Open end wrench capable of fast driving

An open end wrench includes first and second jaws. The first jaw includes an arcuate sliding groove having two support walls and an arcuate sliding wall between the support walls. A slide is slideably received in the sliding groove and includes an arcuate sliding face slideable along the sliding wall. Two wings respectively extend from top and bottom faces of the slide. Top and bottom extension faces extend from a wrenching face of the slide and are located on inner faces of the wings. When the open end wrench drives a workpiece to rotate, an outer face of each wing is partially in contact with the second jaw. Force imparted from the workpiece to the wings is transmitted to the second jaw.

BACKGROUND OF THE INVENTION

The present invention relates to an open end wrench capable of fast driving and, more particularly, to an open end wrench capable of fast driving a workpiece without the risk of undesired shifting from the workpiece.

U.S. Pat. No. 1,320,668 discloses a wrench including a stationary jaw and a movable jaw slideable along a guide. The movable jaw is forced against an abutment at an outer end of the guide by a spring bearing against the stationary jaw. An end of the spring is received in a bore in the stationary jaw. The other end of the spring is received in another bore in the movable jaw. An intermediate portion of the spring is exposed between the stationary jaw and the movable jaw. When the user is intended to tighten or loosen a nut, the wrench is turned in a driving direction during which operation the movable jaw remains in contact with the abutment. For reengagement of the wrench with the nut it is necessary only to turn the wrench in the opposite direction, during which operation the movable jaw slides backward against the pressure of the spring and on the edges of the nut. The movable jaw is forced forward again as soon as the bearing surfaces of the stationary and movable jaws are parallel with the sides of the nut. The nut can be tightened or loosened through repeated operations. However, the structural strength of the wrench is insufficient for high-torque operation, as the movable jaw merely encloses the guide and is not enclosed by other members. Furthermore, the guide is irregularly formed in a wrenching space of the wrench, leading to difficulties in processing. Further, the exposed portion of the spring, when compressed by the movable jaw, is liable to bend and, thus, in frictional contact with the end edges of the bores of the stationary and movable jaws, leading to non-smooth compression of the spring or even permanent deformation of the spring. Further, the exposed portion of the spring is apt to be contaminated by oil to which debris easily adheres.

U.S. Pat. No. 3,695,125 discloses an open end ratchet wrench including a head having a fixed jaw and an opposed pawl support portion. A pawl and a spring are mounted to an inner side of the pawl support portion. The pawl is biased by the spring and slideable between an extended torquing position and a retracted ratcheting position. Two side caps are fixed to two sides of the head to define a space receiving the pawl and the spring and to prevent disengagement of the pawl and the spring. The pawl includes a stop shoulder to prevent the pawl from moving out of the pawl support portion under the action of the spring. The pawl support portion includes an arcuate section and then extends perpendicularly to the fixed jaw. Such a structure is difficult to process. Furthermore, assembly of the open end ratchet wrench is troublesome. Further, the pawl is merely enclosed at both sides and has insufficient structural strength in the lateral direction. Further, a contact area of the workpiece (such as a nut) engaged with the movable pawl is smaller than a contact area of the workpiece engaged with the fixed jaw. When the nut is tightened to a position adjacent to an object to be fixed, wear or damage to the nut may occur if the nut has insufficient contact area or has a small volume.

U.S. Pat. No. 4,706,528 discloses an adjustable wrench including a fixed jaw and an adjustable jaw. In an embodiment, a sliding jaw is provided on the fixed jaw. The sliding jaw includes a rectilinearly extending slot through which a pin is extended, preventing disengagement of the sliding jaw. A plate spring is mounted to an inner face of the fixed jaw to bias the sliding jaw outward. A hole is formed in an end wall of the slot and receives a coil spring to bias the sliding jaw inward. Thus, the sliding jaw is movable inward or outward and can be retained in place under action of the plate spring and the coil spring. Such a wrench is particularly suitable for rotating pipes, but not suitable for tightening or loosening fasteners such as bolts, nuts, or the like. This is because the sliding jaw can only slide rectilinearly, and the shape of the slot will cause the sliding jaw to slide along the slot to a position pressing against the periphery of the pipe.

U.S. Pat. No. 7,024,971 discloses an open end ratchet wrench including first and second stationary jaws. The first stationary jaw supports a movable plate. A space is sandwiched between two face plates of the first stationary jaw to accommodate the movable plate. The movable plate includes two angled slots each receiving a pin extending through the space, avoiding disengagement of the movable plate. The wrench further includes a hole receiving a spring that has an end located outside of the hole for biasing the movable plate. Each angled slot of the movable plate includes a short section and a long section at an angle to the short section such that the movable plate can move in two stages each having a rectilinear travel. However, the stationary jaw is enclosed by the movable plate such that the contact area between the stationary jaw and the workpiece is significantly decreased. Instead, the supporting effect depends on the larger contact area between the workpiece and the movable plate with structural strength weaker than the fixed jaw. The holding force applied by the open end ratchet wrench is reduced.

