AU4709779A

AU4709779A - Atwo-speed pump assembly

Info

Publication number: AU4709779A
Application number: AU47097/79A
Authority: AU
Inventors: Albert W. Vanderstappen; Richard F. van Allen
Original assignee: ALBERT W VANDERSTAPPEN; RICHARD F VAN ALLEN
Current assignee: Brock Equipment Co
Priority date: 1978-05-26
Filing date: 1979-05-16
Publication date: 1979-11-29
Also published as: BR7903248A; IT7949158A0; DE2921359A1; ES8100434A1; FR2426815A1; NL7903953A; BE876566A; JPS5529082A; ZA792240B; ES480941A0; GB2021683A; IT1126813B

Description

C,n 4hhmf ar

We iROCK EQUIPMENNT COMPANY

of 8603 Pyott Road, Crystal Lake, Illinois 60014, United States of America

e' v 4 hereby:,apply for the grant of a Patent for an invention entitled 9•@ 9 "A TWO-SPEED PUMPel ASSEMBLY" 4,,

4 49# w4 99

whict is described in the accompanying complete specification. This application is a Convention Application and is based on the application numbered 909,'963

for a patent or similar protectior, made in United States of America

on 26th May, 1978 4. 0 0 *9Q* S -My- address fol service is: Our Care: SPRUSON FERGUS6N PATENT ATTORNEYS ESSO HOUSE, 127 KENT STREET SYDNEY NEW SOUTH WALES. AUSTRALIA.

Dated this FIFTEENTH day of MAY 19 79 BROCK v 4 ENT ii~r0 ba opot W 1uPa cw a~ A,ppstion m~ade. for a fran iniwnzdtloa eifltted

"A TW')-tMCD PUMP ASSElMBLY"

Pugi nnw *oidad* Marvin Hans Richer *Wuof J).olAuL of 8603 Pyott R~oad Crystal Lake, IL 60014, United States of America do solemnly and sincerely declare as follows:-

so 0' (or, in the case of an application by a body corporate) am authorised by BROCK( EQUIPM4ENT COMANY the applicant for tgpaltent .to make this declaration on its behalf.

[No"r cowtuy and 2. The basic application as defined by Section 141 of the Act was made in 4Zt of buic appli- cawIn WW nsme of United States of America on the 26ti day of May 19 78Bby Albert W. Vanderstappen and Richard F. Van Allen

(o hr eso te hnth netri teapiat *u.4eada-3. ABR .VADRTPE

Ful nmean a. LRICAR F. VAND AEN dw~o(Iw~~(a of5Car Ilioais Road3, Cr.Ilni 01. United States of America,

ntited Usat Saktes piof aeiaflo-

inenatur nvs os.f iveto

4. The basic application referred to in paragraph 2 of this Declaration Was the first application made in a Convention country in respect of the invontion the subject of the application. Declared at: Crystal L.6kblthis Z~th day of May 19 79

Sisn~ture of De#cIkr=at To:'

:I

i;

AUA 1

(12) PATENT SIECIFICATION ABS- AU (19) AU (21) 47097/79 (22) 16.5.79 (23) 16.5.79 (24) 26.5,78 (31) 909963 (32) 26.5.78 (33) US (43) 7,9.i.79 (51)2 F04B 3/00 F04B 23/06 (54). A TWO-SPEED PUMP ASSEMBLY (A (71) BROCK EQUIPMENT COMPANY (72) VANDERSTAPPEN A.W. AND VAN ALLEN R.F. t~ (74) SF (57) A method is also claimed. CLAIM

4. A two-speed pump assembly for delivering fluid from a reservoir to a utilization device compri sing: a fluid channel connected to the utilization device; a low pressure pump for automatically precharging the fluid chanro a predetermined low pressure at a f~r~t predetermir.-d w te rate; and a high pressure pump for charging t he fluid channel to a predetermined higx. oressure at a second #.ziume rate lowep than the first volume rate.

i

45.2

FOR OPPICE UE

Class Int. Class APploatiron Nvmbai Lordged

j/ Conplot. Specification Lodged Accepted "'V

Published 0e Pakity

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sg.atod Art 0

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Name of Applicant BROOK EQUIPMENT COMPANY

q*e .gd;*ss of Ap).,icanV 8603 Pyott Road, Crytal Lake, Illinois 60014, C P7 United States of iAmerica,

