US3179120A - Proportional flow divider - Google Patents

Description

April 20, 1965 2 Sheets-Sheet 1 Filed May 24, 1963 PII 20, 1965 R. w. ERICKSON ETAL 3,179,120

PROPORTIONAL FLOW DIVIDER 2 Sheets-Sheet 2 Filed May 24, 1963 United States Patent O 3,179,120 PRUPGRTIONAL FLOW DIVlDER Robert W. Erickson and John F. Lindell, Newton, Iowa, assignors to- Koeln-ing Company, Milwaukee, Wis., a corporation of Wisconsin Filed May 24, 1963, Ser. No. 282,953 1 Claim. (Cl. 137-161) This invention relates generally to a tractor mounted material loader of the type including a vertically swingable boom having a material handling bucket at the outer end of the boom.

In loaders of this type it is necessary that the boom and bucket movements are properly coordinated under various operating conditions, and this is usually accomplished by means of hydraulic cylinders and an associated hydraulic control system for the cylinders.

One of the important functions which are required of such a control system in the operation of the loader is to keep -the bucket level and thereby prevent an accumulated load therein from spilling while the boom and bucket are swung up and down in unison relative to the ground.

The principal object of the present invention is to provide an improved proportional ow divider which lends itself for use in a hydraulic control system of the mentioned character and by means of which the desired leveling of the bucket will be effected automatically while the boom is moved up or down from one vertically adjusted position to another.

More specilically it is an object of the present invention to provide an improved proportionalow divider of the mentioned character incorporating a check valve which in association with other circuit components will control operation of the boom lift cylinder as well as of the bucket tilt cylinder.

These and other objects and advantages will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawing, in which:

FIGURE 1 shows a tractor mounted loader which utilizes the present invention, the view being more or less schematic in nature in regard to the hydraulic circuit and valves; and

FIGURE 2 is a more simpliiied schematic diagram of lthe circuit shown in FIGURE 1.

Referring to the general organization shown in the drawings, 4the tractor T has a pair of lift arms 1 pivoted about a horizontal axis 1a at their rear ends. A bucket B is pivoted about a horizontal axis 2 to and between the free ends of the lift arms or booms 1.

Double acting, hydraulic lift cylinders 3 (one shown) are pivotally connected between the tractor and the lift arms to vertically position the latter, and second double acting hydraulic cylinders 4 (one shown) are connected between the bucket and the boom to tilt the bucket relative to the arms.

A standard two-spool, four-way control valve V is mounted on the tractor and has a lift cylinder spool 6 yand a bucket tilting spool 7, both of which are axially shiftable by the operator, to connect the cylinders as will more fully appear with a hydraulic pump (not shown) but which furnishes pressure fluid to inlet port 8 of the control valve. An outlet port 9 of the valve V dumps the low pressure fluid back to the tank 1l) via conduit 11.

. The general system also includes a normally closed, pilot operated load check valve 14 which opens when pressure of a sutlicient amount is applied to the pilot passage 15. The spool 16 of valve 14 is subjected at its right end, as viewed in the drawing, to pressure from pilot passage 15, while the other end of the spool is open `to simply drain leakage of iluid to the tank via drain conduit`2l. A manual adjusting screw Ztl is provided for changing the resilient loading of the spring 20a on the spool 16.

Excessive pressure in passage 15 passes through cross bores 15a and shifts the spool to the left. This movement permits fluid from conduit 17 to ow into passage 18 via annular groove 19, and then to conduit 22, as will more fully appear.

If no pressure is applied to pilot passage 1S, then fluid flow from conduit 17 is blocked from passage 1S and conduit 22.

A conduit 22 then places passages 1S and 1S in communication with the head end of bucket cylinder 4 and with conduit 23 which in turn communicates with the bucket spool portion of the control valve V. Another conduit 25 places the conduit 17 and valve: V in iluid communication with the -rod end of cylinder ffl.

Adjustable liow proportoner or self-leveling vulve An adjustable flow proportioning or self-leveling valve 30 is provided in the hydraulic system and is constructed as follows. A cylindrical valve chamber Sli within a housing is closed at its opposite ends by plugs 51 and S2. The valve chamber presents end lands 37C, 37d, and intermediate lands 37e, 37j spaced axially from each other and from the end lands in the space between the latter. A central fluid passage 53 extends transversely of the valve chamber between the intermediate lands 37e, 37f and communicates with a fluid inlet port 54 of the housing. A first lluid outlet passage 55 and a second iluid outlet passage 56 extend transversely ofthe valve chamber at the axially opposite sides, respectively, of the central tluid passage 53 intermediate the end lands 37C, 37d, and; terminate at a iirst fluid outlet port 31 and at a second,`

fluid outlet port 34, respectively, of the housing. An

axially shiftable valve spool 37 within the valve chamber Sii has a radially recessed central portion presenting an external groove G within the central passage 53. Thespool 37 also has axially recessed iirst and second end portions 57, 58 in sliding engagement, respectively with the end lands 37e and 37d. An internal passage of the valve spool 37 connects the external groove G with the interior of the rst axially recessed end portion 57 and presents a iiow restricting orifice 33. A iirst branch passage 59 within the housing connects the central passage 53 with the end of the valve chamber Sil which communicates with the second axially recessed spool end 58.

