EP3683021A1 - Hammer - Google Patents
Hammer Download PDFInfo
- Publication number
- EP3683021A1 EP3683021A1 EP20151879.2A EP20151879A EP3683021A1 EP 3683021 A1 EP3683021 A1 EP 3683021A1 EP 20151879 A EP20151879 A EP 20151879A EP 3683021 A1 EP3683021 A1 EP 3683021A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ram
- ring
- cylinder
- beat piece
- passage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000033001 locomotion Effects 0.000 claims abstract description 16
- 230000005540 biological transmission Effects 0.000 claims abstract description 5
- 238000013022 venting Methods 0.000 claims description 4
- 238000013459 approach Methods 0.000 claims description 3
- 238000005461 lubrication Methods 0.000 claims description 3
- 230000013011 mating Effects 0.000 claims 1
- 239000004033 plastic Substances 0.000 description 9
- 239000002184 metal Substances 0.000 description 5
- 238000013461 design Methods 0.000 description 3
- 230000003252 repetitive effect Effects 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- NAUDBLLLYYHPLG-NSISKUIASA-N ram-354 Chemical compound C1C(=O)CC[C@@]2(O)[C@H]3CC4=CC=C(OCC)C(OC)=C4[C@]21CCN3C NAUDBLLLYYHPLG-NSISKUIASA-N 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D11/00—Portable percussive tools with electromotor or other motor drive
- B25D11/005—Arrangements for adjusting the stroke of the impulse member or for stopping the impact action when the tool is lifted from the working surface
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2211/00—Details of portable percussive tools with electromotor or other motor drive
- B25D2211/003—Crossed drill and motor spindles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2211/00—Details of portable percussive tools with electromotor or other motor drive
- B25D2211/06—Means for driving the impulse member
- B25D2211/068—Crank-actuated impulse-driving mechanisms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2222/00—Materials of the tool or the workpiece
- B25D2222/54—Plastics
- B25D2222/57—Elastomers, e.g. rubber
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
- B25D2250/035—Bleeding holes, e.g. in piston guide-sleeves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
- B25D2250/191—Ram catchers for stopping the ram when entering idling mode
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
- B25D2250/345—Use of o-rings
Definitions
- the present invention relates to a ram catcher for a ram in a hammer drill.
- a typical hammer drill comprises a body in which is mounted an electric motor and a hammer mechanism.
- a tool holder is mounted on the front of the body which holds a cutting tool, such as a drill bit or a chisel.
- the hammer mechanism typically comprises a ram, slideably mounted in a cylinder, reciprocatingly driven by a piston via an air spring, the piston being reciprocatingly driven by the motor via a set of gears and a crank mechanism or wobble bearing.
- the ram in turn repeatedly strikes the end of the cutting tool via a beat piece.
- hammer drill also comprise a rotary drive mechanism which enables the tool holder to rotatingly drive the cutting tool held within the tool holder.
- the cylinder is the form of a rotatable spindle. This can be in addition to the repetitive striking of the end of the cutting tool by the beat piece (in which case, the hammer drill is operating in a hammer and drill mode) or as an alternative to the repetitive striking of the end of the cutting tool by the beat piece by switching off the hammer mechanism (in which case, the hammer drill is operating in a drill only mode).
- EP1157788 discloses such a hammer drill.
- a hammer drill comprises a body 2 having a rear handle 4 moveably mounted to the rear of the body 2.
- the rear handle 4 comprises a centre grip section 90 and two end connection sections 92; 94, one end connection section being attached to one end of the centre grip section, the other end connection section being connected to the other end of the centre grip section.
- the handle 4 is connected to the rear of the body 2 by the two end connection sections 92, 94.
- the rear handle is constructed from a plastic clam shell 100 and a rear end cap 102 which is attached to the clam shell 100 using screws (not shown).
- the rear of the body is formed by three plastic clam shells 6, 70, 72 which attach to each other and to the remainder of the body 2 using screws (not shown).
- An SDS tool holder 8 is mounted onto the front 10 of the body 2.
- the tool holder can hold a cutting tool 12, such as a drill bit.
- a motor (shown generally by dashed lines 48) is mounted within the body 2 which is powered by a mains electricity supply via a cable 14.
- a trigger switch 16 is mounted on the rear handle 4. Depression of the trigger switch 16 activates the motor in the normal manner.
- the motor drives a hammer mechanism (shown generally by dashed lines 46 in Figure 1 ), which comprises a piston 204 reciprocatingly driven by the motor via a crank shaft 206 within a spindle 150, which in turn reciprocatingly drives a ram 152 via an air spring 170 which in turn strikes, via a beat piece 156, the end of the cutting tool 12.
- the motor can rotationally drive the spindle 150 via a bevel gear 200 and torque clutch 202.
- a mode change mechanism (not shown) can switch the hammer drill between three modes of operation, namely hammer only mode, drill only mode or hammer and drill mode.
- a rotatable knob 18 is mounted on the top of the body 2. Rotation of the knob 18 changes the mode of operation of the hammer drill in well known manner.
- the spindle 150 has a longitudinal axis 154. In side of the spindle 150 is located the ram 152, forward of the piston 204, a beat piece 156, forward of the ram 152, a ram catcher located between the ram 152 and the beat piece 156 and a beat piece support structure.
- the forward end 162 of the spindle 150 forms part of the tool holder 8.
- the cutting tool 12 (shown in dashed lines in Figure 2 ) is held within the forward end 162 of the spindle 50 by the tool holder.
- the cutting tool 12 is prevented from rotating relative to the spindle 50 whilst being capable of moving axially over a limited range of movement within the forward end 162 of the spindle 150 in well known manner.
- the piston 204 is mounted directly in the rear of the spindle 150 and comprises an O ring 208 which locates in a groove formed around the main body of the piston and which provides an air tight seal between the piston and the inner wall of the spindle 150.
- the ram 152 is mounted directly in the spindle 150 and comprises a main body 166 attached to an end cap 160, via a neck 168, of smaller diameter than the main body 166 of the ram 152, located at the forward end of the ram 152.
- the ram is circular in cross section in any plane which extends perpendicularly from the longitudinal axis 154 (which is co-axial with the longitudinal axis of the spindle 150 when the ram is located inside of the spindle) of the ram 152 along its length.
- the ram 152 comprises an O ring 158 which locates in a groove formed around the main body 166 of the ram and which provides an air tight seal between the ram 152 and the inner wall of the spindle 150.
- the ram 152 is reciprocatingly driven by the piston 204 via an air spring 170 formed between the piston 204 and ram 152 in well known manner along the longitudinal axis 154.
- the air spring 170 between the ram 152 and the piston 204 is maintained by the air in the air spring 170 being prevented from escaping from (or air external of the air spring entering into) the space between the piston 204 and ram 152 due to the two O rings 208, 158.
- the ram catcher comprises a rubber ring 214 which locates against the inner wall of the spindle 150 and is axially held in position inside of the spindle by being sandwiched between a ring retainer, comprising a circlip 216 and metal washer 218, and a metal tubular insert 210 of the beat piece support structure, both being located inside of the spindle 150.
- the rubber ring 214 provides a lip which projects radially inwardly into spindle 150 towards the longitudinal axis 154.
- the diameter of the aperture formed by the rubber ring 214 is less than that of the end cap 160 of the ram 152 but similar to that of the neck 168 of the ram 152.
