US2366119A - Fluid pressure control device - Google Patents

Description

Dec. 26, 1944. L. A. MAJNERi 2,366,119

FLUID PRESSURE CONTROL DEVICE Filed'Sept. 14, 1942 2 Sheets-Sheet 1 INVENTOR.

LUDWIG AL MAJNERI ATTORNEYS Dec. 26, 1944.

2 Shets-Sheet 2 Filed Sept. 14, 1942 INVENTOR. LUDWIG AMAJNE'RI ATTORNEYS vide an improved fluid Patented Dec. 26, 19,44

Ludwig A. Majneri,

to The Warner Grosse Pointc, Mich, assignor Aircraft Corporation, Detroit, Mich., a corporation of Mic higan,

{\pplication September 14, 1942, Serial No. 458,264 9 Claims. (01. GO- 54.6)

The invention relates to fluid pressure control devices andrefers more particularly to fluidpressure control devices for hydraulic brakes.

The invention has for one of its objects to propressure control device of the compound type having a low pressure producing means and a high pressure producing means adapted to operate successively in produc; ing fluid pressure.

The invention has for another of its objects to provide an improved mechanism for control ling thechange-over from the effective operation of the low pressure producing means to the eifec tive operation of the high pressure producing means during the advance or pressure stroke of the device.

The invention has for other objects to provide the change-over controlling mechanism with a valve .and with adjustable means for controlling the movement of the valve; to provide the change-over controlling mechanism with means for limiting movement of thevalve tosecure approximately the same effective advance or pressure stroke regardless of the speed of advanc'e; to provide the change-over controlling mechanism with means for resiliently opposing movement-of the valve in a manner to approximately compensate for difierent brake characteristics; to provide the change-over controlling mechanism with means for opposing movement of the valve approximately in accordance with "the viscosity of the fluid; and to provide the change-over controlling mechanism with a plunger for operating the valve and with means engageable with the plunger to oppose a resistance to its movement.

The inventionhas for further objects to provide a fluid pressure control device in which the low pressure producing and the high pressure producing means comprise low pressure and high pressurecylinders and pistons slidable within the cylinders and adapted to be directly moved from position by a piston rod which serves to conductfluid from the high pressure cyl nder to hold a valve in open position and thereby allow fluid in the low pressure cylinder to flow to a reservoir,

In the drawings:

Figure l isa vertical central section through a fluid pressure controldevice embodying my invention; i v i v Figure 2 is a similar viewshowing the parts in a different position during the operation of the device; 7 Figures 3 and 4 are cross sections'on the lines 3-3 and 4-4, respectively, of Figure 1;

Figures 5 and 6 are; views similar to Figures 1.

and 2, respectively, showing another embodiment of the invention;

Figure 7 is a viewsimilar to aportion of Figure 1 showing another embodiment of the invention. The fluid pressure controldevice is particularly applicable to a hydraulic brake system of an. airplane, but it is apparent that the devicemay be used with other hydraulic brake systems, While the devices, as shown, do notfincorpdrate the A parking features of my Patent No. 2,115,174, issued April 26, 1938, or my Patent No; 2,120,073, issued June 7, 1938, the parking features maybe readily incorporated in accordance with "the teachings of the patents.

The fluid pressure control device generally comprises highpressure producing means, low pressure producing means, a reservoir, and mechanism for controlling the change-over from the efiective operation of the low pressure producing means tothe effective operation'of the'high pressure producing means during the advance or pressure stroke of the device. As illustrated, the dewhereby the low pressure cylinder isrelieved; and

vice occupies asubstantially vertical position and comprises a highpressure chamber inits lower portion, a low pressure chamberabove the high pressure chamber, and a reservoir above the low pressure chamber and in the upper portion of the device. The high pressure chamber is adapted to d scharge fluid under pressure, through a discharge port which is adapted. to be connected by tubingto a wheel cylinder for actuating a brake. The low pressure chamber is adapted to discharge fluidunder pressure to the high pressure chamber until a predetermined pressureof fluidin the low pressure chamber iscreated, at which time the change-over controlling mechanism places the low pressure chamber in communication with the V reservoir. Then when a predetermined pressure;

of fluid in the high pressure chamber is created, the fluid in the highpressure chamber operates upon the change-over controlling mechanism to hold the low pressure chamber'incommunication the low pressurechamber. I

Referring to Figures 1 to 4, inclusive, the fluid with the reservoir independently of the fluid in (not shown).

