US3854492A

US3854492A - Gear type flow divider

Info

Publication number: US3854492A
Authority: US
Inventors: Y Kita
Original assignee: Shimadzu Corp
Current assignee: Shimadzu Corp
Priority date: 1969-07-31
Filing date: 1973-12-28
Publication date: 1974-12-17
Anticipated expiration: 1991-12-17

Abstract

A flow divider includes a casing within which a plurality of gears are rotatably mounted in intermeshing relation. The intermeshing gears constitute at least two gear-pump or gearmotor structures. Each gear pump structure has a fluid inlet and a fluid outlet and all of the inlets for a plurality of gear pump structures are connected to a single inlet port. Fluid enters through the single inlet port into a plurality of inlets. From there it is carried by a synchronized rotation of the intermeshing gears toward a plurality of outlets at substantially the same flow rate regardless of the difference in pressure at said outlets. The flow divider also operates as a flow collector.

Description

llmte tates ate t 1191 1111 3,854,492

Kita 1 1 Dec. 17, 1974 1 GEAR TYPE FLOW DIVIDER 2,291,578 7/1942 Johnson 137 99 x 2,765,749 6/1969 Mosbacher [75] Inventor. Yasuo Klta, Kyoto, Japan 3,447,422 6/1969 Bidlack at MM 73 Assigneez Shimadzu Seisakusho, Ltd Kyoto, 3,472,170 10/1969 Eckerle 418/196 X Japan FOREIGN PATENTS OR APPLICATIONS [22] Filed; Dec 1973 445.072 4/1936 Great Britain 418/196 [21] Appl. No.: 429,325

Related U.S. Application Data Continuation of Ser. No. 299,590, Oct. 20, 1972, abandoned. which is a continuation of Ser. No. 59.280, July 29, 1970. abandoned.

Primary Examiner-Robert G. Nilson [57] ABSTRACT A flow divider includes a casing within which a plurality of gears are rotatably mounted in intermeshing relation. The intermeshing gears constitute at least two gear-pump or gear-motor structures. Each gear pump structure has a fluid inlet and a fluid outlet and all of the inlets for a plurality of gear pump structures are connected to a single inlet port. Fluid enters through the single inlet port into a plurality of inlets. From there it is carried by a synchronized rotation of the intermeshing gears toward a plurality of outlets at substantially the same flow rate regardless of the difference in pressure at said outlets. The flow divider also operates as a flow collector.

7 Claims, 8 Drawing Figures PATENTEUILCI 71974 3854,492-

sum 30F 3 INVENTOR @1'00 hm BY ATTORNEY GEAR TYPE FLOW DIVIDER This is a continuation of application Ser. No. 299,590, filed Oct. 20, 1972, now abandoned, which, in turn, was a continuation of application Ser. No. 59,280, filed July 29, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a new and improved flow divider for dividing an inflow fluid into a plurality of outflow fluids of substantially the same flow rate regardless of the difference in pressure acting on the outflow fluids.

Hydraulic circuits are known and they are employed widely in various hydraulic mechanisms such as hydraulic hoists, hydraulic jacks, hydraulic lifts and hydraulic presses. Hydraulic circuits for use in these mechanisms generally includes a plurality of cylinder pistons, at least one pumping device and a fluid reservoir. The cylinder, pumping device and the reservoir are connected to each other by suitable piping and pistons in the cylinders are operatively connected to the moving or driving means of some hydraulic machine. In operation the pumping device delivers a pressure fluid, commonly oil, from the reservoir into the cylinders to move the pistons axially therein. The axial movement of these piston in turn drives the moving or driving part of the hydraulic apparatus.

In hydraulic system or circuit wherein a plurality of cylinder pistons are used and they are to be operated in strict synchronization difficulties have been encountered in obtaining the desired synchronized operation of the cylinder pistons by the introduction of pressure fluid from one fluid source into a plurality of cylinders. In one way the plurality of cylinder pistons may be communicated with a single pumping device via a suitable distributing valve which directs the pressure fluid supplied by the pump into the cylinders. In another way a pumping device is associated with each one of the plurality of piston cylinders for supplying pressure fluid thereinto. In the latter way the plurality of pumping devices may be connected to and driven by a common drive shaft. This system is commonly employed in recent years but none of the above mentioned conventional systems provides satisfactory results.

As to the first mentioned hydraulic system wherein a plurality of cylinder pistons are connected to a single pumping device via a distributor valve, it provides satisfactory synchronized operation of the pistons while substantially equal load is imposed on each cylinder piston. Once this balanced load condition is broken i.e., the load on one cylinder piston becomes greater than the load on the other cylinder pistons the normal synchronized operation of the entire cylinder pistons in the system is disturbed. More specifically, under such unbalanced load condition the hydraulic pressure within the highly loaded cylinder increases greatly in comparison with the pressure in the remaining less loaded cylinders. As the result the pressure fluid delivered by the pump tends to enter the less loaded piston cylinder making the asynchronous operation of the cylinder pistons more serious. In case such hydraulic system is incorporated into a hydraulic jack, elevator or similar apparatus for raising or lowering great weights and the plurality of cylinder pistons in the system are adapted to drive a platform of the apparatus on which a heavy material to be handled is supported it would cause seri ous operational troubles and hazards. For example, if

the cylinder pistons for driving the support platform do not move in complete synchronization and either one or more of which drive the platform to a greater extent than the others due to the above described load unbalance, the platform may incline in one direction to such degree that the heavy material on the platform may finally slip down along the inclined surface thereof forcing the normal operation to be stopped and greatly damaging the apparatus.

As to the second mention hydraulic system wherein each of the plurality of piston cylinders in the circuit is connected directly to its own pumping device it is extremely difficult to start and operate a plurality of pumps in good synchronization. Pumps may have different operational capacities. In addition, as in the case with the first system, different loads on the piston cylinders may cause a difference in the fluid discharge rate of the pumps which results in an asynchronous operation of the piston cylinders. Further, this system is costly in that it requires many pumping devices. Pumping devices on which a relatively greater load is to be applied tends to be broken down at an earlier stage of the expected operational life.

