[DESCRIPTION] lInvention Title) WRENCH WITH A SINGLE MOVABLE TEETH PORTION (Technical Field] The present invention relates to a wrench having a single movable tooth piece, and, more particularly, to a wrench, which has a movable tooth piece equipped to one of opposite jaws of the wrench, and an access preventing protrusion formed between the jaws, thereby allowing the wrench to tighten a bolt upon rotation in one direction while allowing the wrench to rotate without tightening the bolt upon rotation in the opposite direction.

[Background Art] The present invention relates to a wrench having a single movable tooth piece. More particularly, the present invention relates to a wrench, which has a movable tooth piece equipped to one of opposite jaws of the wrench, and an access preventing protrusion formed between the jaws, thereby allowing the wrench to tighten a bolt upon rotation in one direction while allowing the wrench to rotate without tightening the bolt upon rotation in the opposite direction. Accordingly, once the wrench is fitted onto the bolt, continuous operations can be performed without the wrench being disengaged from the bolt until the wrench completely tightens the bolt. Moreover, the access preventing protrusion is formed on a head of the wrench, so that the movable tooth piece can be prevented from being pushed into a recess guide of the wrench, thereby fundamentally preventing the wrench from rotating without tightening the nut.

According to the simplest construction of a wrench, which is a tool for

tightening or disengaging a bolt or nut, the wrench has jaws fixed to the wrench.

The wrench having the fixed jaws can be used in order to tighten a nut, in such a manner that the fixed jaws of the wrench are fitted onto the nut, followed by rotating the wrench, and the jaws are then released from the nut, followed by fitting the fixed jaws of the wrench onto the nut again at a new position of the nut, and these operations axe repeated until the nut is completely tightened.

However, with this construction of the wrench, there are problems in that, as the wrench is repeatedly fitted onto and released from the nut, the operations become cumbersome, and an operation time may be extensive.

In order to solve the problems, a ratchet wrench is designed for allowing the operation to be finished by performing fitting and release of the wrench on the nut only once. The ratchet wrench employs a principle of a ratchet, which restricts the rotation of the ratchet in one direction while allowing the rotation thereof in the opposite direction, and various kinds of wrenches have been designed according to an installation manner of the ratchet on the wrench.

For example, a widely used ratchet wrench is designed to allow for the rotation of the wrench in only one direction by attaching a closed-looped rotational tooth piece onto the ratchet. The ratchet wrench having the closed-looped rotational tooth piece is configured to allow the wrench to be fitted onto the nut through an opening defined in the rotational tooth piece. In this regard, in the case of tightening a nut installed around an intermediate portion of a pipe or a nut installed to a pipe having no cut portion in a working space by use of the ratchet wrench, since it is very difficult to fit the ratchet wench onto the nut, the wrench having the opened jaws fixed to the wrench is generally used. Accordingly, the ratchet wrench has a problem in that an application range of the wrench is limited.

As for an improved ratchet wrench, open-style ratchet wrenches are designed which allow the wrench to be fitted onto the nut in a lateral direction while having an advantage of the ratchet wrench, which removes the necessity of the repetitious release and fitting of the wrench.

One of the open-style ratchet wrenches is a wrench having two movable tooth pieces.

Fig. 14 is a partially cross-sectional view illustrating a conventional wrench having the two movable tooth pieces. As shown in Fig. 14, the wrench having the two movable tooth pieces generally comprises a head 80 having receiving grooves 82 formed through the head 80, and movable tooth pieces 83 received in the receiving grooves 82 such that the movable tooth pieces 83 can be elastically supported within the receiving grooves 82 by means of springs 84, respectively.

When the wrench having the two movable tooth pieces bites a nut 85 and is then rotated in the clockwise direction, the wrench tightens the nut 85 with each of the movable tooth pieces 83 latched and fixed to latch portions 81 of the movable tooth pieces 83. Then, when the wrench is rotated in the counterclockwise direction, each of the movable tooth pieces 83 is retracted into an inner portion of the corresponding receiving groove 82, allowing the wrench to be rotated without tightening the nut 85, and the operation for tightening the nut by rotating the wrench in the clockwise direction is performed.

However, since the two tooth pieces-mounted wrench has two movable tooth pieces 83, there are problems in that the wrench has a complicated construction, and manufacturing costs for the wrench is increased due to installation of the two movable tooth pieces 83 on the wrench.

