US3901130A

US3901130A - Valve arrangement for the working cylinder of a pneumatically operated stapler

Info

Publication number: US3901130A
Application number: US409564A
Authority: US
Inventors: Wilfried Lange
Original assignee: BUKAMA GmbH
Current assignee: BUKAMA GmbH; BUKAMA HANNOVER GmbH
Priority date: 1972-10-27
Filing date: 1973-10-25
Publication date: 1975-08-26
Anticipated expiration: 1992-08-26
Also published as: DE2252735A1; IT1045866B; DE2252735C3; DE2252735B2; GB1388345A

Abstract

A valve arrangement of a pneumatically operated stapler comprising one or a plurality of annular valve chambers with one or a plurality of elastic, radially deformable rings. An additional elastic, radially deformable ring or gasket is mounted underneath the working cylinder. The outer rim of which gasket communicates via a channel with an adjoining chamber of the working cylinder and the inner rim serves as a closing member for the outlet opening of the working cylinder.

Description

United States Patent 11 1 Lange 1 1 Aug. 26, 1975 [54] VALVE ARRANGEMENT FOR THE 3,392,632 7/1968 Volkman v 91/457 WORKING CYLINDER OF A 3,396,636 8/1968 Bade 91/399 3.680582 8/1972 Pauliukonis. 25l/DIG. l PNEUMATKALLY OPERATED STAPLER 3.715.069 2/1973 OConncr 227/130 [75] Inventor: Wilfried Lange, Altenhngem 3,788,195 l/l974 Langc 227/130 X Germany [73] Assignee: Bukama Gmbl-l Hannover, Primary Examiner-Irwin C. Cohen Hemmingen-Westcrfeld Germany Attorney, Agent, or Firm-Allison C. Collard [22] Filed: Oct. 25, 1973 [21] Appl. No: 409,564 [57] ABSTRACT A valve arrangement of a pneumatically operated stal l Forelgn Application Pnorlty Data pler comprising one or a plurality of annular valve Oct 27, 1972 Germany 2252735 chambers with one or a plurality of elastic, radially deformable rings. An additional elastic, radially deform- [52] U.S. Cl. 91/461; 91/399; 227/130 able ring or gasket is mounted underneath the working [51 Int. Cl.'- F15B 11/08; FlSB 13/042 cylinder. The outer rim of which gasket communicates [58] Field of Search 91/399, 23, 402, 367, 461, via-a channel with an adjoining chamber of the work- 91/304; 227/130 ing cylinder and the inner rim serves as a closing member for the outlet opening of the working cylin- [56] References Cited der;

UNITED STATES PATENTS 3 Cl 4 D F 3,304,872 2/1967 English 137/525 x rawmg gums All PATENIED mczsms sum 1 OF 4 sum 3 0F 9 [III/II Mil? A ENE III/14mm 2 27 i IM VALVE ARRANGEMENT FOR THE WORKING CYLINDER OF A PNEUMATICALLY OPERATED STAPLER This invention relates to a valve arrangement for the working cylinder of a pneumatically operated stapler or other percussion machine. particularly of a stapler controlled by an auxiliary valve having in its compressed air conducting channel one or a plurality of annular valve chambers provided with one or several flexible rings deformable in radial direction. the outer rims of which rings constitute control pressure areas that are subject to be affected by the auxiliary valve and the inner rims of which constitute closing members for the compressed air channel.

For venting the backstroke or return motion chamber of the working cylinder of a pneumatically operated stapler it was customary heretofore to use both spring-loaded valves and slide members. In one of the prior art outlet a valve arrangement according to the US. Pat. No. 3.396.636 a cylindrical passage opening of an annular elastic buffer mounted at the bottom of the working cylinder is provided with a springloaded return or check valve which is being held open by its biased spring during the stroke of the working piston and which ventilates the backstroke space. The working piston in its lower dead center position strikes the buffer and seals off. in this connectiornits passage opening. Simultaneously compressed air passes from the adjoining chamber through the radial bores of the working cylinder into the backstroke chamber at its inferior or foot side and actuates the check valve for closing purposes whereby the air from the adjoining chamher is being sealed off against the ambient air and the working piston returns to its initial position. The check valve is controlled in this connection essentially in a mechanical manner by way of the stroke ofthe working piston. subjecting it to extensive mechanical wear and tear.

A slide valve gear or control of the aforementioned type has been disclosed by way of the German Pat. Specification No. 1.997.069. Said control means oper ates on the outlet opening of the backstroke chamber of the working cylinder.

By means of a slide control of this type the outlet opening of the working cylinder is no longer controlled by the mechanical stroke exerted when the working cylinder is in its lower dead center position, rather the control is performed completely pneumatically so as to provide for longer durability than can be had by the use of a spring-loaded check valve. For tools operating at a high stroke rate and which require. therefore, very short switching times slide valve controls can be employed to advantage only within a very restricted range of application. The inertia forces alone set limits to the use of slides for the control of the outlet openings in tools having a high stroke rate. Additionally. slide controls or gears are not capable of making on the spot available for cross sections for attaining the high stroke rate. as is often required. Due to this fact also. the realm of application for slides is further restricted.

