JP2000161440A - Balance device for four-cycle v-type eight-cylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balance device to be made mountable on mass-produced vehicles by equipping a plane crank, and miniaturizing and lightening a V-type engine having a bank nipping angle of 90 deg.. SOLUTION: First and second gears are interposed between first and second endless power transmission belts 15a and 15b, for driving the cam shafts of the cylinder heads of respective banks having V-character shape and a crank shaft 7; and a pair of balance shafts are provided so that the axial lines of the balance shafts can be parallel to the shaft 7 at symmetric positions, with the divided surface between upper and lower blocks 1 and 2 divided from a horizontal surface passed through by the center of the shaft 7 in a cylinder block as the center. The belts 15a and 15b and a third endless power transmission belt 19 are made unlapped in a crank axial direction by connecting the shaft 7 and a lower block side balance shaft 16 by a third endless power transmission belt, and connecting both the mating balance shafts by third gears 20a and 20b and inversely driving the balance shafts. The swollen out of an engine in the axis 7 direction can be suppressed by arranging the respective mating belts and the respective mating gears on the same plane orthogonal to the axis 7 direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a 4-cycle V-type 8
The present invention relates to a balance device for canceling a secondary vibration force of a cylinder engine.

[0002]

2. Description of the Related Art A 4-cycle V-type 8 having a bank angle of 90 degrees.
In a cylinder engine, when a plane crank in which all the crankpin shaft centers are located on the same plane is employed, the operation cycle between both banks is every 180 degrees, and intake and exhaust alternately occur. According to this, the intake air in one bank
Since the exhaust timing is at regular intervals and exhaust interference does not occur, it is advantageous in obtaining high output.

On the other hand, in the case of a flat crank V-type eight-cylinder engine, secondary imbalance occurs due to the inertial force of the reciprocating mass. This is equivalent to the situation where the cylinder is horizontal (the inertial force remains in the horizontal direction). Therefore, this unbalance is achieved by applying the theory of the secondary balancer for the conventional in-line four-cylinder engine, bisecting the bank narrow angle and arranging the two at symmetrical positions with respect to the horizontal plane passing through the center of the crankshaft. The balance can be offset by rotating the balance shafts in opposite directions (see Japanese Patent Application Laid-Open No. 8-193648).

[0004]

If the balancer is to be provided in a flat crank V-type eight-cylinder engine, as shown in the above-mentioned Japanese Patent Application Laid-Open No. 8-193648, the balancer is actually provided below one cylinder head. It is a target.

On the other hand, in a V-type engine having a bank narrow angle of 90 degrees, both cylinder heads are relatively separated from each other.
Generally, the timing endless power transmission bands between the crankshaft and each cylinder head are provided separately. In this case, it is natural that the balancer is arranged so as not to interfere with the timing endless power transmission band.For example, when the balancer is driven by a chain, the drive chain is also arranged so as not to interfere with the timing endless power transmission band. Must be placed.

Therefore, at least three pulleys or sprockets are provided on the crankshaft, so that the engine tends to swell especially in the direction of the crankshaft.

[0007] The present invention has been devised to solve such problems of the prior art, and its main objects are as follows.
An object of the present invention is to provide a balance device for a four-cycle V-type eight-cylinder engine that can be miniaturized as an engine mounted on a mass-produced vehicle.

[0008]

In order to achieve the above object, the present invention provides a V-shaped crank having a plane crank whose center is located on the same plane and whose bank narrow angle is 90 degrees. The first and second endless power transmission bands (chain 15) for driving the camshafts of the cylinder heads of the V-shaped banks and the first and second endless power transmission bands (chains 15) in the type engine. And a pair of balance shafts 16a and 16b for rotating in opposite directions to each other.
Is provided in a cylinder block at a position symmetrical with respect to a division plane of the upper block 1 and the lower block 2 which is divided from a horizontal plane through which the center of the crankshaft passes, such that its axis is parallel to the crankshaft 7. The shaft 7 and the lower block 2 side balance shaft 16b are connected by a third endless power transmission band (chain 19) for driving the shaft, and the lower block side balance shaft 16b and the upper block side balance shaft 16a. Are connected by third gears 20a and 20b, and a balance device for reverse rotation driving is provided. As a result, the first and second endless power transmission bands for driving the camshaft and the third endless power transmission band for driving the balance shaft do not overlap in the crank axis direction, and the expansion of the engine in the crank axis direction. Outgoing can be suppressed. In particular, the first to third endless power transmission bands are arranged on the same plane orthogonal to the crank axis,
In addition, by disposing the first to third gears on the same plane orthogonal to the crank axis, the swelling of the engine in the direction of the crank axis can be further suppressed. Also, an upper block side balance shaft 1 is provided on the tight side of the third endless power transmission band.
6a, and a third endless power transmission band (chain 1).
By providing the guide member 28 and the supporting portion 28a of 9) between the upper block-side balance shaft 16a and the tight side of the third endless power transmission band, the distance between the crankshaft 7 and the two balance shafts 16 is increased. Can be minimized, and the dead space between the two can be effectively used.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an embodiment shown in the accompanying drawings.