,?Atfol Inventor 4 ALBERT W. VANDERSTAPPEN and RICHARD F. VAN ALLEN

Alress for Service Spruson Ferguson, Patent Attorneys, Eno House, 127 Kent Stret, Sydney, Now South Wales, 2000 Australia. 0rr

Compoi. Spocificotico for the invention entitled

"A TWO-SPEED PUMP ASSEMBJY"

The folowing statement is a full description of this invention, including the best method of performing 4' 610". tro"f *us

P k

SAn improved, manually-operable two-speed hydraulic pump for delivering fluid from a reservoir to a utilization device. A first low pressure, hioh volume pump automatically, precharges a fluid channel to a predetermined low pressure o and a second high pressure pump raises the fluid to a pre- determined high pressure at which an automatic high pressure relief valve opens. Replaceable, modular check valves are provided between the low pressure pump, the high pressure

90 10 pump, and the utilization device. The check valves are I *9. R 0 *9*9 modular in construction and have a spring and check ball con- 4 9, *9 tained witiiin a hollow cylindrical member having a ball seat 4 0

*0*0 formed as part of the hollow cylindrical member. Automatic U. *9 4 *9 pressure relief valves limit fluid pressure in the pump. .49 S Manual relase of high pressure is difficult unless the auto- matic high pressure relief valve has opened. A method for providing high pressure fluid to a 4* *1* 4 9 5* utilization device includes precnarging a conduit from a low •I o «J pressure fluid pump and then automatically pressurizing the e*

20 fluid in the conduit to a high pressure with a high pressure 09 fluid pump. The method may also include limiting the low 9 pressure as well as the high pressure by an automatically

S operated relief valve. BACKGROUND OF THE INVENTION This invention relates generally to hydraulic pumps

and more particularly to hydraulic pumps for providing hydraulically de eloped forces for pressure operated dies and the like which may, for example, apply compression fittings to electrical conductors 9f various types, which may cut wire? and the like. These pumps may be hand operated or foot

-2- ~9.

operated in conformity with the requirements of a particular application. A

-Portable hydraulic presses are known in the prior

art. U.S. Patent No. 2,815,646 issued to Swanson on December 10, 1957, discloses a hydraulic compression tool

having a main pump which is operated by swinging two handles toward and away from each other to pump fluid at high pressure against a main cylinder which advances a movable die towards a fixed die so as to develop high compression fdrces there- 0 between. An auxiliary pump is provided to facilitate faster 0

initial advancement of the movable portion of the die under C, 0000*4a low pressure towards the fixed portion of the die. Operation of the low pressure pump requires twisting one of the handles

so as to advance or retract tha movable die portion. C6m- pression tools of this type are heavy and often involve use 00 0090O 6 in situations where the operator must maintain the tool in *040

an awkward, uncomfortable position so that devices which 0*@ 4 *I *0 0Q require manual twisting of a handle both to initia]ly close 4 0 0

the dies around a workpiece and then to open the dies after 0 high pressure compression are tedious and fatiguing to operate. Automatic changeover from a fast advance/low pres-

3 sure to high pressure operation without having to twist a handle is especially desirable in these other applications. L

00* It is also desirable that upon completion of a task an operator does not have to manually twist a handle to retract the movable die to remove the workpiece. Automatic die with- de~al is a desirable operational feature for such equipment Prior art fluid actuator pumps have varuis kinds

df ball-check fluid valves which have a valve seat formed as 0 an integral part of the housing of each device. Remachining of a valve seat requires reworking an entire housing. Elim- ination of or use of modular, replaceable valve assemblies is desirable for this type of apparatus. SL14M4ARY OF'THE INVENTION~ It is, therefore, an object of this inv6eition to provide a two-speed pump assembly having combined low pressur& and high pressure piston assemblies to provide a hydraulic pump having reduced overall size. It is another object of this invention to provide

10 a two-speed pump assembly having serially connected conduits lot#*

and utilizing a reduced number of check valves.

#Not It is dnother object of the invention to provide

N, replaceable, throw away, modular check valves in a high 3O B

pressure hydraulic pump assembly. It is another object of the invention to provide

a two-speed hydraulic pump assembly which is easy to assemble

and to repair the component parts thereof.

