JPH0650089Y2 - Operation mode switching device for electric hammer drill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Utilization of the Invention] The present invention relates to an operation mode switching device for a tool, such as an electric hammer drill, which switches between an operation mode of rotation and impact and an operation mode of rotation only.

[Background of the invention]

Conventionally, a rotation mode in which the rotation of a drive shaft driven by a motor is transmitted to a cylinder via an intermediate shaft and the tool is rotated by this cylinder, and a striking mode by the operation of a reciprocating bearing provided in the intermediate shaft is added to this rotation mode. Electric hammer drills have been proposed which have both rotating and striking modes of operation.

In order to switch between the operation mode of only this rotation and the operation mode of rotation and striking, a movable clutch that transmits or interrupts the rotation of the intermediate shaft to the reciprocating bearing is provided on the intermediate shaft. The movable clutch moves to the reciprocating bearing side and meshes with the reciprocating bearing to add a striking mode for rotation and striking operation mode.When the movable clutch moves to the tool opposite to the reciprocating bearing side, Since the meshing with and disengaged, and no longer giving power, the operation mode was only rotation.

In order to move this movable clutch, one side of the movable clutch is provided with a spring that constantly presses the movable clutch toward the reciprocating bearing side.From the outside of the electric hammer drill, the spring is pressed against the reciprocating bearing side. It was configured to be movable by an operable switching lever.

In the operation mode switching device of the conventional electric hammer drill configured as described above, the load vibration applied by the impact is applied to the reciprocating bearing during the rotation and impact operation modes, and the vibration is transmitted to the movable clutch meshing with the reciprocating bearing. There is a problem that it will be done. Due to such a problem, even if vibration is transmitted to the movable clutch, the engagement with the reciprocating bearing cannot be disengaged.Therefore, the pressing force of the spring must be increased, and when the pressing force of the spring is increased, There is a problem in that the sliding portion between the switching lever and the movable clutch is quickly worn. In order to solve this problem of wear, it is necessary to indirectly operate the movable clutch by using a wear resistant material for the sliding portion, and the number of parts is large and the structure is difficult to assemble.

[Purpose of device]

It is an object of the present invention to provide an operation mode switching device for an electric hammer drill which eliminates the above-mentioned drawbacks of the prior art, has a minimum number of parts, and can reliably perform a switching operation of a movable clutch without impairing its function.

[Outline of device]

The present invention is designed to prevent the load and vibration applied to the reciprocating bearing from being transmitted to the movable clutch when transmitting power from the intermediate shaft to the reciprocating bearing through the movable clutch in the rotating and striking operation modes of the electric hammer drill. If the gap is provided between the movable clutch claw and the reciprocating bearing claw, the load of the spring that biases and presses the movable clutch can be minimized. The end is
The stopper is provided to restrict the movement of the movable clutch toward the reciprocating bearing so that the meshing can be maintained without abutting in the axial direction of the intermediate shaft.

[Embodiment of the Invention] An embodiment of the present invention is shown in FIGS. 1 to 4.

The rotation of the motor (not shown) is transmitted to the intermediate shaft 3 via the motor drive shaft 1 and the first gear 2, and the rotation is always transmitted to the final gear 14 that meshes with the pinion 8 provided on the intermediate shaft 3, and the cylinder 15 Rotate tool 16 through. A reciprocating bearing 5 is loosely fitted coaxially to the intermediate shaft 3, and a reciprocating bearing claw 5a is integrally provided on the left end surface of the reciprocating bearing 5 in the figure. When the movable clutch claw 4b of the movable clutch 4 described later meshes with the reciprocal bearing claw 5a, the rotation of the intermediate shaft 3 is transmitted to the reciprocal bearing 5, and the swing rod 18 provided at one end of the reciprocal bearing 5 moves in the axial direction. And swings the piston 12 connected to the swing rod 18. Piston 12
Slides on the inner surface of the cylinder 15 and swings the striker 13 through the air chamber 17. Here, the air chamber 17 has the function of an air spring. In this way, the striker 13 strikes the rear end portion of the tool 16 by the striking force converted into swinging, that is, reciprocating motion, and the rotation and striking operation modes are set.

In order to set the operation mode to only rotation, the movable clutch claw 4b and the reciprocating bearing claw 5a of the movable clutch 4 described above are used.
You just have to remove the mesh. A switching lever (10) that can be operated from the outside of the electric hammer drill is provided in order to disengage the movable clutch claw (4b) and the reciprocating bearing claw (5a). The switching lever 10 is provided with a lever pin 9 which is eccentrically fixed at one end, and the position of the lever pin 9 is displaced by the rotating operation of the switching lever 10, so that the movable clutch 4 engaged with the lever pin 9 is a shaft. The movable clutch claw 4b and the reciprocating bearing claw 5a are engaged with each other or removed from each other.

As shown in FIG. 4, the movable clutch 4 has a spline 4a formed on the inner surface and a movable clutch pawl 4b formed on the right end surface in the drawing. Further, a movable clutch groove 4c with which the lever pin 9 of the switching lever 10 described above is engaged is formed on the outer circumference of the middle side of the movable clutch 4.

