JP2012184668A - Overhead cam engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overhead cam engine capable of preventing oil mist from being exhausted from a cylinder head upper part.SOLUTION: In an overhead cam engine, in which a valve train camshaft is installed on an upper part of a cylinder head 1, a cam nose entrance groove 3 is provided at an upper part inner bottom surface of the cylinder head 1, and a cam nose of the rotating valve train camshaft enters the cam nose entrance groove 3, an oil outflow groove 5 and an oil flow-down hole 6 are provided at the upper part inner bottom surface of the cylinder head 1, the oil flow-down hole 6 is in communication with the cam nose entrance groove 3 via the oil outflow groove 5, engine oil flowing into the cam nose entrance groove 3 flows out to the oil flow-down hole 6 via the oil outflow groove 5, and flows down to an oil pan via the oil flow-down hole 6.

Description

  The present invention relates to an overhead cam type engine, and more particularly to an overhead cam type engine capable of suppressing oil mist discharge from the upper part of a cylinder head.

Conventionally, as an overhead cam engine, a valve camshaft is installed on the upper part of the cylinder head, a cam nose entry groove is provided on the upper inner bottom surface of the cylinder head, and the cam nose of the rotating valve camshaft enters the cam nose entry groove. There are some (see Patent Document 1, for example).
This type of overhead cam engine has the advantage that the height of the cylinder head can be kept low.
However, this prior art has a problem because there is no engine oil outflow means from the cam nose entry groove.

Japanese Patent Laid-Open No. 7-102933 (see FIGS. 1 and 2)

<Problem> A lot of oil mist may be discharged from the upper part of the cylinder head.
Because there is no engine oil outflow means from the cam nose entry groove, if engine oil leaking from the bearing part of the valve camshaft accumulates too much in the cam nose entry groove, much engine oil is swept up by the cam nose of the valve camshaft. The amount of generated oil mist increases, and a lot of oil mist may be discharged from the upper part of the cylinder head through the breather chamber.

  The subject of this invention is providing the overhead cam type engine which can suppress discharge | emission of the oil mist from a cylinder head upper part.

Invention specific matters of the invention according to claim 1 are as follows.
As illustrated in FIGS. 1 (A) and 1 (B), a valve camshaft (2) is installed on the top of the cylinder head (1), and a cam nose entry groove (3) is formed on the upper inner bottom surface of the cylinder head (1). In an overhead cam type engine provided with a cam nose (4) of a rotating valve camshaft (2) entering the cam nose entry groove (3),
As illustrated in FIGS. 3A to 3C, an oil outflow groove (5) and an oil flow down hole (6) are provided in the upper inner bottom surface of the cylinder head (1), and oil is provided in the cam nose entry groove (3). The oil flow hole (6) communicates with the outflow groove (5),
The engine oil that has flowed into the cam nose entry groove (3) flows out into the oil flow down hole (6) through the oil outflow groove (5) and flows down into the oil pan through the oil flow down hole (6). This is an overhead cam engine.

(Invention of Claim 1)
The invention according to claim 1 has the following effects.
<Effect> Oil mist can be prevented from being discharged from the upper part of the cylinder head.
As illustrated in FIGS. 3A to 3C, the engine oil that has flowed into the cam nose entry groove (3) flows out to the oil flow hole (6) through the oil flow groove (5), and the oil flow hole ( 6), the engine oil does not collect too much in the cam nose entry groove (3), and the cam nose (4) of the valve camshaft (2) illustrated in FIG. The generation amount of the oil mist that is lifted up is suppressed, and the discharge of the oil mist from the upper part of the cylinder head (1) can be suppressed.

(Invention of Claim 2)
The invention according to claim 2 has the following effect in addition to the effect of the invention according to claim 1.
<Effect> It is possible to adjust the lubrication of the valve camshaft by oil mist.
As illustrated in FIG. 3B, the groove inner bottom surface (7) of the oil outflow groove (5) is disposed at a position higher than the groove inner bottom surface (8) of the cam nose entry groove (3), thereby forming the cam nose entry groove. Since the engine oil that has flowed into (3) overflows into the oil outflow groove (5) and then into the oil flow down hole (6), the groove inner bottom surface (7) of the oil outflow groove (5) and the cam nose entry By adjusting the positional relationship between the groove (3) and the bottom surface (8) in the groove, the oil level of the engine oil accumulated in the cam nose entry groove (3) can be adjusted, and the amount of oil mist generated can be adjusted. This makes it possible to adjust the lubrication of the valve camshaft (2) by oil mist.

