Percussion device comprising a damping mechanism

Abstract

A percussion device including a shank adaptor, a machine housing that contains a percussion piston that is arranged to carry out a reciprocating movement caused by the pressure from a hydraulic fluid and to strike the shank adaptor when the percussion device is in use. An elastic element is arranged radially outwards from the percussion piston to dampen the recoil from the shank adaptor. The machine housing has an inner surface that faces the percussion piston. The elastic element has an inner surface that faces the percussion piston and an outer surface that faces the inner surface of the machine housing. At least a part of the outer surface of the elastic element directly faces the inner surface of the machine housing.

Claims

1. A percussion device, comprising: a shank adaptor, a percussion piston that is arranged to carry out a reciprocating movement caused by pressure from a hydraulic fluid and to strike said shank adaptor when the percussion device is in use, a machine housing containing said percussion piston, an elastic element that is arranged radially outwards from said percussion piston to dampen a recoil from said shank adaptor, wherein said machine housing has an inner surface that faces said percussion piston, and wherein said elastic element has an inner surface that faces said percussion piston and an outer surface that faces said inner surface of said machine housing, whereby at least a part of said outer surface of said elastic element directly faces said inner surface of said machine housing, and whereby the inner surface of the elastic element directly faces the percussion piston when the percussion device is in use; and a gap defined between the outer surface of said elastic element and said inner surface of said machine housing when said elastic element is at room temperature.

2. The percussion device according to claim 1, further comprising: a transmission element, whereby said shank adaptor is arranged to strike said transmission element during recoil of the shank adapter.

3. The percussion device according to claim 1, further comprising: a stop plate that is arranged between said transmission element and said elastic element.

4. The percussion device according to claim 3, further comprising: a locking element to fasten or tighten said stop plate in said machine housing.

5. The percussion device according to claim 1, wherein said elastic element comprises a ring-shaped element.

6. The percussion device according to claim 1, further comprising: a locking element to fasten or tighten said elastic element in said machine housing.

7. The percussion device according to claim 1, further comprising: a gap between the inner surface of said elastic element and said percussion piston when percussion device is in use.

8. The percussion device according to claim 1, wherein said percussion piston is arranged to strike said shank adaptor at a frequency of 10 Hz or higher.

9. The percussion device according to claim 1, wherein said elastic element comprises at least one of the following materials: rubber, polyurethane.

10. The percussion device according to claim 1, wherein the percussion device is a handheld and/or hand-maneuvered percussion device.

Description

BRIEF DESCIPTION OF THE DRAWINGS

(1) In the following, the present invention shall be described in more detail with reference to the accompanying schematic figures, in which:

(2) FIG. 1 shows a part of a percussion device according to an embodiment of the present invention, and

(3) FIG. 2 shows a cross section along line X-X in FIG. 1.

(4) It should be noted that the drawings have not necessarily been drawn to scale and that the dimensions of certain features may have been exaggerated for the sake of clarity.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) FIG. 1 shows part of a hydraulic fluid-driven percussion device 10 according to an embodiment of the present invention. The percussion device 10 comprises a shank adaptor 12 and a substantially cylindrical machine housing 14 that contains a percussion piston 16. The percussion piston 16 is arranged to carry out a reciprocating movement (indicated by arrow A), for example at a frequency of 10 Hz or higher, along its longitudinal axis, and to strike the shank adaptor 12 when the percussion device 10 is in use.

(6) An elastic element 18, such as a rubber ring, is arranged radially outwards from the percussion piston 16 to dampen the recoil from the shank adaptor 12. The shank adaptor 12 is arranged to strike a transmission element 20 during its recoil (which recoil movement is indicated by the arrows B). The transmission element 20 is spring loaded and arranged to follow the shank adaptor's 12 movements during it recoil. For example, the transmission element 20 is arranged to be displaced 5-10 mm forwards and backwards along the percussion device's longitudinal axis with the shank adaptor 12.

(7) The machine housing 14 has an inner surface 14i that faces the percussion piston 16. The elastic element 18 has an inner surface 18i that faces the percussion piston 16 and an outer surface 18y that faces the inner surface 14 in the machine housing 14. In the illustrated embodiment the elastic element's 18 entire outer surface 18y directly faces the machine housing's 14 inner surface 18i with only gas/air therebetween. Only 25%, 50% or 75% of the elastic element's 18 outer surface 18y can however be arranged to directly face the machine housing's 14 inner surface 18i.

(8) The percussion device 10 comprises a stop plate 22 arranged between the transmission element 20 and the elastic element 18, and a locking element 24 to fasten or tighten the stop plate 22 and the elastic element 18 in the machine housing 14.

(9) In the illustrated embodiment there is a gap 26 between the outer surface 18y of the elastic element 18 and the inner surface 14i of the machine housing 14 when the elastic element 18 is at room temperature. The elastic element 18 can expand into at least part of this gap 26 if/when it is heated up during use or on compression.

(10) The illustrated percussion device 10 also comprises a gap 28 between the inner surface 18i of the elastic element 18 and the percussion piston 16 when the percussion device 10 is in use. The elastic element 18 can also expand into part of this gap 28 if/when it is heated up during use or on compression.

(11) According to an embodiment of the invention the elastic element 18 is pre-tensioned, for example a few millimeters, in order to have an increased initial force towards the left in FIG. 1 so that the percussion point will not vary too much when the percussion device 10 is in use. The pre-tensioning can be achieved by arranging the elastic element to be slightly too long so that it is compressed when the two different machine housings are brought together when the percussion device 10 is in use.

(12) FIG. 2 shows a cross section along line X-X in FIG. 1 and shows the gap 26 between the outer surface 18y of the elastic element 18 and the inner surface 14i of the machine housing 14, and the gap 28 between the inner surface 18i of the elastic element 18 and the percussion piston 16.

(13) Several modifications of the inventions would be possible within the scope of the accompanying claims. For example, even though the illustrated embodiments are directed to a ring-shaped elastic element 18, a ring-shaped stop plate 22, a cylindrical percussion piston 16 and a substantially cylindrical machine housing 14, a percussion device 10 according to the present invention and its components may be of any suitable shape.