It is another object of the invention to provide a two.-.speed pump assembly which is activated by applying both hn and low pressure operational forces at a single force

application poin- and which automatically changes from low 4, pressure to high pretssure operation. 0 0 It is another object of the invention to provide

a hydraulic pump which rapidly advances a tool until resis- tance to movement occurs. It is another object of the invention to provide a method of operating a hydraulic pump which automatically changes mode of operation when a predetermined pressure is

attained. 30 It is another object of the invention to provide !4

I.

S.- a pump assembly which requires an operator thereof to pump

the fluid to a predetermined maximum high pressure rather than to prematurely manually redease pressure in the system. Accordingly, a two-si e& pump assembly is provided for delivering fluid i!rom a rese,:oir to a utilization means 0 which includes a low pressure unit, a high pressure unit, and a utilization means unit. The low pressure unit has a low pressure pump for delivering low pressure, high volume, fluid, the maximum low pressure being limited by an automatic

10 low pressure relief valve. The high pressure unit includes a high pressure pump for low volume, high pressure operation. O Check valves are placed between the fluid reservoir and the

959 S low pressure unit and the loi pressure unit and the high pres- 99 sure units. The utlization means includes a check valve in 0 o

a conduit to the high pressure idnit and an automatically operated high pressure relief valve. The check valves are removable modules having hollow cylindrical members containing SO seats for spring-biased check balls. According to another aspect of the invention a two- speed pump assembly is provided which has a low pressure

9. 9 pump for automatically precharging a fluid channel at a given volume rate and which has a high pressure pump for pressuriz- ing the fluid channel to a predetermined high pressure. Another aspect of the invention provides a combined, compact

assembly of coaxial, intermeshing low and high pressure pis- tons with the low pressure piston having a larger working surface. According to another aspect of the vention, a

method of providing high pressure fluid to a u} ilization device includes precharging a utilization means at a low

I NC r pressure and a high'fluid volume rate from a low pressure pup n pressurizing the fluid to a high pressure with a

high pressure pump. The pressure developed by each pump is automatically limited to predetermined values. DESCRIPTION OF THE PREFERRED EM~BODIMENT Referring now to Fig. I of the drawingsi a t'1_o-

speed pump assembly 10 is shown as part of a hand-operated compression tool 12 of the type commuonly used for crimping, swaging, splicing, etc. of multi-stranded cable and the like. .o *0 Ii 0 Fig. 2 shows in somewhat more detail the two-speed pump assemn- 490 9 0000 bly. Referring to Fig. I of the drawings, the compression 90 00 90 tool 12 includes several major components. Affixed to one 9000 0 U 0 0090 end of the two-speed pump assembly 10 is a handle assembly 09 0 009 4 14 which has an internally threaded fitting 16 for attachment 0 *090 0000 4 to the two-speed pump assembly 10. A handle 18 which is for-

med, for example, from fiberglass or another suitable non-

0090 conductive material for use in connection with high voltage 9 *0 00 0 09 e~lectrical power distribution lines, has a hollow chamber

090 0 formed therein which containi3 a flexible bladder 22 for con- 04

O taining the hydraulic fluid used to operate the pump. The

0 bladder 22 is formed, for example, from a neoprene rubber 00

9400 0 material and contains at one end thereof a plug arrangement 0 400000 0 24 which is held in position by being threaded into the handle 18 and which serves as a stopper for the bladder 22. As shown in Fig. 2 and Fig. 3 of the drawings,

a fulcrum bracket 30 is attached to the pump assembly 10 by bolts 32 being threaded into apertures formed in t}tm pump assembly 10. The fulcrum bracket 30 has a bore 34 formed therethrough. ~.movable handle 36 as shown in rig. 1 of the O drawings has a pair of ears 38 (one showna) attached to one

L 6 *4

4:4 'I I9

O~d tbreo~l, A gpin 40 p -as throug'h the bore 34 in the

fulorum.bracket 3,0 and the holes in th' ears 38 so that the movable band assembily 36 pivots around the axis of the ful- crum hreacket bore 34 towards and away from the handle assem- bly 14. The movable handle assembly 36,is formed, for exampleo, from a hollow fiberglass tube. A trigger 42 is pivotally attached to a rod 44 contained within the handle assembly and moves a free end of an actuator 46, which is pivotally attached to the handle assembly 36, in a direction along the axis of the movable handle assembly 36. 'This causes the free end of the

actuator 46 to be alignable with a manually operable pressure :*Off release valve 48 mounted on the pump assembly 10 as shown. Referring to Fig, 1 and Fig. 5 of the drawings, a pin 040 0 passes through holes in the ears 38 and through a rectangularly *0*

shaped channel bracket 52, which has a split 54 formed therein lor engaging an undercut portion 56 of a piston assembly 58.

