JPH071026B2 - Engine block structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention divides an engine block structure, in particular, an engine body into a block forming a head portion and a cylinder portion, and a block forming a skirt portion, and The present invention relates to an engine block structure in which both blocks are bolted together.

(Prior Art) In an engine for an automobile or the like, a head portion having an intake / exhaust port is formed in a cylinder head, and a cylinder portion having a cylinder bore and a skirt portion forming a crank chamber are integrally formed in a cylinder block. Is customary. However, according to such an engine structure, a plurality of head bolts must be arranged across the cylinder block from the upper part of the cylinder head while avoiding interference with the intake and exhaust ports and intake and exhaust valves. Therefore, the layout of the intake / exhaust system is restricted by the bolts and the degree of freedom thereof is significantly reduced, and the mating surfaces of the cylinder head and the cylinder block are deformed by the influence of high temperature and high pressure combustion gas. In particular, in a high-power and high-speed engine, the sealing property of the mating surface against the combustion gas is significantly deteriorated.

To deal with such a problem, for example, Japanese Patent Laid-Open No.
As shown in JP-A-34938, by integrally forming a portion extending from the head portion to the cylinder portion as one block, the head bolt is abolished and this block is provided at a portion corresponding to the combustion chamber. A block structure of an engine has been proposed in which the mating surface between the block and other blocks is not located, thereby increasing the degree of freedom in the layout of the intake / exhaust system and improving the sealing performance against combustion gas. . When this type of block structure is adopted, the machining work is performed to ensure the roundness of the cylinder bore or liner formed in the cylinder portion, or when the head portion is machined from the cylinder portion side, that is, the engine bottom side. For the sake of simplification or simplification, the head portion and the cylinder portion are integrally formed into one block and the skirt portion is formed into another block, and then these two blocks are used with bolts or the like. It is conceivable or attempted to conclude.

(Problems to be Solved by the Invention) By the way, as described above, the engine body is divided into a block forming the head portion and the cylinder portion, and a block forming the skirt portion, and the both blocks are bolted together. The block structure as described above has the advantages that the roundness of the cylinder bore can be secured and the machining of the head portion can be facilitated as described above, but has the following drawbacks.

That is, in the cylinder portion of the one block, the piston slidingly contacting the inner surface of the cylinder bore reciprocates, and in the skirt portion of the other block, the crankshaft pivotally supported by the bearing reciprocates the piston. However, in this case, an extremely large load is intermittently applied to the crankshaft via the connecting rod due to the explosive load of the combustion gas from the piston. Along with this, stress is repeatedly applied to the mating surfaces of the one block and the other block, and the cylinder part becomes hotter than the skirt part, so that a difference in thermal expansion occurs between the two blocks. Further, in a multi-cylinder engine, the phases of the reciprocating motions of the pistons are different from each other, so that bending stress or shearing force acts on the mating surfaces.
Therefore, it is necessary to secure sufficient coupling rigidity or mounting rigidity on the mating surfaces of both the blocks, but nevertheless, for example, the flange portions having the mating surfaces formed in a flat shape are brought into contact with each other. In the case where the two blocks are joined together by fastening them with a bolt or the like, rattling or deviation occurs between the two blocks, and as a result, the relative position between the piston and the crankshaft is displaced, The compression ratio varies from cylinder to cylinder or from engine to engine, and the connection state of the mission case mounted across both blocks at the rear end of the engine body becomes unstable. This causes various harmful effects such as vibration noise. Then, in order to prevent or suppress the occurrence of such adverse effects, not only the mounting rigidity of the mating surface but also the positioning or positioning accuracy of both blocks are important, but a simple and effective concrete means for these is found. The reality is that it is not.

(Means for Solving Problems) The present invention relates to a block structure of an engine, and more particularly to a block structure in which both a block forming a head portion and a cylinder portion and a block forming a skirt portion are bolted together. By effectively improving the mounting rigidity and the positioning accuracy of the two blocks by using a simple means or structure, the load and heat acting on the mating surfaces of the two blocks can be dealt with. An object of the present invention is to provide a block structure of an engine that is well positioned by suppressing deformation in the vicinity of the mating surfaces and further rattling and deviation occurring between the blocks. In order to achieve this object, the present invention is characterized by having the following configuration.

