JPH0570733B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a balancer that can eliminate high-order unbalanced forces generated by reciprocating masses when driving a reciprocating engine and prevent engine vibration. It is related to the device.

[Prior Art] Forces that cause the reciprocating engine to vibrate when the engine is driven include an unbalanced inertia force and an unbalanced moment due to the reciprocating mass. BACKGROUND ART Conventionally, in order to prevent engine vibration, devices have been proposed that eliminate unbalanced inertia force among the unbalanced forces. For example, as shown in Fig. 3, this device is equipped with a pair of balancers M, M at approximately symmetrical positions with respect to the cylinder axis Z, and rotates the same pair of balancers M, M at twice the crank rotation speed. The unbalanced inertial force caused by the reciprocating mass is eliminated by rotating the reciprocating masses in opposite directions.

In the case of a single cylinder as shown in FIG. 3, the unbalanced inertia force Frec generated during driving can be expressed by the following equation (1).

Frec≒mrω ² (cosωt+1/ρcos2ωt−1/4ρ ³ cos4
ωt +……) …(1) However, in equation (1) and Figure 3, m is the reciprocating mass,
r is the crank radius, ω is the crank rotation angular velocity,
is the conrod length, and ρ=/r is the conrod ratio.

Considering the case where such a single cylinder constitutes a 4-cylinder series engine with a crank arrangement as shown in Fig. 4, the unbalanced inertia force Frec generated when this engine is driven is equal to the unbalanced inertia force Frec generated by each cylinder. Since it is the resultant force of the equilibrium inertia force, it can be obtained by substituting the crank angles ωt, ωt+π, ωt+3π, and ωt+2π of each cylinder into equation (1) and composing them. however,
In equation (1), ρ is usually 3 to 4, and terms after 1/ρ ³ are considered to have little influence, so the unbalanced inertia force generated by this 4-cylinder series engine is the lowest order, the second order. can be represented by That is, the unbalanced inertial force Frec can be expressed by the following equation (2).

Frec≒4mrω ² 1/ρcos2ωt (2) FIG. 5a is a graph showing the phase of this unbalanced inertial force Frec.

Here, if the above-mentioned device is used to generate an inertial force having the same amplitude and opposite phase as the force expressed by equation (2), the adverse effects of the unbalanced inertial force can be eliminated. That is, the masses and rotation radii of the balancers M, M are appropriately set according to the reciprocating mass m of the engine, etc., and the balancers M, M are rotated in mutually opposite directions at twice the rotation speed of the crankshaft. It is sufficient to cause the engine to generate a force in the opposite direction to the force generated by a reciprocating piston or the like.

[Problems to be Solved by the Invention] In the reciprocating engine as described above, in addition to the unbalanced inertia force, an unbalanced moment due to the reciprocating mass is generated. The unbalanced moment T generated in a single cylinder is generally expressed by the following equation (3).

T≒mr ² ω ² (1/4ρsinωt−1/2sin2ωt−3/4
ρsin3ωt −...) ...(3) Then, if the unbalanced moment generated in the above-mentioned four-cylinder engine is represented by the lowest order, which is the second order, it can be expressed by the following equation (4).

T≒−2mr ² ω ² sin2ωt ...(4) However, the meanings of the symbols are the same as in equation (1). In addition,
FIG. 5b is a graph showing the phase of this unbalanced moment T.

However, since the conventional device described above cannot generate a moment, it is not possible to eliminate the unbalanced moment T shown in equation (4) above.
There was a problem in that engine vibration due to unbalanced force could not be completely prevented.

[Object of the Invention] The purpose of the present invention is to provide a small-sized balancer device with a simple structure, which can balance both unbalanced inertia force and unbalanced moment to prevent vibrations of a reciprocating engine. There is.

[Means for Solving the Problems] A balancer device for a reciprocating engine according to the present invention is provided at positions below the left and right sides of the crankshaft so as to be parallel to the crankshaft and symmetrical with respect to the axis of the piston. Two balancer shafts are rotated in opposite directions at a rotation speed corresponding to the order of the high-order unbalanced force to be caused, a first moment correction balancer is fixed to one balancer shaft, and the other balancer shaft is rotated in opposite directions. a second moment correction balancer rotatably provided with respect to the balancer shaft and rotated in the same direction as one of the balancer shafts; It is characterized by comprising a pair of inertia force correction balancers, each of which is fixedly installed.

