JPH11200941A - Engine structure - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide an engine structure that improves sealing performance between a cylinder head and a cylinder block. SOLUTION: A cylinder block 1 is provided with a bolt hole 10 penetrating from a bearing cap 8 side to a cylinder head 9 side, and the cylinder block 1 is provided along the bolt hole 10.
A reinforcing member 11 having higher strength was provided, a through bolt 12 was inserted into a bolt hole 10, and the cylinder head 9 and the bearing cap 8 were fastened together with the bolt 12 sandwiching the cylinder block 1. Since the cylinder block 1 is sandwiched between the cylinder head 9 and the bearing cap 8 by the through bolts 12, the cylinder block 1
Is pressed against the cylinder head 9 as a whole, and the sealing surface pressure of the cylinder head 1 is substantially uniform irrespective of the location, and the sealing performance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As shown in FIG.
Is constructed by fastening a cylinder head c to a cylinder block b with a head bolt d. The head bolt d is
The sealing surfaces of the cylinder head c and the cylinder block b are brought into close contact with each other via a gasket (not shown), and the sealing performance therebetween is ensured against the combustion pressure in the cylinder bore. The head bolt d is, as shown in FIG.
The cylinders are arranged around the cylinder bores e at predetermined intervals in the crankshaft direction.

[0003]

In recent years, the cylinder block b has been changed from cast iron to aluminum in order to reduce the weight of the engine. However, aluminum has lower strength than iron.

Therefore, in the engine having the structure shown in FIGS. 4 and 5, the axial force of the head bolt d is concentrated near the threaded portion f of each bolt, and only the threaded portion f of the cylinder block b is directed upward. Will be raised. As a result, the surface pressure of the x-marked portion g in the middle of each head bolt d of the cylinder block b decreases, and the sealing performance deteriorates. Such a problem is remarkable in a diesel engine having a high combustion pressure, particularly a diesel engine with a supercharger.

[0005] As a countermeasure, it is conceivable to increase the tightening torque of the head bolt d in order to secure the surface pressure of the above-mentioned mark x. However, even if the tightening torque of the head bolt d is carelessly increased, the seat pressure of the bolt d only buckles beyond the allowable surface pressure of the material (aluminum).
Further, the vicinity of the threaded portion f of the cylinder block b (made of aluminum) is locally deformed, and the inner diameter of the cylinder bore e deviates from the designed size.

SUMMARY OF THE INVENTION An object of the present invention, which has been made in view of the above circumstances, is to provide an engine structure in which a sealing property between a cylinder head and a cylinder block is improved.

[0007]

In order to achieve the above object, an engine structure according to the present invention is characterized in that a cylinder block is provided with a bolt hole penetrating from the bearing cap side to the cylinder head side, and the cylinder is provided along the bolt hole. A reinforcing member having a higher strength than the block is provided, a through bolt is inserted into the bolt hole, and the cylinder head and the bearing cap are fastened together with the bolt sandwiching the cylinder block.

According to the present invention, since the cylinder block is sandwiched between the cylinder head and the bearing cap by the through bolt, the sealing surface of the cylinder block is entirely pressed against the cylinder head, and the sealing surface of the cylinder head is pressed. The pressure is substantially uniform irrespective of the location, and the sealing performance is improved. In addition, since the reinforcing member is provided along the bolt hole of the through bolt, the axial force at the time of tightening the bolt is supported by the reinforcing member, so that the tightening torque of the bolt can be increased, and the sealing performance is improved. improves. Also,
Since the cylinder block is reinforced by the reinforcing member, deformation of the cylinder bore at the time of bolt tightening is suppressed.

The cylinder block has a bulkhead for partitioning each cylinder, and a cylindrical cylinder bore wall mounted so as to bridge over an adjacent bulkhead, and the bolt hole penetrates through the bulkhead. Alternatively, it may be formed from the bearing cap side to the cylinder head side. According to this configuration, the axial force of the through bolt inserted into the bolt hole acts to press the cylinder bore wall toward the cylinder head via the bulkhead, so that the upper end of the cylinder bore wall is pressed uniformly against the cylinder head. And the sealing property is improved.

[0010] The through bolt may be inserted from the bearing cap side, penetrate a bolt hole of the cylinder block, and screwed into the cylinder head. According to this configuration, the space occupied by the through bolts in the cylinder head is reduced, so that the degree of freedom in designing the intake and exhaust ports and the like formed in the cylinder head is increased.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view of a cylinder block which is a main part of an aluminum alloy engine according to the present embodiment, and FIG. 2 is a sectional view of the engine (corresponding to a sectional view taken along line II-II of FIG. 1). FIG. 3 is a bottom view of the cylinder block of FIG.

