EP0202130B1 - Ratchet wrench - Google Patents
Ratchet wrench Download PDFInfo
- Publication number
- EP0202130B1 EP0202130B1 EP86303726A EP86303726A EP0202130B1 EP 0202130 B1 EP0202130 B1 EP 0202130B1 EP 86303726 A EP86303726 A EP 86303726A EP 86303726 A EP86303726 A EP 86303726A EP 0202130 B1 EP0202130 B1 EP 0202130B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- anvil
- hammer
- jaw
- ratchet
- cam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
- B25B21/004—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose of the ratchet type
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
- B25B21/02—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose with means for imparting impact to screwdriver blade or nut socket
Definitions
- This invention pertains to a powered ratchet wrench for tightening or removing threaded parts.
- An impact clutch mechanism connects the ratchet mechanism with a rotary power source.
- Conventional powered ratchet wrenches such as that disclosed in Japanese Utility Model Gazette No. 1976-16,555, have a motor operated by compressed air in the base of the housing. When a throttle lever is pressed, compressed air flows to the motor, and the output shaft of the motor turns a transmission shaft by way of speed reducing gears. Slow speed and high torque are transmitted to the transmission shaft.
- the eccentric rotation of a crankshaft at the front end of the transmission shaft oscillates a ratchet yoke.
- the movement of the ratchet yoke causes the ratchet spindle or tool head of a ratchet mechanism to rotate so that a bolt, nut, or other threaded part is tightened or removed.
- the gear drive continues to transmit motor torque directly to the operator even after the fastener has been tightened to a specified tightening torque. That is, if the throttle lever is held open after the fastener has been firmly tightened, compressed air continues to drive the motor and the gears, which in turn drive the transmission shaft and ratchet mechanism.
- a considerable reaction force is transmitted to the operator as the tool tries to rotate around the tightened, stationary fastener.
- the operator's hand can be jerked forward by the wrench, or the operator may lose his grip.
- the tightening force applied by these prior art tools can therefore be inconsistent.
- conventional powered ratchet wrenches are unsuitable for use in tight places where there is room for only one hand. Because the ratchet wrench cannot be gripped tightly in such cramped places, and since it is difficult to release the throttle lever at exactly the right time, the hand is often jerked or loses its grip. The operator's hand can be forcefully thrown against an obstruction and injured, or the ratchet wrench can forcefully strike a projecting part and be damaged.
- a hend-held powered ratchet wrench comprising a rotary motor having a rotatable output shaft drivingly associated with an eccentric crank which is rotatable eccentrically to oscillate a ratchet yoke and operate a ratchet mechanism for rotating a ratchet spindle or tool head about an axis normal to the output shaft, ratchet reverse means being provided to determine the direction of rotation of the ratchet spindle or tool head resulting from the oscillation of the ratchet yoke, wherein the connection between the motor and the ratchet mechanism includes an impact clutch mechanism rotated by the output shaft and driving a rotatable anvil having an axially extending cam surface with a gradually rising portion and a sharply falling portion, the anvil being connected to the crank continuously to rotate the anvil and rotate the ratchet spindle or tool head when the ratchet spindle or tool head encounters a resistance to rotation below a sufficient resistance and axially
- This invention provides a powered ratchet wrench such that, when used to tighten or remove a part or fastener, an impact clutch mechanism provides the connection between the tool motor and the ratchet mechanism.
- an impact clutch mechanism provides an initial direct connection between the motor and the ratchet mechanism to set or snug-up the fastener during "run down”.
- the ratchet mechanism is thereafter rotated by a series of rotational impacts delivered by the impact clutch.
- the impacts break the fastener loose, while the direct drive "runs up” the fastener. If the throttle lever is not released when fastener tightening is completed, only minimal torque reaction force is transmitted to the operator due to the impact clutch.
- the tool can perform consistent tightening quickly and reliably, without manual assistance.
- the ratchet wrench according to this invention is constructed so that the motor and ratchet mechanism are connected with an impact clutch rather than a speed reducing gear device, as in the conventional wrench.
- the impact clutch allows the ratchet mechanism to rotate either under direct motor power or by rotational impacts. An impact can be produced rapidly and extremely smooth during each motor rotation, so that the threaded part can be firmly tightened by the ratchet.
- the connection between the motor and the ratchet is intermittently broken, so that the ratchet is rotating with minimum reaction to the operator.
- This wrench is also suitable for use in tight places with room for only one hand on the tool. The hand won't be thrown against the work piece and injured, as could happen previously. Also, the danger of the ratchet wrench striking an obstruction and being damaged is avoided.
- FIG. 1 shows a longitudinal cross section through a preferred embodiment of the ratchet wrench.
- the ratchet wrench 10 is constructed of several components which will first be described generally.
- Athrottle lever 20 controls the airflowto a rotary air motor 30.
