AUTO-LOCKING BALL JOINT |
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申请号 | EP16163491.0 | 申请日 | 2016-04-01 | 公开(公告)号 | EP3187740A1 | 公开(公告)日 | 2017-07-05 |
申请人 | Leo D. Bernstein & Sons, Inc.; | 发明人 | SUTTON, Levi; | ||||
摘要 | An auto-locking ball joint includes a first elongate member, a ball, and a second elongate member. The first elongate member includes a receiver disposed at one end. The receiver has an inner surface that defines a well. The ball is rotatable disposed within the well. The ball is formed from a plurality of segments that are moveable relative to one another towards and away from a ball axis. The second elongate member is translatable along the ball axis. In a locked configuration, the outer surface of the ball frictionally engages the inner surface to prevent the ball from rotating within the well. In an unlocked configuration of the ball joint, the ball is rotatable within the well. The second elongate member is depressed along the ball axis to transition the ball joint from locked configuration to the unlocked configuration. | ||||||
权利要求 | |||||||
说明书全文 | The present disclosure relates to ball joints and, more specifically, to ball joints including an auto-locking mechanism. Ball joints allow two links to be coupled together while permitting rotation of the links about the joint in all three rotational degrees of freedom (DOF). Some ball joints include a locking mechanism that allow the ball joint to be locked to fix the links to one another in one or more of the DOF. Typically, a locking mechanism includes an external member that is moved into contact with a ball of the ball joint such that engagement of the external member and the ball locks the ball joint. One limitation of this type of locking member is that when a force is applied to one of the links to move the links relative to one another about the locked ball joint, the force of the external member exerted on the ball must be increased or be greater than the force applied to the links. It can be difficult for a user to exert a large enough force with the external member on the ball to lock the ball joint when a large force is applied to one of the links to move the links relative to one another. Accordingly, there is a continuing need for ball joints that can lock two links relative to one another in the presence of a large force being exerted on the links. This disclosure relates generally to an auto-locking ball joint that is biased to a locked configuration where arms or links of the ball joint are fixed relative to one another. In the locked condition, the ball joint is configured to utilize forces on the links to increase the locking or fixing of the links relative to one another and acts as a self-actuating brake. As a self-actuating brake, the more force that is applied to move the ball joint the greater the locking force of the joint. The ball joint is transitioned to an unlocked condition by depressing one of the links towards the ball joint which allows the links of the ball joint to rotate in one or more degrees of freedom relative to one another. When the depressed link is released, the ball joint returns to the locked condition. It is envisioned that the force required to depress the link is relatively small compared to the forces experienced by the link in directions other than towards the ball joint to unlock the ball joint. In an aspect of the present disclosure, an auto-locking ball joint includes a first elongate member, a ball, and a second elongate member. The first elongate member includes a receiver disposed at one end. The receiver has an inner surface that defines a well that rotatably receives the ball. The ball defines a ball axis and a channel about the ball axis. The ball is formed from a plurality of segments that are moveable towards and away from the ball axis. The segments of the ball cooperate to define an outer surface of the ball. The second elongate member is translatable along the ball axis and has first and second end portions. The first end portion is disposed within the channel of the ball. In a locked configuration of the auto-locking ball joint, the outer surface of the ball frictionally engages the inner surface defining the well to prevent the ball from rotating within the well. In an unlocked configuration of the auto-locking ball joint, the ball is rotatable within the well. The second elongate member is depressed towards the receiver along the ball axis to transition the auto-locking ball joint from the locked configuration to the unlocked configuration. In aspects, the auto-locking ball joint is biased towards the locked configuration. The auto-locking ball joint may include a biasing member that is disposed within the well and engaged with the first end portion of the second elongate member to urge the auto-locking ball joint towards the locked configuration. In some aspects, the plurality of segments of the ball define a first gap between adjacent segments in the locked configuration and define a second gap between adjacent segments in the unlocked configuration where the second gap is smaller than the first gap. In the unlocked configuration, the second gap may be substantially zero such that adjacent segments are in contact with one another. The first end portion of the second elongate member may include flats and edges that are defined at the intersection of adjacent flats. The edge of the first end portion may be disposed in a gap between adjacent segments of the ball such that rotation of the second elongate member engages the edge with one of the adjacent segments to move the ball segment outward and into engagement with the inner surface defining the well of the receiver. The geometry of the auto-locking ball joint may be designed such that rotation of the second elongate member increases the locking force of the joint. In addition, the more force applied to rotate the second elongate member may increase the locking ability of the auto-locking ball joint. In certain aspects, the auto-locking ball joint includes a contracting member about the ball, the contracting