Vibration prevention in a linear actuator

Information

  • Patent Grant
  • 11255405
  • Patent Number
    11,255,405
  • Date Filed
    Thursday, October 20, 2016
    8 years ago
  • Date Issued
    Tuesday, February 22, 2022
    2 years ago
Abstract
An apparatus for vibration reduction in a linear actuator includes one or more sets of counterweights, one or more enclosures configured to receive one set of counterweights for each enclosure, and a driving shaft configured to mount the one or more sets of counterweights. The one or more sets of counterweights are disposed symmetrically with respect to a plane that extends perpendicularly and longitudinally through a longitudinal axis of the linear actuator. The driving shaft extends perpendicularly and transversely through the longitudinal axis and the plane. A portion counterweight of a given set of counterweights may rotate clockwise and another portion counterweight of the given set of counterweights may rotate counterclockwise.
Description
TECHNICAL FIELD

The present invention relates to the field of vibration prevention, and more particularly to the field of vibration prevention in linear actuators.


BACKGROUND

Vibration propagates via mechanical waves and is detrimental in various engineered systems. Many techniques have been developed to prevent vibrations in such systems. The techniques for vibration prevention generally fall into two categories: passive vibration isolation and active vibration isolation. The passive vibration isolation usually employs materials and/or mechanical linkages that absorb and damp these mechanical waves, for example, mechanical springs and/or pads or sheets of flexible materials such as elastomers, rubber, cork, dense foam, and laminate materials. The active vibration isolation usually involves sensors and actuators that create destructive interference to cancel out incoming vibration.


For example, vibration of an internal combustion engine can significantly impact the performance of the internal combustion engine, and may cause undesirable damage to the internal combustion engine. The techniques that have been employed to reduce or eliminate vibration of an internal combustion engine include a crankshaft damper and an engine mount that attaches an engine to the chassis.


The vibration prevention of the present disclosure may mitigate or solve one or more of the problems set forth in linear actuators and/or free piston engines or linear engines.


SUMMARY

One aspect of the present disclosure is directed to an apparatus for vibration reduction in a linear actuator. The apparatus may include one or more sets of counterweights Each set may be configured to have one or more counterweights. The apparatus may include one or more enclosures configured to receive one set of counterweights for each enclosure, and a driving shaft configured to mount the one or more sets of counterweights. The one or more sets of counterweights may be configured symmetrically with respect to a plane that extends perpendicularly and longitudinally through a longitudinal axis of the linear actuator. The driving shaft may extend perpendicularly and transversely through the longitudinal axis of the linear axis and the plane.


Another aspect of the present disclosure is directed to a linear actuator. The linear actuator includes a piston, a piston rod configured to connect the piston at each side thereof, an enclosed cylinder cavity configured to enclose the piston and a portion of the piston rod, and an apparatus configured to be mounted on the linear actuator and to reduce vibration of the linear actuator. The piston reciprocates within the cylinder cavity during operation of the linear actuator.





BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute part of this specification, together with the description, illustrate and serve to explain the principles of various exemplary embodiments.


For a better understanding of the present invention and to show how the same may be carried out in practice, reference will now be made to the accompanying drawings, in which:



FIG. 1 is a perspective schematic view of an exemplary embodiment of a vibration prevention assembly of the present invention, embodied on a free piston engine;



FIG. 2 is a schematic side view of the vibration prevention assembly of FIG. 1 in a first position of the piston of the engine;



FIG. 3 is a schematic side view of the vibration prevention assembly of FIG. 1 in a second position of the piston of the engine;



FIG. 4 is a schematic side view of the vibration prevention assembly of FIG. 1 in a third position of the piston of the engine;



FIG. 5 is a top view of an exemplary embodiment of a vibration prevention assembly of the present invention, embodied in a free piston engine;



FIG. 6 is a side view of the vibration prevention assembly of FIG. 5;



FIG. 7 is a view of the vibration prevention assembly of FIG. 6 showing the balancing arms in a first position of the piston;



FIG. 8 is a view of the vibration prevention assembly of FIG. 6 showing the balancing arms in a second position of the piston; and



FIG. 9 is a view of the vibration prevention assembly of FIG. 6 showing the balancing arms in a third position of the piston.