- a series of holes 220 are formed around the circumference of the spindle rearward of the circlip 216 which each extend through the wall of the spindle 150.
- the ram 152 is reciprocatingly driven over a range of axial positions (one of which is shown in Figure 2 ) inside of the spindle located to the rear of the ram catcher, the ram 152 being prevented from engaging the ram catcher due to the position of the beat piece 156.
- the ring 214 has no contact with any part of the ram 152 during the normal operation of the tool.
- the end cap 160 engages with the rubber ring 214 and passes through the aperture due to the ring deforming, allowing the lip to flex to enable the cap 160 to pass through it.
- the lip returns to its original shape, locating in the neck 168 of the ram to hold the ram 152 stationary (as shown in Figures 3 and 4 ).
- the beat piece 156 is supported by a beat piece support structure formed in part by the spindle 150 and in part by a support structure inside the spindle 150 comprising a metal tubular insert 210 sandwiched between an O ring 212 and the rubber ring 214 of the ram catcher.
- the beat piece 156 is circular in cross section in any plane which extends perpendicularly from the longitudinal axis 154 (which is co-axial with the longitudinal axis of the spindle 150 when the beat piece is located inside of the spindle) of the beat piece 156 along its length, the centre of the circular cross section being located on the longitudinal axis.
- the beat piece 156 comprises a middle section 172, a front section 174 and a rear section 176.
- the middle section 172 has a uniform diametered circular cross section along its length, the centre of the circular cross section being located on the longitudinal axis 154.
- the rear section 176 has a uniform diametered circular cross section along its length, the centre of the circular cross section being located on the longitudinal axis 154.
- the rear end 240 of the rear section 176 is flat and is impacted by the cap 160 of the ram 152 during normal operation.
- the rear section 176 is joined to the middle section 172 via a first angled region 242.
- the first angled region 242 engages with a correspondingly shaped first angled shoulder 244 formed on the metal insert 210 located inside the spindle when the beat piece is in its most rearward position, limiting the amount of rearward movement of the beat piece 156.
- the wall of the angled shoulder 244 is circular in cross section in any plane which extends perpendicularly from the longitudinal axis 154 of the spindle 150, the centre of the circular cross section being located on the longitudinal axis.
- the front section 174 is frusto conical in shape centred around the longitudinal axis 154 of the beat piece 156.
- the front end 246 of the front section 174 is flat and impacts the cutting tool 12 during normal operation.
- the front section 174 is joined to the middle section 172 via a second angled region 248 which is frusto conical in shape centred around the longitudinal axis 154 of the beat piece 156.
- the second angled region 248 engages with a correspondingly shaped second angled shoulder 250 formed on the inner wall of the spindle 150 when the beat piece is in its most forward position, limiting the amount of forward movement of the beat piece 156.
- the wall of the second angled shoulder 250 is circular in cross section in any plane which extends perpendicularly from the longitudinal axis 154 of the spindle 150, the centre of the circular cross section being located on the longitudinal axis 154.
- the ram strikes the beat piece 156 which in turn strikes the end of cutting tool 12 in the tool holder 8.
- the ram 152 is reciprocatingly driven over a limited range of axial movement within the spindle, the maximum distance from the piston being limited by the position of the beat piece 156 which it impacts, the position of which in turn is controlled by the end of the cutting tool 12. Whilst traveling within this range of axial movement, the O ring 158 of the ram 152 does not pass the holes 220. As such, the air spring 170 between the piston 204 and ram 152 is maintained.
- the rear section 176 projects rearwardly through the aperture of the ring 214 of the ram catcher, to enable the cap 160 of the ram 152 to strike it as shown in Figure 2 .
- the beat piece 156 When the cutting tool 12 is removed from the work piece, the beat piece 156 is able to move forward as the cutting tool 12 can extend out of the tool holder 8 to its maximum position. If the motor is still running, the piston 204 is able to drive the ram 152 via the air spring 170 further along the spindle 150, as the beat piece 156 can move forward, passing the air holes 220. Once the O ring 158 of the ram 152 has passed the air holes 220, the air is able to freely pass into and out of the spindle 150 in the space between the piston 204 and ram 152, causing the air spring 170 to be broken and thus disconnecting the drive between the piston 204 and ram 152.
- the ram 152 is able freely continue to travel along the length of the spindle 150.
- the ram 152 engages with the ram catcher, the cap 160 passing through the ring 214 allowing the neck 168 to engage with the ring, to secure the ram in the ram catcher, as seen in Figure 3 and 4 .
- the reciprocating movement of the piston 204 has no effect on the ram 152 as the air spring 170 is broken due to the holes 220 which allow air in and out of the spindle 170 in the space between the piston 204 and ram 152.
- the beat piece 156 is pushed forward in the spindle 150 by the ram 152 in the ram catcher.
- the cutting tool 12 In order to release the ram 152 from the ram catcher, the cutting tool 12 is pressed against a work piece causing it to be pushed into the tool holder 8, which in turn pushes the beat piece 156 rearwardly into engagement with the cap 160 of the ram 152, pushing it out of the ram catcher and past the holes 220. In such a position, the air spring 170 is reformed and the piston 204 is able to reciprocatingly drive the ram 152 again.
- a problem associated with the ram 152 and ram catcher of the hammer mechanism described above with reference to Figures 1 to 5 is that the ram 152 comprises an end cap 160 and neck 168. This increases the length of the ram 152.
- the part (the end cap 160) of the ram 152 which strikes the beat piece 156 has to be located a significant distance forward of the main body 166 of the ram 152 resulting in an overall longer hammer mechanism.
- the ram 152 which is slideably mounted in a cylinder 702 (which in turn is mounted in a rotatable spindle 150), comprises an end cap 160 attached to a main body 166 by a neck 168.
- the ram catcher comprises two O rings 700 which locate within the neck 168 of the ram 152, to hold the ram 152, when the beat piece 156 (which is supported by the spindle 150) has moved to a forward position and the end cap 160 has passed forward (left) through the O rings 700.
- the length of the neck 168 has to be long to accommodate both O rings 700 resulting in the end cap 160 being located a considerable distance forward of the main body 166 resulting in an overall longer hammer mechanism.
- the present invention overcomes this problem by avoiding the use of an end cap and neck on the ram.
- the hammer mechanism is that used in the DEWALT 7-12 kg hammer drill range.
- the ram 152 which is slideably mounted in a cylinder 702 (which in turn is mounted in a rotatable spindle 150), comprises a main body 166 only.
- the front end 704 of the main body 166 directly strikes the rear section end 240 of the rear section 176 of a beat piece 156. This results in an overall reduction in the length of the hammer mechanism.
- the hammer mechanism comprises a ram catcher having an O ring 706.
- the O ring 706 locates inside of a narrow central section 710 of the ram 152, to hold the ram 152, when the beat piece 156 has moved to a forward position and the front end 704 has passed forward (left) through the O ring 706.
- the O ring 706 is mounted within a groove 708 formed in the internal wall 712 of the cylinder 702. The manufacture of a cylinder 702 with an internal groove 708 and the insertion of an O ring 706 during production is both difficult and expensive.
- the present invention overcomes this problem by mounting an O ring outside and forward of the cylinder thus avoiding the complexity and expense. Furthermore, by mounting the O ring forward of the cylinder, the length of the cylinder can be reduced.
