US2177158A - Pneumatic tool - Google Patents

Description

Oct 24, 1939.

w. A. SMITH, .1R

PNEUMATIC TOOL Filed May 23' 1938 /1/5 Arm/win Patented Oct. 24, 1939 PATENT oFFicE PNEUMATIC TOOL William A. Smith, Jr., Dayton, Ohio, assigner to The Buckeye Portable Tool Company, Dayton, Ohio, a corporation of Ohio Application May 23, 193s, serial No. 209,478

4 Claims.

This invention relates to pneumatic tools and more particularly to automatic valve mechanism for controlling the admission of air to the y cylinder to a piston type tool.

One object of the invention is to provide a pneumatic tool with an automatic valve which will be simple in construction and e'icient in operation.

A further object of the invention is to provide a valve of such a character that the action of the air on the movable valve member will move the same positively to the limit of its movement in either direction and will prevent the uttering of the valve member.

A further object of the invention is to provide a valve which may be easily manufactured and assembled and which will be compact in form.

Other objects of the invention may appear as the mechanism is described.

In the accompanying drawing Fig. l. is a longitudinal section taken through a pneumatic tool embodying the invention, on the lines I-I of Figs. 3 and 4; Fig. 2 is a transverse section taken on the line 2-2 of Fig. l; Fig. 3 is a transverse section taken on the line 3 3 of Fig. l; and Fig. 4 is a transverse section taken on the line 4 4 of Fig. l.

In the drawing I have illustrated one embodiment of my invention and have shown the same as embodied in a pneumatic hammer of a well known type. It will be understood, however, that the valve mechanism may take various forms and may be embodied in pneumatic tools of various kinds.

In the particular embodiment here illustrated the pneumatic hammer comprises a body the forward portion 5 of which constitutes a cylinder in which is mounted a piston or hammer 6, this hammer being arranged to strike the shank 'I of the tool mounted in the forward end of the cylinder. The rear portion of the body is here shown in the form ofr ar housing or cap 8 which is screw threaded onto the rear portion of a cylinder. Rigidly secured to this rear portion or cap is a handle 9 by which the tool may be supported and manipulated, and this handle is provided with an air conduit II] leading to the Valve mechanism, as will be hereinafter described. At one end the air conduit is provided with a means, such as a fitting I I, for connecting the same with a source of supply for air under pressure, in a well known manner. The handle is also provided with a manually operable master valve I2 for controlling the passage of air through the conduit IB, this valve being of a well known type.

'Ihe cylinder 5 is provided with longitudinal inlet conduits I3 which are connected at their forward ends by ports I4 with the forward end of the cylinder, in advance of the piston. These conduits extend through the rear end of the cylinder and are connected with the valve mechanism, as will be presently described. The cylinder is also provided with a series of exhaust conduits I5, there being in the present instance six of these conduits. The forward portion of each exhaust conduit is connected with the interior of the cylinder by ports I6 and I 'l spaced one from the other. The rear end of each exhaust conduit is connected by one or more ports I8 with a circumferential exhaust channel i8 having a series of openings 20 in the outer wall thereof.

The rear or cap portion of the body has that part thereof in the rear of the cylinder enlarged to form a cavity and in this cavity is mounted a valve unit ZI which is preferably circular in form and is of a diameter somewhat less than the diameter of the cavity in the cap so as to form between the valve unit and the circumferential wall of the cavity a circumferential passageway 22 which is in open communication with the air conduit Iii in thehandle 9. Preferably the conduitl Ii) is enlarged at its point of connection with the passageway, as shown at 23, to provide a better. distribution of the air in the passageway.

The valve unit comprises a front member or plate 2t, here shown as circular in form and as having. a central opening 25 in open communication with the rear end of the cylinder, and a rearwardly facing annular channel 26 surrounding the opening. A rear member or plate 21 is spaced a short distance to the rear of the front member 2li and is provided with a central opening 28 which communicates with the inlet conduits i3 of the cylinder, as will be presently described, and is also provided with a forwardly facing annular channel 29 which is arranged in opposed relation to the rearwardly facing channel 26 in the front member 24. Interposed between the outer portions of the front and rear members 24 and 2'! is an intermediate member 3U which is annular in form and which preferably has its inner edge projecting slightly into the space between the opposed annular channels of the front and rear members. This intermediate member isprovided with a series of substantially radial ports 3i which connect the circumferential passageway 22 with the annular channels 26V and 29. These three parts of the valve mechanism are rigidly connected one to the other tez and to the cylinder, as by means of dowel pins, 32, the pins being so arranged that the several parts can be assembled only in their proper relation one to the other and to the cylinder. Each stationary member is provided near the edge thereof with two openings, the corresponding openings in the three members being arranged in alinement one with the other and with' the respective inlet conduits I3, and thus provide extensions 33 of the inlet conduits. These extensions 33 are in open communication with the central opening 28 of the rear stationary member 21, this member being provided in the present instance with a transverse bore 34 which is in open communication with the opening 28 and with the extensions 33 of the respective inlet conduits.

