JP2021143604A - Head cover seal structure - Google Patents

Abstract

To improve attaching/removing properties of a head cover.SOLUTION: A head cover seal structure is provided, in which a plurality of cylinders #1 to #4 is disposed in series. The seal structure is equipped with an insertion hole which is provided in the head cover for each cylinder, and in which an injector of each cylinder is inserted, and a seal ring 5 which is provided around the insertion hole in the head cover for each cylinder, and seals a gap between the insertion hole and the injector. An interference S1 of the seal ring of the cylinder located on one end side (front side) in a cylinder row direction is smaller than an interference S4 of the seal ring of the cylinder located on the other end side (rear side) in the cylinder row direction.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a seal structure of a head cover, and more particularly to a seal structure of a head cover of a group of cylinders in which a plurality of cylinders are arranged in series.

For example, in an in-line multi-cylinder direct injection internal combustion engine, a fuel injection injector for each cylinder is fixed to a cylinder head, and a head cover is mounted on the cylinder head. The head cover is provided with an insertion hole for each cylinder through which an injector of each cylinder is inserted. A seal ring is provided on the head cover for each cylinder to seal the gap between the insertion hole and the injector.

Japanese Unexamined Patent Publication No. 2009-236219

By the way, the head cover may be removed from the cylinder head when servicing an internal combustion engine or the like. At this time, the head cover may be lifted and removed by holding the one end in the longitudinal direction of the head cover, which is long in the cylinder row direction, and holding the other end by hand as a fulcrum and rotating the head cover.

In such a case, if the seal ring is tightly tightened to the injector, it becomes difficult to remove it. The same problem occurs when the head cover is attached by rotating it in the same manner after maintenance or the like.

Therefore, the present disclosure was conceived in view of such circumstances, and an object of the present disclosure is to provide a seal structure for a head cover capable of improving the detachability of the head cover.

According to one aspect of the present disclosure
It is a seal structure of the head cover of a group of cylinders in which multiple cylinders are arranged in series.
An insertion hole provided in the head cover for each cylinder and for inserting an injector of each cylinder,
A seal ring provided for each cylinder around the insertion hole in the head cover and seals the gap between the insertion hole and the injector.
With
The seal structure of the head cover is characterized in that the tightening allowance of the seal ring of the cylinder located on one end side in the cylinder row direction is smaller than the tightening allowance of the seal ring of the cylinder located on the other end side of the cylinder row direction. Provided.

Preferably, the tightening allowance of the seal ring of each cylinder is sequentially increased from one end side to the other end side in the cylinder row direction.

Preferably, the seal ring of each cylinder has a circular inner peripheral surface that contacts the injector, and the inner diameter of the seal ring of each cylinder is reduced from one end side to the other end side in the cylinder row direction. NS.

According to the present disclosure, the detachability of the head cover can be improved.

It is the schematic which shows the seal structure of a head cover. It is an enlarged view of the part II of FIG. It is the top view which shows the seal ring of each cylinder simplified.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the present disclosure is not limited to the following embodiments.

FIG. 1 is a schematic view showing a seal structure of a head cover according to the present embodiment. Such a seal structure is for sealing the gap between the head cover 1 and the fuel injection injector 2 in the in-line multi-cylinder direct injection internal combustion engine E. The internal combustion engine (also referred to as an engine) E of the present embodiment is a diesel engine for vehicles, but the type and use thereof are not particularly limited. For example, the engine may be a gasoline engine or a natural gas engine.

For convenience, each direction of front, back, left, right, up and down is defined as shown in the figure. However, it should be noted that each of these directions is only defined for convenience of explanation. The front-rear direction coincides with the cylinder row direction or the crankshaft direction. The vertical direction coincides with the cylinder axial direction.

The engine E of the present embodiment is an in-line 4-cylinder engine, and has # 1, # 2, # 3, and # 4 cylinders in order from the front side. A cylinder group is formed by these four cylinders. The number of cylinders can be any number of 2 or more.

The length of the engine E and the head cover 1 in the front-rear direction is larger than the width in the left-right direction. The front-rear direction means the longitudinal direction of the engine E and the head cover 1.

In the engine E, the cylinder head 4 is detachably attached to the cylinder block 3 by a plurality of bolts (not shown), and the head cover 1 is detachably attached to the cylinder head 4 by a plurality of bolts (not shown). ..

The injector 2 is fixed to the cylinder head 4 by a clamp member or the like (not shown). The injector 2 is arranged so that its central axis extends in the vertical direction. Fuel is directly injected into the cylinder from the injection hole at the lower end of the injector 2.

In each cylinder, a seal ring 5 for sealing the gap between the insertion hole (described later) of the head cover 1 and the injector 2 is provided. The details of this seal portion will be described below.

FIG. 2 shows the details of Part II of FIG. 1, that is, a partial cross section of the seal ring 5, and a head cover 1 and an injector 2 around the partial cross section.

