torque wrench

Abstract

A torque wrench for applying torque to a fastener, a method of calibrating a preload of a biasing element of a torque wrench, and a scale ring for use with a torque wrench. The torque wrench includes a fastener driving structure, a wrench body, a handle foot engagement and stabilizing structure, a stress biasing element, and an adjuster. The adjuster includes an adjustment shaft, a handle insert, a handle, and an adjustment nut. The handle insert has an outer surface shaped to define one or more gears and an inner opening shaped to receive a splined portion of the adjustment shaft, the surface of the inner opening including one or more splines such that rotation of the handle insert will rotate the adjustment shaft. The handle has an interior recess configured to receive the handle insert such that at least one gear of the outer surface of the handle insert is at a 12 o'clock orientation within the handle, and rotation of the handle when the handle insert is disposed in the recess applies a rotational force to the handle insert and subsequently to the adjustment shaft.

Description

Technical Field

[0001] This invention relates to a torque wrench for applying torque to fasteners. More specifically, this invention relates to a torque wrench with a graduated ring capable of providing simultaneous measurement in metric and imperial units. Background Technology

[0002] Torque wrenches are well known in the art. Typically, a torque wrench includes a fastener drive mechanism having a fastener engagement head, such as a ratchet-type head, and an elongated shank member extending from the head. The fastener drive mechanism is inserted into a housing structure. The fastener drive mechanism and the housing structure are pivotally connected by a pivot pin for relative pivoting movement between a normal position and a torque-over-torque position. The shank engagement member is spring-biased to engage with the rear end portion of the shank member to hold the fastener drive mechanism and the housing structure in the normal position during torque application operations. An adjuster is provided to regulate the stress in the spring. During torque application to the fastener, the spring holds the fastener drive mechanism and the housing structure in the normal position until the torsional resistance provided by the fastener reaches a threshold level determined by the spring force. Upon reaching this torsional resistance, the hand force applied to the housing structure causes the housing structure to pivot relative to the fastener drive mechanism, thereby bringing the housing structure into contact with the fastener drive mechanism to produce an audible "click." This "click" indicates to the user that the threshold torque level has been reached.

[0003] One drawback of these types of torque wrenches is that they require calibration to maintain their accuracy after a period of use. Calibration is a complex process that typically involves disassembling the torque wrench, resetting the spring tension, and then reassembling it. When reassembling the torque wrench, certain critical components (such as the handle insert) must be adjusted / aligned, while other components (such as the adjusting shaft) must remain completely still to maintain the new spring return tension. This complex process is generally inefficient and time-consuming. Therefore, there is a need for a torque wrench that includes elements that simplify the calibration process.

[0004] Another drawback of torque wrenches is that the units of measurement are often difficult to read. Typically, a scale is printed on the shaft of the torque wrench body. This scale is usually in units of 10. Another scale, in units of 1, is located around the edge of the adjuster handle. As the handle rotates about the shaft, the edge translates along the scale. The desired setting is measured across the cross-section of both scales. This complex method of determining the measured torque setting is often difficult to read and can lead to errors. Therefore, there is a need for a torque wrench that includes elements that simplify the method of determining the measured torque setting.

[0005] Furthermore, when users need to switch between metric and imperial measurement systems, traditional torque wrenches may have two graduations on the shaft of the wrench body. However, if the metric graduations on the wrench body are in units of 10, then the imperial graduations do not have such regular intervals. This is because 1.0 Nm equals 0.73 ft-pounds. These irregular intervals in the readings are exacerbated by the fact that there is only one graduation around the edge of the adjuster. In our example, this graduation is in metric units (Nm). Therefore, a second unit conversion is necessary to accurately determine the torque wrench setting in imperial units. This complex method of determining the torque setting in an alternative measurement system often leads to errors. Therefore, a torque wrench is needed that includes elements that simplify the method of determining the measured torque setting and allow for accurate switching between metric and imperial units. Summary of the Invention