(Invention of Claim 3)
The invention according to claim 3 has the following effect in addition to the effect of the invention according to claim 1 or claim 2.
<Effect> It is possible to suppress discharge of engine oil from the upper part of the cylinder head.
As illustrated in FIG. 1B, the lower gap (17) is disposed at a relatively low position, and the front and rear gaps (18) and (19) are located away from the valve operating camshaft (2) to one side. Therefore, the engine oil lifted by the cam nose (4) of the valve drive camshaft (2) is unlikely to enter these gaps (17), (18), and (19).
Further, as illustrated in FIG. 1B, since the lower gap (17), the front and rear gaps (18) and (19), and the relatively large-capacity breather chamber entrance lower space (16) are provided, the oil mist is removed. The blow-by gas included flows from the entire area of the lower gap (17) and the front and rear side gaps (18) and (19) at a low speed into the lower space (16) at the inlet of the breather chamber. A large amount of oil mist is condensed on the surface of the plate (15), and the function of separating the engine oil is high.
For these reasons, the amount of oil mist entering the breather chamber inlet (14) is suppressed, and engine oil discharge from the top of the cylinder head (1) can be suppressed.

(Invention of Claim 4)
The invention according to claim 4 has the following effect in addition to the effect of the invention according to claim 3.
<Effect> The engine oil that has been lifted by the cam nose of the valve camshaft is unlikely to enter from both front and rear gaps.
As illustrated in FIG. 2A, the front and rear side plates (15b) and (15c) are oriented so as to gradually spread toward the lateral side wall (1a) of the cylinder head (1). Even if the engine oil swept up by the cam nose (4) collides with the front and rear plates (15b) and (15c), the side wall (1) of the cylinder head (1) on the surface of the front and rear plates (15b) and (15c) ( It is oriented in a direction that gradually expands toward 1a), and hardly enters from the front and rear side gaps (18) and (19).

(Invention according to claim 5)
The invention according to claim 5 has the following effect in addition to the effect of the invention according to claim 3 or claim 4.
<Effect> It is possible to suppress the oil mist from entering the breather chamber entrance.
As illustrated in FIG. 2B, a separating oil dropping hole (21) is formed in the breather chamber bottom wall (13), and the separating oil dropping hole (21) is disposed above the breather chamber inlet lower space (16). As a result, oil mist can be prevented from entering the breather chamber inlet (14).

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the overhead cam type engine which concerns on embodiment of this invention, FIG. 1 (A) is a vertical side view of a cylinder head and a cylinder head cover, FIG.1 (B) is a BB sectional view of FIG. FIG. FIG. 2A is a bottom view of a cylinder head cover to which a baffle plate is attached, and FIG. 2B is a view of a breather chamber bottom wall and a baffle plate. It is a B direction arrow directional view. FIG. 3A is a plan view of a cylinder head, FIG. 3B is a cross-sectional view taken along line BB in FIG. 3A, and FIG. ) Is a cross-sectional view taken along line CC of FIG.

  1 to 3 are diagrams for explaining an overhead cam type engine according to an embodiment of the present invention. In this embodiment, a vertical in-line two-cylinder overhead cam type spark ignition engine will be described.

In this engine, as shown in FIGS. 1A and 1B, a valve camshaft (2) is installed on the upper part of the cylinder head (1), and a cam nose entry groove ( 3) is provided so that the cam nose (4) of the rotating camshaft (2) enters the cam nose entry groove (3).
The valve camshaft (2) moves the exhaust valve (24) and the intake valve (25) via the rocker arms (22) and (23).
The valve camshaft (2) is supported by a pair of front and rear bearings (26) and (27).

As shown in FIGS. 3 (A) to 3 (C), an oil outflow groove (5) and an oil flow down hole (6) are provided in the upper inner bottom surface of the cylinder head (1), and the oil outflow into the cam nose entry groove (3). The oil flow hole (6) communicates with the groove (5).
Engine oil that has flowed into the cam nose entry groove (3) flows out to the oil flow down hole (6) through the oil outflow groove (5) and flows down to the oil pan (not shown) through the oil flow down hole (6). I have to.
The oil flow hole (6) is disposed on the exhaust side.
Engine oil leaking from the bearing portions (26), (27) of the valve drive camshaft (2) is accumulated in the cam nose entry groove (3).