As shown in the figure, the head cover 1 is provided with an insertion hole 6 for inserting an injector 2 of each cylinder for each cylinder. A seal ring 5 for sealing the gap between the insertion hole 6 and the injector 2 is provided for each cylinder around the insertion hole 6 in the head cover 1.

The insertion hole 6 has a central axis C1 (see FIG. 1) extending in the vertical direction, and is circular when viewed from above. A ring insertion hole 7 having an enlarged diameter is provided around the insertion hole 6. The lower end and the inner peripheral side of the ring insertion hole 7 are opened, while the upper end and the outer peripheral side thereof are closed. The seal ring 5 is detachably inserted into the ring insertion hole 7 from below, and is specifically press-fitted. The inner peripheral surface 7A of the ring insertion hole 7 has a flat cylindrical shape coaxial with the insertion hole 6.

The seal ring 5 has a circular ring shape as a whole, and has a substantially U-shaped or V-shaped cross-sectional shape with the upper side open, and is integrally formed of an elastic material such as rubber. The seal ring 5 integrally integrates the insertion cylinder portion 8 on the outer peripheral side, the contact portion 9 on the inner peripheral side, and the U-shaped or V-shaped connecting portion 10 that connects the insertion cylinder portion 8 and the contact portion 9. Have in.

When inserted into the ring insertion hole 7, the seal ring 5 is arranged coaxially with the insertion hole 6. That is, the central axis C2 of the seal ring 5 (see FIG. 1) and the central axis C1 of the insertion hole 6 coincide with each other.

The insertion tube portion 8 is a portion substantially inserted into the ring insertion hole 7. In order to increase the press-fitting strength and adhesion of the insertion cylinder portion 8 to the ring insertion hole 7, the outer diameter d1 of the insertion cylinder portion 8 is made larger than the inner diameter D1 of the ring insertion hole 7, and the outer peripheral surface of the insertion cylinder portion 8 is formed. The unevenness 11 is provided. Further, a metal core metal 12 is built in the insertion cylinder portion 8, and the rigidity of the insertion cylinder portion 8 is enhanced. The core metal 12 has a flat plate ring shape coaxial with the central axis C2 of the seal ring 5.

The contact portion 9 is a portion that comes into contact with the outer peripheral surface 2A of the injector 2. The inner diameter D2 of the contact portion 9 before the injector is inserted, that is, in the natural state, is made smaller than the outer diameter d2 of the outer peripheral surface 2A of the injector 2. As a result, the injector 2 is press-fitted into the contact portion 9, and at the same time, the connecting portion 10 is elastically deformed so as to close, and the contact portion 9 is elastically deformed in the diameter-expanding direction. Then, the contact portion 9 is brought into close contact with the injector outer peripheral surface 2A.

In order to increase the surface pressure of the contact portion 9 after the injector is inserted, a protrusion 13 having a substantially triangular cross section is provided on the inner peripheral surface of the contact portion 9 so as to project toward the inner peripheral side. The inner diameter D2 of the contact portion 9, that is, the inner diameter D2 of the seal ring 5, is defined by the inner diameter of the maximum protrusion position of the protrusion 13.

A metal core metal 14 is also built in the contact portion 9, and the rigidity of the contact portion 9 is increased. The core metal 14 has a flat plate ring shape coaxial with the central axis C2 of the seal ring 5.

The difference (d2 / 2-D2 / 2) between half of the outer diameter d2 of the injector 2, that is, the outer radius d2 / 2, and half of the inner diameter D2 of the seal ring 5, that is, the inner radius D2 / 2, is the tightening allowance of the seal ring 5. S is specified (S = d2 / 2-D2 / 2). As the tightening allowance becomes larger, the sealing ring 5 is tightened or fitted tightly to the injector 2, and the sealing property is improved, but it becomes difficult for the sealing ring 5 to be attached to and detached from the injector 2.

By the way, in the present embodiment, as shown in FIG. 1, when the head cover 1 is removed from the cylinder head 4 at the time of maintenance of the engine E or the like, first, the bolt fixing the head cover 1 is removed. Then, while grasping the front end portion of the head cover 1 which is long in the front-rear direction, the head cover 1 is lifted and removed by holding the rear end portion as a fulcrum and rotating the head cover 1 as shown by an arrow a.

On the other hand, if the tightening allowance of the seal ring 5 is large, the sealing property is good, but the head cover 1 is difficult to remove. In particular, the amount of movement of the seal ring 5 in the front-rear direction during rotation of the head cover 1 is larger on the front side in the front-rear direction than on the rear side. This is because the distance from the rear end, which is the fulcrum, is long. For this reason, the feeling of being caught on the front side becomes stronger, and the seal ring 5 becomes difficult to come off from the injector 2, which makes it difficult to remove the head cover 1.

The same problem occurs when the head cover 1 is similarly rotated and attached after maintenance or the like.

Therefore, in the present embodiment, the structure of the seal ring 5 is improved as follows in order to improve the detachability of the head cover 1.