FIG. 1 shows a four-cycle V to which the present invention is applied.
FIG. 3 is an elevation view of a type 8-cylinder engine on a crank pulley side.

The engine E has an upper block 1 having a pair of cylinder banks having a narrow angle of 90 degrees, a lower block 2 joined to a lower surface of the upper block 1, and a lower block 2 joined to a lower surface of the lower block 2. It comprises an oil pan 3 and cylinder heads 4a and 4b joined to respective upper surfaces of both cylinder banks of the upper block 1. Two camshafts 5a and 5b are provided above the cylinder heads 4a and 4b, respectively. These camshafts 5
a and 5b are covered with head covers 6a and 6b joined to the upper surfaces of the cylinder heads 4a and 4b.

A crankshaft 7 is supported by a main bearing on the joint surface between the upper block 1 and the lower block 2, as in a known engine.

An air conditioner compressor 8 is mounted on the right side of the crankshaft 7 in the upper block 1, and an AC generator 9 is mounted on the left side of the crankshaft 7 in the lower block 2. The compressor 8 and the alternator 9 are linked to the crankshaft 7 via a belt / pulley mechanism (not shown).

A crank sprocket 10 is fitted at an axially inner position of the crank pulley on the crankshaft 7, and a drive pinion 11 is further fitted at an axially inner position.

The drive pinion 11 has two reduced gear driven pinions as first and second gears provided at positions symmetrical to the plane passing through the center of the crankshaft, bisecting the narrow angle of the bank. 12a and 12b are engaged at the same time. And these two driven pinions 12a
・ 12b has small sprockets 13a and 13b respectively
Are provided integrally, and the small sprocket 13a
13b and two camshafts 5a and 5 for each cylinder bank
The silent chains 15a and 15b as the first and second endless power transmission bands for driving the cam shaft are wound around the cam sprockets 14a and 14b provided on the b. Thus, the rotational force of the crankshaft 7 is transmitted to each of the two camshafts 5a and 5b of both banks.

The upper block 1 and the lower block 2
The two balance shafts 16a and 16b are divided from a horizontal plane through which the center of the crankshaft passes, and their axes extend parallel to the crankshaft 7 at positions vertically symmetric with respect to these divided surfaces.
Is pivoted.

Of these two balance shafts 16a and 16b, a balance shaft sprocket 17 is fitted to the shaft end of the balance shaft 16b supported on the lower block side. A third endless power for driving the balance shaft is provided between the balance shaft sprocket 17, the crank sprocket 10, and a pump sprocket 18 fixed to an oil pump (not shown) mounted on the lower surface of the lower block 2. By winding the silent chain 19 as a transmission band, the lower balance shaft 16 b and the oil pump rotate in conjunction with the crankshaft 7.

The two balance shafts 16a and 16b are
The gears 20a and 20b as third gears having the same number of teeth fitted on the inner side in the axial direction of the sprocket 17 rotate in opposite directions at the same rotational speed.

The balance shaft 16 is disposed on the tight side of the silent chain 19 with respect to the direction of rotation of the crankshaft 7. Thereby, the relative phase angle error between the crankshaft 7 and the balance shaft 16 can be minimized.

Here, as described above, the respective camshaft driving silent chains 15a and 15b are driven by the crankshaft 7 (drive pinion 11) via the deceleration driven pinions 12a and 12b. Therefore, since the silent chain 19 is slightly separated from the crankshaft 7 and is wound around the balance shaft 16b (balance shaft sprocket 17) supported on the lower block side, the first endless power There is no interference between the silent chain 15a as the transmission band and the silent chain 19 as the third endless power transmission band. Therefore, the swelling of the engine E, particularly in the axial direction of the crankshaft 7, can be suppressed. In this configuration, the silent chains 15a and 15b and the silent chain 19
Are arranged on the same plane orthogonal to the axis of the crankshaft 7, and the driven pinions 12a and 12b and the gear 20a
20b are arranged on the same plane orthogonal to the axis of the crankshaft 7, whereby the swelling of the engine E, particularly in the axial direction of the crankshaft 7, can be further suppressed.

Each of the silent chains 15a and 15b wound around the cam sprockets 14a and 14b of each cam shaft 5 and the silent chain 19 wound around the balance shaft sprocket 17 and the pump sprocket 18 in both cylinder banks are provided. Tensioner 22 to 24 whose pressing force is automatically adjusted by a hydraulic plunger
And chain guides 25 to 28 for steadying. The chain tensioners 22 to 24 and the chain guides 25 to 28 include an upper block 1, a lower block 2, an oil pan 3, and a cylinder head 4a.
4b is fixed at an appropriate position on the end face of each crank pulley using a bolt or the like.

