US2833217A - Fluid pump - Google Patents

Description

y 1958 I L. c. BULLINGTON 2,833,217

FLUID PUMP Filed Sept. 8, 1953 2 Sheets-Sheet 1 LEO C. BULLINGTON, INVEN TOR.

HUEBNER, BEEHLER,

WORREL 8 HERZIG.

ATTORNEYS.

FLUID PUMP Leo C. Bullington, Montebello, Calif. Application September 8, 1953, Serial No. 378,774 4 Claims. (Cl. 103-37 This invention relates to fluid pumps; and more particularly to fluid pumps wherein the output volume of the pump is automatically adjusted in accordance with the; output pressure against which the pump must force the fluid, so that as the output pressure increases, the volume decreases, thereby maintaining relatively constant load on the motive means driving the pump.

It is an object of this invention to provide an improved pump in which the output volume of the pump varies automatically and inversely with the output pressure against which the fluid must be forced by the pump.

It is a further object of this invention to provide a fluid pump having automatic means for continuously and variably adjusting the volumetric displacement of the pump inversely with the fluid pressure against which the pump must force the fluid.

In accordance with these and other objects which will become apparent hereinafter, a preferred embodiment of the instant invention will now be described with reference to the accompanying drawings wherein:

Fig. l is a longitudinal elevational section of the Fig. 2 is a cross-section taken on line 22 in Fig. 1;

Fig. '3 is a cross-section taken on line 3-3 in Fig. 1; and

Fig. 4 is a cross-section taken on line 4--4in Fig. 1.

Referring to the drawings, 11 designates. a housing having .a pair of cylindrical cavities. or cylinders 12 and 13 formed therein. A pair of shafts 14 and 16 are rotatably mounted in the housing 11. The shaft 14 is mounted by a pair of aligned bearings 17 and 18, and the shaft 16 is mounted by a pair of aligned bearings 19 and 21. ,In the'particular embodiment shown, the shafts 14 and 16 are aligned.

Each of the shafts .14 and 16 is disposed generally transverse to its respective cylinder 12, 13, and includes a crank portion aligned with the respective cylinder. The shaft 14 is provided with a crank 22 which rotates in the left portion of the housing 11, in the crank chamber 23 associated and communicating with the cylinder 12; and the shaft 16 includes a crank 24,-rotating in the nitedStatcs Patent "ice munication with either the cylinder 12 or 13, or the passageway 32.

Resilient linking means torsionally linking the shafts 14 and 16 is provided, and such means will now be de scribed.

The shaft 14 extends beyond the crank chamber 23, outside and past the bearing 18, and to the shaft is secured a housing 41, by means of bolts 42. The shaft 16 also projects beyond its crank chamber 26 and past its bearing 19 into the housing 41, and is journalled in the housing 41 by bearings 43 and 44. The shaft 16 is resiliently, torsionally linked to the shaft 14 by means of a torsion spring 46 encircling the shaft 16. One end of the spring 46 is anchored to the shaft 16 at 47, while the other end is anchored to the housing 41, and hence to the shaft 14, at the spring end 48.

The pump of the present invention may be driven from either endthat is, either the shaft 14 or the shaft 16 may be driven; but both shafts should not be driven simultaneously. If the shaft 14 is to be driven, it should be rotated in the direction shown by the arrow 49, while if the shaft 16 is to be driven, it should be rotated in the direction shown by the arrow 51. Assuming the shaft 14 to be driven in the direction shown by the arrow 49, it will be seen that torque is transmitted from the shaft 14 to the shaft 16 through the spring 46. By virtue of the resilient link between the two shafts, in the form of the spring 46, the phase displacement between the two shafts will be directly proportional to the torque transmitted from the shaft 14 to the shaft 16. The

torque transmitted will in turn be dependent upon the resistance torque encountered by the crank 24, and this in turn will vary with the fluid pressure against which the piston 28 must force the fluid out the outlet pipe 38.

The linking means between the shafts 14 and 16 also includes a dashpot means, including the housing 41, which is effective to dampen rapid change in phase relation between the two shafts 14 and 16. Description of this dashpot means will be deferred until the basic operation of the pump has been briefly explained,

below.

crank chamber 26 associated and communicating with the cylinder 13. Within the cylinders 12 and 13 reciprocate, respectively, pistons 27 and 28, which are connected to their respective cranks 22 and 24 by piston rods 29 and 31, respectively. v I

A passageway 'or fluid conduit means 32 connects jthe upper portion of the two cylinders 12 and 13. Inlet conduit means to the cylinders 12 and 13: is provided inthe form of a pair of pipes 33 and 34 feeding into the respective cylinders 12 and 13, and including inletcheck- I vcylinder 13, and vice versa.

up as the piston 29 is coming down.

