Sensor system and temperature compensation method thereof

Abstract

A sensor system includes a first sensor, a second sensor, and a controller in electrical communication with the first sensor and the second sensor. The controller includes a memory for storing data, the memory being configured to store an offset profile of at least one output of the first sensor. The offset profile includes a plurality of offset values ​​calculated using a measured output of the first sensor determined while maintaining a position of a conductive material and varying a temperature of an ambient atmosphere.

Description

Technical Field

[0001] The presently disclosed subject matter relates to sensor systems and, more particularly, to sensor systems and methods of temperature compensation thereof. Background Art

[0002] An Electric Differential Lock (EDL) is an actuator that controls the operation of a differential. A differential improves a vehicle's traction by providing equal torque to each wheel located at the end of its axle assembly. As is well known, an EDL is positioned in an engaged state using an electromagnetic solenoid. The electromagnetic solenoid actuates a piston which in turn moves a locking gear located within the differential. A sensor may be used to measure the engagement and disengagement of the locking gear from the differential. Typically, the sensor measures the engagement and disengagement of the locking gear by sensing the axial position of the locking gear.

[0003] One such type of sensor is an eddy current sensor. An eddy current sensor uses an induction coil to generate a high frequency alternating magnetic field. If a conductive material (e.g., a locking gear) is brought close to the eddy current sensor, eddy currents will form within the conductive material. These eddy currents produce a magnetic field that is opposite to the magnetic field of the wire coil. The amplitude of this opposing magnetic field is proportional to the distance of the locking gear from the wire coil. The net effect is a reduction in the apparent inductance of the wire coil, which is proportional to the distance of the locking gear from the wire coil. The inductance of the wire coil is measured in the eddy current sensor. The microcontroller uses the measured inductance to calculate the distance of the locking gear from the wire coil.

[0004] It is desirable to produce a sensor system and a temperature compensation method thereof which improve the accuracy and efficiency of the sensor system. Summary of the invention

[0005] In coordination and consistency with the present disclosure, a sensor system and method for temperature compensation thereof have surprisingly been discovered that improve the accuracy and efficiency of the sensor system.

[0006] In one embodiment, a sensor system includes: a first sensor configured to generate at least one output; and a controller electrically communicating with the first sensor, the controller including a memory for storing data, the memory configured to store at least one offset value of at least one output of the first sensor.

[0007] As aspects of certain embodiments, the first sensor is an eddy current sensor.

[0008] As aspects of certain embodiments, at least one output of the first sensor indicates a distance of the conductive material from the first sensor.

[0009] As aspects of certain embodiments, at least one output of the first sensor is a frequency signal.

[0010] As aspects of certain embodiments, at least one offset value is a difference between at least one measured output of the first sensor and a predetermined output of the first sensor.

[0011] As aspects of certain embodiments, at least one measurement output of the first sensor is determined while maintaining a position of the conductive material and varying a temperature of the surrounding atmosphere.

[0012] As aspects of certain embodiments, the predetermined output of the first sensor is a frequency signal at an ideal ambient temperature.

[0013] As aspects of certain embodiments, further comprising a second sensor in electrical communication with the controller, wherein the second sensor is configured to measure a temperature of the desired input location.

[0014] As aspects of certain embodiments, the second sensor is a thermistor.

[0015] In another embodiment, a method for temperature compensation of a sensor system comprises the following steps: providing a first sensor configured to generate an output; providing a controller in electrical communication with the first sensor, wherein the controller includes a memory for storing data; providing an offset profile stored in the memory of the controller, wherein the offset profile provides a plurality of offset values ​​for the output of the first sensor; transmitting the output of the first sensor to the controller; and calculating a temperature compensated output of the first sensor by adjusting the output of the first sensor by one of the offset values ​​stored in the memory of the controller.

[0016] As aspects of certain embodiments, further comprising the step of providing a second sensor in electrical communication with the controller, wherein the second sensor is configured to measure a temperature of the desired input location.

[0017] As aspects of certain embodiments, one of the offset values ​​is obtained from an offset profile based on an output of the first sensor and a measured temperature from a second sensor.

[0018] As aspects of certain embodiments, further comprising the step of comparing the temperature compensated output of the first sensor to a calibrated value of the output of the first sensor to determine a state of a differential of the vehicle.

[0019] As aspects of certain embodiments, the offset value is calculated using a measured output of the first sensor determined while maintaining a position of the conductive material and varying a temperature of the surrounding atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are included as part of the specification. The accompanying drawings described herein illustrate embodiments of the subject matter of the present disclosure and illustrate selected principles and teachings of the present disclosure. However, the accompanying drawings do not illustrate all possible implementations of the subject matter of the present disclosure and are not intended to limit the scope of the present disclosure in any way.

