EP2511048B1 - Screw driver with torque limitation - Google Patents

Description

The invention relates to a screwdriver with torque limiter according to the preamble of patent claim 1.

Are known screwdriver with a torque limiting enclosing handle and with a handle inserted coaxially into the shaft, which is rotatably coupled to the handle and torque-locked with this over the torque limiter, each relative rotation between the shaft and the handle by at least one defined angle a switching cycle represents. Torque-limiting screwdrivers are advantageous for tightening screws with a predetermined force, which, on the one hand, ensures reliable holding of the screw connection and, on the other hand, precludes overstressing the thread. The shaft is therefore rotatable in the handle to allow disengagement of the torque limiting mechanism. When the torque transmitted via the clutch from the handle to the shaft exceeds a limit torque, the torque limiting mechanism disengages and the shaft rotates against the handle by at least a defined angle until the torque limiting mechanism reengages. The torque limiting mechanism is subject to wear.

From the DE 20 2007 007 759 U1 , of the DE 20 2005 013 648 U1 and the EP 1 092 510 A2 are each a screwdriver with a torque limiting enclosing handle and with a coaxially inserted into the handle shaft, which is rotatably coupled to the handle and torque-coupled with this torque limiting, known in which a torque exceeded to a relative rotation between the shaft and the handle by at least one defined angle leads.

From the US Pat. No. 7,047,849 B2 a ratchet is known in which when exceeding a given torque inside a tubular, screwed with a handle shank by displacement of a wedge, a signal is generated, which is counted by a counter.

The object of the invention is therefore to develop a generic screwdriver with torque limiter to make the use more comfortable.

The object is achieved by a screwdriver with the features of claim 1.

Advantageous embodiments and further developments of the invention are specified in the dependent claims.

The screwdriver according to the invention with a torque limiting enclosing handle and with a coaxially inserted into the handle shaft which is rotatably coupled to the handle and torque-coupled thereto via the torque limiter, each relative rotation between the shaft and the handle by at least one defined angle a switching cycle is characterized in that the screwdriver comprises means for counting the switching cycles. By the means for counting the switching cycles, the user is given the information on which wear the torque limiting mechanism is already subjected, so that the user can see how much stress the screwdriver is.

The means for counting the switching cycles may preferably be formed as an active or passive component.

According to a particularly preferred embodiment of the invention, the means to a Hall sensor and at least one magnetic element, wherein preferably the Hall sensor rotatably connected to the handle and the at least one magnetic element rotatably connected to the shaft. In a relative rotation between the shaft and the handle thus also takes place a relative rotation between the Hall sensor and the at least one magnetic element, so that the relative rotation can be detected by the Hall sensor.

Particularly preferably, the magnetic element is made of magnetic plastic, which allows a simple and cost-effective production.

Preferably, a disc is coaxially penetrated by the shaft and is rotatably connected thereto, wherein at least one magnetic element is arranged on the disc. In this way a mounting of the magnetic elements on the shaft is made possible in a compact design.

According to a preferred embodiment of the invention, the means comprise a reed contact and a magnetic element, wherein preferably the magnetic element rotatably connected to the shaft and the reed contact rotatably connected to the handle.

According to a preferred embodiment of the invention, the means comprise a cam disc with at least one cam and a button, wherein preferably the cam disc rotatably connected to the shaft and the probe rotatably connected to the handle.

Preferably, an actuator is disposed between the cam and the button, which in particular allows a compact arrangement within the handle.

Preferably, the means include optical, inductive, capacitive or by means of a piezoelectric element, the switching cycles.

According to a preferred embodiment of the invention, the torque limiting two by means of engagement elements, preferably by means of ratchet teeth, interlocking coupling elements, wherein the defined angle is defined by the angular distance between two adjacent engagement elements.

According to a particularly preferred embodiment of the invention, the number of magnetic elements or the number of cams corresponds to the number of engagement elements or to this in an integer ratio, in order thus to a direct correlation between the relative rotation between the shaft and handle and the counted Number of switching cycles to achieve.