member may urge the plurality of segments of the ball towards the ball axis. The contracting member may urge each segment towards adjacent segments to reduce the diameter of the ball. In particular aspects, the second elongate member defines a lumen that is disposed about the ball axis and the first elongate member defines a passage that is in communication with the well. The auto-locking ball joint may include a pin that is disposed within the lumen and the passage to align the first and second elongate members with one another while allowing the auto-locking ball joint to rotate in only one degree of freedom in the unlocked configuration. In aspects, at least a portion of the channel of the ball is frusctoconical in shape and the first end portion of the second elongate member is frusctoconical in shape. The entire channel of the ball may be frusctoconical in shape. The second end portion of the second elongate member may extend from the ball. In some aspects, a length of contact between the second elongate member and the ball is larger in the unlocked configuration than in the locked configuration. The second elongate member may be configured to deflect in the locked configuration in the presence of a high load such that the auto-locking ball joint slips in the locked configuration. In another aspect of the present disclosure, an auto-locking ball joint includes a first elongate member, a ball, and a second elongate member. The first elongate member includes a receiver disposed at one end. The receiver has an inner surface that defines a well. The ball is rotatably disposed within the well and has an outer surface. The ball defines a ball axis and a channel about the ball axis. The second elongate member is translatable along the ball axis and includes a portion disposed within the channel of the ball. In a locked configuration of the auto-locking ball joint, the outer surface of the ball frictionally engages the inner surface defining the well to prevent the ball from rotating within the well. In an unlocked configuration of the auto-locking ball joint, the ball is rotatable within the well. The second elongate member is depressed towards the receiver along the ball axis to transition the auto-locking ball joint to the unlocked configuration. In aspects, the ball includes a plurality of segments that are disposed about the ball axis. The plurality of segments may be moveable towards and away from the ball axis to vary a diameter of the ball defined by the outer surface of the ball. Alternatively, the ball may be formed from a resilient compressible material such that a diameter of the ball defined by the outer surface of the ball may be varied. In another aspect of the present disclosure, a mannequin includes first and second anatomical structures and a joint between the first and second anatomical structures. The joint includes an auto-locking ball joint to provide selective movement between the first and second anatomical structures. The auto-locking ball joint includes a first elongate member, a ball, and a second elongate member. The first elongate member includes a receiver disposed at one end. The receiver has an inner surface that defines a well. The first elongate member is disposed within and fixed relative to the first anatomical structure. The ball is rotatably disposed within the well and defines a ball axis and a channel about the ball axis. The ball is formed from a plurality of segments that are moveable towards and away from the ball axis. The segments of the ball cooperate to define an outer surface of the ball. The second elongate member is translatable along the ball axis and has first and second end portions. The first end portion is disposed within the channel of the ball and the second end portion is disposed within and fixed relative to the second anatomical structure. In a locked configuration of the joint of the mannequin, the outer surface of the ball frictionally engages the inner surface defining the well to prevent the first and second anatomical structures from moving relative to one another. In an unlocked configuration of the joint of the mannequin, the ball is rotatable within the well to allow the first and second anatomical structures to move relative to one another. The first anatomical structure is pressed into the joint to transition the joint from the locked configuration to the unlocked configuration. In aspects, the first and second anatomical structures are moveable in three degrees of freedom relative to one another when the joint is in the unlocked configuration. Alternatively, the first and second anatomical structures may only be moveable in one degree of freedom relative to one another when the joint is in the unlocked configuration. Further, to the extent consistent, any of the aspects described herein may be used in conjunction with any or all of the other aspects described herein. Various aspects of the present disclosure are described hereinbelow with reference to the drawings, which are incorporated in and constitute a part of this specification, wherein:
Embodiments of the present disclosure are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. Typically, prior art locking ball joints use frictional engagement of a locking member to frictionally engage a ball and to urge the ball into frictional engagement with a portion of the ball joint. For example with reference to This disclosure relates generally to an auto-locking ball joint including a cup having a shaft, a ball, and a stem. The cup receives the ball and the ball receives the stem such that as the stem rotates the ball rotates within the cup. The ball joint includes a biasing member disposed between the stem an inner surface of the cup that biases the stem such that the ball joint is biased towards a locked condition where the ball frictionally engages the inner surface of the cup to prevent the stem from rotating relative to the cup. To transition the ball joint to an unlocked configuration, where the stem is rotatable relative to the cup, the stem is depressed towards the ball such that the stem