JP2005134238A - Driving condition stabilizer for car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize structure capable of finding the rotational speed of a wheel of a car quickly and accurately when the wheel rotates unstationarily, and performing appropriate control for stabilizing the driving condition of the car. <P>SOLUTION: The time difference between a moment when the boundary part between a S pole and a N pole existing on a surface to be detected of an encoder 7a passes a position just before one detecting element 13a of a pair of detecting elements 13a, 13b, and a moment when the part passes a position just before the other detecting element 13b in the same way is found. A command signal for performing control for stabilizing driving according to the variations of data on time differences at each of these boundary parts, caused by variations in the rotational speed of the wheel is output. If the pitch D of both detecting elements 13a, 13b is regulated accurately, the rotational speed of the encoder 7a can be found accurately and quickly, even if the precision of the pitch P of changes in property of the surface to be detected is not made higher especially, and former problems can be solved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improvement in a vehicle running state stabilization device that detects fluctuations in the rotational speed of wheels of a vehicle, particularly an automobile, and performs control for ensuring running stability of the vehicle.

  Conventionally, as a device for ensuring the running stability of a vehicle, an anti-lock brake system (ABS), a traction control system (TCS), and a stability control device having a structure such as a combination of these ABS and TCS have been used. Are known. In each of these systems and devices, signals such as an acceleration sensor that detects acceleration applied to the vehicle and a yaw rate sensor that detects the yaw rate are compared with each rotation speed detection sensor that detects the rotation speed of each wheel. Estimate the slip ratio of the contact portion between each wheel and the road surface. When the slip rate of each contact portion exceeds a predetermined threshold, the brake attached to each wheel exerts an appropriate braking force, or the engine output is controlled (decreased). Ensure driving stability.

  In any system or device, in order to ensure the running stability of the vehicle, it is necessary to detect the rotational speed of the wheel supported by the suspension device by the rolling bearing unit. For this purpose, various rotational speed detection devices have been proposed and used in practice. For example, Patent Document 1 describes a rotational speed detection device as shown in FIGS. In this rotational speed detection device, a rotating shaft 2 is rotatably supported by a bearing 3 on the inner diameter side of a housing 1 that does not rotate even when in use. Further, the end opening of the space 4 between the outer peripheral surface of the rotating shaft 2 and the inner peripheral surface of the housing 1 is closed by a combination seal ring 5. An annular encoder 7 is attached to the outer surface of the slinger 6 constituting the combination seal ring 5. The encoder 7 is a permanent magnet such as a rubber magnet and is magnetized in the axial direction. The magnetization direction is changed alternately at an equal pitch with respect to the circumferential direction. Therefore, N poles and S poles are alternately arranged on the outer surface of the encoder 7 at an equal pitch.

  On the other hand, a rotational speed detection sensor 8 is supported on the housing 1, and a detection portion of the rotational speed detection sensor 8 is made to face and face an outer surface which is a detection surface of the encoder 7. The rotational speed detection sensor 8 includes a magnetic detection element whose characteristics change according to the direction and strength of the magnetic flux, such as a Hall element, a magnetoresistive element (MR element), etc., and responds to the change in the characteristics of the magnetic detection element. Change the output signal. When the rotating shaft 2 rotates, the S pole and the N pole disposed on the outer surface of the encoder 7 alternately pass through the vicinity of the end face of the detection portion of the rotational speed detection sensor 8. For this reason, the characteristics of the magnetic detection element incorporated in the rotational speed detection sensor 8 change, and the output of the rotational speed detection sensor 8 changes. The frequency at which the output of the rotational speed detection sensor 8 changes in this way is proportional to the rotational speed of the rotary shaft 2.

  Therefore, if the output of the rotational speed detection sensor 8 is sent to a processing circuit (not shown), the rotational speed of the rotary shaft 2 can be obtained (or a signal corresponding to the rotational speed is obtained). In this processing circuit, in order to obtain the rotational speed of the rotary shaft 2 based on the output signal of the rotational speed detection sensor 8, a method of obtaining from the change period of the output signal and the number of changes per unit time ( Frequency). The rotational speed is inversely proportional to the period and is proportional to the frequency.

  In order to obtain the rotation speed of the rotating shaft 2 in real time, it is preferable to obtain the rotation speed from the period of change in the output signal of the rotation speed detection sensor 8. By calculating from the frequency of this change, the rotational speed can be determined only every predetermined time (unit time) that is several times to several tens of times the period. For this reason, a difference is likely to occur between the obtained rotational speed and the instantaneous rotational speed, and the ABS and TCS cannot be appropriately controlled by the obtained rotational speed. On the other hand, if the rotational speed is obtained from the period of change of the output signal, the difference between the obtained rotational speed and the instantaneous rotational speed can be almost eliminated, and the ABS or TCS can be determined depending on the obtained rotational speed. Can be controlled appropriately.

  However, in order to accurately obtain the rotation speed from the period of change of the output signal, it is necessary to accurately regulate the pitch at which the characteristic of the detected portion of the encoder 7 changes in the circumferential direction. Even if the rotational speed is the same, if the pitch is longer than the design value, the period of change of the output signal becomes longer, and if the pitch is shorter, the period becomes shorter. For this reason, from the period of change of the output signal, the pitch at which the characteristic of the detected portion of the encoder 7 changes is equal over the entire circumference in the portion facing the detection portion of the rotational speed detection sensor 8. Necessary for obtaining the rotational speed accurately.

