US3440928A - Impulse tool having shutoff mechanism - Google Patents

Description

April 29, 1969 Filed Sept. 8, 1967 R. W. PAULEY ETAL IMPULSE TOOL HAVING SHUTOFF MECHANISM Sheet of 2 INVENTORS REGINALD n. PAULEY LE 0 KRAMER ATTORNEY April 969 R. w. PAULEY ETAL 3,440,928

IMPULSE TOOL HAVING SHUTOFF MECHANISM Filed Sept. 8, 196'? Sheet 2 of 2 FIG. 4

58a INVENTORS REGINALD 14 PAULEY' LEO KRAMER ATTORNEY United States Patent 3,440,928 IMPULSE TOOL HAVING SHUTOFF MECHANISM Reginald W. Pauley, Belle Mead, and Leo Kramer, Skillman, N.J., assignors to Ingersoll-Rand Company, New

York, N.Y., a corporation of New Jersey Filed Sept. 8, 1967, Ser. No. 666,441 Int. Cl. F01c 21/12 US. Cl. 91-59 Claims ABSTRACT OF THE DISCLOSURE An impulse tool including a chamber connected to receive fluid from the high pressure portion of the spindle cavity and to discharge fluid to the low pressure portion of such cavity. A normally closed valve controls the flow of fluid into the chamber; and a second normally closed valve controls the discharge of fluid from the chamber. The motor of the tool is connected to be shut off when the pressure of fluid in the chamber attains a predetermined pressure; and the second valve is opened, to relieve the pressure of fluid in the high pressure portion, when the pressure of fluid in the chamber exceeds this predetermined pressure.

Background of the invention The present invention relates to impulse tools and more particularly to impulse tools of the type including a mechanism for shutting off the driving motor of the tool in response to a predetermined torque output of the tool.

conventionally, the high and low pressure portions of the spindle cavity of an impulse tool have frequently been connected by a fluid passage, containing a pressure relief valve, in an attempt to limit the torque output of the tool by limiting the pressure of the fluid in the high pressure portion. Moreover, in some instances, as disclosed in United States Patent No. 3,116,617 issued J an. 27, 1964, to Donald K. Skoog, the fluid flowing through this fluid passage has been employed to actuate a mechanism which shuts off the tool. In these conventional impulse tools, however, a fixed restriction is provided between the shutoff mechanism and the low pressure portion to provide sufficient back pressure to enable the shutoff mechanism to properly function.

This construction has been, however, frequently undesirable and disadvantageous. For example, when the relief valve opens, as during the tightening of a high rate joint, this fixed restriction has been found to frequently cause an excessive back pressure which results in an undesirable overtorquing of the fastener driven by the tool.

The principal object of the present invention is to provide an impulse tool which includes a new and improved shutoff mechanism particularly constructed and arranged to substantially minimize the aforedescribed back pressure and resultant overtorquing.

Summary of the invention This object, and those other objects and advantages of the invention which will be apparent from the following description taken in connection with the accompanying drawings, are attained by the provision of a new and improved shutoff mechanism for an impulse tool which includes housing means provided with a cavity sealingly containing a fluid, and spindle means in the housing means and in the fluid. A drive means is operatively associated with a first of the housing means and the spindle means for causing relative rotary movement between the housing means and the spindle means. A sealing means, associated with the housing means and the spindle means, is operable during a relatively small portion of each revolution of the relative rotary movement to dynamically seal the cavity into a high pressure portion and a low pressure portion to produce a primary pressure pulse in the high pressure portion and on the other of the housing means and the spindle means, thereby causing the other to rotate with respect to the first of the housing means and the spindle means.

The new and improved shutoff mechanism, more specifically, comprises a connecting chamber, first passage means for supplying fluid from the high pressure portion of the cavity to the connecting chamber, second passage means for discharging fluid from the connecting chamber to the low pressure portion of the cavity, and a valve for controlling fluid flow from the first passage means to the chamber. A valve means is provided for restricting the flow of fluid from the chamber when the pressure of fluid in the chamber is less than a predetermined pressure and for permitting increased fluid flow from the chamber through the second passage means when the pressure of the fluid exceeds such predetermined pressure, whereby the pressure of fluid in the high pressure portion of the cavity is relieved through the aforementioned fluid passages and the chamber when the pressure of fluid in the chamber exceeds the predetermined pressure. A means is also provided for shutting off the drive means in response to the pressure of fluid in the chamber.

Brief description of the drawings FIG. 1 is an elevational view, partially broken away and in section, of an impulse tool including an embodiment of the present invention;

FIG. 2 is an enlarged sectional view taken on line 22 of FIG. 1, looking in the direction of the arrows;

FIG. 3 is an enlarged, elevational sectional view of the embodiment of the invention in the impulse tool illustrated in FIG. 1; and

FIG. 4 is a fragmentary view generally similar to FIG. 3, but illustrating an alternative embodiment of the invention as applied to the impulse mechanism of an impulse tool.

Description of the preferred embodiments Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, FIG. 1 illustrates an impulse tool designated generally as 10 which comprises a housing or casing 12 formed to include a barrel 14 and a handle 16 depending from the barrel 14. A rotatable spindle shaft 18 projects from the forward end of the barrel 14 and rigidly carries a socket 20 which is adapted to rotatably drive a fastener or other workpiece during its rotation with the spindle shaft 18.

The impulse tool 10 is powered by a pneumatically operated motor, designated generally as 22, which is carried by the barrel 14 adjacent the rearward end of the latter. The pneumatically operated motor 22, as illustrated, is of the vane type and comprises a rotor 24, a rotatably mounted shaft 26 formed integrally with the rotor 24 and projecting from the opposing ends of the rotor 24, and a plurality of vanes 28 carried by the rotor 24. Pressurized air is supplied to the pneumatically operated motor 22 through an inlet passage '30 formed in the handle 16, a cavity 32 communicating with the inlet passage 30, and a valve chamber 34 which connects the cavity 32 with an inlet passage 36 leading to the pneumatically operated motor 22. The flow of pressurized air through the inlet passage 30 is controlled by a conventional, normally closed, flow control valve, designated generally as 38, which is suitably mechanically connected to the trigger or actuator 40 of the impulse tool 10 to be opened upon manual depression of the trigger 40.

The flow of pressurized air from the cavity 32 to the valve chamber 3 4 is controlled by a valve assembly designated generally as 42. The valve assembly 42 is of conventional construction and comprises a slidably mounted trip valve 44 which includes a plurality of fluid passages or bores 46, 48 for balancing the pressures upon opposing sides of the trip valve 44. An exhaust passage 54, connected to the rearward end of the valve chamber 34, communicates through a chamber 55 with an exhaust bore 56 which discharges to the atmosphere. A coil spring 50 is disposed within the valve chamber 34 with one of its ends bearing against the trip valve 44 and the other of its ends engaging a ball valve 52 which controls the flow of pressurized air through the exhaust passage 54. This arrangement, as will be seen, causes the coil spring 50 to bias the trip valve 44 to an open position and simultaneously bias the ball valve 52 to a closed position. Thus, during the normal operation of the impulse tool 10, pressurized air is permitted to flow from the cavity 32 to the inlet passage 36' through the valve chamber 34, but is prevented from exhausting from the valve chamber 34, through the exhaust passage 54. When, however, the ball valve 52 is sufficiently displaced to permit the flow of pressurized air through the exhaust passage 54, the pressurized air in the valve chamber 34 rearwardly of the trip valve 44 is exhausted, thereby causing the trip valve 44 to move to a position preventing the flow of pressurized air from the cavity 32 to the inlet passage 36.

The impulse mechanism of the impulse tool is generally similar to that disclosed in the aforementioned United States Patent No. 3,116,617 issued Jan. 27, 1964, to Donald K. Skoog and comprises a housing means 58, disposed within the casing 12 adjacent the forward end of the barrel 14, which includes an eccentric cavity 60 sealingly containing a fluid such as oil. A rotatable spindle or spindle means 62, formed integral with the spindle shaft 18, extends through the cavity 60 and the fluid contained in the latter. The housing means 58, as illustrated in FIG. 1, is rotatably journalled in bearings 64 and spline connected to the shaft 26 of the pneumatically operated motor 22. Alternatively, however, the spindle 62 could be connected to the shaft 26 to be rotatably driven by the pneumatically operated motor 22, providing that the socket is suitably mounted on the housing means 58 for rotation with the latter.

A sealing means is provided for sealing the cavity 60 into a high pressure portion HP and a low pressure portion LP during the rotation of the housing means 58 relative to the spindle 62. As illustrated in FIG. 2, this sealing means comprises a spindle blade 66 slidably mounted within a transverse slot 67 in the spindle 62, and a pair of opposing lands 68, spaced by undercuts 70, on the housing means 58 in the cavity 60. The spindle blade 66 and the lands 68 cooperate, during a relatively small portion of each revolution of the rotation of the housing means 58 relative to the spindle 62, to dynamically seal the cavity 60 into the high pressure portion HP and the low pressure portion LP to produce a primary pressure pulse in the fluid in the high pressure portion HP and on the spindle 62. This primary pressure pulse, as will be understood, causes the spindle 62 to rotate with respect to the housing means 58 and thereby rotatably drives the socket 20. A slot 72 is provided in the spindle blade 66 to prevent the aforedescribed sealing means from sealing the cavity 60 into the high and low pressure portions HP and LP, respectively, in excess of once during each rotation of the housing means 58 relative to the spindle 62. Moreover, it will be understood that in those instances in which the spindle 62 is connected to the pneumatically operated motor 22, the sealing means will be suitably arranged to cause the primary pressure pulse to rotate the housing means 58.

The embodiment of the shutoff mechanism included in the impulse tool 10, as illustrated in FIG. 3, comprises a first or connecting chamber 74 which is formed in the housing means '58. The chamber 74 is connected at one of its ends to a fluid passage or bore 76 which communicates with the high pressure portion HP such that fluid from the high pressure portion HP is supplied to said end of the chamber 74. The chamber 74 is connected intermediate its ends to a fluid passage or bore 78 which communicates with the low pressure portion LP of the cavity 60 such that fluid may be discharged from the chamber 74 to the low pressure portion LP. The chamber 74, moreover, is connected, intermediate its connections to the fluid passages 76, 78, to a signal passage or bore 80 which communicates with a second or pilot chamber 82 for discharging fluid to the latter.

The second chamber 82 contains a slidable piston 84 which is rigidly mounted upon one end of an actuating rod 86. The actuating rod 86 projects rearwardly in the casing 12 and, at its other end, engages a ball 88 which is slidably disposed in a bore 90 formed longitudinally through the shaft 26 of the pneumatically operated motor 22. The ball 88, in turn, bears against one end of an actuating rod 92, slidably disposed in the bore 90, which is threadedly connected at its opposing end to a cap member 94. The cap member 94 is forwardly biased, to urge the actuating rods 86, 92 and the ball 88 forwardly in the casing 12, by a spring 96 which is positioned in a spring chamber 98 at the rearward end of the barrel 14 of the casing 12. The cap member 94, furthermore, is suitably connected to a lever arm 100, including an end 102 engaging the ball valve 52, such that movement of the cap member 94 against the spring 96 causes the lever arm to open the ball valve 52.

A fluid passage or bore 104 connects the rearward end of the chamber 82 with the low pressure portion LP of the cavity 60 such that fluid from the low pressure portion LP is supplied to the chamber 82 rearwardly of the piston 84 during the operation of the shutoff mechanism. A relatively small diameter bleed passage 105 directly connects the signal passage 80 with the bore 104 for permitting a limited quantity of fluid to bypass the piston 84.

A valve means is provided for controlling the flow of fluid from the fluid passage 76 to the chamber 74. In addition, a valve means is provided for controlling the fluid exhausted from the chamber 74 through the fluid passage 78 such that the flow of fluid from the chamber 74 is restricted until the pressure of fluid in the chamber 74 exceeds a predetermined pressure whereupon the pressure of fluid in the chamber 74, and hence in the high pressure portion HP, is relieved. More specifically, as illustrated in FIGS. 1 and 3, a ball valve 106 is slidably disposed within the chamber 74 at the end of the latter communicating with the fluid passage 76. A piston valve 108 is slidably disposed in the chamber 74 in abutment with the ball valve 106 and arranged to control the flow of fluid from the chamber 74 through the fluid passage 78. The ball valve 106 and the piston valve 108 are biased by a single spring 110 to closed positions wherein they restrict the flow of fluid into the chamber 74 through the fluid passage 76 and from the chamber 74 through the fluid passage 78, respectively, to prevent such flows of fluid.

During the operation of the impulse tool 10, depression of the trigger 40 causes pressurized air to flow through the inlet passage 30 and the cavity 32 to the valve chamber 34 from whence it is directed by the inlet passage 36 to the pneumatically operated motor 22. The pressurized air which is thus supplied to the pneumatically operated motor 22 rotatably drives the latter and, through the spline connection of the housing means 58 to the shaft 26, effects simultaneous rotation of the housing means 58 relative to the spindle 62, as indicated by the arrow in FIG. 2. This rotation of the housing means 58 causes the spindle blade 66 to cooperate with the lands 68 to seal the cavity 60 into the aforementioned high pressure portion HP and low pressure portion LP to create a primary pressure pulse in the high pressure portion HP and on the spindle 62. The primary pressure pulse, as will be understood, causes the spindle 62 to rotate relative to the housing means 58 and thereby rotatably drives the socket 20 which is carried by the spindle shaft 18. In this manner, the fastener or other workpiece driven by the spindle 62 is rotated until the pressure of the fluid in the high pressure portion HP attains a predetermined pressure which is sufliciently high to overcome the preset resistance of the spring 110.

At this time, the fluid in the fluid passage 76 moves the ball and piston valves 106, 108, respectively, sufficiently to enable it to flow into the signal passage 80 and to the chamber 82. The fluid which thus enters the chamber 82 moves the piston 84 rearwardly to thereby cause the actuating rods 86, 92 and the ball 88 to urge the cap member 94 against its biasing spring 96-. The movement of the cap member 94 against the spring 96 actuates the lever arm 100 to cause the end 102 of the latter to open the ball valve 52, whereupon the valve chamber 34 is exhausted through the exhaust passage 54. This exhausting of the valve chamber 34 causes the trip valve 44 to move to a closed position wherein it prevents pressurized air from flowing from the cavity 32 to the valve chamber 34. Thus, the supply of pressurized air to the pneumatically operated motor 22 is automatically shut off by the fluid flowing into the chamber 82.

The aforedescribed shutting-oh of the pneumatically operated motor 22 does not, of course, immediately stop the rotation of the housing means 58. Rather, the momentum of the latter causes its continued rotation and, thereby, causes the pressure of the fluid in the high pressure portion HP, and in the fluid passage 76, to be increased to a pressure in excess of the aforementioned predetermined pressure. This increased pressure, as will be understood, moves the piston valve 108 to an open position wherein the pressure of fluid in the high pressure position HP is relieved, through the fluid passages 76, 78 and the chamber 74, to prevent overtorquing of the fastener or other workpiece driven by the spindle 62. Thus, it Will be seen that the pneumatically operated motor 22 is shut olf by fluid at a predetermined pressure; and the piston valve 108 is opened by fluid at a pressure in excess of this predetermined pressure.

FIG. 4 illustrates an alternative embodiment of the shutoff mechanism in combination with the impulse mechanism of an impulse tool designated generally as a. It will be understood that the impulse mechanism of the impulse tool 10a is constructed similarly to that of the aforedescribed impulse tool 10 and that, hence, the parts of the impulse mechanism shown in FIG. 4 have been designated by the reference character for their respective similar parts of the impulse tool 10 followed by the suflix a. It Will also be understood that, except as otherwise described with reference to the embodiment of the shutoff mechanism illustrated in FIG. 4, the remainder of the impulse tool 10 is constructed identically to the impulse tool 10.

Referring more particularly to FIG. 4, the embodiment of the shutoff mechanism therein illustrated comprises a first or connecting chamber 112 which is formed in the housing means 58a. The chamber 112 is connected at one of its ends to a fluid passage 114 which communicates with the high pressure portion HP of the cavity 60a such that fluid from the high pressure portion HP is directed to such end of the chamber 112. The chamber 112 contains a ball valve 116 which is biased by a spring 118 to a closed position at the aforementioned end of the chamber 112 such that it normally prevents the flow of fluid from the fluid passage 114 into the chamber 112.

The chamber 112 is connected intermediate its ends to a fluid passage or bore 120 which communicates through an inlet cavity 122 with a second chamber 124. A fluid passage or bore 126 is connected to the valve chamber 124 adjacent the rearward end of the latter and communicates the chamber 124 with the low pressure portion LP of the cavity 60a. The chamber 124 contains a valving member 128 which is rigidly mounted upon an axially movable supporting rod 130 and biased by a spring 132 to a closed position wherein it prevents the flow of fluid from the inlet cavity 122 to the valve chamber 124. The inlet cavity 122 is, however, directly connected by a relatively small diameter, bleed passage 134 to the fluid passage 126 such that a limited quantity of fluid may bypass the chamber 124 and the valving member 128. The supporting rod 130 is connected to a lever arm (not shown) in the manner in which the actuating rod 86 is shown as connected to the lever arm in FIGS. 1 through 3. This lever arm, moreover, is constructed and arranged similarly to the lever arm 100 such that axial movement of the supporting rod causes the supply of pressurized air to the pneumatically operated motor of the impulse tool 10a to be shut off.

The operation of the embodiment of the shutolf mechanism illustrated in FIG. 4 is believed to be apparent from the aforegoing description taken in connection with FIG. 4, and in view of the previous description of the operation of the impulse tool 10 shown in FIGS. 1 through 3. It should be noted, however, that, in the operation of the embodiment illustrated in FIG. 4, the valve member 128 is initially moved against the spring 132, by fluid at a predetermined pressure, to cause the motor of the tool 10a to be shut otf and thereafter moved an additional distance against the spring 13 2, by fluid at a pressure in excess of such predetermined pressure, to a position wherein the fluid passages 120, 126 communicate through the chamber 124. Thus, as in the embodiment of the invention illustrated in FIGS. 1 through 3, the FIG. 4 embodiment is constructed such that the motor of the tool is shut off at a predetermined pressure of fluid; and the high pressure portion HP is communicated with the low pressure portion LP at a pressure in excess of this predetermined pressure. It will be understood, moreover, that, although FIGS. 1 through 4 illustrate the shutoff mechanism as being provided in the housing means 58, 580, it could be alternatively provided in the spindles 62, 62a.

From the aforegoing it will be seen that We have provided new and improved means for accomplishing all of the objects and advantages of our invention. It will be understood, however, that, although we have specifically illustrated and described only two embodiments of our invention, our invention is not limited merely tothese illustrated and described embodiments but contemplates other embodiments and variations which utilize the concepts and teachings of our invention.

Having thus described our invention, We claim:

1. For an impulse tool having housing means provided with a cavity sealingly containing a fluid, spindle means in said cavity and in said fluid, drive means operatively associated with a first of said housing means and said spindle means for causing relative rotary movement between said housing means and said spindle means, sealing means associated with said housing means and said spindle means operable during a relatively small portion of each revolution of said relative rotary movement to dynamically seal said cavity into a high pressure portion and a low pressure portion to produce a primary pressure pulse in said high pressure portion and on the other of said housing means and said spindle means, thereby causing said other to rotate with respect to said first of said housing means and said spindle means, a shutoff mechanism comprising:

a connecting chamber;

first passage means for supplying fluid from said high pressure portion of said cavity to said connecting chamber;

second passage means for discharging fluid from said connecting chamber to said low pressure portion of said cavity;

a valve for controlling fluid flow from said first passage means to said connecting chamber;

valve means for normally restricting fluid flow from said connecting chamber through said second passage means and for permitting increased fluid flow from said connecting chamber through said second passage means when the pressure of fluid in said connecting chamber exceeds a predetermined pressure, whereby the pressure of fluid in said high pressure portion is relieved through said fluid passages and said connecting chamber when the pressure of fluid in said connecting chamber exceeds said predetermined pressure; and

means operable, in response to the pressure of fluid in said connecting chamber, for shutting off said drive means.

2. A shutoff mechanism according to claim 1, further comprising: bypass passage means for discharging a restricted flow of fluid from said connecting chamber to said low pressure portion when said valve means restricts the flow of fluid through said second passage means.

3. A shutoff mechanism according to claim 2, further comprising:

means for biasing said valve to a position wherein it restricts fluid flow into said connecting chamber; and

said shutoff means being actuatable to shut off said drive means by fluid supplied to said connecting chamber through said first passage means when such fluid attains said predetermined pressure.

4. A shutoff mechanism according to claim 3, further comprising:

said second passage means including a second chamber,

a passage communicating said connecting chamber with said second chamber, and a second passage communicating said second chamber with said low pressure portion of said cavity; and

said valve means being disposed within said second chamber.

5. For an impulse tool having housing means provided with a cavity sealingly containing a fluid, spindle means in said cavity and in said fluid, drive means operatively associated with a first of said housing means and said spindle means for causing relative rotary movement between said housing means and said spindle means, sealing means associated with said housing means and said spindle means operable during a relatively small portion of each revolution of said relative rotary movement to dynamically seal said cavity into a high pressure portion and a low pressure portion to produce a primary pressure pulse in said high pressure portion and on the other of said housing means and said spindle means thereby causing said other to rotate with respect to said first of said housing means and said spindle means, a shutoff mechanism in one of said housing means and said spindle means, comprising:

a connecting chamber;

first passage means for supplying fluid from said high pressure portion of said cavity to said connecting chamber;

second passage means for discharging fluid from said 8 connecting chamber to said low pressure portion of said cavity;

a valve for controlling fluid flow from said first passage means to said connecting chamber;

means actuatable for shutting off said drive means;

and valve means for normally restricting fluid flow from said connecting chamber through said second passage means and operable, in response to the pressure of fluid in said connecting chamber attaining a predetermined pressure, for actuating said shutoff means; said valve means being movable, in response to the pressure of fluid in said connecting chamber exceeding said predetermined pressure, for permitting increased fluid flow from said connecting chamber through said second passage means, whereby the pressure of fluid in said high pressure portion is relieved through said fluid passages and said connecting chamber when the pressure of fluid in said connecting chamber exceeds said predetermined pressure. 6. A shutoff mechanism according to claim 5, further comprising: bypass passage means for discharging a restricted flow of fluid from said connecting chamber to said low pressure portion when said valve means restricts the flow of fluid through said second passage means.

7. A shutoff mechanism according to claim 5, further comprising:

said second passage means including a second chamber, a first passage for communicating said connecting chamber with said second chamber, and a second passage for communicating said second chamber with said low pressure portion of said cavity; and

said valve means being disposed within said second chamber.

8. A shutoff mechanism according to claim 7, further comprising: bypass passage means connecting said passages for discharging a restricted flow of fluid from said first passage to said second passage when said valve means restricts the flow of fluid through said second passage means.

9. A shutoff mechanism according to claim 8, further comprising: means for biasing said valve to a position wherein it restricts fluid flow into said connecting chamber.

10. A shutoff mechanism according to claim 9, further comprising: said housing means containing said connecting chamber and said first and second passage means.

EVERETTE A. POWELL, JR., Primary Examiner.

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