DETAILED DESCRIPTION

The present disclosure is generally directed to a vibration prevention apparatus (also referred to as a vibration prevention assembly herein) for reducing and/or cancelling vibrations generated in a linear actuator. The assembly can be used with any type of linear actuator. Particularly, the vibration prevention assembly according to the present disclosure may be used for preventing vibrations in free piston engines or linear engines.


The assembly comprises a multitude of balancing arms that counter balance the weight and momentum of the piston of the engine with respect to all symmetry planes and with respect to other systems that are connected to the engine, such as power generating units. The symmetry planes may include, for example, planes P, Q, and R as depicted in FIG. 1, which will be described in detail below.


Attention is drawn to FIGS. 1 to 9, which show a vibration prevention assembly 10 according to embodiments of the present invention. For a matter of simplicity, the vibration prevention assembly 10 will hereinafter be called “assembly”.


In general, vibration prevention assembly 10 can be used with any linear actuator. According to some embodiments of the present invention, vibration prevention assembly 10 is used for preventing vibrations in a free piston engine 12 in which vibration prevention assembly 10 is mounted thereon.


Free piston engine 12 includes a longitudinal axis A, a piston 14 connected to a piston rod 16 at each side thereof. Piston 14 may freely slide within a cylinder cavity 18 of free piston engine 12.



FIG. 5 depicts an exemplary embodiment of the vibration prevention assembly of the invention. In the exemplary embodiment depicted in FIG. 5, engine 12 may further include an air blower 40, a set of mounting arms 42, one or more linear electric generators 44, cooling fins 46, one or more fuel injectors 48, cross arms 50, spark plugs 52 (not shown in FIG. 5), and mounting bolts 54 (not shown in FIG. 5). Air blower 40 may be driven by a rotational movement produced by engine 12. Mounting arms 42 may be configured to mount air blower 40 to engine 12. Linear electric generators 44 may be configured to be driven by engine 12 to generate electricity. Fuel injectors 48 may be configured to provide fuel to engine 12. Cross arms 50 may be configured to connecting linear generators 44 and at least ono piston rod 16. Spark plugs 52 may be used to ignite a compressed fuel and air mixture gas. Mounting bolts 54 may be configured to mount assembly 10 to engine 12.



FIG. 6 depicts a side view of the exemplary embodiment of the vibration prevention assembly depicted in FIG. 5. Spark plugs 52 and mounting bolts 54 are depicted in FIG. 6.


Vibration prevention assembly 10 is symmetrical with respect to a vertical reference plane P that passes through the longitudinal axis A. In the embodiment shown, in FIG. 6, for example, vibration prevention assembly 10 is operable around an assembly axis B that passes through the longitudinal axis A, perpendicularly thereto, and perpendicularly to the vertical reference plane P.


According to a given embodiment of the present invention, vibration prevention assembly 10 comprises two sets of balancing arms 20. Each set of balancing arms 20 comprises two arms and is provided within an arms case 22.


Each balancing arm 20 typically comprises a mounting portion 24, which is in the form of a mounting opening 26 that is mounted on a driving shaft 28, a neck portion 30 extending radially outwardly from the mounting portion 24, and a weight portion 32 that extends radially outwardly from neck portion 30.


Each set of balancing arms 20 is driven by an electric motor that receives a signal from a sensor that senses the position of the piston 14. The electric motor may drive a pinion, having conical gears. The pinion may simultaneously drive two oppositely positioned and oppositely rotating conical gears.


The two conical gears rotating in opposite directions may form a portion of a set of balancing arms 20, that is, the two conical gears may be accounted as a portion of a counterweight comprising the set of balancing arms. The two sets of balancing arms 20 that are located at opposite sides of the reference plane P are mirror images of each other and, in this case, the reference plane P forms a symmetry plane.


The purpose of balancing arms 20 is to counter-balance the weight and momentum that piston 14 applies on free piston engine 12 while moving back and forth within cylinder cavity 18.



