US 2627248 A
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2,627,248 ITI-I IMPROVED VALVE ACTUATING MEANS 2 SHEETS-SHEET 2 NVN`T \Q\' wheat Q4. Shouf; @Mgg .ma/QQ@ r4/1%` fh-romezvf E. H. SHAFF PRESSURE FLUID ACTUATED TOOL W Feb. 3, 1953 Filed Nov. 50, 1948 Patented Feb. 3, 1953 PRESSURE FLUID ACTUATED TOOL WITH IMPROVED VALVE ACTUATING MEANSI Ernest H. shan, spring Lake, Mich., assignmto Keller Tool Company, Grand Haven, Mich., a`
corporation of Michigan Application November 30, 1948, Serial No. 62,674
2 Claims. (Cl. 121-12) The present invention pertains in general to pressure iiuid actuated tools and more particularly to Ysuch tools embodying a reciprocating member such, for example, as a portable filing tool. I
It is an object of the invention to provide in a pressure fluid operated too1 having a reciprocating piston or the like, novel valve means for controlling the admission and exhaust of fluid which effectually eliminates stalling of the too1 or tendency to stall.
A more specic object is to provide means utilizing movement of the reciprocating member of the tool to initiate movement of a valve element and utilizing the action of pressure fluid to complete such movement.
A further object is to provide novel means whereby the length of the stroke of the reciprocating element can be varied.
Still another object lies in the provision of a novel pressure iluid actuated tool of the aforesaid character which is eiheient in operation and permits of economical manufacture.
The objects of the invention thus generally set forth, together with other objects and ancillary advantages are attained by the construction and arrangement shown by way of illustration in the accompanying drawings in which:
Figure 1 is a central longitudinal section through a ling tool embodying the instant invention.
Figure 2 is a fragmentary central longitudinal section simil-ar to Fig. l but illustrating different relative positions of the tool components.
Fig. 3 is a fragmentary central longitudinal section taken substantially in the plane of line 3--3 in Fig. 1 but showing still other relative positions of too1 components.
Fig. 'i is a fragmentary central longitudinal section similar to Fig. 3 but on an enlarged scale and showing still different component relationships.
Fig. 5 is a transverse section taken substantially in the plane of line 5-5 in Fig.- 2.
Fig. 6 is a transverse section taken substantially in the plane of line 6-6 in Fig. 4.
While the invention is susceptible of various modiilcations and alternative constructions, there is shown in the drawings and will herein be described in detail the preferred embodiment, but it is to be understoodthat it it not thereby intended to limit the invention to the form` disclosed, but it is intended to cover all modifications and. alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims. I
The embodiment of the invention shown in the accompanying drawings comprises a portable filing tool. However, itwill be readily apparent that the invention can be incorporated in other similar pressure fluid operated tools as Well. As shown, the instant too1 includes an elongated housing or barrel I0 dening a cylinder I2, the rear end of which is closed by la too1 head |41. The latter is secured. to the barrel `by a collar I3. The forward end of the barrel I0 has a. bore therethrough coaxially disposed with respect to the cylinder I2 within which is received a linerA Disposed Within the barrel is the reciprocating; member of the too1 which, in this instance, in-
cludes a piston I6 which is received in the cyl-y inder I2 eiectually dividing it into forward andi rear chambers I8 and I9, respectively, and a. piston rod I'I. The piston is rigidly secured'. to the rear end of ,the` rod I'I and the latterv extends forwardly therefrom into the liner I5.. The piston rod I1 is of tubular form having an. axial bore Ila therethrough, the outer end of which is adapted to receive the shank of a ille F, and a set screw S is provided adjacent the outer end of the piston rod Il for engagement with the shank to clamp the same in the bore I la. The barrel I0 and the liner I5 are` provided with registering slots I0a and I5a, respectively, for the reception of the head of the set screw. The slots thus serve as a guide for the` reciprocating member and the le F secured thereinI preventing rotation of the same relative to the barrel I0.