[0021] Figure 1 schematically depicts a vehicle according to an embodiment of the presently disclosed subject matter;

[0022] Figure 2 is a cross-sectional view of a differential according to an embodiment of the presently disclosed subject matter;

[0023] Figure 3 is based on Figure 2 a segmented cross-sectional view of a portion of a differential of , wherein the differential is in an unlocked state;

[0024] Figure 4 is based on Figure 2 A partial cross-sectional view of a portion of a differential of , wherein the differential is in a locked state;

[0025] Figure 5 is a perspective view of a portion of an axle assembly according to an embodiment of the presently disclosed subject matter, wherein a portion of a differential carrier is not shown;

[0026] Figure 6 is based on Figure 2 A partial cross-sectional view of a portion of a differential, wherein the differential case is not shown;

[0027] Figure 7 is a partial cross-sectional view of a portion of a differential having a lateral sensor according to an embodiment of the presently disclosed subject matter;

[0028] Figure 8 is a flow chart of a method for temperature compensation of a sensor system according to an embodiment of the presently disclosed subject matter; and

[0029] Fig. 9 Is used according to Figure 8 A flow chart of a sensing method of a sensor system. DETAILED DESCRIPTION

[0030] It should be understood that, except for situations that are explicitly designated to the contrary, the subject matter disclosed herein may assume a variety of alternative orientations and step sequences. It will also be understood that the specific components and systems illustrated in the drawings and described in the following specification are only exemplary embodiments of the inventive concepts defined herein. Therefore, unless otherwise explicitly indicated, specific dimensions, directions, or other physical features associated with the disclosed embodiments are not considered to be limiting. In addition, although they may not be, similar elements in the various embodiments described herein may be referred to collectively by similar reference numerals in this part of the application.

[0031] Figure 1 An all-wheel drive (AWD) vehicle 10 according to the subject matter currently disclosed is shown. The vehicle 10 can be any desired vehicle type, such as a conventional fuel-powered vehicle, an electric vehicle, and an electric hybrid vehicle. In one embodiment, the vehicle 10 may include a powertrain arrangement 12 having a power source 14. The power source 14 can be, but is not limited to, an internal combustion engine or an electric motor. The powertrain arrangement 12 may also include a transmission 16 having an input that is drivably connected to the power source 14 and an output that is drivably connected to a transfer case 18. The transfer case 18 includes a first output that is continuously drivably connected to a rear drive unit 19 and a second output that is selectively drivably connected to a front drive unit 20. The rear drive unit 19 or the front drive unit 20 may further include an axle assembly 21 that is drivably connected to a wheel set 22.

[0032] like Figure 2-Figure 6 As shown, the axle assembly 21 includes a differential 23 having a differential case 24. When the AWD function is not needed, the differential 23 improves fuel economy by disconnecting the AWD driveline components. The differential case 24 is mounted for rotation within the differential carrier 10 via a pair of bearings 34, 36. In some embodiments, the differential 23 can be Figure 1 The method disclosed herein can be used in an axle assembly 21 of the vehicle 10 shown. However, the method used with the differential 23 as disclosed herein can also be used with other movable parts. The method can have applications in both light and heavy vehicles, as well as passenger, commercial and off-highway vehicles. Further, the method can also have industrial, locomotive, military, agricultural and aerospace applications, as well as applications in passenger, electric and autonomous or semi-autonomous vehicles.

[0033] like Figure 5 As shown, the ring gear 40 can be coupled to the differential case 24. In an embodiment, the ring gear 40 can be integrally formed with the differential case 24. In another embodiment, as shown in FIG. Figure 2 and Figure 5As shown, the differential case 24 may include a ring gear flange 42. The ring gear flange 42 may define a plurality of fastener holes (not shown) disposed circumferentially therearound and formed therein. Mechanical fasteners 44 (such as bolts) may be disposed through the fastener holes into the first side of the ring gear 40 to couple the differential case 24 and the ring gear 40.

[0034] The ring gear 40 includes a plurality of teeth (not depicted) on a second side 48 of the ring gear 40. The ring gear teeth extend circumferentially and continuously around the second side 48. The ring gear teeth mesh with a set of teeth on a pinion gear 49, such as Figure 1 As shown. Pinion 49 is coupled to transfer case 18. Pinion 49 receives torque from power source 14.

[0035] like Figure 2 As shown, in an embodiment, the pinion shaft 50 is disposed within the differential case 24. In an embodiment, an additional pinion shaft 50A may be located at a position that is 90 degrees to the pinion shaft 50 and transverse to the pinion shaft 50. The pinion shafts 50, 50A may also be referred to as spider shafts. The pinion shaft 50 is connected to the differential case 24. In an embodiment, the pinion shaft 50 may extend into the differential case 24 so that the pinion shaft 50 may be fixed therein. Therefore, the pinion shaft 50 rotates with the differential case 24.