That is, the engine body including the head portion, the cylinder portion, and the skirt portion is divided into a block forming the head portion and the cylinder portion and a block forming the skirt portion,
Further, in the block structure of the engine in which both the blocks are fastened by bolts, the positioning means in the front-rear direction (engine longitudinal direction) of the both blocks is provided at the transmission side end parts (engine rear part) of the both blocks,
A stepped portion is provided at a predetermined position on the mating surface of the both blocks, and the side surfaces of the stepped portion that come into contact with each other are positioning portions in the left-right direction (engine width direction) of the both blocks. And

(Operation) According to the above configuration, the head portion having the intake / exhaust ports and the like and the cylinder portion having the cylinder bore or the cylinder liner are integrally formed in one block, and this block and the other block are Since it is divided between the cylinder part and the skirt part, the conventional head bolt can be eliminated and the flexibility of the layout of the intake and exhaust system can be increased, and the workability of the head part from the engine bottom side can be improved. It is possible to maintain the roundness of the cylinder bore with high precision while improving the roundness.

In particular, according to the present invention, the positioning of both blocks in the front-rear direction is performed by the positioning means such as a knock pin driven across both blocks at the mission side end, so that both of them can be operated during the operation of the engine. Even if a relatively large difference in thermal expansion occurs in the front-rear direction, that is, in the longitudinal direction of the engine due to the temperature difference between the blocks, the blocks on both sides of the mission are firmly positioned at the mission-side ends of both blocks. The relative positions do not deviate, so that the coupled state of the mission cases mounted over the end faces of both blocks is always good and reliable. Further, since the positioning in the front-rear direction is performed only on the mission side end portion in this way, and only the end portion is constrained,
It is also possible to obtain an effect that deformation, vibration and the like due to the difference in thermal expansion between the two blocks are appropriately absorbed or suppressed.

Further, a stepped portion is formed on the mating surfaces of the two blocks, and both blocks are bolted together while the corresponding stepped portions are engaged. Compared with the case where bolts are fastened in a state in which the formed mating surfaces are in contact with each other, the mounting rigidity of the mating surfaces is increased, and both of them are generated due to the load or heat acting on the mating surfaces. Rattling and displacement of the block, and further vibration and the like are effectively suppressed. In addition, since the side surfaces of the stepped portion formed on the mating surface that abut each other are positioned in the left-right direction, that is, the engine width direction, a large bending stress due to the interlocking motion of the piston and the crankshaft on the mating surface or Even if a shearing force is applied, the displacement of both blocks due to the bending stress is prevented by the abutment of the both side surfaces, thereby ensuring the positioning of both the blocks and possible variations in the compression ratio, etc. Will be suppressed.

(Example) Hereinafter, the Example of this invention is described based on drawing.

In this embodiment, the present invention is applied to an in-line 4-cylinder 4-valve engine.

First, a schematic structure of an engine according to the present invention will be described with reference to FIG. 1. The main body of the engine 1 includes a first block 2 on which a head cover (not shown) is attached, and an oil pan 3 on the lower side. The first block 2 is provided with a head portion 5 and a cylinder portion 6, and the second block 4 is provided with a skirt portion 7. The two blocks 2 and 4 are fastened with bolts 8 ... 8.
The head portion 5 of the first block 2 is formed so as to correspond to the intake port 10 and the exhaust port 11 respectively opened on the ceiling surface of the combustion chamber 9 and these ports 10 and 11. The stem fitting holes 12 and 13 of the intake and exhaust valves, the bearing holes (lower half) 14 and 15 of the cam shaft for opening and closing the intake and exhaust valves, and the valve and cam shaft The tappet fitting holes 16 and 17 are provided, and the cylinder portion 6 of the first block 2 is provided with a cylinder bore 18 for fitting and holding a piston.
On the other hand, in the second block 4 (skirt portion 7), partition walls 19 located below between adjacent bores, and bearing caps formed on these walls 19 and attached below the walls 19, respectively.
A bearing hole (upper half portion) 21 for fitting and holding the journal portion of the crankshaft is provided between the crankshaft 22 and the crankshaft 22, and the second block 4 and the oil pan 3 constitute a crank chamber 22. An inter-skirt plate 23 is attached to the lower end of the block 4 to prevent the end portion from being deformed when the engine is operating.

A squish generation surface 9'for generating a squish of the air-fuel mixture is formed in the combustion chamber 9 at the peripheral portion of the combustion chamber 9 formed in the first block 2. The surface 9'is also used as a reference surface when processing the bearing hole 21 of the crankshaft. Further, a recess is formed in the lower end portion of the cylinder bore 18 in the first block 2.
18 '... 18' is formed, but this recess 18 '... 1
Reference numeral 8'is provided to avoid interference between the tool and the end portion when the valve stem fitting holes 12 and 13 in the head portion 5 of the block 2 are processed.

