US2759455A

US2759455A - Hydraulic power system

Info

Publication number: US2759455A
Authority: US
Publication date: 1956-08-21
Anticipated expiration: 1973-08-21

Description

Aug. 21, 1956 F. H. KIND HYDRAULIC POWER SYSTEM 5 Sheets-Sheet 1 Filed April 22, 1954 1956 F. H. KIND HYDRAULIC PQWER SYSTEM 3 Shets-Sheet 2 Filed April 22, 1954 U U H Aug. 21, 1956 K 2,759,455

HYDRAULIC POWER SYSTEM Filed April 22, 1954 v 3 Sheets-Sheet 3 IN V EN TOR.

United States Patent HYDRAULIC POWER SYSTEM Frederick H. Kind, Racine, Wis., assignor to Racine Hydraulics & Machinery Inc., Racine, Wia, a corporation of Wisconsin Application April 22, 1954, Serial No. 424,979

8 Claims. (Cl. 121-20) This invention relates to a hydraulic system and more particularly to a high speed reversible hydraulic power system embodying a new and improved reversing valve mechanism.

A general object of the invention is to provide a new and improved hydraulic power system embodying a reversing valve mechanism and a high speed hydraulic tamping machine, hammer or other work device having a cylinder provided with a piston to be rapidly reciprocated.

Another object is to provide a hydraulic system embodying a source of hydraulic fluid under pressure, a tool having a piston and cylinder device, the piston being spring urged in one direction and intermittently hydraulically driven in the opposite direction, a reversing valve for controlling the supply of fluid to one end of the cylinder and the return of it therefrom through a plurality of conduits in parallel between the valve and cylinder, and means for causing intermittent progressive movement of the fluid in one conduit towards the cylinder and in another conduit away from the cylinder to prevent the fluid from over-heating.

Another object is to provide a new and improved-reversing valve mechanism embodying a main valve for controlling fluid flow to and from a work piston, and a shiftable pilot valve for controlling reciprocation of the main-valve, the shifting movement of the pilot valve'b'etween operative positions being initiated by and during movement of the main valve to'facilitate maximum utili zation of hydraulic power for causing rapid reciprocation of the main valve and-work piston.

Another object is to-provide a'valve mechanism of the type described above embodying a main valve, spring urged in one direction and-hydraulically driven in the reverse direction, and a shiftable pilot valve for controlling the hydraulic movement of the main valve, the pilot valve being mechanically connected to the main valve and releasably held in operative positions by a detent device-of a load andfire device prior to being rapidly shiftedbythe load and firedevice actuated by and during the main valve movements.

Another object is to provide a valve mechanism of the type described above provided with means for varying the rate of reciprocation of the main valve.

Further" objects and advantages will become apparent from the following detailed'description taken in connection with the appended'drawings'in which:

Fig. 1 is a view of a preferred form of'theinv'en'tion showing a system with the valve and a work device in central section'andwith the parts in the positions assumed when the main valve connects the work device to a source of hydraulic fluid under pressure and just prior to the shifting of the main valve into the position illustrated in Fig; 2; I

Fig. 2 is a view similar to Fig. l'but showing the relation of'the' main valve, pilot valve'an'd work device parts when themai'n valve isposition'e'd' for connecting the 2,759,455 Patented Aug. 21, 1956 2 work device to drain just prior to the shifting of the main valve into the position illustrated in Fig. 1;

Fig. 3 is an elevational view of the reversing valve looking at the right hand end of the valve in Fig. 1; and

Fig. 4 is a sectional view taken along line 44 of Fig. 1.

While this invention is susceptible of embodiment in many diflerent forms, there is shown in the drawings and will be herein described in detail an illustrative embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

In the preferred embodiment of the invention illustrated in the drawings, a reversing valve, generally desigdated 10 is connected in a system comprising a hydraulic fluid source 11, a pump 12, and a work device in the form of a tamping tool 15.

