CA1111321A - Pneumatic hack saw - Google Patents
Pneumatic hack sawInfo
- Publication number
- CA1111321A CA1111321A CA328,328A CA328328A CA1111321A CA 1111321 A CA1111321 A CA 1111321A CA 328328 A CA328328 A CA 328328A CA 1111321 A CA1111321 A CA 1111321A
- Authority
- CA
- Canada
- Prior art keywords
- piston
- rod
- piston rod
- valve
- cylinder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
- B25D9/14—Control devices for the reciprocating piston
- B25D9/16—Valve arrangements therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
- B23D51/00—Sawing machines or sawing devices working with straight blades, characterised only by constructional features of particular parts; Carrying or attaching means for tools, covered by this subclass, which are connected to a carrier at both ends
- B23D51/01—Sawing machines or sawing devices working with straight blades, characterised only by constructional features of particular parts; Carrying or attaching means for tools, covered by this subclass, which are connected to a carrier at both ends characterised by the handle
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
- B23D51/00—Sawing machines or sawing devices working with straight blades, characterised only by constructional features of particular parts; Carrying or attaching means for tools, covered by this subclass, which are connected to a carrier at both ends
- B23D51/16—Sawing machines or sawing devices working with straight blades, characterised only by constructional features of particular parts; Carrying or attaching means for tools, covered by this subclass, which are connected to a carrier at both ends of drives or feed mechanisms for straight tools, e.g. saw blades, or bows
- B23D51/18—Sawing machines or sawing devices working with straight blades, characterised only by constructional features of particular parts; Carrying or attaching means for tools, covered by this subclass, which are connected to a carrier at both ends of drives or feed mechanisms for straight tools, e.g. saw blades, or bows actuated by fluid or gas pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
- F01B11/00—Reciprocating-piston machines or engines without rotary main shaft, e.g. of free-piston type
- F01B11/001—Reciprocating-piston machines or engines without rotary main shaft, e.g. of free-piston type in which the movement in the two directions is obtained by one double acting piston motor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L23/00—Valves controlled by impact by piston, e.g. in free-piston machines
Abstract
PNEUMATIC RECIPROCAL ACTION TOOL
Abstract of the Disclosure A valving apparatus for a pneumatically driven tool such as a hacksaw actuated by a double acting piston within a pneumatic cylinder having a rod member slidably supported within the piston's piston rod with one end connected to a valve member mounted for movement between detented positions in a housing attached to the cylinder.
The rod member includes a pair of flanged sleeve members yieldably mounted thereon with a coil spring interposed therebetween. The flanges of the sleeve members cooperate with abutments within the piston rod to alternately compress the coil spring and effect limited unified movement of the rod member and piston rod to release the valve member from each of its detented positions which is then quickly slid to the other of its detented positions by the energy stored within the coil spring.
Abstract of the Disclosure A valving apparatus for a pneumatically driven tool such as a hacksaw actuated by a double acting piston within a pneumatic cylinder having a rod member slidably supported within the piston's piston rod with one end connected to a valve member mounted for movement between detented positions in a housing attached to the cylinder.
The rod member includes a pair of flanged sleeve members yieldably mounted thereon with a coil spring interposed therebetween. The flanges of the sleeve members cooperate with abutments within the piston rod to alternately compress the coil spring and effect limited unified movement of the rod member and piston rod to release the valve member from each of its detented positions which is then quickly slid to the other of its detented positions by the energy stored within the coil spring.
Description
3'~
PNEUMATIC RECIPROCAL ACTION TOOL
Background of the Invention The present invention pertains to a pneumatically driven power tool and more particularly to an improved valving apparatus for controlling the air which is alternate-ly introduced and released from each side of a double acting piston within a pneumatic cylinder.
Power driven reciprocal action tools such as hacksaws or sanders are well known which operate either electrically or pneumatically and the more popular of the commercially available types utilizes what is known as the scotch yoke type of driving device for effecting reciprocation of the work performing element.
A number of United States patents show and describe saws and other forms of tools which are pneumatica7ly actuated by double acting pistons and for reference to thP teachings of such disclosures attention is hereby drawn to United States Patents 2,443,568 and 3,155,011.