U.S. Publication No. 2009/0193941 A1 discloses first and second jaws formed on a jaw support. The first jaw can be moved by rotating a worm. The jaw support includes an open track in the form of a slot receiving the second jaw. The jaw support further includes a pin extending through the track. The second jaw includes a rectilinear opening through which the pin extends, preventing the second jaw from disengaging from the jaw support. A biasing member is mounted in the opening of the second jaw to bias the second jaw outward. Since the second jaw includes a single rectilinear opening, a change in the spacing from the second jaw to the first jaw is relatively small such that a workpiece will be rotated when the wrench rotates in a reverse direction not intended to rotate the workpiece. Thus, the first jaw must be movable, and the spacing between the first and second jaws can be adjusted by rotating the worm to avoid joint rotation of the workpiece when the wrench rotates in the reverse direction. However, the wrench of this type includes many elements, and the track, opening, and holes in the elements weaken the wrench. Furthermore, since the track is open, the reactive force imparted to the second jaw during driving of the workpiece is completely transmitted to the pin. Thus, the pin is liable to be damaged. Although the second jaw includes a surface in sliding contact with the jaw support to guide sliding movement of the second jaw, this surface merely transmits the reactive force to the pin instead of effectively withstanding the torque. Further, since the second jaw moves rectilinearly, the opening in the second jaw must be lengthened if it is desired to increase the spacing between the first and second jaws. However, this would expose the opening support such that the opening and the biasing member in the opening would easily be contaminated by oil to which debris adheres easily. Furthermore, operation of the biasing member would be adversely affected, causing non-smooth movement of the second jaw.

U.S. Patent Publication No. US 2009/0301271 A1 discloses an open-ended wrench including a first jaw and a second jaw. The second jaw includes an auxiliary jaw retracting opening that receives an auxiliary jaw. A spring is mounted between an end of the auxiliary jaw and an end wall of the auxiliary jaw retracting opening. The auxiliary jaw includes a limiting slot. An auxiliary jaw limiting member extends from a surface of the second jaw through an opening to the auxiliary jaw retracting opening and is coupled with the limiting slot for confining the auxiliary jaw to move between a first position in which the auxiliary jaw is non-longitudinally biased and a second position in which the auxiliary jaw is longitudinally biased. The auxiliary jaw has an arcuate pushing surface and a driving surface. In use, the wrench can drive a nut in a driving direction to a position and then directly move in a reverse direction about the center of the nut. The auxiliary jaw is compressed by a side of the nut and retracts into the auxiliary retracting opening. Thus, the wrench can be directly rotated in the reverse direction through an angle to a next driving position for driving the nut in the driving direction without the need of disengaging from the nut and reengaging with the nut. However, it is difficult to form the auxiliary jaw retracting opening in the second jaw, which is particularly true for axial drilling. Furthermore, the pushing face and the driving surface of the auxiliary jaw must retract into the auxiliary retracting opening so that the wrench can move in the reverse direction to the next driving position. Thus, the widths of the pushing face and the driving surface must be smaller than the size of the auxiliary jaw retracting opening. However, if the nut is of a smaller thickness or if the nut is moved to a position adjacent to a surface of an object to be tightened such that the width of the side of the nut is smaller than the extent of the pushing face and the driving surface, the pushing face and the driving surface may be worn or damaged due to insufficient contact area with the side of the nut.

U.S. Patent Publication No. US 2010/0071516 A1 discloses a reciprocatable open end wrench including first and second jaws and a swing member. The second jaw includes a concave arcuate surface having a slot. The swing member is received in the slot. A surface of the swing member faces the second jaw and has an arcuate hollow groove for receiving a returning device. A retaining pin is inserted into the hollow groove in a manner that allowing the swing member to be slideable relative to the second jaw. The returning device presses against the retaining pin and the swing member and, thus, biases the swing member outward. However, the diameter of the curvature of the concave arcuate face is not concentric to a wrenching width between two parallel sides of a workpiece. After the wrench has driven the workpiece to rotate in a driving direction, the rotating arc of the diameter can not allow the wrench to rotate in a reverse direction to the next driving position. Specifically, the wrench has to be moved backwards through a certain travel so that the concave arcuate face can slide along the side of the workpiece to the next driving position. If the wrench is directly rotated about the center of the workpiece without the backward travel, the arcuate face will be interfered by a side of the workpiece. The driving operation provided by the wrench is not smooth.

Thus, a need exists for an open end wrench capable of fast driving of a workpiece without the disadvantages of the above conventional open end wrenches.