' from the reservoir past the fitting.

pressure. control device has the lower high pressure cylinder the upper low pressure cylinder 2 of larger diameter-than the high pressure cylinder, and the braking fluid reservoir 3 above the low pressure cylinder. The fluid pressure -contro1 device also has the high pressure and low pressure pistons 4 and 5, respectively, slidinder for actuating a brake by the usual tubing The reservoir 3 is closed at its upper end by'the upper end fitting |l fixedly secured to the reservoir. The fitting has the depending annular flange l2 which is preferably threaded into the reservoir and which is provided with the external annular groove l3 and the radial passageways 4 leading from the groove to the chamber within the annular flange. The groove opens into the port l5 which i adapted 'to be connected to an. auxiliary braking fluid reservoir. |6is a sealing ring above the annular groove for preventing the leakage of braking fluid Thepiston rod 6 is constructed to be pivotally connected to a suitable foot pedal for longitu dinally moving the piston rod downwardly to operate the control device; The fitting H is provided with a suitable bushing l1 for engaging a 'pivot'pin of a suitable support.

The lower high pressure piston 4 has the annular head l3 slidable within the high pressure cylinder I and the upwardly extending sleeve l9 formed of the reduced portion and the enlarged portion 2 The upper end of the reduced portion has the annular valve seat 22 and the lower end of the enlarged portion has the transverse ports 23. The piston rod 6' slidably extends through the annular head and sleeve. The high pressure piston also has the annular sealing cup 24 preferably formed-of rubber and provided with concentric lips for slidably engaging the wall of the high pressure cylinder and the piston rod 6. Thehead I8 is formed withthe transverse ports 25 for permitting the flow of the braking fluid from the low pressure cylinder to the high pressure cylinder. A resilient thin sheet metal disc 24' is preferably provided between the head I 8 and the sealing cup 24 to prevent the latter from being forced'into the transverse ports 25. Also a circular cross sectioned ring 24" preferably formed of rubber is preferably provided between the head I8 and the piston rod 6 to prevent the flow of the braking fluid therebetween- During the flow of the braking fluid from the low pressure cylinder to the high pressure cylinder through the transverse ports both the resilient disc and the sealing cup are flexed. The low pressure piston 6 has the body 26 and the annular head 21 which are fixedly secured to the upper end of the enlarged portion 2| of the sleeve of the high pressure piston. As shown, the-body 26 is threaded into the upper end of the enlarged portion 2| and has the annular flange "which extends over and clamps the annular head 21 against the annular The is closedat its lower end high pressure cylinder by suitable means and, as ,shown,' is threaded at 3 into the high pressure cylinder- The high pressure cylinder is provided.- near its lower end with the discharge port l0 which is adapted to be connected to a wheel cylv of shoulder 23 formed on the enlarged portion 2|.

I preferablyprovide the sealing ring 30 between the annular flange and head. The low pressure piston also has the flanged sealing ring 3| preterably formed of rubber and abutting the lower side of the head 21 and provided with an outer lip which slidably engages the wall of the low pressure cylinder 2. The sealing ring is clamped by the head 21 against the annular shoulder 32 formed on the enlarged portion 2| of the sleeve of the high pressure piston. The head 21 is formed with the transverse ports 33 for permitting the flow of braking fluid fromthe reservoir to the low pressure cylinder, during which time the sealing ring 3| is flexed.

