The present invention relates to a extremely sturdy and versatile torque limiting device adapted to be used in conjunction with any type of driver tool utilized for the rotational tightening of mechanical fasteners. More particularly, to an accurate torque limiting device designed to be used in a production environment where the driver it is matingly coupled to is operated pneumatically, hydraulicly or electrically at a high speed.
The proper operation of many mechanical components is, to a large degree, dictated by how the parts are assembled. Over tightening of mechanical fasteners can lead to cracked bodies, stretched and weakened bolts, stripped threads, smaller clearance tolerances, and a plethora of other maladies that can seriously affect the operation of the item in question. Similarly, under tightening of mechanical fasteners can have its own, different but potentially disastrous results. For this reason, where the tightness of a mechanical fastener is critical to the overall operation of the item, torque values are experimentally determined and assigned to the individual mechanical fasteners.
Conventional torque limiting devices are separate from the high speed production drivers used to tighten the fastener, and must be interchanged periodically as the desired torque value is approached. This slows the assembly process as conventional torque limiting devices require time to operate. Further, many of the conventional torque limiting devices (such as a torque wrench) indicate the torque level yet do not prevent that level from being exceeded.
The present device is an adjustable torque limiter that can be connected between a high speed driver and the bit that couples to and rotates the mechanical fastener. When the preset torque level is reached, the torque limiter goes into a free wheel mode therein disengaging the rotational drive force from the bit. In this mode the high speed driver may continue to rotate but the bit will remain stationary.
The adjustability of the torque limitation is accomplished by varying the amount of spring force by which a thrust disk (coupled to the high speed driver) frictionally rotates an upper torque body (coupled to the bit) through a intervening set of steel balls that are frictionally captured in an arced (or straight) depression formed in the underside of the upper torque body. When a certain preset torque limit that is being transmitted from the driver to the bit is exceeded, the upper torque body's rotation is retarded with respect to the lower torque body's rotation and the steel balls traverse downward and outwardly along separate arced and rearward ramped radial slots formed thereon a radial torque plate extending normally from the lower torque body, gradually depressing the spring and separating the radial torque plate of the lower thrust body from the thrust disc until the balls exit the distal end of their respective radial paths and enter the outer race of the upper torque body, wherein the bit and upper torque body go into a disengaged or free wheel mode. The unit is reset by a counter rotation of lower torque body with respect to the upper torque body so that the set of balls return to the proximate end of their radial paths in the radial torque plate.
Simply stated, the present torque limiter overcomes all of the stated deficiencies of the traditional prior art through the use of an adjustable force coupling system between the drive and driven ends of the unit. Henceforth, the present invention would fulfill a long felt need in the fabrication industry. This new invention utilizes and combines known and new technologies in a unique and novel configuration to overcome the aforementioned problems therein reducing assembly time and preventing unnecessary damage.
The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a torque limiter that is able to overcome the problems of the prior art and provide a failsafe method of quickly tightening mechanical fasteners in a production environment to a specified torque value.
It has many of the advantages mentioned heretofore and many novel features that result in a new and improved torque limiter which is not anticipated, rendered obvious, suggested, or even implied by any of the prior art, either alone or in any combination thereof.
In accordance with the invention, an object of the present invention is to provide an improved adjustable torque limiter capable of use with a plethora of high speed drivers.
It is another object of this invention to provide an improved torque limiter capable of connection between a conventional mechanical driver and a conventional mechanical fastener bit.
It is a further object of this invention to provide an improved torque limiter capable of eliminating torque in excess of a desired preset value from being transmitted from a driver to the driven mechanical fastener.
It is still a further object of this invention to provide for an improved torque limiter capable of simple calibration.
It is yet a further object of this invention to provide an inexpensive torque limiter capable of accurate adjustment.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. Other objects, features and aspects of the present invention are discussed in greater detail below.