Moreover, since both the two movable tooth pieces 83 are movable in the head 80, when a force is applied to the wrench in one direction with the wrench fitted onto the nut 85, one of the movable tooth pieces 83 is retracted into the receiving groove 82 thereof, and in this state, the other movable tooth piece does not bite an edge of the nut, causing a problem in that, when tightening the nut, the wrench does not bite the nut and rotates around the nut without tightening the nut.

Additionally, when both the two movable tooth pieces are withdrawn into the receiving grooves with the wrench fitted onto the nut, since it is possible for the wrench to bite the nut in case where the nut has dimensions larger than those of the

wrench, there is a problem in that whether or not the dimensions of the wrench are identical to those of the nut cannot be confirmed promptly.

Meanwhile, in the case where the nut has dimensions larger than those of the wrench, if the wrench is fitted onto the nut and then tightens the nut, each of the movable tooth pieces is fixed to one side of the receiving grooves by virtue of a frictional force caused by a force applied from the nut in a state that the movable tooth piece does not reach a latching jaw of the receiving groove, and in this state, if the wrench continues to tighten the nut, some portion of the receiving grooves are abraded to be deforrned or the jaws of the wrench can be broken away.

Moreover, since the nut is tightened by use of the two movable tooth pieces, the respective receiving grooves must be accurately positioned in symmetrical locations in the wrench in order that both the movable tooth pieces accurately bite the nut. Accordingly, the receiving grooves are accurately formed in the wrench, and if the locations of the receiving grooves are even minutely deviated from predetermined locations, bite between the movable tooth pieces and nut are loosened, and a load is locally applied to a tooth portion of the tooth piece, thereby causing wear and breakage of the tooth.

[Disclosure] [Technical Problernl Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a wrench designed to allow the wrench to continuously perform operations without being deviated from a nut upon tightening or releasing the nut, thereby allowing for easy and rapid operations by use of the wrench.

[Technical Solution]

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a wrench having a single movable tooth piece, comprising: a head including one jaw having a first plurality of teeth at one side of the head, another jaw having a guide recess with a latching portion at the other side of the head, and an opening defined between the jaws; a movable tooth piece positioned inside the guide recess while being supported by an elastic member inside the guide recess, such that the movable tooth piece can move along the guide recess, and having a second plurality of teeth formed at one side of the movable tooth piece; and a grip connected to the head, wherein the movable tooth piece is restricted in movement within a predetermined range in the guide recess by means of the latching portion, and the head has an access preventing protrusion protruded toward the opening defined between the jaw at one side of the head and the jaw at the other side of the head.

Advantageous Effects i In accordance with a wrench having a single movable tooth piece according to preferred embodiments of the present invention constructed as described above, since the movable tooth piece applies a force to a nut only upon rotation of the wrench in one direction in a state wherein an opening of a head is fitted onto the nut, operations can be continuously performed upon tightening or releasing the nut by use of the wrench without the wrench being deviated from the nut, thereby providing an advantageous effect of allowing for easy and rapid operations by use of the wrench.

The first and second teeth are formed on the head having a relatively steep right side and a gently sloped left side, thereby helping the wrench to smoothly rotate around the nut without tightening the nut.

Since it can be easily confirmed whether the wrench has a dimension identical to that of the nut by confirming whether or not the movable tooth piece is

latched to the guide recess after contacting the first teeth of the wrench with the nut in a state wherein the wrench according to the present invention is fitted onto the nut, the wrench can be prevented from being broken due to operations of the wrench on the nut having a dimension larger than that of the wrench.

The wrench according to the present invention has the first teeth fixed thereto, and thus, when the second teeth of the movable tooth piece bite an edge of the nut, there is provided an advantageous effect in that an optimal bite between the wrench and the nut can be easily established.

Since the wrench according to the present invention has the single movable tooth piece, it is not required to consider the symmetry of the guide recesses, which is an important factor when forming two guide recesses, thereby providing an advantageous effect of allowing for easy construction of the guide recess.

The wrench having the single movable tooth piece according to the present invention has a movable left jaw, and thus allows a distance between the jaws to be adjustable according to the dimension of the nut, thereby allowing the nuts having various dimensions to be tightened by use of one wrench.

