JPH0586832A - Engine cylinder head structure - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a cylinder head structure of an engine that is compact and contributes to improving the rigidity of a camshaft support mechanism. [Structure] The cam shafts 19 and 20 are mounted on the cam carrier 2 from below.
9. A cam cap 30 is rotatably supported from above. The cam carrier is provided with a partition wall 33 that partitions this space into upper and lower parts and that constitutes a cam carrier connecting part that connects the journal parts 29a and 29b for both cam shafts. Similar to the cam carrier, the cam cap also constitutes a cam cap connecting portion that connects the journal portions 30a and 30b that support the intake and exhaust cam shafts, and includes a partition wall 36 that vertically divides a space therebetween. The space between the partition wall of the cam carrier and the partition wall of the cam cap constitutes the second oil separator chamber 37. A space between the partition wall of the cam cap and the cylinder head cover 42 constitutes a third oil separator chamber 43. The cam carrier and the cam cap have two partition walls integrally, and thus have high rigidity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine cylinder head structure, and more particularly to a cylinder head incorporating an oil separator chamber for blow-by gas.

[0002]

2. Description of the Related Art A blow-by gas processing apparatus for collecting unburned gas leaking from a combustion chamber, that is, blow-by gas, and re-introducing it into an engine is known. In this case, since the blow-by gas contains oil mist, it is usual to separate the oil by the oil separator before introducing it into the engine. The oil separator chamber is conventionally provided in the space above the cylinder head. However, it may be difficult to provide an oil separator chamber at this portion due to the layout of a DOHC engine or the like. In view of such circumstances, Japanese Utility Model Laid-Open No. 59-157516 discloses that a space between two cam shafts of a DOHC engine is used.
It is disclosed that an oil separator chamber is provided. In the disclosed structure, the oil separator chamber is defined by the cylinder head cover so as to project into the space. This provides a compact blow-by gas treatment device.

[0003]

The structure disclosed in this publication can provide a compact device and improve the rigidity of the cylinder head cover, but the effect of improving the support rigidity of the camshaft cannot be expected so much. In view of such circumstances, it is an object of the present invention to provide a cylinder head structure for an engine that is compact and can contribute to improving the rigidity of a camshaft supporting mechanism.

Another object of the present invention is to provide a structure of a cylinder head incorporating an oil separator which can provide a good oil separating function.

[0005]

In order to solve the above problems, the present invention is configured as follows. A cylinder head structure of an engine according to the present invention includes a pair of cam shafts arranged in the cylinder head and a connecting member for connecting between bearing portions of the cam shaft, and the connecting member defines an oil separator chamber. It is characterized by being made.

Further, in a preferred mode, a cam cap forming an upper portion of the bearing portion, a cam carrier forming a lower portion, a cam cap connecting portion forming the connecting member and connecting between the cam caps, and the connecting member. And a cover member that defines a space above the cam cap, and a first oil separator chamber is formed below the cam carrier and the cam carrier connecting portion. A second oil separator chamber is formed above the cam carrier and the cam carrier connecting part and below the cam cap and the cam cap connecting part, and a third oil separator chamber is formed above the cam cap and the cam cap connecting part and below the cover member. It is characterized by In this case, preferably, the cam carrier connecting portion,
Gas passages communicating with the adjacent oil separator chambers are formed in the cam cap connecting portion at positions not overlapping with each other.

[0007]

