US2781025A

US2781025A - Distributing valve means for elastic pressure fluid driven percussion tools

Info

Publication number: US2781025A
Application number: US418162A
Authority: US
Inventors: Ekstrom Gosta Ivar
Original assignee: Atlas Copco AB
Current assignee: Atlas Copco AB
Priority date: 1954-03-23
Filing date: 1954-03-23
Publication date: 1957-02-12
Anticipated expiration: 1974-02-12
Also published as: GB767167A; ES220784A1

Description

Feb. 12, 1957 G. l. EKSTRbM 3 DISTRIBUTING VALVE MEANS FOR ELASTIC PRESSURE FLUID DRIVEN PERCUSSION TOOLS Filed March 25. 1954 Fig/ IN V EN TOR.

United States Patent ce DISTRIBUTING VALVE MEANS FOR ELASTIC rr gss uun FLUID DRIVEN PERCUSSION T L Giista Ivar Ekstriim, Nacka, Sweden, assignor to Atlas gopco Aktiebolag, Nacka, Sweden, a corporation of weden Application March 23, 1954, Serial No. 418,162

8 Claims. (Cl. 121-19) This invention relates to improvements in distributing valve means for percussion tools having a cylinder and a hammer piston reciprocable in said cylinder under the action of an elastic pressure flu'id. Such valve means are provided for controlling the admission of said pressure fluid to one or more working chamber in the cylinder. One object of the invention is to provide a valve means of this type which are simple and cheap in manufacture, easy to assemble and disassemble, and make possible the formation of large valve throwing surfaces, so that a valve member forming a part of said valve means may be quickly and safely moved from one desired position to another. The invention involves valve means formed and arranged in such a manner that the designer has greater freedom than in conventional designs to form valve throwing surfaces and valve'holding surfaces of sizes which meet his demands. A further object of the a low resistance to the flow of pressure fluid to the working cylinder. A further object of the invention is to provide a valve means which makes possible a more eflicient utilization of pressure fluid than valve means of conventional design. A still further object of the invention is to provide a valve means which makes possible favourable starting conditions and a very gradual increase of the percussion work produced by the tool.

For these and other purposes we provide valve means including a valve member which controls the supply of pressure fluid to working chamber in the cylinder for producing the percussion stroke as well as the return stroke of the hammer piston, and including valve throwing surfaces acted on by the pressure fluid for moving the valve member to its difierent positions, one of said valve throwing surfaces, at least, being provided on a member formed separate from the valve member and movable in the valve chest for cooperation with the valve member for moving said member. Further features of the invention will be understood and explained hereinbelow in connection with t e description of a hammer rock drill according to the invention illustrated on the accompany ing drawing. This drill, however, should only be considered as an example and does not limit the scope of the invention as set forth in the claims. I

In the drawing Fig. 1 is a longitudinal section of a compressed air driven hammer rock drill provided with valve means according to the invention. Fig. 2 illustrates a valve member forming a part of said valve means in side elevation, and Fig. 3 is a side View of a tubular sleeve forming a further part of the valve means.

The compressed air driven hammer rock drill illustrated in the drawing consists of a cylinder 1, a valve chest 3, 4, 5, 27 in which a rifle bar 6 is mounted in conventional manner, and an intermediate portion 7 which together with a bushing 2 forms the lower end wall of the working cylinder. The portion 3, of the valve chest contains .a pawl and ratchet mechanism 9 cooperating with the rifle, bar 6 and of a design which is conventional in rock drills, for producing rotation of the drill steel (not illustrated).

' a passage (not illustrated) in the cylinder with the atinvention is to provide a valve means which produces 1 2,781,025 PiitentedFeb. 12, 1951 A hammer piston ltlis reciprocable in the cylindrical bore of the cylinder 1 and provided with a nut 11 in the piston head which in conventional manner fits and engages inclined splines 12 on the rifle bar 6. The front head and back head of the drill are not illustrated since they may be of any conventional design and do not form part of the present invention.

The head of the piston divides the cylinder bore in two working chambers, the first rear working chamber being designated 15 and the second forward working chamber 14. A port 16 in the cylinder communicates through mosphere forming an exhaust passage from the working chambers 'of the cylinder controlled by the piston head.

