US3924961A

US3924961A - Pneumatic torqueing tool

Info

Publication number: US3924961A
Application number: US530047A
Authority: US
Inventors: Johann Hess; Kurt Paule; Kurt Latzina; Richard Wolf
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1973-12-15
Filing date: 1974-12-05
Publication date: 1975-12-09
Anticipated expiration: 1992-12-09
Also published as: SE7415625L; DE2362458A1; NL7416284A; SE398996B; GB1466198A

Abstract

A pneumatic torqueing tool, particularly a pneumatic wrench, has a housing in which a pneumatic motor is mounted that is rotatable in two mutually opposite directions. A fluid conduit system is provided including a fluid passage which supplies pneumatic fluid to the motor when the same is to rotate in one of these directions. An adjustable throttle valve controls the flow of fluid through this passage and includes a valve member a portion of which is movable into and out of an orifice in the passage. A first arrangement mounts the valve member so that it can be gradually adjusted relative to the orifice whereby the portion of the valve member varies the effective cross section of the orifice. Another arrangement is provided for rapidly withdrawing the valve member with its portion entirely from the orifice in order to expose the maximum effective cross section thereof.

Description

United States Patent 11 1 11 1 ,924,961 Hess et al. [4 Dec. 9, 1975 PNEUMATIC TORQUEING TOOL 3,696,834 10/1972 Vonhoff, Jr 173/169 3,833,068 9/1974 Hall [75] Inventors Johan" Hess Kurt Paul, both of 3,861,476 1/1975 BOI'SUm 173/169 Stuttgart; Kurt Latzina,

Waldenbuch; Richard Wolf, Stuttgart, all of Germany [73] Assignee: Robert Bosch GmbH, Stuttgart,

Germany Primary ExaminerHenry F. Raduazo Attorney, Agent, or FirmMichael S. Striker [57] ABSTRACT [22] Flled: 1974 A pneumatic torqueing tool, particularly a pneumatic [21] Appl. No.: 530,047 wrench, has a housing in which a pneumatic motor is mounted that is rotatable in two mutually opposite directions. A fluid conduit system is provided including [30] Forelgn Application Priority Data a fluid passage which supplies pneumatic fluid to the Dec. 15, Germany motor when the same is to rotate in one of these directions. An adjustable throttle valve controls the flow of UeS- Clthrough passage and includes a alve mem- 173/169 ber a portion of which is movable into and out of an Int. Cll rifice in the passage A first arrangement mounts the [58] Field of Search 415/157, 152, 503, 30,

valve member so that it can be gradually adjusted rela- 415/32, 38; 7 168, 169 tive to the orifice whereby the portion of the valve member varies the effective cross section of the ori- [56] References Cited fice. Another arrangement is provided for rapidly UNITED STATES PATENTS withdrawing the valve member with its portion en- 3,011,480 12/1961 Vilmerding 415/152 tifely from the Orifice in Order expose the maximum 3,298,284 1/1967 Alexander 173/169 ffective cross section thereof.

3,510,099 5/1970 Crump 173/169 3,667,345 6/1972 Schaedler et al. 173/169 7 Clalms, 4 Drawmg Figures US. Patent Dec. 9, 1975 Sheet 1 of2 3,924,961

PNEUMATIC TORQUEING TOOL BACKGROUND OF THE INVENTION The present invention relates to a pneumatic torqueing tool, and is particularly applicable to pneumatic wrenches.

Pneumatic wrenches are already known and are, for example, used in the automobile industry to tighten and loosen nuts on wheels of automotive vehicles. When such a wrench is used to tighten a nut the compressed air is supplied to the pneumatic motor of the wrench via a throttle valve; when the nut is to be loosened, that is when the direction of rotation of the pneumatic motor is to be reversed, the throttle valve is bypassed and the compressed air is supplied to the pneumatic motor directly since the torque required for removing a nut (whose threads may have become corroded or which may otherwise be difficult to turn) is almost invariably greater than the torque required for tightening it. Therefore, in bypassing the throttle valve the compressed air is supplied to the pneumatic motor directly so that the latter will develop its full torque.

In the prior-art torqueing tools of this type the throttle valve is either continuously variable or can be adjusted in steps; when the valve is set for the largest possible throughput of fluid, its throttling effect has been reduced practically to zero.