- the rotary output of the motor is transmitted to the hammer assembly 40 of an impact clutch mechanism.
- a spring 50 biases an anvil shaft 60 into association with the hammer assembly 40.
- the anvil shaft can be directly driven by the motorthrough the hammer assembly or can be driven intermittently by a series of rotational impacts from the hammer assembly.
- the rotation of a crank on the anvil shaft causes the reversible ratchet mechanism 70 to rotate in the desired direction, thus tightening or removing a threaded part or fastener. Only a small reaction force is transmitted by the tool to the operator once the fastener is tight.
- the tool 10 includes a motor housing 11 and a ratchet housing 12, secured together in fixed relation such as by a threaded coupling ring 13 and coupling nuts 14.
- a throttle lever 20 opens and closes a throttle valve 22.
- throttle valve 22 When throttle valve 22 is in the open position, compressed air enters the tool at air inlet 24 which is connected to a suitable compressed air source. The compressed air flows into the rotary air motor 30 and transfers its energy to the rotor. The spent air is exhausted from exhaust 26.
- the rotary motor 30 is located in the motor housing 11.
- an air motor is shown, but any rotary power source such as a hydraulic or electric motor could also be used.
- Air motor 30 has a rotor 34 and an extending output shaft 31.
- the two ends of rotor 34 are supported by bearings 33 which in turn are supported by end plates 32.
- the rotor is mounted for rotation in the cylinder 35, the open ends of which are covered by the end plates 32.
- the cylinder has an eccentric bore, as is typical of conventional air motors.
- a plurality of vanes 36 are slidably mounted in radial slots in the rotor. The vanes slide radially back and forth in the slots as the rotor turns due to centrifugal force and the eccentric inner surface of cylinder 35. As the inlet air pushes against vanes 36, it causes rotor 34 to rotate, thus causing output shaft 31 to rotate therewith.
- Numeral 41 designates the hammer cage. It is cup shaped, having a cylindrical wall portion and a base portion which together form an inner surface designated by numeral 44. Within the hammer cage on the inner surface 44 are two diametrically opposed axial grooves. The axial grooves extend only part way down the cylindrical wall portion, forming semi-circular shoulders at a specified distance above the base portion.
- the hammer cage 41 in this preferred embodiment is directly driven by the output shaft 31, as for example by a splined connection. Alternatively, however, the hammer cage could be gear driven.
- a circular raceway 47 Formed in the base portion of the hammer cage is a circular raceway 47, which is concentric about the axis of rotation. Coinciding with the raceway, but extending for only a limited number of degrees, is a larger-dimensioned cam ball pocket 46.
- the cam ball pocket typically describes an arc in the range of 45 to 180 degrees.
- a cam ball 43 is held in the pocket and rolls freely through the arc.
- the anvil shaft 60 carries an axially extending cam 62.
- the cam 62 is a one-sided cam and projects axially from the end of the anvil shaft.
- the cam forms a cam peak with one gradually rising inclined surface adjacent the cam peak and one sharply falling surface adjacent the other side of the peak.
- the inclined surface occupies about a 90 degree arc on the anvil shaft. The sharp surface facilitates escape of the cam.
- the cam 62 and the raceway 47 are dimensioned so that when the hammer cage rotates with the cam extending into the raceway, the hammer cage rotates freely without interference from the cam. In other words, as the raceway rotates relative to the cam, the raceway permits the cam to extend into it without interference.
- the anvil shaft carries at least one, and preferably two anvil jaws 63.
- the anvil jaws and diametrically opposed and radially extending.
- the outer radial surfaces of the anvil jaws are dimensioned so thatthe inner chamber 44 of the hammer cage can rotate freely about the anvil jaws.
- the anvil shaft also carries an eccentric crank 61 at the shaft end opposite the cam 62.
- the anvil shaft 60 is supported by needle bearing 54 so that it slides freely in the axial direction as well as freely rotates.
- the anvil shaft is also journaled for rotation and axial movement by a bore in hammer cage top 42.
- Numeral 50 designates a helical coil biasing spring of a size to fit around a reduced diameter portion of the anvil shaft 60 and abut against a shoulder on the shaft. This biasing spring normally urges the anvil shaft 60 toward the base portion of the hammer cage 41, such that the extending cam 62 normally projects into the raceway 47.
- At least one, and preferably two hammer jaws 45 are received in the axial grooves of the hammer cage 41.
- the hammer jaws are harden pins and when in place are half embedded in the cylindrical wall portion and half exposed in the inner chamber 44.
- the hammer jaws rest on the shoulders of the axial grooves so as not to extend to the base portion of the hammer cage.
- An uninterrupted cylindrical surface is provided belowthe shoulders at the base of the inner chamber 44. This surface allows the hammer cage 41 to rotate relative to the anvil jaws 63 when the biasing spring urges the anvil shaft toward the base portion of the hammer cage without impacting on the anvil jaws.
