on both sides of the crankshaft 1a. An intake port 4 and an exhaust port 5 are formed in the cylinder head 3 of each bank. An intake manifold 6 is communicated with the intake port 4 of each cylinder, and the intake manifolds 6 of each cylinder of each bank are assembled and communicated with the intake chambers 7a and 7b. Further, a variable intake valve 8 which is opened and closed by an actuator 9 is interposed in a passage communicating with the intake chambers 7a and 7b of each bank.

The actuator 9 is connected to a negative pressure tank 11 which communicates with one of the intake chambers 7a via a one-way valve 10. A switching solenoid valve provided in a passage connecting the actuator 9 and the negative pressure tank 11 is provided. 1
2, the operating pressure introduced into the actuator 9 is switched between negative pressure and atmospheric pressure in accordance with the engine operating range.

The intake chamber 7 corresponding to each bank
a, 7b, passages 13a, 13b extend upstream from respective positions on both sides of the variable intake valve 8, and these passages 13a, 13b
a and 13b collectively communicate with a throttle chamber 15 in which a throttle valve 14 interlocked with an accelerator pedal is interposed so that intake air is evenly distributed to each bank. An intake pipe 17 is connected to an upstream side of the throttle chamber 15 via an air chamber 16, and an air cleaner 18 is attached to an upstream side of the intake pipe 17. A chamber 19 communicates with the air intake passage connected to the air cleaner 18.

Further, a bypass passage 20 for bypassing the throttle valve 14 is connected to the throttle chamber 15. The bypass passage 20 is provided with an idle control valve (ISC valve) 21 that constitutes an idle control device that controls the idle speed. The ISC valve 21 adjusts the air flow rate of the bypass passage 20.

A spark plug 22 for exposing the discharge electrode portion to the combustion chamber is attached to each cylinder of the cylinder head 3, and an air assist is provided immediately upstream of the intake port 4 of each cylinder of the intake manifold 6. An injector 25 is provided. In the air assist injector 25,
Fuel is supplied through a fuel supply passage 27 extending from the fuel tank 26, and the atomization of the injected fuel is promoted in a low rotation speed and low load region through an air assist passage 28 extending from the ISC valve 21. Assist air is introduced to perform the operation.

An in-tank type fuel pump 30 is provided in the fuel tank 26, and the fuel from the fuel pump 30 is supplied to the air assist injector 25 through a fuel supply path 27.
The pressure is fed to the pressure regulator 31, the excess fuel is returned from the pressure regulator 31 to the fuel tank 26, and the fuel pressure of the fuel supply system to the air assist injector 25 is adjusted to a predetermined pressure.

Further, a first purge passage 32 extends from the upper portion of the fuel tank 26 to purge the fuel vapor generated in the fuel tank 26 into the intake system.
3, and is communicated with an upper portion of a canister 34 having an adsorbing portion made of activated carbon or the like. The canister 34 is provided at its lower part with a fresh air inlet communicating with the atmosphere, and a second purge for introducing a mixture (evaporative gas) of fresh air from the fresh air inlet and the evaporated fuel gas stored in the adsorption section. A passage 35 extends from the top.

The second purge passage 35 is provided with the throttle valve 1
4, the passages 13 a, 13 communicating from the throttle chamber 15 to the intake chambers 7 a, 7 b of each bank.
An opening is provided in the intake system at a location substantially upstream and at the center of the branch portion 13c that branches to the path b. In the middle of the second purge passage 35, a canister purge control (CPC) duty solenoid valve whose valve opening is controlled in accordance with the duty ratio of the drive signal in order to control the purge ratio of evaporated fuel to intake air. 36, and this CP
On the upstream side of the C-duty solenoid valve 36, a chamber 37 for silencing airflow noise and pulsation noise generated when the CPC duty solenoid valve 36 operates is provided.

