US3563316A

US3563316A - Low profile resonant plow

Info

Publication number: US3563316A
Application number: US714659A
Authority: US
Inventors: Howard L Shatto
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1968-03-20
Filing date: 1968-03-20
Publication date: 1971-02-16
Anticipated expiration: 1988-02-16

Abstract

A sonically-driven resonator of a resonant plow or trenching tool is formed so that at least its major dimension extends in a plane substantially parallel to the surface of the earth formation being plowed and extends substantially along the direction of travel so as to reduce the vertical dimension thereof and any interference with overhead structures.

Description

United States Patent [72] Inventor Howard L. Slutto Refel'gncgs Cit d 2 A I N 2}: UNITED STATES PATENTS 1 g fi, 1968 3,387,668 6/1968 Mathers 172/719 Patented 1 Lamb [73] Assignee Shell 01 Company 3,231,025 l/1966 Bodine 172/40 New York N Y 3,339,641 9/1967 Carter 172/40 3,398,798 8/1968 Shelton 172/1 3,461,970 8/1969 Bodine 172/1 3,461,969 8/1969 Bodine, Jr. 172/1 PrimaryExaminer-Robert E. Pulfrey 54 w PR 580" Assistant Examiner-Clifford D. Crowder l 3 gg no. Low Attorneys-J. H. McCarthy and Freling E. Baker [52] US. Cl. 172/40,

299/14, 173/49, 37/ 193, 172/773, 37/98 ABSTRACT: A sonically-driven resonator of a resonant plow [51] Int. Cl. A011: /00, or trenching tool is formed so that at least its major dimension 1321537120 extends in a plane substantially parallel to the surface of the [50] iieldofselrch 172/1, 699, earth formation being plowed and extends substantially along 763, 88, 776, 719, 37/( VD), 193, 195; the direction of travel so as to reduce the vertical dimension til/72.5, 72.6; 173/49; 299/14, 37 thereof and any interference with overhead structures.

I6 I '40 1 I l7 1. h 15b 21 I9 20 Q 7 15 o 1 1] 22 |3 v PATENTED mnmsm 3,563,316

' nm 1 OF 2 FIG. I

INVENTORI H. SHATTO BYI HIS ATTORINEY LOW PROFILE RESONANT now BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to the plowing of trenches and pertains more particularly, to the application of sonic energy to a plowing or trenching tool for forming trenches in which to lay cables. pipes and similar structures.

2. Description of the Prior Art The potential benefits of applying sonic energy to cable plows and other earth working tools have been known for some time. These proposed prior art devices, however, utilize an enormous resonant member or bar to transmit the energy from the oscillator to the plow blade. A major disadvantage of these prior art devices is that the resonator bar becomes too large and bulky when designed for deep trenching. This is because the nodes (points of minimum amplitude of velocity and motion) of the bar must be'positioned above the surface of the ground for most efficient operation. The resonator, an elongated rectangular bar in these prior devices, will vibrate transversely as a free-free bar with two nodes or points of minimum vibration. These nodes will be located at points about one-quarter of the length of the bar from each end. Therefore, to keep the lower node of such a resonant bar above the ground for a three foot deep trench, a bar of uniform cross section must be greater than 4 times 3 or greater than l2 in length. Such a resonant bar would extend greater than 9 vertically into the air when in the operative position or greater than 12 when in the inoperative position. Such an apparatus is bulky and difficult to handle and limited in its use because of its interference with overhanging structures such as tree branches, buildings, and power lines. Another major difficulty with such prior art devices is that the necessary positioning'of the sonic vibration generator on the resonant bar is such that it cannot be readily driven from the power takeoff of a towing vehicle. The sonic vibration generator must be placed at or near an antinode for best results. These antinodes appear at the ends and at the center of the bar. Thus, the sonic vibration generator must be connected to the bar at its center or at its upper end.

Summary of the Invention It is the primary object of the present invention to overcome the above objections of the prior art by providing a resonant so'nic trencher that is compact and easy to manipulate.

A further object of the present invention is to provide a resonant sonic trencher formed such that the sonic generator may be positioned thereon for direct drive from the powertakeoff of a towing vehicle.

In accordance with the invention the resonator bar of a resonant sonic plow is formed such that the axis of a major portion thereof extends substantially along the direction of travel and in a substantially horizontal plane in order to form an apparatus having a very low profile. Other significant aspects of the invention include forming the resonator bar for maximum 0. or sharpness of resonance, per pound of material.

Brief Description of the Drawing ment of the present invention;

. FIG. 6 is a cross-sectional view taken along line 6-6 of the apparatus of FIG. I

FIG. 7 is a schematic elevational view of still another embodiment of the present invention;

embodi- FIG 8 IS a schematic elevational view of a further embodiment of the apparatus of the present invention;

FIG 9 is a schematic elevational view of a still further embodiment of the present invention.