The piston rod 6 has at its upper end the enlarged cup-shaped portion 34 which i located within the enlarged portion 2| of the high pressure piston sleeve. The bottom of the cup-shaped portion is provided with the annular ring 35 preferably formed of rubber and constituting a valve which is adapted to seat on the valve seat 22. The piston rod is provided with the. axial passageway 36 and the radial passageways 31 and 38 leading from the axial passageway, the'passageways 31 being below the sealing cup 24 and the passageways 38 being immediately below the valve 35. 39 is a retractingcoil spring, 'for resiliently holding the piston rod 6 in its of! position. This coil spring abuts the sealing cup 8 and the annular shoulder 40 formed upon the annular wall 4| of the cup-shaped retainer 42. The retainer is held from upward movement relative to the piston rod by suitable means, suchas the cwasher 43 within the retainer and engaging an annular groove in the piston rod. To prevent sticking of the sealingcup 24 during the return is slotted so that the axialipassageway of the piston rod is always in communication with the high pressure cylinder. 44 .is a second retracting spring located betweenthe low pressure piston and the piston rod for resiliently holding both'the low pressure piston and the high pressure piston in their off position. As shown, the retracting spring 44 is a coil spring abutting the body. 26

of the low pressure piston and the nut 45 which is threaded into the upper end of the enlarged .cupshaped portion 34 of the piston rod.

With the parts as thus far described, the high pressure piston and the low pressure piston are fixedly connected to each other and move in unison. Downward movement of the piston rod.6 v

through its valve 35 abutting the seat 22 advances both pistons and the'piston rod and both pistons and the piston rod are adapted to be retracted to their off position by the coil springs .39 and 44. The coil spring 39 acts upon the piston rod to retract the same and the coil spring 44 acts upon the pistons to retract the same. The off position of the pistons is determined by abutment of the annular head 21 of the low pressure piston with the lower end of the annular flange |2 of the upper end fitting while the ofi position of the piston rod is determined by the change-over controlling mechanism which is later described and which positions the piston rod relative to the pistons so that the valve .35 is spaced from the valve seat 22, at which time the high pressure cylinder is in communication with the low pressure cylinder. It will be noted that during the advance of the pistons braking passageways fluid is discharged from the low pressure cylinder into the high pressure cylinder through the ports 25 and past the resilient disc 24' and the sealing cup 24 and that during the retraction of the pistonrod and pistons brakingfluid may pass from the high pressure cylinder to the low pressure cylinder through the passageways 31, 35 and 35 of the piston rod between the separated valve 35 and seat 22 and through theports 23 in the high pressure piston sleeve. Braking fluid may also pass from the reservoir to the low pressure cylinder through the ports 33 in the head 21 of the low pressure piston and past'the sealing ring 3|. a

To relieve the fluid pressure in the low pressure cylinder during the advance or pressure stroke of the fluid pressure control device. I have i provided a change-over controlling device for placing the low pressure cylinder in communica- .tion with the reservoir. The mechanism is first operated by the fluid in the low pressure cylinder to open the communication and then operated by the fluid in the high pressure cylinder to hold the communication open, thereby completely relieving the fluid in the low pressure cylinder from pressure except that of the hydraulic head of the fluid in the reservoir. g

In detail, the body 25 of the low pressure piston is annular and provides an axial passageway 45 therethrough, the uper portion of which is nlarged. The upper portion of the annular flange 25 of the body is provided with the aligned radial grooves 41 forplacing the enlarged portion ofthe axial passageway in communication with the reservoir. To place the reduced port on of the axial passageway in communication with the low pressure cylinder,

I have provided the radial high pressure piston sleeve and the external annular groove 49 in the body 25 registering with the radial passageways 48 and also the radial passageways 50 in the body 25 leading fr m the annular groove to the axialpassageway. is a ball valve within the enlarged portion of the axial passageway 46 and adapted to seat up n the annular seat 52 which is formed in the body 25.

For unseating the ball valve or raising it from its seat, I have provided the plunger 53 having its upper end engageable with theball valve and ring within the cup-shaped enlargement 34 and having its base held against the nut 45 by the spacer 55. The sealing ring is channel-shaped 48 in the enlarged portion 2! of the in cross section and has an outer lip engaain' the annularwall oi the cup-shaped enlargement 34 and an inner lip engaging the plun er 53 which extends through and slidablyen ages the nut 45. The length of the plunger 53 is such that when the piston rod and the pistons are in oil? position the piston rod abuts the lun er and it, in *turn, abuts the ball valve and holds the same 01f its seat. However, as soon as the piston rod is advanced to engage its valve 35 with the valve seat 22 the plunger is loweredandthe ball valve engages its valve seat.

