JPH05321760A - Engine cylinder block structure - Google Patents

Abstract

PURPOSE:To provide a constant transmission time of each cylinder vibration to be transmitted from a bearing cap to an engine mount and improve the riding comfort. CONSTITUTION:In a cylinder block structure of an engine 20 to be mounted through a mounting member 44, the cylinder block structure is provided with a cylinder block body 24, a plurality of bearing caps 28B-28E to support the crankshaft in a rotatable manner at a plurality of points along the longitudinal direction of the cylinder block body 24, and a plurality of side bolts to fix the respective bearing caps 28B-28E from the side of the cylinder block body 24. The smaller the tightening force of the side bolts becomes, as the farther the corresponding bearing cap is located from the mounting member 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine cylinder block structure mounted on a vehicle body via a mount member.

[0002]

2. Description of the Related Art Conventionally, when mounting an engine on a vehicle body, one or two places of an engine block are supported by an engine mount provided close to a vehicle compartment, and two parts near a mission connected to the engine are supported. In general, a structure in which a car is supported by a vehicle body via an engine mount is also used.

[0003]

However, in the above configuration, the engine is supported by the vehicle body at a position deviated with respect to the longitudinal direction thereof by the engine mount, so that the distance from each cylinder to the engine mount is different. It depends on the cylinder. Therefore, when the engine starts, vibration of the crankshaft due to explosive combustion in each cylinder is transmitted to the cylinder block via the bearing cap and further transmitted to the engine mount, the time required for the vibration to reach the engine mount by each cylinder is reached. It was different. Therefore, vibration due to the explosion of each cylinder temporally interferes with each other and an unpleasant vibration is increased and transmitted to the vehicle interior, or even if such interference does not occur, the rhythm of the vibration transmitted to the vehicle interior. There was a problem that the car became irregular and the riding comfort was deteriorated. Therefore, the present invention has been made in view of the above problems, and an object thereof is to make the transmission time of the vibration of each cylinder transmitted from the bearing cap to the engine mount constant and improve the riding comfort. It is to provide a cylinder block structure of an engine capable of performing.

[0004]

In order to solve the above-mentioned problems and to achieve the object, a cylinder block structure of an engine of the present invention has a crankshaft extending along a longitudinal direction, In the cylinder block structure of the engine, which is attached to the other side through the mount member,
A cylinder block main body having side wall portions extending in the vertical direction on both sides in the width direction, and a crankshaft that is disposed at a substantially central portion in the width direction below the cylinder block main body and rotates a crankshaft at a plurality of locations along the longitudinal direction. A plurality of bearing caps for fixing a bearing metal that supports freely to the cylinder block body, and a plurality of bearing caps for fixing each of the plurality of bearing caps to the side wall portion from the side of the cylinder block body. A plurality of side bolts are provided, and the fastening force of the side bolts for fixing the bearing cap is set to be smaller as the bearing cap is farther from the mount member.

In the cylinder block structure of the engine according to the present invention, the cylinder block has:
At least one auxiliary machine is arranged between the plurality of bearing caps and the mount member, and the closer the bearing cap is to the auxiliary machine, the smaller the fastening force of the side bolts for fixing the bearing caps is. There is.

Further, in the engine cylinder block structure according to the present invention, the bearing cap is formed with a female screw portion to be screwed into the side bolt, and the side wall portion has a through hole in a central portion thereof. It is characterized in that a plurality of bushes are fitted, the side bolts are screwed into the female screw portion through the bushes, and the bearing cap is fixed to the side wall portion. Further, in the cylinder block structure of the engine according to the present invention, the lower portion of the cylinder block is
The cylinder block main body is composed of a lower block divided from the upper part of the cylinder block main body with the vicinity of the central axis of the crankshaft as a vertical boundary, and the side wall portion is formed in the lower block.

