Continuous fluid-operated wrench

Abstract: A fluid operated wrench has a fluid-operated drive including a cylinder (4) , a piston (5) reciprocatingly movable in the cylinder and having a piston rod (6) with a piston rod end (7), a ratchet mechanism having a ratchet (11) provided with a plurality of teeth, and at least two pawls (9, 10) operatively connectable with the piston rod end (7) and engageable with teeth of the ratchet so that during an advance stroke of the piston (5) one of the at least two pawls engages with at least one ratchet tooth while the other of the at least two ratchets over at least one ratchet tooth, while during a return stroke of the piston the other of the at least two pawls engages with at least one ratchet tooth while the one of the at least two pawls ratchets over at least one ratchet tooth. At least one (9) of the at least two pawls (9, 10) is disengageable from and liftable above the teeth of the ratchet (11) so as to permit the ratchet to turn backwards to release a built up torsion and material flex, so that the fluid operated wrench can be taken off a job.

Description: BACKGROUND OF THE INVENTION The present invention relates to continuous-turning fluid operated wrenches. Continuous turning fluid-operated wrenches are known in the art, for example as disclosed in US-A-4,409,865 and US-A-4,644,829. While the continuous turning fluid operated wrenches have been satisfactory, several new and important improvements had to be made under consideration of the fact that these tools are used for torque in excess of 678 Nm (500 ft.lbs) with the largest one going over 108,480 Nm (80,000 ft.lbs). In addition, the tool has to be improved so as to work in conjunction with the three-piece nut invented by me as disclosed in US-A-5,318,397 as well. The nut includes an inner sleeve, an outer sleeve, and a washer which is,non-rotatably but axially movably connected to the inner sleeve. As the action and reaction forces of this nut are different from the action and reaction forces of a standard nut, it is important to design such a fluid operated wrench which can be used on standard nuts and on the above mentioned new nut. In particular, the tool is to be used on standard nuts where the reaction arm is connected on the same side but outside of the drive that connects with the nut to be turned, as well as with the above described new nut where the reaction drive that connects to the inner sleeve is inside of the drive that connects with the outer sleeve to be turned. In other words, it is expected that a modern continuous rotating fluid-operated wrench should be usable for standard applications with standard nuts as well as applications with my new nut. SUMMARY OF THE INVENTION Accordingly, it is an aim of the present invention to provide a continuous turning fluid operated wrench which can be used on standard nuts as well as on my new nuts including the outer and inner sleeves and the washer. It is also an aim of the present invention to provide a continuous turning hydraulic fluid operated wrench which assures that the pawls engage positively with the corresponding ratchet tooth, without slipping over the ratchet tooth, which breaks off the top of the tooth and causes malfunction. It is also an aim of the present invention to provide a continuous turning fluid operated wrench that can be taken off the nut when the bolt torsion and the flex of the tool parts lock the engaged pawl against the ratchet tooth in their rewinding process, with the use of a disengagement device that lets the tool operator disengage one of the driving pawls so as to allow the ratchet to turn slightly backwards and release the torsion build up and the flex in the tool parts to free the tool from the job. It is also an aim of the present invention to create a continuous cycling and thus a continuous turning of the ratchet without having to switch the valve on the pump from advance to retract strokes manually. Finally, it is also an aim of the present invention to diminish the usual build-in-over stroke when tool operates at low torque. The over-stroke depending on the ratchet mechanism in some cases is 50% or more and is necessary to assure that even under high torque and thus high flex of the driving parts, the ratcheting mechanism does not fail. At low torque the driving parts do not flex so that 50% or more of the stroke is non-productive. The present invention provides a fluid operated wrench as defined in claim 1. Preferred or optional features of the wrench are defined in claims 2 to 9. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a view showing a continuous turning fluid operated wrench which is known in the art; Figures 2A and 2B are a side view and an end view showing the continuous turning fluid operated wrench which is provided with a new inventive mechanism in accordance with one embodiment of the present invention; Figures 3A and 3B are a side view and an end view showing a ratchet mechanism of the inventive continuous turning fluid operated wrench in accordance with another embodiment of the present invention; Figure 4 is a view showing the ratchet mechanism of the inventive continuous fluid operated wrench in accordance with a further embodiment of the present invention; Figure 5 is a view showing the ratchet mechanism of the continuous fluid operated wrench in accordance with still a further embodiment of the present invention; and Figure 6 is a view showing the continuous turning fluid operated wrench of Figure 5 with a fluid pump. DESCRIPTION OF PREFERRED EMBODIMENTS As shown in Figure 1, a continuous turning fluid operated wrench has a housing which is identified with reference numeral 1 and has a first housing part 2 and a second housing part 3. The first housing part 2 accommodates fluid operated drive means which include a cylinder 4 which forms a working chamber, a piston 5 reciprocatingly movable in the cylinder, and a piston rod 6 having a piston rod end 7. The second housing portion 3 accommodates a ratchet mechanism which includes a drive plate 8, two pawls 9 and 10 turnably connected with a drive plate 8, and a ratchet 11 provided with a plurality of teeth engageable by the pawls 9 and 10. During the operation of the continuous turning fluid operated