*0:00 In operation tlvh'-pin 40 serves as the pivot fo.. 'be movable handle assembly{ 3O' as it swings toward and away from th hanle asemby 14~ ~e pin 50 moves in a circular arc

20 with respect to the axis oth~e pin 40. The channel bracket 52 slit 54 loosely enga undercut portion 56 of the piston assembly 58 so thtt~movement of the pin 50 through a portion of an arc is conve ad 4:0 a straight line motion for

the piston assembly 58. Becahise tb-IO- actuator 46 is loaate,$ much farther from the Pin 40 Jt A is pin 50, the lever force 01 fP exerted on the rtoleas~i valveiA4? L-s considerably less than that

applied to the pinto,{ anaemI, 58. This makes the manual release valve 48 dif 4cult 'zo operate when the pump has a high pressure therein. It is therefore easier for an

1 0 i_ I I, 1 i'

operator to Continue to operate the pump to obtain the maxi-

mum pressure level required be exerted on a particular workpiece with a subsequent au matic release of that pressure than it is for the operator to attempt to releasethe pump pressure manually. This insures that full force is applied

to a workpieos, Referring to Fig. 1 of the drawing, an exemplary hydraulic power take-off assembly 60 is affixed to an end of the two-speed pump assembly 10. This assembly contains a

V .0 spring-retractable, hydraulically advanced piston (not shown) which applies mechanical force to a crimping die assembly 62 a affixnd to an end thereof. The crimping die assembly 62 has a 0,40#0 C-shaped member which supports a fixed die half 64 and a als movable die half 66 dr,.ven by the hydraulic power take-off

0*00e assembly

Figs. 2, 3, 4, and 8 show the exterior details of

the two-speed pump assembly, Referring to Figs. 2 and 8 of the drawings, two-speed pump assembly 10 has a projecting portion with external threads 70 formed thereupon for engage-

0 ment with the internal threads of the fitting 16 which is part of the handle assembly 14. A groove 72 is formed in S•that same projecting portion of the pump assembly 10 for accepting dhe open end of the flexible bladder 22 which is contained within the handle assembly 14. Referring to Fig.

a compression ring 73 is placed over the portion of the flex- ible bladder 22 contained within the groove 72 and is com- pressed by the interior surface of the fitting 16 when it is threaded onto the pump assembly 10. Referring to Fig. 3 of the drawings, threaded holes 74 are provided for attaching

various utilization devices such as, for example, the hydraulic power take-off assembly 60 as shown in Fig. 1 of the drawing to the two-speed pump assembly 10. Many other hydraulic power utilization devices and means for providing operating power for the pump known in the art, such as, for example, foot-operated levers to drive the pistons, may be attached to the two-speed pump assembly as desired. Referring now to Fig. 9 of the drawings, a hydraulic schematic diagram shows the interrelationship of the various elements which form the tw6-speed pump assembly 10. Hydraulic fluid for the system is obtained and returned to a common reservoir 80 containing hydraulic fluid at atmospheric pressure* e •During the intake stroke of a low pressure pump 82, fluid is drawn from the reservoir 80 through a fluid conduit 84 and through a one way check valve 86 to a low pressure fluid 9 conduit 88. The one way check valve 86 permits fluid to flow only in the direction indicated by the arrow with fluid flow in the opposite direction being prevented. A low pressure

