JPH09210134A - Balancer shaft structure for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of balancer function by the engine oil penetrating into the cylindrical cover of the balancer shaft, without using any special sealer. SOLUTION: The shaft 26 of the balancer shaft 22 comprising two balancer weights 26-1, 26-2, and two cylindrical covers 27, 28 covering these weights, forms spaces 45, 46 therebetween. By fixing both ends of respective cylindrical covers 27 and 28 with press fitting P and rolling calking C, the oil is prevented from penetrating into the spaces 45, 46. By forming oil drain holes 47, 48 in the cylindrical covers 27, 28, the centrifugal force by the rotation of the balancer shaft 22 drains oil from the spaces 45, 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancer shaft structure for an engine which constitutes a balancer shaft having a substantially cylindrical outer shape by fixing a cover to a balancer weight portion rotating inside an oil pan.

[0002]

2. Description of the Related Art A balancer shaft for such an engine is known from Japanese Utility Model Publication No. 62-839. When the balancer weight part that is eccentric from the rotation axis is rotated inside the oil pan, the balancer weight part stirs the oil in the oil pan, which causes rotation resistance. By fixing the coaxial cylindrical cover, it is possible to prevent the oil from being stirred by the balancer weight portion and reduce the rotation resistance.

[0003]

By the way, the above-mentioned conventional balancer shaft has a space inside the cylindrical cover. However, when oil enters the space through the gap between the balancer weight portion and the cylindrical cover, The oil may rotate together with the balancer weight portion, and the balancer function may deteriorate. If you seal the joint between the balancer weight and the cylindrical cover to avoid this,
There is a problem that the number of parts increases.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to avoid functional deterioration of the balancer shaft due to oil infiltration without using a special seal member.

[0005]

In order to achieve the above-mentioned object, the invention described in claim 1 is a balancer weight portion which is eccentrically rotated from an axis of rotation in an oil pan.
In a balancer shaft structure of an engine that constitutes a balancer shaft having a substantially columnar outer shape by fixing a cover having at least a partial arc surface centered on the rotation axis, the balancer is defined between the cover and the balancer weight portion. It is characterized in that an oil discharge path for communicating the above space to the outside is provided and an inner end of this oil discharge path is formed in the vicinity of the outer peripheral portion of the balancer shaft.

According to a second aspect of the present invention, a cylindrical cover centering on the rotating shaft is fixed to a balancer weight portion which is eccentrically rotated from the rotating shaft inside the oil pan, thereby providing a general circle. In a balancer shaft structure of an engine that constitutes a balancer shaft having a columnar outer shape, a cover support portion having a circumferential groove is formed in the balancer weight portion, and at least one end portion of the cover is fitted to the cover support portion. It is characterized in that it is fixed to the circumferential groove by caulking.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 9 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an engine, and FIG. 2 is a line 2-2 of FIG.
2 is a sectional view taken along the line 3 in FIG. 2, and FIG.
-4 line enlarged arrow view (bottom view of the secondary balancer device), FIG. 5 is a view taken along line 5-5 of FIG. 4, FIG. 6 is a sectional view taken along line 6-6 of FIG. 4, and FIG. 7 is an enlarged sectional view taken along line 7-7, FIG. 8 is a longitudinal sectional view of the rear balancer shaft, and FIG. 9 is an enlarged sectional view taken along line 9-9 of FIG.

As shown in FIGS. 1 to 3, an engine E of this embodiment has a crankshaft 1 arranged horizontally and four cylinder axis lines 2 ... Arranged substantially vertically. Is. The engine body includes a cylinder head 3, a cylinder block 4 connected to the lower surface of the cylinder head 3, a lower block 5 connected to the lower surface of the cylinder block 4, and an oil pan 6 connected to the lower surface of the lower block 5. Prepare Five journal support parts 4 ₁ to 4 ₅ formed on the lower surface of the cylinder block 4 and five journal support parts 5 ₁ to 5 formed on the upper surface of the lower block 5.
Between the 5 _5, # 1 to # 5 journal portions 1 ₁ to 1 ₅ of the crankshaft 1 is rotatably supported by being sandwiched.