BRIEF SUMMARY OF THE INVENTION

The present invention solves this need and other problems in the field of reliable structural strength of fast drivable open end wrenches by providing an open end wrench capable of fast driving a workpiece. The workpiece includes an outer periphery having first, second, third, fourth, fifth, and sixth sides respectively having first, second, third, fourth, fifth, and sixth faces in a first rotating direction and respectively having first, second, third, fourth, fifth, and sixth force-receiving faces in a second rotating direction. The open end wrench includes a body having a handle and a jaw portion formed on an end of the handle. Spaced first and second jaws are formed on an end of the jaw portion opposite to the handle. The first and second jaws and the jaw portion are integrally formed as a single and inseparable component of a same material. The jaw portion further includes a throat intermediate the first and second jaws. The first jaw includes a front end and a rear end. The rear end of the first jaw is connected to the throat. The second jaw includes a front end and a rear end. The rear end of the second jaw is connected to the throat. The throat and the first and second jaws together define a wrenching space. The wrenching space is adapted to receive the workpiece. The first jaw includes a force-applying face facing the wrenching space. The jaw portion further includes an arcuate sliding groove facing the wrenching space. The sliding groove includes spaced, first and second support walls and an arcuate sliding wall extending between the first and second support walls. A guide is fixed in the sliding groove and includes two ends fixed in the first and second support walls. A slide is slideably received in the sliding groove. The slide includes a first side having an arcuate sliding face slideable along the sliding wall of the sliding groove. The slide is capable of driving the workpiece or sliding along the outer periphery of the workpiece. The slide is movable between an extended position and a retracted position. The slide further includes a second side opposite to the first side of the slide. The second side of the slide is located outside of the sliding groove and includes a first wrenching face located in a front end of the slide. The slide further includes a top face and a bottom face. The top face slideably abuts the first support wall. The bottom face slideably abuts the second support wall. The top and bottom faces are symmetrically supported by the first and second support walls. The slide further includes an arcuate guiding slot extending from the top face through the bottom face. The guide is received in the guiding slot, preventing the slide from disengaging from the sliding groove. The guiding slot includes an abutting end and a pressing end. The front end of the slide includes two wings respectively extending away from the top and bottom faces. Each wing includes inner and outer faces. The inner faces of the wings are adapted to drive the workpiece. An elastic element is mounted in the guiding slot and has two ends respectively abutting the guide and the pressing end of the guiding slot. The elastic element urges the abutting end of the guiding slot to contact with the guide, biasing the slide to the extended position.

When the open end wrench drives the workpiece to rotate in a first direction, the slide is in the extended position, and the outer face of each wing is partially in contact with the second jaw. Force imparted from the workpiece to the two wings is transmitted to the second jaw, and the slide stably abuts the workpiece.

When the open end wrench rotates in a second direction reverse to the first direction, the slide moves towards the retracted position, and a contact area between the outer face of each wing is gradually increased. When the open end wrench reaches a next driving position for driving the workpiece to rotate in the first direction, the elastic element moves the slide to the extended position, and the contact area between the outer face of each wing is gradually decreased.

Preferably, with the first wrenching face includes a top extension face extending away from the top face and a bottom extension face extending away from the bottom face. The top and bottom extension faces are coplanar to the first wrenching face and located on the inner faces of the wings. Only a portion of the outer face of each wing contacts with the first face of the second jaw when the workpiece is driven by the open end wrench in the first direction. The outer face of each wing has a curvature equal to that of the first face of the second jaw, providing surface contact between the portion of the outer face of each wing and the first face of the second jaw.

Preferably, the sliding wall of the sliding groove is free of holes, grooves, and recesses and has a concave, arcuate face. The sliding face of the slide is free of holes, grooves, and recesses and has a convex, arcuate face. The guiding slot is free of holes, grooves, and recesses.

Preferably, the force-applying face faces the front end of the second jaw. The sliding groove is formed in the second jaw and the throat and faces the wrenching space. The force-applying face is adapted to correspond to the first force-receiving face in the first rotating direction of the workpiece. The first wrenching face and the wings of the slide are adapted to correspond to the fourth force-receiving face in the first rotating direction of the workpiece when the slide is in the extended position.

Preferably, with the sliding face of the slide has a first curvature. The sliding wall of the sliding groove has a second curvature equal to the first curvature. The sliding face of the slide is smoothly slideable along the sliding wall of the sliding groove. The sliding face is adapted to transmit reactive force from the workpiece to the sliding wall and to avoid concentration of stress on the slide, increasing torque bearing capacity of the slide when the workpiece is driven by the body to rotate. The guiding slot has a third curvature equal to the second curvature, allowing relative smooth, arcuate sliding between the guiding groove of the slide and the guide in the sliding groove without operational interference therebetween.

