JP2000045860A - Cylinder head cooling device for overhead valve type engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To intensively cool a valve system supported onto a cylinder head. SOLUTION: A center cooling air passage 7 is arranged inside a cylinder head 2 of an overhead valve type engine 1. A rocker arm shaft 4 of a valve system 30 which opens and closes intake and exhaust valves 35, 36 is supported by a rocker arm bracket 15 attached to the cylinder head 2. A cooling fin 16 is arranged on a ceiling surface 11 of the cooling air passage 7 and lower side of the rocker arm bracket 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device provided in a cylinder head of an overhead valve type engine.

[0002]

2. Description of the Related Art An overhead valve type engine according to the present invention is constituted, for example, as follows. That is, an intake / exhaust port and an intake / exhaust valve are provided on the cylinder head of the engine, and a valve gear for opening / closing the intake / exhaust valve is provided on the cylinder head.

[0003] The valve train is constructed, for example, as follows. In other words, the valve train controls the intake and exhaust valves,
It is configured to be linked to a valve operating cam in a crank chamber via a rocker arm and a push rod. The push rod is driven up and down by the valve cam, and the rocker arm is vertically swung by the push rod, whereby the intake and exhaust valve is opened and closed.

Incidentally, the rocker arm is swingably supported by a rocker arm shaft disposed above the cylinder head, and the rocker arm shaft is supported by a rocker arm bracket mounted on the cylinder head. Have been. By lubricating the space between the rocker arm and the rocker arm shaft with lubricating oil, the rocker arm swings properly and the intake and exhaust valves open and close smoothly.

[0005]

However, in the above-described overhead valve type engine, if the temperature of the rocker arm shaft becomes too high, the lubricating performance between the rocker arm and the rocker arm shaft deteriorates. Therefore, the rocker arm cannot maintain proper swing. Therefore, it is necessary to cool the rocker arm shaft to maintain the lubrication performance. On the other hand, the cylinder head is cooled by a cooling medium such as cooling air or cooling water, and the rocker arm shaft can be cooled by transmitting the heat of the rocker arm shaft to the cylinder head.

However, since the rocker arm shaft is attached to the cylinder head via the rocker arm bracket as described above, the heat of the rocker arm shaft is transmitted to the cylinder head via the rocker arm bracket. However, there is a problem that the rocker arm shaft is hardly cooled. SUMMARY OF THE INVENTION An object of the present invention is to enable a valve train supported on a cylinder head to be cooled strongly. Still another object is to allow both the cylinder head and the valve gear to be cooled more strongly.

[0007]

Means for Solving the Problems [Invention of claim 1] The invention of claim 1 is, for example, shown in FIG.
As shown in FIG. 2 and FIG. 2, the configuration is as follows. A cooling passage (7) is provided in the cylinder head (2) of the overhead valve type engine (1), and a valve operating device (30) for opening and closing the intake and exhaust valves (35) (36) is mounted on the cylinder head (2). (1)
In the cylinder head cooling device for an overhead valve type engine supported by the cooling fin (5), a cooling fin (1) is provided on the passage ceiling surface (11) of the cooling passage (7) and below the support portion (15).
6) is provided.

[Invention of claim 2] The invention of claim 2 is the same as the above-mentioned invention of claim 1, but further configured as follows. The cooling fins (16) are arranged so as to extend along the direction of the cooling passage (7).

[Invention of claim 3] Further, the invention of claim 3 is the same as the above-mentioned invention of claim 1 or 2, further constituted as follows. The passage ceiling surface (11) of the cooling passage (7) is raised from the both sides (12) of the ceiling surface where the intake valve (35) and the exhaust valve (36) are located toward the center of the ceiling surface (13). It is formed in.

[0010]

The invention of claim 1 operates as follows, for example, as shown in FIGS. That is,
The support (15) that supports the valve gear (30) through the cooling fins (16) is strong by a cooling medium such as cooling air flowing in the cooling passage (7) in the cylinder head (2). Is cooled. As a result, the valve gear (30) via the support (15)
Is strongly cooled.

[Claim 2] The invention of claim 2 operates in the following manner in addition to the effect of the invention of claim 1. That is, since the cooling fins (16) extend in the direction of the passage of the cooling passage (7), the cooling medium smoothly flows in the direction of the cooling passage (7) along the cooling fins (16). Can flow.

[Claim 3] The invention of claim 3 operates in the following manner in addition to the operation of the invention of claim 1 or 2. That is, the passage cross-sectional area of the cooling passage (7) is increased by an amount corresponding to the height of the cooling passage (7). Thereby, the flow rate of the cooling medium flowing in the cooling passage (7) increases.