On the other hand, the exhaust ports 5 of the cylinder head 3 of the engine 1 are gathered in the cylinder head 3 for each bank and communicated with the exhaust pipe 38, and the exhaust pipe 38 of each bank is provided.
In addition, a catalytic converter 39 containing a three-way catalyst is interposed, and a catalytic converter 40 also containing a three-way catalyst is interposed in a collecting portion of the exhaust pipe 38 of each bank. 42.

Also, EG is supplied from the exhaust pipe 38 of one bank.
An R (exhaust gas recirculation) passage 43 extends, and passages 13a, 13 extending from intake chambers 7a, 7b of each bank.
3b. In the middle of the EGR passage 43, E
An EGR valve 44 for adjusting the GR amount is interposed, and a part of the exhaust gas is recirculated to the intake system according to the degree of opening of the EGR valve 44.

Further, the cylinder head 3 of one bank
A positive crankcase ventilation (PCV) valve 45, which is a flow control valve for controlling the flow rate of blow-by gas when recirculating blow-by gas generated in the crankcase to the intake system, is attached.
A blow-by gas passage 46 opening downstream of the throttle valve 14 is connected to the V valve 45. A throttle valve 14 is provided in the cylinder head 3 near the PCV valve 45 to introduce fresh air for scavenging into the crank chamber and the valve operating chamber.
A fresh air introduction passage 47 communicating with the air chamber 16 is connected as an upstream side of the air chamber 16.

The PCV valve 45 is, as shown in FIG.
In the valve body 70, a valve body 71 including a straight shaft portion 71a and a flange portion 71b serving as a seat for a spring 72 is housed. One side of the valve body 70 is screwed to the cylinder head cover 3a of the cylinder head 3, and the other side is connected to a pipe 46a forming a blow-by gas passage 46 also as a connector.

Inside the valve body 70, a spring chamber 70a for accommodating the valve body 71 and the spring 72, and the inner diameter of the spring chamber 70a is reduced so that the shaft portion 71a of the valve body 71 is slidable on the distal end side. Body supporting part 7 to be supported
0b is formed. The spring chamber 70a is arranged on the side that is screwed into the cylinder head cover 3a, and when the spring chamber 70a extends from the valve body support 70b to the connector, the inner diameter is increased on the connector side.

Inside the spring chamber 70a, a spring 72 is provided between a step portion from the spring chamber 70a to the valve body support portion 70b and a flange portion 71b of the valve body 71 in which the shaft portion 71a is inserted through the valve body support portion 70b. A disk-shaped plate 73 having a hole serving as a blow-by gas inflow port opened at the center is fixed to the end on the cylinder head side by caulking or the like. Further, the valve body support 70 b is provided with the valve body 7.
1 is the initial position of stroke 0 (cylinder head cover 3
(a rearmost position on the a side), and is formed to have a length capable of supporting the shaft portion 71a.

The flow rate of the blow-by gas flowing from the opening of the plate 73 is adjusted by a throttle 74 formed at the position of the valve support 70b. The opening area of the throttle unit 74 changes according to the stroke of the valve body 71. In the present embodiment, the throttle unit 74 is connected to the valve body 71 as shown in FIG.
And a groove 71c provided in the longitudinal direction along the shaft portion 71a. The groove 71c has a tapered groove bottom whose groove depth becomes shallower from the distal end side of the shaft portion 71a toward the base side (the flange portion 71b side). The opening area of the body supporting portion 70b changes, and the flow rate of the blow-by gas is adjusted.

That is, the difference between the intake pipe pressure downstream of the throttle valve 14 and the pressure on the blow-by gas inlet side is small,
When the flange portion 71b side of the valve body 71 moves in the direction away from the valve body support portion 70b side by the urging force of the spring 72, the groove depth of the groove 71c of the shaft portion 71a at the position of the valve body support portion 70b increases, The opening area of the throttle portion 74 formed by the groove 71c increases, and the flow rate of blow-by gas increases. On the other hand, the difference between the intake pipe pressure downstream of the throttle valve 14 and the pressure on the blow-by gas inlet side is large, and the flange portion 71b side of the valve body 71 is
When moving in the direction approaching the valve body support 70b against the urging force of the shaft 71, the shaft 71 at the position of the valve body support 70b
The groove depth of the groove 71c becomes shallow, the opening area of the narrowed portion 74 formed by the groove 71c becomes small, and the flow rate of the blow-by gas decreases.

