US2752808A

US2752808A - Torque controlled wrench

Info

Publication number: US2752808A
Application number: US492219A
Authority: US
Inventors: Harold C Reynolds
Original assignee: Ingersoll Rand Co
Current assignee: Ingersoll Rand Co
Priority date: 1955-03-04
Filing date: 1955-03-04
Publication date: 1956-07-03
Anticipated expiration: 1973-07-03

Description

July 3, 1956 Filed March 4, 1955 c. REYNOLDS 2,752,808

TORQUE CONTROLLED WRENCH 2 Sheets-Sheet l 4 INVENTOR FLUID MOTOR HAROLD C. REYNOLDS HIS ATTORNEY July 3, 1956 c. REYNOLDS 2,752,808

TORQUE CONTROLLED WRENCH Filed March 4, 1955 2 SheetsSheet 2 INVENTOR HAROLD 6. REYNOLDS BY 4".

90 F766 HIS ATTORNEY TORQUE CQNTRQLLED WRENCH Harold C. Reynolds, Athens, Pa., assignor to Ingersoll- Rand Company, New Yorlz, N. Y., a corporation of New Jersey Application March 4, 1955', Serial No. 492,219

9 Claims. (Cl. 81--52.4)

This invention relates to power tools, and more particularly to fluid-operated torque-controlled wrenches.

One object of the invention is to provide a motor driven wrench construction which develops a predetermined maximum twisting force.

Another object is to provide such a wrench with a simple adjusting device for varying the maximum twisting orce.

A further object is to provide a motor driven wrench construction which is adapted to automatically shut down the motor when a predetermined degree of tightness in a workpiece is reached.

Another object is to provide such a wrench with a shut-down device having a high degree of sensitivity and which is so located as to be substantially foolproof in operation.

Other objects will be pointed out in the following description and the accompanying drawings which illustrate a preferred embodiment of the invention in which similar numerals refer to similar parts and in which- Fig. 1 is a plan view of an angle torque-controlled wrench constructed in accordance with the practice of the 1nvent1on,

Fig. 2 is a side elevation to enlarged scale, partly in section, of the rearward portion of the wrench, and

Figs. 3, 4, and 6 are transverse sections taken along the lines 33, 4-4, 5-5 and 66, respectively, of Fig. 2 looking in the directions indicated by the arrows.

Referring to the drawings, the invention is shown as applied to an angle wrench 28 adapted to deliver twisting force, or torque, to a socket adapter spindle 22 for rotating a workpiece. The wrench 20 comprises a body or casing 24 containing a conventional air motor 26 for driving the spindle 22, which is controlled by moving a control valve handle 28. The casing 24 supports a lever, or handle 30, movable relative thereto for actuating a normal1y-open shut-down valve 31 to stop the motor 26 when the workpiece attains predetermined degree of tightness.

Pressure fluid for driving the motor 26 is conducted thereto through a conduit 32 connected to the casing 24 and through an internal supply passage 34 to a normallyclosed control valve 36 arranged to be actuated by the handle 28. The valve 36 admits fluid through an inlet passage 38 to the valve 31 and thence through an outlet passage 40 to drive the motor 26. The turning force, or torque, of the motor 26 applied to the spindle 22 increases as the workpiece is tightened, and there is a correspondingly increasing reaction force tending to rotate the casing 24 about the axis of the workpiece in the direction opposite to the rotation of the spindle. This reaction force is resisted by the operator in holding the handle 30, and a spring 42 biased between the casing 24 and handle prevents relative movement therebetween whenever the degree of tightness of the work is below a predetermined value Above this value, the reaction force overcomes the resistance of the spring 42 and moves the States Patent 0 Patented July 3, 1956 casing 24 relative to the handle to actuate a trip valve 44 for shutting down the motor.