[0006] In a first aspect, the present invention discloses a torque wrench for applying torque to a fastener, the torque wrench comprising a fastener drive structure having a head configured and arranged to detachably engage with a fastener and a shank structure extending rearward from the head. The torque wrench further comprises a wrench body including a housing structure, the fastener drive structure and the housing structure being pivotally connected for pivoting about a pivot axis (A) from a normal position relative to each other to a torque-over-torque position to generate a torque-over-torque signal. The torque wrench further comprises a shank engagement and stabilizing structure having a tilting block and a pusher, wherein the tilting block includes a front end and a rear end, and wherein when the housing structure is in its normal position, a shank engagement surface engages flush with a rear end portion of the shank, and a pusher engagement surface engages flush with the pusher, and wherein when the housing structure is in its torque-over-torque position, an edge of the tilting block adjacent to the shank engagement surface engages the rear end portion of the shank, and another edge of the tilting block adjacent to the pusher engagement surface engages the pusher. The torque wrench also includes a stress biasing element that applies a biasing force to the foot engagement and stabilizing structure such that, during torque application operation, the force applied to the wrench body (a) is transmitted as torque to a fastener detachably engaged with the head, and (b) tends to pivot the housing structure relative to the fastener drive structure about the pivot axis. The biasing force applied by the biasing element maintains engagement of the foot engagement and stabilizing structure with the rear end portion of the foot structure, thereby keeping the housing structure and the fastener drive structure in their said normal position until the torsional resistance provided by the fastener reaches a threshold level determined by the biasing force of the biasing element. At this point, the force applied to the wrench body pivots the housing structure relative to the fastener drive structure to the torque over-voltage position to generate the torque over-voltage signal, indicating that the torsional resistance provided by the fastener has reached the threshold level. The torque wrench also includes an adjuster configured and arranged such that its rotational movement adjusts the stress in the biasing element, and thereby adjusts the biasing force applied by the biasing element to the shank engagement and stabilizing structure, thereby setting the aforementioned threshold level of the torsional resistance, at which the force applied to the wrench body causes the housing structure to pivot relative to the fastener drive structure as previously described. The torque wrench is characterized in that the adjuster includes an adjusting shaft having a threaded portion, a splined portion, and a pin-retaining portion. The adjuster also includes a handle insert having an outer surface shaped to define one or more gears and an inner opening shaped to receive the splined portion of the adjusting shaft, wherein the surface of the inner opening includes one or more splines configured to engage with the splines of the adjusting shaft such that rotation of the handle insert causes rotation of the adjusting shaft.The adjuster further includes a handle having an internal recess configured to receive the handle insert, wherein the recess is positioned within the handle such that at least one gear on the outer surface of the handle insert is positioned at the 12 o'clock position within the handle, and wherein when the handle insert is positioned in the recess, rotational movement of the handle applies a rotational force to the handle insert and subsequently transmits it to the adjusting shaft. The adjuster also includes an adjusting nut defining an opening with a threaded surface configured to engage with the threaded portion of the adjusting shaft, wherein when a rotational force is applied to the adjusting shaft, the engaging threaded portion causes the adjusting nut to translate, the adjusting nut adjusting the thrust bearing and applying a biasing force to the biasing element.

[0007] This invention discloses a torque wrench for applying torque to a fastener, the torque wrench including a fastener drive structure having a head configured and arranged to detachably engage with a fastener and a shank structure extending rearward from the head. The torque wrench also includes a wrench body comprising a housing structure, wherein the fastener drive structure and the housing structure are pivotally connected for pivoting about a pivot axis (A) from a normal position relative to each other to a torque-over-torque position to generate a torque-over-torque signal. The torque wrench further includes a shank engagement and stabilization structure having a rocker arm and a pusher arm. The rocker arm includes a shank engagement surface and a pusher engagement surface. When the housing structure is in its normal position, the shank engagement surface engages flush with the rear end portion of the shank, and the pusher engagement surface engages flush with the pusher arm. When the housing structure is in its torque-over-torque position, an edge of the rocker arm adjacent to the shank engagement surface engages the rear end portion of the shank, and another edge of the rocker arm adjacent to the pusher engagement surface engages the pusher arm. The torque wrench also includes a stress biasing element that applies a biasing force to the shank engagement and stabilizing structure such that, during torque application operation, the force applied to the wrench body (a) is transmitted as torque to a fastener detachably engaged with the head, and (b) tends to pivot the housing structure relative to the fastener drive structure about the pivot axis. The biasing force applied by the biasing element maintains engagement between the shank engagement portion and the rear end portion of the shank structure, thereby keeping the housing structure and the fastener drive structure in their normal positions until the torsional resistance provided by the fastener reaches a threshold level determined by the biasing force of the biasing element. At this point, the force applied to the wrench body pivots the housing structure relative to the fastener drive structure to the torque-over-torque position to generate the torque-over-torque signal, indicating that the torsional resistance provided by the fastener has reached the threshold level. The torque wrench also includes an adjuster configured and arranged such that its rotational movement adjusts the stress in the biasing element, and thereby adjusts the biasing force applied by the biasing element to the shank engagement and stabilizing structure, thereby setting a threshold level of torsional resistance at which the force applied to the wrench body causes the housing structure to pivot relative to the fastener drive structure as previously described. The torque wrench is characterized in that the adjuster includes an adjusting shaft having a threaded portion, a splined portion, and a pin-retaining portion. The adjuster also includes a handle insert having an outer surface shaped to define one or more gears and an inner opening shaped to receive the splined portion of the adjusting shaft, wherein the surface of the inner opening includes one or more splines configured to engage with the splines of the adjusting shaft such that rotation of the handle insert causes rotation of the adjusting shaft.The adjuster further includes a handle having an internal recess configured to receive the handle insert, wherein the recess is positioned within the handle such that at least one gear on the outer surface of the handle insert is positioned at the 12 o'clock position within the handle, and wherein when the handle insert is disposed in the recess, rotational movement of the handle applies a rotational force to the handle insert and subsequently transmits it to the adjusting shaft. The adjuster also includes an adjusting nut defining an opening with a threaded surface configured to engage with the threaded portion of the adjusting shaft, wherein when a rotational force is applied to the adjusting shaft, the engaging threaded portion causes the adjusting nut to translate, the adjusting nut adjusting the biasing force of the biasing element.

[0008] On the other hand, the present invention discloses a method for calibrating the preload of a biasing element of a torque wrench, comprising the following steps: providing a torque wrench according to the invention, wherein the biasing element has a useful preload range from a first value to a second value. The next step is to place the torque wrench in a horizontal position on a calibration table. A torque is then applied to the torque wrench until it reaches its torque overload position. An initial torque value is measured at the torque overload position. This initial torque value is then compared with the first value. It is determined whether the initial torque value is within an acceptable tolerance range. If the initial torque value is within the acceptable tolerance range, the next step is performed. If, on the other hand, the initial torque value is not within the acceptable tolerance range, the tension setting in the biasing element is adjusted using the adjuster, and the steps of applying / measuring the initial torque value and comparing it with the first value are repeated until the initial torque value is within the acceptable tolerance range. The next step is to partially disassemble the adjuster by removing the handle and separating the handle insert from the adjusting shaft, and rotating the handle insert to bring one of the gears to the 12 o'clock position. The regulator is then reassembled by re-engaging the handle insert to the adjustment shaft at its new 12 o'clock position, and the handle is reinstalled.

