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 bulletin for the 'Autopulse' electric fuel pump covering its service, capacity, life, efficiency, and operation.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan024 | |
| Date | 15th July 1926 guessed | |
| Page 7 (Column 1) ...may be made with the vehicle, increasing the power delivery until lack or a sufficient supply of fuel is indicated with each unit; thus comparing their capacity and functioning. Instead of operating the vehicle, the same test may be made by removing the pipe plug (ignition switch off) in the end of the delivery manifold and connecting a short piece of pipe for delivery, or, if both ends of the manifold are pipe connected to the carburetor, one may be disconnected at the carburetor. Place a vessel under the end of this pipe to catch the fuel and turn on the switch. SERVICE In case of accident to the AUTOPULSE, it is generally advisable to replace it with a new unit. It is so small in size and weight that it can handily be carried in the tool receptacle or car pocket. It is very rugged and reasonable handling will not affect its calibration. Replacement service is as simple and convenient with the AUTOPULSE as with a spark plug. Only the upper chamber of the AUTOPULSE normally contains fuel (indicated by arrows in diagram illustration). Should a leak occur, possibly due to defective material, the fuel will drain down and onto the breaker contacts. In time the contacts will become carbonized or greasy and will cause the operation to become more or less erratic or even fail. A leak will develop gradually and this warning is given while it is still so small that it will cause very little inconvenience. Operation for considerable traveling can be obtained, after this warning is given, by observing the following instructions: (1) Sharply rap the top of the AUTOPULSE with a block of wood while the current is applied. This will usually produce results and may be all that is required. (2) In case it cannot be kept going, the remedy (1) being insufficient, CUT OFF THE IGNITION SWITCH, loosen the pipe connections and turn the AUTOPULSE bottom side up. Then tighten the pipe connections, remove the cap screw (13) (See diagram cut), the magnetic shell (15) and allow the fuel to dry off somewhat. Clean the contacts with a file or a LINEN cloth (no fuzz). Replace shell, driving spring and screw. The fuel will not drain onto the contacts and it should now give considerable service. The bottom side up installation is not specified as a regular mounting because it is desirable to have this warning given, in time, when a leak occurs and also to prevent water and dirt collecting in chamber (17). The agitation of the pumping element or bellows does not permit this accumulation when right side up. (Column 2) Note: The AUTOPULSE will not operate without the magnetic shell (15). The AUTOPULSE is practically SEALED AGAINST OUTSIDE FUEL LEAKAGE and there is no danger of fire from an inside leak. It is almost impossible to fire gasoline under the condition maintained within the AUTOPULSE, and, even if it were possible, there could be no harm, as there is very little air to support the combustion. A large mesh screen is provided to prevent fuzz and or dirt from getting into the coarse particles of metal from the valves. See (7) (on diagram cut). CAP SCREW (8) SHOULD NOT BE REMOVED unless the ammeter indicates a restriction. See (3) under Operation Tests it is removed, the gasket (9) must be carefully replaced and preferably shellaced. A leak at this gasket will allow air to enter. If suction valve (6) is removed, attention must be given to properly replacing the three parts in order. The spring, the cork gasket (5) and the other should be placed within the small hole up. The boss at the center of the valve, should be placed in the hole with the polished seat up. The assembly is completed by snapping the cap over the end of the cage. Delivery valve (4) SHOULD NEVER BE REMOVED... the screw directly above the valve holds it in place... screw may result in the displacement and loss of the valve. In the "MULTIPLE" INSTALLATION the units are connected together by fittings which are clamped together by bolts and gasketed with cork. ANY UNIT MAY BE REMOVED from the line and REPLACED without disturbing the other units. CAPACITY The AUTOPULSE unit is adjusted to deliver about eight gallons of gasoline an hour through an orifice 1/16" in diameter while lifting 18" to 20" and operating upon a battery current of the rated voltage as marked (6V or 12V). Under the same conditions, except for a larger orifice or unrestricted delivery, it has a capacity of about 12 gallons an hour. This 50% surplus over the rated capacity is a reserve for possible reduced voltage, increased elevation, valve leakage, restrictions and general deterioration. The operation is satisfactory over the very wide RANGE OF VOLTAGE encountered in vehicle service. The safe operation is at least one-third of the rated voltage and the capacity may increase greater than the rated... Page 8 (Column 1) ...slightly with the increase in voltage. Two-thirds of the rated voltage will deliver 85% capacity, and one-third of the rated voltage will produce operation and strong engine idle. The VARIATION IN LIFT, represented by the difference in height of the pump over the fuel level, has only a slight effect upon the capacity for any condition encountered upon a vehicle. A change from 1½ feet to 5 feet will reduce the capacity about ½ gallon per hour. The variation in lift, due to grade in the case of an automobile, does not affect the delivery pressure. The suction stroke is magnetic and an increase in suction, due to increased elevation or other causes, is compensated for by an increase in electrical power. FOR GREATER CAPACITY than the UNIT rating, additional units are required. Any number of units can be used in multiple or manifolded. The illustration below shows a five combination. When connected in this manner each unit operates independently of every other unit and each will deliver its proportion of the fuel used at all times to the extent of the full capacity of each, and be governed by the same pressure conditions as is each unit. That is, the maximum pressure attained does not increase with the increase in the number of units, but, for any given... (Column 2) ...quantity, the delivery pressure will be maintained at more nearly the maximum, the greater the number of units. The rated capacity of a five-unit pump is 40 gallons of gasoline per hour with an unrestricted delivery of 50 to 60 gallons per hour. This "quintette" is suitable for a "Liberty Twelve" engine. (450 H.P.). The AUTOPULSE CAPACITY FOR PUMPING AIR is greater than for fuel. When pumping air alone the stroke lengthens and doubles in speed. Because of this characteristic, a considerable air leakage into the suction line can be overcome and a quick pick up, from an empty system, obtained. There is no time lag in the delivery of fuel from the AUTOPULSE. It will instantly change from zero to full