US2453538A

US2453538A - Constant pressure pump

Info

Publication number: US2453538A
Application number: US778010A
Authority: US
Inventors: William T Rauch
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1947-10-04
Filing date: 1947-10-04
Publication date: 1948-11-09
Anticipated expiration: 1965-11-09

Description

:inventori His Attorney.

Nov. 9, 1948. w. 1'. RAUCH CONSTANT PRESSURE PhillA .mea oct; 4, 1941 atented cv." 9, i f

Wiiliam il?. Rauch, Vcorheeaville, N. Y., assigner to General Eiectriic cinpany, a corporationot Application @catcher d, i947, @arial No. '17@,0310

il Siae. (El. lus-mit) previous attempts have taken the form of gov` erning apparatus for theJ stroking ring. However, one of the inherent diiculties with this` type of pump is that the reaction force ofthe uid being pumped tends to restore the stroking ringr toward neutral, or low stroke, position. AcA cordingly, it isnecessary. to hold the stroking means lpositively against this reaction force as well as to control its movement to govern the pressure supplied by the pump. While some attempts have been made to control the discharge pressure of the pump by varying the position of thev stroking ring, these efforts have produced governing apparatus with undesirable regulation since the discharge pressure decreases with an increased load on the system. With this type of apparatus, for each position of the stroking Lring there is a predetermined pressure and flow condition in thed system supplied by the pump.

It is an object of my invention to provide apparatus for automatically governing the uid discharge pressure of' a radial piston type pump independently of the flow requirements of the fluid system being supplied by the pump and the position of the stroking means. v

A further object of lmy invention is to provide pressure governing apparatus for a radialpistcn pump which will maintain constant the pressure differential between the inlet and discharge lines of the pump.

A still further object of my invention is to provide governing apparatus to maintain stable and reliable operation of a radial piston pump at a constant differential between some low pressure. such as the inlet line pressure and the discharge line pressure. f'

Another object oi my invention is to provide `simple and inexpensive governing apparatus for a radial piston pump.

Further objects and advantages of my invenf tion will become apparent and my invention will be better understood from the following description referring to the accompanyingdrawing, and the features of novelty which characterize my in'- vention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

2 in the drawings, Fig. 1 is a sectional view oi' a radial piston pump embodying pressure governing apparatus in ac-l cordance with my invention.

Fig. 2 is a cross-sectional view looking in the J direction of the arrows 2--2 in Fig. 1 with a portion of the pump block cut away to`show part of l the pressure governing apparatus. i

Referring to the drawing I have shown inFlg. 1 a radial piston pump having a back flange I with a pintle 2 located in an axial bore 3 in the center of the flange. Pintle 2 is so arranged that it separates inlet and discharge means, such as bores and 5, respectively, in the flange which radially intersect bore 3. To pumpfluid from the inlet side of the pintle to the discharge side I provide a rotatable cylinder 6 including bearing` surface 1 mounted on extension 8 of the flange` I surrounding pintle 2. Piston means,`such as balls 9, are reciprocably mounted in a plurality` of radial bores III which serve as cylinders in block 6. Back ange I is providedv with an axial bore II parallel to bore 3 for. supplying makeup uid from the sump (n/ot shown) to the fluidv system in which the pump is connected. An annular groove I25a1so located in the back ange connects with bore II. Pump block 6 is provided with a.plurality of radial veins I3 adjacent the annular groove I2 and these veins serve as a centrifugal pump to increase the pressure of the,

fiuid entering the pump through bore II and annular groove I2. Veins I3 pump the fluidrinto annular groove I4 which is in communication with inlet bore 4 through passage I5.

Driving means` for the pump elements, blockV B and balls 9, is provided through shaft I6 adapted to be rotated by an external-power source (not shown). Shaft I6 rotates an Oldham coupling I'I through key I8 in a keyway in shaft I6. Oldham vcoupling I1 comprises a driving ange I 9, an intermediate flange 20, and apair of shoulders 2I integrally formed on the cylinder block I0. As shown ring 22 surrounds the cylinder block 8 to maintain balls il in the cylinder bores p I0 and provide a raceway for the balls. A housing member 23 having an ovate recess 24 adapted to surround ring 22 mates with flange I to enclose the` radial pump and stroking means.` A I uid seal 25 to prevent leakage of fluid under ring 22 is press 4e is provided between the Oldham coupling 1 and the housing 23. "Y

As indicated above the stroking ring 22 may be moved radially with respect to the axis of the'cylinder block 6, but housing 23 is provided with a pair of inserts 26 to limit this motion to movement parallel to the major axis of pintle 2. Ovate recess 24 is so located that movement oi' .and 38 adjacent recess 24 in housing 23. As

shown in the drawing, end 3| of piston 28 is adapted to move inwardly against stroking ring 22 to hold pump block 6 in full stroke position.

