The present invention relates to a torque wrench and, more particularly, to a torque wrench capable of tightening threaded assemblies to precise torque levels and which is compact. Furthermore, the torque wrench has an adjustable biasing mechanism for biasing a movable member to effect adjustment of torque applied to the threaded assemblies.
Microwave and radio frequency (RF) equipment utilize threaded connectors which are manufactured to tight tolerances in order to provide precise connection of electrical components and cables. This is necessary to ensure that the electrical connection does not adversely affect electrical signals traveling through the connection by causing reflections resulting in a voltage standing wave ratio (VSWR) which is greater than specifications permit. In order to ensure a proper connection it is often necessary to tighten mating connectors to a precise torque value. This torque setting prevents damage to the components and allows repeatable measurements.
A process for a typical attachment of a device to equipment, in particular test equipment, requires that an operator hand-tighten a connector nut until the last quarter turn and then use a standard open-end torque wrench to precisely tighten the connector nut to a required torque value. After a measurement is made, the connector nut is then loosened with a open-end fixed wrench until the device is free. Typical torque settings are 5,8 and 12 lb-in.
Accordingly, it is an object of the invention to provide a torque device which overcomes the drawbacks of the prior art by providing a compact design while permitting accurate adjustment of torque and minimizing parts and assembly and manufacturing requirements.
Briefly stated a torque device of the present invention includes a housing rotatably accepting an inner ring assembly having a pin eccentrically disposed relative to a torque axis. A movable member is slidably or pivotably disposed in the housing to come into and out of engagement with the pin when the inner ring assembly rotates relative the housing. The movable member has a slanted face for engaging the pin. The pin and the slanted face are alternatively interchanged in positions on the inner ring assembly and movable member. An adjustable biasing device biases the movable member. The biasing device includes a split ring spring and a ring segment spring. Alternatively, the biasing device includes a compression spring.
In accordance with these and other objects of the invention, there is provided a housing, and an inner ring assembly defining a torque axis upon which torque is to be applied, the inner ring assembly including at least one pin eccentrically disposed relative to the torque axis and an engaging structure coaxially disposed relative the torque axis for engaging a rotatable member to be tightened. The housing rotatably accepts the inner ring assembly to permit rotation about the torque axis. A movable member is disposed in the housing to move along a travel path to come into and out of engagement with the at least one pin when the inner ring assembly rotates relative to the housing to rotate the at least one pin along a circumferential path of travel about the torque axis and relative to the housing. The movable member has a slanted face slanted relative to a tangent to an intersection of the circumferential path of travel of the at least one pin and a center line of the movable member in a moving direction thereof such that continued rotation in a first direction of the inner ring assembly, relative to the housing, engages the slanted face with the at least one pin and urges the movable member outward relative to the torque axis to a disengagement point where the at least one pin moves out of engagement with the slanted face. An adjustable biasing device is provided for biasing the movable member toward the at least one pin such that the inner ring assembly applies a predetermined level of torque to the rotatable member at the point of disengagement.
According to a feature of the invention, there is further provided an embodiment wherein the movable member is a sliding member slidably disposed in the housing. Alternatively, the movable member may be embodied as a pivoting member pivotally disposed in the housing.
According to a further feature of the invention, there is further provided in the above embodiment a configuration wherein the adjustable biasing device includes a split ring spring, the housing defines a slide notch for slidably accepting the sliding member, and the housing further defines a circumferential opening accepting the split ring spring such that the split ring spring is disposed around the inner ring assembly and an inner circumference of the split ring spring engages a sliding member end of the sliding member, opposing the slanted face, to apply bias to the sliding member to engage the at least one pin with the slanted face.
There is still further provided the feature that the split ring spring is integral with the sliding member in any of the embodiments recited herein including the split ring spring.
A further feature of the invention includes the biasing device described above having a ring segment spring having first and second ends, the ring segment spring being disposed in the circumferential opening radially outside of the split ring spring with the first and second ends engaging an outer circumference of the split ring spring at first and second points, and the biasing device further including a threaded member threaded into the housing and disposed to adjustably apply pressure to the ring segment spring such that the first and second ends of the ring segment spring apply adjustable pressure to the first and second points on the outer circumference of the split ring spring.
Yet another feature of the present invention includes the at least one pin being rotatably disposed in the inner ring assembly and the inner ring assembly including a plurality of the rotatable pins.
In yet another embodiment of the present invention the torque device includes the housing defining a slide notch for slidably accepting the movable member, the movable member being a sliding member slidably disposed in the slide notch defined by the housing and the sliding member having a longitudinal slot aligned along a sliding axis of the sliding member, a guide pin disposed in the housing and within the longitudinal slot, and the slide notch being configured to restrict sliding movement of the sliding member to a linear path when rotation of the inner ring assembly is relative to the housing in the first direction and configured to permit rotation of the sliding member about the guide pin by engagement of the at least one pin with the sliding member with rotation of the inner ring assembly in a second direction, opposite the first direction, such that disengagement of the sliding member with the at least one pin is permitted by continued rotation of the inner ring assembly in the second direction thereby effecting ratcheting operation of the inner ring assembly relative to the housing. This embodiment may incorporate any of the biasing arrangements described herein.