According to the above construction of the present invention, the bearing portions of the camshaft are connected to each other by the connecting member, and
The connecting member constitutes a partition wall of an oil separator for blow-by gas to define an oil separator chamber.
This connecting member is originally provided to secure the rigidity of the bearing portion. In the present invention, the connecting member is extended in the direction of each cylinder in a panel shape to form the partition wall. The blow-by gas is introduced into the bottom of the oil separator chamber, diffuses or meanders in the cylinder row direction or the lateral direction while separating the oil, and is gradually guided to above the oil separator chamber and discharged from there.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. The engine according to one embodiment of the present invention is a V-type 6 cylinder engine. In this structure, the cylinder head is attached to each bank. Referring to FIG. 1, a cross section of the engine 1 for one bank is shown. The engine 1 includes a cylinder block 3 having a cylinder bore 2 extending in an oblique direction, and a piston 4 slides in the cylinder bore 2. The piston 4 is connected via a connecting rod 5 to a crankshaft (not shown) housed in a lower portion of the cylinder block 3 and a crankcase 6 attached to the lower portion. A blow-by gas passage 8 communicating with an inner space of the crankcase, that is, the crank chamber 7 is provided around the cylinder block 3.

An oil pan 9 is provided below the crankcase 6.
Is installed. The cylinder block 3, the crankcase 6 and the oil pan 9 are connected to each other by through bolts 10. A cylinder head 11 is attached to the upper part of the cylinder block 3 for each bank. In the lower part of the cylinder head 11, a recess is formed in the cylinder bore 2 which cooperates with the upper part to form the combustion chamber space 12. Further, the cylinder head 11 is provided with an intake port 13 and an exhaust port 14 (each one is connected to the combustion chamber 12).
Are shown one by one). An intake valve 15 and an exhaust valve 16 for opening and closing the intake port 13 and the exhaust port 14 are provided, respectively. Further, the cylinder head 11 is provided with a blow-by gas passage 18 which communicates with the blow-by gas passage 8 of the cylinder block 3 via a communication passage 17.

Above the intake and exhaust valves 15 and 16, there are provided an intake camshaft 19 and an exhaust camshaft 20 for driving these valves 15 and 16, respectively. Cams 21 and 22 are formed on the camshafts 19 and 20 corresponding to the valves 15 and 16, respectively. The tips of the valves 15 and 16 are rocker arms 23 and 2.
No. 4 of the rocker arms 23 and 24 driven by the cams 21 and 22 through the rocker arms 23 and 24, and the other of the rocker arms 23 and 24 are engaged with lash adjusters 25 and 26. The contact pressure of the cam is adjusted. The valves 15 and 16 are pressed against the cams 21 and 22 by springs 27 and 28.

The cam shafts 19 and 20 are rotatably supported by a cam carrier 29 from below and a cam cap 30 from above. The cam carrier 29 and the cam cap 30 of this example are commonly provided for the intake and exhaust cam shafts 19 and 20. That is, the intake camshaft 19 and the exhaust camshaft 20 are formed as an integral part.
The cam carrier 29 and the cam cap 30 are connected to each other. FIG. 2 shows a plan view of the cam carrier 29 of one bank. The intake camshaft 19 is provided with journal portions 29a on both sides of the pair of cams 21 and 22 for the cylinders a, b and c, and the exhaust camshaft 20 is provided with a journal portion 29b between the pair of cams. It is provided.

A plug hole 31 for inserting an ignition plug (not shown) is formed at the center of each cylinder a, b, c. The cam carrier 29 of this example is the cam shaft 1
The lower parts of the journal portions 9 and 20 are formed integrally with the lower part of the plug hole wall 32 forming the plug hole 31. Journal parts 29a, 29 for supporting the intake and exhaust camshafts 19, 20 of the cam carrier 29
The space surrounded by b and the plug hole wall 32 constitutes a blow-by gas passage. And the cam carrier 2 of this example
9 is provided with a partition wall 33 that divides this space into upper and lower parts and constitutes a cam carrier connecting part that connects the journal parts 29a and 29b for both cam shafts 19 and 20.

The space below the partition wall 33 and the upper surface of the cylinder head communicates with the crank chamber 7 through the blow-by gas passage 8 of the cylinder block, and separates the oil mist accompanying the blow-by gas. The first oil separator chamber 34 is configured. The cam carrier 29 is fixed to the cylinder block 3 by the bolts 35 inserted into the bolt holes 35a.

