JPH0318761Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a lubricating oil passage structure in an engine balancer shaft, particularly when a thrust plate is provided to restrict axial movement of the shaft.

(Prior Art) In a reciprocating piston engine, centrifugal force acts on eccentrically rotating parts such as the crank arm and crank pin of the crankshaft, or inertial force acts on reciprocating parts such as the piston and piston pin. There is a problem in that an excitation force is generated and, along with the generation of this excitation force, significant vibration is generated. Therefore, in recent years, for example,
An engine equipped with a balancer device as described in the above publication is being put into practical use. As shown in Fig. 5, this balancer device has unbalanced parts B' and B' on both sides of a cylinder block A (only one side is shown in the figure) and extends in the longitudinal direction of the engine. Balancer shaft B, bearing
It is rotatably held via C ₁ and C ₂ and driven by the crankshaft D, and the phase of the unbalanced parts B' and B' with respect to the crankshaft D and the balancer shaft from the crankshaft D are controlled. By appropriately setting the rotation transmission ratio to B, etc., engine vibration is reduced as much as possible.

However, when the balancer shaft B is installed in an engine, one end surface of the cylinder block A is
A thrust plate E as shown in FIG. 6 is fixed to the end surface of the side where the balancer shaft B protrudes, and the end surface (bearing surface) of the plate E is fixed.
, journal part B ₁ (bearing) of balancer shaft B
The axial movement of the balancer shaft B is restricted by bringing the end faces of the balancer shaft B (fitted into C ₁ ) into contact or sliding contact with each other. According to such a configuration, when the balancer shaft B rotates, the thrust plate E and the journal part B ₁
There will be a need to supply the required amount of lubricating oil to the sliding contact area F with the bearing _C1 (bearing metal). It has been customary to lubricate the sliding contact portion F by introducing lubricating oil to the thrust plate E side through a small gap H between the bearing C ₁ and the journal portion B ₁ .

(Problem to be solved by the invention) By the way, as mentioned above, the lubrication for the sliding contact part F between the balancer shaft B (journal part B ₁ ) and the thrust plate E is conducted from the bearing C ₁ through the gap H. According to the configuration using lubricating oil, the above-mentioned gap H is extremely small, and the gap H
As a part (a large amount) of the lubricating oil flows out from the anti-thrust plate E side, it becomes difficult to spread the required amount of lubricating oil over the entire area of the sliding contact part F, which makes it difficult to achieve good lubrication and Since the cooling action is no longer performed, an excessive increase in frictional heat and seizure caused by this will occur in the sliding contact portion F. In addition, according to such a lubrication method, the oil that was once used for lubrication between the bearing C ₁ and the journal part B ₁ is reused, so that the above-mentioned problems are noticeable. will be made into

Furthermore, since the balancer shaft B has an unbalanced portion B', when the balancer shaft B rotates, especially at high speed, the sixth As shown by the chain line in the figure, the shaft B is located at the unbalanced portion.
It will bend convexly towards B' side. Such deflection of the balancer shaft B causes so-called one-sided contact in which both end surfaces of the journal portion _B1 and the thrust plate E come into sliding contact only on the unbalanced portion B' side. At the bottom, the lubricating oil is supplied only to the clearance created on the opposite side of the contact area, without reaching the sliding contact area or the _one- side contact area. Uneven wear occurs on the sliding surface, which may eventually lead to seizure.

(Means for Solving the Problems) The present invention improves the structure of the oil passage for supplying lubricating oil to the sliding contact portion between the balancer shaft and the thrust plate and appropriately arranges the passage. The lubricating oil is efficiently supplied so that the required amount of lubricating oil can be supplied over the entire sliding contact area of the two, and the sliding that is caused by the balancer shaft being bent during its rotation is avoided. This was made for the purpose of preventing uneven wear and seizure of the contact parts, and is characterized by the following structure.

That is, a balancer shaft driven by a crankshaft and having an unbalanced portion offset in a predetermined direction with respect to the center of rotation is rotatably held on a machine wall via a bearing, and is attached to one end of the balancer shaft. In a configuration in which a thrust plate is fixed to the machine wall for slidingly contacting the end face of the stepped portion and regulating the axial movement of the shaft, lubricating oil led to the bearing is transferred between the stepped portion and the thrust plate. An oil passage for supplying oil to the sliding contact portion with the plate is bored in the balancer shaft. The opening of the oil passage to the sliding contact portion is offset from the center of rotation of the balancer shaft in the same direction as the unbalanced portion.