[Operation] While driving the reciprocating engine, both balancer shafts are rotated in opposite directions at a rotation speed set according to the order of the unbalanced force to be balanced. The inertia force correction balancers fixed to both balancer shafts generate a force opposite to the unbalanced inertia force generated in the reciprocating direction of the engine, and this force balances the unbalanced inertia force. Since the two inertial force correction balancers rotate in opposite directions, the forces acting in the direction perpendicular to the above-mentioned force are always balanced. Also the first
The moment compensating balancer rotates in the same direction as one of the balancer shafts, and the second moment compensating balancer rotates in the opposite direction to the other rotating balancer shaft, i.e., in the same direction as the first moment compensating balancer. It's rotating. Both moment correction balancers are
A moment is generated by a component of the force acting on both moment correction balancers that is parallel to the reciprocating direction of the engine, and this moment balances the fluctuating unbalanced moment of the reciprocating engine.

[Example] A reciprocating engine to which the balancer device of this example is applied is a four-cylinder series engine as described in the section [Prior Art]. In FIGS. 1 and 2, the center axes of the cylinders of the reciprocating engine (not shown) are parallel to the Z-axis, and the cylinders are arranged side by side in the y-z plane with the centers in the side-by-side direction aligned with the z-axis. has been done. That is, the crankshaft C of this reciprocating engine is y
It is assumed to be parallel to the axis.

At a lower position of the reciprocating engine, two balancer axes O ₁ and O ₂ are arranged parallel to each other in the xy plane so as to be symmetrical with respect to the yz plane. Both balancer shafts O ₁ and O ₂ are rotatably supported by a support portion 1 that is integrally formed with the case of the engine. One balancer shaft _O1 is interlocked and connected to the crankshaft C of the engine by a driving force transmission means (not shown), and in this embodiment rotates in the opposite direction to the crankshaft at twice the rotation speed of the crankshaft. It is becoming more and more common. The other balancer shaft O ₂ is interlocked and connected to the one balancer shaft O ₁ by a driving force transmission means (not shown), and both balancer shafts
O ₁ and O ₂ are configured to rotate at the same rotation speed in opposite directions.

A cylindrical first moment correction balancer 2 is fixed approximately at the center of one balancer axis _O1 . A cylindrical second moment correction balancer 3 is provided approximately in the center of the other balancer shaft O ₂ so as to be rotatable with respect to the shaft and to be restricted from moving in the axial direction. Gear parts 2a and 3a are provided at the side ends of both moment correction balancers 2 and 3, respectively.
is provided. An intermediate gear 4 is rotatably provided between both gear parts 2a and 3a.
The first moment correction balancer 2, which is rotated in the opposite direction to the crankshaft C, is configured to be able to rotate the second moment correction balancer 3 in the same direction and at the same rotation speed. Note that the interlocking mechanism for both the moment correction balancers 2 and 3 may be other than a gear mechanism, such as a chain. Further, as shown in FIG. 2a, the weight portions m _A and m _A of both moment correction balancers 2 and 3 are configured such that their mounting positions in the respective rotational directions differ from each other by 180 degrees.

Cylindrical inertia force correction balancers 5 and 6 are fixed to both the balancer shafts O ₁ and O ₂ on both sides of the moment correction balancers 2 and 3, respectively. Each weight part of the inertia force correction balancers 5 and 6 provided two each on both balancer axes O ₁ and O ₂
m _B is configured to always be at a symmetrical position with respect to the yz plane.

Next, the operation of the above configuration will be explained.

A 4-cylinder series engine is driven to rotate the crankshaft C at an angular velocity ω. By the driving force transmission means, one balancer shaft _O1 is rotated at an angular velocity of 2ω in the opposite direction to the crankshaft C, and the other balancer shaft
O ₂ is rotated in the same direction as the crankshaft C at an angular velocity of 2ω. As shown in FIG. 2b, an inertial force of m _B r _B (2ω)2 acts on the weight portion m _B of each of the rotating inertial force correction balancers 5 and 6, respectively. weight part
The x-direction components of the inertial force acting on m _B cancel each other in opposite directions, and the resultant force Fz of the z-direction component is Fz=-2m _B r _B (2ω) ² cos2ωt ...(5). Since the phase of this force Fz is opposite to that of the graph of Frec shown in Figure 5a, here, Equation (2)
If the values of m, m _B , r, r _B , and ρ are set so that the sum of Frec shown in and Fz in equation (5) above becomes 0,
Vertical vibrations generated in the engine by the unbalanced inertial force Frec can be eliminated.

