JP5019614B2 - Balancer unit for reciprocating engine - Google Patents

Description

  The present invention relates to a balancer unit for reducing vibration, noise, and the like generated when a piston or the like in a reciprocating engine reciprocates.

  In a reciprocating engine such as an automobile, vibration, noise, and the like are generated by an inertial force or the like due to a reciprocating motion of a piston and a connecting rod connected to the piston. In order to reduce the primary vibration that occurs at the same frequency as the rotation speed of the crankshaft, a counterweight is provided on the crank arm that connects the connecting rod and the crankshaft. In addition, in order to reduce secondary vibration that occurs at a frequency twice that of the crankshaft, the pair of balance shafts having a balance weight is rotated at twice the engine speed as the crankshaft rotates. The driven rotation is performed at

  The pair of balance shafts are rotatably supported by a housing divided into two. And the housing divided | segmented into two is assembled | attached in the state which pinched and supported the pair of balance shafts between the mating surfaces. As such a housing divided into two, for example, in the balancer device of Patent Document 1, an upper balancer housing and a lower balancer housing are disclosed.

  Further, the pair of balance shafts are engaged with each other by gears provided. In order to keep the amount of backlash generated between the gears within a target dimensional tolerance, for example, from a plurality of gears having different OBD (overball diameter) depending on the formation state of the tooth surface pressure angle and the like. A pair of gears is selected in which the amount of backlash is within a predetermined dimensional tolerance. In addition, OBD means the distance between the outermost surfaces of the ball | bowl measured by putting a ball | bowl between adjacent tooth surfaces (tooth root part) in the position where the phase in a gear differs about 180 degrees.

  However, even if an attempt is made to select a pair of gears having different OBDs in order to adjust the amount of backlash, the required OBD gears may not necessarily be selected. Further, according to this selection, the amount of backlash that can be adjusted is limited, and in some cases, the amount of backlash cannot be adjusted. In this case, a defective housing is generated.

Japanese Patent Laid-Open No. 11-325185

  The present invention has been made in view of such conventional problems, and provides a balancer unit that can reliably set the amount of backlash generated between the gears of a pair of balance shafts within a targeted dimensional tolerance. It is what.

The present invention provides a balancer unit that rotatably supports a pair of balance shafts that are driven and rotated by the rotation of a crankshaft of a reciprocating engine.
Each of the pair of balance shafts includes a gear that meshes with each other, a balance weight that forms an eccentric load, an engagement hole of the balance weight, and a shaft portion that is inserted into the engagement hole of the gear. And
The housing includes a pair of bearing portions that rotatably support the shaft portions of the pair of balance shafts, and a cover portion that connects the pair of bearing portions so as to cover the balance weights of the pair of balance shafts. A pair of divided blocks that are divided in such a manner that the pair of bearing portions and the cover portion are divided and the shaft portions of the balance shafts are rotatably supported separately. Formed,
The pair of divided blocks sets a distance between the pair of balance shafts to a predetermined distance by sandwiching a spacer having a predetermined thickness continuously disposed on the pair of bearing portions and the cover portion. It is in the balancer unit for reciprocating engines characterized by being assembled (Claim 1).

The balancer unit of the present invention is devised in the formation state of a housing that rotatably supports a pair of balance shafts so that the distance between the axes of the pair of balance shafts can be arbitrarily set.
Specifically, a pair of division | segmentation blocks which comprise the housing of this invention are formed in the state which supports the shaft part of a pair of balance shaft so that it can each rotate separately. In the present invention, a distance between the pair of balance shafts is set to a predetermined distance by sandwiching a spacer having a predetermined thickness between the mating surfaces of the pair of divided blocks.
Therefore, the amount of backlash in the gears of the pair of balance shafts can be easily set within the targeted dimensional tolerance by appropriately changing the thickness of the spacer.

Further, the thickness of the spacer can be easily set to an arbitrary thickness, and the amount of backlash cannot be adjusted, so that a defective product can be prevented from occurring in the housing.
Therefore, according to the balancer unit of the present invention, the amount of backlash generated between the gears of the pair of balance shafts can be reliably set within a target dimensional tolerance.

A preferred embodiment of the present invention described above will be described.
In the present invention, the balance weight is between between the pair of bearing portions, fitted to the shaft portion, the gear, the end of the shaft portion protruding to the outside between the between the pair of bearing portions (Claim 2).
In this case, the structure of the balancer unit is simple.

Hereinafter, embodiments of a balancer unit for a reciprocating engine according to the present invention will be described with reference to the drawings.
The balancer unit 1 for the reciprocating engine of this example can rotate a pair of balance shafts 4 that rotate following the rotation of the crankshaft 11 of the reciprocating engine to the housing 2 as shown in FIGS. 1, 2, and 4. To support. The pair of balance shafts 4 includes a gear 41 that rotates in mesh with each other, a balance weight 42 that forms an eccentric load, an engagement hole 421 of the balance weight 42, and a shaft portion 43 that is inserted into the engagement hole 411 of the gear 41. Respectively.

