MX2008007712A - Motor brake - Google Patents

Abstract

A brake assembly (36) is configured for a strapping tool tensioning motor having a housing and an output shaft (30) operably connected to a tensioning wheel. The brake assembly (36) includes a one-way bearing (34) operably connected to the motor output shaft (30) to permit the shaft to rotate relative to the bearing in the first direction and to stop rotation of the shaft relative to the bearing in the reverse direction. The bearing has at least two stop members (38) thereon. When the brake is engaged with the one of the bearing stop members, the motor can freely rotate in the first direction and cannot rotate in the second reverse direction. The brake release moves the brake element out of engagement with the one of the bearing stop members and the motor can freely rotate in the second reverse direction until the brake release is reengaged with one of the bearing stop members.

Description

ENGINE BRAKE FIELD OF THE INVENTION The present invention pertains to improved brake and unlocking for a strapping tool. More particularly, the present invention is directed to a unidirectional clutch brake and release for a motor-driven strapping tool.

BACKGROUND OF THE INVENTION Strapping tools are well known in the art. These tools come in a wide variety of types, from fully manual to automatic tools, shelf tools. These tools are usually designed specifically for use with a metal or plastic / polymer type strap. A strapping machine for applying polymeric or strapping plastic materials is driven to provide power to tension the strap and adhere the strapping material thereon. A typical strapping tool includes a body, one or more motors, a base (on which the load rests), a tension wheel, a vibrating or sealing element and, typically, a pneumatic module to channel the air and provide control of the tool. When using the tool, the first and second layers of strapping material are passed over the base of the tool, between the base and the tension wheel. The strap is tensioned by rotation of the wheel. As the strap is tightened, it is also tightened on the base of the tool, holding the base to the load. The strip is sealed to itself same (by welding) and the free end of the strip is cut. Although this in fact straightens the load, this also retains the tool (at the base) sealed to the load. To allow the tool to be removed from the load, many tools are configured to allow the tension wheel to retract, a small amount. This keeps the strap in tension, but releases only enough tension to allow the base of the tool to be pulled between the strap and the load. Several arrangements are known to allow a slight amount of recoil. For example, it is known that pneumatic systems use a delay in the pneumatic circuit that allows a slight recoil after tensioning. Other strapping tools use a complex gear arrangement to allow recoil. Accordingly, there is a need for a simplified arrangement of motor brake and unlocking providing recoil in a strapping tool.

Desirably, said arrangement eliminates the need for tires to provide recoil. More desirably, said braking and unlocking arrangement provides a positive brake against excessive recoil.

BRIEF DESCRIPTION OF THE INVENTION A brake assembly is configured to be used with a tensioning motor for a strapping tool. The motor has a housing and a motor shaft operably connected to a tension wheel. The tension wheel rotates in a first direction to tension the strap and a second reverse direction to release the tension in the strap. The release of tension is required to be able to remove the tool from the load that is strapped. However, loose or recoil must be controlled to prevent a lack of excessive strap tension. The brake assembly includes a unidirectional support operably connected to the motor's motor shaft. The support allows the shaft to rotate with respect to the support in the first direction and prevents rotation of the shaft with respect to the support in the reverse direction. The support has at least two (and preferably two) stop members therein. A brake element is operatively mounted to the motor housing and is capable of moving toward and away from the support for movement in and out of engagement with one of the stop members of the support. The brake element stops the reverse rotation of the motor shaft and the support when the brake element is coupled with one of the stop members of the support. A brake release is operatively connected to the brake element to move the brake element in and out of engagement with the stop member of the support. A guiding element predisposes the brake element towards the coupling with the stop member of the support. When the brake is coupled with the support stop member, the motor can rotate freely in the first direction (to tighten the strap) but can not rotate in the second reverse direction. When the brake release moves the brake element out of engagement with the stop member of the support, the motor (and support) can rotate freely in the reverse direction to loosen the strap slightly, until the brake release is re-engaged with one of the top members of the support. In the current brake assembly, the support includes a continuous circumference formed therein and includes outwardly extending projections that form the stop members. A preferred support includes two stop members. The brake release is pivotally mounted to the motor housing by a pivot. A finger release is separated from the pivot and the brake element is operatively connected to the brake release between the finger release and the pivot. In a current assembly, a cam operatively connects the brake release and the brake element. The cam is configured to translate the movement of the brake release towards an opposite movement of the brake element. In one embodiment, the cam includes a central disk portion and a pair of pins extending outward from the opposing side surfaces of the disk. The pins are disposed approximately 180 degrees one from the other. The brake release and the brake element each includes a slot for receiving their respective pins. The brake release is predisposed to keep the brake element in the engaged position. The orienting element is arranged between the pivot and the nail release, and more particularly, between the nail release and the cam. A strapping motor is also disclosed. These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS The benefits and advantages of the present invention will be more apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and the accompanying drawings in which: Figure 1 is a perspective view of an exemplary strapping tool having an engine brake that incorporates the principles of this invention; Figure 2 is a side view of the strapping machine; Figure 3 is a side view of the strapping motor of the strapping machine; Figure 4 is a cross-sectional view taken along line 4-4 of Figure 3; Figure 5 is a cross-sectional view of the engine; Figure 6 is a sectional view illustrating the brake release; Figure 7 is a perspective view of the engine showing the release; Figure 8 is a view showing the separated parts of the brake release, the cam and the plunger; Figure 9 is a front view of the support; Figure 10 is a perspective illustration of the frame of the support cable; Figure 11 is a top view of the support; and Figures 12A and 12B are side and front views of the cam.