Next, FIG. 2 (first block 2) shows the connection state and the positioning means of the first and second blocks 2 and 4 which are the features of the present invention.
Will be described with reference to FIGS. 3 and 4 (single unit plan view of the second block 4).

First, in the first block 2 shown in FIG. 2, the peripheral wall portions 24..24 of the cylinder bores 18..18 at the bottom thereof are formed so as to project downward with respect to the lower end surface 25 of the block 2. The projected peripheral wall portions 24 ... 24 are connected between adjacent bores via connecting portions 24 '... 24'. Also,
The lower end surface 25 has both ends thereof and the connecting portions 24 '... 24'.
Screw holes 26..26 into which the tips of the bolts 8..8 are screwed are formed on both sides of the above, and a seal is provided so as to surround these screw holes 26..26 and the peripheral wall portions 24..24. A member mounting groove 27 is provided.

On the other hand, the second block 4 shown in FIG. 3 has the boss portion 30 of the bolt insertion hole 29 in the upper wall portion 28, the upper end surface 31 of the wall portion 28 is formed in a flat shape, and each bore is formed. The upper part of the partition 19 ... 19 provided at the position corresponding to the space is the thin part 32 ...
32, and the thin block 32 has the first block 2
24 'are formed corresponding to the connecting portions 24' ... 24 '(see FIG. 1). Then, on the upper part of the second block 4, the partition walls 19 ... 19 and the front and rear end walls 34, 35 are formed.
Each hole 36 that is partitioned by and leads to the crank chamber 22.
... 36 is provided.

However, each bore peripheral wall portion 24 in the first block 2 ...
First side surfaces 37 ... 37 are formed on both outer side portions of 24, respectively, and both side edges 38 ... 38 of the lower end surface of the block 2 are formed.
And a space between each of these first side surfaces 37 ... 37 is set to a predetermined width, and an upper end surface 31 of the second block 4 is formed.
Second side surfaces 39 ... 39 are formed on both inner side portions of the second block 4 so as to correspond to the respective first side surfaces 37 ... 37, and both side edges 40 ... 40 of the upper end surface 31 of the second block 4 are formed. And these second
A predetermined width is set between each of the side surfaces 39 ... 39. Then, the bore peripheral wall portions 24 ... 24 of the first block 2 are fitted into the holes 36 ..
By inserting the bolts 8 ... 8 into the bolt insertion holes 29 ... 29 and screwing them into the screw holes 26. The both blocks 2 and 4 are bolted together.
In that case, each of the first side surfaces 37 of the first block 2 ...
And the respective second side surfaces 39 of the second block corresponding to these ...
39 will be in close contact with each other, so both blocks 2,
Positioning in the left-right direction of 4, that is, the engine width direction is performed.

Further, on the lower end surface 25 of the first block 2, a first pin hole 41 is opened at a corner portion of a mission side end portion, that is, an engine rear end portion (left end in the drawing), and the second block 4
Also on the upper end face 31 of the second pin at a position corresponding to the first pin hole 41
The pin hole 42 is opened. Then, the knock pin 43 is driven across the first and second pin holes 41, 42 (see FIG. 1) so that both blocks 2, 4 are positioned in the front-rear direction, that is, in the engine longitudinal direction. Has become. Further, mission flanges 44 and 45 are formed at the rear ends of the first and second blocks 2 and 4, respectively, and a mission case 46 shown by a chain line in FIG. It is configured to be attached.

According to the above configuration, the head portion 5 having the intake / exhaust ports 10, 11 and the like and the cylinder portion 6 having the cylinder bore 18 are integrally formed in the first block 2. It is possible to increase the degree of freedom in the layout of the intake / exhaust system by abolishing it, and to improve the sealing performance around the combustion chamber 9. Further, since the first block 2 and the second block 4 are just divided between the cylinder portion 6 and the skirt portion 7, the roundness of the cylinder bore 18 is maintained with high precision, and the first and second blocks are Processing work from below on the head portion 5 when the two blocks 2 and 4 are divided is facilitated or simplified in combination with the provision of the recesses 18 '... 18' in the lower end portion of the bore 18. Will be.

The machining of the crankshaft bearing hole 21 shown in FIG.
Assemble the first and second blocks 2 and 4 in the state shown in the figure,
In addition, since the dimension from the squish generating surface 9'in the peripheral portion of the combustion chamber 9 to the center of the bearing hole 21 is set to a predetermined value, the variation of the compression ratio among the cylinders can be prevented. become.