4 For guiding and controlling the movement of me a depending annularflange extending freely within the enlarged portion or the axial passage way 45 of the low pressure piston and encircling the ball valve 5| and having its body engageable with the ball valve. The bottom 01' the plunger is resiliently held against the ball valve bythe coil spring 51 which at its lower'end abuts the yoke or bar. 55 secured to the plunger as by ex-.

tending diametrically .therethrough in registration with the grooves 41. The upper end of the coil spring abutsthe collar 55 which is mounted 0n the,,annular flange 54, which latter extends upwardly from the annular body 25 of the low pressure piston and, more particularly, the annular flange 25 01' the body. Thecollaris, ad- Justably threaded on the annular flange to allow change of pressure of the spring for resiliently holding the ball valve in closed position to there.- by approximately compensate-tor the diiier'ent,

characteristics of the various brakes with which the fluid pressure control device may be used so that uniform braking action maybe secured- To oppose movement of the ball valve approximately in accordance withqthe viscosity of the braking.

fluid, the plunger 55 is constructed to cooperate with the cylinder 5| in a manner to effect a dashpot action. The plunger slidably engages the cylinder and, as shown, is provided with the series of passageways 52 extending longitudinally through the body. To limit the movement of the ball valve to secure approximately the same ei'-.

fective advance or pressure stroke of thepfitnns regardless of the speed of advance, the "dashpot cylinder 5| is formed with the annular stop 52 a which is engageable with the upper end of the plunger. The cylinder is adjustably mounted on' v the low pressure piston as by being threaded into the annular flange 50. To locktthe collar 59 and the dashpot cylinder 5]. in their various adjusted positions, I. preferably longitudinally slot thean- I nular flange 50 in' registration with the radial grooves 41, longitudinally slot the upper end por-.

tion of the dashpot cylinder 5| and form penings in the collar 58 to receive a lock wire 54. The

coil spring 51 is ofa strength suiflcient to hold the ball valve 5| to its seat 52 against the effort exerted by the braking fluid in the low pressure cylinder 2 until a pressure of the braking 'fluid predetermined by the adjustment of the collar 4 59 is created. However, the strength of the coil pressure control device so that the coil spring; I

ball valve to become unyields,to permit the seated. l 4

It will be noted.- that the .011 position of the piston rod 5 is determined by the dashpot cylinder 5! which is adjustably carried by the low pressure piston 5. The dashpot cylinder 51 abuts the dashpot plunger 55, which isengaged by the ball valve 5|, which latter in turn is engaged by the plunger 53 by means of the retracting spring 39.

Assuming the parts to be in the oil position,

as shown in Figure Lthehigh pressure cylinder I is in communication with the low pressure cyl' inder 2 and the low pressure cylinder 2 is in communication with the reservoir 3. Upon downward pull of the piston rod 6, its valve 35 will seat upon the valve seat 22 to close communicaheld upwardly by the piston rod Iowpressurecylinder 2 through'the piston rod. Atvthe-sametime, the. spring 51 seats the ball valve-51 upon its seat 52to close communication between the --low pressure-cylinder. land the reservoir. 3;: Continued downward movement of the piston rod-'6' compels the high pressure piston 4 and the low pressure piston 5 to move. downwardly in unison during, which time the braking fluidunder pressure is-forced from the low pressure-cylinder [through the ports 25 and past the resilient 1disc;.24 andsealing cup 24 into the high pressurecylinder l and the braking fluid in the latter cylinder is discharged through the discharge port .16; However, when-pressure of the braking-fluid withinthe low pressure cylinder 2 reaches a. predetermined point, the braking fluid. 'in=the1lcwpressure cylinder unseats the ballvalve 5|, thereby placing the low pressure cylinder in :communication with the reservoir 3.

