JP4296615B2 - Engine balancer lubrication structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lubrication structure for an engine balancer.
[0002]
[Prior art]
In general, in a four-cylinder engine, for example, due to a secondary inertia force generated by a reciprocating motion of a piston in the vertical direction, an imbalance occurs in the rotational balance of the crankshaft, and this causes vertical vibrations in the engine. For this reason, conventionally, an engine balancer has been provided which has two balance shafts provided with an eccentric balance weight and rotates the balance shafts in opposite directions by the rotational force of the crankshaft to suppress engine vibration. Various proposals have been put into practical use.
[0003]
An example of this type of engine balancer is disclosed in Japanese Utility Model Publication No. 62-28937. In this engine balancer, two balance shafts provided with eccentric balance weights are rotatably supported by a casing attached to a lower part of the cylinder block so as to be positioned in the oil pan, The casing is covered with a casing so that the oil stored in the cylinder and the oil flowing down from the cylinder block do not come into contact with each other. The casing is provided with an oil outlet for discharging oil stored in the casing after lubrication of the bearing portion of the balance shaft to the outside of the casing by the rotating balance shaft. It is located above the oil level. As a result, this conventional engine balancer attempts to reduce power loss by preventing oil agitation by the balance shaft (balance weight) while ensuring good lubrication of the bearing portion of the balance shaft.
[0004]
[Problems to be solved by the invention]
However, in the conventional engine balancer described above, the oil in the casing is to be discharged out of the casing by the rotation of the balance weight having a semi-cylindrical shape. There was a problem that the stirring resistance of the balance weight due to the stored oil could not be reduced and the power loss increased.
[0005]
Further, in the conventional engine balancer described above, a pair of gears fixed to each balance shaft and meshed with each other so as to rotate the balance shafts in opposite directions are immersed in the oil in the oil pan. Therefore, there is a problem that not only the gear agitation resistance by the oil in the oil pan is large, the power loss is increased, but also the bubbles are mixed into the oil.
[0006]
Therefore, an object of the present invention is to reduce power loss by reliably preventing oil agitation caused by rotation of the balance shaft while ensuring good lubrication of the bearing portion of the balance shaft.
[0007]
[Means for Solving the Problems]
The technical means taken in order to solve the above-mentioned problems include a housing attached to a lower part of a cylinder block so as to be positioned in an oil pan, a shaft rotatably supported in parallel with each other and a crank on one of the housings. A pair of balance shafts to which the rotational power of the shaft is transmitted; a balance weight provided eccentrically on the outer periphery of each balance shaft; and rotatable with the balance shaft in a weight chamber formed in the housing; and each balance A pair of gears that are respectively provided on the shaft and meshed with each other so that the balance shafts rotate in opposite directions by the rotational power of the crankshaft, and the bearing portion of the balance shaft is interposed via an oil passage In an engine balancer that is lubricated by the supplied oil, A cover is fixed to the housing so as to form a gear chamber for housing the gear with the housing, and a communication passage is provided in the housing for communicating the bottom of the weight chamber and the bottom of the gear chamber. The cover is provided with a discharge passage that communicates the gear chamber and the space above the oil level of the oil pan, and the oil flow in the oil pan flows backward to the discharge passage at the lower portion of the oil pan side opening of the discharge passage The shielding part which prevents is formed .
[0008]
According to the above-described means, the oil that has lubricated the bearing portion of the balance shaft is sucked into the gear chamber from the weight chamber through the communication passage by the rotation of the gear, and into the space above the oil level of the oil pan through the discharge passage. Discharged. As a result, while ensuring good lubrication of the bearing portion of the balance shaft, oil agitation due to rotation of the balance shaft is surely prevented and power loss is reduced.
[0009]
In the above-described means, the pair of gears may be helical gears, and a thrust force generated in the gears during rotation transmission may be regulated by the cover.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an engine balancer lubrication device according to the present invention will be described with reference to the drawings.
[0011]
In FIG. 1, an oil pan 12 for storing oil is fixed to a lower portion of a cylinder block 11 on which a crankshaft 10 is rotatably supported, and an engine balancer 20 is fixed so as to be positioned in the oil pan 12. ing. The cylinder block 11 is provided with an oil pump 15 that is driven by the engine and pumps the oil in the oil pan 12 sucked through the strainer 16 to each lubricating portion of the engine. The part is also supplied to the lubricating part of the engine balancer 20 as will be described later.
[0012]
As shown in FIG. 2, the engine balancer 20 has a housing 22 made of aluminum alloy, cast iron, or the like. The housing 22 extends in the longitudinal direction of the housing 22 and closes an upper opening thereof. The cover 37 (see FIG. 4) forms a recess 23a that defines the weight chamber 23 and two parallel support holes 24 and 25 that pass through the weight chamber 23 at right angles. Balance shafts 28 and 29 are rotatably supported in the support holes 24 and 25 through bearings 26a and 26b; 27a and 27b, respectively. One end side of each of the balance shafts 28 and 29 is one end surface of the housing 22. Protruding from. As shown in FIG. 4, flat portions 28a and 29a are formed in portions of the balance shafts 28 and 29 positioned in the weight chamber 23, respectively. Semi-cylindrical balance weights 40 and 41 are fixed to the flat portions 28a and 29a by bolts 42 and 43, respectively, so that the balance weights 40 and 41 are placed in the weight chamber 23 as the balance shafts 28 and 29 rotate. It is designed to be rotated.
