JPH03160107A - Breather device in overhead valve engine - Google Patents

Abstract

PURPOSE:To reduce the total height of an engine by forming a breather chamber at one end of a valve system cam shaft, and opening breather ports on a peripheral wall of this breather chamber in the radial direction thereof together with opening of a discharge port which is communicated with a blow-by gas processing means, on the wall. CONSTITUTION:In an engine main body E of a DOHC-type multicylinder engine, a cylinder head 2 is covered with a cylinder head cover 4 via a packing. In a valve system chamber 5, which is formed by both the cylinder head 2 and the cover 4, an intake (discharge) side valve system cam shaft 6 is supported freely rotatably via a plurality of bearings 10. In this case, an extension part 61 is formed at one end of the valve system cam shaft 6, which is formed into a hollow shape, while a plug body 14 is tightly fitted to a base part of this extension part 61, thereby forming a hollow cylindrical breather chamber 15. In addition, a plurality of breather ports 16 are made in a peripheral wall of this breather room 15 in the radial direction, and moreover a discharge port 21, which is communicated with a blow-by gas processing means (intake system In), is formed in this wall.

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Field of Application The present invention provides a method for efficiently separating lubricating oil droplets from blow-by gas generated within the engine body in an overhead valve type engine and guiding the blow-by gas to a blow-by gas processing means. This invention relates to a breather device for an overhead valve type engine.

(2) Prior art A conventional overhead valve type engine in which a breather device is provided on the upper part of the engine body for discharging blow-by gas generated inside the engine body into an exhaust pipe is disclosed in Japanese Utility Model Publication No. 62-44085, for example. will be disclosed. (3) Problems to be Solved by the Invention In the above-mentioned conventional engine, a breather chamber is provided in the cylinder head cover of the engine body, and the blow-by gas in the valve operating chamber is guided into this breather chamber, and the lubricating oil contained therein is After separating the droplets, they are directed to the exhaust pipe. However, if a breather chamber is provided in the cylinder head force bar and the breather volume is secured so that the breather chamber can perform its intended function, the overall height of the engine body will be increased. If an attempt is made to provide a breather chamber in the cylinder head force bar while avoiding such inconveniences, it will not only be difficult to secure the required volume of the breather chamber, but also the breather chamber will be located close to the valve drive camshaft. There is a problem in that the intended breather function cannot be achieved. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a breather device with excellent breather function without increasing the overall height of the engine.

B. Structure of the Invention (1) Means for Solving the Problems To achieve the above object, the present invention provides an overhead valve type engine equipped with a valve camshaft for operating a valve mechanism in the head of the engine. A breather chamber is formed at one end of the valve camshaft, a breather is opened in the radial direction of the peripheral wall of the breather chamber to communicate the chamber with the valve chamber of the engine head, and an end wall of the breather chamber is formed. Then, open the exhaust port connected to the blow-by gas treatment means. (2) Effect According to the above structure, the breather chamber is formed at one end of the rotating valve drive camshaft, and a breather is opened in the radial direction on the circumference of the chamber, so that the breather is passed through the breather. Lubricating oil droplets that attempt to enter the chamber are separated from the outer circumferential surface of the breather chamber by centrifugal force caused by the rotation of the breather chamber, which is integrated with the valve drive camshaft. Therefore, blow-by gas that does not contain lubricating oil droplets flows into the breather chamber, and is returned to the blow-by gas treatment device through the breather passage. (3) Example A first example of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is an exploded perspective view of the head of a DOHC multi-cylinder engine equipped with the breather device of the present invention, and FIG. 2 is a longitudinal sectional side view of the breather device of the present invention. The engine body E of the DOHC type engine includes a cylinder block 1 and a cylinder block 2 which is superimposed and bonded on the deck surface of the cylinder block 1. A cylinder head force bar 4 is mounted on the cylinder head 2 via a packing 3. The valve operating chamber 5 is defined by the cylinder head 2 and the cylinder head force bar 4. On the cylinder head 2, there is an intake side valve camshaft 6 having a plurality of intake cams 7 and an exhaust side valve camshaft 8 having a plurality of exhaust cams 9.
are rotatably supported via a plurality of bearings 10 in parallel with each other. Each bearing 10 consists of a bearing half 11 integrally formed on the cylinder head 2, and a bearing holder I2 fixed onto the bearing half 1l with a connecting bolt 13. A breather device B of the present invention is provided at one end of each of the two valve drive camshafts 6.8. Since these breather devices B have the same structure, the structure of the breather device B provided at one end of the intake side valve operating camshaft 6 will be mainly explained below.
This will be explained with reference to the figure. An extension portion 6 is provided at one end of the intake side valve drive camshaft 6 formed hollow.
A hollow cylindrical breather chamber 15 is formed by tightly fitting a stopper 14 into the base of the extended portion 6. A plurality of breather holes 16 are bored in the peripheral wall of this breather chamber 15 in the radial direction, and these breather holes l6
The interior of the breather chamber 15 is communicated with the valve operating chamber 5 through the valve.
End walls 2, 4 of the cylinder head 2 and cylinder cover 4 on the breather chamber 15 side. A breather holder 17 is fixed to the outer surface by connecting bolts 18 across the two. A breather passage 19 is provided in the center of this breather holder 17. The inner end of this breather passage 19 is connected to the end wall 2. ,4. It protrudes into the valve train chamber 5 through a seal member 20 provided therebetween, and its inner end is airtightly connected to a discharge port 21 opened in the outer end wall of the breather chamber 15 so as to be relatively rotatable. Ru. A take-out pipe 22 communicating with the breather passage 19 is connected in the radial direction to the outer end of the breather holder 17, and the outer end of the take-out pipe 22 is connected to a blow-by gas processing means, for example, the intake air of an engine, through a rubber tube 23. System 1 Connected to n.