[0009] On the other hand, the present invention discloses a graduated ring for use with a torque wrench, comprising a measuring surface visible from the outside of the torque wrench. The measuring surface has a helical scale to provide readings at a selected torsional resistance threshold level at which a force applied to the wrench body causes the housing structure to pivot relative to a fastener drive structure. The graduated ring also includes a connecting portion that connects to an adjusting nut such that translational movement of the adjusting nut also translates the graduated ring. Attached Figure Description

[0010] The accompanying drawings help to understand various embodiments of the invention. In these drawings:

[0011] Figures 1a and 1b are optional perspective views of a torque wrench constructed according to the principle of the present invention;

[0012] Figure 2 This is an exploded view of the torque wrench in Figure 1;

[0013] Figure 3 This is a cross-sectional view taken along line 3-3 of Figure 1, showing the components of the torque wrench in the normal position;

[0014] Figure 4 This is a cross-sectional view taken along line 4-4 of Figure 1, showing the components of the torque wrench in the normal position;

[0015] Figures 5a and 5b are optional perspective views of the partially disassembled adjuster of the torque wrench of the present invention; the components are constructed according to the principles of the present invention;

[0016] Figure 6 This is a perspective view of the adjusting shaft of the torque wrench's adjuster.

[0017] Figures 7a and 7b are perspective and plan views, respectively, of the retainer insert of the torque wrench adjuster;

[0018] Figures 8a and 8b are optional perspective views of the scale ring of a torque wrench;

[0019] Figure 9 This is a flowchart outlining the steps of a method for calibrating a torque wrench; and

[0020] Figure 10 A plan view of an exemplary label used on the scale ring of the present invention is shown. Detailed Implementation

[0021] Figure 1 shows a torque wrench, generally indicated by 10, for selectively applying torque to fasteners, which embodies the principles of the present invention. Figure 2 -8 shows the main components of the wrench, which include the fastener drive structure, generally shown as 20; the wrench body, generally shown as 30; the tang engaging and stabilizing structure, generally shown as 40; the stress biasing element, generally shown as 50; and the adjuster, generally shown as 60.

[0022] The fastener drive structure 20 has a head 22 configured and arranged to detachably engage with a fastener and a shank structure 24 extending rearward from the head 22. The shank structure 24 has a hole 26 extending through its front portion 25. In the illustrated embodiment, the head 22 is a conventional sleeve-type ratchet head. The head 22 includes a mounting portion 28 integrally formed with the shank structure 24 and a conventional ratchet drive assembly 13 housed within the mounting portion 28. The main components of the conventional ratchet drive assembly are a ratchet 15, a pawl 17, and a pawl biasing element 19. The ratchet is rotatably mounted within the mounting portion such that the ratchet and the mounting portion can rotate relative to each other about the ratchet axis. The ratchet has a plurality of teeth on its outer periphery and a square sleeve mounting portion, indicated by 23 in Figures 1b, 2, and 3, for detachably mounting a conventional sleeve to achieve a detachable connection with the fastener. A pawl is mounted within the mounting portion 28 and biased to engage with the gear teeth, such that the pawl engages with the gear teeth in one direction and ratches over them in the opposite direction. A cover plate, indicated by 21 in Figures 1a, 2, and 3, is mounted on the mounting portion 28 in a covering relationship to enclose the ratchet, pawl, and biasing element. Ratchet drive assemblies are well known in the art and need not be described in detail here.

[0023] Alternatively, the ratchet can be an annular ring with a fastener receiving opening defined by a plurality of fastener engagement surfaces that engage with a flat driven surface on the head of the fastener received therein. Furthermore, while the head 22 is preferably ratchet-type, the invention can be implemented with a non-ratchet head, such as a wrench head with an end opening.

[0024] The wrench body 30 includes a generally cylindrical housing structure 32 having a generally cylindrical inner surface 34 and an outer surface 36. One end 35 of the housing structure 32 has a through hole 38. The opposite end 37 is configured to mount an adjuster 60, which will be described in more detail below. Although the principles of the invention are preferably applied to wrenches having a cylindrical housing structure (i.e., round housing wrenches), they can also be implemented in wrenches having a housing structure with a rectangular cross-section (i.e., flat housing wrenches).

[0025] Fastener drive structure 20 and housing structure 32 are pivotally connected for pivoting relative to each other about pivot axis 80 between a normal position and a torque-over-torque position. In the normal position, such as... Figures 3-4As shown, a torque overload signal is generated at the torque overload position, as will be discussed further below. Specifically, the shank structure 24 of the fastener drive structure 20 is inserted into the housing structure 32 and the holes 26, 38 are aligned. Then, the pivot pin 82 is inserted into the holes 26, 38. As a result, the fastener drive structure 20 and the housing structure 32 pivot about the pivot pin 82 that defines the pivot axis 80.