Pressure fluid is suppliedto the tool from any suitable source (not shown) by way of a fitting 20 received in a passage 2| in the tool head I4 and is under the control of a throttle valve 22. The throttle valve 22 is disposed in a transverse bore 24 adjacent the rear end of the tool head I4. It includes a sleeve 25 closely fitted in the bore 24, and a spring-biased plunger 26 shiftable axially within the sleeve. The throttle valve is operated by a leverl 28 pivoted for engagement with the end of the plunger 26 and conveniently disposed along the tool head for actuation by the hander fingers of an operator using the tool.
In accordance with the invention, a novel reversing valve mechanism 30 is provided for controlling `the admission and exhaust of uid to the forward and rear-cylinder chambers I8 and I9 to produce reciprocation of the piston and vwhich is constructed and varranged `so that stalling or tendency of the too1 to stall is eifectually eliminated. More specifically, the valve mechanism 30 utilizes the movement of the reciprocating member of the too1 through the medium of springs to initiate shifting ofa movable valving element thereof, such shifting being completed by the ac- 3 tion of live pressure iiuid on the movable valving element.
In the present instance, the valve mechanism 30 includes an annular bushing 32 having an axial bore 33 slidable within which `is a sleeve or spool valve 34 and a valve stem 36. To receive the valve mechanism 30 the tool head I4 is provided with a stepped bore 31, the outer end of which is of a diameter to snugly receive the bushing 32, the latter being retained therein by means of an end plate 33. The end plate 38 has a central aperture 39 therein to permit passage of the valve stem 36 but which is of a diameter less than th'at of the valve 34. Thus, the end plateserves add` tionally as a forward limiting abutment for the valve 34. The inner end of the stepped bore 3l is also of a diameter less than that of the valve 34; thus, there is provided a shoulder 31a which' serves to limit rearward valve movement.
Pressure fluid is supplied to the valve mechani-smA 30 from the throttle valve 22 by way'of a passagev 40 in the tool head i4 which registers with apassage 454 inv they bushing 3 2. To afford communication with the interior of the bushing, i. e. the bore 3.3,V and hence with the valvev 34, the bushing 32 is provided with a pair of transverse slots 42 and 43 which areof a depth to intersect the passage 4l and the axial passage 33 through thevbushing'; rihe transverse slots 42 and 43 are equally spaced from the ends of the bushing.
To permit exhaust of spent fluid, the bushing 32 has provided therein a pair of slots 44 and 43 which are located in the sidev of thejbu'shing opposite the slots 42 and' 43, but are disposed in more closelyspa'c'ed relation. These slots too inu tersect theY axial passage 33 through the bushing andcommunicate with the atmosphere by w'ay of apassage`43 in the bushing which registers with an exhaust passage 41 in the tool head i4@ The valve 34"is 'of' a length less than that ofthe bushing 32', such length being determined by the spacing of the slots 42 and 43 tov the' end't'hat when the valve is in its forwardV position the slot 43 yis fully'unco'vered and the slot 42 is closed, and conversely, when it is in its rear positionthe slot 4'3Y is closed and the slot 42v is fully opened. Centrally of' its limit positions the valve closes both slots'.
Intermediate its' ends the valve 34 isprovided with two peripheral grooves 48" and 49 which; in turn, communicate with the ends of the' valve by way of pairs of passages 56 and 5l, respectively. The grooves are disposed so that with the valve in its rearmost position, the groove 43 registers with the bushing slot 45" and the slot 44'is closed. Conversely, with the valve'in its forward position the slot 45 is closed and the groove 43- registers with the slot 44.
With the valve 34'in its rearmost position as shown in Fig. l, pressure iiuid is admitted from the supply passages`4' and 4l through the vbushing slot 42 into the forward end" of the'bore 33 andthence by way of the'end'plate aperture 36 into the cylinder chamberV lbehind'thepiston i6 to force the 'piston' onits'forwardstrolie At the same time spent fluid from the chamber i3 ahead of the piston lis exhausted. For this purpose, the valvestem 36'is'made of tubular form and is extended within the piston rod bore ila through the piston4 I6. It has a passage 52 therethrough which communicates with the chamber i3 by means ofports 53 adjacent the forward end of the stem 36.' The passage 52 is connected with the chamber comprising the inner end of the bore33 by wayof ports 33 disposed adjacent. the rear end" ofthe stem.' Fromthe latter chamber spent fluid passes by way of the passages 5| and rthe groove 49 in the valve 34, the slot and the passage 46 in the bushing 32 and thence to the atmosphere through the exhaust passage 41 in the tool head I4.