FIGS. 1-4 and FIGS. 7-9 depict only one set of balancing arms 20, however, some embodiments of the invention may incorporate multiple sets of balancing arms 20. In particular, vibration prevention assembly 10 may comprise another identical set of balancing arms (not shown) that are a mirror image of the depicted balancing arms 20 with respect to the symmetry plane P. The balancing arms positions in FIGS. 2, 3, and 4 correspond to the balancing arms positions shown in FIGS. 7, 8, and 9, respectively. Reference is made now to FIGS. 2-4, which depict schematic representation of a “transparent” engine so that the principle of operation may be easier described. Although FIGS. 7-9 depict a free piston engine having additional components or elements compared with the corresponding FIGS. 2-4, the principle of operation of vibration prevention assembly 10, as depicted in FIGS. 7-9, is similar, and thus, is not repeated herein.


As shown in FIG. 2, when piston 14 is at its extreme left position, the balancing arms 20 are at their extreme right position, thus balancing the piston with respect to a first plane Q that passes through the assembly axis B and is perpendicular to the longitudinal axis A and to the reference plane P. The balancing of the piston momentum to arrive to this position is counter-balanced by the momentum created by balancing arms 20 in order to get to this position.


As can be seen in FIG. 1, two balancing arms 20 of a given set of balancing arms are located at different planes, i.e., they are differently distanced from the reference plane P. However, in the position shown in FIG. 2, since the two balancing arms 20 are positioned away from the position of piston 14 with respect to the first plane Q, in a side view of assembly 10 two balancing arms 20 overlap each other and therefore only one is shown.


Further in some embodiments, the two oppositely positioned and oppositely rotating conical gears driven by a pinion may each drive one of two balancing arms 20 of a given set of balancing arms such that One of two balancing arms 20 rotates clockwise and the other of two balancing arms 20 rotates counterclockwise to reach the overlap position as depicted in FIG. 2 from a position of two balancing arms 20 depicted in FIG. 1.


As shown in FIG. 3, when piston 14 is at its middle position, balancing arms 20 are at their middle position, i.e., parallel to the first plane. Q. However, if balancing arms 20 would have been overlapping each other, they would have raised a momentum and create a torque around a horizontal plane R that passes through the longitudinal axis A, through the assembly axis B, and is perpendicular to the reference plane P and the first plane Q. For this reason, and in order to prevent built-up of any unwanted torques, in the middle position of the balancing arms 20 they are positioned in opposite directions with respect to the horizontal plane R.


Further in some embodiments, the two oppositely positioned and oppositely rotating conical gears driven by a pinion may each drive one of two balancing arms 20 of a given set of balancing arms such that one of two balancing arms 20 rotates clockwise and the other of two balancing arms 20 rotates counterclockwise to reach the opposite direction position as depicted in FIG. 3 from a position of two balancing arms 20, as depicted in FIG. 2, for example.


As shown in FIG. 4, when the piston is at its extreme right position, balancing arms 20 are at their extreme left position thus balancing the piston with respect to the first plane Q.


Further in some embodiments, the two oppositely positioned and oppositely rotating conical gears driven by a pinion may each drive one of two balancing arms 20 of a given set of balancing arms such that one of two balancing arms 20 rotates clockwise and the other of two balancing arms 20 rotates counterclockwise to reach the position depicted in FIG. 4 from the position of two balancing arms 20 depicted in FIG. 3, for example.


As shown in FIGS. 2 and 4, two balancing arms 20 of a given set of balancing arms 20 move from their extreme right position (FIG. 2) to their extreme left position (FIG. 4), or vice versa, which may be referred to as reciprocation of balancing arms 20 herein.


Thus, as effectively shown and explained, the position and momentum of piston 14 at any given moment is counter-balanced by balancing arms 20 in the following manner: (a) all of the balancing arms 20, four in an exemplary embodiment of the invention, counter-balance the piston with respect to the first plane Q, (b) each set of balancing arms 20 are counter-balanced with respect to the horizontal plane R, meaning a first balancing arm 20 counter-balances a second balancing arm 20, and, (c) each pair of balancing arms 20 counter-balance the other pair of balancing arms 20 with respect to the vertical reference plane P.


