Actuating device of the type provided with an actuating element and sensing means for revealing the positioning of the actuating element

An actuating device which comprises a housing inside of which a slidably displaceable actuating element and sensing means adapted to detect the positioning of the actuating element are provided, wherein the actuating element is coupled to at least one triggering part and the housing comprises at least one reading opening through which the positioning of the at least one triggering part at at least one sensing position can be detected; further wherein the sensing means are placed outside the housing at the reading opening and the at least one triggering part is completely housed inside the housing, the at least one reading opening being sealed with a cover made of a material adapted to allow the detection of the triggering part when placed at the at least one sensing position.

BACKGROUND TO THE INVENTION

The present invention relates to an actuating device of the type provided with an actuating element and sensing means for revealing the positioning of the actuating element which is typically movable between an operative and a non-operative end position. In particular, the present invention relates to an actuating device typically used for handling elements during metalworking processes, e.g. in welding lines of the vehicle body construction industry.

In metalworking processes, the actuating devices are usually provided with sensors to detect the positioning of the actuating elements (at its operative or non-operative end position, respectively) and indicate it to a process computer in order to allow production automation. Typical actuating devices used in the vehicle body construction industry and provided with end position sensors are clamping units or power clamps, pivoting units or power pivots, pin units like e.g. retractable locating pin units, pin clamps, gripper units and marking units. By way of example, in clamping units the actuating element comprises a piston rod connected to a fork linkage. The group consisting of the piston rod and the fork linkage moves between two end positions, thereby displacing an articulated lever mechanism which, on its turn, causes a pivotable arm to rotate.

RELATED ART

The actuating devices nowadays used in the vehicle body construction industry, typically comprise a sensor at least partially housed inside the actuating device. The sensor usually comprises sensing elements positioned outside the sensor body at two predefined sensing positions. Furthermore, the actuating element comprises, is connected or coupled to triggering parts which are moved together with the actuating element in order to reach the one or the other sensing position when the actuating element reaches its operative or non-operative position, respectively. Such kind of actuating devices are known e.g. from DE 196 16 441 wherein the sensing elements are switches which can be alternatively energized by a cam switch (triggering part) connected to the piston rod when arranged in front of the respective switch. A displacement of the piston rod causes the cam switch to move from the first switch to the second switch so that the reaching of the two end positions of the piston rod can be detected.

According to a further kind of known actuating device, the sensor is substantially housed inside the actuating device and the sensing elements are arranged inside the sensor body, one next to the other. The sensing elements typically are of the inductive type and can be triggered by metal parts or, more generally, parts made of ferromagnetic material, displaced inside the actuating device by the actuating element itself or another movable part of the actuating device.

An actuating device of this kind is disclosed in DE 10 2013 001 004. The actuating device described in this document comprises two triggering parts, one connected to a bar slidably mounted inside the actuating device and one connected to the piston rod. Furthermore, the piston rod carries a dragging element which drags the slidable bar when the piston rod is moved towards its operative end position. This causes the triggering part mounted on the bar to reach its sensing position in front of a first sensing element. When the piston rod is brought into its non-operative position, the triggering part mounted on the same reaches its sensing position in front of the second sensing element. Furthermore, during the movement of the piston rod towards its non-operative position, the dragging element disengages from the bar which is returned to its initial position under the action of a spring. In this position, the triggering part mounted on the bar is not anymore arranged in front of the corresponding first sensing element.

Both the above described actuating devices provide for that the sensor is at least partially housed inside the actuating device. This implies that the housing of the actuating device has an opening for the insertion/extraction of the sensor.

Applicant realized that, accordingly, during replacement of the sensor (e.g. in case of malfunctioning of the same) the opening of the housing is in a non-sealed configuration which can lead to the entry of dirt or humidity inside the housing. Furthermore, also when the sensor is mounted inside the opening, an absolute sealing of the device housing cannot be assured because of the interstices between the housing and sensor surfaces in direct contact between each other. Therefore, a small quantity of dirt and humidity can always enter the device housing, thereby gradually deteriorating the moving parts of the device.

