JPS62209213A - Balancer shaft for engine - Google Patents

Abstract

PURPOSE:To prevent uneven contact which occurs at a bearing part by supporting with a bearing the middle part of the unbalanced part of a balancer shaft and at the same time making angles of deflection of the unbalanced parts on both sides of the bearing equalized. CONSTITUTION:The first bearing part 1 is provided at the end part of an extended shaft part 32 joined on one end side of the unbalanced part 31 of a balancer shaft 30, and also the second bearing part 11 and the third bearing part 111 are respectively provided at the end part opposite to the extended shaft part of the unbalanced part 31 and in the middle part of the unbalanced part 31. And out of distances between the first bearing part and the third and between the second bearing part and the third, the longer one between the bearing parts makes the weight of its unbalanced part 31 heavier than the shorter one does, thus equalizing the deflections of the unbalanced parts 31 on both sides of the third bearing part 111.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a balancer shaft for a reciprocating piston engine, and particularly to a bearing structure for the shaft.

(Conventional technology) In reciprocating piston engines, centrifugal force acts on eccentrically rotating parts such as the crank arm and crank bin in the crankshaft, or inertial force acts on reciprocating parts such as the piston and piston pin. There is a problem in that vibrational force is generated. In order to deal with such an excitation force, it is possible to generate an excitation force in the opposite direction by installing a balance weight on the crank arm, etc., and to balance both sides of the excitation force. In an in-line 4-cylinder 4-Nikle engine, the above-mentioned balance weight alone produces a secondary excitation force (excitation force whose frequency is twice the crankshaft rotational speed) due to the inertia of the reciprocating part. I can't cancel it.

To solve this problem, an engine balancer device has been known, for example, as disclosed in Japanese Patent Publication No. 57-44863. This is a system in which a balancer shaft having an unbalanced part is arranged parallel to the crankshaft and is driven by the crankshaft. In the case of a four-cylinder engine, the engine is driven at a rotational speed twice as high as the crankshaft rotational speed, thereby canceling out the secondary excitation force due to the inertial force of the reciprocating portion as described above.

However, when this balancer shaft is installed in an engine, it is necessary to arrange the unbalanced part at the center in the longitudinal direction of the engine so that the unbalanced part does not generate new vibrational force of the pitching moment shade. It is necessary to provide the bearing portion of the shaft at a highly rigid location in the cylinder block, that is, at a partition wall between adjacent cylinders. Therefore, in the past, regarding the structure of this unbalanced part or bearing part, for example, in an inline four-cylinder engine, a structure as shown in FIGS. 5(a) to (C) has been proposed or adopted. There is.

That is, what is shown in FIG. 5(a) is the balancer shaft 1.
The unbalanced part 2 is disposed on the sides of the second and third cylinders 32 and 33 located in the center in the longitudinal direction of the engine, and the first unbalanced part 2 is located at both ends of the unbalanced part 2. A second bearing part 41.42 is provided, and these bearing parts 41.42 are connected to the first bearing part 41.42 in the cylinder block. It is pivotally supported by a partition wall 51 between the second cylinders 31 and 32 and a partition wall 53 between the third and fourth cylinders 33 and 34, respectively. Further, an extension shaft portion 6 connected to a drive mechanism (not shown) is provided at one end side of the unbalanced portion 2, and a third bearing portion 43 is provided at the end of the shaft portion 6. The wall 54 of the end of the cylinder block
The structure is pivoted on the

In addition, what is shown in FIG. 5(b) is the same as that shown in FIG. 5(a) above.
In addition to this structure, a fourth bearing part 4a' is provided in the middle part of the unbalanced part 2', and this bearing part 44' is connected to the partition wall 52 between the second and third cylinders 32 and 33 in the cylinder block. In other words, in this structure, the balancer shaft 1' has first and second bearing parts 41' and 42' at both ends of the unbalanced part, and the end of the extension shaft part 6'. A total of four bearing parts, the third bearing part 43' and the fourth bearing part 44', are provided.