The tamping tool embodies a casing 16 having a cylinder 17 therein communicating at it'sup'per or pressure end 18 with a pair of conduits 13 and 14 which extend in parallel arrangement to the reversing valve. A piston 19 is slidable in the cylinder and is continuously urged to wa'rd the pressure end 1 8 by a coiled sprin'g' 20"positioned in the lower end of the cylinder. A cylindrical piston rod 21 fixed to the piston,- is slidable in a bore 22 in the casing and has a free end 23 operable as a hammer for intermittently striking a tool member 24' slidable in a bore 25 in the lower end of the casing.

The valve 10 is adapted alternately to'adniit hydraulic fluid under pressure tothe upper end 18 of cylinder 17 to drive the piston downwardly to cause a hammer-like blow of the rod 21 against the tool member 24, and to permit return flow of the fluid out of the cylinder as the spring 20 returns the piston upwardly in cylinder 17.

As shown'in Figs. 1 and 2, the valve 10 comprises a casing having a central part 26, a' left end" plate 27 and a right end member 28; A cylindrical main valve member 29 is slidably positioned in a cylindrical sleeve 30 fixed in a main valve bore 31 H Main valve member 29 is provided with

lands

32, 33 and34 defining annular grooves 35' and-SG'therebetweenL A plurality of ports 37-, 38 and 39 in the sleeve 30con= nect with annular grooves 41', 42 and 43' in" the central part-26 of the casing. An annular casing groove 40 surrounds the left' hand end of the sleeve 30 and connects with an annular passage 40' which, as described hereinafter, communicates with a drain line leading to the-source 11. A passage 44 in the casing communicates with the conduits 13 and 14 and with'the gro'ove42' which turn is in constant communication with sleeve port 38. An inlet-passage 45 in the casing communicate's with annular groove 43 and is also shown connected to the pump 12 by a conduit 5. A passage 46in the casing communicates with annulargroove 41' and is also shown connected to the source 11- by a drain conduit 6; A conduit 7 extends from the source 11' to the inle't of the pump 12.

Rapid reciprocation of the-main valve member 29"between a forwarder in'let position as illustrated in Fig. 1 and a reverse or drain position as shown in Fig.- 2 alternately connects'tool 15 to a sourceof hydraulic fluid under pressure or to drain toimpart arapid reciprbcato'ry motion to hammer 23 and tool=member 24; When the main valve member 29 is inthe inlet position (Fig. 1) the upper end 18 of the tool cylinder 17 is suppliedwith fluid under pressure flowing from the'pump 12 through conduit 5, inlet passage 45, groove 43, ports 39, groove 36, port 38, groove 42, passage 44 and parallel conduits 13 and 14 and the piston 19 is driven rapidly down against the force of spring 20. The main valve member,

3 when in the drain position shown in Fig. 2, connects the upper end of cylinder 17 to drain; thus allowing spring 20 to move piston 19 upwardly in the cylinder to force hydraulic fluid back through conduits 13 and 14, passage 44, groove 42, port 38, groove 35, ports 37, groove 41, drain passage 46 and conduit 6.

Preferably annular rubber collars 47 are positioned on bosses 48 and 49 on the casing end plate 27 and end member 28, respectively, to stop and cushion the main valve member at the ends of its strokes when reciprocated as hereinafter described.

The main valve member 29 is spring urged to its drain position as shown in Fig. 2 by means of a coiled spring 51 which is compressed between the boss 48 and a transverse wall 50 in the valve member. At its left hand end the spring is supported by a tube 52 threadably received in boss 48 and at its right hand end on a nut 53 which bears on a flanged sleeve 54 and threadably secures a cylindrical stem 55 to transverse wall 50 of the main valve. A passage 56 in tube 52 receives fluid which may leak into the main valve member and connects with a passage 57 communicating with the annular chamber 40. The chamber 40 communicates with the groove 40 connecting with the left end of main valve sleeve 30 and the chamber 40' connects to drain through a passage 57, a conduit 9 and the conduit 6. Preferably ports 50' are provided in valve wall 50 to prevent a build-up of pressure to the right of the wall.