[0007]

As described above, since the engine cylinder block structure according to the present invention is constructed, the bearing cap adjacent to each cylinder is changed by changing the fastening force of the side bolts for fastening the bearing cap to the lower block. Since it is possible to change the vibration transmission speed from, and the vibration transmission time from each bearing cap to the engine mount can be made constant, there is no interference of vibration due to the explosion of each cylinder, and it is a vibration with a constant interval. , The riding comfort can be improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an engine 2 to which a cylinder block structure of an engine of one embodiment is applied.
It is the figure which showed the cross section orthogonal to the crankshaft 22 of 0. In FIG. 1, the skirt portion 24a of the cylinder block body 24 is cut at a position slightly below the central axis of the crankshaft 22, and is of a so-called short skirt type. A crankshaft 22 as an output shaft of the engine 20 is arranged at a substantially central portion in the width direction (horizontal direction in the drawing) of the cylinder block main body 24 in a state of extending in a direction perpendicular to the paper surface. The upper side of the crankshaft 22 is slidably supported by a half-moon bearing metal attached to a bearing portion 26 of a cylinder block body 24, and the lower surface of the crankshaft 22 is attached to a bearing cap 28 in a half-moon bearing. Similarly, it is slidably supported by the metal 30. Therefore, the crankshaft 22
Is supported by a bearing metal 30 attached to a bearing portion 26 and a bearing cap 28, and is rotatable with respect to the cylinder block body 24. A fitting portion 24b for positioning the bearing cap 28 is formed at the center of the lower end portion of the cylinder block body 24 in the width direction, and both side portions 28a of the bearing cap 28 are fitted to the fitting portion 24b. By doing so, the bearing cap 28 is positioned in the width direction of the cylinder block body 24. Then, the bearing cap 28 is provided with two bolts 32 through through holes 28b formed on both sides in the width direction and penetrating in the vertical direction.
Is fixed to the cylinder block body 24 from below.

On the other hand, the lower blocks 34 are provided on the lower surfaces of the skirt portions 24a on both sides in the width direction of the cylinder block body 24.
The mounting surface 24c is formed horizontally, and the lower block 34 is fixed to the cylinder block body 24 with the upper end surface 34a abutting against the mounting surface. The lower block 34 is formed in a substantially rectangular parallelepiped shape that opens upward, and a plurality of through holes 34c penetrating in the vertical direction are formed in both side wall portions 34a and 34b along the longitudinal direction of the lower block 34. ing. The lower block 34 is fixed to the cylinder block body 24 by inserting a bolt 36 into the through hole 34c from below and screwing the bolt 36 into a female screw portion 24d formed on the cylinder block 24.

Here, in one embodiment, in order to improve the support rigidity of the bearing cap 28, the lower block 34 also has a structure for supporting the bearing cap 28. Specifically, a protrusion 34e for supporting the bearing cap 28 from below is formed at a position on the bottom plate 34d of the lower block 34 corresponding to the bearing cap 28. Through holes 34f extending vertically are formed on both sides of the protrusion 34e with the central axis of the crankshaft 22 interposed therebetween. Bolts 38 are inserted into the through-holes 34f, respectively, and the tips of the bolts 38 are screwed into the female screw portion 28c formed on the bearing cap 28 to form the lower surface of the bearing cap 28 and the lower block 34. The upper surface of the projected portion 34e is joined. The protrusion 34
On both sides of e, rib portions 34g as first reinforcing portions for further reinforcing the protruding portion 34e are formed,
The rib portion 34g is formed on both side wall portions 34 of the lower block 34.
It is connected to a and 34b. In addition, the lower block 34
On both side wall portions 34a, 34b of the crankshaft 22
Horizontally along the direction orthogonal to the extending direction of the through hole 34
h are formed respectively. A female screw is cut on the inner wall of the through hole 34h, and a bush 40 having a male screw portion to be screwed with the female screw formed on the outer periphery is attached to the through hole 34h. A through hole 40a is formed in the central portion of the bush 40. The side bolt 42 is inserted into the through hole 40a, and the tip portion of the bush 40 is attached to the bearing cap 28.
Both side surfaces of the bearing cap 28 and both side walls 34a, 34b of the lower block 34 are joined by being screwed into the female screw portion 28e formed on the boss portion 28d on the side surface of the lower block 34. Here, the bush 40 is made of a metal material having a low Young's modulus and a little elasticity so that the tightening force of the side bolt 42 can be changed.