Preferably, the slide further includes a second wrenching face at an angle of 120° to and located behind the first wrenching face. The second wrenching face is adapted to correspond to the third force-receiving face in the first rotating direction of the workpiece. The slide further includes an evasive portion between the first and second wrenching faces. The evasive portion of the slide is adapted to allow entrance of the third force-receiving face in the second rotating direction of the workpiece.

Preferably, the throat includes a push face facing the wrenching space. The push face is at an angle of 120° to the force-applying face of the first jaw. The push face of the throat is adapted to correspond to the second force-receiving face in the first rotating direction of the workpiece.

Preferably, the second jaw includes first and second faces. The first face of the second jaw faces the wrenching space and the rear end of the first jaw. The second face of the second jaw faces the wrenching space and the front end of the first jaw. The first face of the second jaw is at an angle of 120° to the second face of the second jaw. The first and second faces of the second jaw are adapted to correspond respectively to the fourth and third force-receiving faces in the first rotating direction of the workpiece. The first face of the second jaw is parallel to the force-applying face of the first jaw. A first evasive portion is formed between the force-applying face of the first jaw and the push face of the throat. The first evasive portion is adapted to allow entrance of the first force-receiving face in the second rotating direction of the workpiece. A second evasive portion is formed between the push face of the throat and the second face of the second jaw. The second evasive portion is adapted to allow entrance of the second force-receiving face in the second rotating direction of the workpiece. The jaw portion further includes a third evasive portion between first and second faces of the second jaw. The third evasive portion is adapted to allow entrance of the third force-receiving face in the second rotating direction of workpiece.

Preferably, the first and second support walls of the sliding groove are parallel to each other and have a spacing therebetween. The top and bottom faces of the slide are parallel to each other and have a height in a height direction of the slide equal to the spacing. The guiding slot of the slide has a height in the height direction of the slide equal to the height of the slide. The guiding slot has a width in a width direction perpendicular to the height direction of the guiding slot. The width of the guiding slot is equal to a diameter of the guide. The height of the guiding slot is larger than 1.5 times the width of the guiding slot. The elastic element has a height in the height direction of the slide not larger than the height of the guiding slot. The height of the elastic element is larger than the width of the guiding slot and larger than 0.5 times the height of the guiding slot.

When the jaw portion does not receive the workpiece, the abutting end of the guiding slot is in contact with the guide. The slide is in the extended position. The first wrenching face of the slide and the top and bottom extension faces extend into the wrenching space. The first wrenching face of the slide is not parallel to the force-applying face of the first jaw.

When the jaw portion receives the workpiece but does not drive workpiece, the force-applying face of the first jaw abuts the first force-receiving face in the first rotating direction of the workpiece. The front end of slide abuts the fourth force-receiving face in the first rotating direction of the workpiece. A gap exists between the abutting end of the guiding slot and the guide. The gap is larger than a tolerance of the workpiece.

When the workpiece is rotated by the jaw portion and causes deformation of the jaw portion, the body slightly rotates relative to the workpiece. The gap prevents the slide from rotating together with the body. The front end of the slide remains abutting the fourth force-receiving face in the first rotating direction of the workpiece while the jaw portion expands elastically.

When the jaw portion receives the workpiece but does not drive the workpiece. A buffering angle is formed between the first wrenching face of slide and the fourth force-receiving face in the first rotating direction of the workpiece. The buffering angle allows the body and the slide to gradually rotate relative to the workpiece when the jaw portion expands elastically. The first wrenching face of the slide abuts the fourth force-receiving face in the first rotating direction of the workpiece, providing surface contact between the first wrenching face of the slide and the fourth force-receiving face in the first rotating direction of the workpiece. The buffering angle is larger than 2°.

Preferably, the first wrenching face of the slide includes at least one groove to increase friction between the first wrenching facer and the fourth force-receiving face in the first rotating direction of the workpiece.

Where used in the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “first”, “second”, “third”, “fourth”, “fifth”, “sixth”, “lower”, “upper”, “inner”, “outer”, “side”, “end”, “portion”, “section”, “spacing”, “clockwise”, “counterclockwise”, “width”, “height”, and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

An open end wrench10according to the present invention is shown inFIGS. 1-9. In the form shown, open end wrench10includes a body20, a slide30, and an elastic device40. Body20includes a handle21and a jaw portion22formed on an end of handle21. Jaw portion22can hold a workpiece90, such as a hexagonal head of a bolt, a nut, or the like. Workpiece90includes an outer periphery having first, second, third, fourth, fifth, and sixth sides91,92,93,94,95, and96respectively having first, second, third, fourth, fifth, and sixth force-receiving faces in a first rotating direction91A,92A,93A,94A,95A, and96A. First, second, third, fourth, fifth, and sixth sides91,92,93,94,95, and96of workpiece90respectively have first, second, third, fourth, fifth, and sixth force-receiving faces in a second rotating direction91B,92B,93B,94B,95B, and96B. A user can grip the handle21and rotate body20as well as jaw portion22about an axis of workpiece90to tighten or loosen workpiece90.