An oil pump 7 composed of a trochoid pump and a secondary balancer device 8 for reducing secondary vibration of the engine E are provided on the lower surface of the lower block 5, and these oil pump 7 and the secondary balancer device 8 are provided. Is immersed in the oil accumulated in the oil pan 6. Oil pan 6
Is located deeper than the # 1 journal portion 1 ₁ downward # 4 journal portion 1 ₄ below, is advantageous in disposing the oil pump 7.

As will be apparent with reference to FIGS. 4 to 6 as well, the pump housing 9 of the oil pump 7 connected to the lower surface of the journal support portion 5 ₁ of the lower block 5 has five
Pump body 11 integrally connected by bolts 10 ...
And the pump cover 12 are two members. Six reinforcing ribs 12 _1a, ..., 12 _1b are provided on the surface of the pump cover 12 opposite to the pump body 11 (see FIG. 5). These reinforcing ribs 12 _1a, ..., 12 _1b can not only enhance the support rigidity of the rear balancer shaft 22 described later, but also suppress the oil level change due to the ripple of the oil in the oil pan 6. In particular, the five reinforcing ribs 12 _1a formed radially in the journal supporting part of the rear balancer shaft 22 ..., the support rigidity of the rear balancer shaft 22 is greatly improved.

The pump body 11 is provided with a suction port 11 ₁ which is opened on the mating surface with the pump cover 12, a discharge port 11 ₂ and a pump chamber 11 ₃ , and the pump chamber 1
1 ₃ inner rotor 15 meshing with the outer rotor 14 which is rotatably supported rotating in is coupled to the pump shaft 16 which is rotatably supported by the pump body 11 is driven.

The mounting flange 17 ₁ of the oil strainer 17, which filters the oil in the oil pan 6 and supplies it to the suction port 11 ₁ of the oil pump 7, connects the pump cover 12 to the pump body 11 by the five bolts 10 described above. The pump cover 12 is fastened together by two of the ... The oil discharged from the discharge port 11 ₂ of the oil pump 7 is supplied to an oil gallery (not shown) formed in the cylinder block 4 via the oil passage 11 ₄ and then supplied to each part of the engine E as lubricating oil. It

Thus, the oil pump 7 having the above structure
Are two bolts 18, 18 penetrating the pump body 11 below the # 1 journal section 1 ₁ and the # 1 journal section 1
_The pump body 11 is positioned below the _1st and 2nd journal portions 1 _2, that is, at a position biased to the steady-state journal portion 26 ₄ side.
It is connected to the lower surface of the lower block 5 by one bolt 19 penetrating through.

The secondary balancer device 8 is provided with a front balancer shaft 21 and a rear balancer shaft 22 which rotate in opposite directions at a rotational speed that is twice the rotational speed of the crankshaft 1. Front balancer shaft 21
Is the shaft body 23 and the pair of cylindrical covers 24, 25.
The shaft main body 23 is composed of a pair of balancer weight portions 23 ₁ , 23 _{2 which} are eccentric from the rotation axis.
A main journal portion 23 ₃ formed between the balancer weight portions 23 ₁ and 23 ₂ , a steady rest journal portion 23 ₄ formed at one shaft end, and a main journal portion 23 ₃
And a driving helical gear 23 ₅ formed adjacent to, a pair of cylindrical covers 24 and 25 of the pair are disposed coaxially with the axis of rotation balancer weight portions 23
It is fixed to the shaft body 23 so as to cover ₁ , 23 ₂ .

Like the front balancer shaft 21, the rear balancer shaft 22 is also composed of a shaft main body 26 and a pair of cylindrical covers 27 and 28. The shaft main body 26 has a pair of balancer weight portions 26 ₁ eccentric from the rotational axis thereof. , 26 ₂ and both the balancer weight portions 26 _1, 26 formed between the ₂ main journal portion 2
6 ₃ , a steady rest journal portion 26 ₄ formed at one shaft end, and a driven helical gear 26 ₅ formed adjacent to the main journal portion 26 ₃ are provided. It is fixed to the shaft body 26 so as to be disposed coaxially with the rotation axis and cover the pair of balancer weight portions 26 ₁ and 26 ₂ .

Thus, the cylindrical covers 24, 25; 27,
28 balancer weights 23 ₁ , 23 ₂ ; 26 ₁ ,
By covering the 26 _2, balancer weight portion 2
3 ₁ , 23 ₂ ; 26 ₁ , 26 ₂ can be prevented from stirring the oil in the oil pan 6, and the rotational resistance of the front balancer shaft 21 and the rear balancer shaft 22 can be reduced.

As can be seen by referring also to FIG.
A balancer holder 29 made of an iron material is provided on the lower surface of the journal support portion 5 ₃ of the lower block 5 with two bolts 30 and 3.
Combined with 0. A drive helical gear 23 ₅ of the front balancer shaft 21 and a rear balancer shaft 22 are provided inside a gear chamber 29 ₁ formed in the balancer holder 29.
The driven helical gear 26 ₅ is housed in mesh with the driven helical gear 26 _5, and three thrust plates 31 that cover the opening of the gear chamber 29 ₁ and restrict the axial movement of the front balancer shaft 21 and the rear balancer shaft 22 are provided. The bolt 32 is fixed to the balancer holder 29.
An oil escape hole 31 is provided at the center of the thrust plate 31.
₁ is formed, and the driving helical gear 23 ₅ and the driven helical gear 26 are formed through the oil escape hole 31 _1.
The meshing of ₅ allows the hydraulic pressure generated inside the gear chamber 29 ₁ to escape.

The drive helical gear 23 ₅ and the driven helical gear 26 ₅ are composed of the main journal portions 23 ₃ and 26 ₃ and the steady rest journal portion 2 of both balancer shafts 21 and 22.
Since it is provided between 3 ₄ and 26 ₄ and in the vicinity of the main journal portions 23 ₃ and 26 ₃ , the meshing accuracy is very good. Further, since the thrust plate 31 is composed of one member, the number of parts is small and the mounting is easy. Further, since the oil escape hole 31 ₁ is provided at a position where the pressure of the gear chamber 29 ₁ is high and further below, it is advantageous for the oil escape. By further to the balancer holder 29 and a small iron-based material made of thermal expansion, a change in the center distance between both the balancer shafts 21 and 22 can be minimized, thereby both helical gears 23 _5, 26 ₅ It is possible to prevent generation of abnormal noise due to poor meshing.

As is apparent from FIG. 4, the steady rest journal portion 23 ₄ of the front balancer shaft 21 is supported by the bearing hole 11 ₅ formed in the pump body 11, and the steady rest journal portion 26 _{4 of the} rear balancer shaft 22 is supported. Is a bearing hole 12 ₂ formed in the pump cover 12.
Supported by The pump shaft 16 of the oil pump 7 and the rear balancer shaft 22 are arranged coaxially, and the oil chamber 12 ₃ formed in the pump cover 12 so that the shaft end of the steadying journal portion 26 ₄ of the rear balancer shaft 22 faces. Through the oil passage 12 ₄ to the pump shaft 1
It communicates with the shaft end of 6.

In this way, both balancer shafts 21 and 2 are
2 is the main journal portion 23 ₃ , 26 at the center in the longitudinal direction.
Since it is supported at two places, that is, ₃ and the steady rest journal portions 23 ₄ and 26 ₄ at the shaft ends, it is possible to reliably prevent vibrations of both balancer shafts 21 and 22 due to rotation. Moreover, since the steady rest journal portion 26 ₄ of the rear balancer shaft 22 is supported by the bearing hole 12 ₂ of the pump cover 12, the length of the rear balancer shaft 22 is shortened and more stable support is possible. Further, at the position biased to the steady rest journal portion 26 ₄ side, the pump body 1
Since 1 is connected to the lower surface of the lower block 5 by the bolt 19, the support rigidity of the rear balancer shaft 22 is significantly improved.

As is apparent from FIGS. 1 and 4, a pump driven sprocket 33 and a balancer driven sprocket 34 are fixed to the axial ends of the pump shaft 16 and the front balancer shaft 21 extending from the pump body 11, respectively. And these two sprockets 3
3, 34 are connected to a drive sprocket 35 fixed to the shaft end of the crankshaft 1 via an endless chain 36. A chain guide 37 is provided on the tension side of the endless chain 36.
Is provided, and a hydraulic chain tensioner 38 is provided on the slack side.