Here, the blow-by gas passage system inside the engine 1 will be described with reference to FIG. Specifically, the cylinder block 2 of the engine 1 is separated into a left bank side (hereinafter abbreviated as “LH”) and a right bank side (hereinafter abbreviated as “RH”) extending in the left-right direction. LH cylinder block 2a and RH centering on crankshaft 1a
It is composed of a cylinder block 2b. LH, RH
LH cylinder head 3a and RH cylinder head 3b are attached to cylinder blocks 2a and 2b, respectively.
LH valve chamber 8 formed in each cylinder head 3a, 3b
0 and the RH valve chamber 81 are respectively
a, 3b and LH, RH cylinder blocks 2a, 2b
Are communicated with the crank chamber 82 through the passages 2c and 2d formed in the first and second passages.

At the front of the engine 1, there is provided a chain case 83 composed of a back cover 83a attached to the wall side of the cylinder block 2 and a front cover 83b attached to the back cover 83a. I have. A chain chamber 84 is formed inside the chain case 83 as a housing chamber for housing a chain constituting a transmission mechanism that rotates the camshafts of the valve operating chambers 80 and 81 in synchronization with the crankshaft 1a. Have been.

In the chain chamber 84, as shown in FIG.
Crankshaft 1a arranged at the center of cylinder block 2
The crank sprocket 85 is mounted on the shaft ends of the shafts, and the intake cam shaft 86 and the exhaust cam shaft 87 provided in the valve operating chambers 80 and 81 of the cylinder heads 3a and 3b. , An intake cam sprocket 88, an exhaust cam sprocket 89, and the like. The LH timing chain 90 is connected to the crank sprocket 85, the intake cam sprocket 88, and the exhaust cam sprocket 89.
Are wound, and the camshafts 86 and 87 of the LH cylinder head are rotationally driven in synchronization with the crankshaft 1a. Further, the LH timing chain 90 includes a first idler sprocket 91 disposed below the crank sprocket 85, a second idler sprocket 92 disposed between the crank sprocket 85 and the intake cam sprocket 86, And it is wound around a pump sprocket 94 which is disposed below the second idler sprocket 92 and drives a water pump 93.

The first idler sprocket 91
An RH timing chain 95 is wound around an intake cam sprocket 88 and an exhaust cam sprocket 89 provided on the RH cylinder head 3b. Then, the rotation of the first idler sprocket 91 linked to the crankshaft 1 a by the LH timing chain 90 is transmitted by the RH timing chain 95 to each of the cam sprockets 88 and 89 of the RH cylinder head 3 b. This allows
The respective camshafts 86 and 87 of the RH cylinder head 3b are driven to rotate synchronously with the crankshaft 1a. Here, the crankshaft 1a of the engine 1 is set to rotate clockwise as viewed from the chain case 83 side at the front of the engine 1, and accordingly, the timing chains 90, 9
5 rotates in the same direction in synchronization with the crankshaft 1a.

An oil return passage 96 (see FIG. 4) formed in the cylinder block 2 (RH cylinder block 2b) has a lower portion of the chain chamber 84 and an oil reservoir (not shown) formed in a lower portion of the crank chamber 82. (Indicated by broken lines), and the valve chambers 80, 81 of the cylinder heads 3a, 3b are respectively
3b and oil return passages 2c 'and 2d' formed in the cylinder blocks 2a and 2b.

