Claims
- 1. A synchronous drive apparatus, comprising:
a continuous-loop elongate drive structure (10) having a plurality of engaging sections (15); a plurality of rotors comprising at least a first and a second rotor (11, 12), the first rotor (11) having a plurality of teeth (16) for engaging the engaging sections (15) of the elongate drive structure (10), and the second rotor (12) having a plurality of teeth (16) for engaging the engaging section (15) of the elongate drive structure (10); a rotary load assembly (26) coupled to the second rotor (12); the elongate drive structure being engaged about the first and second rotors, the first rotor (11) being arranged to drive the elongate drive structure (10) and the second rotor (12) being arranged to be driven by the elongate drive structure (10), and one of the rotors having a non-circular profile (19) having at least two protruding portions (22, 23) alternating with receding portions (24, 25), the rotary load assembly (26) being such as to present a periodic fluctuating load torque when driven in rotation; characterised in that the angular positions of the protruding and receding portions of the non-circular profile (19) relative to the angular position of the second rotor (12), and the magnitude of the eccentricity of the non-circular profile (19), are such that the non-circular profile applies to the second rotor an opposing fluctuating corrective torque (104) which reduces or substantially cancels the fluctuating load torque (103) of the rotary load assembly (26).
- 2. A synchronous drive apparatus according to claim 1, in which the non-circular profile (19) is such as to produce the said opposing fluctuating corrective torque by periodic elongation and contraction of the spans of the elongate drive structure (10) adjoining the rotor on which the non-circular profile (19) is formed, the elongate drive structure having a drive span (10A, 10B) on the tight side of the rotor on which the non-circular profile (19) is formed, the angular position of the non-circular profile (19) being within +/−15 degrees of an angular position for which a maximum elongation of the said drive span (10A, 10B) coincides with a peak value of the fluctuating load torque (103) of the rotary load assembly (26).
- 3. A synchronous drive apparatus according to claim 2, in which the angular position of the non-circular profile (19) is within +/−5 degrees of the angular position for which a maximum elongation of the said drive span (10A, 10B) coincides with a peak value of the fluctuating load torque (103) of the rotary load assembly (26).
- 4. A synchronous drive apparatus according to claim 2, in which the angular position of the non-circular profile (19) is that for which a maximum elongation of the said drive span (10A, 10B) substantially coincides with a peak value of the fluctuating load torque (103) of the rotary load assembly (26).
- 5. A synchronous drive apparatus according to claim 1, in which the magnitude of the eccentricity of the non-circular profile is such that the fluctuating corrective torque (104) has an amplitude in the range of 70% to 110% of the amplitude of the fluctuating load torque (103) at a predetermined selected set of operating conditions of the synchronous drive apparatus.
- 6. A synchronous drive apparatus according to claim 5, in which the said range consists of 90% to 100% of the amplitude of the fluctuating load torque (103).
- 7. A synchronous drive apparatus according to claim 5, in which the amplitude of the fluctuating corrective torque (104) is substantially equal to the amplitude of the fluctuating load torque (103).
- 8. A synchronous drive assembly according to claim 1, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) is substantially constant, and the magnitude of the eccentricity of the non-circular profile (19) is such that the fluctuating corrective torque (104) has an amplitude in the range of 70% to 110% of the amplitude of the fluctuating load torque (103).
- 9. A synchronous drive apparatus according to claim 8, in which the said range consists of 90% to 100% of the amplitude of the fluctuating load torque (103).
- 10. A synchronous drive apparatus according to claim 8, in which the amplitude of the fluctuating corrective torque (104) is substantially equal to the amplitude of the fluctuating load torque (103).
- 11. A synchronous drive assembly according to claim 1, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) varies, and the magnitude of the eccentricity of the non-circular profile (19) is such that the fluctuating corrective torque (104) has an amplitude in the range of 70% to 110% of the amplitude of the fluctuating load torque when determined at conditions such that it is a maximum.
- 12. A synchronous drive apparatus according to claim 11, in which the said range consists of 90% to 100% of the amplitude of the fluctuating load torque (103) when determined at conditions such that it is a maximum.
- 13. A synchronous drive apparatus according to claim 11, in which the amplitude of the fluctuating corrective torque (104) is substantially equal to the amplitude of the fluctuating load torque (103) when determined at conditions such that it is a maximum.
