Screw tightening power tool

A screw tightening power tool, comprising a rotation motor, a power supply (27) connected to the motor, an output shaft (13), a torque responsive release clutch (14) including a driving half (16) and a driven half (17) and coupling the motor to the output shaft (13), an activating rod (26) coupled to the power supply (27), a latch means (24) associated with one of the clutch halves (16) and cooperating with the activating rod (26), and a cam (30) associated with the other of the clutch halves (17) and operatively connected to the latch (24) for making the latch shift from an activating rod (26) supporting position to an activating rod (26) releasing position as the transferred torque has reached the actual preset release torque level of the clutch. The cam (30) comprises a spindle (30) which is rotatively supported relative to the driven clutch half (17) for a limited rotational movement relative thereto.

I claim:

1. A screw tightening power comprising:

a rotation motor;

a power supply means (27) connected to said motor for selectively supplying a pressure fluid for driving said motor, and said power supply means (27) being shiftable between an open position for supplying pressure fluid to said motor and a closed position;

an output shaft (13);

a torque responsive release clutch (14) including a driving clutch half (16) and a driven clutch half (17) each having a given number of first coupling means (18, 22) providing a corresponding number of alternative relative engagement positions between said clutch halves (16, 17), and which in said alternative relative engagement positions couple said motor to said output shaft (13);

an activating rod (26) coupled to said power supply means (27) and being axially movable between a supported position, which is a power supply means (27) activating position, and a released position, which is a power supply means (27) inactivating position;

latch means (24) associated with one of said clutch halves (16) and shiftable between an activating rod (26) supporting position and an activating rod (26) releasing position; and

cam means (32) associated with the other of said clutch halves (17) and operatively connected to said latch means (24) for making said latch means (24) shift from said activating rod (26) supporting position to said activating rod (26) releasing position as transferred torque reaches a preset release torque level of said clutch (14);

said cam means (32) comprising a cam spindle (30) which is rotatively supported relative to said other of said clutch halves (17) and drivingly connected to said other of said clutch halves (17) by a second coupling means (33, 34) which provides for a limited angular freedom of said cam means (32) relative said other of said clutch halves (17);

said other of said clutch halves (17) comprising a central bore (31) in which said cam spindle (30) is received;

said second coupling means (33, 34) including means for drivingly connecting said cam spindle (30) to said other of said clutch halves (16, 17) under the provision of said limited angular freedom of said cam means (32); and

wherein said cam spindle (30) comprises cam lobes (32) of a number corresponding to the number of relative engagement positions of said clutch halves (16, 17), and said cam lobes (32) are arranged to act upon said latch means (24) each time said clutch halves (16, 17) leave their relative engagement positions as the predetermined release torque level is reached.

2. The power tool of claim 1, wherein said one of said clutch halves (17) comprises the driving clutch half (16), and said other of said clutch halves (16, 17) comprises the driven clutch half (17).

3. The power tool of claim 1, wherein said coupling means (33, 34) comprises a transverse pin (33) which is rigidly attached to said cam spindle (30) and which extends into diametrically opposite apertures (34) in said other of said clutch halves (16, 17), said apertures (34) having a diameter exceeding a diameter of said pin (33) to provide for said limited rotational movement.

4. The power tool of claim 3, wherein said apertures (34) are located so as to provide for a rotational play by means of which is accomplished a delay in activation of the latch means (24) in both opposite directions of rotation of the tool.

5. The power tool of claim 4, wherein said latch means comprises a radially movable latch member (24) which is spring biassed towards its activating rod (26) supporting position and which is formed with an aperture (29) to receive an end portion of said activating rod (26) when shifted into alignment with said activating rod (26) by said cam means of said cam spindle (30).

6. The power tool of claim 3, wherein said latch means comprises a radially movable latch member (24) which is spring biased towards its activating rod (26) supporting position and which is formed with an aperture (29) to receive an end portion of said activating rod (26) when shifted into alignment with said activating rod (26) by said cam means of said cam spindle (30).

7. The power tool of claim 1, wherein said limited rotational movement between said cam spindle (30) and said other of said clutch halves (17) provides for a delay in the latch means (24) shifting operation by said cam means (30), such that said latch means (24) is shifted after said clutch halves (16, 17) have left their relative engagement positions.