Furthermore, what is shown in Fig. 5 <C> is a3 in Fig. 5 (b).
The first and second bearing parts 41' and 42' are eliminated, and in this structure, the balancer shaft 1" has a first bearing part 41" in the middle of the unbalanced part 2", and an extension shaft part 6.
Two bearing parts are provided, a second bearing part 42'' at the end of ``. Incidentally, this structure is disclosed in the above-mentioned publication.

(Problems to be Solved by the Invention) By the way, each of the bearing structures of the balancer shaft shown in FIGS. 5(a) to 5(G) has the same problems.

That is, in the structure shown in FIG. 5(a), since the span between the first and second bearing parts 41 and 42 at both ends of the unbalanced part 2 becomes long, the unbalanced part 2 has a large As a result, the bending moment acts on the first and second bearing portions 41.42 and the bearing holes (or the bearing metal fitted in the chain holes) of the partition wall 51.53 into which they are fitted, causing uneven wear. This makes them more likely to burn or burn out.

In addition, in the structure shown in FIG. 5(b), since the fourth bearing part 44' is provided in the middle part of the unbalanced part 2', the above-mentioned damage due to the bending moment acting on the unbalanced part 2' Although the adverse effects are prevented or reduced, on the other hand, since the number of bearing parts increases, the driving vJ loss due to the sliding resistance at each bearing part increases.

Furthermore, in the structure shown in FIG. 5(C), drive loss is reduced because the number of bearings is small, and the first bearing 41'' provided in the middle of the unbalanced portion 2'' reduces the unbalanced portion. Although the generation of a large bending moment due to the centrifugal force acting on the portion 2'' is suppressed, in this structure, the portion 28'' on the side opposite to the extension shaft portion of the unbalanced portion 2'' is cantilevered. 2a'' swings around, and problems such as uneven wear in the first bearing part /11'' and the bearing hole into which it is fitted become more serious.

(Means for Solving the Problems) The present invention solves the above-mentioned problems regarding the balancer shaft of an engine, particularly the bearing structure of the shaft, thereby reducing drive loss and preventing uneven wear and seizure in the bearing portion. The purpose of this invention is to realize a balancer shaft that is free from such problems, and in order to achieve this purpose, it is characterized by the following structure.

That is, in the engine balancer shaft according to the present invention, the unbalanced part is disposed at the center in the longitudinal direction of the engine, and an extension shaft part is connected to one end of the unbalanced part to connect it to the drive mechanism. A first bearing part is provided at an end of the extended shaft part, a second bearing part is provided at an end of the unbalanced part on the side opposite to the extended shaft part, and a third bearing part is provided at an intermediate part of the unbalanced part.

Then, between the first and third bearing parts and between the second and third bearing parts, the weight of the unbalanced part is distributed so that the weight of the longer dimension between the bearing parts is greater than that of the shorter dimension. conduct.

(Function) According to the above configuration, in the balancer seat 71- in which the unbalanced part is arranged at the center in the longitudinal direction of the engine, the third bearing part provided in the middle part of the unbalanced part acts on the unbalanced part. The bending moment caused by centrifugal force is suppressed, and since there is no cantilevered portion in the unbalanced portion, bending moment due to whirling is also prevented from occurring. Further, since the number of bearing parts is three, the drive loss for driving the balancer shaft can be relatively small.

Particularly, according to the present invention, the mold opening of the unbalanced part is set to the one between the first and third bearing parts and between the second and third bearing parts, where the dimension between the bearing parts, that is, the longer span is shorter. By distributing the data so that it is larger than , the following problems can be avoided.