- 14. A synchronous drive assembly according to claim 1, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly varies, and the magnitude of the eccentricity of the non-circular profile (19) is such that the fluctuating corrective torque (104) has an amplitude in the range of 70% to 110% of the amplitude of the fluctuating load torque (103) when determined at the natural resonance frequency of the apparatus.
- 15. A synchronous drive apparatus according to claim 14, in which the said range consists of 90% to 100% of the amplitude of the fluctuating load torque (103) when determined at the natural frequency of the apparatus.
- 16. A synchronous drive apparatus according to claim 14, in which the amplitude of the fluctuating corrective torque (104) is substantially equal to the amplitude of the fluctuating load torque (103) when determined at the natural frequency of the apparatus.
- 17. A synchronous drive apparatus according to claim 1, in which the magnitude of the eccentricity of the non-circular profile (19) is such as to produce a periodic elongation and contraction of said drive span given by the formula:
- 18. A synchronous drive apparatus according to claim 17, in which the said operating conditions are such that the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) is substantially constant.
- 19. A synchronous drive apparatus according to claim 17, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) varies, and
T=the amplitude of the fluctuating load torque of the rotary load assembly (26) determined at conditions when it is a maximum.
- 20. A synchronous drive apparatus according to claim 17, in which the amplitude of the fluctuating load torque of the rotary load assembly (26) varies, and
T=the amplitude of the fluctuating load torque (103) of the rotary load assembly determined at the natural resonance frequency of the synchronous drive apparatus.
- 21. A synchronous drive apparatus according to claim 1 in which the said non-circular profile (19) is provided on the first rotor (11).
- 22. A synchronous drive apparatus according to claim 1, in which the said non-circular profile (19) is provided on the second rotor (12).
- 23. A synchronous drive apparatus according to claim 1, in which the non-circular profile (19) is provided on a third rotor (14).
- 24. A synchronous drive apparatus according to claim 23, in which the third rotor (14) comprises an idler rotor urged into contact with the continuous loop elongate drive structure (10), the third rotor (10) having a plurality of teeth (16) for engaging the engaging sections (15) of the elongate drive structure.
- 25. A synchronous drive apparatus according to claim 1, when installed in an internal combustion engine, the said first rotor (11) comprising a crankshaft sprocket.
- 26. A synchronous drive apparatus according to claim 25, in which the internal combustion engine is a diesel engine, and the said rotary load assembly (26) comprises a rotary fuel pump.
- 27. A synchronous drive apparatus according to claim 26, in which the magnitude of the eccentricity of the non-circular profile is such that the fluctuating corrective torque (104) has an amplitude substantially equal to the amplitude of the fluctuating load torque (103) when determined at conditions of maximum delivery of the fuel pump.
- 28. A synchronous drive apparatus according to claim 25, in which the internal combustion engine is a petrol engine and the rotary load assembly (26) comprises a camshaft assembly.
- 29. A synchronous drive apparatus according to claim 28, in which the fluctuating load torque (103) of the camshaft assembly is substantially constant throughout the rev range of the engine, and the amplitude of the fluctuating corrective torque (104) is substantially equal to the amplitude of the fluctuating load torque (103).
- 30. Apparatus according to claim 1, in which the non-circular profile has at least two reference radii (20A, 20B), each reference radius passing from the centre of the rotor on which the non-circular profile (19) is formed and through the centre of a protruding portion (22, 23) of the non-circular profile (19),
the angular position of the non-circular profile (19) being related to a reference direction (27) of the rotor on which the non-circular profile (19) is formed, the reference direction being the direction of a vector (27) that bisects the angle about which the elongate drive structure (10) is wrapped about the rotor having the non-circular profile (19), the angular position of the non-circular profile (19) being such that, when the fluctuating load torque of the rotary load assembly is at a maximum, the angular position of a reference radius (20A) is within a range of 90° to 180° from the reference direction (27) taken in the direction of rotation of the rotor on which the non-circular profile (19) is formed.
- 31. Apparatus according to claim 30, in which the angular position of the reference radius (20A) being within a range of 130° to 140° from the reference direction (27) taken in the direction of rotation of the rotor on which the non-circular profile is formed.
- 32. Apparatus according to claim 30, in which the angular position of the reference radius (20A) is substantially at 135° from the reference direction (27) taken in the direction of rotation of the rotor on which the non-circular profile is formed.
- 33. Apparatus according to claim 1, in which the said non-circular profile (19) is a generally oval profile.
- 34. Apparatus according to claim 1, in which the said non-circular profile (19) has three protruding portions arranged regularly around the rotor.
- 35. Apparatus according to claim 1, in which the said non-circular profile (19) has four protruding portions arranged regularly around the rotor.
- 36. Apparatus according to claim 1, in which the said protruding portions constitute major protruding portions (22, 23) and the said receding portions constitute major receding portions (24, 25), and the non-circular profile (19) includes additional minor protruding portions of lesser extent than the major protruding portions (22, 23), adapted to produce additional, minor, fluctuating corrective torque patterns in the torque applied to the second rotor (12), to reduce or substantially cancel subsidiary order fluctuating load torque presented by the rotary load assembly (26).
- 37. Apparatus according to claim 1, in which the continuous-loop elongate structure (10) is toothed belt.
- 38. Apparatus according to claim 1, in which the continuous-loop elongate structure (10) is a drive chain.
- 39. A method of operating a synchronous drive apparatus which comprises a continuous-loop elongate drive structure (10) having a plurality of engaging sections (15); a plurality of rotors comprising at least a first and a second rotor (11, 12), the first rotor (11) having a plurality of teeth (16) engaging the engaging sections of the elongate drive structure, and the second rotor (12) having a plurality of teeth (16) engaging the engaging section of the elongate drive structure; and a rotary load assembly (26) coupled to the second rotor; one of the rotors having a non-circular profile (19) having at least two protruding portions (22, 23) alternating with receding portions (24, 25), and the rotary load assembly (26) presenting a periodic fluctuating load torque (103) when driven in rotation;
the method comprising the steps of engaging the elongate drive structure about the first and second rotors, driving the elongate drive structure (10) by the first rotor (11), and driving the second rotor (12) by the elongate drive structure (10); characterised by applying to the second rotor (12) by means of the non-circular profile (19) an opposing fluctuating corrective torque (104) which reduces or substantially cancels the fluctuating load torque (103) of the rotary load assembly (26).
- 40. A method according to claim 39, including:
producing said opposing fluctuating corrective torque (104) by the non-circular profile (19) by a periodic elongation and contraction of spans of the elongate drive structure including a drive span (10A, 10B) on the tight side of the non-circular profile (19); and producing a maximum elongation of the said drive span (10A, 10B) at an angular position of the non-circular profile (19) which is within +/−15 degrees of an angular position for which a maximum elongation of the said drive span (10A, 10B) coincides with a peak value of the fluctuating load torque (103) of the rotary load assembly (26).
- 41. A method according to claim 39, including producing a maximum elongation of the said drive span (10A, 10B) at a time which substantially coincides with a peak value of the fluctuating load torque (103) of the rotary load assembly (26).
- 42. A method according to claim 39, including applying to the second rotor (12) a fluctuating corrective torque (104) which has an amplitude in the range of 70% to 110% of the amplitude of the fluctuating load torque (103) at selected predetermined conditions for which reduction or substantial cancellation of fluctuating load torque (103) is required.
- 43. A method according to claim 42, including applying to the second rotor (12) a fluctuating corrective torque (104) which is substantially equal to the amplitude of the fluctuating load torque (103) at selected predetermined conditions for which reduction or substantial cancellation of fluctuating load torque is required.
- 44. A method according to claim 39, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) is substantially constant, and the method includes applying to the second rotor a fluctuating corrective torque which has an amplitude in the range of 70% to 110% of the amplitude of the fluctuating load torque.
- 45. A method according to claim 44, including applying to the second rotor a fluctuating corrective torque (104) which is substantially equal to the amplitude of the fluctuating load torque (103).
- 46. A method according to claim 39, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) varies, and the method includes applying to the second rotor a fluctuating corrective torque (104) which has an amplitude in the range of 70% to 110% of the amplitude of the fluctuating load torque (103) when determined at conditions such that it is a maximum.
- 47. A method according to claim 46, including applying to the second rotor a fluctuating corrective torque (104) which is substantially equal to the amplitude of the fluctuating load torque (103) when determined at conditions such that it is a maximum.
- 48. A method according to claim 39, including applying to the second rotor a fluctuating corrective torque (104) which has an amplitude in the range of 70% to 110% of the amplitude of the fluctuating load torque (103) when determined at the natural resonant frequency of the apparatus.
- 49. A method according to claim 46, including applying to the second rotor a fluctuating corrective torque (104) which is substantially equal to the amplitude of the fluctuating load torque (103) when determined at the natural resonance frequency of the apparatus.
