From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Technical explanation, operating principles, and ordering instructions for the AUTOPULSE electric fuel pump.
| Identifier | ExFiles\Box 41\1\ Scan035 | |
| Date | 30th November 1926 guessed | |
| The best operation is obtained in winter weather when the need is greater. The lower the temperature, the higher the efficiency and the lower the voltage value at which operation will take place. TECHNICAL EXPLANATION The AUTOPULSE is the result of more than two years of intensive experimental and research work. It has been perfected with the invaluable assistance and enthusiastic co-operation of the engineers of many of the principal automobile factories. A novel type of ELECTRICAL MOTOR has been devised EMBODYING TWO NEW MAGNETIC OPERATION PRINCIPLES and several new construction details. Its action is reciprocating, the armature being angularly oscillated upon two steel balls, located near its edge and embedded in hardened steel sockets. Two additional balls complete the assembly and are located over the axis of the other balls in a spring socket. This bearing holds the armature rigidly against unbalanced magnetic side pull, and prevents lost motion due to wear. The stroke, which is controlled by the new magnetically operated breaker principle, is positive and timed as to length and speed (not a vibration). THE ARCING OF CONTACTS is reduced to the vanishing point by means of a “short-circuited secondary magnet winding.” This is another new magnetic principle. It replaces, and is cheaper than a condenser. It is much more effective than any condenser which could be installed in so small a container, and functions as follows: The current in the “working” coil is rising rapidly at the time of break and its magnetic field has induced a current in the closed circuit secondary, which is in the reverse direction to it. This current, being demagnetizing, neutralizes the effect of self-induction at time of break. A SUB-ATMOSPHERIC CHAMBER is provided upon the suction side of the pumping element. The stretching of the air in this chamber allows the armature to complete its stroke without drawing an excessive current, which would otherwise be caused by the inertia effect of a long column of liquid in the suction pipe. It provides a more uniform flow of liquid in this pipe. The operation is explained by reference to the “cutaway prospective” drawing. Before the current is applied, the tungsten contact at (11) is held in contact with another tungsten contact (not shown in drawing, but can be seen in the view having the cover removed) by the delivery spring action. The contact pressure is high in the rest position of the armature and is maintained high throughout the suction stroke by the magnetic action of the breaker. A sleeve of steel (12), which is attached to the spring (11) and is centrally located in the hole through the steel core of the magnet (16), tends to move upwards with force toward the armature (10), thereby stressing the spring (11) and holding the contacts under pressure until the armature, which is pulled toward the magnet, hits the spring (11) and forces the contacts apart. A quick break is produced by the spring movement due to “set up,” after the magnetic stress is removed from the spring (11). The armature (10) is privotly attached at its center to the expansible pumping element or bellows (3) and the action just described completes the suction stroke by expanding the bellows. This action draws fluid from the supply tank through the threaded opening (2), through slots around the under side of the cap screw (8) which contains the closed air chamber (17), through screen (7) and monel disk valve (6) into the bellows (3). (Note the arrows). Valve (6) closes as the armature begins its delivery stroke, powered by the energy stored in the calibrated driving spring (14), which collapses the bellows (3), driving the liquid out through valve (4) and opening (1) until the armature travel brings the contacts together again. If the passage is filled with liquid and the outlet is restricted, the enclosed liquid will prevent the bellows collapsing and the next suction stroke will be prevented until some of the liquid escapes. This action constitutes the control. The driving spring (14) and the magnetic shell (15) are held in place by the gasketed cap screw (13) and the shell and the bellows are sealed against gasoline leakage by a cork gasket. The shellac-lacquered fiber gasket (9) seals cap (8). Referring to the illustration having the shell (15) removed (page 4), the electrical circuit is as follows: Battery to switch (not shown), switch to binding post on base, down through the screw in the insulated spacer sleeve to magnet wire terminal upon the underside of the fiber spool head and under the screw head, through the magnet winding to the insulated contact held in place by said screw and sleeve, through breaker spring, armature, base casting and to the battery, through fuel pipes and engine or directly by wire. The length of stroke of the armature is from .025" to .030" and is determined or controlled as to length by the position of the spring (11), not stressed, in respect to the armature. About 5,000 strokes are made to the gallon of fuel and at the rate of 800 to 1,000 per minute, maximum capacity. In pumping air the length of stroke is doubled and the speed about 1,500 to 2,000 per minute. When the armature comes to rest, with no pressure within the bellows, it has taken a position much higher or traveled farther than it does during stroking. This greater or surplus travel represents set-up pressure for the contact. That is, if electrical contact is not established at the end of the normal stroke or when the “points” touch, the travel of the armature will be continued for a distance of two or three times the stroke or until the electrical resistance is broken down. When a PERMANENT HYDRAULIC PRESSURE is established, as, for instance, by mounting the AUTOPULSE below the carburetor or other delivery point, this “set-up,” or pressure upon the contacts, is reduced. A permanent head of two feet of gasoline upon the delivery side would reduce the FACTOR OF SAFETY in MAKING CONTACT by nearly one-half. This reserve contact pressure, or “follow-up,” is an important feature. It is needed in emergencies for breaking down the resistance which may be introduced by oxidation or other interferences. Under proper conditions, this “follow-up” is sufficient to prevent open circuit failure until the tungsten is entirely gone from the contact points. MARINE APPLICATION As all the fuel feed systems, viz: gravity, air pressure, vacuum tank and water suction, have been unsatisfactory, especially IN SPEED BOATS, for one reason and another, the AUTOPULSE SYSTEM has been enthusiastically received by owners and boatbuilders alike and is rapidly being adopted as standard equipment by Boat Builders and Marine Engine Manufacturers. It is also replacing or supplementing all other systems. The AUTOPULSE CAN BE INSTALLED and FORGOTTEN. The AUTOPULSE is sealed and will not be internally affected by corrosion. In case it is desirable to change the color or further protect the AUTOPULSE by painting, care must be used not to CLOSE THE VENT. This is a small hole located in the center of the bolt head at the bottom of the case. Cut-away Perspective Actual Size Instructions for Ordering 1. Always specify battery voltage. 2. State maximum consumption of fuel in gallons per hour or other information indicating the AUTOPULSE capacity required. 3. If any of the illustrated single unit fittings for mounting are required, order by catalog number. We do not supply standard tube connections. 4. When ordering Duplex (two units) installation, specify direction of pipe connection (see page 8). Unless otherwise specified, the manifolds will be connected as shown in illustration on page 8. In reference to mounting bracket, in Triplex or other multiple installations, four openings are provided. 5. On Duplex, either one or the other of two sizes of manifolds may be furnished accommodating two sizes of pipe threads, 1/8" and 1/4"; unless otherwise specified the 1/8" will be furnished. 6. Four foot lead wires are furnished for all installations. If special length is desired, please specify. 12 13 | ||