As to the third mentioned system which is a modification of the second system and wherein the plurality of pumps are connected together by a common drive shaft in order to obtain a synchronous operation of all piston cylinders, this system successfully avoids an uneven fluid discharge rate of pumping devides due to the unbalanced load condition with respect to the cylinder pistons and different operational conditions with respect to the pumping devices. However, it also requires several pumping devices which inevitably makes the entire system larger in size and more complex in construction with a corresponding cost increase. Among the several pumps to be employed in this system, those which tend to receive greater load may be subject to severe operating conditions and break down earlier than those which receive less load.

Accordingly, it is the primary object of this invention to provide a new flow divider capable of separating one inflow of fluid into a plurality of outflows of substantially the same flow rate regardless of the pressure difference at the outlets of the divider.

Another object of this invention is to provide a new flow divider which is readily convertible into a flow collector for collecting a plurality of inflow fluids into one outflow, said plurality of inflow fluids being collected at substantially the same rate regardless of the difference in pressure on said inflow fluids.

A further object of this invention is to provide a new flow divider comprising a plurality of interrneshing gears which are adapted to be driven by pressurized inflow fluid at the inlet side of the divider and which in turn carry it toward the outlet side of the divider in separate flows to form a plurality of outflows of fluid discharged from the outlet side at substantially the same flow rate regardless of the difference in pressure acting on the outflows.

A further object of this invention is to provide a new flow divider comprising a plurality of intermeshing gears for carrying pressure fluid through the divider in separate flows and a plurality of fluid inlet and outlet means which are capable of efficiently introducing inflow fluid into and outflow fluid out of the gear tooth spaces in axial direction at higher rotational speed of the gears.

A still further object of this invention is to provide a new flow divider comprising a plurality of intermeshing gears for carrying the pressure fluid through the divider in separate flows and gear periphery sealing mans which tightly seal with running clearance the peripheral portions of the gears adjacent the gear tooth meshing areas.

SUMMARY OF THE INVENTION According to one of the aspects of this invention a flow divider includes an outer casing comprising a cylindrical side wall body and a pair of end closures secured to the opposite ends of the body. At least three gears substantially identical in construction are rotatably supported on a corresponding number of shafts in side-by-side intermeshing relationship. The shafts extend axially in parallel spaced away relation between and rotatably supported via needle bearings at the opposite end on a pair of end closures. A pair of thrust members having needle bearing receiving bores are placed around the gear shafts on the opposite side of the intermeshing gears between the end faces of the meshing gears and inner walls of the end closures such that the thrust plates may engage the end faces of the gears at their inner end faces in sealing as well as sliding contact while at their outer ends inner walls of the end covers in abutting relation. The thrust plates have convex surface portions on their outer peripheries adjacent the gear tooth meshing areas. The concave surface portions are made to have a radius of curvature substantially corresponding to the radius of the addendum circles of the meshing gears.

A plurality of sealing means are provided to seal the portions of outer peripheries of the meshing gears adjacent or in the vicinity of meshing gear tooth. Each gear periphery sealing means has a pair of arcuate concave surfaces with the radius of curvature substantially corresponding to the addendum circles of the meshing gears. The sealing means are normally biased by suitable spring means toward the intermeshing gear tooth on both sides of the gear axes. In this position the sealing means extend between a pair of thrust plates with the concave surfaces of each of the sealing means abutting on opposite ends the mating convex peripheral surface portions of the thrust plates in tight sealing relation covering the portions of the outer gear peripheries adjacent the meshing gear tooth. With this arrangement each one of the adjoining two gears forms together with the cooperating sealing means and thrust plates a structure similar to a gear pump or motor.

- A pair of the above mentioned gear periphery sealing means are usually provided on the opposite sides of each pair of intermeshing gears which constitute a gear pump structure. Fluid inlet means are formed in the sealing means and thrust plates on the inlet side, while fluid outlet means are provided in the sealing means and thrust plate on the outlet side. A fluid inlet means comprises an axially extending inlet fluid passage formed in a sealing means and a pair of inlet fluid spaces formed within the thrust plates in axial direction at radial points substantially corresponding to the gear tooth spaces. The axial fluid passage communicates at both ends with the axial fluid spaces through openings made in the wall of the sealing means which faces the meshing gear tooth. One end of the axial fluid passage and one end of the axial fluid space in one thrust plate are also communicated directly with an inlet passage provided in one end closure. Similarly, a fluid outlet means comprises an axially extending fluid passage formed in a sealing means and a pair of inlet fluid spaces formed within the thrust plates in axial direction at radial points substantially corresponding to the gear tooth spaces. The axial fluid passage communicates at both ennds with the axial fluid spaces through openings made in the wall of the sealing means which faces the meshing gear tooth. One end of the axial fluid passage and one end of the axial fluid space in one thrust plate are also communicated directly with an outlet passage provided in one end closure. One inlet means is provided on the inlet side of each gear pump or motor structure while one outlet means is provided on the outlet side of each gear pump structure. Thus, the total number of inlet or outlet means corresponds to the number of gear pump structure made by the intermeshing gear sets. A plurality of inlet means are connected to a single inlet port through suitable manifold fluid path means. On the other hand a plurality of outlet means are connect to their respective outlet port.

With this construction of the flow divider, when fluid under pressure is supplied into the single inlet port of the divider it is introduced through manifold passage means into a plurality of inlet passages. From there the fluid flows directly or through the axial fluid passages into the axial fluid spaces of the thrust plates which direct the pressurized fluid axially into the gear tooth spaces of the intermeshing gears in pressure engagement with tooth faces. The pressure engagement of inflow fluid drives the gears and the fluid in turn is carried by the tooth spaces of the rotating intermeshing gears toward a plurality of outlet means in separate flows and released axially from the tooth spaces into the axial fluid spaces of outlet means. A plurality of gears being substantially identical in construction and arranged in intermeshing relation they rotate in complete synchronization transferring inflow fluid into a plurality of outlets in substantially the same flow rate regardless of the difference in pressure conditions with respect to these outlets. Thus, the single inflow of fluid through the present flow divider is effectively separated into a plurality of outflows which are discharged from the divider at substantially the same rate.