' It is an aim or object of this invention to provide the valve arrangement for the outlet opening of the backstroke chamber of the working cylinder for tools of the aforementioned type in a manner such that large cross sections can be cleared instantaneously and extremely short switching times may be obtained.

This aim and object of the invention is attained according to the invention by the arrangement of an additional elastic. radially deformable ring in an annular groove of the tool housing underneath the working cylinder. the outer rim of said ring forming a control pressure area and its inner rim serving as closing or shut-off member for the outlet opening of the working cylinder. The outer rim of the elastic ring may both be connected via a channel to an adjoining chamber of the working cylinder and. also. via a channel followed by a tube. as the case may be. to the housing bore of the auxiliary valve for the control of the compressed air supply into the working chamber of the working cylinder. It is of particular advantage to arrange a throttle in the channel leading to the outer rim of the elastic ring so as to delay the working medium flowing therein.

According to the invention. the interposition of the elastic ring. e.g. in the form of an O-ring provides for clearing a large cross section. so as to allow the working medium located during the working stroke underneath the working piston to be discharged immediately. An elastic ring of this type has but little mass. which is essential for obtaining very short switching times. Moreover. it is to be observed that the movement of a control member of this type is not effected in the direction of motion of the working cylinder but radially and. hence. symmetrically to the direction of motion of the piston. Vibration or verberation and the concomitant slight motion of the tool is therefore entirely obviated.

The invention will now be described by way of example with reference to the attached drawings. in which:

FIG. 1 is longitudinal section through the working cylinder and the housing of the stapler enclosing said working cylinder. with the working cylinder in its initial or starting position;

FIG. 2 is a longitudinal section according to FIG. I with the release lever in its retracted position and the working cylinder at the moment of striking the impact buffer;

FIG. 3 shows the same operational position as FIG. 2. the gasket however in a different position after the stroke imparted by the working cylinder to the impact buffer. and

FIG. 4 illustrates the connection of the gasket to the control channel of the intake valve.

The pneumatically operated stapler is provided with a handle-type housing I enclosing an compressed air reservoir 2 connected to a compressed air conduit and containing in its forward portion 3 a working cylinder 4 wherein a piston 5 is mounted for reciprocating movement. The piston 5 is provided at its lower surface with a prolongation 6 to which a driving blade or ram 7 is connected penetrating the cylinder bottom 9 which carries an elastic. annular buffer 8 and which ram 7 drives. during its working stroke. a staple. nail or the like from a magazine 10 into a workpiece (not shown The compressed air reservoir 2 encloses the upper portion of the working cylinder 4 the lower part of which may possibly be surrounded by an adjoining chamber closed off by way of an intermediary wall II. and communicating therewith by means of

passages

13 and 14.

The upper end of the working cylinder 4 forms to-. gcther with the upper housing portion 15 an annular channel 16 which communicates via a funnel-shaped groove 17 with the reservoir 2. An annular valve chamber 18 is arranged in the inner wall of the housing.

which wall defines said annular channel 16. Two concentric and elastic O-rings 19 are disposed in said valve chamber 18 which communicates via a control channel 20 with the auxiliary valve 21 having its plunger 22 penetrate into the compressed air reservoir 2 and mounted so as to be snugly guided in a bore 23 of the housing portion 24. The lower end of the plunger 22 rests on a manually operative release lever 25 mounted for pivotal movement about a pinion 26 attached to the housing portion 24. The housing bore 27 of the auxiliary valve 21 communicates via a venting channel 28 as well as via a bore 30 provided in the housing cover with the ambient air. The annular valve chamber 18 is also vented via a venting channel 31 and a bore 32 of the housing cover 29. Above the annular valve chamber 18 there is provided a turned groove 34 containing an elastic Oring 33. This groove 34 communicates via a channel 35 with the housing bore 27 of the auxiliary valve 21. The annular channel 16 surrounding the upper end of the working cylinder 4 communicates via a groove 36 of the housing cover 29 with ambient air. On the housing cover 29 a protector cap 37 has been mounted which defines therewith a venting channel 38. A magnet 39 has been embedded on the lower surface of the housing cover 29. This magnet 39 maintains the piston 5 in the starting position shown in FIG. 1. In the valve plunger 22 there is an axial bore 40 which connects. depending on the position of the plunger 22, the compressed air reservoir 2 to the valve chamber 18 or to the channel 33. Reference numeral 41 stands for the slot-shaped inlet openings at the upper end of the working cylinder and 42 designates the interst-ices between the concentrically spaced ()-rings 19.

An annular groove for receiving an elastic ring in the instant case. an ()-ring 51 has been provided underneath the working cylinder 4 in the housing 1 of the tool. According to the invention. this ()-ring 5] is to clear the passage of the working medium during the working stroke to the outlet openings 52. A channel 53 has the annular groove 50 (FIG. 1) communicate with the adjoining chamber 12. A throttle has been interposed in channel 53 so as to delay the current flow. A communication between the elastic gasket and the control channel is illustrated in FIG. 4. The communicating conduit is a tube leading from channel 53 to control channel 20.