'Then. when the pressure .of the braking fluid withinthe high pressure cylinder I reaches a higher predetermined point the braking fluid withinthe axial passageway 36 in the piston rod acts-upon the plunger 53 to hold the same against the ball 5| inopen position, thereby completely relieving the braking fluid in the low pressure cylinder'from pressure except that of the hydraulic head of the braking fluid in the reservoir. Theunseating of the ball valve 5| takes place against the effort exerted by the coil spring 51and .the resistance offered by the dashpot cylinder'li I and dashpot plunger 56. The sealing ring 54 opposes frictional resistance to the unseating movement of the plunger 53 to hold the plunger from movement until the pressure of the braking fluid in the high pressure cylinder is higher than the pressure of the braking fluid in the low pressure cylinder when the ball valve is moved to open position. The unseating movementof the ball valve is limited by the stop 63 of the'cylinder engaging the plunger. At this time I the parts are inthe position indicated in Figure 2 and the fluid pressure within the low pressure cylinder 2 is relieved by reason of the low pressure cylinder being placed in communication with the reservoir. As a result, continued downward movement of the piston rod causes the high pressure piston only to discharge braking fluid through the discharge port. When the piston rod is released, the coil springs 39 and 44 act to return the piston rod and the pistons, respectively, to their off position.

With the construction as shown, the plunger.

53 is movedagainst the ball valve 5| when the pressure of the braking fluid in the high presthe high pressure piston and the low pressure piston, preferably by having a press fit with the 'reduced portion H of the sleeve 12 of the high pressurepiston and also by having the integral enlargement 13 abutting an annular shoulder formed at the upperend of the reduced portion H and held in-engagement therewith by the sealing cup" and the annular spacer 15. The uption'between' the high pressure cylinder l and the per end of the spacer is abutted by the annular body I of the low pressur piston. The constructio of the device for relieving the fluid pressure in the low pressure cylinder 69 is the same as that of Figures 1 to 4, inclusive, with the exception that the plunger 11 for unseating the ball valve is of a length such that the ball valve is seated when the parts are in off position. There is but one retracting coil spring 18 which operates upon the piston rod to return the piston rod and the pistons to their off position.

In the off position of the parts, as illustrated in Figure 5, the high pressure cylinder 66 is in communication through the passageways 65 with the low pressure cylinder 69 and. the low pressure cylinder 69 is in communication through the passageways 68v with the reservoir 19. The

. ball valve is seated to close the communication between the low pressure cylinder and the reservoir through the low pressure piston.

the ball valve is unseated by the braking fluid in the low pressure cylinder and then when a higher predetermined pressure of the braking fluid in the high pressure cylinder is reached, the braking fluid in the high pressure cylinder acts upon the plunger 11 to move the same upwardly to hold the ball valve in open position, at which time the low pressure cylinder is completely relieved from fluid pressure except that of the hydraulic head of the braking fluid in the reservoir. movement of the piston rod the high pressure piston 64 acts only to discharge the braking fluid. as illustrated in Figure 6.

Figure '7 illustrates another modification which differs essentially from the modifications of Figures 1 to 4, inclusive, and Figures 5 and 6 in forming the upper end of the piston rod with the annular flange 8| for directly slidably engaging the plunger 82 for unseating the ball valve. In this case, a suitable sealing ring 83 is provided in an annular groove in the plunger 82 for engaging the annular flange 8| to prevent the escape of the braking fluid through the axial pas-' sageway in the piston rod and between the plunger-and the annular flange. This sealing ring also functions in the same manner as the sealing ring 54 to oppose frictional resistance to the unseating movement of the plunger.

What I claim as my invention is:

1. A fluid pressure control device comprising a cylinder having a discharge port, a second cylinder of larger diameter than said first mentioned cylinder, a fluid reservoir, a piston slidable in said first mentioned cylinder, a second piston slidable in said second cylinder and movable with said first mentioned piston, said second piston having a passageway therethrough for placing said second cylinder and reservoir in communication. a valve movable relative to said second piston for closing said passageway, a piston rod for directly advancing said pistons from off position, said piston rod being movable axially relative to said first mentioned piston and having a passageway Upon downward pull on the pistonrod 10, the pistons As a result, during continued downward a means between a resistance to a high pressure 2,866,119 I for placing said cylinders incommunication and said low pressure chamber, said mech a valve engageable with said flrstmentloned piscomprising a valve movableby the fluid in said ton to close said last mentioned passageway and one or said chambers, a dashpot plunger engageto directly move said pistons from off position,

and a plunger engageable with said flrst mentioned valve in the off-position of said piston rod to hold said first mentioned valve in open position, said plunger also being movable relative to said piston rod during the advance of the latter to permit said flrst mentioned valve to move to closed position and then to hold said flrst mentioned valve in open position under the fluid pressure created in said flrst mentioned cylinder.