An oil pan 2e stores oil at the same level as the oil reservoir at the bottom of the chain chamber 84. As shown in FIG. 5, when the engine 1 is operating, the oil level is the first idler sprocket 91.
Is set so that the lower part of the
4 stays in each timing chain 90,
95 and is carried upward.

The chain chamber 84 includes a crank chamber 82
Blow-by gas discharge port 9 provided at the upper part at the joint between LH cylinder block 2a and RH cylinder block 2b
7 communicates with the crank chamber 82. Of the valve chambers 80, 81 of each bank, only the valve chamber 80 of the LH cylinder head 3a communicates with the chain chamber 84 via a passage 98 formed in the LH cylinder head 3a. The aforementioned fresh air introduction passage 47 is connected only to the valve operating chamber 80 side of 3a, and the aforementioned PCV valve 45 is connected via a breather device 99, and the blow-by gas passage 46 to the intake system is extended. I have.

Returning to FIG. 1, the engine 1 is provided with sensors for detecting the operating state of the engine. That is, the throttle opening sensor 50 is attached to the throttle valve 14 interposed in the throttle chamber 15.
a and a throttle sensor 50 incorporating an idle switch 50b that is turned on when the throttle valve 14 is fully closed. An intake pipe pressure sensor 51 that detects the intake pipe pressure downstream of the throttle valve 14 is provided downstream of the throttle valve 14. It is arranged. Further, an intake air temperature sensor 52 for detecting the intake air temperature faces the air chamber 16.

Further, a knock sensor 53 is attached to each bank of the cylinder block 2 of the engine 1, and a cooling water temperature sensor 55 faces a cooling water passage 54 formed in the cylinder block 2. A linear air-fuel ratio sensor 56 is disposed upstream of the catalytic converter 39 of the exhaust pipe 38 of each bank.
On the downstream side of the catalytic converter 40 interposed in the collecting portion of
An O2 sensor 57 is provided. A crank angle sensor 59 is provided on the outer periphery of a crank rotor 58 which is mounted on the crankshaft 1a of the engine 1.
A cylinder discriminating sensor 61 is provided opposite to a cam rotor 60 connected to a cam shaft that makes a half turn with respect to a.

The above engine 1 is electronically controlled by an electronic control unit (not shown). That is, the electronic control unit processes a detection signal from each sensor / switch, a battery voltage, and the like, and based on various data stored in a memory, various learning value data, fixed data, and the like, a fuel injection amount,
Calculate the ignition timing, the target idle speed, the target purge rate of the evaporative fuel, the target EGR rate, etc., and perform fuel injection control, ignition timing control, idle speed control, evaporative fuel purge control, EG
Engine control such as R control is performed.

Here, blow-by gas generated in the crank chamber 82 by the operation of the engine 1 is supplied to the air chamber 1.
The PCV valve 45 is scavenged by fresh air introduced through the fresh air introduction passage 47 through the fresh air introduction passage 47, and according to a differential pressure between the intake pipe pressure downstream of the throttle valve 14 and the pressure in the LH valve operating chamber 80 of the cylinder head 3. Then, the flow rate is adjusted and the air is sucked into the intake passage downstream of the throttle valve 14 through the blow-by gas passage 46. That is, the blow-by gas blown into the crank chamber 82 flows into the chain chamber 84 mainly from the blow-by gas discharge port 97 opened in the upper part of the crank chamber 82, and flows from the chain chamber 84 through the passage 98 to move the LH cylinder head 3 a. It flows into the valve chamber 80. Then, when passing through the breather device 99, it is separated into gas and liquid in a predetermined manner, and then sent to an intake system where it is reburned.

In this case, the crankshaft 1a of the engine 1
Is set to rotate clockwise as viewed from the front of the chain case 83 of the engine 1 as described above, and the timing chains 90 and 95 rotate in the same direction in synchronization with the crankshaft 1a. I do. The flow of oil due to the clockwise rotation of the timing chains 90 and 95 generates a pressure difference in the chain chamber 84 where the RH cylinder head 3b side has a lower pressure than the LH cylinder head 3a side. The pressure in the valve operating chamber 81 of the RH cylinder head 3b decreases due to the suction operation, and the pressure in the oil reservoir below the crank chamber 82 becomes R
It has been found through experiments and the like that the pressure in the valve operating chamber 81 of the H cylinder head 3b becomes low.