Referring in greater detail to the construction of the wrench shown in Figs. 2 and 4, the flow of pressure fluid to the motor 26 during the operation thereof is regulated by the manually-operated control valve 36. For this purpose the valve 36 comprises a valve member 46 adapted to seat against a valve body 48 fitted in the casing 24 and communicating the supply passage 34 with the inlet passage 38. The valve member 46 is noramlly held in the closed position by a spring 50 biased between one end thereof and a plug 51 threaded in the casing, and is operable into the open position by the handle 28 which bears against the opposite end of the member 46 and is pivotally mounted on the casing 24 by a pin 52 (see Fig. 5).

The shut-down valve 31 is arranged to cut off the flow of pressure fluid to the motor 26 when the nut or bolt being tightened attains the predetermined degree of tightness. To this end the valve 31, similar to that described in my copending application, Serial No. 378,888, filed September 8, 1953, comprises a valve body 54 fitting the casing 24 and containing a valve chamber 56 to accommodate a valve member 58 slidable therein for controlling communication between the inlet passage 38 and the outlet passage 40. The valve body 54 is provided with a series of ports 60 in communicative alignment with an annular portion 62 of the inlet passage 38 and with a series of ports 64 in communicative alignment with an annular portion 66 of the outlet passage 40. The valve member 58 has an annular groove 68 to afford communication between the inlet and

outlet passages

38 and 40 when the member 58 is held in one limiting or open position by a spring 78 biased between one end thereof and a plug 72 threaded in the corresponding end of the valve body 54. The opposite end of the valve member 58 constitutes a pressure surface 74 including the bottom surface 75 of a recess 76 in that end for the reception of a head 78 located at the inner end of the trip valve 44. It will be seen that the head 78 is of similar shape but has slightly smaller dimensions than the recess '76 to define a restricted passage 80 therebetween when the trip valve 44 is in the open position.

The valve member 58 is moved into the other limiting or closed position by the application of pressure fluid to the pressure surface 74. For this purpose fluid is constantly supplied to the passage 80 through a passage 82, formed in the body 54 and the pressure surface end of the valve member 58, leading from the inlet passage 38 to that end of the member 58. In order to control the pressure of the fluid in the passage 80, the trip valve 44, which slidably fits through the valve body 54, contains an exhaust passage 84 to vent fluid from the passage 88 to the atmosphere when the valve 44 is in the open position. When the valve 44 is in the closed position-i. e., the head 78 contacts the bottom surface 75 which covers the inlet end of passage 84, flow of fluid to the atmosphere is cut' off. The flow area of the exhaust passage 84 and the area of the head 78 adjacent the passage 80 are so proportioned that sufficient back pressure is created therein to normally maintain the trip valve 44 in the open position.

Thus, as long as the trip valve 44 remains in this open position, passages 82, 8t) and 84 serve to constantly bleed a small amount of pressure from the inlet passage 38 to the atmosphere. However, when the trip valve 44 is moved into the closed position preventing the escape of fluid from the recess 76, the pressure of the fluid therein increases immediately due to the small volume of the passage 80. This increase in pressure overcomes the resistance of the spring 79 to start the valve member 58 moving and expose the whole pressure surface 7 4 to full line pressure to almost instantaneously snap the member 58 into the closed position.

The trip valve 44 is closed only when a predetermined tightening torque applied by the wrench 2t) to a workpiece is exceeded. To this end. the handle 3%, which encircles the casing 24 and closely resembles the shape thereof to provide a convenient hand grip for the wrench 2b, is movable relative to the casing 24 into two limiting positions as determined by the opposite sides of the rearward peripheral surface 86 of the c sing which serve as stops for the rearward portion 3% of the handle (see Fig. 3). Accordingly, the handle 30 is pivotally mounted on the casing 24 by a bolt 9i extending through the c g spaced relation to the axis of the spindle A nut 92. threaded on the bolt 9%, as shown in 6, maintains the handle in concentric relation to the casing to afford free movement therebetween. I

When the handle 3! is held substantially stationary by the operator during the operation of tightening; a workpiece there is an increasing force tending to rotate the casing 24 about the spindle and relative to the handle When this force compresses the spring 52, the casing Ed moves in a counterclockwise direction, as viewed in rig. 2, to operate the trip valve 44 into the closed position. To accomplish this the handle 3% is provided. with a lever as pivotally mounted on the casing on a pin r; fitted therein (also shown in Fig. 5) and engaging the outer end of the trip valve 4d. A screw threaded through the easing bears against the lever 96 to permit adjustment in the degree of pivotal movement of the handle to actuate the valve 44.