DETAILED DESCRIPTION OF THE INVENTION Although the present invention is susceptible to being incorporated in various forms, it is shown in the drawings and will now be described as a presently preferred embodiment with the understanding that the present disclosure will be considered an example of the invention and is not intended of limiting the invention to the specific embodiment illustrated. Furthermore, it should be understood that the title of this section of this specification, mainly, "Detailed Description of the Invention", refers to the requirement of the United States Patent Office, and does not imply, nor should it interfere with, the imitation of the matter disclosed herein. Referring now to the figures and in particular to Figure 1, there is shown an exemplary pneumatic motor strapping tool or strapping tool 10 having an engine brake 12 incorporating the principles of the present invention. The tool 10 is configured to tension a strap S around a load L, weld the strapping material S on itself and serve a supply end F of the strap S. For purposes of the present disclosure, the strapping material S will be referred to have a supply end F which is the supply end of the material and a free end D which is that end of the material that is supplied around the load L and reinserted towards the strapping tool 10. The tool 10 generally includes a body 14, a base 16, a tensioner motor 18, a welding motor 20, a housing 22 and a tire module 24. The tire module 24 is mounted in the housing 22 which is mounted to the body 14 and provides pneumatic paths between the module 24, the housing 22 and the welding and voltage motors 18, 20, for introducing and venting the compressed gas, such as compressed air, to and from the motors 18, 20. An exemplary tool is disclosed in Nix, US Patent No. 6,907,717, whose patent is commonly assigned with the current application and is incorporated herein by reference. The tensioner motor 18 is pneumatically driven and drives a tension wheel 26. It will be appreciated that the power output of the motor per tire 18 is slow, while the force required for the tension of the strip S is relatively high. As a consequence, the pulse or transmission 28 (operatively connects the motor 18 to the wheel 26) which is in a relatively high gear ratio, in the order of 20:01 to 30:01. Thus, the motor shaft 30 of the motor 18 rotates at a relatively high speed, but with a low power, and transmission 28 moves the high speed / low power output on the 30 axis to high power / / low speed on the tension wheel 26. When using the tool 10, the first and second course F, D of the material of the strip S is passed above the base 16 of the tool 10 between the base 16 and the tension wheel 26. The strip S is tensioned by the activation of the tensioner motor 18 which rotates the tension wheel 26. As the strap S is tensioned, it is also tightened on the base 16, holding the base 16 of the load L. The strip S is sealed as well (by welding) and the free end F of the strip S is cut. Although this in fact straightens the load L, it also retains the tool 10 (in the base 16) tightly held to the load L. As previously stipulated, the previously known straps use a pneumatic system and / or a complex gear arrangement for allow recoil It will be appreciated that the amount of backward turns must be controlled such that the S strap does not loosen too much. Accordingly, the current brake assembly 12 includes a unidirectional support 34 which is mounted to the motor shaft of the motor 30 and a cooperating brake assembly 36. The bracket 34 and the brake assembly 36 allow the motor shaft 30 to freely rotate with with respect to the support in one direction (forward), the direction of tension, but prevents rotation (backwards) in an opposite direction. The support 34 includes at least one and preferably a pair of stops 38 generally oriented radially outwards. The stops 38 extend outwardly from the circumferential edge 40 in the support 34 in the caliber 42 through which the shaft 30 extends. In a present support 34 and brake assembly 36, the support 34 is formed as a collar with a circumferential channel 44 formed therein. The stops 38 are formed as wall portions extending towards the channel 44. The stops 38 are generally formed radially, oriented slightly in shape tangential, as will be described later (see figure 9). The assembly 36 includes a plunger 46 which is fitted in an opening 48 in the motor housing 50. The plunger 46 is configured to move in and out (towards and away from the support 34) along the line A46 projecting through of the central axis A18 of the motor 18 and the shaft 30. A finger 52 at the end of the piston 46 moves towards the channel 44 to engage one of the stops 38 and to disengage from the stop 38. The plunger 46 is predisposed to the coupled position by a spring 54. When the plunger 46 is in the coupling