Abstract:
A ratchet wrench ( 1 ) with a single-piece jaw ( 3 ) having two positions for driving a hexagonal head ( 4 ), in particular of a screw or a nut. In each driving position, two opposite surfaces of the head ( 41,42 ) are driven by respective protuberances (P 2,  P 7 ) of the two grips of the jaw, and a supplementary protuberance (P 5 ) is urged in localized support in the front half of an intermediate surface ( 43 ) of the head located immediately in front of the rear surface. Thus, the inner profile of the jaw has six main protuberances, with an angular offset of 24 to 28° between two groups of three protuberances.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a ratchet-type wrench for driving a component, particularly a screw or a nut, the head of which has a hexagonal drive profile. 
     Patent Application PCT/FR 96/00 963, in the name of the Applicant Company, describes a ratchet-type wrench, which is particular easy and stable to use and which drives a hexagonal head with good protection. 
     However, in this known ratchet-type wrench, the backing-off movement of the ratchet between two driving positions extends angularly over 60°, whereas certain working environments do not offer enough empty space for movement of such an amplitude. 
     Ratchet-type wrenches with a backing-off movement on the order of 30° have been proposed in U.S. Pat. No. 4,889,020, but with serious drawbacks. Specifically, if the wrench is a one-piece wrench, the user has to shift the wrench radially with respect to the head in order to reach the second driving position, which is something that is difficult to achieve. Such shifting can be avoided only at the cost of adding an elastically loaded sliding finger. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a ratchet-type wrench with one-piece pair of jaws that are capable of ratcheting with a backing-off movement on the order of 30° while constantly being pushed toward the axis of the hexagonal head. 
     To this end, the subject of the present invention is a ratchet-type wrench of the aforementioned type. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the present invention will now be described with reference to the appended drawings, in which: 
     FIG. 1 is a partial view of a ratchet-type wrench constructed in accordance with the invention; 
     FIG. 2 depicts a portion of the interior profile of a pair of jaws of the wrench shown in FIG. 1, on an enlarged scale; 
     FIG. 3 depicts the ratchet-type wrench, engaged with a hexagonal nut, in a first driving position; 
     FIGS. 4 to  7  depict five successive phases of a backing-off movement of the wrench from a first driving position to a second driving position. 
     FIGS. 8 to  12  depict five successive phases of the backing-off movement of the wrench from the second driving position to the first driving position; 
     FIG. 13 depicts an alternative form of the ratchet-type wrench, in plan view; 
     FIG. 14 depicts a plan view of another alternative form of the ratchet-type wrench; 
     FIG. 15 is a side view taken in the direction of arrow XV of FIG. 14; and 
     FIG. 16 is a partial sectional view taken on the line XVI—XVI of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The ratchet-type wrench  1  depicted in FIG. 1 is a one-piece steel component having a flat overall shape. The wrench comprises a handle  2  of elongate shape, of overall axis X-X, which widens at its distal end to form a driving pair of jaws  3 . At its other end, the handle  2  may form another driving head, either similar to the pair of jaws  3  but of a different size, or of any other known type, particularly of the open-ended or ring wrench type, indicated by reference numeral  103  as shown in FIG.  13 . 
     The pair of jaws  3  is intended to drive a hexagonal head  4 , shown in FIGS. 3 to  12 , which is assumed to be a nut, in the clockwise direction F. In what follows, the terms “front” and “rear”, “advance” and “back-off” refer to this direction of driving. 
     The pair of jaws  3  may be considered as made up of three regions: a front jaw  5 , a rear jaw  6 , and an intermediate bow  7  which connects these two jaws. The interior profile of these three regions will be described below. 
     The front jaw  5  comprises two protrusions, namely a front protrusion P 1  and a rear protrusion P 2 , separated by a recess E 1 . 
     The rear jaw  6  comprises two protrusions, namely a front protrusion P 6  and a rear protrusion P 7 , separated by a recess E 6 . 
     The intermediate bow  7  comprises three protrusions, namely a front protrusion P 3 , an intermediate protrusion P 4  and a rear protrusion P 5 . A recess E 2  separates the protrusion P 2  from the protrusion P 3 , and likewise a recess E 3  separates the protrusion P 3  from the protrusion P 4  and a recess E 4  separates the protrusion P 4  from the protrusion P 5 . 
     Thus, the pair of jaws  3  has, from front to rear, seven successive protrusions P 1  to P 7 , separated by six successive recesses El to E 6 . In this example, the term “protrusion” should be understood as meaning a part which is convex in profile, and the term “recess” should be understood as meaning a concave part. 
     Going into greater detail, from front to rear: 
     Protrusion P 1  consists successively of two rounded portions  8  and  9  of similar radii, connected by a rounded portion  10  of a far larger radius; 
     Recess E 1  is formed of a simple rounded portion  11  of small radius; 
     Protrusion P 2  has a substantially triangular overall shape, with two flanks, a front flank  12  of large radius and a rear flank  13  which is substantially straight, connected by a rounded portion  14  of small radius; 
     Recess E 2  consists of a simple rounded portion  15 ; 
     Protrusion P 3  consists of a rounded portion  16  of small radius connected directly to the recess E 2 , and a substantially straight rear flank  17 ; 
     Recess E 3  consists of two rounded portions  18  and  19  connected by a bottom  20  of large radius; 
     Protrusion P 4  has a substantially triangular overall shape with two flanks—front  21  and rear  22 —which are substantially straight and connected by a rounded portion  23  of small radius; 
     Recess E 4  is a simple rounded portion  24 ; 
     Protrusion P 5  consists of a substantially straight front flank  25  followed by a rounded portion  26 ; 
     Recess E 5  is a simple rounded portion  27 ; 
     Protrusion P 6  consists of a rounded portion  28  followed by a substantially straight segment  29 ; 
     Recess E 6  is a simple rounded portion  30 ; and 
     Protrusion P 7  consists of a rounded portion  31  followed by a substantially straight segment  32  then by a rounded portion  33 . 
     All of the portions  8  to  33  of the profile meet at a tangent to one another, with the exception of the connections between  29  and  30  and between  32  and  33  which require additional small-radius blend radii. 
     The regions P 4  to P 7  of the profile are depicted on an enlarged scale in FIG.  2 . 
     The middles of the rounded portions  23 ,  26 ,  28  and  31  of the protrusions P 4  to P 7  are denoted A 4  to A 7  respectively, and these four points are substantially the points of contact of the four protrusions with the faces of the nut during the driving phases which will be described later. In addition, the maximum depths of the recesses E 4  to E 6 , measured at right angles to the segments P 4 -P 5 , P 5 -P 6  and P 6 -P 7 , are denoted p 4  to p 6  respectively, and the lengths of these three segments are denoted  14 ,  15  and  16 . This then gives the following dimensional relationships: 
     