By the above shown construction and operation, assembly 10 may effectively eliminates any vibrations during the operation of free piston engine 12.


The vibration prevention assembly of the present invention is not limited to be used with a free piston engine only, and it may be used with other linear actuators, such as mechanisms of machines that have a linear back and forth movement.


If desired, the driving shaft of the pinion may be used as a shaft of a turbine that is used for supplying the engine with forced air. In this case, the rotation of the turbine creates a dynamic balance to the entire structure that the turbine is connected to.


The vibration prevention assembly may comprise other numbers of balancing arms, depending on the structure of the linear actuator and its connected systems.


The balancing arms may have different shapes than the shape described above or depicted in the figures to suit different design needs.


The balancing arms may be integrally formed with their driving shaft, or may be separately connected thereto.


The different sets of balancing arms do not have to be driven by different electric motors, if desired, all the balancing arms may be driven through a single electric motor.


It should be noted that directional terms appearing throughout the specification and claims, e.g., “forward,” “rear,” “upper,” “lower,” etc., are used as terms of convenience to distinguish the location of various surfaces relative to each other. These terms are defined with reference to the figures, however, they are used for illustrative purposes only, and are not intended to limit the scope of the invention.


Although the present invention has been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the spirit or scope of the invention as hereinafter described.

Claims
  • 1. An apparatus for vibration reduction in a linear actuator, comprising: one or more sets of counterweights, each set comprising one or more counterweights;one or more enclosures configured to receive the one or more sets of counterweights; anda driving shaft configured to receive the one or more sets of counterweights mounted thereon;wherein: the one or more sets of counterweights are disposed symmetrically with respect to a plane that extends perpendicularly and longitudinally through a longitudinal axis of the linear actuator;the driving shaft extends perpendicularly and transversely through the longitudinal axis and the plane, and the driving shaft is configured to be driven separately from a reciprocating shaft of the linear actuator; andeach counterweight comprises: a mounting portion configured to mount the counterweight to the driving shaft;a neck portion configured to extend radially outwardly from the mounting portion; anda weight portion configured to extend radially outwardly from the neck portion.
  • 2. The apparatus of claim 1, wherein the linear actuator comprises: a piston;a piston rod configured to connect the piston at each side thereof: andan enclosed cylinder cavity configured to enclose the piston and a portion of the piston rod;wherein: the longitudinal axis is a central longitudinal axis of the piston rod;the piston reciprocates within the enclosed cylinder cavity; andthe driving shaft is disposed on a plane that the piston is configured to cross as the piston reciprocates.
  • 3. The apparatus of claim 2, wherein the one or more sets of counterweights are positioned outside of the cylinder cavity.
  • 4. The apparatus of claim 1, wherein the apparatus further comprises one or more electric motors configured to drive the one or more sets of counterweights.
  • 5. The apparatus of claim 1, wherein a first portion counterweight of the one or more sets of counterweights rotates clockwise and a second portion counterweight of the one or more sets of counterweights rotates counterclockwise.