The valve chest portion 4 has a bore 24, in which a tubular valve member 17 fits with a sliding fit. The valve member 17, also illustrated in Fig. 2, is axially reciprocable between two annular valve seats 18 and 19, respectively, provided on the valve chest portions 5 and 4, respectively. The rear end of the valve member 17 is formed with a flange 26 extending radially outwardly and provided close to the periphery with annular sealing surfaces 21 and 22, respectively, on opposite axial faces of the flange, said sealing surfaces being arranged for cooperation with the valve seats 18 and 19, respectively. The valve member 17 is further provided with a cylindrical guide surface 23 which is guided in the cylindrical bore 24'with a large diameter in the valve chest portion 4, said diameter, however, being less than the inner diameter of the annular surface 22. The valve member 17 has a further cylindrical guide surface 25 of less diameter than the surface 23 movable with a sliding fit in a bore 26 in the valve chest portion 27 provided between the valve chest portion 4 and the cylinder 1. A tubular sleeve 28, Fig. 3, is arranged with a sliding fit on the cylindrical surface 25 and has a flange 29 directed radially outward-1y and cooperating with a sliding fit with a bore 13 in the valve chest portion 4. In the position of the valve member 17 illustrated in Fig. l the valve member together with an extension 44'of the valve chest portion 5 forms an annular stream-lined difiusor-shaped passage 30 which from the valve opening between the seat 18 and the valve surface 21 leads to the first working chamber 15 in the cylinder. The flange 20 and the opposed part 31 of the valve chest portion 5 are rounded so-as to form a streamlined inlet to the valve opening from a chamber 32 in the valve chest to which compressed air is supplied over a conventional main admission valve 33. 34 indicatesa valve holding surface on which the pressure of thefluid acts to hold the valve member 17 in engagement with the seat 19.

A control passage 35 is provided in the cylinder and communicates with the bore of the cylinder at a point which during the percussion stroke of the piston is uncovered before the percussion stroke is completed and before the piston uncovers the port 16 leading to the exhaust opening. The passage 35 communicates with a groove 36 in the valve chest portion 27 and also with a space 37 at the underside of the flange 29 of the sleeve 28. A space 38 in the valve chest on the upper side ofthe flange 29 communicates through a duct 39 with the atmosphere. The lower face of the flange 29 forms a valve throwing surface for moving the valve member 17 from the position illustrated in Fig. 1 towards the valve seat 18. When the hammer piston during the percussion stroke has moved so far downwardly that it uncovers the opening of the passage 35to the first W011i: ing chamber 15 the air-pressure in saidchamber-is transferred to the space 37 so that-the sleeve 28 is pressed upwardly and moves'the valve member 17 towards the seat 18. The annular portion on the valve member, 17 between the cylindrical surfaces 23 and 25 f orm at),

abutment. for-the; upperend face of the sleeve. 28. It is obvious that the valve throwing surface which in this case is the annular surface at the underside of the sleeve 28'and flange 2921s indicated by 40 in Fig.1 is materially larger th'an the counteracting valve holding surface 34. so that a quick and safe movement of the valve is ob.- tained before the piston during the percussion stroke 7 uncovers the port 16. A certain expansion of the pressure fluid in the working chamber 15 may consequently take place, which is of advantage with regard to the compressed air consumption of the drill.

When the valve member 17 has moved against the valve seat 18 compressed air is admitted to the second working chamber 14 below the hammer piston from the chamber 32 through a valve opening between the valve seat '19 and the sealing surface 22 through an annular groove 41 in the valve chest portion 4 and a passage 42 in the cylinder. After having delivered the blow the'hammer piston is returned towards the valve chest by the fluid pressure in the chamber 14.

7 When the piston uncovers the'exhaust port 16 during the percussion stroke the fluid pressure in the first work'- ing chamber 15 is reduced towards atmospheric pressure and, consequently, the pressure in the space 37 is also reduced. During the return stroke of the piston air is compressed in the working chamber 15 and an annular recess 43 in the piston head momentarily brings the passage 35 into communication with the exhaust 1o so that compression pressure in working chamber 15 is not transferred to the space 37. When. the piston is close to the valve chest portion 27 the compression pressure is so large that the pressure acting on the valve member 17 on a surface 46 throws the valve member forwardly in the drill and opens the supply of live air to the work.- ing chamber 15. The working chamber 14 is then vented to the atmosphere and a new percussion stroke may take place, a described hereinabove.

