JPH0212344Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an engine balancer device.

[Conventional technology]

In vehicle engines, for example, the rotational balance is unbalanced due to the secondary inertia force generated by the reciprocating movement of the piston in the vertical direction, and this causes vertical vibration in the engine. In this way, two balancer shafts with balance weights are supported eccentrically at the lower end of the cylinder block, and these are rotated in opposite directions by the rotational force of the crankshaft, thereby suppressing engine vibration. It is. However, in this case, there is a problem in that the balance weight is located below the oil level in the oil pan, and the oil acts as rotational resistance of the balancer shaft, resulting in output loss.

Therefore, conventional balancer devices include, for example,
As shown in Japanese Patent No. 36-24901, there is a balancer shaft in which a thin cylindrical member is attached to reduce rotational resistance due to oil.

[Problem that the invention attempts to solve]

However, in the device described in the above-mentioned conventional publication, for example, when this device is installed in a four-cylinder engine, the balancer shaft and the cylindrical member rotate at high speed, such as requiring two revolutions of the balancer shaft for one revolution of the crankshaft. Centrifugal force acts on the cylindrical member, deforming the cylindrical member, which rotates in oil, creating rotational resistance for the balancer shaft, and deformation caused by centrifugal force causes the cylindrical member to separate from or hit the balancer shaft. There were problems in terms of durability, such as dripping or hitting the other cylindrical member.

In view of these problems, this invention aims to provide an engine balancer device that can reliably reduce the rotational resistance of the balancer shaft and guarantee durability.

In the above engine balancer device, another method for reducing the rotational resistance of the balancer shaft is to attach a semi-cylindrical lightweight member to the semi-circular cross section of the balancer shaft. However, with this method, the flat surface of the semicircular cross-sectional part of the balancer shaft is not flush due to manufacturing errors, etc., and there are variations, and due to these variations, it is difficult to securely attach the lightweight member to the balancer shaft. Since the balancer shaft and the lightweight member cannot be fixed together, it is necessary to form the mating surfaces of the balancer shaft and the lightweight member with high precision.

[Means for solving problems]

Therefore, in an engine balancer device, a protruding stepped portion is provided along the entire length of the balancer shaft along the axial direction on both side edges perpendicular to the axial direction of the plane portion of the balancer shaft having a substantially semicircular cross section. A concave stepped portion is provided on both sides of a plane of a lightweight member having a substantially semi-cylindrical shape, and the pair of protruding stepped portions of the balancer shaft are fitted into the stepped portions, and the balancer shaft is attached using a bolt. A predetermined gap is provided between the flat surface of the shaft and the lightweight member by interposing a protrusion into which the bolt is inserted.

[Effect]

In this invention, protruding step portions are provided along the entire length of the shaft flat portion along the axial direction on both side edges perpendicular to the axial direction of the flat portion of the balancer shaft, which has a generally semicircular cross section. A concave stepped portion is provided on both sides of the plane of the columnar lightweight member,
A pair of protruding stepped portions of the balancer shaft are fitted into the stepped portions and attached using bolts, and
Since the protrusion through which the bolt is inserted is interposed between the flat part of the balancer shaft and the lightweight member to provide a predetermined gap, the rotational resistance of the balancer shaft is reduced and the torsional rigidity of the shaft is increased. Durability is also improved, variations in the mating surfaces of the balancer shaft and the lightweight member are absorbed by the gap between them, and positioning when installing the balancer shaft and the lightweight member is facilitated, improving ease of assembly.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 3 show an engine balancer device according to an embodiment of the present invention. In the figure, 1
is a cylinder block of an engine, a crankshaft 3 is supported on a crankcase 2 of the cylinder block 1, and a connecting rod 4 connects the cylinder block 1 to the crankshaft 3.
An inner piston (not shown) is connected thereto, and an oil pan 5 is provided below the cylinder block 1, and an oil strainer 6 is provided within the oil pan 5.

Further, a balancer device 7 is provided below the cylinder block 1. This balancer device 7
, a balancer shaft case 8 is attached to the crankcase 2 of the cylinder block 1 so as to bridge between both sides of the lower end surface of the crankcase 2, and two balancer shafts 9 are installed within the balancer shaft case 8 (however, one is not shown in the figure). (Only the book is shown) is rotatably supported via a metal 8a, and the balancer shaft 9 is provided with a balance waist portion 9a having a semicircular cross section. A gear case 10 is attached to one end of the balancer shaft case 8, and a drive gear 11 is housed in the gear case 10. It meshes with the drive gear 12 fixed to the
As a result, one balancer shaft 9 is driven in conjunction with the crankshaft 3. Further, a gear device 13 is provided on the other end side of the crankshaft case 8 for transmitting the rotation of the crankshaft 3 to the other balancer shaft 9.

