JP5147531B2 - Rotation angle detection device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of, for example, a steering shaft of a vehicle as an absolute angle and a method for manufacturing the rotation angle detection device.

  This type of rotation angle detection device is suitable for use in detecting the steering operation (rotation angle of the steering shaft) by the driver as an absolute angle, for example, with respect to vehicle attitude control technology. The rotation angle is generally detected by calculating the absolute angle from the phase difference between the rotations of the two driven gears that mesh with the main driving gear while the main driving gear is rotated integrally with the rotation of the steering shaft. The calculation method is adopted.

For this reason, conventionally, as a gear mechanism for generating a phase difference in rotation between two driven gears, prior art in which the driven gears having the same number of teeth are meshed with two main driving gears having different numbers of teeth (for example, patent documents) 1) is known. This prior art has a structure in which the first main driving gear and the second main driving gear having different numbers of teeth are arranged in two stages in the axial direction and arranged concentrically with each other, and the driven gears having the same number of teeth are meshed with each other. . In such prior art, an angle signal corresponding to the rotation angle of each driven gear can be taken out, and the absolute angle of the rotor portion can be detected from the difference between these angle signals and at least one of the angle signals. . In particular, in the prior art, when the maximum rotational speed of the rotor portion is N (N is an integer) and the gear ratio between one main driving gear and the driven gear is n (n is an integer), the number of teeth of the first main driving gear is N. Xn is m times (m is an integer), and the number of teeth of the second main driving gear is m times Nxn-1 (m is an integer).
Japanese Patent Laying-Open No. 2004-340677 (paragraphs 0014 to 0016, Table 1, FIG. 1)

  According to the above prior art, the combination of the number of teeth of each main gear and the number of teeth of the driven gear can be selected from a plurality of patterns, so that the selection range is wide and the degree of design freedom is high. Benefits are gained.

  However, when this type of rotation angle detection device is applied to a steering angle sensor of a vehicle or the like, the space for actually installing the rotation angle detection device (space in the steering column) is limited to some extent, so that the component size becomes extremely large. It is difficult to employ a combination of teeth. Specifically, when the number of teeth difference between the two main driving gears is increased to 2, 3, 4,..., 9 in the prior art, the number of teeth of each main driving gear is doubled and tripled accordingly. The number of teeth of the driven gear is dramatically increased to 2 times, 3 times, 4 times, ..., 9 times. In such a situation, the mechanical parts (various gears) will not fit in the housing due to the increase in size, so the number of teeth is within the practical range even if it is feasible in design. There is no choice but to suppress it.

  Then, this invention makes it a subject to provide the technique which can implement | achieve the combination of the number of teeth with a high freedom within the range suitable for practical use.

In order to solve the above problems, the present invention employs the following solutions.
The present invention is a rotation angle detection device that detects, as an absolute angle, the rotation angle of a detection object that rotates in a range of a predetermined angle exceeding 360 degrees. In particular, the rotation angle detection device of the present invention has a first main driving gear that rotates concentrically with the object to be detected, a number of teeth different from the number of teeth that the first main driving gear has, and together with the first main driving gear. A second main driving gear that rotates concentrically with the object to be detected, a first driven gear that rotates in mesh with the first main driving gear, and a first rotation angle signal corresponding to the rotation angle of the first driven gear. The first signal output unit for output, the second driven gear having a number of teeth different from the number of teeth of the first driven gear and meshing with the second driven gear, and the rotation angle of the second driven gear. A second signal output unit that outputs a corresponding second rotation angle signal and an angle detection unit that detects an absolute angle of the detection target based on the first and second rotation angle signals are provided.

  According to the rotation angle detecting device of the present invention, the number of teeth of the first main driving gear and the number of teeth of the second main driving gear are different from each other, and the number of teeth of the first driven gear and the number of teeth of the second driven gear meshing with each other. Are also different from each other. At this time, the gear ratios of the first main driving gear and the first driven gear, and the second main driving gear and the second driven gear are different, thereby causing a phase difference in the rotation of the two driven gears. An absolute angle can be detected.

  In particular, in the rotation angle detection device of the present invention, even if the number of teeth difference between the first main driving gear and the second main driving gear is set to a number other than 1, each tooth of the first driven gear and the second driven gear that mesh with each other is set. By adjusting the number individually, an appropriate combination of the number of teeth can be set without simply increasing the number of teeth by 2 times, 3 times,... For this reason, even if the difference in the number of teeth between the main driving gears is changed, the overall size does not increase excessively. Accordingly, the degree of design freedom can be increased accordingly.

