JPS6024920Y2 - Push rod chamber of overhead valve type engine - Google Patents

Description

[Detailed description of the invention] In a conventional overhead valve type engine, as shown in FIGS. 1 to 4, in order to introduce an appropriate amount of lubricating oil into the valve gear chamber a, The crank chamber was communicated with a push rod chamber C on the cylinder head j side, a push rod chamber d on the cylinder side, and a communication hole e.

In this case, in order to apply the cam f and the tappet g evenly and prevent local wear, the hole i in the tappet g is precisely machined so that the central axis of the tappet g is perpendicular to the central axis of the cam f. However, since the push rod chamber d on the cylinder side is deep, it is necessary to use a drilling jig.

However, if the cross section of the cylinder side push rod chamber d is circular as shown in FIG.
It was difficult to drill at right angles accurately.

In addition, since the cross-sectional areas of the cylinder head side push rod chamber C and the cylinder side push rod chamber d are the same, the lubricating oil that has risen in large quantities at high speeds flows directly into the valve train chamber a. There was a drawback that the lubricating oil was heated in the cylinder head j, the oil temperature rose, and the amount of oil jetted from the breather 1 increased.

This project relates to an improvement of the push rod chamber of an overhead valve type engine that overcomes these difficulties, and includes a cylinder head side push rod chamber formed in each of the cylinder head and inside the cylinder, into which the push rod is inserted and arranged in series. and a cylinder side push rod chamber, wherein one open end of the cylinder head side push rod chamber communicates with the valve gear chamber and the other open end communicates with the cylinder side push rod chamber, and the cylinder head side push rod chamber communicates with the cylinder side push rod chamber through a communication hole. The cross-sectional area of the cylinder-side push rod chamber is formed to be large, and the cross-sectional area of the cylinder head-side push rod chamber or the push rod hole of the head gasket interposed between the cylinder head and the cylinder is It is characterized by having a cross-sectional area smaller than that of the cylinder side push rod chamber, and its purpose is to prevent excessive lubrication at high speeds and to accurately process the tappet hole. The point is to provide a push rod chamber for an overhead valve type engine that can be used.

As described above, the present invention includes a cylinder head-side push rod chamber and a cylinder-side push rod chamber which are formed in the cylinder head and the cylinder, respectively, and are arranged in series with a push rod inserted therein, and the cylinder head side push rod chamber is arranged in series. One open end is communicated with the valve gear chamber and the other open end is communicated with the cylinder side push rod chamber, and the cylinder side push rod chamber is communicated with the crank chamber via a communication hole, and the cylinder side push rod chamber is communicated with the cylinder side push rod chamber. is formed to have a large cross-sectional area, and the cross-sectional area of the cylinder head-side push rod chamber or the push rod hole of the head gasket interposed between the cylinder head and the cylinder is configured to be smaller than the cross-sectional area of the cylinder-side push rod chamber. It is possible to increase the rigidity of the tappet hole drilling jig, accurately process the tappet hole, prevent uneven contact between the cam and the tappet, and prevent back wear as much as possible.

In addition, in this case, the cross-sectional area of the cylinder-side push-rod chamber is larger than the cross-sectional area of the cylinder head-side push-rod chamber or the push-rod hole of the head gasket interposed between the cylinder bed and the cylinder. Even if a large amount of lubricating oil is sometimes suppressed, it is throttled by the cylinder head side push rod chamber or cylinder by the push rod hole of the rad gasket, preventing the lubricating oil from flowing into the valve gear chamber, preventing excessive lubrication. This prevents an increase in oil temperature and an increase in oil jet from the breather.

The present invention will be explained below with reference to the embodiments shown in FIGS.
A piston 5 is rotatably supported and slidably fitted into a cylinder 4 above the crankcase 1, and the crankshaft 3 is connected by a connecting rod 6.

Further, an oil scraper plate 7 is fixed to the lower end of the connecting rod 6, and the oil scraper plate 7 allows lubricating oil to be collected at the bottom of the crank chamber 2.
It is designed to flip upward.

Further, a cylinder head 9 disposed above the cylinder 4
is provided with an intake valve 10, which is driven by an intake cam 14 via a rocker arm 11, a push rod 12, and a tappet 13.

A cylinder rad cover 16 is attached to the cylinder head 9 to cover the valve gear including the intake valve 10, rocker arm 11, exhaust valve 15, etc., and a valve gear chamber 17 is formed by the cylinder rad cover 16. has been done.

Further, push rod chambers 18 and 19 for accommodating the push rod 12 are formed in the cylinder 4 and the cylinder head 9, and the cylinder side push rod chamber 18 and the crank chamber 2 communicate with each other through a communication hole 20.

Furthermore, a breather 21 is attached to the upper part of the crankcase 1, and the breather 211 consists of an inner chamber 22, a check valve 23, and an exhaust port 24 to the atmosphere. Air passages 25, 26 respectively bored in the rad cover 16 to the cylinders.
The crank chamber 2 and the inner chamber 22 are communicated with each other through a small hole 28 formed in the bottom wall of the inner chamber 22 of the breather 21 .

