CN210978375U

CN210978375U - Balance shaft assembly

Info

Publication number: CN210978375U
Application number: CN201921693607.7U
Authority: CN
Inventors: 安在鸿; 徐皓中
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-09-16
Filing date: 2019-10-11
Publication date: 2020-07-10
Anticipated expiration: 2029-10-11
Also published as: KR102244217B1; KR20210032061A

Abstract

The utility model relates to a set up in the balanced axle subassembly that is used for reducing the vibration of engine such as vehicle. The utility model discloses a balanced axle subassembly includes: a first shaft having one or more counterweights; a second shaft provided in parallel with the first shaft and having one or more counterweights; a first gear provided at one end of the first shaft and rotating in conjunction with a crankshaft of an engine; a second gear provided at one end of the second shaft and screwed with the first gear to rotate; an upper housing surrounding upper sides of the first shaft and the second shaft; and a lower housing coupled to the upper housing and rotatably supporting the first shaft and the second shaft, wherein the first shaft and the first gear or the second shaft and the second gear are integrally formed. According to the utility model has the advantages of firm and practice thrift manufacturing cost.

Description

Balance shaft assembly

Technical Field

The present invention relates to a balance shaft, and more particularly, to a balance shaft assembly (balance shaft assembly) provided in a vehicle or the like for reducing vibration of an engine.

Background

In general, a vehicle such as an automobile obtains power from an engine to drive tires, thereby realizing running.

In such a vehicle, it is necessary to reduce vibration generated from the engine for the purpose of ride comfort or prevention of other vibration. That is, the crankshaft of the engine should rotate smoothly without vibration, but the center of the crank journal and the center of the crank pin are eccentric, and thus balance cannot be maintained during rotation.

Thus, the crank arm on the opposite side of the crankpin is provided with a balance Weight (or Counter Weight) to achieve balance during rotation.

In this way, the balance of the crankshaft itself of the engine can be maintained to some extent, and the vibration of such an engine exists in various sizes depending on the arrangement or number of cylinders.

The balance weights (or counter weights) are linked with the crank arms and rotate in opposite directions, thereby damping the vibration generated when the crank arms rotate.

Therefore, in addition to the balance weight (or the counter weight), a gear is provided in the balance shaft so that the balance shaft is rotated in a manner corresponding to the rotation of the crank arm.

However, in the conventional art, gears for transmitting power to the balance shaft are separately manufactured and coupled to each other. Therefore, in such a prior art, a separate structure for coupling the gears is required, and problems may be caused because the coupling of the separately manufactured gear and the shaft may be free or loose with the long-term operation.

As described above, the conventional method of separately manufacturing and assembling the shaft including the block and the gear has a problem that the overall precision of the product is lowered due to tolerance accumulation or the like occurring in the assembly process when the product is manufactured. Therefore, when the product is driven after the engine is installed, there occurs a case where the maximum efficiency cannot be exhibited or the product is damaged by the driving of 3000RPM or more.

In the conventional structure, a housing is assembled to an engine cylinder block, using the upper and lower portions of a mass balance shaft (mass balance shaft) that is separately manufactured. Therefore, there is a problem that fuel efficiency may be lowered due to the weight of the upper and lower cases.

[ Prior art documents ]

Patent documents: korean registered patent No. 10-1242273

SUMMERY OF THE UTILITY MODEL

Problem to be solved by the utility model

Therefore, an object of the present invention is to provide a balance shaft assembly in which a shaft and a gear are integrally formed to solve the problems of the prior art as described above.

Another object of the present invention is to provide a balance shaft assembly, which has a housing that only surrounds the upper and lower rotating portions of the shaft gear, thereby achieving an overall lightweight effect.

