JP2002115603A - Sealing structure for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing structure for an engine, assuring high sealing property in a space between the opposed faces of a cylinder block and a cylinder head without requiring a cylinder head gasket. SOLUTION: The cylinder block 10 has an annular protruded portion 15 at the outer edge of each cylinder bore 13. The space between the opposed faces of the cylinder block 10 and the aluminum cylinder head 11 is sealed based on the elastic deformation thereof utilizing the protruded portion 15 due to the tightening force of a head bolt 12. The space between the opposed faces is filled with a micro-seal. The height and width of the protruded portion 15 and a distance from the center of each cylinder bore 13 to the inner periphery of the protruded portion 15 are so set that the displacement of the cylinder head 11 with the operation of the engine is minimized, depending on the quality of the cylinder head 11, the tightening position and force of the head bolt 12 and the displacement of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure for an engine, and more particularly to a structure for sealing between a cylinder block and a cylinder head of an engine.

[0002]

2. Description of the Related Art As is well known, an engine includes a cylinder block and a cylinder head that covers an upper surface of the cylinder block. Usually, the cylinder head is fastened to the cylinder block by a head bolt.

By the way, in such an engine, during operation, a high combustion pressure acts on the cylinder head, and the lower surface tends to be displaced away from the cylinder block. The force acting on the cylinder head in this way is a major factor that impairs the sealing performance between the opposing surfaces of the cylinder head and the cylinder block.

Therefore, conventionally, in such an engine, a cylinder head gasket is provided between the opposing surfaces of the cylinder block and the cylinder head. The cylinder head gasket is usually provided with a bead or a sealing material at a portion corresponding to a peripheral edge of a cylinder bore of the cylinder block.

By providing such a cylinder head gasket, even if the lower surface of the cylinder head is displaced as described above, the bead or the sealing material absorbs the displacement. Then, by absorbing this displacement, fluctuations in the surface pressure distribution between the opposing surfaces of the cylinder block and the cylinder head that sandwich the cylinder head gasket are suppressed, and as a result, the sealing property between the opposing surfaces is ensured. Become.

[0006]

As described above, according to the conventional sealing structure using the cylinder head gasket, the displacement of the cylinder head is absorbed through the bead or the like provided on the cylinder head gasket, and the cylinder block and the cylinder are removed. The sealing property between the heads can be ensured. However, in the same seal structure, it is necessary to dispose such a cylinder head gasket.
An increase in the number of parts in the engine as a whole is inevitable, and inevitably disadvantages in terms of workability and cost involved in assembling the engine are inevitable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to ensure a high sealing property between opposed surfaces of a cylinder block and a cylinder head without requiring a cylinder head gasket. It is an object of the present invention to provide an engine seal structure that can be used.

[0008]

The means for achieving the above object and the effects thereof will be described below. The invention according to claim 1 is an engine sealing structure for sealing between a cylinder block of an engine and a cylinder head fastened to a top surface thereof by a fastening member, wherein at least one of the cylinder block and the cylinder head abuts. The gist is that a projection is provided on the surface, and sealing between the cylinder head and the cylinder block is performed based on elastic deformation of at least one of the cylinder head and the cylinder block using the projection by the fastening force of the fastening member. I do.

According to the above configuration, at least one of the cylinder block and the cylinder head generates an elastic force due to the elastic deformation. This elastic force becomes a non-linear spring force,
It acts in a direction opposing the combustion pressure at the time of fuel combustion. Therefore, even when an aluminum cylinder block and a cylinder head that are particularly easily deformed are used, the deformation of the cylinder block and the cylinder head can be suppressed during operation of the engine. A high sealing performance between the opposing surfaces of the cylinder block and the cylinder head can be ensured with a simple configuration without the need for a cylinder head gasket.

According to a second aspect of the present invention, in the engine seal structure according to the first aspect, the protrusion is provided so as to surround an outer edge of a cylinder bore of the cylinder block, and the protrusion is provided from the cylinder bore. The point is that at least one of the distance to the outer periphery and the height of the protruding portion is formed so as to change along the outer periphery of the cylinder bore.