Positive valving of compressed air in pneumatically actuated tools of the double acting piston type, frequently presents the problem of dead centering and stalling during repeated starting and stopping of the tool. In other words, ,, ~
, .
' .' :
- 3- ~ L321 the piston may have traveled only a portion of its stroke when stopped and when attempting to restart the sliding type valve will have only moved a portion of its normal distance resulting in the tool stalling in mid-stroke.
The improved valving apparatus of the present inven-tion has eliminated the above problem by providing a sliding type valve with actuating means for effeeting a snap action movement thereof between first and second detented positions for alternately introducing and releasing air from opposite sides of the double acting piston. Additionally, the valving arrangement of the invention provides a means whereby the stroke length of the work performing element has been sub-stantially increased relative to known types of portable power driven reciprocal action tools. In a pneumatic hacksaw, for example, this longer stroke of the cutting blade greatly increases the number of cutting teeth that are caused to act upon a workpiece and provides a very desirable feature of increased lifQ expectancy of said cutting blade.
, Su~mary of the Invention The valving apparatus according to the invention is disposed within a valve housing tha~ is attached to one end of a pneumatic cylinder within which a double acting piston is caused to reciprocate. The valve defines a slidable block member having one end of a rod member or valve rod connected thereto. The opposite end of this rod member is slidably supported within a piston extension element or a piston rod (hereinafter referred to as pis~on rod) and includes a pair of spaced flanged sleeve members yieldably mounted thereon having a coil spring interposed therebet~een.
4 ~ 32~
These flanges cooperate with spaced abutments within the piston rod as the latter is reciprocated which compresses the coil spring to the extent where the sleeve members engage one another and temporarily cause the valve rod and piston rod to move in unison as a single element. The initial movement of the valve rod and piston rod in unison is suf-ficient to release the valve from either one of its two detented positions and the energy stored by compression within the coil spring causes the valve to be quickly slid to the other of the detented positions.
The valve member supports a pair of spaced cylindrical pins operatively associated with a spring biased detent plate having a pair of spaced detents for each pin that define the first and second positions to which the valve is alternately shifted by the rod member. ~hen the spring :;
is compressed between the flanges to the extent where the sleeve members engage one another, the biasing force of the .
detent plate is overcome causing the latter to move slightly upwardly and the valve to shift a predetermined distance which causes its pins to engage the detents that place the valve in either its first or second position depending on the direction of movement of the piston.
It is a general object of the invention to provide an improved valving apparatus for a pneumatically driven reciprocal action tool in which the valve is moved in a positive manner and temporarily locked in those positions for introducing and releasing air from each side of a double acting piston.
A further object is to provide a valving apparatus which is actuated so as to permit a substantial increase in . ,~. , .
~1321 the length of the effective stroke that the piston rod can travel.
A still further object is to provide an improved valving apparatus of simplified construction, which is relatively inexpensive to manufacture and with long life expectancy.
These and other objects of the invention will become more fully apparent by reference to the appended claims and as the following detailed description proceeds in reference to the figures of the drawings wherein:
Brief Description of the Drawings Fig. 1 is a perspective view of a pneumatically driven hacksaw to which the presently preferred form of the valving apparatus of the invention is applicable;
Fig. 2 is a sectional view in side elevation of the hacksaw in Fig. 1 showing the valve member in one of ` its two positions;
~; Fig. 3 is a view similar to Fig. 2 but showing the valve member in the other of its two positions;
Fig. 4 is a sectional view in side elevation of the valve housing wl~ich forms one end of the pneumatic cylin-der;
Fig. 5 is an end view of the valve housing shown in Fig. 4;
Fig. 6 is a bottom view of the valve housing shown in Figs. 4 and 5; and Fig. 7 is a perspective view in exploded form show-ing the valve housing and the various elements of the valve apparatus.
Description of the Preferred Embodiment Referring now to Fig. 1 the pneumatically actuated hacksaw to which the valving apparatus according to the invention is applicable is identified generally by numeral 10. Among its various parts the hacksaw includes a pneumatic cylinder 12 one end of which defines a valve housing 14 having a control handle 16 which is connected to any suitable source of compressed air by means of a line 18.