An adjustable flow restrictor 39 withinthe branch passage` 59 has a variable orifice 41. A second branch passage 60A connects the central passage 53 with the lirst outlet passage 55; and a check valve 36 within the second branch passage 6u is biased to accommodate fluid flow through the second branch passage 60 in the direction from the first outlet passage 55 into the central passage 53 and to when the lift cylinder spool 6 is shifted to the appropriate position, as will appear.

The function of the valve 36 is to divide the flow into two streams in a iixed proportion. relatively constant at different flow rates.

Assume valve 30 is set to divide the flow between conduits 33 and 32 in the order of 9% and 91%, respectively.

Any flow into the valve 30 from line 35 iiows into the inlet of the valve, and some oil then tends to go through the fixed orifice 33 to the 91% port.

The variable orifice can be adjusted to provide the desired pressure drop across itself. The adjusted pressure Patented Apr. 20, 1965 This proportion is` drop provides the desired drop in relation to the drop across the lixed orice. These two different pressures on different ends of the spool 37 cause the spool `to shift and either open or close depending on the setting. This shift ing causes the spool to meter through the cross holes 37a or 37b that are drilled toward the outer ends of the spool.

The setting of the adjustable oritice thereby determines the ratio that the llow is split into.

Whenever oil is owing from line 35 through the proportion v-alve 30, and either line 32 or 33 become shut off by a cylinder so they can accept no oil, the flow to both lines is shut olr". Assume oil is flowing and the bucket cylinder 4 becomes extended and thereby line 33 will laccept no more oil. At the instant the cylinder stops, the pressure in the left side or adjusted portion et the valve will rise to the same pressure as that of the inlet. This pressure on the left end of the spool would cause it to shift'to the right and thereby shut olf the ilow to line 32 because the cross holes 37a in the right end of the spool would be covered by the land 37C at the right side of the body. The process would be exactly the same if line 32 became blocked, only the spool would shift to the left to cut off flow to line 33.

Oil can ow in reverse from line 32 back to line 35 because of the check valve 36. When oil is owing out of line 32v to line 35 via check valve 36, a slight back pressure in line 32 will keep oil from coming from line 33 out into the inlet or line 35. The only way it would be possible to get reverse flow from 33 to 35 would be if there was a pressure in the rod end of the bucket cylinder to pressurize line 33. This is never the case so no reverse flow results.

If line 33 is pressurized by an external force when no reverse ow exists from line 32 to line 35, oil from line 33 cannot pass into line 32. As soon as the pressure rises in line 33, the spool 37 shifts to the right and the cross holes on the right end of the spool seal lines 35 and 33 from line 32.

The circuit also includes a conduit i2 which places the rod end of cylinder 3 in communication with the lift spool portion of control valve V.

It should be understood that the pilot operated load check valve 14 and the flow proportioning valve could be incorporated in the same housing or sandwiched or stacked together.

The operation of the circuit will now be described in greater detail and in reference to both standard operating functions as well yas special operating functions. The terms lluid or oil will be used interchangeably, it being understood that the invention is usable with any iluid medium as a pressure producing medium.

Raising lift arms In order to raise the lift arms 1, the spool 6 is pulled to admitlluid via conduit 35 to the proportioning valve 30. The adjustment lll of thevvalve 3@ is set as previously mentioned, for example, to divide the flow between conduits 33 and 32 in the order of 9% and 91%, respectively. Of course, this ratio of tlow is adjustable according to the particular loader on which the invention is used. At any rate, in the present example, 91% of the pressure uid passes through the annular groove G of the spool and is conducted by conduit 32 to the yanchor end of cylinder 3 to raise the lift arms. The fluid from t-he opposite -rod end of cylinder 3 then lloWs via conduit 42 and through valve V to the tank. At the same time, Huid from conduit 35 is prevented from flowing directly through the proportioning valve 30 because of the oneway check valve 36.

As the lift arms are raising, 9% of the fluid is conducted via conduits 33 and 22 which connect with conduit 23 and the lluid llows into the anchor end of cylinder 4. At this time, fluid is trapped in the rod end of cylinder 4 by the pilot operated load check valve 14. The

4f pressure rise of this trapped fluid in the rod end of cylinder 4 causes a pressure rise in conduit 22 which in turn is reflected in pilot passage 15, thereby causing the check spool 16 to open slightly, permitting fluid llow from line 17, through check valve 14 and out passage 18, and conduit 22 and then to the anchor end of cylinder 4.