On the other hand, the pitch may be different in the circumferential direction for the following two reasons (1) and (2).
(1) Manufacturing error of encoder 7.
(2) Encoder 7 assembly error.
Of these, (1) occurs because the pitch for changing the magnetization direction of the encoder 7 becomes non-uniform in the circumferential direction. The above (2) occurs when the geometric center of the detected surface of the encoder 7 and the rotation center are shifted. When the detected surface is present on the side surface in the axial direction, the magnetization width of the detected portion becomes wider toward the outer side in the radial direction, so that the S pole and the N pole change when both the centers deviate. The pitch is not uniform in the circumferential direction. In any case, if the change pitch becomes non-uniform in the circumferential direction, the rotation speed cannot be accurately obtained from the change cycle of the output signal of the rotation speed detection sensor 8. Such a problem occurs not only in the combination of the encoder 7 made of a permanent magnet and the rotation speed detection sensor 8 incorporating the magnetic detection element, but also in a combination of an encoder having another structure and the rotation speed detection sensor.

  Patent Document 2 describes that in a permanent magnet encoder, the difference in pitch at which the S pole and the N pole change is suppressed to ± 2% or less. According to the technique described in Patent Document 2 as described above, the accuracy in obtaining the rotation speed from the period of change in the output signal of the rotation speed detection sensor 8 can be improved to some extent. However, as the pitch accuracy is increased, the production cost of the permanent magnet encoder is inevitably increased, and there is a limit to increasing the pitch accuracy of the permanent magnet encoder. Moreover, even if the pitch accuracy of the permanent magnet encoder is increased, the error due to the above (2) cannot be eliminated. In order to minimize the error due to (2), it is necessary to increase the assembly accuracy, and it is inevitable that the cost will increase. Therefore, at present, a structure for obtaining the rotational speed from the period of change in the output signal of the rotational speed detection sensor 8 is employed, and the rotational speed accuracy is increased (for example, error) based on the improvement of the pitch accuracy of the permanent magnet encoder. Is less than 1%).

In view of such circumstances, the present inventor quickly changes the rotational speed of the wheel during a so-called unsteady rotation (with high response), such as during acceleration or deceleration. Moreover, in order to obtain accurately and perform appropriate control in order to stabilize the traveling state of the vehicle, it has been considered that the following is important.
That is, the rotational angular velocity of this encoder is obtained with high accuracy for each boundary portion where the characteristics change on the detected surface of the encoder that rotates together with the wheel, and each time this boundary portion passes the detection portion of the rotational speed detection sensor. It was considered that the above-mentioned purpose (high response and accuracy) could be achieved if vehicle traveling control was performed according to the obtained fluctuation of the rotational angular velocity.

  Conventionally, techniques described in Patent Documents 3 to 6 are known as techniques for obtaining a value related to the rotation speed of an encoder using a pair of sensors. Among these, the prior art described in Patent Documents 3 and 4 has a detection signal of a pair of rotation detection sensors provided in a state of being opposed to the detection surface of the encoder and spaced apart in the rotation direction of the encoder. The rotation direction of the encoder can be determined by the changing timing. The prior art described in Patent Documents 5 and 6 is opposed to the detection surface of the encoder supported by the rotating shaft that rotates at a substantially constant speed (steady rotation) and is separated in the rotation direction of the encoder. The torsional vibration of the rotating shaft is measured at the timing when the detection signals of the pair of rotation detection sensors provided in the state change.

  In any of Patent Documents 3 to 6 described above, by using a pair of rotation detection sensors, the rotation speed of a wheel changes rapidly, and this rotation speed is obtained quickly and accurately during so-called unsteady rotation. Thus, there is no description of a technique for performing appropriate control in order to stabilize the traveling state of the vehicle. Further, even a description suggesting that the above-described object is achieved by a structure incorporating a pair of rotation detection sensors is not described in any of Patent Documents 3 to 6.

JP-A-8-338435 JP 2002-155962 A Japanese Utility Model Publication No. 2-120017 JP-A-6-174736 JP-A-62-291519 JP-A-6-307922

  In view of the circumstances as described above, the present invention is to obtain the rotation speed quickly and accurately at the time of so-called unsteady rotation in which the rotation speed of the wheel changes rapidly, in order to stabilize the traveling state of the vehicle. The present invention has been invented to realize a vehicular running state stabilization device capable of performing appropriate control.

The vehicle running state stabilization device of the present invention includes the following (a) to (c).
(a) An encoder that is provided concentrically with a rotating member that rotates together with the wheel, and in which characteristics of the detected surface are alternately changed in the circumferential direction.
(b) A rotational speed supported by a fixed member provided in the vicinity of the rotating member, with a pair of detecting portions facing each of the detection surfaces provided in a state of being separated in the circumferential direction of the encoder Detection sensor.
(c) The moment when the boundary portion of the encoder on which the characteristic is changed passes the position immediately before one of the pair of detection units, and the position immediately before the other detection unit. A time difference data processing unit that obtains a time difference from the moment of passing through each boundary portion where the direction of characteristic change coincides, and fluctuations in time difference data at each boundary portion due to wheel speed fluctuations A controller having a traveling control unit that issues a command signal for performing control for stabilizing the traveling according to the control.

