Torque measuring device

Abstract

Provided is a torque measuring device capable of preventing a magnetostrictive sensor supported to a housing from rotating relative to the housing. A torque measuring device (1) includes a housing (2) that does not rotate in use, a rotating shaft (3) supported so as to be able to rotate relative to the housing (2) and having a magnetostrictive effect portion (8) whose magnetic permeability changes according to a transmitted torque, and a magnetostrictive sensor (4) having a detection portion (10) disposed in proximity to the magnetostrictive effect portion (8) and changing a voltage in correspondence with a change in the magnetic permeability of the magnetostrictive effect portion (8), and supported to the housing (2), and the torque measuring device has a rotation prevention configuration that prevents the magnetostrictive sensor (4) from rotating relative to the housing (2).

Description

Technical Field

[0001] This invention relates to a torque measuring device for measuring the torque transmitted by a rotating shaft. Background Technology

[0002] In recent years, the following systems have been developed in the automotive field: measuring the torque transmitted by the rotating shaft that constitutes the power transmission system, and using the measurement results to execute output control of the engine and electric motor, which serve as power sources, and speed control of the transmission.

[0003] Currently, magnetostrictive torque measuring devices are known as structures for measuring the torque transmitted by a rotating shaft. In such devices, as described in Japanese Patent Application Publication No. 59-61730, a magnetostrictive material is fixed to the outer circumferential surface of the rotating shaft, and a magnetostrictive sensor for detecting changes in the permeability of the magnetostrictive material is disposed near the material. When a torque is applied to the rotating shaft, elastic torsional deformation occurs in the magnetostrictive material, resulting in a change in its permeability based on the inverse magnetostrictive effect. Consequently, the output signal of the magnetostrictive sensor changes accordingly with the change in the permeability of the magnetostrictive material, thereby enabling the measurement of the torque transmitted by the rotating shaft.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 59-61730 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In existing magnetostrictive torque measurement devices, if the magnetostrictive sensor, which is positioned near the magnetostrictive material, rotates relative to the housing supporting the magnetostrictive sensor, the measured torque may be inaccurate.

[0009] The object of the present invention is to provide a torque measuring device with a structure that prevents a magnetostrictive sensor supported by a housing from rotating relative to the housing.

[0010] Solution for solving the problem

[0011] One aspect of the torque measuring device of the present invention includes: a housing that does not rotate during use; a rotating shaft supported so as to be rotatable relative to the housing and having a magnetostrictive effect portion whose permeability varies according to the transmitted torque; and a magnetostrictive sensor having a detection portion disposed close to the magnetostrictive effect portion and causing the voltage to change in accordance with the change in the permeability of the magnetostrictive effect portion, and being supported on the housing.

[0012] In particular, one aspect of the torque measuring device of the present invention has an anti-rotation structure that prevents the magnetostrictive sensor from rotating relative to the housing.

[0013] One embodiment of the torque measuring device of the present invention further includes an outer ring disposed around the rotating shaft and embedded within the housing. Furthermore, the magnetostrictive sensor is supported on the housing via the outer ring.

[0014] In this case, a structure with a rolling bearing can be adopted, which is configured to include the outer ring and support the rotating shaft for free rotation relative to the housing.

[0015] Alternatively, a structure with a one-way clutch can be used, which is configured to include the outer ring, allowing the rotating shaft to rotate relative to the housing in a predetermined direction, and preventing the rotating shaft from rotating relative to the housing in a direction opposite to the predetermined direction.

[0016] In one aspect of the torque measuring device of the present invention, the aforementioned anti-rotation structure is formed by engaging a protrusion that protrudes radially outward from a portion of the circumferential direction of the magnetostrictive sensor with a portion of the housing.

[0017] In this case, in one aspect of the torque measuring device of the present invention, a portion of the housing is an axially elongated groove provided on the inner circumferential surface of the housing, an end of a wire harness is connected to the axial side of the protrusion, and a portion of the wire harness is disposed inside the groove.

[0018] In one aspect of the torque measuring device of the present invention, the aforementioned anti-rotation structure is formed by engaging a portion of a protrusion that protrudes radially outward from the circumferential direction of the outer ring with a portion of the outer housing.

[0019] In one aspect of the torque measuring device of the present invention, the aforementioned anti-rotation structure is formed by fitting the outer peripheral surface of the outer ring with the inner peripheral surface of the outer shell in a non-circular manner.

[0020] The effects of the invention are as follows.

[0021] According to one aspect of the present invention, a torque measuring device is provided with a configuration capable of preventing a magnetostrictive sensor supported on a housing from rotating relative to the housing. Attached Figure Description

[0022] Figure 1 This is a perspective view of a torque measuring device showing a first example of an embodiment of the present invention, with the rotation axis omitted.

