1. A tensioning device comprising:
a back plate configured to be secured to a wall by inserting at least two back plate securing elements through a respective one of at least two back plate mounting transcurrent openings therein, wherein the back plate is fixed with respect to the wall such that the back plate cannot pivot with respect to either of the at least two securing elements when the at least two back plate securing elements are engaged with the at least two back plate mounting transcurrent openings and the wall, and
a tensioning roller installed onto the back plate, the tensioning roller including;
at least one bearing, and
a pulley supported by the at least one bearing, the tensioning roller being installed on the back plate with a tension roller axis (X4) capable of rotating about an eccentric axis (X6) during installation of the tensioning device, the tensioning device is configured such that the tension roller axis (X4) is fixed during normal operation, and
the tensioning roller is provided with a protuberance engaged in a peripheral recess produced exclusively on the periphery at the outer edge of a zone projecting from the back plate, the peripheral recess limiting the movement of the protuberance between two abutments wherein when the protuberance abuts either of the abutments the tensioning roller axially overlaps at least one of the back plate mounting transcurrent openings located in the back plate, the peripheral recess being configured for moving the tensioning roller prior to fixing the tension roller axis (X4) for normal operation of the tensioning device, wherein the tensioning device is free of springs.
2. The tensioning device according to claim 1, wherein the at least one bearing is installed securely on a roller support that is provided with the protuberance.
3. The tensioning device according to claim 2, wherein the peripheral recess is produced on a maximum of one half of the circumference of the projecting zone.
4. The tensioning device according to claim 1, wherein the peripheral recess is in the form of a sector of a circle according to a radial cross section in relation to the eccentric axis (X6) about which the tensioning roller can move on the back plate during installation.
5. The tensioning device according to claim 1, further comprising a screw inserted into a first screw transcurrent opening in the tensioning roller and into a second screw transcurrent opening in the back plate, the eccentric axis (X6) of the screw being parallel although not combined with, the tension roller axis (X4).
6. The tensioning device according to claim 1, wherein a traction element is subjected to a force (F1) exerted by the tensioning roller when the protuberance is in contact with the abutment corresponding to a final installed position of the tensioning device in the traction circuit.
7. The tensioning device according to claim 3, wherein the peripheral recess is produced on one quarter of the circumference of the projecting zone.
8. The tensioning device according to claim 6, wherein the peripheral recess is configured such that if during use the tensioning device malfunctions and the tensioning roller axis is no longer fixed, the tensioning roller will be biased into the proper position by the traction element being subjected to a force (F2) exerted by the tensioning roller greater than (F1) when disposed in an intermediate position of the protuberance in the peripheral recess of the back plate, with no contact with any of the two abutments, thus providing an anti-return feature.
9. An engine equipped with at least one traction circuit driven by a traction element and equipped with a tensioning device, the tensioning device comprising:
a back plate configured to be secured to a wall by inserting at least two back plate securing elements through a respective one of at least two back plate mounting transcurrent openings therein, wherein the back plate is fixed with respect to the wall such that the back plate cannot pivot with respect to either of the at least two securing elements when the at least two back plate securing elements are engaged with the at least two back plate mounting transcurrent openings and the wall, and
a tensioning roller installed onto the back plate, the tensioning roller including;
at least one bearing, and
a pulley supported by the at least one bearing, the tensioning roller being installed on the back plate with a tension roller axis (X4) capable of rotating about an eccentric axis (X6) during installation of the tensioning device, the tensioning device is configured such that the tension roller axis (X4) is fixed during normal operation, and
the tensioning roller is provided with a protuberance engaged in a peripheral recess produced exclusively on the periphery at the outer edge of a zone projecting from the back plate, the peripheral recess limiting the movement of the protuberance between two abutments wherein when the protuberance abuts either of the abutments the tensioning roller axially overlaps at least one of the back plate mounting transcurrent openings located in the back plate, the peripheral recess being configured for moving the tensioning roller prior to fixing the axis (X4) for normal operation of the tensioning device, wherein the tensioning device is free of springs.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A power tool, comprising:
an active portion driven by a motor;
a pawl disposed proximate to the active portion and pivotally coupled at a first end to a frame member of the power tool;
a biasing member engaged with the pawl and operating to urge the pawl into engagement with the active portion;
a release mechanism selectively coupled between the pawl and the frame member, wherein the pawl is disengaged from the active portion when the release mechanism is coupled to the pawl and the pawl is biased by the biasing member into engagement with the active portion when the release member is uncoupled from the pawl;
a transmitter capacitively coupled to the active portion and operable to transmit an electrical signal to the active portion;
a receiver capacitively coupled to the active portion and operable to receive the electrical signal transmitted to the active portion;
a controller connected to the receiver and the release mechanism, the controller operable to detect a variation in the electrical signal and send an activation signal to the release mechanism when the variation in the electrical signal exceeds a threshold value, where the release mechanism uncouples the pawl in response to the activation signals and the controller adjusts the threshold value in accordance with parasitic capacitance present at the active portion during motion of the active portion.