Therefore, in order to prevent the pressure in the valve operating chamber 81 of the RH cylinder head 3b from becoming lower than the pressure in the oil reservoir below the crank chamber 82 by the suction action caused by this pressure difference, the RH The valve chamber 81 of the cylinder head 3b does not communicate with the chain chamber 84. The oil supplied to the valve operating chamber 81 of the RH cylinder head 3b is supplied to an oil return passage 2d 'formed in the RH cylinder head 3b and the RH cylinder block 2b.
The oil is returned to the oil reservoir below the crank chamber 82 only through the oil reservoir.

On the other hand, the valve operating chamber 8 of the LH cylinder head 3a
No. 0 communicates with the chain chamber 84 via the passage 98 to make the pressure in the valve operating chamber 80 of the LH cylinder head 3a higher than the pressure in the oil storage chamber and use the chain chamber 84 as an oil return passage. . Part of the oil supplied to the valve operating chamber 80 of the LH cylinder head 3a is
The oil is returned to the oil reservoir via the oil return passage 2c 'formed in the cylinder head 3a and the LH cylinder block 2a, and the remaining oil is passed through the chain chamber 84 from the passage 98 in the valve operating chamber 80 of the LH cylinder head 3a. The oil is returned to the oil reservoir through an oil return passage 96 formed in the RH cylinder block 2b at a lower portion of the chain chamber 84.

In response to the pressure difference due to the oil flow in the chain chamber 84 due to the clockwise rotation of the timing chains 90 and 95, the valve chamber 81 of the RH cylinder head 3b is not communicated with the chain chamber 8, Since only the valve chamber 80 of the LH cylinder head 3a communicates with the chain chamber 84, the valve chamber 80 of the LH cylinder head 3a is
A pressure difference is generated between the valve chamber 81 of the H cylinder head 3b. That is, the pressure amplitude in the valve operating chamber 81 of the RH cylinder head 3b that is not connected to the chain chamber 84 is smaller than the pressure amplitude in the valve operating chamber 80 of the LH cylinder head 3a that is connected to the chain chamber 84. Looking at the average value of the pressure pulsation at the center, the pressure in the valve operating chamber 81 of the RH cylinder head 3b is lower than that in the valve operating chamber 80 of the LH cylinder head 3a, and the valve operating chamber of the RH cylinder head 3b. 81, the internal pressure may be lower than the atmospheric pressure.

Further, in addition to the above, since the exhaust camshaft 87 is disposed below the intake camshaft 86 in each of the valve operating chambers 80 and 81, and the respective camshafts 86 and 87 rotate clockwise,
A difference occurs in the amount of oil mist in each of the valve operating chambers 80 and 81. That is, within the valve operating chamber 80 of the LH cylinder head 3a, the exhaust camshaft 87 rotating clockwise acts in a direction to suck oil between the side wall of the valve operating chamber 80 and promote discharge from the passage 98. RH cylinder head 3b
In the valve operating chamber 81, the exhaust camshaft 87 rotating in the clockwise direction acts in a direction in which oil jumps up between the side wall of the valve operating chamber 81 and the exhaust cam shaft 87. The amount of oil mist is LH cylinder head 3a
Is larger than the amount of oil mist in the valve operating chamber 80.

