JPH0196410A - Cam shaft provided with oil separator mechanism - Google Patents

Abstract

PURPOSE:To eliminate a buffer chamber from a rocker cover by separating oil component in blow-by gas fed into a dynamic valve chamber through utilization of a cam shaft. CONSTITUTION:A path 1c having opposite ends opening respectively to the circumferential face near the front end and to the rear end face is made in the core of a cam shaft 1, and an oil slinger 13 is formed at the rear end. Oil escape paths 3a, 3c for discharging oil which is dispersed from the oil slinger 1e and collected into a dynamic valve chamber 4 are formed in a bearing 3 for bearing the rear end of the cam shaft 1, and a fitting 8 surrounding the rear end of the cam shaft 1 and communicating the path 1c with a suction system is mounted at the rear end of the bearing 3. Blow-by gas led from a crank case into the dynamic valve chamber 4 is sucked into the path 1c of the cam shaft 1 where oil component is separated centrifugally, then the gas is discharged through escape paths 3a, 3c into the dynamic valve chamber 4 so as to recirculate only the blow-by gas to the suction system.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a camshaft with an oil separator mechanism that separates oil contained in blow-by gas of an engine.

(Prior art) Blow-by gas that leaks from the combustion chamber of an engine into the crankcase through the gap between the piston ring and the cylinder wall is composed of approximately 80% unburned gas and approximately 20% exhaust gas. In addition, engine oil is mixed in the crankcase. Nowadays, with exhaust gas regulations in place, this blow-by gas is returned to the intake system and combusted again.

The blow-by gas recirculation system normally uses a closed system to completely prevent blow-by gas from leaking.
Blow-by gas is guided from the crank chamber to the valve train chamber in the upper part of the ring head through the ventilation hole (passage) in the clinder block, and the inertia difference between the gas and oil particles is absorbed in the baffle chamber provided in the rocker cover (cylinder cover). The blow-by gas is separated from the oil, leaving as much of the oil inside the rocker cover as possible, and only the blow-by gas is returned to the intake system.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional blow-by gas recirculation system, the provision of the baffle chamber in the rocker cover increases the overall height of the engine, which is a factor that hinders miniaturization of the engine. However, if the rocker cover is provided with a baffle chamber, the structure of the rocker cover becomes complicated and the cost increases.

The present invention was made to solve the above-mentioned problems, and uses a camshaft to separate the oil component of the blow-by gas introduced into the valve chamber at the top of the cylinder head, and only the blow-by gas is sent to the intake system. An object of the present invention is to provide a camshaft with an oil separator mechanism that allows reflux.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, one end of the camshaft is opened on the peripheral surface near the front end of the camshaft, and the other end is opened on the rear end surface of the camshaft. A passage is bored and an oil slinger is formed at the rear end, while an oil relief passage is formed in a bearing that pivotally supports the rear end of the camshaft to collect the oil that can fly from the oil slinger and discharge it to the valve train chamber. Further, a fitting is attached to the rear end of the bearing to surround the rear end of the camshaft and connect the passage to the intake system.

(Operation) As the engine rotates, blow-by gas in the crankcase is introduced into the valve train chamber at the top of the cylinder head. Further, the passage of the camshaft that communicates with the intake system has a negative pressure with respect to the valve chamber, and the blow-by gas introduced into the valve chamber is sucked into the passage of the shaft center from the opening near the front end of the camshaft. It flows through the passage toward the rear end. The blow-by gas in this passage rotates together with the camshaft, and the oil it contains is centrifugally separated until it reaches the rear end.The separated oil is transmitted along the inner wall of the passage due to the negative pressure of the intake system The oil reaches the rear end, is scattered outward of the camshaft by the oil slinger, and is discharged into the valve train chamber through an oil relief passage formed in the bearing. On the other hand, the blow-by gas from which the oil has been separated is discharged from the rear end of the passage, reaches the fitting, and is returned to the intake system.

(Example) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a cross section of a camshaft to which the present invention is applied,
The camshaft 1 has a hole 1c bored in its axis from the rear end surface 1a to the vicinity of the front end, and furthermore, in the vicinity of the front end, holes 1c are formed at predetermined intervals in the circumferential direction and have a diameter smaller than the hole 1c in the radial direction. A plurality of communication holes 1d are bored. Each of these communication holes 1d has one end opened in the circumferential surface of the camshaft 1, and each other end opened in the inner wall of the front end of the hole 1c to communicate with each other. Each of these communication holes 1d is bored at a position as far away as possible from the rear end surface 1a of the camshaft 1, that is, from the rear opening end of the hole IC, so that the effective length of the hole 1c is set to be long. There is.

The communication hole 1d serves as an inlet for blow-by gas, the hole 1c in the shaft center serves as a passage for the blow-by gas, and the rear open end of the hole 1c serves as an outlet for blow-by gas and oil. Hereinafter, the hole 1c will be referred to as a passage, and the communication hole 1d will be referred to as an inlet.

Furthermore, a substantially umbrella-shaped oil slinger 1e is integrally formed at the rear end of the camshaft 1 to shake off oil transmitted through the camshaft 1 by centrifugal force.