- the hammer comprises a housing 340 in which is mounted a cylinder 302 and an electric motor 344 in well known manner.
- the cylinder 302 has a longitudinal axis 334 and forms a passage 396 along its length.
- Mounted inside the passage 396 at one end of the cylinder 302 is a piston 306.
- the piston 306 is reciprocatingly driven by a crank shaft 348 which connects to an eccentric pin 350 of a crank mechanism 352.
- the crank mechanism 352 forms part of a transmission mechanism which converts the rotary motion of the motor 344 in a reciprocating motion of the piston 302.
- the crank mechanism 352 is rotationally driven by the electric motor 344.
- a ram 304 Mounted inside of the passage 396 of the cylinder 302 in front of the piston 306 is a ram 304.
- the ram 354 is reciprocatingly driven by the reciprocating piston 302 via an air spring 308.
- the reciciprocating ram 306 repetitively strikes the rear end of a beat piece 310, which in turn transfers the impact onto the rear end of a cutting tool 356 held in a tool holder 358 mounted on the front of the housing 340.
- the beat piece 310 is held in a beat piece support structure 360 which is located forward of the cylinder 302.
- a ram catcher 362 Located between the front of the cylinder 302 and the beat piece support structure 360 is a ram catcher 362 which is described in more detail below.
- the operation of a hammer drill is well known and therefore will not be described in any more detail.
- the ram 304 is reciprocatingly driven by the oscillating piston 306 via the air spring 308.
- the ram 304 repetitively strikes the beat piece 310 which in turn transfers the impact to the cutting tool 356 in well-known manner.
- Figure 9 shows the ram 304 and beat piece 310 in their normal working positions.
- the beat piece 310 moves to its most forward position (left in Figure 7 ) allowing the ram 304 to move to a forward space 312 where it is caught by the ram catcher 362.
- Figure 10 shows the ram 304 and beat piece 310 when the beat piece 310 is in a forward position and the ram 304 is held by the ram catcher 362.
- the ram 304 comprises a front section 328 having a diameter equal to that of the inner diameter of the cylinder 302, a middle section 330 of reduced diameter, and a rear section 332 having a diameter equal to that of the front section and the inner diameter of the cylinder 302.
- a space 336 is formed adjacent the middle section 330 between the front section 328 and the rear section 332 which acts as a circumferential receiving groove for an O ring 326 of the ram catcher 362.
- a second circumferential groove 364 is formed around the rear section 332 in which is located an O ring 366. The O ring 366 acts as a seal between the ram 304 and the inner wall 368 of the cylinder 302.
- the beat piece 310 comprises rear section 370, a middle section 372 of greater diameter, and a front section 374.
- a rear angled section 376 connects the rear section 370 with the middle section 372.
- a front angled section 378 connects the middle section 372 with the front section 374.
- the middle section 372 locates inside of a passage 380 formed inside of the front end 360 of a tubular spindle 382.
- the inner passage 380 has a circular cross section with a constant diameter along its length.
- Two circumferential grooves 382 are formed around the middle section 372 in each of which is located an O ring 384.
- the O rings 384 act as seals.
- the front end 360 of the spindle 382 acts as the beat piece support structure.
- the rear end of the spindle 382 surrounds the front half of the cylinder 302.
- the front of the spindle 382 is mounted in bearings 384 in the housing.
- the rear of the spindle 382 is mounted on bearings 722 on the cylinder 302.
- the spindle 382 is capable of being rotationally driven, to transfer rotary movement to the cutting tool 356, in well-known manner.
- a beat piece dampener 386 and a ram catcher 362 Located between front end of the spindle 382 and the cylinder 302 is a beat piece dampener 386 and a ram catcher 362, the ram catcher 362 being located adjacent the front end of the cylinder 302 and the beat piece dampener 386 being located adjacent the front end 360 of the spindle 382.
- the beat piece dampener 386 comprises a metal washer 388 and a rebound dampener 322.
- the rebound dampener 322 comprises a large rubber ring which is sandwiched between the ram catcher 362 and the washer 388 in a compressed state, the rebound dampener 322 urging the washer 388 towards and into contact with a rear wall 390 of the front end 360 of the spindle 382.
- the washer 388 extends radially inwards so that its inner diameter is less than the inner diameter of the passage formed in the front end 360 of the spindle 382.
- the radial inner end 392 of washer 388 is tapered in a forward direction in a corresponding manner to the rear angled section 376 of the beat piece 310.
- the middle section 372 of the beat piece 310 is located forward of the washer 388. As such, the washer 388 abuts against the rear wall 390 of the front end 360 of the spindle 382.
- the rear angled section 376 makes contact with the tapered part 392 of the washer 388 and prevents further rearward movement of the beat piece 310.
- the washer 388 can move rearwardly slightly, compressing the rebound dampener 322 as it does so.
- the rebound dampener 322 absorbs the energy of the moving beat piece 310, stopping it from making any further rearward movement.
- the ram catcher 362 comprises a first plastic ring 314 which mates with a second plastic ring 316 by a rim 318 on the second plastic ring 316 locating within a recess 320 of the first plastic ring 314.
- the first plastic ring 314 comprises a passage.
- the second plastic ring 316 also comprises a passage.
- the two rings 314, 316 are arranged so that they locate next to each other in succession along the longitudinal axis 334 of the cylinder 302.
- the passage of the second ring 316 aligns with the passage 396 of the cylinder 304 and the passage of the first ring 314 aligns with the passage of the second ring 316.
- the second ring 316 is located adjacent the end of the cylinder 302.
- the first ring 314 is located adjacent the second ring 316, the second ring being located between the first ring 314 and the end of the cylinder 302.
- the plastic rings 314, 316 are held in position by being sandwiched between the rebound dampener 322 and the end of the cylinder 302.
- a circumferential groove 324 is formed at the junction between the two rings 314, 316 which faces radially inwards.
- An O ring 326 locates within the groove 324.
- a radial inner side of the O ring 326 projects inwardly towards the central axis 34 of the cylinder 2.
- the diameter, from the central axis 334, of the radial inner side of the O ring 326 is less than the outer diameter of the front section 328 of the ram 304 but greater than the middle section 330 of the ram 304.
- the groove 324 is wide enough in an axial direction to avoid squeezing the O ring 326 as well as providing enough space to allow the O ring 326 to be compressed by the ram 304 when it passes through the O ring 326.
- the ram 304 is located to the rear (right) of the O ring 326 with rear section 370 of the beat piece 310 passing through it as shown in Figure 7 .
- the motor 344 is still activated, the ram 304 and beat piece 310 move forward (left in Figure 7 ), the ram 304 moving into the forward space 312.
- the front section 328 engages with the O ring 326 causing it to compress as the front section 328 passes over the O ring 326.
- the O ring 326 reverts to its normal shape, the radial inner side of the O ring 326 projecting inwardly towards the central axis 334 of the cylinder 302 and entering the space 336 adjacent the middle section 330 between the front section 328 and the rear section 332.
- the O ring 326 is sufficiently resilient to hold the ram 304 if it rebounds, preventing the front section 328 passing back over the O ring 326 as the ram 304 will have lost a lot of momentum.
- the O ring 326 then holds the ram 304 in the forward position.