In the rotation angle detection device of the present invention, the number of teeth of the first main driving gear (Z ₁ ), the number of teeth of the second main driving gear (Z ₂ ), the number of teeth of the first driving gear (S ₁ ), and the number of second driving gears The number of teeth (S ₂ ) can be freely set within a range that satisfies the following conditions.

That is, when the absolute angle range detectable by the angle detector is set as the maximum absolute angle (θmax) that exceeds 360 degrees and is proportional to the number of teeth of the first driven gear (S ₁ ), the number of teeth (Z ₁ , Z ₂ , S ₁ , S ₂ ) is obtained by adding / subtracting an arbitrary natural number (m) to / from the number of teeth (Z ₁ ) of the first main driving gear (Z ₁ ± m) and the ratio of the number of teeth (S ₁ ) of the first driven gear ((Z ₁ ± m) / S ₁ ) to the gear ratio (Z ₂ / S ₂ ) of the second driven gear and the second driven gear. ) Is met.

In this case, if an arbitrary natural number (m) is selected to be the minimum 1, each number of teeth (Z ₁ , Z ₂ , S ₁ , S ₂ ) can be set to the minimum. Further, under the conditions of the present invention, even if an arbitrary natural number (m) is selected as a number other than 1, the number of teeth (Z ₁ , Z ₂ , S ₁ , S ₂ ) is simply doubled accordingly. The number of teeth (Z ₁ , Z ₂ , S ₁ , S ₂ ) having a certain size is within a practically reasonable range because it does not increase three times. It can be set optimally.

In the rotation angle detection device of the present invention, when the maximum absolute angle (θmax) detectable by the angle detection unit is set to an arbitrary number (N) times 360 degrees, the number of teeth of the first driven gear (S ₁ ) Is set to a number (m · N) obtained by multiplying an arbitrary natural number (m) and an arbitrary number (N).

In this case, the number of teeth (S ₁ ) of the first driven gear can be easily set by simply selecting an arbitrary natural number (m) and an arbitrary number (N), and the other number of teeth (Z ₁ , Z ₂ , S ₂ ) can also be set easily.

  Moreover, this invention provides the manufacturing method of a rotation angle detection apparatus. The manufacturing method of the present invention includes the following steps.

[Step 1]
As a detectable range, the maximum absolute angle (θmax) is determined to be an arbitrary number (N) times 360 degrees. In this case, an arbitrary number (N) may be determined from the practical rotation angle of the detection target.

[Step 2]
Next, the number of teeth (S ₁ ) of the first driven gear is determined from the product (m · N) of an arbitrarily selected natural number (m) and an arbitrary number (N). As for the natural number (m), when the minimum 1 is selected as described above, the condition at that time minimizes the number of teeth.

[Step 3]
A value obtained by multiplying a value obtained by multiplying the arbitrarily set gear ratio (K) by an arbitrary number (N) by 1, and then multiplying the value after the addition / subtraction by an arbitrarily selected natural number (m). It is determined as the number of teeth (Z ₁ ) of the first driven gear.

[Step 4]
A combination of the number of teeth of the second main driving gear (Z ₂ ) and the number of teeth of the second driven gear (S ₂ ) is selected under the condition that the relationship of the gear ratio (K) is satisfied. Here, the combination of the number of teeth can be freely selected as long as the relationship of the gear ratio (K) is established, so that the degree of freedom is extremely high.

In the manufacturing method of the present invention, the gear ratio (K) is an integer or a value within a range in which a combination of the number of teeth of the second main driving gear (Z ₂ ) and the number of teeth of the second driven gear (S ₂ ) is established. It can be set from a decimal. In this case, since combinations of more diverse numbers of teeth can be realized, the degree of freedom can be further improved.

  According to the rotation angle detection device and the manufacturing method thereof of the present invention, the number of teeth of each gear can be set with a high degree of freedom. For this reason, it is possible to optimally configure the rotation angle detection device in accordance with various detection objects without greatly changing the existing combination of the number of teeth.

Hereinafter, an embodiment of a rotation angle detection device will be described with reference to the drawings.
FIG. 1 is a perspective view of a rotation angle detection device 10 according to an embodiment. The rotation angle detection device 10 is suitable for use as a steering angle sensor that detects, for example, the rotation angle of a steering shaft of a vehicle as an absolute angle. In this case, the object to be detected is the steering shaft, and the absolute angle detection range is, for example, about five times 360 degrees. However, the present invention is not limited to such conditions.

