US3688848A - Air spring bleed assembly - Google Patents

Air spring bleed assembly Download PDF

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Publication number
US3688848A
US3688848A US124376A US3688848DA US3688848A US 3688848 A US3688848 A US 3688848A US 124376 A US124376 A US 124376A US 3688848D A US3688848D A US 3688848DA US 3688848 A US3688848 A US 3688848A
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US
United States
Prior art keywords
piston
ram
barrel
tool bit
peripheral portion
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.)
Expired - Lifetime
Application number
US124376A
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English (en)
Inventor
Stephen L Vick
Weldon H Clark Jr
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.)
Black and Decker Corp
Original Assignee
Black and Decker Manufacturing Co
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 Black and Decker Manufacturing Co filed Critical Black and Decker Manufacturing Co
Application granted granted Critical
Publication of US3688848A publication Critical patent/US3688848A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • B25D11/06—Means for driving the impulse member
    • B25D11/12—Means for driving the impulse member comprising a crank mechanism
    • B25D11/125—Means for driving the impulse member comprising a crank mechanism with a fluid cushion between the crank drive and the striking body

Definitions

  • ABSTRACT A portable electric hammer comprising a housing having an electric motor disposed therein.
  • a hollow piston is slideably supported in a barrel and is reciprocated by the motor acting through a drive train.
  • a ram is slideably disposed within the piston and is moved by the piston through alternate suction and compression generated in an air spring between the piston and ram, whereby the ram delivers longitudinal impact blows to a tool bit supported in the front end of the barrel.
  • Improved means is provided to automatically bleed air into the air spring cavity between the ram and the piston to maintain efficient hammer operation, and to automatically de-activate the ram when the tool bit is out of contact with a workpiece.
  • the present invention resides in an improved telescoping piston and ram construction in a reciprocating hammer mechanism which facilitates air replenishment in an air spring between the piston and ram during use of the mechanism, and which renders the ram inactive (idle) when the tool bit moves far enough forwardly in the housing where it cannot be struck by the ram.
  • the inventive construction embodies the utmost in simplicity, efficiency and reliability.
  • Main objects, therefore, of the present invention are to provide an improved bleed and idling assembly for an air spring in a reciprocating hammer mechanism including a ram slideably telescoped within a reciprocating piston and adapted to deliver an impact blow to a tool bit, which assembly efficiently and automatically maintains the air spring between the piston and ram at an optimum level by replenishing air therein during use of of the mechanism, and which provides for substantial immobility idling) of the ram automatically when the tool bit has moved forwardly in the barrel, such as, when the tool bit is out of contact with a workpiece.
  • FIG. 1 is a side elevational view illustrating a portable electric hammer embodying the present invention
  • FIG. 2 is an enlarged, longitudinal sectional view of a portion of FIG. 1 and showing the position of the parts following delivery of an impact blow to a tool bit;
  • FIG. 3 is a view similar to FIG. 2 showing the position of the parts during compression of the air spring and with the piston and ram moving forwardly toward impact;
  • FIG. 4 is a view similar to FIGS. 2 and 3 showing the position of the parts at impact;
  • FIG. 5 is a view similar to FIGS. 2-4 showing the position of the parts with the tool bit out of range to be struck by the ram, and the ram idling;
  • FIG. 6 is an enlarged sectional view of FIG. 2 taken along the line 6-6 thereof;
  • FIG. 7 is an enlarged sectional view of FIG. 2 taken along the line 7-7 thereof.
  • FIG. 8 is an enlarged sectional view of FIG. 5 taken along the line 8-8 thereof.
  • the present invention relates to a reciprocating hammer mechanism comprising a housing including an elongated barrel, a piston slideably reciprocated in said barrel and interconnected with a drive source, said piston including a hollow tubular forward portion and a closed rear end, a solid ram slideably reciprocated within said piston and adapted to deliver a longitudinal impact below to a tool bit supported in said barrel forwardly of said piston, said ram having a substantially continuous peripheral portion sealingly engageable with the inner wall of said piston and forming therewith an air spring within said piston between said peripheral portion and said rear wall, recess means in the inner periphery of said piston and operable to bleed air past said peripheral portion into said air spring during sub-atmospheric condition thereof, port means formed through the wall of said piston and operable to communicate said air spring with the atmosphere when said peripheral portion is adjacent said recess means, said port means being located to communicate directlywith said air spring when said tool bit is moved forwardly in said barrel and out of striking
