JPH0221463B2 - - Google Patents

Description

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

(Prior art) Conventionally, as seen in Japanese Patent Application Laid-Open No. 51-46607, a multi-cylinder engine has a balance weight in order to cancel vibrations caused by secondary reciprocating inertia force generated in the vertical direction. A technique is known in which a balancer shaft is provided and the balancer shaft is driven by a crankshaft in opposite directions at a speed twice the engine rotation speed.

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 is twice the pulley diameter of the balancer shaft, and the diameter of the cam pulley is 4 times the diameter of the pulley of the balancer shaft.
On the other hand, there is a limit to making the balancer shaft pulley smaller in terms of its strength and reliability, and even if it is set to the minimum diameter, the cam pulley diameter becomes very large. Therefore, this cam pulley is higher than the cylinder head portion, which becomes an obstacle in reducing the overall height of the engine.

In addition, two power transmission members are engaged with the crankshaft to drive the balancer shaft and the camshaft separately and independently, and the diameter of the crank pulley for each is changed to reduce the diameter of the cam pulley, as described above. It is conceivable to satisfy the requirements for the overall height of the engine. However, in this case, engaging the two power transmission members with the crankshaft means that the end of the crankshaft protrudes 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, it is an object of the present invention to provide an engine balancer device that reduces both the overall height and overall length of the engine.

(Structure of the Invention) The balancer 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, and also engages a first power transmission member that transmits the rotation of the crankshaft to the camshaft. An intermediate shaft having a first intermediate driving force transmitting part on the front side with which the second power transmitting member engages is provided with a second intermediate driving force concentrically from the first intermediate driving force transmitting part to the cylinder block side. a force transmitting portion, and a second power transmitting member is engaged with a driving force transmitting portion of a balancer shaft having a balance weight and a second intermediate driving force transmitting portion of the intermediate shaft; The second power transmission member is arranged at least partially along a space recessed below the water jacket at the front end of the cylinder block of the engine, and at least a part of the second power transmission member is arranged in the space inside the front end surface of the water jacket. It is characterized by being installed so that it passes through.

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 or a timing chain.
The power transmission member is composed of a timing belt, a timing chain, or a gear, and correspondingly, the driving force transmission section is composed of a belt pulley, a chain sprocket, or a gear.

(Effects of the Invention) According to the present invention, the second power transmission member is separately connected to the first power transmission member that drives the camshaft via the first and second intermediate drive force transmission portions of the intermediate shaft. By arranging at least a portion of the second power transmission member along the space provided below the water jacket of the cylinder block, the driving force transmission portion of the balancer shaft is configured to drive the balancer shaft. Even if the diameter of the second power transmitting member is increased to some 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. Since the balancer device passes inward from the front end of the water jacket of the block, it prevents the protrusion length of the crankshaft from increasing, that is, the overall length of the engine, and counteracts the reciprocating inertia force on the engine. It can be installed in

(Example) Hereinafter, an example of the present invention will be described 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 cross section at the center, Figure 3 is a front view in cross section at 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.

The in-line four-cylinder engine 1 has a cylinder block 2.
A cylinder head 3 is fastened to the top, an oil pan 4 is mounted below the cylinder block 2, and a head cover 5 is mounted on the cylinder head 3, respectively.

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 portion 2b between each cylinder of the cylinder block 2, and due to the shape of this crankshaft 8, when the pistons 6 of the first and fourth cylinders are at the top dead center, the pistons of the second and third cylinders are The piston 6 of the cylinder 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 chamber 10. 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. be done. The intake valve 14 and the exhaust valve 13
is opened and closed by the rocking of the rocker arm 16 as the camshaft 15 rotates (see FIG. 3).

One end of the crankshaft 8 is connected to the cylinder block 2.
A crank pulley 19 is integrated with the crankshaft 8 as a disk-shaped driving force transmitting part, which is engaged with a timing belt 18 as a first power transmitting member for driving the camshaft 15. is fixed to. Also, this crank pulley 19
A belt pulley 19a is formed in which a transmission belt 20 that drives an alternator, water pump, etc. (not shown) is engaged (see FIG. 2). On the other hand, the other end of the crankshaft 8 protrudes toward the rear end of the cylinder block 2 and is connected to a flywheel 21, which outputs engine driving force.