  The rotation angle detection device 10 is formed with an insertion hole 10a penetrating in the thickness direction at the center thereof, and the rotation angle detection device 10 is in a state where a steering shaft of a vehicle (not shown) is inserted into the through hole 10a. It is attached in a steering column (not shown). In a state where the rotation angle detection device 10 is attached, the rotation center of a steering shaft (not shown) substantially matches the center axis CL of the insertion hole 10a. A plurality of screw insertion holes 10b are formed in the peripheral portion of the rotation angle detection device 10 for fixing to a rotation connector (not shown) mounted in the steering column.

  A housing (housing) of the rotation angle detection device 10 is roughly composed of two parts, a cover 20 and a case 40. A holder 30 is installed between the cover 20 and the case 40. The cover 20 and the case 40 are assembled so as to face each other in the thickness direction (in the direction of the central axis CL) from both sides in a state where the holder 30 is disposed just in the middle.

  The insertion hole 10 a is formed by connecting the cam rotor 50 and the main driving gear unit support body 60. The main driving gear unit support body 60 is integrally formed with the main driving gear unit 12 of a synthetic resin material as a supporting body for supporting the main driving gear unit 12 described later. Each of the cam rotor 50 and the main driving gear unit support 60 has an annular shape, and rotates around the central axis CL with respect to the cover 20, the case 40, and the holder 30. Among these, the cam rotor 50 is formed with a cancel cam 50a at one place in the circumferential direction, and the cancel cam 50a protrudes along the central axis CL. The cancel cam 50a can be used as a mechanism component for returning the turn signal switch (not shown) to the neutral (OFF) position when the left or right operation (ON) is performed, for example.

  Further, the main driving gear unit support body 60 is formed with a connecting portion 60a that protrudes in the opposite direction to the cancel cam 50a at one place (a plurality of places) in the circumferential direction. The connecting portion 60a can be used as a mechanism component that transmits the rotation of the movable housing of the rotary connector to the main gear unit support 60 by being fitted into a concave portion of the movable housing of the rotary connector (not shown). . Here, the movable housing of the rotary connector is directly connected to the steering shaft, and the stationary housing is fixed to the steering column.

  Further, a connector 20a is provided so as to protrude from the upper surface (surface on the front side in the figure) of the cover 20, and the rotation angle detection device 10 is connected to an electronic control unit (in-vehicle ECU) (not shown) via this connector 20a. It has become. As shown in FIG. 1, a plurality of pin insertion holes 20 b (only a part of which are denoted by reference numerals) are arranged on the upper surface of the cover 20. In these pin insertion holes 20b, contact probes are inserted when the electrical characteristics are inspected or software is written in a built-in device after the rotation angle detector 10 is assembled. . In addition, after completion | finish of a test | inspection etc., the pin insertion hole 20b is closed by label sticking which is not illustrated, for example.

  Next, FIG. 2 is a perspective view showing the rotation angle detection device 10 disassembled into main components. Hereinafter, main components of the rotation angle detection device 10 will be described.

  The rotation angle detection device 10 includes a main driving gear unit 12, a first driven gear 14, and a second driven gear 15. Of these, the main drive gear unit 12 is provided with an insertion hole 12a extending through the center thereof. The insertion hole 12a constitutes a part of the insertion hole 10a when the rotation angle detection device 10 is completed. When the rotation angle detector 10 is attached to a steering column (not shown), a steering shaft (detection target) (not shown) is inserted into the through hole 12a of the main gear unit 12, and in this state, the steering shaft is integrated with the steering shaft. The main gear unit 12 rotates.

  A first main driving gear 12 b and a second main driving gear 12 c are formed on the outer peripheral portion of the main driving gear unit 12. The first and second main driving gears 12b and 12c are arranged concentrically with each other in two stages in the axial direction. The first main driving gear 12b and the second main driving gear 12c have different numbers of teeth.

  The first and second driven gears 14 and 15 are meshed with the first and second main driving gears 12b and 12c, respectively. In this state, the first and second driven gears 14 and 15 rotate according to the rotation of the first and second main driving gears 12b and 12c, respectively. The first driven gear 14 and the second driven gear 15 also have different numbers of teeth.

  A magnet 16 is attached to each of the first and second driven gears 14 and 15 with the rotation center as a reference. The magnet 16 is installed in an exposed state on one end face side of each driven gear 14, 15, and rotates integrally with the rotation of the first and second driven gears 14, 15, respectively.

