Balancer device for internal combustion engine and its assembly method

Patent metadata

Field	Value
Publication number	US-9618079-B2
Application number	US-201414481416-A
Country	US
Kind code	B2
Filing date	Sep 9, 2014
Priority date	Sep 13, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A balancer device for an internal combustion engine includes upper and lower housings made of aluminum alloy. The upper housing includes a leg part fixed to the engine. The lower housing is coupled to the upper housing by tightening bolts. A pair of balancer shafts are rotatably supported by the upper and lower housings. A positioning pin is disposed at a distal end portion of the leg part for positioning the upper housing with respect to the engine by positional correspondence to a positioning hole of the engine when the tightening bolts are tightened. The leg part is inclined outwardly with respect to a body of the upper housing such that a distal end of the positioning pin is located outside of a proximal end of the leg part with respect to the body of the upper housing when the tightening bolts are loosened.

First claim

What is claimed is:

1. A balancer device for an internal combustion engine, the balancer device comprising:
an upper housing including a plurality of leg parts configured to be fixed to the internal combustion engine, wherein the upper housing is made of aluminum alloy;
a lower housing configured to be coupled to the upper housing by a plurality of tightening bolts, wherein the lower housing is made of aluminum alloy;
a balancer shaft disposed in an internal space formed between the upper housing and the lower housing, and rotatably supported through bearings with respect to the upper housing and the lower housing; and
a positioning pin disposed at a distal end portion of each of the plurality of leg parts;
wherein a distance between distal end portions of leg parts facing each other across the balancing shaft under a second condition that the tightening bolts are loosened becomes narrower than a distance under a first condition that the tightening bolts are tightened to couple the lower housing to the upper housing.

2. The balancer device as claimed in claim 1 , wherein:
the balancer shaft comprises a pair of balancer shafts;
each of the balancer shafts includes a counter weight at an outer periphery thereof;
the upper housing is provided with a first reinforcement rib; and
the first reinforcement rib is located to correspond to the counter weights of the balancer shafts in an axial direction of the balancer shafts, and extend between the balancer shafts in a direction perpendicular to the axial direction of the balancer shafts.

3. The balancer device as claimed in claim 2 , wherein the first reinforcement rib is located to correspond substantially to a central part of the counter weights of the balancer shafts in the axial direction.

4. The balancer device as claimed in claim 3 , wherein the plurality of tightening bolts are located outside of the balancer shafts in the perpendicular direction and in different positions in the axial direction.

5. The balancer device as claimed in claim 2 , wherein the first reinforcement rib is located at a part of the upper housing surrounded by the plurality of leg parts.

6. The balancer device as claimed in claim 2 , wherein at least one of the tightening bolts is arranged between the pair of balancer shafts, and two of the tightening bolts are arranged on corresponding outsides of the balancer shafts.

7. The balancer device as claimed in claim 6 , wherein the upper housing is provided with a second reinforcement rib at an outer end portion thereof in a direction in which the at least one and the two of the tightening bolts are arranged.

8. The balancer device as claimed in claim 7 , wherein the second reinforcement rib is located close to one of the leg parts of the upper housing.

9. The balancer device as claimed in claim 7 , wherein:
a first one of the leg parts is arranged at a first outer end portion of the upper housing in a width direction of the upper housing;
a second one of the leg parts is arranged at a second outer end portion of the upper housing in a width direction of the upper housing, wherein the second outer end portion is opposite to the first outer end portion; and
the second reinforcement rib include a rib part located close to a side portion of the first leg part and a rib part located close to a side portion of the second leg part.

10. The balancer device as claimed in claim 1 , wherein shifting from the second condition to the first condition causes the distance between the distal end portions of the leg parts facing each other across the balancer shaft to be changed by about 10 to 30 micrometers.

11. The balancer device as claimed in claim 1 , wherein:
a lower surface of a cylinder block of the internal combustion engine is provided with a bearing cap bearing a crankshaft; and
the plurality of leg parts are configured to be fixed to portions of the cylinder block without interference with the bearing cap.

12. The balancer device as claimed in claim 1 , wherein:
a first one and a second one of the leg parts are arranged on a first side of a crankshaft;
the first and second leg parts are arranged in different positions in an axial direction of the balancer shaft;
a third one and a fourth one of the leg parts are arranged on a second side of the crankshaft opposite to the first side; and
the third and fourth leg parts are arranged in different positions in the axial direction of the balancer shaft.

13. The balancer device as claimed in claim 1 , wherein:
each leg part includes a cylindrical hollow extending inside thereof in an axial direction thereof; and
the upper housing is configured to be fixed to the internal combustion engine by mounting bolts, wherein each mounting bolt is inserted in the hollow of a corresponding one of the leg parts.

14. A balancer device for an internal combustion engine, the balancer device comprising:
an upper housing including a plurality of leg parts configured to be fixed to the internal combustion engine, wherein the upper housing is made of aluminum alloy;
a lower housing configured to be coupled to a lower part of the upper housing by a plurality of tightening bolts, wherein the lower housing is made of aluminum alloy;
a pair of balancer shafts disposed in an internal space formed between the upper housing and the lower housing, and rotatably supported with respect to the upper housing and the lower housing; and
positioning members each of which is disposed at a distal end portion of a corresponding one of the leg parts, and configured to extend longitudinally of the corresponding leg part, and position the upper housing with respect to the internal combustion engine by positional correspondence to a corresponding positioning part of the internal combustion engine;
wherein
at least a first one of the tightening bolts is disposed between the balancer shafts;
each positioning member is configured to correspond in position to the corresponding positioning part of the internal combustion engine under a first condition that the first tightening bolt is tightened; and
at least one of the positioning members is configured to fail to correspond in position to the corresponding positioning part of the internal combustion engine under a second condition that the first tightening bolt is loosened.

15. An assembly method for a balancer device for an internal combustion engine,
the balancer device including:
an upper housing including a plurality of leg parts configured to be fixed to the internal combustion engine, wherein the upper housing is made of aluminum alloy;
a lower housing configured to be coupled to a lower part of the upper housing by a plurality of tightening bolts, wherein the lower housing is made of aluminum alloy;
a balancer shaft disposed in an internal space formed between the upper housing and the lower housing, and rotatably supported with respect to the upper housing and the lower housing; and
positioning pins each of which is disposed at a distal end portion of a corresponding one of the leg parts, and configured to extend longitudinally of the corresponding leg part, and position the upper housing with respect to the internal combustion engine by positional correspondence to a corresponding positioning hole of the internal combustion engine;

the assembly method comprising:
a first operation of coupling the lower housing to the upper housing by tightening the tightening bolts;
a second operation of drilling a press-fit hole in the distal end portion of each corresponding leg part, after the first operation; and
a third operation of inserting each positioning pin

Assignees

• Hitachi Automotive Systems Ltd

Inventors

• Kitamura Masaharu

Classifications

• F16F15/267 Primary

  characterised by bearing support of balancer shafts; Lubrication arrangements · CPC title

• F16F15/264

  Rotating balancer shafts (F16F15/262 takes precedence) · CPC title

• F02B75/20

  with cylinders all in one line · CPC title

• F16F15/265

  Arrangement of two or more balancer shafts (F16F15/267 takes precedence) · CPC title

• Y10T29/49231

  I.C. [internal combustion] engine making · CPC title