The timing belt 18 is connected to a cam pulley 2 fixed to the camshaft 15 as a disk-shaped driving force transmission part.
2 and two idler pulleys 23 and 24 to drive this camshaft 15, and a portion thereof is engaged with an intermediate pulley 26 serving as a disk-shaped first intermediate driving force transmission portion of the intermediate shaft 25. and 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 rotates at 1/2 the rotation of the crankshaft 8.
The diameter of the intermediate pulley 26 of the intermediate shaft 25 is smaller than that of the crank pulley 19, and the intermediate shaft 25 is driven at a higher speed than the rotation of the crankshaft 8.

Further, a pair of balancer shafts 28 and 29 are disposed on the cylinder block 2 at set positions on the left and right sides with respect to the axis of the crankshaft 8. These left and right balancer shafts 28 and 29 are located slightly above the crankshaft 8, and are provided with balancer shaft cases 3 that are integrally formed with the left and right side walls of the cylinder block 2, respectively.
0.30, and is arranged parallel to the crankshaft 8. Each balancer shaft 28, 29 has an eccentrically formed balance weight 28a, 29a.
It is supported by the front end of the cylinder block 2 and intermediate shaft portions 28b and 29b (see FIG. 2).

The front end portions of the left and right balancer shafts 28, 29 protrude toward the front side of the cylinder block 2, and chain sprockets 31, 32 are provided at these portions as disc-shaped driving force transmitting portions, respectively. on the other hand,
The intermediate shaft 25 is provided with an intermediate sprocket 27 as a disk-shaped second intermediate driving force transmitting portion on the inner side of the intermediate pulley 26, that is, on the cylinder block 2 side. Then, from the intermediate sprocket 27 of the intermediate shaft 25, the left and right balancer shafts 28, 2
A timing chain 34 is engaged with the sprockets 31, 32 and the idler sprocket 33 as a second power transmission member. This timing chain 34 has a chain guide 35,
36, 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, so that the left and right balancer shafts 28, 29 They 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 rotated at higher speed than the rotation of the intermediate shaft 25. being driven. These balancer shafts 28 and 29 are used to increase the speed from the crankshaft 8 to the intermediate shaft 25, and to increase the speed from the crankshaft 8 to the intermediate shaft 25.
Due to the two-stage speed increase from 5 to the balancer shafts 28 and 29, the crankshaft 8 is finally driven to rotate at twice the speed of the crankshaft 8. Furthermore, the rotational phase of the balancer shafts 28 and 29 is such that when the piston 6 is at the top dead center or the bottom dead center, the balance weights 28a and 29a are eccentrically downward on the opposite side from the cylinder head 3, as shown in FIG. It is provided so that it is located.

The timing chain 34 as the second power transmission member is disposed 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 on the right side of FIG. The front wall 2d of the lower part is recessed in a stepped manner with respect to the front end surface 2c of the cylinder block 2 in the part of the jacket 37, so that the water jacket 3
A space S is provided below 7, and the timing chain 34 is disposed so as to pass along the flat portion of the front wall 2d in this space S. Therefore, the sprocket 31 of the balancer shafts 28, 29,
32 and the timing chain 34 for driving it, the intermediate sprocket 27 of the intermediate shaft 25 that engages with it, the idler sprocket 33, and at least the inner portions of the chain guides 35 and 36.
It is located inward from the front end surface 2c of the water jacket 37.

Furthermore, it is necessary to supply lubricating oil to the timing chain 34, and to prevent this lubricating oil from adhering to the timing belt 18, the front side of the timing chain 34 is covered with a chain case 38, as shown in FIG. The joint sealing surface 38a is shown. On the other hand, a timing belt cover 39 is provided on the front side of the timing belt 18,
This is 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 is
In the figure, the joint sealing surface 39a with respect to the chain case 38 is shown by a chain line.