Furthermore the actuating device described in EP 2 548 700 is also known. This actuating device comprises an optical sensor lodged completely outside the housing of the actuating device. The optical sensor detects the position of a movable element projecting from the housing. The projecting element is slidably displaced between two sensing positions of the sensor by means of two dragging parts connected to the piston rod. When the dragging parts disengage from the projecting element, it is returned into a neutral non-sensing position by means of elastic means.

When the sensor is mounted on the housing, it completely covers the opening from which the projecting element protrudes.

Applicant realized, however, that even if the opening is covered by the sensor housing, a sealing of the device housing is not assured. Furthermore, when the sensor is replaced, the opening is laid open by the removal of the sensor thereby allowing dirt and humidity to enter inside the housing.

SUMMARY OF THE INVENTION

Accordingly, Applicant considered the problem of obviating the above mentioned drawbacks and, in particular, of providing an actuating device which assures an always constant and high sealing degree, even during replacement of the sensor.

Accordingly, the present invention relates to an actuating device comprising:a housing inside of which an actuating element is provided, the actuating element being slidably displaceable along a first axis between a first operative position and a second non-operative position and sensing means adapted to detect the positioning of the actuating element at at least one of the first or the second position;the actuating element being coupled to at least one triggering part so that a positioning of the actuating element at one of the first or the second position corresponds to the positioning of the at least one triggering part at at least one sensing position;the housing comprising at least one reading opening through which the positioning of at least one triggering part at the at least one sensing position can be detected;the sensing means comprising at least one sensing element associated with the at least one sensing position in order to detect the positioning of at least one triggering part at the at least one sensing position, the sensing means being placed outside the housing and being connected to the same at the reading opening;
characterized in that the at least one triggering part is completely housed inside the housing and the at least one reading opening is sealed with a cover made of a material adapted to allow the detection of the triggering part when placed at the at least one sensing position.

Throughout the present description and in the appended claims the expression “sensing position” refers to a position falling within the sensing range of a sensing element so that a detectable part located at the sensing position is effectively detected by the sensing element.

This advantageously allows achieving a constant and reliable sealing condition of the actuating device housing even during replacement of the sensor. In fact, the triggering parts are completely housed inside the device and the sensor is completely external to the device. Between the two interacting parts, an opening is provided which, however, is sealed with a material which still allows the sensor to detect the presence of the triggering parts. Therefore, during both, normal use and replacement of the sensor, the opening remains in a permanently sealed condition, even when the sensor is removed. Consequently, the entering of dirt or humidity into the device housing is mainly and constantly prevented, thereby assuring a longer life of the device moving parts.

Preferably, the cover is made of non-magnetic material, preferably non metallic material.

Advantageously, this kind of material makes it possible to use inductive sensing elements, since non-magnetic material does not interfere with the detection of metallic ferromagnetic materials operated by inductive sensors.

Preferably, the cover is made of an adhesive material, preferably an acrylic material.

Advantageously, this assures a reliable sealing of the reading opening so that no humidity or powder particles can enter inside the housing.

Preferably, the actuating element is coupled to two triggering parts movable towards and away from a respective first and second reading opening, each reading opening being coupled to a sensing element of the sensing means thereby defining a sensing position.

Preferably, the sensing means comprise two sensing elements placed out of alignment with respect of both, a vertical and a horizontal axis.

Expediently, this avoids that the displacement of a triggering part interferes with both sensing elements, thereby providing incorrect detections.

More preferably, the two sensing elements are placed along a line inclined diagonally with respect to the horizontal/vertical axis, preferably inclined by 45° or 60°.

This advantageously allows indifferently constraining the sensing means to the housing according to two reciprocally perpendicular configurations. This reveals to be particularly favorable in case the sensor needs to be connected to a slim housing. In this case, the sensor is mounted so as to have its larger side vertically oriented.

Preferably, the sensing elements are inductive sensing elements and the triggering parts are made of metallic material.

Preferably, the sensing means comprise a sensor body to which a connector for signal extraction is fixed by means of a screw, wherein the connector is adapted to be fixed to the sensor body according to a plurality of orientations.

This advantageously assures a higher flexibility degree, allowing to set the most suitable orientation of the connector according to the room available and the particular plant line design.

More preferably, the connector comprises a nut shaped so as to cooperate with the head of the screw in order to define a plurality of stable connections between the connector and the sensor body.