[0023] Figure 2 This is a cross-sectional view showing the torque measuring device of the first example.

[0024] Figure 3 This is a diagram of the first example of a torque measuring device, observed from the axial side.

[0025] Figure 4 This is a cross-sectional view illustrating an example of a reference example associated with the present invention.

[0026] Figure 5 This is a perspective view of a torque measuring device according to a second embodiment of the present invention, omitting the outer casing.

[0027] Figure 6 This is a cross-sectional view showing the torque measuring device in the second example.

[0028] Figure 7 This is a partial cross-sectional view of a torque measuring device of a third embodiment of the present invention, viewed from the opposite axial side with the rotation axis omitted.

[0029] Figure 8 This is a cross-sectional view of a fourth embodiment of the torque measuring device of the present invention, viewed from the opposite axial side with the rotation axis omitted.

[0030] Figure 9 This is a cross-sectional view of a torque measuring device according to a fifth embodiment of the present invention.

[0031] Figure 10 This is a cross-sectional view of a torque measuring device according to a sixth embodiment of the present invention.

[0032] Figure 11 This is a cross-sectional view of the torque measuring device according to the seventh embodiment of the present invention. Detailed Implementation

[0033] [First example]

[0034] use Figures 1-3 The torque measuring device of the first embodiment of the present invention will be described.

[0035] The torque measuring device 1 in this example is a device for measuring the torque transmitted by the rotating shaft 3, and can be installed in various mechanical devices. Specific examples of mechanical devices that can be installed in the torque measuring device 1 in this example include mechanical devices constituting the powertrain of an automobile, such as automatic transmissions (AT), belt-driven continuously variable transmissions (CVTs), toroidal CVTs, semi-automatic transmissions (AMTs), dual-clutch transmissions (DCTs), and other transmissions that change speeds under vehicle-side control, as well as transfer cases and manual transmissions (MTs). Furthermore, the drive type of the vehicle being tested, such as FF, FR, MR, RR, 4WD, etc., is not particularly limited. Specific examples of mechanical devices that can be installed in the torque measuring device 1 in this example include speed reducers and speed increasers constituting windmills, railway vehicles, and steel rolling mills.

[0036] The torque measuring device 1 in this example includes a housing 2, a rotating shaft 3, and a magnetostrictive sensor 4. Furthermore, the torque measuring device 1 has an anti-rotation structure to prevent the magnetostrictive sensor 4 from rotating relative to the housing 2. In this example, the anti-rotation structure is constructed by engaging a portion of a protrusion 18 that protrudes radially outward from a portion of the circumferential direction of the magnetostrictive sensor 4 with a portion of the housing 2.

[0037] Unless otherwise specified, regarding torque measuring device 1, the axis is the axis of rotation shaft 3, that is... Figure 2 The left and right directions within. Furthermore, one side is axial. Figure 2 On the right side of the axis, the other side is Figure 2 On the left side of the middle.

[0038] The outer casing 2 does not rotate during use. The outer casing 2 has an inner circumferential surface 6 formed by a cylindrical surface extending axially. Furthermore, the outer casing 2 has a groove 19 extending axially along its entire length at a location on the inner circumferential surface 6. In the illustrated example, the groove 19 has an end face shape that is rectangular when viewed from the axial direction.

[0039] The rotating shaft 3 is supported so that it can rotate relative to the housing 2, transmits torque during use, and has a magnetostrictive effect part whose magnetic permeability varies according to the transmitted torque.

[0040] The rotating shaft 3 is inserted through a central hole defined by the inner circumferential surface 6 of the housing 2, and is coaxially arranged with the inner circumferential surface 6. In this state, the rotating shaft 3 is supported by a rolling bearing (not shown) and is able to rotate relative to the housing 2. The axial intermediate portion of the rotating shaft 3... Figure 2 The outer peripheral surface of the intermediate shaft portion 8 shown is composed of a cylindrical surface.

[0041] In this example, by constructing the rotating shaft 3 with a magnetic metal, the intermediate shaft portion 8 of the rotating shaft 3 functions as a magnetostrictive effect portion. As the magnetic metal constituting the rotating shaft 3, various magnetic steels can be used, such as carburized steels like SCr420 and SCM420, and carbon steels like S45C, as specified in JIS.

[0042] If a torque is applied to the rotating shaft 3, and torsional deformation occurs in the intermediate shaft portion 8, then the stress corresponding to the torque is applied to the intermediate shaft portion 8, namely, tensile stress in the 45° direction relative to the axial direction and compressive stress in the -45° direction relative to the axial direction. Simultaneously, the permeability of the intermediate shaft portion 8 in each direction changes due to the dimagnetostrictive effect.