However, in this engine 1, the first and second blocks
The combination of 2, 4 brings the lower end surface 25 of the first block 2 and the upper end surface 31 of the second block 4 into close contact with each other, and the respective bore peripheral wall portions 24 projecting downward with respect to the lower end surface 25 of the first block 2. The first side surfaces 37 ... 37 formed on the first and second side surfaces 24 and 24 are closely contacted with the second side surfaces 39 ... 39 formed on the inner side of the upper wall portion 28 of the second block 4 correspondingly. In the state, bolt 8
Since it is configured to be fastened by using 8 ..., compared with, for example, the case where the end surfaces of both blocks formed in a flat shape are brought into close contact with each other and the bolts are fastened, the connecting rigidity or the mounting rigidity is improved. It will be enhanced effectively.
As a result, it is possible to avoid a situation in which rattling or deviation between the blocks 2 and 4 and further vibration or the like occur between the blocks 2 and 4 due to the load or heat acting on the joint between the blocks 2 and 4. In addition, each first side surface 37 of the first block 2
...... 37 and the second side surfaces 39 of the second block 4 are brought into close contact with each other to position the two blocks 2 and 4 in the left-right direction. Even if a large bending stress or shearing force is applied due to the coordinated movement of the above, the above-mentioned first and second side surfaces 37 ... 3
The contact of the blocks 39, 39 ... 39 prevents the displacement of the blocks 2, 4 in the left-right direction due to the bending stress, thereby improving the positioning accuracy between the blocks 2, 4.

Furthermore, by striking the knock pin 43 across the first and second both pin holes 41 and 42 formed at the transmission side end portion in the coupling portion of the above first and second blocks 2 and 4, both blocks are driven.
Since the positioning of the engine 2 and 4 in the front-rear direction is performed, the temperature difference between the blocks 2 and 4 when the engine 1 is operating (the temperature of the first block 2 is higher than that of the second block 4) Even if a relatively large difference in thermal expansion occurs due to
Since the transmission side end portions of the two blocks 2 and 4 are firmly positioned, the relative positions of the mission flanges 44 and 45 formed on the two blocks 2 and 4, respectively, are not displaced, and accordingly, The connection of the mission case 46 to both blocks 2 and 4 is always maintained in a stable state. Further, the positioning of the blocks 2 and 4 in the front-rear direction in this way is performed only at the mission side end, and only the end is constrained, so that both blocks 2 and 4 are restrained. It is also possible to obtain an effect that deformation, vibration and the like due to the difference in thermal expansion are appropriately absorbed.

In this embodiment, the oil passage of the lubricating device has a passage structure as shown below in order to favorably perform the lubricating action on each lubricating portion of the engine 1.

That is, as shown in FIGS. 4 and 5, an oil discharge passage 50 for discharging the lubricating oil in the oil pan 3 by the oil pump P is formed at one side of the first block 2 (skirt portion 7). On the side portion of the second block 4 (cylinder portion 6), an oil cooling passage 52 is formed in parallel with the water jacket 51 (see FIG. 1), and the oil discharge passage is formed. Since 50 communicates with the oil inlet 55 provided in the oil filter mounting portion 54 through the first communication passage 53 and the oil cooling passage 52 communicates with the oil outlet 56 provided in the mounting portion 54. , Above both passages 5
0 and 52 are configured to communicate with each other via an oil filter. Further, the end portion of the oil cooling passage 52 on the oil filter side is provided with the tappet fitting holes 16 and 17 and the camshaft bearing holes 14 and 15 via the second communication passage 57 which is disposed in the vicinity of the water jacket 51. To the oil gallery 58 communicating with the main gallery 60 formed in the second block 4 via the third communication passage 59 at the downstream end of the cooling passage 52. The gallery 60 communicates with the bearing hole 21 of the crankshaft through each branch passage 61.

With the oil passage thus configured, when the lubricating oil discharged from the oil pump P to the oil discharge passage 50 of the second block 4 passes through the oil cooling passage 52 of the first block 2. In water jacket 51
After being brought to a low temperature state by the cooling water therein, it again flows into the second block 4 and is pressure-fed to the main gallery 60, and further from the gallery 60 via the branch passages 61 ... 61 to the crankshaft bearing hole 21. ... supplied to 21. As a result, the lubricating action and cooling action on the bearing holes 21 ... 21 or the crank journal portion are favorably performed, and the early deterioration of the lubricating oil due to the temperature rise is effectively suppressed. still,
Oil gallery 58 leading to the tappet fitting holes 16 and 17, etc.
To the water jacket 51, the lubricating oil is supplied through the second communication passage 57 disposed in the vicinity of the water jacket 51, so that the lubrication and cooling action on the valve operating mechanism can be favorably performed.