This will cause the bucket B to dump a predetermined amount in relation to the rise of the lift arms, in accordance with the amount or proportion of lluid that is bypassed by the proportioning valve 30.

The lluid entering passage 15 from conduit 33 controls the speed of the self-leveling because this rluid is required to causethe pressure build up in conduit 22.

It the bucket is heavily loaded, fluid would tend to be forced out conduit 17, but this is prevented because the load check valve 14El is not open until a pressure is created in conduit 22.

The above-mentioned opening and closing of load check valve 143- is a continuous metering operation as contrasted with a definite stop and start operation; as a result, theV To effect dumping of the bucket, the bucket spool 7 is pushed to cause tluid to beradmitted to conduit 23 andsirnultaneously permits lluid to return to the tank via con.

duit 25.

When conduit 23 is pressurized, conduit 22 is also pressurized, the load check valve 14 can open but no flow occurs because of check valve 24 in conduit 17; therefore, fluid returns tothe tank through line 25 and via passage 25a of Valve V. Fluid is prevented from leaving via conduit 33 by the proportioning valve 3u which is so designed that lluid cannot flow from conduit 33 back'into conduit 32 or 35.

Bucket retracling To retract the bucket B, the operator pulls bucket spool '7 of the control valve V, causing lluid to tlow into line 25 to the rod end of bucket cylinder 4 andallows fluid to tlow out of the anchor end through line 23 to the tank 1li. Any pressure created in line 25 will-carry over to the pilot operated load check 14, via line 17. Oil from line 17 cannot get into passage 13 because line 22 and 23 are open to the tank, so the pilot operated load check 14 in turn would be closed.

Lowering lift arms To lower the lift arms l, the operator pushes the lift spool 6 on the control valve V. This causes fluid to flow into line 42 and open line 35 to the tank. Oil then lows out of the anchor end of the lift cylinder 3 through line 32 and through the check valve 36 and into line 35 to the tank. Oil cannot get into line 35 from line 33 due to the design of the proportion valve 39.'

Simultaneous pushing of both spools In the event both spools are pushed at the same time, the cylinder which requires least pressure will be'actuated first, and this depends on the particular loading on the machine at that particular time. inder to move has completed its operation, then the other will be actuated.

Simultaneous pulling of both spools If the bucket cylinder 4 needs the most pressure, the lift cylinder 3 would move and 9% of the l'luid would then go to line 22 and return to the tank, as line 23 would be open to the tank. At the same time, there would be a After the first cyl-V pressure in the rod end of the bucket cylinder 4 equal to the pressure in line 35 because they are both at pump supply pressure or open to a common supply. The bucket B in this instance could possibly dump a little if the lift cylinder 3 was able to force the iiuid back out of line 25 into the pump supply. This would have a slight regenerative eltect on the lift cylinder 3 and might cause it to speed up slightly.

If the lift cylinder 3 needed the most pressure, the bucket B would retract as in the normal bucket retract operation. Line 25 would be pressurized in this instance and thereby line 17 also. However, the pilot operated load check valve 14 would shut ott line 17, because line 22 would be at low pressure due to the fact that it is open to the tank through line 23.

It both cylinders needed the same pressure, some fluid would be coming into line 35 and some into line 25. In that case (in the example mentioned), 9% of the oil from line 35 would then pass to line 33 and to the tank at low pressure `via line 22 which connects to line 23 that is open to the tank. Any fluid that would be entering line 25 at the same time would cause the bucket to roll back (counterclockwise), because oil from line 25 could not pass the pilot operated load check valve 14, because line 22 is then at low pressure and the load check valve 14 closed.

Pushing both spools If the bucket cylinder 4 requires more pressure, the lift cylinder 3 will move rst. Conduits 23 and 42 will be pressurized by the control valve spool movement. The arms 1 will lower as in a standard lowering lift arm operation. Line 22 will also be pressurized, but no oW will occur either to line 33 or 17 due to the proportioner valve 36 and check valve 24. If the lift cylinder 3 needs more pressure, the bucket cylinder 4 will dump the bucket because line 25 is open to the tank, and the pressure in lines 23 and 22 cannot be relieved because of the proportion valve 30 and check valve 24. If both cylinders need about the same pressure, the lift arms will lower and the bucket will dump to some extent, but both actions will happen at a slower rate.

Pulling lift spool und pushing bucket spool If this spool action takes place, and the lift cylinder needs more pressure, the bucket will dump as in normal operation. The pressure in line 23 and 22 will be maintained because of the check valve 24. If the bucket cylinder needs the pressure, the lift arms will rise and 9% of the oil from line 35 will go to line 33 and from there to line 22. The pilot operated check 14 may open, but no flow from line 22 to line 17 would occur because of the check valve 24. The oil from line 22 would go to the anchor end of the bucket cylinder, and the bucket will dump as the arms rise.

