WO1995027855A1

WO1995027855A1 - Rotary actuator

Info

Publication number: WO1995027855A1
Application number: PCT/AU1995/000190
Authority: WO
Inventors: Donald Mathieson Devenish
Original assignee: Donald Mathieson Devenish
Priority date: 1994-04-07
Filing date: 1995-04-04
Publication date: 1995-10-19
Also published as: AUPM487394A0; IL113256A; TW275104B; ZA952896B; IL113256A0

Abstract

A rotary actuator (10) comprising first and second slider elements (56, 58) coupled to respective pneumatic rams (44, 46) and a plate (12) which is pivoted for rotation about an axis (16). The rams (44, 46) operate on opposite sides of the plate (12) to turn it about 90° in opposite directions from a reference position. The rams (44, 46) are selectively driven such that during linear movement of one ram and its associated slider the other ram and slider assembly acts as a stopper on the other side of the plate (12) to prevent rotation beyond the desired angle. The plate (12) is adapted to carry a target.

Description

Title ROTARY ACTUATOR Field of the Invention

The present invention relates to a rotary actuator and, in particular, but not exclusively, to a rotary actuator for a target. More particularly, the invention relates to a pneumatically operated rotary actuator for a target for use in shooting practice.

Background of the invention Pop-up targets for shooting practice are well known and have been used extensively. Typically the pop-up target is arranged so as to raise a target from a concealed position, display the target in order for a shooter to attempt to hit the target and then return the target either automatically upon the expiration of a short period of time or upon the striking of the target by a bullet or other projectile. A pop-up target of this type is described in the applicant's International application no. PCT/AU90/00546 (WO 91/07594) .

A limitation with pop-up targets in general is that the target . itself cannot be easily or quickly changed to provide variation to the shooter. That is, while individual targets can have targets of a "friend or foe" requiring the shooter to discern which target to attempt to strike, the representation remains the same for any particular target.

The present invention was developed in order to provide a more versatile target which in addition to being able to be raised and lowered from a concealed to an exposed position, allows opposite faces of a target already in a raised position to be turned selectively to present at least two different targets for the shooter. That is, the present invention will enable, for example, a target to be placed in an edge on position to a shooter and then selectively rotated in opposite directions to display opposite target faces to the shooter. Accordingly, opposite target faces can be provided with a representation of a "friend and foe" which can be selectively turned at will and without notice to the shooter.

The actuator in accordance with embodiments of the invention can be used either as a stand alone unit or in conjunction with a pop-up target, in particular where the pop-up target of the type described in the applicant's above-referenced International application. However, it is to be understood that the general principle of the rotary actuator described herein is applicable in any industrial field where it is required to cause a rapid turning of an object in opposite directions.

Summary of the Invention According to the present invention, there is provided a rotary actuator comprising: a member mounted for rotation about an axis; a first element adapted for linear travel in opposite directions, said first element arranged to contact said member during at least a part of its linear travel; a second element adapted for linear travel in said opposite directions, said second element arranged to contact said member during at least a part of its linear travel, said first and second elements disposed on opposite sides of a plane parallel to the direction of said linear travel and containing said axis; said elements being selectively driven so that during linear travel of one of said elements, said one element can contact said member to cause the member to rotate about said axis between a reference position and a first rotated position being offset from said reference position in a first rotation direction, and during linear travel of the other of said elements, said other element can contact said member to cause said member to rotate about said axis between said reference position and a second rotated position being angularly offset from said reference position in a second rotational direction being opposite to said first rotational direction, whereby in use, said rotary actuator can be turned in opposite directions from said reference position to said first rotational position or said second rotational position.

Preferably said elements and member are relatively juxtaposed so that at the end of the linear travel of any one element, both elements are in contact with or close proximity to said member to stop substantially rotation of said member about said axis upon the application of extraneous forces on said member.

Preferably said elements and member are further juxtaposed so that when said plate is rotated by the linear travel of one of said elements from said reference position to said first or second rotated positions, the other element can contact said member to stop further rotation of said member about said axis in the direction of rotation effected by said one element.

Preferably said member comprises a plate lying in a plane substantially perpendicular to said axis.

Preferably said plate is configured so as to provide clearance for said elements when being rotated about said axis so that said plate can be rotated to said first and second rotated positions without jamming with the element engaged in linear travel.

Preferably said plate is formed with respective arcuate cut-outs in which said elements can ride while maintaining contact with said plate when engaged in linear travel for rotating said plate about said axis thereby providing said clearance. Preferably said rotary actuator further comprises a housing in which said plate and elements are housed, said housing having parallel side walls along which said elements slide when engaged in linear travel.