FIG. 3 shows the seal ring 5 of each cylinder in a simplified manner from the top view. Reference numeral 2A indicates an outer peripheral surface of the injector 2 where the seal ring 5 is in contact. Reference numerals S1 to S4 indicate tightening allowances for the cylinders # 1 to # 4 (generally represented by the reference numeral S). The figure is deformed to emphasize the difference in the seal ring 5 of each cylinder.

As shown in the figure, the tightening allowance S of the cylinder seal ring 5 located on one end side, that is, the front side in the front-rear direction is smaller than the tightening allowance S of the seal ring 5 of the cylinder located on the other end side, that is, the rear side in the front-rear direction. Will be done.

That is, the tightening margins S1 to S4 of the seal ring 5 of each cylinder are sequentially increased from the front side to the rear side. S1 <S2 <S3 <S4.

The seal ring 5 of each cylinder has an inner peripheral surface 15 that is circular in top view and is in contact with the outer peripheral surface 2A of the injector. In the case of the present embodiment, as shown in FIG. 2, the inner peripheral surface 15 is formed by the surface of the maximum protruding portion of the protrusion 13.

Then, in order to realize the tightening margins S1 to S4 as described above, the inner diameter D2 of the seal ring 5 of each cylinder is reduced from the front side to the rear side. When the inner diameter of the inner peripheral surface of the seal ring of the # 1 to 4 cylinders is D2 _{1 to D2 4} , D2 ₁ > D2 ₂ > D2 ₃ > D2 ₄ .

In this way, the seal ring 5 of each cylinder has the same outer diameter d1, but the inner diameter D2 is different for each cylinder, and the inner diameter D2 is sequentially reduced toward the rear side.

According to the present embodiment, the tightening allowance S on the front side is made smaller than the tightening allowance S on the rear side. Therefore, when the head cover 1 is removed by lifting and rotating the front end portion of the head cover 1 as described above, the removal is easy. can do. That is, since the tightening allowance S is smaller on the front side where the amount of movement in the front-rear direction is large when the head cover 1 is rotated than on the rear side, the seal ring 5 can be easily pulled out on the front side and the feeling of being caught can be weakened accordingly. .. Thereby, the detachability of the head cover 1 can be improved.

Further, when the head cover 1 is removed, the amount of movement of the seal ring 5 in the front-rear direction when the head cover is rotated becomes smaller toward the rear side. It is increased toward the rear side. As a result, the tightening allowances S1 to S4 of each cylinder can be set to an optimum size that achieves both detachability and sealability.

The above points are the same when the head cover 1 is rotated and attached.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure may also include the following other embodiments.

(1) For example, the engine may be a V-type engine. In this case, the present disclosure can be applied to the cylinder group of each bank. For example, in a V6 engine, the present disclosure can be applied to a single bank cylinder group consisting of three cylinders.

(2) In the above embodiment, the tightening allowance S of all cylinders is different, but the tightening allowance S may be the same for some cylinders. For example, only the tightening allowance S1 of the frontmost # 1 cylinder is made smaller than the tightening allowance S2 to S4 of the remaining # 2 to # 4 cylinders, and the tightening allowance S2 to S4 of the # 2 to # 4 cylinders is the same. be able to. Alternatively, the tightening margins S1 and 2 of the # 1 and # 1 and 2 cylinders may be the same, the tightening margins S3 and 4 of the # 3 and 4 cylinders may be the same, and the tightening margins S1 and 2 may be smaller than the tightening margins S3 and 4.

(3) The shape and structure of the seal ring 5 are arbitrary and are not limited to those of the above embodiment. For example, one without a core or one with a different number of cores may be used.

The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the ideas of the present disclosure defined by the claims are included in the present disclosure. Therefore, this disclosure should not be construed in a limited way and may be applied to any other technique that falls within the scope of the ideas of this disclosure.

1 Head cover 2 Injector 5 Seal ring 6 Insertion hole 15 Inner peripheral surface

Claims (3)

It is a seal structure of the head cover of a group of cylinders in which multiple cylinders are arranged in series.
An insertion hole provided in the head cover for each cylinder and for inserting an injector of each cylinder,
A seal ring provided for each cylinder around the insertion hole in the head cover and seals the gap between the insertion hole and the injector.
With
A head cover seal structure characterized in that the tightening allowance of the seal ring of a cylinder located on one end side in the cylinder row direction is smaller than the tightening allowance of the seal ring of a cylinder located on the other end side of the cylinder row direction. The seal structure for a head cover according to claim 1, wherein the tightening allowance of the seal ring of each cylinder is sequentially increased from one end side to the other end side in the cylinder row direction. The seal ring of each cylinder has a circular inner peripheral surface in contact with the injector, and the inner diameter of the seal ring of each cylinder is reduced from one end side to the other end side in the cylinder row direction. The seal structure of the head cover according to 1 or 2.

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