US2998025A - Combination valve - Google Patents

Description

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COMBINATION VALVE Filed Sept. ll, 1957 2 Sheets-Sheet 2 K a. c

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2,998,025 COMBINATION VALVE Stanley I. MacDuif, South Bend, Ind., assignor to The Bendix Corporation, a corporation of Delaware Filed Sept. 11, 1957, Ser. No. 683,423 8 Claims. (Cl. 137-622) The present invention relates to control valves of the Itype adapted to supply a modulated pressure to one or the other of two outlet ports; and more particularly to a hydraulic control valve of .the above referred to type.

An object of the present invention is the provision of a new and improved control valve formed by a chamber yof uniform cross section having a feed port, a control port, and an exhaust port, spaced in that order, and a jvalve spool therein having first and second land portions* :the rst of which overlies a portion of the chambers sidewalls between the feed and control ports, while the second land portion overlies a Iportion of the .sidewalls between the control and exhaust ports, and wherein movement of the spool axially of the Vchamber varies "the relative leakage rates from the feed to the control port and 'from the control to the exhaust port to smoothly regulate the control pressure in the control port.

Another object of the present invention is vthe provision rof a .new and improved control valve having a rst portion for modulating a control pressure intermediate inlet 4and exhaust pressures, and a .second portionfor diverting this pressure to one or the other of a pair of outlet ports thereby modulating the pressure in either one of the outlet ports.

.Another object of the present invention is the provision of a new and improved control valve of the immediately 'above referred to type having a controlled member with two degrees of movement--one degree of which is used to actuate the first referred to valve portion and the second degree of movement of which is used to actuate the second valve portion to smoothly deliver a modulated pressure to either one of a pair of outlet ports.

Another object of the presen-t invention is the provision of a ynew and improved hydraulic control valve having a iirst portion for producing a modulated pressure and a second portion -for conducting the modulated pressure to either one or both of a pair of outlet ports-the second valve portion being adapted to close off one of the outlet ports when its movable member is moved out off its center position by a predetermined amount, and also being adapted upon continued movement in the same direction to dump all pressure from the previously valved off outlet port, whereby modulated control of the systems connected to the outlet ports can be vachieved by an intermediate degree of control lmovement and pressure .in either of the systems controlled can be quickly dumped by extreme movements yof the control member.

The invention resides in certain constructions and com- .binations and yarrangements of parts, and further objects and advantages will 'become apparent Ito those 'skilled in the art to which the invention relates from the following description of the preferred embodiment described with reference to the accompanying drawings, and in which:

FIGURE l is a cross-sectional view of a valve embodying the principles of the present invention and which view also schematically depicts the hydraulic system in which the valve is intended to be used;

FIGURE 2 is a fragmentary cross-sectional view of porting in the valve;

ice

FIGURE 3 is a fragmentary cross-sectional view taken approximately on the line 3 3 of FIGURE l.

The hydraulic system shown in FIGURE l of the drawings is adapted to perform the combined functionsI of operating a hydraulic lift on a farm tractor, as Well as to operate the t-wo rear wheel brakes of the vehicle.. The system shown is of the open center type wherein; iiuid discharged from hydraulic pump A is continually circulated through the system back to the reservoir B'y without producing any appreciable back pressure against. the hydraulic pump A, until such time as either the .hy-- draulic lift C, or either one or both of the brake applying, wheel cylinders D and E are actuated by the operator.y Related systems are shown in the S. I. MacDulT Patent; 2,517,005 and the l. B. Brown Patent 2,624,361; and the major advantage of such systems is that instantaneousA control is always available without wasting appreciable amounts oi energy except during those times when the control devices are actually actuated. Peculiar problems are involved in the control of the system shown in the drawing, however, inasmuch as each of the brake applying wheel cylinders D and E must be smoothly supplied with modulated pressure to actuate either of the 'wheel cylinders individually or simultaneously.