  • 6. A linear actuator, comprising: a piston:a piston rod configured to connect the piston at each side thereof;an enclosed cylinder cavity configured to enclose the piston and a portion of the piston rod; andan apparatus configured to be mounted on the linear actuator and to reduce vibration of the linear actuator;wherein the piston reciprocates within the enclosed cylinder cavity back and forth across a first plane, and the apparatus is configured to balance the piston with respect to the first plane;the apparatus comprises: one or more sets of counterweights, each set comprising one or more counterweights;one or more enclosures configured to receive the one or more sets of counterweights; anda driving shaft configured to receive the one or more sets of counterweights mounted thereon;wherein: the one or more sets of counterweights are disposed symmetrically with respect to a second plane that extends perpendicularly and longitudinally through a longitudinal axis of the linear actuator; andthe driving shaft extends perpendicularly and transversely through the longitudinal axis and the second plane; andwherein the apparatus further comprises one or more electric motors configured to drive the one or more sets of counterweights.
  • 7. The linear actuator of claim 6, wherein the one or more sets of counterweights are positioned outside of the enclosed cylinder cavity.
  • 8. The linear actuator of claim 6, wherein each counterweight comprises: a mounting portion configured to mount the counterweight to the driving shaft,a neck portion configured to extend radially outwardly from the mounting portion; anda weight portion configured to extend radially outwardly from the neck portion.
  • 9. The linear actuator of claim 6, wherein a first portion counterweight of the one or more sets of counterweights rotates clockwise and a second portion counterweight of the one or more sets of counterweights rotates counterclockwise.
  • 10. The apparatus of claim 6, further comprising: a driving shaft configured to receive the one or more sets of counterweights mounted thereon, the driving shaft configured to be driven separately from a reciprocating shaft of the linear actuator.
  • 11. A method for vibration reduction in a linear actuator, comprising: providing a vibration reduction apparatus configured to be mounted on the linear actuator and to reduce vibration of the linear actuator; andmounting the apparatus onto the linear actuator;wherein: the linear actuator comprises: a piston;a piston rod configured to connect the piston at each side thereof; andan enclosed cylinder cavity configured to enclose the piston and a portion of the piston rod, the piston configured to reciprocate within the enclosed cylinder cavity; andwherein the apparatus comprises: one or more sets of counterweights disposed symmetrically with respect to a plane that extends perpendicularly and longitudinally through a longitudinal axis of the linear actuator, each set comprising one or more counterweights;one or more enclosures configured to receive the one or more sets of counterweights; anda driving shaft extending perpendicularly and transversely through the longitudinal axis and the plane and configured to receive the one or more sets of counterweights mounted thereon,the method further comprising counter-balancing the piston with the one or more sets of counterweights with respect to a plane that the piston reciprocates back and forth across; andproviding one or more electric motors configured to drive the one or more sets of counterweights.
  • 12. The method of claim 11, wherein mounting the apparatus onto the linear actuator comprises: positioning the one or more sets of counterweights outside of the enclosed cylinder cavity.
  • 13. The method of claim 11, further comprising: rotating a first portion counterweight of the one or more sets of counterweights clockwise; androtating a second portion counterweight of the one or more sets of counterweights counterclockwise.
CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national phase entry under 35 U.S.C. § 371 from International Application No. PCT/IB2016/001678, flied Oct. 20, 2016, which claims the benefit of priority based on U.S. Provisional Patent Application No. 62/243,677 filed on Oct. 20, 2015, to both of which this application claims the benefit of priority, and the entirety of the subject matter of both of which is incorporated herein by reference.