The number of teeth of the balancer driven sprocket 34 is set to one half of the number of teeth of the drive sprocket 35, and the number of teeth of the pump driven sprocket 33 is set to be different from the number of teeth of the balancer driven sprocket 34. ing. It is preferable for the performance of the oil pump 7 that the number of teeth of the balancer driven sprocket 34 is smaller than the number of teeth of the pump driven sprocket 33. The endless chain 36 that drives the oil pump 7 and the front balancer shaft 21 is inside the endless chain 36a for driving the camshaft, that is, the # 1 journal portion 1 of the crankshaft 1.
It is located on the _1st side.

Next, the structure of the rear balancer shaft 22 will be described in more detail with reference to FIGS. 8 and 9.

A cylindrical cover press-fitting support portion 41 having a circular cross section and a cylindrical cover caulking support portion 42 are formed at both ends of _one balancer weight portion 26 ₁ of the shaft body 26, and similarly the balancer weight portion 26 ₂ of the other balancer weight portion 26 ₂ . A cylindrical cover press-fitting support portion 43 and a cylindrical cover caulking support portion 44 having a circular cross section are also formed at both ends. The pair of cylindrical cover press-fitting support portions 41 and 43 are driven helical gears 2, respectively.
6 ₅ and the main journal portion 26 ₃ are formed at a position adjacent to the pair of cylindrical cover caulking support portions 42, 4
4 are formed on the shaft end side of the rear balancer shaft 22, respectively.

One end of the cylindrical cover 27 is press-fitted P to the outer circumference of the cylindrical cover press-fitting support portion 41 to drive the driven helical gear 26.
The end wall surface 41 ₁ on the ₅ side is abutted and fixed. Further, the other end of the cylindrical cover 27 has a cylindrical cover caulking support portion 42.
Is fitted to the outer circumference of the groove and fixed to the circumferential groove 42 ₁ formed therein by rolling caulking C. Similarly, one end of the cylindrical cover 28 is press-fitted P to the outer periphery of the cylindrical cover press-fitting support portion 43, and abutted and fixed to the end wall surface 43 ₁ on the main journal portion 26 ₃ side. The other end of the cylindrical cover 28 is fitted on the outer circumference of the cylindrical cover caulking support portion 44 is fixed by there formed a circumferential groove 44 ₁ to rolling caulking C.

Thus, the balancer weights 26 ₁ and 26
₂ and the cylindrical cover 27, 28 between the half-cylindrical space 4
5, 46 are formed. And these spaces 45, 46
Two oil discharge holes 47, 47; 48, 48 are formed in the cylindrical covers 27, 28, respectively, so that the inside and the outside of the cylinder can communicate with each other.

The structure of the front balancer shaft 21 is
Substantially the same as that of the rear balancer shaft 22 described above.
Since they are the same, their duplicate description will be omitted. The figure
As is clear from FIG. 4 and FIG. 8, the rear balancer shuff
Main journal section 26 of To 22 _ThreeAn annular oil groove 26₆But
It is formed. This oil groove 26₆Is a balancer holder 2
9 oilways 29_TwoFrom the main balancer of the rear balancer shaft 22
Journal section 26_ThreeThe lubricating oil supplied to the oil passage
29_ThreeThrough the main balancer of the front balancer shaft 21
Internal section 23_ThreeIt is for leading to.

Next, the operation of the embodiment of the present invention having the above-described configuration will be described.

When the engine E is driven, the crankshaft 1 is rotated so that the drive sprocket 35 and the endless chain 3 rotate.
It is transmitted to the pump driven sprocket 33 and the balancer driven sprocket 34 via 6. Since the number of teeth of the balancer driven sprocket 34 is set to one half of the number of teeth of the drive sprocket 35, the front balancer shaft 21 and the drive helical gear 23 ₅ and the driven helical gear 26 having the same number of teeth on the front balancer shaft 21. Rear balancer shaft 2 connected via ₅
The reference numeral 2 reduces the secondary vibration of the engine E by rotating the crankshaft 1 in the opposite directions at twice the rotational speed. Further, since the number of teeth of the pump driven sprocket 33 is different from the number of teeth of the balancer driven sprocket 34, the pump shaft 16 has a rotational speed different from those of the balancer shafts 21 and 22 (for example, 2 times the rotational speed of the balancer shafts 21 and 22). Rotate in 1/1).