capacity upon demand. Full delivery pressure at the carburetor will usually be attained... [Image Caption: "Quintette" (½ size) Height, 3½"; width, 5¾"; length, 11". Bracket holes, ¼"; center distance, approximately 8¾". Pump centers, 2-1/8". All openings ⅛" pipe tap] The capacity is directly affected by the CHANGE IN PRESSURE UPON THE DELIVERY SIDE of the AUTOPULSE. The delivery stroke is spring-actuated and adjusted to raise a column of gasoline to a maximum height of 50" to 60" above the pump outlet. This "head" represents the pressure at which the electrical contacts will be held apart and, therefore, no current is used or fuel pumped. This pressure condition is instantly attained upon the closing of the carburetor float valve when the pump is installed at the same level as the carburetor. The calibration pressure will be directly increased or diminished as the pump is raised or lowered in respect to the carburetor. When the fuel is flowing, the delivery pressure is governed by the restriction at carburetor valve and the pressure is less than when at rest. It requires a gasoline head of about 40" to force gasoline at a rate of 8 gallons an hour through a round orifice 1/16" in diameter. Page 9 (Column 1) ...before the engine is cranked. The ignition switch being operated in the customary manner. LIFE The life of the AUTOPULSE is MEASURED BY THE NUMBER OF GALLONS OF FUEL PUMPED and is practically independent of the time period required. When there are no air or gasoline leaks, there is no waste pumping. Laboratory tests indicate that the life of AUTOPULSE UNIT, when pumping gasoline, is from 10,000 to 20,000 gallons, and a single unit should, therefore, outwear most engines of corresponding capacity. The tests also show that the average duty, without need of adjustment, should be the pumping of more than 6,000 gallons. Few automobiles use more than 1,000 gallons per year and the average is less than 500 gallons. The wearing away of the contact points is compensated for by other characteristics to a great extent. In some cases, however, there may be a capacity loss of 10% during the first 6,000 gallons pumped. Should AIR BE ALLOWED (See Operation Tests and Checks) to enter the suction line, waste pumping will be caused to an extent represented by the proportion of air entering and the useful life will be reduced in a like proportion. The total air pumping in the life of a vehicle would probably not be an hour. It occurs only for a short period when the system is first supplied with fuel and upon other occasions more or less accidental. The AUTOPULSE operates at a high rate of speed and under a severe strain when upon air alone; but it will withstand several hundred hours of continuous air pumping at its rated voltage before rupture of the pumping element occurs. The pumping element or bellows was especially developed for the AUTOPULSE. It is strengthened by overlapping and soldering at the bends, where the greatest strain occurs, thereby causing the flexing to occur at the proper place in the diaphragms. The process used in producing this bellows has resulted in greater uniformity and several times the life of the usual bellows product. The AUTOPULSE is GUARANTEED AGAINST DEFECTS IN MATERIAL AND WORKMANSHIP. EFFICIENCY The AUTOPULSE requires so little power that its amount need not be taken into account in respect to battery capacity. It requires about one ampere to pull the stroke, but, on account of the intermittent action, the ammeter reading or average flow at rated capacity is only ¼ to ½ ampere. About 50 ampere... (Column 2) ...hours are required for pumping 1,000 gallons, or less than ½ a small battery charge for a year or more of hard automobile driving. For six-volt rating. For twelve volts the current values are reduced nearly one-half. 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 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. A third ball is located over the axis of the other balls in a spring which holds the armature rigidly against unbalanced motion. This bearing allows the armature a lost motion due to wear. The stroke, which is electromagnetically operated by the "working" coil is rising 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 winding." This is another new secondary magnet which replaces, and is cheaper than, and much more effective than any condenser. It is installed in so small a container which could be used as follows: The current in the "working" coil is rising rapidly at the time of break and 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. [Handwritten: Correct] [Handwritten: E7C] A SUB-ATMOSPHERIC CHAMBER is provided upon the suction side of the pumping element. The stretching of the bellows in this chamber allows the 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 "cut-away prospective" drawing. Before the current is... Page 10 (Column 1) ...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 it is maintained high throughout the suction stroke by the magnetic action of the breaker spring (11) and sleeve. 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 magnet. A quick break is produced by the spring "set up," after the magnetic stress is removed from the spring (11). The armature (10) is pivotally attached at its center to the expansible bellows (3) and the action just described completes the suction stroke by expanding the bellows. This suction stroke and by expanding draws fluid from the supply tank through the threaded opening (2), through screen (7) which contains the closed air chamber (17), through screen (7) and monel disk valve (6) into the bellows (3). (Note that 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 into the line leading... (Column 2) ...to the carburetor. This opening (1) until the electrical contacts touch together again. If the engine is stalled and the outlet is restricted, the enclosed liquid will prevent the bellows from collapsing and the next suction stroke will be prevented. This action constitutes the control. The driving spring (14) and the shell are held in place by the gasketed base casting until some of the liquid escapes. The bellows are sealed by a cork gasket. The shell and gasket are sealed against gasoline leakage by a cork laced 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 rubber-covered binding post on base, down through the screw in the insulated spacer sleeve to a spring, which is in the reverse direction to it. This upon the underside of the fiber sleeve, through breaker spring, the screw head, through the insulated contact held in place by said screw and sleeve, through breaker spring, 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 by the position of the spring (11) with 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 2,500 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. The contacting is further assisted by a slight rubbing action due to the mounting of the contacts at an angle to their travel. [Image Caption: Cut-away prospective / Actual size] 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. | ||