JPH0230834B2 - KEITAIYODENDOKOGUNOOFUKUDOSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reciprocating device for a portable power tool having a reciprocating mechanism, such as an electric hammer.

2. Description of the Related Art As a reciprocating device for a portable power tool having a reciprocating drive member, one using a piston-crank mechanism is known. This mechanism can transmit a large amount of power, but the rotation axis of the crank is perpendicular to the direction of reciprocating motion. This means that the prime mover shaft must be placed at right angles to the reciprocating direction, or the prime mover shaft must be placed in the reciprocating direction, and a mechanism for changing the direction of the rotary axis must be additionally provided. The small size and lightweight configuration required for the tool may be impaired. In view of this point, a reciprocating mechanism is also known in which a motor shaft is arranged in the reciprocating direction and a cam is used to obtain reciprocating motion. However, since this known mechanism uses a cam, the cam surface and the driven body move in point or line contact, and therefore have the disadvantage that large amounts of power cannot be transmitted. In order to compensate for this drawback, it becomes necessary to increase the size of the cam device, thus defeating the original purpose of obtaining a compact and lightweight structure.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a portable tool having a reciprocating device that is small and lightweight.

The present invention focuses on the fact that the link mechanism is suitable for transmitting large amounts of power, and by combining the direction changing function of a bell crank, which is a modification of the link mechanism, and a drive mechanism using an inclined crank, It was devised to obtain reciprocating motion in the direction.

Figure 1 is. This is a specific example of an electric hammer drill having a reciprocating device according to the present invention. In the figure,
1 is the prime mover, 2 is the prime mover shaft, 3 is the inclined crank,
4 is a bell crank, 5 is a ball joint, 6 is a piston pin, 7 is a piston, 8 is a cylinder, 9 is a striker,
10 is a meson, 11 is a tool holder, 12 is a gear,
13 is a tool. In such a configuration, the rotation of the prime mover 1, which is installed to have a rotation axis parallel to the reciprocating axis of the piston 7, is caused by the outer periphery of the crown portion of the inclined crank 3, which meshes with a gear provided at the tip of the prime mover shaft 2. The tilting crank 3 is rotated through the gear provided in the. The tilting shaft of the tilting crank 3 is formed as a hole provided in the crank crown, and the axis of the hole rotates on a cone having its apex at a point on the rotation axis of the tilting crank.
A bearing 14 is installed in the hole, and is coupled in a rotating pairwise relationship to a rotating arm 15 of a bell crank 4 supported by a ball joint 5 centered at the apex of the cone. Since the axis of the rotary arm passes through the center of the bearing, the rotation of the inclined crank 3 causes the rotary arm of the bell crank to rotate on the cone. At this time, the swinging arm 16 of the bell crank performs a swinging motion centering on the center of the ball joint 5 on a plane passing through the center of the ball joint 5 and the axis of the cylinder 8 .
The swing arm 16 is connected to a piston 7, which is a driving member, via a piston pin 6.
is reciprocated by the swinging motion of the swinging arm 16. The striking element 9 is reciprocated by the piston 7 via an air action and strikes the intermediate element 10. This impact energy is transmitted to the tool 13 held by the tool holder 11 through the meson.
On the other hand, a gear provided at the shaft end of the inclined crank 3 meshes with the gear 12 to rotationally drive it. The gear 12 is non-rotatably coupled to the tool holder 11, and rotates the tool 13 via the gear 12.

Figure 2 shows details of the reciprocating device. A ball joint 5 supporting the bell crank 4 is fixed by a pivot pin 17 to a part 18 of the casing. The swinging arm 16 is loosely fitted into the hole 19 of the piston pin, and some slippage occurs during the swinging motion. The piston pin 6 is loosely fitted into a pin hole 20 of the piston, and rotates by the swing angle as the swing arm swings.

According to the present invention, it is possible to obtain reciprocating motion parallel to the prime mover shaft without using a rotational direction change mechanism, so that a portable power tool having a reciprocating motion mechanism can be made compact and lightweight. . Also, compared to using a cam to obtain reciprocating motion, there is no point contact or line contact, so
A reciprocating mechanism capable of transmitting relatively large power can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partially longitudinal side view showing an embodiment of the reciprocating device according to the present invention, FIG. 2 is a longitudinal side view showing details of the reciprocating device portion of FIG. 1, and FIG.
FIG. In the figure, 3 is an inclined crank, 4 is a bell crank, 5 is a ball joint, 7 is a piston, and 8 is a cylinder.

Claims (1)

[Claims] 1. In a reciprocating device for a portable power tool having a drive member that reciprocates in an axial direction guided by a guide means, the drive member is rotationally driven by a crankshaft with one arm inclined. A reciprocating device for a portable power tool, which is a bell crank, the fulcrum of which is supported by a universal joint, and is driven by the swinging motion of the other arm.