Hand power tool with a pneumatic striking mechanism

• US 20040016558A1
• Filed: 05/28/2003
• Published: 01/29/2004
• Est. Priority Date: 11/16/2001
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Meixner, Gerhard, Mueller, Frank
• Granted Patent: US 7,040,413 B2
• Time in Patent Office: Days
• US Class Current: 173/201
• CPC Class Codes: B25D 11/005 Arrangements for adjusting the stroke of the impulse member or for stopping the impact action when the tool is lifted from the working surface
• CPC Class Codes: B25D 2222/57 Elastomers, e.g. rubber
• CPC Class Codes: B25D 2250/035 Bleeding holes, e.g. in piston guide-sleeves
• CPC Class Codes: B25D 2250/131 Idling mode of tools

Abstract

The striking mechanism has a hammer barrel (3), which has at least one control opening (23) through which, in an idle position, the air can escape from the hammer barrel (3), and which in a striking position is closed by a covering (25) that prevents the escape of air. To achieve the greatest possible sealing off of the at least one control opening (23) and thus high efficiency of the striking mechanism, the covering (25) is molded from an elastomer.

Claims

1. A hand power tool—

preferably a drill hammer or jackhammer—

with a pneumatic striking mechanism that has a hammer barrel (3) which has at least one control opening (23), through which, in an idle position, air can escape from the hammer barrel (3) and which is closed, in a striking position, by a covering (25) preventing the escape of air, characterized in that the covering (25) comprises an elastomer.

2. The hand-power tool of claim 1, characterized in that the hammer barrel (3) is supported displaceably in the direction of its longitudinal axis in the power tool housing (1), and that the covering (25) is disposed in such a way in the power tool housing (1), nondisplaceably in the axial direction, that the hammer barrel (3) upon an axial displacement into the striking position moves with its at least one control opening (23) to beneath the covering (25).

3. The hand power tool of claim 1, characterized in that a retaining means (27), supported displaceably in the axial direction, for the covering (25) is disposed in the power tool housing (1), and that means (19, 29, 31) are present which at the transition from the idle position to the striking position displace the retaining means (27) along with the covering (25) axially, so that the covering (25) comes to rest above the at least one control opening (23) in the hammer barrel (3).

4. The hand power tool of claim 3, characterized in that the means comprise a snap head die (19), which is supported in the hammer barrel (3) and is displaced against a machining point by a tool (15) introduced into the hammer barrel (3), when the tool (15) is pressed upon, and which has a stop (29, 31) that transmits the axial motion of the snap head die (19) to the retaining means (27).

5. The hand power tool of claim 4, characterized in that the stop is a disk (29), which is placed on the snap head die (19) and which protrudes with one or more arms (31) through an opening (33) in the hammer barrel (3) as far as the retaining means (27) surrounding the hammer barrel (3).

6. The hand power tool of one of claims 3-5, characterized in that the retaining means (27) for the covering (25) is embodied such that it enables play of the covering (25) in the radial direction relative to the hammer barrel (3).

7. The hand power tool of one of the foregoing claims, characterized in that the covering is a control sleeve (25) surrounding the hammer barrel (3).