Means is provided to move the main valve member hydraulically from the position shown in Fig. 2, to which it is moved by the spring 51, to its inlet position, as shown in Fig. 1. The valve stem 55 is slidable in a bore 58 in casing member 28, which bore is enlarged at 59 and carries a bushing 60. Enlarged bore 59 provides a cylinder for a piston formed by a shoulder 61 adjacent a reduced portion 55' of the valve stem. It is the supply of hydraulic fluid under pressure to and the release of fluid from this cylinder by a pilot valve mechanism which, aided by the spring 51, causes the automatic reciprocation of main valve member 29.

The pilot valve mechanism comprises a spool type valve member 62 slidable in a cylindrical sleeve 63 fixed n a bore 64 in casing member 28. The valve member is provided with collars 65, 66 and 67 defining annular grooves 68 and 69 operably associated with sleeve ports 70, 71 and 72 and annular casing grooves 74 and 75 for passing fluid controlled by the pilot valve. The sleeve 63 extends through a bore in casing part 26 to leave an annular passage 76 between the valve inlet passage 45 and ports 70. The end of the sleeve is closed by a plate 63' and has a resilient plug 79 for cushioning the reversmg of the valve member 62 at the left hand end of its reciprocatory movement. The valve member 62 has a hollow bore 62a to permit escape of air and any leakage fluid from the end of the sleeve containing plug 79.

In the position shown in Fig. 1, fluid under pressure from the inlet passage 45 passes through passage 76, ports 70, groove 68, ports 71 and groove 74 to a passage 77 which connects with cylinder 59 and the piston 61 is moved to the left against the action of spring 51 until the main valve reaches the position shown in Fig. 1. The pilot valve member 62 is then shifted (by means hereinafter described) to the position shown in Fig. 2, and during the shifting motion fluid in the cylinder 59 exhausts through passage 77, groove 74, ports 71, groove 69, ports 72, groove 75, a passage 78, and drain passage 46 and valve member 29 moves to the position shown in Fig. 2 under the influence of spring 51.

In the preferred form of the invention, the pilot valve member 62 is mechanically connected to the main valve stem 55 by means including a load and fire device so that as the main valve member reaches each end of its stroke the pilot valve is automatically shifted from one position to the other in which it causes reversal of the main valve member. The connecting means comprises an arm 82 secured at its lower end to main valve stem portion 55 as by nuts 83 and has at its upper end a hole in which a sleeve 84 is fixed. This sleeve is slidable between spaced

abutments

85 and 86 fixed to a stem 87 carried by the pilot valve member 62 and extending therefrom in a substantially parallel spaced relation to main valve stem 55. Sleeve 84 is provided with cylindrical

spring confining extensions

88 and 89 in engagement with adjacent ends of coiled springs 98 and 91 which surround the pilot valve stem 87 between the

abutments

85 and 86 respectively and the slidable sleeve 84. The springs 90 and 91 are so designed that they expand as shown in Figs. 1 and 2 and can alternately 'be compressed within the

extensions

88 and 89 to permit engagement of the ends of the extensions with the

abutments

85 and 86, after the springs are compressed, to positively actuate the pilot valve member.

In order to obtain heavy hammer blows on the tool member 24 the reversing valve is adapted to shift the main valve member 29 rapidly back and forth between its operative positions so that for any given speed of reciprocation the valve member supplies a maximum amount of fluid to the tool 15 by opening the fluid ports quickly to their wide open positions, thus giving the greatest possible transmission of power to the tool. To accomplish this the pilot valve is also adapted to remain in one position as long as possible and then shift rapidly to the other.

As shown in the drawings, the load and fire device embodies a detent mechanism for releasably holding the pilot valve member in either of its operative positions. This mechanism comprises a cylindrical detent collar 92 fixed around a portion 62 of pilot valve member 62 and against a shoulder formed between portion 62' and an integral extension 62" which forms a part of the pilot valve stem 87. A central circumferential rib 93 extends outwardly from the collar and is provided with oppositely facing

surfaces

94 and 95 each alternately engageable with an expandable O-shaped coil spring 96 positioned around the detent collar adjacent one face of rib 93. The detent collar is slidable within a cylindrical bushing 97 mounted in the casing 28 and having two parallel circumferential ribs 98 defining an annular slot 99 opening toward the rib 93 and, serving to confine the coil spring 96 against movement longitudinally of the casing while permitting it to expand to pass over the rib 93.

The pilot valve is arranged to be shifted during the end limits of the main valve movement. The Figs. 1 and 2 illustrate the relative positions of the main valve and pilot valve immediately prior to shifting of the pilot valve by movement of the main valve into the end limits of its inlet and drain positions, respectively. As the main valve member moves to the inlet position as illustrated in Fig. 1, sleeve 84 moves to the left first to compress the spring 90 and coil spring 96 acts against face 94 of rib 93 to prevent the pilot valve from shifting. Continued movement of the main valve beyond the position shown in Fig. 1 causes spring confining extension 88 to positively engage abutment 85, and in eflfect, to bump the pilot valve member in the direction the main valve member is moving. This positive engagement causes coil spring 96 to expand over rib 93 and trigger the load and fire device to release the force of compressed spring 90 which is of suffieient strength to thereafter quickly shifit the pilot valve into the position shown in Fig. 2. 'llhis allows the main valve to shift to its spring-urged reverse position of Fig. 2. Movement of the main valve to the position illustrated in Fig. 2 first compresses spring 91 and then causes the other spring confining extension 89 to bump abutment 86 again snapping loop spring 96 over rib 93 to trigger the load and fire device and release the force of compressed spring 91 to cause shifting of the pilot valve into the position shown in Fig. 1 and allow flow of hydraulic fluid into cylinder 59 to drive the main valve into the inlet position.

To aid in cushioning the pilot valve at its other limit of movement, a coiled spring 80 is placed between valve collar 67 and a disk 81 slidable on valve portion 62. As shown in Fig. 1, the disk 81 engages rib 98 tocushion the pilot valve member at the right hand end of its stroke.

Normally, with a hydraulic system in which a reversing valve controls the flow of fluid through a relatively long conduit to only 'one end of a cylinder that has a piston returned by a spring, a substantial part of the column of hydraulic fluid in the conduit continuously recipro'caltes in the cylinder and conduit and is not replaced with other fluid. The trapped fluid thus becomes excessively hot. To .avoid such trapping and excessive heating of the fluid the invention provides means, associated with passages 13 and 14, to cause circulation of hydraulic fluid in the circuit during operation of the reversing valve. As illustrated in Figs. 1, 2 .and 4, conduits '13 and 14 are formed in part by connecting bores in plates 110, 1 11, and 1 12 forming the upper end of the casing of the tool '1 5 where conduit '18 is provided with a nozzle 1'00 directed downwardly or towards the cylinder 17 and conduit '14 is provided with a similar nozzle 103 directed upwa-rd'lyor away from the cylinder 17. Nozzle 3100 is formed by adownwardly tapered and diminishing bore 101 in the plate 1111 which produces an annular shoulder 102 tending to obstruct flow of fluid out of the cylinder through conduit 16. Nozzle 103 is formed by a similar upwardly tapered and diminishing bore 104 in the plate 111 which produces an annular shoulder 105 tending to obstruct flow of fluid towards the cylinder through conduit 14. Thus it is apparent that although conduits 13 and 14 provide parallel passages between the reversing valve and the tool 15, and are otherwise the same, conduit 13 allows flow of a larger volume of fluid to cylinder 17 than conduit 14 does each time the cylinder is connected by the valve to receive fluid and conduit 13 allows the passage of a lesser volume of fluid from the cylinder than conduit 14 does when the piston 19 is returned upwardly by spring 20. This prov-ides an intermittent but uni-direc-' tional circulation of fluid in the parallel conduits, cylinder and valve so that the fluid fed :to the-cylinder is continuously changed to prevent the fluid from over-heating and also allows any air in the connecting lines to escape, which would otherwise be trapped in the lines.

Means may be provided for varying the rate of reciprocation of the main valve (and, thereby, the tool piston 19) by controlling the rate of fluid flow through passage 78. As shown in Figs. 1 to 3, a cylindrical valve 106 is threadably received in a bore in casing member 28 extending across passage 78 and is provided with a diametrically extending port 107 which forms a part of the passage. The rate of flow may be varied by rotating the valve to vary the port opening in communication with fluid in the passage. The valve has a screw driver slot 108 to f-acili tate adjustment of the valve.

I claim:

1. A hydraulic system comprising; in combination, a source of hydraulic fiuid under pressure, an operating device having a cylinder and a piston slidable therein and spring urged in one direction and periodically hydraulically driven in the reverse direction, a reversing valve for controlling the flow of fluid to and from said cylinder to drive the piston repeatedly against the action of said spring including, a main valve member having spring means for urging it to a drain position, means including a pilot valve shifta'ble between first and second positions for hydraulically controlling reciprocation of the main valve member, and means responsive to the movement of the main valve member for shifting the pilot valve to reverse movement of the main valve member, means defining a pair of conduits communicating between the reversing valve and cylinder, and means in one of said conduits for partly obstructing fluid flow in one direction 6 only in said conduit to provide intenmittent unidirectional circulation of fluid in the conduits during reciprocation of said piston.

2. A hydraulic system for operation by a hydraulic fluid under pressure comprising; in combination, an operating device having a cylinder and a piston slidable therein and spring urged in one direction and periodically hydrau 'l-ically driven in the reverse direction, a reversing valve comprising a casing, a main valve member slidable therein between an inlet position for feeding a hydraulic fluid under pressure to the cylinder and a drain position [for connecting the cylinder to drain, spring means for urging the main valve member toward its drain position, means including a pilot valve for hydraulically driving the main valve member toward its inlet position, means responsive to the movement of the main valve member tor shitting the pilot valve to reverse movement of the main valve member including a load and fire device connected between said main valve member and .the pilot valve, and means defining a plurality of conduits communicating between the main valve member and said cylinder, at least one of said conduits having means for retarding fluid flow 'in one direction only in said conduit during reciprocation of the columns of fluid in the conduits to reciprocate said piston to provide some intermittent uni-directional circulation of fluid in the conduits to avoid excessive heating .of the fluid.

3. A hydraulic system for operation by a hydraulic fluid under pressure comprising; in combination, an operating device having a cylinder and a piston reciprocable therein spring urged in one direction and periodically hydraulically driven in the reverse direction, a reversing valve operable for alternately feeding hydraulic fluid to one end of the cylinder and exhausting it from said end of the cylinder to drain, means defining first and second conduits communicating between the valve and cylinder, said first conduit having an internal tapered portion terminating to form a shoulder facing fluid flow from said cylinder, and a tapered portion in said second conduit terminating tO fOIII1 a shoulder facing fluid flow to said cylinder, said first conduit allowing flow of a larger volume of fluid to said cylinder than the second conduit when the cylinder is connected 'by the valve to a source of hydraulic fluid under pressure and passage of a lesser volume of fluid from the cylinder than the second conduit when the cylinder is connected by the valve to drain thereby providing some uni-directional circulation of fluid through the conduits during reciprocation of said piston.

4. A hydraulic system for operation by a hydraulic fluid under pressure comprising; in combination, an operating device having a cylinder and a piston reciprocable therein and spring urged in one direction and periodically hydraulically driven in the reverse direction, a reversing valve operable for alternately feeding a pressure fluid to and exhausing it from one end of the cylinder, means defining a plurality of conduits communicating between the valve and cylinder, at least one of said conduits having an internal tapered portion forming a shoulder facing fluid flow from said cylinder to provide some uni-directional circulation of fluid in the system during reciprocation of the piston in the cylinder.

5. A hydraulic system comprising; in combination, an operating device having a cylinder and a piston reciprocable therein, means continuously urging the piston in one direction, and means periodically hydraulically driving the piston in the reverse direction comprising a source of hydraulic fluid under pressure, a reversing valve operable for alternately supplying said fluid to and exhausting it from one end of the cylinder, and means defining a plurality of conduits communicating between the reversing valve and cylinder, at least one of said conduits having means for obstructing fluid flow in one direction in said conduit to provide some uni-directional circulation of fluid in the system during reciprocation of the piston in the cylinder.

6. A hydraulic system comprising; in combination, an operating device having a cylinder and a piston reciprocable therein, means for intermittently supplying hydraulic fluid under pressure to and exhausting it from one end of the cylinder, means defining a pair of conduits communicating between the cylinder and said fluid supply means, at least one of said conduits having means operable to cause less flow of fluid in one of said conduits in one direction than in the other direction during continuous reciprocation of the piston in the cylinder.

7. An automatic reversing valve mechanism for controlling the flow of hydraulic fluid to and from a high speed impact tool member comprising; in combination, a casing, a main valve member reciprocable in a bore in said casing between a forward position in which a hydraulic fluid under pressure is connected to said impact member and a reverse position in which the impact member is connected to drain, a spring positioned in said bore bearing against one end of the main valve member and operable to urge the main valve member to its reverse position, a valve stem connected to said main valve memher, a portion of said valve stem being reciprocable in a bore of the casing and having a shoulder operable as a piston in a cylinder formed by an enlargement of the bore, a pilot valve member reciprocable in another bore in said casing between a first position wherein fluid under pressure is directed into the cylinder against the shoulder to drive the main valve member to its forward position and a second position wherein the cylinder for the valve stem shoulder is connected to drain, means operable by the main valve member for shifting the pilot valve member between its first and second positions including a stem connected to said pilot valve member, an arm connected to said main valve stem for movement therewith and having one end slidably mounted on said pilot valve stem for movement between spaced abutments alternately engageable by said arm during the end limits of movement of the main valve member, a spring positioned between said arm and each abutment, and detent means including a detent collar with an outwardly-extending rib fixed to the pilot valve member and an O-shaped coil spring confined against movement with the pilot valve member and alternately engageable with opposite sides of said rib for releasably holding said pilot valve member in either of its positions.

8. A reversing valve mechanism adapted for continuously reversing the flow of hydraulic fluid therethrough comprising; in combination, a casing, a main valve member reciprocable in a bore in said casing between a forward position and a reverse position, spring means for urging the main valve member to its reverse position, piston and cylinder means operable for driving the main valve member to the forward position, a pilot valve member reciprocable in another bore in said casing between a first position wherein fluid under pressure is directed into the piston and cylinder means to drive the main valve member toward its forward position and a second position wherein the piston and cylinder means is exhausted, means for cushioning the pilot valve member at the end limits of its stroke, means operable by the main valve member for shifting the pilot valve member between its first and second positions including a stem connected to said pilot valve member, means connected to said main valve member for movement therewith and fixed to a sleeve slidably mounted on said pilot valve stem for movement between axially spaced abutments fixed to said stein for alternate engagement by said sleeve during the end limits of the main valve member movements, a coiled spring encircling said pilot valve stem between the sleeve and each abutment, a detent mechanism for releasably holding said pilot valve member in each of its positions and including a detent collar fixed to said pilot valve member and having a rib extending outwardly therefrom, said detent collar being slidable in a bushing fixed to said casing and having an annular slot opening toward said rib, and an O-shaped coil spring confined in said annular slot for alternate engagement with opposite sides of said rib and operable for releasably holding the pilot valve member in either of its positions.

References Cited in the file of this patent UNITED STATES PATENTS 1,443,200 Adams Jan. 23, 1923 1,704,238 Barks Mar. 5, 1929 FOREIGN PATENTS 274,166 Great Britain July 7, 1927 623,478 Great Britain May 18, 1949