Additionally, since the wrench having the single movable tooth piece according to the present invention has the guide recess formed at one side of the opening, and the movable tooth piece elastically supported in the groove, the wrench has a simple construction in comparison to the wrench having two movable tooth pieces, thereby proving an advantageous effect of minimizing manufacturing costs.

In the case where the access preventing protrusion is formed on the head of the wrench according to the present invention, the access preventing protrusion limits an accessing distance of the nut without adjusting a force for fitting the wrench onto the nut, and thus prevents the movable tooth from being pushed into the guide recess, so that the head of the wrench completely restricts the nut, thereby preventing the wrench from rotating around the nut without tightening the

nut.

According to the present invention, the wrench can be fitted onto the bolt in the transverse direction of the bolt as well as in the axial direction of the bolt, and can be easily fitted onto the nut, which is installed in an intermediate location of an elongated pipe.

[Description of Drawings] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a plan view illustrating the construction of a wrench having a single movable tooth piece according to a first preferred embodiment of the present invention; Fig. 2 is a partially perspective view illustrating a guide recess and a movable tooth piece of the wrench having the single movable tooth piece according to the first preferred embodiment of the present invention; Fig. 3 is a partially cross-sectional view illustrating the wrench having the single movable tooth piece according to the first preferred embodiment of the present invention when tightening a nut; Fig. 4 is a partially plan view illustrating a wrench having a single movable tooth piece according to a second preferred embodiment of the present invention; Fig. 5 is a partially cross-sectional view illustrating a head of the wrench having the single movable tooth piece according to the second preferred embodiment of the present invention in which the cross-section of the head is shown in the transverse direction; Fig. 6 is a partially plan view illustrating a wrench having a single movable tooth piece according to a third preferred embodiment of the present

invention; Fig. 7 is a perspective view illustrating a wrench having a single movable tooth piece according to a fourth preferred embodiment of the present invention ; Fig. 8 is an exploded perspective view illustrating the wrench having the single movable tooth piece according to the fourth preferred embodiment of the present invention, in which the movable tooth piece is separated from the wrench; Fig. 9 shows the movable tooth piece of the wrench in a state of being pushed into the guide recess of the wrench, which does not have an approach preventing protrusion formed therein; Fig. 10 is a front view illustrating the wrench having the single movable tooth piece according to the fourth embodiment of the present invention, in which the teeth of the wrench come into contact with the lateral sides of the nut; Fig. 11 is a front view illustrating the wrench having the single movable tooth piece according to the fourth embodiment of the present invention in a state of being rotated from the state shown in Fig. 10 in the counterclockwise direction; Fig. 12 is a front view illustrating the wrench having the single movable tooth piece according to the fourth embodiment of the present invention, in which the teeth of the wrench bite the nut ; Fig. 13 is a front view illustrating the wrench having the single movable tooth piece according to the fourth embodiment of the present invention in a state of being rotated from the state shown in Fig. 12 in the counterclockwise direction; and Fig. 14 is a partially cross-sectional view illustrating a conventional wrench having two movable tooth pieces.

[Best Model Construction of a wrench having a single movable tooth piece according to preferred embodiments of the present invention will now be described in detail with

reference to drawings. Like components will be denoted by like reference numerals throughout the drawings.

Fig. 1 is a plan view illustrating the construction of a wrench having a single movable tooth piece according to a first preferred embodiment of the present invention, and Fig. 2 is a partially perspective view illustrating a guide recess and a movable tooth piece of the wrench having the single movable tooth piece according to the first preferred embodiment of the present invention. As shown in Figs. 1 and 2, the wrench having the single movable tooth piece according to the present invention includes a bar-shaped grip 2 having fixed jaws formed at one side of the grip, a head 1 comprising the fixing jaws consisting of a left jaw 3 and a right jaw 10 which define an opening of the head 1 at one side of the grip 2 therebetween, and a movable tooth piece 20 located on one side of the right jaw 10.

