JPS61105325A - Balancer driving device of engine - Google Patents

Abstract

PURPOSE:To reduce the diameter of a drive transmission portion of a cam shaft and the projecting length of a crankshaft by taking out driving force by a countershaft engaged with the first power transmission member, and driving a balancer shaft by the second power transmission member engaged with the countershaft. CONSTITUTION:As a timing chain 34 as the second power transmission member is not engaged with a crankshaft 8, and crankshaft 8 is driven through a countershaft 25, the diameter of a cam pulley 22 of a cam shaft 15 can be set smaller, not regulated by balancer shafts 28, 29. On the other hand, a driving force transmission portion where the second power transmission member for driving the balancer shafts 28, 29 is engaged is not formed on the cam shaft 15, so that the total height and length of an engine can be reduced by lessening the projection amount of the crankshaft 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a balancer drive device for suppressing vibrations in an engine.

(Prior art) Conventionally, as seen in Japanese Patent Laid-Open No. 51-46607, in order to cancel the vibration caused by the secondary reciprocating inertia force generated in the vertical direction in a multi-cylinder engine, the shaft of the crankshaft has been used. A pair of balancer shafts are provided on the left and right sides of the center, and the balancer shafts are rotated in opposite directions at a speed of 2 engine revolutions.
A technique for driving at twice the speed is known.

In order to drive the balancer shaft with the crankshaft, the crankshaft must also drive the camshaft in response to its rotation, and the camshaft must be decelerated to 1/2 of the rotation of the crankshaft. need to be driven.

However, if the pair of balancer shafts and camshafts are driven by a single power transmission member such as a timing belt or chain engaged with the crankshaft, as seen in the previous example, the engine There is a risk that the overall height will increase. In other words, the diameter of the crank pulley needs to be twice the diameter of the balancer shaft's bobber, and the diameter of the camboob should be roughly four times larger.On the other hand, it is not possible to make the pulley of the balancer shaft smaller. , there is a limit in terms of reliability such as strength, and even if this is set to the minimum diameter, the diameter of the camboole will be extremely large. Therefore,
This cambool is higher than the cylinder head and becomes an obstacle in reducing the overall height of the engine.

In addition, two power transmission members are engaged with the crankshaft so that the balancer shaft and the camshaft are driven separately and independently.
It is conceivable to change the diameter of the crank pulley for each to reduce the diameter of the camboo so as to satisfy the above-mentioned requirement for the overall height of the engine. However, in this case, engaging the two power transmission members with the crankshaft causes the end of the crankshaft to protrude significantly from the end face of the cylinder block, which increases the overall length of the engine. , which becomes an obstacle to compactness.

(Object of the Invention) In view of the above circumstances, an object of the present invention is to provide an engine balancer drive device that reduces both the overall height and overall length of the engine.

(Structure of the Invention) The balancer drive device of the present invention engages a first power transmission member that transmits the rotation of the crankshaft to the camshaft with a driving force transmission section provided respectively on the crankshaft and the camshaft. A part of the first power transmission member is engaged with a first driving force transmission part of an intermediate shaft having a smaller diameter than a driving force transmission part of the crankshaft, and is connected to a second driving force transmission part of the intermediate shaft in a left and right pair. A second power transmitting member is engaged with the driving force transmitting portion of the balancer shaft, and the diameter of the driving force transmitting portion of the balancer shaft is formed to be smaller than the diameter of the second driving force transmitting portion of the intermediate shaft. This is a characteristic feature.

The first power transmission member is composed of a timing belt or a timing chain, while the second power transmission member is composed of a timing belt, a timing chain, or a gear. Alternatively, it may be composed of gears.