  As shown in FIG. 2, the housing 2 is formed by assembling a pair of divided blocks 21 that are divided in a state where the shaft portions 43 of the pair of balance shafts 4 are rotatably supported separately. The pair of divided blocks 21 are assembled by setting a distance between the pair of balance shafts 4 to a predetermined distance by sandwiching a spacer 3 having a predetermined thickness between the mating surfaces 211. FIG. 5 shows a state in which the pair of divided blocks 21 are assembled via the spacer 3.

Hereinafter, the balancer unit 1 for the reciprocating engine of the present example will be described in detail with reference to FIGS.
As shown in FIG. 6, the reciprocating engine 1 of this example is an in-line four-cylinder reciprocating engine, and when the two pistons 13 are located at the top dead center U, the remaining two pistons 13 are at the bottom dead center L. Configured to be located. Each piston 13 is connected to a crank arm 111 provided on the crankshaft 11 via a connecting rod 14. Further, a counterweight 112 is formed on the crank arm 111 on the side opposite to the side where the connecting rod 14 is connected.
As shown in FIG. 1, the balancer unit 1 is attached to the engine by engaging the driven gear 45 with the drive gear 12 and screwing the housing 2 into the cylinder block 5 of the engine.

As shown in FIGS. 1 and 6, the crankshaft 11 is provided with a drive gear (crank gear) 12, and one of the pair of balance shafts 4 is driven by the rotation of the drive gear 12. A rotating driven gear 45 is provided adjacent to the gear 41. The driven gear 45 can be formed integrally with the gear 41, or can be formed separately from the gear 41.
The drive gear 12 and the driven gear 45 of this example are provided at positions corresponding to the crankshaft 11 between the piston 13 positioned on the outermost side of the four pistons 13 and the piston 13 positioned on the inner side thereof.

  Further, the reference pitch circle diameter and the number of teeth of the driven gear 45 are half the reference pitch circle diameter and the number of teeth of the drive gear 12. The gears 41 of the pair of balance shafts 4 have the same reference pitch circle diameter and the same number of teeth. When the crankshaft 11 rotates once, the driven gear 45 and the gear 41 of the pair of balance shafts 4 rotate twice.

As shown in FIG. 1, the balance weight 42 applies a balance force in a direction away from the piston 13 when each piston 13 connected to the crankshaft 11 is at the top dead center U or the bottom dead center L. It is configured.
That is, in this example, as shown in FIG. 6, the first and fourth pistons 13A, D located at both ends of the four cylinders are at the top dead center U, and the remaining second, third pistons 13B, C are at the bottom. When at the dead point L, the balance weight 42 generates a balance force in a direction away from each piston 13. Although not shown, when the first and fourth pistons 13A and 13D are at the bottom dead center L and the second and third pistons 13B and C are at the top dead center U, the balance weight 42 is A balance force is generated in a direction away from each piston 13A-D.

On the other hand, as shown in FIG. 7, when the first to fourth pistons 13 </ b> A to 13 </ b> D are at an intermediate position M between the top dead center U and the bottom dead center L, the balance weight 42 is in a direction approaching each piston 13 </ b> A to D. Generate balance force. Further, when the pair of balance shafts 4 are rotated in the opposite directions, the pair of balance weights 42 forms a positional relationship that is closest to each other and a positional relationship that is most distant from each other.
In this way, the balance force (inertial force) by the balance weight 42 is applied in the direction opposite to the direction of action of the inertia force and the inertia couple generated by the reciprocating motion of the pistons 13A to 13D and the connecting rod 14, and the reciprocating engine 1 Generation of secondary vibration can be reduced.

As shown in FIGS. 2 to 4, the pair of divided blocks 21 of the present example includes a pair of bearing portions 22 that rotatably support the shaft portions 43 of the pair of balance shafts 4, and a pair of cover portions 4 so as to cover the balance shaft 4. The cover part 25 which connects the bearing part 22 is each provided. The balance weight 42 of the pair of balance shafts 4 is fitted to the shaft portion 43 between the pair of bearing portions 22. The gear 41 of the pair of balance shafts 4 is fitted to the end portion of the shaft portion 43 that protrudes outward between the pair of bearing portions 22. One of the pair of balance shafts 4 is provided with a driven gear 45 adjacent to the gear 41 on the outer side between the pair of bearing portions 22.
Each bearing portion 22 is formed with a shaft hole 221 for inserting the shaft portion 43 in a rotatable state, and a metal bush 222 is provided in the shaft hole 221.

  As shown in FIG. 3, the pair of divided blocks 21 are assembled by a plurality of bolts 24 that pass through the spacer 3 with the spacer 3 sandwiched between the mating surfaces 211. Specifically, one divided block 21A and the spacer 3 are formed with through holes 23A through which a plurality of (four in this example) bolts 24 are inserted, and the other divided block 21B has a plurality of through holes 23A. A screw hole 23B for screwing the bolt 24 is formed. Then, a plurality of bolts 24 inserted into the through hole 23A of the one divided block 21A and the through hole 31 of the spacer 3 are screwed into the other divided block 21B, so that the pair of divided pieces is held with the spacer 3 sandwiched therebetween. Block 21 can be assembled.