The left jaw 3 has a first plurality of teeth 4 formed thereon. A guide recess 11 is formed through the right jaw 10 as a straight and rectangular path with a slope against the head 1 to guide the movable tooth piece 20 therethrough. The guide recess 11 has stepped latching portions 12 and 13 formed on one end of the recess. The movable tooth piece 20 has a second plurality of teeth 21 formed on one side of the movable tooth piece 20, and four perpendicular planes 25 adapted to contact the guide recess 11 of the rectangular path such that the movable tooth piece 20 can be slide inside the guide recess 11. The movable tooth piece 20 has latching jaws 26 formed on upper and lower surfaces of the movable tooth piece 20, respectively, such that the latching jaws 26 can be latched to the latching portions 12 and 13. The movable tooth piece 20 is attached to a spring 40 at the other side of the movable tooth piece 20 opposite to one side of the movable tooth piece 20 where the second plurality of teeth 21 are formed, and the spring 40 attached to the movable tooth piece 20 is supported by a support 15.

Fig. 3 is a partially cross-sectional view illustrating the wrench having the single movable tooth piece according to the first preferred embodiment of the invention, in which the wrench is fitted onto a nut. As shown in Fig. 3, each of the

first teeth 4 formed in the left jaw 3 of the wrench having the single movable tooth piece according to the invention has a relatively steep left surface 5 and a gently sloped right surface 6. Similarly, each of the second teeth 21 of the movable tooth piece 20 provided to the guide recess 11 of the right jaw 3 also has a relatively steep left surface 22 and a gently sloped right surface 23.

Fig. 4 is a partially plan view illustrating a wrench having a single movable tooth piece according to a second preferred embodiment of the invention, and Fig. 5 is a partially cross-sectional view illustrating a head of the wrench having the single movable tooth piece according to the second preferred embodiment of the invention.

As shown in Figs. 4 and 5, the wrench having the single movable tooth piece according to the second embodiment of the invention has the same construction as that of the wrench having the single movable tooth piece according to the first embodiment of the invention, except that a head 60 of the wrench has a left jaw 52, which is transversely movable from the head 60.

In order to allow the left jaw 52 of the head 60 to be transversely movable, the wrench having the single movable tooth piece according to the second preferred embodiment of the invention has the left jaw 52, which is provided at one side of the left jaw 52 with a plurality of teeth 53 having the same shape as that of the first teeth 4 of the wrench according to the first embodiment, and at a lower portion of the left jaw 53 with a sliding portion 54 extended transversely and coupled to a sliding guide 62 of the head 60. The sliding portion 54 comprises conveying teeth 55 on an upper surface of the sliding portion 54 for conveying the left jaw 52 from the head 60 in a state of being engaged with a conveying nut 66.

A right jaw 61 of the head 60 has the same shape as that of the right jaw 10 of the wrench according to the first embodiment of the invention. The sliding guide 62 is provided to the opposite side of the right jaw 61, and allows the left jaw 52 to be installed thereto. A conveying nut-holding groove 63 is formed below the sliding guide 62 such that the conveying nut 66 can be engaged with the conveying teeth 55 of the sliding portion 54 within the conveying nut-holding groove 63.

Fig. 6 is a partially plan view illustrating a wrench having a single movable tooth piece according to a third preferred embodiment of the present invention. As shown in Fig. 6, the wrench having the single movable tooth piece according to the third embodiment of the invention has the same construction as that of the wrench having the single movable tooth piece according to the first embodiment of the invention, except that a head 100 of the wrench is detachably coupled to a grip 120 by means of a fastening protrusion 110 of the head 100 and a fastening recess 130 of the grip 120.

Fig. 7 is a perspective view illustrating a wrench having a single movable tooth piece according to a fourth preferred embodiment of the invention, and Fig. 8 is an exploded perspective view illustrating the wrench having the single movable tooth piece according to the fourth preferred embodiment of the invention, in which the movable tooth piece is separated from the wrench. As shown in Figs. 7 and 8, the wrench having a single movable tooth piece 230 according to the fourth embodiment of the invention includes a head 200, which comprises a left jaw 210 having a first plurality of teeth 213 formed on the left jaw 210, and a right jaw 220 having a movable tooth piece installed to the right jaw 220. A guide recess 224 is formed through the right jaw 220 with a slope, and the movable tooth piece 230 having a second plurality of teeth 232 formed thereon is elastically supported inside the guide recess 224 such that the movable tooth piece 230 can be slidably moved through the guide recess 224. In order to allow the movable tooth piece 230 to be elastically supported inside the guide recess 224, a spring is disposed at a rear side of the movable tooth piece 230 inside the guide recess 224, and is then supported by a cover fixed to the head 220 by means of a fixing piece. The movable tooth piece 230 is formed with stepped jaws, so that the stepped jaws are latched to a latching portion 222, which is protruded from one end of an inner surface of the guide recess, 224, and thereby restricts the movement of the movable tooth piece 230.