Fig. 1

eine Seitenansicht eines ersten Ausführungsbeispieles eines Schraubendrehers gemäß der Erfindung,

Fig. 2

einen Längsschnitt durch den Schraubendreher gemäß Figur 1,

Fig. 3

eine perspektivische Ansicht der Scheibe mit den magnetischen Elementen des Schraubendrehers gemäß Figur 2,

Fig. 4

eine Seitenansicht eines Schraubendrehers gemäß einem weiteren Ausführungsbeispiel der Erfindung,

Fig. 5

einen Längsschnitt entlang der Linie A-A gemäß Figur 4,

Fig. 6

eine Ansicht von hinten auf den Schraubendreher gemäß Figur 4 ohne Endkappe,

Fig. 7

eine weitere Seitenansicht des Schraubendrehers gemäß Figur 4,

Fig. 8

einen Längsschnitt entlang der Linie B-B des Schraubendrehers gemäß Figur 7 und

Fig. 9

eine perspektivische Ansicht der Nockenscheibe mit Betätigungselement und Taster gemäß Figur 8.

The invention will be explained in detail with reference to the following figures. Show it

Fig. 1

a side view of a first embodiment of a screwdriver according to the invention,

Fig. 2

a longitudinal section through the screwdriver according to FIG. 1 .

Fig. 3

a perspective view of the disc with the magnetic elements of the screwdriver according to FIG. 2 .

Fig. 4

a side view of a screwdriver according to another embodiment of the invention,

Fig. 5

a longitudinal section along the line AA according to FIG. 4 .

Fig. 6

a view from behind on the screwdriver according to FIG. 4 without end cap,

Fig. 7

another side view of the screwdriver according to FIG. 4 .

Fig. 8

a longitudinal section along the line BB of the screwdriver according to FIG. 7 and

Fig. 9

a perspective view of the cam with actuator and button according to FIG. 8 ,

In the FIGS. 1 to 3 a first embodiment of a screwdriver 10 is shown with a handle 20 in which a torque limiting mechanism is integrated and in which a shaft 30 is inserted coaxially. The torque limiting mechanism is not the subject of the invention and can be designed in different designs. It is essential that the shaft 30 is inserted coaxially rotatable in the handle 20 and that the force exerted on the handle 20 torque is transmitted via a coupling 78 of the torque limiting mechanism on the shaft 30. In this case, the clutch 78 is acted upon, for example by a helical spring designed as a compression spring 88 which holds the clutch 78 with an axial compressive force in engagement. The clutch 78 has a first coupling element 80 and a second coupling element 84. The first coupling element 80 is rotatably connected to the shaft 30, while the second coupling element 84 is rotatably connected to the handle 20. The two coupling elements 80, 84 may have, for example, a corresponding number of latching teeth 82, 86 which are engaged with each other upon engagement of the coupling 78. Exceeds the transmitted from the handle 20 to the shaft 30 via the clutch 78 torque a predetermined limit, the clutch 78 is lifted against the force of the compression spring 88 from the engaged position, so that the handle 20 can rotate relative to the shaft 30. For example, the ratchet teeth 82, 86 slide over each other until the clutch 78 is again engaged. Instead of ratchet teeth 82, 86 can also be used differently shaped engagement elements, for example based on balls or the like. As a switching cycle, a rotation between the shaft 30 and the handle 20 is considered by the smallest possible angle of rotation, which is necessary for a lifting out of an engagement position of the clutch 78 until the clutch 78 is engaged again, for example, the angular distance between two adjacent Latching teeth 82 of the first coupling element or two adjacent latching teeth 86 of the second coupling element.

The screwdriver 10 has means for counting the switching cycles. The means for counting the switching cycles can be designed as active or passive components.

In the in the Figures 1-3 Screwdriver 10 shown have the means an active device in the form of a Hall sensor 40 and a disc 50 with a plurality of magnetic elements 52. As passive components, for example, alternative to the Hall sensor 40 and reed contacts can be used. The Hall sensor 40 is rotatably connected to the handle 20. The disc 50 is rotatably connected to the shaft 30 and is particularly coaxially penetrated by this. The number of magnetic elements 52 preferably corresponds to the number of engagement elements, in particular the number of ratchet teeth 82, 86 of the clutch 78. For example, the clutch 78 may have a first coupling element 80 with nine ratchet teeth 82 and a second coupling element 84 with nine ratchet teeth 86. In this case, nine magnetic elements 52 are likewise arranged on the disk 50 (cf. Fig. 3 ). The magnetic elements are preferably made of magnetic plastic. Furthermore, the magnetic elements 52 can be placed on the disc 50 and secured thereto be. Preferably, the magnetic elements 52 and the disc 50 are integrally formed and in particular made of magnetic plastic.

The Hall sensor 40 is arranged in particular axially parallel to the longitudinal axis of the shaft 30 and can distinguish whether a magnetic element 52 is in its detection range or the gap between two adjacent magnetic elements 52. The Hall sensor 40 is in this case with an evaluation electronics by means of which it can be counted how many times a magnetic element 52 moves past the Hall sensor 40. In this way, the switching cycles of the clutch 78 can be counted. To power the Hall sensor 40 and the evaluation electronics, a battery or the like is provided.