[0013]
The balance shafts 28 and 29 are respectively formed with an axial passage 30 that passes through the axial center and opens at the other end, and an axial passage 31 that passes through the axial center and opens at both ends. The opening 31 is closed by plugs 34, 35 and 36, respectively. The balance shafts 28, 29 are formed with radial passages 32a, 32b; 33a, 33b that respectively connect the bearings 26a, 26b; 27a, 27b and the shaft holes 30; As shown in FIG. 5, the housing 22 is formed with an oil supply passage 38 that supplies a part of the oil pumped from the oil pump 15 to the bearings 26 a and 27 a. Thereby, the oil from the oil pump 15 is sequentially supplied to the oil supply passage 38 → the bearings 26a, 27a → the radial passages 32a, 33a → the axial passages 30, 31 → the radial passages 32b, 33b → the bearings 26b, 27b. Thus, the bearings 26a, 26b, 27a, 27b are lubricated well.
[0014]
In this embodiment, the balance shaft 28 is longer than the balance shaft 29 by a predetermined amount, and a helical gear 57 is fixed to one end of the balance shaft 29 protruding from one end surface of the housing 22. A helical gear 56 that meshes with the helical gear 57 is fixed to the outer periphery of the balance shaft 29 protruding from one end surface of the housing 22 so that the balance shafts are rotated in opposite directions. ing.
[0015]
As shown in FIGS. 2 and 3, the one end surface of the housing 22 is made of aluminum alloy, cast iron, or the like having a recess 51a that defines a gear chamber 51 that houses the gears 56 and 57 with the one end surface of the housing 22. A thrust cover 50 is fixed. The shape of the recess 51a is a shape corresponding to the helical gears 56 and 57 so that the clearances between the helical gears 56 and 57 have appropriate values. Further, in order to receive the thrust force generated by the helical teeth, a minute clearance of 0.1 mm or less is provided between the bottom surface of the recess 51a and the side surfaces of the helical gears 56 and 57.
[0016]
A through hole 58 through which one end of the balance shaft 28 passes is formed in the thrust cover 50, and the chain sprocket 21 is fixed to the tip end of the balance shaft 28 protruding from the thrust cover 50 by a nut 60. As shown in FIG. 1, the rotational power of the crankshaft 10 is doubled and transmitted to the chain sprocket 21 via the chain 14 and the crank sprocket 13, thereby each balance shaft. 28 and 29 are rotated in opposite directions (in the direction of the arrow in FIG. 3) through helical gears 56 and 57 at a rotational speed twice that of the crankshaft 10.
[0017]
As shown in FIGS. 3 and 5, the housing 22 is formed with a communication passage 39 that communicates the bottom of the weight chamber 23 with the gear chamber 51, and the gear chamber side opening of the communication passage 39 has a helical gear 56, It is located in the gear chamber space (gear chamber lower space) on the engagement start side with respect to the engagement portion 57. Note that the communication passage 39 is preferably formed to be inclined downward from the weight chamber 23 toward the gear chamber 51. The thrust cover 50 is formed in the space (gear chamber upper space) at the end of meshing with the meshing portions of the helical gears 56 and 57 of the gear chamber 51 so as to open at both longitudinal ends of the thrust cover 50. The discharge grooves 52 and 53 are communicated. These discharge grooves 52 and 53 form a pipe line with one end surface of the housing 22.
[0018]
As shown in FIGS. 1 and 3, protrusions 54 and 55 are integrally formed at the lower part of the external opening of the discharge grooves 52 and 53 of the thrust cover 50. These protrusions 54 and 55 prevent the oil level in the oil pan 12 when the maximum amount of oil is stored in the oil pan 12 in order to prevent the oil in the oil pan 12 from flowing into the gear chamber 51 (see FIG. 1), the thrust cover 50 is integrally formed by a mold when the thrust cover 50 is cast.
[0019]
In the present embodiment configured as described above, when the engine is operated, the rotational power of the crankshaft 10 is transmitted to the balance shaft 28 via the crank sprocket 13, the chain 14, and the chain sprocket 21, and the helical gears 56 and 57 are turned on. To the balance shaft 29. As a result, the balancer shafts 28 and 29 and the balance weights 40 and 41 rotate in directions opposite to each other, and the vertical vibration caused by the secondary inertial force of the engine is suppressed. During the engine operation, the oil stored in the oil pan 12 and the oil flowing down from the cylinder block 11 are prevented from flowing into the weight chamber 23 by the housing 22 and the cover 37.
[0020]
Therefore, in the present embodiment, as described above, a part of the oil pressure-fed from the oil pump 15 is transferred from the oil supply passage 38 → the bearings 26a, 27a → the radial passages 32a, 33a → the axial passages 30, 31 → The radial passages 32b and 33b are supplied in the order of the bearings 26b and 27b, so that the bearings 26a, 26b, 27a and 27b are well lubricated. Part of the oil supplied to the bearings 26 a, 26 b, 27 a, 27 b flows into the gear chamber 51 and into the weight chamber 23.