  As shown in FIG. 3B, the groove inner bottom surface (7) of the oil outflow groove (5) is disposed at a position higher than the groove inner bottom surface (8) of the cam nose entry groove (3), and the cam nose entry groove ( The engine oil flowing into 3) overflows into the oil outflow groove (5) and then flows out into the oil flow down hole (6).

  As shown in FIGS. 1 (A) and 1 (B), the valve camshaft (2) is installed on the upper inner bottom of the cylinder head (1), and the cylinder cylinder head cover (11) is assembled on the cylinder head (1). The breather chamber (12) is provided on the ceiling of the cylinder cylinder head cover (11), the breather chamber inlet (14) is opened in the breather chamber bottom wall (13), and the baffle plate (15 When the baffle plate (15) obstructs the oil mist contained in the blow-by gas from entering the breather chamber inlet (14), the following is performed.

As shown in FIGS. 2A and 2B, the baffle plate (15) is a U-shaped plate that covers the breather chamber entrance lower space (16) from three sides, and the baffle plate (15) is a valve camshaft. A back plate (15a) along the front-rear direction, which is the installation direction of the valve camshaft (2), on one side of (2), and the valve camshaft (2) from the front and rear end edges of the backplate (15a) The front and rear side plates (15b) and (15c) are respectively led out toward the opposite side to the side.
As shown in FIG. 2B, a reed valve (32) is attached to the top of the breather chamber bottom wall (13), and this reed valve (32) faces the breather chamber inlet (14).
As shown in FIG. 1 (B), the baffle plate (15) is disposed on the side opposite to the engine oil splash-up side by the rotation (2a) of the valve drive camshaft (2).

As shown in FIGS. 1 (A) and 1 (B), the lower end edge (15d) of the baffle plate (15) is lowered to the height position of the valve operating camshaft (2), and the lower end edge (15d) of the baffle plate (15). And a lower gap (17) is formed between the upper inner bottom of the cylinder head (1).
As shown in FIG. 1B, the lower end edge (15d) of the baffle plate (15) is the uppermost part of the shaft portion (29) between the cam portions (28) and (28) of the valve operating camshaft (2). It is arranged at a position lower than the central axis (30) of the valve camshaft (2).
The lower end edge (15d) of the baffle plate (15) is a cam of the valve camshaft (2) from the viewpoint of suppressing the entry of oil mist from the lower gap (17) to be described later into the breather chamber inlet lower space (16). Although it is disposed at a position lower than the uppermost position of the cam nose (4) of the portion (28), it is preferably disposed lower than the uppermost portion of the basic circle of the cam portion (28), and more preferably than the uppermost portion of the shaft portion (29). It is more desirable to arrange it lower.

As shown in FIGS. 2A and 2B, the leading edges 15d and 15e of the front and rear plates 15b and 15c of the baffle plate 15 and the lateral side wall 1a of the cylinder head 1 are shown. ) And the front and rear clearances (18) and (19), respectively.
As shown in FIG. 1 (B), the storage space (20) of the valve camshaft (2) at the top of the cylinder head (1) and the breather chamber entrance lower space (16) surrounded by the baffle plate (15) are formed. The cylinder head (1) communicates with the lower gap (17) near the upper inner bottom and the front and rear gaps (18) (19) near the horizontal side wall (1a) of the cylinder head (1). .
As shown in FIG. 2 (A), the leading edges (15d) and (15e) of the front and rear side plates (15b) and (15c) of the baffle plate (15) are arranged on the side wall (1a) of the breather chamber bottom wall (13). ) Is led out to the position of the edge (13a) closer.

As shown in FIG. 2 (A), the front and rear side plates (15b) (15c) are oriented so as to gradually spread toward the lateral side wall (1a) of the cylinder head (1).
The front and rear side plates (15b) and (15c) are inclined at an angle of 110 ° with respect to the back plate (15a), but the oil mist from the front and rear side gaps (18) and (19) to the breather chamber inlet lower space (16) This angle is preferably 95 ° to 125 °, more preferably 100 ° to 120 °, and most preferably 105 ° to 115 °.

