Patent Application
20080317548
The present invention generally pertains to the hobby-mechanical industry. More specifically, the present invention pertains to an adapter configured to be coupled to a hobby servo output shaft for driving an auxiliary shaft.
A servo motor (a.k.a. simply a “servo”) is a device having a rotatable output shaft. The output shaft can typically be positioned to specific angular positions in accordance with a coded signal received by the servo. It is common that a particular angular position will be maintained as long as a corresponding coded signal exists on an input line. If the coded signal changes, the angular position of the shaft will change accordingly. Control circuits and a potentiometer are typically included within the servo motor casing and are functionally connected to the output shaft. Through the potentiometer (e.g., a variable resistor), the control circuitry is able to monitor the angle of the output shaft. If the shaft is at the correct angle, the motor actuates no further changes. If the shaft is not at the correct angle, the motor is actuated in an appropriate direction until the angle is correct.
There are different types of servo motors that include output shafts having varying rotational and torque capabilities. For example, the rotational and/or torque capability of an industrial servo is typically less restricted than that of a hobby servo. That being said, hobby servos are generally available commercially at a cost that is much less than that associated with industrial servos.
Because hobby servos are relatively small and inexpensive, they are popular within the hobby-mechanical industry for applications such as, but not limited to, hobby robotic applications and radio-controlled models (cars, planes, boats, etc.). One example of a hobby servo is the Futaba S-148 available from Futaba Corporation of America located in Schaumburg, Ill.
Ridges (or teeth) are typically distributed around the outside surface of the output shaft of a hobby servo. Thus, the hobby servo has a “male” spline configuration. Mechanism to be driven by the output shaft will typically have a corresponding “female” spline receiver adapted to engage the output shaft. For example, a gear having a toothed receiver portion may be engaged to the output shaft of a hobby servo. Currently, it can be difficult to engage a device that does not include a “female” spline configuration to a hobby servo.
Further, some applications require that shafts (i.e., axles, rods, beams, etc.) be driven (e.g., rotated) by a hobby servo. These shafts might be round and/or smooth, but could have a different shape (e.g., polygonal like triangle, square, etc.). Driving any shaft, regardless of shape, with the output shaft of a hobby servo presents challenges at least because the output shaft is typically not very durable. For some applications, there is a need to engage a shaft to the output shaft of a hobby servo such that the shaft can be driven (e.g., rotated) in line with the output shaft.
An adapter is provided for coupling an output shaft of a servo to an auxiliary shaft. The adapter includes an adapter body having a longitudinal axis extending from a first end to a second end. The adapter body includes a first bore centered on the longitudinal axis and extending into the first end a first distance. The first bore is configured to accept a portion of the auxiliary shaft. The adapter body also includes a second bore centered on the longitudinal axis and extending into the second end a second distance. The adapter also includes an engagement member positioned within the second bore. The engagement member is configured to accept and engage a portion of the output shaft of the servo.
Other features and benefits that characterize embodiments of the present invention will be apparent upon reading the following detailed description and review of the associated drawings.
Electrical cable 22 is attached to the servo motor 10 to provide electrical power and/or electrical signals to cause the output shaft 12 to rotate in a counter-clockwise or clockwise direction. Servo motor 10 can be any type of servo motor including a hobby servo motor and is not limited in terms of its style, capacity, motor speed, or load carrying capability.
An output shaft adapter assembly 30 is configured to engage output shaft 12 of servo motor 10. Output shaft adapter assembly 30 is further configured to accept and be engaged with an auxiliary shaft 32 (shown in
The output shaft adapter assembly 30 includes an adapter body 40. In one example, adapter body 40 is formed from aluminum. However, body 40 can be made of any suitable material including, but not limited to, other metals, polymers, composite materials and so forth. Adapter body 40 will be described in more detail below. The output shaft adapter assembly 30 also includes a threaded fastener 28 that is configured to engage the threaded orifice 14 to secure adapter body 40 to splined output shaft 12.
As illustrated in
Output shaft adapter assembly 30 includes an output bore 54 adapted to receive auxiliary shaft 32. While auxiliary shaft 32 is illustrated as a round shaft, any shape and size shaft can be received by assembly 30. For example, assembly 30 can be adapted to receive triangular or square shafts. In other examples, polygons having more than four sides can be received by assembly 30.