[0026] The shank engagement and stabilization structure 40 includes a tilting block 90 and a pusher 100. The tilting block 90 includes a front end 90a and a rear end 90b. As will be discussed below, when the housing structure is in its normal position, the front end engages the rear end portion 27 of the shank flush with the rear end, and the rear end engages the pusher flush with the rear end. The term "flush" simply means that a large portion of the end face is in direct contact with its corresponding surface. Conversely, when the housing structure is in its torque-over-range position, the edge 90c of the tilting block adjacent to the front end engages the rear end portion of the shank, and another edge 90d adjacent to the rear end engages the pusher.

[0027] The rear end portion 27 of the foot structure 24 and the pusher 100 each have recesses 29, 49 formed therein. The tilting block 90 is received in the recesses 29, 49 and is movable between the recesses 29, 49 to accommodate the pivoting movement of the housing structure 32 with the foot engagement and the stabilizing structure 40 relative to the fastener drive structure 20.

[0028] Those skilled in the art will recognize that the tilting block 90 can be a cube. Therefore, the front end 90a and rear end 90b of the tilting block 90 each have a pair of generally parallel edges 90c, 90d. The tilting block 90 and the recesses 29, 49 are oriented such that the pair of generally parallel edges 90c, 90d are arranged to be substantially parallel to each other. Furthermore, the tilting block 90 is configured such that the distance between the opposite edges of its front end 90a and rear end 90b is greater than the distance between adjacent edges of its front end 90a and rear end 90b.

[0029] A stress biasing element 50, in the form of a helical spring 52, applies a biasing force to the shank engagement and stabilizing structure 40 to maintain the recess 49 of the pusher 100 engaged with the tilting block 90, thereby keeping the housing structure 32 and the fastener drive structure 20 in their normal positions, such as... Figures 3-4 As shown. One end 54 of the biasing element 50 engages with the pusher 100, while the other end 65 engages with the washer 72 located on top of the spacer 70.

[0030] The movement of spacers 70 and 72 is controlled by and can be considered part of adjuster 60. The axial movement of spacers 70 and 72 adjusts the stress in biasing element 50, and thus adjusts the biasing force applied by biasing element 50 to pusher 100. Those skilled in the art will recognize that additional spacers 73 and bearings 75 can also be used within adjuster 60. These additional spacers and bearings are not necessary, as their geometry can be integrated into other components. Rather, their presence is for improved manufacturing efficiency.

[0031] The adjuster 60 is constructed and arranged such that its rotational movement adjusts the stress in the biasing element, and thus adjusts the biasing force applied by the biasing element to the shank engagement and stabilizing structure, thereby setting a threshold level of torsional resistance at which the force applied to the wrench body causes the housing structure to pivot relative to the fastener drive structure from a normal position to a torque-over-torque position. The adjuster 60 includes an adjusting shaft 62 having a threaded portion 64, a splined portion 66, and a pin-retaining portion 68. The threaded portion 64 may include a standard thread, such as 2N-LH-M10×1.0-6g, where N is the number of thread starts. In this case, the thread is double-start. LH indicates a left-hand thread. M10 is the thread outer diameter in millimeters. In this case, the outer diameter is 10 mm. The number 1.0-6g refers to a 1.0 mm pitch and a precision tolerance. Therefore, for every revolution of the adjusting shaft, the thread moves 1.0 mm. However, because the number of thread starts is 2, the thread travels 2.0 mm per revolution. Those skilled in the art will recognize that the threaded portion 64 may include other standard threads without departing from the scope of the invention. The spline portion 66 may include a plurality of grooves 67 serving as splines. In a preferred embodiment, the spline portion 66 includes 10 splines. The primary function of the splines is to engage with an external object and transmit the rotational motion of the external object to the adjusting shaft 62. Finally, the pin engagement portion 68 of the adjusting shaft is a chamfered groove 69. Preferably, the chamfered groove extends around the circumference of the adjusting shaft 62. Having a chamfered groove surrounding the adjusting shaft allows the pin to engage the adjusting shaft in any rotational position. As will be discussed below, this is advantageous when reassembling the adjuster as part of a calibration process.

[0032] The adjuster 60 also includes a handle insert 74 having an outer surface 76 shaped to define one or more gears 77 and an inner opening 78 shaped to receive a splined portion 66 of the adjusting shaft 62, wherein the surface 84 of the inner opening includes one or more splines 86 configured to engage with splines 67 of the adjusting shaft such that rotation of the handle insert 74 will rotate the adjusting shaft 62. In a preferred embodiment, the handle insert 74 will include three mirrored gears 77 as shown in Figures 7a and 7b. Preferably, the handle insert 74 also includes ten internal splines 86 to match the preferred number of splines on the splined portion of the adjusting shaft.

[0033] The adjuster 60 also includes a handle 88 having an inner recess 92 configured to receive a handle insert 74, wherein the inner recess is positioned within the handle such that at least one gear 77 on the outer surface of the handle insert is in a 12 o'clock position within the handle 88, and wherein when the handle insert is positioned in the inner recess, rotational movement of the handle applies a rotational force to the handle insert 74 and subsequently to the adjusting shaft 62.

[0034] The handle 88 may also include a locking ring 91 biased by a spring 93. The locking ring is configured to prevent unwanted rotational movement in the handle. Therefore, the locking ring prevents the handle from rotating until such rotational movement is required. In operation, the user can pull the locking ring 91 downward against the bias of the spring 93. This unlocks the handle and allows rotational movement. When the user releases the locking ring, the spring biases it back to its locked position, where rotational movement of the handle is restricted.

[0035] The adjuster 60 also includes an adjusting nut 94. The adjusting nut defines an opening 96 having a threaded surface 98 configured to engage with a threaded portion 64 of the adjusting shaft 62, wherein when a rotational force is applied to the adjusting shaft, the engaging threaded portion causes the adjusting nut to translate and applies a biasing force to the biasing element 50, adjusting the spacer 70.

