US2340196A - Rotary hydraulic pump and pressure control valving therefor - Google Patents

Description

Jan-`25, 1944. G. M. MAGRUM ET AL l 2,340,196

ROTARY HYDRAULIC PUMP AND PRESSURE CONTROL VALUING THEREFOB w n l A l d Znz/E'rzzr" E 0o @germs-e ff. Maeva, gl Mge? @ws/MAM, de.

Jan. 25, 1944. Q M MAGRUM ET AL l 2,340,196

ROTARY HYDRAULIC PUMP AND PRESSURE CONTROL VALVING THEREFOR Fiied June 16, 1941 2 Sheets-.Sheet 2 .ZES-

lPatented Jan. 25, 1944 ROTARY HYDRAULIC PUMP AND PRESSUR CGNTROL VALVING THEREFOR Gervase M. Magrum and Harry L. Chisholm, Jr., Buialo, N. Y., assignors, by mesne assignments, to Houdaille-Hershey Corporation, Detroit, Mich., a corporation of Michigan Application .rune 1e, 1941, serial No; 398,246

13 claims.. (ci. 10s-42) This invention relates to rotary hydraulic pumps and particularly to valving assembly forming part' of the pump structure for controlling the pump pressure.

The important' object of the invention is to provide compact valvlng assembly subjected to the pressure of the fluid pumped by the pump and functioning for relieving the pressure should the pump pressure gradually rise above normal predetermined pressure, and to provide blow-off for quick return to normal of the pressure should the pressure suddenly rise abnormally, the pump being'thus protected against overloading automatically and holding the pump pressure within its predetermined limits.

compressing packing around the shaft to pre-v vent leakage.v

The pump cylinder forming elements are rings and plates clamped together between the head I2 and the block I3 by a clamping ring 2 having threaded engagement in the open end ol the housing .wall I 0 and abutting the ange 22 lon I the head I2. As shown there are two rings 23 Another important feature of the invention is Figure 3 is an elevation of the left end of the' pump structure.

The pump structure shown is of the welllmown type as, for` example, that shown in the pending application of Sherwood C. Bliss, Serial No. 282,447, led July 1, 1939, issued into Patent No. 2,271,730, dated February'3, 1942.

Briefly describing the pump, its housing comprises the cylindrical wall Ill having the inner end wall or head II integral therewith, the outer end of the housing receiving the outer 'end wall or head I2. Fitting into the wall 'III and seating against the head II is the cylindrical block I3 the various elements which form the pump cylinders. A drive shaft I4 extends into the housing and. is journaled in ball'bearings I5 and 'I3 supported respectively by the block I3 and the head I2, the shaft .extending outwardly from the head II for mounting, or connection with, a

driving source (not shown) such as an electric motor. A fitting I'I receives .the shaft and is se cured, as by bolts I8, to the head II, and may serve as a bracket for supporting the pump struc= ture. The tting I1 engages a Washer I9 for and 24 respectively, an inner plate 25, an intermediate plate 26, and an outer plate 21, the outer diameters of the rings and plates being such that they will iit snugly in the cylindrical bore of the wall I0. The rings and plates denne annular cylinder. spaces 28 and 29 into whichd'lheA rotor members 30 and 3| respectively extend to be rotated by the shaft I4 to which they are secured as by keys 32.

vReferring to Figure 2, the rotor elements 30 1 and 3l are of generally elliptical shape so as to y between which and the outer head I2 are clamped dene with the cylinder lspace walls crescent shaped working chambers. The two .rotors are displaced ninety degrees from the shaft I4 so that the opposite working chambers 33 and 34 between the rotor 30 and the ring 23 will be displaced respectively ninety degrees from the Working chambers 35 and 36 between the rotor 3| and the ring 24.

The. block I3`is cored out to provide a suction or intake space S and a discharge space D, the suction space S communicating with the inlet 3l! on the wall I!) connected by suitable piping with a source of uld such as oil, and the discharge space or chamber D communicating with the outlet 38 lon the wall I0 connectable by suitable piping with hydraulic devices for receiving the huid under 'pressure from the pump.