In order to facilitate the comprehension of the principles involved in the present invention, an analogy may be drawn between the acoustically vibrating circuit and an equivalent electrical circuit. Such an analogy iswell known to those skilled in the art and is described in Chapter 2 of "Sonics" by Hueter and Bolt, published in 1955 by John Wiley and Sons, In this analogy, mechanicalforce F is equated to electrical voltage E; velocity of vibration u is equated with electrical current i,mechanical compliance Cm is equated with electrical capacitance Cennass M is equated with electrical inductance -L;mechanic'al resistance (friction) Rm is equated with electrical resistance R;and mechanical impedance Zm is equated with electrical impedance Ze.Thus, it can be shown that if a member is elastically vibrated by means of an acoustical sinusoidal force F0 sin an, to being equal to 21r times the frequency of vibration, that In such a system, the peak resonant condition will exist where wM is equal to l/mCm, and the effective mechanical impedance Zm is reduced to its minimum value which is simply the mechanical resistance, and the reactive impedance components 10M and I/wCM will cancel each other out. At resonance, the velocity of vibration u will be at the maximum effective power factor of unity, and energy is most effectively delivered to a load to which the system may be coupled.

Description of Preferred Embodiments In FIGS. 1 and 2 are illustrated a preferred embodiment of the invention which comprises a self-propelled transport vehicle 11 having prime mover means 12 coupled through transmission means in a conventional manner to traction wheels 13. In this embodiment the resonator assembly comprises a resonant member 14 in the shape of an inverted U which is pivotally supported at its nodal points by

pins

15 and 16 to link

members

17 and 18 which are connected to

shafts

19 and 20 which are connected in a conventional manner to rotatable means on vehicle 11 for raising and lowering the resonator assembly. The U-shaped for the resonator bar approaches that of a tuning fork but may be constructed so as to have two vibrational nodes as in a straight rectangular rather than one asin the tuning fork. This construction provides two places at which the bar may be connected to supporting and manipulating framework or mechanism. Actually, the true nodal points for a bar like that illustrated has been found to appear somewhere above the bar. However, for the purposes of this illustration, points designated on the bar will be selected for the attachment of supporting structure. A sonic vibration generator 21 is connected in any suitable manner to the forward leg of the resonator bar 14 and is driven by means of a telescoping cardon shaft 22 from power-takeoff shaft 23 of the prime mover means 12 of vehicle 11. A trenching tool 24, whichls preferably constructed of a good grade of tool steel and having a point 25, is coupled to the trailing leg of the resonator bar 14. The resonant member 14 may be a laminated structure constructed of a number of U-shaped plates l4a,14b,l4c having tapered progressively shorter legs. The plates may be connected together by:press-fitting bolts or rivets in holes arranged along the centerline of the plate. This is the area of In the modification illustrated in FIGS. 3 and 4, the resonant member 26 is shown as being formed in substantially the same U-shaped configuration as that of FIG. 1, but with a different cross-sectional configuration. The substantially H or I crossi sectional configuration of this modification permits the attainment of an even higher Q for a given pound of material (generally steel) in the resonator. This is because the stress in the bar varies from about zero at its center to a maximum at its outer surfaces when the bar vibrates in its lateral mode. In other words, the outer grains are highly stressed, while the center grains receive very little stress. Thus, only a relatively thin web 26a is needed to connect the

flanges

26c and 26d together. This construction places the maximum amount of material in the area of maximum stress. The resonant member 26 is pivotally connected at the nodes by means of pairs of

links

27 and 28 to a raising and lowering mechanism on a transport vehicle such as that shown in FIG. 1. A sonic vibration generator 29 is rigidly connected in any suitable manner such as by bolting or clamping to the forward leg 26a of the resonant member 26. The sonic vibration generator 29 is schematically illustrated as a single bar orbiting rotor type, buy may be any type as discussed above. The sonic generator is driven by means of drive shaft 30 from a powertakeoff shaft such as that of the prime movervehicle. It is also apparent that the sonic vibration generator may be coupled to the resonant member at other points to transfer the energy thereto. For example, the sonic generator may be coupled at the center of the midsection, or at the lower end of the trailing leg 26b.A cutting or trenching tool 31 is attached in any suitable manner such as by riveting or bolting between plates 32 to the rear or trailing leg 26b of the resonant member 26.