The head 200 has an access preventing protrusion 205 protruded at an intermediate portion between the left jaw 210 and the right jaw 220 toward an

opening defined between the left jaw 210 and the right jaw 220. The access preventing protrusion 205 is located at the intermediate portion between the left jaw 210 and the right jaw 220 to prevent a nut or a bolt from accessing an inner surface of the head 200 beyond a predetermined range within the opening of the head 200.

A distance between the first teeth 213 formed in the left jaw 210 except the lowermost end of the left jaw 210 and the second teeth 232 formed in the right jaw 230 except the lowermost end of the right jaw 230 is similar to a distance between the opposite sides of the nut corresponding to the dimension of the wrench.

Operations of the wrench having the single movable tooth piece according to the preferred embodiments of the invention having the construction as described above will now be described hereinafter.

First, the operations of the wrench having the single movable tooth piece according to the first embodiment of the invention will be described.

When the wrench is rotated in the clockwise direction 39 with the opening of the head 1 fitted onto the nut 30, one of the first teeth 4 of the left jaw 3 has the left surface 5 contacting a right side 31 of one edge of a nut 30, and one of the second teeth 21 of the movable tooth piece 20 has the left surface 22 contacting a right side 32 of another edge of the nut 30. Then, as the right side 32 of another edge of the nut 30 pushes the left surface 22 of the second teeth 21 of the movable tooth piece 20 into the guide recess, the movable tooth piece 20 is latched to the latching portions 12 and 13 of the guide recess 1 1 located at the left side of the movable tooth piece 20, whereby the second teeth 21 of the movable tooth piece 20 applies a force to the nut due to a counter reaction of the latching portions 12 and 13, causing the nut 30 to be tightened.

Meanwhile, when the wrench is rotated in the counterclockwise direction without the wrench being separated from the nut, one of the second teeth 21 of the movable tooth piece 20 allows the right surface 23 adjacent to the left surface 22 to come into contact with a left side 33 of the edge of the nut 30. Then, as the nut 30 pushes the right surface 23 of the second teeth 21 into the guide recess, the right

surface 23 of one of the second teeth 21 is retracted into the guide recess 11 along with the movable tooth piece 20, and allow the nut 30 to move over one of the second teeth 21, whereby the wrench is freely rotated around the nut 30 without tightening the nut 30. At this time, since the first and second teeth 4 and 21 have the gently sloped right surfaces 6 and 23 and the steep left surfaces 5 and 22, the construction of the teeth 4 and 21 allows the nut to move over the teeth 4 and 21 in the clockwise direction, helping the wrench to be freely rotated around the nut 30 without tightening the nut 30.

In the wrench having the single movable tooth piece according to the first embodiment of the invention, since the first teeth 4 are fixedly formed on the head 1 and the second teeth 21 are movable together with the movable tooth piece 20 with respect to the head 1, it can be confirmed whether or not the dimensions of the wrench are identical to the dimensions of the nut 30 by confirming whether or not the movable tooth piece 20 contacts the latching portions 12 and 13 of the guide recess 11 after closely contacting the first teeth 4 to the nut 30 with the wrench fitted onto the nut 30. That is, if the movable tooth piece 20 contacts the latching portions 12 and 13 of the guide recess 11, the dimensions of the wrench are identical to those of the nut 30, whereas, if it does not contact them, the dimensions of the wrench are larger than that of the nut 30.

Since the wrench having the single movable tooth piece according to the first embodiment of the invention has the first teeth 4 fixed to the head 1, if the wrench is fitted onto the nut 30 such that the first teeth 4 closely contact one edge of one side of the nut 30 and restrict the edge of the nut 30, and the second teeth 21 of the movable tooth piece 20 engage with one edge of the other side of the nut 30, the wrench and the nut 30 are in an optimally engaged state for tightening the nut 30.

Accordingly, when fitting the wrench onto the nut, it is not required to shake the wrench in an attempt to allow the wrench to be in the optimally engaged state with the nut.