The camshaft 1 has its rear end rotatably supported by a bearing 3 integrally formed with a cylinder head 2, and has an oil seal 5 attached to its front end. Of course, it goes without saying that the camshaft 1 is rotatably supported by a plurality of bearings (not shown) integrally formed at predetermined locations on the cylinder head 2. A sprocket 6 is firmly screwed and fixed by a bolt 7, and is rotationally driven in the direction of the arrow by a timing chain (none of which is shown) that is wound between the sprocket and the sprocket fixed to the crankshaft.

The bearing 3 that pivotally supports the rear end of the camshaft 1 is formed with a gap 3a in which the oil slinger 1e of the camshaft 1 is rotatably accommodated with a small gap. Further, on the upper surface 3b of the bearing 3, there are a plurality of, for example, two ? Th13c and 3c are formed. The oil sling 1e housed in the cavity 3a
The inner and outer end faces 1f and 1g respectively face each end face of the bearing 3 with a slight gap, and these gaps 3a and each groove 3c
, 3c are oil relief passages.

Rear end surface 3 of the bearing 3 that pivotally supports the rear end of the camshaft 1
A fitting 8 that surrounds the end surface 3d and the rear end surface 1a of the camshaft 1 and defines a space 10 therein is fluid-tightly attached to the fitting 8, and a nipple 8a integrally formed with the fitting 8 is connected to the tube 9. It is connected to the engine's intake system (not shown) via.

The action will be explained below.

The internal pressure of the passage 1c of the camshaft l becomes negative pressure with respect to the valve operating chamber 4 due to the intake pressure (negative pressure) of the intake system as the engine rotates. On the other hand, blow-by gas in the crankcase is guided to the valve operating chamber 4 of the cylinder head 2 through a passage in the cylinder block. The blow-by gas led to the valve chamber 4 is sucked into the shaft center passage lc from each suction port 1d at the front end of the camshaft 1 as shown by arrow A, and
The inside flows toward the rear as shown by arrow B.

The blow-by gas rotates together with the camshaft 1 while flowing backward in the passage lc, and the oil contained therein moves outward in the radial direction, causing the inner wall IC of the passage 1c to rotate.
This causes the blow-by gas and oil to be centrifugally separated.

The oil adhering to the inner wall 1c' of the passage 1c flows along the inner wall 1c' toward the rear end due to the negative pressure of the intake system and reaches the open end. The oil that has reached the opening end of this passage 1c flows radially outward along the outer end surface 1g of the oil slinger 1e due to centrifugal force as the camshaft 1 rotates, tHIt outward, and temporarily enters the gap 3a. It is stored. Also,
Oil that is supplied between the camshaft 1 and the bearing 3 and flows backward along the axial direction as the camshaft 1 rotates is also scattered outward by the inner end surface 1f of the oil slinger 1e and is temporarily stored in the gap 3a. be done. The oil stored in this gap 3a is discharged into the valve train chamber 4 as shown by the arrow through each groove 30.3C on both sides, and then passes through an oil return passage (not shown) provided in the cylinder head 2 to the crankshaft. It is refluxed into the case.

On the other hand, the blow-by gas from which the oil has been separated is discharged from the rear opening end of the passage IC of the camshaft 10 into the space 10 between the rear end surface 1a of the camshaft and the fitting 8, and passes through the nipple 8a and the tube 9 shown by the arrow C. The air is returned to the intake system as shown in . In this way, the blow-by gas led from the crankcase to the valve operating chamber 4 in the upper part of the cylinder head is returned to the intake system with most of the oil contained therein removed.

(Effects of the Invention) As explained above, according to the present invention, a passage is bored in the axis of the camshaft, one end of which opens in the circumferential surface near the front end of the camshaft, and the other end opens in the rear end face of the camshaft. an oil slinger is formed at the end thereof, and an oil relief passage is formed in a bearing that pivotally supports the rear end of the camshaft to collect oil scattered from the oil slinger and discharged into the valve train chamber; a fitting that surrounds the rear end of the camshaft and connects the passage to an intake system, and sucks blow-by gas led from the crankcase to the valve train chamber into the passage of the camshaft; Since the oil content is centrifugally separated in the passage and discharged from the oil relief passage to the valve train chamber, and only the blow-by gas is returned to the intake system, a baffle chamber is provided in the rocker cover attached to the cylinder head. As a result, the height of the rocker cover, that is, the overall height of the engine, can be reduced, making it possible to downsize the engine, and the structure of the rocker cover is simplified, reducing costs. There are excellent effects such as being able to reduce the amount of water used.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a camshaft with an oil separator mechanism according to the present invention. DESCRIPTION OF SYMBOLS 1...Camshaft, LC...Hole, 1d...Communication hole, 1e...Oil slinger, 2...Cylinder head, 3...Bearing, 3a...Gap, 3C... groove, 4
... Valve train chamber, 5... Oil seal, 6... Sprocket, 7... Bolt, 8... Fitting, 9...
··tube. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kanji Nagado

Claims (1)

[Claims] A passage is bored in the axial center of the camshaft, with one end opening in the peripheral surface near the front end of the camshaft and the other end opening in the rear end surface, and an oil slinger is formed at the rear end. An oil relief passage is formed in a supporting bearing to collect oil scattered from the oil slinger and discharged into the valve train chamber, and the passage is connected to an intake system by surrounding the rear end of the camshaft at the rear end of the bearing. A camshaft with an oil separator mechanism that is equipped with a fitting that communicates with the camshaft.