The movable clutch 4 thus configured is arranged on the intermediate shaft 3 shown in FIG. On the intermediate shaft 3, a pinion 8 having a slightly larger diameter is integrally formed at a position where it meshes with the final gear 14, and an intermediate shaft spline 3a is further formed on a portion where the movable clutch 4 moves. An intermediate shaft ring groove 3b is formed near the end of the intermediate shaft spline 3a, and an O-ring 11 can be inserted into the intermediate shaft ring groove 3b.

When the intermediate shaft 3, the movable clutch 4, the reciprocating bearing 5 and the like are assembled, the structure is as shown in FIG. By engaging the intermediate shaft spline 3a and the movable clutch spline 4a,
The movable clutch 4 is movable in the tool axial direction with respect to the intermediate shaft 3 and is integrally formed in the rotational direction. By disposing a spring 6 that comes into contact with the left end surface of the movable clutch 4 in the drawing with a washer 7, It is always urged to the right on the intermediate shaft 3. In order to limit the movement of the movable clutch 4 to the right side in the drawing, the intermediate shaft ring groove of the intermediate shaft 3 is formed.
An O-ring 11 is provided on 3b. Since the outer diameter of the O-ring 11 is larger than the inner diameter of the movable clutch 4, the movable clutch 4 can move only to the position of the O-ring 11 even if it is pressed by the spring 6 to the right side in the drawing. That is,
The O-ring 11 acts as a stopper for the movable clutch 4.

The reciprocating bearing 5 is loosely fitted in the assembly of the intermediate shaft 3 and the movable clutch 4 configured in this way, and finally the first gear 2 is fitted.

In the configuration shown in FIG. 2, the movable clutch pawls provided on the movable clutch 4 when the movable clutch 4 is moved to the right side in the drawing, that is, the operation modes of rotation and striking.
The position of the O-ring 11 provided on the intermediate shaft 3 is determined so that the reciprocating bearing claws 5a provided on the reciprocating bearing 5 and 4b always have the gap L.

When the position of the O-ring 11 is determined in this way, the gap L always exists in the axial direction between the movable clutch 4 and the reciprocal bearing 5, so that the load vibration transmitted to the reciprocal bearing 5 by striking is prevented. It is absorbed by this gap L and is not transmitted to the movable clutch 4. Since the load vibration due to the impact is not transmitted to the movable clutch 4, it is not necessary to increase the pressing force of the spring 6 more than necessary. As a result, the lever pin 9 provided on the switching lever 10 and the movable clutch groove 4c of the movable clutch 4 are eliminated. The wear of the sliding part of the device is reduced, and it becomes unnecessary to use a wear resistant member in this part.

According to the present invention, the movable clutch pawl provided on the movable clutch and the reciprocal bearing pawl provided on the reciprocal bearing always have a gap, so that the load vibration transmitted to the reciprocal bearing by impact is affected. Is not transmitted to the movable clutch, and there is no need to increase the pressing force of the spring more than necessary, so the clutch can be operated directly from outside the electric hammer drill, and the minimum number of parts can be set.
It is possible to provide an operation mode switching device for an electric hammer drill that can reliably switch the movable clutch without impairing its function.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an operation mode switching device for an electric hammer drill according to the present invention, and FIG. 2 is a side view showing an embodiment of a configuration on an intermediate shaft of an electric hammer drill according to the present invention. FIG. 3 is a side view showing an embodiment of an intermediate shaft of the electric hammer drill according to the present invention, and FIG. 4 is a sectional view showing an embodiment of a movable clutch and a reciprocating bearing of the electric hammer drill according to the present invention. In the figure, 1 is a motor drive shaft, 2 is a first gear,
3 is an intermediate shaft, 3a is an intermediate shaft spline, 3b is an intermediate shaft ring groove, 4 is a movable clutch, 4a is a movable clutch spline,
4b is a movable clutch claw, 4c is a movable clutch groove, 5 is a reciprocating bearing, 6 is a spring, 7 is a washer, 8 is a pinion, 9 is a lever pin, 10 is a switching lever, 11 is an O-ring, 12 is a piston, and 13 is an impact. Child, 14 is the final gear,
Reference numeral 15 is a cylinder, 16 is a tool, 17 is an air chamber, and 18 is a rocking rod.

Claims (1)

[Scope of utility model registration request] 1. A motor drive shaft driven by a motor,
An intermediate shaft rotated by the motor drive shaft and a cylinder rotated by the intermediate shaft, and a reciprocating bearing rotatably provided on the intermediate shaft causes a piston contained in the cylinder to move in the tool axial direction. An electric hammer drill that moves the intermediate shaft to the reciprocating bearing and interrupts the rotation of the intermediate shaft. A movable clutch pawl is integrally provided on the end surface on the bearing side, and a spring for constantly pressing the movable clutch toward the reciprocating bearing side is provided, and the movable clutch is moved in the tool axial direction by an operation from the outside of the electric hammer drill. In an operation mode switching device for an electric hammer drill, the movement of the movable clutch toward the reciprocating bearing side is restricted. By providing a stopper at a predetermined position on the intermediate shaft, the movable clutch pawl and the reciprocating bearing pawl provided on the reciprocating bearing so as to be connectable with the movable clutch pawl always have a gap. Hammer drill operation mode switching device.