For the cylinder spaces 28 and 29 in whichthe rotors. operate, i'luid inlet and uid outlet ports are provided. As vshown on vFigure 2, each cylinder space has diametrically opposite inlet ports 39 and 39' and diametrically opposite discharge ports 40 and 40. As shown on Figure 1, the rings 23 and 24 have transverse bores 4I therethrough which align withthe transverse bores 42 in the plates 25, 26 and 27 to form an outlet passageway which at its inner end communicates with the discharge space D connected with the outlet 38. The ports 40 extend through thev rings 23 and 2 4 to connect the pump chambers with the discharge passageway through the rings and plates. At a diametrically opposite point, the rings and plates are bored to form another passageway therethrough connecting with the discharge space D andconnected by the ports 40' with the pump chambers.A On Figure 2 the two ysthroughi-,heringendpiete assemblies are dicated by. d and d'.

The rings and plates are alsobored to provide `diametrically opposite inlet passageways s and s communicating with the suction or inlet space S and connected by the ports 39 and 39' with the pump chambers- The . rings 23 and 24 are each provided with diametrically opposite blades 43 and 43' for cooperating with the rotors surrounded by the respectiveV rings, the blades operating in radially extending slots u, the blades 43 being located a collar 46 on the stem and the'top of the plug 46,

the springs tending to hold the blades with its edge in engagement with the respective rotors. When'the pump is being driven the iluid will be drawn into the space S from a source of supplysuch as a reservoir, the iluid being drawn by the rotors through the inlet passageways s and s' -an`d thrpughthe ports 38 and 39' into the working chambers 33, 34 and 35, 36 and the blades will -intercept the fluid and direct it from the working chambers into the outlet passageways d and d' and into the discharge space D for outflow from the outlet 38 of the pump.

Describing now the valving structure for controlling the pump pressure, the valving assembly is located within the extension 49 from the pump .head I2. 'I'ne extension has the outer bore 56,'

and the inner bore 5I of larger diameter forming a chamber whose inner end ls closed by a plate 52 engaging between the ball bearing I6 and the shoulder 53 on the extension 43. The chamber 5I is connected with the bore 56 by na passageway 54 which is surrounded by an annular Valve seat 55. A distance outwardly from the valve seat 55 a guide member or plug 56 is seated in the bore 56 and is rigidly held in thebore as by press fit therein, orj other means. outwardly oi the plug 56, a plunger member 51 is. axially shiftable in the 'bore 56 and has a stem 56 extending through The plunger. 51 is held against rotary movement in the bore 56 as by means of a stop pin 62' Passageways 1l and 1I' through the head I2 connect this space 6I with the outlet ends of the ldischarge passageways d and d' of the pump so that the space 6I always contains fluid under pump pressure. e

When the plunger 51 is in its normal position with the valve end 66 engaging against the seat 55, the plunger body is separated from the guide plug 56 by an annular space 12 which is in communication through ports 13 with the bore in the stem 58 inwardly of the abutment nut 69. The plunger body lhas the restricted oriiice 14 connecting the -space 12 with the space 15 be- 43 to communicate with the chamber 5I. The

space 5I has an outlet passageway 18 therefrom through the head I2 to the exterior of the pump,

and this passageway may be connected with the supply source or reservoir for the pump.

In order to adjust the tension of the spring 16 against the check valve 68, provision is made for rotation of the abutment nut 69 from the exterior of the pump. .As shown, an vadjusting pin 13 extends-through a gland 86 on the cap 64 the spring 16 against the valve 68.

extending from the plug 56 into a recess 63`in the I plunger. The outer end-of thel bore 56 is closed by a detachable 'cap 64 having threaded engagement. with the extensionlae d between/this cap i and the plunger is a' spring" 5 which; tendait) hold the plunger in position i'or seatingngageyment of thevalve end A66 with the valve seat-55. The plunger andits stemehas the bore 66 therethrough` andthe stem', a distance outwardly from the valve end 66, has the annular internal ilange 61 forming a seat for a relief valve which may 4be in the form of a ball 68 within the bore 66. The 1 bore 66 at its outer end is threaded for reception fof the abutment plug or nut '.66 between which and the ,valve 68 is interposed a spring 16 which tends to hold the valve to its seat 61 to disconnect the vplunger bore 6 3 from the space 6I.