Here, the chain guide 28 on the tension side of the silent chain 19 and its supporting portion 28a are provided between the silent chain 19 on the tension side and the balance shaft 16a on the upper block side. As a result, the dead space between the silent chain 19 on the tension side and the balance shaft 16a on the upper block side can be effectively used, and the chain guide 28 does not become unnecessarily large.

The chain guide 28 is connected to the silent chain 15 on the side where the balance shaft 16 is provided.
and the chain guide 25 of FIG. As a result, at least two necessary supporting portions can be shared, and the number of parts and the number of assembling steps can be reduced. The integrated chain guides 25, 28 cover the upper block-side balance shaft 16a from that position, but since the position in the crank axis direction substantially coincides with the shaft end of the balance shaft 16a. The chain guide can be disposed by effectively utilizing the space outside the end of the balance shaft 16a, and this chain guide can be used as a thrust receiver for the balance shaft 16a. In this case, a thrust plate such as a thrust plate is used. Separate parts are not required, and the number of parts can be reduced and the size of the engine can be further reduced.

In the above structure, the endless power transmission band is a chain, but may be a belt. In this case, the sprocket may be changed to a pulley.

[0025]

As described above, according to the present invention, there is provided a flat crank in which all the crankpin centers are located on the same plane,
In a V-type engine having a bank narrow angle of 90 degrees, a crankshaft is provided between first and second endless power transmission bands for driving a cam shaft above a cylinder head of each bank forming a V-shape. In order to rotate in opposite directions with the first and second gears interposed therebetween, a pair of balance shafts is divided into an upper block and a lower block by dividing a horizontal plane through the center of the crankshaft in the cylinder block. Are provided at symmetrical positions around the axis so that their axes are parallel to the crankshaft, and the crankshaft and the lower block-side balance shaft are connected by a third endless power transmission band to drive the shaft, and By providing a balance device for connecting the lower block-side balance shaft and the upper block-side balance shaft with a third gear and performing reverse rotation, the first and second endless power transmission bands for cam drive are separated from each other. The third endless power transmission band for driving the shaft is separated from the third endless power transmission band so as not to overlap in the crank axis direction, and it is possible to suppress expansion of the engine in the crank axis direction. Turning is not complicated. In particular, the first to third endless power transmission bands are arranged on the same plane orthogonal to the crank axis, and the first to third gears are arranged on the same plane orthogonal to the crank axis. Swelling in the axial direction can be suppressed. Also, an upper block-side balance shaft is disposed on the tension side of the third endless power transmission band, and the guide member and its support portion of the third endless power transmission band are connected to the upper block-side balance shaft and the tension member on the tension side. By providing between the endless power transmission band 3 and the endless power transmission band 3, the relative phase angle error between the crankshaft and the balance shaft can be minimized, the dead space between the two can be effectively used, and the space can be saved.

[Brief description of the drawings]

FIG. 1 is an elevational view of a V-type engine to which the present invention is applied, on a crank pulley side.

FIG. 2 is an enlarged view of a main part of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Upper block 2 Lower block 7 Crankshaft 10 Crank sprocket 11 Drive pinion 12a Reduced driven pinion (first gear) 12b Reduced driven pinion (second gear) 15a Silent chain (first endless power transmission band) 15b Silent chain (second endless power transmission band) 16a / 16b Balance shaft 17 Balance shaft sprocket 19 Silent chain (third endless power transmission band) 20a / 20b Third gear 25-28 Chain guide (guide member) )

Claims (3)

[Claims] 1. A flat crank having all crankpin shaft centers located on the same plane, and a bank narrow angle of 9
A zero-degree balance device for a four-cycle V-type eight-cylinder engine, comprising first and second endless power transmission bands for driving a camshaft provided above a cylinder head of each V-shaped bank. A first gear and a second gear interposed between the first and second gears, and a pair of balance shafts for rotating in mutually opposite directions, an upper block divided from a horizontal plane passing through the center of the crankshaft in the cylinder block; The crankshaft and the lower block-side balance shaft are provided at positions symmetrical about a division surface with the lower block so that their axis is parallel to the crankshaft.
The third endless power transmission band is connected, and the lower block side balance shaft and the upper block side balance shaft are connected by a third gear to be driven in reverse. Balance device for cycle V type 8 cylinder engine. 2. The first to third endless power transmission bands are arranged on a first same plane orthogonal to a crank axis, and the first to third gears are arranged on a second plane orthogonal to the crank axis. The balance device for a four-cycle V-type eight-cylinder engine according to claim 1, wherein the balance device is arranged on the same plane. 3. The upper block-side balance shaft is disposed on the tight side of the third endless power transmission band, and the guide member of the third endless power transmission band and its supporting portion are connected to the upper block side. The balance device for a four-stroke V-type eight-cylinder engine according to claim 1 or 2, wherein the balance device is provided between a balance shaft and the third endless power transmission band on the tension side.