JP2005331006A - Balancer device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a balancer device capable of reducing vibration due to inertia force of a piston system reciprocating part without increasing dimension of an engine, in regard to an off-set cylinder type engine. <P>SOLUTION: In the engine arranged by off-setting an axis Ay of a cylinder 9 for guiding a piston 8 reciprocating with rotation of a crank shaft 5 to one side of an axis Ac of the crank shaft 5, an axis Ab of a guide shaft 13 for guiding a balance weight 11 reciprocating in a direction opposite to the piston 8 with rotation of the crank shaft 5 is arranged in parallel with the axis Ay of the cylinder 9 and to be off-set to the other side of the axis Ac of the crank shaft 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine in which an axis of a cylinder for guiding a piston that reciprocates in conjunction with rotation of a crankshaft is offset to one side of the axis of the crankshaft, and in particular, a reciprocating motion part in the engine. The present invention relates to a balancer device for reducing vibration due to inertial force.

Conventionally, a so-called offset cylinder type engine in which an axis of a cylinder for guiding a piston that reciprocates in conjunction with rotation of a crankshaft is offset to one side of the axis of the crankshaft is disclosed in, for example, Patent Document 1 below. Known to be disclosed.
JP 2002-227601 A

  In such an offset cylinder type engine, the way in which the inertial force of the piston reciprocating part comes out is different from that in a general engine in which the cylinder axis intersects the axis of the crankshaft. Technical guidelines have not yet been proposed for balancer devices that reduce the vibration.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a balancer device capable of effectively reducing vibration due to inertial force of a piston system reciprocating portion in an offset cylinder type engine and not causing an increase in size of the engine. .

  In order to achieve the above object, the present invention provides an engine in which an axis of a cylinder for guiding a piston that reciprocates in conjunction with rotation of a crankshaft is offset to one side of the axis of the crankshaft. The guide shaft axis that guides the balance weight that reciprocates in the opposite direction to the piston in conjunction with the rotation of the crankshaft is offset parallel to the cylinder axis and to the other side of the crankshaft axis. The first feature is that they are arranged.

  Further, in addition to the first feature, the present invention has a second feature that the balance weight is configured such that the center of gravity thereof is closer to the cylinder axis than the crankshaft axis.

  According to the first aspect of the present invention, the axis of the guide shaft for guiding the balance weight that reciprocates in the direction opposite to the piston is parallel to the cylinder axis and with respect to the crankshaft axis. By offsetting to the opposite side of the axis, the inertial force of the balance weight system reciprocating motion part is made to oppose the inertial force of the piston system reciprocating motion part, and it is generated in the engine due to the inertial force 1 Secondary vibration can be effectively reduced. In addition, since there are no overhangs on both sides of the balance weight that reciprocates along the guide shaft, it is possible to avoid an increase in the size of the engine due to the balance weight.

  Further, according to the second feature of the present invention, the piston reciprocation locus and the balance weight reciprocation locus are offset in opposite directions with respect to the axis of the crankshaft. The equilibrium couple can also be reduced.

  Embodiments of the present invention will be described based on preferred embodiments of the present invention shown in the accompanying drawings.

  1 is a longitudinal side view of an engine equipped with a balancer device according to the present invention, FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1, FIG. 3 is an enlarged cross-sectional view of the main part of FIG. FIG. 5 is an equivalent diagram of the engine, FIG. 6 is a diagram of inertial force between the comparative engine (A) and the engine of the present invention (B), and FIG. 7 is a comparative engine (A) and the main engine. It is an unbalanced couple diagram with an invention engine (B).

  First, in FIGS. 1 and 2, the engine E in the illustrated example is a four-cycle two-cylinder engine. The engine body 1 includes a crankcase 2 having a mounting flange 2A on the lower surface and horizontally supporting the crankshaft 4, a cylinder block 3 projecting obliquely upward from one side of the crankcase 2, and the cylinder block The cylinder head 4 is joined to the upper end surface of the cylinder. The crankcase 2 is composed of a case body 2a formed integrally with the mounting flange 2A and the cylinder block 3 and having one side opened, and a bearing bracket 2b bolted to the open side of the case body 2a. Both end portions of the crankshaft 5 are supported by the side walls of the case body 2a and the bearing bracket 2b via ball bearings 6 and 7, respectively. The crankshaft 5 includes a pair of left and right crankpins 5a, 5a having the same phase, and an auxiliary crankpin 5b disposed in the opposite phase to the crankpins 5a, 5a. A pair of cylinders 9, 9 arranged side by side in parallel with each other corresponding to 5 a, 5 a are formed in the cylinder block 3. The ignition timings in the cylinders 9 and 9 are set so as to be shifted from each other by 360 ° in crank angle.