Means for solving the problems

According to the features of the present invention for achieving the object as described above, the balance shaft assembly of the present invention is characterized by comprising: a first shaft 120 having one or more counterweights M', M "; a second shaft 220 arranged in parallel with the first shaft 120 and having one or more counterweights M', M "; a first gear 110 provided at one end of the first shaft 120 and rotating in conjunction with a crankshaft of an engine; a second gear 210 which is provided at one end of the second shaft 220 and is screwed with the first gear 110 to rotate; an upper housing 300 surrounding upper sides of the first shaft 120 and the second shaft 220; and a lower housing 400 coupled to the upper housing 300 and rotatably supporting the first shaft 120 and the second shaft 220, wherein the first shaft 120 and the first gear 110 or the second shaft 220 and the second gear 210 are integrally formed.

The utility model is characterized in that, still be equipped with at above-mentioned upper portion shell 300: one or more through holes 310 that penetrate vertically; and a transmission gear 320 receiving the rotational power of the engine to rotate the first gear 110.

The utility model is characterized in that, above-mentioned lower part shell 400 includes: a left housing 400' supporting left ends of the first and

second shafts

120 and 220; and a right housing 400 'supporting right side ends of the first and

second shafts

120 and 220, the left and right housings 400' and 400 "being spaced apart and combined with the upper housing 300.

The present invention is characterized in that left and right ends of the first and

second shafts

120 and 220 are respectively formed with left and

right journals

130 and 230 and

right journals

140 and 240, the left housing 400' respectively supports the

left journals

130 and 230, and the right housing 400 ″ respectively supports the

right journals

140 and 240.

The utility model is characterized in that a lower cap 600 is arranged on one side of the lower shell 400, the front and back openings of the lower cap 600 are arranged on the side of the lower cap 600, and the placing groove 610 is formed by respectively sinking to the lower side in a mode that one ends of the first shaft 120 and the second shaft 220 are protruded.

Effect of the utility model

The utility model discloses a balanced axle subassembly has following effect.

First, in the present invention, the first shaft gear and the second shaft gear are respectively formed as one body. I.e. the first shaft and the first gear or the second shaft and the second gear are formed in one piece. Therefore, compared with the case that the shaft and the gear are separately formed to realize the assembly, the operation required for the assembly is not required, so that the production efficiency can be improved, the tolerance generated during the assembly can be eliminated to realize high precision, and the whole rigidity is improved.

In the present invention, the first shaft gear and the second shaft gear are formed of a material such as ductile cast iron (FCD 700). Therefore, the surface hardness required for driving the crankshaft is 250-300 HB, and the process of carburizing or high-frequency heat treatment is not needed like the conventional product. Therefore, there is an advantage in that the heat treatment process is eliminated to improve the efficiency of the manufacturing process.

In addition, the present invention is additionally provided with a transmission gear as an idle gear (idle gear) and engaged with the crank gear. Therefore, the balance shaft assembly of the present invention can be separated from the cylinder block of the engine by a predetermined distance, and therefore, there is an advantage that it is possible to prevent the occurrence of a risk such as interference due to the approach of the engine.

Furthermore, the unnecessary part of the housing surrounding the shaft gear is removed in the present invention. That is, a through hole penetrating vertically is formed in the upper casing, and the lower casing is separated into 2 casings and supported only around the bearing (journal) portion of the shaft gear. Therefore, there is an effect of greatly reducing the weight (when compared with the same size product, the weight is reduced from 8kg to 5.5kg) as compared with the existing upper and lower cases.

Drawings

Fig. 1 is a perspective view showing the structure of a preferred embodiment of the balance shaft assembly of the present invention.

Fig. 2 is an exploded perspective view showing a detailed structure of the balance shaft assembly of the present invention.

Fig. 3 is a perspective view showing the structure of the first shaft gear constituting the embodiment of the present invention.

Fig. 4 is a perspective view showing the structure of the second shaft gear constituting the embodiment of the present invention.

Fig. 5 is a lower perspective view showing the structure of an upper housing constituting an embodiment of the present invention.

Description of the reference numerals：

100: first shaft gear 110: first gear

120: first shaft 130: left side 1 st journal

140: right side 1 st journal portion 200: second shaft gear

210: second gear 220: second shaft

230: left side 2 nd journal portion 240: right 2 nd journal

300: the upper housing 310: through hole

320: the transmission gear 330: left side 1 st shaft groove

332: left side 2 nd axial groove 340: right side 1 st shaft groove

342: right 2 nd axial slot 350: fastening mechanism

400: lower housing 410: left 1 st shaft support

412: left 2 nd shaft support part 420: right side 1 st shaft support part

422: right 2 nd shaft support 500: upper bushing

510: the lower bushing 600: lower cap

M': internal counterweight M': external counterweight

O: oil flow path

Detailed Description

Hereinafter, the balance shaft assembly of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 to 5 show the structure of an embodiment of the balance shaft assembly (draft assembly) according to the present invention. That is, fig. 1 and 2 show a perspective view and an exploded perspective view of the balance shaft assembly of the present invention, fig. 3 and 4 show a perspective view of the structures of the first shaft gear and the second shaft gear constituting the balance shaft assembly of the present invention, respectively, and fig. 5 is a view showing a structure of an upper housing constituting the balance shaft assembly of the present invention in a perspective view from a lower portion.

As shown in these drawings, the balance shaft assembly of the present invention includes, for example, the following structures: a first shaft gear 100 and a second shaft gear 200 which receive rotation of a crankshaft of the engine and rotate; and an upper housing 300 and a lower housing 400 which vertically surround the first shaft gear 100 and the second shaft gear 200 to support the first shaft gear 100 and the second shaft gear 200.

The first shaft gear 100 includes, for example, the following structure: a first gear 110 that receives rotation of a crankshaft that rotates based on power of an engine; and a first shaft 120 that serves as a rotation center of the first gear 110.

As shown in the drawing, the first shaft 120 is formed in a cylindrical shape having a predetermined length along the left and right sides, and the first gear 110 is integrally formed at the right side end of the first shaft 120. The first gear 110 is integrally formed with the first shaft 120 at the same time. That is, the first shaft 120 is formed after forming or machining the left portion of the first shaft 120 from a single raw material.

As described above, when the first gear 110 and the first shaft 120 are integrally formed by casting or the like, the first gear 110 and the first shaft 120 are more robust than the case where they are separately formed and assembled.

The first shaft 120 is provided with one or more weights (weights) M', M "called mass. That is, an inner weight M' is formed at the center of the first shaft 120, and an outer weight M ″ is formed at the left end of the first shaft 120.

A left 1 st journal portion 130 is formed between the inner weight M 'and the outer weight M ″, and a right 1 st journal portion 140 is formed on the right side of the inner weight M'. The left 1 st journal portion 130 and the right 1 st journal portion 140 are rotatably supported by a left 1 st axle supporting portion 410 of the left housing 400' and a right 1 st axle supporting portion 420 of the right housing 400 ″ to be described below, respectively.

As shown in the drawing, the inner weight M' and the outer weight M ″ are formed only on one side (lower side) of the first shaft 120 to have a semicircular shape. This is to receive a force in a direction opposite to a force generated when a crankshaft (not shown) of the engine rotates, and to cancel out vibration caused by rotation of the crankshaft.

The first shaft gear 100 having the above-described structure is formed into a rough shape by casting (injection molding) or the like at a time, and then the left 1 st journal portion 130, the right 1 st journal portion 140, and the like are machined by cutting, and then the thread forming the first gear 110 is formed.

The first gear 110 is engaged with a second gear 210 and a transmission gear 320, which will be described below. Therefore, the first gear 110, the second gear 210, and the transmission gear 320 have threads formed on their outer peripheral surfaces so as to be engaged with each other.

The width (thickness) of the first gear 110 is larger than the width (thickness) of the second gear 210 or the transmission gear 320. That is, as shown in the drawing, the second gear 210 and the transmission gear 320 are simultaneously engaged with the first gear 110 to rotate, and therefore, it is preferable that the gear width (thickness) of the first gear 110 is formed to be wide.