The torqueing tools of this type that are known from the prior art have been found to be a great advantage in the industry. However, they are still possessed of certain drawbacks which are generally found to be objectionable. For example, if the valve is set to permit the pneumatic motor to develop a large amount of torque, as would be required for tightening wheel nuts on trucks or the like, it must subsequently be reset if the tool is to be used for another application, for example for tightening wheel nuts on a passenger automobile where the amount of torque previously used for tightening the wheel nuts on the much larger bolts of a truck would be excessive and might lead to damage. Experience has shown that under the pressure of work this readjustment is frequently overlooked, with the result that the threads on smaller bolts and nuts are stripped, requiring replacement of the affected parts.

SUMMARY OF THE INVENTION It is therefore a general object of the invention to overcome the disadvantages of the prior art.

More particularly, it is an object of this invention to provide a pneumatic torqueing tool, particularly a pneumatic wrench, which is not possessed of the aforementioned disadvantages.

Still more specifically, an object of the invention is to provide such a pneumatic torqueing tool wherein an adjustable throttle valve is provided which permits the pneumatic motor to develop maximum torque in response to a simple manipulation of the throttle valve without, however, causing or requiring any change in the setting of the throttle valve for applications wherein less than maximum torque is required.

Another object of the invention is to provide a torqueing tool of the type in question which is simple in its construction and operation.

In keeping with these objects, and others which will become apparent hereafter, one feature of the invention resides. in a pneumatic torqueing tool, particularly a pneumatic wrench, in a combination which comprises a housing, a pneumatic motor in the housing and rotatable in a first direction and also in an opposite second direction, and fluid conduit means which includes a fluid passage for supplying pneumatic fluid to the motor when the same is to rotate in the first direction. According to the invention we provide an adjustable throttle valve for controlling the flow of fluid through the passage, and this throttle valve comprises a valve member having a valve member portion movable into and out of an orifice in the passage, first means mounting the valve member for gradual adjustment of the axial position of the valve member portion within the orifice to thereby vary the effective cross-section of the latter, and second means for rapidly withdrawing the valve member portion entirely from the orifice to thereby expose the maximum effective cross-section thereof.

The maximum effective cross-section that can be set in the orifice by gradual adjustment of the axial position of the valve member portion is smaller than the effective crosssection which influences the flow of pneumatic fluid to the pneumatic motor when the latter is to rotate in the opposite second direction, that is in the direction in which it loosens rather than tightens a threaded element.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partially sectioned side view illustrating a torqueing tool according to the present invention;

FIG. 2 is an end view of FIG. 1, looking towards the left;

FIG. 3 is a fragmentary enlarged sectional view, illustrating the sectioned detail of FIG. 1; and

FIG. 4 is a view similar to FIG. 3 but illustrating a different embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1-3 illustrate one embodiment of the invention wherein a torqueing tool is illustrated which in this particular case is a pneumatic wrench. The tool has a housing 1 at the front of which (the left-hand end in FIG. 1) a tool socket or the like is provided, whereas the rear end of the housing (the right-hand end in FIG. 1) has affixed to it a flange 2 on which there is mounted by means of screws 3a a cover 3. A sealing plate 4 is interposed between the flange 2 and the cover 3. A protective ring 5 of rubber or synthetic elastomeric material is pulled over the juncture between the flange 2 and the cover 3.

The cover 3 is formed with a passage portion 6 which communicates via a circular orifice 7 with a passage portion 8 in the flange 2. The housing 1 itself is provided with a conduit 9 communicating with the passage portion 8 and also communicating in a not illustrated manner with a compressed air inlet 11. The communication between the inlet 11 and the conduit 9 can be established and interrupted by operation of a valve controlled by the illustrated trigger 10. It is pointed out here that insofar as some reference numerals appear in parentheses in FIGS. 1 and 2, these are reference numerals that will be described with respect to the embodiment in FIG. 4 but which designate components of the embodiment in FIGS. l3 that are employed identically in FIG. 4 and have merely been given different numerals. The manner in which the valve operated by the trigger is constructed and operates is well known in the art of trigger-controlled pneumatic torqueing tools and therefore requires no detailed description or illus tration, especially as it does not form a part of the invention.

The flow of compressed air from the conduit 9 through the passage portion 8 and from there through the orifice 7 into the passage portion 6 is controlled by the novel throttle valve of the present invention, and in particular by a valve plate 12 which is normally located in the orifice 7.

FIG. 3 shows details of the throttle valve utilized in FIGS. 1 and 2 to control the flow of fluid from the inlet 11 via the

passage

8, 6 to the diagrammatically illustrated pneumatic motor M. The throttle valve has a valve body 13 the rear end of which (the end remote from the orifice 7) is constructed as a knob 14 that can be turned. The knob 14 has a roughened circumferential surface (no details shown) and is formed with a lateral projection 15 that is most clearly visible in FIG. 2 and which, when the knob 14 is turned, engages an abutment pin 15a that is mounted in the cover 3 to delimit the rotational displacement of the knob 14. Forwardly (i.e. inwardly) of the knob 14 the valve body 13 is stepped to form a cylindrical portion 16 of reduced diameter which is formed in the region of its forward end with an external thread 17. The external thread 17 meshes with the internal thread 18 that will be seen to be formed in a bore 21 of the cover 3. Intermediate the thread 17 and the head 14 the cylindrical portion 16 is formed with a narrow circumferential groove 19 in which a O-ring 20 is located which engages the circumferential wall bounding the bore 21 to provide a sealing action. The rear end of the valve body 13 is formed with a bore 22 from which a smaller-diameter bore 23 extends forwardly to the front end of the valve body 13 where the bore 23 is enlarged to form a chamber 24 of polygonal (e.g. quadratic, hexagonal or the like) crosssection, in which a matingly configurated nut 25 is received so that the nut 25 cannot turn but has freedom of axial displacement longitudinally of the chamber 24.

A valve member 26 is formed at its front end with a valve plate 12 which is located within the orifice 7 and can be shifted axially relative thereto. The valve member 26 carries at its rearward end (the rightward end in FIG. 3) a cylindrical plate 27 which is formed with a slot 28 into which a screwdriver or similar tool may be turning for tuning the plate 27 and therefore the valve member 26. Inwardly of the plate 27 the valve member 26 has a cylindrical shaft portion 29 formed with a circumferential groove 30 in which another Oring 31 is located. The shaft portion 29 is guided in the bore 23 of the valve body 13 for shifting displacement in the bore 23. The forward (left-hand) portion of the shaft portion 29 is formed with an external thread 32 which meshes with a self-retarding action with the internal thread of the nut 25. Thus, the valve member 26 cannot turn relative to the nut 25 as a result of vibrations that are transmitted to it; such turning can be effected only by inserting a tool into the slot 28 and exerting sufficient force to effect turning. A helical spring 33 surrounds 4 the righthand portion of the shaft portion 29 and be ars with its opposite ends against the valve body 13 and the plate 27, respectively.

The lefthand facing radial face of the knob I4 is formed with a plurality of circumferentially distributed depressions 34 located on a circle surrounding the longitudinal axis of the valve body 13. Spaced from this axis by the same distance as are the depressions 34 is a blind bore 35 that is formed in the cover 3 and in which a pin 36 is slidably received, being urged outwardly by a biasing spring 37 which urges the conical outer end of the pin 36 against the radial face of the knob 14 which is formed with the depressions 34, so that when one of the depressions 34 registers with the pin 36, the latter will snap into it to provide a detent action.

When the torqueing tool having the valve of FIG. 3 is to be operated the knob 14 is turned until the valve plate 12 exposes in the orifice 7 the largest possible effective cross-section for the passage of pneumatic fluid to the motor M, in order to make the same rotate in one direction in which it will cause nuts or the like to be tightened, that is normally in the right-hand direction. This position is reached when the knob 14 has been turned until the projection 15 abuts the pin 150. By turning the plate 27 via a screwdriver or the like the valve member 26 turns in the nut 25 and thus becomes displaced axially either towards the left or towards the right in FIG. 3, until the valve plate 12 has assumed a position relative to the orifice 7 in which the desired maximum quantity of compressed air flows from the passage portion 8 into the passage portion 6 and from there to the pnaumatic motor M. If subsequently the knob 14 is turned to one of the other detent positions determined by the respective depressions 34, a user can correspondingly select different fractions of the pre-set maximum throughput of air to the motor M.

The valve can thus be set to enable the motor M to furnish a selected amount of torque, for example the amount of torque required to tighten nuts on the bolts of wheels on passenger automobiles. If for some reason, for example because the tool is temporarily to be used for tightening the nuts on bolts of wheels on trucks where the bolts and the nuts are much stronger than those used on passenger automobiles, it is desired that the motor M should develop maximum torque during the nut-tightening movement, then it is not necessary to turn the blade 27 to a different position and to thereby readjust the valve. Instead, the user simply needs to push in the blade 27, by exerting pressure upon it in leftward direction in FIG. 3. This causes the nut 25 and the valve member 26 to be shifted leftward so that the valve plate 12 moves completely out of the orifice 7, thereby exposing the maximum effective cross-section of the orifice so that air can freely flow from the passage portion 8 into the passage portion 6 and from there to the motor M to enable the latter to develop maximum torque.