The control valve G shown in the drawing for controlling the operation of the wheel cylinders D and E comprises a body member lo having a `generally vertically extending cylindrical bore l2 therein, provided with a now-through port 14, a feed port 16, a control port 18 and `an exhaust port 20, spaced apart vertically in that order. Fluid from the reservoir B is supplied to the pump A by conduit 22, and the discharge of pump A is supplied to the feed port i6 through the conduit 24. in the normal condition of the valve, wherein neither of the wheel cylinders D or E are being actuated, flow from thepump A is communicated directly from the feed port 16 to the flow-through port 14; and is thence conducted through an open center control valve 26 to its exhaust line 28 by which the ilow is returned to reservoir B. The iluid discharged from the pump A circulates continually through this system at a pressure just sutiicient to overcome line friction until such time yas either the control valve 26 or the control Valve G is actuated, whereupon a suitable back pressure is created by either of these control valves, .26 or G, against the pump A to actuate the control device. The control valve 26 may be of any well known commercial construction; i-t `forms no part of the present invention; yand will not be elaborated upon. -It will be seen, that during the normal condition of the hydraulic system, substantially no pressure will exist in the feed port 16; `and tha-t a variable pressure will be eX- perienced in the feed port lr6 during actuation of the hydraulic lift C depending upon the back pressure devolop-ed by its control valve 25. It is a function of the pontion G1 of the control Valve comprising the valve ports previously recited to deliver various degrees of pressure from 'the feed port 16 to the control port 14 when back pressure from the control valve 26 is experienced; and to, at the same time, provide means for developing a sui-table back pressure in the feed port 16 whenever the control valve `26 is not being actuated.v Fluid presume delivered to the control port 16 is thereafter controlled by a second portion G2 of the valve, which portion, either simultaneously or individually, delivers the control pressure to one or the other of two outlet ports 30 and 32 which respectively communicate with the.

wheel cylinders D and E through lines 314 and 36 respectively.

The pressure modulating portion G1 of the valve is completed by a movable valve member or slide 38 positioned in the vertically extending cylindrical bore 12 and adapted to control communication between its various valve ports. The movable valve member 38 is formed from a generally cylindrical structure having a generally predetermined t with respect to the sidewalls ofthe cylinder bore 12, and is provided with three vertically spaced land portions 40, 42, and 44, formed by recesses '46 and 48, the first of which must have a generally predetermined width with respect to the distances between the feed and exhaust ports 16 and 18 as will now be described.

In the normal position of the movable valve member 38, the bottom edge of the first land portion 40 will be held open from the bottom edge of the exhaust port 20 a generally predetermined distance a extending through an opening 52 in the bottom end of the bore 12 to abut the lower end of the movable valve member 38. Plunger 58 is provided with a shoulder 54 which by a plunger 50 engages the upper end of a counter bore 56 which acts as .l a stop for the shoulder 54, and the plunger is held in its upper position against the upper end of the counter bore by a coil spring 58 positioned between the ange 54 and an end cap 60 screwed into the lower end of the counter bore 56. The first recess 46 has a width which is less than the width of cylinder sidewall separating the feed and exhaust ports 16 and 20 by an amount, which will provide an amount of overlap b with respect to the feed port 16, which is greater than the underlap distance a previously recited by a predetermined amount.

