JPS6179039A - Balancer of 4-cycle single cylindered engine - Google Patents

Abstract

PURPOSE:To reduce rolling round a crankshaft in a simple structure by disposing a balance weight directly on a cam shaft of a 4-cycle single cylindered engine to form the primary/secondary balancer. CONSTITUTION:A crank gear 5 is coupled to a crankshaft 3 of a 4-cycle single cylindered engine, and a cam gear 7 coupled to a cam shaft 6 is engaged with the crank gear. A balance weight 8 is disposed directly on the cam gear having twice as many as teeth as the crank gear to form the primary/secondary balancer as a whole. Thus, rolling round the crankshaft depending upon a piston thrust force produced by combustion pressure can be reduced in a simple structure.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a balancer device for a four-stroke single-cylinder engine, and more particularly to a balancer device for reducing rolling vibration around the crankshaft direction due to combustion pressure in a four-stroke single-cylinder engine. This is related.

[Prior art] Balancer devices with various configurations have been proposed for engines in order to balance the inertial force of reciprocating masses such as pistons accompanying rotational drive of engines, and each proposal has its own effects. There are 1. Furthermore, even in single-cylinder engines, which is the field of application of the present invention, a balancer device that functions in the same way is used, for example, in Japanese Patent Application Laid-Open No. 49-5820.
There is a proposal for a device configuration described in Publication No. 4. Here, the prior art related to this proposal has a configuration in which a camshaft is attached to the crankshaft and these two shafts are rotated in conjunction with each other, and the balancer is rotatably supported on the camshaft. This balancer was rotated in the opposite direction of the crankshaft at the same speed by gear A7, which is different from the cam gear, thereby balancing and compensating for the primary inertial force caused by the forward motion of the piston, etc. . [Problems to be Solved by the Invention] However, in the case of the above-mentioned prior art, it is intended to obtain a counteracting effect of the primary tti force acting on the engine, and in such a conventional configuration, the 4-cycle Imaging reduction for rolling vibration (1/2 order) around the crankshaft that occurs once every two revolutions of the crankshaft in a single-cylinder engine, or the rolling moment around the crankshaft that occurs due to combustion pressure. The problem was that it was not possible to

[Purpose of the invention]

In view of the above-mentioned conventional problems, the present invention is designed to reduce rolling vibration around the crankshaft direction with a simple configuration of simply installing a balance weight directly on the camshaft to form a 1/2 balancer. The object of the present invention is to provide a balancer device for a four-stroke single-cylinder engine that is improved in this way.