(Effects of the Invention) According to the present invention, the intermediate shaft is engaged with the first power transmission member that drives the camshaft, the driving force is extracted by the intermediate shaft, and the second power transmission member engaged with the intermediate shaft is engaged with the intermediate shaft. The left and right balancer shafts are driven by the crankshaft, and the speed of the previous stage is increased by transmission from the crankshaft to the intermediate shaft, and the speed is roughly increased by transmission from this intermediate shaft to the balancer shaft. Therefore, even if the diameter of the driving force transmitting part of the balancer shaft is increased to a certain extent, the diameter of the driving force transmitting part of the camshaft can be suppressed, thereby preventing the overall height of the engine from increasing, and also reducing the diameter of the second power transmitting member. Since the balancer shaft does not engage with the crankshaft, it is possible to prevent the protrusion length of the crankshaft from increasing, that is, the overall length of the engine, and to negate the secondary reciprocating inertia force on the engine, making it possible to install a balancer shaft drive device in a compact manner. It is something.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

Figure 1 is a front view of the engine with the timing belt cover and chain case removed, Figure 2 is a side view in central section, Figure 3 is a front cross-sectional view of the cylinder bore, and Figure 4 is a partial view of the cylinder block. FIG. 2 is a plan view of a main part shown in cross section.

In the in-line four-cylinder engine 1, a cylinder head 3 is fastened onto a cylinder block 2, an oil pan 4 is mounted on the lower part of the cylinder block 2, and a head cover 5 is mounted on the cylinder head 3.

A piston 6 is fitted into each cylinder bore 2a of the cylinder block 2, and each piston 6 is connected to a crankshaft 8 by a connecting rod 7. This crankshaft 8 is supported by a bearing part 2b between each cylinder of the cylinder block 2, and due to the shape of this crankshaft 8, when the piston 6 of the 1.4th cylinder is at the top dead center, the piston 6 of the 2nd and 3rd cylinder is at the top dead center. The piston 6 is configured to reciprocate out of phase so that it is located at the bottom dead center (see FIG. 2).

Further, the cylinder head 3 is formed with an intake port 12 and an exhaust port 11 that communicate with the combustion seedling 10, and the intake port 12 is opened and closed by an intake valve 14, and the exhaust port 11 is opened and closed by an exhaust valve 13, respectively. Above intake valve 1
(See Figure 3)
.

One end of the crankshaft 8 protrudes to the front side of the cylinder block 2, and a timing belt 1 as a first power transmission member for driving a camshaft 15 is attached to the crankshaft 8.
A crank pulley 19 serving as a disk-shaped driving force transmitting portion to which the crank pulley 8 is engaged is integrally fixed. Further, a belt pulley 19a is formed on the crank pulley 19 and is engaged with a transmission belt 20 that drives an alternator, water pump, etc. (not shown) (see FIG. 2). On the other hand, the other end of the crankshaft 8 protrudes toward the rear end side of the cylinder block 2 and is connected to a flywheel 21, which outputs engine driving force.

The timing belt 18 is engaged with a cam pulley 22 and two idler pulleys 23 and 24, which are fixed to the camshaft 15 as a disc-shaped driving force transmission part.
5, and a part thereof is engaged with an intermediate pulley 26 serving as a disk-shaped first driving force transmission portion of the intermediate shaft 25,
This intermediate shaft 25 is driven at the same time. The diameter of the cam pulley 22 is twice the diameter of the crank pulley 19, and the camshaft 15 is driven at a speed of 1/2 of the rotation of the crankshaft 8, while the diameter of the intermediate pulley 26 of the intermediate shaft 25 is is formed smaller than the crank pulley 19, and the intermediate shaft 25 is driven at a higher speed than the rotation of the crankshaft 8.

The cylinder block 2 also has a crankshaft 8.
A pair of balancer shafts 28 are placed at set positions on the left and right with respect to the axis of the
．． 29 are arranged. This left and right balancer shaft 28.
29 are housed slightly above the crankshaft 8 in balancer shaft cases 30.degree. 30 formed integrally with the left and right side walls of the cylinder block 2, respectively, and are disposed parallel to the crack shaft 8. Each balancer shaft 28, 29 includes an eccentrically formed balance weight 28a, 29a,
Front end and intermediate shaft portions 28b, 29b of cylinder block 2
(See Figure 2).