[0036] In a preferred embodiment, the adjuster 60 further includes a scale ring 102. As shown in Figures 8a and 8b, the scale ring is generally cylindrical in shape and includes a measuring surface 104 visible from the outside of the torque wrench 10. The measuring surface includes a helical scale 103 to provide readings at selected torsional resistance threshold levels at which forces applied to the wrench body cause the housing structure to pivot relative to the fastener drive structure. In a preferred embodiment, the measuring surface includes graduations for torque measurement in metric units (Newton-meters) and imperial units (foot-pounds).

[0037] In a preferred embodiment, the spiral scale 103 is printed on a label 111 affixed to the measuring surface 104. The specific location and positioning of the values ​​of the spiral scale 103 are determined by a method that relies on both the characteristics of the threaded portion of the adjusting shaft and the geometry of the measuring surface. The first step is to determine the length of the label 111. This is achieved by using the circumference of the measuring surface, which is equal to the diameter × π. For precision, the label thickness can be doubled to obtain the accurate desired label length. This length is then divided into equal scales to allow for a reading obtained after a full rotation along the measuring surface. In a preferred embodiment, the label length is divided into 10 equal scales. After determining the label length and scale size, the pitch of the spiral must be determined. In other words, how far the scale ring translates after each full rotation. This pitch is controlled by the characteristics of the threaded portion 64 of the adjusting screw 62. As mentioned above, the threaded portion can use a standard thread, such as 2N-LH-M10 × 1.0-6g. In this type of thread, the number 1.0-6g refers to a 1.0mm pitch and its tolerance. Therefore, for every revolution of the adjusting shaft, the thread moves 1.0mm. However, because there are two thread starts, the thread travels 2.0mm per revolution. To create our helical scale 103, moving from right to left, for each of our ten equal scales, the next number must be 0.2mm lower than the number immediately to its right. Therefore, when a full revolution is completed, the number on the scale will be exactly 2.0mm lower than the number directly above it. See also... Figure 10 Those skilled in the art will recognize that, without departing from the scope of the invention, helical scales with different diameters of measuring surfaces and / or different threads of adjusting shafts can be readily created.

[0038] In a preferred embodiment, the spiral scale 103 will include both metric and imperial units. After determining the position of the numerals in the first scale (e.g., metric), the imperial numerals can be directly inserted into the middle of each of the ten equal scales. To improve the readability of the graphic, the different scales can be slightly offset from each other. Furthermore, the fonts or embossing of the different scales can be different to avoid confusion when reading the various scales.

[0039] The scale ring 102 also includes a connecting portion 106 for connecting the scale ring to the adjusting nut 94. The connecting portion includes a series of fins 107 and a main groove 109. The fins 107 are spaced apart from an end 105 of the scale ring. The end 105 includes a lip 108. However, the main groove 109 extends to this end of the scale ring. The main groove 109 is configured to engage with a screw 89 located inside the handle 88. Thus, when the handle 88 is rotated, the screw 89 engages one of the fins 107 adjacent to the main groove 109, and subsequently rotates the scale ring. The lip 108 of the connecting portion 106 is configured to be received by a scale retainer 110. The scale retainer 110 is configured to engage both the lip 108 and the adjusting nut 94 simultaneously. The scale retainer engages the lip 108 in such a way that the rotational movement of the scale ring is free, while the axial movement of the scale ring is restricted. The scale retainer can be attached to the adjusting nut 94 via screw 112. Because the scale retainer 112 attaches the scale ring to the adjusting nut 94, any translational movement of the adjusting nut will also cause the scale ring to translate. Those skilled in the art will recognize that the scale ring 102 and / or scale retainer 110 of the present invention can be used in conjunction with any torque wrench.

[0040] In a preferred embodiment, the measuring surface 104, more specifically, the helical scale is visible from the outside of the torque wrench. This is achieved by a nose 114 comprising one or more lenses 116. In one embodiment, the nose 116 comprises two lenses that allow visual access to both the helical scale with metric units and the helical scale with imperial units. Those skilled in the art will recognize that the nose 114 may also include a nose cap 115 and a hose retainer 117, which help maintain the position of the nose 114 on the torque wrench.

[0041] The operation of the torque wrench 10 will now be described in more detail. First, the operator grasps the wrench 10 around the handle 88 of the adjuster 60 and detachably engages the head 22 with the fastener. The user then applies force to the wrench body 30, which is transmitted as torque through the shank engagement and stabilizing structure 40 and the fastener drive structure 20 to the detachably engaged fastener. However, this force also tends to cause the housing structure 32 to pivot relative to the fastener drive structure 20 about the pivot axis 80.

[0042] In wrench types using ratchet drive assemblies, when the socket of the head 22 is coupled to a fastener in a torque transmission relationship, the hand force applied to the wrench body 30 in the torque application direction is transmitted from the wrench body 30 to the fastener drive structure 20, and then from the fastener drive structure to the fastener via the drive engagement between the pawl and the ratchet, thereby applying torque to the fastener to affect its rotation. The hand force applied to the wrench body 30 in the ratcheting direction, opposite to the torque application direction, causes the wrench body 30 to rotate relative to the ratchet, wherein the pawl repeatedly slides across the ratchet teeth in a ratcheting manner, overcoming the bias of the pawl biasing element.