The second shaft gear 200 has a shape corresponding to the first shaft gear 100 as a whole, and is spaced apart from each other at a predetermined interval in parallel in the front-rear direction, and the second shaft gear 200 includes, for example, the following: a second gear 210 that rotates in conjunction with the first gear 110; and a second shaft 220 which serves as a rotation center of the second gear 210.

Preferably, the second shaft 220 has a length in the left-right direction corresponding to the first shaft 120, and has a cylindrical shape. And, a second gear 210 is integrally formed at a right side end of such a second shaft 220.

Preferably, the second gear 210 is integrally formed with the second shaft 220 at the same time. That is, it is preferable that the second shaft 220 is formed or machined after the left portion of the second shaft 220 is formed or machined from one raw material.

As described above, when the second gear 210 and the second shaft 220 are integrally formed by casting (molding) or injection molding, the second gear 210 and the second shaft 220 are more firmly assembled than when they are separately formed.

The second shaft 220 also has one or more counterweights M', M ″ as in the first shaft 120. That is, an inner weight M' is formed at the center of the second shaft 220, and an outer weight M ″ is formed at the left end of the second shaft 220.

A left 2 nd journal portion 230 is formed between the inner weight M 'and the outer weight M ″, and a right 2 nd journal portion 240 is formed at the right side of the inner weight M'. The left 2 nd journal portion 230 and the right 2 nd journal portion 240 are rotatably supported by a left 2 nd journal supporting portion 412 of the left housing 400' and a right 2 nd journal supporting portion 422 of the right housing 400 ″, which will be described below, respectively.

As shown in the drawing, the inner weight M' and the outer weight M ″ are formed only on one side (lower side) of the second shaft 220 to have a semicircular shape. This is to receive a force in a direction opposite to a force generated when a crankshaft (not shown) of the engine rotates, and to cancel out vibration caused by rotation of the crankshaft.

The second shaft gear 200 having the above-described structure is formed in a rough shape by casting (injection molding) or the like at a time, and then the left 2 nd journal portion 230, the right 2 nd journal portion 240, and the like are machined by cutting, and then the thread forming the second gear 210 is formed.

The second gear 210 is engaged with the first gear 110 to rotate. Therefore, it is preferable that gears (threads) having the same gear specification are formed on the outer circumferential surfaces of the first gear 110 and the second gear 210, respectively, so as to be capable of gear coupling with each other.

Further, it is preferable that the first shaft gear 100 and the second shaft gear 200 be made of a material having a rigidity to such an extent that no additional carburizing or high-frequency heat treatment is required. That is, the first shaft gear 100 and the second shaft gear 200 are preferably made of a material satisfying the condition of the surface hardness of 250 to 300HB, and are preferably made of a material such as ductile iron (FCD700), that is, a material not requiring post-treatment such as heat treatment.

Of course, when the entire material of the first and second shaft gears 100 and 200 cannot be made of a material such as ductile iron (FCD700), it is preferable that at least the material of the first and

second gears

110 and 210 is made of a material having high rigidity such as ductile iron (FCD 700).

The upper housing 300 surrounds the upper sides of the first shaft 120 and the second shaft 220.

The upper case 300 is further provided with: one or more through holes 310 that vertically penetrate therethrough; and a transmission gear 320 for receiving the rotational power of the engine to rotate the first gear 110.

More specifically, the upper housing 300 is formed to entirely surround the upper portions of the first shaft gear 100 and the second shaft gear 200, and is preferably formed in a square plate shape having a predetermined thickness along the upper and lower sides.

In the upper case 300, 2 through holes 310 are formed to penetrate vertically. As shown in the drawing, the through-holes 310 are preferably formed in the front and rear of the upper case 300, respectively, and have a square cross section.

The through hole 310 is formed because the weight of the upper housing 300 is reduced and oil or the like smoothly flows up and down the upper housing 300.