As shown in FIG. 4, the balance shaft 4 of this example is formed by shrink fitting a balance weight 42 and a gear 41 to the shaft portion 43. Specifically, the balance weight 42 and the gear 41 are heated to expand the engagement holes 421 and 411 thereof, and the shaft portion 43 is replaced with the metal bush of the shaft hole 221 formed in the pair of bearing portions 22. 222 is inserted into the engagement hole 421 of the balance weight 42 disposed between the pair of bearing portions 22 and the engagement hole 411 of the gear 41, and the balance weight 42 and the gear 41 are cooled. Sometimes, these engagement holes 421 and 411 are reduced, and these can be fitted to the shaft portion 43.
Further, when the one balance shaft 4A is formed, the driven gear 45 is also heated to expand the engagement hole 451, and the shaft portion 43 is also inserted into the engagement hole 451. The driven gear 45 is also fitted to the shaft portion 43.

The balancer unit 1 of this example is devised in the formation state of the housing 2 that rotatably supports the pair of balance shafts 4 so that the distance between the axes of the pair of balance shafts 4 can be arbitrarily set.
Specifically, the pair of divided blocks 21 constituting the housing 2 of the present example is formed in a state in which the shaft portions 43 of the pair of balance shafts 4 are separately rotatably supported. In this example, the distance between the axes of the pair of balance shafts 4 is set to a predetermined distance by sandwiching the spacer 3 having a predetermined thickness between the mating surfaces 211 of the pair of divided blocks 21. Yes.
Therefore, by appropriately changing the thickness of the spacer 3, the amount of backlash in the gear 41 of the pair of balance shafts 4 can be easily set within a target dimensional tolerance.

Also in this example, the spacer 3 is used, and the backlash amount is a predetermined dimension from a plurality of gears 41 having different OBD (overball diameter) depending on the formation state of the tooth face pressure angle, etc. A pair of gears 41 within the tolerance can be selected. Here, OBD means the distance between the outermost surfaces of the balls measured by putting the balls between adjacent tooth surfaces (tooth roots) at a position where the phase of the gear 41 differs by about 180 °. .
For example, the balancer unit 1 can be manufactured by preparing the spacers 3 of several thicknesses in advance and using the selection of the spacers 3 and the selection of the pair of gears 41 together.

In addition, the thickness of the spacer 3 can be easily set to an arbitrary thickness, and the amount of backlash cannot be adjusted, so that a defective product can be prevented from occurring in the housing 2.
Therefore, according to the balancer unit 1 of this example, the amount of backlash generated between the gears 41 of the pair of balance shafts 4 can be reliably set within the targeted dimensional tolerance.

Explanatory drawing which shows the balancer unit in the Example seen from the axial direction of the crankshaft. In the Example, it is a figure which shows the balancer unit in the state seen from the axial direction of the balance shaft, and is explanatory drawing which shows the cross section of the arrangement | positioning position of a balance shaft. In the Example, it is a figure which shows the balancer unit in the state seen from the axial direction of the balance shaft, and is explanatory drawing which shows the cross section of the formation position of the bearing part of a division | segmentation block. Explanatory drawing which shows the cross section of the state which looked at the balancer unit in the Example from the direction of the crankshaft. Explanatory drawing which shows the state which assemble | attaches a divided block in an Example. Explanatory drawing which shows the balancer unit attached to the reciprocating engine in the Example seen from the side of the crankshaft. Explanatory drawing which shows the balancer unit attached to the reciprocating engine in the Example seen from the side of the crankshaft.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Balancer unit 11 Crankshaft 12 Drive gear 13 Piston 2 Housing 21 Divided block 211 Matching surface 3 Spacer 4 Balance shaft 41 Gear 42 Balance weight 43 Shaft part 45 Driven gear

Claims (2)

In a balancer unit that is rotatably supported by a housing with a pair of balance shafts that rotate following the rotation of a crankshaft of a reciprocating engine,
Each of the pair of balance shafts includes a gear that meshes with each other, a balance weight that forms an eccentric load, an engagement hole of the balance weight, and a shaft portion that is inserted into the engagement hole of the gear. And
The housing includes a pair of bearing portions that rotatably support the shaft portions of the pair of balance shafts, and a cover portion that connects the pair of bearing portions so as to cover the balance weights of the pair of balance shafts. A pair of divided blocks that are divided in such a manner that the pair of bearing portions and the cover portion are divided and the shaft portions of the balance shafts are rotatably supported separately. Formed,
The pair of divided blocks sets a distance between the pair of balance shafts to a predetermined distance by sandwiching a spacer having a predetermined thickness continuously disposed on the pair of bearing portions and the cover portion. A balancer unit for reciprocating engines characterized by being assembled. According to claim 1, said balance weight, between between the pair of bearing portions, Yes fitted to the shaft portion,
The balancer unit for a reciprocating engine, wherein the gear is fitted to an end portion of the shaft portion protruding outward between the pair of bearing portions.

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