That is, when the balancer shaft 1~ rotates, especially when rotating at high speed, the shaft is bent due to the centrifugal force generated due to the eccentric rotation of the unbalanced part, but in this case, the weight of the unbalanced part is If (1) is evenly distributed over both spans, as shown in simplified form in FIG. Even if the maximum deflection m in both spans up to the bearings 71 and 72 on both sides is equal, or the longer span is somewhat larger, each deflection angle on both sides of the journal section of the third bearing section 73 Regarding α1 and α2, the deflection angle α1 on the longer side of the span is smaller than the deflection angle α2 on the shorter side. In that case, an oil clearance is provided between the bearing hole 83 and the journal part in the third bearing part 73 in order to generate a desired oil film, but the deflection angles α1 and α2 are different as described above. In addition, when the difference between the two exceeds a certain limit, a so-called partial contact occurs in which the journal portion and the bearing hole 83 come into contact or layer contact only on the short side of the span, as shown by the symbol X in the figure. Due to this, IFJ wear or abnormal wear, as well as seizure, etc. occur in the third bearing portion 73. Also. Even when the rigidity of the journal part is increased so that the journal part itself hardly flexes, uneven contact may occur in the same manner as in the above case, as shown in FIG. This causes various problems such as wear and tear.

However, according to the present invention, as described above, [t of the unbalanced portion is distributed such that it becomes larger in the longer span, so that the maximum deflection amount in the longer span is equal to the deflection amount in the shorter one. is relatively increased compared to the 6th
Since the deflection angles α1 and α2 shown in the figure are approximately equal, problems such as uneven contact as described above are solved.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

This embodiment relates to an in-line four-cylinder 4→1 cycle engine, and is intended to deal with secondary vibrational force due to inertia of reciprocating parts such as pistons.

As shown in FIG. 1, a cylinder block 11 of an engine 10 is provided with a partition wall 12 between adjacent cylinders, and a crankshaft 13 is arranged in the center of the skirt portion of the cylinder block 11 in the direction of the cylinder row. has been done. This crankshaft 13 has each crank journal section supported by a main bearing 15 which is made up of the above-mentioned partition walls 12, end walls (not shown) at both ends of the cylinder block, and bearing latches 14 attached to these walls. Although not shown, the pistons of each cylinder are connected to a crank bin provided at an eccentric position via a crank arm via a connecting rod. Further, the cylinder block 11 of the engine 10 is provided with a pair of left and right balancer shafts 30,30. These balancer shafts 30, 30 are supported parallel to and symmetrically with the crankshaft 13 above the top on both left and right sides of the crankshaft 13, and are driven by the crankshaft 13 through a drive mechanism (not shown). The shift 1
They are driven in opposite directions to each other at twice the rotational speed of 3.

Next, the configuration of this balancer shaft 30 and the bearing structure of this qt shaft 30 will be explained with reference to FIG. An extension shaft part 32 is connected to one end of the balance part 31, and a first journal part 33 is provided at the end of the extension shaft part 32. A second journal portion 34 is provided at the side end portion, and a third journal portion 35 is provided at the intermediate portion of the unbalanced portion 31, respectively. The unbalanced portion 31 is disposed on the side of the second and third cylinders 102 and 103 in the central portion in the longitudinal direction of the engine 10, and the first journal portion 33 is disposed on the fourth cylinder 104 side of the cylinder block 11. The second V-nal portion 34 is further inserted into the second bearing hole 18 formed in the partition wall 121 between the first and second cylinders 101 and 102. The third journal section 35 is the second journal section. They are rotatably fitted into the third bearing holes 19 formed in the partition wall 122 between the third cylinders 102 and 103 via bearing metals 20, 21 and 22, respectively, whereby the first to third bearing parts 1.
I[, If[ are configured.

A protruding shaft portion 36 that protrudes from the cylinder block end wall 16 is provided at the end of the balancer shaft 30 on the first journal portion 33 side, and a drive mechanism between the shaft portion 36 and the crankshaft 13 is provided. Constituent gear 3
7 is fixed.

Here, the end wall 16 of the cylinder block 11 and the partition wall 1
21, 122 are provided with oil passages 24, 25° 26 led from the oil gear gallery 23 shown in FIG. The first to third journal parts 33, 34.35 in Il, m and the first to third bearing holes 17, 18.19 (bearing metal 20) into which these journal parts are fitted.
, 21, 22), and the ends of each of the oil passages 24, 25, 26 that open to the outer surface of the cylinder block are provided with blind plugs 27...・Closed by 27. Further, the end wall 16 and the partition wall 122 have first and third bearing portions 1. A baffle 28° 28 is provided to cover the I

This is to prevent oil flowing out from (2) from scattering into the cylinder block 11 and becoming oil mist.

