A hammer drill having a motor mounted within a body and an output spindle; a tool holder mounted on the body capable of holding a cutting tool; a hammer mechanism having a piston; a reciprocating drive for converting rotary movement of the motor into reciprocating movement of the piston; a ram recip
A hammer drill having a motor mounted within a body and an output spindle; a tool holder mounted on the body capable of holding a cutting tool; a hammer mechanism having a piston; a reciprocating drive for converting rotary movement of the motor into reciprocating movement of the piston; a ram reciprocatingly driven by the piston via an air spring to strike a cutting tool held in the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use; an air replenishment mechanism capable of refreshing the air spring during certain time periods during normal use; the air replenishment mechanism capable of being adjusted to refresh the air spring during time periods within the hammer cycle and/or the system allows different volumes of air into or out of the air spring during the refreshment time periods.
대표청구항▼
1. A hammer drill comprising: a body;a cylinder mounted within the body;a motor mounted within the body having an output spindle;a tool holder mounted on the body, the tool holder being capable of holding a cutting tool;a hammer mechanism comprising: a piston slideably mounted within the cylinder;a
1. A hammer drill comprising: a body;a cylinder mounted within the body;a motor mounted within the body having an output spindle;a tool holder mounted on the body, the tool holder being capable of holding a cutting tool;a hammer mechanism comprising: a piston slideably mounted within the cylinder;a reciprocating drive mechanism mounted within the body which, when the motor is activated, converts the rotary movement of the spindle of the motor into a reciprocating movement of the piston within the body;a ram slideably mounted within the cylinder forward of the piston, the ram being reciprocatingly driven by the reciprocating movement of the piston via an air spring to repetitively strike a cutting tool when held by the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use;an air replenishment mechanism which is capable of refreshing the air spring during certain time periods within the hammer cycle during normal use;characterized in that the air replenishment mechanism is capable of being adjusted so that it refreshes the air spring during different time periods within the hammer cycle during normal use and/or it allows different the volumes of air allows into or out of the air spring during the refreshment time periods,wherein the air replacement mechanism comprises a bleed hole formed through the wall of the cylinder and a valve connected to the bleed hole which, during the hammer cycle, selectively opens and closes the air bleed hole to allow air to pass through it during certain time periods within the hammer cycle and/or controls the volume of air passing through the bleed hole when it is open. 2. A hammer drill as claimed in claim 1, wherein there is provided a cylinder mounted within the body, the piston and ram being slideably mounted within the cylinder, the ram being mounted within the cylinder forward of the piston; wherein the air replenishment mechanism comprises: at least two bleed holes formed through the wall of the cylinder in different axial positions along the length of the cylinder;a selector mechanism which selectively opens and closes the bleed holes, the selector mechanism only opening one bleed hole at any one time. 3. A hammer drill as claimed in claim 2, wherein the dimensions of the at least two bleed holes are different relative to each other. 4. A hammer drill as claimed in claim 2, wherein the selector mechanism comprises a sleeve mounted in an axially slideable manner on the cylinder and which comprises at least two apertures, one of which is capable of being selectively aligned with one of the bleed holes at any one time as the sleeve is axially slid along the cylinder, the sleeve closing the remaining bleed holes. 5. A hammer drill as claimed in claim 1, wherein there is provided a sensor for providing a signal which is an indication of the position of the piston and which is used to control the opening and closing of the valve. 6. A hammer drill as claimed in claim 1, wherein the bleed holes are further opened and closed using the piston and/or ram. 7. A hammer drill as claimed in claim 1, wherein the selector mechanism is operated manually to operate the air replenishment mechanism. 8. A hammer drill comprising: a body;a motor mounted within the body having an output spindle;a tool holder mounted on the body, the tool holder being capable of holding a cutting tool;a hammer mechanism comprising: a piston slideably mounted within the body;a reciprocating drive mechanism mounted within the body which, when the motor is activated, converts the rotary movement of the spindle of the motor into a reciprocating movement of the piston within the body;a ram slideably mounted within the body which is reciprocatingly driven by the reciprocating movement of the piston via an air spring to repetitively strike a cutting tool when held by the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use;an air replenishment mechanism which is capable of refreshing the air spring during certain time periods within the hammer cycle during normal use;characterized in that the air replenishment mechanism is capable of being adjusted so that it refreshes the air spring during different time periods within the hammer cycle during normal use and/or it allows different volumes of air allows into or out of the air spring during the refreshment time periods;wherein the piston is a hollow piston, the ram being slideably mounted within the piston;wherein the air replacement mechanism comprises a bleed hole formed through the wall of the piston and a valve connected to the bleed hole which, during the hammer cycle, selectively opens and closes the air bleed hole to allow air to pass through it during certain time periods within the hammer cycle and/or controls the volume of air passing through the bleed hole when it is open. 9. A hammer drill comprising: a body;a motor mounted within the body having an output spindle;a tool holder mounted on the body, the tool holder being capable of holding a cutting tool;a hammer mechanism comprising: a piston slideably mounted within the body;a reciprocating drive mechanism mounted within the body which, when the motor is activated, converts the rotary movement of the spindle of the motor into a reciprocating movement of the piston within the body;a ram slideably mounted within the body which is reciprocatingly driven by the reciprocating movement of the piston via an air spring to repetitively strike a cutting tool when held by the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use;an air replenishment mechanism which is capable of refreshing the air spring during certain time periods within the hammer cycle during normal use; characterized in that the air replenishment mechanism is capable of being adjusted so that it refreshes the air spring during different time periods within the hammer cycle during normal use and/or it allows different volumes of air allows into or out of the air spring refreshment time periods; wherein the tool holder is capable of holding a cutting tool in a range of axial positions, the average axial position of the cutting tool within the tool holder during use being dependant on the hardness of the material being cut by the cutting tool;wherein there is further provided: a detection mechanism which determines the position of a cutting tool within the tool holder and provides an indication of the cutting tools position; andthe air replenishment mechanism, in response to indication of the detection mechanism, is adjusted so that it refreshes the air spring during different time periods within the hammer cycle and/or it allows different the volumes of air allows into or out of the air spring during the refreshment time periods dependent on the position of the cutting tool. 10. A hammer drill as claimed in claim 9, wherein the detection mechanism determines the average position of the cutting tool. 11. A hammer drill as claimed in claim 9, wherein there is further provided: a beat support structure mounted within the housing;a beat piece slideably mounted within the beat piece support structure,wherein the ram strikes a cutting tool via the beat piece, the detection mechanism determining the position of a cutting tool within the tool holder by determining the position of the beat piece within the beat piece support structure. 12. A hammer drill as claimed in claim 11, wherein the detection mechanism determines the average position of the beat piece. 13. A hammer drill as claimed in claim 11, wherein the beat piece comprises a flange, and wherein the detection mechanism determines the position of the flange. 14. A hammer drill as claimed in claim 13, wherein the detection mechanism comprises a rod which is biased towards and capable of engaging with the flange. 15. A hammer drill as claimed in claim 9, wherein the valve is open and closed dependent on the position of the piston and the position of the cutting tool.
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이 특허에 인용된 특허 (5)
Ranger Ulrich (Leinfelden-Echterdingen DEX) Wanner Karl (Leinfelden-Echterdingen DEX) Kaltenecker Johann (Leinfelden-Echterdingen DEX) Hellbach Manfred (Ostfildern DEX) Meixner Gerhard (Filderstadt D, Hammer drill.
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