[Configuration of the Invention] In order to achieve the above object, the present invention provides a crankshaft;
The crankshaft has a camshaft attached to the crankshaft, and the crank gear fixed on the crankshaft is meshed with the cam gear fixed on the camshaft.
In a configuration in which the camshaft is operated 1/2 rotation in the opposite direction with one rotation, a balance weight is installed on the camshaft so that the rotation occurs once every two rotations of the crankshaft. The rolling vibration moment around the crankshaft, which is blocked by the piston thrust force caused by the combustion pressure, is reduced by the rotational centrifugal force acting on the balance weight provided on the camshaft. [Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is an explanatory diagram showing the outline of the apparatus of this embodiment. In FIG. 1, reference numeral 1 is a cylinder, 2 is a piston, and 3 is a crankshaft connected to the piston 2 by a connecting rod 4, on which a crank gear 5 is fixed. 6 in the figure is a camshaft attached to the crankshaft 3 (1) i7, on which the crank gear 5 is attached.
A cam gear A77 that meshes with the cam gear A77 is fixed so that it can rotate 1/2 with one rotation of the crank gear 5, and a balance weight is mounted on the camshaft 6 to function as a 1/2 balancer. 8 is fixed. Therefore, the 62M condition for the balance weight 8 is such that the distance between the pivot point of the connecting rod 4 relative to the piston 2 and the rotation center of the crankshaft 3 at the maximum combustion pressure is 11. The distance from the rotation center of 6! , the piston thrust force is Fp due to the combustion pressure, and the rotational centrifugal force due to the balance weight 8 is
1), settings are made so that the relational expression Fpxl-=Ibxf holds true. That is, as a specific example of installing the balance weight 8 on the camshaft 6, as shown in FIG. A plurality of holes 8b are opened in the cleft so that the predetermined shape 11 is arranged ((2) and (b) in the same figure).
), or they may be attached to the camshaft 6 using separate members 8G arranged at a predetermined distance m ((C) in the same figure). Therefore, as a result, the balance weight 8 is operated integrally with the camshaft 6 by 1/2 rotation in a counterclockwise direction as the crankshaft 3 operates one rotation in a certain direction, and this balance weight The rotational centrifugal force acting on 8 is 17゛2
The second balancer is configured to cancel the rolling vibration moment around the crankshaft based on the piston thrust force caused by combustion pressure, which occurs once every two revolutions of the crankshaft 3, and the vibration that occurs when the engine rotates. can be reduced as much as possible. Here, the operating principle of the 1st, 72nd order balancer according to the device of the present invention described above is as follows. In other words, as shown in Figure 3, if there is a dynamic balancer on two axes that rotates at a constant speed with the crankshaft, and the camshaft is on the X-axis, the force around the y-axis (crankshaft) is The vibration moment My (clockwise direction in Figure 3 is positive) is My = −rQ A (Pc 1 sinθ
+ps1cosθ+pc 5inl/2 θ+p
s cos1/2 θ) (gas pressure rgas term) −((Mrec rO” w2 ), ′4λ) s
inθ(reciprocating mass m IQ sexual force f rcclJi ) +
Zl k, Mrec rOw2 sinθ+
XlkIMrec r,) w2 cosθ × primary balancer inertia force fi1 term) −Zz kz Mrec ro(W,,'2 >
2xsin (1/2θ+α) −)h k2Mrec rQ (w/ 2 >
2xcos (1/2θ+α) (camshaft balancer inertia hfic term), °, PC1, Ps L, Pc1/2, Ps1
/2 = Coefficient of CO3θ,..., 5in1/2θ term when gas pressure fluctuation (1cy at 2θ) is expanded into Fourier series. MreC = moment due to reciprocating motion. λ = connection ratio (=A/r). A = Piston pressure receiving area. θ - crank angle. rQ = crank radius. L = connecting rod length. W = angular velocity. kl, = constant for IA C1 on crank radius 1゛0. fgas = gas pressure 6 free = inertia force due to reciprocating mass. fil = primary balancer inertia force. fic = camshaft balancer inertia force. In this example, since x1=O, Zz−0, My −−r
a A (PC1sinθ+p31cO3θ+ pc1
/25inl/2θ+Ps1/2 cos1/2θ)-
((Mrec r,)” w2 ) /4λ) si
nθ+ Zl k, Mrec r□ w2 s
inθ−X, k, Mrec r□ (w/2
> 2xcos (1/2θ+α) If we summarize this by order, My=[-roA Pct-((Mrec r□”
w2 )/4 λ ) + 11 kI M
rec ro W2 ] sin θ−l
'o A Pc 1 cosθ-rQ A
Pcs 1/2 cos(1/2 θ+β
)-Xt k, IvJrec rO (w/2)
2xcos (1/2 θ+α) Therefore, A Pcs 1/2 =' -x2, Mrec
By setting (W/2) α - β, the 1st and 2nd order terms, that is, the O-ring vibration a (1/2nd order) around the crankshaft direction can theoretically be made zero. . Incidentally, the effect of C3k + 1/' secondary balancer at rated load in an engine with a dynamic balancer manufactured by the applicant's company is shown in Figure 4 (2), ■) and Figure 5 (2),
In (b), the vertical axis is the amplitude value, the horizontal axis is the measurement position and its direction,
Shown as a graph. As is clear from these figures, the application of the embodiment device has a remarkable effect (q) on reducing the rolling vibration (1/2 order) around the crankshaft direction of the J5 4-cycle single-cylinder engine. [Effects of the Invention] As explained above, according to the present invention, in a 1-cycle single-cylinder engine, a 1,72-order balancer can be configured by simply installing a balance weight directly on the camshaft. This extremely simple mechanism can sufficiently reduce the rolling vibration around the crankshaft based on the piston thrust force caused by the combustion pressure nozzle, creating a 4-stroke single-cylinder engine with less vibration, and a new balancer. There are ten effects such as being able to easily and inexpensively promote VCV construction without requiring a balance heron V or the like.

[Brief explanation of the drawing]

Fig. 1 is a configuration explanatory diagram showing an embodiment of the balancer equipment according to the present invention, and Figs. 2 (2), (b), and (c) are perspective views, respectively, without showing the usual manner of installing the balance weight. , Fig. 3 is a relational diagram explaining the operating principle of the 1772-order balancer, Fig. 4 (2), (b), and Fig. 5 (c), (b).
) are graphs showing the experimental results of Mid of the present invention. 2... Piston, 3... Crankshaft, 5... Crank gear, G... Cam sleeve, 7... Cam gear, 8...
・Balance weight. Same dialect 1! P-shi Susumu Murai (a)■! b 7 虱f 無 7 > y base 7 ri 7 no Yodo Shin l iP crying L

Claims (1)

[Claims] It has a crankshaft and a camshaft attached to the crankshaft, and the crank gear fixed on the crankshaft is meshed with the cam gear fixed on the camshaft, and the crankshaft is operated one rotation in a fixed direction. Accordingly, in a configuration in which the camshaft is operated 1/2 rotation in the opposite direction, a balance weight is installed on the camshaft to prevent combustion, which occurs once every two rotations of the crankshaft. A balancer device for a four-stroke single-cylinder engine, characterized in that the rolling vibration moment around the crankshaft based on piston thrust force due to pressure is reduced by rotational centrifugal force acting on a balance weight provided on the camshaft.