(Function) According to the above configuration, when the balancer shaft rotates, the balancer shaft is deflected in a convex shape toward the unbalanced part due to the action of centrifugal force generated in conjunction with the eccentric rotation of the unbalanced part. Even if both end surfaces of the thrust plate and the stepped part (for example, the journal part) of the balancer shaft are in a state of uneven contact where they are in sliding contact only on the unbalanced part side, the lubricating oil is offset and opened toward the unbalanced part side. Since the oil is supplied through the oil passage, the lubricating and cooling effects on the one-sided contact portion can be performed satisfactorily.

In addition, by providing a separate oil passage in the balancer shaft from the bearing to the sliding contact area, lubricating oil is actively supplied.
This effectively prevents the lack of oil amount, which would otherwise occur in the case where a portion of the lubricating oil once used for lubricating the bearing or journal portion is reused.

The balancer shaft is held in a rotatable state by a plurality of bearings, and in this case, it is desirable that the oil passage communicate with a bearing disposed close to the thrust plate.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. This embodiment relates to an in-line 4-cylinder 4-cycle engine, and is intended to deal with secondary vibrational force due to inertial force of reciprocating parts such as pistons.

As shown in FIG. 1, a cylinder block 2 of an engine 1 is provided with a partition wall 3 between adjacent cylinders, and a crankshaft 4 is arranged in the center of the skirt portion of the cylinder block 2 in the direction of the cylinder row. has been done. This crankshaft 4 includes the above-mentioned partition walls 3 and end walls 5, 5 at both ends of the cylinder block.
(only a part of which is shown in FIG. 2) and a bearing cap 6 attached to these walls. Each crank journal part is rotatably supported by a main bearing 7, which is not shown. However, the pistons of each cylinder are connected via a connecting rod to a crank pin provided at an eccentric position via a crank arm. The cylinder block 2 of the engine 1 also has a pair of left and right balancer shafts 8,
8 is provided. These balancer shafts 8, 8 are supported slightly above the left and right sides of the crankshaft 4, in parallel with the shaft 4 and symmetrically, and in synchronization with the rotation of the crankshaft 4, the balancer shafts 8, 8 rotate twice as much as the crankshaft 4. It is designed to be driven at a rotational speed of . In that case, both of the two balancer shafts 8, 8 are rotationally driven by the rotation of the crankshaft 4 being transmitted through the chain 9;
The balancer shaft 8 located on the right side of the drawing is
The chain 9 is wound around a sprocket (not shown) fixed to one end of the shaft 8, so that the balancer shaft 8 is arranged in the same direction as the rotation of the crankshaft 4 and on the left side.
As shown in FIG. 2, an idle gear 11 meshes with a gear 10 fixed to one end of the shaft 8.
The chain 9 is wound around the sprocket 12, which rotates integrally with the crankshaft 4, so that the chain 9 rotates in the opposite direction to the rotation of the crankshaft 4.

Next, the configuration of this balancer shaft 8 and the bearing structure of this shaft 8 will be explained with reference to FIG. The shaft 8 has an unbalanced portion 8a provided offset in a predetermined direction with respect to the axis, and an unbalanced portion 8a.
The extended shaft part 8b is connected to one end thereof, and a first journal part 81 is provided at the end of the extended shaft part 8b, and a second journal part ₈₁ is provided at the intermediate part of the unbalanced part 8a. A journal portion 8 ₂ is provided, and a third journal portion 8 ₃ is provided at the end opposite to the extension shaft portion. The unbalanced portion 8a is the second and third unbalanced portions in the central portion in the longitudinal direction of the engine 1.
The first journal portion 8 1 is disposed on the side of the cylinders 13 ₂ and 13 ₃ and the first journal portion 8 ₁ is disposed on the side of the cylinder block 2 .
The second journal part 82 is connected to the first bearing hole 14 formed in the end wall 5 on the fourth cylinder ₁₃₄ side, and the second journal part 82 is connected to the second bearing hole 14 formed in the end wall ₅ on the fourth cylinder 134 side.
A third bearing hole 15 is formed in the partition wall 3 ₁ between the third cylinders _{13 2} and 13 ₃ , and a third journal portion 8 ₃ is formed in the partition wall 3 ₂ between the first and second cylinders 13 ₁ and 13 ₂ . The first, second and third bearing holes are respectively inserted into the third bearing hole 16.
They are rotatably fitted via bearings (bearing metal) 17, 18, and 19. Further, a protruding shaft portion 8c protruding from the cylinder block end wall 5 is provided at the end of the balancer shaft 8 on the first journal portion ₈₁ side, and a protruding shaft portion 8c is provided between the shaft portion 8c and the crankshaft 4 described above. A gear 10 constituting a drive mechanism is fixed.

