JP4716079B2 - Rotation amount detection device - Google Patents

Description

  The present invention relates to a rotation amount detection device that detects a rotation amount of a rotation shaft.

There is a rotation angle detection device that detects the rotation angle of a rotating shaft by detecting the amount of rotation of a rotating body such as a gear that rotates in conjunction with the rotating shaft (see, for example, Patent Documents 1 and 2). The gear of the rotation angle detection device of Patent Document 2 is directly supported by a housing that houses a rotation angle sensor and the like. Specifically, the support shaft of the gear is rotatably supported by a support hole formed in the housing, and the support shaft slides with respect to the support hole.
JP-T-2001-505667. Japanese Patent Application No. 2002-223441.

  Usually, the gear and the housing are formed of a resin material. However, since the optimal material for the gear is different from the optimal material for the housing, the gear and the housing are formed of different materials among the resin materials. That is, the gear and the housing have different linear expansion coefficients, and a difference occurs in the amount of thermal expansion between the gear and the housing due to a temperature change. For this reason, in the structure of patent document 2, the spindle of a gear will be fastened by the support hole of a housing, and there exists a possibility that the torque cross of a gear may increase.

  The present invention has been made under such a background, and an object of the present invention is to provide a rotation amount detection device capable of suppressing an increase in torque loss of a rotating body accompanying a temperature change.

To achieve the above object, the present invention provides a rotating body row including a plurality of rotating bodies that rotate in conjunction with a rotatable shaft to be measured, a rotation amount sensor that detects a rotation amount of at least one rotating body, A housing for housing the row of rotating bodies and a rotation amount sensor; and a support hole provided in the housing for rotatably supporting a support shaft of at least one rotating body, wherein the support shaft is elastic in a radial direction. An elastic support portion that can be supported is provided , and the elastic support portion can be elastically expanded and contracted in the radial direction of the support hole by connecting the receiving portion with an arc-shaped receiving portion that receives the circumferential surface of the support shaft. and a stretchable portion, the receiving portion and the elastic portion provides a rotation amount detection apparatus according to claim Rukoto formed integrally with the housing by resin molding.

According to the present invention, even if there is a difference in the amount of thermal expansion between the rotating body and the housing due to the temperature change, this difference can be absorbed by the elastic deformation of the elastic support portion, so that the support shaft is tightened excessively by the support hole. Can be prevented. As a result, an increase in the torque cross of the rotating body can be reliably suppressed.
Further, the elastic supporting portion includes a circular-arc cross section receiving portion for receiving the peripheral surface of the spindle, and a resiliently stretchable elastic portion in a radial direction of the support hole and connecting the receiving portion. Thereby , a support shaft can be smoothly rotated by a receiving part, and it can prevent reliably that a support shaft is tightened too strongly by a support hole because an expansion-contraction part expands and contracts.

Moreover , the said receiving part and the expansion-contraction part are integrally formed in the said housing by resin molding . Thereby , the manufacturing cost can be significantly reduced through the reduction of the number of parts.
In the present invention, a rotating body row including a plurality of rotating bodies that rotate in conjunction with a rotatable shaft to be measured, a rotation amount sensor that detects a rotation amount of at least one rotating body, the rotating body row, A housing for accommodating a rotation amount sensor; a support hole provided in the housing for rotatably supporting a support shaft of at least one rotating body; and an annular spacer interposed between the support hole and the support shaft. The linear expansion coefficient of the annular spacer may be in the range of 80% to 120% of the linear expansion coefficient of the corresponding support shaft.

In this case, the amount of thermal expansion of the support shaft and the annular spacer accompanying the temperature change can be made substantially equal, so that the support shaft can be prevented from being tightened excessively by the annular spacer due to the difference in the amount of thermal expansion. As a result, an increase in the torque cross of the rotating body can be reliably suppressed.
In the present invention, the annular spacer may be supported in the support hole in a non-rotatable manner. In this case, the support shaft can be rotated with respect to the annular spacer having substantially the same linear expansion coefficient. Thereby, it is possible to prevent the fitting gap from being clogged due to a temperature change at the portion where the support shaft slides relatively during rotation. As a result, the torcross of the rotating body can be more reliably suppressed.
In the present invention, a rotating body row including a plurality of rotating bodies that rotate in conjunction with a rotatable shaft to be measured, a rotation amount sensor that detects a rotation amount of at least one rotating body, the rotating body row, A housing that accommodates a rotation amount sensor and a support hole that is provided in the housing and rotatably supports a support shaft of at least one rotating body, and the support shaft can be elastically supported in the radial direction in the support hole. An elastic support portion is provided, and the elastic support portion includes an escape hole that is disposed in a radially outward portion of the support hole of the housing and penetrates the housing, and the escape hole has a thickness at an edge of the support hole. This meat may escape when thermally expanded.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic plan view of a rotation amount detection device 100 according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the rotation amount detection device 100. Referring to FIGS. 1 and 2, rotation amount detection device 100 includes first to fourth gears 1, 2, 3, 4 as a plurality of rotating bodies that rotate in conjunction with rotatable measurement shaft 200. A gear train 5 as a rotating body row including the first rotation amount sensor 6 that detects the rotation amount (rotation angle) of the second gear 2, and a second that detects the rotation amount (rotation angle) of the fourth gear 4. Rotation angle sensor 7 and an absolute angle calculation unit as calculation means for calculating the absolute rotation angle of the shaft 200 to be measured based on the rotation amounts detected by the first and second rotation amount sensors 6 and 7. 8 (see FIG. 3 which is a block diagram showing an electrical configuration).

  In the present embodiment, description will be given in the case where the rotation amount detection device 100 is applied to an electric power steering device to detect the rotation angle of a steering member (not shown) such as a steering wheel. In this case, the shaft 200 to be measured is constituted by a shaft such as a steering shaft connected to the steering member so as to be able to rotate together. However, the present invention can be applied to general absolute angle detection of a multi-rotation axis.

  The first to fourth gears 1, 2, 3, and 4 are spur gears made of synthetic resin such as POM (Poly Oxy Methylene). The first gear 1 is coaxially disposed around the shaft to be measured 200 and can rotate integrally with the shaft to be measured 200. The second gear 2 is formed on the rotation axis 10 of the first support shaft 9 with the same diameter as the first gear 1 and meshes with the first gear 1, and the second gear 2 has a smaller diameter than the second gear 2. The third gear 3 that rotates integrally is provided. That is, the rotation axis 10 is also the rotation axis of the second gear 2. The first support shaft 9, the second gear 2, and the third gear 3 are integrally formed.

  The third gear 3 is formed so as to protrude from one side surface 2 a of the second gear 2. The first support shaft 9 protrudes from one side surface 3 a of the third gear 3. The fourth gear 4 has a larger diameter than the third gear 3 and meshes with the third gear 3. The fourth gear 4 has one side surface 4a opposite to the one side surface 2a of the second gear 2 and another side surface 4b. The second support shaft 12 protrudes from the other side surface 4b, and the third support shaft 11 protrudes from the one side surface 4a.

With the above configuration, the rotation of the shaft 200 to be measured is decelerated by the third and fourth gears 3 and 4, and the rotation amount detected by the second rotation amount sensor 7 is detected by the first rotation amount sensor 6. The rotation amount is smaller than the rotation amount.
The first rotation amount sensor 6 has a movable portion 6a and a fixed portion 6b that face each other. The movable portion 6 a is fixed to the concave portion 13 of the other side surface 2 b of the second gear 2 on the rotation axis 10, and rotates integrally with the second gear 2. The fixing part 6b is fixed to a substrate 14 as a fixing member.

  Similarly, the second rotation amount sensor 7 has a movable portion 7a and a fixed portion 7b that face each other. The movable portion 7 a is fixed to the concave portion 15 of the end surface 11 a of the third support shaft 11 of the fourth gear 4 on the rotation axis 14 of the second support shaft 12, and rotates integrally with the fourth gear 4. The rotation axis 14 is also the rotation axis of the fourth gear 4. The fixing part 7 b is fixed to the substrate 14. The absolute angle calculation unit 8 is mounted on the substrate 14.

The detection signals from the first and second rotation amount sensors 6 and 7 are input to the absolute angle calculation unit 8, and are detected by the first and second rotation amount sensors 6 and 7 in the absolute angle calculation unit 8. Based on the rotation amounts of the second and fourth gears 2 and 4, the absolute rotation angle of the shaft 200 to be measured is calculated.
4 shows an example of the actual packaging of the rotation amount detection device 100 shown schematically in FIGS. 1 and 2, and FIG. 5 is a cross-sectional plan view taken along the line II-II in FIG. . Referring to FIGS. 4 and 5, rotation amount detection device 100 houses first and second rotation amount sensors 6 and 7 (only the first rotation amount sensor 6 side is shown in FIG. 4). 16 is provided. The housing 16 is made of a synthetic resin such as PBT (Poly Buthylene Terephthalate), and includes first and second divided housings 17 and 18 that are combined with each other.

  The first and second divided housings 17 and 18 accommodate the first to fourth gears 1, 2, 3, and 4 of the gear train 5. The first divided housing 17 includes a support hole 19 that rotatably supports the first support shaft 9 that is a support shaft common to the second and third gears 2 and 3, and a support shaft of the fourth gear 4. Support holes 19 for rotatably supporting the second support shaft 12 are formed.

The feature of the present embodiment is that these support holes 19 are provided with elastic support portions 20 capable of elastically supporting the corresponding first and second support shafts 9 and 12 in the radial direction R of the support holes 19. It is in the point which has each provided. Since each elastic support part 20 has the same structure, it demonstrates along with the elastic support part 20 which supports the 1st spindle 9 below.
The support hole 19 concentrically surrounds the peripheral surface 9 a of the first support shaft 9, and an elastic support portion 20 is integrally formed on the peripheral surface of the support hole 19.

The elastic support portion 20 receives a peripheral surface 9 a of the first support shaft 9 and rotatably supports the first support shaft 9. The elastic support portion 20 includes a receiving portion 21 having an arcuate cross section, and the receiving portion 21 and the support hole 19. An expansion / contraction part 22 connected to the peripheral surface and elastically expandable / contractible in the radial direction of the support hole 19 is included.
A plurality of (for example, four) receiving portions 21 are provided on the circumference of the support hole 19 so as to surround the circumferential surface 9 a of the first support shaft 9. The shape of one side surface 21a of each receiving portion 21 is formed in a shape corresponding to the shape of the peripheral surface 9a of the first support shaft 9 (a cross-sectional arc shape with the same curvature), and the peripheral surface 9a of the first support shaft 9 Can slide smoothly with respect to the one side surface 21a of the receiving portion 21.

  For example, one expansion / contraction part 22 is provided in each receiving part 21, and is arranged on the circumference of the support hole 19. Each stretchable part 22 is formed in a shape in which a pair of bent pieces having a V-shaped cross section facing each other in a direction intersecting the radial direction of the support hole 19 (for example, the circumferential direction) are integrally combined. Each expansion / contraction part 22 includes one end 60 fixed to the other side surface 21 b of the corresponding receiving part 21, the other end 61 fixed to the peripheral surface of the support hole 19, and the one end 60 and the other end 61. And a bent portion 62 that is bent in a direction intersecting the radial direction of the support hole 19.

The receiving portion 21 and the stretchable portion 22 are integrally formed with the first divided housing 17 of the housing 16 by resin molding. That is, the 1st division | segmentation housing 17, the receiving part 21, and the expansion-contraction part 22 are formed with a single member.
With the above configuration, when there is a difference in the amount of thermal expansion between the first support shaft 9 and the first divided housing 17 due to the temperature change, this difference is caused by the expansion / contraction part 22 of the elastic support part 20 expanding and contracting in the radial direction R. To be absorbed.

  The housing 16 is fixed to the mounting object 25 by a metal screw 24. Specifically, the shaft portion 26 of the screw 24 is provided with a columnar guide portion 27 and a screw portion 28 that is formed on the tip side of the guide portion 27 and has a smaller diameter than the guide portion 27. Opposing bosses 29 and 30 are formed in the first and second divided housings 17 and 18, and the substrate 14 and the positioning member 31 are sandwiched between the end surfaces 29 a and 30 a of the bosses 29 and 30. The guide portion 27 of the screw 24 is inserted into the insertion holes 32 and 33 of the bosses 29 and 30, the insertion hole 34 of the substrate 14, and the insertion hole 35 of the positioning member 31 by so-called narrow clearance insertion. The insertion holes 32 to 35 are aligned with each other by the guide portion 27. The screw portion 28 of the screw 24 is screwed into the screw hole 36 of the attachment target 25.

With the above configuration, the first divided housing 17, the positioning member 31, the substrate 14, and the second divided housing 18 are integrally sandwiched between the receiving surface 38 of the attachment target 25 and the head 39 of the screw 24. The The length of the guide portion 27 is made shorter by a predetermined amount L (for example, 0.5 mm) than the cumulative length of the members 17, 31, 14, 18 that are sandwiched integrally.
Thereby, when the screw 24 is tightened, the annular step portion 37 formed at one end portion of the guide portion 27 comes into contact with the receiving surface 38 of the attachment object 25, and the head portion 39 is connected to the members 17, 31, 14 and 18 can be reliably pressed and attached without play, and the positioning accuracy between the members 17, 31, 14, and 18 in the axial direction of the screw 24 can be further increased. In addition, since the guide portion 27 is inserted into the insertion holes 32, 35, 34, 33 of the members 17, 31, 14, 18 with a narrow clearance, the members 17, 31, 14, The positioning accuracy of 18 can be further increased.

  Further, the positioning member 31 whose positioning accuracy is increased in this way has an annular positioning projection 40. The other side surface 2b of the second gear 2 is received by the receiving surface 41 that is an end surface of the positioning protrusion 40, and the second gear 2 is positioned in the axial direction. The positioning protrusion 40 also functions as a thrust bearing for the second and third gears 2 and 3.

  In addition, an annular protrusion 42 centered on the rotation axis 10 is formed on the other side surface 2 b of the second gear 2. The annular protrusion 42 is rotatably fitted in the annular positioning protrusion 40, whereby the second gear 2 is positioned in the radial direction. In this way, the positioning accuracy of the second and third gears 2 and 3 can be increased via the positioning member 31. Although not shown, the fourth gear 4 is similarly positioned in the axial direction and the radial direction by the positioning member 31.

The fastening structure using the screw 24 is provided at a plurality of places, for example, four places. Since the housing 16 can be directly fixed to the mating housing or the mating bracket as the mounting object 25 using the screw 24, the assembling property can be improved and the assembling cost can be reduced.
Further, since the guide portion 27 is formed integrally with the screw 24, the first and second divided housings 17, 18, the substrate 14, and the positioning member 31 are positioned with respect to the axial direction and the radial direction of the screw 24. There is no need to provide a separate dedicated part, and the number of parts can be reduced to further reduce the part cost.

  As described above, according to the present embodiment, even if there is a difference in thermal expansion between the second to third gears 2, 3, 4 and the first divided housing 17 of the housing 16 due to temperature change, Since the difference can be absorbed by expansion / contraction (elastic deformation) of the expansion / contraction part 22 of the elastic support part 20, it is ensured that the first support shaft 9 and the second support shaft 12 are tightened excessively by the corresponding support hole 19. Can be prevented. As a result, an increase in the torque cross of the second to fourth gears 2, 3 and 4 can be reliably suppressed.

  Further, the receiving portion 21 having an arcuate cross section of the elastic support portion 20 receives the peripheral surfaces 9a and 12a of the corresponding first and second support shafts 9 and 12, so that the first and second support shafts 9 and 12 can be rotated smoothly. Furthermore, by forming the receiving portion 21 and the expansion / contraction portion 22 of the elastic support portion 20 integrally with the first divided housing 17 of the housing 16, the manufacturing cost can be significantly reduced through the reduction of the number of parts.

As shown in FIG. 6, the support shaft 43 protruding from the one side surface 1 a of the first gear 1 can be freely rotated into the support hole 19 of the first divided housing 17 of the housing 16 via the elastic support portion 20. You may support.
FIG. 7 is a partial cross-sectional side view of a rotation amount detection device according to another embodiment of the present invention, and FIG. 8 is a cross-sectional plan view taken along line III-III in FIG. Below, a different point from embodiment shown in FIGS. 1-6 is demonstrated, the same code | symbol is attached | subjected to a structure and the description is abbreviate | omitted. With reference to FIGS. 7 and 8, the present embodiment is characterized in that an annular spacer 45 is provided in place of the elastic support portion 20 described above. Since the annular spacer 45 that supports the first support shaft 9 and the annular spacer 45 that supports the second support shaft 12 have the same configuration, hereinafter, the annular spacer 45 that supports the first support shaft 9 will be referred to as “annular spacer 45”. I will explain it as a rule.

  The annular spacer 45 is interposed between the support hole 19 of the first divided housing 17 of the housing 16 and the first support shaft 9, and rotatably supports the first support shaft 9. 19 is supported so as not to rotate. The linear expansion coefficient of the material of the annular spacer 45 is set in the range of 80% to 120% of the linear expansion coefficient of the material of the first support shaft 9. In the present embodiment, the annular spacer 45 is formed of a synthetic resin, but may be formed of a metal material that does not affect the magnetic field.

  The annular spacer 45 includes an annular main body 46 and a convex portion 47 protruding from the outer peripheral surface 46 a of the annular main body 46. The first support shaft 9 is fitted on the inner peripheral surface 46b of the main body 46 so as to be slidable in the circumferential direction. The outer peripheral surface 46 a of the main body 46 is fitted into the support hole 19 of the first divided housing 17 of the housing 16. For example, two convex portions 47 are provided on the outer peripheral surface 46 a of the main body portion 46 at equal circumferential intervals. On the peripheral surface of the support hole 19, concave portions 48 are formed at positions corresponding to the respective convex portions 47, and the convex portions 47 corresponding to the concave portions 48 are respectively fitted.

  Thus, according to the present embodiment, the linear expansion coefficient of the annular spacer 45 is made approximately equal to the linear expansion coefficient of the first and second support shafts 9 and 12, so that the first and The amount of thermal expansion of the second support shafts 9 and 12 and the corresponding annular spacer 45 can be made substantially equal. Accordingly, it is possible to prevent the first and second support shafts 9 and 12 from being excessively tightened by the corresponding annular spacer 45 due to the difference in the amount of thermal expansion. As a result, an increase in the torque cross of the second to fourth gears 2, 3 and 4 can be reliably suppressed.

  Further, by supporting the annular spacer 45 in the support hole 19 in a non-rotatable manner, the first and second support shafts 9 and 12 can be rotated with respect to the annular spacer 45 having substantially the same linear expansion coefficient. Thereby, it is possible to prevent the fitting gap from being clogged due to a temperature change at a portion where the first and second support shafts 9 and 12 slide relative to each other during rotation. As a result, the torcross of the second to fourth gears 2, 3 and 4 can be more reliably suppressed.

As shown in FIG. 9, the support shaft 43 of the first gear 1 may be rotatably supported in the support hole 19 of the first housing 17 via an annular spacer 45.
FIG. 10 is a partial cross-sectional plan view of a rotation amount detection device according to still another embodiment of the present invention. Referring to FIG. 10, a feature of the present embodiment is that a relief hole 50 for letting out the meat of the edge portion 49 of the support hole 19 is formed in the radially outward portion of the support hole 19. The elastic support portion 51 is provided. Since the configuration for supporting the first support shaft 9 and the configuration for supporting the second support shaft 12 are the same, the following description will be made in accordance with the configuration for supporting the first support shaft 9.

The first support shaft 9 is directly fitted into the support hole 19 of the first divided housing 17 of the housing 16 and is supported by the support hole 19 so as to be slidable (rotatable). A plurality of, for example, four relief holes 50 are formed on the circumference of the support hole 19 so as to surround the support hole 19 so as to surround the support hole 19.
According to the present embodiment, even if there is a difference in the amount of thermal expansion between the second to fourth gears 2, 3, 4 and the first divided housing 17 of the housing 16 due to temperature changes, the edge of the support hole 19 This difference can be absorbed by letting 49 meat escape to the hole 50, so that the first and second support shafts 9 and 12 can be prevented from being excessively tightened by the corresponding support holes 19. As a result, an increase in the torque cross of the second to fourth gears 2, 3 and 4 can be reliably suppressed.

As shown in FIG. 11, the support shaft 43 of the first gear 1 is directly fitted into the support hole 19 of the first housing 17 of the housing 16, and the relief hole is formed in the radially outer portion of the support hole 19. 50 may be provided.
The present invention is not limited to the contents of the above-described embodiment, and various modifications can be made within the scope of the claims. For example, only one of the first and second support shafts 9 and 12 may be provided with the corresponding elastic support portion 20, the annular spacer 45, and the elastic support portion 51. Moreover, the structure which detects the rotation amount of the to-be-measured shaft 200 only with one rotation amount sensor may be sufficient. Further, the receiving portion 21 and the stretchable portion 22 of the elastic support portion 20 may be formed separately from the housing 16.

1 is a schematic plan view of a rotation amount detection device according to an embodiment of the present invention. It is typical sectional drawing of a rotation amount detection apparatus. It is a block diagram which shows the principal part of the electrical structure of a rotation amount detection apparatus. An example in the case of actually packaging the rotation amount detection device shown schematically in FIGS. 1 and 2 is shown. It is a cross-sectional top view which follows the II-II line | wire of FIG. An example of actually packaging the first gear is shown. It is a partial cross section side view of the rotation amount detection apparatus of other embodiment of this invention. It is a cross-sectional top view which follows the III-III line of FIG. An example of actually packaging the first gear is shown. It is a partial cross section top view of the rotation amount detection apparatus of further another embodiment of this invention. An example of actually packaging the first gear is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Rotation amount detection apparatus 200 Measuring shaft 1 1st gear (rotating body)
2 Second gear (rotating body)
3 Third gear (rotating body)
4 Fourth gear (rotating body)
5 Gear train (rotating body row)
6 first rotation amount sensor 7 second rotation amount sensor 9 first support shaft 9a peripheral surface 12 second support shaft 12a peripheral surface 16 housing 19 support hole 20 elastic support portion 21 receiving portion 22 telescopic portion 45 annular spacer 43 Support shaft 51 Elastic support R Radial direction

Claims (4)

A rotating body row including a plurality of rotating bodies that rotate in conjunction with a rotatable shaft to be measured;
A rotation amount sensor for detecting a rotation amount of at least one rotating body;
A housing for housing the row of rotating bodies and the rotation amount sensor;
A support hole provided in the housing and rotatably supporting a support shaft of at least one rotating body;
An elastic support portion capable of elastically supporting the support shaft in the radial direction is provided in the support hole ,
The elastic support part includes an arcuate cross-section receiving part that receives the peripheral surface of the support shaft, and an extendable part that connects the receiving part and can elastically expand and contract in the radial direction of the support hole,
The receiving unit and the expansion unit, the rotation amount detecting apparatus according to claim Rukoto formed integrally with the housing by resin molding. A rotating body row including a plurality of rotating bodies that rotate in conjunction with a rotatable shaft to be measured;
A rotation amount sensor for detecting a rotation amount of at least one rotating body;
A housing for housing the row of rotating bodies and the rotation amount sensor;
A support hole provided in the housing and rotatably supporting a support shaft of at least one rotating body;
An annular spacer interposed between the support hole and the corresponding support shaft,
The rotation amount detecting device according to claim 1, wherein a linear expansion coefficient of the annular spacer is in a range of 80% to 120% of a linear expansion coefficient of a corresponding support shaft. 3. The rotation amount detection device according to claim 2, wherein the annular spacer is non-rotatably supported by the support hole.   A rotating body row including a plurality of rotating bodies that rotate in conjunction with a rotatable shaft to be measured;
  A rotation amount sensor for detecting a rotation amount of at least one rotating body;
  A housing for housing the row of rotating bodies and the rotation amount sensor;
  A support hole provided in the housing and rotatably supporting a support shaft of at least one rotating body;
  An elastic support portion capable of elastically supporting the support shaft in the radial direction is provided in the support hole,
  The elastic support portion includes an escape hole that is disposed in a radially outward portion of the support hole of the housing and penetrates the housing.
  The rotation amount detecting device according to claim 1, wherein the escape hole releases the meat when the meat at the edge of the support hole is thermally expanded.

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