2. The power tool of claim 1 wherein the biasing member is further defined as a spring.
3. The power tool of claim 1 wherein the release mechanism is further defined as a fuse.
4. The power tool of claim 1 wherein release mechanism includes a wire coupled at one end to the pawl and the other end to the frame member.
5. The power tool of claim 1 wherein the controller adjusts the threshold value in accordance with a drive signal of the transmitter.
6. The power tool of claim 5 wherein the controller increases the threshold value when the parasitic capacitance increases.
7. The power tool of claim 5 wherein the controller decreases the threshold value when the parasitic capacitance decreases.
8. A power tool, comprising:
a frame structure;
a blade mounted on a spindle that is supported by the frame structure;
a drive motor mounted to the frame structure and configured to drive the spindle;
a pawl disposed proximate to the blade and pivotally coupled at a first end to a frame structure;
a biasing member engaged with the pawl and operating to urge the pawl into engagement with the blade;
a release mechanism selectively coupled between the pawl and the frame structure, the pawl being disengaged from the blade when the release mechanism is coupled to the pawl and the pawl is biased by the biasing member into engagement with the blade when the release member is uncoupled from the pawl;
a transmitter capacitively coupled to the blade and operable to transmit an electrical signal to the blade;
a receiver capacitively coupled to the blade and operable to receive the electrical signal transmitted to the blade;
a controller connected to the receiver and the release mechanism, the controller operable to detect a variation in the electrical signal and send an activation signal to the release mechanism when the variation in the electrical signal exceeds a threshold value, where the release mechanism uncouples from the pawl in response to the activation signals and the controller adjusts the threshold value according to parasitic capacitance present at the blade while the blade is being driven.
9. The power tool of claim 8 wherein the release mechanism is further defined as a fuse.
10. The power tool of claim 8 wherein release mechanism includes a wire coupled at one end to the pawl and the other end to the frame structure.
11. The power tool of claim 8 wherein release mechanism includes a wire arranged in a loop around a portion of the pawl, the wire having a first end and a second end coupled to the frame structure.
12. The power tool of claim 8 wherein the controller adjusts a magnitude of the electrical signal transmitted by the transmitter in order to maintain signal strength of the electrical signal received by the receiver and adjusts the threshold value in accordance with the magnitude of the electrical signal transmitted by the transmitter.
13. The power tool of claim 12 wherein the controller increases the threshold value when the parasitic capacitance increases.
14. The power tool of claim 12 wherein the controller decreases the threshold value when the parasitic capacitance decreases.
15. A table saw comprising:
a frame structure with a generally flat work surface;
a blade mounted on a spindle and being adapted to have at least a portion of the blade extending above the work surface;
a drive motor mounted to the frame structure and configured to drive the spindle;
a pawl disposed proximate to the blade;
a biasing member engaged with the pawl and operating to urge the pawl into engagement with the blade;
a release mechanism selectively coupled between the pawl and the frame structure, the pawl being disengaged from the blade when the release mechanism is coupled to the pawl and the pawl is biased by the biasing member into engagement with the blade when the release member is uncoupled from the pawl;
a transmitter capacitively coupled to the blade and operable to transmit an electrical signal to the blade;
a receiver capacitively coupled to the blade and operable to receive said electrical signal transmitted to the blade; and
a controller connected to said receiver, said controller operable to detect a variation in said electrical signal and send an activation signal to a braking mechanism when said variation in said electrical signal exceeds a threshold value, where the release mechanism uncouples from the pawl in response to the activation signals and said controller adjusts said threshold value according to parasitic capacitance present at the blade while the blade is being driven.
16. The power tool of claim 15 wherein the release mechanism is further defined as a fuse.
17. The power tool of claim 15 wherein release mechanism includes a wire coupled at one end to the pawl and the other end to the frame structure.
18. The power tool of claim 15 wherein release mechanism includes a wire arranged in a loop around a portion of the pawl, the wire having a first end and a second end coupled to the frame structure.
19. The power tool of claim 15 wherein the controller adjusts a magnitude of the electrical signal transmitted by the transmitter in order to maintain signal strength of the electrical signal received by the receiver and adjusts the threshold value in accordance with the magnitude of the electrical signal transmitted by the transmitter.
20. The power tool of claim 19 wherein the controller increases the threshold value when the parasitic capacitance increases.
21. The power tool of claim 19 wherein the controller decreases the threshold value when the parasitic capacitance decreases.