JPS5831653Y2 - Motor tool equipped with reciprocating motion balance device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a motor tool equipped with a reciprocating motion balance device among tools having a mechanism for converting the rotation of an eccentric shaft into reciprocating motion, such as the Todenki hammer.

In a motor tool that has a mechanism that converts the rotation of an eccentric shaft into reciprocating motion, in order to eliminate the unbalance of the reciprocating motion, an unbalance that balances the reciprocating unbalance is provided in the rotating part to achieve balance. , this time, the rotational balance will be disrupted.

Therefore, balancing is normally performed to reduce the reciprocating unbalance and increase the rotational unbalance, but since the unbalance remains, there is a drawback that vibrations are large.

An object of the present invention is to obtain a motor tool that eliminates the drawbacks of the above-mentioned prior art and exhibits particularly low vibrations when no load is applied.

The present invention focuses on the fact that if two unbalances that balance the reciprocating unbalance are brought into counterrotation engagement with each other, the rotational balance will also be maintained, and this is done coaxially.

The present invention will be explained below using examples.

As shown in FIG. 1, a pinion 3 provided on the rotor shaft 2 of the moder 10 and a pinion 4 provided at the tip thereof mesh with an external gear 5 and an internal gear 6, respectively.

The external gear 5 is non-rotatably coupled to the crankshaft 7 by a key 8, and the internal gear 6 is rotatably incorporated into the crankshaft 7 concentrically with the external gear 5.

Here, the gear ratio between the pinion 4 and the internal gear 6 is the same as the gear ratio between the pinion 3 and the external gear 5.

On the eccentric shaft 9 provided protruding from one end of the crankshaft 7,
A connecting rod 10, which is rotatably attached at one end, is rotatably connected to a piston 12 via a pin 11 at the other end.

Note that the external gear 5 is provided with a balance tray 13, the internal gear 6 is provided with a balance tray 14, and the crankshaft 7 is provided with a balance tray 15. The direction in which the tooth gear 60 is installed is determined.

Furthermore, the unbalance in the reciprocating motion (in the X direction) caused by the piston 12 and the connecting rod 10 is balanced by the unbalance in the X direction caused by the connecting rod 10, the crankshaft γ, the internal gear 6, the external gear 5, etc. , the rotational unbalance caused by the crankshaft 7 and the externally toothed gear 5 is of a magnitude that is balanced with the rotational unbalance of the internally toothed gear 60.

Therefore, the unbalance of the internal gear 6 is half the reciprocating unbalance caused by the piston 12 and the connecting rod 10.

As shown in FIGS. 4 and 3, when pinion 3 and pinion 4 rotate in the direction of the arrow, external gear 5 and internal gear 6 rotate in opposite directions.

On the other hand, when the external gear 5 rotates, the rotationally coupled
The eccentric shaft 9 of the crankshaft 7 also rotates, and the piston 12 reciprocates via the connecting rod 10.

Now, if the rotation angle of the crankshaft T is in the direction ωt shown in FIG. 2, the internal gear 6 has a rotation angle of -ωt as shown in FIG. 3, and the external gear 5 has a rotation angle of -ωt as shown in FIG. , ωt, the total inertial force X in the reciprocating direction and the total inertial force Y in the direction perpendicular to the reciprocating motion are determined by the following equation.

In X (P+C)rω2cosωt+Lcos2ωt)+
(C'-to-8) rω2cosωt-Urω2cos
(-ωt)-: (-8-U to P+C-1-C'-)
rω2c OSωt+(P+C)rω2XLcos2
(1) t Y: (C'-to-8) rω2s i nωt-Urω2
sin(-ωt) = (-8+U to C'-) r
(7J2S i n ω, where ω is the rotation angular velocity of the crankshaft 10, t is the time, r is the rotation radius of the eccentric shaft 90, t is the length of the connecting rod 10, P is the mass of the piston 12, and C is the mass of the connecting rod 1.
0 is the equivalent reciprocating mass, C' is the equivalent rotating mass of the connecting rod 10,
K is the rotational mass of the crankshaft 70, S is the rotational mass of the external gear 5, and U is the rotational mass of the internal gear 60, and all of the rotational masses are converted into the radius r position.

In the previous equation, P+C+C'- has -8-U=0, C'-
externally toothed gear 5, internally toothed gear 6, so that −8+U=0.
Since the balance trie of the crankshaft 7 is set to 13.14°15, X (P + C) r' Since there is no inertia force in the right angle direction, reciprocating motion with very little vibration is achieved.

5, 6, and 7 show examples in which a timing belt 16 is used instead of an internal gear, but exactly the same effect can be obtained.

According to the present invention, it is possible to obtain a motor tool equipped with a reciprocating motion balance device that can eliminate the primary inertia force of reciprocating motion and the inertia force in the direction perpendicular to the reciprocating motion, and in particular has very little vibration when no load is applied. Can be done.

[Brief explanation of drawings]

Figures 1 and 3 are side views showing an embodiment of a motor tool equipped with a reciprocating balance device according to the present invention;
Figure 3 is a cross-sectional view taken along the line ■-■ in Figure 1.
FIG. 4 is a sectional view taken along the line ■-■ in FIG. 1. Fig. 5 is a side view showing another embodiment of the present invention, and Fig. 6 is a side view showing another embodiment of the present invention.
FIG. 7 is a cross-sectional view taken along the line VI-VI in FIG. 5, and FIG. 7 is a cross-sectional view taken along the line ■-V in FIG. In the figure, 1 is a model, 2 is a rotor shaft, 3°4 is a pinion, 5 is an external gear, 6 is an internal gear, 7 is a crankshaft, 8 is a key, 9 is an eccentric shaft, 10 is a connecting rod, 11 is a pin,
12 is the piston, 13, 14° 15 is the balance bird, 1
6 is a timing belt.

Claims (1)

[Scope of utility model registration request] When the rotation of the rotor of a motor tool is transmitted through a gear to the crank, which is the rotation axis of the gear, the eccentric shaft, which is eccentrically fixed to the crankshaft, rotates around the crankshaft center, and both ends of the rotor are connected to the eccentric shaft and the piston. A motor tool equipped with a reciprocating balance device characterized by having a coaxial balancer that rotates in opposite directions in a mechanism that causes a piston to reciprocate through a rotatably attached connecting rod.