[0043] The biasing force applied by the biasing element 50 keeps the foot engagement and stabilizing structure 40 engaged with the rear end portion 27 of the foot, particularly with the tilt block 90, thereby holding the housing structure 32 and the fastener drive structure 20 in their normal positions until the torsional resistance provided by the fastener reaches a threshold level determined by the biasing force of the biasing element 50. Specifically, in the illustrated embodiment, the engagement of the foot engagement and stabilizing structure 40 keeps the foot structure 24 (and the entire fastener drive structure 20) substantially aligned with the housing structure 32. In this position, the front end 90a and rear end 90b of the tilt block 90 engage flush with the rear end portion 27 and the pusher, respectively. At the threshold level of fastener resistance, the force applied to the wrench body 30 overcomes the biasing force of the biasing element 50 and pivots the housing structure 32 relative to the fastener drive structure 20 to a torque-over-torque position, where the tilt block 90 tilts such that edges 90c and 90d engage with the rear end portion 27 and the pusher 100, respectively. As the tilt block 90 tilts, this generates a torque-over-torque signal. This signal indicates that the torsional resistance provided by the fastener has reached a threshold level.

[0044] The torque exceedance signal is generated by the rear end portion 27 of the handle structure 24 and the housing structure 32, which are in contact at the torque exceedance position, to produce audible noise. It is conceivable that a contact switch could be positioned at the contact point between the handle structure 24 and the housing structure 32, actuating an indicator light or audible beep to inform the user that the threshold level has been reached.

[0045] The tilting block 90 and the recesses 29 and 49 are configured such that, during the pivoting movement of the housing structure 32 relative to the fastener drive structure 20 to a position where the torque exceeds the limit, one edge of its front end 90a pivots around one edge of the recess 29 of the shank rear end portion 27, and the opposite edge of its rear end 90b pivots around the recess 49 of the actuator 100. Because the distance between the opposite edges of the tilting block 90 is greater than the distance between its adjacent edges, the tilting block 90 pushes the shank engagement and stabilizing structure 40 rearward, and the biasing element 50 is subjected to increasing stress due to the tilting block 90 during the aforementioned pivoting movement.

[0046] The biasing force applied by the biasing element 50 maintains the engagement of the recess 49 of the pusher 100 with the tilting block 90, thereby holding the housing structure 32 and the fastener drive structure 20 in their normal positions, such as Figures 3-4 As shown, until the torsional resistance provided by the fastener reaches the aforementioned threshold level, at which the force applied to the housing structure 32 is sufficient to affect the aforementioned pivoting movement of the tilt block 90 against the biasing force of the biasing element 50.

[0047] The adjuster 60 sets a threshold level for the aforementioned torsional resistance, at which the force applied to the wrench body 30 causes the housing structure 32 to pivot relative to the fastener drive structure 20. As described above, the handle 88 of the adjuster 60 can rotate relative to the housing structure 32 to adjust the adjusting shaft 62, thereby adjusting the biasing force applied to the handle engagement and stabilizing structure 40 by the biasing element 50.

[0048] The torque wrench 10 of the present invention must be calibrated before its initial use and periodically throughout its service life. Generally, calibrating a torque wrench is an iterative two-step process, in which, in the first step, a preload is set on the biasing element, and in the second step, an internal lever associated with the tilting block 90 is set. The present invention significantly improves the method associated with the first step.

[0049] The disclosed method for calibrating the preload of a biasing element includes a first step of providing a torque wrench according to the invention. The torque wrench includes a biasing element having a useful preload range from a first value to a second value. For example, the torque wrench may have a useful range of 5-25 Nm, 10-50 Nm, 20-100 Nm, 40-200 Nm, 60-340 Nm, or any other range. For the purposes of our example, assume we will calibrate a torque wrench with a useful range of 10-50 Nm. Therefore, the first value is 10 Nm, and the second value is 50 Nm.

[0050] Next, place the torque wrench horizontally on the calibration platform. The calibration platform accurately measures the torque applied by the torque wrench. Insert the square socket of the torque wrench into the calibration platform and keep the handle horizontal.

[0051] After placing the torque wrench on the calibration table, apply torque to the handle until the torque exceedance position is reached. The calibration table measures this initial torque value and gives a reading. In our example, let's assume this initial torque value is measured as 5 Nm. Compare this initial torque value to a first value of 10 Nm. 5 Nm is well over the acceptable tolerance of 10 Nm, for example, ±2%.

[0052] Because the initial torque value exceeds the acceptable tolerance, the preload of the bias element must be adjusted. This adjustment can be achieved by rotating the adjuster 60 to compress the bias element 50. More specifically, the locking ring 91 is disengaged by pulling it down against the spring 93, at which point the handle 88 can rotate. When the handle 88 rotates, the handle insert 74, located within the inner recess 92, also rotates. The splines of the handle insert and the mating splines of the adjusting shaft also rotate. Therefore, the entire adjusting shaft rotates. As the threaded portion of the adjusting shaft rotates, the mating threads of the adjusting nut cause the entire adjusting nut to translate axially. Figure 3 and Figure 4 As shown, this causes the spacer 70 and washer 72 to compress the bias element 50. After compressing the bias element using the adjuster 60, another torque is applied to the torque wrench and the new initial torque value is measured. This new initial value is compared to the first value of 10 Nm. The following process is repeated until the initial torque value is within the acceptable tolerance of the first torque value: adjust the adjuster to apply (or reduce) the bias force in the bias element; apply torque to the torque wrench; measure the initial torque value and compare it to the first value.