wrench when the fluid is supplied into the cylinder so that the piston 5 moves in one direction, one of the pawls engages with the teeth of the ratchet 11 and turns the ratchet in one direction while the other pawl just ratchets over the teeth. When the fluid is supplied in the cylinder from the opposite side and the piston moves in a reverse stroke, the first pawl ratchets over the teeth of the ratchet while the second pawl engages with the teeth of the ratchet and turns it also in the same direction. This substantially corresponds to the known construction of the continuous turning fluid operated wrenches. In accordance with the present invention, at least one of the pawls 9 and 10 can be easily disengaged and lifted above the teeth of the ratchet 11 so as to permit the ratchet to turn backwards to release a build up torsion and material flex, so that the fluid-operated wrench can be taken off the job. For this purpose, a lever 12 which is spring loaded by a spring 13 is provided as shown in Figure 2A. The lever 12 is pivotably mounted on a slider 14 which has a projection 15 engageable in a groove 16 of the housing portion 3. The housing portion 3 has a slot 17, and a connecting element 18 extends through the slot 17 and connects the slider 14 with a push button 19. As can be seen from the drawings, the pawl 9 has two arms located at opposite sides of a pivot point. During a normal operation of the fluid-operated wrench, the slider is located in a position shown at the left side of Figure 2A and is held in place by the projection 15 engaging in the groove 16 of the housing portion. The spring loaded lever 12 exerts a force on the pawl 9 keeping it in engagement with the teeth of the ratchet 11 until the turning force applied by pawl 9 to its engaged tooth of the ratchet 11 holds it in engagement. If it is necessary to remove the fluid-operated wrench from the job, one of the two pawls 9, 10 has to be released. The release of either pawl 9 or 10 accomplishes the removal of the fluid-operated wrench, regardless of which of the pawls 9, 10 was the last one to turn ratchet 11. It is therefore clear that the same disengagement device as that shown in Figure 2A could also be connected solely to pawl 10. When the disengagement device is meant for disengaging pawl 9 as shown in Figure 2A, pawl 10 is put into engagement with ratchet 11 to apply a turning force to it so as to free pawl 9. Slider 14 is then pushed to the right and held in a position far from the groove 16 of the housing. The spring loaded lever 12 now exerts a force to the arm of the pawl 9 which is located at an opposite side from the pivot point of the pawl, the left arm of the pawl is lifted from the teeth, and the pawl 9 is disengaged from the ratchet. Upon release of the push button 19, the spring loaded lever 12 again reacts against the pawl 9 and pushes the slider 12 back into the starting position in which the projection 15 engages in the groove 16. The disengagement device cannot exert enough force to disengage the pawl 9 or 10 when the ratchet "kicks back" as a result of torsion or when the material flex relaxes. In the embodiment shown in Figures 3A and 3B, the ratchet 11 is provided with pockets 21 at its opposite sides. The pawls 9 and 10 are provided in turn with guiding projections 22. When at least one of the pawls hits at least one ratchet tooth the front portion of the pawl is guided by guiding the projections 22 of the pawl in the pockets 21 of the ratchet, before a rounded end portion of the pawl makes contact with a rounded portion of a gap between the teeth of the ratchet. In the embodiment shown in Figure 4, the ratchet 11 is located between two parts of the second portion 3 of the housing 1. It is connected with an action drive element 31 by interengaging splines. A reaction drive element 32 has a left end engaging in a polygonal opening of a drive retainer 33 which is held by a clip 34 and is non rotatably connected with the housing portion 3 by interengaging splines. During the operation of the fluid operated wrench the action drive element 31 engages, with its castellations 35, one part of a fastener, for example an outer sleeve of my three-piece nut, while the reaction element 32 engages another part of the three-piece nut, for example a washer or an inner sleeve. In this construction the ratchet has an inside diameter which is substantially larger than the diameter that is actually needed for the drive member to withstand the torque output of the continuous turning fluid operated wrench, so that when the tool is used in conjunction with a mechanical tensioning nut, the reaction drive 32 can go through the centre of the action drive 31 which turns the nut. In the embodiment shown in Figure 5 each pawl 9 and 10 is provided with a sensor 41 and 42 at its free end engageable with the teeth of the ratchet 11. A switching unit 43 is provided in the fluid operated tool and cooperates with the sensor 41 and 42. In particular, when the sensor 41 of the front pawl 9 meets a ratchet tooth, a signal is sent to the switching unit 43, the switching unit acts on a valve which reverses a fluid flow from one side of the piston to the other side of the piston, and the direction of movement of the piston changes to an opposite one. Similarly, when the pawl 10 meets a ratchet tooth, the sensor 42 sends a signal to the switching unit 43, and the switching unit 43 again acts on a valve to reverse the movement of the piston to the opposite direction. The connection between the sensors and the switching unit, and the sensors and the valve is wireless. In particular, the sensors can be formed as remote transmitters while the switching means can include remote receivers. Also, the switching means can be provided with a remote transmitter while the valve is provided with a remote receiver. Figure 6 shows schematically the inventive continuous fluid operated wrench W and a fluid operated pump P which supplies the fluid to the wrench W, through a valve V. 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 continuous fluid-operated wrench, it is not intended to be limited to the details shown, since modifications and structural changes may be made without departing in any way from the scope of the appended claims.