The unique construction of the present flow divider enables it to be used as a flow collector which collects fluid from a plurality of sources into a single flow. In this instance fluids from a plurality of sources are introduced into a plurality of outlets of the divider and they are carried therethrough in separate flows into a plurality of inlet means by the tooth spaces of rotating gears. Fluid flows through the inlet means are combined into one as they flow through the manifold passageway and discharged out of the single outlet of the divider. Here again, fluids are collected by the synchronized rotation of the intermeshing gears from a plurality of sources at substantially the same rate regardless of the difference in pressure acting on the fluids.

A BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood from the following'description taken in conjunction with the accompanying drawings and its scope will be pointed out in the appended claims.

FIG. 1 is a perspective view of a novel flow divider embodying the present invention;

FIG. 2 is a vertical cross-sectional view of the flow divider illustrated in FIG. 1, illustrating in detail three intermeshing gears and a pair of thrust plates provided on the opposite sides of the gears;

FIG. 3 is a cross-sectional view of the flow divider taken along the line 3-3 of FIG. 2 showing primarily the intermeshing gear construction and a plurality of gear periphery sealing members place in position on the thrust plate to sealingly cover the portions of gear peripheries adjacent the meshing gear tooth;

FIG. 4 is a cross-sectional view taken along the line 44 of FIG. 2 showing the relative positioning of the thrust plate and sealing members;

FIG. 5 is a cross-sectional view taken along the line 55 of FIG. 3 showing the first inlet and outlet means;

FIG. 6 is a schematic view of a hydraulic circuit for operating a plurality of hydraulic piston cylinders to drive a support platform of a material lifting apparatus and having a flow divider of the present invention incorporated therein;

FIG. 7 is a schematic illustration showing fluid paths through the flow divider of the present invention; and

FIG. 8 is a schematic illustration similar to FIG. 7 showing fluid paths through the flow divider of this invention when operated as a flow collector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, in particular to FIGS. 1, 2 and 3, there is illustrated a novel flow divider of this invention. The flow divider includes a casing comprising a generally cylindrical side wall body 10 and a pair of circular end closures or covers 11 and 12 secured to the opposite ends of the body. The body and the closures together form a cylindrical fluid chamber 13 within which three gears 14, 15 and 16 are disposed. The

gears

14, 15 and 16 are supported on shafts 17, I8 and 19 respectively and arranged vertically side by side in intermeshing relationship such that the gear tooth of upper and

lower gears

14 and 18 are positioned a slight radial distance away from the inner surrounding wall of the cylindrical body.

Gear shafts

17, 18 and 19 are journaled on their right side in

needle bearings

20a, 20b and 200 and on their left side in needle bearings 21a, 21b and 210, respectively.

Right needle bearings

20a, 20b, 20c are located in circular hollow recesses 22a, 22b and 220 formed in the right end closure 12 while left needle bearings 21a, 21b and 210 are received in similar recesses 23a, 23b and 230 formed in the left end closure 11. Thus, the gear shafts are rotatably supported within the casing between a pair of end closures 11 and 12.

A pair of

thrust plates

24 and 25 having needle

bearing receiving bores

26a, 26b, 26c and 27a, 27b, 27c are provided on the opposite sides of the intermeshing gears 14, 15 and 16. More specifically, as best shown in FIG. 2 one thrust plate 24 is disposed around the shafts between the inner wall 28 of the end closure 12 and the right end faces of gears l4, l5 and 16 while the other thrust plate 25 is placed around the shaft between the inner wall 29 of the end closure 11 and the left end faces of gears l4, l5 and 16. The

thrust plates

24 and 25 are similar in construction and shaped in the general form of three rings connected side by side as viewed in vertical cross section. The thrust plates are at their inner end faces in sliding as well as sealing contact with the opposite end faces of gears l4, l5 and 16 and at their outer ends in abutting engagement with the

inner walls

28 and 29 of the end closure members respectively. Bearing receiving bores 26a, 26b, 260, 27a, 27b, and 27c are formed in the

thrust plates

24 and 25 in complete registry with corresponding circular recesses 22a, 22b, 22c and 23a, 23b, 230 made in end closures 12 and 11. The bores cooperate with these recesses to receive the needle bearings placed on the shafts l7, l8 and 19. The thrust plates are in turn supported on the shafts via the needle bearings. For the purpose hereinafter explained the portions of the outer periphery of the

thrust plates

24 and 25 adjacent or in the vicinity of gear tooth meshing areas are formed to have a

convex surface portions

30 and 31 on both sides of gear axes substantially conforming to the addendum circle of the meshing gears which are substantially identical in construction.

As described hereinabove, the cylindrical body 10 is made as a separate member and end closures or covers 11 and 12 are secured to the opposite ends of the body to form a casing. For this purpose six screw bolts 32 are utilized in the illustrated embodiment which extend axially through the right end cover 12, the fluid chamber 16 and screwed into mating threaded holes (not shown) in the left end cover 11 to tightly fasten the end covers to opposite ends of the cylindrical body. It should be noted that among six screw bolts four bolts are disposed to extend in such radial position that the shank portions of the bolts may engage the inner surrounding wall 33 of the body 10. Thus, the screw bolts 32' not only function to secure the end covers to the cylindrical body but also assist in positioning the cylindrical body with respect to the intermeshed gears l4, l5 and 16.

As shown clearly in FIGS. 3 and 4, peripheral portions of two

intermeshing gears

14 and 15 adjacent or in the vicinity of gear tooth meshing area, i.e., peripheral portions of the gears immediately before and behind the meshing tooth are covered by gear

periphery sealing members

34 and 35. Similarly, peripheral portions of another two

intermeshing gears

15 and 16 in the vicinity of meshing tooth are covered by gear

periphery sealing members

36 and 37.