In this way, the bearing cap 28
The lower end surface and both side surfaces thereof are strongly supported by the lower plate 34d of the lower block and the both side walls 34a and 34b, so that the crankshaft 22 is prevented from being twisted due to the tilting of the bearing cap 28. The engine 20 shown in the embodiment is an in-line four-cylinder engine, and the bearing caps 28 are arranged between the cylinders and at both ends of the four cylinders along the extending direction of the crankshaft 22. Therefore, five bearing caps 28 are arranged along the direction perpendicular to the paper surface. However, as will be described later in detail, the bearing cap 28 and the lower block 3
4 is the fastening state of these five bearing caps 28
All are not the same, but the fastening state is slightly different depending on each bearing cap. Therefore, in the following description, in order to distinguish the bearing caps from each other, the bearing caps are denoted by reference numerals 28A to 28E.

An oil pan 43 for supplying oil to the drive portion is attached to the lower surface of the lower block 34. The crankshaft 22 is assumed to rotate in the counterclockwise direction in FIG. Next, FIG. 2 is a partial cross-sectional view of the engine shown in FIG. 1 viewed from the arrow direction. The engine 20 shown in the embodiment is an in-line 4-cylinder engine as described above, and is arranged in a so-called vertical position with respect to the vehicle body 18 with the crankshaft 22 along the front-rear direction of the vehicle body 18. ing. The engine 20 is supported by a mount bracket 44 fixed to the vehicle body 18 on the upper side 24e of the cylinder block body 24 on the front side on the right side in the drawing. The left side of the figure, that is, the lower side of the mission case 45 of the mission connected to the rear side is supported by the vehicle body 18 by an engine mount (not shown). The cylinders arranged in the engine 20 are numbered as the first cylinder 46A, the second cylinder 46B, the third cylinder 46C, and the fourth cylinder 46D in order from the rear side of the engine 20. Further, as shown in the figure, the bearing caps arranged between the cylinders are arranged in the order of 28A from the rear side of the engine 20.
The symbols of 28E are attached.

These five bearing caps 28A
~ 28E and these bearing caps 28A-28
The crankshaft 22 is rotatably supported by a bearing portion 26 formed on the cylinder block body 24 corresponding to E. These five bearing caps 28A to 28E are, as already described in FIG. 1,
It is fixed to the lower block 34 from the side surface of the lower block 34 by side bolts 42 via bushes 40 mounted on both side walls 34a and 34b of the lower block 34, respectively.

On the other hand, at the rear end of the lower block 34, a mission case 45 which constitutes the outer shell of the mission.
A plate-shaped mounting portion 34i extending downward for fixing the to the lower block 34 is integrally formed. In addition, a mounting surface 24f for fixing the mission case 45 to the rear end of the cylinder block body 24 as well.
Are formed. Then, the transmission case 45 shown by the chain double-dashed line is fixed in a state of straddling the mounting surface 24f on the cylinder block body 24 side and the mounting portion 34i of the lower block 34 in the vertical direction. The transmission of the vibration of the engine 20 causes the mission case 45 to generate a divided vibration with respect to the main body side of the cylinder block 24, so that an uncomfortable vibration is easily generated. Therefore, in order to vibrate as much as possible with the cylinder block body 24, the attachment portion 34i of the mission case 45 of the lower block 34 has a substantially triangular reinforcing portion 34j as a second reinforcing portion as illustrated. Is provided. The substantially triangular reinforcing portions 34j are provided on both sides of the lower block 34 in the width direction (see FIG. 7). The connection point 3 between the base of the triangular reinforcing portion 34j and the lower block 34
As shown in the drawing, 4k is set at a position substantially right below the bearing cap 28B. As a result, the mission case 45 is firmly coupled to the entire engine block in which the cylinder block body 24 and the lower block 34 are combined.