  • the present invention relates to an air spring bleed and idler assembly for a reciprocating hammer mechanism
  • a barrel having a hollow piston slideable therein, means closing the rear end of said piston, port means extending through the wall of said piston and communicating with the atmosphere
  • said piston having a smooth inner peripheral surface interrupted by groove means formed therein, said groove means defining a total are along the inner periphery of said piston substantially less than and located between said port means and said closed end
  • said ram having a continuous peripheral portion slideably and sealingly engageable with the inner peripheral portion of said piston and having an axial dimension less than the axial dimension of said groove means, said ram being adapted to deliver a longitudinal impact blow to a tool bit supported within said barrel during reciprocation of said piston, said ram peripheral portion being confined for movement within said piston between said port means and said closed end when a tool bit is in position in said barrel, said ram peripheral portion adapted to move outwardly past said port means upon movement of said tool bit forwardly of said barrel and out of position to be struck
  • the present invention relates to a reciprocating hammer mechanism
  • a reciprocating hammer mechanism comprising a housing having an elongated barrel formed therein, a motor driven piston in said barrel and having relatively remotely spaced lands slideably engaging said barrel, said piston having a hollow forward portion, port means extending through the wall of said piston portion between said lands, a ram slidable in said hollow piston portion and movable in synchronism therewith to deliver a longitudinal impact blow to a tool bit supported by said housing in the forward end of said barrel, said ram having a substantially continuous annular portion adjacent its rearward end slidingly engaging the inner wall of said piston portion, groove means formed in the inner wall of said piston and defining a total are of substantially less than 180,said groove means having an axial length greater than the axial length of said ram annular portion, said ram having a stabilizing lip portion axially spaced forwardly of said annular portion and slidably engageable with the inner wall of said piston, said lip and annular portion being spaced
  • a portable electric hammer embodying the present invention is illustrated generally at 11 in FIG. 1 and is seen to include a housing comprising an interconnected motor housing 13, gear case 15, barrel 17, and handle 19.
  • An electric motor (not shown) is supported within the motor housing 13 and is powered from a conventional electric power source connected thereto by means of a line cord 21.
  • a suitable on-off trigger switch 23 is provided on the'handle 19 for convenient operator control of the tool.
  • the motor (not shown) has an output rotary shaft (not shown) interconnected by a gear train (not shown) with a rotatable crank 25 supported within the gear case by a bearing 27 (see FIG. 2).
  • a crack pin 29 is fixed to the crank and is rotatably interconnected with one end of a connecting rod 31.
  • the other end of the connecting rod 31 is coupled by a piston pin 33 to a piston 35 formed with longitudinally spaced lands 36, 38 slideably disposed within the barrel 17.
  • the piston 35 includes a closed rear wall 37 and an elongated skirt 39 extending forwardly therefrom.
  • a solid ram 41 is telescoped within the piston skirt 39 and has a forward end portion 43 adapted to impact against and deliver a longitudinal impact blow to a tool bit 45 supported in a bit holder 46 in the front end of the barrel 17.
  • a retainer yoke 47 is fixed to retainer rods 49, 51 which in turn are resiliently supported upon thebarrel 17 by coil compression springs 53, 55 and prevents the bit 45 from coming out ofthe barrel 17.
  • the electric motor acting through the gear train, crank 25 and connecting rod 31, reciprocates the piston 35 within the barrel 17.
  • ram 41 is also caused to reciprocate, by means of alternate suction and compression of an air spring within an air spring cavity 57 defined by the ram 41, the piston wall 37, and the tubular piston skirt 39. In so reciprocating, the forward end 43 of the ram 41 impacts against the rear end of the tool bit 45.
  • the ram 41 has a continuous peripheral portion 63 which slideably and sealingly engages the inner periphery 65 of the piston skirt 39. If desired, an annular groove 67, formed in the portion 63 of the ram 41, may carry a seal ring 69.
  • the ram 41 may also have a lip 68 positioned forwardly of the peripheral portion 63 to help stabilize the ram 41 in the piston 35.
  • the piston skirt 39 has a plurality of radial ports 71 extending therethrough.
  • the piston lands 36, 38 are provided with flats which communicate the atmosphere with the ports 71, and therefore with the interior of the piston skirt 39.
  • the inner peripheral surface 65 of the piston skirt 39 is interrupted by a plurality of recess means or grooves 73 formed therein.