Here, the end wall 5 and the partition walls 3 ₁ and 3 ₂ of the cylinder block 2 are provided with an oil gear gallery 2 shown in FIG.
1st to 3rd oil supply passages 2 led from 0
1, 22, and 23 are provided, respectively, and the above-mentioned first to third
The lubricating oil is supplied to the sliding surfaces of the first to third journal parts 8 ₁ , 8 ₂ , 8 ₃ of the bearings 17 , 18 , 19 and the balancer shaft 8 fitted thereto, and the above-mentioned The ends of each of the oil supply passages 21, 22, 23 that open to the outer surface of the cylinder block are closed by blind plugs 24...24. Furthermore, the end wall 5 and the partition wall 3 ₁ are provided with baffles 25 and 25 that cover the first and second bearings 17 and 18, and these are designed to prevent oil flowing out from each bearing 17 and 18 from entering the cylinder block 2. This is to prevent oil from scattering and becoming oil mist.

On the other hand, on the end wall 5 of the cylinder block 2,
A thrust plate 26 into which the protruding shaft portion 8c of the balancer shaft 8 is loosely inserted and which is interposed between the first journal portion ₈₁ and the gear 10 and receives the thrust of the shaft 8 is fixed by bolts 27, 27. has been done. When the balancer shaft 8 rotates, the outer _end surface (the right end surface in FIG.
By abutting or slidingly contacting the inner end surface (the left end surface in the figure) of the shaft 8, the axial movement of the shaft 8, particularly the rightward movement in FIG. 3, is restricted.

As shown in the enlarged cross-section of FIG. 4, the first journal portion ₈₁ of the balancer shaft 8 has a sliding contact between the outer end surface of the journal portion ₈₁ and the inner end surface of the thrust plate 26. An oil passage 28 for supplying lubricating oil to section X is bored. The oil passage 28 has one end opened in the circumferential surface of the first journal portion 8 ₁ and communicates with the first oil supply passage 21 via a circumferential groove 17 a formed in the inner circumferential surface of the first bearing 17 . , and the other end is opened at the outer end surface of the journal part 8 ₁ and the sliding contact part X
The opening 28a extends from the opening 28a on the circumferential surface of the journal portion 8 ₁ toward the axis of the journal portion 8 ₁ , is bent in the middle, and then extends in the axial direction. The upstream end opening of this oil passage 28, that is, the opening 28b on the outer end surface of the journal part ₈₁ , is located at the shaft center with respect to the axis of the journal part ₈₁ (rotation center axis of the balancer shaft 8). It is provided at a position offset by a predetermined amount in the same direction as the unbalanced portion 8a of No.8.

Next, the operation of this embodiment will be explained.

First, when the engine 1 is operating, a secondary excitation force is generated due to the inertia force acting on reciprocating parts such as the piston and piston pin, and this excitation force is transmitted to the left and right balancer shafts 8, 8 is canceled out as follows. In other words, these balancer shafts 8, 8 are arranged symmetrically and are driven in mutually opposite directions at twice the rotation speed of the crankshaft 4, so that the unbalanced portions 8a, 8 of both balancer shafts 8, 8, The resultant force of the centrifugal force acting on the crankshaft 8a fluctuates in the vertical direction at a half cycle of the rotation cycle of the crankshaft 4. Therefore, by appropriately setting the phases of the crankshaft 4 and both balancer shafts 8, 8, the centrifugal force acting on the unbalanced portions 8a, 8a when the excitation force due to the inertial force of the reciprocating portion is directed upward can be reduced. It becomes possible to generate a resultant force of the forces downward, and also to generate this resultant force upward when the above-mentioned excitation force is downward, thereby canceling out the above-mentioned excitation force. In this way, the vibrations of the engine 1 are effectively reduced.

On the other hand, when the balancer shaft 8 is rotating as described above, an oil pump (not shown) driven by the crankshaft 4 pumps lubricating oil in the oil pan to the oil gear gallery 20 formed in the cylinder block 2. Furthermore, the gear 20
First to third oil supply passages 21 to 23 leading to
It is supplied to the first to third bearings 17 to 19 via.
As a result, an oil film of lubricating oil is generated on the sliding surfaces of each of the bearings 17 to 19 and each of the journal parts 8 ₁ to 8 ₃ of the balancer shaft 8 fitted thereto, and the lubricating oil is removed from the shaft 8 to each bearing. The radial forces acting on the bearing holes 17 to 19 and the bearing holes 14 to 16 are well received while the respective sliding surfaces are lubricated.