Preferably said rotary actuator further comprises first and second linear actuators connected with respective first and second elements for linearly driving said elements in said opposite directions.

Advantageously each linear actuator comprises a cylinder with a piston which may be selectively extended and retracted from said cylinder so as to provide said linear travel.

Advantageously said linear actuators are operated by a compressed gas.

Preferably said plate is further provided with first and second resilient pads disposed so that said pads can contact said elements to cushion any impact between said plate and said element when said plate is rotated to said first or second rotated positions.

According to a further aspect of the present invention, there is provided a rotary actuator comprising: a member mounted for rotation about an axis; first and second linear actuators each for producing linear motion in opposite directions; a first element coupled with said first linear actuator and a second element coupled with said second linear actuator, said elements disposed on opposite sides of a plane parallel to the direction of motion produced by said linear actuators and passing through said axis, said elements further disposed so as to contact said member at a location offset from said axis, whereby said first linear actuator can be operated to move said first element in a first direction to rotate said member about said axis in a first rotational direction from a reference position to a first rotated position at which said member can contact said second element to prevent further rotation of said plate in said first rotational direction, and said first actuator can be operated to move said first element in a second direction opposite to said first direction to contact said member and rotate said member in a second rotational direction opposite to said first rotational direction back to said reference position; and, said second actuator can be operated to move said second element in said second direction so as to rotate said member about said axis in said second rotational from said reference position to a second rotated position at which said member can contact said first element to prevent further rotation of said member in said second rotational direction and, said second actuator can be operated to move said second element in said first direction to contact said member and rotate said member in said first rotational direction back to said reference position.

Preferably said rotary actuator is further provided with a target carrier connected with said plate said target carrier having opposing side surfaces wherein when said member is in said reference position, said target carrier is edge on to a predetermined reference point, and when said member is rotated to said first rotated position one side surface of said target carrier faces said predetermined reference point, and when said member is rotated to said second rotated position, an opposite side surface of said target carrier faces said predetermined reference point. Brief Description of Drawings

An embodiment of the present invention will now be described by reference to the accompanying drawings in which:

Figure 1 is a plan view of an embodiment of the rotary actuator with a plate of said actuator in a reference position;

Figure 2 is a plan view of the rotary actuator shown in Figure 1 with the plate turned to a first rotated position;

Figures 3a-3g is a series of conceptual snap shots of the plate of the actuator shown in Figures 1 and 2 being rotated from a reference position to a rotated position;

Figure 4 is a detailed plan view from the top of an element incorporated in the actuator shown in Figures 1 and 2;

Figure 5 is a side view of the element shown in Figure 4; and,

Figure 6 is a schematic representation of a pneumatic control system for the rotary actuator shown in Figures 1 and 2.

Detailed Description of the Preferred Embodiment

Referring to the accompanying drawings, and in particular, Figure 1, it can be seen that a rotary actuator 10 comprises a member in the form of plate 12 fixed to a spindle 14 which extends perpendicular to the plane of the plate 12. The spindle 14 is supported by bearings (not shown) to allow said plate and spindle 14 to rotate about an axis 16 concentric with the spindle 14. The plate 12 is of a substantially T or paddle shape and having a pair of arcuate cut-outs 20 and 22 which are disposed on opposite sides and at the same end of the plate. Plate 12 may conveniently be considered as being composed of a contiguous substantially square head 15, neck 17 and body 19, where the cut-outs 20 and 22 are formed on opposite sides of the plate 12 between the head 15, neck 17 and body 19. As will be explained in greater detail hereinbelow, the cut-outs 20 and 22 provide clearance from other parts of the rotary actuator 10 as the plate 12 is rotated. Resilient pads 24 and 26 are also attached on opposite side edges 28 and 30 of head 15 near back edge 31 of plate 12.

Plate 12 is rotatably retained about axis 16 within a housing 32. The housing is in the form of a rectangular box having opposite side walls 34 and 36 and opposite end walls 38 and 40 which join with the side walls 34 and 36. The walls 34, 36, 38 and 40 are connected with an underlying rectangular base 42 and an upper cover (not shown) which is configured to allow at least spindle 14 to pass therethrough.