However, the weight of the unbalanced portion 31 of the balancer shaft 30- is distributed as shown below.

That is, the axis of the first unbalanced part 311 located at the longer span between the first and third journal parts 33.35 and the second and third journal parts 34.35 of the balancer shaft 30. The direction length Ll is made longer than the length L2 of the second unbalanced portion 312 located on the shorter side of the span, and in addition to this, the first and second unbalanced portions 3.1
Since the cross-sectional areas of 1.312 are made equal for both, the ff1ffi of the first unbalanced portion 311 is larger than that of the second unbalanced portion 312 by a predetermined amount.

Note that the outer peripheral surface of the third journal portion 35 and the bearing metal 2
An oil clearance is provided between the inner circumferential surfaces of No. 2 (the same applies to the first and second bearing parts, No. 2) in order to generate a desired oil film.

Next, the operation of this embodiment will be explained.

First, when the engine 10 is operating, a secondary excitation force is generated by the inertia force acting on the reciprocating parts such as the piston and piston pin, and this excitation force is generated by the pair of left and right balancer shafts 30 and 30. It is canceled as follows. That is, these balancer shafts 30.3
0 are arranged symmetrically and are driven in mutually opposite directions at twice the rotation speed of the crankshaft 13,
Unbalanced portion 31 of both balancer shafts 30.30.
The resultant force of the centrifugal force acting on the crankshaft 13 fluctuates in the vertical direction with a period that is half the rotation period of the crankshaft 13. Therefore, by appropriately setting the phases of the crankshaft 13 and both balancer shafts 30.30, it is possible to prevent the centrifugal force acting on the unbalanced portion 31.31 when the excitation force due to the inertial force of the reciprocating portion is directed upward. 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 that case, since both balancer shafts 30.30 are arranged symmetrically and driven in opposite directions at the same speed, new Since the unbalanced portion 31 31 is located approximately at the center in the longitudinal direction of the engine 10, the unbalanced portion 31
．． No pitching moment is generated due to the centrifugal force acting on the engine 31, and in this way the vibrations of the engine 10 are reduced.

However, in this type of balancer shaft, a bending moment is generated due to the centrifugal force acting on the unbalanced portion, and this bending moment acts as a load on the bearing portion. The middle part of the unbalanced part 31 is made up of the third journal part 35 at the middle part of the unbalanced part 31 and the third bearing hole 19 (bearing metal 22) into which the journal part 35 is fitted. is supported, the bending moment acting on the unbalanced portion 31 is suppressed, and the load acting on the first and second bearing portions I and II at both ends of the shaft 30 is reduced. Moreover, since the second bearing part (2) is provided at the end of the unbalanced part 31 on the extended shaft part side, the second bearing part (2) of the unbalanced part 31 is
, the portion between the third journal portions 34 and 35 swings around, and there is no possibility that a large load will be applied to the third @receiving portion (■).

In particular, in this balancer shaft 30, between the first and third journal parts 33.35 and between the second and third journal parts V-
Since the first unbalanced part 311 located at the longer span between the null parts 34 and 35 is heavier than the second unbalanced part 312 located at the shorter span, the system When the shaft 30 rotates, especially when rotating at high speed, the centrifugal force generated due to the eccentric rotation of the unbalanced part 31 causes the shaft 30 to pivot on the first, second, and third bearing parts, ■, and ■. When the journal portion 35 of the third bearing portion (2) is bent as shown in FIG.