As shown in FIG. 2 (B), a separating oil dropping hole (21) is formed in the breather chamber bottom wall (13), and this separating oil dropping hole (21) is disposed above the breather chamber inlet lower space (16). ing.
Another separation oil dropping hole (31) is arranged in the breather chamber bottom wall (13).
Both separation oil dropping holes (21) and (31) are arranged in a point-symmetrical position with respect to the center point (13c) of the breather chamber bottom wall (13) so that the engine can be tilted in any of the front, rear, left and right directions. The separated oil falls from the breather chamber (12).
Both separation oil dropping holes (21) and (31) may be disposed at point-symmetrical positions with respect to the central portion of the breather chamber bottom wall (13).

(1) Cylinder head
(1a) One side wall
(2) Valve camshaft
(3) Cam nose entry groove
(4) Come nose
(5) Oil outflow groove
(6) Oil flow hole
(7) Bottom surface of oil outflow groove
(8) Bottom face of cam nose entry groove
(11) Cylinder cylinder head cover
(12) Breezer room
(13) Breezer room bottom wall
(14) Breezer room entrance
(15) Baffle plate
(15a) Backboard
(15b) Front plate
(15c) Rear side plate
(15d) Leading edge of front plate
(15e) Outlet edge of rear side plate
(16) Breezer room entrance space
(17) Lower gap
(18) Front gap
(19) Rear gap

Claims (5)

A valve camshaft (2) is installed on the upper part of the cylinder head (1), a cam nose entry groove (3) is provided on the upper inner bottom surface of the cylinder head (1), and the valve is rotated in the cam nose entry groove (3). In an overhead cam engine in which the cam nose (4) of the camshaft (2) enters,
An oil outflow groove (5) and an oil flow down hole (6) are provided in the upper inner bottom surface of the cylinder head (1), and an oil flow down hole (6) is provided in the cam nose entry groove (3) through the oil outflow groove (5). Communicate
The engine oil that has flowed into the cam nose entry groove (3) flows out into the oil flow down hole (6) through the oil outflow groove (5) and flows down into the oil pan through the oil flow down hole (6). This is an overhead cam engine. The overhead cam engine according to claim 1,
The oil bottom surface (7) of the oil outflow groove (5) is positioned higher than the bottom surface (8) of the cam nose entry groove (3) so that the engine oil flowing into the cam nose entry groove (3) An overhead cam type engine characterized by overflowing into the groove (5) and then into the oil flow hole (6). The overhead cam type engine according to claim 1 or 2,
A valve camshaft (2) is installed on the inner bottom of the upper part of the cylinder head (1), a cylinder cylinder head cover (11) is assembled on the upper part of the cylinder head (1), and a breather chamber ( 12), the breather chamber inlet (14) is opened in the breather chamber bottom wall (13), the baffle plate (15) is provided under the breather chamber bottom wall (13), and the oil mist contained in the blow-by gas is breathed by the breather. To obstruct the entrance to the room entrance (14) with the baffle plate (15),
The baffle plate (15) is a U-shaped plate that covers the breather chamber entrance lower space (16) from three sides, and the baffle plate (15) is located on the lateral side of the valve camshaft (2), on the valve camshaft. The back plate (15a) along the front-rear direction, which is the installation direction of (2), and the front and rear side plates derived from the front and rear end edges of the back plate (15a) toward the side opposite to the valve drive camshaft (2) side. (15b) (15c)
The lower end edge (15d) of the baffle plate (15) is lowered to the height position of the valve drive cam shaft (2), and between the lower end edge (15d) of the baffle plate (15) and the upper inner bottom of the cylinder head (1). A lower gap (17) is formed in
The front and rear side gaps (18) between the leading end edges (15d) and (15e) of the front and rear side plates (15b) and (15c) of the baffle plate (15) and the horizontal side wall (1a) of the cylinder head (1), respectively. 19)
The upper inner bottom portion of the cylinder head (1) is defined as a storage space (20) of the valve camshaft (2) at the upper part of the cylinder head (1) and a lower space (16) at the inlet of the breather chamber surrounded by the baffle plate (15). An overhead cam type engine characterized in that it communicates with a lower gap (17) closer to the front and rear gaps (18) and (19) closer to one side wall (1a) of the cylinder head (1). The overhead cam engine according to claim 3,
The overhead cam type engine characterized in that the front and rear side plates (15b) and (15c) are oriented so as to gradually spread toward the lateral side wall (1a) of the cylinder head (1). In the overhead cam type engine according to claim 3 or 4,
An overhead cam type engine characterized in that a separating oil dropping hole (21) is formed in the breather chamber bottom wall (13), and the separating oil dropping hole (21) is disposed above the breather chamber inlet lower space (16). .

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