As described above, the cylinder block body 24 of the engine 20 is provided with the first cylinder 46A to the fourth cylinder 46E in order from the rear side, and the bearing caps 28A to 28A are arranged between these cylinders. 28E are arranged respectively. And these bearing caps 28
A to 28E are fixed to the lower block 34, but as described above, these five bearing caps 2
Not all 8A to 28E are fixed to the lower block 34 in the same manner. The fastening state of the five bearing caps 28A to 28E and the lower block 34 will be described below with reference to FIGS. 2 and 3.

First, the bearing cap 28A disposed closest to the mission case 46 and the third
The bearing caps 28C and 28D arranged on both sides of the cylinder 46C and the bearing cap 28E arranged on the most front side are fixed to the lower block 34 in the state shown in FIG. 28A, 28C, 28D, 28E are reinforced so as to prevent the front-back tilt. On the other hand, the first cylinder 4
The bearing cap 28B located between the 6A and the second cylinder 46B is fixed to the protruding portion 34e ₂ protruding from the lower plate 34d of the lower block 34 as shown in FIG. 3, but this protruding portion 34e ₂ Unlike the other protruding portion 34e, does not have a rib portion 34g connected to both side walls 34a and 34b of the lower block 34.

The reason for this is as follows. In FIG. 2, as described above, the vibration of the engine 20 is transmitted to the mission case 46. However, when the mission case 46 and a heavy object that is a whole of the mission vibrate, the reaction force thereof is transmitted. It is transmitted to the triangular reinforcing portion 34j through the mounting portion 34i of, and is further transmitted from the reinforcing portion 34j to the connecting portion 34k between the reinforcing portion 34j and the lower block. Therefore, the reaction force of the force to vibrate the mission case 46 acts on the lower block 34 as a force to vibrate the connecting point 34k in the vertical direction. Therefore, the portion of the lower block 34 near the connection point 34k is displaced so as to bend in the vertical direction in the plane of the drawing. At this time, if the protruding portion 34e ₂ located directly above the connecting point 34k is connected to both side walls 34a and 34b of the lower block 34 by the rib portion 34g, the protruding portion 34e ₂ is reinforced by the rib portion 34g. It will be directly received the lifting force from 34j. Therefore, the bearing cap 28 </ _b > B receives the force of tilting in the front-back direction due to the front-back tilting of the protrusion 34 e ₂ . Therefore, due to the fall of the bearing cap 28B,
A twisting force acts on the crankshaft 22, which further excites the vibration of the crankshaft 22, which is not preferable. For this reason, the protrusion 34e ₂ is provided on both side walls 34a, 34 of the lower block 34.
It is not connected to b, and the pushing force from the reinforcing portion 34j is difficult to be transmitted.

Next, the detailed shape of the lower block 34 will be described with reference to FIGS. FIG. 4 is a plan view of the lower block of one embodiment as viewed from above. As described above, the position corresponding to the belling cap 28A closest to the mounting portion 34i of the mission case 46, the position corresponding to the bearing caps 28C and 28D on both sides of the third cylinder 46C, and the mounting portion 34 of the mission case 46.
A rib portion 34g is arranged at a position corresponding to the bearing cap 28E farthest from i so as to connect between the side walls 34a and 34b. Also, the first cylinder 46A and the second cylinder
Only the protrusion 34e ₂ for fixing the bearing cap 28B is formed between the cylinders 46B, and the rib 34g for connecting the protrusion 34e ₂ and the side walls 34a and 34b is not formed.