On the handle 20, a display, not shown, is arranged, on which with the aid of the evaluation electronics, the number of switching cycles can be displayed. Furthermore, the status of the battery used for the Hall sensor 40 or, if the torque of the torque limiting mechanism of the screwdriver 10 is variable, the set torque can be displayed on such a display. If necessary, appropriate warning signals or warnings can be output when overwriting predetermined limit values for the number of switching cycles or the set torque or shortly before complete emptying of the battery.

In the Figures 4-9 is another embodiment of a screwdriver 10 'shown. This differs from that in the Figures 1-3 illustrated embodiment of the screwdriver 10 essentially by the design of the means for counting the switching cycles, while the torque limiting mechanism is essentially identical. The screwdriver 10 'has means for counting the switching cycles, which have a cam disc 70 and a button 60. The cam plate 70 is rotatably connected to the shaft 30, while the button 60 rotatably connected to the handle 20. On the cam plate 70 cams 72 are arranged. The number of cams 72 preferably corresponds to the number of engagement elements of the clutch 78. In particular, in the present case, the cam disk 70 has ten cams 72 (cf. Fig. 9 ). Between the cam plate 70 and the button 60, an actuating element 75 is arranged substantially parallel to the longitudinal axis of the shaft 30, so that the button 60 can be arranged radially inside the cam plate 70 and axially offset therefrom to achieve a compact design. Rotates the cam plate 70 in a relative movement between the shaft 30 and the handle 20, the actuating element 75 is tilted by the cam 72 such that the remote from the cam 72 end of the actuating element 75 actuates the button 60. An evaluation electronics connected to the button 60 counts the actuations of the button 60 and thus the number of switching cycles of the coupling 78. The number of switching cycles or other information relevant to the user can be displayed on a display 90 in the handle 20 of the screwdriver 10.

LIST OF REFERENCE NUMBERS

10

screwdriver

10 '

screwdriver

20

handle

30

shaft

40

Hall sensor

50

disc

52

magnetic element

60

button

70

cam

72

cam

75

actuator

78

clutch

80

first coupling element

82

ratchet

84

second coupling element

86

ratchet

88

compression spring

90

display

Claims (10)

1. Screwdriver (10, 10') comprising a handle (20), including torque limitation, and a shank (30) which is coaxially inserted into the handle (20), that can be rotated against the handle (20) and torsionally fixed thereto by means of the torque limiter, wherein each relative rotation about at least one defined angle between the shank (30) and the handle (20) represents an operating cycle, characterized in that the screwdriver (10, 10 ') has means for counting the operating cycles.
2. Screwdriver according to any one of the above claims, characterized in that the means have a Hall sensor (40) and at least one magnetic element (52), wherein preferably the Hall sensor (40) is rotationally fixed to the handle (20) and the at least one magnetic element (52) is rotationally fixed to the shank (30).
3. Screwdriver according to claim 2, characterized in that the magnetic element (52) is made of magnetic plastic.
4. Screwdriver according to any one of claims 2 to 3, characterized in that a disc (50) is coaxially traversed by the shank (30) and is rotationally fixed thereto and at least one magnetic element (52) is arranged on the disc (50).
5. Screwdriver according to any one of the above claims, characterized in that the means have a Reed contact and a magnetic element, wherein preferably the magnetic element is rotationally fixed to the shank and the Reed contact is rotationally fixed to the handle.
6. Screwdriver according to any one of the above claims, characterized in that the means has a cam disc (70) with at least one cam (72) and a sensor (60), wherein preferably the cam disc (70) is rotationally fixed to the shank (30) and the sensor (60) is rotationally fixed to the handle (20).
7. Screwdriver according to claim 6, characterized in that an actuator (75) is arranged between the cam disc (70) and the sensor (60).
8. Screwdriver according to any one of the above claims, characterized in that the means count the operating cycles optically, inductively, capacitively or by way of a piezo element.
9. Screwdriver according to any one of the above claims, characterized in that the torque limiter has two coupling elements (80, 84) engaging one another by means of engagement elements, preferably by means of ratchet teeth (82, 86), and the defined angle is defined by the angular distance between two adjacent engagement elements.
10. Screwdriver according to claim 9, characterized in that the number of the magnetic elements (52) or the number of the cams (72) corresponds to the number of the engagement elements or stand in an integer relationship with each other.

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