[0053] Those skilled in the art will recognize that adjusting the bias element has caused misalignment of the adjuster itself and the scale ring (if present). Therefore, the next step is to partially disassemble the adjuster and realign the handle 88, handle insert 74, and main pin 82. Additionally, if present, the scale ring can be adjusted to allow 10 Nm of light to be seen through the lens 116 at the nose 114. As shown in FIG5a, the adjuster 60 is partially disassembled by first removing the pin 119 and then removing the handle 88. The pin 119 is disposed in the handle 88 and engages the pin retaining portion 68 of the adjusting shaft 62. More specifically, the pin 119 engages the chamfered groove 69 of the adjusting shaft. After removing the pin, the handle 88 can be removed. After removing the handle 88, the handle insert 74 is removed and rotated clockwise or counterclockwise until at least one of its external gears 77 is in the 12 o'clock position. This realignment can be guided by the hole 121 located in the end 37 of the housing structure 32. Hole 121 is aligned with hole 38 and pivot pin 82 located on opposite end 35 of the housing structure. By aligning at least one of the gears 77 with the 12 o'clock position, the operator ensures that future adjustments will accurately compress or decompress the bias element in a precise and consistent manner.

[0054] Now is a good time to discuss the specific features of the handle insert 74. Those skilled in the art will recognize that the handle insert 74 can be constructed in a virtually unlimited number of ways with respect to the number of external gears and internal splines. However, due to engineering / manufacturing tolerances, the handle insert preferably comprises three (3) mirror-finish external gears and ten (10) internal splines. This results in thirty (30) possible divisions when the handle insert is rotated about the adjusting shaft (i.e., each of the three mirror-finish gears has 10 different spline positions). It has been determined that the individual incremental adjustment of these 30 divisions will increase (or decrease) by 0.07 Nm (1.33%) for small torque wrenches of 5-25 Nm; or by 1.33 Nm (2.22%) for large torque wrenches of 60-340 Nm. These incremental adjustments are within an acceptable tolerance of ±2%. However, if the product of the external gear and the internal spline is much less than 30, individual increments will exceed the tolerance, especially with larger wrench sizes. Conversely, if the product of the external gear and the internal spline is 60, the tolerance will be better (see table below). However, manufacturing and machining parts at this level of precision can prove costly and inefficient. Furthermore, the improvement in tolerance is not worth the extra cost / trouble.

[0055]

[0056] After aligning the handle insert to position one of its gears at the 12 o'clock position, the adjuster needs to be reassembled. After setting the preload in the bias element, the adjusting shaft cannot be moved at all. Otherwise, the preload we just painstakingly calibrated will be lost and inaccurate. This is particularly difficult in the prior art because the adjusting shaft typically includes a cylindrical pin retainer portion comprising two sets of vertically aligned holes for receiving and retaining the pin 121. Imagine how difficult it would be to assemble the handle 88 and then attempt to position one set of said vertically aligned holes with the retaining pin 121 without moving the adjusting shaft and losing the calibration preload of the bias element 50. The present invention overcomes this problem by completely eliminating the two sets of vertically aligned holes for receiving and retaining the pin 121. Instead, the present invention includes an adjusting shaft 62 with a pin retainer portion 68 having a circumferentially chamfered groove 69. The chamfered groove 69 allows the retaining pin to engage easily, regardless of the orientation of the adjusting shaft. Furthermore, and crucially, the insertion of pin 121 into handle 88 and engagement with the adjustment shaft does not interfere with the setting of the adjustment shaft and the preload of the bias element.

[0057] Therefore, it can be understood that the objectives of the present invention have been fully and effectively achieved. The foregoing specific embodiments are provided to illustrate the structural and functional principles of the invention, and are not intended to be limiting. Rather, the invention is intended to cover all modifications, alterations, and substitutions within the spirit and scope of the appended claims.