The first cylinder 46A of the lower block 34
The portion directly below each cylinder except for is formed in a cross-sectional shape as shown in FIG. That is, in the width direction of the lower block 34, the curved surface portion 3 along the locus of the lower end portion of the connecting rod is formed.
4m is formed. In the curved surface portion 34m, the surface on the entrance side of the connecting rod on the left side in the drawing is shaped along the trajectory of the connecting rod, and the portion on the exit side on the opposite side is planar as shown. And the side wall 34b on the escape side
A collar portion 34n is formed on the inner surface of the to reduce the oil lifted by the connecting rod. An oil return hole 34p for returning oil to the oil pan 43 attached to the lower portion of the lower block 34 is formed on the lower side of the collar portion 34n.
Thus, the oil repelled on the lower side is dropped into the oil pan 43. Similarly, an oil return hole 34 is provided between the curved surface 34m on the connecting rod entrance side and the side wall 34a.
q is formed.

Further, an oil return hole 34r is provided at a position closer to the connecting rod entrance side of the curved surface portion 34m in order to improve the return efficiency of oil riding on the curved surface portion 34m. This oil return hole 34r
Are formed in a plane position as shown in FIG. Here, as shown in FIG. 4, the oil pan 43 attached to the lower side of the lower block 34 sucks up the oil in the oil pan 43 and circulates it in the cylinder block 24 by a broken line. Oil strainer 50 shown in
Are arranged. The position of the suction port 50a of the oil strainer 50 is arranged on the escape side of the connecting rod in the width direction in the oil pan 43 as shown in the figure. On the other hand, the oil return hole 34r is formed at a position as far as possible from the suction port 50a of the oil strainer 50 on the entrance side of the connecting rod. This is because when the oil drops into the oil pan 43 from the oil return hole 34r, bubbles are mixed into the oil due to the impact of the drop, so that the bubbles are less likely to be sucked into the oil strainer 50. .. If air bubbles are mixed in the oil sucked into the oil strainer 50, the oil will not be sufficiently cooled, which will cause the engine to burn.
Therefore, with such consideration, the oil strainer 5
Air bubbles are not mixed in 0 as much as possible. A rib portion 34s is formed on the back surface of the portion of the lower block 34 where the oil return hole 34r is formed, as shown in FIG. 7, which is a view of the lower block 34 from the back side. The circumference of the return hole 34r is reinforced. This is to improve the oil return
Since the oil return hole 34r is provided at a position where the explosion load is most applied, the oil return hole 3r is caused by this load.
This is to prevent damage around the 4r.

Further, the shape of the portion of the lower block 34 immediately below the first cylinder has a sectional shape as shown in FIG. In this cross-sectional portion, as described above, in order to reduce the support rigidity of the protrusion 34e ₂ fixing the bearing cap 28B, the peripheral portion of the protrusion 34e ₂ is made flat. As described above, this first cylinder 46
The bottom plate portion of the lower block 34 corresponding to the cylinders other than A is
Since it is formed into a curved surface as shown in FIG. 5, oil is likely to adhere to the connecting rod and the oil is likely to be lifted up. Actually, it is better in terms of lubricity that the oil is easily attached to the connecting rod in this way, but since the oil of the connecting rod is lifted up, this lifted oil causes the cylinder block to block. There is a problem that the blow-by gas, which is opened below the main body 24, easily enters the reflux passage. The blow-by gas is oil-removed by an oil separator provided in the middle of the recirculation passage, is returned to the intake system and is re-combusted, but it can be said that it passes through the oil separator once.
It is not preferable that a large amount of oil is mixed in the blow-by gas.