Linear actuators in the form of pneumatic rams 44 and 46 are connected with the housing 32 at diagonally opposite corners with ram 44 passing through end wall 38 and ram 46 passing through end wall 40. Ram 44 includes a cylinder 48 and piston rod 50 which can be selectively extended or retracted from cylinder 48. Likewise ram 46 includes a pneumatic cylinder 52 and piston rod 54 which can be selectively extended from or retracted into the cylinder 52. Rams 44 and 46 are disposed so that their respective piston rods 50 and 54 when extending and retracting travel beneath the plate 12.

Elements in the form of sliders 56 and 58 are coupled with piston rods 50 and 54 respectively. The slider 56 is shown in greatest detail in Figures 4 and 5. In these figures it can be seen that each slider comprises a pair of plates 60 and 62 connected together at one edge by a weld 64 so as to be in a facing and spaced relationship. Plate 60 is of essentially rectangular shape but with an upper corner being cut-out or machined away to leave a recess 66 and adjacent lug 68. Plate 60 also includes a side edge 70 and perpendicular bottom edge 72 with lug 68 provided with bearing edge 71 opposite side edge 70. In this embodiment bearing edge 71 is of a convex shape.

Plate 62 is also of rectangular shape but of a smaller width and height dimension than plate 62. Plate 62 is disposed below recess 66 and is flush with plate 60 at the side containing the weld 64. Two holes 74 and 76 are formed through both plates 60 and 62. Hole 74 is tapped so as to threadingly engage a screw thread formed on piston rods 50, 54. Adjacent hole 76 receives a nut and bolt assembly 78.

Slider 56 is connected with piston rod 50 by initially screwing the piston rod through hole 74 to a desired position and then tightening the nut and bolt assembly 78 so as to bias plates 60 and 62 toward each other to effectively clamp the slider to the piston rod 50. The slider 56 is orientated so that side edge 70 faces side wall 36 and bottom edge 72 faces base 42. Slider 58 is coupled in a similar manner to piston rod 54.

Figures 1 and 3A show plate 12 in a reference position, where piston rod 54 is in a retracted state and piston rod 50 is in an extended state, and sliders 56 and 58 are coplanar and disposed on opposite sides of body 19. The body 19 of the plate 12 is received in recesses 66 of sliders 56 and 58. If ram 46 is operated so as to extend piston rod 54, the slide 58 will travel in direction A toward cylinder 48. After a short distance the lug 68 of slider 58 will ride in cut-out 22 and thereafter contact the plate 12 at a leading edge 67 of head 15 (refer Fig. 3B) causing the plate to rotate in anticlockwise direction. This rotation is facilitated by the cut-out 22 which ensures that during rotation, the plate 12 does not become jammed with slider 58 as shown in Figures 3C to 3F. The plate 12 is rotated to a first rotated position 90° anticlockwise from its reference position as shown in Figure 3G. When in this position, the pad 26 contacts the slider 56 which has remained stationary. The pad 26 effectively acts as a shock absorber to cushion impact with slider 56. This is necessary as in practice the speed of rotation of plate 12 is very high.

Retraction of piston rod 54 will rotate the plate 12 about axis 16 in a clockwise direction back to the reference position shown in Figure 1.

By operating ram 44 to now retract piston rod 50, tab 66 of slider 56 will contact leading edge 69 of head 15 and ride in cut-out 20 to rotate clockwise from the reference position by 90° to the position shown in Figure 2. Further rotation in the clockwise direction is prohibited by the pad 24 which would come into contact with the tab 66 of slider 58. Operation of ram 46 to now extend piston rod 50 will cause rotation of the plate 12 in the anticlockwise direction back to the reference position shown in Figure 1.

When the plate 12 is in the reference position shown in Figures 1 and 3A or in either of the fully rotated positions as shown in Figures 2, 3G or 6, it is effectively locked against rotation about axis 16 in response to extraneous forces or moments that may be applied for example by a ballet or projectile striking a target coupled to spindle 14. This locking feature exists whether or not positive pressure is applied to rams 44 and 46. In the reference position shown in Figures 1 and 3A, if a moment is applied to the plate 12 about axis 16, body 19 will push against bearing edge 71 of either slider 58 or 56

(depending on the sense of the applied moment) , in a direction perpendicular to the direction of linear travel of sliders 56, 58 and corresponding piston rods 50, 54.

Thus, it is not possible for plate 12 to rotate from the reference position apart from perhaps a very small degree of rotation due to manufacturing tolerances, except by actuation of rams 44, 46 or catastrophic failure such as shearing of the body 19 from neck 17. This is the case even if no air pressure is applied to rams 44, 46.