- the hammer cage top 42 has a short, snug- fitting, reduced diameter portion that is inserted into the inner chamber 44 of the hammer cage.
- the cage top also has two diametrically opposite pilot bores that axially align with the axial grooves of the hammer cage.
- the hammer jaws 45 are also received into these pilot bores to fix the hammer jaws in an axial position and to lock the hammer cage and hammer cage top together against relative rotation.
- Figure 1 illustrates the ratchet wrench in a position when the biasing spring 50 is extended and the cam 62 is positioned in the raceway 47.
- the anvil jaws 63 are biased by the spring toward the base of the hammer cage such that during rotation of the hammer cage, the hammer jaws 45 do not intercept the anvil jaws 63.
- the uninterrupted cylindrical portion of the hammer cage 41 that portion located below the hammer jaws, rotates radially adjacent to the anvil jaws.
- Eccentric crank 61 is positioned at the end of the anvil shaft 60 opposite the cam 62.
- the crank slides axially in the bore of a drive bushing 52 so as to allow for the axial movement of the anvil shaft.
- the ratchet reverse knob 74 By turning the ratchet reverse knob 74 to the appropriate setting, the direction of rotation of the ratchet spindle can be determined.
- the tool can be operated to tighten or remove a fastener by setting the ratchet reverse knob 74.
- the ratchet mechanism is first simply directly driven by the motor through the impact clutch to rotate or "run down" the fastener to a snug position.
- impacts are applied by the impact clutch mechanism to further rotate the ratchet mechanism and further torque the fastener.
- FIG. 1 illustrates the "run down" position of the tool.
- the anvil shaft 60 is in its normal axial position, that is biased toward the base portion of the hammer cage with the one-sided cam 62 extending into the raceway 47.
- the cam ball 43 is contained in the limited arc cam ball pocket 46.
- output shaft 31 causes hammer cage 41 to rotate with it due to the splined connection.
- the trailing shoulder of the rotating cam ball pocket engages and drives the cam ball in the direction of rotation directly of the hammer cage.
- the cam ball next engages but does not roll up the inclined surface of the one-sided cam 62.
- the rotating cam ball imparts rotation to the anvil shaft 60.
- the gradual inclined surface of the cam 62 begins to ride up on the cam ball 43 due to the continued rotation of the cam ball with the hammer cage.
- the anvil shaft and the attached anvil jaws 63 are moved axially forward away from the base portion of the hammer cage.
- the cam ball cooperates with the cam to move the cam and attached anvil shaft axially forward as the cam rides up on the cam ball as it revolves within the cam ball pocket and rotates with the ham mer cage.
- This impact drives the anvil shaft 60 in the direction of rotation of the hammer cage until sufficient resistance is met.
- This resistance is the resistance the fastener encounters as it tightens and is transferred from the fastener through the ratchet mechanism to the anvil shaft 60.
- the anvil shaft stops rotating and the hammer jaws and anvil jaws will begin to disengage.
- the force in the compressed biasing spring 50 overcomes the axial momentum of the anvil shaft and begins to push the cam back towards the hammer cage base as the cam peak moves toward the base, the steep escape surface adjacent the cam peak kicks the cam ball in the direction of the leading edge of the cam ball pocket. The cam peak then again enters the raceway 47.
- the cam 62 once again encounters the cam ball 43.
- the cam ball rotates in the cam ball pocket with the cam until the ball reaches the trailing edge of the pocket. If there still is sufficient resistance due to fastener tension, the cam ball will again force the cam to ride up on the cam ball and the impact sequence will be repeated until the fastener can not be further tightened.
- the cam ball thus times the impacts.
- the impact clutch mechanism will continue to cause the hammer to impact on the anvil.
- the ratchet mechanism will not provide any more tightening torque to the fastener. However, the tool operator will not experience any torque reaction due to the tool turning on the tightened fastener. Rather the operator will experience only the minimal reactions due to the impact clutch.
- anvil shaft 60 can be constructed of two pieces to facilitate the manufacture and assembly of the tool.
- a separate cam portion having the cam peak and anvil jaws can be positioned inside the inner chamber 44 of the hammer cage and splined to a shaft portion extending through the bore of the hammer cage top.
- biasing spring 50 can be positioned anywhere along the shaft portion of the anvil shaft 60.
- the biasing spring can be positioned on the splined connection between the cam portion and the shaft portion.
- the purpose of the impact clutch mechanism is to translate rotary motion to interrupted rotary motion having less torque reaction.
- the impact clutch mechanism described in connection with the preferred embodiment can be broadly categorized as a unique embodiment of a cam engage, spring disengage impact clutch. Other embodiments of the cam engage, spring disengage type impact clutch are also considered to be within the scope of this invention.
- the anvil shaft moves axially.
- An alternate embodiment can provide for the hammer jaws to move axially rather than the anvil shaft.
