TORSION BAR FOR RAISING AND LOWERING A TARGET
United States Patent 3733073
A target raising and lowering mechanism employs a torque tube and torsion r combination to provide weatherproof housing for its electric motor and reduction gear means while also storing energy in the torsion bar during lowering of a target for later use during raising of the target.
US Patent References:
Target elevating mechanism
Mongello - September 1957 - 2805066
Target
Cauble - May 1962 - 3034788
Torsion bar spring draft sensing means for implement hitch mechanism
Brudnak - March 1966 - 3241620
Ball-pitching machine with trajectory-controlling means
Laird - July 1966 - 3261340
Target elevating mechanism
Mongello - September 1957 - 2805066
Target
Cauble - May 1962 - 3034788
Torsion bar spring draft sensing means for implement hitch mechanism
Brudnak - March 1966 - 3241620
Ball-pitching machine with trajectory-controlling means
Laird - July 1966 - 3261340
Application Number:
05/236390
Publication Date:
05/15/1973
Filing Date:
03/20/1972
View Patent Images:
Export Citation:
Assignee:
The United States of America as represented by the Secretary of the Navy (Washington, DC)
Primary Class:
Other Classes:
267/154
International Classes:
F41J7/00; F41J7/00
Field of Search:
273/12S,12.1R,12.1C,12.1E,12.2R,12.2S,105.6,105.2 124/7
Primary Examiner:
Pinkham, Richard C.
Assistant Examiner:
Siskind, Marvin
Claims:
What is claimed is
1. A mechanism for moving a target between raised and lowered positions, said mechanism comprising:
2. A mechanism as defined in claim 1, and wherein:
3. A mechanism as defined in claim 2, and further comprising:
4. A mechanism as defined in claim 3, and wherein:
5. A mechanism as defined in claim 4, and wherein:
1. A mechanism for moving a target between raised and lowered positions, said mechanism comprising:
2. A mechanism as defined in claim 1, and wherein:
3. A mechanism as defined in claim 2, and further comprising:
4. A mechanism as defined in claim 3, and wherein:
5. A mechanism as defined in claim 4, and wherein:
Description:
BACKGROUND OF THE INVENTION
This invention relates to target devices, and more particularly to an improved target raising and lowering mechanism suitable for use with targets of substantial size, say seven by nine feet, in the training, for example, of tank gunners.
Target raising and lowering mechanisms have been proposed heretofore which are electrically driven and operate through gears, levers and the like to move targets of plywood or the like between horizontal and vertical plane positions. Such mechanisms are typically used in military field training maneuvers wherein the mechanisms are exposed to extremes of weather including high winds, rain, snow, and heat, as well as shock, dirt, and flying debris from explosions of training rounds and the like. Experience with the prior mechanisms has shown that such conditions result in so many mechanical and electrical failures that the usefulness of the devices was severely limited.
Moreover, such devices have been expensive, bulky, difficult to maintain, and have required greater electrical power for operation than is desirable for field use where batteries and/or portable electric generators are the source.
SUMMARY OF THE INVENTION
With the foregoing in mind, it is a principal object of this invention to provide an improved electrically driven target raising and lowering mechanism which has great mechanical and electrical reliability even under the adverse conditions set forth above.
Another object of the invention is to provide an improved target positioning mechanism which has a low profile, is reasonably economical to manufacture, and has modest electrical power requirements.
As another object this invention aims to provide a mechanism of the foregoing character which utilizes a torque tube and torsion bar combination to store energy while the target is being lowered and to use that energy when the target is being raised.
Yet another object is to utilize the torque tube as a weatherproof housing for a drive motor and a harmonic gear drive.