As described above, since the pump shaft 16 and the rear balancer shaft 22 arranged below the cylinder block 4 are coaxially separated from each other and driven independently, the oil pump 7 becomes large. Without
Moreover, not only the oil pump 7 and the rear balancer shaft 22 can be compactly arranged below the cylinder block 4, but also the rotational speed of the oil pump 7 is set irrespective of the rotational speed of the rear balancer shaft 22 to maintain the degree of design freedom. be able to. The pump shaft 16 and the rear balancer shaft 22 do not have to be arranged exactly on the same axis, but in consideration of the compactness of the engine E and the degree of freedom in design, it is desirable to arrange them on the same axis as in the embodiment.

As is apparent from FIG. 4, the oil pump 7
Discharge port 11_TwoLubrication groove 12 with one end communicating with_FiveTo
Formed on the surface of the pump cover 12 facing the pump shaft 16
Then, this lubrication groove 12_FiveForm the other end of the pump cover 12
Axial oil passage 12_FourSince it is connected to the
11_TwoTo oil groove 12_FiveOil supplied via
Is the oil passage 12 in the axial direction_FourThrough the oil chamber 12_ThreeSupplied to
Oil chamber 12_ThreeBearing hole 12 connected to_TwoRear rose supported by
Steady rest journal portion 26 of the sensor shaft 22 _FourJun
Slip. In this way, the oil passage 12 is attached to the pump cover 12._FourThe shape
The rear balun with the minimum length of oil passage
The steady rest journal portion 26 of the shaft 22_FourLubricate
can do.

Further, the rear balancer shaft 22 is urged in the direction of arrow A in FIG. 4 by the reaction force that the driven helical gear 26 ₅ receives from the drive helical gear 23 ₅ of the front balancer shaft 21. However, oil supply is formed in the pump cover 12 a groove 12 ₅ and the axial oil passage 1
For 2 ₄ bracing shaft end of journal portion 26 ₄ of the rear balancer shaft 22 by hydraulic pressure applied to the oil chamber 12 ₃ through are urged in the direction of arrow B, restricting movement in the thrust direction of the rear balancer shaft 22 It is possible to prevent the generation of abnormal noise.

Since the front balancer shaft 21 and the rear balancer shaft 22 are immersed in the oil in the oil pan 6, both balancer shafts 21,
The oil may enter the spaces 45 and 46 of the 22.
By the infiltration of this oil, both balancer shafts 21,
The amount of eccentricity of the center of gravity position of 22 from the rotation axis may be substantially reduced and the balancer function may be affected. However, in this embodiment, the cylindrical covers 24, 25, 27, 2
8, one end of which is press-fitted into the cylindrical cover press-fitting support parts 41 and 43 and abuts against the end wall surfaces 41 ₁ and 43 ₁ , and the other end of which is the circumferential groove 4 of the cylindrical cover caulking support parts 42 and 44.
Since the rolling caulking is performed on the parts 2 ₁ and 44 ₁ , it is possible to enhance the sealing performance in those parts and minimize the infiltration of oil into the spaces 45 and 46 without using a special sealing member.

At this time, the cylindrical cover press-fitting support portions 41, 4
One end of each of the cylindrical covers 24, 25, 27, 28 press-fitted into the pressure roller 3 is a large diameter portion d _L, and the cylindrical cover caulking support portion 42,
Since the other ends of the cylindrical covers 24, 25, 27, 28 press-fitted into the 44 are small-diameter portions d _S having a smaller diameter than the large-diameter portion d _L , the set of the cylindrical covers 24, 25, 27, 28 At the time of attachment, both the large diameter portion d _L and the small diameter portion d _S can be simultaneously press-fitted to enhance the sealing property. Moreover, the large diameter part d _L
Is the end wall surfaces 41 ₁ , 4 of the cylindrical cover press-fitting support portions 41, 43.
Because it is abutting the 3 _1, the sealing property is further improved.