[0013]

[Embodiment 1] The invention of the above-described embodiment 1 has the following effects because it is configured and operates as described above. Cooling fins are provided on the passage ceiling surface of the cooling passage in the cylinder head, which is below the support portion that supports the valve gear, so that only the cooling fins are provided. The support located above the fins can be cooled strongly. As a result, the valve train is strongly cooled through the support, and the temperature rise of the valve train can be reliably prevented. Accordingly, it is possible to prevent the lubrication performance of the valve gear from deteriorating due to the above-mentioned high temperature, and to properly operate the valve gear to reliably obtain the proper opening and closing operation of the intake and exhaust valves. Moreover, by providing the cooling fins, the strength of the passage ceiling surface of the cooling passage can be increased, and the rigidity of the cylinder head can be maintained high.

[Claim 2] The invention of claim 2 has the following effects in addition to the effects of the invention of claim 1 since it is configured and operates as described above. Since the cooling fin extends along the direction of the passage of the cooling passage, the cooling medium smoothly flows in the direction of the passage of the cooling passage along the cooling fin. Accordingly, an increase in flow path resistance in the cooling passage due to the provision of the cooling fins in the cooling passage can be reduced, and a decrease in the flow rate of the cooling medium flowing in the cooling passage can be reduced. Thereby, both the cylinder head and the valve gear can be cooled more strongly.

[Claim 3] Since the invention of claim 3 is configured and operates as described above, it has the following effect in addition to the effect of the invention of claim 1 or 2. Since the passage cross-sectional area of the cooling passage is increased by an amount corresponding to the height of the cooling passage, the flow rate of the cooling medium flowing in the cooling passage is increased, thereby further improving both the cylinder head and the valve gear. Powerful cooling.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cylinder head cooling device for an overhead valve type engine according to the present invention will be described below with reference to FIGS. 1 is a longitudinal sectional view mainly showing a cylinder head of the engine, FIG. 2 (A) is a sectional view taken along the line II-II in FIG. 1, and FIG. 2 (B) is a sectional view taken along a line B in FIG.
FIG. 3 is a longitudinal sectional view showing the entirety of the engine. In this embodiment, a two-valve overhead valve gasoline engine of a forced air-cooled inclined type having a pent roof combustion chamber is described as an example.

A cylinder block (22) is provided integrally with a crankcase (21) of the engine (1), and a cylinder head (2) and a head cover (23) are fixed above the cylinder block (22). I have. Above cylinder block
A piston (24) is arranged in (22), and the piston
(24) is connected to a crankshaft (26) via a connecting rod (25). Crank gear (27) provided on the crank shaft (26)
, A governor gear (28) and a valve gear cam gear (29) are interlockingly connected. The cylinder head (2) has an intake valve.
(35) and an exhaust valve (36) are provided, and an intake port (3) and an exhaust port (5) are provided in the wall of the cylinder head (2). The intake port (3) communicates with the intake valve (35), and the exhaust port (5) communicates with the exhaust valve (36).

A valve operating device (30) for opening and closing the intake and exhaust valves (35) and (36) is arranged in the head cover (23). The valve operating device (30) is connected to a valve operating cam shaft via a tappet (32), a push rod (33), and a rocker arm (34) in this order.
The valve operating cam (31) and the intake / exhaust valves (35) and (36) are linked to each other. The rocker arm (34) of the valve operating device (30) is swingably supported on a rocker arm shaft (14) arranged above the cylinder head (2),
The rocker arm shaft (14) of the valve gear (30) is supported by a rocker arm bracket [support] (15) mounted on the cylinder head (2).

Then, the push rod (33) is moved up and down via the tappet (32) by the valve operating cam of the valve operating cam shaft (31), and the vertical movement is transmitted to the input portion of the rocker arm (34). As a result, the rocker arm (34) swings, and the upper ends of the intake and exhaust valves (35) and (36) are pushed by the output portion of the rocker arm (34), and the intake and exhaust valves (35) and (36) are moved. Opens and closes. The intake valve boss (4) is for supporting the intake valve (35), and the exhaust valve boss (6) is for supporting the exhaust valve (36).

On the other hand, a flywheel fan (3) connected to the front end of the crankshaft (26) is provided on the front side of the crankcase (21).
7) is provided, and the cooling air generated by the flywheel fan (37) is guided by the fan case (38) and the air guide cover (39) to the cylinder block (22) and the cylinder head (2).
The cylinder block (22) and the cylinder head (2) are cooled by flowing along the outer circumference of the cylinder. Also,
On both sides of the intake / exhaust ports (3) (5) of the cylinder head (2), cooling air passages (41) (42) extending in the front-back direction (vertical direction in FIG. 2 (B)) are provided, respectively. And a central cooling air passage that connects the cooling air passages (41) and (42) to each other.
(7) is provided. The central cooling air passage (7) is provided so as to pass between the intake and exhaust ports (3) and (5).

Further, the central cooling air passage (7)
As shown in the figure, the passage ceiling surface (11) becomes higher as it approaches the ceiling surface center portion (13) from both sides (12) of the ceiling surface where the intake valve boss (4) and the exhaust valve boss (6) are located. It is formed in an almost triangular shape. Further, two cooling fins (16) are provided on the passage ceiling surface (11) of the central cooling air passage (7) and below the rocker arm bracket (15). As shown in FIG. 2A, the cooling fins 16 are arranged so as to extend along the direction of the central cooling air passage 7.