[0021]
Here, as described above, the oil that has flowed into the gear chamber 51 due to the pump action caused by the rotation of the helical gears 56 and 57 is discharged into the oil pan 12 through the discharge grooves 52 and 53 as the helical gears 56 and 57 rotate. Is done. The oil that has flowed into the weight chamber 23 is pushed out to the communication passage 39 as the balance weights 40 and 41 rotate, and at the same time, as the helical gears 56 and 57 rotate, the oil in the helical gears 56 and 57 passes through the communication passage 39. The air is sucked into the gear chamber space (gear chamber lower space) on the meshing side and is discharged into the oil pan 12 through the discharge grooves 52 and 53. The oil discharged from the discharge grooves 52 and 53 hits the inner wall of the oil pan 12 and is smoothly mixed with the oil level that undulates during engine operation without causing oil bubbles.
[0022]
As described above, in the present embodiment, the oil flowing into the weight chamber 23 can be surely forcibly discharged by the pumping action by the rotation of the helical gears 56 and 57, so that the bearing is lubricated in the weight chamber 23. It is possible to prevent an increase in power loss due to oil agitation resistance due to oil accumulation and rotation of the balance weight in the oil. Further, since the helical gears 56 and 57 are accommodated in the gear chamber 51 and do not rotate in the oil of the oil pan 12 to stir the oil, the power loss due to the oil stirring of the helical gears 56 and 57 increases. It is possible to prevent air bubbles from entering the oil and the oil temperature from rising.
[0023]
In this embodiment, since the helical gears 56 and 57 suitable for high-speed rotation are used, a thrust force acting in the axial direction on the helical gear during power transmission is received by the thrust cover 50 that forms the gear chamber 51. Further, it is not necessary to provide a separate stopper means for receiving the thrust force, and the configuration can be simplified. Lubrication between the thrust cover 50 that receives this thrust force and the side surfaces of the helical gears 56 and 57 is sufficiently performed by the oil discharged when the oil is discharged, but in order to further improve the lubricity, FIG. In this manner, radial lubrication grooves 72 may be provided on the side surface 71 of the helical gear 70. Since the helical gear is manufactured by sintering or forging a rough material, the lubricating groove can be formed at a low cost simultaneously with the manufacturing of the helical gear.
[0024]
【The invention's effect】
As described above, according to the present invention, the oil that has lubricated the bearing portion of the balance shaft is sucked into the gear chamber from the weight chamber through the communication passage by the pump action by the rotation of the gear, and the oil in the oil pan is discharged through the discharge passage. It can be discharged into the space above the liquid level. As a result, good lubrication of the bearing portion of the balance shaft can be ensured, and at the same time, oil that has lubricated the bearing portion is stored in the weight chamber, and the oil agitation resistance is increased by rotating the balance weight in the oil. It is possible to reliably prevent this and reduce power loss.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a lubricating structure of an engine balancer according to the present invention.
FIG. 2 is a cross-sectional view of the engine balancer shown in FIG.
3 is a cross-sectional view taken along the line AA in FIG.
4 is a cross-sectional view taken along the line BB in FIG.
FIG. 5 is a cross-sectional view taken along the line CC of FIG.
6 is a plan view showing a modification of the helical gear shown in FIG. 3; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Crankshaft 11 Cylinder block 12 Oil pan 15 Oil pump 20 Engine balancer 22 Housing 23 Weight chamber 26a, 26b, 27a, 27b Bearing 28, 29 Balance shaft 39 Communication path 40, 41 Balance weight 50 Thrust cover (cover)
51 Gear chamber 52, 53 Discharge groove (discharge passage)
54, 55 Protruding part (shielding part)
56, 57 Helical gear (gear)

Claims (2)

A housing attached to the bottom of the cylinder block so as to be located in the oil pan;
A pair of balance shafts that are rotatably supported by the housing in parallel with each other and to which the rotational power of the crankshaft is transmitted;
A balance weight that is eccentrically provided on the outer periphery of each balance shaft and is rotatable together with the balance shaft in a weight chamber formed in the housing;
Each of the balance shafts is provided with a pair of gears engaged with each other so that the balance shafts rotate in opposite directions by the rotational power of the crankshaft,
In the engine balancer in which the bearing portion of the balance shaft is lubricated by the oil supplied through the oil passage,
A cover is fixed to the housing so as to form a gear chamber for housing the gear with the housing, and a communication path is provided in the housing for communicating the bottom of the weight chamber and the bottom of the gear chamber. The cover is provided with a discharge passage that communicates the gear chamber and the space above the oil level of the oil pan ,
A lubricating structure for an engine balancer, wherein a shielding portion for preventing a reverse flow of oil in the oil pan to the discharge passage is formed at a lower portion of the oil pan side opening of the discharge passage . 2. The engine balancer lubricating structure according to claim 1 , wherein the pair of gears are helical gears, and a thrust force generated in the gears during transmission of rotation is restricted by the cover.

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