Therefore, in one embodiment, the bottom plate portion (portion shown in cross section in FIG. 6) of the lower block just below the first cylinder 46A, which is already flat for the purpose of lowering the supporting rigidity, is corresponded. An opening 24f of the blow-by gas recirculation passage as shown by a chain double-dashed line in FIG. 4 is formed above the cylinder block main body 24. If you do this,
In the flat plate-like portion of the lower block 34 directly below the first cylinder 46A, it is difficult to lift up the oil in the connecting rod, and therefore it is possible to prevent the oil from being mixed into the blow-by gas as much as possible.

Next, returning to FIG. 2, another method of adjusting the fastening force when fixing the bearing caps 28A to 28E from the side of the lower block 34, which is another feature of the embodiment, will be described. In a normal engine, as shown in FIG. 2, the distance between the bearing caps 28A to 28E arranged between the cylinders and the engine mount 44 differs depending on the bearing caps 28A to 28E. As for the vibration of the engine, the reaction force when pushing down the piston due to the explosion in the cylinder vibrates the entire engine rigidly, and the explosive force transmitted from the piston through the connecting rod causes the crankshaft 22 and Some of them vibrate the flywheel, etc. The latter vibration of these is transmitted from the bearing caps 28A to 28E through the cylinder block body 24 as shown by the arrow in the figure, and the engine mount 44
Through the vehicle. At this time, this vibration is also transmitted to the engine mount provided on the mission side, but since the vibration transmitted to the vehicle interior through the engine mount 44 is transmitted to a position closer to the occupant's position, The impact on riding comfort is great.

Here, as described above, the engine mount 4
Since the position 4 is separated from the positions of the bearing caps 28A to 28E by different distances, the vibrations of the bearing caps 28A to 28E are transmitted to the engine mount 44 at different transmission times. .. On the other hand, since the explosion intervals of the cylinders 46A to 46D are constant, if the transmission time of the vibration from all the bearing caps 28A to 28E to the engine mount 44 is the same, the vibration between the cylinders that explode in sequence will not occur. , Engine mount 4 without overlapping each other
4 is transmitted to the passenger compartment. Therefore, the effect of increasing unpleasant vibration due to the interference of vibration does not occur, and the adverse effect on the riding comfort can be minimized. For example, the rotation speed of the engine 20 becomes high, the time interval between explosions of the cylinders 46A to 46D becomes shorter than the vibration transmission time from the bearing caps 28A to 28E to the engine mount 44, and the vibrations of the explosions mutually occur. Even if they overlap with each other, if each vibration transmission time is constant, a vibration with a constant rhythm occurs, so that it is difficult to notice.

For these reasons, in the engine 20 of the embodiment, the bearing caps 28A to 28A are provided.
The vibration transmission time from E to the engine mount 44 is kept constant. Specifically, the lower block 34
The tightening force of the side bolts 42 for fixing the bearing caps 28A to 28E from the side thereof is set to be looser for the bearing cap farther from the engine mount 44.

More specifically, as the uncomfortable vibration felt by the human body, 200 to 50 caused by the bending vibration of the crankshaft 22 due to the deflection of the crank pulley and the flywheel at the time of combustion of each cylinder 46A to 46D.
There is so-called purring sound in the 0 Hz region. This rumble is mainly due to the engine speed of 3500 to 4000.
It occurs at rpm. In one embodiment, the fastening force of the side bolts 42 that fix the bearing caps 28A to 28E is about 80 kg · cm to 270 kg · c.
Adjusted in the range of m. Then, basically, the fastening torque is made smaller as the bearing cap is farther from the engine mount 44, and when the auxiliary machine 60 and the like are interposed, the fastening torque is made smaller as the bearing cap is closer to the auxiliary machine 60. That is, assuming that the auxiliary machine 60 is not provided, for example, the fastening force of the side bolt of the bearing cap 28A farthest from the engine mount 44 is set to be the weakest, and the bearing caps 28B, 28C, 28
The fastening force is strengthened as the engine mount is approached in the order of D and 28E. If there is an auxiliary machine, its mass acts as a resistance to vibration transmission, so the fastening force is adjusted according to its position.

