Pliers with protected compulsory guide

The invention relates to pliers with a variable sized wrench, in particular to a water pump pliers with a first and a second gripper arms pivotably connected around a pivot pin. The first gripper arm is provided with an integrated pliers jaw. A pliers jaw movable about a joint is provided at the second gripper arm. The movable pliers jaw of the second gripper arm is provided with guiding means for adjustably guiding the movable pliers jaw together with the second gripper arm in a compulsory guide of the first gripper arm. A detent mechanism for locking is provided for keeping the movable pliers jaw with the second gripper arm in a detent position for a rough adjustment.

FIELD OF THE INVENTION

The invention relates to pliers with a variable sized wrench, in particular to water pump pliers with a first and a second gripper arm pivotably connected around a pivot pin.

BACKGROUND OF THE INVENTION

Pliers are a two-legged tool where the effective spots are pressed against each other. Basically, pliers consist of three components, i.e. the handles, the joint and they pliers head. They operate according to the lever principle. Two two-sided levers are interconnected by a joint. Usually the handles form the longer lever arms; the shorter lever arms form the pliers head. The manual power affected on the handles is amplified according to the law of the lever and transferred to the work piece by means of the pliers head.

Pliers related to by the present invention are used in various applications and especially used in the form of water pump pliers. Water pump pliers are gripping pliers, with an adjustable sliding joint, so that opening widths of the opening can be adjusted in various sizes. They are mainly used for gripping pipes, bushings and screws/nuts of different kinds, but also for flats etc.

Key pliers are known from the European Patent specification EP 0 421 107. Key pliers with two pliers jaws forming the pliers opening are described in this publication. One of the pliers jaws tightly abuts a pliers arm which is provided with a longitudinal slot guiding for a pliers leg pivot pin to roughly adjust the pliers opening. A fork-shaped, movable jaw for encompassing the fixed pliers leg is shiftably guided in a guiding groove at the pliers leg carrying the fixed pliers jaw. A power transmission spot between a shoulder of the shiftable pliers jaw and the jaw-side arm of the movable pliers leg is adapted to be displaced to close the pliers opening. The power transmission spot in the form of a form-fit engagement between the jaw-side arm and the movable pliers jaw is the interconnecting spot for the rough longitudinal adjustment as well as for the closing of the pliers opening between the pliers leg and the movable jaw.

The US patent specification U.S. Pat. No. 3,534,641 discloses a pliers consisting of two gripper arms. A first pliers jaw is integrated in a first gripper arm. A second pliers jaw is shiftably arranged on one side of the first gripper arm. For this purpose the first gripper arm is provided with a section with an abutment surface perpendicular to the pivot axis of the pliers. The second pliers jaw is designed to encompass the abutment surface of the first gripper arm with a groove-shaped abutment surface. Furthermore, a detent slot is provided in the first gripper arm wherein a pivot pin in the form of a screw is provided, the pivot pin having a detent mechanism. The second gripper arm engages the second movable pliers jaw at this pivot pin for the power transmission. While the second gripper arm is arranged on the one side of the first gripper arm the second pliers jaw is correspondingly provided on the opposite side of the first gripper arm. The second gripper arm can be adjusted with the second pliers jaw in the detent slot for rough adjustment. By activating the pliers the second pliers jaw is shifted along the section for power transmission according to the lever path.

The known pliers have the disadvantage, that they have many spots, where a user can pinch himself during gripping, for example at the rough adjustment of the pliers.

SUMMARY OF THE INVENTION

One of the objects of the invention is to improve known pliers and prevent injuries of the user.

According to the invention this object is achieved by providing pliers with variable opening size, especially water pump pliers, with a first and a second gripper arm interconnected pivotably about a pivot pin of the above mentioned kind, the compulsory guide for the movable pliers jaw is formed by:two plane abutment surfaces parallel with respect to the pivot axis of the pliers and sideways opposite positioned at the first gripper arm,a corresponding plane abutment surface at the movable pliers jaw,a corresponding opposite plane abutment surface at a guiding lug integrated in the movable pliers jaw, anda longitudinal slot through the first gripper arm to guide the second gripper arm.

