Hydraulic Torque Wrench

Abstract

There is provided a hydraulic torque wrench (10) comprising: a housing (12); a drive pawl (1) pivotally mounted within the housing (12); and a piston rod (2) configured to be driven and coupled to the drive pawl (1) for driving the drive pawl (1). A ratchet gear (3) configured to be rotationally driven by the drive pawl (1). A spring (4) configured to bias the drive pawl (1) into engagement with the ratchet gear (3). A travel limiter arranged to limit the rotational travel of the drive pawl (1) out of engagement with the ratchet gear (3). By limiting the travel of the drive pawl (1), the inventors eliminate the risk of the spring (3) becoming overstretched.

Description

[Technical field]

[0001] The present disclosure relates to a hydraulic torque wrench. [Background technology]

[0002] Hydraulic wrenches are known in the prior art, as an example from WO 2018 / 130854. Atlas Copco, as well as other suppliers, offers hydraulic torque wrenches with a removable drive (typically a square drive, but different shapes of drive can be used, e.g. hexagonal or socket drives). One or more drive sleeves may be used to aid in the insertion and / or positioning of the drive. One or more removable retainers may be used to hold the drive.

[0003] Typically, such tools include a ratchet mechanism repeatedly driven by a hydraulic cylinder having a linear drive and a retract stroke. The ratchet mechanism ensures that the drive only rotates in one direction. Typically, the ratchet mechanism will include a ratchet gear having asymmetrical teeth and driven by a drive pawl. The pawl is biased into contact with the ratchet by a biasing means such as a spring. In normal use, the drive pawl drives the ratchet gear in one direction during the drive stroke, but due to the shape of the ratchet gear teeth, the pawl will ride over the teeth when driven in the opposite linear direction on the retract stroke.

[0004] However, the inventors have realized that when a torque wrench is used to loosen a bolt, the bolt may be suddenly released, causing a shock wave through the tool. The sudden release causes the nut, socket, drive and ratchet gear to rotate rapidly. In particular, the inventors have realized that this may cause the drive pawl to disengage from the ratchet gear and be thrown off.

[0005] The inventors have realized that this snapping motion can cause undue stretching and potentially damage to the spring or other biasing means which is essential for the ratchet mechanism to function properly, which can lead to reliability issues and premature part failure.

[0006] A prior art arrangement is shown in FIGS. Summary of the Invention [Means for solving the problem]

[0007] According to a first aspect of the present invention, we have provided a hydraulic torque wrench comprising: Housing; a drive pawl pivotally mounted in the housing; a piston rod coupled to and configured to drive the drive pawl to drive the drive pawl; a ratchet gear configured to be rotationally driven by a drive pawl; a spring configured to bias the drive pawl into engagement with the ratchet gear; and a travel limiter positioned to limit pivotal travel of the drive pawl out of engagement with the ratchet gear; A hydraulic torque wrench comprising:

[0008] So by limiting the travel of the drive pawl, we eliminate the risk of overstretching the spring. In a preferred embodiment, the travel limiter limits the travel of the drive pawl so as to prevent the spring from stretching beyond its elastic limit.

[0009] The travel limiter may comprise a first drive plate, wherein the first drive plate includes a first opening in which a first pin is mounted, and wherein the drive pawl has a first slot that receives the first pin, such that a limit on the pivotal travel of the drive pawl corresponds to movement of the first pin to an end of the first slot.

[0010] The travel limiter may include a second drive plate, wherein the first and second drive plates are disposed on opposite sides of the drive pawl, wherein the second drive plate includes a second opening in which the second pin is mounted, and wherein the drive pawl includes a second slot that receives the second pin, whereby a limit to the pivotal travel of the drive pawl corresponds to movement of the second pin relative to an end of the second slot.

[0011] Typically, the ratchet gear comprises teeth and wherein the drive pawl comprises a protruding arm configured to engage the teeth and an opening configured to allow the drive pawl to be mounted to the shaft, wherein the first slot is located in the drive pawl between the protruding arm and the opening.

[0012] The first and / or second slots may describe a partial circular arc and may have rounded ends.

[0013] The hydraulic torque wrench may include a hydraulic fluid inlet coupled to a piston mounted within the housing.

[0014] Description of embodiments of the present invention will now be given, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 shows a prior art tool arrangement. [Diagram 2] FIG. 2 shows spring damage in a prior art tool arrangement. [Diagram 3] FIG. 3 shows a perspective view of a tool according to an embodiment of the invention. [Figure 4] FIG. 4 shows a drive plate according to an embodiment of the present invention. [Diagram 5] FIG. 5 illustrates a drive pawl according to an embodiment of the present invention. [Figure 6] FIG. 6 illustrates a pawl spring protection mechanism according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Figures 1 and 2 show a prior art tool 10, with Figure 2 showing spring damage, a problem with the arrangement shown. Figure 1 shows two side views of tool 10 cut away so that the internal components of tool 10 are visible. Tool 10 could be, for example, a torque wrench (depending on how tool 10 is configured) used to tighten and / or loosen bolts.