[0036] A first differential pinion 52 is located at one end of the pinion shaft 50 and a second differential pinion 54 is located at the other end of the pinion shaft 50. The first differential pinion 52 and the second differential pinion 54 each include a plurality of teeth 56, 58 extending circumferentially around the first differential pinion 52 and the second differential pinion 54. As described above, if an additional pinion shaft 50A is provided, additional differential pinions may be located thereon. Figure 2 As shown, the third differential pinion 52A is disposed on the additional pinion shaft 50A. The teeth 56, 58 of the first differential pinion 52 and the second differential pinion 54 mesh with the teeth 60, 62 on the first differential side gear 64 and the second differential side gear 66. The differential side gear teeth 60, 62 extend circumferentially around the first differential side gear 64 and the second differential side gear 66.

[0037] The first differential side gear 64 and the second differential side gear 66 include hollow inner portions 68, 70, respectively. The hollow inner portions 68, 70 may each include radially extending splines 72, 74. The splines 72 of the first differential side gear 64 may engage with splines on a first axle half shaft (not depicted) to transfer rotation to the shaft. The splines 74 of the second differential side gear 66 may engage with splines on a second axle half shaft (not depicted) to transfer rotation to the shaft. The first axle half shaft and the second axle half shaft extend from the differential case 24 and through the axle assembly 21 to the wheel set 22.

[0038] exist Figure 2-Figure 4 and Figure 6 In some of the embodiments shown, the differential 23 may be an electric differential lock (EDL). EDLs may be used in applications in a variety of industries, including automotive, aerospace, industrial automation equipment, and instrumentation applications. In one embodiment, the subject matter disclosed herein may be used in Figure 1 1. In certain embodiments, the second differential side gear 66 can include a set of locking teeth 76 disposed on an axially outer side surface 78. In an embodiment, the locking teeth 76 are integrally formed with the second differential side gear 66. The locking teeth 76 extend circumferentially around the axially outer side surface 78.

[0039] like Figure 2-Figure 6 As shown, the actuator assembly 80 can be mounted on the second differential case flange 28. The actuator assembly 80 is coupled to the differential carrier 10 such that the actuator assembly 80 is fixed and does not rotate relative to the differential carrier 10. In an embodiment, the actuator assembly 80 includes at least one radially extending pin 82. The pin 82 is received in a slotted flange 84 fixedly connected to the differential carrier 10. Receiving the pin 82 in the slotted flange 84 prevents the actuator assembly 80 from rotating with the differential case 24.

[0040] In an embodiment, the actuator assembly 80 includes a solenoid actuator. The actuator assembly 80 may include a housing 88, an electromagnetic coil 90, and an armature 92. In an embodiment, the housing 88 may have an annular geometry such that the inner diameter of the housing 88 is coupled to a sleeve 89. The sleeve 89 may be coupled to the differential case flange 28 such that the sleeve 89 may rotate relative to the differential case 24.

[0041] The electromagnetic coil 90 may be molded or disposed in a resin and disposed within the housing 88. The electromagnetic coil 90 may include a ring shape having a hollow interior. The electromagnetic coil 90 is electrically connected to a power source (not depicted), such as but not limited to a battery, which can selectively power the electromagnetic coil 90. The power source may also be connected to a controller (not shown) that determines when to power the electromagnetic coil 90. In an embodiment, the controller may be mounted to an inner portion of the housing 88. In another embodiment, the controller may be mounted to a radially outer surface of the actuator housing 88. In yet another embodiment, the controller may be mounted to an outer side surface of the housing 88.

[0042] refer to Figure 2-Figure 4 In an embodiment, the armature 92 may be a generally hollow cylinder disposed radially inward from the electromagnetic coil 90. In some embodiments, at least a portion of the armature 92 is continuously radially surrounded by the electromagnetic coil 90. The armature 92 may be formed of a ferromagnetic material. An annular spacer 94 is disposed axially adjacent to the armature 92 and disposed on the inner side thereof. The annular spacer 94 may be made of a polymer material.

[0043] When electricity is applied to the electromagnetic coil 90, the electromagnetic coil 90 generates a magnetic field that extends through the housing 88 and the armature 92. The magnetic field extends into the armature 92, causing the armature 92 to move in an axial direction. In an embodiment, the armature 92 does not rotate.