The invention is based on the principle to design a compulsory guide in such a way that the guiding of the movable pliers jaw is mainly protected. This is particularly achieved in that the second pliers jaw and the movable pliers jaw are guided in a longitudinal slot protecting the user to a large extent of clamping injuries. The longitudinal slot covers the portions of the pliers, where a user can be injured as much as possible especially during adjustment of the pliers. Furthermore, the compulsory guide is shifted to areas, which do not contact the user during adjustment or when the pliers are operated.

It has been proven to be an advantageous modification of the invention if the pivot pin of the pliers according to the invention is guided in a slot parallel to the compulsory guide. By this measure an additional stability of the pliers is achieved by an even distribution of the power.

According to a preferred modification of the pliers according to the invention the detent mechanism is formed by the slot parallel to the compulsory guide and by at least one detent tooth provided at the pivot pin. In order to roughly adjust the pliers the pliers is roughly adjusted to a suitable opening width. The adjustment is carried out by shifting the pivot pin in the slot parallel to the compulsory guide. The detent tooth supports the pivot pin to be fixed in a position, for example by wedging. Preferably the slot parallel to the compulsory guide is provided with a toothing for detent of the detent tooth stabilizing the detent mechanism.

Furthermore the pliers according to the present invention are advantageously designed in that the detent mechanism is provided on two opposite sides of the longitudinal slot. By this measure it is additionally achieved that the power is not distributed on one side of the longitudinal slot, but symmetrically on both opposite sides, of the longitudinal slot. In a one-side detent mechanism the power is transmitted to one side of the longitudinal slot, which can lead to deformations at strong strain due to the asymmetry. With the symmetrical arrangement an even strain of the pliers is affected leading to an increased life time of the pliers.

Furthermore, according to an advantageous modification of the invention the detent mechanism is biased with a spring. Thereby the detent mechanism cannot be easily released from its position. In order to adjust the pliers for the rough adjustment it is, therefore, always necessary to unlock the detent mechanism against the spring power. The user of the tool cannot be injured as easily as before, when the detent mechanism is accidentally released during operation, whereby pinching or slipping-off of the pliers can occur.

It is, furthermore, advantageous with the pliers according to the present invention, if the joint between the second gripper arm and the second movable pliers jaw is formed by an integrated shoulder-shaped projection an end of the second gripper arm engaging a suitable recess of the second pliers jaw for the transmission of power. By this measure a joint is achieved, which is easy to produce and which satisfies the requirements for the power transmission.

A preferred variation of the pliers according to the present invention finally results, if the joint between the second gripper arm and the second movable pliers jaw is covered by protective means towards the outside. By a protective coat, for example, it is not only avoided that dirt enters the joint, but also that a region is protected where a user of the pliers could pinch himself.

The advantageous features of the invention are illustrated in the accompanying drawings.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

InFIG. 1a side view of pliers10according to the present invention is illustrated. The pliers10are provided with a first gripper arm12and a second gripper arm14. Each gripper arm12and14is provided with a handle20,22at a gripping end16,18. At the end24remote from the gripping handle of the first gripper arm12a first pliers jaw26is tightly integrated. The second gripper arm14is pivotably connected about a pivot pin28to the first gripper arm12. A pivot axis29is defined by the pivot pin28, seeFIG. 3.

A second pliers jaw30is shiftably guided in a section32of the first gripper arm12. The second gripper arm14and the second pliers jaw30are movably interconnected by a joint34. The joint34consists of a recess36and a shoulder-shaped projection40integrated into the end38remote from the gripper handle of the second gripper arm14, as it becomes obvious fromFIG. 2.