The invention may be further said to reside in certain novel combinations, constructions, and arrangements of parts whereby the foregoing objects and advantages are achieved, as well as others which will become apparent from the following detailed description of a preferred embodiment when read in conjunction with the accompanying sheets of drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a target raising and lowering mechanism embodying the present invention, and having some moveable parts thereof shown in broken line positions:
FIG. 2 is a view on an enlarged scale, partly in elevation, partly in section, and with some parts broken out, taken substantially along line 2 -- 2 of FIG. 1; and
FIG. 3 is a sectional view taken substantially along line 3 -- 3 of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the form of the invention illustrated in the drawings and described hereinafter, as an example, there is provided a target raising and lowering mechanism generally indicated at 10 in FIG. 1 and which serves to move a target T in both directions between a raised or full line position and a lowered position as shown in phantom. The mechanism 10 comprises a frame including an aluminum torque tube 12 having plates 14 and 16 welded to opposite ends thereof. The plate 14 closes the end of the tube 12 to which it is welded and also provides a flange to which an angle member 18 is bolted to serve as a transverse support base. The plate 16 does not close the end of the tube 12 to which it is welded but 16 serves as a flange to which is bolted a housing 24 for a final gear drive later described in detail. A transverse support base in the form of an angle member 20 is bolted to a plate portion 24a of the housing 24.
Mounted within the torque tube 12 is a reversible electric motor 30 (FIG. 2) which is directly coupled to a reduction gear 32 of the harmonic type. In the present example the motor 30 operates at 1,725 RPM, and the harmonic reduction gear 32 reduces that by 180 to 1. The reduction gear therefore drives at a rate of 9.58 RPM at its output shaft 32a in the plate 24a forming part of that housing.
The plate 24a serves to close the end of the torque tube 12 and a motor and harmonic gear securing collar 36 which is secured to an adapter ring 38. The housing 24 further comprises an annular member 24b welded to the plate 24a and laterally offset from the axis of the tube 12. A circular cover member 24c is secured to the annular member 24b as by screws 40, and this cover member carries a plain bearing 42 which receives the outer end of the harmonic drive output shaft 32a.
Fixed on the shaft 32a for rotation therewith is a pinion gear 44 which is in mesh with a gear or gear sector 46. The outer end of the shaft 32a is conveniently supported by a plain bearing 45 carried by the housing cover 24c, while the gear sector 46 is provided with a central boss 48 which is conveniently journalled in a plain bearing 50 carried by the housing cover 24c.
The gear sector 46 and boss 48 thereof are provided with a square central aperture through which extends one squared end portion 52a of a torsion bar 52, which runs parallel to the tube 12. The squared end portion also extends through a bearing 53 in the plate 24a and through an opening in the cover 24c to the exterior of the latter.
The opposite end of the torsion bar 52 has a squared portion 52b extending through a corresponding opening in the plate 14 and reinforcing weldment 14a, and a round, terminal portion 52c extending through and beyond a spacer 54.
A pair of arms 56 and 58 are mounted on opposite ends of the torsion bar 52, the arm 58 having a squared opening receiving the square portion extending beyond the cover 24c. The arm 58 is spaced from the cover by a spacer 59. The arm 56 is rotatable freely on the projecting round end portion 52c of the torsion bar. A box member 60 interconnects the arms 56 and 58 so that they are required to move in unison about the axis of the torsion bar. The arms 56 and 58 have channels formed in the outer surfaces thereof to receive struts or legs 62 of a target supporting clamp 64 in which a target T is removably secured.
First and second limit switches 70 and 72 are mounted through the plate 24a with their operating plungers directed inwardly of the housing 24 for actuation by a cam surface 74 carried by the gear sector 46. These limit switches are electrically connected into a control circuit (not shown) for the electric motor 30 and serve to limit the up and down positions to which the target T is moved.
The union between the plate 24a of the housing 24 and the tube 12 is provided with an elastomeric sealing ring 80 of the type referred to as an O-ring, whereby the motor 30 and reduction gearing 32 are effectively protected against intrusion of dirt and moisture. Sealing rings are also provided as shown at 82 between the cover 24c and member 24b, at 84 and 86 between the pinion 44 and the housing 24, and also at 88 and 90 between the gear sector 46 and the housing 24. The housing 24 is preferably charged with a quantity of grease or oil through a suitable fitting (not shown).