If the bucket for some reason could not dump, the oil from line 22 Would get back into line 23 from line 22 and regenerate back into the control valve V and from there again to line 35.

If both operations need the same pressure, the lift arms would raise and the bucket would dump, but the dumping action would be slower because there may not be a regenerative etlect of the tluid ilowing from line 17 back into line 22 and from there to the anchor end of the bucket cylinder, because conduit 25 is open to the tank, and the oil from the rod end of the bucket cylinder would return to the tank.

Pushing lift spool und pulling bucket spool It the bucket cylinder needs the pressure, the lift cylinder will move and lines 42 and 25 will be pressurized. This will cause the lift arms 1 to lower with oil going out of line 32, check valve 36 and conduit 35.

If the lift remains stationary, the pressure in line 25 will cause the bucket to roll back. Line 17 would be pressurized in this instance also, but the oil would not go through the pilot operated load check valve 14 because line 22 is at low pressure along with line 23 which is open to the tank.

If both units moved together, the lift arms 1 would lower and the bucket would roll back simultaneously.

A vertical upward force on the lip of the bucket with the arm stationary In this instance, a pressure would be induced in the rod end of the lift cylinder, but it would not move because the lift spool of the control valve has the `ports blocked. A pressure would also be induced in the anchor end of the bucket cylinder, and this would also be blocked by the valve bucket spool 7. The pressure in line 23, however, will carry over to line 22, and this would cause the pilot operated load check Vvalve 14 to open, but any flow through it would be prevented by the check valve 24.

A vertical downward force on the lip of the bucket with the arms stationary A force on the bucket lip causes an induced pressure in the anchor end of the lift cylinder. This pressure is blocked by the lift spool 6, and also by the proportion valve 30 which prevents flow out of line 33 unless there is ilow from line 35 to line 32. Pressure will also be induced in the rod end of the bucket cylinder 4, and this is blocked by the bucket cylinder spool of the control valve. This pressure also carries over to line 17 but tlow is stopped by the pilot operated load check valve 14 which would be closed because there would be no pressure in line 22.

Lifting lurms with bucket cylinders fully extended y In this instance, line 35 would be pressurized. Thel division of flow would be 91% to line 32 and 9% to line 33. Line 33 could accept no oil because it is connected to line 22 which in turn is connected to the anchor end of .the bucket cylinders. The bucket cylinders would not move because they were already extended. In this case, due to the proportion valve 30, ow would stop. When all the flow stops it would be necessary to retract the bucket cylinders before the lift arms could be raised.

Recupitulution By means of the present invention, an adjustable, ow proportioner valve has been provided in a hydraulic systern for a self-leveling bucket type loader, by means of which the bucket is automatically maintained in a level position as the lift arms are raised. This is accomplished without the need of special mechanical linkages, special sets of properly proportioned hydraulic rams for various types and sizes of loaders, and with special series valves or slave cylinders. At the same time, an easily operated and highly versatile control system is provided which functions in an efficient manner. The system is foolproof in operation, easy to service, and adjust, and is capable of adaptation to loaders of existing design without appreciable modiiication thereto.

Various modes of carrying out the invention are contemplated as being within the scope of the following claim particularly pointing out and distinctly claiming the subject matter which is regarded as the invention:

We claim:

In a proportional ilow divider, the combination of a housing having a cylindrical valve chamber presenting a pair of axially spaced annular end lands and a pair of intermediate lands spaced axially from each other and from said end lands in the space between the latter; a central fluid passage extending transversely of said valve chamber between said intermediate lands and communieating with a fluid inlet port of said housing; a rst and a second uid outlet passage extending transversely of said valve chamber at the axially opposite sides, respectively, of said central uid passage intermediate said end lands and terminating at first and second outlet ports of said housing; an axially shiftable valve spool within said valve chamber having a radially recessed vcentral portion presenting an external annular groove Within said central passage, axially recessed first and second end portions in sliding engagement, respectively with said end lands, and an internal passage connecting said external groove with the interior of said first axially recessed end portion and presenting a ilow restricting orifice; a first branch passage Within said housing connecting said central passage With the end of said valve chamber communicating With said second axially recessed end portion of said valve spool; an adjustable ow restrictor Within said first branch passage lhaving a variable orice; va second branch passage conthrough said second branch passage in the opposite direction; said axially recessed end portions of said valve spool having radial apertures in cooperative relation with said end lands, respectively, so Vas to proportion the ow of tluid from said central passage into said outlet passages by axial shifting of said valve spool within said valve chamber.

References Cited b'y the Examiner UNITED STATES PATENTS M. CARY NELSON, Primary Examiner.

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