- the ram 304 In order to disengage the ram 304, from the ram catcher, the ram 304 is pushed rearwardly by the beat piece 310, for example when the cutting tool 356 engages with a work surface, the front section 328 engaging with and passing over the O ring 326 as it moves rearwardly, causing the O ring 326 to compress as the front section 328 passes over the O ring 326. Once the front section 328 has passed the O ring 326, the O ring 326 reverts to its normal shape. The O ring 326 is then located forward of the ram 304, the ram then be able to freely move.
- the second ring 316 comprises a series of notches 720 (as best seen in Figure 8 ).
- the notches 720 perform a venting function when the hammer mechanism is switched off. During the normal operation of the hammer mechanism, an air cushion forms in the space 312 between the beat piece 310 and ram 304.
- the notches 720 allow for the pressurized air in the air spring to dissipate when the ram 304 approaches the ram catcher 362 and/or after the ram 304 has been caught be the ram catcher 362.
- the air spring would remain intact and therefore, the ram 304 would be accelerated back out of the ram catcher 362 by the force of the air spring (which would be greater than the holding force of the O ring 326) towards the piston 306.
- a further function of the notches 720 is to allow lubrication to pass around and/or through the ram catcher. This provides access for lubrication to the front of the cylinder 302 where the cylinder 302 supports the spindle 382 via bearings 722.
- the first ring 314 comprises a series of tabs 714 separated by gaps 716 (as best seen in Figure 8 ).
- the rebound dampener 322 comprises a series of castellations 718 which engage with the gaps 716, the tabs 714 locating between the castellations.
- the tabs 714 centre and guide the rebound dampener 322.
- the gaps 716 provide for additional venting of the air spring between the ram 304 and beat piece 310 as well as reducing the amount of accumulation of debris in that region generated during the operation of the hammer drill.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Percussive Tools And Related Accessories (AREA)
Abstract
Description
- The present invention relates to a ram catcher for a ram in a hammer drill.
- A typical hammer drill comprises a body in which is mounted an electric motor and a hammer mechanism. A tool holder is mounted on the front of the body which holds a cutting tool, such as a drill bit or a chisel. The hammer mechanism typically comprises a ram, slideably mounted in a cylinder, reciprocatingly driven by a piston via an air spring, the piston being reciprocatingly driven by the motor via a set of gears and a crank mechanism or wobble bearing. The ram in turn repeatedly strikes the end of the cutting tool via a beat piece. When the only action on the tool bit is the repetitive striking of its end by the beat piece, the hammer drill is operating in a hammer only mode.
- Certain types of hammer drill also comprise a rotary drive mechanism which enables the tool holder to rotatingly drive the cutting tool held within the tool holder. In such constructions, the cylinder is the form of a rotatable spindle. This can be in addition to the repetitive striking of the end of the cutting tool by the beat piece (in which case, the hammer drill is operating in a hammer and drill mode) or as an alternative to the repetitive striking of the end of the cutting tool by the beat piece by switching off the hammer mechanism (in which case, the hammer drill is operating in a drill only mode).
-
EP1157788 discloses such a hammer drill. - During the operation of a hammer either in hammer only mode or in hammer and drill mode, when the cutting tool held by the tool holder is pressed against a work piece to cut the work piece, the reciprocating piston, driven by the motor, reciprocatingly drives the ram in order to repetitively strike the beat piece which in turn strikes the end of a cutting tool to cause the cutting tool to strike the work piece. When the cutting tool is removed from the work piece whilst the hammer drill is still activated, the piston continues to be reciprocatingly driven by the motor. However, it desirable to stop the ram from continuing to repetitively strike the beat piece as it will result in damaging the support structure for the beat piece and/or tool holder as the energy of the impacts are no longer being absorbed by the work piece.
- One way of achieving this is to provide a ram catcher.
US20090277659 describes such a ram catcher. - A prior art design of hammer mechanism will new de described with reference to
Figures 1 to 5 . - Referring to
Figure 1 , a hammer drill comprises a body 2 having arear handle 4 moveably mounted to the rear of the body 2. Therear handle 4 comprises a centre grip section 90 and twoend connection sections 92; 94, one end connection section being attached to one end of the centre grip section, the other end connection section being connected to the other end of the centre grip section. Thehandle 4 is connected to the rear of the body 2 by the twoend connection sections plastic clam shell 100 and arear end cap 102 which is attached to theclam shell 100 using screws (not shown). The rear of the body is formed by threeplastic clam shells - An
SDS tool holder 8 is mounted onto thefront 10 of the body 2. The tool holder can hold acutting tool 12, such as a drill bit. A motor (shown generally by dashed lines 48) is mounted within the body 2 which is powered by a mains electricity supply via acable 14. Atrigger switch 16 is mounted on therear handle 4. Depression of thetrigger switch 16 activates the motor in the normal manner. The motor drives a hammer mechanism (shown generally bydashed lines 46 inFigure 1 ), which comprises apiston 204 reciprocatingly driven by the motor via acrank shaft 206 within aspindle 150, which in turn reciprocatingly drives aram 152 via anair spring 170 which in turn strikes, via abeat piece 156, the end of thecutting tool 12. The motor can rotationally drive thespindle 150 via abevel gear 200 andtorque clutch 202. A mode change mechanism (not shown) can switch the hammer drill between three modes of operation, namely hammer only mode, drill only mode or hammer and drill mode. Arotatable knob 18 is mounted on the top of the body 2. Rotation of theknob 18 changes the mode of operation of the hammer drill in well known manner. - Referring to the
Figure 2 , thespindle 150 has alongitudinal axis 154. In side of thespindle 150 is located theram 152, forward of thepiston 204, abeat piece 156, forward of theram 152, a ram catcher located between theram 152 and thebeat piece 156 and a beat piece support structure. - The
forward end 162 of thespindle 150 forms part of thetool holder 8. During normal use, the cutting tool 12 (shown in dashed lines inFigure 2 ) is held within theforward end 162 of the spindle 50 by the tool holder. Thecutting tool 12 is prevented from rotating relative to the spindle 50 whilst being capable of moving axially over a limited range of movement within theforward end 162 of thespindle 150 in well known manner. - The
piston 204 is mounted directly in the rear of thespindle 150 and comprises anO ring 208 which locates in a groove formed around the main body of the piston and which provides an air tight seal between the piston and the inner wall of thespindle 150. - The
ram 152 is mounted directly in thespindle 150 and comprises amain body 166 attached to anend cap 160, via aneck 168, of smaller diameter than themain body 166 of theram 152, located at the forward end of theram 152. The ram is circular in cross section in any plane which extends perpendicularly from the longitudinal axis 154 (which is co-axial with the longitudinal axis of thespindle 150 when the ram is located inside of the spindle) of theram 152 along its length. Theram 152 comprises anO ring 158 which locates in a groove formed around themain body 166 of the ram and which provides an air tight seal between theram 152 and the inner wall of thespindle 150. During normal operation of the hammer, theram 152 is reciprocatingly driven by thepiston 204 via anair spring 170 formed between thepiston 204 andram 152 in well known manner along thelongitudinal axis 154. Theair spring 170 between theram 152 and thepiston 204 is maintained by the air in theair spring 170 being prevented from escaping from (or air external of the air spring entering into) the space between thepiston 204 andram 152 due to the twoO rings - The ram catcher comprises a
