Pneumatic impact tool

Claim 2

Pneumatic impact tool for driving a working implement having a shank portion, comprising: a cylinder having a front opening for receiving the shank portion of a working implement such that said working implement is movable axially relative to said cylinder; a differential hammer piston reciprocably powered in said cylinder, said hammer piston having a large piston area facing the impact direction; and a small piston area facing the reverse direction; said hammer cylinder comprising a rear, continuously pressurized drive chamber for imparting a substantially uniform forward directed driving force on said small, reverse direction facing piston area; and a forward, intermittently pressurized drive chamber for imparting a periodically acting, backward directed driving force on said large, impact direction facing piston area; and said cylinder including means for retaining said working implement so that said working implement receives the entire reaction force resulting from said periodically acting, backward directed driving force imparted by said forward drive chamber of said cylinder, whereby said cylinder is prevented from being influenced by said periodically acting force.

Claim 3

Impact tool according to claim 1, comprising a support sleeve slidably mounted in said cylinder for axially supporting said working implement shank portion; and wherein said forward cylinder chamber is at its front end defined partly by said support sleeve and partly by said working implement shank portion.

Claim 4

Pneumatic tool for driving a working implement having a shank portion, comprising: a housing having a front opening for receiving the shank portion of the working implement; a cylinder mounted in said housing and including means for receiving the shank portion of the working implement introduced through said front opening of said housing; a differential hammer piston reciprocably powered in said cylinder, said hammer piston having one large piston area facing the impact direction; and two smaller piston areas facing the reverse direction; said cylinder comprising a rear, continuously pressurized drive chamber for imparting a substantially uniform, forward directed driving force on one of said smaller, reverse direction facing piston areas; and a forward, intermittently pressurized drive chamber for imparting a backward directed, periodically acting driving force on said large, impact direction facing piston area; said working implement being axially movable relative to said cylinder and said cylinder including means for receiving said working implement so that said working implement receives the entire reaction force resulting from said backward directed, periodically acting driving force imparted by said forward drive chamber; and said cylinder further comprising a low pressure chamber continuously maintained at atmospheric pressure, said other of said two smaller, reverse direction facing piston areas in one direction defining said low-pressure chamber.

Claim 5

Pneumatic tool for driving a working implement having a shank portion, comprising: a housing having a front opening for receiving the shank portion of the working implement; a cylinder mounted in said housing and including means for receiving the shank portion of the working implement introduced through said front opening of said housing; a differential hammer piston reciprocably powered in said cylinder, said hammer piston having one large piston area facing the impact direction; and two smaller piston areas facing the reverse direction; said cylinder comprising a rear, continuously pressurized drive chamber for imparting a substantially uniform, forward directed driving force on one of said smaller, reverse direction facing piston areas; and a forward, intermittently pressurized drive chamber for imparting a backward directed, periodically acting driving force on said large, impact direction facing piston area; said working implement being axially movable relative to said cylinder and said cylinder including means for receiving said working implement so that said working implement receives the entire reaction force resulting from said backward directed, periodically acting driving force imparted by said forward drive chamber; and said cylinder further comprising a low pressure chamber continuously maintained at atmospheric pressure, said other of said two smaller, reverse direction facing piston areas in one direction defining said low-pressure chamber.

Claim 6

Impact tool according to claim 3 wherein said cylinder is detachably mounted to said housing and is introduced into said housing through said front opening; and comprising a spring coupled to said cylinder to urge said cylinder backwards into its position in said housing.

Claim 7

Impact tool according to claim 4, further comprising a support sleeve slidably mounted in said cylinder for axially supporting said shank portion of the working implement; and wherein said forward cylinder chamber is at its front end defined partly by said support sleeve and partly by said shank portion of the working implement which protrudes rearwardly from said support sleeve.

Claim 8

Pneumatic impact tool for driving a working implement having a shank portion, comprising: a housing; a pressure air supply means in said housing; a cylinder secured in said housing, and including means for receiving at its forward end the shank portion of the working implement; a differential hammer piston reciprocably powered in said cylinder, said piston having a large diameter piston head facing its impact direction; and a small diameter neck extending in its reverse direction; said cylinder having between both of its ends a constricted portion for receiving with a slip fit said hammer piston neck; said cylinder further comprising a rear drive chamber which is axially defined by said constricted portion and said hammer piston head; and a forward drive chamber which is axially defined by said hammer piston head and said working implement shank portion; a first accumulator chamber continuously interconnecting said rear drive chamber and said pressure air supply means; a second accumulator chamber continuously communicating with said forward drive chamber; and interacting valve means on said hammer piston and said cylinder for alternately connecting said forward drive chamber and said second accumulator chamber to said first accumulator chamber and to the atmosphere for reciprocating said hammer piston within said cylinder.