2. A fluid pressure control device comprising a high pressure cylinder, 9. low pressure cylinder, a reservoir, high pressure and low pressure pistons in said high pressure and low pressure cylinders, respectively, vancing said pistons a piston rod for directly adfrom oil position, said piston rod having a passageway in communication with said high pressure cylinder, said low pressure piston having a passageway therethrough forplacingsaid low pressure cylinderin communication with said reservoir, a valve for controlling said last mentioned passageway, a plunger engageable with said valve and extending within said piston rod and subject to the pressure of the fluid within said piston rod, passageway, and the side of said plunger and the encircling portion of said piston rod imposing the movement of said plunger.

3. A fluid pressure control device comprising cylinder, a low pressure cylinder, a reservoir, high pressure and low pressure pistons in said high pressure and low pressure cylinders, respectively, a piston rod for directly ad vancing said pistons'from off position, said pistn rod having a passageway in communication with said high pressure cylinder, said low pressure piston having a. passageway therethrough for placing said low pressure cylinder in communication with said reservoir, a valve for controlling said last mentioned gageable with said said piston rod and subject to the pressure of the fluid within said piston rod passageway, and a sealing ring between the side of said plunger and the encircling portion of said. piston rod frictionally engaging said plungen 4. A fluid a high passageway, a plunger ensaid valve.

5. A fluid pressure control device comprising a high pressure chamber having a discharge port, a low pressure chamber for discharging fluid into said high pressure chamber, a reservoir, and a mechanism for placing said low pressure chamber in communication with said reservoir when a predetermined pressure is created within one ,of said chambers to relieve the fluid pressure in valve and extending within pressure control device comprising pressure chamber having a discharge port, a low pressure chamber for discharging fluid into plunger engageable able with said valve, an adjustable dashpot cyling movement of said plunger.

, movement of said valve, said controlling means 6.'A fluid pressure control device comprising a high pressure cylinder, a low pressure cylinder, a reservoir, high pressure and tons in said high pressure and low pressure cyl-V inders, respectively, said low pressure piston having a passageway therethrough, a valve for controlling said passageway, means operable by the fluid in said high pressure cylinder for holding said valve in open position, a dashpot plunger controlling movement of said valve, a dashpot cylinder mounted on said low pressure piston and within which said plunger is slidable, and spring means mounted on said low pressure piston for resiliently resisting movement of said plunger.

7. A fluid pressure control device comprising pressure cylinder, areservoir having an opening,;a closure member for the opening detachably secured to said reservoir, high pressure and low pressure pistons in said high pressure and low pressure cylinders respectiveiy, and mechanism for placing said low pressurefcylinder in communication with said reservoir when a predetermined pressure is created in one of said cylindersto relieve the fluid pressure in said low pressure cylinder, said mechanism comprisingv a valve movable by the fluid in said one of said cylinders, a dash pot plunger engageable with said valve, a dash pot cylinder within whichsaid plunger is slidable, said cylinder being adjustably mounted on said low pre'ssurepiston, and spring means resisting movement of said plunger, said spring means also being adjustably mounted on said'low pressure piston, said dash Dot, plunger, dash pot cylinder and spring means being located within said reser voir for ready accessibility through the opening when said closure member is detached. I

8. A fluid pressure control device. comprising a high pressure cylinder, a low pressure cylinder, a reservoir, high pressure tons in said high pressure and low pressure cylinders respectively, said low pressure piston having a passageway therethrough for placing said low pressure cylinder in communication with said reservoir, a valvefor controlling said passageway, said valve being movable to open position by the fluid in one of said cylinders, and

means independent of the flow of fluid through said passageway for controlling the opening comprising a dash pot plunger engaging said valve and a dash pot cylinder slidably receiving,

said dash pot plunger.

9. A fluid pressure control device comprisingi low pressure producing mean and high pressure in said low producing means, a valve for relieving pressure of fluid in said low pressure producing means upon the attainment of a predetermined pressure pressure producing means, adjustable spring mean resisting movement of said valve,

and stop means adjustable independently of said spring means for limiting movement of said valve.

/' LUDWIG A. MAJNERI.

low pressure piss I and low pressure pis-

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