Even more preferably, the nut defines a plurality of seats adapted to house at least a portion of the screw head.

This advantageously assures a high stability of the positioning of the connector when it is constrained to the sensor body at an orientation corresponding to the screw head being stably housed inside one of the plurality of seats.

More preferably, the sensor body comprises a guiding groove which rotatably engages with the connector in order to allow reciprocal rotation between the connector and the sensor body when the screw is not fastened.

Preferably, the at least one triggering part is carried by at least one leverage pivotably connected to the housing, the movement of the actuating element causing the leverage to rotate.

More preferably, the leverage cooperates with a cam guide defined by the outer surface of the actuating element, wherein the displacement of the leverage along the cam guide puts the leverage into rotation.

Even more preferably, the leverage comprises a rotating pin engaging with the cam guide.

The particular moving mechanism chosen to displace the at least one triggering part leads to a high room saving inside the device housing, since the movement of the actuating element is converted into a very small movement of the triggering part.

Preferably, the at least one leverage cooperates with elastic means for returning into a rest position when disengaged from the cam guide.

Preferably, a first triggering part is carried by a first leverage pivotably connected to the housing so as to rotate about a first axis of rotation perpendicular to the sliding movement of the actuating element.

More preferably, a second triggering part is carried by a second leverage pivotably connected to the housing so as to rotate about a second axis of rotation parallel to the sliding movement of the actuating element.

Preferably, the second leverage cooperates with a portion of the actuating element having increased outer diameter which urges the second leverage against the action of the elastic means when the actuating element reaches at least one of the first or the second position.

More preferably, the portion with increased outer diameter is positioned at an axial position of the actuating element and extends along an annular portion or, preferably, all around the actuating element.

Preferably, the actuating device is a clamping unit and the actuating element comprises a piston rod connected to fork linkage, the actuating element acting on an articulated lever or cam mechanism for actuating the rotation of a pivotable arm.

Alternatively, the actuating element is a two-part rod and the at least one triggering part is a fastening pin of the two-part rod.

More preferably, the fastening pin is moved by the two-part rod between the first sensing position and an engagement position in which the fastening pin cooperates with a slide carrying a second triggering part and moves the slide to an end position in which the second triggering part is placed at the second sensing position.

Even more preferably, the slide cooperates with elastic means for returning into a rest position when disengaged from the fastening pin.

Preferably, the actuating device is a pin unit, preferably a retractable locating pin unit.

According to a further embodiment, the actuating element is at least one slidable rod comprising a circular slit and the at least one triggering part is connected to the at least one slidable rod by means of a half-annular connector engaged with the rod slit.

More preferably, the at least one triggering part is movable between the first sensing position and an engagement position in which it cooperates with a slide carrying a second triggering part and moves the slide to an end position in which the second triggering part is placed at the second sensing position.

Even more preferably, the slide cooperates with elastic means for returning into a rest position when disengaged from the fastening pin.

Preferably, the actuating device is a double rod pin unit.

DETAILED DESCRIPTION OF CURRENTLY PREFERRED EMBODIMENTS OF THE INVENTION

InFIGS. 1aand 1ba first embodiment of an actuating device according to the present invention is globally indicated with10. The actuating device according to the first embodiment is a clamping unit.

The clamping unit10comprises a housing15inside of which an actuating element11is provided, wherein the actuating element comprises a piston rod connected to a fork linkage. The actuating element11acts on an articulated lever17or cam mechanism for actuating the rotation of a pivotable arm18. The actuating element11is linearly displaceable along a first axis A, between a first operative12and a second non-operative13position, which correspond to the operative and a non-operative angular positions of the pivotable arm, respectively.

The clamping unit10also comprises sensing means20for revealing the positioning of the actuating element11at its first12or second13end position.

In the embodiment ofFIGS. 1aand 1b, the sensing means comprise a sensor20mounted outside the housing15and fixedly constrained to the same15. The sensor20comprises two inductive sensing elements21completely contained inside the sensor body22.

As shown inFIG. 2, the sensing elements21are positioned out of alignment with respect of both, a vertical Y and a horizontal X axis and, particularly, the two sensing elements21are placed along a line inclined by 45° with respect to the said axes X and Y.

