Patent GB-1044037-A (GB)
Title: Automatic fuel antiknock rating apparatus
IPC: G01N33/28
Filed: 1963-06-25
Abstract: 1,044,037. Detecting detonation; variable compression-ratio engines. ETHYL CORPORATION. June 25, 1963 [June 25, 1962], No. 25206/63. Heading FIB. [Also in Division G1] An apparatus for determining the antidetonation rating of a fuel comprises a test engine 10, Figs. 1 and 2, with a detonator pick-up 70, a first actuator 12 for changing its compression ratio and a second actuator 74 for varying the fuel-air ratio. The signals from the pick-up 70 are fed to a deviation computer 18 which evaluates the deviation of the detonation intensity from a standard knock intensity and actuates a deviation reducing control 24 which operates the first actuator 12 to change the compression ratio so that the detonation is reduced to the standard value. An automatic sequencing device 28 produces the following sequence of events:-(1) causes the actuator 12 to alter the compression ratio to bring the knock to standard intensity (II) causes the second actuator 14 to reduce the fuel-air ratio to a lean value (III) causes the second actuator 14 to increase the fuel-air ratio until maximum knock is reached (IV) causes the actuator 12 to alter the compression ratio until standard knock intensity is again reached, the latter compression ratio giving an indication of the anti-detonation value of the fuel, which can be shown on an indicator 30. The knock signals from the pick-up 70 are fed to a recorder having a pulley 98 controlling a recording pen, the movements of the pen being transmitted to a centre tap 96 of a potentiometer 94 which is compared electrically with a pre-set potentiometer 345 setting the standard knock intensity. If 94 is unbalanced compared with 345, one of the thyratrons 302, 303, is fired to produce a pulse in the lead 351, 353, to actuate the reversible motor 12 and increase or decrease the compression ratio, the pulses being fed to motor 12 until standard knock intensity is obtained and 94 is balanced with 345. The sequence of events in a test cycle is automatically controlled by a stepping solenoid 114 with wafer switches A ... F. After setting the engine to standard knock intensity, reversible motor 14 is energized to lower carburetter float chamber 60 to reduce the fuel air ratio, which reduces the knock causing pulley 98 to rotate anticlockwise until arm 100 thereon closes switch 101 which causes reversal of motor 14 to raise chamber 60 in intermittent steps to enrich the fuel air ratio and increase the knock intensity, rotating pulley 98 clockwise. A pin 264 thereon, Fig. 5 (not shown), holds switch 252 closed until maximum knock is reached when pulley 98 starts to reverse and switch 252 opens to stop motor 14. Motor 12 is then re-energized to reduce the knock to standard value and obtain the anti-detonation rating. If during the process of decreasing or increasing the fuel-air ratio a predetermined knock value is exceeded, switch 102 is closed by arm 100 to stop motor 14 and operate motor 12 to re-establish standard knock intensity, after which the variation of the fuelair ratio to establish maximum knock is resumed. The time-constant of the knock-response device 70 is automatically varied in dependence upon the amount by which the initial knock intensity differs from standard knock intensity. The pulse circuit deviation control of Fig. 4 may be replaced by a meter-type device 556, Fig. 9 (not shown), in which the knock signals move a pointer 552 over a series of arcuate contacts 561-570 controlling relays 571-580 which cause actuation of motor 12 in one direction or the other. Needle 552 normally clears the contacts 561-570 but is moved into contact therewith periodically when an electromagnet is energized by periodic pulses. Standard knock intensity occurs when the needle 552 is opposite the gap between the two halves of the set of contacts, deviation of the needle to either side causing actuation of motor 12 in the appropriate direction. An alternative embodiment utilizes a pair of photoelectric devices covered by a plate on a swinging arm, movement of the arm in accordance with the knock signals in one direction or the other actuating the motor 12 until standard knock condition is obtained. In Fig. 11 (not shown) the deviation reducing control 710 is used to produce signals which operate a reversible motor 700 controlling a blending valve 654 controlling the mixing of an anti-detonant from line 652 with fuel from line 651 to obtain a blended fuel in outlet 656 of predetermined anti knock value. An automatic timing mechanism 750, 751, first operates the test engine on reference fuel from chamber 663, the signals from the deviation reducing control energizing a motor 720 to set a reference potentiometer 745 to a value representative of the anti-detonation value of the reference fuel. A changeover is then made to operating the engine on blended fuel from the outlet 656, the signals from the control 710 actuating a second motor 700 to adjust the blending valve 654 until an adjustable potentiometer 794 is in balance with pre-set potentiometer 745.