JP2010007484A - Internal combustion engine provided with balance shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine provided with a balance shaft configured in such a manner that its axial movement is regulated while the balance shaft is rotated by a helical gear in an interlocking manner, and easily assembled. <P>SOLUTION: A second bearing 21 interposed between a second support 18 and a second shaft 10 is pressure-fitted to the second shaft at this side of the insertion direction of the balance shaft 6, and an engagement step 20 engaged with the second bearing 21 is formed at the back of the second support 18. A first bearing 17 interposed between a first support 15 and a first shaft 8 is pressure-fitted to the first support on a back side in the insertion direction of the balance shaft 6, and the helical gear 11 is attached to this side of the second shaft 10. The balance shaft 6 pressure-fitted with the helical gear 11 and the second shaft 21 is inserted. The first shaft 8 is inserted into the first bearing 17, and also the second bearing 21 is pressure-fitted to the second support 18. The direction of tilt of teeth of the helical gear 11 is so set that when the internal combustion engine is in a compression stroke, the balance shaft 6 is pushed to the back side in the insertion direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine provided with a balance shaft, and more particularly to an internal combustion engine provided with a balance shaft that can regulate movement in the axial direction and can be easily assembled while being configured to rotate the balance shaft in an interlocking manner with an inclined gear. Is.

  Conventionally, in order to reduce the vertical excitation force of an internal combustion engine, a balance shaft provided with an unbalance portion is arranged in parallel to the crankshaft of the internal combustion engine, and the balance shaft is connected to rotate in conjunction with the crankshaft. In addition, the balance shaft and its drive shaft are interlocked with a bevel gear to reduce vibration and noise caused by gear rattling that occurs in the case of a spur gear. There has been known a technique in which the thrust force generated is received by a bearing hole to which lubricating oil is supplied in order to prevent seizure (see, for example, Patent Document 1).

  Also, in a configuration in which the balance shaft is driven by the inclined gear, the inclined gear is press-fitted through a thrust plate fitted to the shaft end of the balance shaft so as to be relatively rotatable, and the thrust plate is fixed to the wall surface of the cylinder block. And what improved the assembly | attachment property and reduced the number of parts is known (for example, refer patent document 2).

In addition, in the configuration in which the water pump impeller shaft is integrally provided at one end of the balance shaft, a disc spring is interposed between one end surface of the balance shaft and the water pump mounting base, and the biasing force of the disc spring is used. There is also known one in which the balance shaft is urged to the inside of the crankcase to prevent rattling (for example, see Patent Document 3).
JP-A-2-212463 JP 11-101309 A Japanese Utility Model Publication No. 61-49036

  However, in the configuration described in Patent Document 1, even though the seizure due to the thrust force can be prevented, the helical gear is used in the helical gear according to the rotational fluctuation that occurs while the internal combustion engine goes through the intake-compression-combustion-exhaust processes. When the acting thrust force fluctuates, there is a problem that a clearance is generated between the bevel gear and the thrust receiving surface. As a result of this, liquid leakage may occur in the mechanical seal. For example, as described in Patent Document 3, the water pump impeller shaft is integrally provided at one end of the balance shaft. There is a problem of causing leakage.

  Further, in the configuration described in Patent Document 2, the thrust force generated by the inclined gear is received by a thrust plate that engages the inclined gear and the balance shaft so as to restrict the axial movement of the balance shaft. However, since there is a need to provide a clearance between the thrust plate and the thrust plate, there is a risk of sound generation due to fluctuations in thrust force and liquid leakage from the mechanical seal due to shaft movement. is there.

  Further, in the configuration described in Patent Document 3, the thrust force acting on the inclined gear is received by the compression restoring force of the disc spring to prevent the axial movement of the balance shaft. In order to prevent the balance shaft from moving even if a large thrust force is applied, the assembly process takes time and effort due to slip resistance with the disc spring accompanying the rotation of the balance shaft. There is a problem of increased loss.

  The present invention provides an internal combustion engine including a balance shaft that is capable of restricting movement in the axial direction and is easy to assemble while having a configuration in which the balance shaft is interlocked and rotated by an inclined gear in view of the above-described conventional problems. For the purpose.

  An internal combustion engine having a balance shaft according to the present invention includes a balance shaft in which a balance shaft is inserted from one direction in parallel with a crankshaft, and shaft portions at both ends of the balance shaft are rotatably supported by support portions. In the internal combustion engine, the shaft diameter of the first shaft portion on the rear side in the insertion direction of the balance shaft is set smaller than the inner diameter of the second support portion on the front side in the insertion direction of the balance shaft, and the front shaft in the insertion direction of the balance shaft is set. A second bearing capable of receiving a thrust force is press-fitted into the second shaft part, the second bearing is press-fitted into the second support part, and the second bearing is engaged with the back side of the second support part in the balance shaft insertion direction. An engaging step portion is provided, the first shaft portion is rotatably supported by the first support portion on the back side in the insertion direction of the balance shaft, and the balance shaft is supported by the second shaft portion of the balance shaft. An oblique gear that rotationally drives the balance shaft is attached to the front side of the insertion direction, and the inclination direction of the tooth of the oblique gear is set so that the balance shaft is pushed to the back in the insertion direction during the combustion process of the internal combustion engine. It is.