Further, in this embodiment, the cooling water passage (water jacket) of the cooling device provided in the engine 1 is configured as described below, so that the cooling action for the engine 1 is favorably performed. Is taken into consideration.

That is, as shown in FIG. 6, the water jacket of the engine 1 is formed on the cylinder portion 6 of the first block 2 and is formed on the side portion thereof so as to surround the cylinder bore 18. (See FIG. 1), and a head portion side jacket 51 ′ formed on the head portion 5 of the first block 2 and having its upper portion covered with the upper deck 70.
And both jackets 51, 51 'are partitioned by lower decks 71 ... 71 provided above the combustion chamber upper wall 9a and between the intake and exhaust ports 10 and 11 between the respective port walls. ing. Further, communication holes 72 ... 72 for communicating the jackets 51, 51 'are formed between the bores of the lower deck 71.
The discharge port 74 of 73 (see FIG. 1) is the above jackets 51, 5
It is connected to the cylinder part side jacket 51 of 1 '. With such a cooling water passage structure, the water pump 73 is connected to the cylinder side jacket 51.
The cooling water discharged to the lower deck 71 remains at low temperature.
The peripheral portion of the combustion chamber upper wall 9a immediately below 71 is immediately reached, so that the combustion chamber 9 is satisfactorily cooled, and the communication holes 72 are provided in the inter-bore portions where the cooling water flow easily stagnates. A proper amount of cooling water is introduced from the cylinder portion side jacket 51 to the head portion side jacket 51 'via 72, so that a smooth cooling water flow occurs between the bores. As a result, the temperature of the combustion chamber 9 is suitably lowered, the knocking resistance and the heat resistance load of the engine 1 are improved, and the cooling performance for the inter-bore portions is improved,
Furthermore, variations in the cooling action for each cylinder can be prevented.

As described above, according to the present invention, in the block structure of the engine in which the engine body is divided into the block forming the head portion and the cylinder portion and the block forming the skirt portion, Since the stepped portions are formed on the mating surfaces and the bolts are fastened with the corresponding stepped portions engaged, the mounting rigidity of both blocks is effectively increased, and rattling between them occurs. The gap will be suppressed as much as possible. Also, since both blocks are positioned in the left-right direction by the side surfaces of the stepped portion formed on the mating surface that abut each other, the bending stress acting on the mating surface causes the blocks to move relative to each other in the lateral direction. A situation such as a deviation is avoided, and the positioning of both blocks is ensured. Further, since the means for positioning the both blocks in the front-rear direction is provided only at the end portion on the mission side, the heat in the front-rear direction of both blocks is maintained while maintaining the stability of the coupling state between the both blocks and the mission case. It is possible to effectively absorb or suppress deformation, vibration, etc. due to the difference in expansion.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a vertical sectional front view of an engine according to the present invention, FIG. 2 is a bottom view of a block constituting a head portion and a cylinder portion, and FIG. 3 is a skirt portion. FIG. 4 is a plan view of a block constituting the skirt portion, FIG. 4 is a longitudinal sectional front view of the block constituting the skirt, and FIG. 5 is an engine showing the constitution of the oil passage extending over both the blocks. Side view of
FIG. 6 is a vertical cross-sectional front view of the block that constitutes the head portion and the cylinder portion, showing the configuration of the cooling water passage. 1 ... Engine, 2 ... Block (first block) forming head and cylinder, 4 ... Block (second block) forming skirt, 5 ... Head, 6
...... Cylinder part, 7 ...... Skirt part, 8 ...... Bolt, 24
...... Stepped part (peripheral wall part), 25,31 …… Mating surface (lower end surface of the first block, upper end surface of the second block), 37,39 …… Side surfaces of both blocks (first side surface, Second side),
41, 42, 43 ... Positioning means in the front-rear direction (first pin hole, second pin hole, knock pin).

Claims (1)

[Claims] 1. An engine body comprising a head portion, a cylinder portion and a skirt portion is divided into a block constituting the head portion and the cylinder portion and a block constituting the skirt portion, and these two blocks are bolted. A block structure of an engine to be fastened, wherein front and rear positioning means for both blocks are provided at end portions of both blocks on a mission side, and stepped portions are provided at predetermined positions on mating surfaces of both blocks. A block structure of an engine, wherein side surfaces of the two blocks, which are provided in the stepped portion and abut against each other, are positioning portions in the left-right direction of the two blocks.