US2731796A

US2731796A - Hydraulic driving apparatus

Info

Publication number: US2731796A
Authority: US
Publication date: 1956-01-24
Anticipated expiration: 1973-01-24

Description

19% l. SUBLETT ET AL 2,731,796

HYDRAULIC DRIVING APPARATUS Filed Feb. 1.7, 1955 4 Sheets-Sheet l Jwmm @Zia &..

Jam. 24, 1955 1. SUBLETT ET AL 2,731,7 6

HYDRAULIC DRIVING APPARATUS Filed Feb. 17, 1955 4 S eets 2 1956 l. SUBLETT ET AL 2,731,796

HYDRAULIC DRIVING APPARATUS HYDRAULIC DREVTNG AEPARATUS Ira Sublett and Charles D. Johnson, Fairrnont, Minn, assiguors to Fairmont Railway Motor s, incorporated, Fairmont, Minn., a corporation of Minnesota Application February 17, 1955, Serial No. 488,336

7 Claims. (Cl. 60-51) This invention relates to a hydraulic driving apparatus and more particularly to an apparatus adapted for use in equipment designed for imparting impact blows or reciprocatory motion, such as, for example, railroad spike drivers, paving breakers, ballast tampers, weed mowers, and the like.

Heretofore in apparatus for such equipment, it has been the customary practice to utilize pneumatic pressure as the source of power with the result that such apparatus is possessed of numerous shortcomings. First, the operating etficiency of such apparatus is exceedingly low because of the amount of wasted power which is expended. Second, to compensate for this wasted power, oversize compressors and associated parts are required which add materially to the cost and weight of the equipment and render manipulation of the equipment a difiicult and frequently an awkward operation. Third, the noise, which is normally produced by such pneumatically operated apparatus, is generally objectionable and is oftentimes disconcerting and fatiguing to the operator, particularly where the equipment is being used continuously over extended periods of time. Lastly, the apparatus had a tendency to frequently get out of synchronization, thus requiring considerable service to maintain in proper working order.

Thus, it is an object of this invention to produce an apparatus which utilizes hydraulic pressure as its source of power and thereby effectively overcome all of the shortcomings aforenoted.

It is a further object of this invention to produce an apparatus which is practically foolproof in operation and which enables the operator to exercise complete and positive control of the apparatus at all times.

It is a still further object of this invention to provide an apparatus which is compact and simple in construction, thereby facilitating manipulation of the apparatus by the operator.

Further and additional objects will appear from the description, accompanying drawings, and appended claims.

In accordance with one embodiment of this invention, a hydraulic driving apparatus is provided comprising a hydraulically responsive piston-cylinder unit in which the driving piston thereof has one end thereof protruding longitudinally from an elongated cylinder section. The piston is provided with an enlarged annular boss which is disposed intermediate the ends thereof and is adapted to slidably engage the interior of such cylinder section and separate the latter into two isolated compartments, the volumes of which vary upon relative movement of the piston. The protruding piston end is operatively connected to a hydraulic pressure accumulator which is isolated from the cylinder section interior by said piston end and is adapted, at predetermined times, to eifect actuation of said piston in one relative direction. The accumulator is in constant communication with a source of hydraulic pressure. Operatively connected to the accumulator is an automatically adjustable control valve which, in turn, has a States Patent first portion thereof operatively connected to an interior portion of the cylinder section disposed, with respect to the accumulator, on the opposite side of the boss formed on the piston, a second portion operatively connected to a reservoir for hydraulic fluid, and a third portion in constant communication with the source of hydraulic pressure. The control valve is biased to normally assume a first position of adjustment wherein the aforenoted interior portion of the cylinder section and the reservoir are interconnected and the driving piston is actuated by the accumulator pressure in the one relative direction. The piston, upon reaching a predetermined station of travel in the one relative direction, automatically causes the valve and accumulator to effect communication with one another whereby said valve is actuated by said accumulator pressure to a second position of adjustment. The control valve, when in a second position of adjustment, effects interconnection of the aforenoted interior portion of the cylinder section and the source of hydraulic pressure and results in the direction of movement of the piston being automatically reversed. Upon the piston reaching a predetermined station while traveling in the reverse direction, communication between said accumulator and valve is automatically interrupted whereupon said valve returns to its normal position of adjustment, and the cycle of operation is repeated.

For a more complete understanding of this invention, reference should be made to the drawings wherein:

Figure 1 'is a fragmentary elevational view of the improved apparatus;

Fig. 2 is a sectional view taken along line 22 of Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view taken alongline 3-3 of Fig. 2;

Fig. 4 is a fragmentary sectional view taken along line 4-4 of Fig. 2;

Figs. 5, 6, and 7 are sectional views taken along lines 5-5, 6-6, and 77, respectively, of Fig. 3; and

Figs. 8, 9, l0, and 11 are diagrammatic views of the improved apparatus and the associated parts therefor, showing the piston in four stations of travel.

Referring now to the drawings and more particularly to Figs. 1 and 2, the improved hydraulic driving apparatus 20 is shown which, as heretofore mentioned, is adapted for use in equipment designed for imparting impact blows or reciprocatory motion. By way of example, and for purposes of simplification, the description of the apparatus to follow hereinafter will be in relation to a railroad spike driver. It is to be understood, of course, that the scope of this invention is not to be confined to this particular type of equipment but is referred to merely by way of illustration.-

The improved apparatus 20 comprises a hollow housing 21 and piston 22 mounted for reciprocatory movement within a chamber 23 formed in the center section 23 of the housing. The center section 23 will be hereinafter referred to as a cylinder section. The section 23' has the upper end thereof terminating in an annular collar 24 provided with a center opening 25 through which the upper end portion 22a of the piston is adapted to extend. A very small tolerance exists between the diameter of the opening 25 and the outside diameter of piston end portion 22a; thus, the latter effects a seal between the interior 23 of cylinder section 23' and a chamber 26 formed in the upper section 27 of the housing 21 while at the same time the piston is free to reciprocate. It is to be noted in Figs. 1 and 2 that the outer periphery of

housing sections

23 and 27 are provided with a plurality of cooling fins 28 which effectively dissipateanyheat which might develop within

chambers

23 and 26 during movement of the piston.- Other means may be utilized, if desired, to

effect such heat dissipation; for example, the

housing sections

23 and 27 may be water-jacketed.

Secured to the upper end of housing section 27 is a hydraulic pressure accumulator 29, the interior of which communicates with chamber 26. The accumulator may be of conventional construction well known to those skilled in the art.

Chamber 26 is adapted to be in continuous or uninterrupted communication with the source of hydraulic pressure 30, see Figs. 8-11, by means of a conduit 31, thereby insuring that the pressure within the accumulator 29 will be rapidly replenished once such pressure has been utilized to actuate the piston 22 in one relative direction in a manner to be hereinafter more fully described. Conduit 31 is diagrammaticaly shown in Figs. 8ll as being a single pipe; however, in the mechanical construction, shown in Fig. 2, conduit 31 comprises a first passageway 31a formed partly in

housing sections

27 and 23 and having only one end thereof communicating with the chamber 26 formed in housing 27 and the other end thereof communicating with an aligned passageway 31b formed in a valve housing 32. Valve housing 32 forms a part of a shuttle type control valve 33 which will be described more fully hereinafter. Passageway 31b, formed in valve housing 32, communicates with a second passageway 34 formed in said housing which, in turn, terminates in a fluid intake port 35. Connected to port 35 is a conduit or pipe 36 leading to the source of hydraulic pressure 30, shown in Figs. 8-11.

Mounted on a flattened surface 27a provided on the outside of housing section 27 is an on-off valve 37 which must be moved to its on position before move ment of the piston 22 can be effected. Valve 37 includes a hollow casing 38 which is secured to housing section 27 by a plurality of bolts 40. Disposed within an elongated chamber 41, formed within casing 38, is an elongated shuttle 42 which is adapted to be moved endwise within said chamber 41. Communicating with chamber 41 at substantially the longitudinal center thereof is a first passageway 43 which, in turn, is aligned with a passageway 44 formed in housing section 27. Passageway 44 terminates at a small cavity or compartment 45 which, during certain stations of travel of piston 22, is in direct communication with chamber 26. An annular shoulder 46 separates chamber 26 and compartment 45 and is provided with an opening 47 which is of such dimension as to permit the upper end 22a of the piston 22 to pass there through. When piston end portion 22a is disposed within opening 47, compartment 45 is isolated from chamber 26.

Communicating with chamber 41 and spaced from passageway 43 is a second passageway 48 formed in casing 38 which, in turn, is aligned with an end of a passageway 50 formed in housing section 23'. Passageway 50 is spaced from chamber 23 and effects communication between on-off valve 37 and a passageway 51, formed in valve housing 32. Passageway 50 communicates with an elongated chamber 52 formed in housing 32. Chamber 52 is adapted to accommodate therein an elongated shuttle 53 which forms a part of control valve 33. Valve 33 will be described more fully hereinafter.

Shuttle 42 of on-ofl valve 37 is provided with an annular groove 42a which is adapted, when the shuttle is actuated to its on position, to effect interconnection between

passageways

43 and 48 of casing 38. When shuttle 42 is in its normally off position, as shown in Fig. 2, interconnection of

passageways

43 and 48 is interrupted by the shuttle. Shuttle 42 is provided with an integral elongated end section 54 which is reduced in size and extends axially from the upper end of the shuttle, as seen in Fig. 2, and is enclosed within a cup-like member 55. Encircling end section 54 is a coil spring 56 which has the lower end thereof contacting a stationary washer 57 held in place by a bushing 58, which, in turn, contacts valve casing 38, and an interior shoulder formed in member 55. The other end of the spring 56 engages a retainer 60 which is aflixed to the end of section 54 and is movable therewith. Formed in the outer end of member 55 is a port 61 which is adapted to receive a conduit 62, see Figs. 8-11, leading to a hand or foot-operated hydraulic piston unit 63. Upon actuation of the piston 63a of unit 63 in a downward direction as viewed in Figs. 8-11, hydraulic pressure is exerted on the large diameter of shuttle 42 and will be of such magnitude as to overcome the bias of spring 61 and eflect compression thereof so as to move the shuttle to the second position of adjustment. Thus, so long as the operator manipulates the unit 63, the apparatus will operate in a manner to be hereinafter described.

The control valve 33, as heretofore mentioned, is provided with a housing 32 which is secured by a plurality of bolts 64 to a flattened surface 65 formed on the exterior of housing cylinder section 23' beneath flattened surface 27a. Housing 32 is provided with a passageway 66 which extends substantially transversely from the longitudinal center of chamber 52 and is aligned with a passageway 67 formed in housing cylinder section 23'. The passageway 67 terminates in the lower end of chamber 23. Disposed within passageway 67 is a restrictive valve 68 which restricts the flow of fluid only when the latter is moving in a direction toward chamber 23. The reason for this one way restrictive action will become apparent hereinafter.

Formed in valve housing 32 is another passageway 70 which terminates at one end in an outlet port 71, the latter being connected by a pipe 72 to the reservoir 73 for the hydraulic fluid, see Figs. 8-ll. A vent 74 is formed in housing 32 which interconnects the lower end 52a of chamber 52 and passageway 70. Communicating with the inner end of passageway 70 and chamber 52 and ex tending angularly therefrom is a passageway 75, see Fig. 4, which, in turn, communicates with the lower end of an elongated passageway 76 formed in cylinder section 23, see Fig. 3. The passageway 76 is substantially diametrically opposite passageway 31a with respect to chamber 23. The upper end 76a of passageway 76 terminates at the upper end of chamber 23 adjacent annular collar 24 thereby providing a communication between the upper end of chamber 23 and the reservoir 73 at all times.

Disposed within the lower portion 52a of chamber 52 of valve housing 32 is a coil spring 77 which is adapted to exert an upward force, as viewed in Fig. 2, on shuttle 53 of valve 33.

The driving piston 22, as heretofore mentioned, is mounted for reciprocatory movement within housing 21. The upper end portion 22a is reduced in cross section and is adapted to be disposed in

chambers

26 and 23. The lower end 22b of piston portion 22a is slightly reduced in cross-sectional size and then flares outwardly and terminates in an enlarged annular boss 220, the

outer periphery of which is substantially the crosssectional size of chamber 23. The reason for such unique configuration of piston 22 will become apparent from the description to follow hereinafter. As the piston 22 reciprocates the boss 22c is confined to movement within chamber 23 and effects separation of said chamber into two isolated upper and lower compartments which vary in volumetric size as the piston moves, see Figs. 8-11. The lower end portion 22d of piston 22 extends downwardly from the opposite side of boss 220. End portion 22a is relatively larger in cross section than upper end portion 22a, and is adapted to strike, upon approaching the lower end of its downward stroke, a driving stud 78 supported at the lower end of housing 21. The stud 78, in turn, is adapted to engage the head of a spike or the like, not shown. As heretofore mentioned, the apparatus may be used in other types of equipment than in a spike driver, and therefore the invention is not to be limited to a spike driver, A bushing 80 is positioned at the lower end of chamber 23 and is adapted to properly align the piston within the housing 21 and also to provide a seal for the lower end of chamber 23.

Operation of apparatus To facilitate understanding of the operation of the improved apparatus, reference should be made to Figs. 811 wherein the direction of movement of the piston at the particular station is shown by the arrow.

To commence operation of the apparatus the piston 63a of unit 63 is manually actuated causing the shuttle 42 of on-oii-valve 37 to be actuated downwardly to an on position as shown in Figs. 8-11.

In Fig. 8, the piston 22 has reached the end of its upward stroke and is in position to be actuated downwardly by the full impact of the hydraulic pressure accumulated in accumulator 29. When the piston is in this relative position, the shuttle 53 is in its normal biased position by reason of coil spring 77. The shuttle 53 is provided with a plurality of axially spaced annular bosses 81a, 81b, and 810, which are adapted to slidably engage axialiy spaced annular collars 82 formed in chamber 52 and eflect alignment of the shuttle 53 within the chamber and at the same time eifect interconnection of certain of the passageways which communicate with the chamber. When the shuttle 53 is in the position shown in Fig. 8, there is an interconnection between

passageways

67 and 72 which results in the lower end of the cylinder chamber 23 being vented to reservoir 73 and simultaneously therewith the flow of high pressure fluid is blocked by bosses 81b and 81c of valve 33. Because of the reduced piston portion 22b, fluid which had previously been entrapped in compartment 45 is likewise vented to the reservoir 73 through collar opening 25 into the upper portion of chamber 23 and then from chamber 23 through passageway 76.

As piston 22 moves from the position shown in Fig. 8 to the position shown in Fig. 9, piston portion 22a closes off the venting of fluid from compartment 45 to chamber 23 and thereby seals any fluid remaining in passageway 44 and compartment 45. The accumulator pressure plus the pressure from source 30, the latter being relatively insignificant, are the driving forces which react on piston portion 22a and result in downward movement of the piston.

When the piston 22 reaches the end of its downward stroke, as seen in Fig. 10, piston portion 22a moves past collar 46 and effects interconnection of compartment 45 and chamber 26 which results in high pressure fluid being introduced into passageway 44, valve 37, passageway 50 and chamber 52 of valve 33. The high pressure fluid reacts against the upper surface of boss 81c and thereby overcomes the bias of spring 77 and causes the shuttle 53 of valve 33 to move to its down position within the valve housing 32, see Figs. and 11. When the shuttle 53 of valve 33 is in its down position, high pressure passageway 36 leading from the source 30 is interconnected to passageway 67 and thereby causes the high pressure fiuid to flow into the lower end of chamber 23 and exert a force on the underside of boss 220 of piston 22 and result in piston 22 moving upwardly in the direction of the arrow, by reason of the undersurface of boss 220 being relatively larger in area than the top surface of piston portion 22a disposed adjacent accumulator 29. The flow of the high pressure fluid past restriction valve 68 in a direction toward chamber 23 is restricted somewhat, as heretofore mentioned, thereby dampening, to a certain extent, the inertia of piston 22 in an upward direction which might ordinarily cause excessive rebound and shock of the piston when the latter reaches the end of its upward stroke.

As piston 22 moves from the position of Fig. 10 to the position of Fig. 11, piston portion 22a once again isolates compartment 45 from

chambers

26 or, 23 and thereby results in shuttle 53 of valve. 33 being locked in its down position by the entrapped hydraulic fluid until venting of compartment 45 into chamber 23 occurs, as shown in Fig. 8, whereupon shuttle 53 returns to its normal upposition clue to the bias of spring 77. The cycle of operation of piston 22 will repeat itself and continue to do so until the operator releases his grip on unit 63 and on-ofl valve 37 automatically returns to its ofFposition.

Thus, it will be seen that an improved hydraulic driving apparatus has been provided wherein the operation of piston 22 and the shuttle 53 of valve 33 will remain in perfect synchronous relation at all times because the movement of the latter is dependent upon the movement of the former and thereby such synchronous relation insures foolproof performance of the apparatus. Furthermore, the apparatus is compact in constructionand of a closed circuit design, thereby facilitating manipula tion and handling of the apparatus. In addition the apparatus results in eflicient utilization of the source of hydraulic pressure and thereby elfects a saving in operat ing costs.

While a particular embodiment of this invention is shown above, it will be understood, of course, that the invention is not to be limited thereto, since many modifications may be made, and it is contemplated, therefore, by the appended claims, to cover any such modifications as fall within-the true spirit and scope of this invention.

We claim:

1. A hydraulic driving apparatus comprising a hydraulically responsive reciprocating element, a source of hydraulic pressure, a reservoir for hydraulic fluid, a hydraulic pressure accumulator communicating with said source and operatively connected to act on one portion of said element to effect at a predetermined time movement of said element in one relative direction, and adjustable means operatively connected to said source, said reservoir, a second portion of said element, and said accumulator; said means, when in one position of adjustment, being responsive to said accumulator pressure and effecting interconnection of said source and said second element portion whereby said element is actuated in a second relative direction'and, when in a second position of adjustment, being out of communication with said accumulator and eflecting interconnection of said reservoir and said second element portion whereby said element is actuated in said one direction by said accumulator pressure.

2. A hydraulic driving apparatus comprising a hydraulically responsive reciprocating element, a source ofhydraulic pressure, a reservoir for hydraulic fluid, a hydraulic pressure accumulator communicating with said source and operatively connected to act on one portion of said element to effect at a predetermined time movement of said element in one relative direction, and adjustable valve means operatively connected to said source, said reservoir, a second portion of said element, and said accumulator; said means, when in one position of adjustment, being responsiveito said accumulator pressure and effecting interconnection of said source and said second element portion whereby said element is actuated in a second relative direction, and when in a second position of adjustment, being out of communication with said accumulator and eifecting interconnection of said reservoir and said second elementportion whereby said element is actuated in said one relative direction by said accumulator pressure; the adjustment of said means being automatically eflecte d by said element upon the latter reaching predetermined stations of travel.

3. A hydraulic driving apparatus comprising a hydraulically responsive reciprocating element, a source of hydraulic pressure, a reservoir for hydraulic fluid, a hydraulic. pressure accumulatorcommunicating with said source and with one portion of said element to eifect at a predetermined time movement of said element in one relative direction, adjustable first means operatively connected to said source, said reservoir, a second portion of said element, and said accumulator, said first means, when in one position of adjustment, being responsive to said accumulator presure and efiecting interconnection of said source and said second element portion whereby said element is actuated in a second direction, and, when in a second position of adjustment, being out of communication with said accumulator and effecting interconnection of said reservoir and said second element portion whereby said element is actuated in said one direction by said accumulator pressure, and an adjustable second means interposed said accumulator and said first means for interrupting the interconnection therebetween when said second means is in one position of adjustment.

4. A hydraulic driving apparatus comprising a hydraulically responsive reciprocating element, a source of hydraulic pressure, a reservoir for hydraulic fluid, a hydraulic pressure accumulator communicating with said source and with one portion of said element to effect at a predetermined time movement of said element in one relative direction, and adjustable valve means operatively connected to said source, said reservoir, a second portion of said element, and said accumulator; said valve means being biased to normally assume one position of adjustment wherein said means is out of communication with said accumulator while said second element portion and said reservoir are in communication with one another to effect actuation of said element in said one direction by said accumulator pressure; said valve means being automatically brought into communication with said accumulator and actuated out of its normal position of adjustment to a second position of adjustment by said accumulator pressure upon said element reaching a predetermined station of travel in said one direction; said valve means, when in said second position of adjustment, effecting communi cation of said source and said second element portion whereby said element is actuated in an opposite direction by the pressure from said source; said valve means automatically reverting to its normal position of adjustment upon said element reaching a second predetermined station of travel in said opposite direction.