According to the above construction, by providing the projection so as to surround the outer periphery of the cylinder bore, when the cylinder head is fastened to the cylinder block by the fastening member, the projection is formed on the entire circumference of each cylinder bore of the cylinder block. The contact pressure acts between the lower surface of the cylinder head or the upper surface of the cylinder block that contacts the projection. Also, by changing at least one of the distance from the cylinder bore to the outer periphery of the projection and the height of the projection along the outer circumference of the cylinder bore so that the contact pressure acts on the projection almost uniformly, the cylinder head A high sealing property between the opposing surfaces of the cylinder block and the cylinder head can be suitably secured without the need for a gasket.

According to a third aspect of the present invention, in the seal structure of the engine according to the first aspect, the protrusion is formed of a material of the cylinder head, a fastening position or a fastening force of the fastening member, or a displacement of the engine. Accordingly, the height or the distance from the cylinder bore of the cylinder block to the cylinder bore is set so that displacement of the lower surface of the cylinder head accompanying the operation of the engine can be suppressed.

According to the above configuration, it is possible to reliably ensure the seal between the cylinder block and the cylinder head in any engine. According to a fourth aspect of the present invention, in the seal structure of the engine according to any one of the first to third aspects, at least a portion between a contact surface between the cylinder block and the cylinder head is filled with a sealant. The gist is to be done.

According to the above-mentioned structure, even if there are minute irregularities generated during the processing on the contact surface between the cylinder block and the cylinder head, the sealing agent enters the irregularities. Can more suitably ensure the sealing property between the opposing surfaces.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a seal structure according to the present invention; FIG.

First, the configuration of an engine to which this seal structure is applied will be described with reference to FIGS.
As shown in FIG. 1, this engine includes an aluminum cylinder head 11 disposed to cover a cylinder block 10 and an upper surface 10a of the cylinder block 10.
And the like. And the cylinder head 11
Is fastened to the cylinder block 10 by being tightened from above by a head bolt 12. In addition,
As shown in FIG. 2, the cylinder block 10 has a predetermined number of cylinder bores 13, a predetermined number of bolt holes 14 into which head bolts 12 are screwed, and an oil passage (not shown) through which lubricating oil flows. And a cooling water passage (not shown) through which cooling water flows.

The upper surface 10 of the cylinder block 10
As shown in FIG. 1 and FIG. 2, an annular projection 15 surrounding each of the cylinder bores 13 is formed to protrude. The protrusion 15 has the same center axis and the same radius L as the cylinder bore 13 and has a predetermined height H and width W.
It is formed with.

On the other hand, the cylinder head 11 has a surface m passing through its center before being fastened to the cylinder block 10.
Is a plane. And the cylinder head 11
Are provided with the same number as the bolt holes 14 of the cylinder block 10 and through holes 16 through which the head bolts 12 are inserted.
And an oil passage and a cooling water passage (not shown) communicating with the oil passage and the cooling water passage of the cylinder block 10, respectively.

When the cylinder head 11 having such a structure is fastened to the cylinder block 10 by using the head bolts 12, a micro seal 17, for example, an adhesive or a pressure-sensitive adhesive, is formed on the entire upper surface 10a of the cylinder block 10. , Silicone gel, fluorine gel, vulcanized rubber, and unvulcanized rubber. Then, after the micro-seal is applied, the cylinder block 10 and the cylinder head 11 are brought into contact with each other, and these are fastened with the head bolts 12.

In the present embodiment, as described above, the protrusion 1 is provided on the periphery of the cylinder bore 13 of the cylinder block 10.
5, the cross-sectional structure after fastening by the head bolt 12 is as shown in FIG. That is, when the cylinder head 11 is fastened to the cylinder block 10 by the head bolt 12, the cylinder head 11
The cylinder head 11 is slightly elastically deformed in such a manner that the vicinity of the portion corresponding to the cylinder bore 13 is lifted upward. Although not shown in FIG. 3, the cylinder block 1 is fastened as described above.
0 is also slightly elastically deformed.

As described above, when the cylinder block 11 and the cylinder head 11 are elastically deformed by using the projections 15 when the cylinder head 11 is fastened to the cylinder block 10 by using the head bolts 12, the engine can be used. It has been confirmed by the inventor that deformation of the cylinder head 11 during operation can be suppressed. Then, as shown in FIG. 4 showing the results of the measurement performed by the inventor in a graph, the cylinder head 1 is moved in accordance with the height H of the protrusion 15.
It has also been confirmed that the amount of displacement of the lower surface of No. 1 differs.

Next, the measurement results will be described with reference to the graph of FIG. FIG. 4 shows the measurement results of the maximum displacement of the lower surface of the cylinder head when the engine is operated while changing the height H by using the cylinder block having the protrusions of the above-described embodiment. It is.
In this graph, the height H of the protrusion is “0 mm”,
"0.02mm", "0.05mm", "0.08m
The maximum displacement amounts of the portions that contact the protrusions on the lower surface of the cylinder head when the distance is set to “m” and “0.1 mm” are shown. Here, as the maximum displacement increases, the gap between the contact surfaces between the cylinder head and the projections increases. The engine used in this measurement was a gasoline engine having a displacement of 1.8 liters, and was equipped with an aluminum cylinder head. And this cylinder head is 50kN
It is fastened to the cylinder block by the head bolt 12 with a (constant) fastening axial force.

As is clear from the graph of FIG. 4, the height H of the projection is "0 mm", that is, the height H of the projection is changed from "0" to the state in which the cylinder head is fastened to the cylinder block without elastically deforming the cylinder head. 0.02mm "," 0.05m
m "and" 0.08 mm ", and the amount of elastic deformation at the time of fastening the cylinder head increases, the maximum displacement of the cylinder head tends to gradually decrease. When the height H of the projection is "0.08 mm", the maximum displacement is the smallest.

On the other hand, assuming that the height H of the projection is "0.1 mm", the height H is "0.08 mm".
The maximum displacement of the cylinder head is slightly larger than that in the case described above. Then, as shown by the broken line in FIG. 4, when the height H of the protrusion is larger than “0.1 mm”, the maximum displacement of the cylinder head tends to gradually increase. Have been.

As shown in the measurement results of the graph of FIG. 4, when the height H of the protrusion of the cylinder block is set to an appropriate value and the cylinder head is elastically deformed, the cylinder head 11 during operation of the engine is operated. It can be seen that the amount of displacement of the lower surface of can be reduced.

The value of the measurement result shown in FIG.
Not common to all engines. This value varies depending on the material of the cylinder head, the fastening position and the fastening force of the head bolt, the displacement of the engine, and the like, and the distance L from the center of the cylinder bore 13 to the inner peripheral surface of the projection is changed.
Is a value that changes depending on the value. For this reason, it is desirable that the height H and the distance L of the protruding portion be set to effective values obtained by experiments or analysis.

Although not shown here, the radial width W of the projection is also measured by the inventor, and the height H of the projection is set to "0.08 mm". It has been confirmed that the maximum displacement of the cylinder head can be minimized by setting the width W in the range of “1.5 mm” to “8 mm”.

In the case of a gasoline engine having a displacement of 1.8 liters and having an aluminum cylinder head, the cylinder block 10 has a height H and a width which can minimize the displacement of the lower surface of the cylinder head 11 described above. It has also been confirmed by the inventor that if a protrusion having W is provided and silicon gel is applied as the microseal 17 between the contact surfaces of the cylinder block 10 and the cylinder head 11, a combustion pressure of 4 MPa can be sealed.

As described above, when the projection 15 is provided on the upper surface 10a of the cylinder block 10, and the cylinder head 11 is fastened to the cylinder block 10 by the head bolt 12, the cylinder block 10 and the cylinder head 11 are elastically deformed. With this elastic deformation, the cylinder head 11
Generates an elastic force, which acts as a non-linear spring force on the projection 15 of the cylinder block 10. For this reason, even when the cylinder block 10 and the cylinder head 11 made of aluminum, which are particularly easily deformed, are used, the deformation of the cylinder head 11 can be suppressed during the operation of the engine. A high sealing performance between the opposing surfaces of the cylinder block 10 and the cylinder head 11 can be ensured with a simple configuration without requiring a cylinder head gasket.