The front end portions of the left and right balancer shafts 28 and 29 protrude toward the front side of the cylinder block 2, and chain sprockets 31 and 32 are respectively provided at these portions as disk-shaped driving force transmitting portions. On the other hand, an intermediate sprocket 27 is provided on the intermediate shaft 25 as a disk-shaped second driving force transmitting portion on the inside of the intermediate pulley 26, that is, on the cylinder block 2 side.
is provided. A timing chain 34 is connected as a second power transmission member from the intermediate sprocket 27 of the intermediate shaft 25 to the sprockets 31.32e and idler sprockets 33 of the left and right balancer shafts 28.29.
is engaged. This timing chain 34 is guided by chain guides 35, 36, and its outer side engages with the sprocket 31 of the left balancer shaft 28, and its inner side engages with the sprocket 32 of the right balancer shaft 29. , the left and right balancer shafts 28, 29 are configured to rotate in opposite directions. Further, the diameters of the sprockets 31 and 32 of the left and right balancer shafts 28 and 29 are set smaller than the diameter of the intermediate sprocket 27 of the intermediate shaft 25, so that the balancer shafts 28 and 29 are sped up faster than the rotation of the intermediate shaft 25. It is driven by This balancer shaft 28.29
is an increase in speed from the crankshaft 8 to the intermediate shaft 25, and an increase in speed from the crankshaft 8 to the intermediate shaft 25.
By increasing the speed from 5 to the balancer shaft 28.29 in two steps,
Ultimately, it is driven to rotate at twice the speed of the crankshaft 8. Roughly speaking, the rotational phase of the balancer shafts 28 and 29 is as shown in FIG. 3 when the piston 6 is at the top dead center or the bottom dead center.

29a is provided so as to be eccentrically located below the cylinder head 3 on the opposite side.

Timing chain 34 as the second power transmission member
is arranged so as to pass through a space S formed below the water jacket 37.

That is, the lower end position of the water jacket 37 on the front side of the cylinder block 2 is formed above the normal formation position as shown on the rear side of the cylinder block 3 in the cloth portion in FIG. With respect to the front end surface 2C of the cylinder block 2 at the portion 37, the front wall 2d of the lower portion is recessed in a stepped manner to provide a space S below the water jacket 37. Timing chain 3 along the flat part
4 is arranged so that it passes through. Therefore, balancer shaft 2
8.29 sprocket 31.32. At least the inner portions of the timing chain 34 for driving the timing chain 34, the intermediate sprocket 27 of the intermediate shaft 25 that engages with it, the idler sprocket 33, and the chain guide 35. It is located on the opposite side.

Further, it is necessary to supply lubricating oil to the timing chain 34, and this lubricating oil is supplied to the timing belt 18.
The front side of the timing chain 34 is covered with a chain case 38 to prevent it from adhering to the surface, and FIG. 1 shows the joint sealing surface 38a of the chain case 38. On the other hand, a timing belt cover 39 is provided on the front side of the timing belt 18 to prevent dust, water, etc. from adhering to the timing belt 18. This timing belt cover 39 is also bonded and sealed to the front side of the chain case 38, and in FIG. 1, the bonding and sealing surface 39a to the chain case 38 is shown by a chain line.

Furthermore, as shown in FIG. 4, the intermediate shaft 25 is equipped with an intermediate sprocket 26 as a first driving force transmitting part at the front end, and an intermediate sprocket 27 as a second driving force transmitting part behind it. , is provided so that the oil pump 40 is driven by this intermediate shaft 25. That is, the oil pump 40 is disposed on the side surface of the cylinder block 2 at the rear of the intermediate shaft 25, and the drive shaft 41 of the oil pump 40 is connected to the rear end of the intermediate shaft 25 to drive the rotor 42 thereof. has been done.

According to the embodiment described above, the timing chain S4 serving as a second power transmission member for driving the balancer shafts 28 and 29 is not engaged with the crankshaft 8, but is driven via the intermediate shaft 25. The balancer shaft 28.
29, the diameter of the cam pulley 22 of the camshaft 15 is the same as that of the balancer shaft 28.
．． It is possible to set the diameter small without being restricted by 29. Also, balancer axis 28°29
The diameters of the chain sprockets 31 and 32 can be set to a certain degree, ensuring reliability, and
By reducing the diameter of the cam pulley 22, the overall height of the engine can be reduced. On the other hand, since the camshaft 15 does not have a driving force transmission part that engages the second power transmission member for driving the balancer shaft 28, 29, the overall length of the engine can be shortened by reducing the protrusion of the crankshaft 8. can be achieved.