Similarly to the cam carrier 29, the cam cap 30 constituting the upper part of the journal portion of the cam shafts 19 and 20 also supports the journal portion 30 for supporting the intake and exhaust cam shafts.
A partition wall 36 that constitutes a cam cap connecting portion that connects a and 30b and that vertically partitions a space therebetween is provided. The space between the partition wall 33 of the cam carrier 29 and the partition wall 36 of the cam cap 30 constitutes a second oil separator chamber 37. The first oil separator chamber 34 and the second oil separator chamber 37 communicate with each other through a communication hole 38 formed in the partition wall 33.

The cam carrier 29 and the cam cap 30 have bolt holes 39 at positions sandwiching the journal portions 29a, 29b, 30a, 30b and are fixed via bolts 40. Referring to FIG. 3, a top view of cam cap 30 is shown. A communication hole 41 that communicates with the second oil separator chamber 37 is provided in the partition wall 36. As shown in FIG. 3, the third oil separator chamber 43 is provided on the intake side. The partition wall is formed by a wall portion connecting the plug hole walls in the cam cap 30. A cylinder head cover 42 is attached above the cam cap 30.

The space between the partition wall 36 of the cam cap 30 and the cylinder head cover 42 constitutes a third oil separator chamber 43. The third oil separator chamber 43 communicates with a blow-by gas chamber (not shown) via a return pipe 47, and further communicates with an intake passage via a valve (not shown). Partition wall 3 of this cam carrier 29
The communication hole 38 provided in No. 3 and the communication hole 41 provided in the partition wall 36 of the cam cap 29 are provided at positions where they do not overlap with each other in plan view. That is, they are provided at positions offset from each other.

A downstream end of an intake manifold 44 is attached upstream of the intake port 13, and the intake manifold 4 is attached.
An injector 45 for injecting fuel toward the intake port 13 is attached to the valve 4. The intake passage 44a of the intake manifold 44 curves upward from the inside of the bank and extends upward. The common intake passage 44b extends above the cylinder head cover 42 in the cylinder arrangement direction of the bank.

The intake manifold 44 is supported by a bracket 46 connecting the common passage 44b and the cylinder head 3. In the above structure, when the engine 1 operates, the unburned gas in the combustion chamber, that is, the blow-by gas, leaks between the piston 4 and the cylinder bore 2 and collects in the crank chamber 7. This blow-by gas passes through a blow-by gas passage 8 provided around the cylinder block 3 and a blow-by gas passage 18 of the cylinder head 11, and the partition wall 33 of the cylinder carrier 11 and the cam carrier 29.
It is introduced into the first oil separator chamber 34 formed between and.

The blow-by gas entrained with the oil mist introduced into the first oil separator chamber 34 enters the oil separator chamber 34 and has a large flow passage cross section, so that the flow velocity decreases and the oil mist becomes a gas component. Separate from the difference in inertial force of. Also, due to the change of the flow direction, they also separate due to the difference in inertial force. Further, the blow-by gas passes from the first oil separator chamber 34 through the communication hole 38 of the partition wall 33 to the second oil above the second oil separator chamber 34.
It is introduced into the oil separator chamber 37. In this case, the flow rate of blow-by gas increases when passing through the communication hole 38,
When it is introduced into the second oil separator chamber 37, the flow velocity decreases again. The oil mist is also separated in the second oil separator chamber 37 due to the change in the flow velocity and the change in the flow direction. Further, the blow-by gas is introduced into the third oil separator chamber 43 via the communication hole 41 provided in the partition wall 36 of the cam cap 30. In this case, the communication hole 38 of the partition wall 33 of the cam carrier 29 and the cam cap 30
Since the partition wall 36 and the communication hole 41 of the partition wall 36 are provided at positions that do not overlap with each other in plan view, the blow-by gas flows through the first and second oil separator chambers 34 and 37 without bypassing. It is introduced into the third oil separator chamber 43. Also in this third oil separator chamber 43, the oil mist entrained in the blow-by gas is separated by the same procedure as above. Then, the blow-by gas from which the oil mist is separated is introduced into the intake system from above the third oil separator chamber 43.

