Crossbow with inertia brake cocking device

Abstract

A crossbow with an inertia brake cocking device preferably utilizes a one-way bearing to control rotation of the drive unit used to wind (take-up) an elongated connecting device. Functional properties of an inertia brake mechanism (IBM) are well known. In its simplest form, an IBM has at least a first plate floating within a cavity, the first plate having a protrusion along an edge, and the cavity having recesses radially about its perimeter. Under controlled rotation in either direction, the IBM allows for the unrestricted rotation of the mechanism to which it is coupled. If the IBM senses a rapid acceleration of the spool, inertia moves the plate to engage a recess in the perimeter of the cavity, stopping uncontrolled rotation of the spool.

Claims

1. A cranking mechanism for a crossbow comprising: a driven gear coupled to a spool and having a first axis of rotation, a drive gear having a second axis of rotation and operably coupled with said driven gear, a drive shaft includes a first driven end and a second end and is axial with said drive gear, a one way bearing is selectively fixed radially by a one way bearing retainer or selectively free to rotate radially by disengagement of said one way bearing retainer, an inertia brake mechanism radially coupled to said drive shaft, said inertia brake mechanism includes a first brake plate, a second brake plate and a brake ring, said brake ring having a plurality of radially spaced recesses, each said brake plate includes a first side, a second side, and a perimeter, said perimeter includes a flat portion and a curved portion, said flat portion of said first and second brake plates face each other, said first and second brake plates slide relative to each other within said brake ring, said curved portion includes a plurality of protrusions sized to interact with said plurality of radially spaced recesses of said brake ring, a peripheral space is created between said plurality of protrusions and radially spaced recesses; and a flexible member having a first end coupled to said spool and a second end coupled to a bowstring drawing device, said drive shaft is rotated a first direction causing rotation of said drive gear and said driven gear, winding said flexible member on said spool, said one way bearing retainer engages said one way bearing preventing rotation of said drive shaft in a second direction, said inertia brake plates rotate freely within said peripheral space.

2. The crossbow cranking mechanism of claim 1 wherein: disengagement of said one way bearing retainer allows controlled rotation of said drive shaft in a second direction for unwinding said flexible member from said spool.

3. The crossbow cranking mechanism of claim 1 wherein: an uncontrolled rotation of said driveshaft is interrupted by said inertia brake mechanism, in that inertia forces at least one of said plurality of protrusions to engage at least one of said plurality of radially spaced recesses.

4. A cranking mechanism for a crossbow comprising: a driven gear coupled to a spool and having a first axis of rotation, a drive gear having a second axis of rotation and operably coupled with said driven gear, a drive shaft includes a first driven end and a second end and is axial with said drive gear, a one way bearing axial to said drive shaft and operably retaining said drive shaft, said one way bearing is selectively fixed radially by a one way bearing retainer or selectively free to rotate radially by disengagement of said one way bearing retainer, an inertia brake mechanism axial to and coupled to said driven gear, said inertia brake mechanism having a first and second brake plate and a brake ring, said brake ring having a plurality of radially spaced recesses, each of said brake plates has a first side, a second side, and a perimeter, said perimeter includes a flat portion and a curved portion, said flat portion of said first and second brake plates face each other, said first and second brake plates slide relative to each other within said brake ring, said curved portion includes a plurality of protrusions sized to interact with said plurality of radially spaced recesses of said brake ring, a peripheral space is created between said plurality of protrusions and radially spaced recesses; and a flexible member having a first end coupled to said spool and a second end coupled to a bowstring drawing, said driven end of said drive shaft is rotated in a first direction causing rotation of said drive gear and driven gear, winding said flexible member on said spool, said one way bearing retainer engages said one way bearing preventing rotation of said drive shaft a second direction, said inertia brake plates rotate freely within said peripheral space.

5. The crossbow cranking mechanism of claim 4 wherein: disengagement of said one way bearing retainer allows controlled rotation of said drive shaft in a second direction for unwinding said flexible member from said spool.

6. The crossbow cranking mechanism of claim 4 wherein: an uncontrolled rotation of said driveshaft is interrupted by said inertia brake mechanism, in that inertia forces at least one of said plurality of protrusions to engage at least one of said plurality of radially spaced recesses.

7. A cranking mechanism for a crossbow comprising: a driven gear coupled to a spool and having a first axis of rotation, a drive gear having a second axis of rotation and operably coupled with said driven gear, a drive shaft includes a first driven end and a second end and is axial with said drive gear, an inertia brake mechanism axial to and coupled to driven gear, said inertia brake mechanism having first and second brake plates and a brake ring, said brake ring having a plurality of radially spaced recesses, each of said brake plates has a first side, a second side, and a perimeter, said perimeter includes a flat portion a curved portion, said flat portion of said first and second brake plates face each other, said first and second brake plates slide relative to each other within said brake ring, said curved portion includes a plurality of protrusions sized to interact with said plurality of radially spaced recesses of said brake ring, a peripheral space is created between said plurality of protrusions and radially spaced recesses; and a flexible member having a first end coupled to said spool and a second end coupled to a bowstring drawing device, said driven end of said drive shaft is rotated in a first direction causing rotation of said drive gear and a ratchet gear and said driven gear, said ratchet gear is located on said drive shaft, winding said flexible member on said spool, a pawl engages said ratchet gear preventing rotation of said drive shaft in a second direction, said inertia brake plates rotate freely within said peripheral space.

8. The crossbow cranking mechanism of claim 7 wherein: disengagement of said pawl allows controlled rotation of said drive shaft in a second direction for unwinding said flexible member from said spool.

9. The crossbow cranking mechanism of claim 7 wherein: an uncontrolled rotation of said driveshaft is interrupted by said inertia brake mechanism, in that inertia forces at least one of said plurality of protrusions to engage at least one of said plurality of radially spaced recesses.

10. A cranking mechanism for a crossbow comprising: a driven gear coupled to a spool and having a first axis of rotation, a drive gear having a second axis of rotation and operably coupled with said driven gear, a drive shaft includes a first driven end and a second end and is axial with said drive gear, an inertia brake mechanism axial to and coupled to said drive gear, said inertia brake mechanism having first and second brake plates and a brake ring, said brake ring having a plurality of radially spaced recesses, each of said brake plates has a first side, a second side, and a perimeter, said perimeter includes a flat portion, said flat portion of said first and second brake plates face each other, said first and second brake plates slide relative to each other within said brake ring, said curved portion includes a plurality of protrusions sized to interact with said plurality of radially spaced recesses of said brake ring, a peripheral space is created between said plurality of protrusions and radially spaced recesses; and a flexible member having a first end coupled to said spool and a second end coupled to a bowstring drawing device, said driven end of said drive shaft is rotated a first direction causing rotation of said drive gear and a ratchet gear and said driven gear, said ratchet gear is located on said drive shaft, winding said flexible member on said spool, a pawl engages said ratchet gear preventing rotation of said drive shaft a second direction, said inertia brake plates rotate freely within said peripheral space.

11. The crossbow cranking mechanism of claim 10 wherein: disengagement of said pawl allows controlled rotation of said drive shaft in a second direction for unwinding said flexible member from said spool.

12. The crossbow cranking mechanism of claim 10 wherein: an uncontrolled rotation of said driveshaft is interrupted by said inertia brake mechanism, in that inertia forces at least one of said plurality of protrusions to engage at least one of said plurality of radially spaced recesses.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a partial rear perspective view of a cranking mechanism in accordance with the present invention.

(2) FIG. 2 is an exploded perspective view of a cranking mechanism in accordance with the present invention.

(3) FIG. 3 is an exploded perspective view of a cranking mechanism in accordance with the present invention.

(4) FIG. 4 is a perspective view of an assembled cranking mechanism of in accordance with the present invention.

(5) FIG. 5 is a partial perspective view of a crossbow with an integrated cranking mechanism in accordance with the present invention.

(6) FIG. 6 is a partial perspective view of a crossbow with an integrated cranking mechanism in accordance with the present invention.

(7) FIG. 7 is a partial perspective view of a crossbow with a grip portion and a trigger lever extending from the grip portion in accordance with the present invention.

(8) FIG. 8 is a partial perspective view of a crossbow with a portion of a grip portion removed and a trigger lever extending from the grip portion in accordance with the present invention.

(9) FIG. 9 is a partial perspective view of a crossbow with a grip portion removed and a trigger lever connected to an actuator in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) A crossbow cocking device has a driven gear 60 axially coupled to a spool 70, both having a first axis of rotation. A drive gear 50 is axially coupled with a one-way bearing 32, both having a second axis of rotation. The one-way bearing 32 is radially fixed in a retainer 30, and selectively radially retained allowing the drive gear 50 to rotate in a first direction winding an elongated member 72 about the spool 70, but does not rotate in a second direction. When the one-way bearing retainer 30 is radially de-coupled, the one-way bearing 32, the retainer 30 and the drive gear 50 may rotate the second direction.

(11) The IBM 10 is axial to the second axis of rotation, and a brake ring 12 is radially fixed. A cranking handle 40 may be engaged with the drive gear 50, rotating the drive gear 50 a first direction causing the rotation of the driven gear 60, winding the elongated member 72 about the spool 70. One end of the elongated member 72 is attached to the spool 70 and an opposing end is attached to a bowstring drawing device, such as a bowstring carrier 160. The one-way bearing 32 is selectively retained radially, and prevents the drive gear 50 from rotating in a second direction when the crank handle 40 ceases rotation.

(12) The user may selectively disengage the one-way bearing retainer 30, and rotate the crank handle 40 in the second direction, allowing the driven gear 60 to unwind the elongated member 72 from the spool 70. Due to the functional characteristics of the IBM 10, a controlled rotation of the drive gear 50 in either direction is allowed.

(13) During the unwinding of the elongated member 72 from the spool 70, if the crank handle 40 were to slip out of the user's hand, the sudden uncontrolled rotation will be sensed by the IBM 10, and inertia will force first plate 14 and a second plate 16 into cooperation with the brake ring 12, ceasing uncontrolled rotation of the spool 70 and crank handle 40. Each brake plate 14, 16 includes a flat portion and a curved portion. The flat portion of said brake plates 14, 16 face each other. A plurality of protrusions 20 are formed on the curved portion. The plurality of protrusions 20 cooperate with a plurality of recesses 18 formed in an inside perimeter of the brake ring 12, preventing rotation of the drive gear 50 and driven gear 60. The first and second brake plates 14, 16 are slidable retained. Alternately, the IBM 10 may be axial with the first axis of rotation, and the brake ring 12 radially fixed. A peripheral space is created between the plurality of protrusions and radially spaced recesses. The IBM 10 may be built into the crossbow, or removable from the crossbow. Alternately, a motor may be used to rotate the drive gear 50.

(14) An alternate embodiment replaces the one-way bearing 32 and retainer 30 axial with the drive shaft with a simple pawl and ratchet gear operably coupled with the drive shaft (not shown).

(15) The trigger lever 200 is pivotally retained with the grip portion 100 of the crossbow stock, wherein the trigger lever 200 is coupled to a connecting arm 90 which is coupled to a sear. The trigger lever 200 may be spring loaded to a return position, to bias the trigger lever 200 in a first or second direction. The connecting arm 90 may be spring loaded to bias the connecting arm 90 in a first or second direction. In a preferred embodiment, the connecting arm 90 may be selectable for length, to change the length of pull. Alternately, the connecting arm 90 may be of differing lengths, and the user chooses a desired length of connecting arm 90 for the chosen length of pull. Length of pull is the distance from the shoulder-engaging portion of the butt stock and the trigger lever 200.

(16) The grip portion 100 of the crossbow having the trigger lever 200 is coupled to the crossbow frame 150 relative to a length of the connecting arm 90 and a length of pull.

(17) Alternately, a trigger lever 200 is retained in a grip portion 100. The trigger arm 200 is movable from a first position to a second position, the first position does not release the bowstring, the second position releases the bowstring. A first contact surface 190 is preferably located on the trigger lever 200, a second contact surface 192 and a third contact surface 194 contact surface are located adjacent the first contact surface 190. An actuator 180 works in cooperation with the sear (not shown). When the actuator 180 is in a first position, the sear lever (not shown) is in a first position, retaining the bow string. When the actuator 180 is in the second position, the sear is allowing the release of the bowstring. A power source 210 is operably connected with the actuator 180 and the second contact surface 192 and third contact surface 194, such that when the trigger lever 200 is in the first position, the first contact surface 190 does not make contact with the second contact surface 192 and the third contact surface 194. An open circuit is the result of the trigger lever 200 in the first position. When the trigger lever 200 is in the second position, the first contact surface 190 is in contact with the second and third contact surfaces 192, 194 and the circuit is completed activating the actuator 180, which allows the release of the bowstring.

(18) The trigger lever 200 may be spring loaded to bias the first contact surface 190 away from the second contact surface 192. The grip portion 100 of the crossbow having the trigger lever 200 is coupled to the crossbow frame 150 relative to the length of the desired length of pull.

(19) While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.