.0 relief valve 90 opens at a predetermined pressure to permit fluid flow from the low pressure fluid conduit 88 through a o~ •0 fluid conduit 92 to the fluid reservoir 80. The pressure ,in the low pressure fluid conduit never exceeds the pre- determined value as determined by the pressure relief valve The volume of fluid pumped by the lot! ptessure pump 82 is relatively large in comparison with the voldme of fluid pumped by a high pressure pump to be described hereinbelow. It is readily understood that the volume rate of flow of a pump determines the rate, or speed, at which a hydraulically- operated device advances against minimal resistring forces. For example, it is desirable to quickly bring the ie halves of a press together as rapidly as possible using low hydraulic pressure. Once the die halves are tdother high hydraulic pressure iss appltad to exert high, force on A wI!rkpiece in the die or to hold the die halves tightly together., The low pressure pump 82 is utilized to pump relatively large volumes of fluid at no more than a certain predetermined fluid pressure as determined by the low pressure relief valve opening pressure. A high pressure pump 100 on its intake stroke draws fluid through a one way check valve 102 into a high pressure fluid pump conduit 1.04. As noted previously the low pressure pump .9 10 82 has a greater volume rate than the high pressure pump 100. *04

When the fluid circuit is first being pressurized, the low 04 mE .9 000@ presciure pump 82 haLving a greater fluid flow rate, provides 4 4 *000 fluid from the low pressure fluid conduit 88 through the one

.9 *94 way check valve 102 to the high pressure pump conduit 104 and 0094 9 then through a onc. way check valve 106 to a power take-off fluid conduit 108. Aftar a sufficient volume of fluid at low pres-

*9*9 sure is built tip in the system, the high pressure pump 100 04 9* 4

9, pressurizes the fluid in the conduit 104 and 108 at pressures .ini 9 exceeding the maxim~um,prassure permitted in the low pressure 00 4 9 009 fluid conduit 88 by the low pressure relief valve 90 setting. A power take-off device, or utilization device, 110 is 9. 9. i voupled to fluid conduit 108. This device 9,sp for example 4 *00004 4 a hydraulic power take-off assembly 60 which drives a crimping din 60 as shown in Fig. 1 of the drawings. The low pressure pump 82 precharges the high pressure pump 100 fluid conduit 104 and the utilization conduit 108 at a relatively large rate of fluid flow until the predetermined low pressure vtlue for the low pressure relief valve 90 is reached in conduit 88. Thim allows a utilization device 110 to htve a large volume of fluid at relatively low pressure applied thereto so thatt for example, the movable die half of a crimping device is moved into contact with a workpiece. Once the die halves are in contact with the workpiece, high pressure is supplied by the high pressure pump 100. Fluid conduit 108 is in communication with a high pressure relief valve 112 which when a predetermined high pressure fluid pressure value is reached in conduit 108 opens to permit fluid f3ow to fluid conduit 114 and thence to the reservoir 80 at atmospheric pressure. This limits the maxi- mum pressure developed in the power take-off 'fluidconduit *eq

108 to a predetermined high pressure value. The high pressure erelief valve 112 stays open. for a time sufficient for the

fluid pressure in conduit 108 to be considerably reduced to 4 j value much less than the maximum pressure in that conduit. 4 6 too* The presence of the automatic high pressure relief valve 112

insures that a predetermined maximum pressure is provided to

0404 the utilization, or power take-off, device. After the hiqh 4.e U pressure relief valve 112 is activated, the pressure in *44 conduit 108 is reduced to a value sufficiently low so that a 04 .SO manually operated release valve 116 may be easily actuated by an operator. Operation of the manual pressure release valve 116 permits fluid in the conduit 108 to flow through a conduit safe* 118 back to the fluid reservoir 80. After the manual pressure release valve 116 in opened, ptessure in the fluid circuit is reduced to a minimal value determined by the residual pressure required to open check valves 102 and 106. Havinq the manual release valve 116 operative with a considerablv smaller mecha- niceal advantage than that employed for the high pressure pis- ton makes it asier for an operator to operate the high pree- msure pump to the point where the high pressure relief valve

112 automatically opens than to manually open the release valve 116 with the high back pressure thereupon. The hydraulic fluid flow circuit of Fig. 9 of the drawings shows tht. interconnections required for a two-speed pump assembly 10. Fig. 5 of the drawings shows the mechanical details. As shown in Fig. 5 of the drawings, a pump assembly block 120 which is molded, for example, from an aluminium alloy material with appropriate bores being machined therein. A reservoir 80 containing appropriate hydraulic fluid is shown 10 in Fig. 5 being formed from the flexible bladder 22 of Pig. 1 for illustrative purposes only. The same numerals are used to designate various elements in Fig. 9 which were used with gFig. 9. The elements of Fig. 5 are used also for illustrative purposes and it is not intended that the fluid schematic of