PCT Information
Filing Document Filing Date Country Kind
PCT/IB2016/001678 10/20/2016 WO 00
Publishing Document Publishing Date Country Kind
WO2017/068427 4/27/2017 WO A
US Referenced Citations (85)
Number Name Date Kind
1040472 Wade Oct 1912 A
1707035 Wurfel Mar 1929 A
1720504 Williams Jul 1929 A
1755673 Solenberger Apr 1930 A
1764815 Williams Jun 1930 A
1796882 Bowers Mar 1931 A
2028331 Janicke Jan 1936 A
2187979 Malpas Jan 1940 A
2392052 Matheisel Jan 1946 A
2399683 Loeb May 1946 A
2407790 Le Tourneau Sep 1946 A
2421164 Senkowski May 1947 A
2831738 Marien Apr 1958 A
2874012 Stern Feb 1959 A
3146940 McCrory et al. Sep 1964 A
3358656 Panhard Dec 1967 A
3365879 Panhard Jan 1968 A
3369733 Campbell Feb 1968 A
3465161 Cutkosky Sep 1969 A
3610217 Braun Oct 1971 A
3791227 Cherry Feb 1974 A
3797466 Nambu Mar 1974 A
3914574 Hill et al. Oct 1975 A
4156410 Ramsey May 1979 A
4385597 Stelzer May 1983 A
4414927 Simon Nov 1983 A
4489554 Otters Dec 1984 A
4653274 David Mar 1987 A
4658768 Carson Apr 1987 A
4803960 Köppen Feb 1989 A
4831972 Barnwell May 1989 A
4854218 Stoll Aug 1989 A
4876991 Galitello, Jr. Oct 1989 A
4932373 Carson Jun 1990 A
4979476 Islas Dec 1990 A
5022157 Chang Jun 1991 A
5123245 Vilenius et al. Jun 1992 A
5158046 Rucker Oct 1992 A
5285752 Reed et al. Feb 1994 A
5351659 Chao Oct 1994 A
5676097 Montresor Oct 1997 A
5710514 Crayton et al. Jan 1998 A
5816202 Montresor Oct 1998 A
6035637 Beale et al. Mar 2000 A
6065438 Kiesel May 2000 A
6164250 Bailey et al. Dec 2000 A
6170442 Beale Jan 2001 B1
6199519 Van Blarigan Mar 2001 B1
6240828 Fujimoto Jun 2001 B1
6298941 Spadafora Oct 2001 B1
6443107 Mendler Sep 2002 B1
6467397 Fuchs et al. Oct 2002 B1
6722322 Tse Apr 2004 B2
6854429 Gelfand Feb 2005 B2
6948459 Laumen et al. Sep 2005 B1
7032548 Tusinean Apr 2006 B2
7194989 Hallenbeck Mar 2007 B2
7207299 Hofbauer Apr 2007 B2
7318506 Meic Jan 2008 B1
7331407 Stirm Feb 2008 B2
7412949 Cillessen et al. Aug 2008 B1
9010287 Morreim Apr 2015 B2
9206900 Smith et al. Dec 2015 B2
20020189433 Unger et al. Dec 2002 A1
20040244765 Elmer Dec 2004 A1
20050284426 Tusinean Dec 2005 A1
20060157003 Lemke et al. Jul 2006 A1
20060232268 Arns, Jr. et al. Oct 2006 A1
20070017684 Stirm et al. Jan 2007 A1
20080251050 Jacobsen et al. Oct 2008 A1
20090114391 Smith, IV et al. May 2009 A1
20110073419 Matsuzaki et al. Mar 2011 A1
20110239642 Schwiesow et al. Oct 2011 A1
20120160190 Klöpzig Jun 2012 A1
20120192438 Aoki et al. Aug 2012 A1
20120266842 Cockerill Oct 2012 A1
20120280513 Cockerill Nov 2012 A1
20130276740 Wandrie et al. Oct 2013 A1
20130298874 Sun et al. Nov 2013 A1
20140116389 Khurgin May 2014 A1
20150114352 McAlister et al. Apr 2015 A1
20160208686 Gadda et al. Jul 2016 A1
20170016327 Yaakoby Jan 2017 A1
20170044975 Yaakoby Feb 2017 A1
20190011011 Higuchi Jan 2019 A1
Foreign Referenced Citations (17)
Number Date Country
3149930 Aug 1982 DE
3347859 Jun 1985 DE
3518982 Nov 1986 DE
4136331 May 1992 DE
4447040 May 1996 DE
20 2006018097 Jun 2008 DE
102008004879 Jul 2009 DE
1 437 474 May 1996 FR
337248 Oct 1930 GB
602310 May 1948 GB
2183726 Jun 1987 GB
2232718 Dec 1990 GB
2353562 Feb 2001 GB
S6238833 Feb 1987 JP
63-192916 Oct 1988 JP
2 500 905 Dec 2013 RU
WO 2015155912 Oct 2015 WO
Non-Patent Literature Citations (4)
Entry
International Search Report and Written Opinion dated Mar. 31, 2017, in International Application No. PCT/IB2016/001678 (10 pgs.).
Jan Ridders, “Dual 2stroke model engine,” available at URL: https://www.youtube.com/watch?v=gLwHEUJ752s, uploaded May 22, 2013.
Extended European search report in Application No. 16823945.7-1004/3322884 PCT/IB2016001189 dated Jan. 24, 2019.
European examination report in Application No. 15782938.3-1004 dated Oct. 24, 2019.
Related Publications (1)
Number Date Country
20200248778 A1 Aug 2020 US
Provisional Applications (1)
Number Date Country
62243677 Oct 2015 US