Spaced first and second jaws23and24are formed on an end of jaw portion22opposite to handle21. First and second jaws23and24can withstand reactive force from workpiece90. First and second jaws23and24face each other. Furthermore, first and second jaws23and24and jaw portion22are integrally formed as a single and inseparable component of the same material to provide jaw portion22with excellent structural strength and to increase the torque bearing capacity of jaw portion22.

Jaw portion22further includes a throat25intermediate first and second jaws23and24. Throat25and first and second jaws23and24together define a wrenching space26. Workpiece90can enter wrenching space26by moving jaw portion22in a direction perpendicular to one of the six sides of workpiece90or by moving jaw portion22along the axis of workpiece90.

First jaw23includes a front end and a rear end connected to throat25. Second jaw24includes a front end and a rear end connected to throat25.

First jaw23includes a force-applying face231facing wrenching space26and facing the front end of second jaw24. Force-applying face231corresponds to first force-receiving face in the first rotating direction91A of workpiece90. Second jaw24includes first and second faces241and242. First face241faces wrenching space26and the rear end of first jaw23. Second face242faces wrenching space26and the front end of first jaw23. First and second faces241and242correspond respectively to fourth and third force-receiving faces in the first rotating direction94A and93A. First face241of second jaw24is substantially parallel to force-applying face231of first jaw23.

Throat25includes a push face251facing wrenching space26. Push face251is at an angle of 120° to force-applying face231of first jaw23such that push face251corresponds to second force-receiving face in the first rotating direction92A. Second face242is intermediate first face241and push face251.

Jaw portion22further includes a first evasive portion221between force-applying face231of first jaw23and push face251of throat25. First evasive portion221can receive first force-receiving face in the second rotating direction91B of workpiece90. Jaw portion22further includes a second evasive portion222between push face251of throat25and second face242of second jaw24. Second evasive portion222can receive second force-receiving face in the second rotating direction92B of workpiece90. Furthermore, jaw portion22includes a third evasive portion223between first and second faces241and242of the second jaw24. Third evasive portion223can receive third force-receiving face in the second rotating direction93B of workpiece90.

An arcuate sliding groove27is formed in second jaw24and throat25and faces wrenching space26. Sliding groove27includes spaced, first and second support walls272and273and a concave, arcuate sliding wall271extending between first and second support walls272and273. Sliding wall271is free of holes, grooves, recesses, etc, providing a complete concave arcuate surface and enhancing the structural strength of second jaw24. Thus, jaw portion22can withstand high-torque operation. Furthermore, a center of a concave, arcuate face of the sliding wall271is located in wrenching space26such that sliding wall271can be easily and rapidly processed with a single cutter at low costs while assuring structural strength of jaw portion22. First and second support walls272and273are parallel to each other and have a spacing T27therebetween.

A circular through-hole274is extended through first and second support walls272and273and in communication with sliding groove27. Through-hole274is located adjacent to throat25and receives a cylindrical guide28in the form of a pin. Two ends of guide28are received in two ends of through-hole274in first and second support walls272and273to retain guide28in sliding groove27. Guide28has a diameter D28.

Slide30is slideably received in sliding groove27between an extended position and a retracted position and can drive workpiece90to rotate in a driving direction or slide along a perimeter of workpiece90in a reverse direction opposite to the driving direction without driving workpiece90. Slide30is substantially arcuate in cross section and includes a side having a convex, arcuate sliding face31slideably abutting sliding wall271of sliding groove27, allowing relative arcuate sliding movement between slide30and jaw portion22. Sliding face31is free of holes, grooves, recesses, etc, providing a complete convex, arcuate surface and enhancing the structural strength of slide30. Thus, slide30can withstand high-torque operation.

Sliding face31of slide30has a curvature the same as that of sliding wall271of sliding groove27to allow smooth sliding of sliding face31on sliding wall271. Furthermore, when slide30is subjected to reactive force from workpiece90, due to the same curvature of sliding wall271and sliding face31, the reactive force from the workpiece90can be transmitted to sliding wall271through a large area of sliding face31while avoiding wobbling of sliding30during rotation of workpiece90. Thus, the torque bearing capacity of slide30is increased when workpiece90is driven by body20.

The other side of slide30opposite to sliding face31is located outside of sliding groove27and includes first and second wrenching faces32and33. First and second wrenching faces32and33are adapted to drive workpiece90to rotate. First wrenching face32is at an angle of 120° to second wrenching face33. First wrenching face32is located on a front end of slide30, and second wrenching face33is located in a rear end of slide30. When slide30is in the extended position, first and second wrenching faces32and33correspond respectively to fourth and third force-receiving faces in the first rotating direction94A and93A of workpiece90. An evasive portion34is formed between first and second wrenching faces32and33and can receive third force-receiving face in the second rotating direction93B of workpiece90.

