JP2009162117A - Balancer device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To locate a balancer device at an optimal position by enhancing the flexibility of a layout and reducing the balancer device in weight. <P>SOLUTION: As a primary balancer of a V-six cylinder internal combustion engine, a frontal balancer shaft 11 and a rear balancer shaft 12 which are equipped with weights 14, 24, respectively at two circumferential positions located 180 degrees apart from each other are independently provided back and forth. The frontal balancer shaft 11 is driven by a main timing chain 6 for driving a cam shaft, while the rear balancer shaft 12 is driven by a rear timing chain 32 for driving an oil pump 31. Both the balancer shafts are totally reduced in weight due to the lack of an ineffectual middle shaft as compared one continuous balancer shaft. Further, the flexibility of the layout in the balancer shaft is improved, making it easy to locate the balancer shafts back and forth fully apart from each other and besides at the optimal position near to the center of gravity. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a balancer device for an internal combustion engine that suppresses vibration of a cylinder block by rotating a balancer shaft having an eccentric mass in synchronization with rotation of a crankshaft.

  A balancer shaft having an eccentric mass is rotatably arranged on a part of the cylinder block, and is rotated in synchronization with the rotation of the crankshaft, thereby suppressing primary vibration, secondary vibration, etc. of the cylinder block. Devices are conventionally known.

For example, Patent Document 1 discloses a balancer in which a primary balancer shaft that rotates in the opposite direction at the same rotational speed as that of a crankshaft is disposed at a position between banks in order to suppress the remaining primary vibration in a V-type multi-cylinder internal combustion engine. An apparatus is disclosed. In Patent Document 1, this balancer shaft is driven by a crankshaft via a gear mechanism including an idle gear, but a structure driven by a chain mechanism is also known.
JP 2006-307771 A

  In order to suppress the unbalance before and after the internal combustion engine at the same time, for example, the left and right yaw vibration remaining in the V-type internal combustion engine or the like by the balancer device as described above, eccentricity is provided at two positions before and after the balancer shaft. In addition to providing mass, it is necessary to make the balancer shaft substantially equal to the entire length of the crankshaft so that these eccentric masses are located as far back and forth as possible.

  However, increasing the overall length of the balancer shaft in this way not only causes an increase in the weight of the internal combustion engine, but also increases layout constraints with other parts of the internal combustion engine, and places the balancer shaft in the optimal position. Difficult to do. For example, in Patent Document 1, an attempt is made to arrange the balancer shaft immediately above the crankshaft and in the vicinity of the center of gravity so as to be the optimum position as the primary balancer. The balancer shaft extends through the recess forward and backward, which restricts the layout of intake system components and the like disposed between the banks.

  Therefore, according to the present invention, the balancer shaft is divided into front and rear parts, and each is driven separately. That is, the balancer device for an internal combustion engine according to the present invention has an eccentric mass, and has the same eccentric mass as the first balancer shaft that is rotationally driven by the crankshaft via the first interlocking mechanism, and And a second balancer shaft that is driven to rotate at the same rotational speed in the same direction as the first balancer shaft by a crankshaft via a second interlocking mechanism, and the first balancer shaft is an internal combustion engine. The second balancer shaft is disposed at the front of the internal combustion engine, respectively.

  According to the present invention, each of the first and second balancer shafts is very short, and is lighter than a single continuous balancer shaft. And since there is no useless shaft portion between the first balancer shaft and the second balancer shaft and both can be offset and arranged, the degree of freedom in layout is improved, and other parts Thus, the space can be used more effectively by avoiding the interference, and each eccentric mass can be easily arranged at a more appropriate position for suppressing vibration.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  1 to 3 show an embodiment in which the present invention is configured as a primary balancer of a V-type six-cylinder internal combustion engine having a bank angle of 90 °. FIG. 1 is a front view of the V-type internal combustion engine as viewed from the front of the engine, FIG. 3 is a rear view of the engine as viewed from the rear, and FIG. 2 is a side view of the engine as viewed from the side. FIG. 3 is a configuration explanatory diagram schematically showing only main parts related to the balancer device, omitting structural parts such as cylinder heads.

  As shown in FIG. 1, the crankshaft 1 supported by a cylinder block (not shown) is located at the lower part of the center of the engine as viewed from the front of the engine, and the connecting rods (not shown) of each cylinder in the left and right banks are located here. It is connected. An intake camshaft 2 and an exhaust camshaft 3 are arranged on a cylinder head (not shown) at the top of each bank, and are attached to the front ends of a pair of intake camshafts 2 and 2 located inside the bank. A main timing chain 6 is wound between the intake cam sprockets 4 and 4 and the crank sprocket 5 attached to the front end of the crankshaft 1. As is well known, the intake cam sprocket 4 has a relatively large diameter, and the intake camshaft 2 rotates at half the rotational speed of the crankshaft 1. The exhaust camshaft 3 of each bank includes an exhaust cam sprocket 7 attached to the front end of the exhaust camshaft 3, a second intake cam sprocket 4A overlaid on the intake cam sprocket 4, and a cylinder head side wound around both The intake camshaft 2 is driven via the timing chain 8.