Next, the operation of this first embodiment will be explained.

When the engine is operated now, unburned gas in the combustion chamber of the engine flows into the valve operating chamber 5 between the cylinder head 2 and the cylinder head cover 4 through the valve port opened to the cough chamber.
The gas becomes blow-by gas and is stored in the valve operating chamber 5. This blow-by gas then flows into the breather chamber 15 formed at one end of the valve camshaft 6 through the breather I6, flows from there to the breather passage l9 of the breather holder l7, and passes through the take-out pipe 22 and the rubber tube 23. and is returned to the engine's intake system In. By the way, in the sealed valve train chamber 5, due to the rotation of the valve train camshaft 6.8 and the operation of the valve train mechanism (not shown), the lubricating oil that lubricates them is scattered in the form of droplets. Valve chamber 5
However, the breather chamber 15 is formed at one end of the rotating valve camshaft 6, and a breather hole l6 is opened in the radial direction on the peripheral wall of the chamber 15, so that the The lubricating oil droplets that try to enter the breather chamber 15 are separated from the outer peripheral surface of the breather chamber 15 by the centrifugal force caused by the rotation of the breather chamber 15, which is integrated with the valve drive camshaft 6. Therefore, in the breather chamber 15,
Blowby gas that does not contain lubricating oil droplets flows in, and is returned to the engine intake system In through the breather passage 19, the outlet pipe 22, and the rubber tube 23. FIG. 3 shows a second embodiment of the invention. This second
In the embodiment, the same members as in the first embodiment are given the same reference numerals. End wall 2 of cylinder head 2 and cylinder head cover 4,
,4. A joint pipe 24 is supported slidably in the axial direction between the joint surfaces thereof, and a coil spring 25 is interposed between the joint pipe 24 and the @ walls 2+, 4I, and the elasticity of the spring 25 is The power is generated by pressing the inner end of the joint pipe 24 against the end surface of the discharge port 21 of the breather chamber 15 to maintain airtightness between them.

Further, the joint pipe 24 is coaxial with the breather chamber 15 and the breather passage 19 of the breather holder 17, and the communication hole 26 formed therein communicates the breather chamber work 5 with the breather passage 19.

Note that 27 indicates the breather holder 17 and the end wall 24. This is an O-ring inserted between the two. In this second embodiment, as in the first embodiment, the blow-by gas from which lubricant oil droplets have been separated flows through the breather chamber 15 through the breather chamber 15, and from there flows into the communication hole 26 of the joint pipe 24, the breather passage 19, It passes through the take-out pipe 22 and the rubber tube 23 and is returned to the intake system In.

In the first and second embodiments, the case where the breather device B is provided on either of the intake and exhaust side valve drive camshafts 6, 8 has been described, but the device B can be installed on either of the shafts 6, 8. You may also set it in Further, in the first and second embodiments, the case where the device of the present invention is applied to a DOHC type engine has been described, but it goes without saying that it can also be applied to a SOHC type engine. C. Effects of the Invention As described above, according to the present invention, in an overhead valve type engine, a breather chamber is formed at one end of the valve camshaft, and the peripheral wall of the breather chamber is formed so that the chamber is connected to the valve operating chamber at the head of the engine. The breather that communicates with the engine is opened in the radial direction, and the exhaust port that connects to the blow-by gas treatment means is opened in the end wall of the breather chamber, so the overall height of the engine can be kept lower than that of conventional overhead valve type engines of this type. This can contribute to the miniaturization of the entire engine, and the number of parts of the breather device can be reduced, resulting in simplification of structure and cost reduction.

Furthermore, the centrifugal force generated by the rotation of the valve camshaft can be used to efficiently separate lubricating oil droplets mixed into the blow-by gas.

[Brief explanation of the drawing]

1.2 shows the first embodiment of the device of the present invention, FIG. 1 is a perspective view of a DOHC type engine equipped with the device of the present invention, FIG. 2 is a longitudinal sectional side view of the device of the present invention, and FIG. The figure shows a second embodiment of the device of the present invention, and is a longitudinal sectional side view thereof. 6... Intake side valve drive camshaft, 8... Exhaust side valve drive camshaft, 15... Breather chamber, 16... Breather, 21
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Claims (1)

[Claims] In an overhead valve type engine equipped with a valve camshaft (6, 8) for operating a valve mechanism in the engine head, a breather chamber (15) is formed at one end of the valve camshaft (6, 8). A breather port (1) is provided on the peripheral wall of the breather chamber (15) to communicate the inside of the chamber (15) with the valve operating chamber (5) in the engine head.
6) is opened in its radial direction, and further the breather chamber (1
5) A breather device for an overhead valve type engine, characterized in that an exhaust port (21) connected to the blow-by gas treatment means (In) is opened in the end wall of the engine.