  • the combined cross sectional area of the ports 71 is related to that of the grooves 73 so as not to restrict flow (bleed) of air through the grooves 73 to the air spring cavity 57. Also, the combined cross sectional area of the groves 73 is large enough (e.g., larger than the clearance between the ram sealing portion 59 and piston wall 65, or the ring gap in sealing ring 69) to insure that any air lost during compression of the air spring can be replenished during bleeding.
  • FIG. 2 shows the position of the parts following delivery of an impact blow by the ram 41 against the tool bit 45.
  • the piston 35 has already begun its return movement under the action of the crank pin 29 and connecting rod 31, while the ram 41, at this stage, is rebounding in the same direction as the piston 35 following the impact blow.
  • Continued return movement of the piston 35 causes it to overrun the rebound movement of the ram 41 as it begins to slow and the piston 35 then moves relative to the ram 41 in the return direction.
  • the sealing portion 63 of the ram 41 moves into a position adjacent the grooves 73, air is drawn in from the atmosphere through the ports 71, along the grooves 73, and into the air spring cavity 5.
  • the distance from the lip 68 to the seal portion 63 is greater than the distance from the bleed ports 71 to the grooves 73.
  • the total cross section of the ports 71 may be somewhat greater than that of the grooves 73, if the volume between the ram 'lands 36, 38 is not sufficient, so that air intake to the air spring cavi- -ty during bleeding is controlled by the cross section of the grooves 73.
  • the ports 71 are positioned so that the sealing portion 63 of the ram 41 can move forwardly thereof only when the tool bit 45 is forwardly of the holder 46.
  • the ports 71 communicate with the air spring cavity 57 only by means of the grooves 73.
  • grooves 73 are dimensioned and positioned so as to prevent the ram 41 from bottoming in the piston 39 and to allow the sealing portion 63 to. move therepast during both the suction and compression strokes.
  • the ram 41 is a solid member requiring no through openings or ports. Only the peripheral surface 63 requires machining and this greatly reduces the overall cost of the mechanism.
  • a reciprocating hammer mechanism comprising a housing including an elongated barrel, a piston slideably reciprocated in said barrel and interconnected with a drive source, said piston including a hollow tubular forward portion and a closed rear end, a solid ram slideably reciprocated within said piston and adapted to deliver a longitudinal impact blow to a tool bit supported in said barrel forwardly of said piston, said ram having a substantially continuous peripheral portion sealingly engageable with the inner wall of said piston and forming therewith an air spring within said piston between said peripheral portion and said rear wall, recess means in the inner periphery of said piston and operable to bleed air past said peripheral portion into said air spring during sub-atmospheric condition thereof, port means formed through the wall of said piston and operable to communicate said air spring with the atmosphere when said peripheral portion is adjacent said recess means, said port means being located to communicate directly with said air spring when said tool bit is moved forwardly in said barrelv and out of striking range of said ram.
  • An air spring bleed and idler assembly for a reciprocating hammer mechanism comprising a barrel having a hollow piston slideable therein, means closing the rear end of said piston, port means extending through the wall of said piston and communicating with the atmosphere, said piston having a smooth inner peripheral surface interrupted by groove means formed therein, said groove means defining avtotal arc along the inner periphery of said piston substantially less than and located between said port means and said closed end,.said ram having a continuous peripheral portion slideably and sealingly engageable with the inner peripheral portion of said piston and having an axial dimension less than the axial dimension of said groove means, said ram being adapted to deliver a longitudinal impact blow to a tool bit supported within said barrel during reciprocation of said piston, said ram peripheral portion being confined for movement within saidpiston between said port means and said closedv end when a tool bit is in position in said barrel, said ram peripheral portion adapted to move outwardly past said port means upon movement of said tool bit forwardlyof said barrel and out of position to be struck by
  • said recess means includes a plurality of grooves each of which defines a peripheral angle of approximately 8 or less, said grooves together defining a peripheral angle of substantially 45 or less.
  • said groove means includes a plurality of grooves each of which defines a peripheral angle of substantially 8 or less.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Percussive Tools And Related Accessories (AREA)
US124376A 1971-03-15 1971-03-15 Air spring bleed assembly Expired - Lifetime US3688848A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US12437671A 1971-03-15 1971-03-15