  A front balancer shaft 11 serving as a first balancer shaft and a rear balancer shaft 12 serving as a second balancer shaft are disposed at positions directly above the crankshaft 1 when viewed from the front of the engine. Specifically, it is located at the bottom of the recess between the banks as viewed from the front of the engine, and this position substantially matches the position of the center of gravity when the engine is viewed from the front. As shown in FIG. 2, the front balancer shaft 11 is located at the front end of the engine, and has a sprocket portion 13 and an eccentric mass at each end of the shaft portion having the minimum length necessary for bearing support. Each of the weight portions 14 is provided. The weight portion 14 is provided in a part of the outer peripheral surface of the shaft portion in the circumferential direction, for example, in a range of 180 °. A single bearing 15 that supports the shaft portion is located between the sprocket portion 13 and the weight portion 14. The sprocket portion 13 has the same diameter as the crank sprocket 5 and meshes with the back side (outer peripheral side) of the main timing chain 6 between the pair of intake cam sprockets 4. That is, the main timing chain 6 is engaged with the pair of intake cam sprockets 4, the crank sprocket 5, and the sprocket portion 13 so as to form a large V shape as a whole, and constitutes a first interlocking mechanism. Thereby, the front balancer shaft 11 rotates at the same rotational speed as the crankshaft 1 and in the reverse direction.

  The sprocket portion 13 is divided into a semicircular first region 13A corresponding to the weight portion 14 and a remaining semicircular second region 13B, and the materials and thicknesses of the respective regions are made different. The mass of the first region 13A is relatively large, and this also functions as an eccentric mass together with the weight portion 14. As a result, the eccentric mass is distributed to both sides of the single bearing 15, thereby reducing the load on the bearing 15.

  The rear balancer shaft 12 is located at the rear end of the engine as is apparent from FIG. 2 and is arranged so as to be symmetric with the front balancer shaft 11 in FIG. It is the same as the balancer shaft 11. That is, a sprocket portion 23 and a weight portion 24 serving as an eccentric mass are respectively provided at each end portion of the shaft portion having a minimum length necessary for bearing support, and a single unit that supports the shaft portion. The bearing 25 is located between the sprocket portion 23 and the weight portion 24. The sprocket portion 23 is divided into a semicircle first region 23A corresponding to the weight portion 24 and a remaining semicircle second region 23B, and by making the material, thickness, etc. of each region different, The mass of the first region 23 </ b> A is relatively large and functions as an eccentric mass together with the weight portion 24.

  The rear balancer shaft 12 is driven as a second interlocking mechanism using a rear timing chain 32 for driving an oil pump 31 which is one of auxiliary machines located below the rear part of the internal combustion engine. It is like that. That is, a rear crank sprocket 33 is attached to the rear end portion of the crankshaft 1, and an oil pump sprocket 34 is attached to the rotary shaft end portion of the oil pump 31 heading toward the rear of the engine. At least the rear crank sprocket 33 is It has the same diameter as the sprocket portion 23 of the rear balancer shaft 12. The rear timing chain 32 is wound around a sprocket portion 23 and an oil pump sprocket 34 positioned above and below the rear crank sprocket 33, and the rear crank sprocket 33 is engaged with the rear side (outer peripheral side) thereof. As a result, the rear balancer shaft 12 rotates in the reverse direction at the same rotational speed as the crankshaft 1.

  Therefore, the front balancer shaft 11 and the rear balancer shaft 12 rotate synchronously in the same direction (the opposite direction to the crankshaft 1) and at the same rotational speed (the same rotational speed as the crankshaft 1). Here, the eccentric direction of the eccentric mass of the front balancer shaft 11 and the eccentric direction of the eccentric mass of the rear balancer shaft 12 are different from each other by 180 ° in order to suppress yaw vibration of the internal combustion engine. In this embodiment, the center of rotation of the front balancer shaft 11 and the center of rotation of the rear balancer shaft 12 are aligned on the same straight line, but the positions of the center of gravity and other parts at the front and rear of the internal combustion engine From the above relationship, the respective rotation centers may be offset from each other. Further, the eccentric mass does not necessarily have to be the same size at the two front and rear positions, and may have different sizes for optimization according to the respective positions.

  In the balancer device configured as described above, there is no useless shaft portion between the front balancer shaft 11 and the rear balancer shaft 12, so even if the weight increase due to the sprocket portion 23 and the rear timing chain 32 is taken into consideration. The weight can be reduced as compared with the configuration in which the eccentric mass is provided at both ends of one balancer shaft. In particular, since the front and rear eccentric masses can be arranged sufficiently far away from each other, the eccentric mass necessary for vibration suppression is also reduced, and further weight reduction is possible. In addition, in the above configuration, the rear balancer shaft 12 is driven using a chain mechanism for driving the auxiliary machine (oil pump 31), so that a substantial weight increase due to the driving of the rear balancer shaft 12 is extremely small.