- One advantage of this invention over the prior art includes minimizing the torque reaction to the tool operator when a fastener is tight and the tool continues to run. This allows the tool to be safely operated with one hand and also in confined and awkward situations. The tool will also produce a consistent tightening torque. The operator will not have to stop the tool before the fastener is tight and manually tighten the fastener out of concern for his own safety and well-being. Additionally, the tool allows a faster "run-down" of the fasteners than prior art powered ratchets.
Description
- This invention pertains to a powered ratchet wrench for tightening or removing threaded parts. An impact clutch mechanism connects the ratchet mechanism with a rotary power source.
- Conventional powered ratchet wrenches, such as that disclosed in Japanese Utility Model Gazette No. 1976-16,555, have a motor operated by compressed air in the base of the housing. When a throttle lever is pressed, compressed air flows to the motor, and the output shaft of the motor turns a transmission shaft by way of speed reducing gears. Slow speed and high torque are transmitted to the transmission shaft. The eccentric rotation of a crankshaft at the front end of the transmission shaft oscillates a ratchet yoke. The movement of the ratchet yoke causes the ratchet spindle or tool head of a ratchet mechanism to rotate so that a bolt, nut, or other threaded part is tightened or removed.
- Thus, in a conventional ratchet wrench, the gear drive continues to transmit motor torque directly to the operator even after the fastener has been tightened to a specified tightening torque. That is, if the throttle lever is held open after the fastener has been firmly tightened, compressed air continues to drive the motor and the gears, which in turn drive the transmission shaft and ratchet mechanism. Thus, a considerable reaction force is transmitted to the operator as the tool tries to rotate around the tightened, stationary fastener. The operator's hand can be jerked forward by the wrench, or the operator may lose his grip. Even if the operator quickly releases the lever as soon as tightening is finished, a reaction force is still transmitted to the hand. It is difficult to prevent the hand from being pulled along or from losing its grip. Hence, the operator usually releases the lever before tightening is finished. The operator then turns the tool manually to finish tightening. The tightening force applied by these prior art tools can therefore be inconsistent.
- In some situations, conventional powered ratchet wrenches are unsuitable for use in tight places where there is room for only one hand. Because the ratchet wrench cannot be gripped tightly in such cramped places, and since it is difficult to release the throttle lever at exactly the right time, the hand is often jerked or loses its grip. The operator's hand can be forcefully thrown against an obstruction and injured, or the ratchet wrench can forcefully strike a projecting part and be damaged.
- There is therefore a need for a powered ratchet wrench which minimizes the motor torque reaction force transmitted to the operator. It is desirable to provide a powered ratchet wrench which minimizes the torque reaction force transmitted to the operator's hand so that the hand is not pulled along with the tool while the motor is still operating and torque is still acting on the fastener.
- According to the present invention there is provide a hend-held powered ratchet wrench comprising a rotary motor having a rotatable output shaft drivingly associated with an eccentric crank which is rotatable eccentrically to oscillate a ratchet yoke and operate a ratchet mechanism for rotating a ratchet spindle or tool head about an axis normal to the output shaft, ratchet reverse means being provided to determine the direction of rotation of the ratchet spindle or tool head resulting from the oscillation of the ratchet yoke, wherein the connection between the motor and the ratchet mechanism includes an impact clutch mechanism rotated by the output shaft and driving a rotatable anvil having an axially extending cam surface with a gradually rising portion and a sharply falling portion, the anvil being connected to the crank continuously to rotate the anvil and rotate the ratchet spindle or tool head when the ratchet spindle or tool head encounters a resistance to rotation below a sufficient resistance and axially to displace the anvil relative to hammer jaws when said resistance to rotation is above said sufficient resistance to cause the hammer jaws to deliver impacts to the anvil.
- This invention provides a powered ratchet wrench such that, when used to tighten or remove a part or fastener, an impact clutch mechanism provides the connection between the tool motor and the ratchet mechanism. To tighten a fastener, the impact clutch mechanism provides an initial direct connection between the motor and the ratchet mechanism to set or snug-up the fastener during "run down". The ratchet mechanism is thereafter rotated by a series of rotational impacts delivered by the impact clutch. To remove a fastener, the impacts break the fastener loose, while the direct drive "runs up" the fastener. If the throttle lever is not released when fastener tightening is completed, only minimal torque reaction force is transmitted to the operator due to the impact clutch. Thus, the tool can perform consistent tightening quickly and reliably, without manual assistance.
- More particularly, the ratchet wrench according to this invention is constructed so that the motor and ratchet mechanism are connected with an impact clutch rather than a speed reducing gear device, as in the conventional wrench. The impact clutch allows the ratchet mechanism to rotate either under direct motor power or by rotational impacts. An impact can be produced rapidly and extremely smooth during each motor rotation, so that the threaded part can be firmly tightened by the ratchet. Thus, while the ratchet is tightening the part, and after the part is fully tightened, the connection between the motor and the ratchet is intermittently broken, so that the ratchet is rotating with minimum reaction to the operator.