Since the wrench having the single movable tooth piece according to the

embodiments of the invention has one movable tooth piece 20, it is not necessary to symmetrically forming the guide recesses. That is, the position of the guide recess 11 can be relatively freely selected in comparison to the case where two guide recesses are formed in the head, thereby allowing for easy manufacturing process of the wrench.

In the wrench having the single movable tooth piece according to the second embodiments of the invention, since the left jaw 52 is movable in the head 60, and allows the distance between the left and right jaws to be adjusted according to the dimensions of the nut, all kinds of nuts having various dimensions can be tightened by one wrench.

Although the wrench having the single movable tooth piece according to the second embodiments of the invention employs the construction wherein the conveying teeth 55 and the conveying nut 66 are coupled for conveying the left jaw 52, the present invention is not limited to this construction. Accordingly, it is possible to employ the construction wherein a conveying bolt is engaged with the conveying teeth 55.

In the wrench having the single movable tooth piece according to the third embodiments of the invention, since the head 100 of the wrench is detachably mounted to the grip 120, the heads 100 of various dimensions can be utilized to tighten the nuts having various dimensions.

According to the preferred embodiments of the invention, the latching portions 12 and 13 for restricting the movable tooth piece 20 are formed to surround the movable tooth piece 20 in a C-shape in order to allow load to be sufficiently distributed upon tightening the nut 30. However, the present invention is not limited to this construction, and it is noted that various shapes of the latching portions can be suggested as long as sufficient strength of the latching portions can be maintained.

According to the preferred embodiments of the invention, the movable tooth piece 20 is elastically supported by means of a coil spring. However, the

present invention is not limited to this construction, and it is noted that various means, such as a plate spring, and the like, can be suggested as long as the movable tooth piece 20 can be elastically supported by the means.

Meanwhile, although the third embodiment of the invention has does not have construction for maintaining an engagement between the detachable head 100 and the grip 120, it is needless to say that the present invention comprises means for maintaining the engagement between the detachable head 100 and the grip 120.

The operations of the wrench having the single movable tooth piece according to the fourth embodiment of the invention will be described.

Fig. 9 shows a movable tooth piece of a wrench having a single movable tooth piece in a state of being pushed into a guide recess of the wrench, which does not have an approach preventing protrusion formed therein. Dotted lines indicate a nut and the movable tooth piece, before these are not pushed into the wrench and the recess, respectively. As shown in Fig. 9, when a force is applied to the wrench with a nut 150 fitted into the head 300, which is not formed with the approach preventing protrusion, the nut 150 continues to approach an inner surface of the head 200, and then a lateral side of the nut 150 pushes a second tooth 232 of the movable tooth piece 230 into the guide recess 324, whereby a distance between a first tooth 213 and the second tooth 232 is widened from dl to d2. At this time, even though the wrench is rotated in the clockwise direction, since an edge of the nut 150 moves over the second tooth 232, the nut 150 is not fixed in position in the head 300, and the wrench freely rotates around the nut 150 without tightening the nut 150.

As such, when the approach preventing protrusion is not formed in the head, the nut must be fitted into the head to a correct depth inside the head in order to prevent the wrench from rotating around the nut without tightening the nut.

Additionally, in the case where a force exceeding a predetermined level is applied to the wrench, the nut is excessively fitted into the head, and pushes the movable tooth piece inside the guide recess, causing the wrench to rotate around the nut without tightening the nut. Accordingly, it can be appreciate that the approach preventing

protrusion has an advantageous effect in the head of the wrench.

Fig. 10 is a front view illustrating the wrench having the single movable tooth piece according to the fourth embodiment of the present invention, in which the teeth of the wrench contact lateral sides of the nut. As shown in Fig. 10, as the nut 150 passes through the opening of the head along the lateral sides of the nut 150, the nut 150 can be fitted into the head 200 of the wrench. Then, an edge 156 of the nut 150 contacts an approach preventing protrusion 205, and the opposite sides 152 and 153 of the nut 150 come into contact with the first and second teeth 213 and 232, respectively. Since the nut 150 is latched into the approach preventing protrusion 205, and is then prevented from further approaching the inner surface of the head 300 when the nut 150 contacts the second tooth 232 of the movable tooth piece 230 or before the nut 150 contacts the second tooth 232, the movable tooth piece 230 is prevented from being pushed into the guide recess 224 any longer. In this state, when the wrench is rotated in the clockwise direction, a right side 153 of the nut 150 generates upward frictional force against the second tooth 232.

