Patent Grant
9238967
The subject invention relates to actuators and, in some embodiments, robotics.
Hopping robots are described in U.S. Pat. Nos. 7,263,955; 7,775,305; 6,247,546; and 6,328,002 as well as in pending application Ser. No. 13/066,276 filed Apr. 11, 2011, all of which are incorporated herein by this reference. A combustion powered linear actuator is used to provide hopping mobility
In the designs of U.S. Pat. No. 7,263,955, the actuator piston is releasably latched to the actuator body via a magnet which is exposed to the environment can become fouled when the piston extends. In cases where the piston cannot be retracted or will not stay in the retracted position because of magnet fouling, operation of the robot via a hopping action would be hindered.
Moreover, the combustion gas exhaust ports of the designs depicted in the '995 patent are not sealed when the piston is retracted which can lead to contamination of the components of the actuator in harsh environments. Such contamination may result in a failure to function and premature wear.
The invention provides, in one particular example or embodiment, a new linear actuator sealed with respect to the environment when the piston is retracted. And yet, the seals used are configured to allow exhaust gasses to exit the actuator when the piston extends. In some aspects, the invention features a linear actuator configured with a magnetic latch protected from the environment. In another aspect, the invention improves on the linear actuator of U.S. Pat. No. 7,263,955 in other respects. The actuator can be used with hopping robots of different configurations including, but not limited to, the hopping robot depicted in U.S. Pat. No. 7,263,955 and the hopping robot depicted in U.S. application Ser. No. 13/066,276 filed Apr. 11, 2011.
Featured is a combustion powered linear actuator comprising an actuator body having a first chamber therein and a power piston mounted in the first chamber movable between retracted and extended positions. The power piston has a combustion chamber therein. A first seal is disposed about the piston and seals the piston with respect to the actuator body. A vent region in the body of increased diameter allows exhaust gases to bypass the first seal to a space between the piston and the actuator body and to vent out of the actuator body. A second seal proximate the distal end of the actuator body cooperates with a seal body to seal the vent region when the piston is retracted.
In one preferred version, vent region includes a vent gland in the first chamber about the piston defining a vent chamber between the actuator body and the vent gland. The vent gland may include upper exhaust ports venting exhaust gases from the first chamber into the vent chamber and lower exhaust ports venting the exhaust gases from the vent chamber out the distal end of the actuator body. The second seal is preferably a lip seal mounted to the vent gland.
Further included is a foot attached to the distal end of the piston. One foot has a non-circular face, e.g., a rectangular face. Then, the piston includes a keyed feature and the vent gland includes a piston orientation bearing constraining the piston from rotation. The piston keyed feature may include flat regions. The piston may also include a tapered nozzle communicating with the combustion chamber.
A latch releasably retains the piston in a retracted position. The latch typically includes a magnet. One latch further includes a first flux guide fixed to the top of the actuator body and housing the magnet. A non-ferrous magnet isolator may be disposed at least partially about the magnet. The actuator may include plating at least partially over the first flux guide and the isolator. The first flux guide may include one or more fuel ports leading into the combustion chamber and a glow plug for igniting fuel in the combustion chamber. The piston also includes a proximal flux guide mateable with the first flux guide. A seal may be disposed between the proximal flux guide and the first flux guide. A wear ring may also be disposed about the proximal flux guide.
A spring about the piston is configured to retract the piston. Preferably, the spring is isolated from the vent region. The piston may include a stop member and the vent region includes a stop surface.
One combustion powered linear actuator includes an actuator body having a first chamber therein, a power piston mounted in the first chamber movable between retracted and extended positions, the power piston having a combustion chamber therein, a vent gland disposed between the actuator body and the power piston defining an annular vent chamber between the vent gland and the actuator body, a seal portion on the distal end of the piston, and a seal mounted to the vent gland proximate the distal end of the actuator body cooperating with the seal portion sealing the annular vent chamber when the piston is retracted.
A combustion powered linear actuator in accordance with examples of the invention includes an actuator body having a first chamber therein and a power piston mounted in the first chamber moveable between retracted and extended positions. The power piston includes a combustion chamber therein. A vent region in the actuator body exhausts gases from the combustion chamber and first chamber through one or more ports. One or more seals seal the piston with respect to the actuator body and the vent region port or ports with respect to the atmosphere when the piston is in the retracted position. Preferably, the vent region includes a vent gland in the actuator body defining an annular vent chamber between the actuator body and the vent gland. The vent gland may include exhaust ports venting exhaust gases from the first chamber into the annular vent chamber and also exhaust ports venting exhaust gases from the annular vent chamber to the atmosphere.
The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives.
Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which:
Aside from the preferred embodiment or embodiments disclosed below, this invention is capable of other embodiments and of being practiced or being carried out in various ways. Thus, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. If only one embodiment is described herein, the claims hereof are not to be limited to that embodiment. Moreover, the claims hereof are not to be read restrictively unless there is clear and convincing evidence manifesting a certain exclusion, restriction, or disclaimer.
Note that water and other contaminants can enter exhaust port 30 and adversely affect the operation of the actuator in harsh environments. Also, when the piston is extended, magnet 34 can become fouled by debris. As noted in the Background section above, if the magnet becomes fouled it may be the case that the piston cannot be retracted and/or will not stay in the retracted position.