A further embodiment of the present invention is illustrated in FIGS. and 6. In this embodiment the resonant member 33 has a boxlike cross-sectional configuration with thick upper and lower walls and relatively thin sidewalls. This construction obtains relatively the same benefits as the embodiment of FIGS. 3 and 4. In this embodiment a pair of

thick plates

33c and 33d are connected together by a pair of thin plates 33s and 33f. The resonant member is supported at its nodes from a transport vehicle in any suitable manner, as by pivoting

links

34 and 35. A sonic vibration generator 36 is connected in any suitable manner, as by clamping or bolting to the trailing leg 33b of the resonant member. The sonic vibration generator is illustrated as being fluid driven with fluid supply and exhaust conduits 37 and 38, respectively. A counterweight 39 is attached to the forward leg of the resonant member to counterbalance the system. A cutting or trenching tool 40 is connected to the rear leg 33b of the resonant member. This arrangement provides a more direct drive of the trenching tool from the sonic vibration generator with the resonator bar storing energy to smooth out the pulses.

The modification of FIG. 7 provides a rugged and economical arrangement which maintains a low profile where the linear or horizontal space is not a problem. In this embodiment the resonant member 41 is in the form of elongated rectangular bar having its axis extending along the predetermined direction of travel and substantially parallel to the surface of the earth formation being cut. A cutting or trenching tool 42 extends downward from the resonant member at a point near one node for engagement with the earth formation. The trenching tool is formed or mounted on the resonant member such that its point travels in an are about the node. The point of the trenching tool may be positioned such that it reaches a point directly below the node at its forwardmost point of travel for most ordinary soils. For chipping and breaking layers of rock or pavement, it may be desirable that this forwardmost point of travel be forward of the point directly below the node so that the point travels slightly upward toward the end of its forward travel. A sonic vibration generator 43 is connected to the resonant member at substantially at a point about halfway between the nodes. It is also to be understood that the generator may also be connected to the resonant member at either end. The resonant member 4] is pivotally supported at its nodes by suitable means such as link means 44 connected to a suitable transport vehicle. The wave patterns 45 graphically Illustrate the relative amplitude oi vibration of various points along the resonant member. As illustrated, the nodes normally go through very minor amplitudes of vibration.

In FIG. 8 is illustrated a modification wherein the resonant member 46 is curved so as to retain two seminodal areas and having its major dimension extending along the direction of travel and substantially parallel to the surface of the earth formation. One end of the member is curved downward to present a portion thereof for engagement with the earth formation to form a cutting or trenching tool. A sonic vibration generator 47 is mounted on the forward end of the resonant member to transmit sonic vibrations thereto. The apparatus may be supported from a suitable transport vehicle by like means 48 pivotally connected to the nodal areas of the resonant member.

A further embodiment of the invention is illustrated in FIG. 9 in which the resonant member 49 has its major dimension extending substantially along the direction of travel and its forward end extending downward on which is formed or connected a cutting or trenching tool for engagement with an earth formation. A sonic vibration generator 50 is connected to the other end of the resonator bar to transmit sonic vibrations thereto. The apparatus is supported from a suitable transport vehicle by link means 51 connected to the nodal points of the resonant member.

Various modifications may be made in the construction and arrangement of the apparatus without departing from the scope of the invention as defined in the appended claims.

lclaim:

1. In a sonic earth plow mounted on a carrier vehicle for movement therewith along a predetermined direction of travel:

an elastic resonant member comprising an elongated midsection, said resonant member having its midsection extending along said direction of travel;

a pair of tapered legs extending downward from said midsection to form a substantially U-shaped configuration; earth cutting means connected to the end of one of said legs; and

a vibration generator connected to said resonant member on one of its said legs, whereby vibrations created by said vibration generator are transmitted to said earth cutting means through said elastic resonant member to thereby vibrate said earth cutting means in a plane coextensive with said direction of travel.

2. The apparatus of claim 1 wherein:

said cutting means is connected to the end of one of said legs; and

said vibration generator is connected to the other leg of said resonant member.

3. The apparatus of claim 1 wherein said resonant member comprises:

a plurality of relatively thin members connected together to form a laminated structure.

Claims

1. In a sonic earth plow mounted on a carrier vehicle for movement therewith along a predetermined direction of travel: an elastic resonant member comprising an elongated midsection, said resonant member having its midsection extending along said direction of travel; a pair of tapered legs extending downward from said midsection to form a substantially U-shaped configuration; earth cutting means connected to the end of one of said legs; and a vibration generator connected to said resonant member on one of its said legs, whereby vibrations created by said vibration generator are transmitted to said earth cuttIng means through said elastic resonant member to thereby vibrate said earth cutting means in a plane coextensive with said direction of travel.

2. The apparatus of claim 1 wherein: said cutting means is connected to the end of one of said legs; and said vibration generator is connected to the other leg of said resonant member.

3. The apparatus of claim 1 wherein said resonant member comprises: a plurality of relatively thin members connected together to form a laminated structure.