US2639673A

US2639673A - Pump or motor

Info

Publication number: US2639673A
Application number: US10495A
Authority: US
Inventors: Hadekel Ruben
Original assignee: Electro Hydraulics Ltd
Current assignee: Electro Hydraulics Ltd
Priority date: 1945-04-13
Filing date: 1948-02-24
Publication date: 1953-05-26
Anticipated expiration: 1970-05-26

Description

May 26, 1953 R. HABE-:KEL-

PUMP 0R MOTOR 2 Sheets-Sheet l Filed Feb. 24, 1948 I I l l I `I I Mo 18o 24o 30o l j l l l 18o' 24o Soo 360 R. HADEKEL PUMP OR MOTOR May 26, 1953 2 Sheets-Sheet 2 Filed Feb. 24, 1948 m M m 1 A www MW w Patented May 26, 1953 UNITED STATES PATENT OFFICE FUMI? OR MOTOR Ruben Hadekel.. Warrington,4 England, assignol'. to.4 Electro-Hydraulics Limited, Warrington, England, a, Brit-isla company Application Echi-.nary 24, 1948, Serial No.` 10,495

In Great, Britain April- 13, 1945 Section I, Public Law 690, August 8, 1946 Patent expires April 13, 1965 1 Claim..

This invention relates to gas or liquid multipiston pum-ps or motors, the terms pumps or motors hereinafter being used broadly to include multi-cylinder or liquid pumpsy internal combustier-1 engines and other devices. wherein rotary motion is converted into gas or liquid pressure or vice versa..

In such devices, a constant rotational crankshaft speed corresponds to a pulsating variation in each cylinder and although the outputs of the cylinders are additive. the resultant still contains a substantial pulsating, component or ripple.

:suoli pumps or motors usually have a plurality of piston-cylinder or equivalent pairs, so arranged as to deliver iluid in determinate se.-

quence. For instance in. a four cylinder piston pump the pistons may be driven lby cranks set at 99 speurt,y so that one pistonis phased with respect to another, that is to.- sey, one piston cemmences to deliver one quarter oi a crank revolution before the preceding one. This phasing of the pistons may correspond to actual physical angles between crank throws it the pis-tons are crankshaft driven and set in line; in a crank mechanism with radial arrangement of cylinders it may :correspond to 'angles between the axes of the cylinders.

With such piston pumps or motors as at present known, the diierence in phase between each piston and the next piston is equal; for example, in a `seven piston pump the difference in phase between each piston vand the next is degrees. It is known that such pumps having an even number oi pistons are markedly interior in point of smoothness of delivery to those pumps having an odd number of pistons.

|ihis invention relates to that type of pump or motor in which the iluid chamber is caused to change its volume according Ato an approximate sinusoidal law and is applicable `more particularly to that type comprising' a number of chambers the volume oi which varies approximately according to a simple harmonie law and includes, for example mechanism in which each piston performs two complete to-and-irc motions for one complete revolution of the driving member.

The object of thisinvention is to reduce what may be termed the overall resultant ripple ampltude for a. given number oi pistons the object being achieved by so arranging the phasing o the pistons as to increase the overall resultripple frequency.

In a pump or motor ci the type described according to the present invention an even number of pistons is provided which is not divisible by 4, the pistons `beingr so arranged that the phase diilerence between succeeding pistons is 2 alternately one half and one-and-a-hali times the average phase diderence, the latter 'being edual 360 divided 'by the total number of pistons.

The pistons may, if desired, -be arranged in two banks.

The term phase angle, or phase dierence as. used according to this invention.. is intended to cover the measurement oi displacement of, a piston in such a manner that 360 represent a complete cycle or to-and-fro motion, irrespective of the actual rotation of the driving member.

In order to explain the. mode of. functioning ci a pump; or motor :constructed according to this invention, reference will now be made. to the accompanying diagrammatic drawing, in which Fig. l is a diagrammatic representation of portions of a conventional three cylinder pump or motor showing an angle between adjacent crank throws of 120,

2 is a diagrammatic representation showing thevv rates of delivery from the cylinders of the same,

Fig. is a view similar to Fig. l showing 'a six cylinder motor or pump wherein the crank throws are 60 apart.

Fig. 4 is diagrammatic representation showing the rate of delivery from the cylinders of the same,

Fig. 5r is a. diagrammatic view similar to Figs. l. 'and l showing the cranks, of a six cylinder engine arranged in accordance with the present invention,

Fig. `6 is `a diagrammatic representation showing the rate of delivery from a pump of the type shown in Fig. 5,

Fig. 'l is a sectional view of a ten 'cylinder motor embodying the present invention wherein the pistons are radially slidable and wherein the pistons are arranged in two. banks arranged in two dilierentv planes,

Fig. 8 is a similar view wherein the pistons are all arranged in the same plane, and

Fie. 9 is a diagrammatic showing of the present invention, primarily operating as a pump and driven by an electric motor.

For the sake of clarity, it is assumed that except in Fig. 7., the cylinders are arranged in line and are driven by an orthodox form of crankshaft.