  The above-mentioned “boundary portion where the direction of characteristic change coincides” is, for example, when the encoder is made of a permanent magnet, and the S pole and the N pole are alternately arranged on the detected surface of the encoder. For example, it refers to a boundary portion that changes from the S pole to the N pole (or conversely, a boundary portion that changes from the N pole to the S pole). In the case of an encoder made of a magnetic material, it refers to a boundary portion that changes from a magnetic portion to a nonmagnetic portion (or conversely, a boundary portion that changes from a nonmagnetic portion to a magnetic portion). In short, regarding both the detection units, the characteristic change in the same direction is detected, and the process related to the command signal is performed based on the time difference.

  According to the vehicle running state stabilization device of the present invention configured as described above, the rotational speed v can be obtained quickly and accurately during unsteady rotation in which the rotational speed of the wheel changes rapidly, and the vehicle travels. Appropriate control can be performed to stabilize the state. That is, the detection signals of the pair of detection units provided in the rotation speed detection sensor change with the rotation of the encoder, but the timing at which the detection signals of both the detection units change relates to the rotation direction of the encoder. It shifts according to the pitch D of both detection parts. Specifically, the higher the rotational speed v of the encoder, the smaller the deviation in timing at which the detection signals of the two detection units change (the deviation time T is shorter). Therefore, the rotational speed v can be obtained based on the pitch D of these two detection units and the deviation time T (v∝D / T).

  When the rotational speed v is obtained in this way, the accuracy of the pitch at which the characteristics of the detected surface of the encoder change does not affect the measurement accuracy of the rotational speed v. It is the pitch D of the pair of detectors that affects the measurement accuracy. Ensuring the accuracy of the pitch D is easier than securing the accuracy of the characteristic change of the detected surface. For example, when a magnetic detection element such as a Hall element is used as the both detection units, it is conceivable to install the magnetic detection element on a semiconductor substrate. Such installation work can be performed with extremely high accuracy without particularly increasing the cost by a high-precision semiconductor manufacturing apparatus widely used in the semiconductor manufacturing field. Therefore, the rotational speed v can be obtained with high accuracy without particularly increasing the cost.

  Further, the rotational speed v is obtained every time a boundary portion whose characteristics change among the detection surfaces of the encoder passes between the detection portions. Therefore, the rotation speed v can be obtained many times during one rotation of the encoder. For this reason, the rotational speed of the wheel can be obtained almost in real time, and the control for running stability of the vehicle can be performed more appropriately.

Preferably, when carrying out the present invention, as described in claim 2, the pitch of the pair of detection portions provided in the rotational speed detection sensor is set to be the smallest of the pitches of the characteristic change of the detected surface of the encoder. Less than the pitch.
If comprised in this way, the said rotational speed v can be calculated | required by the frequency | count of the characteristic of the said to-be-detected surface changing, while the said encoder carries out 1 rotation.

Preferably, as described in claim 3, the difference in the pitch of the characteristic change of the detected surface of the encoder is within ± 2%.
With this configuration, even if the pitch D between the two detection units is increased to some extent, the magnitude relationship between the pitch and the characteristic change pitch can be prevented from being reversed for each characteristic change portion. It is necessary for the magnitude relationship not to be reversed for each characteristic change portion in order to obtain the rotational speed v based on the timing difference at which the detection signals of the two detection units change. Increasing the pitch D of both the detection units leads to facilitation of ensuring the accuracy of the pitch D, and further to increasing the accuracy of rotation speed detection obtained in proportion to the pitch D.

Preferably, as described in claim 4, the number of pitches of the characteristic change of the detected surface of the encoder is set to 50 to 100.
If comprised in this way, regarding a rotation speed detection of a wheel, it is possible to achieve both accuracy ensuring and response improvement at a high level. That is, in order to improve the response of detecting the rotational speed of the wheel, it is effective to increase the number of times the rotational speed v is obtained while the wheel rotates once. In other words, the greater the number of times, the higher the resolution related to the detection of the rotational speed v, and the finer control is possible from the viewpoint of ensuring the running stability of the vehicle.
If the number of pitches of the characteristic change of the detected surface is ensured to be 50 or more, the response or resolution is sufficiently increased, and a high degree of control is possible with respect to ensuring the running stability of the vehicle.
On the other hand, it is difficult from the viewpoint of cost to manufacture an encoder in which the number of pitches of the characteristic change exceeds 100. Moreover, in order to obtain the rotational speed v by making use of this number of pitches (enabling the detection of rotational speeds for the number of pitches for each rotation of the wheel), the pitches of the two detecting sections must be made considerably small. Don't be. It is not only technically difficult to make the pitches of these two detection units extremely small, but even if it can be made, it is difficult to ensure the accuracy of the pitch, and the detection accuracy of the rotational speed v deteriorates.
On the other hand, if the number of pitches of the characteristic change is suppressed to 100 or less, the above-described problem does not occur.

Further, preferably, as described in claim 5, the controller is provided with a rotation direction determination processing unit. The rotation direction determination processing unit determines the rotation direction of the encoder based on the front and back of the moment when the boundary portion passes the position immediately before the one detection portion and the moment when the boundary portion passes the position immediately before the other detection portion. .
If comprised in this way, not only driving | running | working stability ensuring when the vehicle moves forward but driving | running | working stability ensuring at the time of reverse | retreating can also be aimed at.

1-3 show Example 1 of the present invention. The vehicle running state stabilization device of this embodiment includes an encoder 7a, a rotational speed detection sensor 8a, and a controller 9. The controller 9 includes a time difference data processing unit and a travel control unit.
Of these, the encoder 7a is externally fitted and fixed to an intermediate portion of the rotary shaft 2 that rotates with a wheel (not shown). In the case of the present embodiment, the encoder 7 a is formed by combining the support ring 10 and the permanent magnet 11. Of these, the support ring 10 is formed by bending a magnetic metal plate such as a mild steel plate to form an annular shape as a whole with an L-shaped cross section. The permanent magnet 11 is a rubber magnet in which a ferromagnetic powder such as ferrite is mixed in rubber, and is magnetized in the axial direction (left-right direction in FIG. 1, front-back direction in FIG. 2). The magnetization direction changes alternately and at an equal pitch with respect to the circumferential direction. Therefore, the south pole and the north pole are alternately arranged in the circumferential direction on one side surface (the right side surface in FIG. 1) of the permanent magnet 11, which is the detected portion of the encoder 7a. It should be noted that the pitch of the change between the S pole and the N pole is preferably equal in the circumferential direction, but is not required to be as strict as in the case of the conventional structure. In extreme cases, the pitches may be different.

  The encoder 7a as described above is fixed around the intermediate portion of the rotary shaft 2 by fitting the cylindrical portion 12 formed on the inner peripheral edge of the support ring 10 to the rotary shaft 2 with an interference fit. Yes. In this state, the permanent magnet 11 is arranged substantially concentrically with the rotating shaft 2. The permanent magnet 11 and the rotating shaft 2 are preferably concentric with each other, but are not required to be as strict as in the conventional structure.

  The rotational speed detection sensor 8a includes a pair of detection elements 13a and 13b, each of which constitutes a detection unit. In the case of the present embodiment, these detection elements 13a and 13b are installed on the IC wafer substrate 14 with a predetermined pitch D (center angle θ). That is, each of the detection elements 13a and 13b, each of which is a magnetic detection element such as a Hall element or a magnetoresistive element, changes the output of the detection elements 13a and 13b on a semiconductor wafer substrate 14 such as a silicon substrate. It is mounted with a circuit that takes out and performs waveform processing. This circuit creates a rectangular wave corresponding to the change in the characteristics of both detection elements 13a and 13b. The rotational speed detection sensor 8a provided with such detection elements 13a and 13b is configured so that each of the detection elements 13a and 13b, which serve as detection units, faces one side surface of the permanent magnet 11 constituting the encoder 7a. In this state, it is supported by a stationary member such as a bearing housing and a knuckle (both not shown) constituting the suspension device.

  In this state, the detection elements 13a and 13b (detection centers thereof) are shifted from the rotation center of the encoder 7a by a predetermined pitch D (angle θ with respect to the rotation center) with respect to the rotation direction of the encoder 7a. Are arranged on the same arc. In the case of the present embodiment, the pitch D is smaller than the pitch P between the S poles (or N poles) arranged on one side of the permanent magnet 11 at the same radius portion (D <P). ing. When the encoder 7a rotates together with the rotary shaft 2, the detection elements 13a and 13b output output signals (rectangular waves) a and b as shown by solid lines or broken lines in FIG. The phases of the output signals of these detection elements 13a and 13b are shifted by a time T corresponding to the pitch D. The magnitude of the deviation time T is inversely proportional to the rotational speed of the encoder 7a.

Therefore, the time difference data processing unit of the controller 9 measures the deviation time T (sec) of the output signals a and b of the detection elements 13a and 13b shown in FIG. 3, and this deviation time T (sec). From this, the rotational speed N (min ⁻¹ ) of the encoder 7a (the rotating shaft 2 with the fixed shaft) is calculated by the following equation (1) or (2). The calculated result is sent to the travel controller of the controller 9. The controller 9 is not necessarily arranged near both the detection elements 13a and 13b, and may be arranged on the vehicle body side (not shown).
N = (60 / πT) × sin ⁻¹ (D / 2r) −−− (1)
N = (30 / π) × (θ / T) −−− (2)

Further, the time difference data processing unit of the controller 9 is a signal representing the deviation time T (sec) of these signals from the output signals a and b of the detection elements 13a and 13b, as indicated by chain lines in FIG. You may make it produce c and send this signal to the travel control part provided in the vehicle body side which is not shown in figure. In this case, the traveling control unit determines that the encoder 7a (the rotating shaft 2 with the fixed shaft) is obtained from the deviation time T (sec) according to the above equation (1) or (2) as in the case described above. The rotation speed of is calculated.
Of the above formulas (1) and (2), formula (1) is obtained from the pitch D between the detection elements 13a and 13b with respect to the rotation direction of the encoder 7a. The cases where the detection elements 13a and 13b are obtained from the angle (center angle pitch) θ with respect to the rotation center of the encoder 7a are shown.
In the above equation (1), r is the distance (rotation radius) from the rotation center of the encoder 7a to the portion where the detection elements 13a and 13b are opposed to each other. Since the angle θ and the pitch D satisfy the following expression (3), if any of them is known, the rotational speed N can be obtained.
θ = 2sin ⁻¹ (D / 2r) −−− (3)

  The time difference data processing unit, which has obtained the rotational speed N by any one of the formulas (1) and (2), sends a signal representing the rotational speed N to the travel control unit. When the signal of the deviation time T created by the time difference data processing unit is sent to the traveling control unit, the rotational speed N is obtained by the traveling control unit. Based on the signal representing the rotational speed N, the traveling control unit issues a command signal for performing control for stabilizing the traveling. That is, the travel control unit is based on a signal representing the rotational speed N, which is sent from the time difference data processing unit or is obtained by the travel control unit based on a signal sent from the time difference data processing unit. Then, the state of the rotational speed fluctuation of the wheel is obtained, and a command signal is issued for performing control that leads to stabilization of traveling. In this case, the traveling control unit obtains the actual traveling speed or acceleration of the vehicle (including deceleration which is a negative acceleration) obtained separately and the traveling speed or acceleration relating to each wheel obtained from the rotational speed N. Thus, the grip state (slip rate) of each wheel is obtained. This point will be described below assuming that the rotation speed can be detected n times while each wheel makes one rotation.

When the encoder 7a is rotated together with each wheel, the boundary of the part that moves from the N pole to the S pole (or the part that moves from the S pole to the N pole) on the detection surface of the encoder 7a is the detection element 13a, 13b. The output signals of both detection elements 13a and 13b change back and forth. At this time, the deviation time T in which the output signals of both the detection elements 13a and 13b change back and forth varies inversely proportional to the rotational speed N of the encoder 7a. The deviation time T is calculated while the encoder 7a makes one revolution. N times. If k is a natural number of 1 to _n , n shift times T ₁ , T ₂ --T _k --- T _n are obtained during one rotation, and based on each shift time. , Ω ₁ , ω ₂ −−− ω _k −−− ω _n , n angular velocities are obtained. If these angular velocities ω ₁ , ω ₂ --- ω _k ---- ω _n are multiplied by the radius of rotation R, which is the distance between the center of rotation of each wheel and the ground contact surface (when ω _k · R is obtained). Then, the peripheral speed of each of these wheels at the contact surface portion is obtained.

On the other hand, the actual traveling speed or acceleration of the vehicle can be arbitrarily set by integrating the detection value of the acceleration sensor installed on the vehicle side, or by processing the road surface photographed by the CCD provided on the vehicle body. You can find it almost instantaneously in real time. Accordingly, the peripheral speed ω _k · R of each wheel at the ground contact surface portion obtained based on the output of the rotational speed detection sensor 8a including both the detection elements 13a and 13b, and the actual traveling at the same moment. The speed V _k can be compared. When slip does not occur on the ground contact surface portion, the actual traveling speed V _k coincides with the peripheral speed ω _k · R (V _k = ω _k · R). On the other hand, when slip occurs on the ground contact surface portion, the actual traveling speed V _k and the peripheral speed ω _k · R do not coincide (V _k ≠ ω _k · R). For example, if slip occurs during deceleration for braking, the actual traveling speed V _k becomes larger than the peripheral speed ω _k · R (V _k > ω _k · R). In this case, the slip ratio S _k at the contact surface portion is expressed by S _k = 1−ω _k · R / V _k . On the other hand, if slip occurs during acceleration, the peripheral speed ω _k · R becomes larger than the actual traveling speed V _k (ω _k · R> V _k ). In this case, the slip ratio S _k at the ground contact surface portion is expressed by S _k = 1−V _k / (ω _k · R).

Running control section of the controller 9 obtains the slip ratio S _k at the each wheel, (to close to zero) in order to reduce the value of the slip ratio S _k, suitably brake the accessory of each wheel The braking force is exerted, or the engine output is controlled (decreased). That the slip ratio S _k of said each wheel is reduced is that the grip of the wheels is ensured, leading to running stability ensuring the vehicle.

As described above, in the case of the vehicle running state stabilization device of this embodiment, the rotational speed of the encoder 7a is calculated based on the deviation time T between the detection signals a and b of the detection elements 13a and 13b. For this reason, for example, each time the characteristic changes in the part to be measured of the encoder 7a, that is, the boundary between the S pole and the N pole passes between the detection parts of the pair of detection elements 13a and 13b. In addition, the rotational speed of the encoder 7a can be calculated. Since there are many boundaries on one side of the encoder 7a, the rotational speed can be obtained almost in real time. In addition, since the pitch D between the detecting portions of the detecting elements 13a and 13b does not change regardless of the rotation of the encoder 7a, the rotation speed is set regardless of the manufacturing error or assembly error of the encoder 7a. Accurately required. In particular, the direction and rate of fluctuation of the travel speed V _k can be accurately obtained regardless of the manufacturing error or assembly error of the rotational speed sensor 8a.

  In order to effectively use the characteristic change of the encoder 7a from the aspect of obtaining the rotation speed in almost real time, the pitch D of the pair of detection elements 13a and 13b is changed to the characteristic change of the detected surface of the encoder 7a. The pitch P is preferably less than the minimum pitch Pmin. The number of times the rotation speed can be obtained varies depending on the size of the pitch D of the pair of detection elements 13a and 13b. Specifically, the upper limit of the number of times that the rotation speed can be obtained during one rotation of the encoder 7a is 360 degrees / θ (D). Therefore, if the pitch D of the pair of detection elements 13a and 13b is larger than the pitch P of the characteristic change, it is meaningless to increase the characteristic change. On the other hand, if D <Pmin, the characteristic change of the encoder 7a can be used effectively.

  Further, based on the timing when the detection signals a and b of the detection elements 13a and 13b change as indicated by the upper solid line and the middle broken line in FIG. You can also know the direction of rotation. However, in order to obtain the rotation direction, it is necessary to set the pitch D to a length other than ½ of the pitch P (D ≠ P / 2). If the pitch D is exactly ½ of the pitch P, the difference in timing at which the detection signals a and b of the detection elements 13a and 13b change is equal regardless of which direction the encoder 7a rotates. Therefore, the rotation direction cannot be obtained.

  In the case of the present embodiment, since both the detection elements 13a and 13b are installed on the same wafer substrate 14, the operation characteristics (threshold, hysteresis, temperature characteristics, etc.) of the both detection elements 13a and 13b are substantially the same. Can be the same. For this reason, the shift time T (see FIG. 3) based on the output signals of both the detection elements 13a and 13b can be obtained with high accuracy. In addition, the accuracy of the pitch D (center angle θ) between the detection elements 13a and 13b, which is proportional to the deviation time T, can be ensured with the accuracy of the IC manufacturing level, and can be handled as an IC package as it is. For this reason, the operation | work which adjusts the pitch D of the detection parts of a pair of detection elements 13a and 13b is also unnecessary. And the assembly | attachment operation | work of both the said detection elements 13a and 13b and the arrangement | positioning operation | work of the harness for taking out a detection signal also become easy, and the reduction of the manufacturing cost of the traveling state stabilization apparatus for vehicles can be aimed at.

  Next, FIGS. 4-6 has shown Example 2 of this invention. The vehicle running state stabilization device of this embodiment is fitted on the rotary shaft 2 by a rotational speed detection sensor 8b comprising optical detection elements 17a and 17b, each having a light emitting element 15 and a light receiving element 16. The rotation speed of the fixed encoder 7b is detected. An LED, a laser diode, or the like can be used as the light emitting element 15, and a photodiode, a phototransistor, or the like can be used as the light receiving element 16. The encoder 7b includes a plurality of through-holes 18 and 18 arranged on a single arc centered on the central axis of the rotary shaft 2 out of the light-impermeable plate material at a substantially equal pitch in the circumferential direction. Formed.

  Also in the present embodiment, the pitch D between the detection parts of both the detection elements 17a and 17b (a straight line connecting the light emitting part of the light emitting element 15 and the light receiving part of the light receiving element 16) is set to a desired value. With this configuration, from the moment when one of the detection elements 17a changes the output a based on the passage of the edge of one of the through holes 18, 18, the other detection element 17b The deviation time T up to the moment when the output b is changed based on the passage of the edge is obtained.

  However, in the case of the present embodiment, the pitch D is larger than the pitch P between the through holes 18 and 18 and more than twice this pitch due to the installation space of the detection elements 17a and 17b. It is small (2P> D> P). For this reason, the shift time T is changed from the moment when the output a of the one detection element 17a changes (rises) to the output b of the other detection element 17b after the instant of change. The time until the moment you stand up. Also in this embodiment, the pitch D is set to a non-integer multiple of 1/2 of the pitch P (D ≠ nP / 2, n = natural number), so that the rotational speed of the rotary shaft 2 is added. You can also know the direction of rotation. Other configurations and operations are the same as those of the first embodiment.

In the above example, the pitch D is 2P>D> P. However, even if the pitch D is larger than twice the pitch P (2P), the deviation time T is measured in the same manner. It is possible to calculate the rotational speed.
Further, as in this embodiment, even when the time difference from the moment when the output a changes (rises) to the moment when the other output b changes (rises) for the second time is adopted as the shift time T, It is possible to measure (calculate) the shift time T every time the output a changes by a microcomputer or a digital circuit. That is, by performing a plurality of processes in parallel at one time, the rotation speed of the rotary shaft 2 can be obtained as many times as the number of the through holes 18 and 18 while the rotary shaft 2 makes one rotation. it can.
Further, in the structures of the first and second embodiments, a case where a magnetic type or an optical type is used as a pair of detection elements is shown, but an eddy current type element is used as the detection element. Also good.

  Next, FIGS. 7 to 9 show Embodiment 3 of the present invention. In each of the first and second embodiments described above, the detection elements 13a, 13b, 17a, and 17b that constitute the rotational speed detection sensors 8a and 8b are those that change the detection signal digitally. On the other hand, in the case of the present embodiment, the detection elements 19a and 19b constituting the rotation detection sensor 8c are those that change the detection signal in an analog manner. That is, in the case of the present embodiment, as both the detection elements 19a and 19b, a permanent magnet 20 and a pole piece 21 for guiding a magnetic flux coming out of (or entering into the permanent magnet 20) from the permanent magnet 20; A passive type magnetic sensor comprising a coil 22 wound around the pole piece 21 is used. On the other hand, the encoder 7c is made of a magnetic material and has gear-like irregularities on the outer peripheral edge. The front end surface of each pole piece 21, which is the detection surface of each of the detection elements 19a and 19b, is located at two positions on the outer peripheral edge of the encoder 7c that are shifted by the center angle in the circumferential direction by θ. Closely opposed.

  In the case of the present embodiment configured as described above, when the encoder 7c rotates together with the rotating shaft 2, the output signals a and b of the detection elements 19a and 19b change sinusoidally as shown in FIG. . Then, the phase of the change of both the output signals is shifted by the shift time T corresponding to the center angle θ. The deviation time T can be obtained as a time difference between the moment when the output signal a rises after passing through 0 and the moment when the output signal b rises after passing through 0, for example. Therefore, the rotational speed N of the rotary shaft 2 can be obtained from the equation (2) based on the deviation time T thus obtained. Also in this embodiment, if the center angle θ is a non-integer multiple of 1/2 the center angle pitch related to the unevenness of the outer peripheral edge of the encoder 7c, in addition to the rotational speed N of the rotary shaft 2 The direction of rotation is required. As in this embodiment, the rotation speed is obtained by an output signal that changes in an analog manner, and an active type magnetic rotation speed detection incorporating a Hall element, a magnetoresistive element, a GMR element, etc. as a pair of detection elements. A sensor, an optical rotation speed detection sensor, or an eddy current rotation speed detection sensor can also be used. Other configurations and operations are the same as those of the first embodiment.

  Next, FIGS. 10 to 11 show Example 4 of the present invention. In the case of this embodiment, a single row deep groove type ball bearing 23 which is a kind of rolling bearing, an encoder 7a, a rotational speed detection sensor 8a provided with a pair of detection elements 13a and 13b, and a controller (not shown). Is incorporated into the vehicle running state stabilization device. The present embodiment is a structure suitable as a device for detecting the rotational speed of a wheel supported by a non-independent suspension device such as a commercial vehicle and stabilizing the traveling state of the vehicle equipped with the wheel.

  The ball bearings 23 are formed concentrically on the outer ring 24, which is a stationary ring that does not rotate, the inner ring 25, which is a rotating wheel that rotates, and the circumferential surfaces of the outer ring 24 and the inner ring 25 that face each other. A plurality of balls 28, 28, each of which is a rolling element, are provided between an outer ring raceway 26 that is a stationary side raceway surface and an inner ring raceway 27 that is a rotation side raceway surface. Of these, the encoder 7 a is fitted and fixed to the outer peripheral surface of the end of the inner ring 25, and the rotational speed detection sensor 8 a is held in a case 29 that is fitted and fixed to the end of the outer ring 24. The case 29 is formed by holding a synthetic resin holder 31 on the inner surface of a reinforcing plate 30 having an L-shaped cross section and an annular shape as a whole by bending a metal plate. The rotational speed detection sensor 8a is held in the holder 31 by molding at the time of injection molding. The structure and operation of the rotational speed detection sensor 8a, the controller, and the encoder 7a are the same as those in the first embodiment shown in FIGS.

  In the case of the present embodiment configured as described above, the rotational speed detection sensor 8a, the controller, and the encoder 7a and the ball bearing 23 constituting the rotational speed detection device are integrally combined. It can be handled. Further, it is possible to reduce the cost by reducing the size of the rotation support portion having the rotation speed detection function and facilitating assembly work. If a rolling bearing capable of supporting a large load, such as a cylindrical roller bearing or a tapered roller bearing, is used in place of the ball bearing 23, a running state stabilizing device for a large vehicle can be realized.

  Next, FIG. 12 shows Embodiment 5 of the present invention. In this embodiment, the rotational speed of a wheel supported by an independent suspension device such as a passenger car is detected, and the structure is suitable as a travel stabilization device for a vehicle equipped with the wheel. The rolling bearing unit for rotatably supporting the wheel on the suspension device is formed on the outer peripheral surface of the hub 32 which is a rotating wheel, and the double-row inner ring raceways 27a and 27a each being a rotation side raceway surface, A plurality of balls 28, 28, each of which is a rolling element, are rolled between two rows of outer ring raceways 26a, 26a, each of which is a stationary side raceway surface, formed on the inner peripheral surface of the outer race 24a. It is provided freely. The hub 32 is formed by fitting an inner ring 25 a to the end of the hub body 33. Since the illustrated example is a rolling bearing unit for driving wheels, a spline shaft 36 attached to a constant velocity joint 35 is inserted into a spline hole 34 provided in the center of the hub body 33.