A plurality of ground anchors, one of which is shown at 90 in FIG. 2, may be provided to secure the angle support members 18 and 20 to the ground. These anchors are preferably of the auger type and comprise a block 90a which overlies a portion of the support member, a vertical shaft 90b journalled in the block, an auger plate 90c, and a cross-bar 90d for rotating the shaft to screw the auger plate into the ground.
In operation of the mechanism 10, when the target T is hit a control circuit is actuated to energize the motor 30 in a direction which causes the pinion 44 to drive the gear sector 46 so as to lower the target toward the broken line position of FIG. 1. When that position is attained the switch 72 is actuated causing the motor 30 to be deenergized until the control circuit re-energizes it in the reverse direction.
It will be recognized that during lowering of the target the torsion bar 52 will be twisted or "wound-up," thereby storing potential energy derived in part from the change of position of the target mass. When the motor 30 is energized in the reverse direction to raise the target, the torsion bar unwinds and contributes the stored energy to the job of moving the target to the raised position.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
This invention relates to target devices, and more particularly to an improved target raising and lowering mechanism suitable for use with targets of substantial size, say seven by nine feet, in the training, for example, of tank gunners.
Target raising and lowering mechanisms have been proposed heretofore which are electrically driven and operate through gears, levers and the like to move targets of plywood or the like between horizontal and vertical plane positions. Such mechanisms are typically used in military field training maneuvers wherein the mechanisms are exposed to extremes of weather including high winds, rain, snow, and heat, as well as shock, dirt, and flying debris from explosions of training rounds and the like. Experience with the prior mechanisms has shown that such conditions result in so many mechanical and electrical failures that the usefulness of the devices was severely limited.
Moreover, such devices have been expensive, bulky, difficult to maintain, and have required greater electrical power for operation than is desirable for field use where batteries and/or portable electric generators are the source.
SUMMARY OF THE INVENTION
With the foregoing in mind, it is a principal object of this invention to provide an improved electrically driven target raising and lowering mechanism which has great mechanical and electrical reliability even under the adverse conditions set forth above.
Another object of the invention is to provide an improved target positioning mechanism which has a low profile, is reasonably economical to manufacture, and has modest electrical power requirements.
As another object this invention aims to provide a mechanism of the foregoing character which utilizes a torque tube and torsion bar combination to store energy while the target is being lowered and to use that energy when the target is being raised.
Yet another object is to utilize the torque tube as a weatherproof housing for a drive motor and a harmonic gear drive.
The invention may be further said to reside in certain novel combinations, constructions, and arrangements of parts whereby the foregoing objects and advantages are achieved, as well as others which will become apparent from the following detailed description of a preferred embodiment when read in conjunction with the accompanying sheets of drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a target raising and lowering mechanism embodying the present invention, and having some moveable parts thereof shown in broken line positions:
FIG. 2 is a view on an enlarged scale, partly in elevation, partly in section, and with some parts broken out, taken substantially along line 2 -- 2 of FIG. 1; and
FIG. 3 is a sectional view taken substantially along line 3 -- 3 of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the form of the invention illustrated in the drawings and described hereinafter, as an example, there is provided a target raising and lowering mechanism generally indicated at 10 in FIG. 1 and which serves to move a target T in both directions between a raised or full line position and a lowered position as shown in phantom. The mechanism 10 comprises a frame including an aluminum torque tube 12 having plates 14 and 16 welded to opposite ends thereof. The plate 14 closes the end of the tube 12 to which it is welded and also provides a flange to which an angle member 18 is bolted to serve as a transverse support base. The plate 16 does not close the end of the tube 12 to which it is welded but 16 serves as a flange to which is bolted a housing 24 for a final gear drive later described in detail. A transverse support base in the form of an angle member 20 is bolted to a plate portion 24a of the housing 24.