Slide30further includes a top face301and a bottom face302respectively at upper and lower sides thereof. First and second wrenching faces32and33extend between top and bottom faces301and302. Top and bottom faces301and302are parallel to each other and slideably abut with first and second support walls272and273of sliding groove27, respectively. Slide30has a height H30between top and bottom faces301and302in a height direction. Ignoring the tolerance, height H30of slide30is the same as spacing T27of sliding groove27. This allows top and bottom faces301and302of slide30to be symmetrically supported by first and second support walls272and273of sliding groove27, avoiding wobbling of slide30while sliding in sliding groove27along an arcuate path and increasing operational stability of open end wrench10.

Slide30further includes a guiding slot35extending from top face301through bottom face302. Guiding slot35is arcuate in cross section and has a curvature the same as the curvature of sliding wall271of sliding groove27. Since guiding slot35extends from top face301through bottom face302, a height H35of guiding slot35in the height direction of slide30is the same as height H30of slide30. Furthermore, guiding slot35has a width W35(between inner and outer arcuate surfaces thereof) in a width direction perpendicular to the height direction of slide30. Namely, width W35is equal to a difference between a radius of the outer arcuate surface and a radius of the inner arcuate surface of guiding slot35. Ignoring the tolerance, width W35of guiding slot35is the same as diameter D28of guide28. Height H35of guiding slot35is larger than 1.5 times width W35of guiding slot35(i.e., width W35of guiding slot35is smaller than 0.66 times height H35of guiding slot35). In this embodiment, height H35of guiding slot35is larger than two times width W35of guiding slot35(i.e., width W35of guiding slot35is smaller than 0.5 times height H35of guiding slot35).

Guiding slot35receives guide28to prevent slide30from disengaging from sliding groove27. Since the curvature of sliding face31of slide30is the same as those of guiding slot35and sliding wall271of sliding groove27, smooth sliding movement between guiding slot35of slide30and guide28in sliding groove27can be obtained while sliding face31of slide30is moving along sliding wall271of sliding groove27along the arcuate path. Undesired interference between slide30, guide28, and sliding wall271is avoided.

Guiding slot35further includes an abutting end351and a pressing end352. When slide30is in the extended position, abutting end351is in contact with guide28, and pressing end352is in contact with elastic device40. Since all of the surfaces of guiding slot35are free of holes, grooves, recesses, etc, stress concentration is avoided, and the structural strength of slide30is assured. Thus, slide30can withstand high-torque operation. Furthermore, since sliding face31and all of the surfaces of guiding slot35of slide30are free of holes, grooves, recesses, etc, the manufacturing costs of slide30can be reduced while providing open end wrench10with high-torque capacity and allowing open end wrench10to be produced at low costs for wider industrial application.

Elastic device40has two ends respectively abutting guide28and pressing end352of guiding slot35for returning slide30to the extended position. Elastic device40includes an elastic element41. After mounting, elastic element41is completely received in guiding slot35. Elastic element41has a height H40in the height direction of slide30. In this embodiment, height H40of elastic element41is not larger than height H35of guiding slot35and larger than width W35of guiding slot35. Furthermore, height H40of elastic element41is larger than 0.5 times height1135of guiding slot35. By providing such an elastic element41, elastic element41will not move away from its initial position in guiding slot35, reliably returning slide30to the extended position under the bias of elastic element41. In this embodiment, elastic element41is a resilient plate having a plurality of interconnected Z-shaped sections.

First wrenching face32includes a top extension face36extending away from top face301and a bottom extension face36extending away from bottom face302. Top and bottom extension faces36are coplanar to first wrenching face32. The front end of slide30includes two wings37respectively extending away from top and bottom faces301and302. Each wing37includes an inner face371and an outer face372. Top extension face36is located on inner face371of one of wings37, and bottom extension face36is located on inner face371of the other wing37. When slide30is in the extended position, first wrenching face32corresponds to fourth force-receiving face in the first rotating direction94A of workpiece90. Wings37of slide30can wrench fourth force-receiving face in the first rotating direction94A of workpiece90.

FIG. 5shows rotation of open end wrench10according to the preferred teachings of the present invention in the driving direction towards first jaw23(the clockwise direction inFIG. 5) to drive workpiece90. Slide30is in the extended position. A portion of outer face372of each wing37is in contact with second jaw24, such that the force imparted from workpiece90to wings37can be transmitted to second jaw24, increasing the torque for rotating workpiece90by open end wrench10and providing high-torque driving effect. Furthermore, slide30stably abuts fourth force-receiving face in the first rotating direction94A of workpiece90.