The height H and width W of the projection 15 and the distance L from the center of each cylinder bore 13 to the inner circumference of the projection 15 are determined by the material of the cylinder head, the fastening position and fastening force of the head bolt 12, and the engine. Setting according to the displacement of the cylinder block, it is possible to reliably ensure the sealing performance between the cylinder block and the cylinder head.

Further, the protrusion 15 is connected to the cylinder bore 13.
Are formed in an annular shape surrounded by the cylinder block 11, and the elastic force of the cylinder head 11 generated when the cylinder head 11 is assembled to the cylinder block 10 causes the projection 15 of the cylinder block 10 and the contact surface between the cylinder head 11 to contact each other. The contact pressure acts. As described above, since the displacement of the cylinder head 11 due to the combustion pressure during the operation of the engine is suppressed by this elastic force,
The fluctuation of the contact pressure can be suppressed, and thereby, a high sealing property between the opposing surfaces of the cylinder block 10 and the cylinder head 11 can be ensured.

Since the micro-seal 17 is filled between the contact surfaces of the cylinder block 10 and the cylinder head 11, there are small irregularities generated during the machining on the contact surfaces of the cylinder block 10 and the cylinder head 11. However, since the micro seal 17 enters the unevenness, the sealing property between the cylinder block 10 and the cylinder head 11 can be more appropriately maintained.

As described in detail above, according to the engine seal structure of this embodiment, many excellent effects as described below can be obtained. (1) The cylinder head 11 is elastically deformed by using the projection 15 of the cylinder block 10, so that the deformation of the cylinder head 11 due to the high combustion pressure is suppressed, and a cylinder head gasket is required. Without these cylinder blocks 1
High sealing performance between the opposing surfaces of the cylinder head 11 and the cylinder head 11 can be ensured.

(2) The height H and width W of the projection 15 and the distance L from the center of each cylinder bore 13 to the inner periphery of the projection 15 are determined by the material of the cylinder head and the fastening position and fastening of the head bolt 12, respectively. Since the setting is made in accordance with the force and the displacement of the engine, the sealing property between the cylinder block 10 and the cylinder head 11 can be reliably ensured.

(3) Since the projections 15 are formed in a ring shape in which the cylinder bores 13 are individually surrounded, high sealing performance between the opposing surfaces of the cylinder block 10 and the cylinder head 11 can be ensured. Become.

(4) Since the micro-seal 17 is filled between the contact surfaces of the cylinder block 10 and the cylinder head 11, the sealing property between these opposing surfaces can be more appropriately ensured.

(5) Since the cylinder head gasket provided in the conventional engine is not required, the number of parts can be reduced, and the workability and cost for assembling the engine can be improved.

(6) Even when the aluminum cylinder head 11 that is easily deformed is used, the displacement of the cylinder head 11 due to the high combustion pressure can be suppressed.

(7) Projection 15 of cylinder block 10
Since the cylinder head 11 is elastically deformed by the axial force generated by the tightening of the head bolt 12 using the above, the cylinder head 11 can be elastically deformed with a simple structure.

In the above embodiment, for example, the configuration can be appropriately changed as follows. In the above embodiment, the height H and the width W of the projection 15 are set according to the material of the cylinder head, the fastening position and the fastening force of the head bolt, and the displacement of the engine. And the width W may be set in accordance with an arbitrary element among the material of the cylinder head, the fastening position and fastening force of the head bolt, and the displacement of the engine.

In the above embodiment, the projections 15 of the cylinder block 10 are provided in an annular shape in which the cylinder bores 13 are individually surrounded. However, the shape of the projections is not limited to an annular shape. The shape of the protrusions can be set arbitrarily. For example, as shown in FIG.
It may be configured to be continuous with the outer periphery of. In FIG. 5, the same components as those in FIG. 3 are denoted by the same reference numerals.

(Other Embodiments) Next, in another embodiment which embodies the seal structure of the present invention, a cross-sectional structure corresponding to a cross-sectional structure along line 6-6 in FIG. 5 is shown. This will be described with reference to FIG. In FIG. 6, the same components as those in FIG. 1 are denoted by the same reference numerals.

