0001]The present invention constitutes a torque detection device used in an electrical power steering device of a vehicle, to a yoke cover to be assembled to the two electromagnetic yokes facing in the axial direction.
Background technique
[0002]An electric power steering apparatus for a vehicle, detected by the torque detector steering torque generated by the operation of the steering wheel by the driver (torque sensor), the steering burden of the driver by applying a steering assist force by the motor to a steering system it is intended to mitigate (e.g., see Patent documents 1-3).
　In the example shown in partial cut-away side view of Figure 9, thereby achieving a reduction in the force required of the electric motor 30 to operate the steering wheel 21 as the source of auxiliary power (e.g., see Patent Document 1).
　Here, when the steering apparatus for a vehicle will be described by way of example in FIG. 9, the rotation of the steering wheel 21 is transmitted to the input shaft 23 of the steering gear unit 22, the pair of left and right tie rods 24 and 24 with the rotation of the input shaft 23 by being pushed and pulled, the steering angle is applied to the front wheels. Steering wheel 21 is supported on the rear end portion of the steering shaft 25, the steering shaft 25 is fixed to the vehicle body is rotatably supported by the steering column 26. The front end of the steering shaft 25 is connected to the rear end of the intermediate shaft 28 via a universal joint 27, the front end of the intermediate shaft 28 is connected to the input shaft 23 via a universal joint 29.
[0003]
　Then, cross-sectional view of FIG. 10, and with reference to the enlarged view of FIG. 11, an example of a more specific structure of the electric power steering apparatus. Steering column 26a is a inner column 31 and the outer column 32 are those comprising a combination of full length to be contracted during the secondary collision, it is supported on the vehicle body. A steering shaft 25a that is rotatably supported inside the steering column 26a is a lower shaft 33 and upper shaft 34, to permit torque transmission, and, comprising a combination of full length to be contracted at the time of a secondary collision. The rear end portion of the upper shaft 34 protruding from the rear end opening of the outer column 32, a steering wheel 21 (see FIG. 9) is fixed. The front end portion of the inner column 31, the housing 35 is coupled fixed, the front half portion of the lower shaft 33 is inserted inside the housing 35. Inside the housing 35, the front side of the lower shaft 33 is an input shaft, an output shaft 36 is rotatably supported by a pair of ball bearings 37 and 38. The output shaft 36 and lower shaft 33 are linked via a torsion bar 39. The front end portion of the output shaft 36 projecting from the front end opening of the housing 35, the universal joint 27 (see FIG. 9) is coupled.
[0004]
　The rear end portion of the output shaft 36, the cylindrical portion 40 is provided. The outer peripheral surface of the cylindrical portion 40, the circumferential groove 41 is provided over the entire circumference in the circumferential direction. In contrast, on the inner peripheral surface of the cylindrical portion 40, the female stopper portion 42 of the concave-convex shape in the circumferential direction is provided. On the other hand, the front end portion of the outer peripheral surface of the lower shaft 33, the outer diameter (diameter of the circumscribed circle) is smaller than near the front end portion, the male stopper 43 of the uneven shape is provided in the circumferential direction. The male stopper portion 43, and the female stopper portion 42, can be recess-projection engaging a relative rotation in a predetermined angle range. Thus, excessive twisting prevention of the torsion bar 39 is achieved.
　Lower shaft 33 is made of steel as a magnetic metal, the front end portion close of the outer peripheral surface of the lower shaft 33, the torque detecting concave and convex portion 44 of the concave-convex shape in the circumferential direction is provided. The outer diameter side of the torque detecting concave and convex portion 44, the cylindrical torque-detecting sleeve 45 made of non-magnetic metal having conductivity such as an aluminum alloy is arranged. Proximal end of the torque detection sleeve 45 is fitted on the cylindrical portion 40 fixed. In this state, in order to position and preventing deformation in the axial direction of the torque detection sleeve 45, the edge portion of the base end portion of the torque detection sleeve 45 is crimped to the circumferential groove 41. The portion of the torque detection sleeve 45 located on the outer diameter side of the torque detecting concave and convex portion 44, a plurality of window holes 46a, 46b are provided. The outer diameter side of the torque detecting concave and convex portion 44 and a torque detecting sleeve 45, the torque detector 47 fixed fitted into the housing 35 is arranged.
[0005]
　The rear end portion of the output shaft 36, the worm wheel 48 is fixedly fitted, the worm wheel 48, worm 49 which is rotatably supported by the housing 35 is engaged. Worm wheel 48 and the worm 49 constituting a worm reduction gear 50.
　The housing 35, the electric motor 30 (see FIG. 9) is supported fixed, the output shaft of the electric motor 30, the proximal end portion of the worm 48, is coupled to torque transmission.
　If the electric power steering apparatus configured as described above, by the driver operates the steering wheel 21, the torque is steering force to a steering shaft 25a is applied, depending on the direction and magnitude of the torque only minute, the torsion bar 39 is twisted elastically. Accordingly, by the circumferential positional relationship between the torque detecting concave and convex portion 44 and the torque-detecting sleeve 45 varies, the impedance change occurs in the coil constituting the torque detection unit 47. Therefore, based on this impedance variation, it can detect the direction and magnitude of the torque. Electric motor 30 generates auxiliary power corresponding to the detection result of the torque. The auxiliary power after being increased by the worm reduction gear 50, is imparted to the output shaft 36. As a result, the force required for the driver to operate the steering wheel 21 is reduced.
[0006]
　Next, partial cross-sectional perspective view of FIG. 12, and with reference to the exploded perspective view of FIG. 13 will be described torque sensor 47 constituting a torque detecting device of Patent Document 3.
　Torque detecting unit 47, a torque detecting concave and convex portion 44 formed in the lower shaft 33, the detection coil 13a and 13b of the pair disposed inside the housing 35, the torque detection sleeve disposed therebetween and a 45.
　The outer periphery of the torque detecting sleeve 45 is surrounded by an electromagnetic yoke 15a and 15b for holding the coil bobbin 18 detection coil 13a and 13b of the same standard are wound. That is, the detection coils 13a, 13b are arranged coaxially with the torque-detecting sleeve 45, the detection coil 13a surrounds the first window row portion consisting of the window hole 46a, the detection coil 13b and the second consisting of the window hole 46b surrounding the Madoretsu part.
[0007]
　Furthermore, the torque detecting section 47, the coil 13a, 13b are two coil bobbin 18 having the same shape that are wound respectively, used facing each other.
　The lateral end of the flange portion 18b of the coil bobbin 18, the terminal mounting portion 18e constituting the coil-side connector connectable to a board-side connector is formed and positions the terminal mounting portions 18e on the upper end portion of the coil bobbin 18 the perpendicular line passing through the center of the coil bobbin 18 in the state as a symmetric axis, the position of the line symmetry, regulating portion 18d is formed.
　Restricting portion 18d includes a base portion in which a part of the flange portion 18b is protruded radially outwardly, the base portion to one region obtained by equally dividing the circumferential direction, formed to protrude toward the outside in the axial direction of the coil bobbin 18 It was composed of the convex portion. In other words, the two coil bobbins 18, in a state of arranging the flange portion 18b so as to face on the same axis, both the regulating portion 18d is abutted in the circumferential direction, and the structure in which the relative position of the rotation angle direction is determined going on.
　Terminal mounting part 18e is a substantially rectangular parallelepiped member which projects further radially outward from the side surface upper portion of the flange portion 18b, the upper surface thereof, two terminal 18f for connecting the board side connector is press-fitted It is. These two coil terminals 18f are disposed parallel to, and is fixed so as to protrude from the upper surface of the terminal mounting portion 18e radially outward.
　Furthermore, on one side portion of the terminal mounting portion 18e, plate-like guide portion 18g projecting further radially outward from the upper surface of the terminal mounting portion 18e is formed.
[0008]
　Electromagnetic yoke 15a and 15b is a member of the same shape, a cylindrical portion 15d fitted around the coil bobbin 18, a ring-shaped bottom portion 15e formed at an end portion facing axially outward as it is fixed to the coil bobbin 18 are composed of the inner diameter of the bottom portion 15e has a inner diameter the same size as the cylindrical portion of the coil bobbin 18 (groove portion 18c).
　The electromagnetic yoke 15a and 15b, the end portion opposite to the bottom portion 15e of the cylindrical portion 15d, 3 one recess 15c are spaced apart by a predetermined angle in the circumferential direction.
　Here, one of the yoke cover 14 is a substantially ring-shaped member, in its outer peripheral surface, three projections 14a are spaced apart by a predetermined angle in the circumferential direction.
　Yoke cover 14, the electromagnetic yoke 15a, in a state in which is fitted the protrusion 14a to the recess 15c and 15b, are pressed into the inner diameter of the opposing two electromagnetic yokes 15a, both of 15b the cylindrical portion 15d.
　The configuration of the yoke cover 14 as described above, the torque detecting device of Patent Document 3, with respect to the torque detecting device of Patent Document 2, reduction of component count and electromagnetic yoke 15a, press-fit the number of yoke cover 14 to 15b It has achieved a reduction.
CITATION
Patent Document
[0009]
Patent Document 1: WO 2014/199959 Patent Publication
Patent Document 2: WO 2004/018987 pamphlet
Patent Document 3: JP 2014-122869 JP
Summary of the Invention
Problems that the Invention is to Solve
[0010]
　One of the yoke cover 14 in the torque detecting device of Patent Document 3, the axial end portions of two electromagnetic yokes 15a of the cylindrical surface of the non-projecting portion 14a, so press-fitted into the 15b fitted, the cylindrical yoke cover 14 it is necessary to increase the accuracy of the surface.
　Further, since it is designed to have a strong holding force in a state in which both axial ends of the cylindrical surface in the axial direction two electromagnetic yokes 15a, fitted is pressed to 15b of the yoke cover 14, the outer peripheral surface corner R portions 14b for improving the press-fitting to a portion is formed.
　Yoke cover 14, while along the corner R portion 14b when pressed electromagnetic yoke 15a, a 15b, since the cylindrical surface of the non-protruding portion 14a is a portion to be fitted, the circumferential length of the portion to be press-fitted long, there is a case where the force required to press-fit becomes the working efficiency and greatly decreases.
[0011]
　Here, the common punching press working Consider an example of obtaining a punched member.
　As shown in enlarged longitudinal sectional view of FIG. 14 (a), the case of performing the punching pressing push the punch P at a plate material W having a thickness of T on the die D, the portion undergoing shear deformation by the machining It is limited clearance c portion and its very near range.
　Then, the punched M punched by punching press working shown in enlarged front view in FIG. 14 (b), is formed with high precision smooth shear plane A is the lower end E1 side, the precision in the upper end E2 side high smooth shear plane is not formed.
　In addition, the punched member M, sagging B vent below the shear plane A is the fracture surface C is formed above the shear plane A.
[0012]
　As described above, only performing such common punching press work, since the shear surface is not only formed on one side, it can not be obtained yoke cover that can be pressed into the two electromagnetic yokes like.
　Here, in order to be able to press-fit the two electromagnetic yokes, it and performing shaving or the like after punching press process, by performing special processing of fine blanking or the like instead of the punching press working, the thickness it is conceivable to form a highly accurate smooth shear plane direction over the entire surface.
　Also, the corner R portion which forms at both ends in the axial direction in order to improve the press-fitting property, it is necessary to form performs different processing.
　Therefore, the yoke cover in the torque detecting device of Patent Document 3, but in which there is a feature of reducing such components count, aspect and of increasing the efficiency of the work of assembling the yoke cover the electromagnetic yoke, to reduce the manufacturing cost see in terms of that there is room for improvement.
[0013]
　An object of the present invention is to increase the efficiency of the work for assembling the one yoke cover two electromagnetic yokes constituting a torque detecting apparatus, and in that to reduce the manufacturing cost of the yoke cover.
Means for Solving the Problems
[0014]
　When performing punching press working as shown in FIG. 14 (a), the as said, the punched member M in FIG. 14 (b), the precise smooth shear plane A is formed on the lower end E1 side, the shear surface sag B vent below the a is the fracture surface C is formed above the shear plane a.
　In contrast, the inner surface defining the hole of the plate material W after punching the punched member M by punching press processing of FIG. 14 (a), a highly accurate smooth shearing surface on the upper end E2 side is formed, sagging vent above the shear plane, fracture surface downward is formed than the shear plane.
　Inventors of the present application, first, such a punching press working a plate thickness direction of the shear plane formed by the position and location of vent sagging and breaking surface is formed by the direction of the punch against the plate material comprising the product changing it, and punching sag focused to become the corner R portions for enhancing the press-fitting property.
　The inventors of the present application is formed on the outer peripheral surface of the yoke cover, one shear surface and the shearing surface to the other is Meawasa it is that Meawasa two electromagnetic yokes, changes direction punched in the circumferential direction of the portion inspired of forming, and have completed the present invention by advancing the study and prototype evaluation, etc. based on such idea.
　Further, the inventors have found that the shape of the yoke cover obtained by such a punching press working, be formed by a processing method other than the punching press working, while maintaining the workability of assembling the electromagnetic yoke manufacturing focusing also that there is a possibility of reducing the cost.
[0015]
　That is, the yoke cover according to the present invention, because of the problem solving,
impedance changes depending on the torque generated in the rotary shaft, a detection coil paired, the torque based on the output voltage of the detecting coil constituting a torque detecting device for detecting, as sandwiched between two electromagnetic yoke facing each other in the axial direction, for holding the two said is Meawasa the inner diameter of the cylindrical portion of the electromagnetic yoke two electromagnetic yoke 1 one of a yoke cover,
　the conjunction forms one on the first cylindrical surface is Meawasa of the two electromagnetic yoke plurality of first circumferential portion of the outer peripheral surface, is Meawasa the other of said two electromagnetic yoke form two cylindrical surfaces to a plurality of second circumferential portion which is offset from the first circumferential portion in a circumferential direction of the outer peripheral surface,
　than the first cylindrical surface of one side of the said electromagnetic yoke To form a corner R portion in the direction part, than the second cylindrical surface, characterized in that by forming a corner R portion in axial section of the other side of the electromagnetic yoke (claim 1).
[0016]
　In such a yoke cover, the cylindrical surface to be Meawasa the electromagnetic yoke, with divided into a second cylindrical surface is Meawasa the first cylindrical surface and the other of the electromagnetic yoke on one of the electromagnetic yoke is Meawasa, first cylindrical It is formed at a position where the surface and the second cylindrical surface is shifted in the circumferential direction.
　Further, the corner R portion is formed on one nearer axial portion of the electromagnetic yoke than the first cylindrical surface, the corner R portion in the axial direction part of the other side of the electromagnetic yoke than the second cylindrical surface is formed there.
　Therefore, the yoke cover when Meawaseru the two electromagnetic yokes, with the required force from the shorter circumferential length of the portion to Awa fitting is reduced, the corner R portion formed at the corner portion of the portion for Awa fit it is possible to Awa wearing electromagnetic yoke along, it can improve the working efficiency.
[0017]
　Here, the other closer axial portion of said first electromagnetic yoke than the cylindrical surface, tapered outer diameter is gradually reduced as the distance in the axial direction from an axial end edge of the first cylindrical surface to form a surface, the one closer axial portion of said second cylindrical surface electromagnetic yoke than gradually decreases the outer diameter as the distance in the axial direction from an axial end edge of said second cylindrical surface preferably by forming a tapered surface (claim 2).
　In such a yoke cover, and forming at a position shifted a first cylindrical surface and second cylindrical surface in the circumferential direction, the tapered surface in the axial portion of the other side of the electromagnetic yoke than the first cylindrical surface formed, to form the tapered surface in the axial portion of one side of the electromagnetic yoke than the second cylindrical surface.
　Therefore, small area of the cylindrical surface is necessary to improve the accuracy, since less accurate machining surface can reduce the manufacturing cost of the yoke cover.
[0018]
　Further, the yoke cover according to the present invention, because of the problem solving, impedance changes depending on the torque generated in the rotary shaft, a detection coil paired, the torque based on the output voltage of the detecting coil constituting a torque detecting device for detecting, as sandwiched between two electromagnetic yoke facing each other in the axial direction, for holding the two said is Meawasa the inner diameter of the cylindrical portion of the electromagnetic yoke two electromagnetic yoke 1 one of a yoke cover,
　the one on the first cylindrical surface which Meawasa of two electromagnetic yokes are formed in a plurality of first circumferential portion of the outer peripheral surface, the second to be Meawasa the other of said two electromagnetic yoke cylindrical surface is formed in a plurality of second circumferential portion which is offset from the first circumferential portion in a circumferential direction of the outer peripheral surface,
　said first cylindrical surface and said second cylindrical surface, punching press Characterized in that it is a shear plane formed by changing the punching direction by Engineering (claim 3).
[0019]
　In such a yoke cover, the cylindrical surface to be Meawasa the electromagnetic yoke, with divided into a second cylindrical surface is Meawasa the first cylindrical surface and the other of the electromagnetic yoke on one of the electromagnetic yoke is Meawasa, first cylindrical It is formed at a position where the surface and the second cylindrical surface is shifted in the circumferential direction.
　Further, in one closer axial portion of the electromagnetic yoke than the first cylindrical surface, with the square R unit is formed by punching sagging of punching press working, the axial portion of the other side of the electromagnetic yoke than the second cylindrical surface the corner R portion is formed by punching sagging of punching press working.
　Therefore, the yoke cover when Meawaseru the two electromagnetic yokes, with the required force from the shorter circumferential length of the portion to Awa fitting is reduced, the corner R portion formed at the corner portion of the portion for Awa fit it is possible to Awa wearing electromagnetic yoke along, it can improve the working efficiency.
　Moreover, while being formed in a position where the first cylindrical surface and second cylindrical surface is shifted in the circumferential direction, a fracture surface of the punching press working in the axial direction part of the other side of the electromagnetic yoke is formed than the first cylindrical surface , fracture surface of the punching press working in the axial direction portion of one side of the electromagnetic yoke is formed than the second cylindrical surface.
　Therefore, small area of the cylindrical surface is necessary to improve the accuracy, since less accurate machining surface can reduce the manufacturing cost of the yoke cover.
[0020]
　Still further, the first cylindrical surface and second cylindrical surface on the other of the electromagnetic yoke are Meawasa that on one of the electromagnetic yoke is Meawasa is because a shear surface formed by changing the punching direction by punching press working, punching those formed by performing a shaving process or the like after pressing or, not have been formed by performing a special process of fine blanking or the like instead of the punching press working.
　Moreover, by punching press work, efficiency since the vent sagging is formed on the other of the electromagnetic yoke side portions than the portion and the second cylindrical surface of the first cylindrical surface one electromagnetic yoke side than the work fit since the corner R portions for performing well is automatically formed by punching press working for forming the first cylindrical surface and second cylindrical surface, additional machining to form the corner R portion is not required.
　Therefore, it is possible to further reduce the manufacturing cost of the yoke cover.
[0021]
　Here, between the first cylindrical surface and said second cylindrical surface adjacent said first cylindrical surface and the flat or curved surface portion located radially inward from the virtual cylindrical surface including the second cylindrical surface formed preferably formed by (claim 4).
　Moreover, the the outer circumferential surface protrusions projecting radially outward from the inner diameter of the electromagnetic yoke formed with a plurality of circumferentially first cylindrical surface and said second cylindrical surface between adjacent groups of said protrusion together but are formed one by one, between the first cylindrical surface and said second cylindrical surface adjacent arranged radially inward of the virtual cylindrical surface including the first cylindrical surface and said second cylindrical surface preferably flat or curved portion is formed (claim 5).
　According to these, such as configuration, the in position near the first cylindrical surface and an axial center in a position near the center in the axial direction towards the one electromagnetic yoke toward the other of the electromagnetic yoke 2 between the cylindrical surface, is spaced apart said first cylindrical surface and the first cylindrical surface to form a flat or curved surface portion located radially inward from imaginary cylindrical surface containing said second cylindrical surface and second cylindrical surface since it is, the switching unit between the first cylindrical surface and second cylindrical surface adjacent never affect the work fit to the electromagnetic yoke.
　Moreover, since no directivity in the axial direction, the direction at the time of working fit (Table, back) is not necessary to consider the.
　Thus, the workability can be improved at the time of Awa fit the yoke cover the opposing two electromagnetic yoke.
[0022]
　Torque detecting apparatus according to the present invention, the impedance changes according to torque generated in the rotary shaft, a detection coil in a pair, a torque detector for detecting the torque based on the output voltage of the detecting coil are those provided with the yoke cover (claim 6).
[0023]
　Electric power steering apparatus according to the present invention, an electric power steering apparatus for applying a steering assist force to a steering system of a vehicle, and the torque detector for detecting steering torque input to the steering mechanism, the torque detecting device in on the basis of the detected steering torque, in which a motor control unit for driving and controlling the electric motor to impart the steering assist force (claim 7).
[0024]
　Method for producing a yoke cover according to the present invention, because of the problem solving,
impedance changes depending on the torque generated in the rotary shaft, a detection coil in a pair, the torque based on the output voltage of the detecting coil constituting a torque detecting device for detecting, as sandwiched between two electromagnetic yoke facing each other in the axial direction, for holding the two said is Meawasa the inner diameter of the cylindrical portion of the electromagnetic yoke two electromagnetic yoke a one manufacturing process of the yoke cover,
　relative to plate, the one on the first cylindrical surface is Meawasa two electromagnetic yokes, so as to form a shear plane to a plurality of first circumferential portion of the outer peripheral surface a first punching step of forming by press punching the first cylindrical surface,
　with respect to the plate which has undergone the first punching step, the other of the two electromagnetic yoke A second cylindrical surface that Meawasa, so as to form a shear plane to a plurality of second circumferential portion which is offset from said first circumferential portion of the outer peripheral surface in the circumferential direction, by press punching the second cylindrical surface formed, and having a second punching step of varying the first punching step and the punching direction (claim 8).
[0025]
　According to the method for producing a yoke cover, by punching press process comprising the first punching step and the second punching step changed the punching direction, of the first cylindrical surface and the other to be Meawasa on one of the electromagnetic yoke since the second cylindrical surface in the electromagnetic yoke is Meawasa is formed as a shear plane, with no need to perform the shaving or the like after punching press working, not performing also a special process, such as fine blanking.
　Thereon by punching press working, part of the first cylindrical surface one electromagnetic yoke side of, and on the other electromagnetic yoke side portion than the second cylindrical surface, since the vent sagging are formed, fitting work the so corner R portions for efficiently performed is automatically formed by punching press working for forming the first cylindrical surface and second cylindrical surface, additional machining to form the corner R portion is not required.
　Thus, it is possible to reduce the manufacturing cost of the yoke cover.
[0026]
　Here, between the first cylindrical surface and said second cylindrical surface adjacent the flat or curved surface portion located radially inward from the virtual cylindrical surface including the first cylindrical surface and said second cylindrical surface formed preferably to formed by (claim 9).
　Further, the yoke cover, which projections projecting radially outward from the inner diameter of the electromagnetic yoke on the outer peripheral surface is formed with a plurality of circumferentially said between adjacent groups of said protrusion first the first cylindrical surface and said second cylindrical surface and forming one, between the first cylindrical surface and said second cylindrical surface adjacent imaginary cylindrical surface including the first cylindrical surface and said second cylindrical surface the by forming a flat or curved surface portion located radially inward from preferably (claim 10).
　According to these manufacturing methods, such as a shear surface formed by changing the punching direction by punching press working, first cylindrical surface and the shaft in a position near the direction of one of the electromagnetic yoke from the center of the axial direction between the second cylindrical surface from the center in a direction at a position closer towards the other electromagnetic yoke plane located radially inward from the virtual cylindrical surface including the first cylindrical surface and said second cylindrical surface or since it is separated a first cylindrical surface and second cylindrical surface forms a curved surface portion, never switching unit between the first cylindrical surface and second cylindrical surface adjacent affects the work fit to the electromagnetic yoke .
　Moreover, since no directivity in the axial direction, the direction at the time of working fit (Table, back) is not necessary to consider the.
　Thus, the workability can be improved at the time of Awa fit the yoke cover the opposing two electromagnetic yoke.
[0027]
　Method of manufacturing an electric power steering apparatus according to the present invention is a manufacturing method of an electric power steering apparatus for applying a steering assist force to a steering system of the vehicle, constituting a torque detecting apparatus for an electric power steering apparatus, in the axial direction the inner diameter of the cylindrical portion of the two electromagnetic yokes facing each other, is intended to include the step of Awa fit the yoke cover manufactured by the manufacturing method (claim 11).
Effect of the invention
[0028]
　As described above, according to the yoke cover and the manufacturing method thereof according to the present invention, it is possible to improve the efficiency of the work for assembling the one yoke cover two electromagnetic yokes constituting a torque detecting device, the manufacturing cost of the yoke cover a marked effect of such can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029]
It is a perspective view of the yoke cover according to the embodiment of FIG. 1 the present invention.
[2] also (a) is a front view, (b) is a fragmentary enlarged front view.
[FIG 3] (a) is a plan view of the yoke cover, is an arrow sectional view taken along line X-X of (b) is (a).
[FIG. 4] (a) is a plan view of an electromagnetic yoke, is an arrow Y-Y cross-sectional view of (b) is (a).
FIG. 5 is an exploded perspective view of the yoke cover and two electromagnetic yoke.
[Figure 6] is a front view showing a state where press-fitting the yoke cover the inner diameter of the cylindrical portion of the two electromagnetic yokes, other components that constitute the torque detecting apparatus is omitted.
[Figure 7] is an explanatory view showing an example of a manufacturing method of a yoke cover according to the preferred embodiment of the present invention, showing (a) shows a first punching step, (b) a second punching step.
[Figure 8] is an explanatory view showing another example of a method for manufacturing a yoke cover according to the preferred embodiment of the present invention, showing (a) shows a first punching step, (b) a second punching step .
9 is a partial cut-away side view of the steering apparatus.
It is a cross-sectional view of FIG. 10 electric power steering device.
11 is an enlarged view of the left end upper half in FIG. 10.
It is a partial cross-sectional perspective view of FIG. 12 torque detector.
FIG. 13 is an exploded perspective view of the torque detector shown by omitting the detection coil.
[FIG. 14] (a) is a fragmentary enlarged vertical sectional view showing an example of a typical punching press working, (b) is an enlarged front view showing a punched punched by punching press working (a).
DESCRIPTION OF THE INVENTION
[0030]
　Next will be described an embodiment based on the accompanying drawings of the present invention, the present invention is, all embodiments meet the requirements referred to in the invention is not limited to that shown in the accompanying drawings forms claims including is Dressings.
[0031]
　Yoke cover of the present invention has the same function as the yoke cover constituting a torque detecting device of Patent Document 3 (yoke cover 14 of FIG. 12 and FIG. 13), the two electromagnetic yoke facing each other in the axial direction as sandwiched, the inner diameter of the cylindrical portion of the two electromagnetic yokes are those Meawasa.
　The torque detecting device of the present invention has the same function as the torque detecting device of Patent Document 3 (torque detecting apparatus comprising a torque detecting portion 47 of FIG. 12), opposite directions in response to torque generated in the rotary shaft to, or impedance changes in the same direction, a detection coil in a pair, and detects the torque based on the output voltage of the detection coil.
　Furthermore, the electric power steering apparatus of the present invention are those having the same function as the electric power steering apparatus of Patent Document 1, and the torque detector for detecting steering torque input to the steering mechanism, the torque detecting device in on the basis of the detected steering torque, in which a motor control unit for driving and controlling the electric motor to impart the steering assist force.
[0032]
　Perspective view of FIG. 1, as shown in a plan view and a cross-sectional view shown in FIG. 3 (b) of the front view and enlarged front view of FIG. 2 (b), and FIGS. 3 (a) of FIG. 2 (a), yoke cover 1 according to the embodiment of the present invention is a substantially ring-shaped member, in its outer peripheral surface F, the first cylindrical surface 2a is formed on the first circumferential portion F1 of the three, first round second cylindrical surface 2b is formed in the second circumferential portion F2 of the three positions offset from the direction portion F1 in the circumferential direction. The first cylindrical surface 2a and the second cylindrical surface 2b are alternately arranged in the circumferential direction.
　Here, first circumferential portion F1 and the second circumferential portion F2 and the protruding portion 1a forms a first cylindrical surface 2a and the second cylindrical surface 2b may if two or more places.
　The yoke cover 1 of the present embodiment, the circumferential equal intervals in the three projections 1a are formed, projecting portion 1a adjacent, between 1a, first cylindrical surface 2a and the second cylindrical surface 2b is one It is formed.
　Further, the planar portion 5 is formed between the projecting portion 1a, the first cylindrical surface 2a and the second cylindrical surface 2b adjacent between 1a.
　Furthermore, the planar portion 6 between the projecting portion 1a and the first cylindrical surface 2a is planar portion 7 is formed between the projecting portion 1a and the second cylindrical surface 2b.
　The planar portions 5, 6 and 7 may be a rather may be a curved surface, a surface located radially inward from imaginary cylindrical surface including a first cylindrical surface 2a and the second cylindrical surface 2b plane .
[0033]
　The first cylindrical surface 2a and the second cylindrical surface 2b is in punching press processing by a shearing surface formed by changing the punching direction, first cylindrical surface 2a is one axial direction (Figures 1 and 2 at a position offset downward), second cylindrical surface 2b is formed at a position offset to the other axial (upward in FIGS. 1 and 2). Then, as shown in FIG. 2 (b), the first cylindrical surface 2a is located on the lower side than the axial center (center of the plate thickness T), a second cylindrical surface 2b on the upper side than the axial center To position.
　Further, since the first cylindrical surface 2a is sheared surfaces formed by press punching, punching sag (angular axial one (lower in FIG. 1 and FIG. 2) close to the R-shape of the first cylindrical surface 2a R part) 3a is, fracture surface 4a is formed above) closer in the axial direction of the other (Figures 1 and 2 of the first cylindrical surface 2a.
　Similarly, the second cylindrical surface 2b is, since changing the punching pressing and punching direction to form a first cylindrical surface 2a is a shear plane formed by punching press work, one axial direction of the second cylindrical surface 2b fracture surface 4b to close (downward in FIGS. 1 and 2), the axial direction of the other vent sagging (corner R portion) of the R shape toward (upward in FIGS. 1 and 2) 3b of the second cylindrical surface 2b is formed It is.
　Here, fracture surface 4a from the upper edge of the first cylindrical surface 2a toward the upward (from the upper edge of the first cylindrical surface 2a as the distance in the axial direction) outer diameter decreases gradually tapered a surface, fracture surface 4b is tapered to an outer diameter toward downward from the lower end edge of the second cylindrical surface 2b (as the distance from the lower edge of the second cylindrical surface 2b in the axial direction) gradually decreases which is the surface.
[0034]
　Plan view and FIG. 4 a cross-sectional view of (b) of FIG. 4 (a), and as shown in the exploded perspective view of FIG. 5, two electromagnetic yokes 11a to the yoke cover 1 is pressed, 11b are members of the same shape a is composed of a coil bobbin (not shown) and a cylindrical portion 11d fitted around a ring-shaped bottom portion 11e formed at an end portion facing axially outward when secured to the coil bobbin.
　The electromagnetic yoke 11a, 11b is on the opposite side of the end portion and the bottom portion 11e of the cylindrical portion 11d (an end portion of the yoke cover 1 side), along with three recesses 11c circumferentially equal intervals is formed, adjacent recesses 11c, 11c notch 11f is formed between the. Recess 11c and the notch portion 11f are alternately arranged in the circumferential direction. In Figure 5, but is longer than the circumferential length of the recess 11c circumferential length of the notch 11f, these large and small does not matter.
　Here, the cutout portion 11f, the coil bobbin terminal mounting portion (see the coil bobbin 18 of FIG. 13) (see the terminal mounting portion 18e of FIG. 13) is engaged.
[0035]
　Exploded perspective view of FIG other components that constitute the torque detecting device which are omitted, and as shown in the front view of FIG. 6, the yoke cover 1 two electromagnetic yokes 11a, 11b of the cylindrical portion 11d of when press-fitting the inner diameter, the first cylindrical surface 2a of the three positions with fitted is pressed into the electromagnetic yoke 11a, a second cylindrical surface 2b of the three is fitted is pressed to the electromagnetic yoke 11b.
　The first cylindrical surface 2a of the yoke cover 1 is fitted to the inner surface of the engaging protrusion G1 electromagnetic yoke 11a, the inner surface a second cylindrical surface 2b of the yoke cover 1 is engaged protrusion G2 electromagnetic yoke 11b It fits into. Further, the protruding portion 1a of the yoke cover 1 is engaged electromagnetic yoke 11a, the concave portion 11c of the 11b, the 11c.
　When press-fitting the yoke cover 1 as shown in FIG. 5 electromagnetic yoke 11a, and 11b, unplug sagging 3a of R shape in the yoke cover 1, since there is a 3b (see also FIG. 1), the press-fitting is improved.
　When assembled in this way two electromagnetic yokes 11a, a yoke cover 1 to 11b, since the first cylindrical surface 2a and the second cylindrical surface 2b of the yoke cover 1 has a high smooth shear plane precision, the electromagnetic yoke 11a, 11b of the cylindrical portion 11d, a stable firm holding power was in a state of fitted by press-fitting the yoke cover 1 to the inside diameter of 11d has occurred.
　Here, the press-fitting depth when the yoke cover 1 is pressed electromagnetic yoke 11a, and 11b are regulated, the protrusion 1a and the electromagnetic yoke 11a of the yoke cover 1 as shown in FIG. 6, the recess 11c of 11b, by the 11c is, depth of less than half the thickness of the yoke cover 1 is pressed.
　Incidentally, the yoke cover 1 and the electromagnetic yoke 11a, the fitting between 11b, electromagnetic yoke 11a and the yoke cover 1, an electromagnetic yoke 11a in a state assembled to 11b, since it becomes a state where 11b can not move relatively, pressed (interference fit) may be a fit middle instead.
[0036]
　Next, a method for manufacturing the yoke cover 1.
　Method for manufacturing a yoke cover 1 (see FIGS. 1 to 3 of the present embodiment) performs punching press working, having a first punching step and second punching step.
　The first punching step is to plate, two electromagnetic yokes 11a, a first cylindrical surface 2a on one 11a being Meawasa of 11b, so as to form a plurality of first circumferential portion F1 Nisen section of the outer peripheral surface F to, those formed by press punching a first cylindrical surface 2a.
　The second punching step, the said relative plate material through the first punching step, two electromagnetic yokes 11a, a second cylindrical surface 2b of the other 11b are Meawasa of 11b, the first circumferential direction of the outer peripheral surface F so as to form a portion F1 as a plurality of second circumferential portion F2 Nisen cross section circumferentially displaced, that the second cylindrical surface 2b, is formed by punching press process of varying the first punching step and the punching direction it is.
[0037]
　Next, an example of a method of manufacturing the yoke cover 1 according to the embodiment of the present invention.
(First punching step)
　as shown in the illustration of FIG. 7 (a), performing a punching press working with respect to the plate material by the first punching die 8a is a hatched portion in FIG. (E.g., FIGS. 7 (a) punching the surface side from the back side).
　The first cutting die 8a, together has a recess forming the projecting portion 1a, has an arc portion R1 and the linear portion S1, S2, S3,.
　Thus, the plate, protrusions 1a, first cylindrical surface 2a is shear plane, punching sag 3a and broken surface 4a, and flat portions 5, 6 and 7 are formed (see FIGS. 1 to 3).
[0038]
(Second punching step)
　as shown in the illustration of FIG. 7 (b), performing a punching press working with respect to the plate member by the second punching die 8b is a hatched portion in FIG. (E.g., and FIG. 7 (b) punching from the surface side to the back side).
　Second cutting die 8b has a circular arc portion R2.
　Therefore, the plate member, a second cylindrical surface 2b, punching sag 3b and fracture surface 4b is formed a shear plane (see FIGS. 1 to 3).
　Further, since the same time punching the outer and inner diameter 1b of the yoke cover 1 by the second punching die 8b, it can be secured in the outer inner diameter accuracy (concentricity).
[0039]
　Next, a description will be given of another example of a method of manufacturing the yoke cover 1 according to the embodiment of the present invention.
(First punching step)
　as shown in the illustration of FIG. 8 (a), performing a punching press working with respect to the plate material by the first punching die 9a is a hatched portion in FIG. (For example shown in FIG. 8 (a) punching the surface side from the back side).
　The first punching die 9a has an arc portion R1 and the linear portion S1, S2,.
　Therefore, the plate member, the first cylindrical surface 2a, punching sag 3a and broken surface 4a, and flat portions 5 and 6 is formed is a shear plane (see FIGS. 1 to 3).
[0040]
(Second punching step)
　as shown in the illustration in FIG. 8 (b), performing a punching press working with respect to the plate member by the second punching die 9b is a hatched portion in FIG. (For example, and FIG. 8 (b) punching from the surface side to the back side).
　The second punching die 9b has an arc portion R2 and the linear portion S3,.
　Therefore, the plate member, a second cylindrical surface 2b, punching sag 3b and fracture surface 4b, and the plane portion 7 is formed a shear plane (see FIGS. 1 to 3).
　Further, since the same time punching the outer and inner diameter 1b of the yoke cover 1 by the second punching die 9b, it can be secured in the outer inner diameter accuracy (concentricity).
　In the step of FIG. 8 (a) and (b), since no punched outer peripheral portion of the projecting portion 1a, it requires additional engineering. The may be punched outer peripheral portion of the projecting portion 1a in the second punching step is a matter of course.
[0041]
　By performing the punching press working of the first punching step and second punching step as described above, it can be produced yoke cover 1.
　Incidentally, a shear plane in the first punching step to form a first cylindrical surface 2a, so to form a second cylindrical surface 2b is a shear plane in the second punching step, the center and the second cylinder of the first cylindrical surface 2a If the center of the surface 2b is shifted (if there is a misalignment) it is assumed.
　However, even in such a case, as shown in FIG. 2 (b), the first cylindrical surface 2a is located on one side in the axial direction than the axial center, the second cylindrical surface 2b axial center since it is located on the other side in the axial direction than not that the second cylindrical surface 2b is interference when Meawaseru on one of the electromagnetic yoke 11a of the first cylindrical surface 2a, while a second cylindrical surface 2b of nor first cylindrical surface 2a when Meawaseru the electromagnetic yoke 11b interfere.
[0042]
　According to the manufacturing method of the yoke cover 1 as described above, by punching press process comprising the first punching step and the second punching step changed the punching direction, a first cylindrical surface which Meawasa on one of the electromagnetic yoke 11a since the 2a and the other electromagnetic yoke 11b is formed as a second cylindrical surface 2b shear plane being Meawasa, there is no need for shaving the like after punching press process. In addition, slow productivity cycle time is not also performed special processing such as fine blanking to deteriorate.
　Further, by punching press work, one of the electromagnetic yoke 11a side portion than the first cylindrical surface 2a, and the other of the electromagnetic yoke 11b-side portion than the second cylindrical surface 2b, because the vent sagging is formed since the corner R portions for efficiently performed tasks fit is automatically formed by punching press working for forming the first cylindrical surface 2a and the second cylindrical surface 2b, additional machining to form the corner R portion is unnecessarily Become.
　Therefore, it is possible to reduce the manufacturing cost of the yoke cover 1.
[0043]
　Furthermore, a shear surface formed by changing the punching direction by punching press working of the first cylindrical surface 2a and axially from the center in the axial direction in a position closer toward the one electromagnetic yoke 11a from the center the other since it is separated a first cylindrical surface 2a and the second cylindrical surface 2b to form a planar portion 5 between the second cylindrical surface 2b at the position near the direction of the electromagnetic yoke 11b, a first cylindrical surface adjacent switching section 2a and the second cylindrical surface and 2b does not influence the work fit to the electromagnetic yoke 11a, 11b.
　Moreover, since no directivity in the axial direction, the direction at the time of working fit (Table, back) is not necessary to consider the.
　Thus, two electromagnetic yokes 11a which facing the yoke cover 1 manufactured by the manufacturing methods such as these, to 11b can improve the workability in Meawaseru.
[0044]
　In the above description, the case of manufacturing by press punching the yoke cover 1 in the shape of FIG. 1 and FIG. 2 (a), a yoke cover 1 in the shape of FIG. 1 and FIG. 2 (a), the machine machining, forging, or may be produced by such a casting.
　In the yoke cover 1 has a shape as shown in FIG. 1 and FIG. 2 (a), the electromagnetic yoke 11a, a cylindrical surface is Meawasa to 11b, the first cylindrical surface 2a and the other electromagnetic that on one of the electromagnetic yoke 11a is Meawasa with divided into a second cylindrical surface 2b of the yoke 11b are Meawasa are formed at positions where the first cylindrical surface 2a and the second cylindrical surface 2b is displaced in the circumferential direction.
　Further, the corner R portion 3a is formed in the axial portion of the one 11a side of the electromagnetic yoke than the first cylindrical surface 2a, the corner R in axial section of the other 11b side of the electromagnetic yoke than the second cylindrical surface 2b part 3b is formed.
　Therefore, the yoke cover 1 two electromagnetic yokes 11a, when Meawaseru to 11b, along with the required force from the shorter circumferential length of the portion to Awa fitting is reduced, which is formed at the corner portion of the portion for Awa fit electromagnetic yoke 11a along the corner R part, since it is possible to Awa wearing 11b, thereby improving the working efficiency.
　Moreover, as to form at a position shifted a first cylindrical surface 2a and the second cylindrical surface 2b in the circumferential direction, in the axial portion of the other 11b side of the electromagnetic yoke than the first cylindrical surface 2a, a first cylindrical surface 2a from an axial end edge of the tapered surface 4a of the outer diameter decreases gradually formed in accordance with axially spaced, on one axial portion of the 11a side of the electromagnetic yoke than the second cylindrical surface 2b of the second outer diameter as the distance from the axial edge of the cylindrical surface 2b in the axial direction forms a tapered surface 4b gradually decreases.
　Therefore, small area of ​​the cylindrical surface is necessary to improve the accuracy, since less accurate machining surface can reduce the manufacturing cost of the yoke cover 1.
DESCRIPTION OF SYMBOLS
[0045]
1 yoke cover 1a projections
1b inner peripheral portion
2a first cylindrical surface (shear plane by the first punching
step) 2b second cylindrical surface (shear plane in the second punching
step) 3a, 3b angle R unit (excl sagging) 4a, 4b tapered surface (fracture
surface) 5,6,7 flat portion 8a, 9a first cutting die
8b, 9b second punching die 11a, 11b electromagnetic yoke
11c recess 11d cylindrical portion
11e bottom 11f notch
13a, 13b detection coil 14 yoke cover
14a protruding portions 15a, 15b electromagnetic yoke
15c recess 15d cylindrical portion
15e bottom 18 coil bobbin
18a, 18b flange portion 18c groove
18d restricting portion 18e terminal mounting portions
18f terminal 18g guide portion
21 steering Eel 22 steering gear unit
23 the input shaft 24 tie rod
25,25a steering shaft 26,26a steering column
27 universal joint 28 the intermediate shaft
29 the universal joint 30 the electric motor
31 the inner column 32 outer column
33 lower shaft 34 upper shaft
35 housing 36 the output shaft
37, 38 ball bearing 39 the torsion bar
40 the cylindrical portion 41 circumferential groove
42 female stopper 43 male stopper portion
44 torque detecting concave and convex portion 45 torque detecting sleeve
46a, 46b windows 47 torque sensor
48 worm wheel 49 worm
50 worm reducer
A shear plane B vent sagging
C fracture surface c clearance
D die E1 lower end
E2 upper portion F outer peripheral surface
F1 first circumferential portion F2 second circumferential portions
G1, G2 engaging protrusion M punched
P punch R1, R2 arc portion
S1, S2, S3 straight portion T thickness

claims

Impedance changes according to torque generated in the rotary shaft, a detection coil in a pair to constitute a torque detecting device for detecting the torque based on the output voltage of the detection coil and facing each other in the axial direction 2 one of so as to be sandwiched between the electromagnetic yoke, wherein a single yoke cover the inner diameter of the cylindrical portion of the two electromagnetic yokes for holding the two electromagnetic yokes are Meawasa,
　Meawasa on one of the two electromagnetic yoke a first cylindrical surface and forming a plurality of first circumferential portion of the outer peripheral surface to said the other of the two electromagnetic yoke circumferentially of the second cylindrical surface from said first circumferential portion of the outer peripheral surface to be Meawasa forming a plurality of second circumferential portion which is offset,
　to form a corner R portion on one nearer axial portion of said first electromagnetic yoke than the cylindrical surface, prior to the second cylindrical surface Yoke cover, characterized in that by forming a corner R portion in axial section of the other side of the electromagnetic yoke.
[Requested item 2]
　Forming said the other closer axial portion of the electromagnetic yoke than the first cylindrical surface, tapered surface whose outer diameter decreases gradually as the distance from the axial edge of the first cylindrical surface in the axial direction to together, in one closer axial portion of said second cylindrical surface electromagnetic yoke than from said axial end edge of the second cylindrical surface as the distance in the axial direction the outer diameter decreases gradually tapered by forming a surface according to claim 1 yoke cover according.
[Requested item 3]
　Impedance changes according to torque generated in the rotary shaft, a detection coil in a pair to constitute a torque detecting device for detecting the torque based on the output voltage of the detection coil and facing each other in the axial direction 2 one of so as to be sandwiched between the electromagnetic yoke, wherein a single yoke cover the inner diameter of the cylindrical portion of the two electromagnetic yokes for holding the two electromagnetic yokes are Meawasa,
　Meawasa on one of the two electromagnetic yoke first cylindrical surface is formed in a plurality of first circumferential portion of the outer peripheral surface, the other of said two electromagnetic yokes second cylindrical surface offset from the first circumferential portion of the outer peripheral surface in the circumferential direction of Meawasa that was now formed into a plurality of second circumferential portion,
　said first cylindrical surface and said second cylindrical surface, a shear surface formed by changing the punching direction by punching pressing this Yoke cover characterized by.
[Requested item 4]
　Between the first cylindrical surface and said second cylindrical surface adjacent flat or curved surface portion located radially inward from the virtual cylindrical surface is formed including the first cylindrical surface and said second cylindrical surface yoke cover according to any one of claims 1-3.
[Requested item 5]
　Wherein the outer peripheral surface projecting portion projecting radially outward from the inner diameter of the electromagnetic yoke formed with a plurality of circumferentially first cylindrical surface and said second cylindrical surface between adjacent groups of the protrusion 1 One each with formed, between the first cylindrical surface and said second cylindrical surface adjacent, plane located radially inward from the virtual cylindrical surface including the first cylindrical surface and said second cylindrical surface or any yoke cover according to one of claims 1 to 3, the curved portion is formed.
[Requested item 6]
　Impedance changes according to torque generated in the rotary shaft, a detection coil in a pair, a torque detector for detecting the torque based on the output voltage of the detection coil,
　any one of claims 1 to 5 torque detecting apparatus provided with a yoke cover according to (1).
[Requested item 7]
　The electric power steering apparatus for applying a steering assist force to a steering system of a vehicle,
　and a torque detecting apparatus according to claim 6, wherein for detecting the steering torque inputted to the steering mechanism, the steering torque detected by the torque detecting device based on the electric power steering apparatus that includes a motor control unit for driving and controlling the electric motor to impart the steering assist force.
[Requested item 8]
　Impedance changes according to torque generated in the rotary shaft, a detection coil in a pair to constitute a torque detecting device for detecting the torque based on the output voltage of the detection coil and facing each other in the axial direction 2 one of so as to be sandwiched between the electromagnetic yoke, wherein a one manufacturing process of the yoke cover the inner diameter of the cylindrical portion of the two electromagnetic yokes for holding the two electromagnetic yokes are Meawasa,
　to plate, the two a first cylindrical surface which Meawasa to one electromagnetic yoke, a first punching step of forming to form a shear plane to a plurality of first circumferential portion of the outer peripheral surface, by press punching the first cylindrical surface ,
　to the plate which has undergone the first punching step, a second cylindrical surface that is press-fitted Awa fit to the other of the two electromagnetic yokes, or the first circumferential portion of the outer peripheral surface So as to form a shear plane to a plurality of second circumferential portion which is offset in the circumferential direction to form a press-punching the second cylindrical surface, and a second punching step of varying the first punching step and the punching direction ,
the production method of the yoke cover and having a.
[Requested item 9]
　Between the first cylindrical surface and said second cylindrical surface adjacent by forming a flat or curved surface portion located radially inward from the virtual cylindrical surface including the first cylindrical surface and said second cylindrical surface method for producing a yoke cover according to claim 8.
[Requested item 10]
　Said yoke cover, which projections projecting radially outward from the inner diameter of the electromagnetic yoke on the outer peripheral surface is formed with a plurality of circumferentially first cylinder between adjacent groups of said protrusion to form a surface and the second cylindrical surface one by one, between the first cylindrical surface and said second cylindrical surface adjacent the imaginary cylindrical surface including the first cylindrical surface and said second cylindrical surface the method according yoke cover to claim 8, wherein by forming a flat or curved surface portion located radially inwardly.
[Requested item 11]
　A manufacturing method of an electric power steering apparatus for applying a steering assist force to a steering system of the vehicle,
　constituting a torque detecting apparatus for an electric power steering system, the inner diameter of the cylindrical portion of the two electromagnetic yoke facing each other in the axial direction the method of manufacturing the electric power steering device including a step of Awa fit the yoke cover manufactured by the manufacturing method according to any one of claims 8-10.