position it contacts the stop 38 to prevent the motor 18 from rotating in the reverse direction. Plunger 46 includes a slot 56 formed therein. A manual lever releasing the brake 58 is mounted in the motor housing 50. The brake lever 58 includes a body 60 which is received in the housing 58. The body 60 is mounted in the housing 50 in a pivot 62. The releaser the finger 64 is mounted on the body 50 separated from the pivot 62 to secure or move the lever 58. An elongated slot 66 is formed in the body 60 between the finger release 64 and the pivot 62. A cam 68 is mounted between the release of finger 64 and plunger 46. Cam 68 has a disc-like, round body 70 with pins 72, 74 extending from disk 70, on opposite sides thereof. The pins 72, 74 are mounted approximately 180 degrees one from the other. One of the pins 72 is received in the slot 66 of the body of the lever of the brake release and the other pin 74 is received in the slot of the piston 56. The arrangement of the slot of the lever / cam / groove of the plunger (66) / 68/56) serves to translate the downward movement of the support 64 of the projection with released lever to an upward movement of the plunger 46. That is, because the pins 72, 74 are located 180 degrees from others, as spike 72 with liberating lever that is driven inward by pressing the support 64, it rotates the central disc 70, which in turn rotates the pin 74 of the plunger upwardly (or outwardly) to move the projection 54 of the plunger out of engagement with the stopper support 38. The elongated slots 66, 56 in the body 60 of the lever and the plunger 46 allow movement without holding it between the pins 72, 74 and their respective openings 66, 56. This allows the support 34 and the motor 18 turn in the rear direction. As can be seen from FIGS. 4 and 9, when the plunger 46 is engaged with the stop bracket 38, the finger 52 contacts the stop 38 to prevent the return of the support 34 and the motor 18. The location and orientation of the stops 38 are the nail 52 resting against the surface of the stop 38, instead of contacting only the stop 38. In addition, as seen in figure 10, the wall (as indicated in point 39) that defines the stop 38 is round (together with the finger 52), again, to maintain a relatively large contact area to facilitate easy disengagement of the finger 52 from the stop 38 In use, as the tool 10 is in the mode of tension, the motor 18 rotates clockwise (as seen in Figure 4), the plunger 46 is in the engaged position, but the motor shaft 30 rotates freely with respect to the support 34 of a single address. However, the holder 34 can rotate clockwise with the shaft 30 until the back side of the stop 38 contacts the finger 52. When the motor 18 is stopped (that is, when the air towards the motor 18 is isolated), the tension in the strap S pulls the tension wheel 26 in the reverse direction. Since the motor 18 and the tension wheel 26 are connected to each other (through a gear or transmission group 28), the motor 18 will begin to rotate backwards or counterclockwise (in FIG. 4) , until the stop 38 support hits or engage the finger 52. This will stop the return of the tension wheel 26 and the motor 18. With the finger 52 engaged with the stop 38, the tension in the strap S is too great to remove the tool 10 from the load L In order to "release" the tool 10 to the tension wheel 26 it should be allowed to slightly rotate backwards or slightly reduce the tension in the strap S. However, it will be appreciated that too much recoil is not desired in that excessive loosening that It may result. By depressing the nail release 64 the protrusion of the plunger 52 moves outward to release the brake 36. The tension in the strap S pulls the tensioning wheel 26 rearwardly because the plunger 46 is out of engagement with the stop brake 38. Since the brake assembly 36 is predisposed, the projection 64 is released allowing the plunger 46 to reattach to the stop brake 38 and stop the wheel 26 from rotating backward. Although the release of the brake 36 may result in 1/2 rotation (eg, a 180 degree rotation) of the motor 18 (until the opposite stop 38 engages the finger 52), since the ratio of change of the motor 18 and the tension wheel 26 (from about 20: 1 to 30: 1), that rotation of the motor 18 results in approximately 1/50 rotation of the tension wheel 26. Thus, excessive loosening of the strap does not occur. In order to free the tool 10 from the strapping S tensioned in the load L, the tensioning wheel 26 must allow the subsequent retraction to form the welding of the strap. The tension is maintained during the welding and the recoil is then allowed, following the welding, to allow the removal of the tool 10 from the load L. The current brake system 12 allows this recoil without an excessive loosening in the strap S , in an arrangement that eliminates complex gear and / or tire systems.