With the pump at rest, the two cranks 22 and 24 are substantially aligned, that is, the pistons 27 and 28 are substantially in phase with each other. Under these conditions, when the shaft 14 is rotated, the two pistons 27 and 28 rise and fall together so that maximum fluid is drawn in with each stroke through the valves 36 and 37, and maximum fluid is forced out throughthe valve 39 with each up stroke.- If the output pressure into which the outlet pipe 38 feeds is very low so as to be negligible, then the back pressure on the pistons, in particular on the piston 28, is very low, and hence the resistance torque on the crank 24 and shaft 16 is low. Under these conditions there is very little torque transmitted through the spring 46, and the phase displacement between the two shafts 14 and 16 is small. Thus We have a condition of maximum volumetric displacement of fluid with each revolution of the pump, and against minimum pressure.

Let it now be assumed that the shafts 14 and 16 are moved 180 apart, so thatthe' piston 28 is going In other words, the pistons are exactly 180 out of phase. Under this circumstance there will be no fluid forced out through the outlet conduit 38, because all the fluid displaced by the piston 27 will be immediately accepted by the Thus we see that the volume output of the pump may be varied between a maximum, when theshafts 14 and 16 are in phase, down to zero, when the shafts 14 and 16 are l out ifdesired, and this may be placed anywherefin comof phase. In between, say at crank displacement,

3 the output volume will be'between maximum and zero.

It has been shown that with negligible output presu e at e qut t-ce duitfi the tw ha t 1 m 16 rotate substantially in phase, since the torque transmitted through the, spring 46 is negligible. Now let it be supposed that the output pressure increases. In this event the back pressure encountered by the piston 28 increases, and a resistance torque will be .aPPlied against theshaft 16 through the crank 24. This torque forces the spring ,46 to wind up around the shaft 16 and creates a phase,displacement-between the shaft 14 and the shaft 16, the latter now lagging in phase behindthe shaft .14. Under .this circumstance the volume of fluid ,put out through the outlet 38 decreases, since a portion of the fluid put out from the cylinder 12 is taken up in the cylinder 13 and vice versa, and only the remainder goes out through. the outlet 38. This decreased volume output permitsof a greater pressure to be delivered by the pump for a given energy input of the driving means, since pressure times volumetric output is proportional to the power input. Therefore, it will be seen that if constant power input is applied, the output pressure will go up as the volume output goes down.

Thus is will be seen that as the output pressure into which the pump must feed the fluid goes up, the volume or flow rate correspondingly decreases, thus keeping constant power load at all times on the prime mover driving the shaft 14. The prime mover is thus able at all times to deliver constant horse power to the pump, with the pump automatically adjusting itself to absorb all of the horse power put out by the prime mover, either in terms ofhigh volume .and low pressure, or low volume and high pressure, or any intermediate range.

When there is a relative phase displacement between the two shafts 14 and 16, as for example, when the shafts are 90 displaced, and the pump is pumping medium volume at mediumpressure, the resistance torque applied against the crank 24 through the piston 28 varies considerably over one revolution of the shaft 16. Such variation would cause a constant shifting in phase between the shaft 16 and the shaft 14 throughout .one cycle or revolution, were it not for the dashpot means mentioned hereinbefore and contained within. the housing .41.

Thismeans is shown in Figs. 1 and 4, wherein the housing 41 is shown as having two cylindrical cavities or dashpot cylinders 52 and 53. In'these cylinders reciprocate, respectively, pistons 54 and 56 connected, respectively, by rods 57 and 58 to acrank 59 formed on the end of the shaft .16 between .the bearings .44 and 43. The two cylinders 52 and 53 are connected at their upper regions orheads by a passageway 61, which communicates with the cylinder 52 through a restricted orifice 62 and with the cylinder 53through arestricted orifice 63. The passageway 61 and thecylinders 2 and 53, above the heads of their respective pistons, are filled with a fluid, preferably a liquid, such as hydraulic oil. This oilserves as a .damping means for limiting the speed of phase displacement between the shaft 14, secured to the housing 41, and the shaft.16, linked to the pistons 54 and 56, respectively,

It will be seen thatrelative phase displacementbetween the shafts 14 and 16 causes piston 54to advance or go up in its cylinder 52, while piston '66 is retract-- and 16, in spite of the widely varying torque resistance encountered by the crank 24 on the shaft 16. As a result, for any given condition of operatiouthat is, for any given output pressure at the outlet pipe 38, the phase displacement between the shafts 14 and 16 will settle upon a predetermined angular displacement, which is a function of the average torque transmitted from the shaft 14 to the shaft 16, rather than the rapidly fluctuating instantaneous torque which occurs throughout any given revolution.

In practice, it is preferred to space the orifices 62 and/or 63 at points somewhat short of the maximum excursions of their respective pistons 54'and 56, as shown in Figs. 1 and 4. In this way, positive stops are provided for the pistons 54 and 56, since when the pistons have passed the orifices 62 and 63, respectively, no further fluid canescape, and the pistons are brought to an absolute halt. This provision limits the relative phase displacement between the shafts ,14 and 16, which instead of being able to shift from zero to 180 relative phase displacement, will now be limited to a range of from 10 to 170, for example.