  As shown in FIGS. 3 and 5, the cylinders 9 and 9 are arranged such that their axis Ay is offset by a predetermined distance δ above the axis Ac of the crankshaft 5. The crank pins 5a and 5a are connected to a pair of pistons 8 and 8 slidably fitted in the cylinders 9 and 9 via a pair of connecting rods 10 and 10, respectively.

  In this manner, offsetting the axis Ay of the cylinders 9 and 9 with respect to the axis Ac of the crankshaft 5 causes a decrease in the inclination angle of the connecting rods 10 and 10 at the maximum pressure in the expansion stroke of the engine E. As a result, the side thrust received by the pistons 8 and 8 from the inner surfaces of the cylinders 9 and 9 is reduced, and the sliding frictional resistance of the pistons 8 and 8 is reduced, thereby contributing to the improvement of output performance.

  In the crankcase 2, a balance weight 11 that reciprocates so as to exert an inertial force that opposes the inertial force of the reciprocating motion parts such as the pistons 8 and 8 is disposed. The balance weight 11 has a disk shape, and has a guide hole 12 that penetrates the balance weight 11 along the diameter line. A guide shaft 13 that is slidably fitted in the guide hole 12 is a crankcase 2. It is screwed to the peripheral wall. The guide shaft 13 is arranged such that its axis Ab is parallel to the axis Ay of the cylinders 9 and 9 and is offset from the axis Ac of the crankshaft 5 by a predetermined distance δ ′ on the side opposite to the axis Ay of the cylinders 9 and 9. Is done. The balance weight 11 is connected to the auxiliary crank pin 5b through an auxiliary connecting rod 14. That is, the small-diameter annular portion 14a formed at one end of the auxiliary crankpin 5b is fitted to the outer periphery of the auxiliary crankpin 5b so as to be relatively rotatable, and the large-diameter annular portion 14b formed at the other end is a disc-shaped balance. It is fitted to the outer periphery of the weight 11 so as to be relatively rotatable. The large-diameter annular portion 14b is provided with a long hole 17 penetrating the guide shaft 13 so that the swinging of the auxiliary connecting rod 14 around the balance weight 11 is not interfered with the guide shaft 13.

  In FIGS. 1 and 2 again, oil dippers 16 and 16 are formed at the large ends of the connecting rods 10 and 10, and these oils are stored in the bottom of the crankcase 2 as the crankshaft 5 rotates. The parts of the crankcase 2 are lubricated by being scattered, and oil holes 15 (see FIG. 4) for introducing the scattered oil into the guide holes 12 of the balance weight 11 are provided on the balance weight 11. Provided on both side walls.

  As shown in FIGS. 3 and 4, the balance weight 11 has crescent-shaped additional weight portions 11 a, 11 a protruding from both sides thereof, and these additional weight portions 11 a, 11 a are separated from the axis line Ac of the crankshaft 5. By offsetting the cylinders 9 and 9 toward the axis Ay, the center of gravity G of the balance weight 11 is offset from the axis Ac of the crankshaft 5 by a predetermined distance δ ″ from the axis Ay of the cylinders 9 and 9.

  Thus, when the pistons 8 and 8 are reciprocated along the cylinders 9 and 9, the reciprocating motions are converted into rotational motions by the connecting rods 10 and 10 and the crank pins 5a and 5a, and transmitted to the crankshaft 5. 5 is output to the outside as rotational power. The rotational movement of the crankshaft 5 is converted again into reciprocating movement via the auxiliary connecting rod 14 and auxiliary crankpin 5 b and transmitted to the balance weight 11. The balance weight 11 reciprocates along the guide shaft 13. To do.

  At that time, the crankpins 5a and 5a and the auxiliary crankpin 5b are in an opposite phase relationship, that is, there is a phase difference of 180 °, so that the reciprocating direction of the pistons 8 and 8 and the balance weight 11 The direction of motion is opposite to each other. Therefore, if the inertial force in the cylinder axis Ay direction of the reciprocating motion part of the pistons 8 and 8 system and the inertial force in the axis Ab direction of the guide shaft 13 of the balance weight 11 are balanced, the reciprocating motion of the pistons 8 and 8 etc. As a result, the primary vibration of the engine E that occurs with the engine can be eliminated.

  Based on FIG. 5, the balance between the inertial force in the cylinder axis Ay direction of the reciprocating motion part of the pistons 8 and 8 system and the inertial force in the axis Ab direction of the guide shaft 13 of the balance weight 11 is analyzed.

  The inertial force F in the cylinder axis Ay direction of the reciprocating part of the pistons 8 and 8 can be expressed by the following equation.

