US3684034A - Impact air driven tool - Google Patents

Impact air driven tool Download PDF

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Publication number
US3684034A
US3684034A US39390A US3684034DA US3684034A US 3684034 A US3684034 A US 3684034A US 39390 A US39390 A US 39390A US 3684034D A US3684034D A US 3684034DA US 3684034 A US3684034 A US 3684034A
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valve
passage
piston
casing
compressed air
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US39390A
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Hiromu Terada
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Nippon Pneumatic Manufacturing Co Ltd
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Nippon Pneumatic Manufacturing Co Ltd
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Priority claimed from JP1440470A external-priority patent/JPS4830947B1/ja
Priority claimed from JP1440570A external-priority patent/JPS4830948B1/ja
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    • 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

Definitions

  • a cylinder has a piston slidable therein for striking a chisel, the chisel being operatively supported by a chisel holder secured to one end of said cylindenA valve member is mounted within a valve casing and is reciprocated within said casing by piston operating air supplied into an upper cylinder cavity above the uppermost end surface of the piston and a lower cylinder cavity beneath the lowermost end surface of the piston.
  • a limiting valve 1 is provided and is operated by a variation of the amount of air within said cylinder for change-over of 'supply of said piston operating air to said valve member.
  • a throttle valve is disposed in an intermediate portion of a passage through which compressed air for shifting the valve member from the advanced position to the original position is supplied.
  • the throttle valve controls the flow of .air to the valve member and thereby adjusts the duration of the piston resting phase during which the valve member is shifted.
  • the present invention relates to an impact air driven tool utilizing compressed air for producing destructive forces.
  • the present invention has in its object to provide an impact air driven tool with which, as compared with one exemplary type of conventional impact air driven tools, a relatively greater value of striking energy per piston stroke can be obtained.
  • Another object of the present invention is to provide an improved impact air driven tool wherein the number of piston strokes can be varied from the zero value to the maximum possible value as desired so that the optimum value can be selected to suit to the capacity of a compressor in stock in case of said tool of the present invention being in effect connected with said compressor in stock.
  • FIG. 1 is a longitudinal sectional view of one embodiment of the present invention with a portion being broken away,
  • FIG. 2 is a cross-sectional view of a control valve mechanism in said embodiment of the present inventron
  • FIG. 3 is a longitudinal sectional view of a throttle valve portion, on an enlarged scale, employed in the embodiment shown in FIG. 1,
  • FIG. 4 is a longitudinal sectional view, on an enlarged scale, of a rapid exhaust valve portion employed in the embodiment shown in FIG. 1,
  • FIG. 5 is alongitudinal sectional view of a modified embodiment of the present invention with a portion being broken away,
  • FIG. 6 is a cross-sectional view of a control valve mechanism employed in said modified embodiment shown in FIG. 5,
  • FIG. 7 is a longitudinal sectional view, on an enlarged scale, of a throttle valve portion employed in the modified embodiment shown in FIG. 5,
  • FIG. 8 is a longitudinal sectional view, on an enlarged scale, of a rapid exhaust valve portion employed in the modified embodiment shown in FIG. 5, and
  • FIG. 9 is a longitudinal sectional view, on an enlarged scale, of a check valve portion employed in the modified embodiment shown in FIG. 5.
  • the improved impact air driven tool basically comprises a cylinder unit, a piston unit, a chisel unit, and a control valve unit for controlling the flow of compressed air supplied to said cylinder unit.
  • reference numeral 11 represents a cylinder
  • 12 represents a top plate secured to an upper end of said cylinder
  • 13 represents a chisel holder secured to a lower end of said cylinder
  • 14 represents a chisel
  • 15 represents a piston slidably received in said cylinder.
  • nipple 19 remote from said supply port 18 is rigidly connected with an elbow 20 to which a tubular hose connected from a suitable compressor means may be connected.
  • the valve casing 16 is secured at its right-hand side as viewed from FIG. 2 with a plate member 21 formed therein with a passage 22 communicating with a righthand opening 24 of a valve chamber 23.
  • the valve casing 16 is also provided therein with a limiting valve chamber 26 slidably receiving a limiting valve therein and with a valve chamber 28 having therein a tubular check valve 27 biased by a spring to the left within said valve chamber 28.
  • This valve chamber 28 is formed at its outer peripheral surface with a tubular gap 29 and at its left-hand portion with a passage 31 communicating with said passage 22.
  • said check valve 27 acts to permit the flow of air from the passage 31 to the gap 29, but to restrict said flow from the gap 29 to said passage 31.
  • the plate member 21 is also formed therein with an adjustable needle valve in the form of a throttle valve 32 situated between a passage 33 and a passage 34, which are also formed within the plate member 21, for regulating the flow of air passing between said passages 33 and 34.
  • the passage 33 is communicated with the valve chamber 28 while the passage 34 is communicated with the gap 29.
  • the valve body 17 is formed at its right-hand portion with an enlarged diameter portion. 35 having a recess at its right-hand extremity in the axial direction thereof, so that when said valve body 17 is moved to the right an annular groove 36 on the inner peripheral surface of the valve chamber 23 can be closed by said enlarged diameter portion 35 while, when said valve body 17 is moved to the left, said annular groove 36 commences to communicate with the opening 24 through a righthand portion of said chamber 23 and also with said gap 29.
  • the valve body 17 is formed about its intermediate portion with a reduced diameter portion 40 which, upon movement of the valve body 17 to the right, acts to communicate between annular grooves 41 and 42 formed on the inner peripheral surface of the valve chamber 23 at a position around said reduced diameter portion 40.
  • This annular groove 41 is directly communicated with an exhaust port 43 formed in the valve casing 16 and the annular groove 42 is directly communicated with a passage 44 formed as shown in FIG. 1, in a wall portion of the cylinder 1 l.
  • the valve chamber 23 is also formed on its inner peripheral surface at a left-hand portion next to the annular groove 41 with an annular groove 45 which.may be communicated with the annular groove 41 through said reduced diameter portion 40 when the valve body 17 is situated to the left, but blocked of its communication therewith when the valve body 17 is situated to the right.
  • This annular groove 45 is directly communicated with a passage 46 open to the interior of the cylinder 11 at a position below an opening of the passage 39, as shown in FIG. 1.
  • the limiting valve 25 is formed at its intermediate portion with a reduced diameter portion 47 which, upon movement of said valve 25 to the right, acts to communicate between passages 48 and 49 formed on the inner peripheral surface of the valve chamber 26.
  • This passage 48 is directly communicated with the gap 29 and the passage 49 is directly communicated with the annular groove 37.
  • the valve chamber 26 is also formed in its peripheral wall at a position about the right-hand extremity of the limiting valve 47 with a passage 50 and about a lefthand portion of the limiting valve 47 with a passage 51 and a passage 52.
  • the passage 50 is communicated with the annular groove 38 by means of the common passage 39 which is in turn open to the interior of the cylinder 11.
  • the passage 51 is communicated with the annular groove 45 by means of the common passage 46 which is in turn open to the interior of said cylinder 11.
  • the passage 52 may be communicated with the passage 48 through the reduced diameter portion 47 to permit the flow of air to an exhaust port 53 when the limiting valve 25 is moved to the left.
  • Reference numeral 54 represents a rapid exhaust valve casing secured to an intermediate portion of the cylinder 11. As shown particularly in FIG. 4, this rapid exhaust valve casing 54 is formed with a ventilating port 55 directly communicated with a ventilating hole 68 formed in the wall of the cylinder 11. Within said valve casing 54, a valve chamber 59 is formed for slidably receiving therein a valve member 56 capable of closing and opening the ventilating port 55. It should, however, be noted that the valve member 56 is formed with an auxiliary valve chamber 58 in which an auxiliary valve 57 in the form of a plate member is operatively mounted as shown in FIG. 4.
  • the valve 56 is formed at its left-hand portion with an opening 60 which may be closed by the auxiliary valve 57 when the latter is moved to the left.
  • the auxiliary valve chamber 58 is formed at its depth with a plurality of holes 61 communicating between the righthand portion of the auxiliary valve chamber 58 and the ventilating port 55 and thus ventilating hole 68.
  • This valve chamber 58 is also formed at a central portion of its depth with a slight projection which permits, together with a plurality of notches formed on the outer periphery of the auxiliary valve 57, the flow of air from the opening 60 to the holes 61 even when the righthand surface of the auxiliary valve 57 is contacted with the depth of said valve chamber 58 or the left-hand surface of said projection.
  • annular cushioning member 62 Provided at the left-hand extremity of the valve chamber 59 is an annular cushioning member 62, made of elastic material, having a through hole at its center, said through hole being communicated with a passage 69 which is in turn connected to the passage 44 formed in the wall of the cylinder 1 1.
  • valve member 56 and accordingly the valve chamber 59 are stepped to give an enlarged diameter portion on the side adjacent to the ventilating port 55. Therefore, it will thus be understood that, when the valve member 56 is moved to the right, a cavity b will be formed betweenv said enlarged diameter portion of the valve chamber 59 and a correspondingly reduced diameter portion of the valve member 56.
  • This cavity b is communicated with an exhaust port 65 by means of a small passage 64, the both of the latter being formed in a lower wall portion of the casing 54.
  • a plurality of small holes 66 are disposed for discharging the exhaust air from the port 65 to the atmosphere.
  • valve casing 16 is rigidly secured at its left-hand side as viewed from FIG. 2 with another plate member corresponding to the abovementioned plate member 21, but the plate member at the left-hand side of the valve casing 16 is provided with an outlet hole communicated with the left-hand portion of the valve chamber 23.
  • the air in the passage 34 will pass through a clearance a of the throttle valve 32 to the passage 33 and then to the passage 31 passing through the check valve 27. Thereafter, the air in the passage 31 will be introduced to the opening 24 through the passage 22 into the recess formed on the right-hand extremity of the valve member 17 in the axial direction.
  • the throttle valve 32 provides a narrow clearance a as shown in FIG. 3, the air is somewhat slowly supplied from the passage 34 into the recess, and the value of pneumatic pressure will, accordingly, slowly increase.
  • valve body 17 commences to move to the left.
  • the valve body 17 will be rapidly moved to the left because pneumatic pressure that has been applied to the annular groove 36 is added to the pneumatic pressure applied through the opening 24.
  • the grooves 37 and 42 in the valve chamber 23 are communicated to each other by the reduced diameter portion 67 while communication between the grooves 37 and 38 and communication between the grooves 41 and 42 are respectively cut off. Accordingly, the compressed air supplied to the supply port 18 will flow to the passage 44 through the groove 37and then the groove 42, pressing the valve member 56 and the auxiliary valve 57 to the right and passing through the notches on the periphery of the auxiliary valve 57 and then the holes in the depth of the auxiliary valve chamber 58, and finally be supplied through the ventilating hole 68 by means of the ventilating port 55 into the lower cylinder cavity defined by the lower extremity of the piston and the upper extremity of the chisel.
  • a seal ring provided in the peripheral surface of the right-hand end of the valve member 56 is at this time tightly contacted to the adjacent end surface of the ventilating port 55 so as to prevent the air in the ventilating port from leaking out.
  • the grooves 41 and 45 in the valve chamber 23 are also communicated to each other by the reduced diameter portion 40, permitting the passage 46 to communicate with the exhaust port 43 and then to atmosphere through said grooves 41 and 45. Accordingly, the air contained in an upper cylinder cavity defined between the upper extremity of the piston 15 and the back of the top plate 12 will be discharged to the atmosphere through the passage 46 that has been communicated with the exhaust port 43. Thus, the piston 15 commences to move upward.
  • the passage 51 is also communicated to the atmosphere. At this time, a value of pressure in the passage 39 and thus a valve of pressure in the passage communicated therewith are equalized to the atmosphere. Thus, the limiting valve 25 remains to the right.
  • the passage 48 is communicated by the reduced diameter portion 47 of the valve 25 with the passage 52, permitting the air in the gap 29 and the groove 36 to be discharged to the atmosphere therethrough by means of the exhaust port 53.
  • valve chamber 59 within the rapid exhaust valve casing 54 is again communicated to the atmosphere by means of the passage 44 extending from the passage 69 communicated with said chamber 59. Then, in the same manner as has been seen during the previous downward movement of the piston 15 within the cylinder 11, the air contained in the lower cylinder cavity will again open the valve member 56 and escape therefrom to the atmosphere through the ventilating port 55, the exhaust port 65 and finally the small holes 66, while the piston 15 is again abutted against the upper extremity of the chisel 14.
  • the limiting valve 25 can be positioned as illustrated in FIG. 2.
  • the number of piston strokes per unit time can be varied as desired. Even in the event that the number of piston strokes per unit time is varied, a value of striking energy per piston stroke does not vary at all. The reason therefor will be hereinafter set forth.
  • the piston 15 within the cylinder 1 1 has a striking phase wherein the valve body 17 and the limiting valve 25 are positioned as shown in FIG. 2, a resting phase which continues from the time at which the piston strikes the chisel 14 until the time at which the piston commences its upward movement away from the chisel, and a return phase wherein the upward movement of the piston takes place.
  • the resting phase is a time duration of the valve body 17 moving from the right to the left within its valve chamber 23, commencing at the moment that the piston 15 strikes the chisel 14 and ending at the moment that the piston 15 commences its upward movement away from the chisel.
  • the throttle valve 32 is constructed in the form of screw type needle valve as substantially shown in FIG. 3, a value of pneumatic pressure acting on the right-hand extremity of the valve body 17 can be rapidly increased by adjusting the valve 32 so as to increase a value of the clearance a, resulting in the reduction of the time necessary for the valve body 17 to complete its movement from the right to the left, that is to say, duration of the resting phase.
  • the duration of the resting phase may be prolonged.
  • reference numeral 71 represents a cylinder
  • 72 represents a top plate secured to an upper end of said cylinder
  • 73 represents a chisel holder
  • 74 represents a chisel
  • 75 represents a piston slidably received in said cylinder.
  • Reference numeral 76 represents a valve casin secured to a lateral upper portion of said cylinder 71, in which valve casing a valve body 77 is slidably received.
  • This valve casing 76 is formed with a compressed air supply port 78 to which a nipple 79 is pivotably connected.
  • One end of said nipple 79 remote from said port 78 is rigidly connected with an elbow 80 to which a tubular hose connected from a suitable compressor means may be connected.
  • the valve casing 76 is secured at its both right-hand and left-hand sides as viewed from FIG.
  • the valve casing 76 is also provided therein with a time lag valve chamber 86 in which a time lag valve 85 is slidably received and with a valve chamber 88 in which a check valve 87 is provided.
  • a time lag valve chamber 86 in which a time lag valve 85 is slidably received
  • a valve chamber 88 in which a check valve 87 is provided.
  • annular gap 89 Provided around the outer periphery of said valve chamber 88 is an annular gap 89.
  • the chambers 88 and 86 are connected to each other by a passage 91.
  • the check valve 87 is normally biased to the right within its valve chamber 88 so as to permit the flow of air from the passage 91 to the gap 89, but to restrict the flow of air from the gap 89 to the passage 91.
  • the other or left-hand plate member 92 is provided therein with a throttle valve 93 in the form, for example, of an adjustable needle valve and at a suitable position with an exhaust hole communicating between the left-hand portion of the chamber 83 and the atmosphere.
  • a throttle valve 93 in the form, for example, of an adjustable needle valve and at a suitable position with an exhaust hole communicating between the left-hand portion of the chamber 83 and the atmosphere.
  • the throttle valve 93 is positioned between a passage 94 communicated with the valve chamber 88 and a passage 95 communicated with the gap 89, so as to act to regulate the flow of air therebetween.
  • the valve body 77 is formed at its intermediate portion with a reduced diameter portions 103 and 140 and at its right-hand end with an enlarged diameter portion 96 which is in turn formed at its right-hand extremity with a circular recess in the axial direction thereof.
  • the valve chamber 83 is provided on its inner peripheral surface with annular grooves 97 and 98 which can be isolated from each other by the enlarged diameter portion 96 as the valve body 77 is moved to the left, said passage 98 being in turn connected with a passage 99 open to the interior of the cylinder 71 and said passage 97 being in turn connected with the supply port 78.
  • This valve chamber 83 is also formed on a left-hand inner peripheral surface with a plurality of annular grooves 100, 101 and 102, the grooves 100 and 101 being communicated to each other by the reduced diameter portion 103 of the valve body 77 when the latter is moved to the left while the grooves 101 and 102 being communicated to each other by said reduced diameter portion of the valve body 77 when the latter is moved to the right.
  • the groove 100 is in turn connected with a passage 104 open to the interior of the cylinder 71 at a position below the opening of the passage 99 formed on the inner peripheral surface of the cylinder 71, the groove 101 is in turn connected with an exhaust port 105 formed in the casing 76 and the groove 102 is in turn connected with a passage 106 formed in a wall portion of the cylinder 71.
  • the time lag valve 85 is formed at its intermediate portion with a reduced diameter portion 107 which, upon movement of said valve 85 to the left, acts to communicate between passages 108 and 109 formed on the inner peripheral surface of the valve chamber 86.
  • the passage 108 is directly connected with an exhaust port 110.
  • a passage 111 communicating between the valve chamber 86 and a passage 112 which is in turn connected to a passage 95 formed in the plate member 92.
  • the valve chamber 86 is also formed at its right-hand portion with a passage 1 13 connected to the groove 97, the right-hand portion 114 of the chamber 86 being also connected to said groove 97.
  • the right-hand portion 114 is designed to slidably receive a right-hand reduced diameter portion 115 of the time lag valve 85 therein, the diameter of said reduced diameter portion 115 being smaller than that of the left-hand extremity of the valve body 85.
  • the right-hand portion is provided on its left-hand inner peripheral surface with an O-ring, to the left of which O-ring the valve chamber 86 is somewhat enlarged to give its diameter greater than that of the right-hand portion 114.
  • an exhaust hole communicating between that enlarged portion of the chamber 86 to the atmosphere is provided.
  • the cylinder 71 is provided on its inner peripheral surface at a position below the opening of the passage 104 formed thereon with another opening in which a limiting valve operating member 116 is collapsibly mounted in such a manner as to project a portion thereof toward the interior of the cylinder 71 unless the projected portion 'is backwardly retracted by the piston 75.
  • This operating member 116 is in the form of a ball and, as shown in FIG. 9, acts to operate a limiting valve 118 in a valve chamber 117 formed within a limiting valve casing 145 formed in the cylinder wall.
  • the limiting valve 118 is normally biased toward the operating member 116 by a spring 119 and will operate when the operating member 116 is collapsed by the piston 75.
  • the valve chamber 117 is formed about its outer periphery with a passage 120 communicated with the passages 111 and 112 within the valve casing 76 and the passage 95 in the plate member 92 by means of an annular cavity 121 formed in said valve casing 117.
  • This valve chamber 117 is also formed at its depth with a valve seat 122 to which the limiting valve 118 is seated by the spring 119.
  • a passage 123 communicated with an exhaust port 125, formed in the valve casing 76, through a passage 124 formed in the cylinder wall.
  • a cavity 141 formed in the valve casing 76 in communication with the annular groove 97 within the valve chamber 83 by means of a passage 146.
  • the limiting valve 118 is also formed at its left-hand extremity with a recess 142 of a desired depth in communication with a passage 143 which is in turn connected with the annular cavity 121 by means of a passage 144, the both passages 143 and 144 being formed within the valve casing 145 at a position adjacent to the left-hand exv tremity of the limiting valve 118.
  • Reference numeral 126 represents a rapid exhaust valve casing secured to the cylinder 71. As shown particularly in FIG. 8, this rapid exhaust valve casing 126 is formed with a ventilating port 127 directly communicated with a ventilating hole 146 formed in the wall of the cylinder 71. Within said valve casing 126, a valve chamber 129 is formed for slidably receiving therein a valve member 128 capable of closing and opening the ventilating port 127. The valve member 128 is formed with an auxiliary valve chamber 130 in which an auxiliary valve 131 in the form of a plate member is operatively mounted.
  • the valve member 128 is formed at its left-hand por tion with an opening 132 which may be closed by the auxiliary valve 131 when the latter is moved to the left.
  • the auxiliary valve chamber is formed at its depth with a plurality of holes 133 communicating between the right-hand portion of the auxiliary valve chamber 130 and the ventilating port 127 and thus the ventilating hole 146.
  • This valve chamber 129 is also formed at a central portion of its depth with a slight projection which permits, together with a. plurality of notches formed on the outer periphery of the auxiliary valve 131, the flow of air from the opening 132 to the holes 133 even when the right-hand surface of the auxiliary valve 131 is contacted with the depth of said valve chamber 129 or the left-hand surface of said projection.
  • annular cushioning member 134 Provided at the left-hand extremity of the valve chamber 129 is an annular cushioning member 134, made of elastic material, having a through hole at its center, said through hole being communicated with a passage 135 which isin turn connected to the passage 106 formed in the wall of the cylinder 71.
  • valve member 128 and accordingly the valve chamber 129 are stepped to give an enlarged diameter portion on the side adjacent to the ventilating port 127. Therefore, it will thus be understood that, when the valve member 128 is moved to the right, a cavity d will be formed between said enlarged diameter portion of the valve chamber 129 and a correspondingly reduced diameter portion of the valve member 128. This cavity d is communicated with an exhaust port. 138 by means of a small passage 137, the both of the latter being formed in a lower wall portion of the casing 126. At a lower portion of the casing 126 beneath said, exhaust port 138, a plurality of small holes 139 are disposed for discharging the exhaust air from the port 139 to the atmosphere.
  • the improved impact air driven tool may function in such a manner as hereinafter set forth.
  • the annular groove 97 is then communicated with the right-hand portion 1 14 of the valve chamber 86 and the groove 1 13 which is in turn communicated with the time lag valve chamber 215. Accordingly, the compressed air will also act on the right-hand reduced diameter portion 115 of the time lag valve 85 to render the valve 85 to move to the left and thereby to close the passage 113, as shown in FIG. 6.
  • the groove 97 is communicated with the cavity 141 of the limiting valve casing by means of the passage 146, the pneumatic pressure will also act on the left-hand extremity of the valve 118 and then flow to the annular cavity 121 in the order through the recess 142, passage 143 and passage 144.
  • the air in the annular cavity 121 then in part flow to the passage 95 in the plate member 92 and thus to the passage 94 through a clearance c of the throttle valve 93.
  • the air in the passage 94 is introduced against the left-hand extremity of the time lag valve 85 through the check valve 87 by means of the passage 91. Also, the compressed air in the passage 85 will in part flow into the gap 89, acting on the check valve 87.
  • the compressed air is slowly accumulated within a left-hand portion of the valve chamber 88 and the passage 91 via the clearance c of the throttle valve.
  • the time lag valve 85 is positioned to the left until a value of pressure of the compressed air acting on the left-hand extremity of the valve 85 increases over that of pressure acting on the right-hand reduced diameter portion 115 of said valve.
  • the valve 85 commences to move to the right.
  • valve 85 As soon as the left-hand extremity of the valve 85 passes through the O-ring positioned at the left side of the valve chamber 86, it can be rapidly moved to the right as pressure in the passage 112 is also applied through the passage 111 to the left-hand extremity thereof, until the right-hand reduced diameter portion 115 is abutted against the cushioning member provided at the depth of the righthand portion 1 14 of the chamber.
  • the reduced diameter portion 107 of said valve communicates the passage 109 with the passage 113.
  • the compressed air from the groove 97 always exists in the passage 113 throughout the operation of the impact air driven tool of the present invention. Therefore, upon communication between the passages 109 and 113, the air flows into the passage 109 from the passage 113 and the to the right-hand portion of the chamber 83 through the opening 84 by means of the passage 82 communicated therewith. This air thus supplied then acts on the righthand extremity of the enlarged diameter portion 96 of the valve body 77 so as to move the latter to the left.
  • the reduced diameter portion of the valve 77 communicates the groove 101 with the groove 100 while an intermediate portion of said valve 77 isolates the grooves 101 and 102 and the reduced diameter portion 140 of the valve 77 communicates the groove 97 with the groove 102 while the enlarged diameter portion 96 thereof closes the groove 98.
  • the air in the groove 97 is supplied to the passage 106 through the groove 102 and then to the passage 135, then passing through the notches on the periphery of the auxiliary valve 131 and then the ventilating port 127 into the lower cylinder cavity defined between the lowermost end of the piston and the uppermost end of the chisel.
  • the piston is upwardly moved thereby.
  • the seal ring provided in the peripheral surface of the right-hand end of the valve member 128 is tightly contacted to the adjacent end surface of the ventilating port 127 so as to prevent the air in the ventilating port from leaking out.
  • the limit valve operating member 116 is backwardly retracted by the uppermost end of said piston. Rectraction of said member 116 will cause the limit valve 118 to move to the left, compressing the spring 119 while closing the passage 143 in the valve 118. At this time, the passage 124 communicated to the atmosphere commences to communicate with the valve chamber 1 17.
  • valve chamber 117 is communicated with the left-hand portion of the valve chamber 86 through the passage 120, the annular groove 121, and the passages 112 and 111, the air in said portion of the valve chamber 86 is exhausted and the time lag valve 85 is moved to the left under the influence of the pneumatic pressure always existing in the right-hand portion 114 as supplied from the groove 97. Also, upon communication of the passage 112 with the exhaust port 125, the air in the passage 95 and the gap 89 is exhausted while the air contained in the check valve 87 and the passage 91 presses the check valve 87 so as to open the latter so that this air is also exhausted through the exhaust port 125 by means of the gap 89.
  • valve body 77 is returned to the right with its enlarged diameter portion 96 being applied with pneumatic pressure in the left-hand portion of the valve chamber 83, thus commencing the next cycle of operation.
  • the number of piston strokes per unit time can be varied by adjusting the opening, or the value of the clearance c, of the throttle valve 93 as in the first mentioned embodiment of the present invention. Similarly, even in the event that the number of piston strokes per unit time is varied, the value of striking energy per piston stroke does not vary at all.
  • the piston 75 within the cylinder 71 has a striking phase, a resting phase and a return phase throughout each cycle of operation.
  • the duration of the resting phase of the piston by adjusting the duration of the resting phase of the piston, the number of piston strokes per unit time can be varied without affecting the striking phase and the return phase.
  • the resting phase of the piston 75 represents a duration of time between the time at which the piston strikes the chisel and the time-at which said piston commences its upward movement away from said chisel.
  • this time duration may be determined by the time necessary for the time lag valve 85 to complete its movement to the right after the piston strikes the chisel.
  • the throttle valve 73 is constructed in the form of screw type needle valve as substantially shown in FIG. 7 in order to permit the adjustment of the size of the clearance c, the number of piston strokes per unit time can be varied through controlling the duration of the resting phase of the piston.
  • the impact air driven tool is designed such that the limiting valve 118 is actuated to bring the time lag valve 85 into the striking phase during the return movement of the piston 75 away from the chisel 74 and thereby to bring the valve body 77 into the striking phase through the shifting movement of said valve 85. Therefore, retardation of the shifting movement of the valve body 77 with respect to the movement of the piston 75 does not take place with smooth, rapid shift of the movement of the piston from the return phase to the striking phase.
  • An air driven impact tool comprising a cylinder with a closed upper end, a chisel closing the bottom end of said cylinder, an impact piston movable within said cylinder and forming an upper cavity between said piston and said upper end and a lower cavity between said piston and said chisel; a casing attached to said cylinder at the upper portion thereof, a main valve body movably mounted in said casing, a limiting valve movably mounted in said casing, an adjustable throttle valve mounted within said casing, a one-way check valve movably mounted in said case, a compressed air supply port extending into said casing and acting to bias said main valve body in a first direction, a first passage communicating said compressed air to said upper cavi ty what said main valve bodyjs in said first djrecti n, a secon passage communicating compresse air rom said upper cavity to urge said limiting valve in a given direction; an exhaust valve connected to said cylinder below said casing, an opening communicating said exhaust valve to said lower cavity, a third
  • An air driven impact tool comprising a cylinder with a closed upper end, a chisel closingthe bottom end of said cylinder, an impact piston movable within said cylinder and forming an upper cavity between said piston and said upper end and a lower cavity between said piston and said chisel; a casing attached to said cylinder at the upper portion thereof, a main valve body movably mounted in said casing, time lag valve movably mounted in said casing, a one-way check valve movably mounted in said casing, an adjustable throttle valve mounted within said casing, a limitvalve operating member mounted within said casing and having a member extending into said upper cavity, a compressed air supply port extending into said casing and acting to bias said main valve body in a first direction, a first passage communicating said compressed air to said upper cavity when said main valve body is in said first direction; an exhaust valve connected to said cylinder below said casing, an opening communicating said exhaust valve to said lower cavity, a second passage from said casing to said exhaust valve communicating said lower cavity

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  • Fluid Mechanics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Percussive Tools And Related Accessories (AREA)

Abstract

An impact air driven tool. A cylinder has a piston slidable therein for striking a chisel, the chisel being operatively supported by a chisel holder secured to one end of said cylinder. A valve member is mounted within a valve casing and is reciprocated within said casing by piston operating air supplied into an upper cylinder cavity above the uppermost end surface of the piston and a lower cylinder cavity beneath the lowermost end surface of the piston. A limiting valve is provided and is operated by a variation of the amount of air within said cylinder for change-over of supply of said piston operating air to said valve member. A throttle valve is disposed in an intermediate portion of a passage through which compressed air for shifting the valve member from the advanced position to the original position is supplied from the limiting valve to the valve member. The throttle valve controls the flow of air to the valve member and thereby adjusts the duration of the piston resting phase during which the valve member is shifted.

Description

United States Patent Terada IMPACT AIR DRIVEN TOOL inventor: Hiromu Terada, lkoma, Japan Assignee: Nippon Pneumatic Manufacturing Company Limited, Osaka City, Osaka Prefecture, Japan Filed: May 21, 1970 Appl. No.: 39,390
[30] Foreign Application Priority Data Feb. 19, 1970 Japan ..45/ 14404 Feb. 19, i970 Japan ..45/ 14405 US. Cl ..173/137, 173/138 Int. Cl ..E2lb 1/00, 825d 9/00 Field of Search ..173/135, 137, 138
[56] References Cited UNITED STATES PATENTS 8/1966 Cooley et a1 ..l73/138 X 8/1939 Holloway ..173/ 137 X 3/1950 Horvath 173/137 X 6/1964 Zinkiewicz.... 173/137 X 6/1966 Leavell 173/137 X [57] ABSTRACT An impact air driven tool. A cylinder has a piston slidable therein for striking a chisel, the chisel being operatively supported by a chisel holder secured to one end of said cylindenA valve member is mounted within a valve casing and is reciprocated within said casing by piston operating air supplied into an upper cylinder cavity above the uppermost end surface of the piston and a lower cylinder cavity beneath the lowermost end surface of the piston. A limiting valve 1 is provided and is operated by a variation of the amount of air within said cylinder for change-over of 'supply of said piston operating air to said valve member. A throttle valve is disposed in an intermediate portion of a passage through which compressed air for shifting the valve member from the advanced position to the original position is supplied.
from the limitingvalve to the valve member. The throttle valve controls the flow of .air to the valve member and thereby adjusts the duration of the piston resting phase during which the valve member is shifted.
2 Claims, 9 Drawing; Figures PATENTED M13 1 5 I97? 3. 6 84 O 34 sum 1 or 5 HIROMU TERADA,
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- INVENTOR ATTORNEYS IMPACT AIR DRIVEN TOOL The present invention relates to an impact air driven tool utilizing compressed air for producing destructive forces.
The present invention has in its object to provide an impact air driven tool with which, as compared with one exemplary type of conventional impact air driven tools, a relatively greater value of striking energy per piston stroke can be obtained.
Another object of the present invention is to provide an improved impact air driven tool wherein the number of piston strokes can be varied from the zero value to the maximum possible value as desired so that the optimum value can be selected to suit to the capacity of a compressor in stock in case of said tool of the present invention being in effect connected with said compressor in stock.
These and other objects and features of the present invention will become apparent from the following description taken in conjunction with preferred embodiments thereof with reference to the attached drawings, in which:
FIG. 1 is a longitudinal sectional view of one embodiment of the present invention with a portion being broken away,
FIG. 2 is a cross-sectional view of a control valve mechanism in said embodiment of the present inventron,
FIG. 3 is a longitudinal sectional view of a throttle valve portion, on an enlarged scale, employed in the embodiment shown in FIG. 1,
FIG. 4 is a longitudinal sectional view, on an enlarged scale, of a rapid exhaust valve portion employed in the embodiment shown in FIG. 1,
FIG. 5 is alongitudinal sectional view of a modified embodiment of the present invention with a portion being broken away,
FIG. 6 is a cross-sectional view of a control valve mechanism employed in said modified embodiment shown in FIG. 5,
FIG. 7 is a longitudinal sectional view, on an enlarged scale, of a throttle valve portion employed in the modified embodiment shown in FIG. 5,
FIG. 8 is a longitudinal sectional view, on an enlarged scale, of a rapid exhaust valve portion employed in the modified embodiment shown in FIG. 5, and
FIG. 9 is a longitudinal sectional view, on an enlarged scale, of a check valve portion employed in the modified embodiment shown in FIG. 5.
As illustrated in the attached drawings, the improved impact air driven tool according to the present invention basically comprises a cylinder unit, a piston unit, a chisel unit, and a control valve unit for controlling the flow of compressed air supplied to said cylinder unit.
Referring now to FIG. 1 through FIG. 4 in which one preferred embodiment of the present invention is shown, reference numeral 11 represents a cylinder, 12 represents a top plate secured to an upper end of said cylinder, 13 represents a chisel holder secured to a lower end of said cylinder, 14 represents a chisel and 15 represents a piston slidably received in said cylinder.
end of said nipple 19 remote from said supply port 18 is rigidly connected with an elbow 20 to which a tubular hose connected from a suitable compressor means may be connected.
The valve casing 16 is secured at its right-hand side as viewed from FIG. 2 with a plate member 21 formed therein with a passage 22 communicating with a righthand opening 24 of a valve chamber 23.
The valve casing 16 is also provided therein with a limiting valve chamber 26 slidably receiving a limiting valve therein and with a valve chamber 28 having therein a tubular check valve 27 biased by a spring to the left within said valve chamber 28. This valve chamber 28 is formed at its outer peripheral surface with a tubular gap 29 and at its left-hand portion with a passage 31 communicating with said passage 22. Thus, said check valve 27 acts to permit the flow of air from the passage 31 to the gap 29, but to restrict said flow from the gap 29 to said passage 31.
The plate member 21 is also formed therein with an adjustable needle valve in the form of a throttle valve 32 situated between a passage 33 and a passage 34, which are also formed within the plate member 21, for regulating the flow of air passing between said passages 33 and 34. The passage 33 is communicated with the valve chamber 28 while the passage 34 is communicated with the gap 29.
The valve body 17 is formed at its right-hand portion with an enlarged diameter portion. 35 having a recess at its right-hand extremity in the axial direction thereof, so that when said valve body 17 is moved to the right an annular groove 36 on the inner peripheral surface of the valve chamber 23 can be closed by said enlarged diameter portion 35 while, when said valve body 17 is moved to the left, said annular groove 36 commences to communicate with the opening 24 through a righthand portion of said chamber 23 and also with said gap 29.
The valve body 17 is formed about its intermediate portion with a reduced diameter portion 40 which, upon movement of the valve body 17 to the right, acts to communicate between annular grooves 41 and 42 formed on the inner peripheral surface of the valve chamber 23 at a position around said reduced diameter portion 40. This annular groove 41 is directly communicated with an exhaust port 43 formed in the valve casing 16 and the annular groove 42 is directly communicated with a passage 44 formed as shown in FIG. 1, in a wall portion of the cylinder 1 l.
The valve chamber 23 is also formed on its inner peripheral surface at a left-hand portion next to the annular groove 41 with an annular groove 45 which.may be communicated with the annular groove 41 through said reduced diameter portion 40 when the valve body 17 is situated to the left, but blocked of its communication therewith when the valve body 17 is situated to the right. This annular groove 45 is directly communicated with a passage 46 open to the interior of the cylinder 11 at a position below an opening of the passage 39, as shown in FIG. 1.
The limiting valve 25 is formed at its intermediate portion with a reduced diameter portion 47 which, upon movement of said valve 25 to the right, acts to communicate between passages 48 and 49 formed on the inner peripheral surface of the valve chamber 26.
This passage 48 is directly communicated with the gap 29 and the passage 49 is directly communicated with the annular groove 37.
The valve chamber 26 is also formed in its peripheral wall at a position about the right-hand extremity of the limiting valve 47 with a passage 50 and about a lefthand portion of the limiting valve 47 with a passage 51 and a passage 52. The passage 50 is communicated with the annular groove 38 by means of the common passage 39 which is in turn open to the interior of the cylinder 11. The passage 51 is communicated with the annular groove 45 by means of the common passage 46 which is in turn open to the interior of said cylinder 11. The passage 52 may be communicated with the passage 48 through the reduced diameter portion 47 to permit the flow of air to an exhaust port 53 when the limiting valve 25 is moved to the left.
Reference numeral 54 represents a rapid exhaust valve casing secured to an intermediate portion of the cylinder 11. As shown particularly in FIG. 4, this rapid exhaust valve casing 54 is formed with a ventilating port 55 directly communicated with a ventilating hole 68 formed in the wall of the cylinder 11. Within said valve casing 54, a valve chamber 59 is formed for slidably receiving therein a valve member 56 capable of closing and opening the ventilating port 55. It should, however, be noted that the valve member 56 is formed with an auxiliary valve chamber 58 in which an auxiliary valve 57 in the form of a plate member is operatively mounted as shown in FIG. 4.
The valve 56 is formed at its left-hand portion with an opening 60 which may be closed by the auxiliary valve 57 when the latter is moved to the left. The auxiliary valve chamber 58 is formed at its depth with a plurality of holes 61 communicating between the righthand portion of the auxiliary valve chamber 58 and the ventilating port 55 and thus ventilating hole 68. This valve chamber 58 is also formed at a central portion of its depth with a slight projection which permits, together with a plurality of notches formed on the outer periphery of the auxiliary valve 57, the flow of air from the opening 60 to the holes 61 even when the righthand surface of the auxiliary valve 57 is contacted with the depth of said valve chamber 58 or the left-hand surface of said projection.
Provided at the left-hand extremity of the valve chamber 59 is an annular cushioning member 62, made of elastic material, having a through hole at its center, said through hole being communicated with a passage 69 which is in turn connected to the passage 44 formed in the wall of the cylinder 1 1.
However, it should be noted that the valve member 56 and accordingly the valve chamber 59 are stepped to give an enlarged diameter portion on the side adjacent to the ventilating port 55. Therefore, it will thus be understood that, when the valve member 56 is moved to the right, a cavity b will be formed betweenv said enlarged diameter portion of the valve chamber 59 and a correspondingly reduced diameter portion of the valve member 56. This cavity b is communicated with an exhaust port 65 by means of a small passage 64, the both of the latter being formed in a lower wall portion of the casing 54. At a lower portion of the casing 54 beneath said exhaust port 65, a plurality of small holes 66 are disposed for discharging the exhaust air from the port 65 to the atmosphere.
It should be noted that the valve casing 16 is rigidly secured at its left-hand side as viewed from FIG. 2 with another plate member corresponding to the abovementioned plate member 21, but the plate member at the left-hand side of the valve casing 16 is provided with an outlet hole communicated with the left-hand portion of the valve chamber 23.
In this arrangement as hereinbefore fully described, the operation of the improved impact air driven tool of the present invention is as follows.
When compressed air is supplied to the supply port 18 of the casing 16 through the elbow 20 and then nipple 19, the compressed air will flow to the annular groove 37 and then to the annular groove 38 communicated therewith by the reduced diameter portion 67 of the valve body 17. However, since the groove 38 is communicated to the passage 39 of which the other end is open to the interior of the cylinder 11, the compressed air thus supplied will cause the piston 15 to move downward.
At the same time, since the groove 37 is communicated with the limiting valve chamber 26 by means of the passage 49 which is at this time communicates with the passage 48 by the reduced diameter portion 47 of the limiting valve 25, the other end of said passage 48 being communicated to the gap 29 around the check valve 27, the same compressed air will be introduced to said gap 29 and via passage 34 directed to the throttle valve 32 formed in the plate member 21.
While the check valve 27 is normally positioned as illustrated in FIG. 2, the air in the passage 34 will pass through a clearance a of the throttle valve 32 to the passage 33 and then to the passage 31 passing through the check valve 27. Thereafter, the air in the passage 31 will be introduced to the opening 24 through the passage 22 into the recess formed on the right-hand extremity of the valve member 17 in the axial direction. However, since the throttle valve 32 provides a narrow clearance a as shown in FIG. 3, the air is somewhat slowly supplied from the passage 34 into the recess, and the value of pneumatic pressure will, accordingly, slowly increase.
In addition thereto, since a passage communicating the groove 38 to the passage 39 open to the interior of the cylinder 11 is communicated with the passage 50 which is in turn communicated with the right-hand portion of the limiting valve chamber 26, the compressed air will also be supplied to the right-hand extremity of the valve 25 through said passage 50. The compressed air supplied into the interior of the cylinder 11 by means of the passage 39 will then flow into the passage 46, which is in turn introduced against the left-hand extremity of the limiting valve 25 through the passage 51. However, since the working area of the left-hand extremity of the limiting valve 25 is greater than that of the right-hand extremity thereof, the limiting valve 25 is biased to the right even when as a result, pressure of the compressed air acts on both extremities thereof.
While in this condition, the annular groove 42 in the chamber 23 is communicated with the annular groove 41 by the reduced diameter portion 40 of the valve member 17 and then to the atmosphere through the exhaust port 43 formed in a wall portion of the casing 16. Accordingly, it will be clearly understood that the valve chamber 59 within the rapid exhaust valve casing 54 is communicated to the atmosphere by means of the passage 44 extending from the passage 69 communicated with said chamber 59. Therefore, as the piston moves downward, the air contained in a lower cylinder cavity defined between the lower extremity of the piston 15 and the upper extemity of the chisel 14 will open the valve member 56 and escape therefrom to the atmosphere through the ventilating port 55, the exhaust port 65 and then a plurality of the small holes 66. Thus, the piston 15 is rapidly moved downward to abut against the upper extremity of the chisel 14.
As a value of pneumatic pressure in the recess at the right-hand extremity of the valve body 17 gradually increases in excess of a value of pneumatic pressure acting on an annular area on the left-hand side of the enlarged diameter portion 35 so as to move the valve body 17 to the right, the valve body 17 commences to move to the left. As soon as the right-hand extemity of the valve body 17 thus passes through an O-ring provided to the right of the annular groove 36, the valve body will be rapidly moved to the left because pneumatic pressure that has been applied to the annular groove 36 is added to the pneumatic pressure applied through the opening 24.
Upon completion of the movement of the valve body 17 to the left, the grooves 37 and 42 in the valve chamber 23 are communicated to each other by the reduced diameter portion 67 while communication between the grooves 37 and 38 and communication between the grooves 41 and 42 are respectively cut off. Accordingly, the compressed air supplied to the supply port 18 will flow to the passage 44 through the groove 37and then the groove 42, pressing the valve member 56 and the auxiliary valve 57 to the right and passing through the notches on the periphery of the auxiliary valve 57 and then the holes in the depth of the auxiliary valve chamber 58, and finally be supplied through the ventilating hole 68 by means of the ventilating port 55 into the lower cylinder cavity defined by the lower extremity of the piston and the upper extremity of the chisel. A seal ring provided in the peripheral surface of the right-hand end of the valve member 56 is at this time tightly contacted to the adjacent end surface of the ventilating port 55 so as to prevent the air in the ventilating port from leaking out.
At the same time as hereinbefore described, the grooves 41 and 45 in the valve chamber 23 are also communicated to each other by the reduced diameter portion 40, permitting the passage 46 to communicate with the exhaust port 43 and then to atmosphere through said grooves 41 and 45. Accordingly, the air contained in an upper cylinder cavity defined between the upper extremity of the piston 15 and the back of the top plate 12 will be discharged to the atmosphere through the passage 46 that has been communicated with the exhaust port 43. Thus, the piston 15 commences to move upward.
In addition, when the groove 45 is communicated to the atmosphere, the passage 51 is also communicated to the atmosphere. At this time, a value of pressure in the passage 39 and thus a valve of pressure in the passage communicated therewith are equalized to the atmosphere. Thus, the limiting valve 25 remains to the right.
However, as the piston 15 moves upward and sub sequently its upper extremity closes the passage 46, the
remaining air in the upper cylinder cavity will be compressed and subsequently pressure of said compressed air be applied through the passage 50 to the right-hand extremity of the limiting valve 25 to move the latter to the left.
As the limiting valve 25 moves to the left, the passage 48 is communicated by the reduced diameter portion 47 of the valve 25 with the passage 52, permitting the air in the gap 29 and the groove 36 to be discharged to the atmosphere therethrough by means of the exhaust port 53.
Thus, as a valueof pressure within the gap 29 and the annular groove 36 is equalized to the atmosphere, a value of pressure within the right-hand portion of the valve chamber 23 also reaches atmospheric and, therefore, the valve body 17 is moved to the right by the ac tion of pressure acting on the left-hand extremity of said enlarged diameter portion 35. As soon as the lefthand extremity passes through an O-ring provided to the right of the groove 36, communication between the groove 36 and the right-hand portion of the valve chamber 23 will be cut off with subsequent increase of a value of pressure within said right-hand portion of the valve chamber 23, the increased pressure then acting through the passage 31 to the check valve 27 so as to open the latter. As the check valve 27 is thus opened, the air within the right-hand portion of the chamber 23 can be discharged from the exhaust port 53 in the order through the passage 22, passage 31, gap 29, passage 48 and finally the passage 52, and, thus, the movement of the valve body 17 to the right completes to establish the condition as shown in F l6. 2.
As a result, compressed air is again supplied into the upper cylinder cavity while the passage 44 is communicated to the atmosphere.
Accordingly, it will be clearly understood that the valve chamber 59 within the rapid exhaust valve casing 54 is again communicated to the atmosphere by means of the passage 44 extending from the passage 69 communicated with said chamber 59. Then, in the same manner as has been seen during the previous downward movement of the piston 15 within the cylinder 11, the air contained in the lower cylinder cavity will again open the valve member 56 and escape therefrom to the atmosphere through the ventilating port 55, the exhaust port 65 and finally the small holes 66, while the piston 15 is again abutted against the upper extremity of the chisel 14.
Subsequently, as the upper extremity of the piston 15 clears the opening of the passage 46 during its downward movement, the compressed air supplied through the passage 39 into the upper cylinder cavity will again flow to the passage 51 by means of the passage 46, applying its pneumatic pressure to the lefthand extremity of the limiting valve 25 thereby to move the latter to the right. Thus, the limiting valve 25 can be positioned as illustrated in FIG. 2.
As hereinbefore fully described, so long as compressed air is supplied to the supply port 18 of the improved impact air driven tool of the present invention, the above-mentioned operation of one cycle may be repeated, wherein the piston is fiercely reciprocated within the cylinder to strike on the upper extremity of the chisel and thereby to perform the intended work.
According to the preferred embodiment of the present invention as shown in FIG. 1 through FIG. 4, by adjusting the opening, or a value of the clearance a, of the throttle valve 32, the number of piston strokes per unit time can be varied as desired. Even in the event that the number of piston strokes per unit time is varied, a value of striking energy per piston stroke does not vary at all. The reason therefor will be hereinafter set forth.
It should be noted that the piston 15 within the cylinder 1 1 has a striking phase wherein the valve body 17 and the limiting valve 25 are positioned as shown in FIG. 2, a resting phase which continues from the time at which the piston strikes the chisel 14 until the time at which the piston commences its upward movement away from the chisel, and a return phase wherein the upward movement of the piston takes place. However, the resting phase is a time duration of the valve body 17 moving from the right to the left within its valve chamber 23, commencing at the moment that the piston 15 strikes the chisel 14 and ending at the moment that the piston 15 commences its upward movement away from the chisel.
Accordingly, if the throttle valve 32 is constructed in the form of screw type needle valve as substantially shown in FIG. 3, a value of pneumatic pressure acting on the right-hand extremity of the valve body 17 can be rapidly increased by adjusting the valve 32 so as to increase a value of the clearance a, resulting in the reduction of the time necessary for the valve body 17 to complete its movement from the right to the left, that is to say, duration of the resting phase.
On the contrary, if the throttle valve 32 is adjusted so as to reduce the value of said clearance a, the duration of the resting phase may be prolonged.
As hereinbefore described, change of the duration of the resting phase results in the change of the number of piston strokes per unit time. It will be thus understood that the adjustment of the throttle valve merely affects the duration of the resting phase independent of the striking phase and the return phase. Therefore, the number of the piston strokes per unit time can be advantageously adjusted without any substantial reduction of the amount of the striking energy obtained by the improved impact air driven tool of the present invention.
Referring now to FIG. through FIG. 9 in which a modified embodiment of the present invention is shown, reference numeral 71 represents a cylinder, 72 represents a top plate secured to an upper end of said cylinder, 73 represents a chisel holder, 74 represents a chisel, and 75 represents a piston slidably received in said cylinder.
Reference numeral 76 represents a valve casin secured to a lateral upper portion of said cylinder 71, in which valve casing a valve body 77 is slidably received. This valve casing 76 is formed with a compressed air supply port 78 to which a nipple 79 is pivotably connected. One end of said nipple 79 remote from said port 78 is rigidly connected with an elbow 80 to which a tubular hose connected from a suitable compressor means may be connected. The valve casing 76 is secured at its both right-hand and left-hand sides as viewed from FIG. 6 with a pair of plate members 81 and 92, one of which or the right-hand plate member 81 being formed therein with a passage 82 communicated with an opening 84 of a valve chamber 83 in which said valve body 77 is slidably received.
The valve casing 76 is also provided therein with a time lag valve chamber 86 in which a time lag valve 85 is slidably received and with a valve chamber 88 in which a check valve 87 is provided. Provided around the outer periphery of said valve chamber 88 is an annular gap 89. The chambers 88 and 86 are connected to each other by a passage 91. The check valve 87 is normally biased to the right within its valve chamber 88 so as to permit the flow of air from the passage 91 to the gap 89, but to restrict the flow of air from the gap 89 to the passage 91.
The other or left-hand plate member 92 is provided therein with a throttle valve 93 in the form, for example, of an adjustable needle valve and at a suitable position with an exhaust hole communicating between the left-hand portion of the chamber 83 and the atmosphere.
The throttle valve 93 is positioned between a passage 94 communicated with the valve chamber 88 and a passage 95 communicated with the gap 89, so as to act to regulate the flow of air therebetween.
The valve body 77 is formed at its intermediate portion with a reduced diameter portions 103 and 140 and at its right-hand end with an enlarged diameter portion 96 which is in turn formed at its right-hand extremity with a circular recess in the axial direction thereof. The valve chamber 83 is provided on its inner peripheral surface with annular grooves 97 and 98 which can be isolated from each other by the enlarged diameter portion 96 as the valve body 77 is moved to the left, said passage 98 being in turn connected with a passage 99 open to the interior of the cylinder 71 and said passage 97 being in turn connected with the supply port 78.
This valve chamber 83 is also formed on a left-hand inner peripheral surface with a plurality of annular grooves 100, 101 and 102, the grooves 100 and 101 being communicated to each other by the reduced diameter portion 103 of the valve body 77 when the latter is moved to the left while the grooves 101 and 102 being communicated to each other by said reduced diameter portion of the valve body 77 when the latter is moved to the right. The groove 100 is in turn connected with a passage 104 open to the interior of the cylinder 71 at a position below the opening of the passage 99 formed on the inner peripheral surface of the cylinder 71, the groove 101 is in turn connected with an exhaust port 105 formed in the casing 76 and the groove 102 is in turn connected with a passage 106 formed in a wall portion of the cylinder 71.
The time lag valve 85 is formed at its intermediate portion with a reduced diameter portion 107 which, upon movement of said valve 85 to the left, acts to communicate between passages 108 and 109 formed on the inner peripheral surface of the valve chamber 86. The passage 108 is directly connected with an exhaust port 110. To the left of said passage 108, a passage 111 communicating between the valve chamber 86 and a passage 112 which is in turn connected to a passage 95 formed in the plate member 92.
The valve chamber 86 is also formed at its right-hand portion with a passage 1 13 connected to the groove 97, the right-hand portion 114 of the chamber 86 being also connected to said groove 97. The right-hand portion 114 is designed to slidably receive a right-hand reduced diameter portion 115 of the time lag valve 85 therein, the diameter of said reduced diameter portion 115 being smaller than that of the left-hand extremity of the valve body 85. The right-hand portion is provided on its left-hand inner peripheral surface with an O-ring, to the left of which O-ring the valve chamber 86 is somewhat enlarged to give its diameter greater than that of the right-hand portion 114. About the boundary between said portion 114 and that enlarged portion of the valve chamber 86, an exhaust hole communicating between that enlarged portion of the chamber 86 to the atmosphere is provided.
The cylinder 71 is provided on its inner peripheral surface at a position below the opening of the passage 104 formed thereon with another opening in which a limiting valve operating member 116 is collapsibly mounted in such a manner as to project a portion thereof toward the interior of the cylinder 71 unless the projected portion 'is backwardly retracted by the piston 75. This operating member 116 is in the form of a ball and, as shown in FIG. 9, acts to operate a limiting valve 118 in a valve chamber 117 formed within a limiting valve casing 145 formed in the cylinder wall. The limiting valve 118 is normally biased toward the operating member 116 by a spring 119 and will operate when the operating member 116 is collapsed by the piston 75.
The valve chamber 117 is formed about its outer periphery with a passage 120 communicated with the passages 111 and 112 within the valve casing 76 and the passage 95 in the plate member 92 by means of an annular cavity 121 formed in said valve casing 117.
This valve chamber 117 is also formed at its depth with a valve seat 122 to which the limiting valve 118 is seated by the spring 119. Provided around said valve seat 122 is a passage 123 communicated with an exhaust port 125, formed in the valve casing 76, through a passage 124 formed in the cylinder wall. Provided adjacent to the left-hand extremity of the limiting valve 118 is a cavity 141 formed in the valve casing 76 in communication with the annular groove 97 within the valve chamber 83 by means of a passage 146. The limiting valve 118 is also formed at its left-hand extremity with a recess 142 of a desired depth in communication with a passage 143 which is in turn connected with the annular cavity 121 by means of a passage 144, the both passages 143 and 144 being formed within the valve casing 145 at a position adjacent to the left-hand exv tremity of the limiting valve 118.
Reference numeral 126 represents a rapid exhaust valve casing secured to the cylinder 71. As shown particularly in FIG. 8, this rapid exhaust valve casing 126 is formed with a ventilating port 127 directly communicated with a ventilating hole 146 formed in the wall of the cylinder 71. Within said valve casing 126, a valve chamber 129 is formed for slidably receiving therein a valve member 128 capable of closing and opening the ventilating port 127. The valve member 128 is formed with an auxiliary valve chamber 130 in which an auxiliary valve 131 in the form of a plate member is operatively mounted.
The valve member 128 is formed at its left-hand por tion with an opening 132 which may be closed by the auxiliary valve 131 when the latter is moved to the left.
The auxiliary valve chamber is formed at its depth with a plurality of holes 133 communicating between the right-hand portion of the auxiliary valve chamber 130 and the ventilating port 127 and thus the ventilating hole 146. This valve chamber 129 is also formed at a central portion of its depth with a slight projection which permits, together with a. plurality of notches formed on the outer periphery of the auxiliary valve 131, the flow of air from the opening 132 to the holes 133 even when the right-hand surface of the auxiliary valve 131 is contacted with the depth of said valve chamber 129 or the left-hand surface of said projection.
Provided at the left-hand extremity of the valve chamber 129 is an annular cushioning member 134, made of elastic material, having a through hole at its center, said through hole being communicated with a passage 135 which isin turn connected to the passage 106 formed in the wall of the cylinder 71.
However, it should be noted that the valve member 128 and accordingly the valve chamber 129 are stepped to give an enlarged diameter portion on the side adjacent to the ventilating port 127. Therefore, it will thus be understood that, when the valve member 128 is moved to the right, a cavity d will be formed between said enlarged diameter portion of the valve chamber 129 and a correspondingly reduced diameter portion of the valve member 128. This cavity d is communicated with an exhaust port. 138 by means of a small passage 137, the both of the latter being formed in a lower wall portion of the casing 126. At a lower portion of the casing 126 beneath said, exhaust port 138, a plurality of small holes 139 are disposed for discharging the exhaust air from the port 139 to the atmosphere.
While in the arrangement of the modified embodiment of the present invention as hereinbefore fully described, the improved impact air driven tool according thereto may function in such a manner as hereinafter set forth.
When compressed air is supplied to the supply port 78 of the casing 76 through the elbow 80 and then nipple 79, the compressed air will flow to the annular groove 97 and then to the annular groove 98 communicated therewith by the reduced diameter portion 140 of the valve body 77. However, since the groove 98 is communicated to the passage 99 of which the other end is open to the interior of the cylinder 71 at a position above the upper extremity of the piston 75, the compressed air thus supplied will cause the piston 75 to move downward.
At the same time, the annular groove 102 connected to the passage 135 of the rapid exhaust valve casing 126 by means of the passage 106 is communicated by the reduced diameter portion 103 of the valve body 77 with the annular groove 101 communicated in turn to the exhaust port 105. Accordingly, it will be clearly un derstood that, as the piston 75 is downwardly moved, the air contained in a lower cylinder cavity defined between the lowermost end surface of said piston and the uppermost end surface of the chisel 74 will press the valve member 128 whereby said air can be discharged to the atmosphere through the exhaust port 138 and then the holes 139, resulting in the rapid downward movement of the piston to strike the chisel 74.
The annular groove 97 is then communicated with the right-hand portion 1 14 of the valve chamber 86 and the groove 1 13 which is in turn communicated with the time lag valve chamber 215. Accordingly, the compressed air will also act on the right-hand reduced diameter portion 115 of the time lag valve 85 to render the valve 85 to move to the left and thereby to close the passage 113, as shown in FIG. 6. In addition, since the groove 97 is communicated with the cavity 141 of the limiting valve casing by means of the passage 146, the pneumatic pressure will also act on the left-hand extremity of the valve 118 and then flow to the annular cavity 121 in the order through the recess 142, passage 143 and passage 144. Then, the air in the annular cavity 121 then in part flow to the passage 95 in the plate member 92 and thus to the passage 94 through a clearance c of the throttle valve 93. The air in the passage 94 is introduced against the left-hand extremity of the time lag valve 85 through the check valve 87 by means of the passage 91. Also, the compressed air in the passage 85 will in part flow into the gap 89, acting on the check valve 87.
Accordingly, the compressed air is slowly accumulated within a left-hand portion of the valve chamber 88 and the passage 91 via the clearance c of the throttle valve.
Although the compressed air acts on the both extremities of the time lag valve 85 as hereinbefore described, the time lag valve 85 is positioned to the left until a value of pressure of the compressed air acting on the left-hand extremity of the valve 85 increases over that of pressure acting on the right-hand reduced diameter portion 115 of said valve. Upon increase of the value of pressure acting so as to move the valve 85 to the right in excess of the value of pressure acting so as to move the valve 85 to the left, the valve 85 commences to move to the right. As soon as the left-hand extremity of the valve 85 passes through the O-ring positioned at the left side of the valve chamber 86, it can be rapidly moved to the right as pressure in the passage 112 is also applied through the passage 111 to the left-hand extremity thereof, until the right-hand reduced diameter portion 115 is abutted against the cushioning member provided at the depth of the righthand portion 1 14 of the chamber.
As the time lag valve 85 is thus moved to the right, the reduced diameter portion 107 of said valve communicates the passage 109 with the passage 113. However, it should be noted that the compressed air from the groove 97 always exists in the passage 113 throughout the operation of the impact air driven tool of the present invention. Therefore, upon communication between the passages 109 and 113, the air flows into the passage 109 from the passage 113 and the to the right-hand portion of the chamber 83 through the opening 84 by means of the passage 82 communicated therewith. This air thus supplied then acts on the righthand extremity of the enlarged diameter portion 96 of the valve body 77 so as to move the latter to the left.
As the valve body 77 is moved to the left, the reduced diameter portion of the valve 77 communicates the groove 101 with the groove 100 while an intermediate portion of said valve 77 isolates the grooves 101 and 102 and the reduced diameter portion 140 of the valve 77 communicates the groove 97 with the groove 102 while the enlarged diameter portion 96 thereof closes the groove 98. Subsequently, the air in the groove 97 is supplied to the passage 106 through the groove 102 and then to the passage 135, then passing through the notches on the periphery of the auxiliary valve 131 and then the ventilating port 127 into the lower cylinder cavity defined between the lowermost end of the piston and the uppermost end of the chisel. Thus, it will be understood that the piston is upwardly moved thereby. At this time, the seal ring provided in the peripheral surface of the right-hand end of the valve member 128 is tightly contacted to the adjacent end surface of the ventilating port 127 so as to prevent the air in the ventilating port from leaking out.
While in this condition as hereinbefore described, the air contained in the upper cylinder cavity is discharged to the atmosphere in the order through the passage 104, the grooves 100 and 101 communicated to each other, and the exhaust port 105 of the casing 76.
However, as the piston 75 is upwardly moved a sufficient distance, the limit valve operating member 116 is backwardly retracted by the uppermost end of said piston. Rectraction of said member 116 will cause the limit valve 118 to move to the left, compressing the spring 119 while closing the passage 143 in the valve 118. At this time, the passage 124 communicated to the atmosphere commences to communicate with the valve chamber 1 17. However, since this valve chamber 117 is communicated with the left-hand portion of the valve chamber 86 through the passage 120, the annular groove 121, and the passages 112 and 111, the air in said portion of the valve chamber 86 is exhausted and the time lag valve 85 is moved to the left under the influence of the pneumatic pressure always existing in the right-hand portion 114 as supplied from the groove 97. Also, upon communication of the passage 112 with the exhaust port 125, the air in the passage 95 and the gap 89 is exhausted while the air contained in the check valve 87 and the passage 91 presses the check valve 87 so as to open the latter so that this air is also exhausted through the exhaust port 125 by means of the gap 89.
Thus, when the time lag valve 85 is moved to the left as hereinbefore described, the passages 108 and 109 are communicated to each other and the air contained in the right-hand portion of the valve chamber 83 can be discharged to the atmosphere via the opening 84,
the passage 82 and then through the exhaust port. Ac-
cordingly, the valve body 77 is returned to the right with its enlarged diameter portion 96 being applied with pneumatic pressure in the left-hand portion of the valve chamber 83, thus commencing the next cycle of operation.
As hereinbefore fully described, so long as compressed air is supplied to the supply port 78 of the improved impact air driven tool of the present invention, the above-mentioned cycle of its operation may be repeated, wherein the piston 75 is fiercely reciprocated within the cylinder to strike on the upper extremity of the chisel 74 and thereby to perform the intended work.
Even in the modified embodiment of the impact air driven tool of the present invention, the number of piston strokes per unit time can be varied by adjusting the opening, or the value of the clearance c, of the throttle valve 93 as in the first mentioned embodiment of the present invention. Similarly, even in the event that the number of piston strokes per unit time is varied, the value of striking energy per piston stroke does not vary at all.
More particularly, it should be noted that the piston 75 within the cylinder 71 has a striking phase, a resting phase and a return phase throughout each cycle of operation. However, according to the modified embodiment of the present invention, by adjusting the duration of the resting phase of the piston, the number of piston strokes per unit time can be varied without affecting the striking phase and the return phase.
In other words, the resting phase of the piston 75 represents a duration of time between the time at which the piston strikes the chisel and the time-at which said piston commences its upward movement away from said chisel. However, this time duration may be determined by the time necessary for the time lag valve 85 to complete its movement to the right after the piston strikes the chisel.
In order to cause the time lag valve 85 to move from the left to the right, it is necessary to increase the value of pneumatic pressure acting through the clearance c of the throttle valve 93 on the left-hand extremity of said valve 85. Accordingly, it will be clearly understood that the time necessary for the time lag valve 85 to complete its movement to the right after the piston strikes the chisel can be varied by adjusting the size of the clearance c and thereby to adjust the rate of increase of the pneumatic pressure acting therethrough on the lefthand extremity of said time lag valve 85.
Accordingly, if the throttle valve 73 is constructed in the form of screw type needle valve as substantially shown in FIG. 7 in order to permit the adjustment of the size of the clearance c, the number of piston strokes per unit time can be varied through controlling the duration of the resting phase of the piston.
, In addition thereto, in the modified embodiment of the present invention, the impact air driven tool is designed such that the limiting valve 118 is actuated to bring the time lag valve 85 into the striking phase during the return movement of the piston 75 away from the chisel 74 and thereby to bring the valve body 77 into the striking phase through the shifting movement of said valve 85. Therefore, retardation of the shifting movement of the valve body 77 with respect to the movement of the piston 75 does not take place with smooth, rapid shift of the movement of the piston from the return phase to the striking phase.
What I claim is:
1. An air driven impact tool comprising a cylinder with a closed upper end, a chisel closing the bottom end of said cylinder, an impact piston movable within said cylinder and forming an upper cavity between said piston and said upper end and a lower cavity between said piston and said chisel; a casing attached to said cylinder at the upper portion thereof, a main valve body movably mounted in said casing, a limiting valve movably mounted in said casing, an adjustable throttle valve mounted within said casing, a one-way check valve movably mounted in said case, a compressed air supply port extending into said casing and acting to bias said main valve body in a first direction, a first passage communicating said compressed air to said upper cavi ty what said main valve bodyjs in said first djrecti n, a secon passage communicating compresse air rom said upper cavity to urge said limiting valve in a given direction; an exhaust valve connected to said cylinder below said casing, an opening communicating said exhaust valve to said lower cavity, a third passage from said casing to said exhaust valve communicating said lower cavity to atmosphere when said main valve body is in said first direction; said piston being forced downwardly to strike said chisel when said compressed air is supplied to said upper cavity; a channel through said adjustable throttle valve to slowly supply said compressed air to bias said main valve body in a direction opposite said first direction, whereby a predetermined time after said piston strikes said chisel said main valve body is moved in said opposite direction, said first passage being blocked from communication with said compressed air and exhausted to atmosphere when said main valve body is in said opposite direction, and said third passage being connected to said compressed air supply when said main valve body is in said opposite direction such that compressed air is supplied to said lower cavity.
2. An air driven impact tool comprising a cylinder with a closed upper end, a chisel closingthe bottom end of said cylinder, an impact piston movable within said cylinder and forming an upper cavity between said piston and said upper end and a lower cavity between said piston and said chisel; a casing attached to said cylinder at the upper portion thereof, a main valve body movably mounted in said casing, time lag valve movably mounted in said casing, a one-way check valve movably mounted in said casing, an adjustable throttle valve mounted within said casing, a limitvalve operating member mounted within said casing and having a member extending into said upper cavity, a compressed air supply port extending into said casing and acting to bias said main valve body in a first direction, a first passage communicating said compressed air to said upper cavity when said main valve body is in said first direction; an exhaust valve connected to said cylinder below said casing, an opening communicating said exhaust valve to said lower cavity, a second passage from said casing to said exhaust valve communicating said lower cavity to atmosphere when said main valve body is in said first direction; said piston being forced downwardly to strike said chisel when said compressed air is supplied to said upper cavity; a channel through said adjustable throttle valve to slowly supply said compressed air to urge said time lag valve in a given direction, whereby a predetermined time after said piston strikes said chisel said tine lag valve and said main valve body are moved in directions opposite to said given direction and first direction, respectively, said first passage being blocked from communication with said compressed air and exhausted to atmosphere when said main valve body is in said opposite direction, said second passage being connected to said compressed air supply when said time lag valve is in said opposite direction such that compressed air is supplied to said lower cavity, and said member of said limit valve operating member being movable upon contact by said piston when said piston moves upwardly.