Still another feature of the present invention includes the adjustable biasing device including a threaded member and a compression spring with the threaded member disposed to adjustably apply force to the compression spring which in turn applies the bias to the movable member in any of the embodiments of the movable member.
Yet another embodiment of the present invention includes a torque device for applying torque to a rotatable member, having a housing, an inner ring assembly defining a torque axis upon which torque is to be applied, the inner ring assembly including at least one first engaging surface eccentrically disposed relative to the torque axis and an engaging structure coaxially disposed relative the torque axis for engaging and applying torque to a rotatable member, the housing rotatably accepting the inner ring assembly to permit rotation about the torque axis, a movable member disposed in the housing and having a second engaging surface disposed to move along a travel path to come into and out of engagement with the at least one first engaging surface when the inner ring assembly rotates relative the housing to rotate the a least one first engaging surface along a circumferential path of travel about the torque axis and relative to the housing, the first and second engaging surfaces being disposed to effect engagement along a surface path slanted relative to a tangent to an intersection of the circumferential path of travel of the first engaging surface and a center line of the movable member in a moving direction thereof such that continued rotation in a first direction of the inner ring assembly, relative to the housing, engages the second engaging surface with the at least one first engaging surface and urges the movable member outward relative to the torque axis to a disengagement point where the second engaging surface moves out of engagement with the at least one first engaging surface, and an adjustable biasing device for biasing the movable member toward the at least one first engaging surface such that the inner ring assembly applies a predetermined level of torque to the rotatable member at the point of disengagement.
In the above embodiments the movable member is optionally a sliding member slidably disposed in the housing or a pivoting member. Furthermore, the second engaging surface is optionally a surface of a pin rotatably disposed in the sliding member and the at least one first engaging surface is optionally a surface disposed at an incline relative to a radial direction of the inner ring assembly. Alternatively, the movable member is a pivoting member pivotably disposed in the housing optionally incorporating a rotatable pin.
Yet another embodiment of the present invention includes any of the embodiments of the torque device describe above being incorporated into an electrical connector wherein the rotatable member is a nut, or rotating threaded connecting collar, of the electrical connector and the engaging structure of the inner ring assembly is integral with the nut thereby providing an electrical connector with a torque limiting function. In one embodiment the electrical connector is part of a cable assembly. In another embodiment the electrical connector is provided on a piece of electrical equipment, such as a test instrument for example, or an adaptor for female-female, male-male, or male-female connections.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. The present invention is considered to include all functional combinations of the above described features and is not limited to the particular structural embodiments shown in the figures as examples.
a is a rear view of an embodiment of an outer case component of the torque wrench;
b is a side elevation cross-sectional view of the outer case component of the torque wrench of
a is a front view of an embodiment of an inner ring assembly of the torque wrench;
b is a side elevation view of the inner ring assembly of the torque wrench of
c is rear view of the inner ring assembly of the torque wrench of
a is a rear partially cross-sectional view of the torque wrench of
b is a side elevation cross-sectional view of the torque wrench of
a is a top, side and front side perspective view of a slide block of the torque wrench of
b is a top, side and front side perspective view of another embodiment of a slide block of the present invention;
a is a top, side and front side perspective view of a further embodiment of a slide block of the present invention;
b is a top view of the slide block of
c is a front view of the slide block of
d is a side view of the slide block of
a is a rear partial cross-sectional view of another embodiment of the present invention in a first state of operation;
b is a rear partial cross-sectional view of the embodiment of the present invention of
a is a first alternative embodiment of a ring spring of the present invention;
b is a second alternative embodiment of the ring spring of the present invention;
c is a third alternative embodiment of the ring spring of the present invention which incorporates a slide block;
d is a fourth alternative embodiment of the ring spring of the present invention which incorporates a slide block;
a is a top, front and side perspective view of an alternative embodiment of a slide block of the present invention;
b is a front view of a portion of an alternative embodiment of a ring assembly of the present invention for operation in cooperation with the embodiment of the slide block of
a is rear partial cross-sectional view of another embodiment of the present invention having an alternative biasing configuration; and
b is an exploded view of an assembly of the alternative biasing configuration of
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The present invention further includes the torque wrench 30 being integrated with cables to form cable assemblies which may be used for testing or for permanent installation. In such configurations the nut of the cable is permanently affixed in the inner ring assembly 36 either mechanically or is integrally formed in the inner ring assembly. Such cable assemblies provide for enhanced repeatability of testing as the torque wrench 30 is mated with the cable to ensure the cable is always tightened to the same torque. It is also within the scope of the present invention to provide test equipment having the torque wrench 30 integrated into connectors on the equipment itself. Once again, enhance repeatability of testing is facilitated.