Where M is the mass of the reciprocating part of the piston 8 system L is the effective length of the connecting rod 10 R is the radius of rotation of the crankpin 5a λ is L / R
δ: Offset amount of the axis line Ay of the cylinder 9 with respect to the axis line Ac of the crankshaft 5 θ: Rotational angle of the crankpin 5a around the axis line Ac ω: Rotational speed of the crankshaft 5 (δ / R) sin θ is an inertial force generated more than a normal engine in which the axis Ay of the cylinder 9 is not offset with respect to the axis Ac of the crankshaft 5.

  On the other hand, the inertial force F ′ in the direction of the axis Ab of the guide shaft 13 of the balance weight 11 system can be expressed by the following equation.

However, M '... balance weight mass L' ... effective length of auxiliary connecting rod 14 R '... turning radius of auxiliary crank pin 5b λ' ... L '/ R'
δ ′: Offset amount of the axis Ab of the guide shaft 13 with respect to the axis Ac of the crankshaft 5 θ ′: Rotation angle of the auxiliary crankpin 5 b around the axis Ac As shown in the above two formulas, the balance weight 11 is reciprocated, that is, the axial line Ab of the guide shaft 13 is offset by a distance δ 'on the opposite side of the axial line Ay of the cylinder 9 with respect to the axial line Ac of the crankshaft 5, thereby obtaining two inertial forces F and F'. It is possible to counteract and reduce the primary vibration. The optimum value of the offset amount δ ′ is
δ ′ = − (L ′ / L) δ
It is.

  Further, by setting M ′ = M, λ ′ = λ, and θ ′ = θ, the two inertia forces F and F ′ can be perfectly balanced, and the primary vibration can be eliminated.

  FIG. 6A is an inertial force diagram when the reciprocating motion locus of the balance weight 11 is not offset from the axis Ac of the crankshaft 5, and it can be seen that the primary inertial force remains. On the other hand, FIG. 5B is an inertial force diagram in the embodiment of the present invention, and it can be seen that the primary inertial force becomes zero.

  By the way, since there are no overhangs on both sides of the balance weight 11 that reciprocates along the guide shaft 13, the engine E does not become specially large due to the presence of the balance weight 11.

  The center of gravity G of the balance weight 11 is offset from the axis Ac of the crankshaft 5 by a distance δ ″ on the side of the axis Ay of the cylinders 9, 9. The unbalanced couple generated in the entire engine E due to the offset of the reciprocating motion trajectory of the weight 11 with respect to the axis Ac of the crankshaft 5 can be reduced, and the optimum value is δ ″ = δ, so that the unbalanced couple can be made zero.

  FIG. 7A is an unbalanced couple diagram in the case where the center of gravity G of the balance weight 11 is set on the axis Ab of the guide shaft 13, and shows the unbalanced couple due to the reciprocating motion of the pistons 8 and 8 system. It can be seen that the unbalanced couple is added to the reciprocating motion of the balance weight 11 system, and a large unbalanced couple is generated in the entire engine E. On the other hand, FIG. 5B is an unbalanced couple diagram in the embodiment of the present invention, which is unsatisfactory for the unbalanced couple due to the reciprocating motion of the pistons 8 and 8 and the reciprocating motion of the balance weight 11 system. It can be seen that the equilibrium couple is balanced with each other, and that the engine E has almost no unbalance couple.

  The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the invention. For example, the present invention can be applied to a single cylinder engine. Of course, application to a two-cycle engine is also possible.

The longitudinal section side view of the engine provided with the balancer device concerning the present invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. The principal part expanded sectional view of FIG. FIG. 4 is a sectional view taken along line 4-4 of FIG. Equivalent line diagram of the engine. The inertial force diagram of a comparative example engine (A) and this invention engine (B). The unbalanced couple diagram of a comparative example engine (A) and this invention engine (B).

Explanation of symbols

E ... Engine 5 ... Crankshaft 8 ... Piston 9 ... Cylinder 11 ... Balance Weight 13 ... Guide Shaft Ac ... Crank Axis Ab of shaft 5... Axis Ay of guide shaft 13... Axis of cylinder 9

Claims (2)

The axis (Ay) of the cylinder (9) for guiding the piston (8) that reciprocates in conjunction with the rotation of the crankshaft (5) is offset to one side of the axis (Ac) of the crankshaft (5). In the deployed engine,
The axis (Ab) of the guide shaft (13) that guides the balance weight (11) that reciprocates in the opposite direction to the piston (8) in conjunction with the rotation of the crankshaft (5) is used as the cylinder (9). A balancer device for an engine, wherein the balancer device is arranged in parallel to the axis (Ay) of the crankshaft and offset to the other side of the axis (Ac) of the crankshaft (5). The engine balancer device according to claim 1,
An engine characterized in that the balance weight (11) has a center of gravity (G) located closer to an axis (Ay) of the cylinder (9) than an axis (Ac) of the crankshaft (5). Balancer equipment.

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