Fastener 34 is adapted to engage adapter body 40 at a lateral bore 60 that extends into the adapter body 40 generally perpendicular to a longitudinal axis 35. Bore 60 is configured such that when fastener 34 is tightened body 40 is deformed to some extent, thereby reducing gap 58. Thus, fastener 34 is configured to secure auxiliary shaft 32 within assembly 30. In one example, gap 58 is reduced such that bore 54 forms a relatively tight engagement to shaft 32 and rotatably engages assembly 30 and auxiliary shaft 32.
Output bore 54 extends into adapter body 40 from the first end 42. In one embodiment, the output bore 54 is a generally circular bore, but it should be understood that the output bore 54 can be sized and shaped to accept any auxiliary shaft 32. For example, bore 54 can be a square, pentagon, or any other polygon or non-polygon shape. Further, output bore 54 can include a tapered surface 55 at the first end 42 to allow for ease of insertion of the auxiliary shaft 32. The output bore 54 can be formed into the adapter body 40 by machining the adapter body 40, as part of a molding or additive process, or through any other suitable process.
Adapter body 40 includes an input bore 48 extending into adapter body 40 from second end 44. In one example, input bore 48 has a hexagonal shape configured to accept a generally hollow engagement member 50 having a female spline receiver formed therein. Engagement member 50 is further configured to engage a splined output shaft (i.e., shaft 12 illustrated in
Engagement 50 can be comprised of plastic material. However, engagement member 50 can be any material such as, but not limited to, PVC, metal, or any other suitable material. Further, engagement member 50 can have any engagement configuration suitable to engage a servo output shaft. In various embodiments, engagement member 50 has a 23, 24, or 25-tooth configuration. However, it is important to note that engagement member 50 can have any suitable configuration to engage servo motor 10.
Slit 58 extends into the tab 64 longitudinally from the first end 42 to the second end 44 of the adapter body 40. Slit 58 splits tab 64 into first and second parts 66 and 68. In one embodiment, slit 58 extends into output bore 54 from end surface 67.
First part 66 and second part 68 each have lateral bore 60 extending therethrough. As illustrated, lateral bore 60 is proximate first end 42 of the adapter body 40. In one example, at least a portion of lateral bore 60 in the second part 68 of tab 64 is threaded such that it can engage a fastener 34. When torque is applied to the fastener 34 to cause it to be tightened, the first part 66 and the second part 68 are drawn together such that slit 58 is compressed and the material of the adapter body 40 proximal to the output bore 54 is slightly deformed. When the auxiliary shaft 32 is positioned within the output bore 54, the resultant deformation of the adapter body 40 creates a retaining force to secure the auxiliary shaft 32 within the output bore 54.
Further, an adapter body 40 having a particular output bore 54 shape and size can be configured to be utilized with a plurality of engagement member 50 configurations. In other words, a plurality of similar adapter bodies 40 can be manufactured and configured to engage varying output spline configurations by utilizing different engagement members 50. For example, a 23 tooth engagement member can be utilized with one adapter body configuration while a 25 tooth engagement member can be utilized with a substantially similar adapter body configuration. Similarly, adapter bodies having similar configurations can be manufacture having different bore 54 sizes for engaging varying auxiliary shaft sizes.
Divider 52 extends between the input bore 48 and the output bore 54. In one example, divider 52 is integrated with a portion of material that forms adapter body 40. Divider 52 discourages engagement member 50 from passing through the interior bore of body 40.
As illustrated, divider 52 can be positioned such that output bore 54 extends further into the coupler body 40 than input bore 48. In some examples, output bore 54 extends more than three times further into the coupler body than input bore 48. This provides for an enlarged surface area of the auxiliary shaft 32 that can be accepted into the adapter body 40 and retained by the retaining force applied with the fastener 34 engages the lateral bore 60.
An orifice 56 extends through divider 52 to join the input bore 48 with the output bore 54. When the adapter body 40 is positioned on a servo 10 such that the splined output shaft 12 is inserted into the input bore 48, a threaded fastener 28 (shown in
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 60/936,292, filed Jun. 19, 2007, the content of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60936292 | Jun 2007 | US |