The means for yieldably holding the handle against movement relative to the casing is here shown as the spring biased between a plug threaded in the handle 50 and a washer 1&2 slidahly fitting a bore Stil -i in the casing 2.4. The spring thus mounted constantly urges the cas ing in a counter-clockwise direction (see Fig. 2) relative to the handle and into a position where the screw 94 applies litle or no pressure on the valve 4-4.

As will be readily understood, the resistance of the spring 42 determines the amount of torque required to cause relative movement between the casing 24 and the handle 30. Therefore, it is desirable to provide a means to vary the spring force in order to permit adjustment of the shut-down torque value in accordance with the tightness requirements of a workpiece. For this purpose a screw res engaging the spring washer Hi2 and threaded in the casing .24 in coaxial alignment with the bore W4 is provided. Rotation of the screw 1% results in varying the shutdown torque value which may be determined with the aid of a calibrated torque wrench connected to the spindle while the spring is being adjusted.

In the operation of the wrench in, the socket spindle 22 is applied to a workpiece (not shown) to be tightened and the operator grasps the handle Ell with one hand and with his thumb of same hand depresses the handle 28 to open the control valve as and admit pressure fluid from the supply source through the passages 34, Tall and A l and the normally-open shut-down valve 31 to operate the motor When the workpiece has attained the required degree of tightness, the resistance of the spring is overcome by the motor torque which causes the easing 24 to pivot counterclockwise (seen Fig. 2) relative to the handle 3%, thereby closing the trip valve 44- to permit pressure fluid in the passage 3t) to close the shut-down valve 31 and stop the motor.

Thereupon, the handle 28 is released and the wrench 20 is removed from the workpiece. Inasmuch as the motor is stopped and the torque on the wrench is removed, the rotates the casing 24 clockwise to its original position and the residual pressure acting on the valve member 53 dissipates through the exhaust passage 34 to the atmosphere permiting the spring 769 to move the valve member 53 back to its open position in readiness for subsequent operation of the wrench.

l claim:

l. A hand held wrench comprising, a body, a motor mounted on said body and adapted to be connected to apply a turning force to a workpiece and tending constantly to rotate the body relative to the workpiece during rotation of the workpiece, a lever movably mounted on said bony and adapted to be held against movement l tive to the workpiece, means yieldingly holding the lever against movement relative to the body, and valve means for controlling the supply of power to the motor and arranged to be actuated by relative movement between said lever and said body in response to a predeterforce applied to the workpiece for shutting oil the motor.

2. A hand held wrench comprising, a casing, a motor mounted on the casing and adapted to be connected to rotate a socket adapter spindle, valve means for controlling the supply of power to said motor, a handle provicin hand grip for the wrench and pivotally connected to the casing to move relative thereto in a plane perpendicular to the axis of said spindle into a position to actuate said valve means to cut off the supply of power to said motor, and means resiliently urging said handle in the direction away from said position.

3. A wrench comprising, a casing, a motor mounted on the casing and adapted to be connected to rotate a workpiece, valve means for controlling the supply of power to said motor, a handle for the wrench encircling the casing and pivotally connected thereto such that the rotational axis of said handle about said pivot is substantially parallel to the rotational axis of said workpiece, said casing and handle being movable relative to each other into a position to actuate said valve means to cut off the supply of power to said motor, and spring means arranged to resist such relative movement into said position.