[0043] In implementing this invention, shot peening is performed on the portion of the outer peripheral surface of the intermediate shaft portion 8 that faces the coil 10, which serves as the detection portion of the magnetostrictive sensor 4, thereby forming a compression-hardened layer. This improves both the mechanical and magnetic properties of that portion. Consequently, the sensitivity and hysteresis of the torque measurement of the magnetostrictive sensor 4 can be improved.

[0044] In implementing the present invention, it is also possible to avoid having the intermediate shaft portion 8 itself function as a magnetostrictive effect portion, and instead fix a separate magnetostrictive material, which functions as a magnetostrictive effect portion, to the outer peripheral surface of the intermediate shaft portion 8. For example, a magnetostrictive material formed in a ring shape can be embedded and fixed to the intermediate shaft portion 8, or a coated or thin-film magnetostrictive material such as a plating layer can be fixed to the outer peripheral surface of the intermediate shaft portion 8.

[0045] The magnetostrictive sensor 4 has a detection unit disposed close to the magnetostrictive effect portion of the rotation axis 3 and is supported on the housing 2. The voltage changes in the detection unit in response to changes in the magnetic permeability of the magnetostrictive effect portion.

[0046] The magnetostrictive sensor 4 includes a bracket 9, a coil 10 serving as a detection unit, and a back yoke 11.

[0047] The support 9 is integrally formed using synthetic resin and has a main body 12 and a protrusion 18. The main body 12 is cylindrical. The protrusion 18 protrudes radially outward from a portion in the circumferential direction of the main body 12. In this example, the protrusion 18 is provided along the entire axial length of the main body 12. However, in implementing the present invention, the protrusion may also exist only in a portion of the axial direction of a portion of the main body. In the illustrated example, the protrusion 18 has a rectangular end face shape when viewed from the axial direction. In this example, the end of the wire harness 16 used to extract the voltage signal of the coil 10 of the magnetostrictive sensor 4 is connected to the axial side of the protrusion 18, specifically the side of one axial side of the protrusion 18.

[0048] The coil 10 is cylindrical in shape. The coil 10 is embedded within the main body 12 of the support 9 and is coaxially arranged with the main body 12. In use, an alternating magnetic field is generated around the coil 10 by applying an alternating voltage.

[0049] The back yoke 11 is a component that forms the magnetic circuit of the magnetic flux generated by the coil 10. It is made of magnetic materials such as soft steel and is cylindrical in shape. The back yoke 11 is configured to be embedded in the coil 10 and encased in the main body 12 of the support 9.

[0050] The magnetostrictive sensor 4 is embedded within the inner circumferential surface 6 of the housing 2. Specifically, in this state, the main body 12 of the bracket 9 is embedded in the axial side of the inner circumferential surface 6 of the housing 2 without radial wobble. Furthermore, the protrusion 18 of the bracket 9 engages with the axial side of the groove 19 of the housing 2. That is, in this example, the aforementioned anti-rotation structure is constructed by engaging the protrusion 18 with the groove 19, which is part of the housing 2. Thus, the magnetostrictive sensor 4 is positioned relative to the housing 2 in the rotational direction, and rotation of the magnetostrictive sensor 4 relative to the housing 2 is prevented.

[0051] In this example, such as Figure 1 and Figure 3 As shown, the circumferential width of the groove 19 is slightly larger than the circumferential width of the protrusion 18, and a circumferential gap exists between the inner surfaces on both sides of the inner surface of the groove 19 and the sides of the protrusion 18. Therefore, in this example, due to the presence of such a circumferential gap, it is easy to insert the protrusion 18 axially into the inner side of the groove 19. However, in implementing the present invention, from the perspective of suppressing the circumferential wobble of the magnetostrictive sensor 4a relative to the housing 2a, it is preferable to make such a circumferential gap sufficiently small, or to eliminate such a gap.

[0052] In this example, with the magnetostrictive sensor 4 embedded and held within the inner circumferential surface 6 of the housing 2, the coil 10, which serves as the detection unit, is positioned close to the intermediate shaft portion 8, which serves as the rotation axis 3, in a radially opposing manner covering the entire circumference. Furthermore, a portion of the wire harness 16 is disposed inside the groove 19, specifically inside one axial side of the groove 19.

[0053] If a torque is applied to the rotating shaft 3, causing torsional deformation in the intermediate shaft portion 8, the magnetic permeability of the intermediate shaft portion 8 changes in each direction. This results in a change in the magnetic flux passing through the inner side of the coil 10, which constitutes the magnetostrictive sensor 4. Consequently, the inductance of the coil 10 changes, and based on this, the voltage of the coil 10 changes. Therefore, the torque transmitted by the rotating shaft 3 can be measured using the voltage of the coil 10.