Pig. 9 of the drawings be limited only to the embodiment as shown in Fig. 5 of the drawings. Referring to Fig. 5 of the drawings, the fluid 1 reservoir 80 communicates with the fluid conduit 84 formed 4 *4

within the pump block 120 as shown. A one way ball check .4

'20 valve 86 is located within a bore 122 in the block 120 as shown in Fig. 7 of the drawings. The cheek valve 86 is a .aS: replaceable module and comprines a hollow cylindrical body *4440; 124 which contains a biasing spring 126 and a check ball 128,

which seats in a valve seat portion 130 of the body 124. A fluid passageway 132 provides fluid communication between the conduit 84 and the hollow ihterior of the cylindrical body 124. ArrO.iing 134 is seated in a qioove 136 in the cylindrical body 124 to provide a seal for the modular ansembly in the bore 122. When the valve seat 130 becores worn, the cheek valve imodule

86 is replaced rather than renachining the pump block 120.

As previously described, fluid flows through the check valve 86, to the low pressure fluid conduit 88 as shown in Fig. 5 of the drawings. The low pressure fluid conduit 88 is connected to a I4 pressure pump 82 which has a pump chamber 138 formed between the walls of a bore 140 formed in the block 120 and a housing member 142, which will be described her below. A low pressure pump piston 144 is a hollow cylindrical member which is contained in the bore 140 and which envelops the housing member 142. The piston 144 moves along the axis

10 of the bore 140 and is part of the piston assembly 58, pre- i viously described as moving in a straight line motion by e Sforces exerted, for example, by a pivotal lever arm. A O~gA

scraper ring 146 for the piston 144 is provided in the block *9 120 near the outside surface thereof. An O-ring 148 and a too: ring backup member 150 are contained in a groove formed in the outer surface of the piston 144, providing a low pressure seal for the low pressure pump assembly. In operation, as Otto 4 .4* S* the piston 144 is drawn out of the pump chamber 138, fluid .4 is drawn from the reservoir 80 through the conduit 84 and

lS*to through the check valve 86 into the low pressure fluid conduit 88. On the inward stroke of the piston 144 pressure is 4

exerted on the fluid in the charier 88 causing the check valve ball 128 to seat preventing fluid flow back to the eservoir 80. The valve 102 opens to permit a relatively large volume of fluid to flow into the conduit 104 in a manner which may be characterised as high speed. The fluid flows from the corduit 104 through the check valve 106 to a utilization device (not shown). Pressur and fluid volume ar. thus quickly built up in a low pressure circuit, which i tolly includee conduits 88 and 104. A relatively large

IT.- 13 *K

X. 4 w

voltme of fluid is supplied to the utilization device througl (Qhedkvalve 106 by the 10 pressure pump 82. The low pressure

relief valve 9D automatically operates to predeterminedly release the pressure in the conduit 88. In a bore 152 in the block 120, is-co 7 ned a check ball 154 wich is biased by a force from a spring 156, the spring force being adjust- able by virtue of lock screws 158 which are threaded into the bore apd have fluid passageways through the center thereof to permit fluid communication with the fluid conduit 92 and the reservoir C. S.t The high pressure pump 100 includes a high pressure el id chamber 160 which is connected to the high pressure 6 pump fluid conduit 104. The housing member 142 has a central ~I bore therein forming the high pressure fluid channel 1CC. OO0 Contained within the bore is a high pressure pump piston 162 which is a solid cylinder coaxial with the low pressure piston 44. The piston 162 has an external groove contained therein 06e for containing an 0-ring 164 and a back-up ring 166, providing

a high pressure fluid seal for the high pressure pump 100. 620 The high pressure pump piston 162 has a shoulder member 168 whiph cooperates with a retaining ring 170 to fasten the high 6Ifl *1 69 pressure pump piston 162 coaxially to the low pressure pump *9 6

piston 144 as shown in Fig. 5 of the drawings. Another O-ring 170 provides a pressure seal for the assembly. Since the high pressure pump piston 162 and the low pressure pump piston 144 are assembled together as a unitary device, the stroke