In the form shown, the curvature of outer face372of each wing37is the same as that of first face241, such that a portion of outer face372of each wing37is in surface contact with first face241of second jaw24, as shown inFIG. 5. High-torque driving effect is, thus, provided.

With reference toFIGS. 6-8, since not all of outer face372of each wing37is in contact with second jaw24, the contact area between outer face372of each wing37and second jaw24is gradually increased when open end wrench10moves in the reverse direction and causes movement of slide30to the retracted position away from abutting end351of guiding slot35, avoiding damage to elastic device40while open end wrench10moves rapidly in the reverse direction.

When rotation of open end wrench10in the reverse direction is finished, slide30can smoothly and rapidly moved to the extended position, because the two ends of elastic device40respectively presses against guide28and pressing end352of guiding slot35. The contact area between outer surface372of each wing37and first face241is gradually decreased while slide30is moving to the extended position under the bias of elastic device40for next driving operation, as shown inFIG. 9.

After workpiece90(such as the hexagonal head of a bolt) is screwed to a flat surface (FIG. 4), open end wrench10can be in contact with an overall height h2of workpiece90by first wrenching face32and top and bottom extension faces36, providing high-torque operation by increasing the contact area between workpiece90and slide32through provision of wings37while avoiding slide32from getting stuck. First wrenching face32of slide30contacts a portion h1of height h2of workpiece90.

With reference toFIG. 5, when a user intends to rotate workpiece90in the driving direction towards first jaw23(the clockwise direction inFIG. 5), workpiece90is firstly entered wrenching space26to a driving position with force-applying face231of first jaw23of jaw portion22abutting first force-receiving face in the first rotating direction91A of workpiece90and with first wrenching face32and top and bottom extension faces36of slide30abutting fourth force-receiving face in the first rotating direction94A of workpiece90.

Since fourth force-receiving face in the first rotating direction94A of workpiece90is parallel to first force-receiving face in the first rotating direction91A, to make first wrenching face32and top and bottom extension faces36of slide30be in surface contact with fourth force-receiving face in the first rotating direction94A, elastic element41in slide30is compressed and deformed to move slide30along the arcuate path such that first wrenching face32and top and bottom extension faces36of slide30can automatically abut fourth force-receiving face in the first rotating direction94A while first wrenching face32and top and bottom extension faces36of slide30are substantially parallel to force-applying face231of first jaw23.

In this case, the user can drive handle21in the clockwise direction to rotate jaw portion22about the center of workpiece90. The force applied by the user is transmitted through force-applying face231of first jaw23to first force-receiving face in the first rotating direction91A of workpiece90. At the same time, the force applied by the user is transmitted through first wrenching face32and top and bottom extension faces36of slide30to fourth force-receiving face in the first rotating direction94A of workpiece90. Thus, workpiece90rotates together with jaw portion22.

Since a portion of outer face372of each wing37is in contact with second jaw24when slide30is in the extended position, the force imparted from workpiece90to wings37can be transmitted to second jaw24, increasing the torque capacity of open end wrench90and providing high-torque driving effect while allowing slide30to stably abut against fourth force-receiving face in the first rotating direction94A of workpiece90.

Since first jaw23and jaw portion22are integrally formed as a single and inseparable component of the same material, force-applying face231of first jaw23can effectively withstand the reactive force from first force-receiving face in the first rotating direction91A of workpiece90. Furthermore, since second jaw24and jaw portion22are integrally formed as a single and inseparable component of the same material and since sliding face31of slide30and sliding wall271of sliding groove27are free of holes, grooves, recesses, etc and have the same curvature and are in surface contact with each other, sliding face31of slide30can contact with sliding wall271by a large area, avoiding wobbling of slide30in sliding groove27while driving workpiece90. Thus, open end wrench10according to the present invention can withstand high-torque operation.

In this embodiment, second wrenching face33of slide30abuts third force-receiving face in the first rotating direction93A of workpiece90. Since second jaw24and jaw portion22are integrally formed as a single and inseparable component of the same material and since sliding face31of slide30and sliding wall271of sliding groove27are free of holes, grooves, recesses, etc and have the same curvature and are in surface contact with each other, sliding face31of slide30can contact with sliding wall271by a large area, avoiding wobbling of slide30in sliding groove27while driving workpiece90. Thus, open end wrench10according to the present invention can withstand high-torque operation.

FIGS. 6-8show rotation of open end wrench10according to the present invention in the reverse, non-driving direction towards second jaw24without driving workpiece90. Namely, open end wrench10is moved in the reverse direction back to a position ready for driving workpiece90without the need of disengaging workpiece90from wrenching space26of jaw portion22and subsequent reengaging workpiece90in wrenching space26, allowing fast driving of workpiece90.