This embodiment is the same as the previous embodiment in that the projection 15 is provided so as to surround the outer edge of the cylinder bore 13, but the height H of each projection 15 is It differs in that it is formed to change along the outer circumference.

As shown in FIG. 5, the projections 15 are provided so as to surround the cylinder bores 13 of the cylinder block 10, and the outer periphery of each projection 15 is
5 is continuous with the outer periphery.

As shown in FIG. 6, the height H of each of the projections 15 is, for example, the lowest in the portion A closest to each of the bolt holes 14, and the highest in the portion C most distant, for example. As described above, the pressure changes smoothly along the outer circumference of the cylinder bore 13. The height H of each projection 15 is determined by an experiment or analysis so that the contact pressure acting on each projection 15 when the cylinder head 11 is assembled to the cylinder block 10 with the head bolt 12 is substantially uniform. It is desirable to set to the effective value required in the above.

As described above, according to the engine seal structure of this embodiment, the following effects can be obtained. (1) During operation of the engine, the contact pressure acting on the entire periphery of each projection 15 becomes substantially uniform, so that the cylinder block 10 and the cylinder head 11 face each other without the need for a cylinder head gasket. High sealing performance can be suitably secured.

In the above embodiment, for example, the configuration can be appropriately changed as follows. In the above embodiment, the outer periphery of each projection 15 is formed in an arc shape, and the height H is changed along the outer edge of the cylinder bore 13. However, as shown in FIG. 7 showing the top structure of the cylinder block 10, the height H
May be made constant, and the distance L3 from the cylinder bore 13 to the outer periphery of each projection 15 may be changed along the outer periphery of the cylinder bore 13. Further, both the distance L3 and the height H may be changed along the outer periphery of the cylinder bore 13. The distance L3 and the height H
Is preferably set to an effective value obtained by an experiment, analysis, or the like so that the contact pressures acting on the protrusions 15 during the operation of the engine are substantially uniform.

Other modifiable elements common to the above embodiments include the following. In the above embodiments, the radius of the cylinder bore 13 and the radius L of the projection 15 are the same, but the radius L may be larger than the radius of the cylinder bore 13.

In each of the above embodiments, the upper surface of the projection 15 of the cylinder block 10 is formed so as to be parallel to the upper surface 10a of the cylinder block 10. However, the shape of the upper surface of the projection is arbitrary. For example, the cylinder head 11 may be inclined in accordance with the inclination of the elastic deformation, or may be formed to have an arcuate curved surface.

In the above embodiments, the projection 15 is formed on the cylinder block 10. However, the projection may be formed on the cylinder head 11. The projections may be formed on both the cylinder block 10 and the cylinder head 11, and both projections may be brought into contact when the cylinder block 10 and the cylinder head 11 are fastened.

FIG. 8 is a partial cross-sectional view in which the vicinity of the protrusion is enlarged, and the diameter of the protrusion 1 of the cylinder head 11 is larger than that of the protrusion 15 of the cylinder block 10.
The maze chamber 19 may be formed between the projections 15 and the projections 18 provided with the projections 18 surrounding the projections 5. In this case, the gas burned in the combustion chamber of the engine hardly blows through between the opposing surfaces of the cylinder block 10 and the cylinder head 11.

An annular groove 20 may be provided on the outer edge of the projection 15 of the cylinder block 10 as shown in FIG.
In this case, it is possible to prevent the micro seal 17 filled between the cylinder block 10 and the cylinder head 11 from entering the cylinder bore 13.

In the above embodiments, the cylinder head 11 made of aluminum is used, but the cylinder head is not limited to aluminum. The present invention can be applied to, for example, an engine provided with an iron cylinder head.

In each of the above embodiments, the micro-seal 17 is filled in the entire contact surface between the cylinder block 10 and the cylinder head 11, but the micro-seal 17 is formed by the projection on the contact surface. It may be configured to fill only a part near the outer edge of the portion 15 or near the periphery of the oil passage and the cooling water passage.

