EP0022428A1 - Pneumatic reciprocating mechanism - Google Patents

Pneumatic reciprocating mechanism Download PDF

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Publication number
EP0022428A1
EP0022428A1 EP80850034A EP80850034A EP0022428A1 EP 0022428 A1 EP0022428 A1 EP 0022428A1 EP 80850034 A EP80850034 A EP 80850034A EP 80850034 A EP80850034 A EP 80850034A EP 0022428 A1 EP0022428 A1 EP 0022428A1
Authority
EP
European Patent Office
Prior art keywords
working
support member
pressure air
reaction
reaction support
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.)
Withdrawn
Application number
EP80850034A
Other languages
German (de)
English (en)
French (fr)
Inventor
Gunnar Christer Hansson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Atlas Copco AB
Original Assignee
Atlas Copco AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Atlas Copco AB filed Critical Atlas Copco AB
Publication of EP0022428A1 publication Critical patent/EP0022428A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
    • B25D9/14—Control devices for the reciprocating piston
    • B25D9/16—Valve arrangements therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
    • B25D17/24—Damping the reaction force

Definitions

  • This invention relates to a pneumatic reciprocating mechanism.
  • the invention concerns a reciprocating mechanism of the type having a reciprocable working member which together with a reaction support member defines a pressure air supplied working chamber.
  • the working member is balanced by on one hand the pressure in the working chamber and on the other hand the action of a spring.
  • the present invention intends to create an improved reciprocating mechanism by which the above mentioned problem is solved. This is accomplished by the invention as it is defined in the claims.
  • the impact tool shown in FIG 1 is a light chisel driving pneumatic tool provided with a pistol grip at its rear end.
  • the tool comprises a housing 10, a reciprocating working member 11 and a reaction support member 12.
  • the tool housing 10 consists of three main parts, namely a rear section 13, an intermediate section 14 and a front section 15.
  • the rear section 13 is formed in one piece with a pistol grip 16 by which the tool is supported by the operator.
  • the pistol grip 16 includes a pressure air supply passage 17, a throttle valve (not shown) operated by a trigger 18 and a nipple 19 for connection of a pressure air supply conduit.
  • the intermediate housing section 14 is threaded onto rear section 13, .. and a transverse wall 21 is clamped between the forward end of the rear section 13 and an inner shoulder 22 on the intermediate section.
  • the front section 15 is received in the forward end of the intermediate section 14 and is locked thereto by a lock ring 23.
  • the front section 15 is provided with an axially extending bore 24 for quidingly support of working member 11.
  • the front section 15 also comprises a couple of forwardly directed air outlet passages 26.
  • the working member 11 At its forward extremity, the working member 11 is provided with a chisel bit 27. The latter is positively locked thereto by means of a transverse split pin 28. At its rear end, the working member 11 carries an activation head 29. The latter is secured to the working member 11 by a transverse lock pin 31.
  • a compression spring 32 is inserted between the activation head 29 and the front section 15 of the housing 10 so as to apply a rearwardly directed biasing force on the working member 11.
  • the lock pin 31 extends in opposite directions laterally beyond the head 29 to engage two longitudinally extending grooves 33, 34 in the intermediate section 14 of the housing 10, thereby preventing the working member 11 to rotate relative to the housing 10.
  • the reaction support member 12 is reciprocably quided relative to the housing 10.
  • the reaction support member 12 comprises a reaction head 35, a high intertia balancing weight 36, and a hollow stem 37 rigidly interconnecting the reaction head 35 and the balancing weight 36.
  • the balancing weight 36 is made of lead in order to obtain a high as possible inertia.
  • the stem 37 is longitudinally quided in a central opening 38 of the transverse wall 21 and forms an axial air passage 39.
  • a quide pin 40 is rigidly secured relative to the balancing weight 36 and extends rearwardly therefrom to be quidingly received in a central bore 41 of a conical support element 42. The latter is located at the bottom of the rear housing section 13 and forms a reaction support for a compression spring 43 the opposite end of which takes support against the rear end of the balancing weight 36.
  • the reaction support member 12 is displaceably guided relative to the housing 10 by its hollow stem 37 cooperating with the central opening 38 of the transverse wall 21 and by its guide pin 40 cooperating with .. the central bore 41 of the support element 42.
  • This means that the balancing weight 36 is kept out of any contact with the inside wall of the housing section 13. Instead, there is left an annular space 44 between the balancing weight 36 and section 13 for communicating pressure air from passage 17 in the handle 16 to the forward end of weight 36.
  • the activation head 29 of the working member 11 is formed with a flat rear end surface 46 for axially supporting an elastic seal element 47. (See FIG 2-4). The latter has a flat back surface which is kept in continuous contact with surface 46 of the activation head 29 just by the action of pressure air.
  • the seal element 47 is formed with an annular rearwardly extending valve collar 48 for sealing cooperation with the reaction head 35 of the reaction support member 12, as described below.
  • the reaction head 35 is provided with an annular depression 51 which is coaxial with the seal element 47 and defined by an inwardly facing, peripheral wall 52. The latter diverge by a small angle toward the seal element 47 and has a minimum diameter slightly exceeding the nominal outer diameter of the valve collar 48.
  • the reaction head 35 is provided with an axial opening 53 communicating with the longitudinal passage 39 of stem 37, and, via a couple of lateral openings 54 in stem 37, the working chamber 49 is able to communicate with the annular space 44 and the air supply passage 17.
  • a feed valve operating within the longitudinal passage 39 of the stem 37 to control the air flow through the lateral openings 54.
  • the feed valve comprises a cylindrical element 55 sealingly quided in passage 39 and coupled to the working member 11 by means of a rod 56 extending through passage 39.
  • Rod 56 is of a considerably less diameter than passage 39 and is secured relative to the working member 11 by the transverse lock pin 31.
  • the working member 11 Due to the pressure in the working chamber 49, the working member 11 is moved forwards against the action of spring 32, and since the pressure acts upon the reaction head 35 as well, the reaction support member 12 starts to move backwards against the action of spring 43. Since the mass of the working member 11 is much less than that of the reaction support member 12 (weight 36), the acceleration of the working member 11 is much higher.
  • valve collar 48 of the seal element 47 maintains its sealing contact with the peripheral wall 52, and as the latter is conically diverging, the valve collar 48 is expanded successively by the air pressure to a diameter exceeding its normal outer diameter (see FIG 3).
  • the feed valve 55 In order to prevent pressure air from just rushing through the working chamber 49 during this venting sequence of the working cycle, the feed valve 55 has already cut off the air supply path by covering the openings 54. In this way, the feed valve is able to effectively reduce the air consumption of the tool.
  • valve collar 18 In the position shown in FIG 4, the sealing contact between valve collar 18 and the peripheral wall 52 is broken, the pressure air supply to the working chamber 49 is cut off by valve 55 and the valve collar 48 of the seal element 47 has reassuemd its nominal diameter. In this position, the work stroke is over and the working member 11 and the reaction support member 12 start moving towards each other under the action of springs 32 and 43.
  • the exhaust air leaving the working chamber 49 during operation of the mechanism is collected in the intermediate section 14 of the housing 10 and leaves the tool via the outlet openings 26 in the front housing section 15.
  • the characteristic feature of the reciprocating mechanism according to the invention is the feed valve being employed in the pressure air supply passage so as to obtain a reduction of the air consumption in relation to previous devices without affecting the output power of the device.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Percussive Tools And Related Accessories (AREA)
EP80850034A 1979-03-30 1980-03-25 Pneumatic reciprocating mechanism Withdrawn EP0022428A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE7902872A SE7902872L (sv) 1979-03-30 1979-03-30 Pneumatisk slagmekanism
SE7902872 1979-03-30

