JPS6349531Y2 - - Google Patents

Description

[Detailed description of the invention] A. Purpose of the invention (1) Industrial application field The present invention is a head cover of an engine, particularly a cylinder head having a valve chamber, which is fastened by a bolt penetrating the central part of the cylinder head. This invention relates to improvements to head covers that close valve chambers.

(2) Prior art The head cover of such an engine was developed in U.S. Pat.
This is already known as described in Japanese Patent No. 131930.

(3) Problems to be solved by the invention When the head cover is fastened to the cylinder head with a bolt passing through its center, the packing interposed between the head cover and the cylinder head has a good condition all around it. In order to perform a good sealing function, it is necessary to provide the head cover with sufficient rigidity, and for this purpose, conventionally, the head cover has been formed with a thick wall.

In addition, since a head cover is generally provided with a bulkhead plate equipped with a breather device to communicate the valve chamber with the atmosphere, conventional head covers are heavy due to the thick walls mentioned above. .

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a head cover for the engine that has sufficiently high rigidity, is lightweight, and has a simple structure despite being equipped with a breather device.

B. Structure of the invention (1) Means for solving the problems In order to achieve the above object, the head cover of the invention consists of an outer cover and an inner cover that are joined together by overlapping the peripheral parts and the central part. An atmospheric chamber is defined between the periphery and the center between these two covers, and an exhaust hole that communicates the atmospheric chamber with the atmosphere communicates with the outer cover and communicates the atmospheric chamber with the valve train chamber. Through holes are formed in each of the inner covers, and a check valve device that allows air to flow from the valve train chamber toward the atmospheric chamber through the through holes is provided on the inner surface of the inner cover on the atmospheric chamber side in proximity to the through holes. will be installed on the

(2) Effect A box-shaped structure is formed between the peripheral portion and the central portion between the outer cover and the inner cover, thereby effectively strengthening the rigidity of the entire head cover. Therefore, the tightening force of the bolts applied to the center of the head cover is reliably transmitted to the periphery of the cylinder head, so that the desired crimping is applied to the packing interposed between the periphery and the cylinder head over its entire circumference. Force can be applied evenly.

Further, the atmospheric chamber defined between the inner and outer covers, between the peripheral portion and the central portion, is effectively utilized as an installation space for the check valve device and an expansion chamber. The check mechanism of the check valve device and the function of the atmospheric chamber as an air expansion chamber suppress an increase in internal pressure in the valve operating chamber and effectively prevent leakage of lubricating oil from the chamber. I can do it.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 1, a cylinder head 1 of an engine is formed with a valve train chamber 3 that accommodates a valve train 2. The valve operating chamber 3 communicates with a crank chamber (not shown), and lubricating oil is circulated between the two chambers. The valve chamber 3 has an open upper surface, and a head cover 4 is attached to the cylinder head 1 to close it.
It is fastened to the upper end surface with a single bolt 5. At this time, the bolt 5 passes through the center portion C of the head cover 4 and is screwed onto the cylinder head 1.

The head cover 4 consists of an outer cover 4a and an inner cover 4b, both of which are made of steel plates.
a and 4b are overlapped and bonded to each other at the peripheral portion S and central portion C. Both covers 4a, 4
An atmospheric chamber A is formed between the peripheral portion S and the central portion C of b, and as shown in FIG. 2, this atmospheric chamber A is communicated with the atmosphere through an exhaust hole 7 provided in the outer cover 4a.

The circumferential edges S of the inner and outer covers 4b, 4a that are connected to each other are formed in a flange shape, and a packing is provided between the overlapping surfaces of the circumferential edges S and the cylinder head 1.
P ₁ is interposed. Further, a bolt hole 14 through which the bolt 5 passes is provided in the central portion C of both covers 4a and 4b, which are connected to each other, and a packing is also provided between the bolt hole 14 and the opposing circumferential surface of the bolt 5.
P ₂ is interposed.

A check valve device V that allows air to flow from the valve train chamber 3 toward the atmospheric chamber A side through the through hole 13 of the cover 4b is installed in the inner cover 4b in the vicinity of the through hole 13. It is attached to the inner surface of the atmospheric chamber A side. That is, the inner cover 4b has
An annular valve seat 8 is formed that protrudes toward the atmospheric chamber A side,
A check valve 9 is provided opposite to the valve seat 8. In order to hold the check valve 9, a valve holding plate 10 is welded to the inner cover 4b on the atmospheric chamber A side. A regulating annular projection 10a is formed. A swelling wall 11 that protrudes from the inner peripheral edge of the valve seat 8 toward the valve operating chamber 3 is integrally connected to the inner cover 4b, and the swelling wall 11 defines a damping chamber 12 between it and the check valve 9. do. A through hole 13 is bored at the bottom of the expansion wall 11, and the valve operating chamber 3 and the damping chamber 12 communicate with each other through the through hole 13. The through hole 1
The area of the check valve 3 is selected to be equal to or slightly larger than the area of the annular passage formed between the check valve 9 and the valve seat 8 when the check valve 9 is opened.

Next, the operation of this embodiment will be explained.

When assembling the head cover 4 to the cylinder head 1, when the bolts 5 inserted through the bolt holes 14 of the head cover 4 are screwed into the cylinder head 1 and tightened, the tightening force is applied to the packing _P2 and the packing P via the head cover 4. ₁ acts as a crimping force.