Sealing members

34, 35, 36, and 37 are similar in construction and elongated in directions parallel to the shafts. Each member includes a pair of arcuate

concave surfaces

38 and 39 having a radius of curvature substantially corresponding to the radius of the addendum circles of the gears. The sealing

members

34 and 35 when placed in position as shown in FIG. 3 extend and bridge between two

thrust plates

24 and 25 with the opposite ends of

concave surfaces

38 and 39 in sealing engagement with the mating

convex surface portions

30 and 31 on the outer periphery of thrust plates. The junction edges 40 where the two

concave surfaces

38 and 39 meet extend to a point adjacent the meshing gear tooth. With this arrangement peripheral portions of meshing gears 14 and 15 immediately before and behind their intermeshing gear tooth are sealingly covered by the

concave surfaces

38 and 39 of the

seal members

34 and 35. In order to permit a free and uninterrupted rotation of the gears a suitable running clearance may be provided between the

concave surfaces

38 and 39 of the sealing members and the outer peripheries of the intermeshing gears by making the

concave surfaces

38 and 39 of the sealing

members

34 and 35 and

curved surface portions

30 and 31 of the thrust plates to have a radius of curvature slightly greater than the radius of the addendum circle of the intermeshing gears 14 and 15.

Another pair of

similar sealing members

36 and 37 are used to sealingly cover the peripheral portion of the intermeshing gears 15 and 16 immediately adjacent the meshing tooth thereof in substantially same manner as that of the sealing

members

34 and 35. Thus, when placed in

position sealing members

36 and 37 extend between the two

thrust plates

24 and 25 with their

concave surfaces

36 and 39 in sealing engagement with the mating

convex surface portions

32 and 33 on the outer periphery of the thrust plates. The conjunction edges 40 where the two concave surfaces meet project to a point near the meshing tooth of the

gears

15 and 16.

Concave surfaces

38 and 39 of the

lower sealing members

36 and 37 and mating convex

peripheral portions

32 and 33 of the thrust plates have a radius of curvature slightly greater than the radius of addendum circles of the meshing gears so that when the lower sealing members are placed on the convex

peripheral portions

32 and 33 they sealingly cover the portions of gear peripheries of meshing gears 15 and 16 adjacent the meshing tooth with a suitable running clearance which permits free and smooth rotation of the gears.

Means are provided to normally urge the sealing members into position as described above. The means comprise generally U-shaped leaf springs 41 and 42. As illustrated in FIG. 3 the opposite ends of one leaf spring 41 are suitably secured by fastening screws or rivets to projections formed at the center of outer surfaces 43 of the sealing

members

34 and 37 while the apex portion of the spring is attached by fastening means 44 to a point on the inner wall 33 of the cylindrical body 10, thereby keeping the leaf spring in compression. This compression of the leaf spring produces a force which tends to push or urge the sealing

members

34 and 37 to the right toward the meshing gear tooth resulting in the desired tight sealing engagement f of the concave surfaces on the mating convex peripheral portions of the thrust plates. In similar manner the leaf spring 42 is secured at opposite ends thereof to center projections on the outer surfaces 43 of the sealing

members

35 and 36 and at its appex portion to the inner wall 33 of the cylindrical body 10 by fastening means 45, thereby keeping the leaf spring in compression. The compressed leaf spring 42 imparts a force on the sealing

members

35 and 36 which tends to urge them to the right toward the meshing gear tooth resulting in the desired tight sealing engagement of the concave surfaces of the sealing

members

35 and 36 on the mating convex peripheral portions of the thrust plates. With this simple and inexpensive spring means during operation, all of the gear periphery sealing members are effectively urged and kept in position with their concave surfaces in sealing engagement on respective mating convex periphery portions of the thrust plates.

Fluid path constructions of the present flow divider is now described. Referring particularly to FIG. 5 there is illustrated inlet and outlet passage means for the upper gear pump structure fonned substantially by two intermeshing gears 14 and 15. The end cover 11 has a fluid inlet passage 46 and a fluid outlet passage 47 axially formed therein. The sealing member 34 is provided with an elongated flow passage 43 which extends axially behind the conjunction edge and communicates at one end with the fluid inlet passage 46 of the end cover 11. Sealing member 34 is also provided with a pair of fluid openings 49 and on the line of the junction edge 40 at the opposite sides of the meshing gears 15. The axially extending flow passage 48 in the sealing member communicates through these

openings

49 and 50 with substantially axially directed

inlet spaces

51 and 52 formed in each of the thrust plates such that their inner ends terminate in the inner end faces of the thrust plates at a radial point corresponding to the tooth spaces of the upper intermeshing gears 14 and 15. The inlet space 51 also communicates at its outer end directly with the inlet passage 46 of the end cover 11. The inlet passage 46, the axial flow passage 46, the

openings

49 and 50 and the

spaces

51 and 52 together form first inlet passage means for the hydraulic fluid through the flow divider.

With this inlet passage means substantial inflow fluid through the passage 46 is introduced through the

inlet spaces

51 and 52 axially into the tooth spaces of the intermeshing gears at the inlet side, although some of the inflow may enter the tooth spaces in radial direction i.e. the direction normal to the axis of the gears. The axially introduced inflow of fluid fills the tooth spaces at the inlet side more effectively and completely than the inflow of fluid radially introduced into the tooth spaces. This is due to the fact that the flow resistance is far smaller in the axial direction than in the radial direction of the gear tooth.