Publications (1)

Publication Number Publication Date
EP0022428A1 true EP0022428A1 (en) 1981-01-14

Family

ID=20337691

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80850034A Withdrawn EP0022428A1 (en) 1979-03-30 1980-03-25 Pneumatic reciprocating mechanism

Country Status (6)

Country Link
EP (1) EP0022428A1 (fi)
JP (1) JPS55157485A (fi)
BR (1) BR8001902A (fi)
ES (1) ES489980A1 (fi)
FI (1) FI800914A (fi)
SE (1) SE7902872L (fi)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004014616A1 (de) * 2002-07-04 2004-02-19 Atlas Copco Electric Tools Gmbh Tragbares arbeitsgerät

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2235817A1 (de) * 1971-07-23 1973-02-01 Chicago Pneumatic Tool Co Hydraulischer kolbenhammer
FR2306796A1 (fr) * 1975-04-07 1976-11-05 Nilsson Goran Alfred Mecanisme de frappe actionne par pression de fluide
DE2710920A1 (de) * 1976-03-15 1977-09-22 Nilsson Goran Alfred Einrichtung zur vibrationsdaempfung fuer werkzeuge mit einem hin- und hergehenden schlagmechanismus mit druckmittelantrieb

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2235817A1 (de) * 1971-07-23 1973-02-01 Chicago Pneumatic Tool Co Hydraulischer kolbenhammer
FR2306796A1 (fr) * 1975-04-07 1976-11-05 Nilsson Goran Alfred Mecanisme de frappe actionne par pression de fluide
DE2710920A1 (de) * 1976-03-15 1977-09-22 Nilsson Goran Alfred Einrichtung zur vibrationsdaempfung fuer werkzeuge mit einem hin- und hergehenden schlagmechanismus mit druckmittelantrieb

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004014616A1 (de) * 2002-07-04 2004-02-19 Atlas Copco Electric Tools Gmbh Tragbares arbeitsgerät

Also Published As

Publication number Publication date
ES489980A1 (es) 1980-10-01
SE7902872L (sv) 1980-10-01
JPS55157485A (en) 1980-12-08
FI800914A (fi) 1980-10-01
BR8001902A (pt) 1980-11-25

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Legal Events

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Designated state(s): DE FR GB IT NL

17P Request for examination filed

Effective date: 19810828

STAA Information on the status of an ep patent application or granted ep patent

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18D Application deemed to be withdrawn

Effective date: 19830114

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RIN1 Information on inventor provided before grant (corrected)

Inventor name: HANSSON, GUNNAR CHRISTER