- Thus, if the throttle lever is not released when tightening is completed, only a minimal reaction force is transmitted to the operator. This allows complete tightening to be carried out consistently and reliably.
- This wrench is also suitable for use in tight places with room for only one hand on the tool. The hand won't be thrown against the work piece and injured, as could happen previously. Also, the danger of the ratchet wrench striking an obstruction and being damaged is avoided.
- For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
- Figure 1 shows a longitudinal cross section of a ratchet wrench according to the invention.
- Figure 2 shown a perspective view of the base end of the anvil shaft, and
- Figure 3 shows a cross section along line III-III of Figure 1, showing the hammer cage and cam ball of the impact clutch mechanism.
- Figure 1 shows a longitudinal cross section through a preferred embodiment of the ratchet wrench. The
ratchet wrench 10 is constructed of several components which will first be described generally. Athrottlelever 20 controls the airflowto arotary air motor 30. The rotary output of the motor is transmitted to thehammer assembly 40 of an impact clutch mechanism. Aspring 50 biases ananvil shaft 60 into association with thehammer assembly 40. The anvil shaft can be directly driven by the motorthrough the hammer assembly or can be driven intermittently by a series of rotational impacts from the hammer assembly. The rotation of a crank on the anvil shaft causes thereversible ratchet mechanism 70 to rotate in the desired direction, thus tightening or removing a threaded part or fastener. Only a small reaction force is transmitted by the tool to the operator once the fastener is tight. - More specifically the
tool 10 includes a motor housing 11 and aratchet housing 12, secured together in fixed relation such as by a threadedcoupling ring 13 andcoupling nuts 14. - A
throttle lever 20 opens and closes athrottle valve 22. Whenthrottle valve 22 is in the open position, compressed air enters the tool atair inlet 24 which is connected to a suitable compressed air source. The compressed air flows into therotary air motor 30 and transfers its energy to the rotor. The spent air is exhausted fromexhaust 26. - The
rotary motor 30 is located in the motor housing 11. In the preferred embodiment, an air motor is shown, but any rotary power source such as a hydraulic or electric motor could also be used. -
Air motor 30 has arotor 34 and an extendingoutput shaft 31. The two ends ofrotor 34 are supported bybearings 33 which in turn are supported byend plates 32. The rotor is mounted for rotation in thecylinder 35, the open ends of which are covered by theend plates 32. The cylinder has an eccentric bore, as is typical of conventional air motors. A plurality ofvanes 36 are slidably mounted in radial slots in the rotor. The vanes slide radially back and forth in the slots as the rotor turns due to centrifugal force and the eccentric inner surface ofcylinder 35. As the inlet air pushes againstvanes 36, it causesrotor 34 to rotate, thus causingoutput shaft 31 to rotate therewith. -
Numeral 41 designates the hammer cage. It is cup shaped, having a cylindrical wall portion and a base portion which together form an inner surface designated bynumeral 44. Within the hammer cage on theinner surface 44 are two diametrically opposed axial grooves. The axial grooves extend only part way down the cylindrical wall portion, forming semi-circular shoulders at a specified distance above the base portion. Thehammer cage 41 in this preferred embodiment is directly driven by theoutput shaft 31, as for example by a splined connection. Alternatively, however, the hammer cage could be gear driven. - Formed in the base portion of the hammer cage is a circular raceway 47, which is concentric about the axis of rotation. Coinciding with the raceway, but extending for only a limited number of degrees, is a larger-dimensioned
cam ball pocket 46. The cam ball pocket typically describes an arc in the range of 45 to 180 degrees. Acam ball 43 is held in the pocket and rolls freely through the arc. - The
anvil shaft 60 carries anaxially extending cam 62. Thecam 62 is a one-sided cam and projects axially from the end of the anvil shaft. The cam forms a cam peak with one gradually rising inclined surface adjacent the cam peak and one sharply falling surface adjacent the other side of the peak. The inclined surface occupies about a 90 degree arc on the anvil shaft. The sharp surface facilitates escape of the cam. Thecam 62 and the raceway 47 are dimensioned so that when the hammer cage rotates with the cam extending into the raceway, the hammer cage rotates freely without interference from the cam. In other words, as the raceway rotates relative to the cam, the raceway permits the cam to extend into it without interference. - The anvil shaft carries at least one, and preferably two