5. A hydraulic driving apparatus comprising a hydraulically responsive piston-cylinder unit having one end of the piston thereof protruding from the cylinder and an enlarged boss formed on said piston intermediate the ends thereof and disposed within said cylinder and effecting separation of the cylinder interior into two isolated compartments, a source of hydraulic pressure, a reservoir for hydraulic fluid, a hydraulic pressure accumulator accommodating the protruding end of said piston and being isolated from the interior of said cylinder by said protruding piston end, said accumulator effecting at a predetermined time movement of said piston in one relative direction, and adjustable control means operatively connected to said source and reservoir and in communication with a portion of said cylinder, disposed with respect to said accumulator, on the opposite side of said piston boss, for regulating movement of said piston; said means, when in one position of adjustment, being responsive to said accumulator pressure and effecting interconnection of said source and said cylinder portion whereby said piston is actuated in a second relative direction, and, when in a second position of adjustment, being out of communication with said accumulator and effecting interconnection of said cylinder portion and said reservoir whereby said piston is actuated in said one relative direction by said accumulator pressure, the position of adjustment of said control means being automatically effected upon said piston reaching predetermined stations of travel within said cylinder.

6. A hydraulic driving apparatus comprising a pistoncylinder unit wherein the piston thereof is hydraulically responsive and mounted for reciprocatory movement Within the cylinder of said unit, said piston having one end thereof protruding from said cylinder and having an enlarged boss formed on said piston intermediate the ends thereof and efiecting separation of the cylinder interior into isolated compartments, a source of hydraulic pressure, a reservoir for hydraulic fluid, a hydraulic pressure accumulator accommodating the protruding piston end and being isolated from the interior of said cylinder by said piston end, said accumulator elfecting at a predetermined time movement of said piston in one relative direction, and automatically adjustable control means operatively connected to said source, reservoir, accumulator, and a portion of said cylinder disposed with respect to said accumulator on the opposite side of said enlarged piston boss, for efiecting reciprocatory movement of said piston; said control means being biased to normally assume one position of adjustment wherein said means is out of communication with said accumulator and interconnection of said cylinder portion and said reservoir is effected and said piston is moved in said one relative direction by said accumulator pressure; said control means communicating with said accumulator and being actuated out of normal position by said accumulator pressure to a second position of adjustment upon said piston reaching a predetermined station of travel in said one relative direction; said'means, when in said second position of adjustment, interconnecting said source and said cylinder portion to effect reversal in the direction of relative movement of said piston, the latter upon reaching a predetermined station of travel in said reversed direction effecting interruption of the communication between said accumulator and control means whereupon the latter returns to its normal position of adjustment.

7. A hydraulic driving apparatus comprising a hydraulically responsive ramming piston mounted for reciprocatory movement within a cylinder, said piston having one end thereof protruding from said cylinder and having an enlarged annular boss formed thereon intermediate the ends of said piston and disposed Within and slidably contacting the interior of said cylinder to form two isolated compartments within said cylinder, a source of hydraulic pressure, a reservoir for hydraulic fluid, a hydraulic pressure accumulator communicating with said source and accommodating the protruding piston end and exerting at predetermined times accumulated pressure on said accommodated piston end to elfect movement of said piston in one relative direction, adjustable valve means operatively connected to said accumulator, said source, said reservoir, and a portion of said cylinder disposed with respect to said protruding piston end on the opposite side of said boss, said valve means being biased to normally assume a position wherein said means is out of communication with said accumulator and said reservoir and cylinder portion are interconnected to efiect movement of said piston in said one direction, said piston, upon reaching a predetermined station of travel in said one direction within said cylinder, automatically effecting communication between said accumulator and valve means wherein the latter is moved from its normal position of adjustment to a second position, said valve means, when in said second position, effecting interconnection of said source and said cylinder portion whereby the direction of movement of said piston is reversed and said piston is actuated in said reversed direction by the pressure from said source being exerted on said boss, said piston, upon reaching a predetermined station of travel within said cylinder when moving in said reversed direction, interrupting communication between said accumulat or and said valve means whereby the latter returns to its normal position of adjustment, and a manually operated on-oit control means interposed said accumulator and said valve for interrupting communication therebetween when in an off position.

No references cited.