The torque wrench 30 has a back face plate 40 is secured to the outer ring case 32 by screws 42. The back face plate 40 defines a face plate aperture 41. The back face plate 40 serves to retain the inner ring 36 within the outer 32 along with other components detailed below. A spring loaded ball bearing 44 is optionally provided protruding from a surface of the hex aperture 38 and provides for positive engagement of the hex nut 31.
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In the preferred embodiment the outer ring case 32 is machined from a block of material, preferably stainless steel. However, other materials may be used and the outer ring case 32 need not be monolithic. It will be realized by those skilled in the art that the outer ring case 32 can optionally be formed of assembled individual parts. For instance, the outer ring wall 50 and the inner holding ring 51 may be separately machined and attached to the case face plate 58 by any of various known means such as screws, welding, brazing or bonding agents, for example. It will be realized also that the outer ring case 32 may be also formed by molding. Such alternative construction techniques may be used provided that desired tolerances, which are dictated by the application, are maintained.
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The inner ring body 70 has first and second concentric holes, 90 and 92, of which the second concentric hole 92 has a diameter greater than the first concentric hole 90 such that a step (not shown) is formed within the inner ring body 70. A connector acceptor body 94 is disposed in the second concentric hole 92 and defines the hex aperture 38. In the preferred embodiment, the connector acceptor body 94 is fixedly held in place by a set screw (not shown) threaded in the back flange 74. However, it is realized that other methods known in the art, such as press fitting, brazing, and bonding agents, may be used to secure the connector acceptor body 94, and that the present invention is not limited to methods disclosed herein for securing the connector acceptor body. Furthermore, an embodiment wherein the connector acceptor body 94 and the inner ring body 70 are formed as one piece is also considered to be within the metes and bounds of the present invention.
Referring to
A split ring spring 100 surrounds the inner holding ring 51 and biases the slide block 95 radially inward such that a slanted face 96 of the slide block 95 is positioned to engage the roller pins 80 when the inner ring assembly 36 rotates relative to the outer ring case 32. A ring segment spring 102, also known as a leaf spring, is disposed between the outer ring wall 50 and the inner holding ring 51. Although the split ring spring 100 and the ring segment spring 102 are depicted as circular or portions of a circle, such configurations are not required and the springs may be ellipse or have other configurations provided they function as disclosed herein. An adjustment screw 104 passes through the clearance hole 62 and a first spring clearance hole 106 and a second spring clearance hole 108. A threaded hole 110 accepts the adjustment screw 104. In the embodiment shown the first spring clearance hole 106 is preferably centrally positioned in the ring segment spring 102 while the second spring clearance hole 108 is positioned to align a split 101 of the split ring spring 100 with the slide block 95. While in the preferred embodiment the slit ring spring 100 is circular and the ring segment spring 102 is a segment of a circle, it is understood that the present invention is not limited to circular embodiments of these components.
The adjustment screw 104 applies pressure to the ring segment spring 102 which in turn applies bias pressure to opposing sides of the split ring spring 100. The pressure applied to the split ring spring 100 adjusts bias pressure applied to the slide block 95. The torque wrench 30 is engaged with the hex 31 and rotated in the counter clockwise direction in the view of
The amount of torque applied to the hex nut 31 is adjustable by rotation of the adjustment screw 104 and consequent adjustment of pressure applied by the ring segment spring 102 to the split ring spring 100. The further the adjustment screw 104 is threaded into the threaded hole 110, the greater is the torque applied to the hex nut 31.
The split ring spring 100 and the ring segment spring 102 are formed of any material having an elastic modulus sufficient to provide the desired torque without permanent deformation. In a preferred embodiment beryllium copper having a temper of TH04 (formerly HT) is used and machined into the respective components. It will be realized by those skilled in the art that a softer temper, such as TB00 (formerly A) for example, may be machined and then heat treated to a requisite hardness. Beryllium copper provides for temperature insensitivity thereby permitting accurate functioning over a wide range of temperature.
Referring to
Component dimensions for an 8 lb-in torque wrench, which is an example of the present invention, follow in Table 1.
*For ring segment spring of 0.58″
**For ring segment spring of 0.625″
While the ring segment spring 102 in the above example has a segment angle of 195° in the prototype, the segment angle may be set in the range of about to 132°-136° as noted above. Alternatively, the segment angle is set in a range of 192°-196° for a radius of 0.625″. With regard to the split ring spring 100, the ring segment spring 102 engages the split ring spring 100 at engagement points angularly spaced apart as dictated by the above dimensions with respect to the split ring spring 100. While the above dimensions are used in an 8 lb-in torque wrench, it is within the scope and spirit of the present invention for those skilled in the art to alter the dimensional configuration to achieve other torques for testing and alternative applications.
In the torque wrench various lubricants may be used such as light oils, synthetic and natural, silicone lubricant. However, dry graphite powder is preferably used.
In the embodiment shown in
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It is understood that the present invention includes all combinations of the above alternative embodiments of biasing mechanisms, slide blocks, and combinations thereof. For example, each of the alternative embodiments of the slide block may be used in combination with any of the alternative embodiments of the bias mechanisms except for where to two are combined such as in
Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.