Mounted within the torque tube 12 is a reversible electric motor 30 (FIG. 2) which is directly coupled to a reduction gear 32 of the harmonic type. In the present example the motor 30 operates at 1,725 RPM, and the harmonic reduction gear 32 reduces that by 180 to 1. The reduction gear therefore drives at a rate of 9.58 RPM at its output shaft 32a in the plate 24a forming part of that housing.
The plate 24a serves to close the end of the torque tube 12 and a motor and harmonic gear securing collar 36 which is secured to an adapter ring 38. The housing 24 further comprises an annular member 24b welded to the plate 24a and laterally offset from the axis of the tube 12. A circular cover member 24c is secured to the annular member 24b as by screws 40, and this cover member carries a plain bearing 42 which receives the outer end of the harmonic drive output shaft 32a.
Fixed on the shaft 32a for rotation therewith is a pinion gear 44 which is in mesh with a gear or gear sector 46. The outer end of the shaft 32a is conveniently supported by a plain bearing 45 carried by the housing cover 24c, while the gear sector 46 is provided with a central boss 48 which is conveniently journalled in a plain bearing 50 carried by the housing cover 24c.
The gear sector 46 and boss 48 thereof are provided with a square central aperture through which extends one squared end portion 52a of a torsion bar 52, which runs parallel to the tube 12. The squared end portion also extends through a bearing 53 in the plate 24a and through an opening in the cover 24c to the exterior of the latter.
The opposite end of the torsion bar 52 has a squared portion 52b extending through a corresponding opening in the plate 14 and reinforcing weldment 14a, and a round, terminal portion 52c extending through and beyond a spacer 54.
A pair of arms 56 and 58 are mounted on opposite ends of the torsion bar 52, the arm 58 having a squared opening receiving the square portion extending beyond the cover 24c. The arm 58 is spaced from the cover by a spacer 59. The arm 56 is rotatable freely on the projecting round end portion 52c of the torsion bar. A box member 60 interconnects the arms 56 and 58 so that they are required to move in unison about the axis of the torsion bar. The arms 56 and 58 have channels formed in the outer surfaces thereof to receive struts or legs 62 of a target supporting clamp 64 in which a target T is removably secured.
First and second limit switches 70 and 72 are mounted through the plate 24a with their operating plungers directed inwardly of the housing 24 for actuation by a cam surface 74 carried by the gear sector 46. These limit switches are electrically connected into a control circuit (not shown) for the electric motor 30 and serve to limit the up and down positions to which the target T is moved.
The union between the plate 24a of the housing 24 and the tube 12 is provided with an elastomeric sealing ring 80 of the type referred to as an O-ring, whereby the motor 30 and reduction gearing 32 are effectively protected against intrusion of dirt and moisture. Sealing rings are also provided as shown at 82 between the cover 24c and member 24b, at 84 and 86 between the pinion 44 and the housing 24, and also at 88 and 90 between the gear sector 46 and the housing 24. The housing 24 is preferably charged with a quantity of grease or oil through a suitable fitting (not shown).
A plurality of ground anchors, one of which is shown at 90 in FIG. 2, may be provided to secure the angle support members 18 and 20 to the ground. These anchors are preferably of the auger type and comprise a block 90a which overlies a portion of the support member, a vertical shaft 90b journalled in the block, an auger plate 90c, and a cross-bar 90d for rotating the shaft to screw the auger plate into the ground.
In operation of the mechanism 10, when the target T is hit a control circuit is actuated to energize the motor 30 in a direction which causes the pinion 44 to drive the gear sector 46 so as to lower the target toward the broken line position of FIG. 1. When that position is attained the switch 72 is actuated causing the motor 30 to be deenergized until the control circuit re-energizes it in the reverse direction.
It will be recognized that during lowering of the target the torsion bar 52 will be twisted or "wound-up," thereby storing potential energy derived in part from the change of position of the target mass. When the motor 30 is energized in the reverse direction to raise the target, the torsion bar unwinds and contributes the stored energy to the job of moving the target to the raised position.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.