rubber ring 214 which locates against the inner wall of thespindle 150 and is axially held in position inside of the spindle by being sandwiched between a ring retainer, comprising acirclip 216 andmetal washer 218, and a metaltubular insert 210 of the beat piece support structure, both being located inside of thespindle 150. Therubber ring 214 provides a lip which projects radially inwardly intospindle 150 towards thelongitudinal axis 154. The diameter of the aperture formed by therubber ring 214 is less than that of theend cap 160 of theram 152 but similar to that of theneck 168 of theram 152. A series ofholes 220 are formed around the circumference of the spindle rearward of thecirclip 216 which each extend through the wall of thespindle 150. - During the normal operation of the hammer drill, when the cutting tool is engaged with a work piece, the
ram 152 is reciprocatingly driven over a range of axial positions (one of which is shown inFigure 2 ) inside of the spindle located to the rear of the ram catcher, theram 152 being prevented from engaging the ram catcher due to the position of thebeat piece 156. Thering 214 has no contact with any part of theram 152 during the normal operation of the tool. When theram 152 is able to move forward, due to the position of the beat piece, theend cap 160 engages with therubber ring 214 and passes through the aperture due to the ring deforming, allowing the lip to flex to enable thecap 160 to pass through it. Once thecap 160 has passed through thering 214, the lip returns to its original shape, locating in theneck 168 of the ram to hold theram 152 stationary (as shown inFigures 3 and4 ). - The
beat piece 156 is supported by a beat piece support structure formed in part by thespindle 150 and in part by a support structure inside thespindle 150 comprising a metaltubular insert 210 sandwiched between anO ring 212 and therubber ring 214 of the ram catcher. Thebeat piece 156 is circular in cross section in any plane which extends perpendicularly from the longitudinal axis 154 (which is co-axial with the longitudinal axis of thespindle 150 when the beat piece is located inside of the spindle) of thebeat piece 156 along its length, the centre of the circular cross section being located on the longitudinal axis. - The
beat piece 156 comprises amiddle section 172, afront section 174 and arear section 176. - The
middle section 172 has a uniform diametered circular cross section along its length, the centre of the circular cross section being located on thelongitudinal axis 154. - The
rear section 176 has a uniform diametered circular cross section along its length, the centre of the circular cross section being located on thelongitudinal axis 154. Therear end 240 of therear section 176 is flat and is impacted by thecap 160 of theram 152 during normal operation. Therear section 176 is joined to themiddle section 172 via a firstangled region 242. The firstangled region 242 engages with a correspondingly shaped firstangled shoulder 244 formed on themetal insert 210 located inside the spindle when the beat piece is in its most rearward position, limiting the amount of rearward movement of thebeat piece 156. The wall of theangled shoulder 244 is circular in cross section in any plane which extends perpendicularly from thelongitudinal axis 154 of thespindle 150, the centre of the circular cross section being located on the longitudinal axis. When the firstangled region 242 is in engagement with the firstangled shoulder 244, there is a uniform amount of contact between the two surfaces around thelongitudinal axis 154. - The
front section 174 is frusto conical in shape centred around thelongitudinal axis 154 of thebeat piece 156. Thefront end 246 of thefront section 174 is flat and impacts thecutting tool 12 during normal operation. Thefront section 174 is joined to themiddle section 172 via a secondangled region 248 which is frusto conical in shape centred around thelongitudinal axis 154 of thebeat piece 156. The secondangled region 248 engages with a correspondingly shaped secondangled shoulder 250 formed on the inner wall of thespindle 150 when the beat piece is in its most forward position, limiting the amount of forward movement of thebeat piece 156. The wall of the secondangled shoulder 250 is circular in cross section in any plane which extends perpendicularly from thelongitudinal axis 154 of thespindle 150, the centre of the circular cross section being located on thelongitudinal axis 154. When the secondangled region 248 is in engagement with the secondangled shoulder 250, there is a uniform amount of contact between the two surfaces around thelongitudinal axis 154. - When the hammer drill is operating in the normal manner with the cutting
tool 12 cutting a work piece, the ram strikes thebeat piece 156 which in turn strikes the end of cuttingtool 12 in thetool holder 8. Theram 152 is reciprocatingly driven over a limited range of axial movement within the spindle, the maximum distance from the piston being limited by the position of thebeat piece 156 which it impacts, the position of which in turn is controlled by the end of thecutting tool 12. Whilst traveling within this range of axial movement, theO ring 158 of theram 152 does not pass theholes 220. As such, theair spring 170 between thepiston 204 and ram 152 is maintained. Therear section 176 projects rearwardly through the aperture of thering 214 of the ram catcher, to enable thecap 160 of theram 152 to strike it as shown inFigure 2 . - When the
cutting tool 12 is removed from the work piece, thebeat piece 156 is able to move forward as the cuttingtool 12 can extend out of thetool holder 8 to its maximum position. If the motor is still running, thepiston 204 is able to drive theram 152 via theair spring 170 further along thespindle 150, as thebeat piece 156 can move forward, passing the air holes 220. Once theO ring 158 of theram 152 has passed the air holes 220, the air is able to freely pass into and out of thespindle 150 in the space between thepiston 204 and ram 152, causing theair spring 170 to be broken and thus disconnecting the drive between thepiston 204 andram 152. As theair spring 170 is broken, theram 152 is able freely continue to travel along the length of thespindle 150. Theram 152 engages with the ram catcher, thecap 160 passing through thering 214 allowing theneck 168 to engage with the ring, to secure the ram in the ram catcher, as seen inFigure 3 and4 . The reciprocating movement of thepiston 204 has no effect on theram 152 as theair spring 170 is broken due to theholes 220 which allow air in and out of thespindle 170 in the space between thepiston 204 andram 152. Thebeat piece 156 is pushed forward in thespindle 150 by theram 152 in the ram catcher. In order to release theram 152 from the ram catcher, the cuttingtool 12 is pressed against a work piece causing it to be pushed into thetool holder 8, which in turn pushes thebeat piece 156 rearwardly into engagement with thecap 160 of theram 152, pushing it out of the ram catcher and past theholes 220. In such a position, theair spring 170 is reformed and thepiston 204 is able to reciprocatingly drive theram 152 again. - A problem associated with the
ram 152 and ram catcher of the hammer mechanism described above with reference toFigures 1 to 5 is that theram 152 comprises anend cap 160 andneck 168. This increases the length of theram 152. In particular, the part (the end cap 160) of theram 152 which strikes thebeat piece 156 has to be located a significant distance forward of themain body 166 of theram 152 resulting in an overall longer hammer mechanism. - Referring to
Figure 11 , another prior art design of hammer mechanism is disclosed. The hammer mechanism is that used in the DEWALT D25600 hammer drill. InFigure 11 , theram 152, which is slideably mounted in a cylinder 702 (which in turn is mounted in a rotatable spindle 150), comprises anend cap 160 attached to amain body 166 by aneck 168. The ram catcher comprises two O rings 700 which locate within theneck 168 of theram 152, to hold theram 152, when the beat piece 156 (which is supported by the spindle 150) has moved to a forward position and theend cap 160 has passed forward (left) through the O rings 700. As there are two O rings 700, the length of theneck 168 has to be long to accommodate both O rings 700 resulting in theend cap 160 being located a considerable distance forward of themain body 166 resulting in an overall longer hammer mechanism. - The present invention overcomes this problem by avoiding the use of an end cap and neck on the ram.