SSS (,$foboth pistons is the same with the effective area of the high pressure pump piston 162 being much less than that of the low pressure pump piston 144. The volume displacement of the high pressure pump is therefore much less than that of the low pressure pump. The ratio between the displaced volumes of the pistons may be varied, for example, as required ~rparticular applications, by changing the diameter of the high pressure piston 162 and of the mating lous~ng member 142 bore. The housing member 1462 has an extendihg threaded portion 171 which threads into a bore f ormed in the block 120. In operation, after the low pressure fluid conduit 80 has provided the required volume of fluid at low pressure to the utilization device, the high pressure pump 100 draws small amounts of fluid as needed from the low pressure conduit 88 and exerts high pressure on the fluid in the conduit 104 which conmuni- cateiF through the check valve 106 with the high pressure utilization device. Changeover from a high Violume rate/low pre~ssure mode of operation to a low volume rate/high pressure mncde of operation is automatically accomplished when the low pressure relief valve 90 opens. An operator, for example,

*o~ea hand-operated compression tool 12 continues operating the handles 18 and 3(N towards and away from each other while the pump assemably 10 mode of operction is automatically changed

when the utilization device tool advancement is resisted and the system fluid pressure increases beyond the low pressure C relief valve 90 setting. The operator is required to do

nothing except to continue operating the handles. When the maximum high pressure is reached in the system, the high pressure relief valve automatically opens to permit the system pressure to be reduced to a level where the manual high pressure release valve may be easily operated. The replaceable check valve 102 is modular in constructionL and comprises a biasing spring 172, a check ball 174, and a cylin-

drical memaber 176 as shown iig.7 of the drawings. The

i1s

Iba13 174 for~ms' a -seal with a seat machined in the member 176, ~Whic~h masy be rlaced as required. A passageway 1178 is formed in the outer peripheral surface of the cylindrical member 176 to permit fluid to flow to the low pressure relief valve The check valve 106 is replaceable and comprises a biasing spring 180 and a check ball 182 which seats in a valve seat formed in a hollow cylindrical member 84 contained in a bore 186 and the block 120. 0-rings 188 and 190 provide seals for the check valve 106, Check valves 86, 88 are retained within

the bore 122 and the block 120 by a set screw 192.

Referring to Fig. 7 of the drawings, the power take- off fluid conduit 108 is in fluid communication with the threaded portion of the bore 122. The bore has a high pressure

4 relief valve 112 threaded therein as shown in Fig. 5 of the drawings. The high pressuire relief valve 112 is, for example a replaceable, modular poppet valve which is set to automnati- cally release, for example, at 10,000 pounds per square inch 0S Ufluid pressure. After release of the 'high pressure relief

valve 112,. fluid pressure droPs siniatyin the high pressure conduit 1064 A manually operated release valve 116 is then easily operated and provides fluid communication be- 4 4' tween fluid conduit 108 and 118 as seen in Figs. 5 and 6 of the drawings. The release valve 116 includes a check ball 194

biased by a spring 196, the ball being moved away from-a valve seat contained therein by a plunger 198 which is pushed by an actuator 46 as described hereinabove. After a suitable utilization device is affixed to the two-speed pump assembly, hydraulic fluid is poured into the reservoir 80, which is, for example, the bladder 22

having the plug arrangement 24. Air, being undesirably

4 -16-

I compressible, is required to be purged from the system. This

is accomplished by operating the pump until the low pressure

relief valve 90 opens. Then the manual high pressure release

valve 116 is held open while the pump continues to be operate4.

Finally, the unit is operated so thatU the high pressure relief

valve 112 4,s activated. This procedure will quickly sweep all

air bubbles into .the reservoir where air can be easily dis-

placed by the addition of fluid, providing an air-free body

of fluid. The series arrangement of the check valves and one

of the hi pressure relief valves permit rapid purging of air 0W0 from the sysem.

While a particular embodiment of this system accord- *9

ing to the invention has been shown and described, it should

69 be understood that the invention is not limited thereto since *0OI

many modifications may be made. It is therefore contemplated 0**

9O to cover by the present applicat6doany and all such modifi- cations that fall within the true ppirit and scope of the S9 00 0• basic underlying principles disclosed and claimed herein.