The control handle 16 is provided with a conventional thumb control valve 20 for selectively starting and stopping the flow of compressed air into the valve housing 14. That end of the cylinder 12 opposite the valve housing 14 is referred to as the forward end and defines a housing 22.
As shown in Fig. 1 the upper surface of the housing 22 has a spade type handle 24 assembled thereon by means of a cap screw 26. The lower surface of the housing 22 includes an integrally formed depending lug 28 having an opening 30 formed therein and serves in a known manner as a means for pivotably su~porting the hacksaw during operation.
Referring now to Figs. 2 and 3 the hacksaw's piston is identified by numeral 32 and is mounted for reciprocating movement within the cylinder 12 on one end of a piston rod 34. The piston has a conventional seal 36 assembled thereon to ~revent the by-pass of air to opposite sides thereof.
The piston rod 34 extends forwardly from the piston 32 and passes through a central opening 38 in the housing 22 which includes guide bus'nings 40 within which said piston rod is caused to reciprocate. Additionally conventional seals 42 and 44 are assembled within and adjacent the end of the housing 22 in operative association with ~he piston rod 34~ The free end of the piston rod 34 which extends out-wardly from the housing 22 has a cutting blade 46 assembled thereon by means of a conventional blade cap 48 and fasteners 50 (Figs. 1 and 2).
With reference to Figs. 3 and 4 a valve rod or rod member 52 is assembled for sliding movement within and in a direction co-axial with the piston rod 34. The end of this rod member 52 within the piston rod 34 is of reduced diameter as at 54 and has a pair of spaced flanged sleeve members 56 and 58 yieldably mounted thereon with a coil spring 60 inter-posed therebetween. The end of the rod member 52 within the piston rod is threaded and has a nut 62 assembled thereon which serves to retain the flanged sleeve members 56 and 58 and the coil spring 60 on that portion of said rod member depicted by numeral 54.
As shown in Figs. 3 and 4 that end of the rod member 52 opposite the end within the piston rod 34 is also of re-duced diameter and is identified by numeral 64. This end 64 of the rod member 52 is attac'ned to a valve block 66 by means of a pin 68, which is mounted for sliding movement within the valve housing 14. The upper surface of the valve block 66 (Fig. 73 has a pair of spaced channels 70 and 72 formed there-in within which pins 74 and 76 respectively are located.
The valve block 66 is slidable on a plate member 78 having openings defining ports 80, 82 and 84. This plate member in assembled position is stationary and is disposed intermediate the valve bloclc 66 and a base block 86 which forms the underside of the valve housing 14. The base block 86 is provided with a plurality of holes 88 along each side thereof which align with similar holes 9~ provided in the ~ 1~13Zl plate member 78 and by means of suitable fasteners not shown they provide a means for locating the valve block 66 in operating position within the valve housing 14.
A detent plate 92 is yieldably assembled within the valve housing 14 and is continually biased into contact with the rollers 74 and 76 by means of coil springs 94 and 96.
The springs 94 and g6 are disposed in spaced relation (Figs. 2 and 3) and are seated in openings 98 and 100 within the valve housing 14 in a manner whereby their lower ends are caused to bear against the upper surface of the detent plate 92. To prevent movement other than in a verti-cal direction of the detent plate 92, the latter is provided wi~h a pair of fixed guide pins 102 and 104 disposed in spaced relation and which extend upwardly into guide holes 106 and 108 respec~ively. The underside of the detent plate is provided with a pair of detents for each pin 74 and 76 and they are identified in Fig. 7 by numerals 110 and 112, respectively.
The ports 80, 82 and 84 in the plate member 78 over-lie and align with openings in the base block 86 that are depicted by numerals 114, 116 and 118, respectively.
As the valve block 66 is caused to reciprocate to and fro, by means yet to be described, it will alternately cover and expose ports 80 and 84 so that compressed air is alternately introduced first on one side of the piston 32 and then the other within the cylinder 12.
Port 82 serves as an exhaust port and in timed sequence with alternately introducing air to each side of the piston it serves to exhaust the air from that side of the piston opposite the side which is receiving the compressed L32~
g air. This port 32 is in alignment with opening 116 in the base block 86 and by means of manifold openings 120 (Figs. 2 and 3) intercomlected with said opening 116, air is exhausted from the lower or underside of the valve housing 14.