width of the feed port 16 by an amount which will provide an underlap clearance c between the lower end of the second land portion 42 and the lower end edge of the The width of the second land portion 42 is made less than the 'l feed port 16 by an amount greater than the overlap b. Y ,v In the normal position of the movable valve member 38 just recited, discharge from the pump A will therefore be able to proceed with substantially no restriction from the feed port 16 through the clearance c provided between the lower edge of the second land portion 42 and the bottom edge of the feed port 16 to the dow-through port It is a desired object of the present invention to provide controlled leakage between the feed port 16 and the exhaust port 18 by means of a predetermined clearance between the movable valve member 38 and its cylinder walls; such that a pressure will be created within the first recess 46 which will produce a leakage rate out past the first land portion 40 to the exhaust port 20, which just equals the rate of leakage into the rst recess 46 past the second land portion 42. It would be seen, therefore, that downward movement of the control member 38, after the time that the rst land portion closes o the -exhaust port 20, will cause a gradually increasingresistance to ow out of the recess 46, while at the same time decreasing the resistance to leakage into the recess 46 from the feed port 16 until such time as the movable valve member has been moved the distance b and` the top edge of the second valve land portion 42 begins to open the feed portion 16. By suitable designingf'th'e clearance between the movable valve member 38 andthe side walls of the cylinder, with respect to the inletrpressures to the valve, the general range of modulated pressure desired, and the amount of valve travel desired, laminar dow can be assured in the leakage paths into and out of the recess 46. It will thus be seen that smooth and sensitive control will therefore always be achieved Vwhen the pressure in the control port 18 approaches its vset poin by properly controlling the amount of clearance provided between the movable valve member 38 and the side walls of the cylinder bore 12.

The above stated valve movement produces pressure within the control port 18 provided back pressure existed in the feed port 16 as a result of back pressure produced by the control valve 26. :If the hydraulic lift C was not being actuated at the time the foot pedal structure 70 was being actuated, no pressure rise would be experi--V enced within the rst recess 46 until such time as the lower edge of the second land portion 42 is brought into the proximity of the lower edge of the feed port 16. The second land portion 42 is preferably provided with a width less than that of the feed port .16 by an amountV leakage therepast, no sudden rise in pressure in the feed Actuating movement of the movable Ivalve member 38 is accomplished through a graduation spring 64, the lower end of which is seated in a counter bore 66 in the upper end of the valve member 38, and the upper end of port 16 is experienced when the lower end of the second land portion 42 moves into registry with the portion of the cylinder Walls between the feed port 16 and the dow-through port 14. Thereafter, further downward movement of the movable valve member 38 gradually increases the ow restriction between the feed port 16 and the flow-through port 14 to produce a gradually modulated pressure within the feed port 16. Inasmuch as the lower edge of the rst land portion 40 is still a considerable distance from the upper edge of the control port body member 1) a sucient distance to permit its actul ation by means of a tiltable foot pedal structure adapted to abut the top edge of the plunger. Downward movement of the tiltable foot pedal structure 78 is therefore transmitted through the graduation spring 64 to the movable valve member 38 forcing the plunger 50 down- .1 f

'18, continued downward movement of the movable valve member 38 will now adjust the leakage paths between the feed port 16 and the flow-through port 14 while at the same time adjusting the leakage path from the feed port 16 to the exhaust port 20. Suitable modulated pressure within the recess 46 will thereforeY still be provided, even though back pressure is not being produced by the control valve 26. v

In order to provide a reaction against the foot of the operator which will apprise the operator of the amount of control pressure being developed by the valve,iand which will Iaid him in the proper positioning of the mov,- able valve member 38, pressure from the control port 18 is conducted to the bottom end of the plunger 50 by means of a drilled passageway 72 in the body member to 4cause* the plunger 50 to oppose the downward movement of the control member 38. reaction will, of course;

d be generally proportional to the pressure developed inthe control port 18 and can be made to be of any desired maximum intensity by properly sizing the diameter of the plunger. Upward movement of the movable valve member 38 will, of course, reduce the pressure in the control port 18, both during the times that pressure is, and during the time that pressure is not created [by the control valve 26; and a complete release of pressure against the foot pedal structure 70 will permit the coil spring 58 to move the lower edge of the first land portion 40 clear of the exhaust port to completely remove pressure from the brake applying wheel cylinders D and E.