The transmission gear 320 is rotatably installed at the right side surface of the upper housing 300. Therefore, a shaft groove 322 is formed at a right side end of the upper housing 300, and the transmission gear 320 is rotatably mounted to the shaft groove 322.

The transmission gear 320 rotates around a gear shaft 322' and is formed of an idle gear. Therefore, the transmission gear 320 is mounted to be engaged with a crank gear (not shown) and the first shaft gear 100 and idles (idle rotation).

The first shaft gear 100 and the second shaft gear 200 are rotatably mounted on the bottom surface of the upper housing 300.

Therefore, a left 1 st axial groove 330 and a left 2 nd axial groove 332 are formed in the bottom surface of the upper housing 300, and the left 1 st axial groove 330 and the left 2 nd axial groove 332 accommodate the left 1 st journal portion 130 and the left 2 nd journal portion 230, respectively. That is, as shown in the drawing, the left 1 st axial groove 330 and the left 2 nd axial groove 332, which receive the left 1 st axial neck portion 130 and the left 2 nd axial neck portion 230, respectively, are formed in the bottom surface of the left side end of the upper housing 300 to be recessed upward, and such left 1 st axial groove 330 and left 2 nd axial groove 332 preferably have a semicircular shape corresponding to the upper surfaces of the left 1 st axial neck portion 130 and the left 2 nd axial neck portion 230.

Upper bushings (bush)500 are respectively provided between the left 1 st journal portion 130 and the left 1 st axial groove 330, and between the left 2 nd journal portion 230 and the left 2 nd axial groove 332.

Further, a right-side end of the bottom surface of the upper housing 300 is formed with a right-side 1 st axial groove 340 and a right-side 2 nd axial groove 342, respectively, and the right-side 1 st journal portion 140 and the right-side 2 nd journal portion 240 are accommodated in the right-side 1 st axial groove 340 and the right-side 2 nd axial groove 342, respectively. That is, as shown in the drawing, the right 1 st and 2 nd

axial grooves

340 and 342 for receiving the right 1 st and 2

nd journal parts

140 and 240, respectively, are formed to be recessed upward on the bottom surface of the right side end of the upper housing 300, and such right 1 st and 2 nd

axial grooves

340 and 342 preferably have a semicircular shape corresponding to the upper surfaces of the right 1 st and 2

nd journal parts

140 and 240.

Upper bushings 500 are also provided between the right side 1 st journal portion 140 and the right side 1 st axial groove 340, and between the right side 2 nd journal portion 240 and the right side 2 nd axial groove 342, respectively.

As shown in the drawing, oil flow paths O are formed in the left 1 st and 2 nd

axial grooves

330 and 332, and the right 1 st and 2 nd

axial grooves

340 and 342, and oil flows into and fills the oil flow paths O.

On the other hand, a plurality of fastening holes 352 are formed at four corners of the upper case 300 so as to penetrate vertically, the fastening holes 352 receive fastening mechanisms 350, and the fastening mechanisms 350 couple the upper case 300 and the lower case 400 to each other.

The lower housing 400 is combined with the upper housing 300 by a fastening mechanism 350. As the fastening mechanism 350, a bolt and a nut or various mechanisms other than these may be used.

The lower housing 400 functions to support the first shaft 120 and the second shaft 220 so that the first shaft 120 and the second shaft 220 can rotate.

The lower case 400 includes: a left housing 400' supporting left side ends of the first and

second shafts

120 and 220; and a right housing 400' supporting right side ends of the first and

second shafts

120 and 220.

Preferably, the left and right housings 400' and 400 ″ are coupled to the upper housing 300 in a spaced-apart manner by a fastening mechanism 350, and have the same or corresponding shapes.

As described above, the left and right ends of the first and

second shafts

120 and 220 are respectively formed with the left and

right journals

130 and 230 and 140 and 240, the left housing 400' supports the

left journals

130 and 230, and the right housing 400 ″ supports the

right journals

140 and 240.