Outlet passage means similar in construction to the above mentioned inlet passage means is provided in connection with the sealing member 35. Thus, the sealing member 35 has formed therein an elongated flow passage 54 extending axially behind the conjunction edge 40 and communicating at one end with the fluid outlet passage 47 of the end cover 11. The sealing member is also provided with a pair of fluid openings 55 and 56 at the opposite side of meshing gears 15 on the line of the junction edge. The axially extending flow passage 54 in the sealing member communicate through these openings 55 and 56 with axially directed

outlet spaces

57 and 58 formed in each of the thrust plates such that the inner ends of the outlet spaces terminate in the inner end faces of the thrust plates at a radial point substantially corresponding to the tooth

spaces intermeshing gears

14 and 15. The inlet passage space 57 is also communicated at its outer end directly with the outlet passage 47 of the end cover. The outlet passage 47 axial flow passage 54, a pair of openings 55 and 56 and

axial spaces

57 and 58 together form first outlet passage means for the hydraulic fluid through the flow dividerv The fluid carried by the tooth spaces of the gears from the inlet side to the outlet side is discharged released from the tooth spaces axially into the

outlet spaces

57 and 58. Thereafter it flows directly into the outlet passage 47 or flow through the fluid openings 55 and 56 and flow passage 54 into the outlet passage 47. The axial flow-out of the discharge fluid into the

spaces

57 and 58 enables the fluid trapped in the tooth spaces at the outlet side to be relieved such that entrapment of the fluid in intertooth spaces may be substantially reduced.

A second inlet means substantially identical in construction with the first inlet means is provided in connection with the sealing member 36 for the lower gear pump structure made by meshing

gears

15 and 16, while a second outlet means substantially identical in construction with the first outlet means for the upper set of the meshing gears is provided with respect to the sealing member 37 for the lower two intermeshing gears 15 and 16. For simplicity of description and illustration no explanation is given to the construction of these second inlet and outlet means but instead the corresponding parts are indicated by the corresponding reference numerals with the addition of alphabetical letter b.

It is noted that a subcover plate 58 is interposed on the left end cover 11 to provide additional fluid passage means. As illustrated in FIGS. 1 and 4, a pair of outlet ports 59 and 60 are made through the subplate in direct axial communication with outlet passages 47 and 47b respectively. A single inlet port 61 is also provided in the subplate which is in communication with the two

inlet passages

46 and 46b through a manifold passageway 62.

In order to seal around side opening 63 and 63b at which the

inlet passages

46 and 46b communicate with the axial flow passages 48 and 48b as well as the passage spaces 51 and 51b. O-rings 64 and 64b are interposed between the inner end wall 29 of the end cover 11 and the end surfaces of thrust plate 25 and sealing

member

34 and 36 contacting thereto such that the rings may surround the openings 63 and 63b respectively as best shown in FIGS. 2 and 3. Similarly, in order to seal around

side openings

65 and 65b at which the outlet passages 47 and 47b communicate with the

axial flow passages

54 and 54b and

axial spaces

57 and 57b. Another O-

rings

66 and 66b are interposed between the inner end wall 29 of the end cover 11 and the end surfaces of thrust plate 25 and sealing

members

35 and 37 contacting thereto such that the O-rings may sealingly surround the

openings

65 and 65b, respectively. With this sealing arrangement the leakage of pressure fluid between the inlet and outlet sides through the clearances which might be produced between the inner end wall 29 of the end cover 11 and the contacting surfaces of the thrust plate and gear sealing members is effectively prevented. In stead of the 0- rings any other sealing means such as rubber packings or the like may suitably be used for the purpose described above.

In order to attain a complete balance of axial pressure upon the intermeshing gears, as illustrated in FIG. 5, similar O-

rings

67 and 68 may preferably be interposed between the inner end wall 28 of the right cover plate 12 and the end surfaces the thrust plate 24 and

seal members

34, 35, 36 and 37 in substantially symmetrical relation with respect to the O-

rings

64, 64b and 66, 66b. As can be readily understood this balance of axial pressure avoids any thrust to be applied to the intermeshing gears 14, 15 and 16.

To assist in obtaining the desired axially balanced condition, as best shown in FIG. 2, thrust

plates

24 and 25 are axially recessed a slight distance away from the contacting

inner walls

28 and 29 of the end covers at the outer periphery portions of their outer end surfaces as indicated by the reference numerals 69. The outer peripheral portions 70 of the inner end surfaces of

thrust plates

24 and 25 are also recessed in axial direction a slight distance away from the opposite tooth end surfaces the intermeshing gears 14 and 16. The pressure fluid within the casing fills these recesses 69 and 70 and thereby applies substantially the same axial pressure on the opposite ends of the thrust plates with the result being the axial balance of the two

thrust plates

24 and 25. The recessed outer peripheries 69 and 70 together with the above described O-rings provide means for supporting the unit comprising the meshing gears, thrust plates and sealing members within the casing in a complete axially balanced condition.

As has been explained above, the needle bearings for rotatably supporting the

gear shafts

17, 18 and 19 are received within respective pair of circular recesses formed in the

inner walls

28 and 29 of the end cover plates 12 and 11. The

thrust plates

24 and 25 when placed in position around the gear shafts receive within their

axial bores

26a, 26b, 26c, 27a, 27b and 270, said

needle bearings

20a, 20b, 20c, and 21a, 21b, 21c, respectively. The thrust plates in turn are supported on the

gear shafts

17, 18 and 19 via these needle bearings. Bearing receiving bores 26a, 26b, 260, 27a, 27b, and 270, in the

thrust plates

24 and 25 should be fonned in precise alignment with corresponding bearing receiving circular recesses made in the end covers 12 and 11. With the accurate alignment of the bearing receiving bores with the circular recesses, abrasion of the inner walls of the bores by the rotating needle bearings is reduced to a minimum even after an extended operational period and dimensional interference between the moving parts of the flow divider due to such abrasion can be effectively avoided.

The operation of the present flow divider incorporated in a hydraulic circuit for driving a hydraulic lifting apparatus is now explained in detail with reference to FIGS. 6 and 7. As schematically illustrated in FIG. 6 the hydraulic circuit include the present flow divider FD which is connected at its inlet side to a fluid reservoir through piping 81 and at its outlet side to a plurality of

piston cylinders

82, and 83 via pipings 84 and 85. In actual circuit construction, the pipe 81 is joined to the single inlet port 61, while pipes 84 and 85 are joined to outlet ports 59 and 60 respectively. A pump P which is driven by a motor M is interconnected in the piping 81 between flow divider FD and fluid reservoir 80.