  According to this configuration, generation of rattling noise is prevented by rotating the balance shaft in conjunction with the crankshaft by the inclined gear. In addition, a thrust force is generated by the application of the inclined gear, and the thrust force is transmitted from the inclined gear to the balance shaft and is received by press-fitting and fixing the balance shaft, the second bearing, and the second support portion. The large thrust force acting during the combustion process is received by being engaged with the engagement step portion of the second support portion via the second bearing, so that the axial movement of the balance shaft is reliably regulated, and the thrust is No hitting sound is generated even if there is a fluctuation in force. Even if a mechanical seal is provided integrally with the balance shaft, there is no risk of liquid leakage due to axial movement. In addition, the balance shaft is also assembled by press-fitting the second bearing into the second shaft portion of the balance shaft, attaching a bevel gear to the front side of the second shaft portion, and press-fitting the bevel gear and the second bearing. Assembly can be completed by a simple operation of inserting the balance shaft, inserting the first shaft portion into the first bearing, and press-fitting the second bearing into the second support portion. Thus, although the balance shaft is configured to be interlocked and rotated by the inclined gear, the movement in the axial direction due to the fluctuation of the thrust force accompanying the fluctuation of the rotation can be surely restricted, and the assembly is also easy.

  According to the internal combustion engine provided with the balance shaft of the present invention, generation of rattling noise is prevented by rotating the balance shaft in conjunction with the crankshaft by the inclined gear, and application of the inclined gear. It is possible to reliably control the axial movement of the balance shaft due to the fluctuation of the thrust force, and the assembly is easy even if the thrust force is generated by the fluctuation due to the fluctuation of the rotation. The effect is demonstrated.

  Hereinafter, an embodiment of an internal combustion engine provided with a balance shaft of the present invention will be described with reference to FIGS.

  In FIG. 1, 1 is an internal combustion engine and 2 is the cylinder block. A plurality of cylinders 3 are arranged in parallel in the upper part of the cylinder block 2, and a crankcase part 4 in which a crankshaft 5 is arranged in the lower part. In the internal combustion engine 1 of the present embodiment, a two-cylinder four-cycle internal combustion engine in which two cylinders 3 are arranged in parallel in order to increase the volume of each combustion chamber so that high combustion efficiency can be obtained with a small total displacement. Constitutes an institution. 1 is a connecting rod that connects a piston (not shown) that reciprocates in the cylinder 3 and the crankshaft 5.

  In such a 2-cylinder 4-cycle internal combustion engine, the steps of intake-compression-combustion-exhaust are sequentially performed in one cylinder, and the steps of combustion-exhaust-intake-compression are sequentially performed in the other cylinder. Therefore, the pistons (not shown) in both cylinders reciprocate up and down in the same phase, and a large vertical vibration force is generated. It is essential to dispose.

  Therefore, in the present embodiment, the balance shaft 6 is disposed on one side of the crankshaft 5 in parallel with the crankshaft 5. The balance shaft 6 is configured so as to be inserted and arranged in one axial direction of the balance shaft 6 in a balance shaft arrangement space 7 bulged and formed on one side of the crankcase portion 4.

  As shown in FIG. 2, the balance shaft 6 is located on one side in the radial direction from the axial center between the first shaft portion 8 provided on the back side in the insertion direction and the second shaft portion 10 provided on the front side in the insertion direction. An eccentric portion 9 that is eccentric to the second shaft portion 10, and a gear mounting shaft portion 12 that press-fits a bevel gear 11 and is integrally fixed before the second shaft portion 10, and an impeller mounting shaft 13 that mounts a water pump impeller 14. Are provided integrally.

  In the balance shaft arrangement space 7, a first support portion 15 formed of a cylindrical hole is formed on the end wall 7 a on the back side in the insertion direction of the balance shaft 6. The first support portion 15 has an opening on the outer surface of the end wall 7a, an engagement step portion 16 projecting from an inner end portion of the balance shaft arrangement space 7, and a first bearing 17 is press-fitted and fixed from the outer surface side. Yes. A second support portion 18 formed of a cylindrical hole and a large-diameter gear housing space 19 on the near side are formed on the end wall 7b on the near side of the balance shaft 6 in the insertion direction of the balance shaft 6. An engagement step portion 20 that protrudes toward the inner peripheral side is formed at the inner edge of the balance shaft arrangement space 7 of the second support portion 18, and the second support portion 18 is press-fitted and fixed to the second shaft portion 10. Two bearings 21 are press-fitted and fixed. The impeller mounting shaft 13 passes through a seal mechanism portion 22 disposed on the outer surface of the end wall 7b of the balance shaft arrangement space 7, and a water pump impeller 14 constituting a water pump 23 is attached to the tip of the seal mechanism portion 22. Fastened and fixed at 24.