As previously indicated pressure from the control port 18 is communicated to the outlet ports 30 and 32 by means of the second valve portion G2. The second valve portion G2 comprises a cylindrical chamber 74 into which the control port 18 communicates. The outlet ports 30 and 32 are positioned on opposite sides of control port 18 by a suitable distance, and a pair of exhaust ports 76 and 78 are positioned one on either end of the outlet ports 30 and 32. A spool valve 80 having opposite end land portions 82 and 84 is positioned within the cylindrical chamber 74 -for controlling flow in and out of outlet ports 30 and 32. The land portions 82 and 84 of the spool number 80 are spaced apart a dist-ance slightly greater than the distance between the outlet ports 30 and 32 such that the control port 18 will be communicated with both of the outlet ports 30 and 32 when the spool valve 80 is centered within the cylindrical chamber 74. Spool 80 is biased into its center position by means of a pair of identical opposing structures on either end of the spool, which include washers 86 seated against the bottom ends of counterbores 88 in opposite ends of the cylinder chamber 74, and which washers are biased inwardly towards their respective ends of the spool by means of coil springs 90 which are compressed and held into position by means of closure members 92 screwed into the outer ends of the counter bores.

Communication of the control port 18 with either of the outlet ports 30 or 32 can be prevented by suitable shifting the spool valve 80 endwise of its cylinder 74 until the cooperating land portion of the spool completely overlies the outlet port. The structure shown in the drawing for shifting the spool valve 80 comprises a lever arm 94 positioned in a suitable recess 96 in the body member 10, and one end of which is confined within a pair of flanges 98 on the spool member 80 while the other end is adapted to be rotated by shaft 100. Rotation of the shaft 100, therefore, causes the lever arm 94 to move the slide 80 endwise of its cylinder causing its land portions to close off the appropriate one of the outlet ports. The shaft 100 is journaled in a generally vertically extending drilling in thebody member 10 and is pivotally supported at its lower end by a ball 104 positioned between the bottom end of the bore 102 -and the lower end of the shaft 100.

The upper end of the shaft 100 extends Ibetween a pair of downwardly extending projections 106 on the bottom cf the foot pedal lever structure 70, andV is tiltably connected thereto by means of a pin 108 extending through the projections and through the top end of the shaft 100. It will, therefore, be seen that the foot pedal structure 70 is suitably supported for two degrees of movement-the first of which is a tilting movement which does not move the shaft 100 but actuates the first portion G1 of the valve, and the second degree of which provides a swinging action over the top of the cup-shaped plunger 68 which turns the shaft 100 to actuate the second portion G2 of the valve. It will therefore be seen that the foot pedal structure 70 can be used to simultaneously operate both portions of the valve, such that the tilting motion provides the desired controlled output pressure, while the swinging action of the operators foot distributes this pressure to either one of the brake appiying wheel cylinders D and escapes E. The centering structure provided on either end ofthe spool valve will normally hold the foot pedal structure 70 in its centered position, and in this position a tilting action of the pedal structure 70 will simultaneously deliver the control pressure to both wheel cylinders D and E to apply the same with equal intensity.

As a further renement in the structure forming the second portion G2 of the valve, the land portions 82 and 84 of the valve are made suciently thin such that continued rotation of the shaft after the position in which the outlet ports are valved off from the controlled pressure port 18, will cause the opposite edge of the lands 82 and 84 to move p-ast the outlet ports and open communication between the appropriate outlet port and the adjacent exhaust port 76 or 78. The pressure within the now opened outlet port 30 or 32 as the case may be, will therefore be immediately dumped.

In order to complete the ydescription of the structure shown in the drawing, the upper end of the bore 102 is slightly counter bored as at 110 to relieve leakage between the shaft 100 and its bore 102. The upper end of the counter bore 110 is provided with a suitable seal 112, and the counter bore 110 is communicated with the exhaust port 20 by the passageway 114. In order that the cup shaped plunger 68 will be retained within the upper end of the bore 12, a longitudinally extending groove 116 is milled into the outer edge of the cup shaped plunger 68, and the inner end of a set screw 118 is positioned in the groove to limit the extent of the plungers vertical movement.

While the preferred embodiment of the invention has been described in considerable det-ail, I do not wish to be limited to the particular constructions shown and described, and it is my intention to cover hereby al1 novel adaptations, modifications, and arrangements thereof, which come within the practice of those skilled in the art to which the invention relates as covered `by the following claims.