[0044] In an embodiment, Figure 2-Figure 4 As shown, the sensor plate 124 can be positioned axially adjacent to the inner side of the spacer 94. The sensor plate 124 can also be disposed radially at least partially around the spacer 94. In an embodiment, the sensor plate 124 abuts against the plurality of legs 100 of the locking gear 96. Figure 6 As more clearly shown in FIG. 1 , a locking gear leg 100 extends axially outward from a generally disc-shaped main body portion 102 of the locking gear 96. The leg 100 is located on an axially outer side 104 of the main body portion 102. The locking gear main body portion 102 includes a radially outer surface 106. The radially outermost surface of the leg 100 may extend from the outer surface 106 such that the outer surface 106 and the radially outermost surface of the leg 100 have the same outer diameter.

[0045] In an embodiment, the legs 100 may be circumferentially positioned so that they are separated from each other by arcs of equal length. The legs 100 may taper from the body portion 102 to their ends. In an embodiment, the locking gear body portion 102 may be located entirely within the differential case 24. The locking legs 100 may be primarily located within the differential case 24; however, the ends of the legs 100 extend axially through differential case apertures 108 dedicated to each leg 100. The ends of the legs 100 extend to the exterior of the differential case 24 to contact the armature 92, the spacer 94, or the sensor plate 124.

[0046] A plurality of teeth 112 are located on the axially inner side 110 of the locking gear body portion 102. The teeth 112 extend circumferentially around the locking gear body portion inner side 110. The locking gear teeth 112 are complementary to and selectively mesh with the second differential side gear locking teeth 76.

[0047] In an embodiment, the locking gear 96 defines an annular groove 118 located in its inner side surface. The locking gear groove 118 can be axially aligned with a groove 121 on the axial outer surface 78 of the second differential side gear 66. A biasing member 122 can be at least partially located within the locking gear groove 118 and the second differential side gear groove 121. When the actuator assembly 80 is in the disengaged position, the biasing member 122 biases the locking gear 96 axially away from the second differential side gear 66. The biasing member 122 can be, but is not limited to, a spring, a plurality of springs, one or more Bellville-type washers, or one or more wave springs.

[0048] Being located within the differential case 24, it will be appreciated that the locking gear 96 rotates with the differential case 24. The locking gear 96 is preferably one-piece, unitary, and integrally formed of a strong material such as metal. The locking gear 96 may be made of an electrically conductive material.

[0049] In an embodiment, Figure 2-Figure 4 As shown, the sensor plate 124 can be coupled to the locking gear 96. The sensor plate 124 can include a generally disk-shaped geometry and have a radially inner surface 126, a radially outer surface 128, an axially inner surface 130, and an axially outer surface 132. The axially inner surface 130 and the axially outer surface 132 can be substantially parallel and equally spaced from each other. Figure 2-Figure 4 In the illustrated embodiment, the axially inner surface 130 and the axially outer surface 132 define therebetween a substantially constant thickness of the sensor plate 124. The sensor plate 124 may have a radial dimension that is much greater than its axial dimension. In other words, the thickness of the plate 124 may be much less than the distance between the radially inner surface 126 and the radially outer surface 128.

[0050] like Figure 2-Figure 4 As shown, the sensor plate 124 may include a lug 134 extending axially or laterally to the axial inner surface 130. The radial inner surface of the lug 134 may be adjacent to the sensor plate radial inner surface 126. The lugs 134 may be regularly spaced from each other around the circumference of the radial inner surface 126. In an embodiment, a portion of the lug 134 may be disposed in a radially extending annular groove 135 defined by the locking gear 96 to frictionally lock the sensor plate 124 to the locking gear 96. In one embodiment, the groove 135 is disposed radially inward of the locking gear leg 100.

[0051] At least a portion of the sensor plate 124 is substantially located outside of the differential case 24; however, the sensor plate tab 134 may extend into the differential case 24. More specifically, the tab 134 may extend at least partially through the differential case aperture 108. In other embodiments (not depicted), the sensor plate 124 may be coupled to the locking gear 96 in other ways, such as, but not limited to, mechanical fasteners. Thus, in certain embodiments, the armature 92 or the annular spacer 94 may not directly contact the sensor plate 124, but rather the armature 92 or the annular spacer 94 may directly contact the locking gear 96.

[0052] In an embodiment, the body portion 136 of the sensor plate 124 may include a substantially continuous surface. Figure 6 As shown, the sensor plate body portion 136 may have one or more holes extending radially therethrough. The holes may allow fluids (such as air and lubricants) to flow within the differential carrier 10. In an embodiment (not depicted), the sensor plate 124 may include multiple holes with small diameters, rather than fewer holes with relatively large diameters. The sensor plate 124 coupled to the locking gear 96 moves axially with the locking gear 96 and rotates with the locking gear 96. Further, the sensor plate 124 may include a conductive material.

[0053] The housing 88 includes an inner surface 138, an outer surface 140, and a radially outer surface 142. The radially outer surface 142 can be curvilinear and define a substantially constant outer diameter of the annular housing 88. The inner surface 138 and the outer surface 140 define a substantially constant distance or thickness therebetween. The inner surface 138 and the outer surface 140 are substantially parallel to each other. The inner surface 138 and the outer surface 140 can extend substantially transversely to a rotation axis 144 of the differential case 24.

[0054] Similarly, the inner and outer surfaces 130, 132 of the sensor plate 124 may extend substantially transverse to the axis of rotation 144 of the differential case 24. The inner and outer surfaces 130, 132 of the sensor plate 124 are substantially parallel to the inner and outer surfaces 138, 140 of the housing 88.

[0055] In an embodiment, the sensor system 152 (eg, Figure 1In one embodiment, the position sensor 148 (shown in FIG. 1 ) may be disposed on the inner surface 138 of the housing 88. In another embodiment, the position sensor 148 may be disposed in a groove in the inner surface 138 of the housing 88. The position sensor 148 may be located at any radial position along the inner surface 138. In one embodiment, the position sensor 148 is located near a radially outward portion of the inner surface 138. In an embodiment, more than one position sensor 148 may be located at more than one radial position on the inner surface 138. In another embodiment, the position sensor 148 may include a ring disposed on the inner surface 138.

[0056] In yet another embodiment, Figure 7 As shown, the position sensor 148 can be positioned transversely to the sensor plate 124. For example, the position sensor 148 can be positioned radially outward from the sensor plate 124. In this embodiment, the position sensor 148 is fixed at a constant distance from the radially outer surface 128 of the sensor plate 124.

[0057] The lateral position sensor 148 operates in the same manner as described herein. In one embodiment, the lateral position sensor 148 senses the percentage by which it is covered by the sensor plate radially outer surface 128 so that the microcontroller can determine the position of the sensor plate 124 based on the coverage percentage.

[0058] In yet another embodiment, Figure 7 As shown, first lateral position sensor 148 may be located radially above sensor plate 124, and second lateral position sensor 148A may be located radially below sensor plate 124. "Above" and "below" refer to the first and second sensors being fixed radially relative to each other.

[0059] In another embodiment (not depicted), the first position sensor 148 may be positioned axially adjacent to the sensor plate inner surface 130 and the second position sensor 148 may be positioned axially adjacent to the sensor plate outer surface 132. Thus, the first sensor 148 and the second sensor 148 are located on either side of the sensor plate 124; the first position sensor 148 faces the sensor plate inner surface 130 and the second position sensor 148 faces the sensor plate outer surface 132. The second position sensor 148 may be radially aligned with the first sensor. In other words, the first sensor 148 and the second sensor 148 may be located at the same distance from the differential rotating shaft 144. In this embodiment, the data from the first sensor 148 and the second sensor 148 may be used in combination or separately by the controller microprocessor. When used separately, the data may be compared as a double check of the position of the sensor plate 124. When used together, the data may be used to detect any change in the distance between the sensor plate 124 and the first sensor 148 and the second sensor 148.

[0060] Various types of sensors 148 may be used. Some possible sensors 148 are briefly outlined below, but the device is not limited to these sensors 148 or the operations described below.

[0061] In one embodiment, the position sensor 148 can be a two-wire sensor. A voltage (e.g., about 4-9 volts) is provided to the position sensor 148, and the current consumption is fixed. Depending on the state of the system, the current can be, for example, 7 mA or 14 mA. For example, one current can be associated with the locked state of the differential 23, and the other current can be associated with the unlocked state of the differential 23.

[0062] In another embodiment, the position sensor 148 may be a three-wire sensor. This embodiment may emit an output such as a fixed frequency signal of about 250 Hz, but other frequencies may be used. The duty cycle of the output may vary with the position of the sensor plate 124 or the locking gear 96. The output may be a continuous signal relative to the position of the sensor plate 124 or the locking gear 96, or the output may be a signal with a fixed value based on a specific position of the sensor plate 124 or the locking gear 96. For example, when the sensor plate 124 or the locking gear 96 is closest to the position sensor 148, the output may be a signal indicating 10%, and when the sensor plate 124 or the locking gear 96 is farthest from the position sensor 148, the output may be a signal indicating 90%. In addition, the output may include a percentage signal that may be fixed for a specific position at each instance between the closest position and the farthest position. In yet another embodiment of the position sensor 148, the output may be a signal that is fixed at a specific amount at the closest position (unlocked) and fixed at a different specific amount at the farthest position (locked) without other signals.

[0063] In another embodiment, the output of the position sensor 148 may be a serial digital signal. For example, the output may be a serial digital signal, such as a UART-type or LIN bus output with a predetermined baud rate, such as, for example, 9600 baud.

[0064] In any of the above embodiments, the position sensor 148 can be an inductive sensor including an inductive coil 149. The sensor inductive coil 149 can include, but is not limited to, a bobbin-wound length of wire, a printed circuit board (PCB) trace spiral, or a metal printed trace (if the inside surface is not conductive). In an embodiment, the inductive coil 149 can be substantially planar and rigid. In another embodiment, the inductive coil 149 can be flexible, non-planar, and / or curvilinear.

[0065] In a planar and rigid embodiment, the induction coil 149 may be disposed in or on a substrate. The substrate may be the housing 88, or a material attached to the housing 88 in which the position sensor 148 is embedded.

[0066] In flexible, non-planar and curvilinear embodiments, the induction coil 149 may be similarly disposed in or on a substrate. The substrate may be a flexible material that may conform to a curved surface. In one embodiment, the substrate may be a flexible printed circuit board. Alternatively, all or a portion of the induction coil 149 may be bent or zigzag to give it a curvilinear shape. The induction coil 149 may then be located on a curvilinear shape, such as the differential case 24 or the differential carrier 10 or a structure connected to either.

[0067] When a conductive material is nearby, the induction coil 149 generates a high frequency alternating magnetic field. The magnetic field causes eddy currents to form in the conductive material. The eddy currents generate a magnetic field in the conductive material that is opposite to the magnetic field in the induction coil 149. The amplitude of the eddy currents in the conductive material measured by the position sensor 148 is proportional to the distance of the conductive material from the position sensor 148. The position sensor 148 is configured to generate an output indicating the distance of the conductive material from the position sensor 148 and transmit the output to, for example, a sensor system 154 (e.g., a sensor system 154) that is in electrical communication with the position sensor 148. Figure 1 In some embodiments, the controller 150 may be located on or within the actuator assembly housing 88. However, in other embodiments, the controller 150 may be located as desired. Figure 1 At other suitable locations within the vehicle 10 as shown in FIG.

[0068] In an embodiment, the conductive material may be the sensor plate 124. In another embodiment, the position sensor 148 instead senses the position of the locking gear 96. It will be appreciated that, regardless of whether the position sensor 148 senses the locking gear 96 directly or the sensor plate 124, the position sensor 148 senses the exact position of the locking gear 96. As will be appreciated from the foregoing, the position of the locking gear 96 and / or the sensor plate 124 may be known, so that a reliable determination of whether the differential 23 is in a locked state or an unlocked state may also be reliably known.

[0069] Figure 2 and Figure 3 The differential 23 is shown in an unlocked state. In the unlocked state, the locking gear 96 is not engaged with the second side gear 66. Additionally, the electromagnetic coil 90 is not sufficiently energized to actuate the armature 92. Further, the biasing member 122 biases the locking gear 96 to an axially outboard position.

[0070] When a condition is detected that may require locking of the differential 23, current is provided to the electromagnetic coil 90 in an amount sufficient to cause the electromagnetic coil 90 to generate magnetic flux in the conductive armature 92. Various conditions may exist that may necessitate locking of the differential 23. These conditions may be monitored by one or more vehicle sensors (not depicted).

[0071] The magnetic flux in the armature 92 moves the armature 92 in the axially inner direction. The magnetic flux in the armature 92 is sufficient to overcome the biasing force of the biasing member 122 and move the armature 92. In other words, the axially inner movement of the armature 92 causes the locking gear 96 to axially move in the inner direction. As described above, since the sensor plate 124 is coupled to the locking gear 96, the sensor plate 124 also moves in the axially inner direction.

[0072] Figure 4 The differential 23 is shown in a locked state. In the locked state, the armature 92, the locking gear 96, and the sensor plate 124 move in an axially inboard direction so that the second side gear locking teeth 76 and the locking gear teeth 112 engage with each other. When the second side gear locking teeth 76 and the locking gear teeth 112 are fully engaged, the differential 23 is locked. In the locked state, the second side gear 66 is locked from rotating relative to the differential case 24. This prevents the second side gear 66 from rotating independently of the first side gear 64; instead, the first side gear 64 and the second side gear 66 can only rotate together. The locked state of the differential 23 has the effect of evenly dividing power between the first side gear 64 and the second side gear 66, the two axle half shafts, and the two wheel ends.

[0073] When the locked differential 23 is no longer required, the current to the electromagnetic coil 90 is terminated or reduced. The termination or reduction of power to the electromagnetic coil 90 causes the biasing member 122 to push the locking gear 96 in the axially outboard direction from the second side gear 66. This causes the locking teeth 76 of the second side gear 66 and the teeth 112 of the locking gear 96 to disengage. Once disengaged, the second side gear 66 can rotate relative to the first side gear 64.

[0074] like Figure 1As shown, the sensor system 152 may further include a temperature sensor 154 for measuring and / or estimating a temperature T1 of a desired input location 156 (e.g., a component or fluid of the vehicle 10). It should be understood that additional temperature sensors 154 may be employed to measure temperatures at multiple input locations 156. For example, the desired input location 156 may be a location within the controller 150, a clutch assembly of a rear drive unit, a differential 23, a vehicle engine, an engine fluid, a vehicle transmission, a transmission fluid, ambient air, etc. Various types of controllers or microcontrollers may be employed with the sensor system 152. In the illustrated embodiment, the sensor system 152 facilitates electrical communication between the position sensor 148, the controller 150, and the temperature sensor 154. In certain embodiments, the controller 150 may be in electrical communication with the position sensor 148, the controller 150, and the temperature sensor 154 to facilitate such communication therebetween.

[0075] In certain embodiments, the controller 150 includes a memory 158 for storing data. The memory 158 may be in electrical communication with the position sensor 148 and the temperature sensor 154. The memory 158 may be configured to store an offset profile of the position sensor 148 determined during development of the position sensor 148. The offset profile may be a lookup table that provides an offset value for an output (e.g., a frequency signal) of the position sensor 148 based on temperature.

[0076] In one embodiment, the temperature sensor 154 is a thermistor. For example, various types of thermistors may be used as the temperature sensor 154, such as a negative temperature coefficient (NTC) thermistor and a positive temperature coefficient (PTC) thermistor. For an NTC thermistor, when the temperature increases, the resistance of the NTC thermistor decreases. Conversely, when the temperature decreases, the resistance of the NTC thermistor increases. On the other hand, for a PTC thermistor, when the temperature increases, the resistance of the PTC thermistor increases, and when the temperature decreases, the resistance of the PTC thermistor decreases.

[0077] Unlike other temperature sensors, the temperature sensor 154 can be a non-linear thermistor, meaning that the relationship between resistance and temperature is not a 1:1 ratio. Therefore, the temperature-resistance values ​​plotted on a graph representing this relationship form a curve rather than a straight line. It should be understood that the temperature sensor 154 can have a variety of shapes and sizes, such as, for example, a disc, chip, bead, rod, surface mount. If desired, the temperature sensor 154 can also be encapsulated in epoxy, glass, baked phenolic resin and painted.

[0078] In the illustrated embodiment, a temperature sensor 154 is employed for measuring the temperature T1 of the desired input location 156. The temperature sensor 154 has a minimum amount of current (also commonly referred to as a bias current) flowing therethrough. The controller 150 is configured to cause a power source (not depicted), such as, for example, a battery, to transmit current to the temperature sensor 154. The temperature sensor 154 has a resistance associated with the temperature T1 of the desired input location 156. The current flowing through the temperature sensor 154 converts the resistance of the temperature sensor 154 into a voltage difference measured across the terminals of the temperature sensor 154. The measured voltage difference is then transmitted from the temperature sensor 154 to the controller 150. In certain embodiments, the controller 150 determines the temperature T1 of the desired input location 156 based on at least one determination method, such as using the measured voltage difference and a tolerance band or function of the temperature sensor 154 stored in the memory 158 of the controller 150. The relationship between voltage and resistance is known and can be calculated by utilizing a lookup table or other mathematical relationship between them. Therefore, in certain other embodiments, the determination method of the controller 150 utilizes a lookup table stored in the memory 158 to determine the temperature T1 of the desired input location 156 based on the measured voltage difference of the temperature sensor 154 .

[0079] Reference now Figure 8 , a temperature compensation method 200 for a sensor system 152 according to an embodiment of the presently disclosed subject matter. In certain embodiments, at least one of the position sensor 148 and the controller 150 is calibrated so that the output value of the position sensor 148 is determined to correspond to various switching points (e.g., the engagement point of the second side gear locking tooth 76 and the locking gear tooth 112 associated with the differential 23 in a locked state, and the disengagement point of the second side gear locking tooth 76 and the locking gear tooth 112 associated with the differential 23 in an unlocked state) before operating the vehicle 10. These calibration values ​​are then stored in the memory 158 of the controller 150.

[0080] At step 202, before operating the vehicle 10, the output of the position sensor 148 is measured while maintaining the position of the conductive material and measuring and changing the temperature of the surrounding atmosphere. At step 204, the difference between the measured output of the position sensor 148 at the measured temperature and the value of the predetermined output (i.e., the frequency at the ideal ambient temperature) is calculated. In certain embodiments, the difference between each value of the measured output of the position sensor 148 at the measured temperature and the predetermined output is an offset value of the output of the position sensor 148 at each of the measured temperatures, which represents the effect of temperature on the position sensor 148. Then, at step 206, the offset value is stored in the memory 158 of the controller 150. In this way, at step 208, an offset profile or lookup table of the position sensor 148 is created, which provides calculated offset values ​​for the output of the position sensor 148 across multiple temperatures.

[0081] Reference now Fig. 9 , a sensing method 300 of a sensor system 152 according to an embodiment of the presently disclosed subject matter. At step 302, during operation of the vehicle 10, the position sensor 148 generates an output which indicates a distance of a conductive material from the position sensor 148. At step 304, the output of the position sensor 148 is transmitted to the controller 150.

[0082] At the same time, at step 306, current is supplied from a power source (e.g., a battery) to and through the temperature sensor 154, thereby generating a resistance. At step 308, the resistance of the temperature sensor 154 is then converted to a measured voltage difference across the terminals of the temperature sensor 154, which represents the temperature T1 of the desired input location 156. At step 310, the measured voltage difference is then transmitted to the controller 150 of the sensor system 152 to determine the temperature T1 of the desired input location 156 using any suitable determination method as desired. At step 312, the temperature T1 of the desired input location 156 is used to obtain an associated offset value for the output of the position sensor 148 from an offset profile stored in the memory 158 of the controller 150. Thereafter, at step 314, the temperature compensated output of the position sensor 148 is then calculated by subtracting the associated offset value for the output of the position sensor 148 of step 312 from the output of the position sensor 148 generated by the position sensor 148 at step 302. Then, at step 316 , the controller 150 utilizes the temperature compensated output of the position sensor 148 and compares the temperature compensated output to a calibrated value of the output of the position sensor 148 to determine the state of the differential 23 (ie, locked or unlocked state).

[0083] It should be understood that the sensing method 300 of the position sensor 148 may be repeated as needed. In certain embodiments, the sensing method 300 of the position sensor 148 is repeated continuously. However, in other specific embodiments, the sensing method 300 of the position sensor 148 may be repeated periodically at predetermined intervals if desired.

[0084] Although various embodiments have been described herein, it should be understood that they are presented by way of example and not limitation. Those skilled in the relevant art will appreciate that the disclosed subject matter may be implemented in other specific forms without departing from the spirit and essential characteristics of the present invention. Therefore, the above embodiments are considered to be illustrative in all aspects and not restrictive.

Claims

1. A sensor system for an electric differential, comprising: a first sensor positioned radially outward from a sensor plate coupled to a locking gear of the electric differential, the first sensor configured to generate at least one output, the at least one output of the first sensor indicating a distance of the locking gear of the electric differential from the first sensor; as well as a controller in electrical communication with the first sensor, the controller comprising a memory for storing data, the memory being configured to store at least one offset value of the at least one output of the first sensor, wherein the at least one offset value is a difference between at least one measured output of the first sensor and a predetermined output of the first sensor, wherein the at least one measurement output of the first sensor is determined while maintaining the position of the conductive material and varying the temperature of the surrounding atmosphere, Wherein, the predetermined output of the first sensor is a frequency signal at an ideal ambient temperature.

2. The sensor system according to claim 1, characterized in that The first sensor is an eddy current sensor.

3. The sensor system according to claim 1, characterized in that The at least one output of the first sensor is a frequency signal. 4 . The sensor system of claim 1 , further comprising a second sensor in electrical communication with the controller, wherein the second sensor is configured to measure a temperature of a desired input location.

5. The sensor system according to claim 4, characterized in that The second sensor is a thermistor.

6. A method for temperature compensation of a sensor system for an electric differential, comprising the following steps: providing a first sensor positioned radially outward from a sensor plate coupled to a locking gear of the electric differential, the sensor being configured to generate an output, at least one output of the first sensor being indicative of a distance of the locking gear of the electric differential from the first sensor; providing a controller in electrical communication with the first sensor, wherein the controller includes a memory for storing data; providing an offset profile stored in the memory of the controller, wherein the offset profile provides a plurality of offset values ​​for the output of the first sensor; transmitting the output of the first sensor to the controller; as well as calculating a temperature compensated output of the first sensor by adjusting the output of the first sensor by one of the offset values ​​stored in the memory of the controller, wherein the at least one offset value is a difference between at least one measured output of the first sensor and a predetermined output of the first sensor, wherein the at least one measurement output of the first sensor is determined while maintaining the position of the conductive material and varying the temperature of the surrounding atmosphere, Wherein, the predetermined output of the first sensor is a frequency signal at an ideal ambient temperature.

7. The method of claim 6, further comprising the steps of: A second sensor is provided in electrical communication with the controller, wherein the second sensor is configured to measure a temperature of the desired input location.

8. The method according to claim 7, characterized in that One of the offset values ​​is obtained from the offset profile based on the output of the first sensor and a measured temperature from the second sensor.

9. The method of claim 6, further comprising the steps of: The temperature compensated output of the first sensor is compared to a calibrated value of the output of the first sensor to determine a state of a differential of a vehicle.

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