On the other hand, one end of the central cooling air passage (7)
On the left side in FIG. 2A, a partition wall (18) is provided so as to close the upper part of the central cooling air passage (7). And
The cooling fin (16) is formed in a triangular shape that spreads downward from the other end of the central cooling air passage (7) toward one end, and one end of the cooling fin (16) is It is connected to the partition wall (18).

The cooling air from the flywheel fan (37) flows in the cylinder head (2) as follows. That is,
The cooling air flows backward through the cooling air passages (41) and (42) [FIG.
(B), while the central cooling air passage (7) is indicated by a solid arrow or a broken arrow according to the rotation direction of the flywheel fan (37) [right and left in FIG. 2 (B)]. Direction]. The rocker arm bracket (15) is cooled by the cooling air flowing through the central cooling air passage (7) through the cooling fins (16), and the rocker arm shaft (14) is cooled through the rocker arm bracket (15). ) Is cooled. The plug housing (10) of the ignition plug (9) attached to the ignition plug boss hole (8) is cooled by the cooling air flowing through the central cooling air passage (7).

As described above, the rocker arm bracket (1
Since the cooling fins (16) are provided below the cooling fins (16), the rocker arm bracket (15) cools down through the central cooling air passage (7) of the cylinder head (2) via the cooling fins (16). Cooled by wind. Therefore, the rocker arm shaft (14) supported by the rocker arm bracket (15) is cooled strongly, and the temperature of the rocker arm shaft (14) can be prevented from increasing. This can prevent a decrease in lubrication performance between the rocker arm (34) and the rocker arm shaft (14) due to the high temperature of the rocker arm shaft (14), and the rocker arm (34)
Can be surely swung.

Since one end of the cooling fin (16) is connected to the partition wall (18), burrs are formed on one end of the cooling fin (16) when the cylinder head (2) is cast. Can be prevented. Therefore, it is possible to reduce the time and effort required for burr processing in manufacturing the cylinder head (2). Moreover, the provision of the cooling fins (16) makes it possible to increase the strength of the passage ceiling surface (11) of the central cooling air passage (7).

In the above description, the cooling fins (16) are arranged along the direction of the central cooling air passage (7). However, the present invention is not limited to this. It may be arranged at right angles to the passage direction of the passage (7). In the above description, the rocker arm shaft (14) is cooled by using the cooling air. However, the present invention is not limited to this. For example, the intake port in the cylinder head (2) may be cooled.
A water jacket or an oil jacket may be arranged between (3) and the exhaust port (5), and cooling fins may be provided on the ceiling surface of the passage of the water jacket or the oil jacket. In that case, the rocker arm bracket (15) is cooled by cooling water or oil flowing through the water jacket or oil jacket.

Further, in the above description, the valve operating cam shaft (31) is arranged in the crankcase (21), and the rocker arm shaft (14) of the rocker arm (34) is arranged on the cylinder head (2). However, the present invention is also applicable to, for example, an OHC engine in which a valve operating camshaft is arranged above a cylinder head (2). In this case, the cooling fins are provided on the passage ceiling surface (11) of the central cooling air passage (7) and below the bearing portion supporting the valve cam shaft.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a cylinder head cooling device for an overhead valve type engine according to the present invention, and is a longitudinal sectional view mainly showing a cylinder head of the engine.

2 (A) is a sectional view taken along the line II-II in FIG. 1, and FIG. 2 (B) is a sectional view taken along the line BB in FIG. 2 (A).

FIG. 3 is a longitudinal sectional view showing the whole of the engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... overhead valve type engine, 2 ... cylinder head, 7 ... central cooling air passage [cooling passage], 11 ... ceiling surface of central cooling air passage, 12 ... both sides of ceiling surface of central cooling air passage, 13 ... central cooling Central part of ceiling of wind passage, 15 ... Rocker arm bracket
[Support part], 16: cooling fin, 30: valve gear, 35: intake valve, 36: exhaust valve.

Claims (3)

[Claims] Cylinder head of an overhead valve type engine (1)
A valve train (30) for providing a cooling passage (7) in the (2) and opening and closing the intake and exhaust valves (35) and (36) is provided by a support (15) provided on the cylinder head (2). A cylinder head cooling device for an overhead valve type engine to be supported, comprising: a passage ceiling surface (11) of the cooling passage (7);
(15) A cylinder head cooling device for an overhead valve type engine, wherein a cooling fin (16) is provided at a lower portion. 2. The cylinder head cooling device for an overhead valve type engine according to claim 1, wherein the cooling fins (16) are arranged so as to extend along a direction of the cooling passage (7). A cylinder head cooling device for an overhead valve type engine. 3. The cylinder head cooling device for an overhead valve type engine according to claim 1, wherein a passage ceiling surface (11) of the cooling passage (7) is connected to the intake valve (35).
A cylinder head cooling device for an overhead valve type engine, wherein the height is increased as the position approaches the ceiling surface center portion (13) from both sides (12) of the ceiling surface where the exhaust valve (36) is located. .