When making these adjustments, if transmission speed data is obtained while experimentally adjusting the fastening force for one or several vehicles of one vehicle type, the transmission speed data for the same vehicle type can be obtained based on these data. Since the fastening force may be uniquely determined by taking an average value or the like, it is not necessary to make adjustments while measuring each unit. With such an adjusting method, the tightening force can be adjusted without lowering the production efficiency. Further, if the fastening force is changed in this way, the natural frequency around the bearing cap where the fastening force is weakened is increased, the transmission speed from the bearing cap to the engine mount 44 is increased, and the vibration transmission time is shortened. To be done. On the other hand, since the mass of the lower block 34 is added around the bearing cap where the fastening force is increased and the natural frequency becomes low, the transmission speed from the bearing cap to the engine mount 44 becomes low and the vibration transmission time becomes long. .. Therefore, as a result, it is possible to keep the vibration transmission time from all bearing caps to the engine mount constant, prevent vibration interference due to the explosion of each cylinder, and reduce vibrations that deteriorate ride comfort. You can hold it down.

The present invention can be applied to modifications and variations of the above embodiments without departing from the spirit of the invention. Hereinafter, some modified examples will be described. Figure 8,
FIG. 9 is a diagram showing a first modification. In one embodiment, in order to prevent the thrusting force from the reinforcing portion 34j of the lower block 34 at the connecting point 34k from being easily received,
The protrusion 34e ₂ for fixing the bearing cap 28B located between the first cylinder 46A and the second cylinder 46B is not provided with the rib portion 34g connected to both side walls 34a and 34b of the lower block 34. In the first modification,
Although there is a rib portion 34g connected to both side walls 34a and 34b of the lower block 34, the bearing cap 28B is not fixed to this rib portion 34g. An escape portion 34t is formed at the center of the rib portion 34g as shown in FIG. 9 so that the upper surface of the rib portion 34g does not come into contact with the lower surface of the bearing cap 28B. By doing so, it is possible to prevent the thrust force from the mounting portion 34i of the transmission case 45 from being transmitted to the bearing cap 28B, as in the case of the first embodiment.

FIG. 10 is a diagram showing a second modification. In this modification, the first cylinder 46A and the second cylinder 46B
Like the bearing caps 28A and 28C to 28E of the other parts, the bearing cap 28B located between the two is fixed to the lower block 34 in the state shown in FIG. The connecting point 34k of the reinforcing portion 34j of the mounting portion 34i of 45 to the lower block 34 is displaced from the position corresponding to the bearing cap 28B. With this configuration, the bearing cap 28B is less likely to receive the thrust force from the reinforcing portion 34j.

11 to 13 show the third and fourth modifications.
It is the figure which showed the example. In these variants, the bearing
Projection portion 34e for fixing the caps 28A to 28E₁ ~ 3
4e _Five The strength of each rib portion 34g in the
The closer it is, the weaker it is. This rib part 34g
As a method of changing the intensity of
In the third modification shown, the rib portion 34g₃ ~ 34g_Five of
A rib portion that is distant from the reinforcing portion 34j such that the height is changed.
The height of this rib is made higher. Also,
In the fourth modification shown in FIG. 13, the rib portion 34g₂ ~ 3
4 g_Five The thickness of the
The thicker the rib, the thicker this rib should be.
It

FIG. 14 shows a fifth modified example, which is the center of the second cylinder 46B and the third cylinder 46C, that is, the cylinder block body 24 and the lower block 34.
Of the bearing cap 28 located substantially in the center in the longitudinal direction of the
The C is made to float from the lower block 34.
The positions of the central portions of the cylinder block body 24 and the lower block 34 in the longitudinal direction hit the antinode portion of the vibration of the entire engine block, so the displacement is the largest, and the bearing cap 28C is attached to the cylinder block body 24 and the lower block at this portion. If the bearing cap 28C is fixed on both sides, the bearing cap 28C is likely to be twisted. Therefore, if the bearing cap 28C at the central portion is not fixed to the lower block 34 as shown in FIG. 14, the vibration suppressing effect is further enhanced. It is also possible to combine this modification with one embodiment and other modifications.