Openings 114 and 118 in the base block 86 are elongated and are aligned with ports 80 and 84 respectively as heretofore described. Additionally, the plate member includes openings 122 and 124 (Fig. 7) which are located adjacent to ports 80 and 84 respectively and also overlie openings 114 and 118 formed in the base block 86. As the valve block is caused to move to and fro, compressed air alternately enters openings 114 and 118 through ports 80 and 84 respectively and openings 122 and 124 serve to direct this air upwardly through channels 126 and 128 (Fig. 5). Channel 126 connects opening 122 with a tube 130 which extends through the piston 32 and alternately directs compressed air to the forward part of the cylinder 12 through a port 132, provided in said t~be 130. Channel 128 connects opening 124 with a port 134 (Figs. 5, 6 and 7) which is located in the valve housing 14 so as to alternately direct compressed air to the opposite side of the piston 32 within the cylinder 12.
Referring again to Figs. 2 and 3, the rod member 52 is guided for sliding movement within the piston rod 34 by means of a bushing 136 which provides a means for attach-ing the piston 32 to that end of the piston rod 34 located within the cylinder 12.
The bore of the piston rod 34 within which the rod 32~
member is slidable is identified by numeral 138 and the bushing 136 which supports the piston 32 extends into this bore a sufficient distance so that its inner end defines an abutment 140 (Fig. 2). The bore 138 is also counter-bored at its inner end which is identified by numeral 142 and the shoulder formed between said bore and counterbore defines an abutment 144 (Fig.2)~
To summarize the operation, the piston and piston rod are reciprocated in a well-known manner by altPrnately introducing and exhausting air from opposite sides of said piston. As the piston and piston rod move to the left within the cylinder (Fig. 2) the abutment 144 within the piston rod is caused to engage the flanged portion of sleeve member 58 causing the same to yield to the left a sufficient distance to compress the coil spring 60 and to engage sleeve member 56.
The engagement of the two sleeve members 56 and 58 causes the valve rod and piston rod to move in unison a sufficient distance to overcome the biasing force of springs 94 and 96 on the detent plate 92 which effects yielding of said plate in an upwardly direction. After the detent plate yields in this manner, tne energy within the compressed spring 60 is sufficient to quickly slide the valve block 66 to the left causing its pins 74 and 76 to slide along the underside of said detent plate with a minimum of resistance. During this movement the valve block can only travel a distance wllich places its pins in alignment with the adjacent detents which are ins~antly lowered by springs 94 and 96 so as to stop said valve block in this position. The valve block is temporarily held în this position while air is ~:3L3 3Zl introduced into the rear portion of the cylinder and exhausted from the forward portion.
~ hen the piston and piston rod travel in the opposite direction as shown in Fig. 3, the abutment 140 is caused to engage the flanged portion of sleeve member 56 causing the same to yield to the right a sufficient distance to compress the coil spring 60 and engage sleeve member 58.
Like movement in the opposite direction, the valve rod and piston rod move in unison so as to overcome the biasing force of springs 94 and 96 and the energy stored within spring 60 quickly slides said valve block to the right where it is stopped by the adjacent detents.
Although the present invention has been described in its presently preferred embodiment as used, for example, in a hacksaw, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art will readily understand and that the disclosed valving mechanism may be utilized in other types of pneumatic recip-rocal action tools. Such modifications and variations are considered to be within the purview and scope of the inven-tion and the appended claims.
:'
PNEUMATIC RECIPROCAL ACTION TOOL
Background of the Invention The present invention pertains to a pneumatically driven power tool and more particularly to an improved valving apparatus for controlling the air which is alternate-ly introduced and released from each side of a double acting piston within a pneumatic cylinder.
Power driven reciprocal action tools such as hacksaws or sanders are well known which operate either electrically or pneumatically and the more popular of the commercially available types utilizes what is known as the scotch yoke type of driving device for effecting reciprocation of the work performing element.
A number of United States patents show and describe saws and other forms of tools which are pneumatica7ly actuated by double acting pistons and for reference to thP teachings of such disclosures attention is hereby drawn to United States Patents 2,443,568 and 3,155,011.