8. The power tool of claim 7, wherein said latch means comprises a radially movable latch member (24) which is spring biased towards its activating rod (26) supporting position and which is formed with an aperture (29) to receive an end portion of said activating rod (26) when shifted into alignment with said activating rod (26) by said cam means of said cam spindle (30).

9. The power tool of claim 1, wherein said latch means comprises a radially movable latch member (24) which is spring biased towards its activating rod (26) supporting position and which is formed with an aperture (29) to receive an end portion of said activating rod (26) when shifted into alignment with said activating rod (26) by said cam means of said cam spindle (30).

10. A screw tightening power tool, comprising:

a rotation motor;

a power supply means (27) connected to said motor for selectively supplying a pressure fluid for driving said motor, and said power supply means (27) being shiftable between an open position for supplying pressure fluid to said motor and a closed position;

an output shaft (13);

a torque responsive release clutch (14) including a driving clutch half (16) and a driven clutch half (17) each having a given number of first coupling means (18, 22) providing a corresponding number of alternative relative engagement positions between said clutch halves (16, 17), and which in said alternative relative engagement positions couple said motor to said output shaft (13);

an activating rod (26) coupled to said power supply means (27) and being axially movable between a supported position, which is a power supply means (27) activating position, and a released position, which is a power supply means (27) inactivating position;

latch means (24) associated with one of said clutch halves (16) and shiftable between an activating rod (26) supporting position and an activating rod (26) releasing position; and

cam means (32) associated with the other of said clutch halves (17) and operatively connected to said latch means (24) for making said latch means (24) shift from said activating rod (26) supporting position to said activating rod (26) releasing position as transferred torque reaches a preset release torque level of said clutch (14);

said cam means (32) comprising a cam spindle (30) which is rotatively supported relative to said other of said clutch halves (17) and drivingly connected to said other of said clutch halves (17) by a second coupling means (33, 34) which provides for a limited angular freedom of said cam means (32) relative said other of said clutch halves (17);

said other of said clutch halves (17) comprising a central bore (31) in which said cam spindle (30) is received;

said one of said clutch halves (17) comprising the driving clutch half (16), and said other of said clutch halves (16, 17), comprising the driven clutch half (17); and

said latch means comprising a radially movable latch member (14) which is spring biassed towards its activating rod (26) supporting position and which is formed with an aperture (29) to receive an end portion of said activating rod (26) when shifted into alignment with said activating rod (26) by said cam means of said cam spindle (30).

11. A screw tightening power tool, comprising:

a rotation motor;

a power supply means (27) connected to said motor for selectively supplying a pressure fluid for driving said motor, and said power supply means (27) being shiftable between an open position for supplying pressure fluid to said motor and a closed position;

an output shaft (13);

a torque responsive release clutch (14) including a driving clutch half (16) and a driven clutch half (17) each having a given number of first coupling means (18, 22) providing a corresponding number of alternative relative engagement positions between said clutch halves (16, 17), and which in said alternative relative engagement positions couple said motor to said output shaft (13);

an activating rod (26) coupled to said power supply means (27) and being axially movable between a supported position, which is a power supply means (27) activating position, and a released position, which is a power supply means (27) inactivating position;

latch means (24) associated with one of said clutch halves (16) and shiftable between an activating rod (26) supporting position and an activating rod (26) releasing position; and

cam means (32) associated with the other of said clutch halves (17) and operatively connected to said latch means (24) for making said latch means (24) shift from said activating rod (26) supporting position to said activating rod (26) releasing position as transferred torque reaches a preset release torque level of said clutch (14);

said cam means (32) comprising a cam spindle (30) which is rotatively supported relative to said other of said clutch halves (17) and drivingly connected to said other of said clutch halves (17) by a second coupling means (33, 34) which provides for a limited angular freedom of said cam means (32) relative said other of said clutch halves (17);

said one of said clutch halves (17) comprising the driving clutch half (16), and said other of said clutch halves (16, 17) comprising the driven clutch half (17); and

said latch means comprising a radially movable latch member (24) which is spring biassed towards its activating rod (26) supporting position and which is formed with an aperture (29) to receive an end portion of said activating rod (26) when shifted into alignment with said activating rod (26) by said cam means of said cam spindle (30).