Subsequently, that is when the operation requiring maximum torque for tightening of the nut is completed, there is no danger that the user might forget to reset the valve to a lower-torque operation, because as soon as the leftward pressure upon the plate 27 is relaxed the spring 33 restores the valve member 26 to its original preselected position where the flow of fluid to the motor M is throttled and the torque developed by the motor M is therefore correspondingly smaller.

It will be understood that if the motor M is to turn in the opposite direction, that is normally left since un- FIG. 4 shows a further embodiment of a valve according to the present invention which can-be used in the .tool shown in FIGS. 1 and 2.- This valve is even more foolproof against improper operationthan is the one shown in FIG. 3.

In FIG. 4 the cover 3 of FIGS. 1-3 isreplaced with a cover 103 that is formed with a bore 121 the lefthand end (in FIG. 4) of which is formed with an internal thread 118. The fluid passage has the passageportion 106 in the cover 103 and a passage portion 108 in the flange 102 which replaces the flange 2 of the embodiment in FIG. 1. The

passage portions

106 and 108 communicate with one another via a circular orifice 107. The passage portion 108 communicates with the air inlet conduit 109 in the housing 101, which inlet conduit 109 receives compressed air from the inlet 1 1 (see FIG. 1) via a control valve having a trigger 110 (see FIG. 1). i i

A valve body 113 is threaded into the threads 118 and has a front end portion 116 of cylindrical configuration which is formed with an external thread 117. The rear end portion of the valve body 113 is again constructed as a knob, here identified with reference numeral 114 and formed with aroughened outer sur-' face; the knob 114 has a radially extending projection 115 as shown in FIG. 2, which can abut a pin 115a mounted in the cover 1 13 to delimit the extent to which the knob 114 can be turned. The left-hand end face of the knob 114 is formed with a plurality of circumferentially distributed depressions 134 into which a pin 136 can snap which is guided in a bore 135 of the cover 103 and is biassed outwardly of the bore by a spring 137. The cylindrical portion 116 of the valve body 113 is formed with a circumferential groove 119 in which an O-ring 120 is accommodated which provides a seal for the valve body 113 with reference to the bore 121 in the housing cover 103.

The exposed or right-hand end of the knob 114 is formed with a cylindrical recess 122 from which a bore 123 of lesser cross-sectional area extends forwardly through the valve body 113; the forward end of the bore 123 is enlarged to form a cylindrical chamber 132 whose cross-sectional area is greater than that of the remainder of the bore 123. A tubular valve element 126 is accommodated in the bore 123 so that it can both turn and axially shift therein. The left-hand end of the valve element 126 is formed with a portion 126a of enlarged diameter which is slidably and tumably guided in the chamber 132 and formed in its circumferential surface with a groove 130 accommodating an O- ring 131 which seals the member 126 with reference to the valve body 113. The rear or right-hand end of the member 126 is formed with a slot 126b, and a cap 127 (preferably of synthetic plastic material) is pressed over this rear end. A bore 126c extends through the member 126 is axial direction and its front end is formed with an internal thread 126d.

A valve member 112 carries at its front end a valve plate 112a from which a shaft 112b extends, the rear end of which is formed with external threads 1126 which mesh with the internal threads 126d of the member 126 in such a manner as to provide a self-retarding action, that is these threads engage one another tightly enough so that the

members

112 and 126 cannot turn with reference to one another unless this is specifically accomplished by removing the cap 127 and inserting a tool, such as a screwdriver, through the bore 1266' into engagement with the slot 1 12d formed in the right-hand end of the shaft 1l2b.