On the other hand, as shown in FIG. 2a, inertial forces F _{1 and F 2 of} m _A r _A (2ω) ² act on the weight portions m _A of both moment correction balancers 2 and 3, respectively. Inertial force F ₁
When is decomposed into both x and z direction components Fx _{1 and} Fz ₁ , Fx ₁ = m _A r _A (2ω) ² cos 2ωt, Fz ₁ = m _A r _A (2ω) ² sin 2ωt, and the inertial force F ₂ is x, z bidirectional components Fx ₂ , Fz ₂
Decomposed into Fx ₂ = m _A r _A (2ω) ² cos (2ωt + π) = −m _A r _A (2ω) ² cos2ωt Fz ₂ = m _A r _A (2ω) ² sin (2ωt + π) = −m _A r _A (2ω) ² sin2ωt. When the above component forces are combined, the forces Fx and Fz in both the x and y directions are as follows: Fx=Fx ₁ +Fx ₂ =0, Fz=Fz ₁ +Fz ₂ =0. That is, the moment correction balancers 2 and 3 do not generate unbalanced inertia forces in the x and y directions. Of each of the above component forces, the moment M
is caused only by the forces Fz ₁ and Fz ₂ in the z direction.

M=Fz ₁ ×L+Fz ₂ ×(−L) =m _A r _A (2ω) ² L sin2ωt +m _A r _A (2ω) ² L sin2ωt =2m _A r _A (2ω) ² L sin2ωt ...(6) Formula Since the moment M in (6) is in opposite phase to the graph of T shown in Figure 5b, the moment M shown in equation (4) is
m, so that the sum of M shown in equation (6) becomes 0.
It is sufficient to set the values of m _A , r, and r _A . In this way, the unbalanced moment T can be canceled out, and the vibrations generated in the engine by the moment T can be eliminated.

In the above explanation, only unbalanced inertia force and unbalanced moment were considered as causes of vibration in the engine. However, in reality, a moment due to combustion is also generated. The magnitude of the moment due to combustion varies depending on the load, and is thought to act in a direction to cancel the unbalanced moment. Therefore, in the above explanation, a moment M having the same amplitude and opposite phase as the unbalanced moment T is generated by the moment correction balancers 2 and 3, but in reality, the magnitude of the moment M is smaller than this. It may also be slightly smaller. That is, the unbalanced moment T, the moment due to combustion, and the moment M due to the correction balancer may be made to balance each other at a certain load depending on the operating condition of the engine.

According to the balancer device of the embodiment described above, the reciprocating mass of the 4-cycle series engine is
Since the following unbalanced inertial force and moment can be eliminated as much as possible, the vibrations generated by the engine during operation can be significantly reduced.
An engine equipped with such a balancer device can also be used in FRP ships, plants with strict vibration tolerances, and the like. Further, the balancer device of the above embodiment has a simple overall configuration, has small dimensions similar to those of the conventional device, and can be installed in the lower part of the engine.

In the embodiment described above, a 4-cycle series engine is used as the reciprocating engine, and the cause of vibration is mainly considered to be the secondary inertia force and moment due to the reciprocating mass. It can also be applied to engines and can generally be used to eliminate higher-order unbalanced inertia forces and moments.

[Effects of the Invention] The balancer device for a reciprocating engine according to the present invention has two balancer shafts that rotate at a predetermined rotation speed in opposite directions in the lower part of the reciprocating engine and are symmetrical with respect to the axis of the piston. Inertia force correction balancers are fixedly installed on both shafts, and the moment correction balancers respectively provided on both shafts are configured to rotate in the opposite direction to the crankshaft. Therefore, according to the present invention, the high-order unbalanced inertia force and moment generated in the reciprocating engine can be eliminated as much as possible, and the vibration of the engine can be prevented. Furthermore, as mentioned above, in the invention of this device, two types of balancers are provided on two balancer shafts in order to eliminate two types of forces, but these balancer shafts are symmetrical to each other with respect to the axis of the piston. Because of this arrangement, the balancer device can be accommodated within a small area, and the external shape of the entire reciprocating engine including the balancer device can be made compact.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the present invention viewed from the cylinder axis direction of the engine, Fig. 2a is an explanatory diagram of a moment correction balancer in the same embodiment, and Fig. 2b is an inertial force correction diagram in the same embodiment. An explanatory diagram of a balancer, Fig. 3 is an explanatory diagram of a conventional device, Fig. 4 is an example of a general crank arrangement in a 4-cycle series engine, and Fig. 5a is an unbalance that occurs in a 4-cycle series engine. Figure b is a phase diagram of the unbalanced moment generated in the engine. C...Crankshaft, O ₁ ...One balancer shaft,
_O2 ...Other balancer axis, 2...First moment correction balancer, 3...Second moment correction balancer, 5, 6...Inertia force correction balancer.

Claims (1)

[Claims] 1. Installed at the left and right lower positions of the crankshaft, parallel to the crankshaft and symmetrical to the axis of the piston. Two balancer shafts that are rotated, a first moment correction balancer that is fixed to one of the balancer shafts, and a first moment correction balancer that is rotatable relative to the other balancer shaft and rotates in the same direction as the one balancer shaft. and a pair of inertia force correction balancers respectively fixed to both balancer shafts so as to be in symmetrical positions with respect to the axis of the piston. Balancer device for reciprocating engines.