  In the completed state of the rotation angle detection device 10, the main driving gear unit 12 and the two driven gears 14 and 15 are accommodated between the holder 30 and the case 40. That is, an insertion hole 30a is formed in the center of the holder 30, and the holder 30 can rotatably support the main drive gear unit 12 in a state in which the main drive gear unit 12 is fitted in the insertion hole 30a. In the present embodiment, the main driving gear unit 12, the first and second driven gears 14 and 15, and the holder 30 are all made of a synthetic resin material.

  The holder 30 is formed with two support portions corresponding to the two driven gears 14 and 15. Although not shown because it is hidden in FIG. 2, two support portions are each formed in a substantially circular depression shape on one side surface of the holder 30 to which the case 40 is attached. With the driven gears 14 and 15 fitted in the recesses, the driven gears 14 and 15 can be rotatably supported. FIG. 2 shows protrusions 32 that slightly protrude from the other surface of the holder 30 in correspondence with the two support portions.

  The holder 30 is formed with circular openings 30b corresponding to the two support portions. These openings 30b penetrate the holder 30 in the thickness direction, and the openings 30b are positioned to face the rotation regions of the respective magnets 16 in a state where the driven gears 14 and 15 are supported by the support portions. ing.

  In the present embodiment, the case 40 is formed by pressing a thin stainless steel plate (thickness less than 1 mm), for example. A circular insertion hole 40 a is also formed in the center of the case 40, and this insertion hole 40 a constitutes a part of the insertion hole 10 a in the completed state of the rotation angle detection device 10.

  Circular support portions 42 corresponding to the two driven gears 14 and 15 are formed on the inner surface of the case 40, that is, the surface facing the holder 30 in the completed state. These support portions 42 slightly protrude from the inner surface of the case 40 toward the holder 30, and the first and second driven gears 14 and 15 are fitted to the protruding portions, respectively, so that they can be rotatably supported. can do. In the completed state of the rotation angle detection device 10, the case 40 is combined with the holder 30, whereby the first and second driven gears 14 and 15 are accommodated between the case 40 and the holder 30. In this state, the first and second driven gears 14 and 15 are supported such that their one end surfaces and the other end surfaces are sandwiched between the support portion of the holder 30 and the support portion 42 of the case 40, respectively.

  An annular sliding surface 46 is formed on the inner surface of the case 40 around the insertion hole 40a. The sliding surface 46 can guide its smooth rotation while in contact with the other end surface of the main driving gear unit 12.

  The circuit board 70 is attached to the holder 30 on the other surface located opposite to the one surface on which the main driving gear unit 12 and the first and second driven gears 14 and 15 are attached. The circuit board 70 also has an insertion hole 70a at the center. The connector 20a is mounted on one side of the circuit board 70 (the side that does not face the holder 30).

  Two magnetic sensors 72 are mounted on the mounting surface of the circuit board 70 facing the holder 30 so as to correspond to the first and second driven gears 14 and 15, respectively. With the circuit board 70 attached to the holder 30, the magnetic sensors 72 are positioned to face the magnets 16 of the driven gears 14 and 15 through the openings 30b. As a result, when the magnet 16 rotates integrally with the driven gears 14 and 15 in the completed state of the rotation angle detection device 10, changes in the respective magnetic fields are detected by the corresponding magnetic sensors 72. In the present embodiment, for example, a GMR (Giant Magneto-Resitive) sensor is used as the magnetic sensor 72. In addition, the circuit board 70 is mounted with not-shown microprocessors, peripheral devices such as memory devices and I / O, and these are connected through a predetermined wiring pattern.

  The cover 20 is attached to the holder 30 so as to cover the circuit board 70. The cover 20 is also formed by pressing a thin stainless steel plate (thickness less than 1 mm), for example. A taper hole-shaped insertion hole 20c is formed in the center of the cover 20, and the insertion hole 20c constitutes a part of the insertion hole 10a in the completed state of the rotation angle detection device 10, and the cam rotor 50 ( It becomes a fitting part for attaching (refer FIG. 1). The cover 20 is formed with a rectangular insertion hole 24 to expose the connector 20a.

  The holder 30 is attached to the main driving gear unit 12 and the first and second driven gears 14 and 15 by fitting as described above, but the cover 20, the holder 30 and the case 40 are attached to each other by screwing. Is made by. The circuit board 70 is attached to the holder 30 by screwing to the case 40.

  For this reason, the cover 20 is formed with screw insertion holes 22 at a plurality of locations (three locations in this example) on its peripheral edge, and the holder 30 is also formed with screw insertion holes 34 at corresponding positions. Yes. Each case 40 has a female screw portion 44 at a corresponding position. In the completed state of the rotation angle detection device 10, the male screws (not shown in the drawing) are inserted into the screw insertion holes 22 and 34 of the cover 20 and the holder 30. And tighten.

  Further, the circuit board 70 is formed with screw insertion holes 74 at, for example, a plurality of locations (two locations in this example) on the peripheral edge, and the holder 30 is also formed with screw insertion holes 36 at corresponding positions. Yes. Each case 40 has a female screw portion 44 at a corresponding position. In the completed state of the rotation angle detection device 10, the male screws (not shown in the drawing) are inserted into the screw insertion holes 74 and 36 of the circuit board 70 and the holder 30, respectively. Tightened against.

[Configuration pattern]
FIG. 3 is a diagram schematically showing the configuration of the rotation angle detection device 10. In FIG. 3, the first main driving gear 12b, the second main driving gear 12c, and the first and second driven gears 15 are shown in a simplified form in a circular shape. Further, in FIG. 3, a point (●) shown at the center of each gear 12b, 12c, 14, 15 corresponds to the respective rotation center (rotation axis) position.

[First and second main driving gears]
As described above, the first and second main driving gears 12b and 12c are arranged concentrically with a steering shaft (not shown), and these main driving gears 12b and 12c rotate integrally with the steering shaft. Therefore, the absolute angle of the steering shaft matches the absolute angle θ of the first and second main driving gears 12b and 12c.

[First and second driven gears]
On the other hand, the first driven gear 14 is meshed with the first main driving gear 12b and rotates according to the rotation of the first main driving gear 12b. The second driven gear 15 is meshed with the second main driving gear 12b and rotates according to the rotation of the second main driving gear 12c. In addition, as described above, the first main driving gear 12b and the second main driving gear 12b have different numbers of teeth, and the first driven gear 14 and the second driven gear 15 also have different numbers of teeth. In this state, when the first and second main driving gears 12b and 12c rotate integrally with the steering shaft, the first and second driven gears 14 and 15 rotate at different rotation angles α and β, respectively.

[First and second signal output units]
Said magnetic sensor 72 outputs the rotation angle signal according to the rotation angle of the 1st and 2nd driven gears 14 and 15, respectively. That is, each magnetic sensor 72 generates a voltage corresponding to the direction of the magnetic field of the corresponding magnet 16 and digitally converts it to output a rotation angle signal (first and second rotation angle signals). The rotation angle signal at this time includes a Sin component and a Cos component of the rotation angles α and β, respectively.

(Angle detection unit)
The rotation angle signal output from each magnetic sensor 72 is processed by the microprocessor 80 mounted on the circuit board 70. The microprocessor 80 includes a sensor signal processing unit 82, an absolute angle calculation unit 84, and an output processing unit 86 as components to which specific functions are assigned. Among these, the sensor signal processing unit 82 calculates the rotation angles α and β based on the rotation angle signals output from the magnetic sensors 72, respectively. Then, the absolute angle calculation unit 84 calculates a difference between the rotation angles α and β, corrects the difference, and calculates the absolute angle θ. The absolute angle θ calculated by the absolute angle calculation unit 84 is converted into an output signal by the output processing unit 86 and is transmitted to an in-vehicle electronic control unit (not shown) through the connector 20a. Note that the functions of the sensor signal processing unit 82 and the absolute angle calculation unit 84 may be realized by software. In addition, since a known method can be applied to the absolute angle calculation method using the rotation angle signal, the details thereof are omitted here.

[Method of setting the number of teeth]
Next, the setting method of the number of teeth of each gear 12b, 12c, 14, 15 in this embodiment is demonstrated. That is, in this embodiment, in addition to setting the tooth number difference between the first and second main driving gears 12b and 12c, the tooth number difference is also set between the two driven gears 14 and 15. However, if the condition that the relation between the number of teeth is satisfied is satisfied, the absolute angle of the detection object can be detected from the phase difference of rotation generated between the first and second driven gears 14 and 15.

[Various parameters]
In the following, _{Z 1} the number of teeth of the first main driving gear 12b, and the number of teeth of the second main driving gear 12c _{Z 2, S 1} the number of teeth of the first driven gear 14, the number of teeth of the second driven gear 15 _{S 2} And Further, as described above, the absolute angle between the steering shaft and the first and second main driving gears 12b and 12c is θ, the rotation angle detected for the first driven gear 14 is α, and the rotation angle detected for the second driven gear 15 is Let β.

[Maximum absolute angle]
Here, the range of the absolute angle θ that can be detected by the rotation angle detection device 10 is set as the maximum absolute angle θmax that is proportional to the number of teeth S ₁ of the first driven gear 14. That is, the maximum detectable absolute angle θmax is represented by the following formula (1).
θmax = ± 360 ° · S ₁ (1)

Structurally, the number of teeth S ₁ is not provided that one, the maximum absolute angle θmax from the above equation (1) is set in a range always exceeds 360 °. However, considering the use as a steering angle sensor, usually, it is often to select the number of teeth S ₁ of the first driven gear 14, for example, 10 or more. In other words, the range of the maximum absolute angle θmax is excessive for 10 rotations (= 3600 °) if the above equation (1) is maintained. Therefore, if an arbitrary natural number m is selected and the range of the maximum absolute angle θmax is reduced to 1 / m, the above equation (1) is replaced by the following equation (2).
θmax = ± 360 ° · S ₁ / m (2)

At this time, the number of teeth Z ₁ , Z ₂ , S ₁ , S ₂ can be set within a range that satisfies the following conditional expression (3).
(Z ₁ ± m) / S ₁ = Z ₂ / S ₂ (3)

  If the natural number m is selected as 1, the number of teeth is minimized in the conditional expression (3), and the range (detectable range) of the maximum absolute angle θmax is maximized in the above expression (2). .

(Individual calculation formula)
Next, a formula for individually calculating the number of teeth S ₁ , Z ₁ , Z ₂ is derived from the above formula (2) and conditional formula (3). First, an arbitrary number N is selected here, and the maximum absolute angle θmax (measurement range) is set to N times 360 °. Further, assuming that the gear ratio between the first main driving gear 12b and the second main driving gear 12b is K, the number of teeth S ₁ , Z ₁ , Z ₂ is expressed by the following equations (4), (5), (6), respectively. Is done.
S ₁ = m · N (4)
Z ₁ = m · (K · N ± 1) (5)
Z ₂ = K · S ₂ (6)

The inventors of the present invention have a structure in which the number of teeth of the first and second main driving gears 12b and 12c is different from each other and the number of teeth of the first and second driven gears 14 and 15 are also different from each other as in this embodiment. In the above, by setting the number of teeth Z ₁ , Z ₂ , S ₁ , S ₂ satisfying the conditional expression (3) listed above, the number of various teeth can be increased without extremely increasing the size of the entire structure. It has been confirmed that a combination of differences can be realized. Hereinafter, a procedure example for actually setting the number of teeth Z ₁ , Z ₂ , S ₁ , S ₂ will be described. Moreover, one embodiment of the manufacturing method of the rotation angle detection device 10 will be apparent from the following description.

[Number of teeth setting procedure example]
Step 1: The maximum absolute angle θmax that can be detected (measured) by the rotation angle detection device 10 is determined. In this procedure example, for example, it is 10 times 360 °. This gives a condition of N = 10 in the above equation (4).

Step 2: Set the number of teeth _{S 1} of the first driven gear 14. At this time, if an arbitrary natural number m is, for example, the minimum 1, S ₁ can be set to 10 from the above equation (4).

Step 3: Set the number of teeth _{Z 1} of the first main driving gear 12b. Here, when the gear ratio K is 2, it is possible to set the number of teeth Z ₁ from the above equation (5) to 20 ± 1.

Step 4: The numbers of teeth Z ₂ and S ₂ of the second main driving gear 12c and the second driven gear 15 are set. Here, since the gear ratio K is 2, any number of teeth Z ₂ and S ₂ may be selected as long as the combination satisfies the relationship of the above equation (6). That is, theoretically, it is possible to select a combination (Z ₂ , S ₂ ) of all the number of teeth satisfying the gear ratio K = 2. Thus, for example, combinations of the number of teeth (Z ₂ , S ₂ ) = (10, 5), (12, 6), (14, 7), (16, 8), (18, 9), (20, 10) , (22, 11), (24, 12), (26, 13), (28, 14), (30, 25),... be able to. However, in practice, an appropriate combination may be selected from these in consideration of detection accuracy and component size constraints.

In the above setting procedure is set larger than the number of teeth S ₁ of the tooth number S ₂ of the second driven gear 15 the first driven gear 14, but reduce the number of teeth S ₂ than the number of teeth S ₁ in the opposite It may be set. As a result, the number of teeth Z ₁ , Z ₂ , S ₁ , S ₂ can be set in a very wide range, so that it can be seen that the method of this embodiment has a high degree of freedom of selection. In the above procedure example, the gear ratio K is a natural number. However, even if the gear ratio K is expressed by a decimal number, the number of teeth can be set within a range that satisfies the conditional expression (3).

[Correspondence when the number of teeth difference is changed]
Furthermore, the structure of the present embodiment has excellent flexibility in dealing with the case where a change in the number of teeth is required. Hereinafter, this point will be described.

For example, it is assumed that the number of teeth Z ₁ and Z ₂ of the first and second main driving gears 12b and 12c is determined as an existing setting. In this case, the optimum size of the main drive gear unit 12 is designed based on the set conditions of the number of teeth Z ₁ and Z ₂ , and this size is adapted to the size of the steering shaft that is the detection target. And

In such a situation, for example, when a change occurs in the specification (for example, the outer diameter) of the steering shaft that is a detection target, or a change occurs in a space where the rotation angle detection device 10 can be installed, the rotation angle detection device 10. When the size of the tooth itself is changed, it may be necessary to adjust the difference in the number of teeth by newly setting the number of teeth Z ₁ and Z ₂ . Even in this case, the structure of the present embodiment maintains the existing gear ratio K and the range of the maximum absolute angle θmax without drastically changing the existing size, and the number of teeth Z ₁ , Z ₂ , S ₁ and S ₂ can be flexibly changed.

[Relationship between number of teeth difference and maximum number of teeth]
That is, as a result of verification by the inventors of the present invention, the difference in the number of teeth (| Z ₂ −Z ₂ |) between the first main driving gear 12b and the second main driving gear 12c is, for example, 1, 2, 3,. Even if it is changed, it has been confirmed that the difference in the number of teeth at that time and the maximum number of teeth are not simply increased.

FIG. 4 is a diagram showing the relationship between the difference in the number of teeth and the maximum number of teeth in comparison between the example and the comparative example. In FIG. 4, the horizontal axis represents the difference in the number of teeth (| Z ₂ −Z ₁ |) between the first main driving gear 12b and the second main driving gear 12c, and the vertical axis represents the maximum set under the condition of the respective number of teeth difference. Represents the number of teeth (Z ₂ or Z ₁ ). Further, in FIG. 4, hatched square symbols indicate the results obtained from the example when the structure of the present embodiment is applied, and diamond-shaped symbols with halftone dots are obtained from the comparative example. Results are shown. In addition, the comparative example here is a result in the case of adopting the structure (a structure in which there is a difference in the number of teeth in the main driving gear and no difference in the number of teeth in the driven gear) described in the prior art (Patent Document 1) already described. is there.

  As shown in FIG. 4, when the structure of the present embodiment is adopted, the maximum number of teeth is not simply increased even if the number of teeth difference is increased. It can be seen that it is within (for example, within 50).

  On the other hand, in the comparative example, as the difference in the number of teeth increases, the maximum number of teeth tends to increase proportionally. In this case, since the members are inevitably increased in size as the maximum number of teeth is increased, the degree of freedom in design is reduced when the installation space of the rotation angle detection device 10 is limited.

  On the other hand, in the structure of this embodiment, even if the difference in the number of teeth increases, the maximum number of teeth does not vary greatly. Since the number of teeth can be changed, the degree of freedom in design is high.

The present invention can be implemented with various modifications without being limited to the above-described embodiment. In one embodiment, an example is large number of teeth Z ₂ of the second main driving gear 12c than the number of teeth Z ₁ of the first main driving gear 12b, but they may be inversely related. The same applies to the relationship between the number of teeth S ₁ and S ₂ of the first driven gear 14 and the second driven gear 15.

The numerical values given in the setting procedure of the number of teeth Z ₁ , Z ₂ , S ₁ , S ₂ are merely examples, and the selection of an arbitrary number N, a natural number m, and a gear ratio K can be changed as appropriate. .

  In addition, the rotation angle detection device of the present invention is not limited to a use as a vehicle steering angle sensor, but can be widely applied to a use for detecting an absolute angle of an object to be detected that performs various rotational motions.

It is a perspective view of the rotation angle detection apparatus of one Embodiment. It is the perspective view which decomposed | disassembled and showed the rotation angle detection apparatus to the main components. It is the figure which showed schematically the structure of the rotation angle detection apparatus. It is the figure which contrasted and showed the Example and the comparative example about the relationship between the number of teeth difference, and the maximum number of teeth.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotation angle detector 12 Main drive gear unit 12b First main drive gear 12c Second main drive gear 14 First driven gear 15 Second driven gear 16 Magnet 20 Cover 30 Holder 40 Case 70 Circuit board 72 Magnetic sensor 80 Microprocessor

Claims (4)

A rotation angle detection device that detects, as an absolute angle, a rotation angle of a detection object that rotates within a range of a predetermined angle exceeding 360 degrees,
A first main gear that rotates concentrically with the object to be detected;
A second main driving gear having a number of teeth different from the number of teeth of the first main driving gear and rotating integrally with the detection object together with the first main driving gear;
A first driven gear that meshes with and rotates with the first main driving gear;
A first signal output unit that outputs a first rotation angle signal corresponding to the rotation angle of the first driven gear;
A second driven gear having a number of teeth different from the number of teeth of the first driven gear and rotating in mesh with the second main driving gear;
A second signal output unit for outputting a second rotation angle signal corresponding to the rotation angle of the second driven gear;
And a angle detector for detecting the absolute angle of the detection object based on the first and second rotation angle signal,
The number of teeth of the first driving gear (Z ₁ ), the number of teeth of the second driving gear (Z ₂ ), the number of teeth of the first driven gear (S ₁ ), and the number of teeth of the second driven gear (S ₂ )
When the absolute angle range detectable by the angle detection unit is set as a maximum absolute angle (θmax) that exceeds 360 degrees and is proportional to the number of teeth of the first driven gear (S ₁ ),
By adding or subtracting an arbitrary natural number (m) to the number of teeth (Z ₁ ) of the first main driving gear, the number (Z ₁ ± m) after this adjustment and the number of teeth (S ₁ of the first driven gear) )) ((Z ₁ ± m) / S ₁ ) is set under the condition of matching the gear ratio (Z ₂ / S ₂ ) between the second main driving gear and the second driven gear . A rotation angle detection device characterized by that. The rotation angle detection device according to claim 1,
When the maximum absolute angle (θmax) detectable by the angle detection unit is set to an arbitrary number (N) times 360 degrees,
The number of teeth (S ₁ ) of the first driven gear is set to a number (m · N) obtained by multiplying the arbitrary natural number (m) and the arbitrary number (N). Rotation angle detector. A first main driving gear that rotates concentrically with a detection object that rotates in a predetermined angle range exceeding 360 degrees, and has a number of teeth different from the number of teeth that the first main driving gear has, and A second main driving gear that rotates together with the first main driving gear concentrically with the object to be detected, a first driven gear that rotates in mesh with the first main driving gear, and a rotation angle of the first driven gear. A first signal output unit that outputs a first rotation angle signal corresponding to the first driven gear, and a second driven gear that has a number of teeth different from the number of teeth of the first driven gear and that rotates in mesh with the second main driving gear. And a second signal output unit that outputs a second rotation angle signal corresponding to the rotation angle of the second driven gear, so that the absolute value of the detection object is determined based on the first and second rotation angle signals. In the manufacturing method of the rotation angle detection device for detecting the angle,
  Determining a maximum absolute angle (θmax) as an arbitrary number (N) times 360 degrees as a detectable range;
  Number of teeth of the first driven gear (S ₁ ) Is determined from the product (m · N) of an arbitrarily selected natural number (m) and the arbitrary number (N);
  Obtained by multiplying the arbitrarily set gear ratio (K) by 1 to the value obtained by multiplying the arbitrary number (N) and then multiplying the value after the addition / subtraction by the arbitrarily selected natural number (m). The number of teeth of the first driven gear (Z ₁ ) Step to determine as
  The number of teeth of the second main driving gear (Z ₂ ) And the number of teeth of the second driven gear (S ₂ And a combination with the gear ratio (K) are selected under the condition satisfying the relationship of the gear ratio (K);
A manufacturing method of a rotation angle detecting device having In the manufacturing method of the rotation angle detection device according to claim 3,
The gear ratio (K) can be set from an integer or a decimal number within a range in which a combination of the number of teeth (Z ₂ ) of the second main driving gear and the number of teeth (S ₂ ) of the second driven gear is established. A method of manufacturing a rotation angle detecting device.

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