Even if oil enters the spaces 45 and 46, at the same time when the front balancer shaft 21 and the rear balancer shaft 22 start rotating,
The oil in the spaces 45 and 46 is promptly discharged from the oil discharge holes 47 and 48 of the cylindrical covers 24, 25, 27 and 28 by the action of the centrifugal force, and the balancer function is surely prevented from being deteriorated. Further, the oil discharge holes 47 and 48 are provided in the cylindrical cover 2.
Balancer weight part 2 at 4, 25, 27 and 28
3 ₂ and the opposite side of 26 ₂ (balancer weight portion 23 ₂ ,
Since it is formed on the side where 26 ₂ is not provided,
The structure for the oil discharge hole is simple, and it is also advantageous for weight reduction of the balancer weight portions 23 ₂ , 26 ₂ .

FIG. 10 shows a rear balancer shaft 22 according to the second embodiment, and the front balancer shaft 21 also has substantially the same structure.

In this embodiment, the shaft body 26 has one
It is equipped with a cylindrical cover press-fitting support portion 41, and is provided on both sides thereof.
The pair of cylindrical covers 27, 28 are press-fitted and the end wall surface 41₁,
41 ₁Helical gear 2 driven against the outer circumference
6_FiveAre fitted and fixed. The shaft body 26 is solid
The main journal section of
In the inside of the corresponding position, half the circumference is the balancer weight part.
26_TwoThe other half circumference corresponds to the space 46
I have. Further, as in the first embodiment, the cylindrical covers 27, 28 are
Large diameter portion d at one end and the other end_LAnd small diameter part d_SBe prepared
The large diameter part d_LIs a driven helical gear 26
_FiveIs press-fitted into the cylindrical cover press-fitting support portion 41 inside the
End wall 41₁, 41₁Is struck by.

According to this embodiment, by ensuring a large volume of the spaces 45, 46 in the rear balancer shaft 22, it is possible to increase the eccentric amount from the rotation axis of the center of gravity position and enhance the balancer function. When the rear balancer shaft 22 rotates, the centrifugal force of the balancer weight portions 26 ₁ and 26 ₂ exerts a load in the direction of arrow D, so that the side a corresponding to the main journal portion slides on the support surface of the balancer holder 29. Support the load. In addition, the space 4 is on the b side of the position corresponding to the main journal section.
Since the load supporting strength is low because it opposes 6, the strength problem does not occur because the load does not act on that portion, and an oil film is held between that portion and the balancer holder 29. Lubrication performance can be improved.

Moreover, the large-diameter portion d _L is attached to the driven helical gear 26.
_{Since the} cylindrical cover is press-fitted into the press-fitting support portion 41 and abuts against the end wall surfaces 41 ₁ and 41 ₁ , the sealability is greatly improved, and the rear balancer shaft is different from that of the first embodiment. The axial dimension of 22 can be reduced. The oil discharge hole 4 in the second embodiment
The structures of 7, 48 and rolling caulking are the same as in the first embodiment.

FIG. 11 shows a rear balancer shaft 22 according to the third embodiment, and the front balancer shaft 21 also has substantially the same structure.

In this embodiment, the shaft main body portion 26 is provided with _one balancer weight portion 26 ₁ , and the outer peripheral driven helical gear 2 of the one cylindrical cover 27 covering the outer periphery thereof.
6 ₅ is fitted and fixed. The cylindrical cover 27 has a large diameter portion d _L and a small diameter portion d _S at one end and the other end. The large diameter portion d _L is press-fitted into the cylindrical cover caulking support portion 44 and the small diameter portion d _L is caulked with the cylindrical cover caulking support. It is press-fitted into the portion 42.

According to this embodiment, the cylindrical cover 27 is
The number of parts can be reduced because only one piece is required. Moreover, since rolling crimping can be performed after press-fitting both ends of the cylindrical cover 27, intrusion of oil into the space 45 can be prevented more reliably, and the volume of the space 45 can be maximized to achieve a balancer function. Can be increased. Further, the load bearing strength and lubrication at the position corresponding to the main journal portion are not affected, as in the second embodiment. Incidentally, the oil discharge holes 47, 4 in the third embodiment
The structure of 8 and rolling caulking is the same as that of the first embodiment.