In a new design, in one example, a harsh environment combustion powered actuator is featured wherein the actuator volume is sealed with respect to the environment when the piston is retracted. The actuator of volume is open to the atmosphere only after a specified piston travel in order to allow exhaust gases to exit and thereby allow the piston to be more easily retracted and latched into the retracted position. The magnetic latch used, in one preferred embodiment, is positioned inside the sealed actuator volume to prevent accumulation of ferrous particles (commonly found in sand and dirt) on the magnetic latch which would prevent the actuator from closing and adversely affect refueling operations. In one version, a non-circular (e.g., rectangular) foot is used and means are provided for orientation control of the piston and foot combination. Wear elements are provided on the piston in order to extend the life of the actuator. Featured is a wear element retention method tolerant of high speed gas velocity during venting. A coaxial low resistance exhaust path bypasses the retraction spring and orientation control bearing. A specialized fueling chamber nozzle is included to reduce the required latching force holding requirements. A piston extension stop prevents entanglement with the retraction spring at full extension of the piston and compression of the spring. Not every embodiment, however, includes all these features.
New actuator 50,
Seal body 70 is disposed about the distal end of the piston and environmental lip seal 72 cooperates with seal body 70 to seal annular region 80 when the piston is retracted to prevent contamination of the interior of the actuator. In other embodiments, the two pistons seals (60 and 70, 72) which seal the actuator when the piston is retracted and allow exhaust gasses to exit the actuator when the piston extends, may take other forms.
Although not necessarily a limitation,
Upon ignition of the fuel in combustion chamber 58 by a controllable source such as glow plug 101, as show in
The figures show lip seal 72 is attached to vent gland 90 in one preferred embodiment. Piston foot 100 is also shown and typically has a non-circular (e.g., rectangular) face as shown for improved actuation of the robot in some terrain configurations. Thus, to prevent the piston and the foot from rotation during piston extension, the piston may include a keyed feature and vent glad 90 includes a piston orientation bearing of some type cooperating with the keyed feature of the piston to constrain the piston from rotation. In one version as shown in
Another feature of the invention, in some embodiments, includes tapered nozzle 120,
Further included may be wear ring 150 made of or including Teflon and configured about piston flux guide 137 to mate with the interior wall surface of housing 52. In the design shown, wear ring 150 is disposed about piston flux guide 137. Spring 160 is disposed about the piston and is configured to retract the piston after extension and exhaust gas venting. In this preferred design, spring 160 is isolated from vent region 62 by gland 90 and thus a longer life is expected of spring 160. Also, stop member 170 is preferably a component of piston 56 and mates with stop surface 172 in vent region 62 defined by a shelf formed within gland 90.
Thus, a harsh environment combustion powered actuator is featured wherein the actuator volume is sealed with respect to the environment when the piston is retracted. The magnetic latch used, in one preferred embodiment, is inside the sealed actuator volume to prevent accumulation of ferrous particles (commonly found in sand) on the magnetic latch which would prevent the actuator from closing and adversely affect refueling operations. In one version, a non-circular (e.g., rectangular) foot is used and means are provided for orientation control of the piston and foot combination. Wear elements are provided on the piston in order to extend the life of the actuator. A coaxial low resistance exhaust path bypasses the retraction spring and the orientation control bearing. A specialized fueling chamber nozzle is included to reduce the required latching force holding requirements. A piston extension stop prevents entanglement with the retraction spring at full extension of the piston and compression of the spring.
Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. The words “including”, “comprising”, “having”, and “with” as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection. Moreover, any embodiments disclosed in the subject application are not to be taken as the only possible embodiments.
In addition, any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed: those skilled in the art cannot reasonably be expected to draft a claim that would literally encompass all possible equivalents, many equivalents will be unforeseeable at the time of the amendment and are beyond a fair interpretation of what is to be surrendered (if anything), the rationale underlying the amendment may bear no more than a tangential relation to many equivalents, and/or there are many other reasons the applicant can not be expected to describe certain insubstantial substitutes for any claim element amended.
Other embodiments will occur to those skilled in the art and are within the following claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2158180 | Goddard | May 1939 | A |
| 6247546 | Spletzer et al. | Jun 2001 | B1 |
| 6328002 | Spletzer et al. | Dec 2001 | B1 |
| 7263955 | Fischer | Sep 2007 | B1 |
| 7650919 | Rhyne et al. | Jan 2010 | B2 |
| 7775305 | Fischer | Aug 2010 | B1 |
| 20070267116 | Rhyne et al. | Nov 2007 | A1 |
| 20080230285 | Bewley et al. | Sep 2008 | A1 |
| 20090283185 | Manesh et al. | Nov 2009 | A1 |
| 20100078111 | Anderson et al. | Apr 2010 | A1 |
| 20100200131 | Iwase et al. | Aug 2010 | A1 |
| 20120259460 | Rizzi et al. | Oct 2012 | A1 |
| Entry |
|---|
| Salton et al. and Rizzi et al., “Urban Hopper”, Apr., 2010, 9 pgs. (unnumbered). |
| Fischer, Gary J., “Wheeled Hopping Mobility,” Unmanned/Unattended Sensors an Sensor Networks II, SPIE vol. 5986, 2005, pp. 59860H-1 to 59860H-9. |
| Lambrecht et al., “A Small, Insect-Inspired Robot that Runs and Jumps,” Proceedings of 2005 IEEE International Conference on Robotics and Automation, Apr. 2005, pp. 1240-1245. |
| Nasa, “Flight Path and Orientation Control,” Mar. 18, 2010, 6 pages. |
| Office Action for U.S. Appl. No. 13/066,276 mailed Jan. 13, 2014, 24 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20140083077 A1 | Mar 2014 | US |