  An end plate 25 is fastened and fixed to the tip of the first shaft portion 8 on the back side in the insertion direction of the balance shaft 6 by a flat bolt 26, and the outer peripheral portion of the end plate 25 has a very small interval with the inner ring of the first bearing 17. It is held open. A cover 27 is attached to the outer surface of the end wall 7 a so as to cover the end plate 25 and the exposed portion of the first bearing 17.

  In FIG. 3, the shaft diameter of the first shaft portion 8 on the back side in the insertion direction of the balance shaft 6 is d1, the inner diameter of the first support portion 15 is D1, and the shaft of the second shaft portion 10 on the near side in the insertion direction of the balance shaft 6 The dimensional relationship will be described assuming that the diameter is d2 and the inner diameter of the second support portion 18 is D2. The shaft diameter d1 of the first shaft portion 8 is set smaller than the inner diameter D2 of the second support portion 18, and the balance shaft 6 Is configured to be inserted from one direction. Further, the inner diameter D1 of the first support portion 15 is set so as to press-fit and fix the first bearing 17, and the shaft diameter d1 of the first shaft portion 8 can be inserted into the inner periphery of the first bearing 17 in a loosely fitted state. Is set. The inner diameter D2 of the second support portion 18 is set so as to press-fit and fix the second bearing 21, and the shaft diameter d2 of the second shaft portion 10 is also set so as to be press-fit and fixed to the inner periphery of the second bearing 21. .

  The bevel gear 11 attached to the gear attachment shaft portion 12 of the balance shaft 6 is meshed with a drive bevel gear 28 attached to the crankshaft 5 as shown in FIG. The drive bevel gear 28 and the bevel gear 11 have the same diameter and are configured to rotate synchronously in a state where the crankshaft 5 and the balance shaft 6 maintain the phase relationship. The tooth inclination direction of the inclined gear 11 is such that the thrust force generated when the inclined gear 11 is rotated by the drive inclined gear 28 acts in a direction in which the balance shaft 6 is pushed inward in the insertion direction. It is configured. In addition, 11a and 28a are openings for reducing the weight of the gear.

  Next, the assembly process of the balance shaft 6 in the above configuration will be described with reference to FIG. After the second bearing 21 is press-fitted into the second shaft portion 10 on the front side of the balance shaft 6 in the insertion direction, the inclined gear 11 is press-fitted into the gear mounting shaft portion 12 so as to abut on the inner ring of the second bearing 21. On the other hand, the first bearing 17 is press-fitted into the first support portion 15 of the end wall 7 a of the balance shaft arrangement space 7. Next, the bevel gear 11 is attached, the balance shaft 6 into which the second bearing 21 is press-fitted is inserted into the balance shaft arrangement space 7, the first shaft portion 8 is inserted into the first bearing 17 and the second bearing. 21 is press-fitted into the second support portion 18. At that time, the outer ring of the second bearing 21 can be easily and surely press-fitted by pushing the outer ring of the second bearing 21 through the weight reducing opening 11 a provided in the inclined gear 11.

  Thereafter, the end plate 25 is fixed to the end surface of the first shaft portion 8, the cover 28 is attached to cover the rotating portion, the seal mechanism portion 22 is externally fitted to the impeller mounting shaft 13, and the water is attached to the tip portion. The assembly of the balance shaft 6 is completed by assembling the water pump 23 with the pump impeller 14 mounted and fixed.

  According to the above configuration, the balance shaft 6 is rotated in conjunction with the crankshaft 5 via the bevel gear 11 and the drive bevel gear 28. Occurrence can be prevented. In the two-cylinder internal combustion engine 1 of the present embodiment, (intake + combustion) − (compression + exhaust) − (combustion + intake) − in both cylinders 3 and 3 while the crankshaft 5 rotates twice. (Exhaust + compression) steps are performed, and during the rotation of the crankshaft 5, rotational fluctuation occurs in the phase including the combustion step and the phase including the compression step, and the crankshaft 5 is balanced. Since the inclined gears 28 and 11 are applied to interlock the shaft 6 as described above, a thrust force is generated in the inclined gear 11 and the thrust force greatly fluctuates with the rotation fluctuation. become. That is, a large thrust force is generated in one direction in the phase including the combustion process, and a relatively small thrust force (approximately 1/10) in the reverse direction is generated in the phase including the compression process. However, since the thrust force generated in the phase including the combustion process acts in the direction in which the balance shaft 6 is pushed inward, the inclination direction of the teeth of the inclined gear 11 is set, so that a large thrust force in one direction Is transmitted from the bevel gear 11 to the balance shaft 6 and is engaged from the balance shaft 6 via the second bearing 21 (specifically, its inner ring, bearing ball, outer ring) with the engagement step 20 of the second support 18. Since the bevel gear 11 and the inner ring of the second bearing 21 are in contact with each other, the engaging step portion of the second support portion 18 is directly connected to the bevel gear 11 via the second bearing 21. 20, since a small thrust force in the opposite direction is sufficiently received by press-fitting and fixing the balance shaft 6, the second bearing 21, and the second support portion 18, the axial center of the balance shaft 6 is received. Direction movement Indeed it is possible to regulate not the tapping sound is generated, and it is possible to ensure the high sealing performance to eliminate the cause of liquid leakage from the seal mechanism 22.

  Moreover, the assembly of the balance shaft 6 is also performed by press-fitting the second bearing 21 into the second shaft portion 10 of the balance shaft 6 and press-fitting the first bearing 17 into the first support portion 15 as described above. The bevel gear 11 is mounted on the gear mounting shaft portion 12 on the near side of the gear 10, and the balance shaft 6 into which the bevel gear 11 and the second bearing 21 are press-fitted is inserted into the balance shaft arrangement space 7, so that the first shaft portion 8 can be inserted into the first bearing 17 and the second bearing 21 can be press-fitted into the second support portion 18 to complete the assembly.

  Thus, in the internal combustion engine 1 provided with the balance shaft 6, the axial movement due to the fluctuation of the thrust force due to the fluctuation of the rotation is surely restricted while the balance shaft 6 is configured to rotate in conjunction with the inclined gear 11. And the effect of being easy to assemble can be achieved.

  In the above embodiment, an example in which the first bearing 17 is also constituted by a ball bearing has been shown. However, since only the first shaft portion 8 is inserted and supported rotatably, a sliding bearing such as a metal bearing is provided. May be applied. The second bearing 21 is not limited to a ball bearing, and may be a thrust bearing that can receive a force acting on the balance shaft 6 in the axial direction, such as a conical roller bearing.

  Furthermore, in the illustrated example of the above-described embodiment, the example in which the inclined gear 11 and the inner ring of the second bearing 21 are in contact with each other is shown, but there is a gap between the inclined gear 11 and the inner ring of the second bearing 21. The slip gear 11 and the inner ring of the second bearing 21 may come into contact with each other when slippage occurs in the press-fitting between the balance shaft 6 and the second bearing 21.

  The internal combustion engine having the balance shaft of the present invention is configured to rotate the balance shaft in conjunction with the crankshaft by the inclined gear, but the balance shaft is axially driven by the thrust force generated by the application of the inclined gear. Therefore, it can be suitably used for various internal combustion engines equipped with a balance shaft, particularly for internal combustion engines with less total displacement and less than four cylinders.

1 is a partial cross-sectional side view of an embodiment of an internal combustion engine provided with a balance shaft according to the present invention. The longitudinal section front view of the balance shaft arrangement part of the embodiment. The longitudinal section front view of the assembly | attachment process in the balance shaft arrangement | positioning part of the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 5 Crankshaft 6 Balance shaft 8 1st shaft part 10 2nd shaft part 11 Bevel gear 15 1st support part 17 1st bearing 18 2nd support part 20 Engagement step part 21 2nd bearing

Claims (1)

In the internal combustion engine provided with a balance shaft in which the balance shaft is inserted in parallel with the crankshaft from one direction and the shaft portions at both ends of the balance shaft are rotatably supported by the support portions, respectively.
The shaft diameter of the first shaft portion on the back side in the insertion direction of the balance shaft is set smaller than the inner diameter of the second support portion on the near side in the insertion direction of the balance shaft,
A second bearing capable of receiving a thrust force is press-fitted into the second shaft portion on the front side in the balance shaft insertion direction, the second bearing is press-fitted into the second support portion, and the balance shaft insertion direction of the second support portion An engagement step portion for engaging the second bearing on the back side is provided,
The first shaft portion is rotatably supported by the first support portion on the back side in the insertion direction of the balance shaft,
A bevel gear that rotationally drives the balance shaft is attached to the front side of the balance shaft in the insertion direction of the balance shaft from the second shaft portion of the balance shaft.
An internal combustion engine having a balance shaft, wherein the inclination direction of the teeth of the inclined gear is set so that the balance shaft is pushed to the back in the insertion direction during the combustion process of the internal combustion engine.

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