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US3688848A true US3688848A (en) 1972-09-05

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US124376A Expired - Lifetime US3688848A (en) 1971-03-15 1971-03-15 Air spring bleed assembly

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US (1) US3688848A (it)
JP (1) JPS5418426B1 (it)
IT (1) IT951029B (it)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014392A (en) * 1973-03-01 1977-03-29 Ross Frederick W Stabilized piston-cylinder impact device
US4099580A (en) * 1977-01-24 1978-07-11 Ross Frederick W Impact device with linear air spring
US4201269A (en) * 1977-01-24 1980-05-06 Ross Frederick W Impact device with linear single acting air spring
US4290492A (en) * 1979-01-31 1981-09-22 Black & Decker Inc. Idling and air replenishing system for a reciprocating hammer mechanism
EP0222698A1 (de) * 1985-11-02 1987-05-20 HILTI Aktiengesellschaft Bohrhammer mit pneumatisch angetriebenem Schlagkolben
US4841842A (en) * 1982-09-03 1989-06-27 John Macdonald & (Pneumatic Tools) Ltd. Apparatus for scabbling concrete
US5099926A (en) * 1990-04-05 1992-03-31 Makita Corporation Impact tool
US6119796A (en) * 1997-07-04 2000-09-19 Wacker-Werke Gmbh & Co., Kg Pneumatic spring percussion mechanism with an air supply
US6237700B1 (en) * 1998-06-25 2001-05-29 Wacker-Werke Gmbh & Co. Kg Pneumatic impact mechanism with a drive piston having a reduced wall thickness
US6488195B2 (en) 1998-09-18 2002-12-03 Stanley Fastening Systems, L.P. Multi-stroke fastening device
US6568484B1 (en) * 1999-06-25 2003-05-27 Wacker Construction Equipment Ag Pneumatic piston percussive mechanism with a hollow percussion piston
US20040222001A1 (en) * 2003-05-09 2004-11-11 Makita Corporation Power tool
US20050023017A1 (en) * 2003-07-31 2005-02-03 Makita Corporation Power tool
US20060156860A1 (en) * 2004-12-23 2006-07-20 Klaus-Dieter Arich Drive mechanism for power tool
JP2007223035A (ja) * 2006-02-24 2007-09-06 Black & Decker Inc パワーハンマ
US20080073096A1 (en) * 2003-07-24 2008-03-27 Wacker Construction Equipment Ag Hollow Piston Hammer Device with Air Equilibration and Idle Openings
EP2163355A1 (de) * 2008-09-12 2010-03-17 AEG Electric Tools GmbH Elektrowerkzeug umfassend einen Taumeltrieb oder Kurbeltrieb mit reduzierter Masse
US20100236802A1 (en) * 2005-06-29 2010-09-23 Wacker Construction Equipment Ag Percussive Mechanism with an Electrodynamic Linear Drive
EP2255928A1 (de) * 2009-05-28 2010-12-01 HILTI Aktiengesellschaft Werkzeugmaschine

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1043302A (en) * 1909-02-27 1912-11-05 Henry Deitz Rock-drill.
US1191948A (en) * 1914-11-09 1916-07-25 Charles B Coates Power-hammer.
US2283292A (en) * 1941-03-20 1942-05-19 Ingersoll Rand Co Percussive tool
US2333419A (en) * 1940-10-08 1943-11-02 Chicago Pneumatic Tool Co Gas hammer
US2880585A (en) * 1955-07-11 1959-04-07 Kango Electric Hammers Ltd Percussive tools

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1043302A (en) * 1909-02-27 1912-11-05 Henry Deitz Rock-drill.
US1191948A (en) * 1914-11-09 1916-07-25 Charles B Coates Power-hammer.
US2333419A (en) * 1940-10-08 1943-11-02 Chicago Pneumatic Tool Co Gas hammer
US2283292A (en) * 1941-03-20 1942-05-19 Ingersoll Rand Co Percussive tool
US2880585A (en) * 1955-07-11 1959-04-07 Kango Electric Hammers Ltd Percussive tools