anvil jaws 63. The anvil jaws and diametrically opposed and radially extending. The outer radial surfaces of the anvil jaws are dimensioned so thattheinner chamber 44 of the hammer cage can rotate freely about the anvil jaws. - The anvil shaft also carries an eccentric crank 61 at the shaft end opposite the
cam 62. Theanvil shaft 60 is supported byneedle bearing 54 so that it slides freely in the axial direction as well as freely rotates. The anvil shaft is also journaled for rotation and axial movement by a bore in hammer cage top 42. -
Numeral 50 designates a helical coil biasing spring of a size to fit around a reduced diameter portion of theanvil shaft 60 and abut against a shoulder on the shaft. This biasing spring normally urges theanvil shaft 60 toward the base portion of thehammer cage 41, such that the extendingcam 62 normally projects into the raceway 47. - At least one, and preferably two
hammer jaws 45 are received in the axial grooves of thehammer cage 41. The hammer jaws are harden pins and when in place are half embedded in the cylindrical wall portion and half exposed in theinner chamber 44. The hammer jaws rest on the shoulders of the axial grooves so as not to extend to the base portion of the hammer cage. An uninterrupted cylindrical surface is provided belowthe shoulders at the base of theinner chamber 44. This surface allows thehammer cage 41 to rotate relative to theanvil jaws 63 when the biasing spring urges the anvil shaft toward the base portion of the hammer cage without impacting on the anvil jaws. - The hammer cage top 42 has a short, snug- fitting, reduced diameter portion that is inserted into the
inner chamber 44 of the hammer cage. The cage top also has two diametrically opposite pilot bores that axially align with the axial grooves of the hammer cage. Thehammer jaws 45 are also received into these pilot bores to fix the hammer jaws in an axial position and to lock the hammer cage and hammer cage top together against relative rotation. - Figure 1 illustrates the ratchet wrench in a position when the biasing
spring 50 is extended and thecam 62 is positioned in the raceway 47. Theanvil jaws 63 are biased by the spring toward the base of the hammer cage such that during rotation of the hammer cage, thehammer jaws 45 do not intercept theanvil jaws 63. The uninterrupted cylindrical portion of thehammer cage 41, that portion located below the hammer jaws, rotates radially adjacent to the anvil jaws. - When the
anvil jaws 63 move axially forward, due to thecam 62 riding up oncam ball 43 and compressing the biasingspring 50, the orbit of therotating hammer jaws 45 intercepts the new position of the anvil jaws. When thecam 62 moves the anvil shaft axially forward during each rotation of the hammer cage, thehammer jaws 45 produce a series of rotational impact against theanvil jaws 63. - Eccentric crank 61 is positioned at the end of the
anvil shaft 60 opposite thecam 62. The crank slides axially in the bore of adrive bushing 52 so as to allow for the axial movement of the anvil shaft. - Drive bushing 52 slides vertically in a
bushing pocket 72 ofratchet yoke 71 so as to accommodate the up and down movement of thecrank 61 as it rotates. The remaining oscillating movement of the ratchet yoke is transferred to theratchet mechanism 70. The ratchet mechanism rotates a ratchet spindle ortool head 73 in a conventional manner as is well known in the prior art. - By turning the ratchet
reverse knob 74 to the appropriate setting, the direction of rotation of the ratchet spindle can be determined. The tool can be operated to tighten or remove a fastener by setting the ratchetreverse knob 74. - To set a threaded fastener, the ratchet mechanism is first simply directly driven by the motor through the impact clutch to rotate or "run down" the fastener to a snug position. Next, to fully tighten the fastener, impacts are applied by the impact clutch mechanism to further rotate the ratchet mechanism and further torque the fastener.
- Figure 1 illustrates the "run down" position of the tool. The
anvil shaft 60 is in its normal axial position, that is biased toward the base portion of the hammer cage with the one-sided cam 62 extending into the raceway 47. Thecam ball 43 is contained in the limited arccam ball pocket 46. When the air motor rotates,output shaft 31 causes hammercage 41 to rotate with it due to the splined connection. The trailing shoulder of the rotating cam ball pocket engages and drives the cam ball in the direction of rotation directly of the hammer cage. The cam ball next engages but does not roll up the inclined surface of the one-sided cam 62. The rotating cam ball imparts rotation to theanvil shaft 60. The rotation of thecrank 61 at the end of the anvil shaft causes the ratchet mechanism to "run down" the fastener. Until the ratchet mechanism and theanvil shaft 60 encounter sufficient resistance from the fastener as it becomes snug, the motor is directly driving the ratchet mechanism through the cam ball of the impact clutch mechanism. - When the ratchet mechanism and the