- Referring to
Figure 12 , another prior art design of hammer mechanism is disclosed. The hammer mechanism is that used in the DEWALT 7-12 kg hammer drill range. InFigure 12 , theram 152, which is slideably mounted in a cylinder 702 (which in turn is mounted in a rotatable spindle 150), comprises amain body 166 only. Thefront end 704 of themain body 166 directly strikes therear section end 240 of therear section 176 of abeat piece 156. This results in an overall reduction in the length of the hammer mechanism. The hammer mechanism comprises a ram catcher having an O ring 706. The O ring 706 locates inside of a narrowcentral section 710 of theram 152, to hold theram 152, when thebeat piece 156 has moved to a forward position and thefront end 704 has passed forward (left) through the O ring 706. However, the O ring 706 is mounted within agroove 708 formed in theinternal wall 712 of thecylinder 702. The manufacture of acylinder 702 with aninternal groove 708 and the insertion of an O ring 706 during production is both difficult and expensive. - The present invention overcomes this problem by mounting an O ring outside and forward of the cylinder thus avoiding the complexity and expense. Furthermore, by mounting the O ring forward of the cylinder, the length of the cylinder can be reduced.
- Accordingly, there is provided a hammer drill in accordance with claim 1.
- An embodiment of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:-
-
Figure 1 shows a sketch of a side view of a prior art hammer drill; -
Figure 2 shows a cross sectional view of the hammer mechanism with the ram in a position where it can freely slide within the spindle; -
Figure 3 shows a cross sectional view of the hammer mechanism with the ram in the ram catcher and the beat piece sliding in the spindle; -
Figure 4 shows a cross sectional view of the hammer mechanism with the ram in the ram catcher and the beat piece in its furthest forward position in the spindle; -
Figure 5 shows the beat piece; -
Figure 6 shows a schematic sketch of a hammer drill having a ram catcher in accordance with the present invention; -
Figure 7 a vertical cross section of the ram catcher in accordance with an embodiment of the present invention; -
Figure 8 shows an exploded view of the cylinder, ram, beat piece and ram catcher of the hammer mechanism shown inFigure 7 ; -
Figure 9 shows a cross sectional view of the cylinder, ram, beat piece and ram catcher of the hammer mechanism ofFigure 7 with the ram and beat piece in their working positions; -
Figure 10 shows a cross sectional view of the cylinder, ram, beat piece and ram catcher of the hammer mechanism ofFigure 7 with the ram caught by the ram catcher; -
Figure 11 shows a cross sectional view of the DEWALT D25600 hammer drill (prior art); and -
Figure 12 shows a cross sectional view of the DEWALT 7-12 kg hammer drill range (prior art). - An embodiment of the present invention will now be described with reference to
Figures 6 to 10 . - Referring to
Figure 6 , the hammer comprises ahousing 340 in which is mounted acylinder 302 and anelectric motor 344 in well known manner. Thecylinder 302 has alongitudinal axis 334 and forms apassage 396 along its length. Mounted inside thepassage 396 at one end of thecylinder 302 is a piston 306. The piston 306 is reciprocatingly driven by acrank shaft 348 which connects to an eccentric pin 350 of acrank mechanism 352. Thecrank mechanism 352 forms part of a transmission mechanism which converts the rotary motion of themotor 344 in a reciprocating motion of thepiston 302. Thecrank mechanism 352 is rotationally driven by theelectric motor 344. Mounted inside of thepassage 396 of thecylinder 302 in front of the piston 306 is aram 304. The ram 354 is reciprocatingly driven by thereciprocating piston 302 via anair spring 308. The reciciprocating ram 306 repetitively strikes the rear end of abeat piece 310, which in turn transfers the impact onto the rear end of a cutting tool 356 held in atool holder 358 mounted on the front of thehousing 340. Thebeat piece 310 is held in a beatpiece support structure 360 which is located forward of thecylinder 302. Located between the front of thecylinder 302 and the beatpiece support structure 360 is aram catcher 362 which is described in more detail below. The operation of a hammer drill is well known and therefore will not be described in any more detail. - Referring to
Figures 7 to 10 , during the normal operation of the hammer drill, theram 304 is reciprocatingly driven by the oscillating piston 306 via theair spring 308. Theram 304 repetitively strikes thebeat piece 310 which in turn transfers the impact to the cutting tool 356 in well-known manner.Figure 9 shows theram 304 and beatpiece 310 in their normal working positions. However, when the cutting tool 356 of the hammer drill disengages from a work piece, thebeat piece 310 moves to its most forward position (left inFigure 7 ) allowing theram 304 to move to aforward space 312 where it is caught by theram catcher 362.Figure 10 shows theram 304 and beatpiece 310 when thebeat piece 310 is in a forward position and theram 304 is held by theram catcher 362. - The
ram 304 comprises afront section 328 having a diameter equal to that of the inner diameter of thecylinder 302, amiddle section 330 of reduced diameter, and arear section 332 having a diameter equal to that of the front section and the inner diameter of thecylinder 302. Aspace 336 is formed adjacent themiddle section 330 between thefront section 328 and therear section 332 which acts as a circumferential receiving groove for anO ring 326 of theram catcher 362. A second circumferential groove 364 is formed around therear section 332 in which is located anO ring 366. TheO ring 366 acts as a seal between theram 304 and theinner wall 368 of thecylinder 302. - The
beat piece 310 comprisesrear section 370, amiddle section 372 of greater diameter, and afront section 374. A rearangled section 376 connects therear section 370 with themiddle section 372. A frontangled section 378 connects themiddle section 372 with thefront section 374. During normal operation, the rear end of therear section 370 is struck by theram 304. Themiddle section 372 locates inside of a passage 380 formed inside of thefront end 360 of atubular spindle 382. The inner passage 380 has a circular cross section with a constant diameter along its length. Twocircumferential grooves 382 are formed around themiddle section 372 in each of which is located anO ring 384. The O rings 384 act as seals. Thefront end 360 of thespindle 382 acts as the beat piece support structure. The rear end of thespindle 382 surrounds the front half of thecylinder 302. The front of thespindle 382 is mounted inbearings 384 in the housing. The rear of thespindle 382 is mounted onbearings 722 on thecylinder 302. Thespindle 382 is capable of being rotationally driven, to transfer rotary movement to the cutting tool 356, in well-known manner. - Located between front end of the
spindle 382 and thecylinder 302 is abeat piece dampener 386 and aram catcher 362, theram catcher 362 being located adjacent the front end of thecylinder 302 and thebeat piece dampener 386 being located adjacent thefront end 360 of thespindle 382. - The
beat piece dampener 386 comprises ametal washer 388 and arebound dampener 322. Therebound dampener 322 comprises a large rubber ring which is sandwiched between theram catcher 362 and thewasher 388 in a compressed state, therebound dampener 322 urging thewasher 388 towards and into contact with a rear wall 390 of thefront end 360 of thespindle 382. Thewasher 388 extends radially inwards so that its inner diameter is less than the inner diameter of the passage formed in thefront end 360 of thespindle 382. The radialinner end 392 ofwasher 388 is tapered in a forward direction in a corresponding manner to the rearangled section 376 of thebeat piece 310. During normal operation, themiddle section 372 of thebeat piece 310 is located forward of thewasher 388. As such, thewasher 388 abuts against the rear wall 390 of thefront end 360 of thespindle 382. However, when thebeat piece 310 is allowed to travel rearwardly, the rearangled section 376 makes contact with thetapered part 392 of thewasher 388 and prevents further rearward movement of thebeat piece 310. When the rearangled section 376 makes contact with thetapered part 392 of thewasher 388, thewasher 388 can move rearwardly slightly, compressing therebound dampener 322 as it does so. Therebound dampener 322 absorbs the energy of the movingbeat piece 310, stopping it from making any further rearward movement. - The