On the other hand, each oil separator chamber 34, 37,
The oil mist separated in 43 is the oil separator chamber 3
4, 37, 43 are adhered to and grow on the wall surfaces of the oil separator chambers 34, 37, 43 to form oil droplets, and communicate with the lower communication holes of the plurality of communication holes 38, 41. Flows downward through holes 38, 41. And the first
The oil from the oil separator chamber 34 flows downward in the blow-by gas passage 8 and is returned to the crank chamber 7.

[0021]

According to the above configuration of the present invention, the bearing portions of the cam carrier and the cam cap are coupled to each other by the partition wall which constitutes the connecting member, and the partition wall constitutes the partition wall of the oil separator for blow-by gas. Thus, the oil separator chamber is formed, so that the space between the cam shafts can be effectively used. With this configuration, it is not necessary to provide a member for forming the oil separator chamber, and the number of parts can be reduced. Since this partition wall is formed integrally with the bearing portions of both cam shafts, it has the effect of improving the rigidity of the cam carrier and the cam cap.

According to another feature of the present invention, as described above, according to the present invention, the engine cylinder head structure according to the present invention includes a pair of cam shafts arranged in the cylinder head, and the cams. A connecting member for connecting between the bearing portions of the shaft is provided, and the connecting member defines an oil separator chamber. Further, in the preferred embodiment, the oil separator chamber is divided into three states by the cam carrier, the cam cap, and the cover member, so that a complicated flow path of blow-by gas can be configured, and therefore the oil mist separation efficiency can be increased. Can be improved.

According to another feature, since the communication passages connecting the oil separator chambers are provided so as not to overlap with each other, the oil separator chambers can be circulated without bypassing the oil separator chambers. Separation efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a partial sectional view of an engine according to an embodiment of the present invention,

2 is a cross-sectional view taken along the line AA of the cylinder head of FIG.

3 is a cross-sectional view taken along the line BB of the cylinder head of FIG.

[Explanation of symbols]

 1 Engine 2 Cylinder Bore 3 Cylinder Block 4 Piston 5 Connecting Rod 6 Crankcase 7 Crank Chamber 8 Blowby Gas Passage 9 Oil Pan 10 Through Bolt 11 Cylinder Head 12 Combustion Chamber 13 Intake Port 14 Exhaust Port 15 Intake Valve 16 Exhaust Valve 17 Communication Passage 18 Blowby Gas passage 19 Intake camshaft 20 Exhaust camshaft 21 Intake cam 22 Exhaust cam 23 Rocker arm 24 Rocker arm 25 Rush adjuster 26 Rush adjuster 29 Cam carrier 30 Cam cap 33 Partition wall 34 First oil separator chamber 36 Partition wall 37 Second oil Separator chamber 38 Communication hole 41 Communication hole 43 Third oil separator chamber 44 Intake manifold.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumasa Nomura 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (3)

[Claims] 1. A cylinder head, a pair of cam shafts disposed in the cylinder head, and a connecting member for connecting between bearing portions of the cam shaft, the connecting member defining an oil separator chamber. The cylinder head structure of the engine, which is characterized by 2. A cam cap forming an upper portion of the bearing portion, a cam carrier forming a lower portion, and a cam cap connecting portion forming the connecting member and connecting between the cam caps.
A cam carrier connecting portion that forms the connecting member and connects the cam carriers, and a cover member that defines an upper space of the cam cap, and a first oil separator chamber is formed below the cam carrier and the cam carrier connecting portion. A second oil separator chamber is formed above the cam carrier and the cam carrier connecting portion and below the cam cap and the cam cap connecting portion, and a third oil separator chamber is formed above the cam cap and the cam cap connecting portion and below the cover member. The cylinder head structure for an engine according to claim 1, wherein: 3. The engine cylinder according to claim 2, wherein gas passages communicating with the adjacent oil separator chambers are formed in the cam carrier connecting portion and the cam cap connecting portion so as not to overlap each other. Head structure.