[0017] The tool 10 may include a housing 12 that houses the components of the tool 10. Each figure shows the tool 10 with a piston rod 2, a drive pawl 1, a ratchet gear 3, and a tension spring 4. Collectively, these features may be components of a "drive mechanism." The tension spring 4 may be replaced with other suitable biasing means.

[0018] The piston rod 2 may be configured to be hydraulically driven and the tool assembly 10 may include a power source configured to hydraulically drive the piston rod 2 .

[0019] In the upper side view, the tool 10 is shown during a forward stroke of the piston rod 2, i.e., when the piston rod 2 is driven in a direction towards the driving pawl 1. The piston rod 2 may be configured to couple to the driving pawl 1. The driving pawl 1 may have an opening 1a configured to be mounted on the shaft of the piston rod 2 and couple the two. The driving pawl 1 may be configured to move in response to the movement of the piston rod 2. In the forward stroke shown, the piston rod 2 may transmit motion to the driving pawl 1, which may engage the driving pawl 1 with the ratchet gear 3 to rotate the ratchet gear 3. The ratchet gear 3 is rotatably mounted in the housing 12 and may thereby be rotated by the driving pawl 1; the ratchet gear 3 may have an opening and may be mounted on the shaft via the opening. In the ratchet gear 3 shown, the opening is central.

[0020] The ratchet gear 3 may include teeth 6. The teeth 6 may be uniform but asymmetrical, and each tooth 6 may include a first beveled edge and a second steeply beveled edge, where the sliding portion 9 of the drive pawl 1 is configured to slide over the first beveled edge, and the second steeply beveled edge prevents a portion of the drive pawl 1 from sliding over. Thus, there is a "forward" direction in which the ratchet gear 3 rotates, and the drive pawl 1 is configured to drive the rotation of the ratchet gear 3 in the forward direction. In FIG. 1, the forward direction is indicated by a curved arrow around the circumference of the ratchet gear 3.

[0021] The driving pawl 1 may include a protruding arm 8 configured to engage the ratchet gear 3, for example to engage the teeth 6. The protruding arm 8 may be configured to fit between two adjacent teeth 6. As the driving pawl 1 moves, the slider 9 guides the driving pawl over the teeth 6 until the protruding arm 8 lands in a recess between two adjacent teeth 6.

[0022] The protruding arm 8 may be biased into a recess between two adjacent teeth 6 by a force from a tension coil spring 4. One or more springs 4 may be provided to bias the protruding arm 8 into the recess after it has passed the apex of the tooth 6.

[0023] A lower side view of the tool 10 shows the piston rod 2 being retracted. This movement of the piston rod 2 may be configured to disengage the drive pawl 1 from the ratchet gear 3. This removes the driving force from the drive pawl 1 and may stop rotation of the ratchet gear 3 in the forward direction.

[0024] 1 includes an enlarged view of the drive pawl 1 and shows the tension spring 4. Positive engagement of the drive pawl 1 with the teeth 6 may rely on the spring 4 biasing the drive pawl 1 towards the ratchet gear 3 by returning to a neutral position, which may be expanded as the slider 9 passes over a first sloping side and / or the apex of the tooth 6, returning to neutral, for example, when the protruding arm 8 enters a recess between two adjacent teeth 6.

[0025] A pair of tension coil springs 4 may be provided, each configured to bias the drive pawl 1 towards the ratchet gear 3 and thus the protruding arm 8 into the recess. For example, three or more springs 4 may be provided.

[0026] Under normal operation, the spring 4 may function within acceptable limits.

[0027] 2 shows a tool 10 where the drive pawl 1 has disengaged from the ratchet gear 3. The tension spring 4 has been damaged. The curved arrow indicates that the ratchet gear 3 has been rotated forward but the protruding arm 8 has disengaged not only from the recesses between the teeth 6 but also from the teeth 6 themselves. The drive pawl 1 has been rotated too far out of the ratchet gear 3 causing the spring 4 to become overstretched.

[0028] This may be the result of the tool 10 (which may be a torque wrench) being used to loosen a bolt. The bolt may have suddenly come loose. This may have caused an impact to the tool 10. This sudden release may have caused components of the tool assembly 10, including the ratchet gear 3, to move in an undesired manner by the user. The ratchet gear 3 may have been rotated uncontrollably, meaning that the ratchet gear 3 may have rotated rapidly in a forward direction, causing the drive pawl 1 to be ejected from engagement with the ratchet gear 3.