Describing now the operation and functioningof the valving assembly, the pressure of springs 65 and 16 is such that the valves 66 and 66 will remain closed so long as the pump operates at or below a predetermined maximum delivery pressure. Should the delivery demand on the pump become less than the capacity of the pump, the delivery pressure will rise, and when the pressure becomes higher than the-predetermined magnitude, the pressure lagainst the valve 68 will overcome the resistance 'of the spring 16 and fluid will ow fromthe passages 1| and 1li, past the valve 68 into the bore of the plunger stem, and

lfrom there through ports 13 and into the space 12. From here it must ow through the relatively small orice 14, and' into thespace 15,V

As the pump pressure rises above maximum,v

the valve 68 will`be lifted oft its seat, allowing iiuid to now into space .12. vSince the size of the orice 14 is relatively smaller'than the opening afforded by the valve 68, pressure'will build up in the space 12, causing the plunger structure with its v/alve end 60 to'be lifted oil its seat 55, allowing the iiuid in excess of the demand to pass back to the reservoir.`

When the valve 66 has opened sufficiently to handle the excess uid, the pressure will stabilize at the maximum, or set pressure, and the valve 68 will partly close until the ilow p ast the valve 68 is the same as the ilow through the or'iilce 1li, thus maintaining a constant amount of iluid in Athe space 12, and holding the valve 'A 66 to the proper opening. By the same process,

. When the pressure has dropped below mum, i. e .,when the demand is thesame 'or'.lesa

flcient restriction that it makes a dashpot of plunger structure sure surface thereon normally unexposed to the pump discharge pressure but exposed to the flow through said relief passageway when said passageway is opened,- a valve for said relief passageway, means for holding said valve Iclosed against normal pump pressure but permitting opening of said valve by abnormal pressure for relief fiow through said relief passageway and exposure of said blow-off valve pressure surface to the flow through said relief passageway, means restricting the flow through said relief passageway, means tending to hold said blow-off valve closed but yielding to the relief flow pressure against said blow-off valve pressure surface for 1. A Valving assembly for controlling the pressure in a rotary hydraulic pump to prevent over-` closed against normal pressure in said pressure chamber, excess pressure against said relief valve causing opening thereof for ow of fluid through said relief passageway and against said pressure surface on the blow-off valve whereby said blowoff valve will be moved for opening of said blowoff passageway. l

2. Valving assembly for controlling the pressure in a rotary hydraulic pump to prevent overloading, comprising a pressure chamber connected to receive fluid from the pump under discharge pressure, a blow-01T passageway from said pressure chamber to the exterior thereof, a blow-off valve for closing said passageway, a relief passageway from said pressure chamber to the exterior thereof, said blowoff `valve having a pres-y sure surface normally unexposed to the pump discharge pressure but exposed to the flow through said relief Apassageway when said passageway is open, `a valve for said relief passageway and means yieldingly 'holding said valve closed against normal pump pressure, abnormal pump pressure opening said valve for ow through said relief passageway and against said pressure surface on the v'blow-off valve, yielding means tending to hold said blow-olf valve closed and permitting opening thereof under excess pressure ow through said relief passageway for opening of said blow-olf passageway.

3. A Valving assembly for controlling the pressure in a rotary hydraulic pump to prevent overloading, comprising a pressure chamber connected to receive fluid from the pump under discharge pressure, a blow-olf passageway from said pressure chamber to the exterior thereof, a blow-off valve for closing said passageway, a relief passageway from said pressure chamber to the exterior thereof, said blow-0E valve having a presopening of said blow-off passage by said blow-off valve when the pump pressure becomes excessive.