I claim:

1. In a control valve: a body member having a generally cylindrical chamber therein, a slide valve mounted for reciprocatory movement in said cylindrical chamber, said slide valve and chamber having spaced complementary land-and-groove portions of said chamber-and-valve dening therebetween an exhaust port means, a feed port means and how-through port means, said spaced complementary land-and-groove portions being proportioned to effect sequentially upon relative movement between `said slide valve and chamber a closing of said exhaust port means, restriction of communication between said feed port means and dow-through port means to effect modulation of pressure provided from said feed port means and thereafter separation of said how-through port means from said feed port means to develop back pressure from said feed port means, and control port means disposed between said exhaust port means and feed port means and having fluid connections with said exhaust port means in the normal position of said slide valve in said chamber' and with said feed port means `at operating positions of said slide valve in said chamber to receive said modulated pressure or back pressure from said feed port means.

2. The control valve structure in accordance with claim l including a movable Wall disposed at the end of said slide valve toward which the valve is moved to its operating positions and means to effect biasing effort on said valve for urging said valve to its normal position for communicating pressure from said control port means to said wall to balance input effort biasing said slide valve to one of its operating positions.

3. In a control valve: a body member having a generally cylindrical chamber therein whose sidewalls haveA an exhaust port, a controlled pressure port, a feed port, and a flow through port; a slide valve in said chamber constructed and arranged for reciprocatory movement relative to said ports; said slide having first and second land portions having a generally predetermined t with respect to said sidewalls, said land portions being separated by -a recess to form a terminating` side edge, for the. first land portion and a beginning side edge of the second land' portion, said second land portion also having a ter-y minating side edge on its opposite end; said recess having a width which is less than the distance between said exhaust yand feed ports by a lirstl generally predetermined amount, and said second land having a Width which is. ljess. than lthe width of said feed port by asecond generally predetermined -amount which is less than said irst generally predetermined amount, said slide having a normal position wherein the terminating side edgefof saidr rst land portion is positioned open with respect to the edge of said exhaust port by a first generally predetermined distance, said beginning.V side edge of sai'd second land portion is spaced from said feed' port by a second generally predetermined distance, andthe terminating side edge of said second land portion is spaced open with respect to said feed port by a third generally predetermined distance, said third' distance being greater than said' second distance which in turnis greater than sai'd first' distance, whereby movement of said slide in the direction of'said ow through port sequentially closes olf said ex'- haust port to pressurize said controlled pressure port, thereafter modulates the pressure in said control; Port if' pressure is available in said feed port, and thereafter separates said ow through port from said feed port to develop back pressure in said feed port ifY none previously existed.

' 4. ln a control valve: a body member having a generally cylindrical chamber therein whose sidewalls have an exhaust port, a controlled pressure port-,I a feed port, and a flow through port positioned in that order between upper and lower ends of said chamber, a slide valve in said chamber constructed and arranged for reciprocatory-I movement relative to said ports; said slide having upper and lower land portions having a generally predetermined fit with respect to said sidewalls, said land portions being separated by a recess to form a terminating sideedge for the, upper land portion and a beginning side edge of the lower. land portion, said lower land portion. also having a terminating side edge on its opposite. end; said recess having a width which is less than the distance between said exhaust and feed ports by a rst generally predetermined amount, and saidsecond land having a Width which is less than the width of said feed port by a second generally pre1 by a second generally predetermined. distance, and the terminating side edge of said lower land portion is. spaced open with respect to the lower side edge of said feed, port by a third generally predetermined distance, said third dis;-

tance being greater than said second distance which inV turn is greater than said first distance, whereby downward movement of said slide sequentially closes oit. said exhaust portv to pressurize said controlled pressure port, thereaftermodulates the pressure in said control port if:preS- sure is available in said feed port, and thereafter separates:

saidY flow through port from said feed port to develop hack presure in said feed port if none previously existed, andexpansible means positioned against the lower end of Said slide valve and supplied with pressure from said control port to aid in the positioning of said slide valve.l