However, end 3'2 of piston 21 is also adapted to move inwardly against the stroking ring to actuv` ate the block toward neutral, or low stroke, position.

In order to move the stroking ring toward full stroke position initially, biasing means are provided to urge piston 28 inwardly. As shown, spring means, such as coil spring 33, is located between threaded plugv 34 and en-d 28' of piston 28 to urge the piston inwardly. l In addition to spring 33, I provide fluid pressure means to assist the biasing force of the spring. Fluidpressure in discharge means is introduced to cylinder 3'8 through bore in casing I and passage 36 in housing 23, In this way piston' 28 and stroking ring 22 are maintained in full stroke position against the reaction` force developedby piston balls 9 acting against stroking ring 22. Thus, ring `22 is held in full stroke position against the reaction force which tends to restore the ring to neutral position when the pistons are pumping fluid under pressure.

To overcome the biasing force applied to ring 22 through piston 28, counterbiasing means are fluid pressure to operate against end 41. In this manner the fluid pressure in discharge means 5 actuates valve 42 against' the Valve biasing means and the inlet fluid pressure and opens cylinder 29y to the discharge fluid 4pressure through port 39 and passage 38. The land of valve 42 adjacent end 41 is provided to insure proper alignment of .valve 42 with respect to port l39.

Operation of my pressure governing apparatus is as follows: Before the pump is started coil spring 33 biases piston 28 to thereby position stroking ring 22 in full stroke position relative to cylinder block 6. For clockwise rotation of the,

cylinder block (as shown in Fig. 2) ring 22 is held in a raised position for full stroke operation of the pump. When the cylinder block 6 is rotated by the external power source through shaft I6 and Oldham coupling I1, the ball pistons 9 are forced outwardly by centrifugal force during rotation of the cylinder block E through one half revolution about pintle 2 (left-hand side of 2) and are fully extended in the-top-most position in Fig. 2.- As the block is rotated through the right-hand portion of the revolution, the piston balls are forced inwardly by stroking ring 22 and Acause the fluid entrapped between balls 9 and cylinders 8 to be forced into the right-hand portion of pintle 2 and thus into discharge means 5. The fluid pres- Asure developed in discharge means 5 is applied passage 38. It will be noted that piston means 21 and 28 are arranged to hydraulically lock the stroking ring 22 in any desired position to govern 4o the work stroke of the pump in accordance with provided to urge end 32 of piston 21 against the ring. This counterbiasing means is selectively supplied by the uid pressure in either inlet means 4 or discharge means 5. To control the selection of the fluid pressure to be introduced into cylinder 29 I have provided pressure actuated valve means located in bore 31 in flange I. Passage 38 provides fluid conduit means between cylinder 29 and valve port 39 in bore 31.A Passages 48 and 4i respectively communicate with fluid inlet means 4 and fluid discharge means 5 and respect to Fig. 2) to maintain communication between cylinder 29 and inlet means 4 through passage 48 and bore 31. In addition to the valve biasing, means the fluid inlet pressure operates against jvalve 42 and seat 44 to assist spring 43 in maintaining the valve in this position. Valve 42 is so arranged that when the fluid pressure in discharge means 5 increases, the pressure operates against shoulder 46 and end 41 of the valve 42 to move the valve against rthe force ofv coil spring 43 and the inlet fluid pressure acting on valve 42. A passage 48 in valve 4 2 is provided to admit 'fluid into chamber 58 formed by sealing plug 6I and end 41 of the valve 42 to'permt the the differential pressure across inlet means 4 and discharge means 5;'independently of the fluid reaction force developed by ball pistons 9 acting against ring 22. So long astheilow in the system being supplied by the pump is sufliciently high the stroking ring will be maintained in full stroke position. However, if the flow is decreased with the pump operating at the same speed, the pressure in discharge means 5 will increase.

passage 4i and will operate against shoulder 46 and end 41 ofvalve 42 to overcome the force ofv coil spring 43 and the inlet pressure acting on valve 42 to thereby move valve 42 towardv the left until passage 38 and cylinder 29 are opened to the higher fluid pressure in discharge means 5. Since piston 21 is larger than piston 28 the counterbiasing force on piston 21 will overcome the biasing force of piston 28 and move the stroking ring 22 toward neutral or low` stroke position.

' However, piston 21 .will only be moved far enough to reduce the stroke of the pump to such a position that the pressure differential across inlet means 4 and discharge means 5 will be restored to a pre-set pressure differential across the pump. This pressure differential may be determined by the adjustment of threaded plug 45 which ini-` l differential pressure decreases.

This increased pressure is applied to valve 42 through Y VBy the arrangement of piston valve 42 acting against coilspring 43 and the low pressure for i mfoving stroking ring 22 by piston 21, the move'- ment of the stroking ring is made pressure sensi-4v tive and independent of the ilow condition in the system supplied by the pump except insofar as the flow `varies the pressure in the discharge means. In this way, a lloating type of 'control is obtained wherein the 'same differential pressure may be maintainedliorjany dow demanden the system, sincethere is no fixed relationship between' stroking ring position and the discharge pressure oi' the pump. 'I'his reduces undesirable regulation andmai'ntains the pressure constant` irrespective of the ilow demand on the pump. It will thus be apparent thatthe same pressure may be maintained at any position of the stroking. ring since the stroking ring position will vary only with a change in differential pressure acrossthe pump. By making piston 21 larger than. piston 28, the force on ring 22 due to piston '20 is readily overcome by the counterbiasing force on piston 21. Since the pressure responsive element is remote from piston 21, the piston may move through its complete range of travel for a small displacement of the valve against the spring and thereby l the ring in response to iiuid pressure admittedV to the opposite ends of the cylinder.

It will also be apparent that the pressure maintained by the pump may be the pressure difierential between the pressure in 'the discharge pump, and means lfor selectively subjecting the other oi'said pistons to either the inlet pressure or said discharge pressure or said pump. said means including a valve operable in response to the dif ference in' said pump inlet and discharge pressures. Y

3. In combination, a casing, a radial piston pump rotatablev in said casing.- a stroking ring l `for varying the stroke oi said pump, iiuid inlet lil means and fluid outlet means for said pump, biasing means for maintaining said ring in full stroke position initially, means for reducing said stroke of said pump to maintain the iiuid pressure differential between said outlet means and said inlet means constant, said means comprising piston means adapted-to move said stroking ring, said piston means being reciprocable in a chamber in 2 said casing adjacent said stroking ring and movable in response to fluid pressure in said chamber, pressure actuated valve means for selectively Iconnecting said chamber with either said outlet means or said inlet means, said valve means including biasing means for maintaining said chamber in communication with said inlet means until the force due to said fluid pressure in said y outlet means exceeds the force of said biasing means and any low pressure connected to tlie low pressure side of the valve means. such as atmospheric pressure, since the movement of the stroking ring is substantially due to the pressure differential appearing across the piston valve 42.

While I have illustrated and described a particular embodiment of my invention, modifi ations thereof will occur to those skilled in the art. I desire it to be understood, therefore, that my invention is not to be limited to the particular arrangement disclosed, and I intend` in the appended claims to' cover all modiications which do Y not depart from the spirit and scope of `my invention.

y What I claim as Letters Patent of the United States is:

" l. In combination, a casing, a radial piston pump'block rotatable in said casing, a stroking ring for varying the work stroke of said pump, fluid inlet means and iiuid discharge means for said pump, a pair of hydraulic pistons connected to position said ring, means for subjecting one of said pistons to the pump discharge pressure, means including a valve member for selectively subjecting the other of said hydraulic pistons to either the pump inlet or said discharge pressure Vand means for positioning said valve member in accordance with the diierence in said pump inlete pistons in opposed relation adapted to move said stroking means, conduit means for subjecting one of said pistons to the discharge pressure oi' said new and desire to secure by.

means, said iluid pressure force adapted to actuate said valve means and connect said chamber with said outlet means whereby said piston means may move said stroking ring toward low stroke position to maintain said pressure differential between said outlet means and said inlet means constant.

4. In combination, a pump casing provided with iiuid conduit means for admitting and discharging fluid, a radial piston pump rotatable in said casing, a stroking ring for varying the stroke of said pump between full stroke and low stroke positions, biasing means for maintaining said pump ring initially in -said full stroke position. said biasing means comprising a piston adapted to reciprocate in a cylinder in said casing and to move said ring in response to fluid pressure in said cylinder, and uid conduit means interconnecting said cylinder and the fluid discharge conduit of said pump whereby the pressure 4in said discharge -conduit biases said ring to full stroke position, and counterbiasing means for moving said ring toward said low stroke position, said counterbiasing means comprising second piston means adapted to reciprocate in another cylinder in said casing and to move said ring in response to iiuid pressure in said other cylinder, means including a valve for selectively interconnecting said cylinder with either said iiuid discharge conduit or the fluid inlet conduit of said pump, valve biasing means for positioning said valve to connectsaid other cylinder and said inlet conduit initially, and means for then operating said valve -in opposition to said biasing means in response to the pressure in said fluid outlet conduit whereby said second piston moves said `stroking ring toward low stroke position t-o holdthe pressure differential 'between `said outlet conduit means y and said inlet conduit means constant.

said pump and said cylinder means to admit iluid under pressure from said discharge means to bias Asaid piston means, means for counterbiasing said piston means to neutral stroke position, said counteubiasing means comprising pressure actuated valve means for connecting said cylinder means to said pump discharge means, valve blasing means to maintain said valve means closed to said discharge means until the force due to said pressure in said discharge means exceeds the force of said valve biasing means, and means for moving said valve means against said valve biasing means whereby said counterbiasing means v operates said piston means against said biasing means to move said stroking means toward neutral position and maintain said discharge pressure f into said full stroke position initially, said piston means operated in response to fluid pressure in the discharge means of said pump, second piston means for counterbiaslng said stroking ring toward low stroke position, pressure operated valve means for selectively operating said second piston means in response to either said discharge pressure or the .pressure in the inlet means of said pump, and biasing means for said valve means tomaintainsaid piston responsive to. said inlet pressure until the force due to said dischargel pressure exceeds the force of said valve biasing means, said valve being operated by said discharge pressure to subject said second piston means to said discharge pressure thereby moving said stroking ring towa-rd low stroke position and reducing said workstroke whereby said discharge pressure is reduced to maintain constant the presmounted within said casing and connected to said conduit means. a movable stroking ring for varying the work stroke of said pump between,v full and neutral stroke positions, a floating type of control means for moving said ring whereby said ring may be moved in response to changes in the differential pressure between said discharge means and the inlet means to maintain said differential pressure constant for any position of said ring'. said means comprising a pair of pistons adapted to move said ring between said full and neutral stroke positions, said pistons being reciprocableV in rst and second cylinders in said casing to cause said ring movement, fluid connecting means between said first cylinder and said discharge means whereby one of said pistons is biased by said discharge pressure to hold said ring in said full stroke position initially, valve means for selectively connecting said second cylinder with either said inlet means or said discharge means, and valve biasing means for maintaining said second cylinder open to said inlet means until said differential pressure increased and the force due to the pressure in said discharge means exceeds the force of said biasing means, said valve means then ibeing operated by said "differential pressure to -connect'sraidsecond cylinder to said discharge means whereby the other of said pistons may be counterbiased by said discharge pressure to move said stroking ring toward said neutral position and thereby reduce said discharge pressure ,to maintain said diil'erential pressure constant irrespective' of the ilow prf sure differential between said inlet side and said I outlet side of said pump.

7. Pressure governing'apparatus for a radial piston pump having a stroking ring for varying said stroke, means for biasing said stroking ring into full stroke position initially comprising piston means reciprocable in cylinder means and iluid conduit meansbetween the discharge means oi said pump and said cylinder means for moving said piston means and said stroking ring to full stroke position in response to the pressure in said discharge means and means for countelbiasing1- '5.55 prising second -piston means reciprocable in said cylinder means, control valve means for selec'- pressure m 'said inlet means and holding said said stroking ring Vtoward low stroke position comtively connecting said second cylinder means to duced by said pump.

9. In a radial ball piston pump having a stroking ring for varying the work stroke of said pump. pressure actuated means for moving said stroking ring to full stroke position initially, said means comprising a cylinder, a piston reciprocable in said cylinder and adapted to move said stroking ring, and fluid conduit means between said cylinder and the discharge means oi said pump whereby the discharge pressure is applied to said piston. and differential pressure means for moving said ring toward low stroke position to maintain the diil'erential pressure across said pumpl constant, said means comprising a second cylinder having a piston reciprocable therein, said piston adapted to move said ring toward said low stroke position against the force of said pressure actuated means holding said ring in full stroke position. pressure responsive valve means for seleceither the inlet means cf sind pump or said dis- 'V charge means, valve biasing means for maintaining said second cylinder means in communication with said inlet line initially, and means for moving said valve against said valve fbiasing means iniresponse to an increasev in differential. pressure between said discharge means and said? tively connecting said second cylinder to either the inlet means of said pump or said discharge means, spring biasing means for positioning said valve means to subject said second cylinder to the 'adapted to move against said spring biasing inlet means, said means moving said valve, to

connect said second cylinder means to said clischarge means whereby said second piston means and said stroking ring may be moved toward-flowv l stroke position in-response to said increase in said differential pressure to maintain constant said dinerential pressure.

8. A'constant pressure pump comprising a casing having conduit means for admitting and discharging fluid, a radial pistonV pump rotatably means in response to said increase in differential pressure to connect said second cylinder to said discharge means 1 whereby said second piston moves said ring to reduce said work stroke and Vsaid discharge pressure to maintain said diieren- I ltial pressure constant.

10. Pressure governing apparatus for a radial 'piston pump including a stroking ring :for varying the stroke of the pistons of said pump from full to low stroke positions, fluid inlet means and fluid discharge means for said pump, said ap- 'paratus comprising a pair of cylinder means having pistons movable in said cylinders and adapted escasas to move said ring between said full and low stroke positions, pressure operable valve means adapted to selectively connect one of said cylinders to either'said inlet means or said discharge means in response to the differential pressure across said valve. conduit means between said valve and said inlet and discharge means, spring biasing means for holding said valve in position to maintain said one cylinder open to said inlet means until'the force due to said diierential pressure exceeds the force of said spring biasing means. and fluid conduit means between the other of said cylinders and said discharge means so that said other cylinder is opened to the iiuid pressure in said discharge means whereby said ring is biased to full stroke position initially and moved in response to an increase in diilerential pressure between said inlet means and said discharge means to a lower stroke position to maintain said difierential pressure lconstant.

11. Pressure governing apparatus for a radial piston pump. said pump having stroking means for varying the work stroke of said pump between full stroke and low strokeposition, said apparatus comprising pressure responsive means for biasing said stroking means toZ said full stroke position initially, said means including cylinder means. piston means movable in said cylinder means and adapted to move said stroking means, and conduit means between said cylinder means and the" discharge means of said pump whereby the iiuid pressure in said discharge means.A actuatea said piston means and stroking means to said full stroke position, and differential pressurere- 1g sponsive means for counterbiaslng said stroking means toward said low stroke position when the differential pressure across said pump exceeds a pre-set condition, said means comprising second cylinder means, second'piston means movable in said second cylinder means for moving said stroking means against saidl pressure responsive means, a valve for selectively connecting said second cylinder means to either the inlet means for said pump or said discharge means, adjusts ble valve biasing means for assisting the pressure in said inlet means in' maintaining said valve inl position to-eonnect said second cylinder means to said inlet means initiallyl and adjusting means for pre-setting said valve biasing means. said valve being adaptedrto operate in response to an increase of pressure in said discharge means against said valve biasing means and said inlet means pressure whereby an, increase in said diriierential pressure operatessaid valve to subject i said second piston to said discharge pressure and move said stroking means toward said low stroke position.

' i wmssu '1 1 nAUcH.

nnrsnnncns crrnn The' following references areot record in the ille of this patent:

Ferris L- July 1o. 1934