However, the movable tooth piece 230 is fixed in position in the head 200 in a state of being latched to the latching portion (not shown). Accordingly, the nut 150 can be integrally rotated together with the head 200 of the wrench by means of the second tooth 232 of the movable tooth piece 230 and the first tooth 213 of a left jaw 210, so that the nut 150 can be tightened.

Fig. 11 is a front view illustrating the wrench having the single movable tooth piece according to the fourth embodiment of the present invention in a state of being rotated from the state shown in Fig. 10 in the counterclockwise direction. As shown in Fig. 11, when the wrench is rotated from the state shown in Fig. 2 in the counterclockwise direction, the right side 153 of the nut 150 generates downward frictional force against the second tooth 232, and the movable tooth piece 230 is moved into the guide recess 224. Then, the right side 153 of the nut 150 pushes the second tooth 232 down, and the edge 157 of the nut 150 moves over an uppermost second tooth 232 of the movable tooth piece 230. Thus, the movable tooth piece

230 is pushed into the guide recess 224, and a distance between the teeth 213 and 214 is widened from d3 to d4, thereby allowing a lower end edge 158 of the left side of the nut 150 to climb over the first tooth 213. Accordingly, the head 200 of the wrench does not force the nut 150 to be fixed inside the head 200, and rotates around the nut 150 without tightening the nut 150.

Fig. 12 is a front view illustrating the wrench having the single movable tooth piece according to the fourth embodiment of the present invention, in which the teeth of the wrench bite the nut. The state of the wrench shown in Fig. 12 can be achieved when further rotating the wrench in the counterclockwise direction from the state of the wrench shown in Fig. 11. As shown in Fig. 12, with the edges 157 and 158 fitted and restricted into the first teeth 213 and the second teeth 232, respectively, even though a slight distance is generated between the approach preventing protrusion 205 and a lower side 254 of the nut 150, this distance is small enough to be ignored. Thus, even though the wrench is forced in a direction of the nut, a distance in which the movable tooth piece 230 can be pushed into the guide recess 224 is also small enough to be ignored. Accordingly, the opposite edges 157 and 158 of the nut 150 are still restricted by the first teeth 213 and the second teeth 232, respectively. In this state, when the wrench is rotated in the clockwise direction, the right side edge 157 of the nut 150 restricted between the second teeth 232 applies a force to the second teeth 232 upwardly. However, the movable tooth piece 230 having the second teeth 232 formed thereon is latched to the latching portion (not shown), and fixed in position in the head 200. Accordingly, as the distance between the first teeth 232 and the second teeth 213 is maintained, the edges 157 and 158 of the nut 150 are not released from the first teeth 213 and the second teeth 232, and integrally rotated together with the head 200.

Fig. 13 is a front view illustrating the wrench having the single movable tooth piece according to the fourth embodiment of the present invention in a state of being rotated from the state shown in Fig. 12 in the counterclockwise direction. As shown in Fig. 13, with the edges 157 and 158 of the nut 150 fitted and restricted into

the first teeth 213 and the second teeth 232, respectively, when the wrench is rotated in the counterclockwise direction, one of the second teeth 232 is downwardly forced by the right side edge 157. Additionally, the movable tooth piece 230 having the second teeth 232 formed thereon is pushed into the guide recess 224, and the distance between the first teeth 232 and the second teeth 213 is increased. Then, the left side edge 158 of the nut 150 restricted between the first teeth 213 moves over one of the first teeth 213, and the right side edge 157 of the nut 150 restricted between the second teeth 232 moves over one of the second teeth 232 while pushing the movable tooth piece 230. Accordingly, the head 200 of the wrench does not restrict the nut 150, and rotates around the nut without tightening the nut.

As with the fourth embodiment of the present invention, when the approach preventing protrusion is formed on the head of the wrench, it restricts an approaching distance of the nut without controlling a force of fitting the wrench onto the nut, and prevents the movable tooth piece from being pushed into the guide recess, so that the head of the wrench can completely restrict the nut, thereby preventing the wrench from rotating around the nut without tightening the nut.

The approach preventing protrusion 205 formed on the head 200 of the wrench according to the fourth embodiment of the invention is located at the center between both jaws 210 and 220. When the nut (or the bolt) within the head 200 approaches inside the head 200, the lateral sides 152 and 153 of the nut 150 pass through the opening defined between the jaws 210 and 220, and thus the edge 156 of the nut 150 precedes into the head 200. Accordingly, the approach preventing protrusion 205 must be formed at the center between the jaws 210 and 220 in order to minimize the height of the approach preventing protrusion 205 corresponding to an approaching depth of the nut 150, and to allow the approaching depth of the nut 150 to be easily calculated. It is particularly important to minimize the height of the approach preventing protrusion 205 since interference between the nut 150 and the approach preventing protrusion 205 can be prevented upon rotation of the nut 150 by minimizing the height of the approach preventing protrusion 205.

When the force is applied to the wrench during operation, the approach preventing protrusion 205 prevents the movable tooth piece 230 from being pushed into the guide recess 224, so that the wrench is prevented from being freely rotated without tightening the nut.

Furthermore, the approach preventing protrusion 205 of the head 200 may is a protrusion having a narrow upper end. Meanwhile, in order to allow the wrench to be rotated without tightening the nut in a state wherein the lower side of the nut contacts the approach preventing protrusion 205 of the wrench, the nut 150 pushes down the movable tooth piece 230 while rotating within the head of the wrench. With regard to this, as shown in Fig. 13, the approach preventing protrusion 205 is formed on the head 200 of the wrench, so that an allowance space is formed within the head 200 to allow the edge of the nut 150 to be lowered below an end of the approach preventing protrusion 205 with reference to the head 200 when the nut 150 is rotated. Unless the allowance space for allowing the edge of the nut 150 to be lowered is not formed within the head 200, the nut is spaced apart from the head 200, and in this case, the nut can be easily released from the head 200.

According to the present invention, the distance between some of the first teeth 210 formed on the left jaw 210 and some of the second teeth 232 formed on the movable tooth piece 230 of the right jaw 220 is substantially identical to the distance between the opposite sides of the nut 150. This is attributed to the fact that the first teeth 210 and the second teeth 232 can restrict the lateral sides of the nut 150 as well as the edge of the nut 150, so that a torque can be applied to the nut through all portions of the nut, thereby allowing the operations of the wrench to be more rapid.

While the opening of the head 200 is fitted onto the hexagonal nut 150, one of the edges of the nut 150 contacts the approach preventing protrusion 205 before or at the same time the nut 150 contacts at least one of the second teeth 232 of the movable tooth piece 230, thereby preventing the head from further being fitted onto the nut 150. Accordingly, the approach preventing protrusion 205 is protruded to

have a predetermined height such that the movable tooth piece 230 is prevented from being pushed into the guide recess 224.

According to the invention, a latching portion 222 of the guide recess 224 of the wrench has a step-shaped protrusion formed on one end of an inner surface of the guide recess 224 such that the movable tooth piece 230 sliding on the inner surface of the guide recess 224 is latched to the step-shape protrusion. However, the present invention is not limited to this construction. Alternatively, the guide recess 224 may have a restricting groove having a predetermined dimension depressed at a predetermined position of the inner surface of the guide recess 224, and the movable tooth piece 230 may be formed with a latching protrusion, which can be inserted into the restricting groove, such that the movable tooth piece 230 cannot slide over the predetermined position of the inner surface of the guide recess 224.

In the wrench having the single movable tooth piece 230 according to the fourth embodiment of the invention, the left jaw of the wrench is not formed with the guide recess 224 and is not provided as a movable jaw. However, without being restricted to this construction, as with the second embodiment of the invention having the movable jaw, the wrench having the single movable tooth piece 230 according to the fourth embodiment may have a movable left jaw having the first teeth formed thereon.

Additionally, in the wrench having the single movable tooth piece 230 according to the fourth embodiment of the invention, the head 200 is integrated with the grip. However, the present invention is not limited to this construction, and, as with the fourth embodiment of the invention, the head may be detachably coupled to the grip.

[Industrial Applicability] The present invention is related to the wrench having the single movable

tooth piece, and can also be applied to a wrench for tightening the bolt upon rotation in one direction.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.