a is a front view of the rear housing;
b is a side phantom view of the rear housing;
c is a rear view of the rear housing;
a is a front view of the rear bearing race ring;
b is a side cross sectional view of the rear bearing race ring;
c is a side phantom view of the rear bearing race ring;
d is a rear view of the rear bearing race ring;
a is a front view of the torque adjuster plate;
b is a side view of the torque adjuster plate;
c is a top view of the torque adjuster plate;
d is a side cross sectional view of the torque adjuster plate;
e is a rear view of the torque adjuster plate;
a is a front view of the rear spring compression disk;
b is a side view of the rear spring compression disk;
c is a rear view of the rear spring compression disk;
a is a front view of the compression spring;
b is a side view of the compression spring;
c is a rear view of the compression spring;
a is a front view of the front spring compression disk;
b is a side view of the front spring compression disk;
c is a rear view of the front spring compression disk;
a is a front view of the wear disk;
b is a side view of the wear disk;
c is a rear view of the wear disk;
a is a front view of ring bearing;
b is a side view of the ring bearing;
c is a rear view of the ring bearing;
a is a front view of the trust disk;
b is a side view of the trust disk;
c is a rear view of the trust disk;
a is a top view of the lower torque body;
b is a front view of the lower torque body;
c is a side view of the lower torque body;
d is a rear view of the lower torque body;
a is a top view of the upper torque body;
b is a front view of the upper torque body;
c is a side view of the upper torque body;
d is a rear view of the upper torque body;
a is a front view of the front housing;
b is a side cross sectional view of the front housing;
a is a front view of the front bearing race ring;
b is a side view of the front bearing race ring; and
c is a rear view of the front bearing race ring.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.
There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.
In the most basic description, the torque limiter 2 is an encapsulated torque decoupling mechanism that has an upper driven body and a lower drive body coupled for unitary rotation by the frictional engagement of a set of balls residing partially in radial paths formed in a concavity of the upper driven body and partially in ramped and arced radial slots formed on a radial torque plate on the lower thrust body. The amount of friction or drag exerted by the balls (and thus the coupling force between the upper driven body and a lower drive body) is altered by adjusting the compression force that a fixed spring exerts via a thrust disk onto the balls. The adjustment of the spring and the rotation of the bodies within the encapsulation requires five sets of bearings and a plethora of structural elements. This friction or drag determines the amount of torque required to break apart the unitary rotation of the two bodies. Once this torque is exceed there is slippage between the upper and lower torque bodies forcing the balls to move downward and outward along their ramped and arced radial paths and into an outer race compressing the spring and allowing the balls to rotate around a stationary upper torque body. When this occurs the drive body is free to rotate uncoupled from the driven body. To accomplish unitary rotation again, the drive body rotation must stop and the drive body rotated slightly in a reverse rotation to reset the position of the set of balls in their paths.
A detailed explanation of the improved torque limiter 2 as well as the functionality and structure of all its components can best be seen by looking at
Looking at
Additionally, three or more adjuster balls 44 (and optionally a locking pin) are secured in the rear spring location compression disk 10. The torque adjuster plate 8 has a ring of equidistantly spaced detents 46 that matingly conform to the adjuster balls 44. When the torque adjuster plate 8 is rotationally engaged with the threaded end of the lower torque body 22 so as to advance, the rear spring location compression disk 10 is also forced to advance up the threaded end of the lower torque body 22. Since the rear spring location compression disk 10 has two internal tabs 48 that engage the two longitudinal broachways 50 cut along the threaded portion of the lower torque body 22, the rear spring location compression disk 10 does not rotate relative to the lower torque body 22. This allows the compression of the spring 12 without any twisting that would distort the compression profile of the spring 12, and make the precise linear torque threshold indication impossible. The adjuster balls 44 reduce the friction between the torque adjuster plate 8 and the rear spring location compression disk 10 when the torque is being adjusted, and lock into the ring of equidistantly spaced detents 46 to prevent separation between the torque adjuster plate 8 and the rear spring location compression disk 10 when the torque adjuster plate 8 has been sufficiently advanced along the threaded end of the lower torque body 22. It is also known that in an alternate embodiment not illustrated, a more positive engagement between the torque adjuster plate 8 and the rear spring location compression disk 10 could be accomplished through the use of a set or dog screw advancing through a threaded recess in the torque adjuster plate 8 so as to partially engage a matingly sized detent in the rear spring location compression disk 10. This would serve to lock the torque adjuster plate 8 to the rear spring location compression disk 10 therein preventing any unwanted decompression of the spring 12 once the limiting torque has been set.
Since the various components of the torque limiter 2 are held together by balls, there are specific ways to get the balls into their desired locations. Although the thrust balls 24 may be manually inserted during assembly, and the adjuster balls 44 are permanently affixed into the rear spring location compression disk 10, all other balls require insertion through partially threaded externally accessible passages that then are sealed by set screws or equivalent methods.