[0054] In implementing the present invention, in addition to coils, magnetic detection elements such as Hall elements can be used as the detection unit of the magnetostrictive sensor.

[0055] In this example, a torque measuring device 1 is provided that prevents the magnetostrictive sensor 4, supported on the housing 2, from rotating relative to the housing 2. Specifically, by engaging a protrusion 18, a portion of the circumference of the magnetostrictive sensor 4 protruding radially outward, with a groove 19 that is part of the housing 2, the magnetostrictive sensor 4 is positioned relative to the housing 2 in the rotational direction, and rotation of the magnetostrictive sensor 4 relative to the housing 2 is prevented. Therefore, the position of the coil 10 of the magnetostrictive sensor 4 relative to the intermediate shaft portion 8 of the rotational shaft 3 in the rotational direction can be appropriately limited. From this perspective, torque measurement errors can be minimized.

[0056] In this example, a structure that prevents the magnetostrictive sensor 4, which is supported on the housing 2, from rotating relative to the housing 2 can be achieved by simply engaging the protrusion 18, which protrudes radially outward from a portion of the circumferential direction of the magnetostrictive sensor 4, with the groove 19, which is part of the housing 2.

[0057] In this example, the main body 12 of the bracket 9 is embedded in the inner circumferential surface 6 of the housing 2 without radial wobble, thereby positioning the magnetostrictive sensor 4 radially relative to the housing 2. Therefore, the radial position of the coil 10 of the magnetostrictive sensor 4 relative to the intermediate shaft portion 8 of the rotation axis 3 can be appropriately limited. In other words, the opposing distance, i.e., the gap, between the outer circumferential surface of the intermediate shaft portion 8 and the coil 10 can be appropriately managed. From this perspective, torque measurement errors can also be minimized.

[0058] In this example, a portion of the wire harness 16 is disposed inside the slot 19. Therefore, the construction of the housing 2 can be simplified compared to the case where a separate path for disposing of a portion of the wire harness 16 is formed relative to the housing 2.

[0059] [First example for reference]

[0060] Figure 4 The first example of a reference example associated with the present invention is shown.

[0061] In the torque measuring device 1A of this reference example, the end of the wire harness 16 is connected to the axial side of the magnetostrictive sensor 4A.

[0062] Specifically, the support 9A constituting the magnetostrictive sensor 4A includes: a cylindrical body 12 that encloses the coil 10 and the back yoke 11; and a terminal portion 14A that protrudes circumferentially from one side of the body 12 on one axial side. The end of the wire harness 16 is connected to the front end face of the axial side of the magnetostrictive sensor 4A, which is also the end face of the terminal portion 14A on one axial side.

[0063] The main body 12 of the bracket 9A constituting the magnetostrictive sensor 4A is embedded in the inner circumferential surface 6 of the outer shell 2A without radial wobbling.

[0064] In this reference example, the end of a wire harness 16 for extracting the voltage signal from the coil 10 of the magnetostrictive sensor 4A is connected to the axial side of the magnetostrictive sensor 4A. Therefore, it is unnecessary to form a recess in the housing 2A for arranging the terminal portion 14A, a portion of the wire harness 16, etc. This simplifies the construction of the housing 2A. Furthermore, the magnetostrictive sensor 4A can be easily mounted relative to the housing 2A. Other structural features and effects are the same as in the first example.

[0065] [Second Example]

[0066] use Figure 5 and Figure 6 A second example of an embodiment of the present invention will be described.

[0067] In this example, the torque measuring device 1b, in addition to the housing 2b, the rotating shaft 3 and the magnetostrictive sensor 4b, also has a rolling bearing 20 that supports the rotating shaft 3 so that it can rotate freely relative to the housing 2b.

[0068] The rolling bearing 20 is configured to include an outer ring 21 disposed around the rotating shaft 3 and embedded in the housing 2b. The magnetostrictive sensor 4b is supported on the housing 2b via the outer ring 21. In implementing this invention, the rolling bearing can be of various forms such as ball bearings, roller bearings, and tapered roller bearings.

[0069] In this example, an anti-rotation structure is constructed to prevent the magnetostrictive sensor 4b from rotating relative to the housing 2b by engaging a portion of the protrusion 26 that protrudes radially outward from a portion of the outer ring 21 with a portion of the housing 2b.

[0070] More specifically, in this example, the rolling bearing 20 is a deep groove ball bearing, having an outer ring 21, an inner ring 22, and a plurality of balls 23 that serve as rolling elements.