Claims (2)

1. An air driven impact tool comprising a cylinder with a closed upper end, a chisel closing the bottom end of said cylinder, an impact piston movable within said cylinder and forming an upper cavity between said piston and said upper end and a lower cavity between said piston and said chisel; a casing attached to said cylinder at the upper portion thereof, a main valve body movably mounted in said casing, a limiting valve movably mounted in said casing, an adjustable throttle valve mounted within said casing, a one-way check valve movably mounted in said case, a compressed air supply port extending into said casing and acting to bias said main valve body in a first direction, a first passage communicating said compressed air to said upper cavity when said main valve body is in said first direction, a second passage communicating compressed air from said upper cavity to urge said limiting valve in a given direction; an exhaust valve connected to said cylinder below said casing, an opening communicating said exhaust valve to said lower cavity, a third passage from said casing to said exhaust valve communicating said lower cavity to atmosphere when said main valve body is in said first direction; said piston being forced downwardly to strike said chisel when said compressed air is supplied to said upper cavity; a channel through said adjustable throttle valve to slowly supply said compressed air to bias said main valve body in a direction opposite said first direction, whereby a predetermined time after said piston strikes said chisel said main valve body is moved in said opposite direction, said first passage being blocked from communication with said compressed air and exhausted to atmosphere when said main valve body is in said opposite direction, and said third passage being connected to said compressed air supply when said main valve body is in said opposite direction such that compressed air is supplied to said lower cavity.
2. An air driven impact tool comprising a cylinder with a closed upper end, a chisel closing the bottom end of said cylinder, an impact piston movable within said cylinder and forming an upper cavity between said piston and said upper end and a lower cavity between said piston and said chisel; a casing attached to said cylinder at the upper portion thereof, a main valve body movably mounted in said casing, time lag valve movably mounted in said casing, a one-way check valve movably mounted in said casing, an adjustable throttle valve mounted within said casing, a limit valve operating member mounted within said casing and having a member extending into said upper cavity, a compressed air supply port extending into said casing and acting to bias said main valve body in a first direction, a first passage communicating said compressed air to said upper cavity when said main valve body is in said first direction; an exhaust valve connected to said cylinder below said casing, an opening communicating said exhaust valve to said lower cavity, a second passage from said casing to said exhaust valve communicating said lower cavity to atmosphere when said main valve body is in said first direction; said piston being forced downwardly to strike said chisel when said compressed air is supplied to said upper cavity; a channel through said adjustable throttle valve to slowly supply said compressed air to urge said time lag valve in a given direction, whereby a predetermined time after said piston strikes said chisel said tine lag valve and said main valve body are moved in directions opposite to said given direction and first direction, respectively, said first passage being blocked from communication with said compressed air and exhausted to atmosphere when sAid main valve body is in said opposite direction, said second passage being connected to said compressed air supply when said time lag valve is in said opposite direction such that compressed air is supplied to said lower cavity, and said member of said limit valve operating member being movable upon contact by said piston when said piston moves upwardly.
US39390A 1970-02-19 1970-05-21 Impact air driven tool Expired - Lifetime US3684034A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP1440470A JPS4830947B1 (en) 1970-02-19 1970-02-19
JP1440570A JPS4830948B1 (en) 1970-02-19 1970-02-19

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US3684034A true US3684034A (en) 1972-08-15

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US (1) US3684034A (en)
DE (1) DE2030097C3 (en)
ES (1) ES380443A1 (en)
FR (1) FR2080297A5 (en)
GB (1) GB1310758A (en)
NL (1) NL7101537A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115742042A (en) * 2022-12-01 2023-03-07 泉州煮石山房创意工艺制品有限公司 Pneumatic lettering process for carving hard stone

Citations (5)

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Publication number Priority date Publication date Assignee Title
US2170757A (en) * 1935-07-30 1939-08-22 Holloway Patents Ltd Power hammer
US2500036A (en) * 1945-12-22 1950-03-07 Cleveland Pneumatic Tool Co Cushioned handle for portable percussive tools
US3137483A (en) * 1958-01-24 1964-06-16 Zinkiewicz Wiktor Ground burrowing device
US3255832A (en) * 1962-11-27 1966-06-14 Leavell Charles Vibrationless percussive tool
US3266581A (en) * 1963-11-01 1966-08-16 Mechanical Res Corp Vibrationless power tool

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2170757A (en) * 1935-07-30 1939-08-22 Holloway Patents Ltd Power hammer
US2500036A (en) * 1945-12-22 1950-03-07 Cleveland Pneumatic Tool Co Cushioned handle for portable percussive tools
US3137483A (en) * 1958-01-24 1964-06-16 Zinkiewicz Wiktor Ground burrowing device
US3255832A (en) * 1962-11-27 1966-06-14 Leavell Charles Vibrationless percussive tool
US3266581A (en) * 1963-11-01 1966-08-16 Mechanical Res Corp Vibrationless power tool

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115742042A (en) * 2022-12-01 2023-03-07 泉州煮石山房创意工艺制品有限公司 Pneumatic lettering process for carving hard stone

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DE2030097A1 (en) 1971-09-09
GB1310758A (en) 1973-03-21
NL7101537A (en) 1971-08-23
FR2080297A5 (en) 1971-11-12
DE2030097B2 (en) 1973-10-18
DE2030097C3 (en) 1974-05-16
ES380443A1 (en) 1973-04-01

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