In the rotated position shown in Figure 2, both piston rods 50 and 54 are fully retracted and therefore would be in contact with internal stops (not shown) of their respective rams 44, 46. Side 28 of plate 12 contacts lug 68 of slider 58 and leading edge 69 of plate 12 is in close proximity to or in contact with bearing edge 71 of slider 56. If a clockwise moment is applied about axis 16 to plate 12, the plate is prevented from rotation by slider 58 as corresponding piston rod 54 cannot be retracted any further into cylinder 52. If an anticlockwise moment is applied leading edge 69 will push against bearing edge 71 in a direction perpendicular to the direction of travel of piston rod 50. This merely pushes slider 56 harder against side wall 36 of housing 32 and cannot cause extension of piston rod 50 from cylinder 48.

A similar effect occurs when the plate 12 is in the other fully rotated position shown in Figure 6. However in this case both piston rods 50, 54 are fully extended, and therefore in contact with other internal stops (not shown) of their respective rams 44, 46 preventing further extension. Anticlockwise rotation of plate 12 through application of an extraneous moment is prevented by contact with slider 56 as piston rod 50 can extend no further. Clockwise rotation of plate 12 is prevented as leading edge 67 pushes against bearing edge 71 of slider 58 in a direction perpendicular to that required to cause retraction of piston rod 54 into cylinder 52.

The rams 44 and 46, and thus the operation of the rotary actuator 10, can be controlled by a conventional pneumatic control system such as shown in Figure 6. The system includes a supply of compressed gas 80 which can be selectively coupled to the rams 44 and 46 via four port two position valves 82 and 84 respectively. Hoses 86 and 88 are connected between the valve 82 to ram 44 in a conventional manner as are hoses 90 and 92 to ram 46 through valve 84. The valves 82 and 84 are preferably solenoid operated and of a type which remain in the last selected position after the solenoid is de-energised. Typically, the pressure of the compressed gas provided by supply 80 is between 7 to 10 bar and the plate 12 rotates from the reference position to either rotated position in approximately 0.1 seconds.

In operation, to rotate the plate 12 anticlockwise from the reference position shown in Figure 1 valve 84 controlling the flow of compressed gas from supply 80 to cylinder 52 is moved to the position shown, directing compressed gas through tube 92 to the right hand end of cylinder 52, thus extending piston rod 54 and corresponding slider 58 in the direction of arrow B. Valve 82 controlling gas to cylinder 48 remains in the position shown in Figure 6 so that piston rod 50 and corresponding slider 56 remain fully extended.

To permit accurate and logical control of the rotary actuator, the positions of the pistons in the respective rams can be sensed by limit switches, magnetic reed switches, potentiometers or other similar means. Operation of the rotary actuator can be controlled by directly connected switches, by remote control or by pre-programmed electronic controls including a microprocessor to store a number of suitable operating sequences. Such programmed sequences can include the operation of a pop-up actuator as well as the rotary actuator in a combined pop-up and rotary system. Thus, in a combined pop-up rotary target, these functions can be combined so that, commencing with the target down and in an edge on position, on a given signal the target can be simultaneously turned and raised. This allows minimum time for a shooter to anticipate which of the two target faces will be exposed.

Further, when used in combination with a pop-up target and means for sensing the strike of a projectile, the described embodiment allows for a realistic response in that a "hit" in a first selected area of the target can be interpreted as a fatal hit and cause the target to fall, while a "hit" in a second selected area can be interpreted as a wounding strike and case the target to turn edge on for a random or preset time before returning to a face on position. This gives a clear and instantaneous indication of the result of a hit.

It will be apparent to those -skilled in the relevant arts that numerous modifications and variations can be made to the above-described embodiment without departing from the basic inventive concept. For example, the plate 12 may be of any shape and configuration provided clearance is provided to allow rotation without jamming against the sliders 56, 58 or other components of the actuator 10. Also the sliders 56, 58 may be in the form of a single plate, similar to plate 60 and fixed to piston rods 50, 54 by use of lock nuts only or other mechanical fasteners. For speed of operation it is preferred that the rams 44, 46 are pneumatically operated however, where speed is not critical the rams may be hydraulically or electrically operated. Finally, clearly the described actuator 10 can be used in any application where it is required to obtain a turning motion in opposite directions and need not be restricted to use with a target. All such modifications and variations are deemed to be within the scope of the present invention the nature of which is to be determined from the foregoing description.