As soon as the working stroke of the piston 5 is started. i.e. as soon as it moves in downward direction. the air located below the piston in the bakestroke chamber of the working cylinder 4 is pressed outward via outlet openings 52. In this connection the ring 51 is being opened due to the pressure of air and clears the passage to the outlet openings 52. Simultaneously the working medium. which is air in this case, is pressed. however. through the

openings

13 and 14 of the working cylinder 4 into the adjoining chamber 12 from where pressure can be applied'via channel 53 in conjunction with throttle 54 to the outer side of the gasket trated in FIG. 3. As soon as the release lever 25 has been freed the plunger 22 moves again downward into its starting position whereby both Orings 19, as intake valves, are being compressed due to the compressed air acting on their outer rim and the O-ring 33. is being stretched in its starting position due to the venting of channel 35, in which position the annular channel 16 is opened to the ambient air so that the piston 5 moved upward in a known manner by the compressed air from the adjoining chamber 12 will not experience any counteracting pressure in cylinder 4. At this moment the piston 5 begins to lift off from buffer 8 since the air present in the adjoining chamber 12 can attack the piston 5 from below via bores 14 of the cylinder 4 and move it into its starting position at the upper end of the working cylinder 4.

When using the connecting tube 55 the gasket or ring 51 is held in its radially stretched position as long as the release lever 25 is drawn. This has, however, no bearing on the movement of the working piston 5 since the piston blocks in its lower position the passage of the air entering via inlet slots 41 to the outlet apertures 32 due to the fact that it forms a sealing seat on buffer 8. However, as soon as the release lever 25 is freed, the working piston 5 can return in the manner described above to its starting position; furthermore, compressed air flows via the connecting tube 35 to the outer side of the gasket 51 so as to force it into sealing position.

The control channel 20 (in connection with the embodiment of FIG. 4) and the adjoining chamber 12 (in connection with the embodiment of FIGS. 1-3) are herein defined as means containing a controlled pres sure means for control of the sealing ring 51, as herein described.

What we claim is:

l. A valve arrangement for the working cylinder of a pneumatically operated tool, comprising:

a tool housing;

a working cylinder mounted in said tool housing;

a piston reciprocable in said working cylinder;

a channel formed in said housing through which com pressed air is passed to said cylinder;

at least one annular valve chamber formed in said housing operatively adjacent said channel;

at least one elastic, radially deformable ring arranged in said channel. said at least one ring having outer rims which constitute control pressure areas.

an auxiliary valve means for operatively controlling said control pressure areas;

said at least one ring having inner rims constituting closing members for said air channel,

said housing being formed with an outlet opening communicating with the interior of said working cylinder and formed with an annular groove underneath said working cylinder, said annular groove communicating with said outlet opening;

an additional elastic. radially deformable ring mounted underneath said working cylinder in said annular groove of said tool housing;

said additional elastic ring having an outer rim constituting a control pressure surface and an inner rim serving as a closing means for said outlet opening;

a second channel formed in said housing and communicating with said annular groove; and

means for communicating a means containing a controlled pressure medium into said second channel. said outer rim of said additional elastic ring com- (ill said housing forms a housing bore in which said auxiliary valve means is operatively disposed. as well as a control channel communicating said housing bore with said valve chamber; and

said means for communicating comprises a tube connected to said second channel and communicating with said control channel and said housing. bore. constituting said means containing a controlled pressure medium.

Claims

1. A valve arrangement for the working cylinder of a pneumatically operated tool, comprising: a tool housing; a working cylinder mounted in said tool housing; a piston reciprocable in said working cylinder; a channel formed in said housing through which compressed air is passed to said cylinder; at least one annular valve chamber formed in said housing operatively adjacent said channel; at least one elastic, radially deformable ring arranged in said channel, said at least one ring having outer rims which constitute control pressure areas, an auxiliary valve means for operatively controlling said control pressure areas; said at least one ring having inner rims constituting closing members for said air channel, said housing being formed with an outlet opening communicating with the interior of said working cylinder and formed with an annular groove underneath said working cylinder, said annular groove communicating with said outlet opening; an additional elastic, radially deformable ring mounted underneath said working cylinder in said annular groove of said tool housing; said additional elastic ring having an outer rim constituting a control pressure surface and an inner rim serving as a closing means for said outlet opening; a second channel formed in said housing and communicating with said annular groove; and means for communicating a means containing a controlled pressure medium into said second channel, said outer rim of said additional elastic ring communicating via said second channel with said controlled pressure medium.

2. A valve arrangement according to claim 1, wherein said housing forms an adjoining chamber adjacent said working cylinder and communicating therewith, said adjoining chamber constitutes said means containing a controlled pressure medium; and a throttle is arranged in said second channel.

3. A valve arrangement according to claim 1 wherein said housing forms a housing bore in which said auxiliary valve means is operatively disposed, as well as a control channel communicating said housing bore with said valve chamber; and said means for communicating comprises a tube connected to said second channel and communicating with said control channel and said housing bore, constituting said means containing a controlled pressure medium.