Claims

1. A torque wrench (10) for applying torque to a fastener, the torque wrench comprising: Fastener drive structure (20) having a head (22) configured and arranged to removably engage with a fastener and a shank structure (24) extending rearward from the head. The wrench body (30) includes a housing structure (32) in which the fastener drive structure and the housing structure are pivotally connected for pivoting about a pivot axis (A) from a normal position relative to each other to a torque-over-torque position to generate a torque-over-torque signal; A foot engagement and stabilizing structure (40) having a tilting block (90) and a pusher (100), wherein the tilting block includes a front end (90a) and a rear end (90b), and wherein when the housing structure is in its normal position, the foot engagement surface engages flush with the rear end portion (27) of the foot structure, and the pusher engagement surface engages flush with the pusher, and wherein when the housing structure is in its torque-over position, the edge (90c) of the tilting block adjacent to the foot engagement surface engages the rear end portion of the foot structure, and the other edge (90d) of the tilting block adjacent to the pusher engagement surface engages the pusher; A biasing element (50) applies a biasing force to the shank engagement and stabilizing structure such that, during torque application operation, the force applied to the wrench body (a) is transmitted as torque to the fastener detachably engaged with the head, and (b) tends to pivot the housing structure relative to the fastener drive structure about the pivot axis. The biasing force applied by the biasing element maintains the shank engagement and stabilizing structure engaged with the rear end portion of the shank structure, thereby keeping the housing structure and the fastener drive structure in their normal positions until the torsional resistance provided by the fastener reaches a threshold level determined by the biasing force of the biasing element. At this point, the force applied to the wrench body pivots the housing structure relative to the fastener drive structure to the torque-over-threshold position to generate the torque-over-threshold signal, indicating that the torsional resistance provided by the fastener has reached the threshold level. An adjuster (60) is configured and arranged such that its rotational movement adjusts the stress in the biasing element, and thereby adjusts the biasing force applied by the biasing element to the shank engagement and stabilizing structure, thereby setting a threshold level for the torsional resistance at which the force applied to the wrench body causes the housing structure to pivot relative to the fastener drive structure as previously described; and The regulator is characterized in that it includes... The adjusting shaft (62) has a threaded portion (64), a splined portion (66) and a pin retaining portion (68). A handle insert (74) has an outer surface (76) shaped to define one or more gears (77) and an inner opening (78) shaped to receive the spline portion (66) of the adjusting shaft (62), wherein the surface (84) of the inner opening includes one or more splines (86), the splines (86) of the inner opening surface (84) of the handle insert (74) being configured to engage with the splines (67) of the spline portion (66) of the adjusting shaft (62) such that rotation of the handle insert (74) will cause rotation of the adjusting shaft (62); A handle (88) having an internal recess (92) configured to receive the handle insert, wherein the internal recess is positioned within the handle such that at least one gear on the outer surface of the handle insert is positioned at the 12 o'clock position within the handle, and wherein when the handle insert is disposed in the internal recess, rotational movement of the handle applies a rotational force to the handle insert and subsequently transmits it to the adjustment shaft; and Adjusting nut (94) defines an opening (96) having a threaded surface (98) configured to engage with the threaded portion of the adjusting shaft, wherein when a rotational force is applied to the adjusting shaft, the engaging threaded portion causes the adjusting nut to translate, the adjusting nut adjusting bearing (75) and applying a biasing force to the biasing element (50); The rotation of the handle (88) causes the handle insert (74) and the adjusting shaft (62) disposed in the inner recess (92) to also rotate, so as to adjust the preload of the biasing element (50).

2. The torque wrench (10) according to claim 1, wherein, The adjuster (60) further includes a scale ring (102) having a measuring surface (104) visible from the outside of the torque wrench, wherein the measuring surface includes a helical scale (103) to provide a reading of a selected torsional resistance threshold level at which a force applied to the wrench body causes the housing structure to pivot relative to the fastener drive structure, and wherein the scale ring further includes a connecting portion connected to the adjusting nut such that translational movement of the adjusting nut also causes translation of the scale ring; The handle (88) also includes a locking ring (91) biased by a spring (93). The user pulls the locking ring (91) down against the bias of the spring (93) to unlock the handle and allow the handle to rotate.

3. The torque wrench (10) according to claim 2, wherein, The scale ring (102) is also connected to the handle (88), so that the rotation of the handle also causes the scale ring to rotate.

4. The torque wrench (10) according to claim 2 or 3, wherein, The graduated ring (102) includes imperial and metric units of measurement.

5. The torque wrench (10) according to claim 2, wherein, The pitch of the helical scale (103) is a multiple of the pitch of the threaded portion of the adjusting shaft.

6. The torque wrench (10) according to claim 2, wherein, The adjuster (60) also includes a scale retainer (110) configured to connect the connecting portion of the scale ring to the adjusting nut.

7. The torque wrench (10) according to claim 6, wherein, The scale retainer (110) is fixed to the adjusting nut (94) by a screw (112) that allows the scale retainer to move axially relative to the adjusting nut.

8. The torque wrench (10) according to claim 2, wherein, The spiral scale (103) is a separate label (111) attached to the measuring surface.

9. The torque wrench (10) according to claim 2, wherein, The pusher (100) includes a recess (49) configured to receive the tilt block.

10. A method for calibrating the preload of a bias element (50) of a torque wrench (10), comprising the following steps: A torque wrench (10) according to any one of the preceding claims is provided, wherein the biasing element (50) has a useful preload range from a first value to a second value; Place the torque wrench horizontally on the calibration table; Apply torque to the torque wrench until it reaches its torque over-position, and measure the initial torque value at the torque over-position; The initial torque value is compared with the first value to determine whether the initial torque value is within an acceptable tolerance range. If the initial torque value is within the acceptable tolerance, proceed to the next step; If the initial torque value is not within the acceptable tolerance range, the tension setting in the bias element is adjusted using the regulator (60), and the steps of applying / measuring the initial torque value and comparing the initial torque value with the first value are repeated until the initial torque value is within the acceptable tolerance range. The regulator is partially disassembled by removing the handle (88) and separating the handle insert (74) from the adjusting shaft (62), and by rotating the handle insert to position one of the gears (77) at the 12 o'clock position; and The regulator is reassembled by re-engaging the handle insert to the adjustment shaft at its new 12 o'clock position; and the handle is reinstalled.

11. A scale ring (102) for use with a torque wrench (10) according to claim 1, comprising a measuring surface (104) visible from the outside of the torque wrench, and the measuring surface having a helical scale (103) to provide a reading of a selected torsional resistance threshold level at which a force applied to the wrench body causes the housing structure to pivot relative to a fastener drive structure, and wherein the scale ring further comprises a connecting portion (106) for connecting the scale ring to the adjusting nut (94), the connecting portion being connected to the adjusting nut (94) such that a translational movement of the adjusting nut also causes a translational movement of the scale ring.

12. The graduated ring according to claim 11, wherein, The connecting portion (106) includes a series of fins (107) and a main groove (109), the fins (107) being spaced apart from the end (105) of the scale ring; The spiral scale is in metric and imperial units.

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