Claims

The Claims Defining the Invention are as Follows:-

1. A rotary actuator comprising: a member mounted for rotation about an axis; a first element adapted for linear travel in opposite directions, said first element arranged to contact said member during at least a part of its linear travel; a second element adapted for linear travel in said opposite directions, said second element arranged to contact said member during at least a part of its linear travel, said first and second elements disposed on opposite sides of a plane parallel to the direction of said linear travel and containing said axis; said elements being selectively driven so that during linear travel of one of said elements, said one element can contact said member to cause the member to rotate about said axis between a reference position and a first rotated position being offset from said reference position in a first rotation direction, and during linear travel of the other of said elements, said other element can contact said member to cause said member to rotate about said axis between said reference position and a second rotated position being angularly offset from said reference position in a second rotational direction being opposite to said first rotational direction, whereby in use, said rotary actuator can be turned in opposite directions from said reference position to said first rotational position or said second rotational position.

2. A rotary actuator according to claim 1, wherein said elements and member are relatively juxtaposed so that at the end of the linear travel of any one element, both elements are in contact with or close proximity to said member to stop substantially rotation of said member about said axis upon the application of extraneous forces on said member.

3. A rotary actuator according to claim 2, wherein said elements and member are further juxtaposed so that when said plate is rotated by the linear travel of one of said elements from said reference position to said first or second rotated positions, the other element can contact said member to stop further rotation of said member about said axis in the direction of rotation effected by said one element.

4. A rotary actuator according to claim 3, wherein said member comprises a plate lying in a plane substantially perpendicular to said axis.

5. A rotary actuator according to claim 4, wherein said plate is configured so as to provide clearance for said elements when being rotated about said axis so that said plate can be rotated to said first and second rotated positions without jamming with the element engaged in linear travel.

6. A rotary actuator according to claim 5, wherein said plate is formed with respective arcuate cut- outs in which said elements- can ride while maintaining contact with said plate when engaged in linear travel for rotating said plate about said axis thereby providing said clearance.

7. A rotary actuator according to claim 6, further comprising a housing in which said plate and elements are housed, said housing having parallel side walls along which said elements slide when engaged in linear travel.

8. A rotary actuator according to claim 7, further comprising first and second linear actuators connected with respective first and second elements for linearly driving said elements in said opposite directions.

9. A rotary actuator according to claim 8, wherein each linear actuator comprises a cylinder with a piston which may be selectively extended and retracted from said cylinder so as provide said linear travel.

10. A rotary actuator according to claim 9, wherein said linear actuators are operated by a compressed gas.

11. A rotary actuator according to claim 10, wherein said plate is further provided with first and second resilient pads disposed so that said pads can contact said elements to cushion any impact between said plate and said element when said plate is rotated to said first or second rotated positions.

12. A rotary actuator comprising: a plate mounted for rotation about an axis extending perpendicular to said plate; first and second linear actuators each for producing linear motion in opposite directions; a first element coupled with said first linear actuator and a second element coupled with said second linear actuator, said elements disposed on opposite sides of a plane parallel to the direction of motion produced by said linear actuators and passing through said axis, said elements further disposed so as to contact said plate at a location offset from said axis, whereby said first linear actuator can be operated to move said first element in a first direction to rotate said plate about said axis in a first rotational direction from a reference position to a first rotated position at which said plate can contact said second element to prevent further rotation of said plate in said first rotational direction, and said first actuator can be operated to move said first element in a second direction opposite to said first direction to contact said plate and rotate said plate in a second rotational direction opposite said first rotational direction back to said reference position; and, said second actuator can be operated to move said second element in said second direction so as to rotate said plate about said axis in said second rotational from said reference position to a second rotated position at which said plate can contact said first element to prevent further rotation of said plate in said second rotational direction and, said second actuator can be operated to move said second element in said first direction to contact said plate and rotate said plate in said first rotational direction back to said reference position.

13. A rotary actuator according to claim 12, further comprising a target carrier connected with said plate said target carrier having opposing side surfaces wherein when said plate is in said reference position, said target carrier is edge on to a predetermined reference point, and when said plate is rotated to said first rotated position one side surface of said target carrier faces said predetermined reference point, and when said plate is rotated to said second rotated position, an opposite side surface of said target carrier faces said predetermined reference point.

14. A rotary actuator according to claim 1, further comprising a target carrier connected with said member said target carrier having opposing side surfaces wherein when said member is in said reference position, said target carrier is edge on to a predetermined reference point, and when said member is rotated to said first rotated position one side surface of said target carrier faces said predetermined reference point, and when said member is rotated to said second rotated position, an opposite side surface of said target carrier faces said predetermined reference point.