In general, by configuring the second power transmission member that drives the balancer shafts 28 and 29 with the timing chain 34,
It is narrower than the timing belt 18 and is advantageous in shortening the overall length of the engine. Furthermore, by arranging the timing chain 34 in the space S formed below the water jacket 37 of the cylinder block 2, the overall length of the engine can be further shortened. In addition, by adopting the timing chain 34, there are sprockets 3 inside and outside of the timing chain 34.
Although a structure in which the rotating directions of the left and right balancer shafts 28 and 29 are reversed by engaging the balancer shafts 28 and 29 is simple, a structure in which a gear for reversing is interposed may be used. Note that due to the arrangement of the timing chain 34, the water jacket 3
7 becomes narrower, but since the thermal load is relatively low and the reduction is only in one part, there is almost no effect on the cooling performance.

In particular, in the above embodiment, the balancer shaft 28. ．． By effectively utilizing the intermediate shaft 25 provided for driving the intermediate shaft 29,
5 to drive the oil pump 40, the crankshaft 8 can be made shorter than the conventional structure in which the driving force for the oil pump 40 is taken directly from the crankshaft 8. This contributes to shortening the time.

In the above embodiment, the timing belt 18 is used as the first power transmission member for driving the camshaft 15, but a timing chain may be used instead. This is preferable because the running noise is lower.

Furthermore, although the timing chain 34 is used as the second power transmission member in the above embodiment, the running noise thereof is prevented from being propagated to the outside by the chain case 38 and the timing belt cover 39, thereby reducing it.

On the other hand, the second #j for driving the balancer shaft 28,29
In the above embodiment, the J force transmission member is the timing chain 3.
4 is used, but a timing belt may also be used; in that case, unless a double-sided toothed belt is used, a reversing mechanism using gears must be provided, and the overall length of the engine is shorter than that of a timing chain 34. Although it is larger, it can be made shorter than when two timing belts are engaged with the crankshaft 8. Further, even if the balancer shafts 28 and 29 are driven from the intermediate shaft 25 by a gear train, the overall length of the engine can be shortened similarly to the timing chain 34.

Further, although the above embodiments have been described with respect to an in-line four-cylinder engine, the present invention can be applied to other multi-cylinder engines configured to drive two balancer shafts at increased speed to cancel out the secondary reciprocating inertia force. It is possible.

[Brief explanation of drawings]

Figure 1 is a front view of the engine with the timing belt cover and chain case removed, Figure 2 is a side view in cross section at the center, Figure 3 is a front view in cross section at the cylinder bore, and Figure 4 is a complete view of the cylinder block. FIG. 3 is a plan view of a main part shown in partial cross section. 1... Engine 2... Cylinder block 3... Cylinder head 8... Crankshaft 15... Camshaft 18...・Timing belt (first power transmission member) 19...Crank pulley (driving force transmission part)
22...Cam pulley (driving force transmission part) 25,...
...Intermediate shaft 26 ...Intermediate pulley (first driving force transmission section>2
7... Intermediate sprocket (second driving force transmission part) 28.29... Balancer shafts 28a, 29a... Balance weight 31.3
2... Sprocket (driving force transmission part) 34...
...Timing chain (second power transmission member) 37
...Water jacket 38...Chain case 39...Timing belt cover Fig. 1 Fig. 3 19 819a

Claims (1)

[Claims] (1) A first power transmission member that transmits rotation of the crankshaft to the camshaft is engaged with a disk-shaped driving force transmission portion provided on each of the crankshaft and the camshaft, and the first power transmission member The portion is engaged with a disk-shaped first driving force transmitting portion provided on the intermediate shaft and having a smaller diameter than the driving force transmitting portion of the crankshaft, and is located at a set position on the left and right with respect to the axis of the crankshaft. A pair of balancer shafts each having a balance weight are provided, a second power transmission member is engaged with a second driving force transmission section of the intermediate shaft and a driving force transmission section of the pair of balancer shafts,
A balancer drive device for an engine, wherein the driving force transmitting portions of the two balancer shafts are disc-shaped and have a smaller diameter than the second driving force transmitting portion of the intermediate shaft.