In carrying out the invention; the piston rod Il together with the valve stem 36 through the use of springs is utilized to initiate shifting of the valve 34, this initial movement being sufficient to carry the valve through its intermediate or stall position wherein it closes oi both the supply slots 42'and 43. To this end the valve stem has fixed therein adjacent its ends laterally Y extending pins Eiland 6|, respectively. The projecting ends of the pin are received in a longitudinally extendingslot 62 in the piston rod I1, the length of which is equal to the full stroke length of the tool. Supported by the stem 36 and interposed between the pin 6I and the rear end of, the valve' 3 4 is a spring 6 4, .Adjacent the forwardend of the v valve is' asimilar spring 65 which is maintained vin such position by a snap ring 66, the latter in turn being received ina peripheral groove provided therefor in thestem 34. As the reciprocating member of the tool approachesl the limit of its lforwardstrcgke, the valve 34 being in the position v shown ,in Fig., 1 and pressure iiuidbeing admitted and spentiiuid being exhausted as hereinbeforeset'` forth; the pin Bil is engaged by the rearmend of the' slotV 62 thus moving the stem 36 forwardly, ySuch motioncauses the spring 64 to become-,compressed until it exerts a force on the'reary end o f the valve 34 greater than that exerted on the forward end of the valve by live pressure iiuid entering from thev slot 42. Forward movement of thevalve is therefore initiated to close off theslotu42 (Fig.v 2) and then partially uncover the slot,43 `(Figfi). Pressure fluid ,entering through.'y the slot 4,63 acts on the rear end of the valve 34 to complete its forward movement.
With the valve 34 in its full forward position, pressure fiuid is admitted` to move the piston on its yrearward stroke by way of theslot'43, the chamber comprising the rear end of the bore 31, the valve stem ports 54, Dassagezfand ports 53 into the cylinder chamber I8, Spent pressure fluid is exhausted fromthe chamber l!!l by way of the end plate aperture 39, the valve passages 53 and groove 48, the bushing slot 44andpas'- sage 43 to the exhaust passage 41 in the tool head I4'. v, .y
As the reciprocating Vmember approaches the limit of its rearward stroke, the pin 60 is engaged by the forward end. of' the slot |52,V thus moving the stem 36 rearwardly compressingithe spring 65 until it exerts a force on the forward en d of the valve 34 greater than that: exerted on its rear end by the actio'nof livepressureguid entering by way of the slot 43. Rearward movement of the valve is thus begun to close oi the slot 43 and then to partially uncover, the slot 42. Pressure fluid enteringby way Vof the slot'42 then acts on the forward .end rof thevalve and completes its rearward movement. p
The valve 34 is thus again. in the position shown in Figpl permittingthe cycle of operation, including a complete forward and rearward stroke of the reciprocating member, to be repeated.
Anotherimportan't?feature of the present in# vention liesliriV theprovision of'meansfor shortening the length of the strokeof the reciprocatlng member of the tool, thus lpermittingits use in places where a long stroke tool 'fcould notbe used. To this end, the means provided is effective to produce a change of time relation between the reciprocating member and the shifting of the valve mechanism 30. In other terms, by shortening the length of travel of the reciprocating member relative to the valve stern 36, the latter is actuated sooner thus initiating an earlier shift of the valve 34. In the present instance, this is accomplished through the provision 0f an adjusting screw 10, which is disposed intermediate the ends of the piston rod bore Ila behind the shank of the file F. Normally the screw is positioned so that it terminates just short of the slot 62, so that full use is made of the available lost motion in the pin and slot connection B0, 62. By moving the screw rearwardly, its end becomes positioned to engage the end of the valve stem 31 as the reciprocating member moves on its rearward stroke. Upon its engagement with the end of the valve stein a rearward movement of the stem 36 is produced thereby compressing the spring 65 with the resulting rearward shift of the valve 34 as previously described. The engagement of the screw and the valve stem thus takes the place of the engagement of the pin 60 and the end of the slot 62.