ram catcher 362 comprises a firstplastic ring 314 which mates with a secondplastic ring 316 by arim 318 on the secondplastic ring 316 locating within arecess 320 of the firstplastic ring 314. The firstplastic ring 314 comprises a passage. The secondplastic ring 316 also comprises a passage. The tworings longitudinal axis 334 of thecylinder 302. The passage of thesecond ring 316 aligns with thepassage 396 of thecylinder 304 and the passage of thefirst ring 314 aligns with the passage of thesecond ring 316. Thesecond ring 316 is located adjacent the end of thecylinder 302. Thefirst ring 314 is located adjacent thesecond ring 316, the second ring being located between thefirst ring 314 and the end of thecylinder 302. The plastic rings 314, 316 are held in position by being sandwiched between therebound dampener 322 and the end of thecylinder 302. Acircumferential groove 324 is formed at the junction between the tworings O ring 326 locates within thegroove 324. A radial inner side of theO ring 326 projects inwardly towards thecentral axis 34 of the cylinder 2. The diameter, from thecentral axis 334, of the radial inner side of theO ring 326 is less than the outer diameter of thefront section 328 of theram 304 but greater than themiddle section 330 of theram 304. Thegroove 324 is wide enough in an axial direction to avoid squeezing theO ring 326 as well as providing enough space to allow theO ring 326 to be compressed by theram 304 when it passes through theO ring 326. - During normal operation of the hammer drill, the
ram 304 is located to the rear (right) of theO ring 326 withrear section 370 of thebeat piece 310 passing through it as shown inFigure 7 . However, when the cutting tool 356 is disengaged from a work piece whilst themotor 344 is still activated, theram 304 and beatpiece 310 move forward (left inFigure 7 ), theram 304 moving into theforward space 312. As s it does so, thefront section 328 engages with theO ring 326 causing it to compress as thefront section 328 passes over theO ring 326. Once thefront section 328 has passed theO ring 326, theO ring 326 reverts to its normal shape, the radial inner side of theO ring 326 projecting inwardly towards thecentral axis 334 of thecylinder 302 and entering thespace 336 adjacent themiddle section 330 between thefront section 328 and therear section 332. TheO ring 326 is sufficiently resilient to hold theram 304 if it rebounds, preventing thefront section 328 passing back over theO ring 326 as theram 304 will have lost a lot of momentum. TheO ring 326 then holds theram 304 in the forward position. - In order to disengage the
ram 304, from the ram catcher, theram 304 is pushed rearwardly by thebeat piece 310, for example when the cutting tool 356 engages with a work surface, thefront section 328 engaging with and passing over theO ring 326 as it moves rearwardly, causing theO ring 326 to compress as thefront section 328 passes over theO ring 326. Once thefront section 328 has passed theO ring 326, theO ring 326 reverts to its normal shape. TheO ring 326 is then located forward of theram 304, the ram then be able to freely move. - The
second ring 316 comprises a series of notches 720 (as best seen inFigure 8 ). Thenotches 720 perform a venting function when the hammer mechanism is switched off. During the normal operation of the hammer mechanism, an air cushion forms in thespace 312 between thebeat piece 310 andram 304. Thenotches 720 allow for the pressurized air in the air spring to dissipate when theram 304 approaches theram catcher 362 and/or after theram 304 has been caught be theram catcher 362. Without thenotches 720, the air spring would remain intact and therefore, theram 304 would be accelerated back out of theram catcher 362 by the force of the air spring (which would be greater than the holding force of the O ring 326) towards the piston 306. A further function of thenotches 720 is to allow lubrication to pass around and/or through the ram catcher. This provides access for lubrication to the front of thecylinder 302 where thecylinder 302 supports thespindle 382 viabearings 722. - The
first ring 314 comprises a series of tabs 714 separated by gaps 716 (as best seen inFigure 8 ). Therebound dampener 322 comprises a series ofcastellations 718 which engage with thegaps 716, the tabs 714 locating between the castellations. The tabs 714 centre and guide therebound dampener 322. In addition, thegaps 716 provide for additional venting of the air spring between theram 304 and beatpiece 310 as well as reducing the amount of accumulation of debris in that region generated during the operation of the hammer drill.
Claims (16)
- A hammer drill comprising:a housing (340);a tool holder (358) mounted on the front of the housing (340);a motor (344) mounted with the housing (340);a cylinder (302) comprising a passage (396) mounted inside of the housing (340), the cylinder (302) comprising as longitudinal axis (334);a piston (306) slideably mounted within the passage (396) of the cylinder (302);a transmission mechanism (352) which is capable of converting the rotary movement of the motor (344) into a reciprocating movement of the piston (306), the motor (344) reciprocatingly driving the piston (306) via the transmission mechanism (352) in the passage (396) of the cylinder (302) when activated;a ram (304) slideably mounted within the passage (396) of the cylinder (304) which is capable of being reciprocatingly driven by the piston via an air spring (308) when the piston (306) is reciprocatingly driven by the motor, the ram (304) comprising at least one circumferential receiving groove (336);a beat piece support structure (360) mounted within the housing (340) forward of the cylinder (302) ;a beat piece (310) mounted in the beat piece support structure (360) which is capable of being struck by the reciprocating ram (304), the beat piece (310) capable of transferring the impact onto the end of a cutting tool (356) when held by the tool holder (358);a ram catcher (362) mounted in the housing between the front of the cylinder and the beat piece support structure;characterised in that the ram catcher comprises:a second ring (316) comprising a passage which aligns with the passage (396) of the cylinder (302);a first ring (314) arranged next to the second ring (316) in succession along the longitudinal axis (334) with the second ring (316), the first ring (314) comprising a passage which aligns with the passage of the second ring (316);a radially inward facing groove (324) formed by the two rings (314; 316) at the junction of the first and second rings (314; 316); anda resiliently deformable member (326) mounted in the groove (324) which projects radially inwardly from the radially inward facing groove (324);wherein, when the ram (304) travels to a forward position within the passage (396) of the cylinder (302), the resiliently deformable member (326) engages with the circumferential receiving groove (336) to hold the ram (304) in the forward position.
- A hammer drill as claimed in claim 1 wherein the first ring (314) mates with the second ring (316).
- A hammer drill as claimed in claim 2 wherein one ring (316) comprises a rim (318), the other ring (314) comprises a recess (320), the first ring (314) mating with the second ring (316) by the rim (318) locating within the recess (320).
- A hammer drill as claimed in any of the previous claims wherein the resiliently deformable member is an O ring (326).
- A hammer drill as claimed in any of the previous claims wherein the width of the radially inward facing groove (324) in an axial direction is greater than the width of the resiliently deformable member (326).
- A hammer drill as claimed in any of the previous claims wherein the ram (304) comprises a front section (328) having a diameter equal to that of the inner diameter of the cylinder (302), a middle section (330) of reduced diameter, and a rear section (332) having a diameter equal to that of the front section and the inner diameter of the cylinder (302); Wherein a space (336) is formed adjacent the middle section (330) between the front section (328) and the rear section (332) which forms the receiving groove.