As shown in FIG. 7, the cylinder side push rod chamber 18 is formed in an elliptical shape with a large cross-sectional area, and the cylinder head side push rod chamber 19 has a smaller cross-sectional area than the cylinder side push rod chamber 18. It is formed into a hole with a circular cross section.

Since the embodiments shown in FIGS. 5 to 8 are constructed as described above, when the pressure in the crank chamber 2 increases during engine operation, the gas in the crank chamber 2 is transferred to the oil scraper plate 7.
Both the oil droplets splashed up by the oil droplets (and the oil droplets) enter the valve train chamber 17 from the communication hole 20 through the push rod chambers 18 and 19.

At high speeds and high loads, the amount of blow-by gas increases, and the oil splashed up by the oil scraper plate 7 also increases in volume and at high speed, so the amount of oil that rises to the push rod chamber 18 increases. As shown in the figure, the cross-sectional area of the lower end of the cylinder head-side push rod chamber 19 is rapidly reduced compared to the cross-sectional area of the cylinder-side push rod chamber 18, so the oil is squeezed by the difference in cross-sectional area. and the lower surface 2 of the cylinder head 9.
9 (see Figure 5), separated, and fell downward.
As a result, an appropriate amount of oil is supplied to the valve train chamber 17.

Further, in the valve train chamber 17, the cylinder collides with the inner surface of the rad cover 16 and each member 10, 11, 15 of the valve train chamber, so that oil and air are separated, and the separated oil is After lubricating the device chamber, it is returned to the crank chamber 2.

Since the cylinder side push rod chamber 1B has an oval shape and a large cross-sectional area, the weight of the material is reduced during casting, and the rigidity of the tappet hole machining jig is increased, allowing accurate machining. Cost is lower.

Furthermore, since the cross-sectional area of the cylinder head side push rod chamber 19 is smaller than that of the cylinder side push rod chamber 18, excessive inflow into the valve gear chamber 17 during high-speed operation is prevented, thereby increasing the temperature of the lubricating oil. is prevented) also,
The oil from the breather 20 is gone, and the intake valve 10
This eliminates oil dripping into the cylinder 4 from the gap between the valve guide and the valve guide.

In the embodiments shown in FIGS. 5 to 8, the cross-sectional area of the cylinder-side push rod chamber 18 is formed to be large, and the cross-sectional area of the cylinder head-side push rod chamber 19 is smaller than the cross-sectional area of the cylinder-side push rod chamber 18. I explained the case where it is configured, but
Instead of the cross-sectional area of the cylinder head side push rod chamber 19, the push rod hole of the head gasket 30 interposed between the cylinder head 9 and the cylinder 4 may be made smaller than the cross sectional area of the cylinder side push rod chamber 18. Even in such an embodiment, the same effects as in the above embodiment can be achieved.

[Brief explanation of drawings]

Figure 1 is a vertical side view showing the push rod chamber of a conventional overhead valve type engine, Figure 2 is a vertical front view thereof, Figures 3 and 4.
The figures are a cross-sectional plan view cut along the lines ■-■ and IV-IV in FIG. 1, FIG. FIG. 6 is a longitudinal sectional front view thereof, and FIGS. 7 and 8 are cross-sectional plan views taken along lines 1--2 and 1--2 in FIG. 5. 1... Crank case, 2... Crank chamber, 3... Crankshaft, 4... Cylinder, 5... Piston, 6... ...Connecting rod, 7...Oil scraper plate, 8...Lubricating oil, 9
... Cylinder head, 10 ... Intake valve, 11 ... Rocker arm, 12 ...
Push rod, 13... Tappet, 14... Intake cam, 15... Exhaust valve, 16... Rad cover to cylinder, 17... Movement Valve device chamber, 1
8... Cylinder side push rod chamber, 19... Cylinder head side push rod chamber, 20... Communication hole, 21
...Please, 22...Inner room 23.
...Check valve, 24...Discharge port, 25.
26.27...Air passage, 2...Small hole, 29...Bottom surface of cylinder head, 30...
・Head gasket.

Claims (1)

[Scope of utility model registration request] A cylinder head side push rod chamber and a cylinder side push rod chamber are formed in each of the cylinder head and the cylinder, and a push rod is inserted into the inside and arranged in series, and the cylinder head side push rod chamber has one open end that is movable. The other open end of the valve device chamber communicates with the cylinder side push rod chamber, and the cylinder side push rod chamber communicates with the crank chamber via a communication hole, and the cylinder side push rod chamber has a large cross-sectional area. The overhead valve is characterized in that the cross-sectional area of the cylinder head-side push rod chamber or the push rod hole of the head gasket interposed between the cylinder head and the cylinder is smaller than the cross-sectional area of the cylinder-side push rod chamber. Push rod room of the formula engine.