Referring to Figs. 1 and the pistons and corresponding crank throws are numbered i, 2 and .'i the angle between the crank throws benig 120, which is the phase angle between the successive pistons. The movement of the pistons being approximately simple harmonic, the rate of delivery from each cylinder can `be represented by the positive portion of a sine curve; thus the rates of delivery from, cylinders l, 2 and 3 are shown by curves I, II and II respectively in Fig. 2. The total rate of delivery is obtained by adding the above curves, and is therefore given by curve IV of Fig. 2. It will be noted that this last curve is a series of ripples, each of which spans 60 of crank angle, i. e. one sixth of a revolution. In this sense a three-cylinder pump has virtually siX cylinders.

Referring to Figs. 3 and 4 showing a six-cylinder pump of orthodox construction, the end view of the crank is shown in Fig. 3, the crank throws (I to 6) being 60 apart. Now pistons I, 3 and 5 can be considered as forming a threecylinder pump, and their total rate of delivery will therefore be given by curve IV of Fig. 2. Similarly

pistons

2, 4, land '6 form another threecylinder pump, and their 4delivery is represented by a similar curve, but dephased by 60. This is curve B of Fig. 4, which is seen to be coincident with curve A. The resultant rate of now is obtained by adding the two curves, and is shown .in curve C of Fig. 4. This is merely twice curve A (or B) and it is apparent therefore that the flow of a six-cylinder pump of the type described is no smoother than that of a three-cylinder pump. The same comparison holds between a pump with any odd number of cylinders and a pump with twice that number.

Referring now to Figs. and 6 which show a six-cylinder pump according to this invention, the crank throws are so arranged that the angle between successive throws is alternately 30 and 90, that is, one half and one-and-a-half times the average phase difference which is to the latter by thirty degrees instead of sixty as Fig. 4. The total rate of delivery is now given by curve C which is the sum of `curves A and B.

Curve C now has twelve (instead of six) ripples vfor each crank revolution, the amplitude of the ripples being very much smaller.

Thus a construction according to the invention gives a much smoother resultant output.

In Figures 3 and 5, the cylinders are arranged in two banks positioned in the same plane.

Another example of pump according to the invention is shown in Fig. 7 in which the banks are arranged in two different planes. This consists of a rotor A rotating on a shaft B, and carrying pistons the outer extremities of which bear against a track C eccentric to the rotor axis; the shaft B is provided with slots which are arranged to connect the cylinders to suction or delivery according to direction of motion of the pistons, in known manner.

The pistons are ten in number and arranged in two banks, the rst consisting of pistons I, 3,

I5, 1 and 9 all `spaced 72 apart from each other.

The two banks (which may be in different planes,

1 as shown) are oiset by 18 relatively to each other, that is to say the phase difference bejtween succeeding pistons is alternately one half and one-and-a-half times the average phase difference.

In Fig. 8 of the drawings -a pump or motor similar to that illustrated in Fig. 7 is shown with lthe pistons arranged in the common plane with the ends of the pistons bearing against the track C o1' surrounding eccentric shell whereby rota- 4 tion of the rotor A about the stationary shaft C causes radial reciprocation of the pistons to provide the Idesired pumping action. The showing in Fig. 8 is somewhat enlarged and it will be noted that each of the pistons, which are indicated by the same numerals as in Fig. 7, is reciprocal in a cylinder I5 provided at its inner end with a port I6 adapted to communicate successively with chambers I1 `and I8 formed by transversely grooving the shaft B. This shaft is provided with a pair of longitudinal passages I9 and 20 communicating with the respective chambers I1 and I8. It will be apparent that these passages will be inlet and outlet passages depending on the direction of rotation of the rotor A.

In Fig. 9 the pump as a whole is indicated by the numeral 22 and is provided with inlet and

outlet connections

23 and 24. Used as a pump, the rotor A is adapted to -be driven by `a shaft l25 connected to a motor 26. When the device is used as a motor, the driving motor 26 is of course omitted and the

connections

23 and 24 used for the admission and exhaust of pressure fluid to such motor.

When the invention is applied to hydraulic motors, the arrangement which gives smooth delivery when the machine is used as a pump will give smooth torque when the machine is used as a motor. When the expression driving means occurs in the claim, it will be understood that this driving means is the motor 2S of Fig. 9. Where the apparatus is employed as a motor, the driving means would be means for supplying pressure iiuid or an explosive charge to such motor.

It will, of course, be appreciated that the coupling together of the two pumps having an odd number of cylinders in such a way that the phase difference of the even number of cylinders thus provided fulfills the requirements of this invention and falls within the scope of this invention.

What I claim is:

A fluid pump or motor comprising a plurality of cylinders and pistons arranged in two sets, inlets and outlets for respective cylinders, and driving means for said pistons, each of said sets consisting of an uneven number of pistons, so arranged that the space phase difference between succeeding pistons is alternately one-half 'and one and one-half times the average phase difference, the latter being equal to 360 divided by the total number of pistons.

RUBEN HADEKEL.

References Cited in the ille of this patent UNITED STATES PATENTS Number Name Date 1,212,655 Magie et al Jan. 16, 1917 1,239,059 `Sundh Sept. 4, 191.1 2,074,068 Ferris Mar. 16, 1937 2,289,866 Benedek July 14, 1942 2,327,787 Heintz Aug. 24, 1948 2,431,175 Hofler Nov. 18, 1947 2,439,668 Mercer Apr. 13, 1948 FOREIGN PATENTS Number Country Date 168,488 Great Britain 1921 OTHER REFERENCES Standard Handbook for Electrical Engineers, by Archer E. Knowlton, Seventh Edition (1941), published by McGraw Hill Book Company, New York and London (pages 73, 74, and 850).