That is, when the balancer shaft 30, which is formed to have different span lengths as described above, is bent, the first and second
Assuming that [1] of the unbalanced portions 311 and 312 are evenly distributed, the deflection angles on both sides of the third journal portion 35 are different (the first unbalanced portion 311 side is closer to the second unbalanced portion 312 However, according to the present invention, according to the present invention,
As described above, since the weight of the first unbalanced part 311 is increased by a predetermined amount, the first and second unbalanced parts 311.3 as shown by solid lines in FIG.
The deflection angles 01 and θ2 of 12 are the same or approximately the same. As a result, the third internal portion 35 can be well held by the third bearing hole 19 or the bearing metal 22 while ensuring oil clearance to generate a desired oil film on the peripheral surface thereof. As shown by the chain line in the same figure, the journal portion 35 and the bearing metal 22 are in a one-sided contact state due to the difference in the deflection angles of the two, and this third
Problems such as uneven wear and seizure occurring in the bearing part (2) can be avoided.

Further, in this embodiment, the first unbalanced section 31
By reducing the cross-sectional area over the length of the unbalanced part 31 by the length of 1, the II of the entire unbalanced part 31 is set to the required ■. This also results in the effect of improving load distribution.

In addition, FIG. 4 shows another embodiment of the second bearing part, and in this embodiment, the bearing hole 18' in (1) in the second bearing part ■' penetrates to the outside of the cylinder block 11'. At the same time, a blind plug 29' is attached to this penetrating portion.

By the way, according to such a bearing structure, the bearing hole 18'
Since a closed space a is formed on the side of the plug 29', the oil passage 25' is connected to the journal part 34' and the bearing metal 2.
The lubricating oil supplied between the cylinder block 11' and the cylinder block 11' flows only into the internal space of the cylinder block 11' on the side opposite to the plug, and the lubricity for the portion of the bearing surface on the plug 29' side deteriorates. . Therefore, in this embodiment,
The journal portion 34 in the balancer shaft 30'
A communicating hole 38' passing through in the axial direction is provided in the chain hole 38'.
This allows the space a to communicate with the internal space of the cylinder block 11' so that the lubricating oil supplied to the bearing portion flows equally into both spaces a and b.

(Effects of the Invention) As described above, according to the present invention, in an engine in which a balancer shaft having an unbalanced portion is driven by a crankshaft to reduce photographing, the number of bearing portions is unnecessarily increased. This makes it possible to effectively suppress the bending moment caused by the centrifugal force acting on the unbalanced part, and especially when the span lengths on both sides of the bearing provided in the middle of the unbalanced part are different. In this case, the deflection angles of the unbalanced portions on both sides of the bearing portion are equalized, and uneven contact occurring in the bearing portion is prevented. This prevents significant wear and seizure in each bearing portion (particularly the bearing portion in the middle of the unbalanced portion), thereby improving the durability of the bearing structure of this type of balancer shaft.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of the main part of an engine showing an embodiment of the present invention, and FIG. 2 is an enlarged view of the main part taken along the line I [-ff]. FIG. 3 is an enlarged cross-sectional plan view of the main part showing the operation of the above embodiment, FIG. 4 is a cross-sectional plan view of the main part showing the embodiment of the bearing part, and FIGS. ) is a schematic diagram showing a conventional bearing structure of a balancer shaft, and FIGS. 6 and 7 are schematic explanatory diagrams exaggerating the conventional problems. 10...Engine, 13...Crankshaft, 3
0... Balancer shaft, 31... Unbalanced part, 32... Extension shaft part, 1-■... First to third bearing parts. Figure 5 Figure 6

Claims (1)

[Claims] (1) A balancer shaft for an engine that is disposed parallel to a crankshaft, is driven by the crankshaft, and has an unbalanced part, the unbalanced part being disposed at the center in the longitudinal direction of the engine. , an extension shaft part is connected to one end side of the unbalanced part and connected to the drive mechanism, and a first bearing part is provided at the end of the extension shaft part, and a first bearing part is connected to the end side of the unbalance part opposite to the extension shaft part. A second bearing part is provided at the end of the unbalanced part, and a third bearing part is provided in the middle part of the unbalanced part, and between the first and third bearing parts and between the second and third bearing parts. A balancer shaft for an engine, characterized in that the weight of the unbalanced portion is greater in the longer dimension between the bearing portions than in the shorter dimension.