[0071] The outer ring 21 has a deep groove-shaped outer ring track 24 on its inner circumferential surface. The outer ring 21 has a small diameter portion 25 at one axial side of its outer circumferential surface, with an outer diameter smaller than that of the portion adjacent to the other axial side. The outer ring 21 has a protrusion 26 projecting radially outward from its outer circumferential surface. Therefore, in this example, the radially inner portion of the metal pin 28 is pressed into a recess 27 located at a circumferential location at the other axial side of the outer ring 21's outer circumferential surface. Furthermore, the radially outer portion of the pin 28 forms the protrusion 26.

[0072] The outer ring 21 is loosely fitted into the inner circumferential surface 6 of the outer casing 2b. In this state, the protrusion 26 engages with an axially elongated groove 19a provided at a location in the circumferential direction of the inner circumferential surface 6 of the outer casing 2b. That is, in this example, the protrusion 26 engages with the groove 19a, which is part of the outer casing 2b, thereby constituting the aforementioned anti-rotation structure. Furthermore, a through hole is formed in the outer casing that extends radially along the rolling bearing, and the front end of a pin inserted into this through hole engages with a recess formed in the outer ring, thereby also constituting an anti-rotation structure. In this case, in addition to preventing rotation of the magnetostrictive sensor and the outer ring relative to the outer casing, axial positioning can also be achieved.

[0073] The inner ring 22 has a deep groove-shaped inner ring track 29 on its outer circumferential surface. The inner ring 22 is interference-fitted into the intermediate shaft portion 8 of the rotating shaft 3.

[0074] Multiple balls 23 are freely arranged between the outer track 24 and the inner track 29 while being held by the retainer 30. Furthermore, Figure 6 The illustration of retainer 30 is omitted.

[0075] In this example, the magnetostrictive sensor 4b is integral with the rolling bearing 20 by being mounted on the outer ring 21 of the rolling bearing 20. The magnetostrictive sensor 4b includes a support ring 31, a bracket 9b, a coil 10, and a back yoke 11.

[0076] The support ring 31 is made of a metal plate and is integrally formed into a ring shape. The support ring 31 includes: a cylindrical fitting portion 32; a hollow circular plate-shaped side plate portion 33 bent at a right angle from one axial end of the fitting portion 32 toward the radially inward side; and a cylindrical support portion 34 bent at a right angle from the radially inward end of the side plate portion 33 toward one axial end. The fitting portion 32 is externally fitted and fixed to the small-diameter portion 25 of the outer ring 21. The radially outer side of the side plate portion 33 abuts against the axial side of the outer ring 21.

[0077] The bracket 9b includes: a cylindrical body 12b that encloses the coil 10 and the back yoke 11 and is embedded in a support cylinder portion 34 fixed to the support ring 31; and a terminal portion 14a that protrudes from a portion of the body 12b in the circumferential direction toward one side in the axial direction and toward the radially outward side.

[0078] The coil 10, which serves as the detection unit, is positioned close to the intermediate shaft 8, which serves as the magnetostrictive effect unit, in a radially opposing manner covering the entire circumference. The end of the wire harness 16 is connected to the front end face of the radially outer end face of the terminal portion 14a.

[0079] In this example, the magnetostrictive sensor 4b is integrated with the rolling bearing 20. Therefore, the torque measuring device 1b can be easily assembled, and the magnetostrictive sensor 4b can be configured with less space.

[0080] The magnetostrictive sensor 4b is supported on the housing 2b by an outer ring 21 embedded within the housing 2b. Therefore, the distance, or gap, between the coil 10 (the detection unit) and the outer peripheral surface of the intermediate shaft 8 (the magnetostrictive effect unit) can be appropriately managed. From this perspective, it is easy to ensure the accuracy of torque measurement.

[0081] In this example, an anti-rotation structure is used to prevent the outer ring 21 from rotating relative to the housing 2b and the magnetostrictive sensor 4b from rotating relative to the housing 2b by engaging the protrusion 26 with the groove 19a. Therefore, undesirable situations such as the wire harness 16 being pulled due to the rotation of the outer ring 21 relative to the housing 2b, i.e., creep, can be avoided. Other structural features and effects are the same as in the first example.

[0082] [Third Case]

[0083] use Figure 7 A third example of an embodiment of the present invention will be described.

[0084] In the torque measuring device 1c of this example, the same as the torque measuring device 1b of the second example, the magnetostrictive sensor, which is configured as an annular shape, is mounted on one end of the axial side of the outer ring 21a that constitutes the rolling bearing 20a. Figure 7 This is a partial cross-sectional view of the torque measuring device 1c in this example, omitting the rotation axis and viewed from the other side of the axial direction.