- A hammer drill as claimed in claim 6 wherein the radial inner diameter of the resiliently deformable member 324) is less than the diameter of the front section (2324) of the ram (304) but is greater that the diameter of the middle section (330).
- A hammer drill as claimed in any of the previous claims wherein the second ring (316) is located adjacent the end of the cylinder (302).
- A hammer drill as claimed in any of the previous claims wherein the first ring (314) is located adjacent the second ring (316), the second ring (316 being located between the first ring (314) and the end of the cylinder (302).
- A hammer drill as claimed in any of the previous claims wherein the ram catcher sandwiched between a part of the housing and the end of a cylinder (304).
- A hammer drill as claimed in any of the previous claims wherein there is provided a spindle rotationally mounted in the housing;
wherein a part of the spindle forms the beat piece (310) support structure;
wherein the ram catcher (362) is sandwiched between the part of the spindle which forms the beat piece support structure and the end of a cylinder (302). - A hammer drill as claimed in claim 11 wherein there is provided a beat piece dampener (386) sandwiched between the part of the spindle which forms the beat piece support structure and the ram catcher (362).
- A hammer drill as claimed in any of the previous claims wherein the second ring (316) comprises a series of notches (720), wherein the notches (720) perform a venting function to allow for the pressurized air in an air spring formed in a space (312) between the beat piece (310) and ram (304) to dissipate when the ram 304 approaches the ram catcher 362 and/or after the ram (304) has been caught be the ram catcher 362.
- A hammer drill as claimed in any of the previous claims wherein the second ring (316) comprises a series of notches (720), wherein the notches (720) allow lubrication to pass around and/or through the ram catcher.
- A hammer drill as claimed in any of the previous claims wherein the first ring (314) comprises a series of tabs (714) separated by gaps (716), wherein there is provided a beat piece dampener comprising a rebound dampener (322) wherein the rebound dampener comprises a series of castellations (718) which are capable of engaging with the gaps (716) of the first ring (314), the tabs (714) locating between the castellations, the tabs centring and guiding any movement of the rebound dampener (322).
- A hammer drill as claimed in claim 13 wherein the first ring (314) comprises a series of tabs (714) separated by gaps (716), wherein the gaps (716) perform an additional venting function to allow for the pressurized air in an air spring formed in a space (312) between the beat piece (310) and ram (304) to dissipate when the ram (304) approaches the ram catcher 362 and/or after the ram (304) has been caught be the ram catcher (362).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB1900604.8A GB2580618A (en) | 2019-01-16 | 2019-01-16 | A hammer drill |
GB201914118A GB201914118D0 (en) | 2019-10-01 | 2019-10-01 | Hammer |
Publications (2)
Publication Number | Publication Date |
---|---|
EP3683021A1 true EP3683021A1 (en) | 2020-07-22 |
EP3683021B1 EP3683021B1 (en) | 2023-09-13 |
Family
ID=69172642
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20151879.2A Active EP3683021B1 (en) | 2019-01-16 | 2020-01-15 | Hammer drill |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP3683021B1 (en) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2147240A (en) * | 1983-10-01 | 1985-05-09 | Black & Decker Inc | Hammer drill |
EP1157788A2 (en) | 2000-04-07 | 2001-11-28 | Black & Decker Inc. | Rotary hammer mode change mechanism |
EP1238759A1 (en) * | 2001-03-07 | 2002-09-11 | Black & Decker Inc. | Hammer |
GB2401570A (en) * | 2003-05-12 | 2004-11-17 | Black & Decker Inc | Spindle assembly for hammer drill and method of assembly |
US20090277659A1 (en) | 2008-05-08 | 2009-11-12 | Andreas Roelfs | Hammer drill |
EP2921265A1 (en) * | 2014-03-18 | 2015-09-23 | HILTI Aktiengesellschaft | Power tool |
-
2020
- 2020-01-15 EP EP20151879.2A patent/EP3683021B1/en active Active
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2147240A (en) * | 1983-10-01 | 1985-05-09 | Black & Decker Inc | Hammer drill |
EP1157788A2 (en) | 2000-04-07 | 2001-11-28 | Black & Decker Inc. | Rotary hammer mode change mechanism |
EP1238759A1 (en) * | 2001-03-07 | 2002-09-11 | Black & Decker Inc. | Hammer |
GB2401570A (en) * | 2003-05-12 | 2004-11-17 | Black & Decker Inc | Spindle assembly for hammer drill and method of assembly |
US20090277659A1 (en) | 2008-05-08 | 2009-11-12 | Andreas Roelfs | Hammer drill |
EP2921265A1 (en) * | 2014-03-18 | 2015-09-23 | HILTI Aktiengesellschaft | Power tool |
Also Published As
Publication number | Publication date |
---|---|
EP3683021B1 (en) | 2023-09-13 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP3260241B1 (en) | Hammer | |
US6241026B1 (en) | Rotary hammer | |
EP1238759B1 (en) | Hammer | |
EP1825963B1 (en) | Powered hammer | |
US5025869A (en) | Impact drill | |
EP1027963B1 (en) | Rotary hammer | |
EP3269513B1 (en) | Impact tool | |
JPS5813312B2 (en) | electric pneumatic hammer | |
EP3213876B1 (en) | Striking device | |
EP3683021B1 (en) | Hammer drill | |
EP3822038B1 (en) | Hammer drill | |
US20200223048A1 (en) | Hammer drill | |
JP7236921B2 (en) | impact tool | |
GB2085795A (en) | A hammer drill | |
JP7338460B2 (en) | percussion work machine | |
WO2008062851A1 (en) | Percussion tool | |
US20220219305A1 (en) | Con rod | |
CN213673949U (en) | Impact tool | |
JP2024007801A (en) | Reciprocation tool | |
CN113474125A (en) | Impact working machine | |
JP2024007799A (en) | hammer drill |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN PUBLISHED |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
AX | Request for extension of the european patent |
Extension state: BA ME |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE |
|
17P | Request for examination filed |
Effective date: 20200811 |
|
RBV | Designated contracting states (corrected) |
Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: GRANT OF PATENT IS INTENDED |
|
RIC1 | Information provided on ipc code assigned before grant |
Ipc: B25D 11/00 20060101AFI20230428BHEP |
|
INTG | Intention to grant announced |
Effective date: 20230519 |
|
GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE PATENT HAS BEEN GRANTED |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: EP |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R096 Ref document number: 602020017470 Country of ref document: DE |
|
REG | Reference to a national code |
Ref country code: IE Ref legal event code: FG4D |
|
REG | Reference to a national code |
Ref country code: LT Ref legal event code: MG9D |
|
REG | Reference to a national code |
Ref country code: NL Ref legal event code: MP Effective date: 20230913 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20231214 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: RS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: NO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20231213 Ref country code: LV Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: LT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: HR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: GR Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20231214 Ref country code: FI Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 |
|
REG | Reference to a national code |
Ref country code: AT Ref legal event code: MK05 Ref document number: 1610792 Country of ref document: AT Kind code of ref document: T Effective date: 20230913 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: IS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20240113 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: AT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: ES Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SM Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: RO Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: IS Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20240113 Ref country code: ES Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: EE Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: CZ Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: AT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: PT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20240115 Ref country code: SK Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20240119 Year of fee payment: 5 Ref country code: GB Payment date: 20240124 Year of fee payment: 5 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: PL Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 Ref country code: IT Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT Effective date: 20230913 |