Cylinders

82 and 83 respectively include

pistons

86 and 87 which are operatively connected through suitable power transmitting means to a load support platform 90 of the hydraulic lifting apparatus. The platform is vertically movable for raising or lowering a weight placed thereon. When driven in one direction by the motor M, the pump P draws the fluid in the reservoir 80 supplies it into the inlet port 61 of the flow divider. The fluid supplied into the inlet port then flows through the manifold passageway 62 into two

inlet passages

46 and 46b in separate flows and further into the

axial spaces

51, 51b and 52 either directly or through the axial fluid passages 48 and 48b. Since the supplied fluid is under pressure the fluid flowing into the tooth spaces through the

axial fluid spaces

51, 51b and 52 not only till the tooth spaces but also pressure engages the tooth faces forcing the intermeshing gears to rotate in unison in the directions indicated by arrows in FIG. 3.

At this point it should be pointed out that in the three intermeshing gear arrangement of the illustrated flow divider a synchronized or unitary rotation of the three meshing gears 14, 15 and 16 drives the uppennost gear 14 in one direction and the lowermost gear in opposite direction because of the intermeshing relationship. Accordingly, the two inlet passage means forv the upper and lower sets of the intermeshing gears are provided on the opposite sides of the gear axes while the two outlet passage means for the upper and lower sets of the intermeshing gears are also provided on the opposite sides of the gear axes for the reason that can readily be understood by those skilled in the gear pump art.

As the intermeshing gears are rotated in unison by the inflowing pressurised fluid through the two

inlet passages

46 and 46b in the manner described above, these inflow fluids are in turn carried by the rotating gear tooth toward the outlet side of the flow divider as schematically illustrated in FIG. 7. More specifically a portion of the pressurized fluid flowing into the first inlet 46 is carried by the tooth spaces of the rotating upper gear 14 in counterclockwise direction toward the first outlet as indicated by the arrow while the remaining portion is carried by the tooth spaces of the rotating intermediate gear 15 in clockwise direction toward the second outlet 47b as indicated by the arrow. In the like manner, a portion of the fluid under pressure flowing into the second inlet 46b is transferred by the tooth spaces of the rotating lower gear 16 in counterclockwise direction toward the second outlet 47b as indicated by the arrow, while the remaining portion is car ried by the tooth spaces of the rotating intermediate gear 15 in clockwise direction toward the first outlet 47 of the flow divider.

Returning back to FIG. 6 as described above the first and second outlets 47 and 47b of the flow divider FD are connected to pipings 84 and 85 respectively, and the piping 84 and 85 are in turn connected to cylinders 82 nd and 83. Thus, the fluids under pressure permitted by the gear tooth through the divider toward the first and second outlet flows through pipings 84, 85 into the chambers of

cylinders

82 and 83, thereby forcing the

pistons

86 and 87 vertically upwards as viewed in FIG. 6. The pistons move upwards as long as the pressurized fluid is being supplied by the pump P through the flow divider FD into the cylinders. As explained hereinabove, the three intermeshing gears 14, 15 and 16 are substantially identical in construction and have the same number of gear tooth the same gear diameter the same tooth spaces etc. Moreover, they are arranged side by side in strict intermeshing relationship which assures a synchronized or unitary rotation of the three gears when the necessary driving force is applied to either one or plurality of the gears. Phrased differently, as the three gears rotate they rotate at the same operational speed due to their intermeshing relationship. Thus, during operation the fluid flowing into the two irlets are transferred by the two sets of intermeshing gears 14, 15 and 15, 16 into the two outlets at substantially the same flow rate regardless of the pressure difference at the outlet sides.

Assume that the weight W on the support platform 90 of the hydraulic lifting apparatus is disposed offcenter as indicated in dotted line in FIG. 6,. this offcenter location of the weight imposes a greater load on one piston 86 than the other piston 87. In the conventional hydraulic system this caused serious operational inconveniences since a substantial portion of pressurized fluid supply tends to enter the less loaded piston cylinder 83 under such unbalanced load condition making the load unbalance more grave as discussed hereinabove with the novel flow divider of this invention. On the other hand the unbalanced load condition with respect to the plurality of piston cylinders gives no substantial operational difficulty because the pressurized fluid supply into the single inlet port 61 of the flow divider is evenly divided into two flows which stream out from the two outlets 47 and 47b of the divider at substantially the same flow rate irrespective of the difference of pressure at the outlet sides. In the instance of the illustrated off-center location of the heavy weight W on the platform, the substantial load is imposed on the piston 86. Even though such is the load condition, the flow divider FD feeds the fluid under pressure through pipings 84 and 85 into

cylinders

82 and 83 at substantially the same flow rate. This assures the synchronized movement of of

pistons

86 and 87 which vertically elevates the support platform 90 while maintaining it in horizontal position. Any dangerous possibility of the weight W slipping down along the inclined support platform is thereby eliminated.

When it is desired to lower the platform, the pump P may be driven in opposite direction by reversing the rotation of the motor M to draw the fluid from the cylinder chambers into the divider through its two outlets 47 and 47b. Under this condition the flow divider of the present invention function as a flow collector. More specifically, as the pump operates to draw fluid through the divider back to the reservoir the pressure fluid on the outlet sides of the divider, i.e., the fluid within the

cylinders

82 and 83 is returned through pipings 84 and 85 into the two outlets 47 and 47b and discharged out of the inlet port 61 by the suction force of the pump. As schematically illustrated in FIG. 8, during the return flow a portion of the fluid into the first outlet 47 is transferred by the tooth spaces of the rotating upper gear 14 in clockwise direction toward the first inlet 46 while the remaining portion is transferred by the tooth spaces of the rotating intermediate gear 15 in counterclockwise direction toward the second inlet 46b. In the similar manner, a portion of the fluid returning into the second outlet 47b is carried by the tooth spaces of rotating lower gear 16 in clockwise direction toward the second inlet 46b while the remainder is carried by the tooth spaces of the rotating intermediate gear 15 in counterclockwise direction toward the first inlet passage 46. The fluids transferred by the rotating