4. Valving assembly for controlling the pressure in a rotary hydraulic pump to prevent overloading, comprising a valve chamber connected to receive fluid from the pump at discharge pressure, a blow-off passageway from said valve chamber to the `exterior thereof, a blow-off valve for closing said passageway, a relief passageway from said valve chamber to the exterior thereof, said blow-off valve having a pressure surface normally unexposed to the pump discharge pressure and exposed to the flow through said relief passageway only when said passageway is open,'a valve for said relief passageway vand yielding means normally holding it closed against normal pump pressure, said valve opening under abnormal pump pressure for relief flow through said relief passageway and exposure of said blow-off valve pressure surface to said relief flow pressure, yielding means tending to hold said blow-off valve y closedA against said relief flow pressure,`a restricting orifice included in said relief flow passageway for relieving said pressure against said blowoff valve pressure surface sufliciently to prevent opening of said blow-off valve by said pressure against said yielding means but being insufficient to sufllciently relieve 'the pressure under excess pump pressure whereby said blow-off valve will then be opened for pump pressure relief through v a valve for said reliefI passageway and yielding means normally holding it closed against'normal pump pressure,` said valve opening under abnormal pump pressure for relief ow through said relief passageway and exposure of said blow-olf valve pressure surface to said relief flow pressure, yielding means tending to hold said blowpressure againstfsaid blow-off valve to prevent opening thereof under ordinary abnormal pump pressure but being insucienttorelieve the pres' sure sufficiently under excess pump pressure whereby said .blow-off valve will then rbe 'opened by the pressure against said yielding means 'forg opening Aof the blow-01T passageway and relief of the excess pressure.

' `thereof for relief of ordinary abnormal pump pressure, a blow-oil valve in said valve chamber for closing said blow-off passageway, a relief valve fbr controlling the flow through said relief passageway. yielding means holding said relief valve closed against normal pump pressure but permitting opening thereof for flow through said relief passageway under ordinary abnormal pump pres.- sure, means restricting the flow through said relief passageway whereby relief through said passageway will be gradual, yielding means tending to hold said blow-olf valve closed, said blow-off valve having a pressure surface normally unexposed to the pump discharge pressure and exposed to the flow through said relief passageway charge pressure, ablow-off passageway from the inner end of said valve chamber to the exterior thereof, a blow-off valve movable insaid guide member and yielding means normally holding said valve to close said blow-oil' passageway, a plunger head on said blow-off valve movable in the outer end of said valve chamber and normally unexposed to the pump discharge pressure, a valve chamber in said blow-oil valve, a relief passageway from the inner end of said valve chamber to the exterior thereofand including the valve chamber in said blow-off valve, a relief valve in the valve chamber of said blow-olf valve for said relief passageway, yielding means normally holding said. relief valve closed against normal pump pressure but permitting'opening thereby of said relief passageway under abnormal pump pressure, the inner side of said plunger head being exposed to the flow through said reliefpassageway only when said passageway is opened, whereby' under excess abnormal pump pressure said relief valve will first be opened for flow through said relief passageway and said blowoff valve will then be opened by the excess pressure for opening of the blow-off passageway.

8. A valving assembly foi-controlling the pressure in a rotary hydraulic pump to prevent overf, loading, comprising a valve chamber in the pump frame, a valve guiding member secured in said valve chamber intermediate its ends, the inner end of said valve chamber ybeing connected with the pump to receive fluid therefrom under discharge pressure, a blow-off passageway fromthe inner l end of said valve chamber to the exterior thereof,

a blow-ofi' valve movable in said guide member and yielding means normally holding said valve to close' said blow-off passageway, a plunger head for said blow-olf valve movable in the outer end of said valve chamber and normally unexposed to the pump discharge pressure, a valve chamber J in said blowon valve, a relief passageway from only when -said passageway is opened Iby said the inner end of said valve chamber-to the exterior thereof and including the valve chamber in said blow-on valve, a relief valve in the valve chamber of said blow-off valve for said relief passageway, yielding means holding said relief valve closed against normal pump pressure but permitting opening thereby of said relief passageway under abnormal pump pressure, the 'inner side of said plunger head being exposed to the flow through said'relief passageway only when said passageway is open, whereby under excess abnormal pump pressure said relief valve will' mst be opened for ilow through said reliefpassageway and saidv blow-oil valve will then be opened by the excess pressure for opening of said blow-off passageway,l said plunger head having a restricted passageway therethrough included in the fiowthrough said relief passageway .for retarding the closure movement of said blow-oi! valve by its yielding means after relief of. the excess Pump pressure through said blow-off passageway.