       
         0.27 14≦ p 4≦0.40 14 
       
     
     
       
         0.25 15≦ p 5≦0.33 15 
       
     
     
       
         0.30 16≦ p 6≦0.40 16 
       
     
     In the illustrated example, the pair of jaws  3  is in the overall shape of a fork which is open at the front. As an alternative, as illustrated in FIG. 13, it could be completed by a stiffening front bow  34 , so as to form a ring. In this case, and as shown in the dotted line, the bow  34  may have a break  134  intended to permit the passage of a shank or a tube connected to the nut  4 . The bow  34  does not come into contact with the nut in the driving positions of the wrench which are described later, nor during the backing-off movements of the wrench when the wrench is pushed toward the nut along the axis X-X of its handle. 
     The way in which the wrench works will now be described with reference to FIGS. 3 to  12 . The example is given for a wrench of a minimum size and a nut of a maximum size, taking manufacturing tolerances into account, that is to say, the most unfavorable case for correct achievement of the backing-off movements. It should be noted that the difficulty lies in simultaneously obtaining good conditions for driving nuts of the minimum size and backing-off or ratchet movements without jamming on nuts of the maximum size. It should be understood that, as far as the nuts are concerned, the expressions “minimum size” and “maximum size” are understood within the context of the standardization of nuts. In all of FIGS. 3 to  12 , the nut  4  is depicted in the same position. 
     FIG. 3 depicts the wrench in its first driving position. According to the teaching of the aforementioned PCT/FR application, for zero torque and for any driving torque, that is to say applied in the clockwise direction F, the pair of jaws  3  is in contact with the nut  4  at just three points: two driving points consisting of a point A 2  of the protrusion P 2  and the point A 7 , and an additional bearing point consisting of the point A 5 . The point A 2  lies in the front or forward half of the front face  41 , and the point A 7  lies in the front or forward half of the diametrically opposite rear face  42 , while the point A 5  lies in the front or forward half of the face  43  located immediately ahead of the face  42 . 
     In the first driving position, if d 1 . 1 , d 2 . 1  and d 3 . 1  are used to denote the distances from each point of contact A 2 , A 7 , A 5  to the front corner of the corresponding face, and if L is used to denote the length of one side of the nut, then this gives the following relationships: 
     
       
           d 2.1&gt; d 1.1; 
       
     
     
       
           d 3.1&gt; d 1.1; 
       