The embodiment of the invention described hereinabove and illustrated on the drawing should only be considered as an example and the details of the iriven: tion may be modified in several different ways within the scope of the following claims. The invention also in,- cludes valve members forming parts of the valve means. The valve throwing member 28, 29 may be press fitted or otherwise secured, on the valve member 17.

What I claim is:

1. In a percussion tool, a cylinder, a hammer piston reciprocable in said cylinder under the action of an elastic pressure fluid, a first working chamber the cylinder which said pressure fluid acts to produce a percussion stroke of said piston, a second working .chamberin the cylinder in which the pressure fluid acts to produce a return stroke of the piston, a valve chest, means for supplying pressure fiuid to said valve chest, twp valve seats in the valve chest, a valve member having a portion disposed between said valve seats .and movable in the valve chest from one of said valve seats to the other, i. e. from a position in which pressure fluid is admitted by said valve member to said first working chamber to .a position in which pressure fluid is admitted by thevalve member to said second working chamber, valve throwing-mean comprising pressure'fluid actuated valve throw.- ing surfaces for moving the valve member from .one of the valveseats to the ,other and vice versa, and a valve throwing member separate ,from the valve-member and carrying one of said valve throwing surfaces and disposed .so as to engage the valve member and having a stroke approximately equal to the stroke of the valve member for moving the valve member towards one of the valve seat-s, said other valve throwingssurfaceibeing provided on'saidvalvemember. if i i 2. In-a percussion tool, a cylinder, a hammer p'i ton reciprocable'insaid.cylipder undert v U "in Q ang ,s iC pressure fluidpafirst working chamberin the cylinder in which said pressure. fluid acts to. producea percussion stroke of said piston, a second working chamber in the cylinder in which the pressure fluid acts to produce a return stroke of the piston, a valve chest, means for supplying pressure fluid to said valve chest, two annular valve seats in the valve chest, an annular valve member h ving a tubul r por io a dmovable. n the a ve che from a position in which pressure fluid is admitted by said valve member to said first working chambenthrough said tubular portion to a position in which pressure fluid is. admitted by he val member to 5 se ond not ing chamber, said valve member comprisinga radially outwardly extending flange on said tuhular portion disposedbe tween said valve seats and having annular sealing surfaces at axially opposite faces gooperating with said valve seats, valve throwing means comprising pres sure fluid actuated valve throwing surfaces formoving the valve member from one of the valve seats to the other and vice versa, and an annular valve throwing member formedseparate from the valve member carrying one of said valve throwing surfaces and movable in thevalve chest into engagement with said valve member for moving the valve member towards one of the valve seats, said other valve throwing surface being provided on said valve member.

3. In a percussion tool, a cylinder, a hammer piston reciprocable in said cylinder under the'action of an elastic pressure fluid, a first working chamber in the cylinder in which said pressure fluid acts to produce a percussion stroke of said piston, a second working chamber in the cylinder in which the pressure fluid acts to produce a return stroke of the piston, a valve chest, means for supplying pressure fluid to said valve chest, two annular valve seats in the valve chest, an annular valve member having a tubular portion extending towards said first working chamber and movable in the valve chest from a position in which pressure fluid is admitted by said valve member to the first working chamber through an unobstructed passage formed in between said tubular portion and an extension of the valve chest to a position in which pressure fluid is admitted by the valve member to said second chamber, said valve member comprising a radially outwards extending flange on said tubular portion at the inlet end thereof having annular sealing surfaces on axially opposite faces cooperating with said valve seats,

, valve throwing means comprising pressure fluid actuated valve throwing surfaces for moving the valve member from one of the valve seats to the other and vice versa, and a valvethrowing member formed separate from the valve member and carrying one of said valvethrowing surfaces and movable in the valve'c h'est into engagement with said valve member for moving the valye'member towards one of the valve seats, said other valve throwing surface being provided on said valve member. I

4- In a r enti n 91 a c l nder, a h mm P o reciprocable in said cylinder under the action of an elastic pressure fluid, a first working pharnber in the cylinder. in

said pressure fluid act to produce a percussion stroke of said piston, a second working chamber in the cylinder in w hich the pressure fluid acts to producea return stroke of the piston, avalve chest, means for supplying pressure fluid to said valve chest, two valve seats i h a e c e t a a e m mbe m vab e i the a e ch an m i n a b la Port n v a mi s flt i a passage leading to said first working chamber and a ad l y out ard y di e ted fla e t heil let end of a tubula p n fo min a ealin su fac coope atins w th 9n; 9 Sai valv e ts p s to he a m ss n o pressur fluid throu h he tubu a r r on to the first a ve as 18 sutur a ent ve assu e w th said. valve member for mo ing the valve memberfrom one of the valve seats to the other and vice versa, a piston controlled exhaust opening in the cylinder, and a passage in the cylinder leading from a point of the working chamber uncovered by the piston on the percussion stroke before said exhaust opening is uncovered to a space in the valve chest open to one of said valve throwing surfaces.