Positive valving of compressed air in pneumatically actuated tools of the double acting piston type, frequently presents the problem of dead centering and stalling during repeated starting and stopping of the tool. In other words, ,, ~
, .
' .' :
- 3- ~ L321 the piston may have traveled only a portion of its stroke when stopped and when attempting to restart the sliding type valve will have only moved a portion of its normal distance resulting in the tool stalling in mid-stroke.
The improved valving apparatus of the present inven-tion has eliminated the above problem by providing a sliding type valve with actuating means for effeeting a snap action movement thereof between first and second detented positions for alternately introducing and releasing air from opposite sides of the double acting piston. Additionally, the valving arrangement of the invention provides a means whereby the stroke length of the work performing element has been sub-stantially increased relative to known types of portable power driven reciprocal action tools. In a pneumatic hacksaw, for example, this longer stroke of the cutting blade greatly increases the number of cutting teeth that are caused to act upon a workpiece and provides a very desirable feature of increased lifQ expectancy of said cutting blade.
, Su~mary of the Invention The valving apparatus according to the invention is disposed within a valve housing tha~ is attached to one end of a pneumatic cylinder within which a double acting piston is caused to reciprocate. The valve defines a slidable block member having one end of a rod member or valve rod connected thereto. The opposite end of this rod member is slidably supported within a piston extension element or a piston rod (hereinafter referred to as pis~on rod) and includes a pair of spaced flanged sleeve members yieldably mounted thereon having a coil spring interposed therebet~een.
4 ~ 32~
These flanges cooperate with spaced abutments within the piston rod as the latter is reciprocated which compresses the coil spring to the extent where the sleeve members engage one another and temporarily cause the valve rod and piston rod to move in unison as a single element. The initial movement of the valve rod and piston rod in unison is suf-ficient to release the valve from either one of its two detented positions and the energy stored by compression within the coil spring causes the valve to be quickly slid to the other of the detented positions.
The valve member supports a pair of spaced cylindrical pins operatively associated with a spring biased detent plate having a pair of spaced detents for each pin that define the first and second positions to which the valve is alternately shifted by the rod member. ~hen the spring :;
is compressed between the flanges to the extent where the sleeve members engage one another, the biasing force of the .
detent plate is overcome causing the latter to move slightly upwardly and the valve to shift a predetermined distance which causes its pins to engage the detents that place the valve in either its first or second position depending on the direction of movement of the piston.
It is a general object of the invention to provide an improved valving apparatus for a pneumatically driven reciprocal action tool in which the valve is moved in a positive manner and temporarily locked in those positions for introducing and releasing air from each side of a double acting piston.
A further object is to provide a valving apparatus which is actuated so as to permit a substantial increase in . ,~. , .
~1321 the length of the effective stroke that the piston rod can travel.
A still further object is to provide an improved valving apparatus of simplified construction, which is relatively inexpensive to manufacture and with long life expectancy.
These and other objects of the invention will become more fully apparent by reference to the appended claims and as the following detailed description proceeds in reference to the figures of the drawings wherein:
Brief Description of the Drawings Fig. 1 is a perspective view of a pneumatically driven hacksaw to which the presently preferred form of the valving apparatus of the invention is applicable;
Fig. 2 is a sectional view in side elevation of the hacksaw in Fig. 1 showing the valve member in one of ` its two positions;
~; Fig. 3 is a view similar to Fig. 2 but showing the valve member in the other of its two positions;
Fig. 4 is a sectional view in side elevation of the valve housing wl~ich forms one end of the pneumatic cylin-der;
Fig. 5 is an end view of the valve housing shown in Fig. 4;
Fig. 6 is a bottom view of the valve housing shown in Figs. 4 and 5; and Fig. 7 is a perspective view in exploded form show-ing the valve housing and the various elements of the valve apparatus.
Description of the Preferred Embodiment Referring now to Fig. 1 the pneumatically actuated hacksaw to which the valving apparatus according to the invention is applicable is identified generally by numeral 10. Among its various parts the hacksaw includes a pneumatic cylinder 12 one end of which defines a valve housing 14 having a control handle 16 which is connected to any suitable source of compressed air by means of a line 18.
The control handle 16 is provided with a conventional thumb control valve 20 for selectively starting and stopping the flow of compressed air into the valve housing 14. That end of the cylinder 12 opposite the valve housing 14 is referred to as the forward end and defines a housing 22.
