Rotary power tool having automatic torque shift

Claim 2

A rotary pneumatic torque tool having means for automatic torque shift and comprising a motor unit (1) including a speed reducing gear having one or more reduction gear steps (5,6,7), a clutch sleeve member (12) drivingly connected to the last gear step (7) for transmitting high torque, an output shaft (14) coaxial with and rotatably mounted relative to said clutch sleeve member and connectable to means (3) for engaging a workpiece, said output shaft (14) being rotatably mounted in an internal central bearing (17) provided in the clutch sleeve member (12), an input or driving shaft (9) co-axially and rotatably journalled relative to said clutch sleeve member and connected to the motor unit at a point preceding the last gear step (7) for transmitting low torque, a torque transmission limiting coupling (18a, 18c) provided between said driving shaft (9) and said output shaft (14, 14b), and a free-wheel coupling (22,23) located between the clutch sleeve member (12) and the output shaft (14) and adapted to effect an automatic shift from low torque to high torque transmission when the predetermined maximum torque of the torque transmission limiting coupling be exceeded, said free wheel coupling including a free wheel having back stop members (24) acting in the radial direction, the free wheel clutch (22,23) and the torque transmission limiting coupling (18a, 18c) being provided in the clutch sleeve member on opposite sides of said central bearing (17).

Claim 3

A tool according to claim 1, wherein the input or driving shaft (9) is rotatably journalled in a bearing (15) located in the clutch sleeve member (12).

Claim 4

A tool according to claim 1 wherein the clutch sleeve member (12) is connected to the last gear step by means of an input connection (8a), the output shaft (14) is by means of an output connection (14a) coupled to the workpiece, and the clutch sleeve member (12) and the output shaft (14) respectively extend unsupported or freely between said input and output connections.

Claim 5

A tool according to claim 1, wherein the clutch sleeve member is provided with two axially spaced bearings (16,17) for mounting the output shaft (14) thereto, the free wheel clutch being located between said two bearings, the axially inner one of which being said central bearing.

Claim 6

A tool according to claim 4, wherein the free wheel coupling includes at least two free wheels (22 and 23).

Claim 7

A tool according to claim 13, wherein the torque transmission limiting coupling is a tooth clutch (18a, 18c) comprising a first tooth rim (18a) having axial teeth with oblique flanks and secured to the input or driving shaft (9), and a second tooth rim (18c) having axial teeth corresponding to the teeth of said first tooth rim and provided on a clutch sleeve (18b) which is axially displaceably but non-rotatably mounted on the output shaft (14b), and wherein a torque limiting spring (26) is provided between the output shaft (14) and said clutch sleeve (18b) so as to hold said tooth rims (18a, 18c) yieldably engaged.

Claim 8

A tool according to claim 6, wherein the output shaft (14b) is provided with a ball locking mechanism (27) which cooperates with said clutch sleeve (27) to lock the same when the clutch sleeve has been axially displaced from its tooth rim engaging position to its tooth rim releasing position upon exceeding the predetermined low torque limit which corresponds to said predetermined maximum torque of said torque transmission limiting coupling.

Claim 9

A tool according to claim 6, wherein the ball locking mechanism comprises a number of locking balls (27) which co-operate with the clutch sleeve (14b) and are radially movably mounted in the output shaft (14c), a locking actuating rod (28) is axially displaceably mounted in the output shaft (14, 14c) between a first position in which the rod locks the balls in a radially projected locking position, and a second position in which the balls are released to move to a radially inward position, a spring (30) is provided to bias the rod (28) towards its ball locking position, and a control rod (29) is co-axially and displaceably mounted relative to the locking rod (28) to actuate the same through said spring (30), said control rod (29) being adapted to be actuated by the workpiece so as to automatically bias the locking rod (28) towards the ball locking and ball releasing position respectively.

Claim 10

A rotary pneumatic tool such as a non-impacting nut runner, a screw driver or like tool having means for automatic torque shift, comprising a motor unit (1), speed reducing gear steps (5, 6, 7) connected to the motor unit, a clutch sleeve member (12) drivingly connected to the last one (7) of said gear steps for transmitting high torque, an output shaft (14) co-axial with and rotatably mounted relative to the clutch sleeve member, means (3) connectable to the output shaft (14) and provided for engaging and fastening a threaded fastening member, an input or driving shaft (9) co-axially and rotatably mounted relative to said clutch sleeve and connected to a speed reducing gear step preceding the last gear step (7) of the speed reducing gear for transmission of low torque, a first tooth rim (18a) having axial teeth with oblique flanks, a second tooth rim (18c) co-axial with said first tooth rim and having axial teeth corresponding to the teeth of said first tooth rim (18a) to cooperate therewith, a clutch sleeve (18b) nonrotatably but axially displaceably mounted on the output shaft (14, 14b), said displaceable clutch sleeve supporting said second tooth rim (18c) and being axially displaceable between a tooth rim releasing and a tooth rim engaging position respectively, a torque transmission limiting spring (26) provided between the output shaft (14) and said displaceable clutch sleeve (18b) so as to bias said clutch sleeve towards its tooth rim engaging position, a ball locking mechanism (27) supported by the output shaft (14c) and provided to be controlled in response to the cooperation of the threaded member with the fastening members of the tool so as to lock the displaceable clutch sleeve (18b) in its tooth rim releasing position upon transmission of high torque, and a free wheel coupling (22, 23) provided between the clutch sleeve member (12) and the output shaft (14) for effecting automatic torque shift when said first tooth rim (18a) upon exceeding a predetermined maximum low torque axially urges the second tooth rim (18c) out of engagement, thus displacing the displaceable clutch sleeve (18b) to its position where it is locked by the ball locking mechanism.

Claim 11

A rotary pneumatic tool such as a non-impacting nut runner, a screw driver or like tool having means for automatic torque shift, comprising a motor unit (1), speed reducing gear steps (5, 6, 7) connected to the motor unit, a clutch sleeve member (12) drivingly connected to the last one (7) of said gear steps for transmitting high torque, an output shaft (14) co-axial with and rotatably mounted relative to the clutch sleeve member, means (3) connectable to the output shaft (14) and provided for engaging and fastening a threaded fastening member, an input or driving shaft (9) co-axially and rotatably mounted relative to said clutch sleeve and connected to a speed reducing gear step preceding the last gear step (7) of the speed reducing gear for transmission of low torque, a first tooth rim (18a) having axial teeth with oblique flanks, a second tooth rim (18c) co-axial with said first tooth rim and having axial teeth corresponding to the teeth of said first tooth rim (18a) to cooperate therewith, a clutch sleeve (18b) nonrotatably but axially displaceably mounted on the output shaft (14, 14b), said displaceable clutch sleeve supporting said second tooth rim (18c) and being axially displaceable between a tooth rim releasing and a tooth rim engaging position respectively, a torque transmission limiting spring (26) provided between the output shaft (14) and said displaceable clutch sleeve (18b) so as to bias said clutch sleeve towards its tooth rim engaging position, a ball locking mechanism (27) supported by the output shaft (14c) and provided to be controlled in response to the cooperation of the threaded member with the fastening members of the tool so as to lock the displaceable clutch sleeve (18b) in its tooth rim releasing position upon transmission of high torque, and a free wheel coupling (22, 23) provided between the clutch sleeve member (12) and the output shaft (14) for effecting automatic torque shift when said first tooth rim (18a) upon exceeding a predetermined maximum low torque axially urges the second tooth rim (18c) out of engagement, thus displacing the displaceable clutch sleeve (18b) to its position where it is locked by the ball locking mechanism.

Claim 12

A tool according to claim 9, in which the ball locking mechanism comprises locking balls (27) radially movably mounted in the output shaft (14c) and cooperating with the displaceable clutch sleeve (18b), an axially movable locking rod (28) mounted in the output shaft (14) and displaceable between a first position, in which it locks the locking balls (27) in a radially projected position, and a second position in which the locking balls are released, a spring member (32) for biasing the locking rod (28) towards its position for locking the locking balls, and a rod member (29) which is axially movable relative to the output shaft and through said spring member (30) actuates said locking rod (28) for cooperation with the threaded member to be fastened and automatically biasing the locking rod (28) towards its ball locking and ball releasing position respectively.

Claim 13

A rotary pneumatic torque tool such as a non-impacting nut runner, a screw driver or like tool having means for automatic torque shift, comprising a motor unit (1), a power transmission connected to the motor unit and including at least one speed reducing gear step, a clutch sleeve member (12) connected to said gear step in the power transmission for transmitting high torque, an inner central bearing (17) mounted in the clutch sleeve member (12), an output shaft (14) rotatably and co-axially mounted in the inner central bearing (17) in the clutch sleeve member (12), means (3) connectable to the output shaft for fastening a threaded member, an input or driving shaft (9) mounted co-axially and rotatably relative to the clutch sleeve member (12), said input shaft (9) being connected to said power transmission at a point preceding the last of said at least one gear step in order to transmit low torque, a torque transmission limiting clutch provided to be disengaged at a predetermined maximum low torque, said clutch being located axially ahead of the central bearing (17) as seen in the direction of the power flow to form a clutch directly between the input and output shafts (9, 14), and a free wheel (22, 23) located axially after said central bearing (17) and operatively coupled between the clutch sleeve member (12) and the output shaft (14), said free wheel having radially active back stop members (24) for obtaining an automatic torque shift from low torque to high torque when the predetermined maximum torque of the torque transmission limiting coupling (18a, 18c) be exceeded.

Claim 14

A rotary pneumatic torque tool such as a non-impacting nut runner, a screw driver or like tool having means for automatic torque shift, comprising a motor unit (1), a power transmission connected to the motor unit and including at least one speed reducing gear step, a clutch sleeve member (12) connected to said gear step in the power transmission for transmitting high torque, an inner central bearing (17) mounted in the clutch sleeve member (12), an output shaft (14) rotatably and co-axially mounted in the inner central bearing (17) in the clutch sleeve member (12), means (3) connectable to the output shaft for fastening a threaded member, an input or driving shaft (9) mounted co-axially and rotatably relative to the clutch sleeve member (12), said input shaft (9) being connected to said power transmission at a point preceding the last of said at least one gear step in order to transmit low torque, a torque transmission limiting clutch provided to be disengaged at a predetermined maximum low torque, said clutch being located axially ahead of the central bearing (17) as seen in the direction of the power flow to form a clutch directly between the input and output shafts (9, 14), and a free wheel (22, 23) located axially after said central bearing (17) and operatively coupled between the clutch sleeve member (12) and the output shaft (14), said free wheel having radially active back stop members (24) for obtaining an automatic torque shift from low torque to high torque when the predetermined maximum torque of the torque transmission limiting coupling (18a, 18c) be exceeded.

Claim 15

A tool according to claim 11, comprising a ball locking mechanism (27) controlled by the cooperation between the threaded member and the fastening members of the tool, said ball locking mechanism being mounted in the output shaft (14c) and selectively locking the torque transmission limiting clutch (18c, 18c) in its disengaged position when transmitting high torque.