In the balancer device 7, the balancer shaft 9 is provided with a semi-cylindrical lightweight member 14. That is, the balancer shaft 9
A stepped portion 15 is provided on both sides of the mating surface, which is a flat surface, of the balance weight portion 9a, extending over the entire length of the balance weight portion 9a, while a lightweight member 14 is provided on both sides of the mating surface, which is a flat surface of the lightweight member 14. A stepped portion 16 is recessed over the entire length, and protrusions 17 having bolt holes are formed at appropriate locations on the mating surface of the balance weight portion 9a.
5 and 16 are fitted together, and the bolt 18 inserted through the lightweight member 14 is screwed into the bolt hole of the protrusion 17, whereby the lightweight member 14 is attached to the balancer shaft 9.
They are attached to each other with a predetermined gap 19 between their mating surfaces.

Next, the effects will be explained.

When the engine operates, the crankshaft 3 rotates, and the rotation is transmitted to one balancer shaft 9 via the drive gears 12, 11, and further transmitted to the other balancer shaft 9 via the gear device 13, thereby Both balancer shafts 9 are rotated in opposite directions, and vertical vibrations caused by secondary inertia of the engine are suppressed.

At this time, the lightweight member 14 is attached to the balance weight part 9a of the balancer shaft 9, and the cross-sectional shape of the balancer shaft 9 is approximately circular when viewed as a whole, so the rotation of the balancer shaft 9 is very smooth. be.

In the apparatus of this embodiment as described above, since the balancer shaft is provided with a lightweight member and has a cylindrical shape, rotational resistance due to oil can be significantly reduced.

In addition, since this device is provided with a lightweight member, the amount of deformation of the lightweight member due to centrifugal force is smaller than when a thin cylindrical member is used as in the device described in the above-mentioned conventional publication, and as a result, the rotational resistance mentioned above is reduced. Furthermore, there is almost no contact between the lightweight members or between the lightweight members and the balancer shaft, thus ensuring durability.

In addition, in this device, the stepped portion of the lightweight member mating surface is brought into contact with the stepped portion of the balancer shaft mating surface to fix the two, and a gap is created by interposing a protrusion through which a bolt is inserted between both mating surfaces. Therefore, it is possible to prevent large deformation of lightweight members when tightening bolts, and increase the tightening strength.
Variations in the mating surfaces of the balancer shaft and the lightweight member can be absorbed by the gap, and there is no need to form the mating surfaces with high precision.

Furthermore, in this device, the step on the balancer shaft mating surface is fitted with the step on the lightweight component mating surface, making positioning easier when installing lightweight components and improving assemblage. It is possible to suppress outward deformation of the lightweight member due to centrifugal force, and this also ensures reduction in rotational resistance and durability.

Furthermore, the torsional rigidity of the balancer shaft can be improved by the protruding step portions provided on both side edges of the balancer shaft plane portion.

[Effect of idea]

As described above, according to the engine balancer device according to the present invention, the balancer shaft, which has a substantially semicircular cross section, extends along both side edges perpendicular to the axial direction of the planar portion over the entire length of the shaft planar portion. A projecting step is provided, and a concave step is provided on both sides of the planar surface of the approximately semi-cylindrical lightweight member, and the pair of projecting steps of the balancer shaft are fitted into the step. At the same time, a predetermined gap is provided between the plane part of the balancer shaft and the lightweight member by interposing the protrusion through which the bolt is inserted, so that the rotational resistance of the balancer shaft can be reduced, and the torsion of the shaft can be reduced. Rigidity and durability can be improved, variations in the mating surfaces of the balancer shaft and the lightweight member can be absorbed by the gap between them, and positioning when installing the balancer shaft and the lightweight member can be facilitated, improving ease of assembly.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an engine balancer device according to an embodiment of the present invention, FIG. 2 is a cross-sectional side view of a main part of the device, and FIG. 3 is a cross-sectional view taken along the line -- in FIG. 2. DESCRIPTION OF SYMBOLS 1... Cylinder block, 7... Balancer device, 9... Balancer shaft, 9a... Balance weight part, 14... Light weight member, 15... Step part,
19...Gap.

Claims (1)

[Scope of utility model registration request] In a balancer device for an engine, which has a balancer shaft that is rotatably supported and includes a balance weight, and in which the balancer shaft is driven in conjunction with a crankshaft, in a plane part of the balancer shaft having a substantially semicircular cross section. Protruding step portions are provided along the axial direction on both side edges perpendicular to the axial direction over the entire length of the shaft plane portion, and concave step portions are provided on both side edges on the plane of the approximately semi-cylindrical lightweight member. and a pair of protruding steps of the balancer shaft are fitted together and attached using bolts, and a protrusion through which the bolts are inserted is interposed between the plane part of the balancer shaft and the lightweight member to form a predetermined gap. An engine balancer device comprising: