US2972867A - Pressure intensification device - Google Patents

Description

Feb. 28, 1961 KLINGLER 2,972,867

PRESSURE INTEN$IFICATION DEVICE Filed July 27, 1959 Y Q \\J INVENTOR. Nmum L. KLINGLER M W*W 1,912,861 I i PRESSURE INTENSIFICATION nnvrcn Martin L. Klingler, Hershey, Pa, a'ssignor to AMP Incorporated, Harrisburg, Pa.

Filed July 27, 1959, Ser. No. 829,815 Claims. (Cl. 60- 54.);

This invention relates to devices for pressurising .a hydraulic fluid. The invention is herein disclosed in ,conjunction with a fluid pressure intensifier of these called one shot type, however, it will be apparent that the invention is amenable to usage in other types of fluidoperated devices.

Single stroke or one she intensifiers of the type known to the art comprise a relatively large diameter low pressure cylinder and a relatively small diameter high pressure cylinder, the bore of which is, filled with oil or other hydraulic fluid. The piston within the low pressure cylinder has a plunger secured thereto which extends into the bore of the high pressure cylinder so that upon movement of the piston towards the high pressure cylinder this plunger moves relatively into the bore of the high pressure cylinder to compress the hydraulic fluid therein. Devices of this type are useful in a variety of applications, for example, in relatively small manually held tools such as riveting tools or electrical terminal crimping tools. The motive fluid available for such tools is usually compressed air under a pressure of'about 80- 120 p.s.i. and the 'force required for the crimping or riveting operation is usually such that an extremelylarge air cylinder would be necessary if the piston of the air cylinder directly actuated the riveting or'crimping'dies. If, however, an extremely large air cylinder were to be used, the tool would become unwieldy and could not be manually held during use. If, on the other hand, the tool is adapted to operate on very high pressure (e.g. 5000-8000 p.s.i.) hydraulic fluid, the tool can be extremely small and still deliver the required force for the crimping or riveting operation. The hydraulic fluid under high pressure is supplied by means of an intensifier having alow pressure air cylinder and a high pressure hydraulic cylinder which is connected by means of a flexible hose to the tool itself. J

'In. these intensifiers, as in other hydraulic devices, there is inevitably some loss of hydraulic fluid =by leakage at the couplings required for the device. The amount of fluid lost may be extremely small for each cycle the tool goes through, however the accumulated losses can 2,972,867 Patented Feb. 28, 1061- 'ice m .2 v V the invention to provide a single stroke or one shot fluid intensifying device having a high pressurehydraulic cylinder and a makeupreservoir for the hydraulic cylin: der of improved construction.

'- These andotherobjeots areachieved in a preferred embodiment of :an inte'nsifierin which the low pressure pneumatic cylinderandthe high pressure hydraulic cylinseriously deplete the volume of hydraulic fluid available so that the amount of work which can be obtained from the tool during a single cycle will be decreased, possibly to the .point where the toolwould be incapable of com.-

pletely carrying out the operation, such as riveting or terminal crimping, for which it wasintended. It-is common to provide makeup or replenishing reservoirs to such 7 tools to supply hydraulic fluid which happens to become lost, and it is to construction ofsuch reservoirs that the instant invention is addressed. I, Y Q

It'i's accordingly an object of the invention to provide a hydraulic device having an improved replenishing or make up reservoir. I-t is alfurther'objectito provide a fluidpressure intensifying'device having'fa high "pressure hydraulic cylinder and an improved replenishingres'ervoir. {or this high pressure cylinder. It is a further obj'e'ct of der are in axialalignment with each other. The low pressure cyIinderJhas. a piston therein with a plunger secured to its face'which plunger extends into, and is in alignment with, ,the' highpressur'e hydraulic cylinder so that as the piston. moves relatively towards the high pressure hydraulic cylinder, .the hydraulic fluid is com pressed and the work' required-by the tool to which the device is attached is accomplished. Within the low pressure cylinder and adjacent the end thereof which is next to the high pressure cylinder there is provided a reservoir of replenishing hydraulic fluid. This reservoir has one wall of a resilient'and flexible material such as oil resistant synthetic rubber'or nylon reinforced with synthetic rubber. Resilient means in the form of a coil spring surrounds the plunger and bears at one'end against the face of the piston and at the other end against this resilient wall of the reservoir. The reservoir itself is in communication with the bore of the high pressure cylinder by means of a' passageway so that hydraulic fluid is supplied to the bore of this high pressure cylinder to com 'pensate for any losses which maytake place during use. The reservoir itself is mildly pressurized by means of the spring so that the hydraulic fluidin the reservoir is forced through the passageway as it is needed to replenish previouslosses. Advantageously, the outlet port of the passageway connecting the reservoir withthe bore of the high pressurecylinder is located such that this port is covered and closed during initial movement of the plunger into the high pressure cylinder. By virtue'of this arrangement, the reservoir itself is not subjected to the extremely high pressures generated during movement of the plunger. I In the drawings: 7 Figure 1 is a sectional view of a preferred embodiment of the invention;

Figure 2 is a view similar to Figure 1 but showing the relative positions of the parts during movement of the piston-within the low pressure cylinder, and

Figure3 is a fragmentary view of an alternative embodiment.

I The preferred embodimentprovides a high pressure hydraulic cylinder 2 having a base porti'on4 and an axial bore 6. Cylinder 2 is secured at .i-ts base by means of fasteners 26 to a low pressure pneumaticor air cylinder 8 having a back wall 10 and in which thereis provided a piston 12. A plunger 14 secured 'to theface of thepiston by means of a plate 16 and suitable fasteners as 1 phragm 20'which surrounds plunger 14. The inne'r'edge of this diaphragm is clamped by-means bf a platen and I suitable fasteners as shown to the base portion while' 'theouter edge is' clamped betweenthe'wall of therylinderS, i I Wi 26 24 n in the base portion by means of with the 'aid of the fasteners 26 -A"pas's'a'gew ay. '28 extends from reservoir 30 hrough'fltlie wallroifthe"highpres;

surecylinder and into thejb o're qfthe reof. "'"Itwill'be' noted that'inthe"preferredembodiment the' passageway where it enters bore 6 is disposed at a location such that it is uncovered only when the piston 12 is against the backwall 10 of the low pressure cylinder. By virtue of' this arrangement, upon initial movement of the piston 12 and the plunger 14 this port is closed and sealed from the relatively high hydraulic pressures generated in bore 6.

A coil spring 32 is interposed between the face of piston 12 and the flexible diaphragm of the reservoir so that this spring serves a dual function of biasing piston 12 against wall 10 of the low pressure cylinder and at the same time maintaining a mild pressurization of the reservoir 30. Advantageouslyvthis spring is conical so that its adjacent convolutions fit within each other upon movement of the piston 12 towards the base 4 of the high pressure cylinder. It is desirable to provide a section of plastic tubing as shown at 34 over the convolution of the spring'32 which bears against diaphragm of the reservoir. This section of tubing increases the bearing area of the spring against the diaphragm and additionally protects it against damage by the spring. In order to prevent the piston from ever touching the diaphragm and possibly damaging it, there is provided a stop ring 36 on plunger 14 which is adapted to bear against clamping ring 22 when the piston has traveled its full stroke. It Will be apparent that the size and particularly the length of this stop ring is such that the ends or edges of the piston cannot contact the diaphragm of the reservoir. Suitable Q-rings 38 are provided as'shown in piston 12 and in the bore of high pressure cylinder 2 to prevent leakage of compressed fluid. An outlet 46 and the end of high pressure cylinder 2 accepts the coupling of a flexcylinder than is the case with the embodiment of Figure 1. Toroidal member 44 may be of a firm oil resistant plastic such as a nylon.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is oflered by way of illustration only. The actual scope of the invention is intended to. 'bedefined in the following claims when viewed in their proper perspective against the prior w art.

ible hose by means of which the high pressure fluid is supplied to a crimping tool or the like.

In use, when the tool with which the intensifier is being used is actuated, air is admitted through inlet 11 against the face of piston 12 to drive this piston upwardly as viewed in the drawings. Upon initial movement of the piston passageway 28 is closed off by virtue of the movement of the plunger 14 past the outlet port of this passageway. Upon further. movement the hydraulic fluid within bore 6 is compressed and the work required by the device such as the tool with which the apparatus is usedis accomplished. After the air is exhausted through inlet 11 at the end of the stroke, spring 32, which was compressed during upward movement of the piston, returns the piston against backwall 10. When the port 28 is uncovered, the mild pressure imposed by the spring on wall 20 of the reservoir forces hydraulic fluid from the reservoir into the bore 6 of the high pressure cylinder. Thus the charge of hydraulic fluid within the cylinder is at all times maintained at the maximum level. A filling cap 42 is provided to permit the addition of hydraulic fluid to the reservoir 30 when it becomes necessary to do so.

In Figures 1 and 2, the reservoir 30 is shown as being filled substantially to the limit of its capacity and the diaphragm is, therefore, convex on its external surface against which spring 32 bears. As the fluid in the reservoir is transferred to the bore of the cylinder, the cross section will change, and the spring will press relatively further into the diaphragm. With the embodiment of Figures 1 and 2,.When the reservoir is almostempty, the diaphragm will be concave on its external surface and will be further depressed beneath the spring than in the case in Figures 1 and '2. It will be appreciated thatv the diaphragm 'should be of relatively tough and strong material in order to permit it to withstand the pressure of the fluid.

Figure 3 shows an alternative embodiment in which plastic tube 34 is replaced by a toroidal member 44 havingja radius of .curvature on its external surface which is slightlyless than the radius of curvature of surface 18'.

Withthis arrangement, a greater portion of the fluid in V the reservoir can be forced into the bore of the fluid I claim:

1. Apparatus for pressurizing a :hydraulic fluid comprising, a low pressure cylinder and a high pressure cylinder, said high pressure cylinder having a base portion which forms one end of said low pressure cylinder, a piston in said low pressure cylinder having a plunger extending therefrom into said high pressure cylinder, a replenishing reservoir for said high pressure cylinder in said low pressure cylinder and disposed adjacent said one end, a. passageway extending from said reservoir to said high pressure cylinder, resilient means surrounding said plunger and normally biasing said piston towards the opposite end of said low pressure cylinder, said resilient means bearing against said'reservoir thereby to maintain a pressure on said reservoir and maintain a full charge of fluid in said high'pressure cylinder.

2. A pressure multiplying device comprising, a low pressure cylinder and a high pressure cylinder, said high pressure cylinder having a base portion which forms one end of said low pressure cylinder, a piston in said low pressure cylinder having a plunger extending therefrom into said high pressure cylinder, 21 replenishing reservoir for said high pressure cylinder in said low pressure cylinder and disposed adjacent said one end, a passageway extending from said reservoir. and opening into said high pressure cylinder at a point adjacent the end of said plunger when said plunger is in its retracted position whereby, said'passageway is closed upon movement of said plunger, and means Within said low pressure cylinder for maintaining a mild pressurization of reservoir.

3. A pressure multiplying device comprising, a low pressure cylinder and a high pressure cylinder, said high pressure cylinder having a base portion which forms one end of said low pressure cylinder, a piston in said low pressure cylinder having aplunger extending therefrom into said high pressure cylinder, a replenishing reservoir for said high pressure cylinder in said low pressure cylinder and disposed adjacent said one end, a passageway ex,- tending from. said reservoir and. opening into said high pressure cylinder at a point adjacent the end of said plunger, whereby said passageway is closed upon move.- ment of said plunger, and spring means surrounding said plunger and bearing against said piston and said reservoir, said spring means normally biasing said piston to wards the end of said lowpressure cylinder opposite said base and maintaining a mild pressurization of said reservoir thereby to maintain a full charge of fluid in said high pressure reservoir.

7 4. .A fluid. pressure multiplying device comprising a low'pressure cylinder and a high pressure cylinder, said cylinders being disposed in axial alignment, apiston in said low pressure cylinder having a plunger extending therefrom into said high pressure cylinder, the end'of' said low pressure cylinder which is adjacent said high pressure cylinder having therein an annular reservoir surrounding said plunger, said reservoir being defined by a flexible, substantially impervious disc having a central, opening and by said end of said low pressure cylinder, a passage; way extending ,from said reservoir to said highpressure cylinder, and means in said low pressure cylinderforirn'. posinga mild-pressure on said disc thereby to naintain a ful sha e f lu d i i i h pressure cylind r, f

5. A fluid pressureinteu sifier comprising a relatively large diameter low pressure cylinder and a relatively small diameter high pressure cylinder, said cylinders being axially aligned, a piston in said low pressure cylin der having a plunger secured thereto and extending towards said high pressure cylinder, a reservoir in said low pressure cylinder disposed adjacent the one end thereof which is adjacent said high pressure cylinder, a passageway leading from said reservoir to said high pressure cylinder, and compressible resilient means interposed between said reservoir and the face of said piston whereby said resilient means biases said piston towards the opposite end of said low pressure cylinder and maintains a pressure on said reservoir thereby to maintain a full charge of fluid in said high pressure cylinder.

6. A device as set forth in claim 5 wherein said pas sageway opens into said high pressure cylinder at a location adjacent the end thereof which is adjacent said low pressure cylinder whereby, said passageway is closed upon movement of said plunger and said reservoir is not subjected to pressure obtained in said high pressure cylinder.

References Cited in' the file of this patent UNITED STATES PATENTS 2,335,748 Fowler Nov. 30, 1943

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