moves relative to the ball against the biasing member to allow the ball to decrease in diameter. When the stem is released in the unlocked configuration, the biasing member urges the stem away from the ball to return the ball joint to the locked configuration. Referring now to The ball 40 is received within the well 30 of the cup 20 and defines a channel 42. The channel 42 of the ball 40 defines a ball axis B-B. The channel 42 includes a first or large diameter end 43a defining a first diameter and a second or small diameter end 43c defining a second diameter smaller than the first diameter. As shown, a portion of the channel 42 adjacent the large diameter end 43a is frusctoconical in shape and a portion 43b of the channel 42 adjacent the small diameter end 43c is substantially cylindrical in shape. It is envisioned that the entire channel 42 may be frusctoconical in shape. Further, it is envisioned that at least a portion of the channel 42 may have other shapes with a large diameter end 43a and a small diameter end 43c (e.g., wedge shaped). With additional reference to The segments 44 of the ball 40 cooperate to define an annular groove 46 about an outer surface 41 of the ball 40 transverse to the ball axis B-B ( The stem 50 is an elongate member or link that is translatable along the ball axis B-B defined by the ball 40 and includes a first end portion 52, a second end portion 56, and a central portion 54 disposed between the first and second end portions 52, 56. The first end portion 52 of the stem 50 is disposed within the channel 42 of the ball 40 and the second end portion 56 of the stem 50 extends from the small diameter end 43b of the channel 42. The first end portion 52 of the stem 50 may be frustoconical in shape and includes flats 53a about an outer surface of the stem 50. The flats 53a of the first end portion 52 define edges 53b at the intersections of adjacent flats 53a ( Referring to Referring now to Referring to The locking biasing member 38 may bias the first end portion 52 of the stem 50 into engagement with the segments 44 of the ball 40 to affect outward movement of the segments 44 into engagement with the inner surface 31 of the cup 20 defining the well 30. With reference now to Referring back to In the locked configuration, when loads are applied to the stem 50, with the first end portion 52 disposed within the ball 40, the geometry of the locking ball joint 10 is designed such that the stem 50 forces the segments 44 of the ball 40 outwards into the well 30 of the receiver 22 and friction force between the ball 40 and the receiver 22 of the cup 20 increases. As additional load is applied to move the stem 50 relative to the cup 20, the friction forcebetween the ball 40 and receiver 22 increases. The geometry is designed such that the friction force µ between the ball 40 and the receiver 22 of the cup 20 increases at the same rate or a greater rate than the load to move the stem 50 relative to the cup 20. Since the friction force is applied due to a load, an external locking force is not required to lock the locking ball joint 10 (e.g., tightening the locking handle 1030 in the prior art locking ball joint of To determine if the locking ball joint 10 will maintain the position of the stem 50 relative to the cup 20 (i.e., remain locked) in a given loading case, two loading cases can be considered. With particular reference to When in the unlocked configuration, the effective contact length changes as is shown by length L2 shown in In the second loading case, a torque about the ball axis B-B as represented by torque T. In the locked configuration, the torque T is applied to the stem 50 such that engagement of the first end portion 52 of the stem 50 moves the ball segments 44 outwards. The larger the torque T, the greater the force applied to move the ball segments 44 into the wall 31 defining the well 30 which increases the friction force locking the locking ball joint 10. With additional reference to Referring now to The mannequin 100 also includes a second ball joint 10b disposed in an elbow joint 112 between the upper arm segment 106 and a lower arm segment 114 of the mannequin 100. The second ball joint 10b is set to act as a hinge joint to only allow the upper arm segment 104 and the lower arm segment 114 to move in one DOF relative to one another when the second ball joint 10b is in an unlocked configuration. The shaft 28 of the second ball joint 10b is disposed within upper arm segment 106 and the stem 50 is disposed within the lower arm segment 114. Referring briefly back to Referring to With the upper arm segment 106 in the desired position, the upper arm segment 106 is released. When the upper arm segment 106 is released, the locking biasing member 38 ( With the first ball joint 10a returned to the locked configuration, the second ball joint 10b is unlocked by pressing the lower arm segment 114 into the upper arm segment 106 at the elbow joint 112. This action translates the stem 50 of the second ball joint 10b towards the receiver to transition the second ball joint 10b to the unlocked configuration to allow rotation of the elbow joint 112. With the second ball joint 10b in the unlocked configuration, the lower arm segment 114 is rotated relative to the upper arm segment 106 about the elbow joint 112 until the lower arm segment 114 is in a desired position as shown in As described herein, the ball joint 10 is used in a mannequin to selectively lock anatomical members relative to one another. It is envisioned that the auto-locking ball joint 10 may be used in a variety of applications including, but not limited to, prosthetic limb joints, mounting stands for vices or similar equipment, music stands, monitor stands, television mounts, computer display mounts, microphone stands, GPS mounts, cell phone holders, floor lamps, and table lamps. While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Any combination of the above embodiments is also envisioned and is within the scope of the appended claims. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope of the claims appended hereto. |