As shown in Fig. 1 the upper surface of the housing 22 has a spade type handle 24 assembled thereon by means of a cap screw 26. The lower surface of the housing 22 includes an integrally formed depending lug 28 having an opening 30 formed therein and serves in a known manner as a means for pivotably su~porting the hacksaw during operation.
Referring now to Figs. 2 and 3 the hacksaw's piston is identified by numeral 32 and is mounted for reciprocating movement within the cylinder 12 on one end of a piston rod 34. The piston has a conventional seal 36 assembled thereon to ~revent the by-pass of air to opposite sides thereof.
The piston rod 34 extends forwardly from the piston 32 and passes through a central opening 38 in the housing 22 which includes guide bus'nings 40 within which said piston rod is caused to reciprocate. Additionally conventional seals 42 and 44 are assembled within and adjacent the end of the housing 22 in operative association with ~he piston rod 34~ The free end of the piston rod 34 which extends out-wardly from the housing 22 has a cutting blade 46 assembled thereon by means of a conventional blade cap 48 and fasteners 50 (Figs. 1 and 2).
With reference to Figs. 3 and 4 a valve rod or rod member 52 is assembled for sliding movement within and in a direction co-axial with the piston rod 34. The end of this rod member 52 within the piston rod 34 is of reduced diameter as at 54 and has a pair of spaced flanged sleeve members 56 and 58 yieldably mounted thereon with a coil spring 60 inter-posed therebetween. The end of the rod member 52 within the piston rod is threaded and has a nut 62 assembled thereon which serves to retain the flanged sleeve members 56 and 58 and the coil spring 60 on that portion of said rod member depicted by numeral 54.
As shown in Figs. 3 and 4 that end of the rod member 52 opposite the end within the piston rod 34 is also of re-duced diameter and is identified by numeral 64. This end 64 of the rod member 52 is attac'ned to a valve block 66 by means of a pin 68, which is mounted for sliding movement within the valve housing 14. The upper surface of the valve block 66 (Fig. 73 has a pair of spaced channels 70 and 72 formed there-in within which pins 74 and 76 respectively are located.
The valve block 66 is slidable on a plate member 78 having openings defining ports 80, 82 and 84. This plate member in assembled position is stationary and is disposed intermediate the valve bloclc 66 and a base block 86 which forms the underside of the valve housing 14. The base block 86 is provided with a plurality of holes 88 along each side thereof which align with similar holes 9~ provided in the ~ 1~13Zl plate member 78 and by means of suitable fasteners not shown they provide a means for locating the valve block 66 in operating position within the valve housing 14.
A detent plate 92 is yieldably assembled within the valve housing 14 and is continually biased into contact with the rollers 74 and 76 by means of coil springs 94 and 96.
The springs 94 and g6 are disposed in spaced relation (Figs. 2 and 3) and are seated in openings 98 and 100 within the valve housing 14 in a manner whereby their lower ends are caused to bear against the upper surface of the detent plate 92. To prevent movement other than in a verti-cal direction of the detent plate 92, the latter is provided wi~h a pair of fixed guide pins 102 and 104 disposed in spaced relation and which extend upwardly into guide holes 106 and 108 respec~ively. The underside of the detent plate is provided with a pair of detents for each pin 74 and 76 and they are identified in Fig. 7 by numerals 110 and 112, respectively.
The ports 80, 82 and 84 in the plate member 78 over-lie and align with openings in the base block 86 that are depicted by numerals 114, 116 and 118, respectively.
As the valve block 66 is caused to reciprocate to and fro, by means yet to be described, it will alternately cover and expose ports 80 and 84 so that compressed air is alternately introduced first on one side of the piston 32 and then the other within the cylinder 12.
Port 82 serves as an exhaust port and in timed sequence with alternately introducing air to each side of the piston it serves to exhaust the air from that side of the piston opposite the side which is receiving the compressed L32~
g air. This port 32 is in alignment with opening 116 in the base block 86 and by means of manifold openings 120 (Figs. 2 and 3) intercomlected with said opening 116, air is exhausted from the lower or underside of the valve housing 14.