- 50. A method of constructing a synchronous drive apparatus, comprising:
assembling components comprising a continuous-loop elongate drive structure (10) having a plurality of engaging sections (15); a plurality of rotors comprising at least a first and a second rotor (11, 12), the first rotor having a plurality of teeth (16) for engaging the engaging sections of the elongate drive structure (10), and the second rotor (12) having a plurality of teeth (16) for engaging the engaging section of the elongate drive structure (10); and a rotary load assembly coupled to the second rotor (12); and engaging the elongate drive structure about the first and second rotors, the first rotor (11) being arranged to drive the elongate drive structure (10) and the second rotor (12) being arranged to be driven by the elongate drive structure (10), and one of the rotors having a non-circular profile (19) having at least two protruding portions (22, 23) alternating with receding portions (24, 25), the rotary load assembly (26) being such as to present a periodic fluctuating load torque (103) when driven in rotation; characterised by the steps of determining the angular positions of the protruding and receding portions of the non-circular profile (19) relative to the angular position of the second rotor (12), and the magnitude of the eccentricity of the non-circular profile (19), to be such that the non-circular profile (19) applies to the second rotor (12) an opposing fluctuating corrective torque (104) which reduces or substantially cancels the fluctuating load torque (103) of the rotary load assembly (26).
- 51. A method according to claim 50, including:
arranging the non-circular profile (19) to produce the said opposing fluctuating corrective torque (104) by periodic elongation and contraction of the spans of the elongate drive structure (10) adjoining the rotor on which the non-circular profile (19) is formed, the elongate drive structure (10) having a drive span (10A, 10B) between the rotor on which the non-circular profile is formed and the second rotor, the drive span being positioned on the tight side of the rotor on which the non-circular profile is formed; and determining the angular positions of the protruding and receding portions of the non-circular profile (19) by arranging the angular position of the non-circular profile to be within +/−15 degrees of an angular position for which a maximum elongation of the said drive span (10A, 10B) coincides with a peak value of the fluctuating load torque (103) of the rotary load assembly (26).
- 52. A method according to claim 51, including arranging the angular position of the non-circular profile (19) to be within +/−5 degrees of the angular position for which a maximum elongation of the said drive span (10A, 10B) coincides with a peak value of the fluctuating load torque (103) of the rotary load assembly (26).
- 53. A method according to claim 52, including arranging the angular position of the non-circular profile (19) to be that for which a maximum elongation of the said drive span (10A, 10B) substantially coincides with a peak value of the fluctuating load torque (103) of the rotary load assembly (26).
- 54. A method according to claim 50, in which the magnitude of the eccentricity of the non-circular profile (19) is determined by the following steps:
(i) measuring the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) at a predetermined selected set of operating conditions of the synchronous drive apparatus; (ii) calculating the required amplitude of periodic elongation and contraction of the said drive span (10A, 10B) by the following formula: 7L=TrkL=the amplitude of the periodic elongation and contraction of the said drive span (10A, 10B); T=the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) at a predetermined selected set of operating conditions of the synchronous drive apparatus; r=the radius of the second rotor (12): k=the stiffness coefficient of the elongate drive structure (10) defined as 8k= dF d L where dF is the force required to produce an increase of length dL in the length of the structure. (iii) producing and recording data to relate empirically a series of values of (a) the divergence from circular of the said protruding and receding portions of the non-circular profile (19) and (b) the resulting amplitude of the periodic elongation and contraction of the said drive span (10A, 10B); and (iv) selecting from the data the corresponding eccentricity to give the required amplitude of the periodic elongation and contraction of the drive span (10A, 10B).
- 55. A method according to claim 54, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) is substantially constant.
- 56. A method according to claim 54, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly (26) varies, and is determined at conditions such that it is a maximum.
- 57. A method according to claim 54, in which the amplitude of the fluctuating load torque (103) of the rotary load assembly varies (26), and is determined at the natural resonance frequency of the apparatus.
Parent Case Info
[0001] The present application claims priority to U.S. Provisional Application of Gajewski, Application Nos. 60/333,118, filed Nov. 27, 2001 and 60/369,558, filed Apr. 24, 2002, the entirety of which are hereby incorporated into the present application by reference.
Provisional Applications (2)
|
Number |
Date |
Country |
|
60333118 |
Nov 2001 |
US |
|
60369558 |
Apr 2002 |
US |