[0029] As a result, the tension spring 4 may be overstretched beyond its plastic limit, which may result in damage to the spring as shown.

[0030] The tension spring 4 (or spring 4) may be essential for the proper functioning of the ratchet gear 3 and drive pawl 1 mechanisms. Thus, damage to the spring may cause reliability issues and premature failure of the component.

[0031] Figure 3 illustrates a tool 100 according to an embodiment of the present invention. The illustrated tool 100 includes a housing 12 configured to house the components of the tool 100 therein. The tool 100 is a torque wrench, for example a square drive hydraulic wrench. The tool 100 may include product or manufacturer indicia (12a), for example as shown in Figure 3.

[0032] The present tool 100 may include any (or all) of the features described above that are part of the prior art tool 10, and therefore like numbers are used throughout for like features.

[0033] The drive assembly 30 is mounted to the housing 12. The tool 100 may further include a reaction arm 32 and a pivot assembly 34. The reaction arm 32 and the pivot assembly 34 may be of any type known to those of ordinary skill in the art and / or one or both may be absent in other embodiments. For example, the pivot assembly 34 may be replaced with a different form of hose connector to allow the tool 100 to be coupled to a pump (not shown).

[0034] The drive assembly 30 may include a drive 31, which may more specifically be a square drive 31 as in the illustrated embodiment. Different drives 31 may be used in other embodiments. The tool 100 may include a drive retainer 35 configured to prevent the drive 31 from sliding out of the tool 100.

[0035] Tool 100 may also include various other features standard in the art, such as a reaction pawl within tool 100 that provides an anti-backlash mechanism, and optionally, a reaction pawl lever 37 shown in FIG. 3 that can be used to disengage the reaction pawl from ratchet gear 3 if tool 100 becomes locked onto the object on which it is being used to apply torque.

[0036] Tool 100 may include the drive pawl 1, piston rod 2 and ratchet gear 3 described above and all of the attendant features.

[0037] FIG. 4 shows a cross section of the drive pawl 1 of the present tool 100. To prevent overstretching of the spring and subsequent damage, the drive pawl 1 has an opening configured to receive a retaining pin 60 (see FIG. 6). The retaining pin 60 is generally cylindrical with no straight edges. The tool 100 may include a drive plate 40. The drive pawl 1 is disposed between two drive plates 40 and is attached (e.g., via opening 1a) to a shaft 42. The shaft 42 is configured to couple to a piston rod 2, and the two drive plates 40 may be positioned on either side of the coupling to the piston rod 2. Each drive plate 40 has an opening 44 configured to receive a retaining pin 60.

[0038] The driving pawl 1 may include a slot 50. The slot 50 is configured to receive a retaining pin 60. The retaining pin 60 is smaller in size than the slot 50 so that the retaining pin 60 has some freedom of movement within the slot 50. In this manner, the retaining pin 60 in the slot 50 does not impede or inhibit normal movement of the driving pawl 1, which includes allowing the driving pawl 1 to jump over the teeth 6 of the ratchet gear 3 and for the protruding arm 8 to drop into the recess between the teeth 6.

[0039] The slot 50 describes a partial arc coaxial with the shaft 42 having rounded edges to prevent wear of sharp corners during use by the retaining pin 60 disposed therein, as well as damage to the retaining pin 60 that may be caused by sharp corners.

[0040] The slot 50 is arranged, for example, in the drive pawl 1 between the opening 1 a and the projecting arm 8 .

[0041] In tool 100, the same retaining pin 60 may first pass through the first drive plate 40a and then enter the slot 50. In this manner, movement of drive pawl 1 may be limited to the range permitted by the retaining pin 60 in the slot 50, which is limited by its fixation to the first drive plate 40a.

[0042] The drive plate 40 is disposed in the housing 12 and covers at least a portion of the ratchet gear 3 during use. For example, FIG. 6 shows a view of the ratchet gear 3 and the drive plate 40, showing that the first drive plate 40a is semi-transparent and at least partially covers the ratchet gear 3 underneath. To prevent damage to the spring from impact due to excessive disengagement of the drive pawl 1 from the ratchet gear 3, a retaining pin 60 is inserted through an opening 44 located adjacent to but spaced from the area of ​​the first drive plate 40a that covers the ratchet gear 3. If the retaining pin 60 is inserted too close to the ratchet gear 3, the drive pawl 1 may be prevented from disengaging from the ratchet gear 3 to any degree, which is undesirable. FIG. 6 shows a shaded area 600 representing an exemplary range of movement of the drive pawl 1 when the retaining pin 60 is inserted into the first drive plate 40a and the slot 50. The curved arrows in FIG. 6 indicate the directions in which drive pawl 1 is permitted to pivot away from ratchet gear 3 within range 600 .