As described above, according to the embodiment and the first to fifth modifications, it is possible to provide the lower block structure in which it is difficult to transmit the thrust force from the attachment portion of the mission case to the bearing cap. Further, since the vibration transmission time from the bearing cap to the engine mount can be made constant for all the bearing caps, it is possible to prevent uncomfortable vibration and improve riding comfort.

[0033]

As described above, according to the cylinder block structure of the engine of the present invention, by changing the fastening force of the side bolts for fastening the bearing cap to the lower block, the bearing caps adjacent to each cylinder can be removed. Since it is possible to change the vibration transmission speed of, and the vibration transmission time from each bearing cap to the engine mount can be made constant, there is no interference of vibration due to the explosion of each cylinder, and it also becomes a vibration at a constant interval, The riding comfort can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in a direction orthogonal to a crankshaft of an engine to which an engine cylinder block structure according to an embodiment is applied.

FIG. 2 is a partial cross-sectional view of the engine shown in FIG. 1 seen from the direction of the arrow.

FIG. 3 is a cross-sectional view showing an intermediate bearing cap between the first cylinder and the second cylinder.

FIG. 4 is a plan view of a lower block.

5 is a sectional view taken along line AA in FIG.

6 is a sectional view taken along line BB in FIG.

FIG. 7 is a view of the lower block seen from the back side.

FIG. 8 is a partial cross-sectional view of a first modification viewed from the side.

FIG. 9 is a front view of the first modified example.

FIG. 10 is a diagram showing a second modification.

FIG. 11 is a partial cross-sectional view of a third modification viewed from the side.

FIG. 12 is a front view of a third modified example.

FIG. 13 is a diagram showing a fourth modification.

FIG. 14 is a diagram showing a fifth modification.

[Explanation of symbols]

 20 engine 24 cylinder block body 26 bearing part 28A to 28E bearing cap 30 bearing metal 32 bolt 34 lower block 36 bolt 40 bush 42 bolt 43 oil pan 44 engine mount 45 mission case 46A to 46D first cylinder to fourth cylinder 50 oil strainer

Claims (4)

[Claims] 1. A cylinder block structure of an engine, which has a crankshaft extending along a longitudinal direction and is attached to a vehicle body through a mount member, extending vertically on both sides in the width direction. The cylinder block main body having side wall portions, and the bearing metal, which is arranged at a substantially central portion in the width direction below the cylinder block main body and rotatably supports the crankshaft at a plurality of locations along the longitudinal direction, And a plurality of side bolts for fixing each of the plurality of bearing caps to the side wall portion from the side of the cylinder block body. The farther away the bearing cap is from the support that secures the bearing cap. A cylinder block structure of an engine, wherein a direction to decrease the clamping force of the Doboruto multiplied by correction. 2. The cylinder block main body is provided with at least one auxiliary machine between the plurality of bearing caps and the mount member, and the bearing caps closer to the auxiliary machines fix the bearing caps. The cylinder block structure for an engine according to claim 1, wherein the fastening force of the side bolts is reduced. 3. The bearing cap is formed with a female screw portion to be screwed into the side bolt, and the side wall portion is fitted with a plurality of bushes each having a through hole at the center thereof. 2. The side bolt is screwed into the female screw portion through the pin, and the bearing cap is fixed to the side wall portion.
Alternatively, the cylinder block structure of the engine according to claim 2. 4. The lower portion of the cylinder block main body is constituted by a lower block divided from the upper portion of the cylinder block main body with a boundary in the vertical direction near the central axis of the crankshaft, and the side wall portion is formed of the lower block. The cylinder block structure for an engine according to claim 1, wherein the cylinder block structure is formed in a block.