The valve of FIG. 4 operates as follows:

The knob 114 is turned in clockwise direction until the projection abuts the pin 115a at which time the valve plate 112a isso located with reference to the orifice 107 as to offer the largest selectable effective cross-section for the flow of fluid therethrough. The cap 127 is now removed and a tool, such as a screwdriver, is inserted into engagement with the slot 112d whereupon the valve member 112 is turned until the valve plate 112a is so located with reference to the orifice 107 that the amount of fluid passing through the orifice 107 via the passage portion 106 to the motor M will cause the same to deliver the amount of torque that is desired for the particular selected application, for example tightening of nuts on the wheels of passenger vehicles. During this adjustment the member 126 is prevented from turning by engaging an appropriate tool into the slot 126b. Subsequently, the cap 127 is put back in place and a user is now no longer able to adjust the valve except to the predetermined increments that can be selected by bringing different ones of the depressions 134 into snap-in registry with the pin 136. However, such adjustments are possible only for smaller and smaller torque values, not for any greater torque values.

If, however, maximum torque is to be delivered by the motor M for tightening of a nut, bolt or other threaded element, then the user exerts a left-hand pressure (in FIG. 4) upon the cap 127, shifting the same and thereby the

elements

126 and 112 towards the left, which causes the valve plate 112a to completely move out of the orifice 107, so that the flow of fluid from the passage portion 108 to the passage portion 106 and from there to the motor M is completely unthrottled and the motor M can develop full torque. When this pressure is subsequently aggain released,

members

126 and 112, and hence the valve plate 112a, will automatically turn to their original position as shown in FIG. 4 under the influence of the pressure exerted by the fluid present in the passage portion 106, so that without any further manipulations and without any need for giving thought to the resetting, the valve returns to the preselected setting. The embodiment of FIG. 4 has the advantage, without respect to that in FIG. 3, that the user has neither immediate access to, nor a view of, the components which must be adjusted to reset the valve, so that the FIG. 4 embodiment is even better protected against accidental misuse than that of FIG. 3.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a pneumatic torqueing tool, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by letters patent is set forth in the appended claims:

1. In a pneumatic torqueing tool, particularly a pneumatic wrench, a combination comprising a housing; a pneumatic motor in said housing and rotatable in a first direction and also in an opposite second direction; fluid conduit means, including a fluid passage for supplying pneumatic fluid to said motor when the same is to rotate in said first direction; and an adjustable throttle valve for controlling the flow of fluid through said passage, said throttle valve comprising a valve member having a valve member portion movable into and out of an orifice in said passage, first means mounting said valve member for gradual adjustment of the axial position of said valve member portion within said orifice to thereby vary the effective cross-section of the latter, and second means for rapidly withdrawing said valve member portion entirely from said orifice to thereby expose the maximum effective cross-section thereof.

2. A combination as defined in claim 1, wherein said throttle valve further comprises a valve body in which said valve member is mounted.

3. A combination as defined in claim 2, wherein said first and second means are guided in said valve body for displacement relative to the same.

4. A combination as defined in claim 2, wherein said first means comprises a nut mounted non-rotatably in said valve body but with freedom of sliding displacement toward and away from'said orifice, and screwthreads formed on said valve member and threaded into said nut to engage the threads thereof with a selfretarding action.

5. A combination as defined in claim 4, wherein said second means comprises a springbiasing said valve member axially of said orifice to a position in which said valve member portion is located'within the orifice, and a stuffing portion for stuffing said valve member and nut counter to the force of said spring to a position in which said valve member portion is entirely withdrawn from said orifice.

6. A combination as defined in claim 2, wherein said first means comprises a tubular valve element formed with internal threads, external threads'formed on said valve member and meshing with said internal threads, and means for turning said valve member relative to said valve element.

7. A combination as defined in claim 6, wherein said second means comprises a bore formed in said valve body wherein said valve element is mounted shiftably in direction axially of said orifice, said valve element having a surface exposed to the pressure of fluid in said passage so as to be urged thereby in one axial direction, and a shifting portion for shifting said valve element and said valve member in direction opposite to said one axial direction counter to the pressure of said fluid and to a position in which said valve member portion is entirely withdrawn from said orifice.

Claims

4. A combination as defined in claim 2, wherein said first means comprises a nut mounted non-rotatably in said valve body but with freedom of sliding displacement toward and away from said orifice, and screw-threads formed on said valve member and threaded into said nut to engage the threads thereof with a self-retarding action.

5. A combination as defined in claim 4, wherein said second means comprises a spring biasing said valve member axially of said orifice to a position in which said valve member portion is located within the orifice, and a stuffing portion for stuffing said valve member and nut counter to the force of said spring to a position in which said valve member portion is entirely withdrawn from said orifice.

6. A combination as defined in claim 2, wherein said first means comprises a tubular valve element formed with internal threads, external threads formed on said valve member and meshing with said internal threads, and means for turning said valve member relative to said valve element.