5. in a percussion tool, a cylinder, a hammer piston reciprocable in said cylinder under the action of an elastic pressure fluid, a first working chamber in the cylinder in which said pressure fluid acts to produce a percussion stroke of said piston, a second working chamber in the cylinder in which the pressure fluid acts to produce a return stroke of the piston, a valve chest, mean for supplying pressure fluid to said valve chest, two valve seats in the valve chest, a valve member movable in the valve chest and comprising a tubular portion and a radially outwardly directed flange at one end of said tubular portion forming at least one sealing surface cooperating with one of said valve seats to control the admission of pressure fluid to the first working chamber, means cooperating with said other valve seat for controlling the admission of pressure fluid to said second working chamber, valve throwing means and valve holding means comprising pressure fluid actuated valve throwing and valve holding surfaces operably associated with said valve member for moving said valve member towards one of said seats and for holding it oft the other seat, respectively, said valve throwing surface being larger than said valve holding surface, a piston controlled exhaust opening in the cylinder, and a passage in the cylinder leading from the first working chamber to a space in the valve chest open to said valve throwing surface.

6. In a percussion tool, a cylinder, a hammer piston reciprocable in said cylinder under the action of an elastic pressure fluid, a first working chamber in the cylinder in which said pressure'fluid acts to produce a percussion stroke of said piston, a second working chamber in the cylinder in which the pressure fluid acts to produce a return stroke of the piston, means for supplying pressure fluid to said tool, valve means for controlling the admission of pressure fluid to said first and second'working chambers, an annular valve member forming a part of said valve means and controlling the admission to the first working chamber, valve throwing means and valve I movable into'engagement with said valve member to -throw said valve member to closed position.

7. In a percussion tool, a cylinder, a hammer piston reciprocable in said cylinder under the action of an elastic pressure fluid, a first working chamber in the cylinder in which said pressure fluid act to produce a percussion stroke of said piston, a second working chamber in the cylinder in which the pressure fluid acts to produce a return stroke of the piston, a valve chest, means for supplying pressure fluid to said valve chest, two annular valve seats in the valve chest, a valve member movable in the valve chest and comprising a tubular portion forming therein a passage leading to said first working chamber and a radially outwardly directed flange at the inlet end of said tubular portion forming a sealing surface cooperating with one of said valve seats to control the admission of pressure fluid through the tubular portion :to the first working chamber, means on said valve member cooperating with said other valve seat to control the admission of pressure fluid to said second working chamber, valve throwing means and valve holding means comprising pressure fluid actuated valve throwing and valve holding surfaces, respectively, an abutment on said valve member, an annular valve throwing member slidable on said tubular valve member and carrying one of said valve throwing surfaces and movable in the valve chest into engagement with said abutment for moving the valve member towards one of said valve seats, said valve throwing surface being larger than said valve holding surface serving to keep the valve member off said last named seat, and a passage in the'cylinder communicating with said first Working chamber and leading to a space in the valve chest in which said annular valve throwing member is movable so as to let the fluid pressure in said first working chamber act on the valve throwing surface on the valve throwing member to move the valve member to closed position before the end of the percussion stroke.

8. A valve means for distributing an elastic pressure fluid in a percussion tool having a reciprocable hammer piston operated by said elastic pressure fluid, a tubular body forming a portion of said valve means, a radially outwardly directed flange at one end of said tubular body, annular sealing surfaces on axially opposite faces of said flange, an external cylindrical surface on the tubular body, an annular abutment at one end of said cylindrical surface, a tubular sleeve fitting said cylindrical surface and cooperable at one end with said abutment to move the tubular body, and an annular radially outwards directed flange on said sleeve forming a .valve throwing surface for moving the tubular body in one direction.

References Cited in the file of this patent UNITED STATES PATENTS 1,967,499 Curtis July 24, 1934 2,180,564 Terry Nov. 21, 1939 V FOREIGN PATENTS 338,696 Great Britain Nov. 27, 1930