When the user moves handle21in the counterclockwise direction, jaw portion22and handle21rotate freely relative to workpiece90such that first and second evasive portions221and222of jaw portion22and evasive portion34of slide30respectively approach first, second, and third force-receiving faces in the second rotating direction91B,92B, and93B of workpiece90. Namely, first, second, and third force-receiving faces in the second rotating direction91B,92B, and93B of workpiece90enter first and second evasive portions221and222and evasive portion34.

Further rotation of jaw portion22in the counterclockwise direction causes evasive portion34of slide30to come into contact with third force-receiving face in the second rotating direction93B of workpiece90. In this case, elastic element41is compressed and moves slide30in sliding groove27along the arcuate path. Since not all of outer face372of each wing37is in surface contact with first face241, the contact area between outer face372of each wing37and first face241is gradually increased when open end wrench10moves in the reverse direction and causes movement of slide30to the retracted position, avoiding damage to elastic device40while open end wrench10moves rapidly in the reverse direction.

When slide30is pressed and moved along the arcuate path relative to jaw portion22, jaw portion22can continue its rotation in the counterclockwise direction. Next, force-applying face231of first jaw23moves across first force-receiving face in the second rotating direction91B of workpiece90and approaches second force-receiving face in the first rotating direction92A of workpiece90. At the same time, first wrenching face32of slide30moves across fourth force-receiving face in the second rotating direction94B of workpiece90and approaches fifth force-receiving face in the first rotating direction95A of workpiece90. In this embodiment, second wrenching face33of slide30also moves across third force-receiving face in the second rotating direction93B of workpiece90and approaches fourth force-receiving face in the first rotating direction94A of workpiece90.

With reference toFIG. 9, when rotation of open end wrench10in the reverse direction is finished, slide30can be smoothly and rapidly moved to the extended position, because the two ends of elastic device40respectively presses against guide28and pressing end352of guiding slot35. When force-applying face231of first jaw23abuts second force-receiving face in the first rotating direction92A of workpiece90, elastic element41returns slide30to the extended position and makes first wrenching face32of slide30abut fifth force-receiving face in the first rotating direction95A of workpiece90. Furthermore, first wrenching face32of slide30automatically comes in surface contact with fifth force-receiving face in the first rotating direction95A of workpiece90such that first wrenching face32of slide30is substantially parallel to force-applying face231of first jaw23, reliably positioning jaw portion22in the new driving position ready for driving workpiece90in the clockwise direction without the need of disengaging workpiece90from wrenching space26of jaw portion22and subsequent reengaging workpiece90in wrenching space26, allowing fast driving of workpiece90. The contact area between outer surface372of each wing37and first face241is gradually decreased while slide30is moving to the extended position under the bias of elastic device40for next driving operation. Thus, elastic device40rapidly moves slide30from the retracted position to the extended position.

Thus, open end wrench10is moved to the next driving position and is in a state similar to that shown inFIG. 5. The user can again rotate handle21in the clockwise direction to make jaw portion22rotate about the axis of workpiece90and, thus, drive workpiece90in the clockwise direction.

With reference toFIG. 3, when jaw portion22has not received workpiece90yet, abutting end351of guiding slot35is in contact with guide28, and slide30is in the extended position. First wrenching face32of slide32and top and bottom extension faces36extend into wrenching space26. First wrenching face32of slide30is not parallel to force-applying face231of first jaw23.

With reference toFIG. 5, when jaw portion22receives workpiece90but does not drive workpiece90, force-applying face231of first jaw23abuts first force-receiving face in the first rotating direction91A of workpiece90, and the front end of slide30abuts fourth force-receiving face in the first rotating direction94A of workpiece90. At the same time, a gap38exists between abutting end351of guiding slot35and guide28. Gap38is larger than the tolerance of workpiece90.

When workpiece90is rotated by jaw portion22and causes deformation of jaw portion22, body20slightly rotates relative to workpiece20. Gap38prevents slide30from rotating together with body20. Thus, the front end of slide30can still abut fourth force-receiving face in the first rotating direction94A of workpiece90while jaw portion22expands elastically.

With reference toFIG. 5, when jaw portion22receives the workpiece90but does not drive workpiece90, a buffering angle θ is formed between first wrenching face32of slide30and fourth force-receiving face in the first rotating direction94A of workpiece90. Buffering angle θ allows body20and slide30to gradually rotate relative to workpiece90when jaw portion22expands elastically, such that first wrenching face32of slide30abuts fourth force-receiving face in the first rotating direction94A of workpiece90, providing surface contact between first wrenching face32of slide30and fourth force-receiving face in the first rotating direction94A of the workpiece90. In this embodiment, the buffering angle θ is larger than 2°. Namely, the angle between first and second wrenching faces32and33of slide30is smaller than 118°.

First wrenching face32of slide30can include at least one groove39to increase the friction (i.e., the engagement force) between first wrenching face32of slide30and fourth force-receiving face in the first rotating direction94A of workpiece90.