As shown in FIG. 1, the cylinder block 1 includes a substantially rectangular parallelepiped block body 2 and a skirt 3 integrally formed below the block body 2. Inside the block main body 2, cylindrical cylinder bore walls 5 that define the respective cylinder bores 4 are provided at predetermined intervals in the crankshaft direction, and inside the skirt 3, there are bulk The heads 6 are provided at predetermined intervals in the crankshaft direction.

More specifically, as shown in FIG. 3, each of the cylinder bore walls 5 is mounted on the adjacent bulkheads 6, 6 so as to bridge the bulkheads 6, 6, respectively. Around each cylinder bore wall 5, a water jacket (not shown), an oil drop hole, and the like are provided. At the lower end of each bulkhead 6, a bearing 7 for a crankshaft is provided. These bulkheads 6 include:
As shown in FIG. 2, bearing caps 8 are respectively mounted.

As shown in FIG. 2, the cylinder block 1 is provided with a bolt hole 10 penetrating from the bearing cap 8 side to the cylinder head 9 side through the bulkhead 6. Four bolt holes 10 are provided for each cylinder so as to surround the periphery of each cylinder bore 4.
They are arranged at predetermined intervals in the crankshaft direction. Each bolt hole 10 is a normal hole having no thread on the inner peripheral surface.

Around the bolt holes 10, reinforcing members 11 having a higher strength than the material (aluminum alloy) of the cylinder block 1 are provided.
Are provided along the axial direction of the bolt hole 10. In this embodiment, the reinforcing member 11 is made of fiber reinforced metal (FRM) using aluminum oxide as a whisker and an aluminum alloy as a matrix, and is formed in a pipe shape so as to substantially form the inner peripheral surface of the bolt hole 10. Have been. The reinforcing member 11 is integrally cast when the cylinder block 1 made of an aluminum alloy is cast.

The material of the reinforcing member 11 is not limited to the above-mentioned fiber reinforced metal (FRM), but any material having a strength higher than that of the base material (aluminum alloy) of the cylinder block 1 is sufficient.
For example, iron or stainless steel can be used. Further, the type of the whisker may be aluminum titanate or aluminum borate. Further, the method of attaching the reinforcing member 11 to the cylinder block 1 is not limited to the casting described above. For example, the reinforcing member 11 formed in a pipe may be press-fitted into the bolt hole 10.

As shown in FIG. 2, the cylinder block 1 has a gasket formed on the upper portion thereof (not shown).
An aluminum cylinder head 9 is arranged, and a bearing cap 8 is arranged at a lower part. These cylinder heads 9
The bearing cap 8 and the bearing cap 8 are fastened together with the through hole 12 inserted into the bolt hole 10 so as to sandwich the cylinder block 1. Above through bolt 12
Is inserted from the bearing cap 8 side, passes through the bolt hole 10 of the cylinder block 1, and is screwed into the cylinder head 9.

More specifically, the through bolt 12 is
a, a shaft portion 12b, and a screw portion 12c.
Is seated on the lower surface of the bearing cap 8, the shaft portion 12b is received in the bolt hole 10 of the cylinder block 1, and the screw portion 12c is screwed into a screw hole 13 formed in the cylinder head 9. That is, the screw hole 1 is provided in the cylinder head 9 at a position corresponding to the bolt hole 10 shown in FIGS.
3 is formed, and the bearing cap 8 is similarly formed with an insertion hole 14, and the through bolt 12 serves as both a cylinder head bolt and a bearing cap bolt.

The bearing cap 8 is also attached to the cylinder block 1 by an auxiliary bolt 15. The auxiliary bolt 15 prevents the bearing cap 8 from falling off when the bearing cap 8 is temporarily assembled with the crankshaft sandwiched between the cylinder block 1 and the cylinder block 1. The auxiliary bolt 15 passes through the insertion hole 16 of the bearing cap 8 and is screwed into the screw hole 17 of the bulkhead 6.

The operation of this embodiment having the above configuration will be described.

According to the above-described engine structure, as shown in FIG. 2, the cylinder block 1 is sandwiched between the cylinder head 9 and the bearing cap 8 by the through bolt 12, so that the head 12a of the through bolt 12 The acting upward bolt axial force is transmitted to the cylinder block 1 via the bearing cap 8, and the cylinder block 1
Is pressed substantially uniformly on the cylinder head 9 side. Therefore, the sealing performance between the cylinder head 9 and the cylinder block 1 is improved. At this time, cylinder bore 4
Most of the combustion pressure generated in the inside is taken over by the through bolt 12.

Further, since the reinforcing member 11 is provided along the bolt hole 10 of the through bolt 12, the axial force at the time of tightening the through bolt 12 is supported by the reinforcing member 11, and the tightening of the through bolt 12 is performed. The applied torque can be increased. That is, by providing the reinforcing member 11 along the bolt hole 10 of the through bolt 12, the through bolt 12
Since the boss portion strength and the bearing surface pressure strength are increased, the tightening torque of the through bolt 12 can be increased. Therefore,
The adhesion between the cylinder head 9 and the cylinder block 1 is increased, and the sealing property therebetween is improved.