The sensor20is constrained to the device housing15so that the sensing elements21are positioned each at a reading opening16a,16bobtained in the housing15. Therefore, as shown inFIG. 1b, also the reading openings16a,16bare positioned out of alignment with respect of both, the vertical Y and the horizontal X and particularly along a line inclined by 45° with respect to the said axes X and Y.

According to this configuration, each sensing element21defines a sensing position placed inside the housing15, in front of the respective reading opening16a,16b.

According to the present invention, the reading openings16a,16bare sealed with a cover40made of a material adapted, on the one hand, to allow the sensing elements21to define sensing positions placed inside the device housing15and, on the other hand, to assure a proper permanent sealing of the housing15. In case of inductive sensing elements21, the cover40is made of non-magnetic, adhesive material. In detail, the cover40is made of acrylic material.

As shown in detail inFIGS. 3aand 3b, the actuating element11is coupled to a first31and a second32triggering part so that when the actuating element11is positioned at the first end position12, the first triggering part31is positioned at a first sensing position and, when the actuating element11is positioned at the second end position13, the second triggering part32is positioned at a second sensing position defined by the sensing elements21.

The first triggering part31is carried by a first leverage33pivotably connected to the device housing15at a first pivot34so as to rotate about a first axis of rotation B perpendicular to the sliding movement of the actuating element11.

The first leverage33comprises a rotating pin36which rests against the actuating element11. In detail, the outer surface of the fork linkage defines a cam guide35which cooperates with the rotating pin36in such a way that movement of the fork linkage urges the first leverage31to rotate about the first pivot34towards the housing15wall. This movement of the first leverage33brings the first triggering part31at the first sensing position in front of the first reading opening16a.

Furthermore, the first leverage33cooperates with first elastic means42which cause the return of the first triggering part31into its initial position (away from the respective sensing position), when the actuating element11leaves the first end position12and moves towards its second end position13, namely when the cam guide35does not urge anymore the rotating pin36towards the housing15wall.

The second triggering part32is carried by a second leverage37pivotably connected to the device housing15at a second pivot41so as to rotate about a second axis of rotation C parallel to the sliding movement of the actuating element11.

When the actuating element11reaches its second end position13, a portion38of the piston rod having increased outer diameter interferes with the second leverage37so as to urge it against the action of second elastic means39, shown in detail inFIGS. 4aand 4b. This causes the second triggering part32to be moved towards the second sensing position in front of the second reading opening16b.

When the actuating element11leaves its second end position13, the portion38with increased diameter gets off the second leverage37. So, the second leverage37can return to its initial position under the action of the second elastic means39and the second triggering part32leaves the second sensing position.

With regard toFIGS. 6ato 6d, the sensor20further comprises a connector23constrained to the sensor body22by means of a screw25.

The connector23is mounted on the sensor body22so as to be fixed to the same22according to a plurality of orientations varying within an angle of 90°.FIGS. 5aand 5brespectively show the two outmost orientations.

To achieve the above flexibility in setting the most suitable orientation of the connector23, the surface of the connector which couples with the sensor body22comprises a curved nose26which cooperates with a complementary guiding groove24obtained on the sensor body22in order to retain the connector23, but at the same time allow reciprocal rotation between the connector23and the sensor body22. In detail, both the curved nose26and the guiding groove24develop along an angular portion, which in the depicted embodiment is of 90°.

Furthermore, the connector23comprises on its outer surface a curved nut27shaped so as to cooperate with the head25aof the screw25in order to define a plurality of stable connections between the connector23and the sensor body22.

In detail, the curved nut27has a development extending parallel to the curved nose26and, at predefined angular positions, it defines a plurality of seats27aadapted to house at least a portion of the screw head25a.

In the embodiment depicted inFIGS. 6ato 6b, the curved nut27comprises a seat27aat each of its end positions. This allows stably connecting the connector23to the sensor body22at two orientations inclined by 90° one with respect to the other. Nevertheless, stable connections are possible also at different orientations at which the screw head25aacts against the surface of the curved nut27outside the seats27a.

InFIGS. 7aand 7ba second embodiment of an actuating device according to the present invention is globally indicated with50. The actuating device according to the second embodiment is a retractable locating pin unit50.