Openings 114 and 118 in the base block 86 are elongated and are aligned with ports 80 and 84 respectively as heretofore described. Additionally, the plate member includes openings 122 and 124 (Fig. 7) which are located adjacent to ports 80 and 84 respectively and also overlie openings 114 and 118 formed in the base block 86. As the valve block is caused to move to and fro, compressed air alternately enters openings 114 and 118 through ports 80 and 84 respectively and openings 122 and 124 serve to direct this air upwardly through channels 126 and 128 (Fig. 5). Channel 126 connects opening 122 with a tube 130 which extends through the piston 32 and alternately directs compressed air to the forward part of the cylinder 12 through a port 132, provided in said t~be 130. Channel 128 connects opening 124 with a port 134 (Figs. 5, 6 and 7) which is located in the valve housing 14 so as to alternately direct compressed air to the opposite side of the piston 32 within the cylinder 12.
Referring again to Figs. 2 and 3, the rod member 52 is guided for sliding movement within the piston rod 34 by means of a bushing 136 which provides a means for attach-ing the piston 32 to that end of the piston rod 34 located within the cylinder 12.
The bore of the piston rod 34 within which the rod 32~
member is slidable is identified by numeral 138 and the bushing 136 which supports the piston 32 extends into this bore a sufficient distance so that its inner end defines an abutment 140 (Fig. 2). The bore 138 is also counter-bored at its inner end which is identified by numeral 142 and the shoulder formed between said bore and counterbore defines an abutment 144 (Fig.2)~
To summarize the operation, the piston and piston rod are reciprocated in a well-known manner by altPrnately introducing and exhausting air from opposite sides of said piston. As the piston and piston rod move to the left within the cylinder (Fig. 2) the abutment 144 within the piston rod is caused to engage the flanged portion of sleeve member 58 causing the same to yield to the left a sufficient distance to compress the coil spring 60 and to engage sleeve member 56.
The engagement of the two sleeve members 56 and 58 causes the valve rod and piston rod to move in unison a sufficient distance to overcome the biasing force of springs 94 and 96 on the detent plate 92 which effects yielding of said plate in an upwardly direction. After the detent plate yields in this manner, tne energy within the compressed spring 60 is sufficient to quickly slide the valve block 66 to the left causing its pins 74 and 76 to slide along the underside of said detent plate with a minimum of resistance. During this movement the valve block can only travel a distance wllich places its pins in alignment with the adjacent detents which are ins~antly lowered by springs 94 and 96 so as to stop said valve block in this position. The valve block is temporarily held în this position while air is ~:3L3 3Zl introduced into the rear portion of the cylinder and exhausted from the forward portion.
~ hen the piston and piston rod travel in the opposite direction as shown in Fig. 3, the abutment 140 is caused to engage the flanged portion of sleeve member 56 causing the same to yield to the right a sufficient distance to compress the coil spring 60 and engage sleeve member 58.
Like movement in the opposite direction, the valve rod and piston rod move in unison so as to overcome the biasing force of springs 94 and 96 and the energy stored within spring 60 quickly slides said valve block to the right where it is stopped by the adjacent detents.
Although the present invention has been described in its presently preferred embodiment as used, for example, in a hacksaw, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art will readily understand and that the disclosed valving mechanism may be utilized in other types of pneumatic recip-rocal action tools. Such modifications and variations are considered to be within the purview and scope of the inven-tion and the appended claims.
:'
Claims (10)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a reciprocating tool, a cylinder, a piston mounted for recipro-cation in said cylinder, valve means for controlling the flow of fluid alternately to either side of the piston, connecting means connected to said valve means for movement together, a lost motion connection between said piston and said connecting means comprised of a first thrust transmitting means associated with said piston, a second thrust transmitting means associated with said connecting means, spring means interposed between said first and second thrust transmitting means, engaging means on each of said first and second thrust transmitting means respectively, adapted to engage each other when said spring is compressed whereby the thrust of said piston is transmitted to said connecting means through said thrust transmitting means.