The lower housing balls 40 are inserted through first passage 52 (
The two sets of stabilizer balls 42 are inserted through second passage 58 and third passage 60 (
The upper housing balls 36 are inserted through fourth passage 62 (
Looking at
a-c shows the rear cylindrical housing 4 wherein it can be seen that the stepped cylindrical configuration having a smaller diameter proximate end 72 and a larger diameter distal end 74 accommodates and constrains the lower outer race ring 6. The lower outer race ring 6 has a circumferential groove 76 formed thereon to accept the lower housing balls 40 (
The torque adjuster plate 8 is an disk that is internally threaded so as to matingly engage the threaded end of the lower torque body 22. There are two tool recesses 82 formed therein the distal face for the insertion of a pronged tool to rotate the torque adjuster plate 8. There is also a first passage 52 to allow the lower housing balls 40 to be installed. On the proximate face there is a circular series of equidistant detents 46 formed to jointly receive the equidistantly spaced adjuster balls 44 which are pressed into accommodating recesses (not illustrated) in the rear spring location compression disk 10 (
To ensure that the spring 12 when compressed will not twist and adjust its linear spring coefficient, the rear spring location compression disk 10 has two internal tabs 48 that lock the rear spring location compression disk 10 to the lower torque body 22, preventing rotation relative to the lower torque body 22.
The spring 12 illustrated in
The front spring location compression disk 14 (
Looking at
The lower torque body 22 has a threaded distal end with two longitudinal broachways 50 cut along the threaded end. A radial torque plate 29 extends normally therefrom a forward section of the lower torque body. Into the torque plate 29 are ramped and counter clockwise arced radial slots 28 formed therethrough sized to slidingly accommodate thrust balls 24. The torque plate distal face 86 is planar while the torque plate proximate face 88 is ramped. The ramp thickness of the torque plate 29 increases toward the center. The proximate end of the lower torque body 22 has two parallel and adjacent stabilizer grooves 90 that act as inner races for sets of stabilizer balls 42. (
Referring now to
a and b shows the front cylindrical housing 32 wherein it can be seen that the proximate end has a front bearing race recess 100 to accommodate and constrain the front bearing race 34. The front bearing race 34 has a circumferential groove 102 formed thereon to accept the upper housing balls 36. (
It is important to note that the upper torque body's radial paths 94 are arced in the opposite direction from the radial slots 28 formed in the radial torque plate 29 of the lower torque body 22. It is this clockwise-counterclockwise arced relationship that forces the thrust balls 24 into their outer position when the upper torque body 30 and the lower torque body 22 are decoupled (no longer frictionally engaged). Conversely, when the innermost segments of the radial slots 28 and radial paths 94 are aligned, the thrust balls 24 are constrained in their center most location and frictional engagement is achieved.
The operation of the torque limiter 2 is best understood looking at looking at
When the limiting torque is reached, the application of more torque exceeds this frictional engagement and causes slippage between the upper torque body 30 and the lower torque body 22. With the rotation of the upper torque body 30 retarded (
To reset the torque limiter 2 requires an advancement of the upper torque body 32 by approximately 60 degrees relative to the position of the radial torque plate 30 so that thrust balls 24 can be forced back along the radial slots 28 until the thrust balls 24 are returned to the centermost position of the radial paths 94. Since the lower torque body 22 is separated from the rear cylindrical housing 4 by lower housing balls 40, and since the upper torque body 30 is separated from the front cylindrical housing 32 by the upper housing balls 36, the device's outer housing is rotationally independent and may be held by the operator's hand while the torque limiter is operated.
The above description will enable any person skilled in the art to make and use this invention. It also sets forth the best modes for carrying out this invention. There are numerous variations and modifications thereof that will also remain readily apparent to others skilled in the art, now that the general principles of the present invention have been disclosed. For example the number and shapes of the radial slots 28 and the radial paths 94 as well as their clockwise and counterclockwise arc directions. It is also known that the arced depressions formed in the upper housing may be straight depressions as it is the arc in the torque plate that forces the thrust balls into the decoupled position. It is also known that more than one spring may be used. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Number | Name | Date | Kind |
---|---|---|---|
4712456 | Yuan | Dec 1987 | A |
7150212 | Lee | Dec 2006 | B2 |
7467576 | Gao | Dec 2008 | B2 |
Number | Date | Country | |
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20110000347 A1 | Jan 2011 | US |