The principles of the instant invention also have special application in the field of hydraulic transmissions. For such a use, one of the shafts, for example the shaft 14, serves ;.as a-drive shaft coming from a prime mover. Theshaft 16 is cut off at the bearing 21, and an output shaft is secured to the housing 11 which is now allowed to rotate freely. The output shaft is aligned with the shaft 14, .,By providing special valving means at the outlet in place of the valve 39, a transmission is readily provided which automatically adapts its coupling ratio totheiresistance torque encountered by the output shaft, so that maximum horse power from the prime mover is employed'at all times.

While theinstant invention has been shown and described herein ,in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be .made therefrom within the scope of the'invention, which is therefore not to be limited to the details disclosed herein but is to be accorded the full scope. of the claims.

What isgclaimed is:

l. Mechanism employing fluid and comprising: a housing having a pair of cylinders therein; a pair of shafts rotatably mounted in said housing, each shaft having a crank therein; a pair of pistons reciprocable, respectively, insaid cylinders; a pair of piston rods connecting said pistons, respectively, to the respective cranks; resilient linking means torsionally linking said shafts so ,;that one shaft may drive the other; said linking means -including dashpot means effective to dampen rapid phase displacements between said shafts; said dash pot means comprising a housing secured to one 'ofsaid shafts and having a dashpot cylinder therein, a dashpot crank formed on the other of said shafts, a dashpot-piston -reciproeable in said dashpot cylinder, a dashpo tpiston -rodconnected between said dashpot piston and dashpot crank, and restricted conduit means communicating with said dashpot cylinder; fluid conduit 7 means connecting said cylinders; inlet conduit means to said cylinders including check valve-means; and outlet conduit means from said cylinders including check valve means. i

2. Mechanism employing fluid and comprising: a housing having a pair of cylinders therein; a pair of shafts rotatably mounted in said housing, each shaft having a crank therein; a pair of pistons reciprocable, respectively, in said cylinders; a pair of piston rods connecting said pistons, respectively, to the respective cranks; resilient linking means torsionally linking said shafts so that one may drive. theother; said linking means including dashpot means effective to dampen rapid phase displacements between said shafts; said dashpot means comprising a dashpct housing secured to one of said shafts and having a pair of cylinders therein, dashpot crank means disposed in said dashpot housing and secured to the other of said shafts, a pair of dashpot pistons reciprocable, respectively, in said dashpot cylinders and connected to said dashpot crank means, conduit means communicating between said dashpot cylinders and liquid filling said conduit means and dashpot cylinders in front of said dashpot pistons; fluid conduit means connecting said cylinders; inlet conduit means to said cylinders including check valve means; and outlet conduit means from said cylinders including check valve means.

3. Mechanism employing fluid and comprising: a housing having a pair of cylinders therein; a pair of shafts rotatably mounted in said housing; each shaft having a crank therein; a pair of pistons reciprocable, respectively, in said cylinders; a pair of piston rods connecting said pistons, respectively, to the respective cranks; resilient linking means torsionally linking said shafts so that one shaft may drive the other; said linking means including dashpot means eflective to dampen rapid phase displacements between said shafts; said dashpot means comprising a dashpot housing secured to one of said shafts and having a pair of cylinders therein, dashpot crank means disposed in said dashpot housing and secured to the other of said shafts, a pair of dashpot pistons reciprocable, respectively, in said dashpot cylinders and connected to said dashpot crank means, conduit means communicating with the respective dashpot cylinders at points short of the maximum excursions of said dashpot pistons from 6 said other shaft, and liquid filling said conduit means and said dashpot cylinders in front of said dashpot pistons; fluid conduit means connecting said cylinders; inlet conduit means to said cylinders including check valve means; and outlet conduit means from said cylinders including check valve means.

4. Mechanism employing fluid and comprising a housing having a pair of cylinders therein, a pair of aligned shafts rotatably mounted in said housing, each shaft having a crank therein, a pair of pistons reciprocable, respectively, in said cylinders, a pair of piston rods connecting said pistons, respectively, to the respective cranks, a torsion spring disposed coaxi-ally of said shafts, means connecting one end of said spring to one of said shafts, means connecting the other end of said spring to the other of said shafts, fluid conduit means connecting said cylinders, inlet conduit means to said cylinders including check valve means, and outlet conduit means from said cylinders including check valve means.

References Cited in the file of this patent UNITED STATES PATENTS 1,575,519 A-msler Mar. 2, 1926 2,172,103 Kotaki Sept. 5, 1939 2,327,787 Heintz Aug. 24, 1943 FOREIGN PATENTS 269,747 Great Britain Apr. 28, 1927 517,236 Germany Feb. 2, 1931 620,430 Great Britain Mar. 24, 1-949

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