  Further, since the front balancer shaft 11 and the rear balancer shaft 12 can be individually arranged in combination with the absence of a useless shaft portion in the middle, the degree of freedom in layout increases and the useless space is occupied. In addition, the front and rear eccentric masses can be easily arranged at the optimum positions near the front and rear ends of the engine and near the center of gravity.

  Next, FIG. 4 shows a different embodiment of the first interlocking mechanism that drives the front balancer shaft 11. In this embodiment, the chain mechanism for driving the intake camshaft 2 and the exhaust camshaft 3 has a two-stage configuration, and an intermediate sprocket 41 formed by integrating a large-diameter sprocket 41a and a small-diameter sprocket 41b is provided in each bank. The first timing chain 42 is wound around the pair of intermediate sprockets 41 (specifically, the large-diameter sprocket 41a) and the crank sprocket 5. Then, for each bank, the second timing chain 44 is wound around the small sprocket 41 b of the intermediate sprocket 41, the intake cam sprocket 42, and the exhaust cam sprocket 43. The sprocket portion 13 of the front balancer shaft 11 is meshed with the back side (outer peripheral side) of the first timing chain 42 between the pair of intermediate sprockets 41, thereby the front balancer shaft as in the above-described embodiment. 11 is driven.

  FIG. 5 shows a different embodiment of the second interlocking mechanism for driving the rear balancer shaft 12. In this embodiment, an idler sprocket 51 is provided adjacent to the rear balancer shaft 12, and a rear timing chain 32 is wound around the idler sprocket 51, the oil pump sprocket 34 and the rear crank sprocket 33. It has been. The rear balancer shaft 12 includes a gear portion 52 having a tooth portion on the outer periphery instead of the sprocket portion 23 of the above embodiment, and a gear (not shown) provided integrally with the idler sprocket 51. The gear portion 52 meshes with each other. Accordingly, the rotation of the idler sprocket 51 that rotates in the same direction as the crankshaft 1 is transmitted to the rear balancer shaft 12 in the reverse direction through the meshing of the gears. In this case as well, it is preferable that the gear portion 52 has a non-uniform mass distribution as part of the eccentric mass.

  As mentioned above, although the Example which applied this invention as a primary balancer of a V type internal combustion engine was described, this invention is not limited to this, The primary balancer in the various types of internal combustion engines, a secondary balancer, etc. It is possible to apply as Also, the first interlocking mechanism and the second interlocking mechanism can be variously configured appropriately using gears, chains, etc., and may be independent mechanisms that are separate from the drive of the camshaft and auxiliary equipment.

The front view seen from the engine front which shows roughly the composition of the balancer device of the present invention applied to the V type 6 cylinder internal combustion engine. The side view seen from the engine side. The rear view similarly seen from the engine back. The front view seen from the engine front which shows the Example from which the 1st interlocking mechanism differs. The rear view seen from the engine rear which shows the Example from which a 2nd interlocking mechanism differs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Crankshaft 6 ... Main timing chain 11 ... Front balancer shaft 12 ... Rear balancer shaft 13, 23 ... Sprocket part 14, 24 ... Weight part 31 ... Oil pump 32 ... Rear timing chain

Claims (8)

A first balancer shaft having an eccentric mass and being rotationally driven by a crankshaft via a first interlocking mechanism;
A second balancer shaft that also has an eccentric mass and is rotationally driven at the same rotational speed in the same direction as the first balancer shaft by the crankshaft via a second interlocking mechanism;
A balancer device for an internal combustion engine, wherein the first balancer shaft is disposed at a front portion of the internal combustion engine, and the second balancer shaft is disposed at a rear portion of the internal combustion engine.   2. The balancer device for an internal combustion engine according to claim 1, wherein the first and second balancer shafts are rotationally driven at the same rotational speed as that of the crankshaft to constitute a primary balancer.   The balancer device for an internal combustion engine according to claim 1 or 2, wherein the eccentric mass of the first balancer shaft and the eccentric mass of the second balancer shaft are provided in different phases.   The balancer device for an internal combustion engine according to any one of claims 1 to 3, wherein the first and second balancer shafts are arranged in a portion between banks of the V-type internal combustion engine.   5. The balancer for an internal combustion engine according to claim 1, wherein the rotation center of the first balancer shaft and the rotation center of the second balancer shaft are aligned on the same straight line. apparatus.   The balancer device for an internal combustion engine according to any one of claims 1 to 4, wherein the rotation center of the first balancer shaft and the rotation center of the second balancer shaft are offset from each other.   The balancer device for an internal combustion engine according to claim 5 or 6, wherein the first and second balancer shafts are arranged at positions of the center of gravity when the internal combustion engine is viewed from the front or the rear.   The first interlocking mechanism is a camshaft driving chain mechanism provided at the front end of the internal combustion engine, and the second interlocking mechanism is for driving auxiliary equipment provided at the rear end of the internal combustion engine. The balancer device for an internal combustion engine according to claim 1, comprising a chain mechanism.

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