[0085] In the torque measuring device 1c of this example, an anti-rotation structure is formed to prevent the magnetostrictive sensor from rotating relative to the housing 2c by fitting the outer peripheral surface 35 of the outer ring 21a with the inner peripheral surface 6a of the housing 2c in a non-circular manner.

[0086] Therefore, when the outer peripheral surface 35 of the outer ring 21a is fitted with the inner peripheral surface 6a of the outer shell 2c, the planar portion 36 provided on a portion of the outer peripheral surface 35 in the circumferential direction and the planar portion 37 provided on a portion of the inner peripheral surface 6a of the outer shell 2c are in planar contact with each other. In implementing the present invention, instead of the aforementioned non-circular fitting, fitting with outer and inner peripheral surfaces having polygonal cross-sectional shapes, or serrated fitting, can also be used. Other structures and effects are the same as in the second example.

[0087] [Fourth Case]

[0088] use Figure 8 A fourth example of an embodiment of the present invention will be described.

[0089] In this example, the torque measuring device 1d is the same as the torque measuring device 1b in the second example. The magnetostrictive sensor 4c, which is configured as a ring, is mounted on one end of the outer ring 21 of the rolling bearing 20 on one side of the axial direction. Figure 8 This is a partial cross-sectional view of the torque measuring device 1d in this example, omitting the rotation axis and viewed from the other side of the axial direction.

[0090] In the torque measuring device 1d of this example, an anti-rotation structure is constructed to prevent the magnetostrictive sensor 4c from rotating relative to the housing 2d by engaging a portion of the protrusion 38 protruding radially outward from a portion of the circumferential direction of the magnetostrictive sensor 4c with a portion of the housing 2d.

[0091] Specifically, the aforementioned anti-rotation structure is constructed by engaging a protrusion 38, which is provided on a portion of the circumferential direction of the magnetostrictive sensor 4c and protrudes radially outward beyond the outer circumferential surface of the outer ring 21, with an axially elongating groove 19b provided on a portion of the circumferential direction of the inner circumferential surface 6 of the housing 2d. Other structures and functions are the same as in the second example.

[0092] [Fifth Case]

[0093] use Figure 9 A fifth example of an embodiment of the present invention will be described.

[0094] In the torque measuring device 1e of this example, the rolling bearing 20b that supports the rotating shaft 3 for free rotation relative to the housing 2b is a needle roller bearing, which has an outer ring 21b and a plurality of needle rollers 39 serving as rolling elements. The outer ring 21b has an outer ring track 24a formed by a cylindrical surface on its inner circumferential surface at the axial intermediate portion. The plurality of needle rollers 39 are arranged to roll freely between the outer ring track 24a and the outer circumferential surface of the intermediate shaft portion 8 constituting the rotating shaft 3 while being held by the retainer 30a.

[0095] In this example, the magnetostrictive sensor 4d includes: a support ring 31a that supports and is fixed to one axial end of the outer ring 21b; and a magnetic detection element 40, such as a Hall element serving as a detection unit, which is fixed to the support ring 31a.

[0096] The support ring 31a is made of metal and is integrally formed into a ring shape. The support ring 31a includes: a fitting cylindrical portion 32a, which is interference-fitted into one axial end of the outer ring 21b; and an annular support portion 44, which engages with the one axial end of the fitting cylindrical portion 32a, and whose other axial side abuts against the one axial side of the outer ring 21b. The support portion 44 has a recess 45 that opens only radially inward and extends continuously throughout the entire circumference.

[0097] The magnetic detection element 40 is fixed in a circumferential position within the recess 45 of the support ring 31a. In this state, the magnetic detection element 40 is positioned close to the outer peripheral surface of the intermediate shaft portion 8 of the rotating shaft 3, which serves as the magnetostrictive effect portion.

[0098] The intermediate shaft portion 8 of the rotating shaft 3 is magnetized in the circumferential direction.

[0099] In this example, similarly, if a torque is applied to the rotating shaft 3, torsional deformation occurs in the intermediate shaft portion 8, and the permeability of the intermediate shaft portion 8 changes due to the inverse magnetostrictive effect. Specifically, tensile stress relative to the axial direction at 45° and compressive stress relative to the axial direction at -45° are applied to the intermediate shaft portion 8. Consequently, the permeability of the intermediate shaft portion 8 changes in each direction due to the inverse magnetostrictive effect. In this example, through this change in permeability, the magnetization of the intermediate shaft portion 8 tilts from the circumferential direction to the axial direction. As a result, leakage flux is generated outside the intermediate shaft portion 8, which passes through the magnetic detection element 40, thereby changing the voltage of the magnetic detection element 40. Therefore, the torque transmitted by the rotating shaft 3 can be measured using the voltage of the magnetic detection element 40. Other structural and operational effects are the same as in the second example.