In a section32the first gripper arm12is provided with a longitudinal slot42which is perpendicular to the pivot axis29. The second gripper arm14and a guiding lug44integrated into the second pliers jaw30are guided through this longitudinal slot42.

The first gripper arm12is, furthermore, provided with a detent mechanism46. The detent mechanism46is formed by the pivot pin28and two detent slots48,50. The two detent slots48,50are positioned on opposite sides52,54of the longitudinal slot42. The detent slots48,50are provided with teeth56,58engaging a detent tooth assembly60for detent. The detent toot assembly60is spring biased provided at the pivot pin28. In order to effect a rough adjustment of the pliers10the detent tooth assembly60is removed from the teeth56,58against the spring power with a suitably provided pressure knob59. The pivot pin28may then be shifted with the second gripper arm14and the second movable pliers jaw30within the detent slots48,50. Due to the biasing power of the spring74the detent tooth assembly60of the pivot pin28is set back into the teeth56,58of the detent slots48,50. In such a way the desired rough adjustment of the second gripper arm14with respect to the first gripper arm12can be carried out.

The longitudinal slot42of the first gripper arm12is provided with two pairs of opposite bearing surfaces62,64. The bearing surfaces62,64run parallel to the pivot axis29and parallel to the detent slots48,50. The plane bearing surfaces62,64provided on the front and rear side of the first gripper arm12each surround the longitudinal slot42on its side. The second movable pliers jaw30has a first pair of abutment surfaces66on the side of the longitudinal slot42in the form of a projection. The guiding lug44extending through the longitudinal slot42has a corresponding second pair of abutment surfaces68which is also designed as a button-like projection69. The abutment surfaces68is directed towards the abutment surfaces64.

The bearing surfaces62,64together with the abutment surfaces66,68form a compulsory guide70. The compulsory guide70ensures that the movable second pliers jaw30can slide only along the bearing surfaces62,64—like on a track.

InFIG. 1an area is marked with a circle72, which is shown inFIG. 2in an enlarged version. A portion of the section32is shown in this representation with a portion of the pliers jaws26,30pressed together. The second movable pliers jaw30shows the integrated guiding lug44guided through the longitudinal slot42. The abutment surface68in the form of a button-like projection69can bee seen at an end of the guiding lug44projecting from the longitudinal slot42. The abutment surface66and the abutment surface68guide the second movable pliers jaw30along the bearing surfaces62,64in the section32of the first gripper arm12. Thereby the second pliers jaw30is supported by compulsory guide70formed in such way.

The gripper arms12,14are pivoted about the pivot pin28for producing the lever power effective on the pliers jaws26,30. For this purpose the second gripper arm14engages the joint connection34consisting of the integrated shoulder-shaped projection40and the recess36. The second pliers jaw30is guided only along the compulsory guide70when the tool is operated. The joint34requires a corresponding gap in the recess36in order to enable these movements. The recesses36are normally not visible and covered towards the outside, especially to avoid pinching injuries and dirt.

InFIG. 2also the detent mechanism46for the rough adjustment becomes apparent by the enlarged representation. The pivot pin28is adjustably guided by the guide formed by the two opposite detent slots48,50. The detent tooth assembly60is produced in such a way that they engage the toothing56,58of the detent slots48,50in the locked state. The detent tooth assembly60is biased with springs74. By operating the button59the detent tooth assembly60is pushed out of the toothing56,58. Thereby the pivot pin28can be moved back and forth in the detent slots48,50for rough adjustment. By releasing the press button59the detent tooth assembly60locks in any detent position for the desired pliers opening size.

FIG. 3is a front view in a schematic principle sketch of the pliers10according to the present invention. With this drawing it shall mainly be highlighted, that the longitudinal slot42is formed by the first gripper arm12the second gripper arm14extending therethrough. The gripper arms12and14are pivotable about the pivot axis29formed by the pivot pin28in order to operate the tool. The same components of the pliers10are denoted otherwise with the corresponding numerals as in the previous figures.