By the way, the head cover 4 has a double structure with inner and outer covers 4b and 4a, and an atmospheric chamber A is defined between them, and a box-shaped structure is formed between a central part C and a peripheral part S. As a result, high rigidity is given to the entire head cover 4, so that the tightening force of one bolt 5 is reliably transmitted from the center part C to the entire peripheral part S of the head cover 4, and is applied to the packing _P1 over its entire circumference. , the desired crimping force can be applied evenly. As a result, even by simply tightening one bolt 5, the packing _P1 can exhibit a good sealing function.

Furthermore, since the inner cover 4b also serves as a partition plate for the atmospheric chamber A serving as an expansion chamber, there is no need to provide a separate partition plate for it, and the structure can be simplified and the weight reduced.

During engine operation, when the crank chamber is pressurized with the downward stroke of a piston (not shown), the air in the valve chamber 3 communicating with the crank chamber is pumped through the air hole 1.
3 to the damping chamber 12, the check valve 9 is pushed open, the air passes through the valve seat 8, and is discharged into the atmosphere from the exhaust hole 7 through the atmospheric chamber A.

In this case, when the pressurized air in the valve train chamber 3 passes through the through hole 13 and moves to the damping chamber 12, it is attenuated and the flow velocity decreases. Even if it is carried vigorously, the room 12
It loses its force and falls without reaching the valve seat 8 and returns to the valve operating chamber 3 through the through hole 13. In addition, through hole 13
Since there is a sufficient distance between the valve seat 8 and the valve seat 8,
There are very few oil droplets that go straight from the valve train chamber 3 to the valve seat 8, and even if the oil droplets stick to the valve seat 8, the damping chamber 1
Depending on the pressure air whose flow rate is lowered in step 2, the oil droplets are less likely to be carried away from the valve seat 8 to the atmospheric chamber A. In this way, oil droplets are prevented from passing through the valve seat 8.

Next, when the pressure inside the crank chamber is reduced due to the upward stroke of the piston, the pressure inside the valve train chamber 3 is also reduced.
The check valve 9 receives negative pressure from the damping chamber 12 and closes, thereby preventing air from flowing backward from the atmospheric chamber A to the valve operating chamber 3. By opening and closing the check valve 9 in this manner, the internal pressures of the crank chamber and the valve operating chamber 3 are maintained at an average negative pressure, and leakage of lubricating oil from these chambers is prevented.

C. Effects of the invention As described above, the head cover of the present invention consists of an outer cover and an inner cover that are joined together by overlapping the peripheral parts and the central part, and there is no air between the peripheral parts and the central part between the two covers. A chamber is defined, and an exhaust hole that communicates the atmospheric chamber with the atmosphere is formed in the outer cover, and a through hole that connects the atmospheric chamber with the valve train chamber is formed in the inner cover, and the air flows through the through hole. A check valve device that allows air to flow from the valve chamber toward the atmospheric chamber is mounted on the inner surface of the inner cover on the atmospheric chamber side in close proximity to the through hole.
The rigidity of the head cover can be effectively strengthened by the box-shaped structure constructed between the central part and the peripheral part, thus reducing the tightening force of the bolts.
The packing interposed between the peripheral edge of the head cover and the cylinder head can be applied evenly and reliably over the entire circumference, and the packing can exhibit a good sealing function.

Further, the internal space of the box-shaped structure, that is, the atmospheric chamber, can be effectively used as an installation space and an expansion chamber for the check valve device, and in particular, the check valve device can be installed inside the inner cover after it has been set in advance. By simply joining the outer covers together, it can be easily assembled in place, and after assembly, the head cover is covered with the inner and outer covers and is not exposed to the outside, so the head cover can be attached to the cylinder head. Even if the check valve device is installed in the cylinder head or separated from the cylinder head for inspection and maintenance, there is no risk of the check valve device colliding with other objects and being damaged.Furthermore, since the check valve device does not protrude too far from the outer surface of the outer cover, the engine The appearance is also good. Furthermore, since the inner cover also serves as a partition plate for defining the atmospheric chamber as an expansion chamber, a dedicated large partition plate can be omitted, which contributes to simplifying the structure and reducing the weight of the head cover. Furthermore, the check mechanism of the check valve device and the function of the atmospheric chamber as an air expansion chamber suppress the increase in internal pressure in the valve operating chamber, and effectively prevent leakage of lubricating oil from the chamber. I can do it.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a vertical sectional side view of the main part of an engine equipped with the head cover of the present invention, FIG. 2 is a sectional view taken along the line -- in FIG.
3 and 4 are views in the direction of the arrows in FIG. 1. A...Atmospheric chamber, C...Central part, S...peripheral part,
V...Check valve device, 1...Cylinder head,
3... Valve train chamber, 4... Head cover, 4a... Outer cover, 4b... Inner cover, 5... Bolt,
7...exhaust hole, 13...through hole.

Claims (1)

[Scope of utility model registration request] This is an engine head cover that is fastened to a cylinder head 1 having a valve chamber 3 by a bolt 5 passing through a central portion C to close the valve chamber 3. Consisting of an outer cover 4a and an inner cover 4b that are bonded together by overlapping, an atmospheric chamber A is defined between a peripheral portion S and a central portion C between the two covers 4a and 4b, and the atmospheric chamber A is connected to the atmosphere. An exhaust hole 7 that communicates with the air chamber A is formed in the outer cover 4a, and a through hole 13 that communicates the atmospheric chamber A with the valve operating chamber 3 is formed in the inner cover 4b.
A check valve device V that allows air to flow from the valve train chamber 3 toward the atmospheric chamber A side through the through hole 13.
is attached to the inner surface of the inner cover 4b on the atmospheric chamber A side close to the through hole 13,
Engine head cover.