Timing angle and speed measurement of shafts

Claim 1

A system having first and second rotatable shafts (16,19) and timing means (18) rotatably driving one of the shafts (19) from the other (16) and for varying, within a predetermined range, the angular relationship between the shafts (16,19), characterized by at least one first member (47) rotatable at a speed proportional to the speed of the first shaft (16) and movable through a first circular path; a first signal generating means (48) for generating a first signal (49) in response to movement of the or each first member (47) past a predetermined point (50) in the first circular path; at least one second member (53) rotatable at a speed proportional to the speed of the second shaft (19) and movable through a second circular path; a second signal generating means (54) for generating a second signal (55) in response to movement of the or each second member (53) past a predetermined point (56) in the second circular path; clock means (65) for generating a series of fixed frequency clock pulses; counting means (78) for; a) obtaining a first count of the number of clock pulses occurring in the time interval (T 1 ) beginning and ending with consecutive signals (49) from one (48) of the signal generators (48,54); and b) obtaining a second count of the number of clock pulses occurring in the time interval (T 2 ) beginning with a signal (55) from one (54) of the signal generators (48,54) and ending with a successive signal (49) from the other (48) of the signal generators (48,54); and angle-indicating means (79-83) for generating an angle-indication signal proportional to the ratio of the first and second counts of the counting means (78) to provide an indication of the relative timing between the shafts.

Claim 2

A system having first and second rotatable shafts (16,19) and timing means (18) rotatably driving one of the shafts (19) from the other (16) and for varying, within a predetermined range, the angular relationship between the shafts (16,19), characterized by at least one first member (47) rotatable at a speed proportional to the speed of the first shaft (16) and movable through a first circular path; a first signal generating means (48) for generating a first signal (49) in response to movement of the or each first member (47) past a predetermined point (50) in the first circular path; at least one second member (53) rotatable at a speed proportional to the speed of the second shaft (19) and movable through a second circular path; a second signal generating means (54) for generating a second signal (55) in response to movement of the or each second member (53) past a predetermined point (56) in the second circular path; clock means (65) for generating a series of fixed frequency clock pulses; counting means (78) for; a) obtaining a first count of the number of clock pulses occurring in the time interval (T 1 ) beginning and ending with consecutive signals (49) from one (48) of the signal generators (48,54); and b) obtaining a second count of the number of clock pulses occurring in the time interval (T 2 ) beginning with a signal (55) from one (54) of the signal generators (48,54) and ending with a successive signal (49) from the other (48) of the signal generators (48,54); and angle-indicating means (79-83) for generating an angle-indication signal proportional to the ratio of the first and second counts of the counting means (78) to provide an indication of the relative timing between the shafts.

Claim 5

A system according to any of the claims 1 to 3, including first and second circular members (12,52) each rotatable about the respective centres thereof, the first circular member providing an equiangularly spaced plurality of first members (47) and the second circular member providing an equiangularly spaced plurality of second members (53).

Claim 6

A system according to any of claims 1 to 4, wherein the length of time between successive signals (49) of the first signal generating means (48) is equal to the length of time between successive signals (55) of the second signal generating means (54).

Claim 7

A system according to any of claims 1 to 5, wherein the number of first and second members (47,53) is such that N number of each of the first and second signals (49,55) are generated during one full revolution of one of the first and second shafts (16,19), N being an integer, the counting means (78) is arranged to obtain N/M number of successive first and second counts during one full revolution, M being an integer, and wherein the angle-indicating means (79-83) generates N/M number of successive angle-indicating signals during one full revolution, and including angle-averaging means (84,85) for generating an average-angle signal equal to the sum of NP/M number of successive angle-indicating signals divided by the number NP/ M , wherein P is an integer representing a predetermined number of successive full revolutions.

Claim 8

A system according to any of claims 1 to 6, wherein the counting means (78) obtains the first count by obtaining (69a) a third count of the number of clock pulses occurring in the time interval (T 3 ) between two successive time intervals (T 2 ) and by adding (69b) the third count of one of the second counts.

Claim 9

A system according to any of claims I to 6, wherein the counting means (78) includes first and second pulse counters (69,77), a first gate (66) connected between the clock means (65) and the first pulse counter (69), and a second gate (67) connected between the clock means (65) and the second pulse counter (77), the first gate (66) being successively closed and opened in response to successive signals (49) from one (48) of the signal generating means (48,54), and the second gate (67) being closed in response to a signal (55) from the other (54) of the signal generating means (48,54) and opened in response to a signal (49) from the one (48) signal generating means (48,54).

Claim 12

A system according to any of claims 1 to 10, wherein TIM = (T 2 /T 1 ) K T in which TIM = the angle-indicating signal, T 1 = the first count of the counting means, T 2 = the second count of the counting means, K T = a constant, and the angle-indicating means (79-83) being arranged to a) generate an initial reference angle-indicating signal TIM(o), b) generate a subsequent angle-indicating signal TIM(t), c) generate a corrected angle-indicating signal TIM(T), wherein TIM(T) = TIM(t)-TIM(o), when TIM(t) ≥ TIM(o), and TIM(T) = TIM(t)+K T -TIM(o), when TIM(t)< TIM(o).,

Claim 13

A system according to any of claims 1 to 11, which includes an engine (10), an engine-driven crankshaft (11), a first gear (14) fixed to the first shaft (16), a second gear (13) fixed to the crankshaft (11) and in mesh with the first gear (14), a fuel pump (21) for delivering fuel to the engine (10), the fuel pump (21) having a drive shaft (19) comprising the second shaft, and the first and second gears (14,13) having a gear ratio such that the first shaft (16) is rotated through a ful revolution for each two full revolutions of the crankshaft (11).