     
     
       
           d 3.1&gt; d 2.1; 
       
     
     and 
     
       
         0.25 L≦d 3.1≦0.29 L.   
       
     
     When the driving travel has been completed, the operator executes a movement of backing-off the wrench, that is to say of moving the wrench in the counterclockwise direction F 1 , as illustrated in FIGS. 4 to  7 , in which the contacts mentioned serve to guide the wrench over the nut. It is assumed that a light force is constantly applied to the wrench along the axis X-X of the handle  2  toward the nut (f in FIG.  4 ). 
     As shown in FIG.  4 : the rear flank  17  of the protrusion P 3  comes into contact with the face  41  near to its rear corner  44 ; rear flank  22  of the protrusion P 4  comes into contact with the rear corner  45  of the face  49  that lies between the faces  41  and  43 ; and the protrusion P 6  comes into contact with the rear region of the face  43 . 
     As shown in FIG.  5 : the protrusion P 1  comes into contact with the front part of the face  41 , near to its front corner  46 , and the straight-line segment  29  of the protrusion P 6  presses against the face  43  near rear corner  47 . 
     As shown in FIG.  6 : the illustrated configuration is similar to that of FIG. 5, but the corner  47  moves past the vertex of the protrusion P 6 . 
     As shown in FIG.  7 : the corner  47  enters the recess E 5 , and there are once more three points of contact P 1 - 41 , P 4 - 43  and P 6 - 42 , the three points of contact taking place in the front half of the faces in question. This is the second driving position, similar to that of FIG. 1 but angularly offset by 26° in the counterclockwise direction F 1  with respect to the axis of the nut. 
     In this position, if d1.2, d2.2 and d3.2 are used to denote the distances from each point of contact to the front corner of the corresponding face, then the following relationships are obtained: 
     
       
           d 2.2&gt; d 1.2; 
       
     
     
       
           d 3.2&gt; d 1.2; 
       
     
     
       
           d 3.2&gt; d 2.2; 
       
     
     and 
     
       
         0.11 L≦d 3.2≦0.17 L.   
       
     
     In this position of FIG. 7, torque can once again be applied in the direction F. The operator then once more backs-off the wrench, as illustrated in FIGS. 8 to  12 : 
     As shown in FIG.  8 : there are just two guiding contacts, namely that of the rear flank  13  of the protrusion P 2  on the rear corner  44  of the face  41 , and that of the protrusion P 5  on the rear part of the face  43 . 
     As shown in FIG.  9 : there are just two guiding contacts, namely that of the front face  28  of the protrusion P 5  on the front corner  51  of the face  42  and that of the front flank  12  of the protrusion P 2  on the front corner  48  of the face  49  of the nut, which face lies between the faces  41  and  42 . 
     As shown in FIG.  10 : there are just two guiding contacts, namely that of the front flank  12  of the protrusion P 2  on the front region of the face  49 , and that of the protrusion P 7  on the rear corner  50  of the face  42 . 
     As shown in FIG.  11 : in a similar configuration to the configuration of FIG. 10, the protrusion P 7  pivots about the corner  50 . 
     As shown in FIG.  12 : the protrusion P 7 , having passed the corner  50 , comes to bear against the front part of the face  52  which lies immediately to the rear of the face  42 , and the protrusion P 5  comes to bear on the front part of this face  42 . The contact between P 2  and  49  is maintained. 
     This is then a return to a position that is identical to that of FIG. 3, that is to say to the first driving position, but with a backward angular offset of 60° compared with the position of FIG.  3 . 
     The second backing-off of the wrench, from the second driving position (FIG. 7) to the first driving position (FIG. 12) has the angular amplitude of 60−26=34°. 
     By virtue of the configuration of the protrusions and of the recesses as described above, the corners of the nut are not in contact with the wrench during the driving phases, and no jamming occurs during the backing-off or ratchet phases. 
     It should be noted that, for certain ratios of jaw and nut size, the protrusion P 3  does not play any part during the backing-off movements, depending on the manufacturing tolerances. By contrast, all the other guide surfaces of the protrusions P 1 , P 2  and P 4  to P 7  are always used at least once during at least one of the backing-off movements. More specifically, when backing-off from the first position to the second position the wrench is guided by the protrusions used for driving in the second position, and likewise, when backing-off from the second position to the first position, the wrench is guided by the protrusions used for driving in the first position. 
     The alternative form of the present invention, as shown in FIGS. 14 to  16 , differs from the form of FIG. 13 in the following respects. 
     On the one hand, the front bow  34 , broken at  134 , is reinforced by a web  53 , which is an annular internal collar adjacent to one face of the pair of jaws and contains a break like the bow  34 , as is known per se. 
     Furthermore, as shown in FIG. 15, the handle is doubly cranked. One end of the handle has an oblique section  54  which extends as far as the web  53 , and at the other end the handle has an oblique section  55 , which is substantially parallel to the section  54  and diverges from the overall plane P of the handle in the opposite direction. 
     Finally, the second driving head  103 A is parallel to the plane P, as is the pair of jaws  3 , and is identical to the pair of jaws  3  of FIG. 13, with the bow  34  being continuous. 
     The orientation of the protrusions of the head  103 A is such that the head drives in the counterclockwise direction and ratchets in the clockwise direction, in the position of FIG. 15 in which it is pressed flat against a surface  56 , with the cranked portion  55  avoiding any obstacles  57  that may be projecting from this surface. Once the wrench has been turned over with respect to the plane P, the pair of jaws  3 , on the other hand, is capable of driving in the clockwise direction and ratchets in the counterclockwise direction, as described above.