FIG. 12 shows a fourth embodiment of the rear balancer shaft 22 (or the front balancer shaft 21). In this embodiment, the cross sectional area of the oil discharge holes 47, 48 is reduced from the inner side to the outer side in the radial direction. It has a feature in the point. According to this embodiment, the spaces 45, 4
The oil can be discharged from 6 more effectively.

FIG. 13 shows a fifth embodiment of the rear balancer shaft 22 (or the front balancer shaft 21). In this embodiment, the oil discharge holes 47 and 48 for communicating the inside and the outside of the spaces 45 and 46 are provided in the rear balancer shaft. Balancer weight part 2 on the delay side of rotation direction F of 22
It is formed near 6 ₁ , 26 ₂ . According to this embodiment,
When the rear balancer shaft 22 starts rotating in the arrow F direction, the oil in the spaces 45, 46 is inertially guided in the arrow G direction along the inner peripheral surfaces of the cylindrical covers 27, 28.
It is quickly discharged from the oil discharge holes 47, 48. At this time, if the air introduction hole 49 is formed on the leading side of the rear balancer shaft 22 in the rotation direction F, the oil is further promoted by introducing the air from the air introduction hole 49 into the spaces 45 and 46. .

FIG. 13 shows a fifth embodiment of the rear balancer shaft 22 (or the front balancer shaft 21). In this embodiment, in addition to the oil discharge holes 47 and 48 for communicating the inside and the outside of the spaces 45 and 46, the air is also added. Introduction hole 49
The oil discharge holes 47 and 48 are formed on the lag side of the rear balancer shaft 22 in the rotation direction F, and the air introduction hole 49 is formed on the lead side of the rotation direction F. According to this embodiment, when the rear balancer shaft 22 starts to rotate in the arrow F direction, the oil in the spaces 45 and 46 is inertially guided in the arrow G direction along the inner peripheral surfaces of the cylindrical covers 27 and 27. , Is quickly discharged from the oil discharge holes 47, 48. At this time, the spaces 45, 4 from the air introduction hole 49
The introduction of air into 6 further accelerates the discharge of the oil.

FIG. 14 shows a sixth embodiment of the rear balancer shaft 22 (or the front balancer shaft 21). In this embodiment, instead of forming the oil discharge holes 47, 47 in the cylindrical cover 27, the oil discharge holes 47, 47 are formed in the cylindrical cover press-fitting support portions 41, 43 at both ends of the shaft body 26. If the oil discharge holes 47, 47 are formed in a groove shape as shown in the drawing, the machining thereof is extremely easy.

FIG. 15 shows a seventh embodiment of the rear balancer shaft 22 (or the front balancer shaft 21). In this embodiment, a gap communicating with the space 45 is formed between the balancer weight portions 26 ₁ and 26 ₂ of the shaft body 26 and the cylindrical cover 27, and the oil discharge holes 47 ... Communicating with this gap are formed in the cylindrical cover 27. It was formed. With this configuration, the oil guided by the centrifugal force into the gaps between the balancer weight portions 26 ₁ and 26 ₂ and the cylindrical cover 27 can be effectively discharged from the oil discharge holes 47.

FIG. 16 shows an eighth embodiment of the rear balancer shaft 22 (or the front balancer shaft 21). In this embodiment, a cover 27 fixed to the shaft body 26 is formed in a half-cylindrical shape, and an oil discharge hole 47 is formed in the cover 27. Even if the cover 27 is not a complete cylindrical shape as described above, the first
The oil discharging function similar to that of the seventh embodiment can be exerted.

Although the embodiments of the present invention have been described in detail above, the present invention can be modified in various ways without departing from the scope of the invention.

For example, in the invention described in claim 1, it is not necessary to apply caulking to fix the covers 24, 25, 27, 28, and the covers 24, 25, 27, 28 can be fixed by any means. You can Further, in the invention described in claim 2, the oil discharge holes 47 and 48 can be omitted.

[0052]

As described above, according to the invention as set forth in claim 1, an oil discharge passage for communicating the space defined between the cover and the balancer weight portion to the outside is provided, and the oil discharge passage is provided. Since the inner end of the balancer is formed near the outer periphery of the balancer shaft, even if oil enters the space through the gap between the cover and the balancer weight, this oil will generate centrifugal force from the oil discharge passage as the balancer shaft rotates. It is promptly discharged at, so that the functional deterioration of the balancer shaft can be avoided.

According to the invention described in claim 2,
Since the cover support portion having the circumferential groove is formed in the balancer weight portion, and at least one end portion of the cover is fitted into the cover support portion and caulked and fixed to the circumferential groove, the above-mentioned structure is achieved without using a special seal member. It is possible to prevent the oil from entering the space and prevent the functional deterioration of the balancer shaft.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an engine

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a view in the direction of arrows in FIG. 2;

FIG. 4 is an enlarged arrow view of line 4-4 of FIG. 2 (bottom view of the secondary balancer device).

FIG. 5 is a view taken along line 5-5 in FIG. 4;

FIG. 6 is a sectional view taken along line 6-6 in FIG. 4;

FIG. 7 is an enlarged sectional view taken along line 7-7 of FIG.

FIG. 8 is a vertical sectional view of a rear balancer shaft.

FIG. 9 is an enlarged sectional view taken along line 9-9 of FIG. 8;

FIG. 10 is a vertical sectional view of a rear balancer shaft according to a second embodiment.

FIG. 11 is a vertical sectional view of a rear balancer shaft according to a third embodiment.

FIG. 12 is a transverse sectional view of a rear balancer shaft according to a fourth embodiment.

FIG. 13 is a transverse sectional view of a rear balancer shaft according to a fifth embodiment.

FIG. 14 is a longitudinal sectional view and a lateral sectional view of a rear balancer shaft according to a sixth embodiment.

FIG. 15 is a lateral sectional view and a lateral sectional view of a rear balancer shaft according to a seventh embodiment.

FIG. 16 is a lateral sectional view and a lateral sectional view of a rear balancer shaft according to an eighth embodiment.

[Explanation of symbols]

6 Oil pan 23 ₁ Balancer weight part 23 ₂ Balancer weight part 21 Front balancer shaft (balancer shaft) 22 Rear balancer shaft (balancer shaft) 24 Cylindrical cover (cover) 25 Cylindrical cover (cover) 26 ₁ Balancer weight part 26 ₂ Balancer weight Part 27 Cylindrical cover (cover) 28 Cylindrical cover (cover) 42 Cylindrical cover caulking support part (cover support part) 42 ₁ Circumferential groove 44 Cylindrical cover caulking support part (cover support part) 44 ₁ Circumferential groove 45 Space 46 Space 47 Oil discharge hole (oil discharge path) 48 Oil discharge hole (oil discharge path)

Claims (2)

[Claims] 1. A balancer weight portion (23 ₁ , 2) which is eccentrically rotated from an axis of rotation inside an oil pan (6).
3 ₂ , 26 ₁ , 26 ₂ ) has a cover (24, 25, ₂ ) having at least a partial arc surface centered on the rotation axis.
In the balancer shaft structure of the engine, which comprises the balancer shaft (21, 22) having a substantially cylindrical outer shape by fixing (7, 28), the cover (24, 25, 27, 28) and the balancer weight part ( The oil discharge passages (47, 48) for communicating the space (45, 46) defined between 23 ₁ , 23 ₂ , 26 ₁ , 26 ₂ ) to the outside are provided, and the oil discharge passages (47, 48) are also provided. The balancer shaft (21,
22) A balancer shaft structure for an engine, which is formed in the vicinity of the outer peripheral portion. 2. A balancer weight portion (23 ₁ , 2) which is eccentrically rotated from an axis of rotation inside the oil pan (6).
By fixing a cylindrical cover (24, 25, 27, 28) centering on the rotation axis to 3 ₂ , 26 ₁ , 26 ₂ ), a balancer shaft (21, 22) having a substantially cylindrical outer shape is provided. ), The balancer shaft structure of the engine, the balancer weight portion (23 ₁ , 23 ₂ , 26 ₁ ,
26 ₂ ) is formed with a cover supporting portion (42, 44) having circumferential grooves (42 ₁ , 44 ₁ ), and the cover supporting portion (42, 44) is formed.
44) by fitting at least one end of the cover (24, 25, 27, 28) into the circumferential groove (42 ₁ , 4).
4 ₁ ) The balancer shaft structure of the engine characterized by being caulked and fixed.