As shown in the drawing, the left 1 st and 2 nd

axial supports

410 and 412 are formed to be recessed downward in the left housing 400'. That is, the left housing 400' is formed to have a predetermined length along the front and rear sides, the left 1 st shaft support part 410 is recessed downward to have a semicircular shape in the front half of the left housing 400', and the left 2 nd shaft support part 412 is recessed downward to have a semicircular shape in the rear half of the left housing 400 '.

The left 1 st axis support part 410 supports a lower portion of the left 1 st axis neck part 130, and the left 2 nd axis support part 412 supports the left 2 nd axis neck part 230. Therefore, it is preferable that the upper surfaces of the left 1 st and 2

nd shaft supporters

410 and 412 have a shape corresponding to the bottom surfaces of the left 1 st and 2

nd journal parts

130 and 230.

Further, lower bushings 510 are provided between the left 1 st shaft support part 410 and the left 1 st journal part 130, and between the left 2 nd shaft support part 412 and the left 2 nd journal part 230, respectively.

As shown in the drawing, the right 1 st and 2 nd axial supports 420 and 422 are formed to be recessed downward in the right housing 400 ″. That is, the right housing 400 ″ is formed to have a predetermined length in the front-rear direction, as in the left housing 400', and the right 1 st shaft supporting part 420 is recessed downward to have a semicircular shape in the front half of the right housing 400 ″ and the right 2 nd shaft supporting part 422 is recessed downward to have a semicircular shape in the rear half of the right housing 400 ″.

The right 1 st shaft support part 420 supports a lower portion of the right 1 st journal part 140, and the right 2 nd shaft support part 422 supports the right 2 nd journal part 240. Therefore, it is preferable that the upper surfaces of the right 1 st and 2 nd shaft supports 420 and 422 have a shape corresponding to the bottom surfaces of the right 1 st and 2

nd journal parts

140 and 240.

Also, it is preferable that lower bushings 510 are respectively provided between the right 1 st shaft support part 420 and the right 1 st journal part 140, and between the right 2 nd shaft support part 422 and the right 2 nd journal part 240.

On the other hand, as shown in the drawing, oil flow paths O, into which oil flows and is filled, are formed in the left 1 st and 2 nd shaft supports 410 and 412 and the right 1 st and 2 nd shaft supports 420 and 422.

As described above, the lower housing 400 is configured to support only the bearing (journal) portions of the first shaft gear 100 and the second shaft gear 200. That is, the upper housing 300 and the lower housing 400 do not surround the entire first shaft gear 100 and the second shaft gear 200 in the up-down direction, but surround only the upper and lower portions of the bearing (journal) portion.

Therefore, compared to the

case

300, 400 surrounding the entire first shaft gear 100 and second shaft gear 200, it is effective to reduce the weight.

A lower cap 600 having a front and rear opening is further provided at one side (lower side) of the lower housing 400. The lower case 400 is opened at the front and rear sides thereof to reduce the weight and to make the flow of oil and the like more smooth at the front and rear sides.

Preferably, the lower cap 600 has a shape in which a bottom surface and left and right side surfaces of a square shape are formed as a whole, and is formed to surround the lower sides and the side surfaces of the upper and

lower cases

300 and 400, the first shaft gear 100 and the second shaft gear 200, and the like.

The placement grooves 610 are formed by being recessed downward such that one ends of the first shaft 120 and the second shaft 220 can protrude from the side surfaces of the lower cap 600.

A cover 620 protruding upward to surround a lower gap between the left and right cases 400' and 400 ″ is formed in front and rear of the bottom surface of the lower cap 600.

The cover 620 is formed to have elasticity, and may be in contact with the lower end of the upper housing 300 to prevent oil from scattering therein.

Hereinafter, the operation of the balance shaft assembly of the present invention having the above-described structure is observed with reference to the drawings.