It will be apparent that this action results in the accomplishment of a complete cycle of operation, a forward and a rearward stroke, in a shorter length of time than with a longer or full stroke length. In other words, with the pressure fluid supply remaining constant, as the stroke length is shortened, the frequency of strokes is increased. Thus the filing speed remains substantially constant, i. e. the same amount of le surface passes over a given point on a workpiece in the same time interval.
From the foregoing, therefore, it can be seen that stalling or any tendency to stall is effectually eliminated in a pressure fluid actuated tool constructed in accordance with the present invention. By utilizing movement of the reciprocating member of the tool, through the medium of springs, the valving element controlling the admission and exhaust of fluid is prevented from coming to rest in a position in which the pressure fluid supply to both ends of the tools cylinder is interrupted. The provision of means for varying the stroke length of the tool While maintaining a substantially constant filling speed enhances the tools versatility. And the simplicity of construction and arrangement of its components permits economical manufacture.
I claim as my invention:
1. A pressure fluid actuated tool comprising, in combination, a housing dening a cylinder and a valve chamber coaxially alined with said cylinder, a piston disposed within said cylinder, a piston rod rigid with said piston, a valve including an annular bushing coaxially disposed with respect to said cylinder within said valve chamber and having a supply passage therein for communication with a source of pressure fluid and an exhaust passage therein for communication with the atmosphere and also having sets of supply and exhaust ports therein affording communication betwen said bushing passages and the interior of said bushing, a hollow valving element shiftable within said bushing between limit positions for alternately connecting said sets of ports with said cylinder on opposite sides of said piston to effect reciprocation thereof, a hollow valve stem having one end extending axially through said valving element, a pair of springs supported on said stem on opposite sides of said valving element, and means supported on the other end of said stem and engageable by said piston rod so that as said piston and rod approach the limits of a stroke said means is engaged to move the stem in the direction of motion of the rod to compress one of said springs whereby shifting of said valving element is initiated to close off one of said sets of supply and exhaust ports and partially open the supply port of the other of said sets of ports, pressure fluid admitted through the latter port acting on said valving element to complete its shift into its opposite limit position, said hollow valve stem affording communication between one of said sets of ports and one end of said cylinder.
2. A pressure fluid actuated tool comprising, in combination, a cylinder, a piston disposed within said cylinder, a hollow piston rod rigid with said piston and having a longitudinal slot therein intermediate its ends, a valve including an annular bushing fixed in said tool head bore in coaxially alined relation with said cylinder having a supply passage therein for communication with a pressure fluid source and an exhaust passage therein for communication with the atmosphere, said bushing also having sets of supply and exhaust ports therein affording communication between said bushing passages and the interior of said bushing, a hollow valving element shiftable within said bushing between limit positions for alternately connecting said sets of ports with said cylinder on opposite sides of said piston to effect reciprocation thereof, a valve stem having one end extending axially through said valving element and the other end received in said piston rod, a pair of springs supported on said stem on opposite sides of said valving element, a pin fixed adjacent the other end of said stem and received in said piston rod slot and normally engageable in the ends of the slot as the piston approaches its stroke limits to move the stem in the direction of motion of the rod to compress one of said springs whereby shifting of said valving element is initiated to close off one of said sets of ports and partially open the supply port of the other of said sets of ports, pressure fluid admitted through the latter port acting on said valving element to complete its shift into its opposite limit position, and an adjusting screw supported in said piston rod and movable axially therein to engage the end of said stem prior to the engagement of the end of the piston rod slot and pin whereby the stroke length of the piston and rod can be shortened.
ERNEST H. SHAFF.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 475,776 Johnson May 31, 1892 859,568 Hiester Oct. 29, 1907 882,025 Spoelstra Mar. 17, 1908 1,020,003 Williams Mar. 12, 1912 1,094,811 Reagan et al Apr. 28, 1914 1,767,214 Kelly June 24, 1930 2,072,445 Erling Mar. 2, 1937 2,406,747 Davis Sept. 3, 1946 FOREIGN PATENTS Number Country Date 822 France Nov. 29, 1887