Of the bearings 17 to 19, the first bearing 1 provided on the end wall 5 of the cylinder block 2
7, and the first journal part 8 ₁ fitted thereto
In this case, the lubricating oil led from the first oil supply passage 21 flows into the oil passage 28 bored in the first journal part ₈₁ through the circumferential groove of the bearing 17, and then 28, it is supplied to the sliding contact portion X between the inner end surface of the thrust plate 26 and the outer end surface of the first journal portion ₈₁ . This results in
An oil film of lubricating oil is generated on the sliding contact portion X, and the thrust force of the balancer shaft 8 is received by the thrust plate 26 through this oil film, causing the shaft 8 to move in the axial direction (to the right) during rotation. movement) is regulated. In this way, the oil passage 2 for lubricating the sliding contact portion
8 is provided separately, the required amount of lubricating oil is actively supplied and distributed over the entire sliding contact area X, thereby providing good lubrication and cooling effects while maintaining the axial direction of the balancer shaft 8. It becomes possible to regulate movement.

Furthermore, when the balancer shaft 8 rotates, particularly when rotating at high speed, due to the action of centrifugal force generated due to the eccentric rotation of the unbalanced portion 8a, the left end of the extended shaft portion 8b is caused to move in the direction a shown in FIG. A load is applied (in the direction in which the unbalanced portion 8a is offset with respect to the rotation center axis), and this causes the shaft portion 8b to bend as shown by the chain line in the figure. Due to such deflection of the balancer shaft 8, the outer end surface of the first journal portion ₈₁ slides into contact with the inner end surface of the thrust plate 26 only at the portion indicated by the symbol X' in the figure, so-called one-piece contact. Become.

However, even in such a case, since the upstream end opening 28b of the oil passage 28 is offset by a predetermined amount in the same direction as the unbalanced portion 8a with respect to the rotation center axis of the balancer shaft 8, The lubricating oil led through 28 is supplied in a concentrated manner around the sliding contact portion (one-sided contact portion) indicated by the symbol X'. As a result, lubricating oil is properly and efficiently supplied, and the thrust plate 26 and the first
Insufficient supply of lubricating oil to the uneven contact portion due to uneven contact between the journal portion 8 ₁ and the resulting uneven wear of the outer end surface of the journal portion 8 ₁ or the inner end surface of the thrust plate 26; Furthermore, seizure and the like occurring between the two can be effectively prevented.

In this embodiment, the oil passage 2
The lubricating oil flowing out from the upstream end opening 28b of the gear 10 is transmitted to the inner end surface of the gear 10 and the thrust plate 26 through the gap between the through hole formed in the thrust plate 26 and the balancer shaft protruding shaft part 8c.
The oil is also supplied to the slight gap Y between the balancer shaft 8 and the outer end surface of the balancer shaft 8, and by forming an oil film in this gap Y, the leftward movement of the balancer shaft 8 can be well controlled. It is said that

(Effects of the invention) As described above, according to the invention, in a structure including a balancer shaft provided with an unbalanced portion and a thrust plate that restricts the axial movement of the shaft, the sliding contact portion between the two By providing a separate oil passage for supplying lubricating oil to the sliding contact area between the bearing surface of the thrust plate and the stepped end face of the balancer shaft, lubricating oil can be actively supplied to the sliding contact area. This will provide the desired lubrication and cooling effect.

In particular, according to the present invention, when the balancer shaft rotates, the shaft is deflected by the action of centrifugal force generated due to the eccentric rotation of the unbalanced portion, and this causes the end surfaces of the two to be in a state of one-sided contact. Even in this case, lubricating oil is supplied intensively to the area around the one-sided contact area through the oil passage opened offset to the unbalanced part side, so that uneven wear on both end faces is prevented. This effectively prevents or suppresses burn-in and the like.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view of the main part showing an embodiment of the present invention, Fig. 2 is a front view showing a part of the end face of the cylinder block equipped with the drive mechanism of the balancer shaft, and Fig. 3 is the balancer shaft and its surroundings. FIG. 1 is an enlarged cross-sectional view of the main part taken along the line shown in FIG. FIG. 6 is a cross-sectional view showing a schematic configuration of a conventional engine. 1...Engine, 2...Machine wall (cylinder block), 4...Crankshaft, 8...Balancer shaft, 8a...Unbalanced part, 8 ₁ ...Stepped part (first journal part), 17- 19...Bearing, 26
...Thrust plate, 28...Oil passage, 2
8b...Oil passage opening, X...Sliding contact portion.

Claims (1)

[Scope of utility model registration request] It is rotatably supported on the machine wall via a bearing and driven by a crankshaft, and has an unbalanced part offset in a predetermined direction with respect to the center of rotation, and the end face of the stepped part formed at one end is An engine balancer shaft configured to restrict axial movement by slidingly contacting an end face of a thrust plate fixed to an aircraft wall, the engine balancer shaft having a structure in which lubricating oil led to the bearing is connected to the stepped portion. An oil passage for supplying oil to the sliding contact portion with the thrust plate is bored, and an opening of the oil passage to the sliding contact portion is offset in the same direction as the unbalanced portion with respect to the center of rotation. An engine balancer shaft characterized by: