阅读说明：本技术 包括磁屏蔽罩的扭矩传感器单元 (Torque sensor unit comprising a magnetic shield ) 是由 罗曼·阿耶尔 彼得·克诺尔 山多尔·科瓦奇 彼得·绍博 蒂瓦达尔·克里什托夫·托特 于 2020-02-25 设计创作，主要内容包括：本发明涉及一种扭矩传感器单元(1),包括：环形磁体(4),其可以以在旋转方面联合的方式连接至第一部分轴(2)且相对于纵向轴线(100)同心地布置；两个第一磁通导体(5),其可以连接至第二部分轴,且布置在从环形磁体(4)产生的磁场中并且对磁通进行传导；物理固定的传感器单元(7),其具有两个第二磁通导体(9)和布置在印刷电路板(10)上的磁传感器(11),两个第二磁通导体和磁传感器容纳在传感器单元(7)的传感器壳体(8)中,其中,传感器单元(7)被设计成通过测量在两个第一磁通导体(5)之间产生的磁通密度来检测部分轴(2)之间的旋转角度的变化；第二壳体(12),其围绕环形磁体(4)、两个第一磁通导体(5)和传感器单元(7),其特征在于,扭矩传感器单元包括磁屏蔽罩(19),该磁屏蔽罩相对于纵向轴线(100)至少部分地周向围绕传感器单元(7)并且沿纵向轴线(100)的方向布置在将第二壳体(12)封闭的壳体覆盖件(13)与第二壳体(12)之间。(The invention relates to a torque sensor unit (1) comprising: a ring magnet (4) which can be connected to the first partial shaft (2) in a rotationally conjoint manner and which is arranged concentrically with respect to the longitudinal axis (100); two first magnetic flux conductors (5) which can be connected to the second part-shaft and which are arranged in the magnetic field generated from the ring magnet (4) and conduct the magnetic flux; a physically fixed sensor unit (7) having two second magnetic flux conductors (9) and a magnetic sensor (11) arranged on a printed circuit board (10), which are accommodated in a sensor housing (8) of the sensor unit (7), wherein the sensor unit (7) is designed to detect a change in the angle of rotation between the partial shafts (2) by measuring the magnetic flux density generated between the two first magnetic flux conductors (5); a second housing (12) surrounding the ring magnet (4), the two first magnetic flux conductors (5) and the sensor unit (7), characterized in that the torque sensor unit comprises a magnetic shield (19) at least partially circumferentially surrounding the sensor unit (7) with respect to the longitudinal axis (100) and arranged between a housing cover (13) closing the second housing (12) and the second housing (12) in the direction of the longitudinal axis (100).)

1. A torque sensor unit (1) comprising:

-a ring magnet (4), the ring magnet (4) being connectable to the first partial shaft (2) in a rotationally fixed manner and being arranged concentrically with respect to the longitudinal axis (100),

-two first magnetic flux conductors (5), which two first magnetic flux conductors (5) are connectable to a second part-shaft, which two first magnetic flux conductors (5) are arranged in the magnetic field generated from the ring magnet (4) and conduct the magnetic flux,

-a spatially fixed sensor unit (7), the sensor unit (7) having two second magnetic flux conductors (9) and a magnetic sensor (11) arranged on a printed circuit board (10), the two second magnetic flux conductors (9) and the magnetic sensor (11) being accommodated in a sensor housing (8) of the sensor unit (7), wherein the sensor unit (7) is designed to detect a change in the angle of rotation between the partial shafts (2) by measuring a magnetic flux density generated between the two first magnetic flux conductors (5),

-a second housing (12), the second housing (12) surrounding the ring magnet (4), the two first magnetic flux conductors (5) and the sensor unit (7), characterized in that the torque sensor unit comprises a magnetic shield (19), the magnetic shield (19) surrounding the sensor unit (7) at least partially circumferentially with respect to the longitudinal axis (100) and being arranged in the direction of the longitudinal axis (100) between a housing cover (13) closing the second housing (12) and the second housing (12).

2. Torque sensor unit according to claim 1, characterized in that the magnetic shield (19) has at least one support surface which interacts with a guide in the second housing (12).

3. Torque sensor unit according to claim 1 or 2, characterized in that the magnetic shield (19) shields the sensor housing (8) in at least one area remote from the outer side of the ring magnet.

4. Torque sensor unit according to one of the preceding claims, characterized in that said magnetic shield (19) has two arms (21), said two arms (21) each having a first side (22) and a second side (23), wherein said second side (23) extends parallel to said longitudinal axis (100) and said first side (22) is arranged approximately perpendicular to said longitudinal axis (100).

5. Torque sensor unit according to claim 4, wherein said arms (21) are connected to each other only by one of the first sides (22) of said arms (21) or one of the second sides (23) of said arms (21).

6. Torque sensor unit according to claim 4 or 5, characterized in that said magnetic shield (19) is clamped into said second housing (12) by means of said housing cover (13).

7. Torque sensor unit according to one of the preceding claims, characterized in that said magnetic shield (19) has an opening for the passage of a data line and/or a power supply of said sensor element (7).

8. Torque sensor unit according to one of the preceding claims, characterized in that said sensor unit (7) is arranged at a distance from said ring magnet (4) in a radial direction with respect to said longitudinal axis (100).

9. Torque sensor unit according to one of the preceding claims, characterized in that said shield (19) is made of sheet metal.

10. The torque sensor unit according to claim 9, wherein the metal sheet is stamped and bent.

11. Torque sensor unit according to one of the preceding claims 1 to 8, characterized in that said shield (19) is formed of cold-worked metal.

12. An electromechanical steering system for a motor vehicle, the electromechanical steering system comprising: a steering pinion connected to the second partial shaft and engaged with a toothed rack for a steering wheel, the toothed rack being mounted in a third housing such that the toothed rack is displaceable along a longitudinal axis; at least one electric motor for steering force assist; torque sensor unit (1) according to one of the preceding claims, the torque sensor unit (1) being arranged between a first partial shaft (2) and a second partial shaft connected to the steering wheel and detecting a torque introduced into the steering wheel by a driver.

Technical Field

The present invention relates to a torque sensor unit having the features of the preamble of claim 1 and to an electromechanical power steering system for a motor vehicle comprising such a torque sensor unit.

Background

Torque sensors are used in motor vehicles to measure the torque introduced into the steering wheel by the driver. The torque sensors currently used are magnetic sensors, whose measured values may be easily disturbed by external magnetic fields. Motor vehicles will be, and to some extent are, currently operated fully or partly electrically, which may lead to measurements that are influenced by high-intensity external magnetic fields by means of high-ampacity cables, which are usually located in the vicinity of the steering system. The earth's magnetic field can also have interfering effects on the sensors.

The prior art discloses a series of torque sensors with magnetic shields.

Patent US 7,021,161B 2 discloses a steering angle sensor having a first gear wheel connected to an upper steering shaft and engaging with a second, smaller gear wheel, wherein the smaller gear wheel is surrounded by a shield having a cutout for the first gear wheel. The shield defines the magnetic field of the sensor of the second gear.

Publications EP 3276317 a1, EP 3276318 a1 and EP 3239678 a1 disclose torque sensor units comprising a magnetic shield having a C-shaped cross section and circumferentially surrounding a magnetic flux conductor arranged on the lower steering shaft.

Disclosure of Invention

It is an object of the invention to define a torque sensor unit in which the influence of existing external disturbing magnetic fields on the determination of the torque value is reduced and in association with an improved accuracy.

This object is achieved by a torque sensor unit having the features of claim 1 and by an electromechanical power steering system for a motor vehicle comprising such a torque sensor unit. Advantageous developments can be found in the dependent claims.

Accordingly, the present invention provides a torque sensor unit comprising:

a ring magnet which can be connected to the first part-shaft in a rotationally fixed manner and which is arranged concentrically with respect to the longitudinal axis,

two first magnetic flux conductors which can be connected to the second part-shaft, which are arranged in the magnetic field generated from the ring magnet and conduct the magnetic flux,

a spatially fixed sensor unit having two second magnetic flux conductors and a magnetic sensor, which is arranged on a printed circuit board, which are accommodated in a sensor housing of the sensor unit, wherein the sensor unit is designed to detect a change in the angle of rotation between the partial shafts by measuring the magnetic flux density generated between the two first magnetic flux conductors,

-a second housing surrounding the ring magnet, the two first magnetic flux conductors and the sensor unit, wherein the torque sensor unit comprises: a magnetic shield at least partially circumferentially surrounding the sensor unit and arranged between a housing cover enclosing the second housing and the second housing.

The magnetic shield shields the sensor unit from external interfering magnetic fields, so that the signal quality can be significantly improved. The housing cover is preferably formed of steel. The shield is preferably clamped between the housing cover and the second housing.

The magnetic shield preferably has at least one support surface which interacts with the guide in the second housing. This allows the shield to be simply inserted into the second housing.

It may be provided that the ring magnet is also at least partially circumferentially surrounded by a magnetic shield.

The magnetic shield preferably has two arms, each having a first side and a second side, wherein the second side extends parallel to the longitudinal axis and the first side is arranged approximately perpendicular to the longitudinal axis. The arm is preferably rectangular.

To simplify assembly, the arms are connected to each other only by one of the first sides of the arms or one of the second sides of the arms.

In this case, the arms of the shield preferably each extend in a plane parallel to the longitudinal axis.

It may be provided that the magnetic shield has an opening for the passage of the data lines and/or the power supply of the sensor element.

The sensor unit is preferably arranged at a distance from the ring magnet in a radial direction with respect to the longitudinal axis.

In a preferred embodiment, the shield is manufactured from sheet metal. For the purpose of forming the shield, the metal sheet is preferably stamped and bent. It may be provided that the shield is formed from cold worked metal.

The present invention also provides an electromechanical steering system for a motor vehicle, the electromechanical steering system comprising: a steering pinion connected to the second partial shaft and engaged with a toothed rack for a steering wheel, the toothed rack being mounted in a third housing such that it can be displaced along the longitudinal axis; at least one electric motor for steering force assistance, wherein the steering system further comprises the above-mentioned torque sensor unit which is arranged between the first partial shaft and the second partial shaft connected to the steering wheel and which detects the torque introduced into the steering wheel by the driver for the purpose of controlling the steering force assistance.

Drawings

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Throughout the drawings, identical components or components having identical functions are provided with the same reference numerals. In the drawings:

FIG. 1: a three-dimensional view of the torque sensor unit is shown,

FIG. 2: a side view of the fully assembled torque sensor unit in the direction of the longitudinal axis of the shaft is shown,

FIG. 3: a longitudinal cross-section through the torque sensor unit along the line a-a shown in figure 2 is shown,

FIG. 4: a three-dimensional view of the shield is shown,

FIG. 5: several views of the shield from figure 4 are shown,

FIG. 6: showing a three-dimensional view of another shield, an

FIG. 7: several views of the shield from figure 6 are shown.

Detailed Description

Fig. 1 illustrates a torque sensor unit 1, which torque sensor unit 1 measures the rotation of an upper steering shaft 2 relative to a lower steering shaft, not shown, as a measure of the torque manually applied by the driver to the upper steering shaft 2 or to a steering wheel connected to the upper steering shaft 2. The upper steering shaft 2 and the lower steering shaft are coupled to each other in a rotationally elastic manner via a torsion bar, not shown. The torque sensor unit 1 has a rotation angle sensor, which is also referred to as a torque sensor. The servo unit provides steering assistance to the driver based on the torque measured by the torque sensor unit 1.

The torque sensor unit 1 has a ring magnet (permanent magnet) 4, which ring magnet 4 is connected to the upper steering shaft 2 in a rotationally fixed manner and has a plurality of poles. A set of magnetic flux conductors 5 fixed to the lower steering shaft is arranged in the magnetic field generated by the multi-pole magnet 4. Each of the flux conductors 5 is made of a soft magnetic material and has a plurality of claw poles arranged equidistantly in the circumferential direction. The two flux conductors 5 are arranged such that the claw poles of the two flux conductors 5 engage each other. The multi-pole magnet 4 and the assembled magnetic flux conductor 5 are arranged such that the center of each claw pole of the magnetic flux conductor 5 coincides with a magnetic boundary line (i.e., a boundary between the N pole and the S pole) in order to obtain a neutral point at which the output signal (output voltage) of the magnetic field sensor becomes zero if the torsion bar is not twisted (i.e., when no steering force is transmitted between the upper steering shaft and the lower steering shaft).

The flux conductor 5 conducts and "collects" the flux. The spatially fixed sensor unit 7 detects the density of the magnetic flux generated in the air gap between the magnetic flux conductors 5 located opposite to each other in the axial direction.

The sensor unit 7 has a sensor housing 8, which is also referred to below as a first housing, and in this first housing 8 a magnetic flux conductor 9 and a magnetic sensor 11 are arranged, which magnetic sensor 11 is arranged on a printed circuit board 10. The magnetic flux conductors 5, 9 serve to concentrate the magnetic flux on the magnetic sensor 11. The magnetic sensor 11 detects rotation of the upper steering shaft 2 connected to the magnet ring 4 relative to the lower steering shaft connected to the magnetic flux conductor 5. During mounting, the first housing 8 of the sensor unit 7 is inserted into the second housing 12 of the torque sensor unit 1.

In the assembled state, the second housing 12 of the torque sensor unit surrounds the ring magnet 4, the set of magnetic flux conductors 5 and the sensor unit 7. The second housing 12 of the torque sensor unit has a base surface 120 serving as a base, and an outer wall 121 is disposed on the base surface 120, the outer wall 121 serving as an edge and being arranged substantially perpendicularly on the base 120. The outer wall 121 is preferably welded to the base 120. The outer wall 121 and the base 120 are preferably formed as one piece in a stamping operation. Alternatively, the part is prepared in a casting process, preferably in aluminum die casting. The outer wall 121 circumferentially surrounds the entire torque sensor unit 1. The second housing 12 has an opening 123 on one side away from the base. The opening 123 opens the housing 12 toward the upper steering shaft 2. The opening 123 is covered by the housing cover 13. The housing cover 13 has a cutout 130, through which cutout 130 the upper steering shaft 2 passes in the mounted state. The housing cover 13 is connected to, preferably welded to, an inner sleeve 14 of the steering column. The inner sleeve 14 is inserted into the incision 130. The inner sleeve 14 is part of an adjustable steering column. The inner sleeve 14 is surrounded by an outer sleeve, not shown, and the two sleeves are designed to telescope relative to each other.

The second housing 12 has a housing opening 124 in the edge 121 in the region of the sensor element 7. The sensor element 7 can be connected to a data line and to a power supply via the housing opening 124.

The sensor housing 8 is fixed to the second housing 12 by means of screws 129. The housing cover 13 is also screwed firmly to the second housing 12.

The sensor unit 7 is surrounded by a first housing 8 having a first region 81, the first region 81 accommodating therein the magnetic flux conductor 9, the printed circuit board 10, and the magnetic sensor 11. In a second region 82 adjoining the first region 81, the first housing 8 is configured with a T-shaped longitudinal cross section. To form this T-shape, the first housing 8 has a neck 83, which neck 83 extends in radial direction of the longitudinal axis 100 of the torque sensor unit and abuts a transversely positioned web 84 when the sensor unit 7 is in the assembled state. The transversely oriented webs 84 are plate-shaped and in the mounted state lie on both sides, in each case on inwardly directed projections 18 of the edge 121 of the second housing 12. Each projection has two contact surfaces 181, 182, which contact surfaces 181, 182 form a kind of guide for introducing the sensor unit 7 into the second housing 12.

The second housing 12 is made of aluminum and is therefore not suitable for shielding magnetic fields.

An additional shielding 19 is required, which shielding 19 at least partially surrounds the sensor housing 8 and is accommodated together with the sensor housing 8 in the second housing 12 of the torque sensor unit. The shield case 19 is formed of a magnetically conductive material. Soft magnetic materials with a high degree of permeability, such as nickel-iron alloys or iron-silicon alloys, are particularly suitable. The shield case 19 has two substantially rectangular arm portions 21 connected via a rear side portion 20. The shield 19 is illustrated in detail in fig. 4 to 6. The two arms 21 project substantially perpendicularly from the rear side 20, the rear side 20 engaging on one of the first sides of the arms 22 extending in a plane perpendicular to the longitudinal axis 100. On the side facing away from the sensor, the arms 21 each have an inwardly directed curved portion 24 on one of the two sides 23. The arms 22 each have a cut-out 25, which cut-out 25 extends parallel to the longitudinal axis of the shaft 100 and serves as a guide for: which is used to push the shield onto a projection arranged on the base 120 of the second housing 12. The projection is located between the shaft and the inwardly directed projection 18. The entire shield 19 is located below the projection 18. The arm portion 21 shields the entire sensor unit 7 toward the side. Between the bent portions 24, openings 26 are formed through which openings 26 connections for the sensor unit 7 can pass. The shielding 19 is open on the side remote from the gear. In the present embodiment, during assembly of the torque sensor unit 1, the shield case 19 is first inserted into the second housing 12, and then the sensor unit 7 is inserted into the second housing 12. In a next step, the housing cover 30 closes the shielding cap 19 on the side facing away from the gear. Thus, during assembly, the shield 19 is clamped between the second housing 12 and the housing cover 13 and fixed in this position. The shield cover 19 and the housing cover 13 form a closed box that shields the interfering magnetic fields. The housing cover 13 is preferably made of steel.

Fig. 2 and 3 show the torque sensor unit 1 fully assembled. In a further embodiment, provision may be made for the two arm portions to be connected by means of a second side portion of the arm portion extending parallel to the longitudinal axis. In this case, the connecting wall is located on the side remote from the ring magnet. The connecting wall has a cutout that at least partially surrounds the neck of the sensor unit. In this case, the sensor unit is first introduced into the second housing and then the shielding cage is introduced into the second housing during assembly. In the mounted state, the connecting wall is located between the protruding portion of the second housing and the first region of the sensor housing.

Fig. 6 and 7 show another embodiment of a shield can 190, the shield can 190 in the mounted state completely circumferentially surrounding the sensor housing except for a small interruption 193 through which the neck of the first housing passes. The rear portion 20 of the shield case 190 has a circular opening 191 through which the shaft passes. The edge 192 having the interruption 193 in the region through which the neck of the first housing passes extends approximately perpendicularly from the circumferential side of the rear side 20. The shield 190 is sized such that the shield 190 circumferentially surrounds the flux conductor and the ring magnet. The shield 190 has a cutout 25 in the rear side 20 and in the edge 192, which cutout extends parallel to the longitudinal axis of the shaft and serves as a guide for: the guide is used to push the shield cover onto a projection arranged on the base of the second housing. As already described above, during assembly, the shield can 190 is also clamped between the second housing and the housing cover. As such, the housing cover overlaps the edge 192 and is located on an end side of the edge.