anvil shaft 60 encounter sufficient resistance, the gradual inclined surface of thecam 62 begins to ride up on thecam ball 43 due to the continued rotation of the cam ball with the hammer cage. The anvil shaft and the attachedanvil jaws 63 are moved axially forward away from the base portion of the hammer cage. In other words, the cam ball cooperates with the cam to move the cam and attached anvil shaft axially forward as the cam rides up on the cam ball as it revolves within the cam ball pocket and rotates with the ham mer cage. - When the cam peak overrides the top of the cam ball, the cam momentarily maintains its axial momentum and clears the cam ball, which continues to rotate beneath the cam. The cam is momentarily in "free flight" before an impact occurs. There are a few degrees of clearance between the trailing shoulder of the cam ball pocket and the hammer jaws. The
anvil jaws 63 have been moved axially away from the hammer base portion and are now in an axial position which intercepts the orbit of therotating hammer jaws 45. The exposed portions of thehammer jaws 45 intercept the new position of the anvil jaws and an impact is delivered to the anvil jaws. - This impact drives the
anvil shaft 60 in the direction of rotation of the hammer cage until sufficient resistance is met. This resistance is the resistance the fastener encounters as it tightens and is transferred from the fastener through the ratchet mechanism to theanvil shaft 60. When sufficient resistance is met, the anvil shaft stops rotating and the hammer jaws and anvil jaws will begin to disengage. - At that time, the force in the
compressed biasing spring 50 overcomes the axial momentum of the anvil shaft and begins to push the cam back towards the hammer cage base as the cam peak moves toward the base, the steep escape surface adjacent the cam peak kicks the cam ball in the direction of the leading edge of the cam ball pocket. The cam peak then again enters the raceway 47. - As the hammer cage continues to rotate, the
cam 62 once again encounters thecam ball 43. The cam ball rotates in the cam ball pocket with the cam until the ball reaches the trailing edge of the pocket. If there still is sufficient resistance due to fastener tension, the cam ball will again force the cam to ride up on the cam ball and the impact sequence will be repeated until the fastener can not be further tightened. The cam ball thus times the impacts. At ultimate tightening torque, the impact clutch mechanism will continue to cause the hammer to impact on the anvil. The ratchet mechanism will not provide any more tightening torque to the fastener. However, the tool operator will not experience any torque reaction due to the tool turning on the tightened fastener. Rather the operator will experience only the minimal reactions due to the impact clutch. - Other embodiments are considered to be within the scope of this invention. For example,
anvil shaft 60 can be constructed of two pieces to facilitate the manufacture and assembly of the tool. A separate cam portion having the cam peak and anvil jaws can be positioned inside theinner chamber 44 of the hammer cage and splined to a shaft portion extending through the bore of the hammer cage top. Furthermore, biasingspring 50 can be positioned anywhere along the shaft portion of theanvil shaft 60. For example, in the embodiment with a two piece anvil shaft, the biasing spring can be positioned on the splined connection between the cam portion and the shaft portion. - The purpose of the impact clutch mechanism is to translate rotary motion to interrupted rotary motion having less torque reaction. The impact clutch mechanism described in connection with the preferred embodiment can be broadly categorized as a unique embodiment of a cam engage, spring disengage impact clutch. Other embodiments of the cam engage, spring disengage type impact clutch are also considered to be within the scope of this invention. For example, in the preferred embodiment, the anvil shaft moves axially. An alternate embodiment can provide for the hammer jaws to move axially rather than the anvil shaft.
- One advantage of this invention over the prior art includes minimizing the torque reaction to the tool operator when a fastener is tight and the tool continues to run. This allows the tool to be safely operated with one hand and also in confined and awkward situations. The tool will also produce a consistent tightening torque. The operator will not have to stop the tool before the fastener is tight and manually tighten the fastener out of concern for his own safety and well-being. Additionally, the tool allows a faster "run-down" of the fasteners than prior art powered ratchets.
Claims (6)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP103158/85 | 1985-05-15 | ||
