JP2012122982A - Rotation angle detecting device and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle detecting device capable of reducing backlash of a gear and preventing the lowering of a detection accuracy of the rotation angle, and to provide an electric power steering device.SOLUTION: One end of a spring 12, as energizing means, is elastically brought into contact with a case 9 to energize the case 9 in the direction of a sensor housing 10. By the energizing force of the spring 12 via the case 9, a first detection gear 3 and a second detection gear 4 mounted on the case 9 are pressed in the direction of the main gear 2. The sensor housing 10 on which the case 9 is mounted is provided with a presser plate 13 projecting in such a form as sandwiching the spring 12, and the other end of the spring 12 is elastically brought into contact with the presser plate 13 to be held by the presser plate 13. Both ends of the spring 12 are held by spot-faced holes 14 and 15 provided in the case 9 and the presser plate 13 and held to stabilize the energizing force of the spring 12.

Description

  The present invention relates to a rotation angle detection device and an electric power steering device.

  For example, a rotation angle detection device used for a steering wheel of an automobile includes a main gear engaged with a steering shaft and a detection gear mounted on a case of a detection device meshing with the main gear. When the steering wheel is steered, the main gear rotates, and the detection gear rotates in conjunction with this. Therefore, a magnetic angle sensor mounted on the detection gear and facing the magnet that rotates in conjunction with the detection gear is fixed to the case. The direction of the magnetic field is detected and the rotation angle of the steering wheel is detected. Here, the center positions of the magnet and the magnetic angle sensor are arranged to be the same.

  However, in the conventional rotation angle detection device, the backlash is caused by variations in the distance between the main gear and the detection gear caused by temperature changes, the assembly error between the main gear and the detection gear, or the backlash when the main gear and the shaft are attached. Will occur. If the steering of the right and left turns is repeated, when the steering direction is reversed, the position is temporarily maintained by backlash, and then the movement is started in the opposite direction, so that the rotation angle detection error (so-called hysteresis error) increases. In some cases, the angular accuracy deteriorated. An example of a rotation angle detection device that reduces the backlash of the gear and that can detect the rotation angle with high accuracy and no error is disclosed in Patent Document 1, for example.

JP 2007-192609 A

  In the rotation angle detection device described in Patent Document 1, since the detection gear is pressed and moved in the main gear direction by the spring, backlash between the main gear and the detection gear is reduced, but the magnetic angle sensor is fixed to the case. For this reason, the center position of the magnetic angle sensor and the magnet attached to the detection gear are shifted, and a rotation angle detection error occurs.

  For this reason, it is an object to obtain a rotation angle detection device that suppresses the increase in backlash between the main gear and the detection gear, does not shift the center positions of the magnet and the magnetic angle sensor, and does not reduce the rotation angle detection accuracy. ing.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a rotation angle detection device and an electric power steering device that can reduce gear backlash and do not reduce the detection accuracy of the rotation angle. There is.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes a main gear that rotates in conjunction with a rotating body, a detection gear that rotates in conjunction with the main gear, and a detected member provided in the detection gear. A detection means for detecting rotation of the detection gear; a case for rotatably supporting the detection gear; a case for arranging the detection means; a sensor housing for inserting the rotary body and for attaching the case. The case is attached to the sensor housing so as to be movable relative to the sensor housing in a state in which the main gear and the detection gear can be interlocked, and provided with a biasing means for biasing the case toward the main gear. This is the summary.

  According to the above configuration, the backlash between the main gear and the detection gear can be suppressed by urging the case supporting the detection gear and the detection unit in the main gear direction, and the shift of the center position between the detection unit and the detected member is eliminated. be able to. Thereby, it is possible to obtain a rotation angle detection device that can detect a rotation angle with high accuracy and no detection error.

  The gist of the invention described in claim 2 is that the urging means is provided between the sensor housing and the case.

  According to the above configuration, the urging force of the urging means can be kept constant by providing the urging means between the sensor housing and the case.

The gist of the invention described in claim 3 is that the electric power steering device includes the rotation angle detection device according to claim 1 or 2.
According to the rotation angle detection device of the first or second aspect, since the detection rotation angle is highly accurate, the electric power steering device can be improved in the steering feeling of the vehicle.

  It is possible to provide a rotation angle detection device and an electric power steering device that can reduce backlash of the gear and that does not reduce the detection accuracy of the rotation angle.

The top view of the rotation angle detection apparatus which concerns on embodiment of this invention. AA sectional drawing of FIG. (a) The figure explaining schematic structure of the rotation angle detection apparatus which concerns on this Embodiment, (b) BB sectional drawing of Fig.3 (a).

Embodiments of the present invention will be specifically described below with reference to the drawings.
1 is a plan view of a rotation angle detection device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view seen from the direction of arrow A in FIG. 1, and FIGS. 3 (a) and 3 (b) are schematic views. It is a figure explaining a structure.

  FIG. 3A is a plan view showing a schematic configuration of the rotation angle detection device. The main gear 2 is a rotating body made of an insulating resin having a spur gear formed on the outer periphery, and is engaged with a shaft 11 inserted through the central portion. To do. There are detection bodies for the first detection gear 3 and the second detection gear 4 that detect the rotation angle of the shaft 11.

  The first detection gear 3 is a first detection member made of an insulating resin that is rotatably supported by an insulating resin case 9. The spur gear on the outer periphery meshes with the spur gear of the main gear 2, and this In the center of the first detection gear 3, a magnet 5 (detected member) is mounted by insert molding or the like.

  Further, the second detection gear 4 is a second detection body made of an insulating resin rotatably supported by the case 9, and a spur gear having a different number of teeth from the spur gear of the first detection gear 3 is provided on the outer periphery. The spur gear of the second detection gear 4 is engaged with the spur gear of the first detection gear 3, and a magnet 6 is attached to the center of the second detection gear 4.

  A circuit board (not shown) arranged substantially in parallel above the first detection gear 3 and the second detection gear 4 has a Hall IC (on the surface facing the magnet 5 of the first detection gear 3). A magnetic angle sensor 7 (detection means) such as a magnetic field detection element (see FIG. 3B) is provided on the surface of the second detection gear 4 facing the magnet 6 (not shown). 3 (b) is mounted.

  The magnet 5 and the magnetic angle sensor 7 facing the magnet 5 and the magnet 6 and the magnetic angle sensor 8 facing the magnet 5 formed in this way are the first detection gear 3 and the first detection gear 3 on which the magnets 5 and 6 are mounted. The second detection gear 4 and the circuit board on which the magnetic angle sensors 7 and 8 are mounted are disposed in the case 9.

  Further, the case 9 is attached in contact with the sensor housing 10 made of an aluminum die-cast material. The shaft 11 is inserted into the sensor housing 10 and is rotatably mounted.

  In the above configuration, when the steering wheel (not shown) is steered, the main gear 2 rotates in conjunction with the rotation of the shaft 11, and the spur gear of the first detection gear 3 meshes with the spur gear on the outer periphery of the main gear 2. Further, the spur gear of the second detection gear 4 meshes with the spur gear of the first detection gear 3 and rotates in conjunction therewith.

  The magnets 5 and 6 mounted in the center of the first detection gear 3 and the second detection gear 4 also rotate, and the magnetic angle sensors 7 and 8 detect changes in the magnetic field direction of the magnets 5 and 6, respectively. Then, a PWM signal or the like is output as a detection signal to an external control means (not shown) formed by an electronic component such as a microcomputer, and converted into a rotation angle signal of the main gear 2.

  At this time, since the first detection gear 3 and the second detection gear 4 have different number of teeth of the spur gear and have different rotation speeds, each detection signal from the first and second detection means is a period. And detection signals with different phases.

  Next, in this embodiment, as shown in FIGS. 1 and 2, the spring 12 is a spring made of steel or copper alloy as an urging means, and one end thereof is elastically contacted with the case 9 in a slightly pressed state, Case 9 is urged in the direction of sensor housing 10. The first detection gear 3 and the second detection gear 4 attached to the case 9 are pressed toward the main gear 2 by the biasing force of the spring 12 via the case 9. At this time, the protrusion provided on the case 9 engages with the mounting hole of the sensor housing 10, thereby suppressing the case 9 from moving up and down and left and right with respect to the rotation axis of the shaft 11.

  The sensor housing 10 to which the case 9 is attached is provided with a pressing plate 13 made of resin or metal that protrudes with the spring 12 interposed therebetween. The other end of the spring 12 is elastically contacted with the pressing plate 13, and the spring 12. Hold. Both ends of the spring 12 are held by counterbore holes 14 and 15 provided in the case 9 and the holding plate 13, and the urging force of the spring 12 is held at a constant force, so that the rotation angle detection device 1 is configured. ing.

  As described above, in the present embodiment, the biasing means for pressing the case 9 against the sensor housing 10 is provided, and the stopper means for holding the biasing means is formed on the sensor housing 10. That is, the first detection gear 3 and the second detection gear 4 are pressed and urged against the main gear 2 by the urging force of the spring 12, and the urging force of the spring 12 can be kept constant by the pressing plate 13.

  Further, since the magnetic angle sensors 7 and 8 move in the direction of the main gear 2 together with the opposing magnets 5 and 6 mounted on the case 9, the magnet 5 and the magnetic angle sensor 7, and the magnet 6 and the magnetic angle sensor 8 are used. The center position of each can be prevented from shifting. As a result, backlash between the main gear 2 and the first detection gear 3 can be suppressed, and a highly accurate rotation angle can be detected without error.

In addition, you may change the said embodiment as follows.
In the above embodiment, the configuration in which the case is pressed in the main gear direction by the pressing spring provided between the pressing plate attached to the sensor housing and the case has been described. The present invention can be implemented even when the body is stretched and the case is pulled and biased toward the main gear.

  In the above embodiment, the first detection gear is meshed with the main gear and the second detection gear is meshed with the first detection gear. However, it is possible to implement the present invention. Moreover, you may be comprised by two or more detection gears meshing with a main gear.

  In the present embodiment, an example in which the present invention is applied to a steering wheel of a vehicle has been shown, but it may be embodied in a machine tool or the like.

  In the present embodiment, an example is shown in which a coil spring is used as the biasing means, but the function can be realized even if a plate spring or a torsion spring is used. Further, an elastic member such as rubber or resin may be used instead of the spring.

1: rotation angle detector, 2: main gear, 3: first detection gear, 4: second detection gear,
5, 6: Magnet, 7, 8: Magnetic angle sensor, 9: Case, 10: Sensor housing,
11: Shaft, 12: Spring, 13: Presser plate, 14, 15: Counterbore hole

Claims (3)

A main gear that rotates in conjunction with a rotating body;
A detection gear that rotates in conjunction with the main gear;
A detected member provided on the detection gear;
Detection means for detecting rotation of the detection gear;
A case for rotatably supporting the detection gear and disposing the detection means;
A sensor housing for inserting the rotating body and attaching the case;
The case is attached to the sensor housing so as to be movable relative to the sensor housing in a state where the main gear and the detection gear can be interlocked, and provided with a biasing means for biasing the case in the main gear direction. A rotation angle detection device characterized by the above.   The rotation angle detection device according to claim 1, wherein the biasing unit is provided between the sensor housing and the case.   An electric power steering device comprising the rotation angle detection device according to claim 1.

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