[0043] A second retaining pin 60 is inserted through the second drive plate 40b into the opening 44. The second drive plate 40b may have all of the features of the first drive plate 40a and is located on the opposite side of the shaft 42 from the first drive plate 40a or adjacent thereto such that the drive pawl 1 is located between the drive plates 40a, 40b. The second retaining pin 60 is inserted substantially parallel to the first retaining pin 60. The first and second drive plates 40a, 40b have openings 44 in substantially the same locations.

[0044] The drive pawl 1 may include a second slot 50 configured to receive a second retaining pin 60. The second slot 50 is configured similarly to the first slot 50 to limit movement of the drive pawl 1 by only allowing movement of the retaining pin 60 within the confines of the slot 50.

[0045] Providing a pin 60 on each of the drive plates 40a, 40b may prevent portions of the drive pawl 1 (those defining the slot 50 and those receiving the retaining pin 60) from wearing out faster than other portions without the slot 50 / pin 60. Each pin 60 may also share the load of the task and therefore need not be as robust as, for example, if only one pin 60 were provided. Additionally, having a pin 60 on both sides of the drive pawl 1 may prevent the drive pawl 1 from potentially twisting based on a single pin 60 acting on only one side in the event of an impact.

[0046] The retaining pins 60 may each have a uniform diameter along their entire length, or may be tapered or otherwise have a variable diameter. For example, the pins 60 may have a mushroom-shaped end or otherwise enlarged portion having a diameter that exceeds the diameter of the openings 44 to prevent the pins 60 from passing completely through the openings 44.

[0047] A cap or other stopper may be added to the pin 60 after it has been routed through the opening 44 and / or slot 50 to prevent the pin 60 from slipping out of the opening 44 and / or slot 50. This may be removable and replaceable.

[0048] The retaining pin 60 may prevent movement of the drive pawl 1 in the presence of a shock load, thus protecting each of the tension springs 4 .

[0049] The first and / or second drive plates 40a, 40b may accordingly include one or more additional openings to receive additional retaining pins 60. If desired, the slot 50 may be configured to receive more than one pin 60, or the drive pawl 1 may include more than one slot 50 to accommodate multiple pins 60. Each slot 50 may be appropriately sized and / or shaped to function together to define a range of motion 600 of the drive pawl 1.

[0050] In use, based on the user's desired position of the retaining pin 60 or the desired range 600 of movement of the drive pawl 1, a single retaining pin 60 can be inserted into a drive plate 40 having multiple openings configured to accept the pins 60.

[0051] In either case, each retaining pin 60 may have any or all of the features described herein of the first retaining pin 60, even if there are multiple pins 60 through one drive plate 40, or even if one or more pins 60 are inserted into each drive plate 40a, 40b.

Claims

1. 1. A hydraulic torque wrench comprising: Housing; a drive pawl pivotally mounted in said housing; a piston rod coupled to and configured to drive the drive pawl for driving the drive pawl; a ratchet gear configured to be rotationally driven by said drive pawl; a spring configured to bias the drive pawl into engagement with the ratchet gear; and a travel limiter positioned to limit pivotal travel of the drive pawl out of engagement with the ratchet gear; A hydraulic torque wrench.

2. 2. The hydraulic torque wrench of claim 1, wherein the travel limiter limits the travel of the drive pawl to prevent the spring from stretching beyond its elastic limit.

3. 3. A hydraulic torque wrench as claimed in claim 1 or 2, wherein the travel limiter comprises a first drive plate, the first drive plate including a first opening in which a first pin is mounted, and the drive pawl comprises a first slot that receives the first pin, whereby the limit on the pivotal travel of the drive pawl corresponds to the movement of the first pin to an end of the first slot.

4. 4. The hydraulic torque wrench of claim 3, wherein the travel limiter comprises a second drive plate, the first and second drive plates being disposed on opposite sides of the drive pawl, the second drive plate comprising a second opening into which a second pin is mounted, and the drive pawl comprising a second slot that receives the second pin, whereby the limit on the pivotal travel of the drive pawl corresponds to the movement of the second pin relative to an end of the second slot.

5. 4. The hydraulic torque wrench of claim 3, wherein the ratchet gear includes teeth and the drive pawl includes a protruding arm configured to engage the teeth and an opening configured to allow the drive pawl to be attached to a shaft, the first slot being located in the drive pawl between the protruding arm and the opening.

6. 4. The hydraulic torque wrench of claim 3, wherein the first and / or second slots describe a partial arc.

7. 3. A hydraulic torque wrench as claimed in claim 1 or 2, comprising a hydraulic fluid inlet connected to a piston mounted within the housing.

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