The pin unit50comprises a housing55inside of which an actuating element51is provided, wherein the actuating element is a two-part rod. The two parts51a,51bof the rod51are connected to each other by means of two fastening pins52a,52b. The two-part rod51is linearly displaceable along a sliding axis A′, between a first operative and a second non-operative position.

The pin unit50also comprises sensing means (not shown) for revealing the positioning of the two-part rod51at its first or second end position, which are substantially the same as described with reference to the first embodiment.

The sensor is constrained to the device housing55at two reading openings56a,56bobtained in a plate57constrained to the housing55so as to define two sensing positions placed inside the housing55, in front of the respective reading openings56a,56b.

Also according to the second embodiment, the reading openings56a,56bare sealed with a cover40made of a material adapted, on the one hand, to allow the sensing elements to define sensing positions placed inside the device housing55and, on the other hand, to assure a proper and permanent sealing of the housing55.

The first triggering part coupled to the two-part rod51is one of the fastening pins52awhich protrudes from the two-part rod51towards the side of the housing55to which the plate57carrying the reading openings56a,56bis fastened.

When the two-part rod51is in its non-operative position, the fastening pin52ais positioned at a first sensing position, inside the housing55, in front of the first reading opening56a.

The second59triggering part is carried by a slide53slidably constrained to the device housing55behind the plate57. The slide53is urged into a rest position by means of elastic means58. When the slide53is in its rest position, the second triggering part59is outside the second sensing position which is located inside the housing55, in front of the second reading opening56b.

When the two-part rod51moves towards its operative position, the fastening pin52ais moved away from the first sensing position. When the two-part rod51reaches its operative position, the fastening pin52aengages the slide53and drags it against the force of the elastic means58. This movement of the slide53brings the second triggering part59into the second sensing position.

When the two-part rod51moves back towards its non-operative position, the fastening pin52adisengages from the slide53and the elastic means58urge it53(and consequently the second triggering part59) back into its rest position away from the second sensing position.

InFIGS. 8aand 8ba third embodiment of an actuating device according to the present invention is globally indicated with80. The actuating device according to the third embodiment is a double-rod pin unit80.

The pin unit80comprises a housing85inside of which an actuating element81is provided, wherein the actuating element is a double rod linearly displaceable along a sliding axis A″ between a first operative and a second non-operative position.

The pin unit80also comprises sensing means (not shown) for revealing the positioning of the double rod81at its first or second end position, which are substantially the same as described with reference to the first embodiment.

The sensor is constrained to the device housing85at two reading openings86a,86bobtained in a plate87constrained to the housing85so as to define two sensing positions placed inside the housing85, in front of the respective reading openings86a,86b.

Also according to the third embodiment, the reading openings86a,86bare sealed with a cover40made of a material adapted, on the one hand, to allow the sensing elements to define sensing positions placed inside the device housing85and, on the other hand, to assure a proper permanent sealing of the housing85.

The two rods81a,81bof the double rod81comprise each a circular slit82. The first triggering part83is connected to one of the two rods81a,81bby means of a half-annular connector84engaged with the rod slit82. The first triggering part83is connected to one of the two rods81a,81bin a way so as to protrude towards the side of the housing85to which the plate87carrying the reading openings86a,86bis fastened.

When the two rods81a,81bare in their non-operative position, the triggering part83is positioned at a first sensing position, inside the housing85, in front of the first reading opening86a.

The second triggering part88is carried by a slide90slidably constrained to the device housing85behind the plate87. The slide90is urged into a rest position by means of elastic means89. When the slide90is in its rest position, the second triggering part88is outside the second sensing position which is located inside the housing85, in front of the second reading opening86b.

When the two rods81a,81bmove towards their operative position, the first triggering part83is moved away from the first sensing position. When the two rods81a,81breach their operative position, the first triggering part83engages the slide90and drags it against the force of the elastic means89. This movement of the slide90brings the second triggering part88into the second sensing position.

When the two rods81a,81bmove back towards their non-operative position, the first triggering part83disengages from the slide90and the elastic means89urge it90(and consequently the second triggering part88) back into its rest position away from the second sensing position.