Further, as shown in FIG. 4, the intermediate shaft 25 has an intermediate sprocket 26 as a first intermediate driving force transmitting part at the front end, and an intermediate sprocket 27 as a second intermediate driving force transmitting part behind it. The intermediate shaft 25 is provided to drive the oil pump 40. That is, an oil pump 40 is disposed on the side surface of the cylinder block 2 at the rear of the intermediate shaft 25, and a 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 above-described embodiment, a space S is formed below the water jacket 37 at the front end of the cylinder block 2, and the timing chain 34 is installed in the space S.
is arranged to drive the balancer shafts 28 and 29, thereby shortening the overall length of the engine. In addition,
Although the water jacket 37 becomes narrower due to the arrangement of the timing chain 34, the thermal load is relatively low and the reduction is only in one portion, so there is almost no effect on the cooling performance.

The crankshaft 8 also has balancer shafts 28 and 29.
The balancer shaft 2 is provided so as to be driven via the intermediate shaft 25 without engaging the timing chain 34 as a second power transmission member for driving the balancer shaft 2.
8 and 29, the diameter of the cam pulley 22 of the camshaft 15 is not restricted by the balancer shafts 28 and 29, and can be set small. .
Furthermore, the diameters of the chain sprockets 31, 32 of the balancer shafts 28, 29 can be set to a certain degree large, thereby 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, the balancer shaft 28 is attached to the camshaft 15,
Since a driving force transmitting portion that engages the second power transmitting member for driving the crankshaft 29 is not formed, the overall length of the engine can be shortened by reducing the amount of protrusion of the crankshaft 8.

Furthermore, a second
By configuring the power transmission member with the timing chain 34, the width is narrower than the timing belt 18, which is advantageous in shortening the overall length of the engine. In addition, by employing the timing chain 34, the structure for reversing the rotation direction of the left and right balancer shafts 28, 29 by engaging the sprockets 31, 32 inside and outside the timing chain 34 becomes simple; It is also possible to have a structure in which they are interposed and engaged.

In particular, in the above embodiment, the intermediate shaft 25 provided for driving the balancer shafts 28 and 29 is effectively utilized,
Since the oil pump 40 is driven by the intermediate shaft 25, 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 overall length of the engine.

Note that the timing belt 18 is used as the first power transmission member for driving the camshaft 15 in the above embodiment, but a timing chain may be used instead, but the timing belt is This is preferable because the running noise is lower.
Further, 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, and thus is reduced.

On the other hand, as the second power transmission member for driving the balancer shafts 28 and 29, the timing chain 34 is used in the above embodiment, but a timing belt may also be used. If a belt is not used, a gear-based reversing mechanism must be provided. 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.

In addition, although the above embodiment has been explained with respect to an in-line four-cylinder engine, it is also possible to drive one or two balancer shafts at a constant speed or at an increased speed in order to cancel the primary or secondary reciprocating inertia force in a multi-cylinder engine. The present invention is applicable to those configured as follows.

[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 of the engine in cross section at the center, Figure 3 is a front view of the cylinder bore section, and Figure 4 shows the cylinder block. FIG. 3 is a plan view of a main part shown in partial cross section. 1...Engine, 2...Cylinder block, 2
c... Front end surface, 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 section), 25... Intermediate shaft, S... Space section, 26... Intermediate pulley (first intermediate driving force transmission section), 27... Intermediate sprocket (second intermediate driving force transmission section) Transmission part), 28, 29... Balancer shaft, 28
a, 29a... Balance weight, 31, 32...
... Sprocket (driving force transmission part), 34 ... Timing chain (second power transmission member), 37 ...
water jacket.

Claims (1)

[Claims] 1 A first power transmission member that transmits the rotation of the crankshaft to the camshaft is engaged with the driving force transmission portions provided on the crankshaft and the camshaft, respectively, and the first power transmission member is engaged with the front side of the cylinder block. A first intermediate driving force transmitting part is provided to match the first intermediate driving force transmitting part, and a second intermediate driving force transmitting part is provided concentrically on the cylinder block side of the intermediate shaft of the first intermediate driving force transmitting part, and , a balancer shaft including a balance weight is provided, and a second intermediate driving force transmitting portion of the intermediate shaft and a second driving force transmitting portion of the balancer shaft are provided.
A power transmission member is engaged, and at least a portion of the second power transmission member is disposed along a space recessed below the water jacket at the front end of the cylinder block of the engine. A balancer device for an engine, characterized in that at least a portion of the balancer device is provided so as to pass through a space inside a front end surface of a water jacket.