4. A Wrench comprising, a body, a motor mounted on the body and adapted to be connected to apply a twisting force to a socket adapter spindle, shut-down valve means having one limiting position for admitting power to the motor and a second limiting position for cutting oil" power to the motor, means resiliently holding the shut-down valve means in said one limitins position, trip valve means adapted to control the supply of power to the shut-down valve means for operating the shut-down valve means into said second limiting position, a lever pivotally mounted on the body to move in a plane substantially perpendicular to the axis of said spindle, said lever and body being moved relative to each other at a maximum twisting force applied to the spindle to actuate said trip valve means, and means resiliently urging said lever and body against such relative movement.

5. A Wrench comprising, a casing, 21 motor mounted on the casing and adapted to be connected to apply a tightening torque to a workpiece, shut-clown valve means having one limiting position for admitting power to the motor and a second limiting position for cutting oil power to the motor, means constantly urging the shut-down valve means into said one limiting position, trip valve means adapted to control the supply of power to the shut-down valve means for operating the shut-down valve means into said second limiting position, a lever pivotally mounted on the casing such that the lever is moved relative to the casing in a direction substantially parallel to the rotational plane of said workpiece at a predetermined tightening torque applied to the workpiece to actuate said trip valve means to supply power to the shut-down valve means, and spring means arranged to oppose such movement and being adjustable to vary the torque at which such movement occurs.

6. A wrench comprising, a casing, a motor mounted on the casing and adapted to be connected to apply a twisting force to a socket adapter spindle, a shut-down valve for the motor and having an open position and a closed position, means resiliently urging the shut-down valve into the open position for admitting fluid under pressure to the motor, a passage in the casing for supplying pressure fluid to one end of the shut-down valve and thence to the atmosphere, a trip valve operable to cut off the flow of pressure fluid through the passage to the atmosphere for operating the shut-down valve into the closed position to stop the motor, a handle for the wrench pivotally mounted on the casing to move in a plane substantially perpendicular to the axis of said spindle and being adapted to be held substantially immovable relative to said spindle, said casing being rotated relative to said handle by a predetermined force applied by the motor to the casing to operate the trip valve, an adjustable spring arranged to resist said force applied to the casing, and means arranged to adjust said spring for predetermining said twisting force.

7. A wrench comprising, a casing, a motor within the casing adapted to be connected to apply a torque to a workpiece for rotatably tightening said workpiece, a passage in the casing arranged to supply pressure fluid to the motor, a shut-down valve for controlling the flow of pressure fluid through said passage, a handle for the Wrench pivotally connected to the casing on an axis substantially parallel to the axis of rotation of said workpiece and being movable relative to the casing to actuate the valve to stop the motor and being adapted to be held substantially stationary relative to the workpiece, said casing being moved relative to said handle in a direction opposite to the direction of rotation of the workpiece by a predetermined maximum tightening torque applied to the workpiece, and a spring interposed between the casing and the handle to resist such movement of said casing.

8. A wrench as claimed in claim 7 in which means are provided to vary the resistance of said spring for varying said maximum tightening torque.

9. A shut-down device for a torque-controlled wrench having a casing, a motor mounted on the casing for applying a tightening torque to a rotatable workpiece and valve means for controlling the supply of power to said motor, comprising a handle encircling said casing and pivotally connected thereto such that the rotational axis of said handle is in substantially parallel spaced relation to the rotational axis of said workpiece, said casing being rotated in one direction relative to said handle by a pre' determined tightening torque applied to the workpiece to actuate said valve means for cutting off the supply of power to said motor, a spring interposed between said handle and said casing to resist such movement, and adjustable means arranged to vary the force of said spring for varying the maximum tightening torque.

References Cited in the file of this patent UNITED STATES PATENTS 2,292,146 Meunier Aug. 4, 1942 2,384,399 Reynolds Sept. 4, 1945 2,410,695 Werner Nov. 5, 1946 2,422,905 Jackson June 24, 1947 2,627,770 Hautau et al Feb. 10, 1953 2,632,485 Peck Mar. 24, 1953 2,691,314 Stevens et al Oct. 12, 1954 2,700,443 Boice Jan. 25, 1955