Claims: A fluid operated wrench, comprising fluid-operated drive means including a cylinder (4), a piston (5) reciprocatingly movable in said cylinder (4) and having a piston rod (6) with a piston rod end (7); a ratchet mechanism having a ratchet (11) provided with a plurality of teeth, and at least two pawls (9, 10) operatively connectable with said piston rod end (7) and engageable with teeth of said ratchet (11) so that during an advance stroke of said piston (5) one of said at least two pawls (9, 10) engages with at least one ratchet tooth while the other of said at least two pawls (9, 10) ratchets over at least one ratchet tooth, while during a return stroke of said piston (5) the other of said at least two pawls (9, 10) engages with at least one ratchet tooth while said one of said at least two pawls (9, 10) ratchets over at least one ratchet tooth, characterised in that at least one of said at least two pawls (9, 10) is disengageable from and liftable above said teeth of said ratchet (11) so as to permit said ratchet to turn backwards to release a built up torsion and material flex, so that the fluid operated wrench can be taken off a job. A fluid operated wrench as defined in claim 1, comprising a housing (1) including a first housing portion (2) which accommodates said fluid-operated drive, and a second housing portion (3) which accommodates said ratchet mechanism. A fluid operated wrench as defined in claim 1 or 2, comprising a spring-biased lever (12) urging said at least one pawl (9) into engagement with said ratchet (11); and means (14, 18, 19) for displacement of said lever (12) to a position in which it is no longer urges said at least one pawl (9) so that said at least one pawl (9) is disengageable from said ratchet (11). A fluid operated wrench as defined in claim 3, wherein said displacement means include a slider (14) connected with said lever (12). A fluid operated wrench as defined in any preceding claim, wherein each of said at least two pawls (9, 10) is provided at one end with a guide (22) formed so that when said at least one pawl (9, 10) meets a ratchet tooth, a front of each pawl (9, 10) is guided to the ratchet tooth. A fluid operated wrench as defined in any preceding claim, wherein said ratchet (11) has an inside diameter which is substantially larger than a diameter which is actually needed for a drive member (31) to withstand a torque output of the continuous turning fluid-operated wrench so that when the fluid operated wrench is used in conjunction with a mechanical tensioning nut, a reaction drive (32) can go through a centre of an drive member (31) which turns the nut. A fluid operated wrench as defined in claim 1, wherein each of said at least two pawls (9, 10) is provided with a sensor (41, 42); and further comprising switching means (43) connected with said sensor (41, 42) and operative so that when said switching means (43) receives a signal from said sensor (41) of one (9) of said pawls it reverses a movement of said piston (5) into an opposite direction, and again when said switching means (43) receives a signal from said sensor (42) of the other (10) of said pawls it also reverses the movement of said piston (5) to an opposite direction. A fluid operated wrench as defined in claim 7, comprising wireless means which connect said sensors (41, 42) with said switching means (43) for supplying the signals from said sensors (41, 42) to said switching means (43). A fluid operated wrench as defined in claim 7 or 8, comprising valve means (V) provided in said fluid-operated drive means so as to supply a fluid at opposite sides of said piston (5) and vice versa, in response to said signals received from said sensors (41, 42) of said pawls (9, 10)

Inventors: JUNKERS JOHN K, JUNKERS, JOHN K.
Applicants: JUNKERS JOHN K, JUNKERS, JOHN K.
Application year: 2000
Main classification: B25B21
IPC codes: B25B21, B25B13