*O J

00•

09 9

The claimns defining tho. invention are as follows: 1. A two-speed pump assembly for delivering fluid from a reservoir a utilization means comprising: a low pressure unit ,including: a low pressure fluid conduit; a low pressure fluid pump means for forcing fluid at relatilvely low pressure and high volume from the reservoir to the low pressure conduit a first check valve permitting fluid flow only from the reservoir to the low pressure conduit; an auto- matic low pressure relief valve permitting fluid at a pressure 000 greater than a predetermined low pressure to flow from the low

pressure conduit to the reservoir; a high pressure unit in- cluding: a high pressure pump fluid conduit; a second check

valve permitting fluid flow only from the low *pressure conduit Go tc-" -the high pressure conduit; a high pressure, low volume pump

means for drawing fluid from the low pressure conduit to the high pressure conduit and for pressurizing the fluid; a high

pressure utilization means unit fluid channel, including: a high pressure utilization fluid conduit in fluid communication with the utilization means; a third check valve permitting too fluid flow from only the high pressure pump fluid conduit to

the high pressure utilization fluid conduit; an automatic *high pressure relief valve permitting fluid at a pressure greater than a predetermined pressure to flow from the high pressure utilization conduit to the reservoir; and a manually operable high pressure fluid release valve permitting fluid flow between the high pressure utilization "-aa7.it and the reservoir. 2. The pump assembly of Claim I including a pump assembly block wherein the check valves comprise removable modul~es contained within the pump assembly block.

Claims

3. The pump assenibly of Claim 2 wherein the check

valve modules compri.se: a spring, a check ball biased by the spring- and a,hollow cylindrical member for containing the spring and check ball and having a ball seat contained therein, the sp-.ring-biased ball and ball seat forming a fluid check valve. 4. A two-speed pump assembly for delivering fluid from a reservoir to a utilization device comprising: a fluid channel connected to the utilization device7 a low pressure

V* pump for automatically precharging the fluid channel to a a predetermined low pressure at a first predetermined volume 80*0 0rate7 and a high pressure pump for charging the fluid channel

to a predetermined high pressure at a second volume rate lower

than the first volume rate. A compact two-speed pump assembly comprising: a low pressure pump having a hollow cylindrical piston, said piston having an axcis7 a high pressure pump with a solid cylindrical piston, said piston located within the hollow cylindrical piston on the same axis; a low pressure fluid aconduit pressurized by the low pressure pump; a high pressure fluid conduit; and a check valve permitting fluid flow from the low pressure pump conduit to the high pressure fluid conduit, fluid in the high pressure fluid conduit being pressurized by the high pressure pump, so that the low pres-

sure pump initially precharges the high pressure fluid con- duit at a low pressure and at a volume rate of flow greater than the volume rate of flow of the high pressure pump. 6. The pump assembly of Claim 5 including a low pressure relief valve operable at a predetermined pressure level on the fluid in the low pressure conduit*

ITT

7. The pump assembly of Claim 5 including a high 1W pressure relief valve operable at a predetermined pressure

level on the fluid in the high, pressure conduit. 8. The pump assemrbly of Claim 5 wherein the hollow cylindricj,' piston has a working surface of greater area than that of Vic solid cylindrical piston permitting the hollow cylindrical piston to move a greater quantity of fluid for each piston stroke thereof. 9. A method of providing high pressure fluid to a utilization meano comprising the steps of: precharging a high pressure flunid 6nduit connected to the utilization means from a low pressure relatively high volume fluid pump meansl and *969pressurizing fluid in the high pressure fluid conduit to a

high pressure with a high pressure fluid pump means. The method of Claim 9 including the step of automatically limiting the fluid pressure provided by the low pressure pum~p means to a predetermined low pressure valve, switching operation to a high pressure mode.

limiing11. The method of Claim 9 including the step of limiingthe pressure in the high pressure conduit to a predetermined high pressure valve by an automatically operated .99, relief valve. 99999912. The method of Claim 11 including the step of

releasing by a manually operated release valve the residual pressure remaining in the high pressure conduit and the stop of constructing the manually operated1 release valve apparatus so that grtiater effort is required to open the valve at higher pressures in the high pressure fluid conduit then to continue operating the pump.

~JA~ I

TA'

DAM~ ths OURTENT H 4y of MAYJ 1979

Patent Attorneys for the Applicant SPRt3SOX FERGUSON

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