Claim 9

Pneumatic impact tool for driving a working implement having a shank portion, comprising: a housing; a pressure air supply means in said housing; a cylinder secured in said housing, and including means for receiving at its forward end the shank portion of the working implement; a differential hammer piston reciprocably powered in said cylinder, said piston having a large diameter piston head facing its impact direction; and a small diameter neck extending in its reverse direction; said cylinder having between both of its ends a constricted portion for receiving with a slip fit said hammer piston neck; said cylinder further comprising a rear drive chamber which is axially defined by said constricted portion and said hammer piston head; and a forward drive chamber which is axially defined by said hammer piston head and said working implement shank portion; a first accumulator chamber continuously interconnecting said rear drive chamber and said pressure air supply means; a second accumulator chamber continuously communicating with said forward drive chamber; and interacting valve means on said hammer piston and said cylinder for alternately connecting said forward drive chamber and said second accumulator chamber to said first accumulator chamber and to the atmosphere for reciprocating said hammer piston within said cylinder.

Claim 10

Pneumatic impact tool according to claim 6, wherein said cylinder is tube-shaped; and said first and second accumulator chambers are defined by the outer periphery of said cylinder and said housing.

Claim 11

Pneumatic impact tool according to claim 7, wherein said second accumulator chamber is annular and situated in front of said first accumulator chamber; and said housing includes an annular wall separating said second accumulator chamber from said first accumulator chamber.

Claim 12

Impact tool according to claim 8, wherein said housing surrounds said cylinder and includes means defining a space which communicates with said pressure air supply means as well as said rear cylinder chamber and which forms said first accumulator chamber.

Claim 13

Impact tool according to claim 9, wherein said cylinder is detachably mounted to said housing; and comprising means for retaining said cylinder elastically in said housing axially as well as radially.

Claim 14

Impact tool according to claim 10, comprising a spring coupled to said cylinder to urge said cylinder axial rearwardly into position in said housing.

Claim 15

Pneumatic impact tool, for driving a working implement having a shank portion, comprising: a working cylinder (13) located in a housing; a sleeve member (18) in said working cylinder (13) into which said working implement (22) is slidably mounted; a reciprocable hammer piston (26) slidably mounted in said working cylinder (13), the hammer piston (26) having front and rear face surfaces respectively defining front and rear working chambers (36,37) within said working cylinder (13), said sleeve member (18) at least partially defining said front working chamber (36) and said front working chamber (36) extending between said piston head (27) and the inserted working implement (22); said hammer piston (26) being a differential piston having a head (27) with a sliding seat and slidable in said working cylinder (13), and a neck (28) which joins the rear of the head (27) and passes through a cylindrical narrowed portion (30) in said working cylinder (13) with a sliding fit; said rear working chamber (37) being located between said piston head (27) and said cylindrical narrowed portion (30), and being continuously fed with a substantially constant supply of air pressure; means for continuously venting the portion of said working cylinder (13) located behind said narrowed portion (30); and a control means responsive to the position of said hammer piston (26) for supplying said front working chamber (36) with supply air pressure for the return stroke of said hammer piston (26) and for venting said front working chamber (36) for the working stroke of said hammer piston (26); the overall reaction force exerted by the air pressure in said rear working chamber (37) being accepted by the tool housing free from vibration whereas the entire reaction force due to the air pressure in said front working chamber (36) is accepted by said working implement (22).

Claim 16

Pneumatic impact tool, for driving a working implement having a shank portion, comprising: a working cylinder (13) located in a housing; a sleeve member (18) in said working cylinder (13) into which said working implement (22) is slidably mounted; a reciprocable hammer piston (26) slidably mounted in said working cylinder (13), the hammer piston (26) having front and rear face surfaces respectively defining front and rear working chambers (36,37) within said working cylinder (13), said sleeve member (18) at least partially defining said front working chamber (36) and said front working chamber (36) extending between said piston head (27) and the inserted working implement (22); said hammer piston (26) being a differential piston having a head (27) with a sliding seat and slidable in said working cylinder (13), and a neck (28) which joins the rear of the head (27) and passes through a cylindrical narrowed portion (30) in said working cylinder (13) with a sliding fit; said rear working chamber (37) being located between said piston head (27) and said cylindrical narrowed portion (30), and being continuously fed with a substantially constant supply of air pressure; means for continuously venting the portion of said working cylinder (13) located behind said narrowed portion (30); and a control means responsive to the position of said hammer piston (26) for supplying said front working chamber (36) with supply air pressure for the return stroke of said hammer piston (26) and for venting said front working chamber (36) for the working stroke of said hammer piston (26); the overall reaction force exerted by the air pressure in said rear working chamber (37) being accepted by the tool housing free from vibration whereas the entire reaction force due to the air pressure in said front working chamber (36) is accepted by said working implement (22).