  In order to carry out the present invention using the rolling bearing unit as described above, in this embodiment, the encoder 7a is fitted and fixed to the outer peripheral surface of the end of the inner ring 25a, and the end of the outer ring 24a is fixed. The rotation speed detection sensor 8a is held in a case 29a that is externally fitted and fixed to the case 29a. The case 29a is formed in an annular shape by bending a metal plate, and only the portion holding the rotational speed detection sensor 8a is inflated in the axial direction, and the portion is used as a holding portion 37. . The semiconductor wafer substrate on which the pair of detection elements 13a and 13b (see FIG. 2), each of which constitutes the rotational speed detection sensor 8a and is a Hall element, is made of a synthetic resin held in the holding portion 37. It is held in the holder 31a by molding at the time of injection molding. The structure and operation of the rotational speed detection sensor 8a and the encoder 7a are the same as those in the first example shown in FIGS. In addition, since the rotational speed detection sensor 8a and the encoder 7a and the rolling bearing unit can be handled as an integrated part, the cost can be reduced by facilitating the assembly work. It is the same.

  When the present invention is carried out by using a rolling bearing unit for supporting a wheel on an independent suspension device, it is not limited to the above-described rolling bearing unit for driving wheels as shown in FIG. As in the embodiment described above, a rolling bearing unit for a driven wheel that does not have a spline hole in the center of the hub body 33a can also be used. Of course, it can also be implemented using a rolling bearing unit for a driven wheel of the outer ring rotating type. Furthermore, even when applied to a rolling bearing unit for driving wheels, the present invention is not limited to the structure shown in FIG. 12, but can be applied to various structures such as the structure shown in FIG. In the case of the structure shown in FIG. 14, the inner ring 25 a that is externally fitted to the inner end portion of the hub main body 33 is suppressed by a caulking portion 38 formed at the inner end portion of the hub main body 33. 13 and 14, the sensor unit 39 including a pair of detection elements is arranged in the axial direction (FIG. 13) or radial direction (FIG. 14) of the encoders 7a and 7.

Sectional drawing which shows Example 1 of this invention. The figure seen from the right side of FIG. The diagram which shows the detection signal of a pair of detection element, and the output signal which processed these both detection signals. Sectional drawing which shows Example 2 of this invention. The figure seen from the right side of FIG. The diagram which shows the detection signal of a pair of detection element. Sectional drawing which shows Example 3 of this invention. The figure seen from the side of FIG. The diagram which shows the detection signal of a pair of detection element. Sectional drawing which shows Example 4 of this invention. The figure seen from the right side of FIG. Sectional drawing which shows Example 5 of this invention. Sectional drawing which shows the same Example 6. FIG. Sectional drawing which shows the same Example 7. FIG. The fragmentary sectional view which shows one example of the conventional structure. Viewed from the right side of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2 Rotating shaft 3 Bearing 4 Space 5 Combination seal ring 6 Slinger 7, 7a, 7b, 7c Encoder 8, 8a, 8b, 8c, 8d Rotational speed detection sensor 9 Controller 10 Support ring 11 Permanent magnet 12 Cylindrical part 13a, 13b Detection element 14 Wafer substrate 15 Light emitting element 16 Light receiving element 17a, 17b Detection element 18 Through hole 19a, 19b Detection element 20 Permanent magnet 21 Pole piece 22 Coil 23 Ball bearing 24, 24a Outer ring 25, 25a Inner ring 26, 26a Outer ring raceway 27 27a Inner ring raceway 28 Ball 29, 29a Case 30 Reinforcing plate 31, 31a Holder 32 Hub 33, 33a Hub body 34 Spline hole 35 Constant velocity joint 36 Spline shaft 37 Holding part 38 Caulking part 39 Sensor unit

Claims (5)

A vehicle running state stabilization device comprising the following (a) to (c).
(a) An encoder that is provided concentrically with a rotating member that rotates together with the wheel, and in which characteristics of the detected surface are alternately changed in the circumferential direction.
(b) A rotational speed supported by a fixed member provided in the vicinity of the rotating member, with a pair of detecting portions facing each of the detection surfaces provided in a state of being separated in the circumferential direction of the encoder Detection sensor.
(c) The moment when the boundary portion of the encoder on which the characteristic is changed passes the position immediately before one of the pair of detection units, and the position immediately before the other detection unit. A time difference data processing unit that obtains a time difference from the moment of passing through each boundary portion where the direction of characteristic change coincides, and fluctuations in time difference data at each boundary portion due to wheel speed fluctuations A controller having a traveling control unit that issues a command signal for performing control for stabilizing the traveling according to the control.   The vehicular running state stabilization device according to claim 1, wherein a pitch of the pair of detection units provided in the rotation speed detection sensor is less than a minimum pitch among the pitches of the characteristic change of the detected surface of the encoder.   The traveling state stabilization device for a vehicle according to any one of claims 1 to 2, wherein a difference in pitch of characteristic changes of a surface to be detected of the encoder is within ± 2%.   The vehicle running state stabilization device according to any one of claims 1 to 3, wherein the number of pitches of the characteristic change of the detected surface of the encoder is 50 to 100.   Rotation direction determination process in which the controller determines the rotation direction of the encoder based on before and after the moment when the boundary portion passes the position immediately before the one detection portion and the moment when the boundary portion passes the position immediately before the other detection portion. The traveling state stabilization device according to any one of claims 1 to 4, further comprising a section.

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