gears

14, 15 and 16 into the two

inlet passages

46 and 46b are combined in the manifold section 62 and stream out of the inlet port 61 in a combined single flow. During the operation as a flow collector as is the case with the operation of the flow divider, the pressure fluids are returned from the outlet passages 47 and 47b towards the

inlet passages

46 and 46b at substantially the same flow rate regardless of the pressure difference on the outlet sides by the synchronized rotation of the intermeshing gears 14, 15 and 16. Accordingly, even if the load on the

pistons

86 and 87 varies from one another due to the off-center location of the weight W on platform 90 the pressure fluid within the

cylinders

82 and 83 are returned or collected at the same rate back to the reservoir by the flow divider acting as a flow collector. Thus, under such unbalanced load condition where one cylinder piston is heavily loaded as gainst the other any possibility of the pressure fluid in the heavily loaded cylinder being collected at a higher rate than the fluid in the less loaded cylinder is effectively prevented by operat ing the present flow divider as a flow collector.

From the foregoing description, it will be appreciated that the present flow divider has mounted within its casing three identical gears in intermeshing relationship, said intermeshing gears constituting two gear pump structures which direct one fluid flow through a inlet port into two outlet ports in separate flow of substantially the same flow rate. Thus, equal amount of fluid is discharged from the outlets even if the pressure condition at the outlet sides differs one another. This is one of the distinct advantages that cannot be obtained by the conventional flow distributor valve.

For operation the flow divider of this invention is connected at its single outlet port with a single pumping device. This successfully eliminates the necessity of a plurality of pumping device. By employing the present flow divider in a hydraulic circuit for driving a plurality of piston cylinders or the like, a simple and inexpensive circuit arrangement which allows the synchronized operation of the piston cylinders is provided.

It can also appreciated that in the present flow divider novel thrust plates and sealing members are used to sealingly cover the peripheral portions of the intermeshing gears adjacent their meshing tooth. The sealing assures the gear pump operation of the intermeshing gears. Further, since each gear periphery sealing member is an independent member separate from other constituent parts of the divider, a precise machining of the sealing members is possible to obtaining good sealing action and avoid any dimensional interference at the sealing point contributing to a higher and assured operating performance of the flow divider.

While the flow divider of the illustrated embodiment has only three intermeshing gears, more than three gears may suitably be employed in intermeshing relation depending on the number of outflows desired. The operation of the present flow divider has been explained in connection with a hydraulic circuit for driving a plurality of piston cylinders in synchronization. The flow divider of this invention may also be used satisfactory in other hydraulic application such as fluid amplifier system. In addition, the flow divider operates as a flow collector which combines a plurality of flows into a single flow taking in said flows at substantially the same rate.

While the present invention has been described in connection with details of illustrative embodiments, it is to be understood that this invention is not limited to the particular embodiment disclosed and that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.

What I claim is:

1. A flow divider for dividing an inflow fluid into a plurality of outflow fluids of substantially the same flow rate regardless of the difference in pressure acting on the outflow fluids comprising a casing having a side wall body and end closures, said casing having at one of said end closures both a plurality of fluid inlets and a plurality of fluid outlets, said fluid inlets being adapted to be connected to a single fluid supply line to form a manifold, a gear train located within said casing, said gear train comprising at least three intermeshing rotatable gears, each adjoining pair of which constitute a gear motor and pump structure having a low pressure side and a high pressure side wherein said low pressure side and said high pressure side being communicated to their own corresponding inlet and outlet formed in said one of said end closures of said casing, respectively, for rotation in unison of said intermeshing gears as fluid passes therethrough and wherein one adjoining pair of said intermeshing gears is adapted to function as a motor while the other of said adjoining pair of intermeshing gears functions as a pump in response to a difference in pressure acting on the outflow fluids, said intermeshing gears having their peripheries spaced from the inner wall of said side wall body, gear periphery sealing means for each inlet and outlet side of each adjoining pair of said gears covering the periphery portions of said gears near their meshing areas, said gear periphery sealing means having arcuate concave sealing surfaces corresponding to the addendum circles of said gears and having a running clearance therewith for free and smooth rotation thereof, a pair of thrust plates on the opposite sides of said gear train, each of said thrust plates having peripheral portions for receiving said gear periphery sealing means so that said gear periphery sealing means are maintained in position by bridging it between said two thrust plates, siad periph eral portions being shaped to receive said sealing surfaces in sealing relationship.

2. A flow divider as defined in claim 1, in which one of said thrust plates sealing means coacts with said gear periphery sealing means to form inlet and outlet passages for the fluid to be introduced into tooth spaces at the inlet side and to be discharged from tooth spaces at the outlet side, said inlet and outlet passages being formed substantially in axial directions and communicating with certain corresponding inlets and outlets formed in one of said enclosures of said casing.

3. A flow divider as defined in claim 1, in which said gear periphery sealing member is urged by spring means toward said thrust plates for sealing engagement therewith and for covering said gear periphery portions in sealing relationship.

4. A flow divider as defined in claim 1, in which each of said thrust plates has at its opposite ends recessed areas spaced from the end walls of the end closures and from the end faces of the gears to receive the fluid pressure in such manner that each of said thrust plates is balanced in the axial direction.

5. A flow divider as defined in claim 1, in which the periphery portions of each said adjoining pair of gears is covered by a pair of gear periphery sealing members at the inlet side and at the outlet side, respectively, each of said gear periphery sealing members having arcuate concave sealing surfaces corresponding to the addendum circles of said gears and being supported within said casing so that during operation, the sealing members are urged toward the peripheries of said meshing gears.