5. lIn a control valve constructed in accordance with claim 4 an outlet valve formed by a cylindricalv outlet valve chamber in saidbody mem-ber, said controlledpressure port opening into said outlet valve chamber,`said body member also having first and second outlet ports in' said outlet chamber positioned on opposite sides of Said*v controlled pressure port, an outlet valve spool in said outlet chamber having n t or second lands spaced apart a distance greater than the distance between said outlet ports, and means for moving said` spool to closev off one or the other of said outlet ports while adjusting said slide valve to control the pressure in said outlet ports.

6. In. a control valve constructed in accordance with claim 4 an outlet valve formed by a cylindrical outlet valve chamber in said body member at substantially right angle to said rst mentioned chamber, said controlled pressure port opening into said outlet valve chamber, said body member also having first and second outletv ports in said outlet chamber positioned on opposite sides of said controlled pressure port,v anvv outlet valve spool in said outlet chamber having irst or second lands spaced apart a distance greater than the distance ybetween said outlet ports.

7. In a control valve: a body member having a longi-v tudinal chamber of generally uniform cross-section,y said chamber having a pressure port,` a controlled pressure port, and an exhaust port arranged in that order Vin the sidewalls thereof; a slide valve in said longitudinal cham- -ber constructed and arranged for reciprocatory move- -ment relative to said ports, said slide valve having rst and second land portions having a generally predetermined flt with respect to said sidewalls; said slide being so constructed and arranged that said first land portion overles at least a portion of said sidewalls between said exhaust and controlled pressure ports, when said second land portion overlies at least a portion of said sidewalls between said controlled pressureY port and said pressure port; said rstand second land portions having sucient axial length so that axial movement in o ne directionY increases the amount of sidewall area between said pressure and controlled pressure ports lapped by said second land portion while at the same time decreasing-the amount of sidewall between said controlled pressure and exhaust ports that is lapped by said rst land portion; an outlet valve chamber in said body, said controlled pressure port opening into said! outlet valve chamber; said body mem-- lber also having first and second outlet ports in said outlet chamber positioned on opposite sides of said controlled pressure port; an outlet valve spool in said outlet chamber having first and second lands spaced apart a distance greater than the distance between said outlet ports; and means for moving said spool to close oi one or the other of said outlet ports, whereby the variable leakage rates provided by said slide valve assures smoothY application of control pressure to either of said` outlet' ports during actuation of said spool-valve, a shaft extending generally parallel with respect tol said slide valve, an arm connected to said shaft for transferring rotary movement of said shaft to said outlet valve spool anda pedal member non-rotatably connected to said shaft for turning`` said shaft, said pedal member also being tiltable relative to said shaft for producing movement of said slide valve longitudinally of its chamber, whereby the amount of pressure developed by said valve is determined by the tilting of said pedal member and the outlet port to which it is directed is controlled by turning of the pedal member. 8. In a control valve for modulating a pressure to one.

or both of a pair of outlet ports: a body member having'.

a rst valve chamber which communicates a pressure inlet port, an exhaust port, and a control port, saidV body member having a second valve chamber extending generally atv right angles toV said first valve chamber, said second valve chamber havinga pair of outlet ports, and

an inlet port communicating with said control port of ports; a sha-ft rotatably mounted generally parallel to said rst Valve chamber, a treadle pinned generally transversely to said shaft, means actuating said second Valve means by rotation of said shaft, and means actuating said rst valve means by tilting movement of said treadle about said pinned connection between said treadle and shaft; whereby modulated pressures intermediate that in said pressure and exhaust ports can be supplied to one or the other of said outlet ponts by vappropriate movement of said ltreadle.

References Cited in the tile of this patent UNITED STATES PATENTS Maxon Oct. 2, 1894 Gibson June 17, 19'30 Douglas Ian. 9, 1934 Lapsley et al June 30, 1953 Dorkins Apr. 12, 1955 Gold et al July 9, 1957

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