9. A valving assembly for controlling the pressure in a rotaryA hydraulic pump kto prevent overloading thereof, comprising a pressure chamber connected to receive uid from thepump under discharge pressure, a blow-oil passageway from said pressure chamber vto the exterior thereof, a blow-oir valve in said valve chamber and means normally releasably holding it for closurel of said blow-off passageway, said blow-off valve having.

a pressure surface normally unexposed to the discharge pressure yin said valve chamber, a second passageway for conducting fluid flow under discharge pressure from said pressure chamber against said blow-off valve surface, a valve for said second passageway and means normally yieldably holding it to close said second passageway against discharge now under normal pressure, excess discharge pressure against said valve A sageway, said blow-off valve having a pressure surface thereon normally -unexposed to the discharge Pressure in saidpressure chamber, a passageway through said blow-off valve for the iiow of fluid underdischarge pressure to said pressure surface, a valve for said passageway in the blowoil valve and means normally yieldably holding said valve closed against normal pressure in said pressure chamber, excess pressure against said valve in said passageway -in the blow-off valve structure causing the opening thereof for-flow of uid under discharge pressure against said pressure surface of the blow-oil' valve whereby said blow-oi! valve will then'be moyed for opening of said blow-oil' passageway.

11. A valving assembly for a rotary hydraulic pump for holding delive ressur determinedmaximum, ry p e below s' pre chamber connected with um therefrom under the D D to receive fluid discharge pressure, a blow-oil comprising a pressure passageway from said valve chamber to the exterior of the pump, a blow-ofi valve movable in said pressure chamber and yielding means normally holding it for closure of said blow-oir passageway, a second passageway from said pressure chamber to the exterior of the pump, said blowott valve having a pressure surface thereon adapted to be exposed only to fiowthrough said sec- Y ondary passageway, and a, check valve normally closing said second passageway against vilow to said pressure surface but subjected to tlre pressure in said pressure chamber to open said 'second passageway for flow therethrough against said surface when the pump discharge pressure rises above the predetermined'maximum thereby causing opening movement of said blow-oil valve for opening of said blow-off passageway. v

12. A valving assembly for a rotary hydraulic pump for holding the delivery pressure below a predetermined maximum, comprising a pressure chamber connected with the pump to receive iiuid therefrom under discharge pressure, a blow-o passageway from said pressure chamber to the exterior of the pump, a blow-off valve movable in said pressure chamber and yielding means normally holding it for closure of said blow-01T passageway, a'. valve chamber within said blow-olf valve, a second passageway from said pressure chamber to the exterior of the pump and including said valve chamber, said blow-oi! valve having a pressure surface thereon exposed only to iiow through said second passageway; a spring pressed check valve in said valvechamber normally closing said second passageway against ow .l to said pressure surface but subjected to the pressure in said pressure chamber to open said second passageway for iiow A therethrough against said sageway, a valve Ichamber within said blow-oil' Y' so valve, a second passageway from said pressure chamber to the exterior of the pump and 'includ-' ing said valve chamber, said blow-oil valve having a pressuresurface thereon exposed only to iiow through said second passageway, a spring pressed check valve in said valve chamber normally closing said second passageway againstiiow tc said pressure surface but subjected to the pressure in said pressure chamber to open said second passageway for ow therethrough against' said surface when g the pump discharge pressure rises above a predetermined maximum thereby hausv ing movement of said blow-oil. valve to open said "blow-01T passageway for reduction of the pump discharge pressure below the predetermined maximum, and means in said second passageway for resistingthe iiow therethrough when 'said check valve is open whereby to retard the opening movement of said blow-oir valve.

GERVASE M. MAGRUM.

HARRY L. CHISHOLM, Jn,

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