Cited By (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014392A (en) * 1973-03-01 1977-03-29 Ross Frederick W Stabilized piston-cylinder impact device
US4099580A (en) * 1977-01-24 1978-07-11 Ross Frederick W Impact device with linear air spring
US4201269A (en) * 1977-01-24 1980-05-06 Ross Frederick W Impact device with linear single acting air spring
US4290492A (en) * 1979-01-31 1981-09-22 Black & Decker Inc. Idling and air replenishing system for a reciprocating hammer mechanism
US4841842A (en) * 1982-09-03 1989-06-27 John Macdonald & (Pneumatic Tools) Ltd. Apparatus for scabbling concrete
AU583952B2 (en) * 1985-11-02 1989-05-11 Hilti Aktiengesellschaft Hammer drill with a pneumatically driven striker piston
US4732219A (en) * 1985-11-02 1988-03-22 Hilti Aktiengesellschaft Hammer drill with pneumatically driven percussion piston
EP0222698A1 (de) * 1985-11-02 1987-05-20 HILTI Aktiengesellschaft Bohrhammer mit pneumatisch angetriebenem Schlagkolben
US5099926A (en) * 1990-04-05 1992-03-31 Makita Corporation Impact tool
US6119796A (en) * 1997-07-04 2000-09-19 Wacker-Werke Gmbh & Co., Kg Pneumatic spring percussion mechanism with an air supply
US6237700B1 (en) * 1998-06-25 2001-05-29 Wacker-Werke Gmbh & Co. Kg Pneumatic impact mechanism with a drive piston having a reduced wall thickness
US6488195B2 (en) 1998-09-18 2002-12-03 Stanley Fastening Systems, L.P. Multi-stroke fastening device
US6568484B1 (en) * 1999-06-25 2003-05-27 Wacker Construction Equipment Ag Pneumatic piston percussive mechanism with a hollow percussion piston
DE19929183B4 (de) * 1999-06-25 2004-07-29 Wacker Construction Equipment Ag Luftfederschlagwerk mit Hohl-Schlagkolben mit Leerlauföffnung
US20040222001A1 (en) * 2003-05-09 2004-11-11 Makita Corporation Power tool
US7096973B2 (en) * 2003-05-09 2006-08-29 Makita Corporation Power tool
US7726414B2 (en) * 2003-07-24 2010-06-01 Wacker Neuson Se Hollow piston hammer device with air equilibration and idle openings
US20080073096A1 (en) * 2003-07-24 2008-03-27 Wacker Construction Equipment Ag Hollow Piston Hammer Device with Air Equilibration and Idle Openings
US7204322B2 (en) * 2003-07-31 2007-04-17 Makita Corporation Power tool having pneumatic vibration dampening
US20050023017A1 (en) * 2003-07-31 2005-02-03 Makita Corporation Power tool
US20060156860A1 (en) * 2004-12-23 2006-07-20 Klaus-Dieter Arich Drive mechanism for power tool
US8286725B2 (en) * 2004-12-23 2012-10-16 Black & Dekcer Inc. Drive mechanism for power tool
US20100236802A1 (en) * 2005-06-29 2010-09-23 Wacker Construction Equipment Ag Percussive Mechanism with an Electrodynamic Linear Drive
US8534377B2 (en) * 2005-06-29 2013-09-17 Wacker Neuson Production GmbH & Co. KG Percussive mechanism with an electrodynamic linear drive
JP2007223035A (ja) * 2006-02-24 2007-09-06 Black & Decker Inc パワーハンマ
EP2163355A1 (de) * 2008-09-12 2010-03-17 AEG Electric Tools GmbH Elektrowerkzeug umfassend einen Taumeltrieb oder Kurbeltrieb mit reduzierter Masse
EP2255928A1 (de) * 2009-05-28 2010-12-01 HILTI Aktiengesellschaft Werkzeugmaschine
DE102009026542A1 (de) * 2009-05-28 2010-12-09 Hilti Aktiengesellschaft Werkzeugmaschine
CN101920489A (zh) * 2009-05-28 2010-12-22 喜利得股份公司 工具机
US8739895B2 (en) 2009-05-28 2014-06-03 Hilti Aktiengesellschaft Machine tool
CN101920489B (zh) * 2009-05-28 2015-03-11 喜利得股份公司 工具机

Also Published As

Publication number Publication date
JPS5418426B1 (it) 1979-07-07
IT951029B (it) 1973-06-30
AU3289871A (en) 1973-03-08

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