All of the patents referred to herein, are hereby incorporated herein by reference, specify or not what they do within the text of this disclosure. In the current disclosure, the words "a" or "an" are taken to include both the singular and the plural. Conversely, any reference to plural articles should, when appropriate, include the singular. From the foregoing it will be noted that numerous modifications and variations can be made without departing from the true spirit and scope of the new concepts of the present invention. It should be understood that no limitations with respect to the specific embodiments illustrated are intended or should be inferred. The disclosure is intended to cover all those modifications that fall within the scope of the claims through the appended claims.

Claims (9)

1. A brake assembly for a tensioning motor for a strapping tool, the motor having a housing and having a drive shaft operably connected to a tension wheel, the tension wheel rotating in a first direction to tension a strap and in a second reverse direction to release the tension in the strip, the brake assembly comprising: an operable unidirectional support connected to the motor shaft of the motor to allow the shaft to rotate with respect to the support in the first direction and stop rotation of the shaft with respect to the support in reverse direction , the support having at least two stop members therein; a brake element operably mounted to the motor capable of moving towards and away from the support for movement toward and away from the coupling with one of the stop members of the support, the brake element stopping the rotation of the motor shaft and the support when the The brake element is coupled with one of the stop members of the support; a brake release operably connected to the brake element to move the brake element and out of engagement with one of the stop members of the support; an orienting element for predisposing the brake element towards the coupling with one of the stop members of the support, characterized in that when the brake is coupled with one of the stop members of the support, the motor can freely rotate in the first direction and not it can rotate in the second reverse direction, and when the brake release moves the brake element out of engagement with one of the stop members of the support, the motor it can freely rotate in the second reverse direction until the brake release is reengaged with one of the stop members of the support. The brake assembly according to claim 1, further characterized in that the brake release is pivotally mounted to the motor housing by means of a pivot. The brake assembly according to claim 2, further characterized in that the brake release includes a finger release detached from the pivot and wherein the brake element is operably connected to the brake release between the finger release and the pivot . The brake assembly according to claim 1, further characterized in that it includes a cam operatively connecting the brake release and the brake element, the cam configured to translate the movement of the brake release towards an opposite movement of the element. brake. The brake assembly according to claim 4, further characterized in that the cam includes a central disc portion and a pair of pins extending outward from the opposing side surfaces of the disc, the pins disposed at 180 degrees one of the other, and wherein the brake release and brake element each includes a slot for receiving their respective pins. 6. The brake release according to claim 3, further characterized in that the orienting element is positioned between the pivot and the nail release. 7. The brake release according to claim 5, further characterized in that the orienting element is positioned between the nail release and the cam. 8. The brake release in accordance with claim 1, further characterized in that the support includes a continuous circumference formed therein and includes projections extending outwardly forming the stop members of the support, the brake element making contact with the stop members of the support to prevent rotation of the motor shaft in the reverse direction. 9. The brake release according to claim 8, includes two stop support members.