In the above embodiments, the projection 15 is provided so as to surround the outer edge of the cylinder bore 13, but the shape of the projection is not limited to this. The shape of this protrusion can be set arbitrarily. As shown in FIG.
May be provided. Even in this case, the cylinder head 11 is not
As long as at least one of the cylinder block 10 and the cylinder block 10 can be elastically deformed, the height of the projection 18, the distance L1 from the center of each cylinder bore 13 to the outer edge of the projection 18, and the projection from the center of each bolt hole 14 The distance L2 to the outer edge of each of the projections 18 suppresses the displacement of the cylinder head 11 due to the operation of the engine in accordance with the material of the cylinder head or the fastening position or the fastening force of the head bolt and the displacement of the engine for each projection 18. It can be set to a value to get. The height or height of the projections 18, the distance L1 from the center of each cylinder bore 13 to the outer edge of the projection 18, and the distance L2 from the center of each bolt hole 14 to the outer edge of the projection 18 are also experimentally or analyzed. It is desirable to set to an effective value required by the above. In FIG. 10, the same components as those in FIG. 3 are denoted by the same reference numerals.

Other technical ideas which can be grasped from the above embodiment and the above description will be described below. (A) The protrusion is provided on both the cylinder block and the cylinder head, and one of the protrusions has an inner diameter larger than the outer diameter of the other protrusion, and the other protrusion has the same diameter. The engine seal structure according to claim 3, wherein the seal structure is formed so as to surround the engine.

(B) The engine seal structure according to claim 4, wherein the protrusion is provided on the cylinder block, and an annular groove is formed on an outer edge of the protrusion.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a cross-sectional structure of a cylinder block and a cylinder head of an engine to which a first embodiment of a seal structure according to the present invention is applied before assembly.

FIG. 2 is a plan view showing a top structure of a cylinder block employed in the seal structure of the embodiment.

FIG. 3 is an exemplary sectional view showing the sectional structure of the seal structure according to the embodiment;

FIG. 4 is a graph showing the relationship between the height of a protrusion and the maximum displacement of the lower surface of a cylinder head.

FIG. 5 is a plan view showing a top structure of a cylinder block according to another embodiment.

FIG. 6 is a sectional view taken along line 6-6 in FIG. 5;

FIG. 7 is an enlarged plan view showing a part of the upper surface structure of a cylinder block of a modification of the other embodiment.

FIG. 8 is a partial cross-sectional view showing a cross-sectional structure in the vicinity of a protrusion of a modification of the first embodiment and another embodiment.

FIG. 9 is a partial cross-sectional view showing a cross-sectional structure in the vicinity of a protrusion of the modification.

FIG. 10 is a plan view showing a top structure of a cylinder block of the modification.

[Description of Signs] 10: cylinder block, 10a: upper surface, 11: cylinder head, 12: head bolt, 13: cylinder bore,
14 ... bolt hole, 15 ... projection, 16 ... through hole, 17 ...
Micro seal, 18: Projection, 19: Maze chamber, 20: Annular groove, 21: Projection.

Claims (4)

[Claims] An engine sealing structure for sealing between a cylinder block of an engine and a cylinder head fastened to a top surface thereof by a fastening member, wherein at least one of the cylinder block and the cylinder head has a projection on a contact surface thereof. An engine seal for sealing between the cylinder head and the cylinder block based on elastic deformation of at least one of the cylinder head and the cylinder block using the protrusion by the fastening force of the fastening member. Construction. 2. The projection portion is provided so as to surround an outer edge of a cylinder bore of the cylinder block.
The distance between the cylinder bore and the outer periphery of the projection and at least one of the height of the projection are formed so as to change along the outer periphery of the cylinder bore.
The seal structure for an engine according to the item. 3. The displacement of the lower surface of the cylinder head associated with the operation of the engine according to the material of the cylinder head, the fastening position or the fastening force of the fastening member, or the displacement of the engine. 2. The engine sealing structure according to claim 1, wherein the height or the distance from the cylinder bore of the cylinder block is set so as to be able to perform the operation. 4. The seal structure for an engine according to claim 1, wherein at least a portion between a contact surface between the cylinder block and the cylinder head is filled with a sealant. An engine seal structure characterized by the following.