Further, as shown in FIG. 1, the cylinder bore wall 5 is placed so as to bridge the adjacent bulkheads 6, 6, so that the through bolts 12 inserted into the bolt holes 10 are provided.
The upward bolt axial force acting on the head 12a of the cylinder head is transmitted to the cylinder bore wall 5 via the bulkheads 6, 6, and acts to press the cylinder bore wall 5 against the cylinder head 9. As a result, the upper end of the cylinder bore wall 5 is evenly pressed against the cylinder head 9 and the sealing performance is improved. Therefore, a sufficient surface pressure is applied also to the x-marked portion g in FIG. 5, and gas blow-through from the x-marked portion g where the surface pressure tends to decrease is prevented.

Further, since the strength of the cylinder block 1 itself is reinforced by the reinforcing member 11, the deformation of the cylinder bore 4 when the through bolt 12 is tightened is suppressed. In this embodiment, the reinforcing member 11 is made of a fiber-reinforced metal (F
RM) is used, but the FRM has a smaller thermal expansion than the aluminum alloy that is the base material of the cylinder block 1. For this reason, the aluminum cylinder block 1 which tends to expand at high temperatures is suppressed by the FRM, and the through bolt 1
2 can be reduced in tensile stress.

As described above, since the tensile stress of the through bolt 12 due to the thermal expansion of the cylinder block 1 at high temperatures is reduced, the initial tightening force of the through bolt 12 can be set with a margin. Further, in the present embodiment, the matrix of the FRM as the reinforcing member 11 is made of the same metal as the aluminum alloy as the base material of the cylinder block 1, so that the interface peeling phenomenon that easily occurs between different metals can be avoided.

Since the through bolt 12 is inserted from the bearing cap 8 side, penetrates through the bolt hole 10 of the cylinder block 1 and is screwed into the cylinder head 9, the through bolt 1 in the cylinder head 9 is provided.
2 occupies less space, and intake and exhaust ports, camshafts and the like (not shown) formed in the cylinder head 9.
The degree of freedom in layout design is increased.

A through hole is formed in the cylinder head 9 without providing the screw hole 13, and the through bolt 12 is passed through the cylinder head 9 so that the screw portion 1 is removed from the cylinder head 9.
A structure in which 2c is protruded, and a nut is screwed into 12c of the screw portion to fasten the nut.

Further, the through bolt 12 is inserted from the cylinder head side 9 and the bolt hole 10 of the cylinder block 1 is inserted.
And may be screwed into the bearing cap 8 or through the bearing cap 8 so that the nut is screwed and tightened.

The present invention can be applied not only to the in-line three-cylinder engine as shown in the figure but also to an engine having four or more cylinders, a V-type engine, etc., and also to a supercharged engine and a non-supercharged engine. it can. The material of the cylinder block is not limited to aluminum but may be iron.

[0031]

As described above, according to the engine structure of the present invention, the sealing performance between the cylinder head and the cylinder block can be improved. Therefore, it is suitable for an engine structure having a high combustion pressure, such as a diesel engine with a supercharger.

[Brief description of the drawings]

FIG. 1 is a perspective view of a cylinder block which is a main component of an engine according to an embodiment of the present invention.

FIG. 2 is a sectional view of the engine (corresponding to a sectional view taken along line II-II of FIG. 1).

FIG. 3 is a bottom view of the cylinder block shown in FIG.

FIG. 4 is an explanatory view showing a conventional engine structure.

FIG. 5 is a plan view showing a top surface of a cylinder block of the engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 5 Cylinder bore wall 6 Bulkhead 8 Bearing cap 9 Cylinder head 10 Bolt hole 11 Reinforcement member 12 Through bolt

Claims (3)

[Claims] 1. A bolt hole penetrating from a bearing cap side to a cylinder head side is provided in a cylinder block, a reinforcing member higher in strength than the cylinder block is provided along the bolt hole, and a through bolt is inserted into the bolt hole. An engine structure wherein the cylinder head and the bearing cap are fastened together with the bolts sandwiching the cylinder block. 2. The cylinder block has a bulkhead for partitioning each cylinder, and a cylindrical cylinder bore wall mounted so as to bridge over an adjacent bulkhead, and the bolt hole is formed in the bulkhead. 2. The bearing cap is formed from the bearing cap side to the cylinder head side.
Engine structure as described. 3. The engine structure according to claim 1, wherein said through bolt is inserted from a bearing cap side, penetrates a bolt hole of a cylinder block, and is screwed into a cylinder head.