6. A flow divider for dividing an inflow fluid into a plurality of outflow fluids of substantially the same flow rate regardless of the difference in pressure acting on the outflow fluids comprising a casing having a side wall body and end closures, said casing having at one of said end closures both a plurality of fluid inlets and a plurality of fluid outlets, said fluid inlets being connected to a single fluid supply line to form a manifold, a gear train located within said casing, said gear train comprising at least three intermeshing rotatable gears, each adjoining pair of which constitutes a gear motor and pump structure having a low pressure side and a high pressure side wherein said low pressure side and said high pressure side being communicated to their own corresponding inlet and outlet formed in one of said end closures of said casing, respectively, for rotation in unison of said intermeshing gears as fluid passes therethrough and wherein one adjoining pair of said intermeshing gears is adapted to function as a motor while the other of said adjoining pair of intermeshing gears functions as a pump in response to a difference in pressure acting on the outflow fluids, gear shafts for mounting the respective intermeshing gears thereon, said gear shafts being rotatably supported at their opposite ends through bearings in circular recesses formed in said end closures, the peripheries of said intermeshing gears being spaced from the inner wall of said side wall body, a pair of gear periphery sealing members covering the periphery portions of each of said adjoining pairs of gears near their meshing area at the inlet side and at the outlet side, respectively, each of said gear periphery sealing members having arcuate concave sealing surfaces corresponding to the addendum circles of said gears and having a running clearance therewith for free and smooth rotation thereof and being supported within said casing so that the sealing members are urged to the peripheries of said meshing gears, and a pair of thrust plates on the opposite sides of said gear train, each of said thrust plates having peripheral portions for receiving said gear periphery sealing members so that said gear periphery sealing members are maintained in position by bridging them between said two thrust plates, said peripheral portions being shaped so as .to receive said sealing surfaces in sealing relationship, one of said thrust plates coacting with said gear periphery sealing members to form inlet and outlet passages for the fluid to be introduced into tooth spaces at the inlet side and to be discharged from tooth spaces at the outlet side, said inlet and outlet passages being formed in substantially axial directions and communicating with their corresponding fluid inlet and outlet in said one of said end closures, said thrust plates being supported by said gear shafts through the respective bearings.

7. A flow divider as defined in claim 3, in which the opposite ends of each of said gear periphery sealing means are in contact in a sealing and slidable engagement with the respective inner walls of said end closures.

Claims

1. A flow divider for dividing an inflow fluid into a plurality of outflow fluids of substantially the same flow rate regardless of the difference in pressure acting on the outflow fluids comprising a casing having a side wall body and end closures, said casing having at one of said end closures both a plurality of fluid inlets and a plurality of fluid outlets, said fluid inlets being adapted to be connected to a single fluid supply line to form a manifold, a gear train located within said casing, said gear train comprising at least three intermeshing rotatable gears, each adjoining pair of which constitute a gear motor and pump structure having a low pressure side and a high pressure side wherein said low pressure side and said high pressure side being communicated to their own corresponding inlet and outlet formed in said one of said end closures of said casing, respectively, for rotation in unison of said intermeshing gears as fluid passes therethrough and wherein one adjoining pair of said intermeshing gears is adapted to function as a motor while the other of said adjoining pair of intermeshing gears functions as a pump in response to a difference in pressure acting on the outflow fluids, said intermeshing gears having their peripheries spaced from the inner wall of said side wall body, gear periphery sealing means for each inlet and outlet side of each adjoining pair of said gears covering the periphery portions of said gears near thEir meshing areas, said gear periphery sealing means having arcuate concave sealing surfaces corresponding to the addendum circles of said gears and having a running clearance therewith for free and smooth rotation thereof, a pair of thrust plates on the opposite sides of said gear train, each of said thrust plates having peripheral portions for receiving said gear periphery sealing means so that said gear periphery sealing means are maintained in position by bridging it between said two thrust plates, siad peripheral portions being shaped to receive said sealing surfaces in sealing relationship.

6. A flow divider for dividing an inflow fluid into a plurality of outflow fluids of substantially the same flow rate regardless of the difference in pressure acting on the outflow fluids comprising a casing having a side wall body and end closures, said casing having at one of said end closures both a plurality of fluid inlets and a plurality of fluid outlets, said fluid inlets being connected to a single fluid supply line to form a manifold, a gear train located within said casing, said gear train comprising at least three intermeshing rotatable gears, each adjoining pair of which constitutes a gear motor and pump structure having a low pressure side and a high pressure side wherein said low pressure side and said high pressure side being communicated to their own corresponding inlet and outlet formed in one of said end closures of said casing, respectively, for rotation in unison of said intermeshing gears as fluid passes therethrough and wherein one adjoining pair of said intermeshing gears is adapted to function as a motor while the other of said adjoining pair of intermeshing gears functions as a pump in response to a difference in pressure acting on the outflow fluids, gear shafts for mounting the respective intermeshing gears thereon, said gear shafts being rotatably supported at their opposite ends through bearings in circular recesses formed in said end closures, the peripheries of said intermeshing gears being spaced from the inner wall of said side wall body, a pair of gear periphery sealing members covering the periphery portions of each of said adjoining pairs of gears near their meshing area at the inlet side and at the outlet side, respectively, each of said gear periphery sealing members having arcuate concave sealing surfaces corresponding to the addendum circles of said gears and having a running clearance therewith for free and smooth rotatiOn thereof and being supported within said casing so that the sealing members are urged to the peripheries of said meshing gears, and a pair of thrust plates on the opposite sides of said gear train, each of said thrust plates having peripheral portions for receiving said gear periphery sealing members so that said gear periphery sealing members are maintained in position by bridging them between said two thrust plates, said peripheral portions being shaped so as to receive said sealing surfaces in sealing relationship, one of said thrust plates coacting with said gear periphery sealing members to form inlet and outlet passages for the fluid to be introduced into tooth spaces at the inlet side and to be discharged from tooth spaces at the outlet side, said inlet and outlet passages being formed in substantially axial directions and communicating with their corresponding fluid inlet and outlet in said one of said end closures, said thrust plates being supported by said gear shafts through the respective bearings.