[0100] [Sixth Case]

[0101] use Figure 10 A sixth example of an embodiment of the present invention will be described.

[0102] In this example, the torque measuring device 1f, in addition to the housing 2b, the rotating shaft 3, and the magnetostrictive sensor 4d, also includes a one-way clutch 41. This one-way clutch 41 allows the rotating shaft 3 to rotate relative to the housing 2b in a predetermined direction, and prevents the rotating shaft 3 from rotating relative to the housing 2b in the opposite direction. In this example's construction, the rotating shaft 3 is also coaxially arranged with the inner circumferential surface 6 of the housing 2b, and is supported by a rolling bearing (not shown) to allow it to rotate relative to the housing 2b.

[0103] The one-way clutch 41 is configured to include an outer ring 42 disposed around the rotating shaft 3 and embedded in the housing 2b. The magnetostrictive sensor 4d is supported on the housing 2b via the outer ring 42. In this example, an anti-rotation structure is constructed to prevent the magnetostrictive sensor 4d from rotating relative to the housing 2b by engaging a portion of a protrusion 26 that protrudes radially outward from a portion of the circumferential direction of the outer ring 42 with a portion of the housing 2b.

[0104] More specifically, in this example, the one-way clutch 41 includes an outer ring 42, a plurality of engaging members 43, a retainer (not shown), and a force-applying spring. The outer ring 42 is interference-fitted into the inner circumferential surface 6 of the housing 2b. The plurality of engaging members 43 are each composed of a wedge. The plurality of engaging members 43 are disposed between the inner circumferential surface of the axially intermediate portion of the outer ring 42, which is a cylindrical surface, and the outer circumferential surface of the intermediate shaft portion 8 of the rotating shaft 3. The retainer holds the plurality of engaging members 43. The force-applying spring is engaged with the retainer and elastically presses the engaging members 43 in the direction of engaging with the inner circumferential surface of the axially intermediate portion of the outer ring 42 and the outer circumferential surface of the intermediate shaft portion 8. In addition, the engaging members can also be composed of rollers. When the engaging members are composed of rollers, the inner circumferential surface of the axially intermediate portion of the outer ring is formed by a cam surface that is a concave-convex surface in the circumferential direction.

[0105] When the rotating shaft 3 tends to rotate relative to the housing 2b in a predetermined direction, the engagement of the plurality of engaging members 43 with the inner circumferential surface of the axially intermediate portion of the outer ring 42 and the outer circumferential surface of the intermediate shaft portion 8 is released, allowing the rotating shaft 3 to rotate relative to the housing 2b. Conversely, when the rotating shaft 3 tends to rotate relative to the housing 2b in the opposite direction to the predetermined direction, the plurality of engaging members 43 engage with the inner circumferential surface of the axially intermediate portion of the outer ring 42 and the outer circumferential surface of the intermediate shaft portion 8, preventing the rotating shaft 3 from rotating relative to the housing 2b.

[0106] In this example, the outer ring 42 has a protrusion 26 that projects radially outward from the outer peripheral surface. Therefore, the radially inner portion of the metal pin 28 is pressed into a recess 27 located at a circumferential location on the axial side of the outer peripheral surface of the outer ring 42. The radially outer portion of the pin 28 constitutes the protrusion 26.

[0107] With the outer ring 42 interference-fitted into the inner circumferential surface 6 of the outer casing 2b, the protrusion 26 engages with an axially elongated groove 19a provided at a location on the circumferential surface 6 of the outer casing 2b. That is, in this example, the aforementioned anti-rotation structure is achieved by engaging the protrusion 26 with the groove 19a, which is part of the outer casing 2b.

[0108] In this example, the magnetostrictive sensor 4d is integrally formed with the one-way clutch 41 by being mounted on the outer ring 42 of the one-way clutch 41. The magnetostrictive sensor 4d includes: a support ring 31a that supports and is fixed to one axial end of the outer ring 42; and a magnetic detection element 40, such as a Hall element, which serves as a detection part, and is fixed to the support ring 31a.

[0109] The support ring 31a is made of metal and is integrally formed into a circular ring. The support ring 31a includes: a fitting cylindrical portion 32a, which is interference-fitted into one axial end of the outer ring 42; and a circular support portion 44, which engages with the one axial end of the fitting cylindrical portion 32a, and whose other axial side abuts against the one axial side of the outer ring 42. The support portion 44 has a recess 45 that opens only radially inward and extends continuously throughout the entire circumference.