2. In a reciprocating tool, a cylinder, a piston and piston rod mounted for reciprocation in said cylinder, valve means for controlling the flow of fluid alternately to each side of the piston, connecting means connecting said piston and piston rod to said valve means, a lost motion connection between said piston rod and said connecting means comprised of first and second thrust transmitting means mounted on said connecting means in operative association respectively with first and second abutment means forming a part of said piston rod, spring means interposed between said first and second thrust transmitting means, and first and second engaging means on said first and second thrust transmitting means respectively adapted to contact each other when said spring is compressed whereby the thrust of said piston is transmitted to said connecting means through said thrust trans-mitting means.
3. The structure according to claim 2 wherein said connecting means defines a rod member assembled for sliding movement within and in a direction co-axial with the piston and piston rod.
4. The structure according to claim 3 wherein said first and second thrust transmitting means are located within said piston rod for limited movement therewith.
5. The structure according to claim 3 wherein said first and second thrust transmitting means are mounted for limited alternate sliding movement on said rod member.
6. The structure according to claim 5 wherein said first and second thrust transmitting means define flanged sleeve members disposed in aligned and opposed relation on said rod member.
7. In a reciprocating tool, a cylinder, a piston and piston rod mounted for reciprocation in said cylinder, valve means for controlling the flow of fluid alternately to each side of the piston, connecting means connecting said piston and said valve means, said valve means being comprised of a control member mounted for movement within a housing, inlet and outlet passages leading to and from a portion of the interior of said housing, fluid conduits respectively communicating with each side of said piston, means on said control member in contact with the interior of said housing for alternately connecting said inlet and outlet passages with each of said controls, said control member being biased in one direction into contact with the interior of said housing.
8. The structure according to claim 7 wherein said connecting means defines a rod member having one end fixed to said control member and the opposite end assembled for sliding movement within and in a direction co-axial with said piston rod.
9. The structure according to claim 7 wherein the surfaces of said control member in contact with the interior of said housing are planar.
10. The structure according to claim 7 wherein the interior of said housing engaged by said control member is planar.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US92061978A | 1978-06-29 | 1978-06-29 | |
| US920,619 | 1978-06-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1111321A true CA1111321A (en) | 1981-10-27 |
Family
ID=25444083
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA328,328A Expired CA1111321A (en) | 1978-06-29 | 1979-05-25 | Pneumatic hack saw |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS556100A (en) |
| CA (1) | CA1111321A (en) |
| DE (1) | DE2925844A1 (en) |
| FR (1) | FR2429638A1 (en) |
| GB (1) | GB2023742A (en) |
| NL (1) | NL7905092A (en) |
| SE (1) | SE7905434L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5363739A (en) * | 1993-10-12 | 1994-11-15 | Graco Inc. | Reduced icing low friction air valve |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2039570A (en) * | 1935-05-16 | 1936-05-05 | Elliot I Thornton | Pump |
| US2637304A (en) * | 1950-01-05 | 1953-05-05 | Stewart Warner Corp | Valve mechanism for reciprocating fluid motors |
| US3699846A (en) * | 1970-12-30 | 1972-10-24 | Stewart Warner Corp | Air motor |
| US4079660A (en) * | 1976-07-02 | 1978-03-21 | Ives Frank E | Safety valve for piston type pneumatic powered motor |
| FR2358565A1 (en) * | 1976-07-16 | 1978-02-10 | Dieny Alfred | Reciprocating engine with automatic valve operation - has sliding valve actuated by movement of main piston for reversing movement |
-
1979
- 1979-05-25 CA CA328,328A patent/CA1111321A/en not_active Expired
- 1979-06-06 GB GB7919648A patent/GB2023742A/en not_active Withdrawn
- 1979-06-20 SE SE7905434A patent/SE7905434L/en not_active Application Discontinuation
- 1979-06-27 DE DE19792925844 patent/DE2925844A1/en not_active Withdrawn
- 1979-06-27 FR FR7916585A patent/FR2429638A1/en active Pending
- 1979-06-28 JP JP8198579A patent/JPS556100A/en active Pending
- 1979-06-29 NL NL7905092A patent/NL7905092A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| SE7905434L (en) | 1979-12-30 |
| DE2925844A1 (en) | 1980-01-17 |
| FR2429638A1 (en) | 1980-01-25 |
| JPS556100A (en) | 1980-01-17 |
| NL7905092A (en) | 1980-01-03 |
| GB2023742A (en) | 1980-01-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |