Torque sensor assembly for a vehicle power steering system

Abstract

The present invention relates to a torque sensor assembly for a vehicle power steering system, which has: a magnet; a first flux closing member, a second flux closing member, and a third flux closing member coaxially surrounding the magnet; and a first magnetic sensor and a second magnetic sensor. Each of the plurality of magnets emits a magnetic field. The second flux closing member is between the first flux closing member and the third flux closing member. The first flux closing member and the third flux closing member collect magnetic fields having a first polarity. The second flux closing member collects magnetic fields having a second polarity opposite to the first polarity. The first magnetic sensor and the second magnetic sensor are positioned to have similar polarities. The first magnetic sensor is between the first flux closing member and the second flux closing member. The second magnetic sensor is between the second flux closing member and the third flux closing member. A torque signal is calculated by subtracting a second signal generated by the second magnetic sensor from a first signal generated by the first magnetic sensor.

Description

Technical Field

[0001] The present invention generally relates to a vehicle power steering system, and more particularly to a torque sensor assembly for such a vehicle power steering system. Background Art

[0002] Motor vehicles typically include a power steering system to assist in turning the steerable wheels of the vehicle. The power steering system will typically include a rack and pinion assembly to convert the rotational movement of the vehicle's steering wheel into linear movement to effect the turning of the steerable wheels. A torque sensor assembly is commonly used to measure the direction and magnitude of the steering torque applied by the vehicle driver to the steering wheel. The electronic control unit then uses the measured direction and magnitude of the steering torque to operate a power source that assists in turning the steerable wheels.

[0003] The torque sensor assembly can operate by using a magnetic sensor to detect changes in a magnetic field generated by a magnet fixed to a steering member that rotates with the steering wheel. However, such torque sensor assemblies are vulnerable to external magnetic fields, which may cause the output of the torque sensor to erroneously represent the steering torque applied by the driver. The external magnetic field can be generated by sources external and / or internal to the vehicle. For example, the external magnetic field may be caused by large current cables (such as a starter cable) being routed in the vicinity of the torque sensor assembly due to vehicle packaging requirements. In addition, autonomous vehicles are expected to require increasingly precise steering systems with torque sensor assemblies that are not vulnerable to external magnetic fields.

[0004] The torque sensor assembly can shield the external magnetic field to prevent the erroneous representation of the steering torque applied by the driver. However, such shielding increases the cost, weight, and complexity of the vehicle. Accordingly, there is a desire for a torque sensor assembly that reduces external magnetic fields without the need for shielding. Summary of the Invention

[0005] The present invention relates to a torque sensor assembly for a vehicle power steering system.

[0006] According to one embodiment, the torque sensor assembly may include, individually and / or in combination, one or more of the following features: a plurality of magnets; a first flux closing member, a second flux closing member, and a third flux closing member coaxially surrounding the magnets; and a first magnetic sensor and a second magnetic sensor. Each magnet of the plurality of magnets emits a magnetic field. The second flux closing member is between the first flux closing member and the third flux closing member. The first flux closing member and the third flux closing member collect magnetic fields having a first polarity, and the second flux closing member collects magnetic fields having a second polarity opposite to the first polarity. The first magnetic sensor and the second magnetic sensor are positioned with similar polarities. The first magnetic sensor is between the first flux closing member and the second flux closing member, and the second magnetic sensor is between the second flux closing member and the third flux closing member; and the torque sensor assembly further includes: at least one flux closing extension, the flux closing extension being between the first flux closing member and the first magnetic sensor, between the second flux closing member and the first magnetic sensor and the second magnetic sensor, or between the third flux closing member and the second magnetic sensor, thereby reducing the sensitivity of the torque sensor to external magnetic fields without using a shield.

[0007] According to this embodiment, the torque sensor assembly further includes: a first signal output by the first magnetic sensor in response to the magnetic field; and a second signal output by the second magnetic sensor in response to the magnetic field.

[0008] According to this embodiment, the torque sensor assembly further includes a torque signal calculated by subtracting the second signal from the first signal.

[0009] According to this embodiment, the first flux closing member, the second flux closing member, and the third flux closing member are ferromagnetic rings.

[0010] According to this embodiment, the torque sensor assembly further includes: a first finger extending from the first flux closing member; a second finger extending from the second flux closing member; and a third finger extending from the third flux closing member, wherein when the second finger aligns with the second pole of the magnet, the first finger and the third finger align with the first pole of the magnet, the first pole having a first polarity and the second pole having a second polarity.

[0011] According to this embodiment, a first quantity of the first finger is equal to a second quantity of the second finger, a third quantity of the third finger, and a fourth quantity of the magnet.

[0012] According to this embodiment, the torque sensor assembly further includes: at least one flux-closed extension portion, which is between the first flux-closed member and the first magnetic sensor, between the second flux-closed member and the first and second magnetic sensors, or between the third flux-closed member and the second magnetic sensor.

[0013] According to this embodiment, the first and second magnetic sensors are Hall effect sensors, giant magnetoresistive sensors, anisotropic magnetoresistive sensors, or fluxgate magnetometers.

[0014] According to this embodiment, the magnet is arranged with alternating poles in the circumferential direction.

[0015] According to this embodiment, the magnet includes a plurality of magnet layers coaxial with the first flux-closed member, the second flux-closed member, and the third flux-closed member, and the magnets in the magnet layers are arranged with alternating poles in the circumferential direction and the axial direction.

[0016] According to this embodiment, the plurality of magnet layers include a first magnet layer, a second magnet layer, and a third magnet layer.

[0017] According to this embodiment, the torque sensor assembly further includes: a first shaft; and a second shaft, wherein the magnet is fixed to the first shaft, and the first and second magnetic sensors are fixed to the second shaft.

[0018] According to another embodiment, the torque sensor assembly may include, individually and / or in combination, one or more of the following features: a plurality of magnets arranged in a circular pattern; a first flux closing member having a first finger; a second flux closing member having a second finger; a third flux closing member having a third finger; a first magnetic sensor, and a second magnetic sensor. Each of the magnets has a first pole and a second pole, and the first pole and the second pole alternate in the circumferential direction. The first flux closing member, the second flux closing member, and the third flux closing member are ferromagnetic rings coaxial with the plurality of magnets. The second flux closing member is between the first flux closing member and the third flux closing member. The first finger and the third finger are aligned with the first pole, and the second finger is aligned with the second pole. The first magnetic sensor is between the first flux closing member and the second flux closing member and generates a first signal in response to the plurality of magnets. The second magnetic sensor is between the second flux closing member and the third flux closing member and generates a second signal in response to the plurality of magnets. The second magnetic sensor is positioned to have a similar polarity to the first magnetic sensor, and the first signal minus the second signal is a torque signal for the power steering system; the torque sensor assembly further includes: a first flux closing extension between the first flux closing member and the first magnetic sensor; a second flux closing extension between the second flux closing member and the first magnetic sensor and the second magnetic sensor; and a third flux closing extension between the third flux closing member and the second magnetic sensor, wherein the first magnetic sensor is in a first gap between the first flux closing extension and the second flux closing extension, and the second magnetic sensor is in a second gap between the second flux closing extension and the third flux closing extension, thereby reducing the sensitivity of the torque sensor to external magnetic fields without using a shield.

[0019] According to this embodiment, a first quantity of the first fingers is equal to a second quantity of the second fingers, a third quantity of the third fingers, and a fourth quantity of the magnets.

[0020] According to another embodiment, the torque sensor assembly may include, individually and / or in combination, one or more of the following features: a plurality of magnets arranged in a circular pattern; a first flux closure member, a second flux closure member, and a third flux closure member coaxial with the magnets; and a first magnetic sensor and a second magnetic sensor. Each of the magnets emits a magnetic field and has alternating first and second poles arranged in the axial direction and the circumferential direction in the magnet layer. The first flux closure member, the second flux closure member, and the third flux closure member are ferromagnetic rings. The second flux closure member is between the first flux closure member and the third flux closure member. The first flux closure member and the third flux closure member collect magnetic fields having a first polarity, and the second flux closure member collects magnetic fields having a second polarity opposite to the first polarity. The first magnetic sensor is between the first flux closure member and the second flux closure member and generates a first signal in response to the magnetic field. The second magnetic sensor is between the second flux closure member and the third flux closure member and generates a second signal in response to the magnetic field. The second magnetic sensor is positioned to have a similar polarity to the first magnetic sensor, and the first signal minus the second signal is a torque signal for the power steering system. The torque sensor assembly further includes: a first flux closure extension between the first flux closure member and the first magnetic sensor; a second flux closure extension between the second flux closure member and the first and second magnetic sensors; and a third flux closure extension between the third flux closure member and the second magnetic sensor, wherein the first magnetic sensor is between the first flux closure extension and the second flux closure extension, and the second magnetic sensor is between the second flux closure extension and the third flux closure extension, thereby reducing the sensitivity of the torque sensor to external magnetic fields without using shielding.

[0021] According to this embodiment, the plurality of magnet layers includes a first magnet layer, a second magnet layer, and a third magnet layer.

[0022] According to this embodiment, the second flux closure member has fingers that collect magnetic fields having the second polarity.

[0023] One or more potential and / or realized advantages of embodiments of the torque sensor assembly are that the sensitivity of the torque sensor to external magnetic fields is reduced without using shielding. When read in conjunction with the accompanying drawings, other advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments. Description of the Drawings

[0024] Figure 1 is a schematic diagram of a vehicle power steering system having a first embodiment of a torque sensor assembly according to the present invention.

[0025] Figure 2 is Figure 1 an exploded perspective view of a torque sensor assembly.

[0026] Figure 3 is a front view of the Figure 1 torque sensor assembly in a first position.

[0027] Figure 4 is a front view of the Figure 1 torque sensor assembly in a second position.

[0028] Figure 5 is Figure 3 an enlarged portion in

[0029] Figure 6 is a partial front view of the Figure 5 torque sensor assembly under an external magnetic field different from Figure 1 that.

[0030] Figure 7 is a partial front view of the Figure 5 torque sensor assembly in an operating state different from Figure 1 that.

[0031] Figure 8 is a partial front view of the Figure 1 torque sensor assembly in the operating state of Figure 7 but under a different external magnetic field.

[0032] Figure 9 is a partial front view of the Figure 5 torque sensor assembly under an external magnetic field different from that of Figures 7 Figure 1 to 8.

[0033] Figure 10 is a partial front view of the Figures 5 to 9 torque sensor assembly under an external magnetic field different from Figure 1 that.

[0034] Figure 11 is a partial front view of the Figures 5 to 10 torque sensor assembly under an external magnetic field different from Figure 1 that.

[0035] Figure 12 is an exploded perspective view of a torque sensor assembly according to a second embodiment of the present invention.

[0036] Figure 13 is a front view of the Figure 12 torque sensor assembly in a first position.

[0037] Figure 14 is a front view of the Figure 12Front view of the torque sensor assembly.

[0038] Figure 15 is Figure 13 the enlarged portion in. Detailed implementation

[0039] Now refer to Figure 1 , which schematically shows a part of a vehicle power steering system (generally indicated by 100). The overall structure and operation of the power steering system 100 are conventional in the art. For example, the power steering system 100 can be as disclosed in U.S. Patent No. 7,055,646 to Borghese, the disclosure of which is hereby incorporated by reference in its entirety. Accordingly, only those parts of the power steering system 100 that are necessary for a full understanding of the present invention will be explained and shown in detail. Although the present invention will be described and shown in connection with the specific power steering system 100 disclosed herein, it should be recognized that the present invention can be used in combination with other vehicle power steering systems, including other electric, hydraulic, or otherwise powered power steering systems known to those skilled in the art.

[0040] The power steering system 100 is partially housed in a housing (generally indicated by 102). The power steering system 100 is respectively associated with a first steerable front wheel 104A and a second steerable front wheel 104B of the vehicle.

[0041] The vehicle steering wheel 106 is operatively coupled to the input shaft 108 to rotate therewith about the steering axis X1. Further, the input shaft 108 is operatively connected to the lower shaft 112 through a torsion bar 110. A torque sensor assembly (generally indicated by 114) surrounds the input shaft 108, the torsion bar 110, and the lower shaft 112. The torque sensor assembly 114 is fixed to the input shaft 108 and the lower shaft 112. As will be discussed, the torque sensor assembly 114 generates an electrical signal in response to the rotation of the input shaft 108. The signal is transmitted through a data network 116 to an electronic control unit (ECU) 118. The signal indicates the direction and magnitude of the steering torque applied to the steering wheel 106.

[0042] The lower shaft 112 is operatively connected to the pinion 120. The torsion bar 110 twists in response to the steering torque applied to the steering wheel 106. When the torsion bar 110 twists, relative rotation occurs between the input shaft 108 and the pinion 120 via the lower shaft 112.

[0043] The steerable member 122 that can move linearly can move along the rack axis X2. The rack portion 124 of the steerable member 122 is provided with a series of rack teeth, and these rack teeth engage with the gear teeth provided on the pinion 120. The steerable member 122 further includes a screw portion 126 having an external thread. The steerable member 122 is connected to the first steerable wheel 104A through the first tie rod 128A and is connected to the second steerable wheel 104B through the second tie rod 128B. The first tie rod 128A and the second tie rod 128B are respectively located at the distal end of the steerable member 122. The linear movement of the steerable member 122 along the rack axis X2 causes the first steerable wheel 104A and the second steerable wheel 104B to turn respectively in a known manner.

[0044] The power steering system 100 further includes a power source 130, which is drivingly connected to the ball nut assembly 132. The power source 130 is shown as an electric motor, but it may not be an electric motor. For example, the power source 130 may be a hydraulic system. The ECU 118 controls the power source 130 according to the signal received from the torque sensor assembly 114. The control signal is transmitted from the ECU 118 to the power source 130 via the data network 116.

[0045] The ball nut assembly 132 is operatively connected to the screw portion 126 of the steerable member 122. The power source 130 and the ball nut assembly 132 are operatively connected through a pulley assembly 134, and the pulley assembly includes a belt between the output of the power source 130 and the ball nut assembly 132.

[0046] The rotation of the pulley assembly 134 causes the ball nut assembly 132 to rotate, and thereby generates the linear movement of the steerable member 122. The power source 130 causes the pulley assembly 134 to rotate, and the pulley assembly further transmits the driving force of the power source 130 to the ball nut of the ball nut assembly 132. Since the ball nut is fixed in place on the rack axis X2, the steerable member 122 is driven to move linearly in response to the rotation of the ball nut, so as to respectively achieve the steering movements of the first steerable wheel 104A and the second steerable wheel 104B of the vehicle as discussed. Therefore, the power source 130 provides steering assistance in response to the applied steering torque.

[0047] In the case where the power source 130 cannot achieve the linear movement of the steerable member 122, the mechanical connection between the gear teeth on the pinion 120 and the rack teeth on the rack portion 124 allows the vehicle to be manually steered.

[0048] Now refer to Figures 2 to 4, which shows in detail the torque sensor assembly 114. The torque sensor assembly 114 has a plurality of magnets (generally indicated by 136) arranged around the torque assembly axis X3. There are also a first flux closing member 138, a second flux closing member 140, and a third flux closing member 142 respectively on the torque assembly axis X3. When assembled, the first flux closing member 138, the second flux closing member 140, and the third flux closing member 142 are ferromagnetic rings that are substantially parallelly oriented respectively.

[0049] The first flux closing member 138 has a plurality of first fingers (generally indicated by 144). The second flux closing member 140 has a plurality of second fingers (generally indicated by 146). The third flux closing member 142 has a plurality of third fingers 148.

[0050] The first fingers 144 axially extend from the first flux closing member 138 towards the second flux closing member 140 in a single direction. The second fingers 146 axially extend from the second flux closing member 140 towards the first flux closing member 138 and the third flux closing member 142 respectively in opposite directions. The second fingers 146 have a first part 146A extending towards the first flux closing member 138 and a second part 146B extending towards the third flux closing member 142. As shown, the first part 146A and the second part 146B are respectively aligned across the second flux closing member 140, such that the second fingers 146 are continuous across the second flux closing member 140 between the first part 146A and the second part 146B. The third fingers 148 axially extend from the third flux closing member 142 towards the second flux closing member 140 in a single direction.

[0051] As Figure 3 and Figure 4 best shown, the first flux closing member 138, the second flux closing member 140, and the third flux closing member 142 are respectively positioned relative to each other such that when the torque sensor assembly 114 is assembled, the first fingers 144 mesh with the first part 146A of the second fingers 146 and the second part 146B of the second fingers 146 meshes with the third fingers 148.

[0052] Preferably, the first quantity of the first fingers 144 is equal to the second quantity of the second fingers 146 (the quantities of the first part 146A and the second part 146B are correspondingly equal), the third quantity of the third fingers 148, and the fourth quantity of the magnets 136. As shown, each of the second fingers in the second fingers extends toward both the first flux closing member 138 and the third flux closing member 142. In the illustrated embodiment, the first quantity, the second quantity, the third quantity, and the fourth quantity are all eight, which is a non-limiting example. Alternatively, the first quantity, the second quantity, the third quantity, and the fourth quantity may be greater than or less than eight.

[0053] Each of the magnets 136 has a first pole (generally indicated by 136A) and a second pole (generally indicated by 136B). The magnets 136 are positioned such that the line L between the first pole 136A and the second pole 136B is transverse to the torque assembly axis X3. The magnets 136 are arranged such that the first pole 136A of the first magnet is adjacent to the second pole 136B' of the second magnet, and the second pole 136B of the first magnet is adjacent to the first pole 136A' of the third magnet, i.e., the magnets 136 have alternating poles in the circumferential direction transverse to the torque assembly axis X3.

[0054] In the illustrated embodiment, the magnets 136 are shown adjacent to each other without any air gaps or other voids. Alternatively, the magnets 136 may be arranged such that there are air gaps and / or spaces between each of the magnets 136. Each of the magnets 136 emits a magnetic field, and the magnetic field is configured to be collected by the first flux closing member 138, the second flux closing member 140, and the third flux closing member 142, respectively.

[0055] The torque sensor assembly 114 further includes a first flux closing extension, a second flux closing extension, and a third flux closing extension (generally indicated by 150, 152, and 154, respectively). The first flux closing extension 150 has an arcuate first part 150A and a second part 150B. The first part 150A is associated with the first flux closing member 138, i.e., the first part 150A may be fixed to the first flux closing member 138, otherwise connected to the first flux closing member, or positioned close enough to the first flux closing member such that the magnetic field collected by the first flux closing member 138 is transferred from the first flux closing member 138 to the second part 150B.

[0056] Similarly, the second flux-closure extension 152 has an arcuate first portion 152A and a second portion 152B, and the third flux-closure extension 154 has an arcuate first portion 154A and a second portion 152B. The first portion 152A of the second flux-closure extension 152 transfers the magnetic field collected by the second flux-closure member 140 from the second flux-closure member 140 to the second portion 152B. The first portion 154A of the third flux-closure extension 154 transfers the magnetic field collected by the third flux-closure member 142 from the third flux-closure member 142 to the second portion 154B.

[0057] Alternatively, one or more of the first flux-closure extension 150, the second flux-closure extension 152, or the third flux-closure extension 154 may be integrally formed with the corresponding first flux-closure member 138, second flux-closure member 140, or third flux-closure member 142, respectively, such that the flux-closure extension and the flux-closure member are a single component.

[0058] Alternatively, one or more of the first flux-closure extension, the second flux-closure extension, and the third flux-closure extension (generally denoted by 150, 152, and 154, respectively) may be omitted. When the first flux-closure extension 150 is omitted, the first flux-closure member 138 will then directly guide the magnetic field back and forth between the magnet 136 and the first magnetic sensor 160. When the second flux-closure extension 152 is omitted, the second flux-closure member 140 will then directly guide the magnetic field back and forth between the magnet 136 and the first magnetic sensor 160 and the second magnetic sensor 162, respectively. When the third flux-closure extension 154 is omitted, the third flux-closure member 142 will then directly guide the magnetic field back and forth between the magnet 136 and the second magnetic sensor 162.

[0059] As Figure 3 and Figure 4 best shown, there is a first air gap or void (generally denoted by 156) between the second portion 150B of the first flux-closure extension 150 and the second portion 152B of the second flux-closure extension 152. There is also a second air gap or void (generally denoted by 158) between the second portion 152B of the second flux-closure extension 152 and the second portion 154B of the third flux-closure extension 154.

[0060] The first magnetic sensor 160 and the second magnetic sensor 162 are respectively fixed or otherwise supported on the housing 102. Alternatively, the first magnetic sensor 160 and the second magnetic sensor 162 can be respectively fixed on a sub-housing for the torque sensor assembly 114 within the housing 102. For example, the first magnetic sensor 160 and the second magnetic sensor 162 can be respectively soldered to a printed circuit board captured by the sub-housing. The first magnetic sensor 160 is positioned in the first air gap 156, and the second magnetic sensor 162 is positioned in the second air gap 158. As a non-limiting example, the first magnetic sensor 160 and the second magnetic sensor 162 can be respectively a Hall effect sensor, a giant magnetoresistive sensor, an anisotropic magnetoresistive sensor, or a fluxgate magnetometer. Alternatively, the first magnetic sensor 160 and the second magnetic sensor 162 can be respectively any suitable sensors that generate or otherwise output a predictable electrical signal in response to a change in a magnetic field.

[0061] The magnet 136 is fixed to the input shaft 108 (the first magnetic sensor 160 and the second magnetic sensor 162 are respectively on the lower shaft 112) or the lower shaft 112 (the first magnetic sensor 160 and the second magnetic sensor 162 are respectively on the input shaft 108). Typically, the magnet 136 is fixed to a support ring or other structure (not shown), which in turn is fixed to the input shaft 108 or the lower shaft 112.

[0062] When the magnet 136 is positioned as shown relative to the first flux closing member 138, the second flux closing member 140, and the third flux closing member 142 respectively, Figure 3 the first finger 144, the second finger 146, and the third finger 148 are respectively centered relative to the corresponding first pole 136A and second pole 136B of the magnet 136, and the first finger 144, the second finger 146, and the third finger 148 respectively collect the magnetic field with maximum intensity. As shown by the arrow 164 in Figure 3 , the magnetic field flows from the first pole 136A of each magnet in the magnet 136 through the first finger 144 to the first flux closing member 138 and through the third finger 148 to the third flux closing member 142. Then, the first flux closing extension 150 transfers the magnetic field to the first air gap 156, and the third flux closing extension 154 transfers the magnetic field to the second air gap 158.

[0063] Then, the magnetic field flows from the first flux-closure extension 150 across the first air gap 156 to the second flux-closure extension 152. By doing so, the magnetic field flows through the first magnetic sensor 160, and the first magnetic sensor 160 generates and outputs a first electrical signal in response to the magnetic field. Similarly, the magnetic field flows through the second magnetic sensor 162 across the second air gap 158 from the third flux-closure extension 154 to the second flux-closure extension 152, and the second magnetic sensor 162 generates and outputs a second electrical signal in response to the magnetic field. Then, the magnetic field flows from the second flux-closure extension 152 through the second flux-closure member 140 and the second finger 146 to the second pole 136B of each magnet in the magnet 136.

[0064] When the magnets 136 are positioned relative to the first flux-closure member 138, the second flux-closure member 140, and the third flux-closure member 142 as Figure 4 shown, the first finger 144, the second finger 146, and the third finger 148 are equidistant between the corresponding first poles 136A and second poles 136B of the magnets 136, respectively, and the first finger 144, the second finger 146, and the third finger 148 collect the magnetic field with minimum intensity (i.e., intensity close to zero), respectively. Additionally, the reduced magnetic fields of the magnets 136 flow through the first magnetic sensor 160 and the second magnetic sensor 162 as described above for Figure 3 .

[0065] As the magnets 136 rotate, this predictable and repetitive change in magnetic field intensity (between the positions shown in Figure 3 and Figure 4 ) allows the signals generated by the first magnetic sensor 160 and the second magnetic sensor 162, respectively, to be used to calculate the direction and magnitude of the steering torque applied to the steering wheel 106. Alternatively, the first flux-closure member 138, the second flux-closure member 140, and the third flux-closure member 142 can rotate around the magnets 136, respectively.

[0066] Now referring to Figure 5 , it is shown in detail that when the magnetic field flows from the first flux-closure extension 150 to the second flux-closure extension 152, the first magnetic sensor 160 measures the magnetic field from the magnet 136 (generally indicated by the first arrow 164A). Similarly, when the magnetic field flows from the third flux-closure extension 154 to the second flux-closure extension 152, the second magnetic sensor 162 measures the magnetic field from the magnet 136 (generally indicated by the second arrow 164B).

[0067] The first magnetic sensor 160 and the second magnetic sensor 162 also measure the external magnetic field 166 respectively. The external magnetic field 166 comes from one or more magnetic sources outside the torque sensor assembly 114, that is, not from the magnet 136. The external magnetic field 166 can be any magnetic field that is not emitted by any of the magnets in the magnet 136 and can come from multiple sources.

[0068] The first magnetic sensor 160 and the second magnetic sensor 162 are respectively positioned with similar polarities. As a non-limiting example, the positive pole of the first magnetic sensor 160 can be positioned closest to the first flux-closed extension 150, and the positive pole of the second magnetic sensor 162 can be positioned closest to the second flux-closed extension 152.

[0069] The first intensity of the magnetic field flowing from the first flux-closed extension 150 to the second flux-closed extension 152 (shown by the first arrow 164A) can be characterized as B1, the second intensity of the magnetic field flowing from the third flux-closed extension 154 to the second flux-closed extension 152 (shown by the second arrow 164B) can be characterized as B2, and the third intensity of the external magnetic field 166 can be characterized as B e 。

[0070] The first signal S1 generated by the first magnetic sensor 160 due to the first intensity B1 and the third intensity B e can be described as:

[0071] S1 = -B1 + B e (1)

[0072] And the second signal S2 generated by the second magnetic sensor 162 due to the second intensity B2 and the third intensity B e can be described as:

[0073] S2 = B2 + B e (2).

[0074] Subtract Equation 2 from Equation 1 to eliminate or remove the external magnetic field term B measured by both the first magnetic sensor 160 and the second magnetic sensor 162 e :

[0075] S1 - S2 = (-B1 + B e ) - (B2 + B e ) (3).

[0076] Equation 3 can be simplified to:

[0077] S1 - S2 = B1 + B2 (4)

[0078] where S1 - S2 is the torque signal calculated by the ECU 118 for operating the power source 130.

[0079] Now referring to Figure 6 , which shows a portion of the torque sensor assembly 114, where the external magnetic field 166 has a polarity opposite to that Figure 5 shown, and the magnetic field from the magnet 136 is the same as that Figure 5 shown. The first signal S1 generated by the first magnetic sensor 160 due to the first intensity B1 and the third intensity B Figure 6 shown respectively can be described as: e S1 = -B1 - B

[0080] (5) e

[0081] And the second signal S2 generated by the second magnetic sensor 162 due to the second intensity B2 and the third intensity B Figure 6 shown respectively can be described as: e S2 = B2 - B

[0082] (6). e

[0083] Subtract Equation 6 from Equation 5 to eliminate or remove the external magnetic field term B measured by both the first magnetic sensor 160 and the second magnetic sensor 162 e :

[0084] S1 - S2 = (-B1 - B e ) - (B2 - B e ) (7).

[0085] Equation 7 can be simplified to:

[0086] S1 - S2 = B1 + B2 (8)

[0087] where S1 - S2 is the torque signal calculated by the ECU 118 for operating the power source 130.

[0088] Now referring to Figure 7, which shows a portion of the torque sensor assembly 114 in an operating state different from that Figure 5 shown. In Figure 7, the magnetic field from the magnet 136 has a polarity opposite to that Figure 5 shown, and the external magnetic field 166 is the same as that Figure 5 shown. The first signal S1 generated by the first magnetic sensor 160 due to the first intensity B1 and the third intensity B shown in Figure 7 e respectively can be described as:

[0089] S1 = B1 + B e (9)

[0090] and the second signal S2 generated by the second magnetic sensor 162 respectively due to the second intensity B2 and the third intensity B shown in FIG. 7 can be described as: e

[0091] S2 = -B2 + B e (10).

[0092] Subtract Equation 10 from Equation 9 to eliminate or remove the external magnetic field term B measured by both the first magnetic sensor 160 and the second magnetic sensor 162 e :

[0093] S1 - S2 = (B1 + B e ) - (-B2 + B e ) (11).

[0094] Equation 11 can be simplified to:

[0095] S1 - S2 = B1 + B2 (12)

[0096] where S1 - S2 is the torque signal calculated by the ECU 118 for operating the power source 130.

[0097] Now referring to FIG. 8, a portion of the torque sensor assembly 114 in the operating state of FIG. 7 but under a different external magnetic field is shown. In FIG. 8, the magnetic field from the magnet 136 is opposite to that Figure 5 shown, and the external magnetic field 166 has a polarity opposite to that Figure 5 shown. The first signal S1 generated by the first magnetic sensor 160 respectively due to the first intensity B1 and the third intensity B shown in FIG. 8 e can be described as:

[0098] S1 = B1 - B e (13)

[0099] and the second signal S2 generated by the second magnetic sensor 162 respectively due to the second intensity B2 and the third intensity B shown in FIG. 8 e can be described as:

[0100] S2 = -B2 - B e (14).

[0101] Subtract Equation 14 from Equation 13 to eliminate or remove the external magnetic field term B measured by both the first magnetic sensor 160 and the second magnetic sensor 162 e :

[0102] S1 - S2 = (B1 - B e ) - (-B2 - B e ) (15). ​

[0103] Equation 15 can be simplified to:

[0104] S1 - S2 = B1 + B2 (16)

[0105] Wherein, S1 - S2 is a torque signal calculated by the ECU 118 for operating the power source 130.

[0106] The shape, position, direction, and / or magnitude of the external magnetic field 166 are not limited to Figure 5 those shown in FIG. 8. Any external magnetic field passing through the first flux - enclosing member 138, the second flux - enclosing member 140, and the third flux - enclosing member 142 respectively, or passing through the first flux - enclosing extension 150, the second flux - enclosing extension 152, and the third flux - enclosing extension 154 respectively, will be at least partially reduced or removed. For example, as a non - limiting example, the external magnetic field 166 can be as Figures 9 to 11 shown.

[0107] In Figure 9 , the vector 166A representing the external magnetic field passes through the first flux - enclosing member 138, the second flux - enclosing member 140, and the third flux - enclosing member 142 at different points on the circumferences of the first flux - enclosing member 138, the second flux - enclosing member 140, and the third flux - enclosing member 142 respectively. In Figure 10 , the vector 166B representing the external magnetic field passes through the first flux - enclosing member 138, the second flux - enclosing member 140, and the third flux - enclosing member 142 at the same points on the circumferences of the first flux - enclosing member 138, the second flux - enclosing member 140, and the third flux - enclosing member 142 respectively. In Figure 11 , the first vector 166C, the second vector 166D, and the third vector 166E representing the external magnetic field pass through the first flux - enclosing member 138, the second flux - enclosing member 140, and the third flux - enclosing member 142 at substantially the same points on the circumferences of the first flux - enclosing member 138, the second flux - enclosing member 140, and the third flux - enclosing member 142 respectively, but as a cluster of three vectors. In Figures 9 to 11 , the magnetic field emitted by the magnet 136 is not shown.

[0108] As discussed, the first magnetic sensor 160 and the second magnetic sensor 162 are two - channel sensors respectively. Alternatively, the first magnetic sensor 160 and the second magnetic sensor 162 can each have more than two channels. For example, the first magnetic sensor 160 and the second magnetic sensor 162 can each be a three - channel or four - channel sensor.

[0109] Now refer to Figures 12 to 15, shows a second embodiment of a torque sensor assembly (generally designated 214) in accordance with the present invention. Since torque sensor assembly 214 is a variant of torque sensor assembly 114, like reference numerals increased by 100 designate corresponding parts in the drawings and their detailed description will be omitted.

[0110] Magnet 236 includes a circular first magnet layer, a second magnet layer, and a third magnet layer (generally designated 268, 270, and 272 respectively). Although magnet 236 is shown as having three magnet layers, magnet 236 may have more or fewer than three magnet layers. Corresponding to between the first magnet layer 268 and the second magnet layer 270 is a first support structure 274, and corresponding to between the second magnet layer 270 and the third magnet layer 272 is a second support structure 276. The first support structure 274 and the second support structure 276 support magnet 236 respectively.

[0111] Magnet 236 is arranged such that a first pole 236A of the first magnet is adjacent to a second pole 236B' of an adjacent magnet, and a second pole 236B of the first magnet is adjacent to a first pole 236A' of an adjacent magnet, such that a "checkerboard" pattern is formed. Thus, magnet 236 is arranged in the first magnet layer 268, the second magnet layer 270, and the third magnet layer 272 respectively such that the first and second poles of the magnet alternate along an axial direction parallel to the torque assembly axis X3 and along a circumferential direction transverse to the torque assembly axis X3. In addition, magnet 236 is arranged such that similar poles are diagonally aligned.

[0112] Although the first flux closure member 238 and the third flux closure member 242 are respectively shown as not having fingers, fingers such as the first finger 144 and the third finger 148 etc. may be provided for the first flux closure member 238 and the third flux closure member 242 respectively.

[0113] When magnet 236 is positioned relative to the first flux closure member 238, the second flux closure member 240, and the third flux closure member 242 as shown in FIG. 7 respectively, the fingers 246 are then centered relative to the first pole 236A and the second pole 236B of magnet 236, and the first flux closure member 238, the second flux closure member 240, and the third flux closure member 242 collect the magnetic field with maximum intensity respectively (the second flux closure member 240 collects the magnetic field via the fingers 246).

[0114] When the magnet 236 is positioned relative to the first flux - closing member 238, the second flux - closing member 240, and the third flux - closing member 242 as shown in FIG. 8, the fingers 246 are equidistant between the first pole 236A and the second pole 236B of the magnet 236, and the first flux - closing member 238, the second flux - closing member 240, and the third flux - closing member 242 each collect the magnetic field at a minimum intensity (i.e., an intensity close to zero) (the second flux - closing member 240 again collects the magnetic field via the fingers 246).

[0115] The first intensity of the magnetic field flowing from the first flux - closing extension 250 to the second flux - closing extension 252 (shown by arrow 264A) can be characterized as B1, the second intensity of the magnetic field flowing from the third flux - closing extension 254 to the second flux - closing extension 252 (shown by arrow 264B) can be characterized as B2, and the third intensity of the external magnetic field 266 can be characterized as B e 。

[0116] The first signal S1 generated by the first magnetic sensor 260 due to the first intensity B1 and the third intensity B e can be described as:

[0117] S1 = B1 + B e (17)

[0118] And the second signal S2 generated by the second magnetic sensor 262 due to the second intensity B2 and the third intensity B e can be described as:

[0119] S2 = - B2 + B e (18).

[0120] Subtract equation 18 from equation 17 to eliminate the external magnetic field term B measured by both the first magnetic sensor 260 and the second magnetic sensor 262 e :

[0121] S1 - S2=(B1 + B e )-(- B2 + B e ) (19).

[0122] Equation 19 can be simplified to:

[0123] S1 - S2 = B1 + B2 (20).

[0124] Where S1 - S2 is a torque signal for the power source of the power - assisted steering system.

[0125] In accordance with the provisions of the patent statutes, the principles and mode of operation thereof have been described and illustrated in the preferred embodiments of the present invention. However, it must be understood that the invention may be practiced otherwise than as specifically explained and illustrated, without departing from the spirit or scope of the present invention.

Claims

1. A torque sensor assembly adapted to be used in a vehicle power steering system, comprising: A plurality of magnets, each magnet emitting a magnetic field; A first flux closing member, a second flux closing member, and a third flux closing member coaxial with the magnet, wherein the second flux closing member is between the first flux closing member and the third flux closing member, the first flux closing member and the third flux closing member collect magnetic fields having a first polarity, and the second flux closing member collects magnetic fields having a second polarity opposite to the first polarity; and A first magnetic sensor and a second magnetic sensor, the first magnetic sensor and the second magnetic sensor being positioned with similar polarities, wherein the first magnetic sensor is between the first flux closing member and the second flux closing member, and the second magnetic sensor is between the second flux closing member and the third flux closing member; and The torque sensor assembly further comprises: At least one flux closing extension, the flux closing extension being between the first flux closing member and the first magnetic sensor, between the second flux closing member and the first magnetic sensor and the second magnetic sensor, or between the third flux closing member and the second magnetic sensor, thereby reducing the sensitivity of the torque sensor to external magnetic fields without using a shield.

2. The torque sensor assembly according to claim 1, further comprising: A first signal output by the first magnetic sensor in response to the magnetic field; And A second signal output by the second magnetic sensor in response to the magnetic field.

3. The torque sensor assembly according to claim 2, further comprising: A torque signal calculated by subtracting the second signal from the first signal.

4. The torque sensor assembly according to claim 1, wherein, The first flux closing member, the second flux closing member, and the third flux closing member are ferromagnetic rings.

5. The torque sensor assembly according to claim 1, further comprising: A first finger extending from the first flux closing member; A second finger extending from the second flux closing member; And A third finger extending from the third flux closing member, wherein when the second finger is aligned with the second pole of the magnet, the first finger and the third finger are aligned with the first pole of the magnet, the first pole having a first polarity and the second pole having a second polarity.

6. The torque sensor assembly according to claim 5, wherein, The first number of the first fingers is equal to the second number of the second fingers, the third number of the third fingers, and the fourth number of the magnets.

7. The torque sensor assembly according to claim 1, wherein The first magnetic sensor and the second magnetic sensor are Hall effect sensors.

8. The torque sensor assembly according to claim 1, wherein, The magnets are arranged with alternating poles in the circumferential direction.

9. The torque sensor assembly according to claim 1, wherein, The magnets comprise a plurality of magnet layers coaxial with the first flux closing member, the second flux closing member, and the third flux closing member, and the magnets in the magnet layers are arranged with alternating poles in the circumferential direction and the axial direction.

10. The torque sensor assembly according to claim 9, wherein, The plurality of magnet layers includes a first magnet layer, a second magnet layer, and a third magnet layer.

11. The torque sensor assembly according to claim 1, further comprising: a first shaft; and a second shaft, wherein the magnet is fixed to the first shaft, and the first magnetic sensor and the second magnetic sensor are fixed to the second shaft.

12. A torque sensor assembly adapted to be used in a vehicle power steering system, comprising: a plurality of magnets arranged in a circular pattern, wherein each of the magnets has a first pole and a second pole, and the first pole and the second pole alternate in the circumferential direction; a first flux closing member having a first finger; a second flux closing member having a second finger; a third flux closing member having a third finger, wherein the first flux closing member, the second flux closing member, and the third flux closing member are ferromagnetic rings coaxial with the plurality of magnets, the second flux closing member is between the first flux closing member and the third flux closing member, the first finger and the third finger are aligned with the first pole, and the second finger is aligned with the second pole; a first magnetic sensor between the first flux closing member and the second flux closing member, wherein the first magnetic sensor generates a first signal in response to the plurality of magnets; and a second magnetic sensor between the second flux closing member and the third flux closing member, wherein the second magnetic sensor generates a second signal in response to the plurality of magnets, the second magnetic sensor is positioned to have a similar polarity to the first magnetic sensor, and the first signal minus the second signal is a torque signal for the power steering system; and the torque sensor assembly further comprises: a first flux closing extension between the first flux closing member and the first magnetic sensor; a second flux closing extension between the second flux closing member and the first magnetic sensor and the second magnetic sensor; and a third flux closing extension between the third flux closing member and the second magnetic sensor, wherein the first magnetic sensor is in a first gap between the first flux closing extension and the second flux closing extension, and the second magnetic sensor is in a second gap between the second flux closing extension and the third flux closing extension, thereby reducing the sensitivity of the torque sensor to external magnetic fields without using a shield.

13. The torque sensor assembly according to claim 12, wherein, The first number of the first fingers is equal to the second number of the second fingers, the third number of the third fingers, and the fourth number of the magnets.

14. A torque sensor assembly adapted to be used in a vehicle power steering system, comprising: a plurality of circular magnet layers on an axis, wherein the magnets in the magnet layers are arranged with alternating first and second poles in the axial direction and the circumferential direction and emit a magnetic field; A first flux-closure member, a second flux-closure member, and a third flux-closure member coaxial with the magnet, wherein the first flux-closure member, the second flux-closure member, and the third flux-closure member are ferromagnetic rings, the second flux-closure member is between the first flux-closure member and the third flux-closure member, the first flux-closure member and the third flux-closure member collect magnetic fields having a first polarity, and the second flux-closure member collects magnetic fields having a second polarity opposite to the first polarity; A first magnetic sensor between the first flux-closure member and the second flux-closure member, the first magnetic sensor generating a first signal in response to the magnetic field; and A second magnetic sensor between the second flux-closure member and the third flux-closure member, the second magnetic sensor generating a second signal in response to the magnetic field, wherein the second magnetic sensor is positioned with a similar polarity to the first magnetic sensor, and the first signal minus the second signal is a torque signal for the power steering system; and The torque sensor assembly further includes: A first flux-closure extension between the first flux-closure member and the first magnetic sensor; A second flux-closure extension between the second flux-closure member and the first magnetic sensor and the second magnetic sensor; and A third flux-closure extension between the third flux-closure member and the second magnetic sensor, wherein the first magnetic sensor is between the first flux-closure extension and the second flux-closure extension, and the second magnetic sensor is between the second flux-closure extension and the third flux-closure extension, thereby reducing the sensitivity of the torque sensor to external magnetic fields without using shielding.

15. The torque sensor assembly according to claim 14, wherein, The plurality of magnet layers includes a first magnet layer, a second magnet layer, and a third magnet layer.

16. The torque sensor assembly according to claim 14, wherein, The second flux-closure member has fingers that collect magnetic fields having the second polarity.

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