First, as shown in fig. 3 and 4, the first shaft gear 100 and the second shaft gear 200 are formed into a rough shape by casting (injection) or injection molding, and then the rough shape is formed into a specific shape by cutting. That is, the first shaft gear 100 and the second shaft gear 200, in which the weights M', M ″ and the

gears

110 and 210 are formed on the first shaft 120 and the second shaft 220, respectively, are first manufactured by casting (casting) or other molding methods. Then, the first shaft gear 100 and the second shaft gear 200 are cut in a fixed state, and first, the

journal portions

130, 140, 230, 240 and the like are machined with precise numerical values by cutting, and finally, the threads of the

gears

110, 210 are formed.

The transmission gear 320 is coupled to the right side end of the upper housing 300 after being separately formed, and in this state, the upper housing 300 and the lower housing 400 vertically surround the first shaft gear 100 and the second shaft gear 200 and are coupled by a fastening mechanism 350.

When the lower cap 600 is coupled to the lower side, the state shown in fig. 1 is formed, and the assembly is completed. At this time, the transmission gear 320 is gear-coupled to the first shaft 120, and the first shaft 120 is gear-coupled to the second shaft 220. Therefore, when the transmission gear 320 rotates, the first shaft 120 and the second shaft 220 also rotate by receiving the rotational force.

The balance shaft assembly of the present invention completed by such a process is used in a manner assembled to the underside of the crankshaft of the engine. The weights M ', M "of the first shaft gear 100 and the weights M', M" of the second shaft gear 200 are assembled so as to be positioned in the same direction (for example, lower side).

If the balance shaft assembly of the present invention is installed in an engine, the transmission gear 320 is engaged with a gear (not shown) of a crankshaft. Therefore, when the engine of the vehicle or the like is operated, the first shaft gear 100 and the second shaft gear 200 rotate in association with each other in accordance with the rotation of the crankshaft, and therefore, the counterweights M', M ″ act in the opposite direction to the force direction of the crankshaft of the engine, thereby canceling the vibration of the engine.

The scope of the present invention is not limited to the above-described exemplary embodiments, and various other modifications based on the present invention can be implemented by those skilled in the art within the technical scope of the present invention as described above.

Claims

1. A balance shaft assembly, comprising:

a first shaft (120) having one or more counterweights (M ', M');

a second shaft (220) which is provided in parallel with the first shaft (120) and has one or more counterweights (M ', M');

a first gear (110) which is provided at one end of the first shaft (120) and rotates in conjunction with a crankshaft of an engine;

a second gear (210) that is provided at one end of the second shaft (220), and that rotates in threaded engagement with the first gear (110);

an upper housing (300) that surrounds the upper sides of the first shaft (120) and the second shaft (220); and

a lower housing (400) coupled to the upper housing (300) and supporting the first shaft (120) and the second shaft (220) so that the first shaft (120) and the second shaft (220) can rotate,

wherein the first shaft (120) and the first gear (110) or the second shaft (220) and the second gear (210) are integrally formed.

2. The balance shaft assembly of claim 1, further comprising in said upper housing (300):

one or more through holes (310) that penetrate vertically; and

and a transmission gear (320) which receives the rotational power of the engine to rotate the first gear (110).

3. The balance shaft assembly of claim 2,

the lower case (400) includes:

a left housing (400') supporting left side ends of the first shaft (120) and the second shaft (220); and

a right housing (400') supporting right side ends of the first shaft (120) and the second shaft (220),

wherein the left and right housings (400') and (400') are combined with the upper housing (300) in a spaced-apart manner.

4. The balance shaft assembly of claim 3,

left and right journals (130, 230, 140, 240) are formed on left and right ends of the first and second shafts (120, 220), respectively, the left housing (400') supports the left journals (130, 230), respectively, and the right housing (400") supports the right journals (140, 240), respectively.

5. The balance shaft assembly of claim 4,

a lower cap (600) is further provided at one side of the lower housing (400), the lower cap (600) having a front and rear opening,

a placement groove (610) is formed by recessing downward such that one end of each of the first shaft (120) and the second shaft (220) can protrude from the side surface of the lower cap (600).