[0110] The magnetic detection element 40 is fixed in a circumferential position within the recess 45 of the support ring 31a. In this state, the magnetic detection element 40 is positioned close to the outer circumferential surface of the intermediate shaft portion 8 of the rotating shaft 3, which serves as a magnetostrictive effect portion. Furthermore, the intermediate shaft portion 8 of the rotating shaft 3 is magnetized in the circumferential direction.

[0111] In this example, the magnetostrictive sensor 4d is integrated with the one-way clutch 41. Therefore, the torque measuring device 1f can be easily assembled, and the magnetostrictive sensor 4d can be configured with less space.

[0112] The magnetostrictive sensor 4d is supported on the housing 2b by an outer ring 42 embedded within the housing 2b. Therefore, the distance, or gap, between the magnetic sensing element 40 (the sensing unit) and the outer peripheral surface of the intermediate shaft portion 8 (the magnetostrictive effect unit) can be appropriately managed. From this perspective, it is easier to ensure the accuracy of torque measurement.

[0113] In this example, an anti-rotation structure, formed by engaging the protrusion 26 with the groove 19a, prevents both the outer ring 42 from rotating relative to the housing 2b and the magnetostrictive sensor 4d relative to the housing 2b. Therefore, it avoids undesirable situations such as the unshown wiring harness connected to the magnetostrictive sensor 4d being pulled due to the rotation of the outer ring 42 relative to the housing 2b, i.e., creep. Other structural features and effects are the same as in the first example.

[0114] [Seventh Case]

[0115] use Figure 11 A seventh example of an embodiment of the present invention will be described.

[0116] In the torque measuring device 1g of this example, the outer ring 42a constituting the one-way clutch 41a has a cylindrical support portion 46 at one end on the axial side, the outer diameter of which is smaller than the outer diameter of the portion adjacent to the other axial side. In the implementation of the present invention, the outer diameter of the support portion can also be equal to the outer diameter of the portion adjacent to the other axial side.

[0117] In this example, a magnetostrictive sensor 4e, which includes a magnetic detection element 40 as a detection unit, is supported on the radially inner side of the support portion 46. Other structures and effects are the same as in the sixth example.

[0118] The above-described embodiments and reference examples can be appropriately combined and implemented without creating contradictions.

[0119] Explanation of symbols

[0120] 1, 1b, 1c, 1d, 1e, 1f, 1g, 1A—Torque measuring device; 2, 2b, 2c, 2d, 2A—Housing; 3—Rotating shaft; 4, 4b, 4c, 4d, 4e, 4A—Magnetostrictive sensor; 6, 6a—Inner circumferential surface; 8—Intermediate shaft; 9, 9b, 9A—Bracket; 10—Coil; 11—Back yoke; 12, 12b—Main body; 14a, 14A—Terminal portion; 16—Wire harness; 18—Protrusion; 19, 19a, 19b—Slot; 20, 20a, 20b—Rolling bearing; 21, 21a, 21b—Outer ring; 2 2—Inner ring, 23—Ball, 24, 24a—Outer ring track, 25—Small diameter section, 26—Protrusion, 27—Recess, 28—Pin, 29—Inner ring track, 30, 30a—Retainer, 31, 31a—Support ring, 32, 32a—Matching cylinder section, 33—Side plate section, 34—Support cylinder section, 35—Outer peripheral surface, 36—Flat section, 37—Flat section, 38—Protrusion, 39—Needle roller, 40—Magnetic detection element, 41, 41a—One-way clutch, 42, 42a—Outer ring, 43—Activating element, 44—Support section, 45—Recess, 46—Support section.

Claims

1. A torque measuring device, characterized in that, have: The outer casing does not rotate during use; A rotating shaft, supported to rotate relative to the aforementioned housing, has a magnetostrictive effect portion disposed on the outer peripheral surface of the rotating shaft, the permeability of which varies according to the transmitted torque; and A magnetostrictive sensor has a detection unit that is arranged close to the aforementioned magnetostrictive effect portion in a radially opposed manner and causes the voltage to change in response to a change in the permeability of the aforementioned magnetostrictive effect portion, and is supported on the aforementioned housing. The torque measuring device described above has an anti-rotation structure that prevents the magnetostrictive sensor from rotating relative to the housing. The aforementioned magnetostrictive sensor is embedded in the inner circumferential surface of the aforementioned housing without radial wobble. The aforementioned anti-rotation structure is constructed by engaging a protrusion that extends radially outward from a portion of the circumference of the magnetostrictive sensor with a slot that extends axially and extends through the front-rear direction of the housing on the inner circumferential surface of the housing. The end of the wire harness is connected to the axial side of the aforementioned protrusion, and a portion of the wire harness is disposed inside the aforementioned groove.

Images