A movable valve member 35 is mounted between the inner portions of the front and rear stationary members 24 and 27, so as to separate the openings 25 and 28 in said members, and the peripheral portion of this movable valve member projects into the space between the opposed annular channels 2E and 29 and has a snug sliding fit within the annular intermediate member 39. Preferably this annular intermediate member is provided with a circumferential peripheral groove 36, with which the ports 3l communicate, the front and rear walls of the groove having a series of notches 3'! to connect the same with the respective annular channels 26 and 29.. The peripheral edge of the movable valve member 35 is also preferably provided with one or more circumferential peripheral grooves 38 arranged in line with the groove 3l and the ports 3l. Thus the air entering the grooves 31 and 38 from the ports 3l will be so distributed as to materially reduce its turbulence as it passes through the notches 31 to the annular channels 26 and 29. The movable valve member 35 is of a thickness slightly less than the distance between those portions of the front and rear stationary members 24 and 21 adjacent the openings therein, so that it is capable of a slight fore and aft movement and when in engagement with one stationary member it will be spaced from the other Stationary member a distance suflicient to connect rthe annular passageway and opening of saidrother member. The contacting surfaces of the movable valve member and of the'stationary.` members are iinished to provide a close contact between the same which will prevent any appreciable passage of air between the movable member` and the stationary member with which it is in contact.

When the piston is in its foremost position, as shown in Fig. l, the valve member will ordinarily be in its forward position, that is, in contact with the stationary member 24, and the channel 29 of the rear member will be in open communication with the opening 28 in that member, which opening is in open communication with the forward end of the cylinder. Therefore, when the master valve is opened, the air will pass through the circumferential passageway 22 and ports 3l to the annular channel 29, thence to the opening 29 and to the forward end of thecylinder, thereby moving the piston rearwardly. When the forward end of the piston passes the foremost exhaust port I6 the air pressure thereon will be relieved and the piston will complete its rearward movement b-y momentum. The air which is compressed back of the piston will move the movable` valve member to its rearmost position so as to interrupt the communication between the annular channel 29 and opening 28 of the rear stationary member and to establish communication between the annular channel 26 and opening 25 of the front stationary member, thus admitting air to the rear end of the cylinder and imparting a forward movement to the piston. The rear end of the piston will pass the rear exhaust port I1 before the Vpiston has completed tis movement and this forward movement will be completed by momentum, thus causing that piston to strike the shank of the tool. When the forward end of the piston closes the exhaust port l5 the air in front of the piston will be forced rearwardly through the inlet conduits I3 and will act on the rear face ofthe movable valve member to move the samey forwardly, as soon as the exhaust port l 'l has been opened to relieve the pressure within the rear portion of the cylinder, thus again admitting air to the front end of the cylinder and causing the piston to be retracted. This cycle of operations is repeated with great rapidity so long as the master valve is open.

While I have shown and described one embodiment of my invention I wish it to be understood that I do Vnot desire to be limited to the details thereof as various modications may appear to a person skilled in the art. y

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent is:

l. In a pneumatic tool comprising a cylinder, and a piston in said cylinder, a valve unit including two stationary members spaced one from the other, having opposed annular channels and having openings communicating respectively with the opposite ends of said cylinder, an annular wall extending about the space between said stationary members on the outer side of said channels and having substantially radial ports leading to the space between said stationary members and communicating with said. channels, means for connecting said ports with a source of supply of air under pressure, and a disk valve member mounted between the inner portions of said stationary members for movement into and out of engagement with said stationary members alternately to interrupt the communication between the channel and the opening V,in the member with which it is in engagement and to establish communication between the channel and the opening in the other member.

2. In a pneumatic tool comprising a cylinder and a piston in said cylinder, a valve unit including two stationary members spaced one from the other, having opposed annular channels and having openings communicating respectively with the opposite ends of said cylinder, an annular wall extending about the space between said stationary members on the outer side of said channels and having substantially radial ports leading to the space between said stationary members, means for connecting said ports with a source of supply of air under pressure, a disklike valve member arranged betweenA said stationary members to separate the openings there.- in, extending into the space between the opposed channels and having peripheral grooves in line wtih the ports in said annular wall and communicating with said annual channels, said valve member being movable into engagement with said stationary members alternately to interrupt communication between the channel and the opening of that member with which it is in engagement and to establish communication between the channel and the opening in the other member.

3. In a pneumatic tool comprising a cylinder and a piston in said cylinder, a valve unit including two stationary members spaced one from the other, having opposed annular channels and having openings communicating respectively with the opposite ends of said cylinder, an annular wall extending about the space between said stationary members with its inner edge adjacent the outer side of said channel, a disk-like valve member slidably mounted within said annular wall and arranged between said stationary members to separate the openings therein, the adjacent edges of said annular Wall and said valve member having opposed peripheral grooves, and said annular wall having substantially radial ports leading to the groove therein and also having peripheral notches to connect said groove with said channels, and means for connecting the outer ends of said ports with a source of supply of air under pressure, said valve member being movable by the action of the air into engagement with said stationary members' alternately to interrupt communication between the channel and the opening in that member with which it is in engagement and to establish communication between the channel and the opening in the other member.

4. In a pneumatic tool comprising a cylinder and a piston in said cylinder, and having a `cavity at the rear end of said cylinder, a valve unit mounted in said cavity and spaced from the Wall thereof to provide a circumferential passageway, means for connecting said passageway with a source of supply of air under pressure, said valve unit including a front member having an opening communicating with the rear end of said cylinder and having a rearwardly facing channel surrounding said opening, a rear member having an opening communicating with the front end of said cylinder and having a forwardly facing annular channel surrounding the opening therein and arranged in opposed relation to the channel in said front member, an annular wall extending about the space between said front and rear members at the outer side of said channels and having ports connecting said circumferential passageway With said annular channels, and a movable valve member arranged within said annular wall to separate the openings in said front and rear members one from the other and slidably mounted for fore and aft movement with relation to the front and rear members to alternately establish and interrupt communication between the channels and openings of said front and rear members respectively, said valve member having peripheral grooves arranged in line with the ports in said annular wall, and said annular wall having notches to connect said grooves and said ports with said annular channels.

WILLIAM A. SMITH, JR.

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