JP2002254224A - Slip cluch mechanism for hammer drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the selection of slip clutch characteristics, and to provide a hammer drill having good operability. SOLUTION: A mechanism is configured such that first and second slip clutches with different characteristics are disposed on a shaft of a bevel pinion 4 in a freely mating state, an eccentric pin 14a of a changeover shaft (B) 14 moves a changeover shaft (A) 12 which is arranged in the bevel pinion 4 to the axial direction by rotating a lever 15, and whereby the first slip clutch is connected to a bevel pinion 4 via a steel ball 3, and then the other second slip clutch is disconnected from the bevel pinion 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip clutch mechanism for limiting the torque of a tool bit such as an electric hammer drill.

[0002]

2. Description of the Related Art In a conventional hammer drill, one slip clutch mechanism for regulating the torque transmitted to a tool bit is provided on a shaft in a rotary mechanism for transmitting the rotation of a motor to a bit tool. .

[0003]

In the above-described conventional slip clutch mechanism, the slip torque is set to one.
Therefore, even if the required slip torque differs depending on the operator, there is a problem that it is impossible to select the characteristics of the slip clutch.

An object of the present invention is to provide a hammer drill which solves the above-mentioned drawbacks, enables selection of characteristics of a slip clutch, and has good operability.

[0005]

The object of the present invention is to provide a slip clutch having different slip characteristics on a shaft in a rotation transmitting section.
This is achieved by providing one or more and selecting the slip clutch to be operated.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a slip clutch mechanism of a hammer drill according to the present invention will be described below with reference to FIGS.

In FIG. 1, the rotational motion of the rotor 1 is transmitted to two second gears 2 meshing with a pinion portion 1a of the rotor. The upper second gear 2a has a first slip clutch and a lower second gear 2b. Accommodates a second slip clutch. The first and second slip clutches are set so as to have different slip characteristics, and have a structure to be described later. By the switching operation, one of the first and second slip clutches is connected to the bevel pinion 4 via the steel ball 3, and the bevel pinion 4 meshes with the bevel gear 5 connected to the cylinder 7 via the key 6. I have. The cylinder 7 and the second hammer 8 are fitted in the rotation direction,
The second hammer 8 transmits the rotational force to the tip tool.

Next, the structure of the slip clutch and the setting of the slip characteristics will be described. FIG. 2 is a sectional view of the first slip clutch.

As shown in FIG. 1, a gear holder 9 is accommodated in the second gear 2, and a claw 2c is formed on the inner periphery of the second gear 2. The needle pin 10 disposed on the gear holder 9 receives a load in the outer peripheral direction by the spring (A) 11 and is constantly pressed against the claw 2 c of the second gear 2. When a bevel pinion 4 is subjected to a certain torque or more due to locking of a tool bit or the like during drilling work, the needle pin 10 compresses the spring (A) 11 and climbs over the claw portion 2c of the second gear 2 so that the second gear 2 Slips and the slip clutch operates. The torque at which the slip clutch operates is determined by the load of the spring (A) 11, and the slip characteristic can be set by changing the load of the spring (A) 11.

FIG. 2 shows the first slip clutch provided in the upper second gear 2a. The second slip clutch provided in the lower second gear 2b has the same structure as the first slip clutch. And the spring
(A) Only the load of 11 is different. In addition,
In the present embodiment, the spring in the upper second gear 2a
The load of (A) 11 is set to be larger than the load of the spring (A) 11 in the lower second gear 2b, and the torque for operating the first slip clutch is set to be larger than the torque for operating the second slip clutch. are doing.

Next, the structure for switching the slip clutch will be described.

FIG. 3 shows a state in which the bevel pinion 4 and the first slip clutch are connected and the connection between the bevel pinion 4 and the second slip clutch is released. When the lever 15 is rotated from this state, the switching shaft (B) 14 connected to the lever 15 is rotated, and the eccentric pin 14a provided eccentrically on the end face of the switching shaft (B) 4 is rotated by the switching shaft (B). The eccentric movement is performed with the rotation axis 14 as a fulcrum.

A switching shaft disposed in the bevel pinion 4
(A) 12 is always switched by a spring (B) 13
(B) Since the eccentric pin 14a of the switching shaft (B) is pressed against the eccentric pin 14a, the switching shaft (B) moves in the axial direction in the bevel pinion 4 as shown in FIGS.

In the state shown in FIG. 3, two steel balls 3 constituting the first slip clutch provided in the upper second gear 2a are pushed outward by the switching shaft (A) 12, and the first slip clutch, that is, the upper Second gear 2a
The inner gear holder 9 and the bevel pinion 4 are connected. The two steel balls 3 constituting the first slip clutch provided in the lower second gear 2b are located on the outer peripheral side of the step portion 12a having a small outer diameter of the switching shaft (A) 12, so that the inner peripheral The gear holder 9 and the bevel pinion 4 in the lower second gear 2 b
Has been disconnected. In this state, when a relatively large torque is applied to the bevel pinion 4, the first slip clutch operates.

FIG. 4 shows a state in which the lever 15 is rotated from the state shown in FIG. 3 to release the connection between the bevel pinion 4 and the first slip clutch, and the bevel pinion 4 and the second slip 2 shows a state in which the clutch is connected. In this state, when a relatively small torque is applied to the bevel pinion 4, the second slip clutch operates.

By operating the lever 15 as described above, the slip characteristics of the slip clutch can be switched, so that the operability can be improved.

[0017]

According to the present invention, two or more types of slip clutches having different characteristics are provided on the shaft in the rotation transmitting mechanism, and a slip clutch operated by a switching operation can be selected. A good hammer drill slip clutch mechanism can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of a slip clutch mechanism of a hammer drill of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is an explanatory diagram of an enlarged operation of a main part of FIG. 1;

FIG. 4 is an explanatory diagram of an enlarged operation of a main part of FIG. 1;

[Explanation of symbols]

2 is a second gear, 2a is an upper second gear, 2b is a lower second gear, 2c is a claw portion, 3 is a steel ball, 4
Is a bevel pinion, 9 is a gear holder, 10 is a needle pin, 11 is a spring (A), 12 is a switching shaft (A), 13 is a spring (B), 14 is a switching shaft (B), 14a is an eccentric pin, 15 is It is a lever.

Claims (1)

[Claims] 1. A motor as a drive source, a conversion mechanism for converting the rotational motion of the motor into reciprocating motion, and a motion converted into reciprocating motion by the motion converting portion into a striking force, and a striking force applied to a tool bit. And a rotation mechanism for transmitting the rotation of the motor to the tip tool.
In a hammer drill provided with a slip clutch that regulates torque transmitted to the tip tool in the rotation mechanism, two or more slip clutches having different slip characteristics are arranged on a shaft in the rotation transmission unit, and a slip clutch that operates is provided. A slip clutch mechanism for hammer drills, which can be selected.