JP60103158A JPH0635115B2 (en) | 1985-05-15 | 1985-05-15 | Ratchet wrench hammer structure |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0202130A1 EP0202130A1 (en) | 1986-11-20 |
EP0202130B1 true EP0202130B1 (en) | 1990-10-03 |
Family
ID=14346693
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86303726A Expired EP0202130B1 (en) | 1985-05-15 | 1986-05-15 | Ratchet wrench |
Country Status (5)
Country | Link |
---|---|
US (1) | USRE33711E (en) |
EP (1) | EP0202130B1 (en) |
JP (1) | JPH0635115B2 (en) |
CA (1) | CA1281920C (en) |
DE (1) | DE3674634D1 (en) |
Families Citing this family (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS62246480A (en) * | 1986-04-16 | 1987-10-27 | 信濃空圧工業株式会社 | Clamping device |
US4791836A (en) * | 1987-04-01 | 1988-12-20 | Chicago Pneumatic Tool Company | Ratchet mechanism |
JPS63256373A (en) * | 1987-04-14 | 1988-10-24 | 信濃空圧工業株式会社 | Clamping device |
SE504620C2 (en) * | 1995-04-26 | 1997-03-17 | Atlas Copco Tools Ab | Pneumatic torque pulse tool |
US6105595A (en) | 1997-03-07 | 2000-08-22 | Cooper Technologies Co. | Method, system, and apparatus for automatically preventing or allowing flow of a fluid |
US5890848A (en) * | 1997-08-05 | 1999-04-06 | Cooper Technologies Company | Method and apparatus for simultaneously lubricating a cutting point of a tool and controlling the application rate of the tool to a work piece |
US6082986A (en) | 1998-08-19 | 2000-07-04 | Cooper Technologies | Reversible double-throw air motor |
US6241500B1 (en) | 2000-03-23 | 2001-06-05 | Cooper Brands, Inc. | Double-throw air motor with reverse feature |
US6742609B2 (en) | 2001-05-11 | 2004-06-01 | United Diamond Ltd. | Rotational impact drill assembly |
US6889778B2 (en) * | 2003-01-31 | 2005-05-10 | Ingersoll-Rand Company | Rotary tool |
DE10309012B3 (en) * | 2003-03-01 | 2004-08-12 | Hilti Ag | Control method for hand-held electric hammer drill using microcontroller for repetitive opening and closing of clutch between electric motor and tool chuck |
US7080578B2 (en) * | 2004-09-10 | 2006-07-25 | Sp Air Kabusiki Kaisha Corporation | Hand tool with impact drive and speed reducing mechanism |
US20100064864A1 (en) * | 2008-09-15 | 2010-03-18 | Sp Air Kabushiki Kaisha | Double Hammer Clutch Impact Wrench |
US8261849B2 (en) * | 2008-10-27 | 2012-09-11 | Sp Air Kabushiki Kaisha | Jumbo hammer clutch impact wrench |
US8051746B2 (en) * | 2009-06-30 | 2011-11-08 | Ingersoll Rand Company | Ratchet wrench with collar-actuated reversing mechanism |
WO2012061176A2 (en) | 2010-11-04 | 2012-05-10 | Milwaukee Electric Tool Corporation | Impact tool with adjustable clutch |
TW201338926A (en) * | 2012-03-16 | 2013-10-01 | Basso Ind Corp | Ratchet wrench with switching device |
TWM447817U (en) * | 2012-09-21 | 2013-03-01 | Basso Ind Corp | Pneumatic ratchet wrench having retractable head portion |
US9272400B2 (en) | 2012-12-12 | 2016-03-01 | Ingersoll-Rand Company | Torque-limited impact tool |
US20150165603A1 (en) * | 2013-12-17 | 2015-06-18 | Ming-Ta Cheng | Power device with a unicorn impact unit |
US9737978B2 (en) | 2014-02-14 | 2017-08-22 | Ingersoll-Rand Company | Impact tools with torque-limited swinging weight impact mechanisms |
JP2023025360A (en) * | 2021-08-10 | 2023-02-22 | パナソニックIpマネジメント株式会社 | impact rotary tool |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3174597A (en) | 1961-12-19 | 1965-03-23 | Chicago Pneumatic Tool Co | Impact clutch |
US3212590A (en) * | 1963-07-29 | 1965-10-19 | Reed Roller Bit Co | Impact wrench |
US3414066A (en) * | 1966-08-31 | 1968-12-03 | Chicago Pneumatic Tool Co | Impact wrench |
US3428137A (en) * | 1967-10-12 | 1969-02-18 | Chicago Pneumatic Tool Co | Impact wrench |
JPS5435380Y2 (en) * | 1971-04-13 | 1979-10-27 | ||
JPS5235708B2 (en) * | 1971-09-27 | 1977-09-10 | ||
JPS4918313U (en) * | 1972-05-17 | 1974-02-16 | ||
US4063601A (en) * | 1976-08-23 | 1977-12-20 | Dresser Industries, Inc. | Rotary impact tool |
US4184552A (en) * | 1977-05-17 | 1980-01-22 | Marquette Metal Products Company | Manually actuated impact tool |
US4313505A (en) * | 1979-08-27 | 1982-02-02 | Rodac Pneumatic Tools | Rotary impact clutch |
US4346630A (en) * | 1979-12-17 | 1982-08-31 | Rodac Pneumatic Tools | Ratchet wrench |
US4382476A (en) * | 1981-12-03 | 1983-05-10 | Swenson Oscar J | Manual torque magnifying impact tool |
-
1985
- 1985-05-15 JP JP60103158A patent/JPH0635115B2/en not_active Expired - Lifetime
-
1986
- 1986-05-12 CA CA000508917A patent/CA1281920C/en not_active Expired - Lifetime
- 1986-05-15 DE DE8686303726T patent/DE3674634D1/en not_active Expired - Lifetime
- 1986-05-15 EP EP86303726A patent/EP0202130B1/en not_active Expired
-
1990
- 1990-09-04 US US07/578,363 patent/USRE33711E/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
EP0202130A1 (en) | 1986-11-20 |
JPS61260982A (en) | 1986-11-19 |
JPH0635115B2 (en) | 1994-05-11 |
DE3674634D1 (en) | 1990-11-08 |
USRE33711E (en) | 1991-10-08 |
CA1281920C (en) | 1991-03-26 |
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