High energy limb tip cam pulley archery bow

• US 4,739,744 A
• Filed: 11/01/1982
• Issued: 04/26/1988
• Est. Priority Date: 11/01/1982
• Status: Expired due to Term

• Current Assignee: Precision Shooting Equipment Incorporated
• Original Assignee: David J. Nurney
• Inventors: Nurney, David J.
• Primary Examiner(s): Apley, Richard J.
• Assistant Examiner(s): Bahr, Robert
• Application Number:
  US06/438,204
• Time in Patent Office: 2,003 Days
• Field of Search: 124/23 R, 124/24 R, 124/35 A, 124/86, 124/88, 124/90
• US Class Current: 124/23.1
• CPC Class Codes: F41B 5/10 Compound bows compound crossbows F41B5/123
• CPC Class Codes: F41B 5/105 Cams or pulleys for compound bows
• CPC Class Codes: Y10S 124/90 Limb tip rotatable element structure

Abstract

In a compound archery bow having composite bowstring and take-up string cam pulleys carried by the tip portions of bow limbs extending oppositely substantially symmetrically from a handle with the bowstring connecting the composite cam pulleys and take-up strings extending from each composite pulley to the opposite bow limb, each composite cam pulley is composed of a generally elliptical bowstring pulley section having a major axis passing through its portions of substantially greatest length and a generally elliptical take-up string pulley section having a major axis passing through its portion of substantially greatest length, which pulley sections are integrated in parallel side-by-side relationship with planes containing their major axes substantially perpendicularly intersecting. The effective bowstring lever arm of the bowstring pulley section is small and substantially constant during increase of the draw force to at least 90 percent of the maximum draw force while the bowstring nocking point is displaced less than 40 percent of the total displacement during draw and the bowstring lever arm then increases substantially linearly while the draw force remains at a substantially constant maximum value over at least a third of the total bowstring nocking point displacement during draw of the bowstring. The ratio of bowstring draw arm to take-up string draw arm is substantially constant during the draw force increasing phase of the draw.

Claims

1. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a generally planar noncircular bowstring cam pulley section engaged by the bowstring and a generally planar noncircular take-up string cam pulley section engaged by a take-up string, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section in parallel side-by-side relationship for forming a unit with substantially the entire peripheries of said two noncircular pulley sections out of registration, each of said bowstring cam pulley sections having bowstring lever arm means and each of said take-up string cam pulley sections having take-up string lever arm means for requiring a force to draw the bowstring which increases to a maximum during draw, the effective length of the bowstring lever arm means acting during such required increase in force to draw the bowstring always being less than 20 percent of the length of the maximum bowstring lever arm means.

2. In the bow defined in claim 1, each of the bowstring cam pulley sections and the take-up string cam pulley setion combined therewith being constructed to provide means for effecting a ratio of the efective length of each bowstring lever arm means to the effective length of the take-up string lever arm means combined therewith during the force-increasing phase of the draw which is always less than 10 percent of the maximum ratio of the bowstring lever arm means to the take-up string lever arm means in the same unit during draw of the bow.

3. In the bow defined in claim 1, each of the bowstring cam pulley sections and the take-up string cam pulley section combined therewith being constructed to provide means for effecting a ratio of the effective length of each bowstring lever arm means to the effective length of the take-up string lever arm means combined therewith which is within the range of 0.1 to 0.3 throughout the force-increasing phase of the draw.

4. In the bow defined in claim 1, each of the bowstring cam pulley sections and the take-up string cam pulley section combined therewith being constructed to provide means for effecting a bowstring lever arm means effective length which does not change more than 10 percent and a take-up string lever arm means combined therewith effective length which does not change more than 10 percent throughout the force-increasing phase of the draw to a value which is at least 80 percent of the maximum draw force.

5. In the bow defined in claim 1, each of the bowstring cam pulley sections and the take-up string cam pulley sections respectively combined therewith having a peripheral shape, being of such size, being arranged relative to each other and having a common pivot located to provide means for effecting:

(a) a bowstring lever arm means effective length which increases at least 150 percent,

(b) a take-up string lever arm means effective length which decreases at least 40 percent and

(c) a ratio of the effective length of the bowstring lever arm means to the effective length of the take-up string lever arm means which increases at least 300 percent

during that portion of the bowstring draw displacement in which the draw force required is at least 90 percent of the maximum draw force required to draw the bowstring during draw.

6. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including structure to constitute means for requiring the draw force required to rotate the pulley means relative to the handle member to be substantially a maximum throughout draw of the bowstring effecting at least 25 percent of the total turning of the pulley means relative to the handle member which occurs during the entire draw of the drawstring.

7. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including structure to constitute means for requiring a progressive increase in the force required to turn the pulley means relative to the handle member to a value at least 80 percent of the maximum draw force required during the draw of the bowstring while the pulley means turn through approximately 15 percent of the total turning of the pulley means relative to the handle member which ours during the entire draw of the drawstring.

8. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portions of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising structure to constitute means for requiring application of a draw force of at least 90 percent of the maximum draw force required to turn the pulley means relative to the handle member throughout at least substantially one-half of the full draw movement of the bowstring relative to the handle member.

9. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a planar generally elliptical bowstring cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical bowstring cam pulley section and said bowstring cam pulley section being engaged by the bowstring, each pulley means further including a planar generally elliptical take-up string cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical take-up string cam pulley section and said take-up string cam pulley section being engaged by a take-up string, said take-up string cam pulley section of a pulley means being sufficiently smaller than said bowstring cam pulley section of such pulley means that the length of the major axis of such take-up string cam pulley section is approximately 80 percent of the length of the major axis of such bowstring cam pulley section, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with said major axis perpendicular plane of said bowstring cam pulley section and said major axis perpendicular plane of said take-up string cam pulley section of each pulley means mutually crossing.

10. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a planar generally elliptical bowstring cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical bowstring cam pulley section and said bowstring cam pulley section being engaged by the bowstring, each pulley means further including a planar generally elliptical take-up string cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical take-up string cam pulley section and said take-up string cam pulley section being engaged by a take-up string, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with said major axis perpendicular plane of said take-up string cam pulley section substantially perpendicular to the major axis perpendicular plane of said bowstring cam pulley section and with the major axis perpendicular plane of said take-up string camp pulley section substantially bisecting the major axis of said bowstring cam pulley section. PG,49

11. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a planar generally elliptical bowstring cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical bowstring cam pulley section and said bowstring cam pulley section being engaged by the bowstring, each pulley means further including a planar generally elliptical take-up string cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical take-up string cam pulley section and said take-up string cam pulley section being engaged by a take-up string, said bowstring cam pulley section of one of the pulley means having a minor axis perpendicularly bisecting the major axis of said bowstring cam pulley section of such pulley means, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with said major axis perpendicular plane of said bowstring cam pulley section and said major axis perpendicular plane of said take-up string cam pulley section of each pulley means mutually crossing and with such cam pulley sections of such one of the pulley means having the major axis of the take-up string cam pulley section substantially coplanar with the minor axis of the bowstring cam pulley section and with the end of the bowstring cam pulley section minor axis and of the take-up string cam pulley section major axis which are closer to the bow limb when the bowstring is straight being substantially in registration.

12. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a planar generally elliptical bowstring cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptial bowstring cam pulley section and said bowstring cam pulley section being engaged by the bowstring, each pulley means further including a planar generally elliptical take-up string cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical take-up string cam pulley section and said take-up string cam pulley section being engaged by a take-up string, said bowstring cam pulley section of one of the pulley means having a minor axis perpendicularly bisecting the major axis of said bowstring cam pulley section of such one pulley means, said take-up string cam pulley section of such one of the pulley means having a minor axis perpendicularly intersecting the major axis of such take-up string cam pulley section of such one of the pulley means, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with said major axis perpendicular plane of said bowstring cam pulley section and said major axis perpendicular plane of said take-up string cam pulley section of each pulley means mutually crossing and combining such cam pulley sections of such one of the pulley means with the major axis of the take-up string cam pulley section substantially coplanar with the minor axis of the bowstring cam pulley section and with the minor axis of the take-up string cam pulley section substantially parallel to and spaced from the major axis of the bowstring cam pulley section.

13. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a planar generally elliptical bowstring cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical bowstring cam pulley section and said bowstring cam pulley section being engaged by the bowstring, each pulley means further including a planar generally elliptical take-up string cam pulley section having a major axis extending through substantially its greatest length and lying in a plane which is perpendicular to said planar generally elliptical take-up string cam pulley section and said take-up string cam pulley section being engaged by a take-up string, integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with said major axis perpendicular plane of said bowstring cam pulley section and said major axis perpendicular plane of said take-up string cam pulley section of each pulley means mutually crossing, and mounting means mounting one of the pulley means on the tip portion of a bow limb with said tip portion of the bow limb substantially bisecting an angle between the major axis perpendicular plane of the bowstring cam pulley section of such one pulley means and the major axis perpendicular plane of the take-up string cam pulley section of such one pulley means when the bowstring is straight.

14. In an archery compound bow including a handle member, two resilent limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending betweeen the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a generally planar bowstring cam pulley section having a noncircular periphery engaged by the bowstring and a generally planar take-up string cam pulley section having a noncircular periphery engaged by a take-up string, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with substantially the entire noncircular peripheries of said two pulley sections out of registration and with the major axis perpendicular plane of each take-up string cam pulley section disposed substantially perpendicular to the major axis perpendicular plane of the bowstring cam pulley section integrated therewith, each of said bowstring cam pulley sections having bowstring lever arm means and each of said take-up string cam pulley sections having take-up string lever arm means, said combined bowstring cam pulley sections and take-up string cam pulley sections of each pulley means having peripheral shapes, being of such size, being arranged relative to each other and having a common pivot located to provide means for effecting changes in the lengths of said bowstring lever arm means and said take-up string lever arm means during rotation of the pulley means effected by drawing of the bowstring requiring a draw force which increases substantially linearly to a value of at least 80 percent of the maximum required draw force and thereafter requiring a substantially constant draw force to pull the bowstring during a substantial portion of the remaining draw distance.

15. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a generally planar bowstring cam pulley section having a noncircular periphery engaged by the bowstring and a generally planar take-up string cam pulley section having a noncircular periphery engaged by a take-up string, which bowstring cam pulley section and take-up string cam pulley section are of a size and shape to constitute means for effecting turning of each of the pulley means relative to the bow handle member during draw of the bow through an angle between 200 degrees and 270 degrees, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with substantially the entire noncircular peripheries of said two pulley sections out of registration, each of said bowstring cam pulley sections having bowstring lever arm means and each of said take-up string cam pulley sections having take-up string lever arm means, said combined bowstring cam pulley sections and take-up string cam pulley sections of each pulley means having peripheral shapes, being of such size, being arranged relative to each other and having a common pivot located to provide means for effecting changes in the lengths of said bowstring lever arm means and said take-up string lever arm means during rotation of the pulley means effected by drawing of the bowstring requiring a draw force which increases substantially linearly to a value of at least 80 percent of the maximum required draw force and thereafter requiring a substantially constant draw force to pull the bowstring during a substantial portion of the remaining draw distance.

16. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a generally planar bowstring cam pulley section having a noncircular periphery engaged by the bowstring and a generally planar take-up string cam pulley section having a noncircular periphery engaged by a take-up string, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with substantially the entire noncircular peripheries of said two pulley sections out of registration, each of said bowstring cam pulley sections having bowstring lever arm means and each of said take-up string cam pulley sections having take-up string lever arm means, said combined bowstring cam pulley sections and take-up string cam pulley sections of each pulley means having peripheral shapes, being of such size, being arranged relative to each other and having a common pivot located to provide means for effecting changes in the lengths of said bowstring lever arm means and said take-up string lever arm means during rotation of the pulley means effected by drawing of the bowstring requiring a draw force which increases substantially linearly to a value of at least 80 percent of the maximum required draw force and thereafter requiring a substantially constant draw force to pull the bowstring during a substantially portion of the remaining draw distance, and each of said bowstring cam pulley sections and said take-up string cam pulley sections respectively combined therewith being constructed to provide means for effecting a ratio of the effective length of each bowstring lever arm means to the effective length of the take-up string lever arm means in the same unit during the force-increasing phase of the draw which is less than 6 percent of the maximum ratio of said bowstring lever arm means to said take-up string lever arm means in the same unit during draw of the bow.

17. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulleys means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a generally planar bowstring cam pulley section having a noncircular periphery engaged by the bowstring and a generally planar take-up string cam pulley section having a noncircular periphery engaged by a take-up string, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with substantially the entire noncircular peripheries of said two pulley sections out of registration, each of said bowstring cam pulley sections having bowstring lever arm means and each of said take-up string cam pulley sections having take-up string lever arm means, said combined bowstring cam pulley sections and take-up string cam pulley sections of each pulley means having peripheral shapes, being of such size, being arranged relative to each other and having a common pivot located to provide means for effecting changes in the lengths of said bowstring lever arm means and said take-up string lever arm means during rotation of the pulley means effected by drawing of the bowstring requiring a draw force which increases substantially linearly to a value of at least 80 percent of the maximum required draw force and thereafter requiring a substantially constant draw force to pull the bowstring during a substantial portion of the remaining draw distance, and each of said take-up string cam pulley sections being constructed to provide means for effecting a take-up string lever arm means effecting length which is at a lest 70 percent of its maximum length through the force-increasing phase of the draw to a value which is at least 80 percent of the maximum draw force.

18. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a generally planar bowstring cam pulley section having a noncircular periphery engaged by the bowstring and a generally planar take-up string cam pulley section having a noncircular periphery engaged by a take-up string, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with substantially the entire noncircular peripheries of said two pulley sections out of registration, each of said bowstring cam pulley sections having bowstring lever arm means and each of said take-up string cam pulley sections having take-up string lever arm means, said combined bowstring cam pulley sections and take-up string cam pulley sections of each pulley means having peripheral shapes, being of such size, being arranged relative to each other and having a common pivot located to provide means for effecting changes in the lengths of said bowstring lever arm means and said take-up string lever arm means during rotation of the pulley means effected by drawing of the bowstring requiring a draw force which increases substantially linearly to a value of at least 80 percent of the maximum required draw force and thereafter requiring a substantially constant draw force to pull the bowstring during a substantial portion of the remaining draw distance, and each of said take-up string cam pulley sections being constructed to provide means for effecting a take-up string lever arm means effective length which does not change more than 10 percent throughout increase in the draw force to a value which is at least 80 percent of the maximum draw force.

19. In an archery compound bow including a handle member, two resilient limbs carried by and projecting oppositely substantially symmetrically from the handle member, pulley means mounted on the tip portion of each of the limbs for turning about an axis relative to the handle member, a bowstring extending between the two pulley means and a take-up string engaged with each pulley means, the improvement comprising each pulley means including a generally planar bowstring cam pulley section having a noncircular periphery engaged by the bowstring and a generally planar take-up string cam pulley section having a noncircular periphery engaged by a take-up string, and integrating means directly combining said bowstring cam pulley section and said take-up string cam pulley section of each pulley means in parallel side-by-side relationship for forming a unit with substantially the entire noncircular peripheries of said two pulley sections out of registration, each of said bowstring cam pulley sections having bowstring lever arm means and each of said take-up string cam pulley sections having take-up string lever arm means, said combined bowstring cam pulley sections and take-up string cam pulley sections of each pulley means having peripheral shapes, being of such size, being arranged relative to each other and having a common pivot located to provide means for effecting changes in the lengths of said bowstring lever arm means and said take-up string lever arm means during rotation of the pulley means effected by drawing of the bowstring requiring a draw force which increases substantially linearly to a value of at least 80 percent of the maximum required draw force and thereafter requiring a substantially constant draw force to pull the bowstring during a substantial portion of the remaining draw distance, and each of said bowstring cam pulley sections and said take-up string cam pulley sections respectively combined therewith being constructed to provide means for effecting a bowstring lever arm means effective length and a take-up string lever arm means effective length providing a ratio of the effective length of the bowstring lever arm means to the effective length of the take-up string lever arm means which increases substantially linearly as the bowstring nocking point is displaced during draw while the draw force required is at least 90 percent of the maximum draw force required to draw the bowstring during draw.