For this reason, when the blow-by gas is recirculated from the valve operating chamber 81 of the RH cylinder head 3b having a relatively low pressure to the intake system, the throttle valve in a high-load high-rotation region where the amount of blow-by gas is increased is increased. 14 in the region where the intake pipe pressure is close to the atmospheric pressure, the RH cylinder head 3b
A large amount of fresh air is sucked into the valve operating chamber 81 of the crank chamber 8.
2 is scavenged, and the large amount of fresh air cannot sufficiently separate the oil mist from the valve operating chamber 81 of the RH cylinder head 3b with a large amount of oil mist. There is a possibility that problems such as pollution of the oil, deterioration of exhaust gas emission, and increase in oil consumption may occur. In this case, since the pressure in the valve operating chamber 81 on the inflow side of the blow-by gas is low, the PCV valve 45 restricts the throttle portion 74 against the urging force of the internal spring 72.
Does not act in the direction of reducing the opening area of the blower, and effective flow controllability in the direction of reducing the blow-by gas cannot be obtained.

Therefore, in the engine 1 of the present embodiment, the blow-by gas passage 46 for recirculating blow-by gas to the intake system is connected to the LH cylinder head 3a having a relatively high internal pressure and a relatively small amount of oil mist. Valve train 80
Connected to the PC to maintain the appropriate amount of fresh air
The controllability of the blow-by gas amount by the V valve 45 can be ensured, and the oil mist in the blow-by gas can be sufficiently separated by the breather device 99 and returned to the intake system. As a result, it is possible to prevent the intake system from being contaminated by the oil component in the blow-by gas and to reduce oil consumption.

The fresh air introduction passage 47 and the blow-by gas passage 4 are located on the valve operating chamber 80 side of the same LH cylinder head 3a.
With the provision of 6, it is possible to improve the degree of freedom of outfitting in the engine room by combining the two pipes, and to make the configuration of the piping system compact.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention. For example, in the present embodiment, an example in which the timing chain is wound between the crankshaft and the camshaft has been described, but an engine using a timing gear as a transmission mechanism between the crankshaft and the camshaft is described. Is also good. Further, the engine is not limited to the horizontally opposed engine, but may be any engine having a plurality of banks, and may be applied to a V-type engine or the like.

[0048]

As described above, according to the present invention, blow-by gas is appropriately recirculated in consideration of the pressure difference between the valve chambers of each bank generated in an engine having a plurality of banks,
It is possible to prevent the intake system from being polluted by oil mist in the blow-by gas and increase in oil consumption.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an engine system.

FIG. 2 is a sectional view of a PCV valve.

FIG. 3 is a front view of the valve element as viewed from a tip end side of the shaft portion.

FIG. 4 is an explanatory view schematically showing a blow-by gas passage system inside the engine.

FIG. 5 is an explanatory diagram of a rotation transmission drive system between a crankshaft and a camshaft.

[Description of Signs] 1 ... Engine 1a ... Crankshaft 46 ... Blow-by gas passage 47 ... Fresh air introduction passage 84 ... Chain chamber (accommodation chamber) 80, 81 ... Valve train chamber 82 ... Crank chamber 86, 87 ... Camshaft 90, 95 ... Timing chain (transmission mechanism)

Claims (2)

[Claims] 1. A storage chamber having a plurality of banks and a transmission mechanism for rotatably driving a camshaft disposed in a valve operating chamber of each bank in synchronization with a crankshaft to rotate the camshaft in synchronization with a crankshaft. A blow-by gas processing device for an engine that recirculates the blow-by gas of the engine, which uses the storage chamber as an oil return passage from the valve train, to an intake system by introducing fresh air, and recombustes the blow-by gas. And the upper part of the valve chamber is communicated with the crank chamber. Of the valve chambers of each bank, only the valve operating chamber whose internal pressure is relatively high depending on the rotation direction of the transmission mechanism during engine operation is communicated with the housing chamber, A blow-by gas processing device for an engine, wherein a blow-by gas passage for recirculating blow-by gas to an intake system is connected to the valve operating chamber having a relatively high internal pressure. 2. The blow-by gas processing device for an engine according to claim 1, wherein a fresh air introduction passage for introducing fresh air is connected to the valve operating chamber connecting the blow-by passage.